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/sched/clock.h>
32 #include <linux/sched/task.h>
33 #include <linux/sched/mm.h>
34 #include <linux/delay.h>
35 #include <linux/module.h>
36 #include <linux/proc_fs.h>
37 #include <linux/seq_file.h>
38 #include <linux/spinlock.h>
39 #include <linux/kallsyms.h>
40 #include <linux/interrupt.h>
41 #include <linux/stacktrace.h>
42 #include <linux/debug_locks.h>
43 #include <linux/irqflags.h>
44 #include <linux/utsname.h>
45 #include <linux/hash.h>
46 #include <linux/ftrace.h>
47 #include <linux/stringify.h>
48 #include <linux/bitops.h>
49 #include <linux/gfp.h>
50 #include <linux/random.h>
51 #include <linux/jhash.h>
52 #include <linux/nmi.h>
54 #include <asm/sections.h>
56 #include "lockdep_internals.h"
58 #define CREATE_TRACE_POINTS
59 #include <trace/events/lock.h>
61 #ifdef CONFIG_PROVE_LOCKING
62 int prove_locking = 1;
63 module_param(prove_locking, int, 0644);
65 #define prove_locking 0
68 #ifdef CONFIG_LOCK_STAT
70 module_param(lock_stat, int, 0644);
76 * lockdep_lock: protects the lockdep graph, the hashes and the
77 * class/list/hash allocators.
79 * This is one of the rare exceptions where it's justified
80 * to use a raw spinlock - we really dont want the spinlock
81 * code to recurse back into the lockdep code...
83 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
85 static int graph_lock(void)
87 arch_spin_lock(&lockdep_lock);
89 * Make sure that if another CPU detected a bug while
90 * walking the graph we dont change it (while the other
91 * CPU is busy printing out stuff with the graph lock
95 arch_spin_unlock(&lockdep_lock);
98 /* prevent any recursions within lockdep from causing deadlocks */
99 current->lockdep_recursion++;
103 static inline int graph_unlock(void)
105 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
107 * The lockdep graph lock isn't locked while we expect it to
108 * be, we're confused now, bye!
110 return DEBUG_LOCKS_WARN_ON(1);
113 current->lockdep_recursion--;
114 arch_spin_unlock(&lockdep_lock);
119 * Turn lock debugging off and return with 0 if it was off already,
120 * and also release the graph lock:
122 static inline int debug_locks_off_graph_unlock(void)
124 int ret = debug_locks_off();
126 arch_spin_unlock(&lockdep_lock);
131 unsigned long nr_list_entries;
132 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
135 * All data structures here are protected by the global debug_lock.
137 * Mutex key structs only get allocated, once during bootup, and never
138 * get freed - this significantly simplifies the debugging code.
140 unsigned long nr_lock_classes;
141 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
143 static inline struct lock_class *hlock_class(struct held_lock *hlock)
145 if (!hlock->class_idx) {
147 * Someone passed in garbage, we give up.
149 DEBUG_LOCKS_WARN_ON(1);
152 return lock_classes + hlock->class_idx - 1;
155 #ifdef CONFIG_LOCK_STAT
156 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
158 static inline u64 lockstat_clock(void)
160 return local_clock();
163 static int lock_point(unsigned long points[], unsigned long ip)
167 for (i = 0; i < LOCKSTAT_POINTS; i++) {
168 if (points[i] == 0) {
179 static void lock_time_inc(struct lock_time *lt, u64 time)
184 if (time < lt->min || !lt->nr)
191 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
196 if (src->max > dst->max)
199 if (src->min < dst->min || !dst->nr)
202 dst->total += src->total;
206 struct lock_class_stats lock_stats(struct lock_class *class)
208 struct lock_class_stats stats;
211 memset(&stats, 0, sizeof(struct lock_class_stats));
212 for_each_possible_cpu(cpu) {
213 struct lock_class_stats *pcs =
214 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
216 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
217 stats.contention_point[i] += pcs->contention_point[i];
219 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
220 stats.contending_point[i] += pcs->contending_point[i];
222 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
223 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
225 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
226 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
228 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
229 stats.bounces[i] += pcs->bounces[i];
235 void clear_lock_stats(struct lock_class *class)
239 for_each_possible_cpu(cpu) {
240 struct lock_class_stats *cpu_stats =
241 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
243 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
245 memset(class->contention_point, 0, sizeof(class->contention_point));
246 memset(class->contending_point, 0, sizeof(class->contending_point));
249 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
251 return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes];
254 static void lock_release_holdtime(struct held_lock *hlock)
256 struct lock_class_stats *stats;
262 holdtime = lockstat_clock() - hlock->holdtime_stamp;
264 stats = get_lock_stats(hlock_class(hlock));
266 lock_time_inc(&stats->read_holdtime, holdtime);
268 lock_time_inc(&stats->write_holdtime, holdtime);
271 static inline void lock_release_holdtime(struct held_lock *hlock)
277 * We keep a global list of all lock classes. The list only grows,
278 * never shrinks. The list is only accessed with the lockdep
279 * spinlock lock held.
281 LIST_HEAD(all_lock_classes);
284 * The lockdep classes are in a hash-table as well, for fast lookup:
286 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
287 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
288 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
289 #define classhashentry(key) (classhash_table + __classhashfn((key)))
291 static struct hlist_head classhash_table[CLASSHASH_SIZE];
294 * We put the lock dependency chains into a hash-table as well, to cache
297 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
298 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
299 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
300 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
302 static struct hlist_head chainhash_table[CHAINHASH_SIZE];
305 * The hash key of the lock dependency chains is a hash itself too:
306 * it's a hash of all locks taken up to that lock, including that lock.
307 * It's a 64-bit hash, because it's important for the keys to be
310 static inline u64 iterate_chain_key(u64 key, u32 idx)
312 u32 k0 = key, k1 = key >> 32;
314 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
316 return k0 | (u64)k1 << 32;
319 void lockdep_off(void)
321 current->lockdep_recursion++;
323 EXPORT_SYMBOL(lockdep_off);
325 void lockdep_on(void)
327 current->lockdep_recursion--;
329 EXPORT_SYMBOL(lockdep_on);
332 * Debugging switches:
336 #define VERY_VERBOSE 0
339 # define HARDIRQ_VERBOSE 1
340 # define SOFTIRQ_VERBOSE 1
342 # define HARDIRQ_VERBOSE 0
343 # define SOFTIRQ_VERBOSE 0
346 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_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);
504 printk(KERN_CONT "%s", name);
506 printk(KERN_CONT "%s", name);
507 if (class->name_version > 1)
508 printk(KERN_CONT "#%d", class->name_version);
510 printk(KERN_CONT "/%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);
520 printk(KERN_CONT " (");
521 __print_lock_name(class);
522 printk(KERN_CONT "){%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);
534 printk(KERN_CONT "%s", name);
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(KERN_CONT "<RELEASED>\n");
553 printk(KERN_CONT "%p", hlock->instance);
554 print_lock_name(lock_classes + class_idx - 1);
555 printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
558 static void lockdep_print_held_locks(struct task_struct *p)
560 int i, depth = READ_ONCE(p->lockdep_depth);
563 printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p));
565 printk("%d lock%s held by %s/%d:\n", depth,
566 depth > 1 ? "s" : "", p->comm, task_pid_nr(p));
568 * It's not reliable to print a task's held locks if it's not sleeping
569 * and it's not the current task.
571 if (p->state == TASK_RUNNING && p != current)
573 for (i = 0; i < depth; i++) {
575 print_lock(p->held_locks + i);
579 static void print_kernel_ident(void)
581 printk("%s %.*s %s\n", init_utsname()->release,
582 (int)strcspn(init_utsname()->version, " "),
583 init_utsname()->version,
587 static int very_verbose(struct lock_class *class)
590 return class_filter(class);
596 * Is this the address of a static object:
599 static int static_obj(void *obj)
601 unsigned long start = (unsigned long) &_stext,
602 end = (unsigned long) &_end,
603 addr = (unsigned long) obj;
608 if ((addr >= start) && (addr < end))
611 if (arch_is_kernel_data(addr))
615 * in-kernel percpu var?
617 if (is_kernel_percpu_address(addr))
621 * module static or percpu var?
623 return is_module_address(addr) || is_module_percpu_address(addr);
628 * To make lock name printouts unique, we calculate a unique
629 * class->name_version generation counter:
631 static int count_matching_names(struct lock_class *new_class)
633 struct lock_class *class;
636 if (!new_class->name)
639 list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
640 if (new_class->key - new_class->subclass == class->key)
641 return class->name_version;
642 if (class->name && !strcmp(class->name, new_class->name))
643 count = max(count, class->name_version);
649 static inline struct lock_class *
650 look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
652 struct lockdep_subclass_key *key;
653 struct hlist_head *hash_head;
654 struct lock_class *class;
656 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
659 "BUG: looking up invalid subclass: %u\n", subclass);
661 "turning off the locking correctness validator.\n");
667 * If it is not initialised then it has never been locked,
668 * so it won't be present in the hash table.
670 if (unlikely(!lock->key))
674 * NOTE: the class-key must be unique. For dynamic locks, a static
675 * lock_class_key variable is passed in through the mutex_init()
676 * (or spin_lock_init()) call - which acts as the key. For static
677 * locks we use the lock object itself as the key.
679 BUILD_BUG_ON(sizeof(struct lock_class_key) >
680 sizeof(struct lockdep_map));
682 key = lock->key->subkeys + subclass;
684 hash_head = classhashentry(key);
687 * We do an RCU walk of the hash, see lockdep_free_key_range().
689 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
692 hlist_for_each_entry_rcu_notrace(class, hash_head, hash_entry) {
693 if (class->key == key) {
695 * Huh! same key, different name? Did someone trample
696 * on some memory? We're most confused.
698 WARN_ON_ONCE(class->name != lock->name);
707 * Static locks do not have their class-keys yet - for them the key is
708 * the lock object itself. If the lock is in the per cpu area, the
709 * canonical address of the lock (per cpu offset removed) is used.
711 static bool assign_lock_key(struct lockdep_map *lock)
713 unsigned long can_addr, addr = (unsigned long)lock;
715 if (__is_kernel_percpu_address(addr, &can_addr))
716 lock->key = (void *)can_addr;
717 else if (__is_module_percpu_address(addr, &can_addr))
718 lock->key = (void *)can_addr;
719 else if (static_obj(lock))
720 lock->key = (void *)lock;
722 /* Debug-check: all keys must be persistent! */
724 pr_err("INFO: trying to register non-static key.\n");
725 pr_err("The code is fine but needs lockdep annotation, or maybe\n");
726 pr_err("you didn't initialize this object before use?\n");
727 pr_err("turning off the locking correctness validator.\n");
736 * Register a lock's class in the hash-table, if the class is not present
737 * yet. Otherwise we look it up. We cache the result in the lock object
738 * itself, so actual lookup of the hash should be once per lock object.
740 static struct lock_class *
741 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
743 struct lockdep_subclass_key *key;
744 struct hlist_head *hash_head;
745 struct lock_class *class;
747 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
749 class = look_up_lock_class(lock, subclass);
751 goto out_set_class_cache;
754 if (!assign_lock_key(lock))
756 } else if (!static_obj(lock->key)) {
760 key = lock->key->subkeys + subclass;
761 hash_head = classhashentry(key);
767 * We have to do the hash-walk again, to avoid races
770 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
771 if (class->key == key)
776 * Allocate a new key from the static array, and add it to
779 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
780 if (!debug_locks_off_graph_unlock()) {
784 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
788 class = lock_classes + nr_lock_classes++;
789 debug_atomic_inc(nr_unused_locks);
791 class->name = lock->name;
792 class->subclass = subclass;
793 INIT_LIST_HEAD(&class->lock_entry);
794 INIT_LIST_HEAD(&class->locks_before);
795 INIT_LIST_HEAD(&class->locks_after);
796 class->name_version = count_matching_names(class);
798 * We use RCU's safe list-add method to make
799 * parallel walking of the hash-list safe:
801 hlist_add_head_rcu(&class->hash_entry, hash_head);
803 * Add it to the global list of classes:
805 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
807 if (verbose(class)) {
810 printk("\nnew class %px: %s", class->key, class->name);
811 if (class->name_version > 1)
812 printk(KERN_CONT "#%d", class->name_version);
813 printk(KERN_CONT "\n");
824 if (!subclass || force)
825 lock->class_cache[0] = class;
826 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
827 lock->class_cache[subclass] = class;
830 * Hash collision, did we smoke some? We found a class with a matching
831 * hash but the subclass -- which is hashed in -- didn't match.
833 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
839 #ifdef CONFIG_PROVE_LOCKING
841 * Allocate a lockdep entry. (assumes the graph_lock held, returns
842 * with NULL on failure)
844 static struct lock_list *alloc_list_entry(void)
846 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
847 if (!debug_locks_off_graph_unlock())
850 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
854 return list_entries + nr_list_entries++;
858 * Add a new dependency to the head of the list:
860 static int add_lock_to_list(struct lock_class *this, struct list_head *head,
861 unsigned long ip, int distance,
862 struct stack_trace *trace)
864 struct lock_list *entry;
866 * Lock not present yet - get a new dependency struct and
867 * add it to the list:
869 entry = alloc_list_entry();
874 entry->distance = distance;
875 entry->trace = *trace;
877 * Both allocation and removal are done under the graph lock; but
878 * iteration is under RCU-sched; see look_up_lock_class() and
879 * lockdep_free_key_range().
881 list_add_tail_rcu(&entry->entry, head);
887 * For good efficiency of modular, we use power of 2
889 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
890 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
893 * The circular_queue and helpers is used to implement the
894 * breadth-first search(BFS)algorithem, by which we can build
895 * the shortest path from the next lock to be acquired to the
896 * previous held lock if there is a circular between them.
898 struct circular_queue {
899 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
900 unsigned int front, rear;
903 static struct circular_queue lock_cq;
905 unsigned int max_bfs_queue_depth;
907 static unsigned int lockdep_dependency_gen_id;
909 static inline void __cq_init(struct circular_queue *cq)
911 cq->front = cq->rear = 0;
912 lockdep_dependency_gen_id++;
915 static inline int __cq_empty(struct circular_queue *cq)
917 return (cq->front == cq->rear);
920 static inline int __cq_full(struct circular_queue *cq)
922 return ((cq->rear + 1) & CQ_MASK) == cq->front;
925 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
930 cq->element[cq->rear] = elem;
931 cq->rear = (cq->rear + 1) & CQ_MASK;
935 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
940 *elem = cq->element[cq->front];
941 cq->front = (cq->front + 1) & CQ_MASK;
945 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
947 return (cq->rear - cq->front) & CQ_MASK;
950 static inline void mark_lock_accessed(struct lock_list *lock,
951 struct lock_list *parent)
955 nr = lock - list_entries;
956 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
957 lock->parent = parent;
958 lock->class->dep_gen_id = lockdep_dependency_gen_id;
961 static inline unsigned long lock_accessed(struct lock_list *lock)
965 nr = lock - list_entries;
966 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
967 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
970 static inline struct lock_list *get_lock_parent(struct lock_list *child)
972 return child->parent;
975 static inline int get_lock_depth(struct lock_list *child)
978 struct lock_list *parent;
980 while ((parent = get_lock_parent(child))) {
987 static int __bfs(struct lock_list *source_entry,
989 int (*match)(struct lock_list *entry, void *data),
990 struct lock_list **target_entry,
993 struct lock_list *entry;
994 struct list_head *head;
995 struct circular_queue *cq = &lock_cq;
998 if (match(source_entry, data)) {
999 *target_entry = source_entry;
1005 head = &source_entry->class->locks_after;
1007 head = &source_entry->class->locks_before;
1009 if (list_empty(head))
1013 __cq_enqueue(cq, (unsigned long)source_entry);
1015 while (!__cq_empty(cq)) {
1016 struct lock_list *lock;
1018 __cq_dequeue(cq, (unsigned long *)&lock);
1026 head = &lock->class->locks_after;
1028 head = &lock->class->locks_before;
1030 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1032 list_for_each_entry_rcu(entry, head, entry) {
1033 if (!lock_accessed(entry)) {
1034 unsigned int cq_depth;
1035 mark_lock_accessed(entry, lock);
1036 if (match(entry, data)) {
1037 *target_entry = entry;
1042 if (__cq_enqueue(cq, (unsigned long)entry)) {
1046 cq_depth = __cq_get_elem_count(cq);
1047 if (max_bfs_queue_depth < cq_depth)
1048 max_bfs_queue_depth = cq_depth;
1056 static inline int __bfs_forwards(struct lock_list *src_entry,
1058 int (*match)(struct lock_list *entry, void *data),
1059 struct lock_list **target_entry)
1061 return __bfs(src_entry, data, match, target_entry, 1);
1065 static inline int __bfs_backwards(struct lock_list *src_entry,
1067 int (*match)(struct lock_list *entry, void *data),
1068 struct lock_list **target_entry)
1070 return __bfs(src_entry, data, match, target_entry, 0);
1075 * Recursive, forwards-direction lock-dependency checking, used for
1076 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1081 * Print a dependency chain entry (this is only done when a deadlock
1082 * has been detected):
1085 print_circular_bug_entry(struct lock_list *target, int depth)
1087 if (debug_locks_silent)
1089 printk("\n-> #%u", depth);
1090 print_lock_name(target->class);
1091 printk(KERN_CONT ":\n");
1092 print_stack_trace(&target->trace, 6);
1098 print_circular_lock_scenario(struct held_lock *src,
1099 struct held_lock *tgt,
1100 struct lock_list *prt)
1102 struct lock_class *source = hlock_class(src);
1103 struct lock_class *target = hlock_class(tgt);
1104 struct lock_class *parent = prt->class;
1107 * A direct locking problem where unsafe_class lock is taken
1108 * directly by safe_class lock, then all we need to show
1109 * is the deadlock scenario, as it is obvious that the
1110 * unsafe lock is taken under the safe lock.
1112 * But if there is a chain instead, where the safe lock takes
1113 * an intermediate lock (middle_class) where this lock is
1114 * not the same as the safe lock, then the lock chain is
1115 * used to describe the problem. Otherwise we would need
1116 * to show a different CPU case for each link in the chain
1117 * from the safe_class lock to the unsafe_class lock.
1119 if (parent != source) {
1120 printk("Chain exists of:\n ");
1121 __print_lock_name(source);
1122 printk(KERN_CONT " --> ");
1123 __print_lock_name(parent);
1124 printk(KERN_CONT " --> ");
1125 __print_lock_name(target);
1126 printk(KERN_CONT "\n\n");
1129 printk(" Possible unsafe locking scenario:\n\n");
1130 printk(" CPU0 CPU1\n");
1131 printk(" ---- ----\n");
1133 __print_lock_name(target);
1134 printk(KERN_CONT ");\n");
1136 __print_lock_name(parent);
1137 printk(KERN_CONT ");\n");
1139 __print_lock_name(target);
1140 printk(KERN_CONT ");\n");
1142 __print_lock_name(source);
1143 printk(KERN_CONT ");\n");
1144 printk("\n *** DEADLOCK ***\n\n");
1148 * When a circular dependency is detected, print the
1152 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1153 struct held_lock *check_src,
1154 struct held_lock *check_tgt)
1156 struct task_struct *curr = current;
1158 if (debug_locks_silent)
1162 pr_warn("======================================================\n");
1163 pr_warn("WARNING: possible circular locking dependency detected\n");
1164 print_kernel_ident();
1165 pr_warn("------------------------------------------------------\n");
1166 pr_warn("%s/%d is trying to acquire lock:\n",
1167 curr->comm, task_pid_nr(curr));
1168 print_lock(check_src);
1170 pr_warn("\nbut task is already holding lock:\n");
1172 print_lock(check_tgt);
1173 pr_warn("\nwhich lock already depends on the new lock.\n\n");
1174 pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1176 print_circular_bug_entry(entry, depth);
1181 static inline int class_equal(struct lock_list *entry, void *data)
1183 return entry->class == data;
1186 static noinline int print_circular_bug(struct lock_list *this,
1187 struct lock_list *target,
1188 struct held_lock *check_src,
1189 struct held_lock *check_tgt,
1190 struct stack_trace *trace)
1192 struct task_struct *curr = current;
1193 struct lock_list *parent;
1194 struct lock_list *first_parent;
1197 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1200 if (!save_trace(&this->trace))
1203 depth = get_lock_depth(target);
1205 print_circular_bug_header(target, depth, check_src, check_tgt);
1207 parent = get_lock_parent(target);
1208 first_parent = parent;
1211 print_circular_bug_entry(parent, --depth);
1212 parent = get_lock_parent(parent);
1215 printk("\nother info that might help us debug this:\n\n");
1216 print_circular_lock_scenario(check_src, check_tgt,
1219 lockdep_print_held_locks(curr);
1221 printk("\nstack backtrace:\n");
1227 static noinline int print_bfs_bug(int ret)
1229 if (!debug_locks_off_graph_unlock())
1233 * Breadth-first-search failed, graph got corrupted?
1235 WARN(1, "lockdep bfs error:%d\n", ret);
1240 static int noop_count(struct lock_list *entry, void *data)
1242 (*(unsigned long *)data)++;
1246 static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1248 unsigned long count = 0;
1249 struct lock_list *uninitialized_var(target_entry);
1251 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1255 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1257 unsigned long ret, flags;
1258 struct lock_list this;
1263 raw_local_irq_save(flags);
1264 current->lockdep_recursion = 1;
1265 arch_spin_lock(&lockdep_lock);
1266 ret = __lockdep_count_forward_deps(&this);
1267 arch_spin_unlock(&lockdep_lock);
1268 current->lockdep_recursion = 0;
1269 raw_local_irq_restore(flags);
1274 static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1276 unsigned long count = 0;
1277 struct lock_list *uninitialized_var(target_entry);
1279 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1284 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1286 unsigned long ret, flags;
1287 struct lock_list this;
1292 raw_local_irq_save(flags);
1293 current->lockdep_recursion = 1;
1294 arch_spin_lock(&lockdep_lock);
1295 ret = __lockdep_count_backward_deps(&this);
1296 arch_spin_unlock(&lockdep_lock);
1297 current->lockdep_recursion = 0;
1298 raw_local_irq_restore(flags);
1304 * Prove that the dependency graph starting at <entry> can not
1305 * lead to <target>. Print an error and return 0 if it does.
1308 check_noncircular(struct lock_list *root, struct lock_class *target,
1309 struct lock_list **target_entry)
1313 debug_atomic_inc(nr_cyclic_checks);
1315 result = __bfs_forwards(root, target, class_equal, target_entry);
1321 check_redundant(struct lock_list *root, struct lock_class *target,
1322 struct lock_list **target_entry)
1326 debug_atomic_inc(nr_redundant_checks);
1328 result = __bfs_forwards(root, target, class_equal, target_entry);
1333 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1335 * Forwards and backwards subgraph searching, for the purposes of
1336 * proving that two subgraphs can be connected by a new dependency
1337 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1340 static inline int usage_match(struct lock_list *entry, void *bit)
1342 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1348 * Find a node in the forwards-direction dependency sub-graph starting
1349 * at @root->class that matches @bit.
1351 * Return 0 if such a node exists in the subgraph, and put that node
1352 * into *@target_entry.
1354 * Return 1 otherwise and keep *@target_entry unchanged.
1355 * Return <0 on error.
1358 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1359 struct lock_list **target_entry)
1363 debug_atomic_inc(nr_find_usage_forwards_checks);
1365 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1371 * Find a node in the backwards-direction dependency sub-graph starting
1372 * at @root->class that matches @bit.
1374 * Return 0 if such a node exists in the subgraph, and put that node
1375 * into *@target_entry.
1377 * Return 1 otherwise and keep *@target_entry unchanged.
1378 * Return <0 on error.
1381 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1382 struct lock_list **target_entry)
1386 debug_atomic_inc(nr_find_usage_backwards_checks);
1388 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1393 static void print_lock_class_header(struct lock_class *class, int depth)
1397 printk("%*s->", depth, "");
1398 print_lock_name(class);
1399 printk(KERN_CONT " ops: %lu", class->ops);
1400 printk(KERN_CONT " {\n");
1402 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1403 if (class->usage_mask & (1 << bit)) {
1406 len += printk("%*s %s", depth, "", usage_str[bit]);
1407 len += printk(KERN_CONT " at:\n");
1408 print_stack_trace(class->usage_traces + bit, len);
1411 printk("%*s }\n", depth, "");
1413 printk("%*s ... key at: [<%px>] %pS\n",
1414 depth, "", class->key, class->key);
1418 * printk the shortest lock dependencies from @start to @end in reverse order:
1421 print_shortest_lock_dependencies(struct lock_list *leaf,
1422 struct lock_list *root)
1424 struct lock_list *entry = leaf;
1427 /*compute depth from generated tree by BFS*/
1428 depth = get_lock_depth(leaf);
1431 print_lock_class_header(entry->class, depth);
1432 printk("%*s ... acquired at:\n", depth, "");
1433 print_stack_trace(&entry->trace, 2);
1436 if (depth == 0 && (entry != root)) {
1437 printk("lockdep:%s bad path found in chain graph\n", __func__);
1441 entry = get_lock_parent(entry);
1443 } while (entry && (depth >= 0));
1449 print_irq_lock_scenario(struct lock_list *safe_entry,
1450 struct lock_list *unsafe_entry,
1451 struct lock_class *prev_class,
1452 struct lock_class *next_class)
1454 struct lock_class *safe_class = safe_entry->class;
1455 struct lock_class *unsafe_class = unsafe_entry->class;
1456 struct lock_class *middle_class = prev_class;
1458 if (middle_class == safe_class)
1459 middle_class = next_class;
1462 * A direct locking problem where unsafe_class lock is taken
1463 * directly by safe_class lock, then all we need to show
1464 * is the deadlock scenario, as it is obvious that the
1465 * unsafe lock is taken under the safe lock.
1467 * But if there is a chain instead, where the safe lock takes
1468 * an intermediate lock (middle_class) where this lock is
1469 * not the same as the safe lock, then the lock chain is
1470 * used to describe the problem. Otherwise we would need
1471 * to show a different CPU case for each link in the chain
1472 * from the safe_class lock to the unsafe_class lock.
1474 if (middle_class != unsafe_class) {
1475 printk("Chain exists of:\n ");
1476 __print_lock_name(safe_class);
1477 printk(KERN_CONT " --> ");
1478 __print_lock_name(middle_class);
1479 printk(KERN_CONT " --> ");
1480 __print_lock_name(unsafe_class);
1481 printk(KERN_CONT "\n\n");
1484 printk(" Possible interrupt unsafe locking scenario:\n\n");
1485 printk(" CPU0 CPU1\n");
1486 printk(" ---- ----\n");
1488 __print_lock_name(unsafe_class);
1489 printk(KERN_CONT ");\n");
1490 printk(" local_irq_disable();\n");
1492 __print_lock_name(safe_class);
1493 printk(KERN_CONT ");\n");
1495 __print_lock_name(middle_class);
1496 printk(KERN_CONT ");\n");
1497 printk(" <Interrupt>\n");
1499 __print_lock_name(safe_class);
1500 printk(KERN_CONT ");\n");
1501 printk("\n *** DEADLOCK ***\n\n");
1505 print_bad_irq_dependency(struct task_struct *curr,
1506 struct lock_list *prev_root,
1507 struct lock_list *next_root,
1508 struct lock_list *backwards_entry,
1509 struct lock_list *forwards_entry,
1510 struct held_lock *prev,
1511 struct held_lock *next,
1512 enum lock_usage_bit bit1,
1513 enum lock_usage_bit bit2,
1514 const char *irqclass)
1516 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1520 pr_warn("=====================================================\n");
1521 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
1522 irqclass, irqclass);
1523 print_kernel_ident();
1524 pr_warn("-----------------------------------------------------\n");
1525 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1526 curr->comm, task_pid_nr(curr),
1527 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1528 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1529 curr->hardirqs_enabled,
1530 curr->softirqs_enabled);
1533 pr_warn("\nand this task is already holding:\n");
1535 pr_warn("which would create a new lock dependency:\n");
1536 print_lock_name(hlock_class(prev));
1538 print_lock_name(hlock_class(next));
1541 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
1543 print_lock_name(backwards_entry->class);
1544 pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
1546 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1548 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
1549 print_lock_name(forwards_entry->class);
1550 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
1553 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1555 pr_warn("\nother info that might help us debug this:\n\n");
1556 print_irq_lock_scenario(backwards_entry, forwards_entry,
1557 hlock_class(prev), hlock_class(next));
1559 lockdep_print_held_locks(curr);
1561 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
1562 if (!save_trace(&prev_root->trace))
1564 print_shortest_lock_dependencies(backwards_entry, prev_root);
1566 pr_warn("\nthe dependencies between the lock to be acquired");
1567 pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
1568 if (!save_trace(&next_root->trace))
1570 print_shortest_lock_dependencies(forwards_entry, next_root);
1572 pr_warn("\nstack backtrace:\n");
1579 check_usage(struct task_struct *curr, struct held_lock *prev,
1580 struct held_lock *next, enum lock_usage_bit bit_backwards,
1581 enum lock_usage_bit bit_forwards, const char *irqclass)
1584 struct lock_list this, that;
1585 struct lock_list *uninitialized_var(target_entry);
1586 struct lock_list *uninitialized_var(target_entry1);
1590 this.class = hlock_class(prev);
1591 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1593 return print_bfs_bug(ret);
1598 that.class = hlock_class(next);
1599 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1601 return print_bfs_bug(ret);
1605 return print_bad_irq_dependency(curr, &this, &that,
1606 target_entry, target_entry1,
1608 bit_backwards, bit_forwards, irqclass);
1611 static const char *state_names[] = {
1612 #define LOCKDEP_STATE(__STATE) \
1613 __stringify(__STATE),
1614 #include "lockdep_states.h"
1615 #undef LOCKDEP_STATE
1618 static const char *state_rnames[] = {
1619 #define LOCKDEP_STATE(__STATE) \
1620 __stringify(__STATE)"-READ",
1621 #include "lockdep_states.h"
1622 #undef LOCKDEP_STATE
1625 static inline const char *state_name(enum lock_usage_bit bit)
1627 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1630 static int exclusive_bit(int new_bit)
1638 * bit 0 - write/read
1639 * bit 1 - used_in/enabled
1643 int state = new_bit & ~3;
1644 int dir = new_bit & 2;
1647 * keep state, bit flip the direction and strip read.
1649 return state | (dir ^ 2);
1652 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1653 struct held_lock *next, enum lock_usage_bit bit)
1656 * Prove that the new dependency does not connect a hardirq-safe
1657 * lock with a hardirq-unsafe lock - to achieve this we search
1658 * the backwards-subgraph starting at <prev>, and the
1659 * forwards-subgraph starting at <next>:
1661 if (!check_usage(curr, prev, next, bit,
1662 exclusive_bit(bit), state_name(bit)))
1668 * Prove that the new dependency does not connect a hardirq-safe-read
1669 * lock with a hardirq-unsafe lock - to achieve this we search
1670 * the backwards-subgraph starting at <prev>, and the
1671 * forwards-subgraph starting at <next>:
1673 if (!check_usage(curr, prev, next, bit,
1674 exclusive_bit(bit), state_name(bit)))
1681 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1682 struct held_lock *next)
1684 #define LOCKDEP_STATE(__STATE) \
1685 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1687 #include "lockdep_states.h"
1688 #undef LOCKDEP_STATE
1693 static void inc_chains(void)
1695 if (current->hardirq_context)
1696 nr_hardirq_chains++;
1698 if (current->softirq_context)
1699 nr_softirq_chains++;
1701 nr_process_chains++;
1708 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1709 struct held_lock *next)
1714 static inline void inc_chains(void)
1716 nr_process_chains++;
1722 print_deadlock_scenario(struct held_lock *nxt,
1723 struct held_lock *prv)
1725 struct lock_class *next = hlock_class(nxt);
1726 struct lock_class *prev = hlock_class(prv);
1728 printk(" Possible unsafe locking scenario:\n\n");
1732 __print_lock_name(prev);
1733 printk(KERN_CONT ");\n");
1735 __print_lock_name(next);
1736 printk(KERN_CONT ");\n");
1737 printk("\n *** DEADLOCK ***\n\n");
1738 printk(" May be due to missing lock nesting notation\n\n");
1742 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1743 struct held_lock *next)
1745 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1749 pr_warn("============================================\n");
1750 pr_warn("WARNING: possible recursive locking detected\n");
1751 print_kernel_ident();
1752 pr_warn("--------------------------------------------\n");
1753 pr_warn("%s/%d is trying to acquire lock:\n",
1754 curr->comm, task_pid_nr(curr));
1756 pr_warn("\nbut task is already holding lock:\n");
1759 pr_warn("\nother info that might help us debug this:\n");
1760 print_deadlock_scenario(next, prev);
1761 lockdep_print_held_locks(curr);
1763 pr_warn("\nstack backtrace:\n");
1770 * Check whether we are holding such a class already.
1772 * (Note that this has to be done separately, because the graph cannot
1773 * detect such classes of deadlocks.)
1775 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1778 check_deadlock(struct task_struct *curr, struct held_lock *next,
1779 struct lockdep_map *next_instance, int read)
1781 struct held_lock *prev;
1782 struct held_lock *nest = NULL;
1785 for (i = 0; i < curr->lockdep_depth; i++) {
1786 prev = curr->held_locks + i;
1788 if (prev->instance == next->nest_lock)
1791 if (hlock_class(prev) != hlock_class(next))
1795 * Allow read-after-read recursion of the same
1796 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1798 if ((read == 2) && prev->read)
1802 * We're holding the nest_lock, which serializes this lock's
1803 * nesting behaviour.
1808 return print_deadlock_bug(curr, prev, next);
1814 * There was a chain-cache miss, and we are about to add a new dependency
1815 * to a previous lock. We recursively validate the following rules:
1817 * - would the adding of the <prev> -> <next> dependency create a
1818 * circular dependency in the graph? [== circular deadlock]
1820 * - does the new prev->next dependency connect any hardirq-safe lock
1821 * (in the full backwards-subgraph starting at <prev>) with any
1822 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1823 * <next>)? [== illegal lock inversion with hardirq contexts]
1825 * - does the new prev->next dependency connect any softirq-safe lock
1826 * (in the full backwards-subgraph starting at <prev>) with any
1827 * softirq-unsafe lock (in the full forwards-subgraph starting at
1828 * <next>)? [== illegal lock inversion with softirq contexts]
1830 * any of these scenarios could lead to a deadlock.
1832 * Then if all the validations pass, we add the forwards and backwards
1836 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1837 struct held_lock *next, int distance, struct stack_trace *trace,
1838 int (*save)(struct stack_trace *trace))
1840 struct lock_list *uninitialized_var(target_entry);
1841 struct lock_list *entry;
1842 struct lock_list this;
1846 * Prove that the new <prev> -> <next> dependency would not
1847 * create a circular dependency in the graph. (We do this by
1848 * forward-recursing into the graph starting at <next>, and
1849 * checking whether we can reach <prev>.)
1851 * We are using global variables to control the recursion, to
1852 * keep the stackframe size of the recursive functions low:
1854 this.class = hlock_class(next);
1856 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1857 if (unlikely(!ret)) {
1858 if (!trace->entries) {
1860 * If @save fails here, the printing might trigger
1861 * a WARN but because of the !nr_entries it should
1862 * not do bad things.
1866 return print_circular_bug(&this, target_entry, next, prev, trace);
1868 else if (unlikely(ret < 0))
1869 return print_bfs_bug(ret);
1871 if (!check_prev_add_irq(curr, prev, next))
1875 * For recursive read-locks we do all the dependency checks,
1876 * but we dont store read-triggered dependencies (only
1877 * write-triggered dependencies). This ensures that only the
1878 * write-side dependencies matter, and that if for example a
1879 * write-lock never takes any other locks, then the reads are
1880 * equivalent to a NOP.
1882 if (next->read == 2 || prev->read == 2)
1885 * Is the <prev> -> <next> dependency already present?
1887 * (this may occur even though this is a new chain: consider
1888 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1889 * chains - the second one will be new, but L1 already has
1890 * L2 added to its dependency list, due to the first chain.)
1892 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1893 if (entry->class == hlock_class(next)) {
1895 entry->distance = 1;
1901 * Is the <prev> -> <next> link redundant?
1903 this.class = hlock_class(prev);
1905 ret = check_redundant(&this, hlock_class(next), &target_entry);
1907 debug_atomic_inc(nr_redundant);
1911 return print_bfs_bug(ret);
1914 if (!trace->entries && !save(trace))
1918 * Ok, all validations passed, add the new lock
1919 * to the previous lock's dependency list:
1921 ret = add_lock_to_list(hlock_class(next),
1922 &hlock_class(prev)->locks_after,
1923 next->acquire_ip, distance, trace);
1928 ret = add_lock_to_list(hlock_class(prev),
1929 &hlock_class(next)->locks_before,
1930 next->acquire_ip, distance, trace);
1938 * Add the dependency to all directly-previous locks that are 'relevant'.
1939 * The ones that are relevant are (in increasing distance from curr):
1940 * all consecutive trylock entries and the final non-trylock entry - or
1941 * the end of this context's lock-chain - whichever comes first.
1944 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1946 int depth = curr->lockdep_depth;
1947 struct held_lock *hlock;
1948 struct stack_trace trace = {
1958 * Depth must not be zero for a non-head lock:
1963 * At least two relevant locks must exist for this
1966 if (curr->held_locks[depth].irq_context !=
1967 curr->held_locks[depth-1].irq_context)
1971 int distance = curr->lockdep_depth - depth + 1;
1972 hlock = curr->held_locks + depth - 1;
1975 * Only non-recursive-read entries get new dependencies
1978 if (hlock->read != 2 && hlock->check) {
1979 int ret = check_prev_add(curr, hlock, next, distance, &trace, save_trace);
1984 * Stop after the first non-trylock entry,
1985 * as non-trylock entries have added their
1986 * own direct dependencies already, so this
1987 * lock is connected to them indirectly:
1989 if (!hlock->trylock)
1995 * End of lock-stack?
2000 * Stop the search if we cross into another context:
2002 if (curr->held_locks[depth].irq_context !=
2003 curr->held_locks[depth-1].irq_context)
2008 if (!debug_locks_off_graph_unlock())
2012 * Clearly we all shouldn't be here, but since we made it we
2013 * can reliable say we messed up our state. See the above two
2014 * gotos for reasons why we could possibly end up here.
2021 unsigned long nr_lock_chains;
2022 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
2023 int nr_chain_hlocks;
2024 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
2026 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
2028 return lock_classes + chain_hlocks[chain->base + i];
2032 * Returns the index of the first held_lock of the current chain
2034 static inline int get_first_held_lock(struct task_struct *curr,
2035 struct held_lock *hlock)
2038 struct held_lock *hlock_curr;
2040 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2041 hlock_curr = curr->held_locks + i;
2042 if (hlock_curr->irq_context != hlock->irq_context)
2050 #ifdef CONFIG_DEBUG_LOCKDEP
2052 * Returns the next chain_key iteration
2054 static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2056 u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2058 printk(" class_idx:%d -> chain_key:%016Lx",
2060 (unsigned long long)new_chain_key);
2061 return new_chain_key;
2065 print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2067 struct held_lock *hlock;
2069 int depth = curr->lockdep_depth;
2072 printk("depth: %u\n", depth + 1);
2073 for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
2074 hlock = curr->held_locks + i;
2075 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2080 print_chain_key_iteration(hlock_next->class_idx, chain_key);
2081 print_lock(hlock_next);
2084 static void print_chain_keys_chain(struct lock_chain *chain)
2090 printk("depth: %u\n", chain->depth);
2091 for (i = 0; i < chain->depth; i++) {
2092 class_id = chain_hlocks[chain->base + i];
2093 chain_key = print_chain_key_iteration(class_id + 1, chain_key);
2095 print_lock_name(lock_classes + class_id);
2100 static void print_collision(struct task_struct *curr,
2101 struct held_lock *hlock_next,
2102 struct lock_chain *chain)
2105 pr_warn("============================\n");
2106 pr_warn("WARNING: chain_key collision\n");
2107 print_kernel_ident();
2108 pr_warn("----------------------------\n");
2109 pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
2110 pr_warn("Hash chain already cached but the contents don't match!\n");
2112 pr_warn("Held locks:");
2113 print_chain_keys_held_locks(curr, hlock_next);
2115 pr_warn("Locks in cached chain:");
2116 print_chain_keys_chain(chain);
2118 pr_warn("\nstack backtrace:\n");
2124 * Checks whether the chain and the current held locks are consistent
2125 * in depth and also in content. If they are not it most likely means
2126 * that there was a collision during the calculation of the chain_key.
2127 * Returns: 0 not passed, 1 passed
2129 static int check_no_collision(struct task_struct *curr,
2130 struct held_lock *hlock,
2131 struct lock_chain *chain)
2133 #ifdef CONFIG_DEBUG_LOCKDEP
2136 i = get_first_held_lock(curr, hlock);
2138 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2139 print_collision(curr, hlock, chain);
2143 for (j = 0; j < chain->depth - 1; j++, i++) {
2144 id = curr->held_locks[i].class_idx - 1;
2146 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2147 print_collision(curr, hlock, chain);
2156 * This is for building a chain between just two different classes,
2157 * instead of adding a new hlock upon current, which is done by
2158 * add_chain_cache().
2160 * This can be called in any context with two classes, while
2161 * add_chain_cache() must be done within the lock owener's context
2162 * since it uses hlock which might be racy in another context.
2164 static inline int add_chain_cache_classes(unsigned int prev,
2166 unsigned int irq_context,
2169 struct hlist_head *hash_head = chainhashentry(chain_key);
2170 struct lock_chain *chain;
2173 * Allocate a new chain entry from the static array, and add
2178 * We might need to take the graph lock, ensure we've got IRQs
2179 * disabled to make this an IRQ-safe lock.. for recursion reasons
2180 * lockdep won't complain about its own locking errors.
2182 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2185 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2186 if (!debug_locks_off_graph_unlock())
2189 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2194 chain = lock_chains + nr_lock_chains++;
2195 chain->chain_key = chain_key;
2196 chain->irq_context = irq_context;
2198 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2199 chain->base = nr_chain_hlocks;
2200 nr_chain_hlocks += chain->depth;
2201 chain_hlocks[chain->base] = prev - 1;
2202 chain_hlocks[chain->base + 1] = next -1;
2204 #ifdef CONFIG_DEBUG_LOCKDEP
2206 * Important for check_no_collision().
2209 if (!debug_locks_off_graph_unlock())
2212 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2218 hlist_add_head_rcu(&chain->entry, hash_head);
2219 debug_atomic_inc(chain_lookup_misses);
2226 * Adds a dependency chain into chain hashtable. And must be called with
2229 * Return 0 if fail, and graph_lock is released.
2230 * Return 1 if succeed, with graph_lock held.
2232 static inline int add_chain_cache(struct task_struct *curr,
2233 struct held_lock *hlock,
2236 struct lock_class *class = hlock_class(hlock);
2237 struct hlist_head *hash_head = chainhashentry(chain_key);
2238 struct lock_chain *chain;
2242 * Allocate a new chain entry from the static array, and add
2247 * We might need to take the graph lock, ensure we've got IRQs
2248 * disabled to make this an IRQ-safe lock.. for recursion reasons
2249 * lockdep won't complain about its own locking errors.
2251 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2254 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2255 if (!debug_locks_off_graph_unlock())
2258 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2262 chain = lock_chains + nr_lock_chains++;
2263 chain->chain_key = chain_key;
2264 chain->irq_context = hlock->irq_context;
2265 i = get_first_held_lock(curr, hlock);
2266 chain->depth = curr->lockdep_depth + 1 - i;
2268 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2269 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
2270 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2272 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2273 chain->base = nr_chain_hlocks;
2274 for (j = 0; j < chain->depth - 1; j++, i++) {
2275 int lock_id = curr->held_locks[i].class_idx - 1;
2276 chain_hlocks[chain->base + j] = lock_id;
2278 chain_hlocks[chain->base + j] = class - lock_classes;
2281 if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
2282 nr_chain_hlocks += chain->depth;
2284 #ifdef CONFIG_DEBUG_LOCKDEP
2286 * Important for check_no_collision().
2288 if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
2289 if (!debug_locks_off_graph_unlock())
2292 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2298 hlist_add_head_rcu(&chain->entry, hash_head);
2299 debug_atomic_inc(chain_lookup_misses);
2306 * Look up a dependency chain.
2308 static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
2310 struct hlist_head *hash_head = chainhashentry(chain_key);
2311 struct lock_chain *chain;
2314 * We can walk it lock-free, because entries only get added
2317 hlist_for_each_entry_rcu(chain, hash_head, entry) {
2318 if (chain->chain_key == chain_key) {
2319 debug_atomic_inc(chain_lookup_hits);
2327 * If the key is not present yet in dependency chain cache then
2328 * add it and return 1 - in this case the new dependency chain is
2329 * validated. If the key is already hashed, return 0.
2330 * (On return with 1 graph_lock is held.)
2332 static inline int lookup_chain_cache_add(struct task_struct *curr,
2333 struct held_lock *hlock,
2336 struct lock_class *class = hlock_class(hlock);
2337 struct lock_chain *chain = lookup_chain_cache(chain_key);
2341 if (!check_no_collision(curr, hlock, chain))
2344 if (very_verbose(class)) {
2345 printk("\nhash chain already cached, key: "
2346 "%016Lx tail class: [%px] %s\n",
2347 (unsigned long long)chain_key,
2348 class->key, class->name);
2354 if (very_verbose(class)) {
2355 printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
2356 (unsigned long long)chain_key, class->key, class->name);
2363 * We have to walk the chain again locked - to avoid duplicates:
2365 chain = lookup_chain_cache(chain_key);
2371 if (!add_chain_cache(curr, hlock, chain_key))
2377 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2378 struct held_lock *hlock, int chain_head, u64 chain_key)
2381 * Trylock needs to maintain the stack of held locks, but it
2382 * does not add new dependencies, because trylock can be done
2385 * We look up the chain_key and do the O(N^2) check and update of
2386 * the dependencies only if this is a new dependency chain.
2387 * (If lookup_chain_cache_add() return with 1 it acquires
2388 * graph_lock for us)
2390 if (!hlock->trylock && hlock->check &&
2391 lookup_chain_cache_add(curr, hlock, chain_key)) {
2393 * Check whether last held lock:
2395 * - is irq-safe, if this lock is irq-unsafe
2396 * - is softirq-safe, if this lock is hardirq-unsafe
2398 * And check whether the new lock's dependency graph
2399 * could lead back to the previous lock.
2401 * any of these scenarios could lead to a deadlock. If
2404 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2409 * Mark recursive read, as we jump over it when
2410 * building dependencies (just like we jump over
2416 * Add dependency only if this lock is not the head
2417 * of the chain, and if it's not a secondary read-lock:
2419 if (!chain_head && ret != 2) {
2420 if (!check_prevs_add(curr, hlock))
2426 /* after lookup_chain_cache_add(): */
2427 if (unlikely(!debug_locks))
2434 static inline int validate_chain(struct task_struct *curr,
2435 struct lockdep_map *lock, struct held_lock *hlock,
2436 int chain_head, u64 chain_key)
2443 * We are building curr_chain_key incrementally, so double-check
2444 * it from scratch, to make sure that it's done correctly:
2446 static void check_chain_key(struct task_struct *curr)
2448 #ifdef CONFIG_DEBUG_LOCKDEP
2449 struct held_lock *hlock, *prev_hlock = NULL;
2453 for (i = 0; i < curr->lockdep_depth; i++) {
2454 hlock = curr->held_locks + i;
2455 if (chain_key != hlock->prev_chain_key) {
2458 * We got mighty confused, our chain keys don't match
2459 * with what we expect, someone trample on our task state?
2461 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2462 curr->lockdep_depth, i,
2463 (unsigned long long)chain_key,
2464 (unsigned long long)hlock->prev_chain_key);
2468 * Whoops ran out of static storage again?
2470 if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
2473 if (prev_hlock && (prev_hlock->irq_context !=
2474 hlock->irq_context))
2476 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
2479 if (chain_key != curr->curr_chain_key) {
2482 * More smoking hash instead of calculating it, damn see these
2483 * numbers float.. I bet that a pink elephant stepped on my memory.
2485 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2486 curr->lockdep_depth, i,
2487 (unsigned long long)chain_key,
2488 (unsigned long long)curr->curr_chain_key);
2494 print_usage_bug_scenario(struct held_lock *lock)
2496 struct lock_class *class = hlock_class(lock);
2498 printk(" Possible unsafe locking scenario:\n\n");
2502 __print_lock_name(class);
2503 printk(KERN_CONT ");\n");
2504 printk(" <Interrupt>\n");
2506 __print_lock_name(class);
2507 printk(KERN_CONT ");\n");
2508 printk("\n *** DEADLOCK ***\n\n");
2512 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2513 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2515 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2519 pr_warn("================================\n");
2520 pr_warn("WARNING: inconsistent lock state\n");
2521 print_kernel_ident();
2522 pr_warn("--------------------------------\n");
2524 pr_warn("inconsistent {%s} -> {%s} usage.\n",
2525 usage_str[prev_bit], usage_str[new_bit]);
2527 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2528 curr->comm, task_pid_nr(curr),
2529 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2530 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2531 trace_hardirqs_enabled(curr),
2532 trace_softirqs_enabled(curr));
2535 pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
2536 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2538 print_irqtrace_events(curr);
2539 pr_warn("\nother info that might help us debug this:\n");
2540 print_usage_bug_scenario(this);
2542 lockdep_print_held_locks(curr);
2544 pr_warn("\nstack backtrace:\n");
2551 * Print out an error if an invalid bit is set:
2554 valid_state(struct task_struct *curr, struct held_lock *this,
2555 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2557 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2558 return print_usage_bug(curr, this, bad_bit, new_bit);
2562 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2563 enum lock_usage_bit new_bit);
2565 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2568 * print irq inversion bug:
2571 print_irq_inversion_bug(struct task_struct *curr,
2572 struct lock_list *root, struct lock_list *other,
2573 struct held_lock *this, int forwards,
2574 const char *irqclass)
2576 struct lock_list *entry = other;
2577 struct lock_list *middle = NULL;
2580 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2584 pr_warn("========================================================\n");
2585 pr_warn("WARNING: possible irq lock inversion dependency detected\n");
2586 print_kernel_ident();
2587 pr_warn("--------------------------------------------------------\n");
2588 pr_warn("%s/%d just changed the state of lock:\n",
2589 curr->comm, task_pid_nr(curr));
2592 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2594 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2595 print_lock_name(other->class);
2596 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2598 pr_warn("\nother info that might help us debug this:\n");
2600 /* Find a middle lock (if one exists) */
2601 depth = get_lock_depth(other);
2603 if (depth == 0 && (entry != root)) {
2604 pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
2608 entry = get_lock_parent(entry);
2610 } while (entry && entry != root && (depth >= 0));
2612 print_irq_lock_scenario(root, other,
2613 middle ? middle->class : root->class, other->class);
2615 print_irq_lock_scenario(other, root,
2616 middle ? middle->class : other->class, root->class);
2618 lockdep_print_held_locks(curr);
2620 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2621 if (!save_trace(&root->trace))
2623 print_shortest_lock_dependencies(other, root);
2625 pr_warn("\nstack backtrace:\n");
2632 * Prove that in the forwards-direction subgraph starting at <this>
2633 * there is no lock matching <mask>:
2636 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2637 enum lock_usage_bit bit, const char *irqclass)
2640 struct lock_list root;
2641 struct lock_list *uninitialized_var(target_entry);
2644 root.class = hlock_class(this);
2645 ret = find_usage_forwards(&root, bit, &target_entry);
2647 return print_bfs_bug(ret);
2651 return print_irq_inversion_bug(curr, &root, target_entry,
2656 * Prove that in the backwards-direction subgraph starting at <this>
2657 * there is no lock matching <mask>:
2660 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2661 enum lock_usage_bit bit, const char *irqclass)
2664 struct lock_list root;
2665 struct lock_list *uninitialized_var(target_entry);
2668 root.class = hlock_class(this);
2669 ret = find_usage_backwards(&root, bit, &target_entry);
2671 return print_bfs_bug(ret);
2675 return print_irq_inversion_bug(curr, &root, target_entry,
2679 void print_irqtrace_events(struct task_struct *curr)
2681 printk("irq event stamp: %u\n", curr->irq_events);
2682 printk("hardirqs last enabled at (%u): [<%px>] %pS\n",
2683 curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
2684 (void *)curr->hardirq_enable_ip);
2685 printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
2686 curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
2687 (void *)curr->hardirq_disable_ip);
2688 printk("softirqs last enabled at (%u): [<%px>] %pS\n",
2689 curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
2690 (void *)curr->softirq_enable_ip);
2691 printk("softirqs last disabled at (%u): [<%px>] %pS\n",
2692 curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
2693 (void *)curr->softirq_disable_ip);
2696 static int HARDIRQ_verbose(struct lock_class *class)
2699 return class_filter(class);
2704 static int SOFTIRQ_verbose(struct lock_class *class)
2707 return class_filter(class);
2712 #define STRICT_READ_CHECKS 1
2714 static int (*state_verbose_f[])(struct lock_class *class) = {
2715 #define LOCKDEP_STATE(__STATE) \
2717 #include "lockdep_states.h"
2718 #undef LOCKDEP_STATE
2721 static inline int state_verbose(enum lock_usage_bit bit,
2722 struct lock_class *class)
2724 return state_verbose_f[bit >> 2](class);
2727 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2728 enum lock_usage_bit bit, const char *name);
2731 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2732 enum lock_usage_bit new_bit)
2734 int excl_bit = exclusive_bit(new_bit);
2735 int read = new_bit & 1;
2736 int dir = new_bit & 2;
2739 * mark USED_IN has to look forwards -- to ensure no dependency
2740 * has ENABLED state, which would allow recursion deadlocks.
2742 * mark ENABLED has to look backwards -- to ensure no dependee
2743 * has USED_IN state, which, again, would allow recursion deadlocks.
2745 check_usage_f usage = dir ?
2746 check_usage_backwards : check_usage_forwards;
2749 * Validate that this particular lock does not have conflicting
2752 if (!valid_state(curr, this, new_bit, excl_bit))
2756 * Validate that the lock dependencies don't have conflicting usage
2759 if ((!read || !dir || STRICT_READ_CHECKS) &&
2760 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2764 * Check for read in write conflicts
2767 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2770 if (STRICT_READ_CHECKS &&
2771 !usage(curr, this, excl_bit + 1,
2772 state_name(new_bit + 1)))
2776 if (state_verbose(new_bit, hlock_class(this)))
2783 #define LOCKDEP_STATE(__STATE) __STATE,
2784 #include "lockdep_states.h"
2785 #undef LOCKDEP_STATE
2789 * Mark all held locks with a usage bit:
2792 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2794 enum lock_usage_bit usage_bit;
2795 struct held_lock *hlock;
2798 for (i = 0; i < curr->lockdep_depth; i++) {
2799 hlock = curr->held_locks + i;
2801 usage_bit = 2 + (mark << 2); /* ENABLED */
2803 usage_bit += 1; /* READ */
2805 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2810 if (!mark_lock(curr, hlock, usage_bit))
2818 * Hardirqs will be enabled:
2820 static void __trace_hardirqs_on_caller(unsigned long ip)
2822 struct task_struct *curr = current;
2824 /* we'll do an OFF -> ON transition: */
2825 curr->hardirqs_enabled = 1;
2828 * We are going to turn hardirqs on, so set the
2829 * usage bit for all held locks:
2831 if (!mark_held_locks(curr, HARDIRQ))
2834 * If we have softirqs enabled, then set the usage
2835 * bit for all held locks. (disabled hardirqs prevented
2836 * this bit from being set before)
2838 if (curr->softirqs_enabled)
2839 if (!mark_held_locks(curr, SOFTIRQ))
2842 curr->hardirq_enable_ip = ip;
2843 curr->hardirq_enable_event = ++curr->irq_events;
2844 debug_atomic_inc(hardirqs_on_events);
2847 void lockdep_hardirqs_on(unsigned long ip)
2849 if (unlikely(!debug_locks || current->lockdep_recursion))
2852 if (unlikely(current->hardirqs_enabled)) {
2854 * Neither irq nor preemption are disabled here
2855 * so this is racy by nature but losing one hit
2856 * in a stat is not a big deal.
2858 __debug_atomic_inc(redundant_hardirqs_on);
2863 * We're enabling irqs and according to our state above irqs weren't
2864 * already enabled, yet we find the hardware thinks they are in fact
2865 * enabled.. someone messed up their IRQ state tracing.
2867 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2871 * See the fine text that goes along with this variable definition.
2873 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2877 * Can't allow enabling interrupts while in an interrupt handler,
2878 * that's general bad form and such. Recursion, limited stack etc..
2880 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2883 current->lockdep_recursion = 1;
2884 __trace_hardirqs_on_caller(ip);
2885 current->lockdep_recursion = 0;
2889 * Hardirqs were disabled:
2891 void lockdep_hardirqs_off(unsigned long ip)
2893 struct task_struct *curr = current;
2895 if (unlikely(!debug_locks || current->lockdep_recursion))
2899 * So we're supposed to get called after you mask local IRQs, but for
2900 * some reason the hardware doesn't quite think you did a proper job.
2902 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2905 if (curr->hardirqs_enabled) {
2907 * We have done an ON -> OFF transition:
2909 curr->hardirqs_enabled = 0;
2910 curr->hardirq_disable_ip = ip;
2911 curr->hardirq_disable_event = ++curr->irq_events;
2912 debug_atomic_inc(hardirqs_off_events);
2914 debug_atomic_inc(redundant_hardirqs_off);
2918 * Softirqs will be enabled:
2920 void trace_softirqs_on(unsigned long ip)
2922 struct task_struct *curr = current;
2924 if (unlikely(!debug_locks || current->lockdep_recursion))
2928 * We fancy IRQs being disabled here, see softirq.c, avoids
2929 * funny state and nesting things.
2931 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2934 if (curr->softirqs_enabled) {
2935 debug_atomic_inc(redundant_softirqs_on);
2939 current->lockdep_recursion = 1;
2941 * We'll do an OFF -> ON transition:
2943 curr->softirqs_enabled = 1;
2944 curr->softirq_enable_ip = ip;
2945 curr->softirq_enable_event = ++curr->irq_events;
2946 debug_atomic_inc(softirqs_on_events);
2948 * We are going to turn softirqs on, so set the
2949 * usage bit for all held locks, if hardirqs are
2952 if (curr->hardirqs_enabled)
2953 mark_held_locks(curr, SOFTIRQ);
2954 current->lockdep_recursion = 0;
2958 * Softirqs were disabled:
2960 void trace_softirqs_off(unsigned long ip)
2962 struct task_struct *curr = current;
2964 if (unlikely(!debug_locks || current->lockdep_recursion))
2968 * We fancy IRQs being disabled here, see softirq.c
2970 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2973 if (curr->softirqs_enabled) {
2975 * We have done an ON -> OFF transition:
2977 curr->softirqs_enabled = 0;
2978 curr->softirq_disable_ip = ip;
2979 curr->softirq_disable_event = ++curr->irq_events;
2980 debug_atomic_inc(softirqs_off_events);
2982 * Whoops, we wanted softirqs off, so why aren't they?
2984 DEBUG_LOCKS_WARN_ON(!softirq_count());
2986 debug_atomic_inc(redundant_softirqs_off);
2989 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2992 * If non-trylock use in a hardirq or softirq context, then
2993 * mark the lock as used in these contexts:
2995 if (!hlock->trylock) {
2997 if (curr->hardirq_context)
2998 if (!mark_lock(curr, hlock,
2999 LOCK_USED_IN_HARDIRQ_READ))
3001 if (curr->softirq_context)
3002 if (!mark_lock(curr, hlock,
3003 LOCK_USED_IN_SOFTIRQ_READ))
3006 if (curr->hardirq_context)
3007 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
3009 if (curr->softirq_context)
3010 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
3014 if (!hlock->hardirqs_off) {
3016 if (!mark_lock(curr, hlock,
3017 LOCK_ENABLED_HARDIRQ_READ))
3019 if (curr->softirqs_enabled)
3020 if (!mark_lock(curr, hlock,
3021 LOCK_ENABLED_SOFTIRQ_READ))
3024 if (!mark_lock(curr, hlock,
3025 LOCK_ENABLED_HARDIRQ))
3027 if (curr->softirqs_enabled)
3028 if (!mark_lock(curr, hlock,
3029 LOCK_ENABLED_SOFTIRQ))
3037 static inline unsigned int task_irq_context(struct task_struct *task)
3039 return 2 * !!task->hardirq_context + !!task->softirq_context;
3042 static int separate_irq_context(struct task_struct *curr,
3043 struct held_lock *hlock)
3045 unsigned int depth = curr->lockdep_depth;
3048 * Keep track of points where we cross into an interrupt context:
3051 struct held_lock *prev_hlock;
3053 prev_hlock = curr->held_locks + depth-1;
3055 * If we cross into another context, reset the
3056 * hash key (this also prevents the checking and the
3057 * adding of the dependency to 'prev'):
3059 if (prev_hlock->irq_context != hlock->irq_context)
3065 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3068 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
3069 enum lock_usage_bit new_bit)
3071 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
3075 static inline int mark_irqflags(struct task_struct *curr,
3076 struct held_lock *hlock)
3081 static inline unsigned int task_irq_context(struct task_struct *task)
3086 static inline int separate_irq_context(struct task_struct *curr,
3087 struct held_lock *hlock)
3092 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3095 * Mark a lock with a usage bit, and validate the state transition:
3097 static int mark_lock(struct task_struct *curr, struct held_lock *this,
3098 enum lock_usage_bit new_bit)
3100 unsigned int new_mask = 1 << new_bit, ret = 1;
3103 * If already set then do not dirty the cacheline,
3104 * nor do any checks:
3106 if (likely(hlock_class(this)->usage_mask & new_mask))
3112 * Make sure we didn't race:
3114 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3119 hlock_class(this)->usage_mask |= new_mask;
3121 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
3125 #define LOCKDEP_STATE(__STATE) \
3126 case LOCK_USED_IN_##__STATE: \
3127 case LOCK_USED_IN_##__STATE##_READ: \
3128 case LOCK_ENABLED_##__STATE: \
3129 case LOCK_ENABLED_##__STATE##_READ:
3130 #include "lockdep_states.h"
3131 #undef LOCKDEP_STATE
3132 ret = mark_lock_irq(curr, this, new_bit);
3137 debug_atomic_dec(nr_unused_locks);
3140 if (!debug_locks_off_graph_unlock())
3149 * We must printk outside of the graph_lock:
3152 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3154 print_irqtrace_events(curr);
3162 * Initialize a lock instance's lock-class mapping info:
3164 static void __lockdep_init_map(struct lockdep_map *lock, const char *name,
3165 struct lock_class_key *key, int subclass)
3169 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3170 lock->class_cache[i] = NULL;
3172 #ifdef CONFIG_LOCK_STAT
3173 lock->cpu = raw_smp_processor_id();
3177 * Can't be having no nameless bastards around this place!
3179 if (DEBUG_LOCKS_WARN_ON(!name)) {
3180 lock->name = "NULL";
3187 * No key, no joy, we need to hash something.
3189 if (DEBUG_LOCKS_WARN_ON(!key))
3192 * Sanity check, the lock-class key must be persistent:
3194 if (!static_obj(key)) {
3195 printk("BUG: key %px not in .data!\n", key);
3197 * What it says above ^^^^^, I suggest you read it.
3199 DEBUG_LOCKS_WARN_ON(1);
3204 if (unlikely(!debug_locks))
3208 unsigned long flags;
3210 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3213 raw_local_irq_save(flags);
3214 current->lockdep_recursion = 1;
3215 register_lock_class(lock, subclass, 1);
3216 current->lockdep_recursion = 0;
3217 raw_local_irq_restore(flags);
3221 void lockdep_init_map(struct lockdep_map *lock, const char *name,
3222 struct lock_class_key *key, int subclass)
3224 __lockdep_init_map(lock, name, key, subclass);
3226 EXPORT_SYMBOL_GPL(lockdep_init_map);
3228 struct lock_class_key __lockdep_no_validate__;
3229 EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3232 print_lock_nested_lock_not_held(struct task_struct *curr,
3233 struct held_lock *hlock,
3236 if (!debug_locks_off())
3238 if (debug_locks_silent)
3242 pr_warn("==================================\n");
3243 pr_warn("WARNING: Nested lock was not taken\n");
3244 print_kernel_ident();
3245 pr_warn("----------------------------------\n");
3247 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3250 pr_warn("\nbut this task is not holding:\n");
3251 pr_warn("%s\n", hlock->nest_lock->name);
3253 pr_warn("\nstack backtrace:\n");
3256 pr_warn("\nother info that might help us debug this:\n");
3257 lockdep_print_held_locks(curr);
3259 pr_warn("\nstack backtrace:\n");
3265 static int __lock_is_held(const struct lockdep_map *lock, int read);
3268 * This gets called for every mutex_lock*()/spin_lock*() operation.
3269 * We maintain the dependency maps and validate the locking attempt:
3271 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3272 int trylock, int read, int check, int hardirqs_off,
3273 struct lockdep_map *nest_lock, unsigned long ip,
3274 int references, int pin_count)
3276 struct task_struct *curr = current;
3277 struct lock_class *class = NULL;
3278 struct held_lock *hlock;
3284 if (unlikely(!debug_locks))
3288 * Lockdep should run with IRQs disabled, otherwise we could
3289 * get an interrupt which would want to take locks, which would
3290 * end up in lockdep and have you got a head-ache already?
3292 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3295 if (!prove_locking || lock->key == &__lockdep_no_validate__)
3298 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3299 class = lock->class_cache[subclass];
3303 if (unlikely(!class)) {
3304 class = register_lock_class(lock, subclass, 0);
3308 atomic_inc((atomic_t *)&class->ops);
3309 if (very_verbose(class)) {
3310 printk("\nacquire class [%px] %s", class->key, class->name);
3311 if (class->name_version > 1)
3312 printk(KERN_CONT "#%d", class->name_version);
3313 printk(KERN_CONT "\n");
3318 * Add the lock to the list of currently held locks.
3319 * (we dont increase the depth just yet, up until the
3320 * dependency checks are done)
3322 depth = curr->lockdep_depth;
3324 * Ran out of static storage for our per-task lock stack again have we?
3326 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3329 class_idx = class - lock_classes + 1;
3332 hlock = curr->held_locks + depth - 1;
3333 if (hlock->class_idx == class_idx && nest_lock) {
3337 if (!hlock->references)
3338 hlock->references++;
3340 hlock->references += references;
3343 if (DEBUG_LOCKS_WARN_ON(hlock->references < references))
3350 hlock = curr->held_locks + depth;
3352 * Plain impossible, we just registered it and checked it weren't no
3353 * NULL like.. I bet this mushroom I ate was good!
3355 if (DEBUG_LOCKS_WARN_ON(!class))
3357 hlock->class_idx = class_idx;
3358 hlock->acquire_ip = ip;
3359 hlock->instance = lock;
3360 hlock->nest_lock = nest_lock;
3361 hlock->irq_context = task_irq_context(curr);
3362 hlock->trylock = trylock;
3364 hlock->check = check;
3365 hlock->hardirqs_off = !!hardirqs_off;
3366 hlock->references = references;
3367 #ifdef CONFIG_LOCK_STAT
3368 hlock->waittime_stamp = 0;
3369 hlock->holdtime_stamp = lockstat_clock();
3371 hlock->pin_count = pin_count;
3373 if (check && !mark_irqflags(curr, hlock))
3376 /* mark it as used: */
3377 if (!mark_lock(curr, hlock, LOCK_USED))
3381 * Calculate the chain hash: it's the combined hash of all the
3382 * lock keys along the dependency chain. We save the hash value
3383 * at every step so that we can get the current hash easily
3384 * after unlock. The chain hash is then used to cache dependency
3387 * The 'key ID' is what is the most compact key value to drive
3388 * the hash, not class->key.
3391 * Whoops, we did it again.. ran straight out of our static allocation.
3393 if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
3396 chain_key = curr->curr_chain_key;
3399 * How can we have a chain hash when we ain't got no keys?!
3401 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3406 hlock->prev_chain_key = chain_key;
3407 if (separate_irq_context(curr, hlock)) {
3411 chain_key = iterate_chain_key(chain_key, class_idx);
3413 if (nest_lock && !__lock_is_held(nest_lock, -1))
3414 return print_lock_nested_lock_not_held(curr, hlock, ip);
3416 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3419 curr->curr_chain_key = chain_key;
3420 curr->lockdep_depth++;
3421 check_chain_key(curr);
3422 #ifdef CONFIG_DEBUG_LOCKDEP
3423 if (unlikely(!debug_locks))
3426 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3428 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3429 printk(KERN_DEBUG "depth: %i max: %lu!\n",
3430 curr->lockdep_depth, MAX_LOCK_DEPTH);
3432 lockdep_print_held_locks(current);
3433 debug_show_all_locks();
3439 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3440 max_lockdep_depth = curr->lockdep_depth;
3446 print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3449 if (!debug_locks_off())
3451 if (debug_locks_silent)
3455 pr_warn("=====================================\n");
3456 pr_warn("WARNING: bad unlock balance detected!\n");
3457 print_kernel_ident();
3458 pr_warn("-------------------------------------\n");
3459 pr_warn("%s/%d is trying to release lock (",
3460 curr->comm, task_pid_nr(curr));
3461 print_lockdep_cache(lock);
3464 pr_warn("but there are no more locks to release!\n");
3465 pr_warn("\nother info that might help us debug this:\n");
3466 lockdep_print_held_locks(curr);
3468 pr_warn("\nstack backtrace:\n");
3474 static int match_held_lock(const struct held_lock *hlock,
3475 const struct lockdep_map *lock)
3477 if (hlock->instance == lock)
3480 if (hlock->references) {
3481 const struct lock_class *class = lock->class_cache[0];
3484 class = look_up_lock_class(lock, 0);
3487 * If look_up_lock_class() failed to find a class, we're trying
3488 * to test if we hold a lock that has never yet been acquired.
3489 * Clearly if the lock hasn't been acquired _ever_, we're not
3490 * holding it either, so report failure.
3496 * References, but not a lock we're actually ref-counting?
3497 * State got messed up, follow the sites that change ->references
3498 * and try to make sense of it.
3500 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3503 if (hlock->class_idx == class - lock_classes + 1)
3510 /* @depth must not be zero */
3511 static struct held_lock *find_held_lock(struct task_struct *curr,
3512 struct lockdep_map *lock,
3513 unsigned int depth, int *idx)
3515 struct held_lock *ret, *hlock, *prev_hlock;
3519 hlock = curr->held_locks + i;
3521 if (match_held_lock(hlock, lock))
3525 for (i--, prev_hlock = hlock--;
3527 i--, prev_hlock = hlock--) {
3529 * We must not cross into another context:
3531 if (prev_hlock->irq_context != hlock->irq_context) {
3535 if (match_held_lock(hlock, lock)) {
3546 static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
3549 struct held_lock *hlock;
3551 for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
3552 if (!__lock_acquire(hlock->instance,
3553 hlock_class(hlock)->subclass,
3555 hlock->read, hlock->check,
3556 hlock->hardirqs_off,
3557 hlock->nest_lock, hlock->acquire_ip,
3558 hlock->references, hlock->pin_count))
3565 __lock_set_class(struct lockdep_map *lock, const char *name,
3566 struct lock_class_key *key, unsigned int subclass,
3569 struct task_struct *curr = current;
3570 struct held_lock *hlock;
3571 struct lock_class *class;
3575 depth = curr->lockdep_depth;
3577 * This function is about (re)setting the class of a held lock,
3578 * yet we're not actually holding any locks. Naughty user!
3580 if (DEBUG_LOCKS_WARN_ON(!depth))
3583 hlock = find_held_lock(curr, lock, depth, &i);
3585 return print_unlock_imbalance_bug(curr, lock, ip);
3587 lockdep_init_map(lock, name, key, 0);
3588 class = register_lock_class(lock, subclass, 0);
3589 hlock->class_idx = class - lock_classes + 1;
3591 curr->lockdep_depth = i;
3592 curr->curr_chain_key = hlock->prev_chain_key;
3594 if (reacquire_held_locks(curr, depth, i))
3598 * I took it apart and put it back together again, except now I have
3599 * these 'spare' parts.. where shall I put them.
3601 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3606 static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
3608 struct task_struct *curr = current;
3609 struct held_lock *hlock;
3613 if (unlikely(!debug_locks))
3616 depth = curr->lockdep_depth;
3618 * This function is about (re)setting the class of a held lock,
3619 * yet we're not actually holding any locks. Naughty user!
3621 if (DEBUG_LOCKS_WARN_ON(!depth))
3624 hlock = find_held_lock(curr, lock, depth, &i);
3626 return print_unlock_imbalance_bug(curr, lock, ip);
3628 curr->lockdep_depth = i;
3629 curr->curr_chain_key = hlock->prev_chain_key;
3631 WARN(hlock->read, "downgrading a read lock");
3633 hlock->acquire_ip = ip;
3635 if (reacquire_held_locks(curr, depth, i))
3639 * I took it apart and put it back together again, except now I have
3640 * these 'spare' parts.. where shall I put them.
3642 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3648 * Remove the lock to the list of currently held locks - this gets
3649 * called on mutex_unlock()/spin_unlock*() (or on a failed
3650 * mutex_lock_interruptible()).
3652 * @nested is an hysterical artifact, needs a tree wide cleanup.
3655 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3657 struct task_struct *curr = current;
3658 struct held_lock *hlock;
3662 if (unlikely(!debug_locks))
3665 depth = curr->lockdep_depth;
3667 * So we're all set to release this lock.. wait what lock? We don't
3668 * own any locks, you've been drinking again?
3670 if (DEBUG_LOCKS_WARN_ON(depth <= 0))
3671 return print_unlock_imbalance_bug(curr, lock, ip);
3674 * Check whether the lock exists in the current stack
3677 hlock = find_held_lock(curr, lock, depth, &i);
3679 return print_unlock_imbalance_bug(curr, lock, ip);
3681 if (hlock->instance == lock)
3682 lock_release_holdtime(hlock);
3684 WARN(hlock->pin_count, "releasing a pinned lock\n");
3686 if (hlock->references) {
3687 hlock->references--;
3688 if (hlock->references) {
3690 * We had, and after removing one, still have
3691 * references, the current lock stack is still
3692 * valid. We're done!
3699 * We have the right lock to unlock, 'hlock' points to it.
3700 * Now we remove it from the stack, and add back the other
3701 * entries (if any), recalculating the hash along the way:
3704 curr->lockdep_depth = i;
3705 curr->curr_chain_key = hlock->prev_chain_key;
3707 if (reacquire_held_locks(curr, depth, i + 1))
3711 * We had N bottles of beer on the wall, we drank one, but now
3712 * there's not N-1 bottles of beer left on the wall...
3714 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3720 static int __lock_is_held(const struct lockdep_map *lock, int read)
3722 struct task_struct *curr = current;
3725 for (i = 0; i < curr->lockdep_depth; i++) {
3726 struct held_lock *hlock = curr->held_locks + i;
3728 if (match_held_lock(hlock, lock)) {
3729 if (read == -1 || hlock->read == read)
3739 static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
3741 struct pin_cookie cookie = NIL_COOKIE;
3742 struct task_struct *curr = current;
3745 if (unlikely(!debug_locks))
3748 for (i = 0; i < curr->lockdep_depth; i++) {
3749 struct held_lock *hlock = curr->held_locks + i;
3751 if (match_held_lock(hlock, lock)) {
3753 * Grab 16bits of randomness; this is sufficient to not
3754 * be guessable and still allows some pin nesting in
3755 * our u32 pin_count.
3757 cookie.val = 1 + (prandom_u32() >> 16);
3758 hlock->pin_count += cookie.val;
3763 WARN(1, "pinning an unheld lock\n");
3767 static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3769 struct task_struct *curr = current;
3772 if (unlikely(!debug_locks))
3775 for (i = 0; i < curr->lockdep_depth; i++) {
3776 struct held_lock *hlock = curr->held_locks + i;
3778 if (match_held_lock(hlock, lock)) {
3779 hlock->pin_count += cookie.val;
3784 WARN(1, "pinning an unheld lock\n");
3787 static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3789 struct task_struct *curr = current;
3792 if (unlikely(!debug_locks))
3795 for (i = 0; i < curr->lockdep_depth; i++) {
3796 struct held_lock *hlock = curr->held_locks + i;
3798 if (match_held_lock(hlock, lock)) {
3799 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
3802 hlock->pin_count -= cookie.val;
3804 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
3805 hlock->pin_count = 0;
3811 WARN(1, "unpinning an unheld lock\n");
3815 * Check whether we follow the irq-flags state precisely:
3817 static void check_flags(unsigned long flags)
3819 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3820 defined(CONFIG_TRACE_IRQFLAGS)
3824 if (irqs_disabled_flags(flags)) {
3825 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3826 printk("possible reason: unannotated irqs-off.\n");
3829 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3830 printk("possible reason: unannotated irqs-on.\n");
3835 * We dont accurately track softirq state in e.g.
3836 * hardirq contexts (such as on 4KSTACKS), so only
3837 * check if not in hardirq contexts:
3839 if (!hardirq_count()) {
3840 if (softirq_count()) {
3841 /* like the above, but with softirqs */
3842 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3844 /* lick the above, does it taste good? */
3845 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3850 print_irqtrace_events(current);
3854 void lock_set_class(struct lockdep_map *lock, const char *name,
3855 struct lock_class_key *key, unsigned int subclass,
3858 unsigned long flags;
3860 if (unlikely(current->lockdep_recursion))
3863 raw_local_irq_save(flags);
3864 current->lockdep_recursion = 1;
3866 if (__lock_set_class(lock, name, key, subclass, ip))
3867 check_chain_key(current);
3868 current->lockdep_recursion = 0;
3869 raw_local_irq_restore(flags);
3871 EXPORT_SYMBOL_GPL(lock_set_class);
3873 void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
3875 unsigned long flags;
3877 if (unlikely(current->lockdep_recursion))
3880 raw_local_irq_save(flags);
3881 current->lockdep_recursion = 1;
3883 if (__lock_downgrade(lock, ip))
3884 check_chain_key(current);
3885 current->lockdep_recursion = 0;
3886 raw_local_irq_restore(flags);
3888 EXPORT_SYMBOL_GPL(lock_downgrade);
3891 * We are not always called with irqs disabled - do that here,
3892 * and also avoid lockdep recursion:
3894 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3895 int trylock, int read, int check,
3896 struct lockdep_map *nest_lock, unsigned long ip)
3898 unsigned long flags;
3900 if (unlikely(current->lockdep_recursion))
3903 raw_local_irq_save(flags);
3906 current->lockdep_recursion = 1;
3907 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3908 __lock_acquire(lock, subclass, trylock, read, check,
3909 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
3910 current->lockdep_recursion = 0;
3911 raw_local_irq_restore(flags);
3913 EXPORT_SYMBOL_GPL(lock_acquire);
3915 void lock_release(struct lockdep_map *lock, int nested,
3918 unsigned long flags;
3920 if (unlikely(current->lockdep_recursion))
3923 raw_local_irq_save(flags);
3925 current->lockdep_recursion = 1;
3926 trace_lock_release(lock, ip);
3927 if (__lock_release(lock, nested, ip))
3928 check_chain_key(current);
3929 current->lockdep_recursion = 0;
3930 raw_local_irq_restore(flags);
3932 EXPORT_SYMBOL_GPL(lock_release);
3934 int lock_is_held_type(const struct lockdep_map *lock, int read)
3936 unsigned long flags;
3939 if (unlikely(current->lockdep_recursion))
3940 return 1; /* avoid false negative lockdep_assert_held() */
3942 raw_local_irq_save(flags);
3945 current->lockdep_recursion = 1;
3946 ret = __lock_is_held(lock, read);
3947 current->lockdep_recursion = 0;
3948 raw_local_irq_restore(flags);
3952 EXPORT_SYMBOL_GPL(lock_is_held_type);
3954 struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
3956 struct pin_cookie cookie = NIL_COOKIE;
3957 unsigned long flags;
3959 if (unlikely(current->lockdep_recursion))
3962 raw_local_irq_save(flags);
3965 current->lockdep_recursion = 1;
3966 cookie = __lock_pin_lock(lock);
3967 current->lockdep_recursion = 0;
3968 raw_local_irq_restore(flags);
3972 EXPORT_SYMBOL_GPL(lock_pin_lock);
3974 void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3976 unsigned long flags;
3978 if (unlikely(current->lockdep_recursion))
3981 raw_local_irq_save(flags);
3984 current->lockdep_recursion = 1;
3985 __lock_repin_lock(lock, cookie);
3986 current->lockdep_recursion = 0;
3987 raw_local_irq_restore(flags);
3989 EXPORT_SYMBOL_GPL(lock_repin_lock);
3991 void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3993 unsigned long flags;
3995 if (unlikely(current->lockdep_recursion))
3998 raw_local_irq_save(flags);
4001 current->lockdep_recursion = 1;
4002 __lock_unpin_lock(lock, cookie);
4003 current->lockdep_recursion = 0;
4004 raw_local_irq_restore(flags);
4006 EXPORT_SYMBOL_GPL(lock_unpin_lock);
4008 #ifdef CONFIG_LOCK_STAT
4010 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
4013 if (!debug_locks_off())
4015 if (debug_locks_silent)
4019 pr_warn("=================================\n");
4020 pr_warn("WARNING: bad contention detected!\n");
4021 print_kernel_ident();
4022 pr_warn("---------------------------------\n");
4023 pr_warn("%s/%d is trying to contend lock (",
4024 curr->comm, task_pid_nr(curr));
4025 print_lockdep_cache(lock);
4028 pr_warn("but there are no locks held!\n");
4029 pr_warn("\nother info that might help us debug this:\n");
4030 lockdep_print_held_locks(curr);
4032 pr_warn("\nstack backtrace:\n");
4039 __lock_contended(struct lockdep_map *lock, unsigned long ip)
4041 struct task_struct *curr = current;
4042 struct held_lock *hlock;
4043 struct lock_class_stats *stats;
4045 int i, contention_point, contending_point;
4047 depth = curr->lockdep_depth;
4049 * Whee, we contended on this lock, except it seems we're not
4050 * actually trying to acquire anything much at all..
4052 if (DEBUG_LOCKS_WARN_ON(!depth))
4055 hlock = find_held_lock(curr, lock, depth, &i);
4057 print_lock_contention_bug(curr, lock, ip);
4061 if (hlock->instance != lock)
4064 hlock->waittime_stamp = lockstat_clock();
4066 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
4067 contending_point = lock_point(hlock_class(hlock)->contending_point,
4070 stats = get_lock_stats(hlock_class(hlock));
4071 if (contention_point < LOCKSTAT_POINTS)
4072 stats->contention_point[contention_point]++;
4073 if (contending_point < LOCKSTAT_POINTS)
4074 stats->contending_point[contending_point]++;
4075 if (lock->cpu != smp_processor_id())
4076 stats->bounces[bounce_contended + !!hlock->read]++;
4080 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
4082 struct task_struct *curr = current;
4083 struct held_lock *hlock;
4084 struct lock_class_stats *stats;
4086 u64 now, waittime = 0;
4089 depth = curr->lockdep_depth;
4091 * Yay, we acquired ownership of this lock we didn't try to
4092 * acquire, how the heck did that happen?
4094 if (DEBUG_LOCKS_WARN_ON(!depth))
4097 hlock = find_held_lock(curr, lock, depth, &i);
4099 print_lock_contention_bug(curr, lock, _RET_IP_);
4103 if (hlock->instance != lock)
4106 cpu = smp_processor_id();
4107 if (hlock->waittime_stamp) {
4108 now = lockstat_clock();
4109 waittime = now - hlock->waittime_stamp;
4110 hlock->holdtime_stamp = now;
4113 trace_lock_acquired(lock, ip);
4115 stats = get_lock_stats(hlock_class(hlock));
4118 lock_time_inc(&stats->read_waittime, waittime);
4120 lock_time_inc(&stats->write_waittime, waittime);
4122 if (lock->cpu != cpu)
4123 stats->bounces[bounce_acquired + !!hlock->read]++;
4129 void lock_contended(struct lockdep_map *lock, unsigned long ip)
4131 unsigned long flags;
4133 if (unlikely(!lock_stat || !debug_locks))
4136 if (unlikely(current->lockdep_recursion))
4139 raw_local_irq_save(flags);
4141 current->lockdep_recursion = 1;
4142 trace_lock_contended(lock, ip);
4143 __lock_contended(lock, ip);
4144 current->lockdep_recursion = 0;
4145 raw_local_irq_restore(flags);
4147 EXPORT_SYMBOL_GPL(lock_contended);
4149 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
4151 unsigned long flags;
4153 if (unlikely(!lock_stat || !debug_locks))
4156 if (unlikely(current->lockdep_recursion))
4159 raw_local_irq_save(flags);
4161 current->lockdep_recursion = 1;
4162 __lock_acquired(lock, ip);
4163 current->lockdep_recursion = 0;
4164 raw_local_irq_restore(flags);
4166 EXPORT_SYMBOL_GPL(lock_acquired);
4170 * Used by the testsuite, sanitize the validator state
4171 * after a simulated failure:
4174 void lockdep_reset(void)
4176 unsigned long flags;
4179 raw_local_irq_save(flags);
4180 current->curr_chain_key = 0;
4181 current->lockdep_depth = 0;
4182 current->lockdep_recursion = 0;
4183 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
4184 nr_hardirq_chains = 0;
4185 nr_softirq_chains = 0;
4186 nr_process_chains = 0;
4188 for (i = 0; i < CHAINHASH_SIZE; i++)
4189 INIT_HLIST_HEAD(chainhash_table + i);
4190 raw_local_irq_restore(flags);
4193 static void zap_class(struct lock_class *class)
4198 * Remove all dependencies this lock is
4201 for (i = 0; i < nr_list_entries; i++) {
4202 if (list_entries[i].class == class)
4203 list_del_rcu(&list_entries[i].entry);
4206 * Unhash the class and remove it from the all_lock_classes list:
4208 hlist_del_rcu(&class->hash_entry);
4209 list_del_rcu(&class->lock_entry);
4211 RCU_INIT_POINTER(class->key, NULL);
4212 RCU_INIT_POINTER(class->name, NULL);
4215 static inline int within(const void *addr, void *start, unsigned long size)
4217 return addr >= start && addr < start + size;
4221 * Used in module.c to remove lock classes from memory that is going to be
4222 * freed; and possibly re-used by other modules.
4224 * We will have had one sync_sched() before getting here, so we're guaranteed
4225 * nobody will look up these exact classes -- they're properly dead but still
4228 void lockdep_free_key_range(void *start, unsigned long size)
4230 struct lock_class *class;
4231 struct hlist_head *head;
4232 unsigned long flags;
4236 raw_local_irq_save(flags);
4237 locked = graph_lock();
4240 * Unhash all classes that were created by this module:
4242 for (i = 0; i < CLASSHASH_SIZE; i++) {
4243 head = classhash_table + i;
4244 hlist_for_each_entry_rcu(class, head, hash_entry) {
4245 if (within(class->key, start, size))
4247 else if (within(class->name, start, size))
4254 raw_local_irq_restore(flags);
4257 * Wait for any possible iterators from look_up_lock_class() to pass
4258 * before continuing to free the memory they refer to.
4260 * sync_sched() is sufficient because the read-side is IRQ disable.
4262 synchronize_sched();
4265 * XXX at this point we could return the resources to the pool;
4266 * instead we leak them. We would need to change to bitmap allocators
4267 * instead of the linear allocators we have now.
4271 void lockdep_reset_lock(struct lockdep_map *lock)
4273 struct lock_class *class;
4274 struct hlist_head *head;
4275 unsigned long flags;
4279 raw_local_irq_save(flags);
4282 * Remove all classes this lock might have:
4284 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
4286 * If the class exists we look it up and zap it:
4288 class = look_up_lock_class(lock, j);
4293 * Debug check: in the end all mapped classes should
4296 locked = graph_lock();
4297 for (i = 0; i < CLASSHASH_SIZE; i++) {
4298 head = classhash_table + i;
4299 hlist_for_each_entry_rcu(class, head, hash_entry) {
4302 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
4303 match |= class == lock->class_cache[j];
4305 if (unlikely(match)) {
4306 if (debug_locks_off_graph_unlock()) {
4308 * We all just reset everything, how did it match?
4320 raw_local_irq_restore(flags);
4323 void __init lockdep_init(void)
4325 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4327 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
4328 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
4329 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
4330 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
4331 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
4332 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
4333 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
4335 printk(" memory used by lock dependency info: %lu kB\n",
4336 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4337 sizeof(struct list_head) * CLASSHASH_SIZE +
4338 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4339 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4340 sizeof(struct list_head) * CHAINHASH_SIZE
4341 #ifdef CONFIG_PROVE_LOCKING
4342 + sizeof(struct circular_queue)
4347 printk(" per task-struct memory footprint: %lu bytes\n",
4348 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4352 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4353 const void *mem_to, struct held_lock *hlock)
4355 if (!debug_locks_off())
4357 if (debug_locks_silent)
4361 pr_warn("=========================\n");
4362 pr_warn("WARNING: held lock freed!\n");
4363 print_kernel_ident();
4364 pr_warn("-------------------------\n");
4365 pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
4366 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4368 lockdep_print_held_locks(curr);
4370 pr_warn("\nstack backtrace:\n");
4374 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4375 const void* lock_from, unsigned long lock_len)
4377 return lock_from + lock_len <= mem_from ||
4378 mem_from + mem_len <= lock_from;
4382 * Called when kernel memory is freed (or unmapped), or if a lock
4383 * is destroyed or reinitialized - this code checks whether there is
4384 * any held lock in the memory range of <from> to <to>:
4386 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4388 struct task_struct *curr = current;
4389 struct held_lock *hlock;
4390 unsigned long flags;
4393 if (unlikely(!debug_locks))
4396 raw_local_irq_save(flags);
4397 for (i = 0; i < curr->lockdep_depth; i++) {
4398 hlock = curr->held_locks + i;
4400 if (not_in_range(mem_from, mem_len, hlock->instance,
4401 sizeof(*hlock->instance)))
4404 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4407 raw_local_irq_restore(flags);
4409 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4411 static void print_held_locks_bug(void)
4413 if (!debug_locks_off())
4415 if (debug_locks_silent)
4419 pr_warn("====================================\n");
4420 pr_warn("WARNING: %s/%d still has locks held!\n",
4421 current->comm, task_pid_nr(current));
4422 print_kernel_ident();
4423 pr_warn("------------------------------------\n");
4424 lockdep_print_held_locks(current);
4425 pr_warn("\nstack backtrace:\n");
4429 void debug_check_no_locks_held(void)
4431 if (unlikely(current->lockdep_depth > 0))
4432 print_held_locks_bug();
4434 EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
4437 void debug_show_all_locks(void)
4439 struct task_struct *g, *p;
4441 if (unlikely(!debug_locks)) {
4442 pr_warn("INFO: lockdep is turned off.\n");
4445 pr_warn("\nShowing all locks held in the system:\n");
4448 for_each_process_thread(g, p) {
4449 if (!p->lockdep_depth)
4451 lockdep_print_held_locks(p);
4452 touch_nmi_watchdog();
4453 touch_all_softlockup_watchdogs();
4458 pr_warn("=============================================\n\n");
4460 EXPORT_SYMBOL_GPL(debug_show_all_locks);
4464 * Careful: only use this function if you are sure that
4465 * the task cannot run in parallel!
4467 void debug_show_held_locks(struct task_struct *task)
4469 if (unlikely(!debug_locks)) {
4470 printk("INFO: lockdep is turned off.\n");
4473 lockdep_print_held_locks(task);
4475 EXPORT_SYMBOL_GPL(debug_show_held_locks);
4477 asmlinkage __visible void lockdep_sys_exit(void)
4479 struct task_struct *curr = current;
4481 if (unlikely(curr->lockdep_depth)) {
4482 if (!debug_locks_off())
4485 pr_warn("================================================\n");
4486 pr_warn("WARNING: lock held when returning to user space!\n");
4487 print_kernel_ident();
4488 pr_warn("------------------------------------------------\n");
4489 pr_warn("%s/%d is leaving the kernel with locks still held!\n",
4490 curr->comm, curr->pid);
4491 lockdep_print_held_locks(curr);
4495 * The lock history for each syscall should be independent. So wipe the
4496 * slate clean on return to userspace.
4498 lockdep_invariant_state(false);
4501 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4503 struct task_struct *curr = current;
4505 /* Note: the following can be executed concurrently, so be careful. */
4507 pr_warn("=============================\n");
4508 pr_warn("WARNING: suspicious RCU usage\n");
4509 print_kernel_ident();
4510 pr_warn("-----------------------------\n");
4511 pr_warn("%s:%d %s!\n", file, line, s);
4512 pr_warn("\nother info that might help us debug this:\n\n");
4513 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4514 !rcu_lockdep_current_cpu_online()
4515 ? "RCU used illegally from offline CPU!\n"
4516 : !rcu_is_watching()
4517 ? "RCU used illegally from idle CPU!\n"
4519 rcu_scheduler_active, debug_locks);
4522 * If a CPU is in the RCU-free window in idle (ie: in the section
4523 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4524 * considers that CPU to be in an "extended quiescent state",
4525 * which means that RCU will be completely ignoring that CPU.
4526 * Therefore, rcu_read_lock() and friends have absolutely no
4527 * effect on a CPU running in that state. In other words, even if
4528 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4529 * delete data structures out from under it. RCU really has no
4530 * choice here: we need to keep an RCU-free window in idle where
4531 * the CPU may possibly enter into low power mode. This way we can
4532 * notice an extended quiescent state to other CPUs that started a grace
4533 * period. Otherwise we would delay any grace period as long as we run
4536 * So complain bitterly if someone does call rcu_read_lock(),
4537 * rcu_read_lock_bh() and so on from extended quiescent states.
4539 if (!rcu_is_watching())
4540 pr_warn("RCU used illegally from extended quiescent state!\n");
4542 lockdep_print_held_locks(curr);
4543 pr_warn("\nstack backtrace:\n");
4546 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);