1 // SPDX-License-Identifier: GPL-2.0-only
5 * Runtime locking correctness validator
7 * Started by Ingo Molnar:
9 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
10 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
12 * this code maps all the lock dependencies as they occur in a live kernel
13 * and will warn about the following classes of locking bugs:
15 * - lock inversion scenarios
16 * - circular lock dependencies
17 * - hardirq/softirq safe/unsafe locking bugs
19 * Bugs are reported even if the current locking scenario does not cause
20 * any deadlock at this point.
22 * I.e. if anytime in the past two locks were taken in a different order,
23 * even if it happened for another task, even if those were different
24 * locks (but of the same class as this lock), this code will detect it.
26 * Thanks to Arjan van de Ven for coming up with the initial idea of
27 * mapping lock dependencies runtime.
29 #define DISABLE_BRANCH_PROFILING
30 #include <linux/mutex.h>
31 #include <linux/sched.h>
32 #include <linux/sched/clock.h>
33 #include <linux/sched/task.h>
34 #include <linux/sched/mm.h>
35 #include <linux/delay.h>
36 #include <linux/module.h>
37 #include <linux/proc_fs.h>
38 #include <linux/seq_file.h>
39 #include <linux/spinlock.h>
40 #include <linux/kallsyms.h>
41 #include <linux/interrupt.h>
42 #include <linux/stacktrace.h>
43 #include <linux/debug_locks.h>
44 #include <linux/irqflags.h>
45 #include <linux/utsname.h>
46 #include <linux/hash.h>
47 #include <linux/ftrace.h>
48 #include <linux/stringify.h>
49 #include <linux/bitmap.h>
50 #include <linux/bitops.h>
51 #include <linux/gfp.h>
52 #include <linux/random.h>
53 #include <linux/jhash.h>
54 #include <linux/nmi.h>
55 #include <linux/rcupdate.h>
56 #include <linux/kprobes.h>
58 #include <asm/sections.h>
60 #include "lockdep_internals.h"
62 #define CREATE_TRACE_POINTS
63 #include <trace/events/lock.h>
65 #ifdef CONFIG_PROVE_LOCKING
66 int prove_locking = 1;
67 module_param(prove_locking, int, 0644);
69 #define prove_locking 0
72 #ifdef CONFIG_LOCK_STAT
74 module_param(lock_stat, int, 0644);
79 DEFINE_PER_CPU(unsigned int, lockdep_recursion);
80 EXPORT_PER_CPU_SYMBOL_GPL(lockdep_recursion);
82 static __always_inline bool lockdep_enabled(void)
87 if (this_cpu_read(lockdep_recursion))
90 if (current->lockdep_recursion)
97 * lockdep_lock: protects the lockdep graph, the hashes and the
98 * class/list/hash allocators.
100 * This is one of the rare exceptions where it's justified
101 * to use a raw spinlock - we really dont want the spinlock
102 * code to recurse back into the lockdep code...
104 static arch_spinlock_t __lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
105 static struct task_struct *__owner;
107 static inline void lockdep_lock(void)
109 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
111 __this_cpu_inc(lockdep_recursion);
112 arch_spin_lock(&__lock);
116 static inline void lockdep_unlock(void)
118 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
120 if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current))
124 arch_spin_unlock(&__lock);
125 __this_cpu_dec(lockdep_recursion);
128 static inline bool lockdep_assert_locked(void)
130 return DEBUG_LOCKS_WARN_ON(__owner != current);
133 static struct task_struct *lockdep_selftest_task_struct;
136 static int graph_lock(void)
140 * Make sure that if another CPU detected a bug while
141 * walking the graph we dont change it (while the other
142 * CPU is busy printing out stuff with the graph lock
152 static inline void graph_unlock(void)
158 * Turn lock debugging off and return with 0 if it was off already,
159 * and also release the graph lock:
161 static inline int debug_locks_off_graph_unlock(void)
163 int ret = debug_locks_off();
170 unsigned long nr_list_entries;
171 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
172 static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES);
175 * All data structures here are protected by the global debug_lock.
177 * nr_lock_classes is the number of elements of lock_classes[] that is
180 #define KEYHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
181 #define KEYHASH_SIZE (1UL << KEYHASH_BITS)
182 static struct hlist_head lock_keys_hash[KEYHASH_SIZE];
183 unsigned long nr_lock_classes;
184 unsigned long nr_zapped_classes;
185 #ifndef CONFIG_DEBUG_LOCKDEP
188 struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
189 static DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS);
191 static inline struct lock_class *hlock_class(struct held_lock *hlock)
193 unsigned int class_idx = hlock->class_idx;
195 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfield */
198 if (!test_bit(class_idx, lock_classes_in_use)) {
200 * Someone passed in garbage, we give up.
202 DEBUG_LOCKS_WARN_ON(1);
207 * At this point, if the passed hlock->class_idx is still garbage,
208 * we just have to live with it
210 return lock_classes + class_idx;
213 #ifdef CONFIG_LOCK_STAT
214 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
216 static inline u64 lockstat_clock(void)
218 return local_clock();
221 static int lock_point(unsigned long points[], unsigned long ip)
225 for (i = 0; i < LOCKSTAT_POINTS; i++) {
226 if (points[i] == 0) {
237 static void lock_time_inc(struct lock_time *lt, u64 time)
242 if (time < lt->min || !lt->nr)
249 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
254 if (src->max > dst->max)
257 if (src->min < dst->min || !dst->nr)
260 dst->total += src->total;
264 struct lock_class_stats lock_stats(struct lock_class *class)
266 struct lock_class_stats stats;
269 memset(&stats, 0, sizeof(struct lock_class_stats));
270 for_each_possible_cpu(cpu) {
271 struct lock_class_stats *pcs =
272 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
274 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
275 stats.contention_point[i] += pcs->contention_point[i];
277 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
278 stats.contending_point[i] += pcs->contending_point[i];
280 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
281 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
283 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
284 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
286 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
287 stats.bounces[i] += pcs->bounces[i];
293 void clear_lock_stats(struct lock_class *class)
297 for_each_possible_cpu(cpu) {
298 struct lock_class_stats *cpu_stats =
299 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
301 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
303 memset(class->contention_point, 0, sizeof(class->contention_point));
304 memset(class->contending_point, 0, sizeof(class->contending_point));
307 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
309 return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes];
312 static void lock_release_holdtime(struct held_lock *hlock)
314 struct lock_class_stats *stats;
320 holdtime = lockstat_clock() - hlock->holdtime_stamp;
322 stats = get_lock_stats(hlock_class(hlock));
324 lock_time_inc(&stats->read_holdtime, holdtime);
326 lock_time_inc(&stats->write_holdtime, holdtime);
329 static inline void lock_release_holdtime(struct held_lock *hlock)
335 * We keep a global list of all lock classes. The list is only accessed with
336 * the lockdep spinlock lock held. free_lock_classes is a list with free
337 * elements. These elements are linked together by the lock_entry member in
340 LIST_HEAD(all_lock_classes);
341 static LIST_HEAD(free_lock_classes);
344 * struct pending_free - information about data structures about to be freed
345 * @zapped: Head of a list with struct lock_class elements.
346 * @lock_chains_being_freed: Bitmap that indicates which lock_chains[] elements
347 * are about to be freed.
349 struct pending_free {
350 struct list_head zapped;
351 DECLARE_BITMAP(lock_chains_being_freed, MAX_LOCKDEP_CHAINS);
355 * struct delayed_free - data structures used for delayed freeing
357 * A data structure for delayed freeing of data structures that may be
358 * accessed by RCU readers at the time these were freed.
360 * @rcu_head: Used to schedule an RCU callback for freeing data structures.
361 * @index: Index of @pf to which freed data structures are added.
362 * @scheduled: Whether or not an RCU callback has been scheduled.
363 * @pf: Array with information about data structures about to be freed.
365 static struct delayed_free {
366 struct rcu_head rcu_head;
369 struct pending_free pf[2];
373 * The lockdep classes are in a hash-table as well, for fast lookup:
375 #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
376 #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
377 #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
378 #define classhashentry(key) (classhash_table + __classhashfn((key)))
380 static struct hlist_head classhash_table[CLASSHASH_SIZE];
383 * We put the lock dependency chains into a hash-table as well, to cache
386 #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
387 #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
388 #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
389 #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
391 static struct hlist_head chainhash_table[CHAINHASH_SIZE];
394 * the id of held_lock
396 static inline u16 hlock_id(struct held_lock *hlock)
398 BUILD_BUG_ON(MAX_LOCKDEP_KEYS_BITS + 2 > 16);
400 return (hlock->class_idx | (hlock->read << MAX_LOCKDEP_KEYS_BITS));
403 static inline unsigned int chain_hlock_class_idx(u16 hlock_id)
405 return hlock_id & (MAX_LOCKDEP_KEYS - 1);
409 * The hash key of the lock dependency chains is a hash itself too:
410 * it's a hash of all locks taken up to that lock, including that lock.
411 * It's a 64-bit hash, because it's important for the keys to be
414 static inline u64 iterate_chain_key(u64 key, u32 idx)
416 u32 k0 = key, k1 = key >> 32;
418 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
420 return k0 | (u64)k1 << 32;
423 void lockdep_init_task(struct task_struct *task)
425 task->lockdep_depth = 0; /* no locks held yet */
426 task->curr_chain_key = INITIAL_CHAIN_KEY;
427 task->lockdep_recursion = 0;
430 static __always_inline void lockdep_recursion_inc(void)
432 __this_cpu_inc(lockdep_recursion);
435 static __always_inline void lockdep_recursion_finish(void)
437 if (WARN_ON_ONCE(__this_cpu_dec_return(lockdep_recursion)))
438 __this_cpu_write(lockdep_recursion, 0);
441 void lockdep_set_selftest_task(struct task_struct *task)
443 lockdep_selftest_task_struct = task;
447 * Debugging switches:
451 #define VERY_VERBOSE 0
454 # define HARDIRQ_VERBOSE 1
455 # define SOFTIRQ_VERBOSE 1
457 # define HARDIRQ_VERBOSE 0
458 # define SOFTIRQ_VERBOSE 0
461 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
463 * Quick filtering for interesting events:
465 static int class_filter(struct lock_class *class)
469 if (class->name_version == 1 &&
470 !strcmp(class->name, "lockname"))
472 if (class->name_version == 1 &&
473 !strcmp(class->name, "&struct->lockfield"))
476 /* Filter everything else. 1 would be to allow everything else */
481 static int verbose(struct lock_class *class)
484 return class_filter(class);
489 static void print_lockdep_off(const char *bug_msg)
491 printk(KERN_DEBUG "%s\n", bug_msg);
492 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
493 #ifdef CONFIG_LOCK_STAT
494 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
498 unsigned long nr_stack_trace_entries;
500 #ifdef CONFIG_PROVE_LOCKING
502 * struct lock_trace - single stack backtrace
503 * @hash_entry: Entry in a stack_trace_hash[] list.
504 * @hash: jhash() of @entries.
505 * @nr_entries: Number of entries in @entries.
506 * @entries: Actual stack backtrace.
509 struct hlist_node hash_entry;
512 unsigned long entries[] __aligned(sizeof(unsigned long));
514 #define LOCK_TRACE_SIZE_IN_LONGS \
515 (sizeof(struct lock_trace) / sizeof(unsigned long))
517 * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock.
519 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
520 static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE];
522 static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2)
524 return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries &&
525 memcmp(t1->entries, t2->entries,
526 t1->nr_entries * sizeof(t1->entries[0])) == 0;
529 static struct lock_trace *save_trace(void)
531 struct lock_trace *trace, *t2;
532 struct hlist_head *hash_head;
536 BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE);
537 BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES);
539 trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries);
540 max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries -
541 LOCK_TRACE_SIZE_IN_LONGS;
543 if (max_entries <= 0) {
544 if (!debug_locks_off_graph_unlock())
547 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
552 trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
554 hash = jhash(trace->entries, trace->nr_entries *
555 sizeof(trace->entries[0]), 0);
557 hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1));
558 hlist_for_each_entry(t2, hash_head, hash_entry) {
559 if (traces_identical(trace, t2))
562 nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries;
563 hlist_add_head(&trace->hash_entry, hash_head);
568 /* Return the number of stack traces in the stack_trace[] array. */
569 u64 lockdep_stack_trace_count(void)
571 struct lock_trace *trace;
575 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) {
576 hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) {
584 /* Return the number of stack hash chains that have at least one stack trace. */
585 u64 lockdep_stack_hash_count(void)
590 for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++)
591 if (!hlist_empty(&stack_trace_hash[i]))
598 unsigned int nr_hardirq_chains;
599 unsigned int nr_softirq_chains;
600 unsigned int nr_process_chains;
601 unsigned int max_lockdep_depth;
603 #ifdef CONFIG_DEBUG_LOCKDEP
605 * Various lockdep statistics:
607 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
610 #ifdef CONFIG_PROVE_LOCKING
615 #define __USAGE(__STATE) \
616 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
617 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
618 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
619 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
621 static const char *usage_str[] =
623 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
624 #include "lockdep_states.h"
626 [LOCK_USED] = "INITIAL USE",
627 [LOCK_USED_READ] = "INITIAL READ USE",
628 /* abused as string storage for verify_lock_unused() */
629 [LOCK_USAGE_STATES] = "IN-NMI",
633 const char *__get_key_name(const struct lockdep_subclass_key *key, char *str)
635 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
638 static inline unsigned long lock_flag(enum lock_usage_bit bit)
643 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
646 * The usage character defaults to '.' (i.e., irqs disabled and not in
647 * irq context), which is the safest usage category.
652 * The order of the following usage checks matters, which will
653 * result in the outcome character as follows:
655 * - '+': irq is enabled and not in irq context
656 * - '-': in irq context and irq is disabled
657 * - '?': in irq context and irq is enabled
659 if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) {
661 if (class->usage_mask & lock_flag(bit))
663 } else if (class->usage_mask & lock_flag(bit))
669 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
673 #define LOCKDEP_STATE(__STATE) \
674 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
675 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
676 #include "lockdep_states.h"
682 static void __print_lock_name(struct lock_class *class)
684 char str[KSYM_NAME_LEN];
689 name = __get_key_name(class->key, str);
690 printk(KERN_CONT "%s", name);
692 printk(KERN_CONT "%s", name);
693 if (class->name_version > 1)
694 printk(KERN_CONT "#%d", class->name_version);
696 printk(KERN_CONT "/%d", class->subclass);
700 static void print_lock_name(struct lock_class *class)
702 char usage[LOCK_USAGE_CHARS];
704 get_usage_chars(class, usage);
706 printk(KERN_CONT " (");
707 __print_lock_name(class);
708 printk(KERN_CONT "){%s}-{%hd:%hd}", usage,
709 class->wait_type_outer ?: class->wait_type_inner,
710 class->wait_type_inner);
713 static void print_lockdep_cache(struct lockdep_map *lock)
716 char str[KSYM_NAME_LEN];
720 name = __get_key_name(lock->key->subkeys, str);
722 printk(KERN_CONT "%s", name);
725 static void print_lock(struct held_lock *hlock)
728 * We can be called locklessly through debug_show_all_locks() so be
729 * extra careful, the hlock might have been released and cleared.
731 * If this indeed happens, lets pretend it does not hurt to continue
732 * to print the lock unless the hlock class_idx does not point to a
733 * registered class. The rationale here is: since we don't attempt
734 * to distinguish whether we are in this situation, if it just
735 * happened we can't count on class_idx to tell either.
737 struct lock_class *lock = hlock_class(hlock);
740 printk(KERN_CONT "<RELEASED>\n");
744 printk(KERN_CONT "%px", hlock->instance);
745 print_lock_name(lock);
746 printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
749 static void lockdep_print_held_locks(struct task_struct *p)
751 int i, depth = READ_ONCE(p->lockdep_depth);
754 printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p));
756 printk("%d lock%s held by %s/%d:\n", depth,
757 depth > 1 ? "s" : "", p->comm, task_pid_nr(p));
759 * It's not reliable to print a task's held locks if it's not sleeping
760 * and it's not the current task.
762 if (p->state == TASK_RUNNING && p != current)
764 for (i = 0; i < depth; i++) {
766 print_lock(p->held_locks + i);
770 static void print_kernel_ident(void)
772 printk("%s %.*s %s\n", init_utsname()->release,
773 (int)strcspn(init_utsname()->version, " "),
774 init_utsname()->version,
778 static int very_verbose(struct lock_class *class)
781 return class_filter(class);
787 * Is this the address of a static object:
790 static int static_obj(const void *obj)
792 unsigned long start = (unsigned long) &_stext,
793 end = (unsigned long) &_end,
794 addr = (unsigned long) obj;
796 if (arch_is_kernel_initmem_freed(addr))
802 if ((addr >= start) && (addr < end))
805 if (arch_is_kernel_data(addr))
809 * in-kernel percpu var?
811 if (is_kernel_percpu_address(addr))
815 * module static or percpu var?
817 return is_module_address(addr) || is_module_percpu_address(addr);
822 * To make lock name printouts unique, we calculate a unique
823 * class->name_version generation counter. The caller must hold the graph
826 static int count_matching_names(struct lock_class *new_class)
828 struct lock_class *class;
831 if (!new_class->name)
834 list_for_each_entry(class, &all_lock_classes, lock_entry) {
835 if (new_class->key - new_class->subclass == class->key)
836 return class->name_version;
837 if (class->name && !strcmp(class->name, new_class->name))
838 count = max(count, class->name_version);
844 /* used from NMI context -- must be lockless */
845 static __always_inline struct lock_class *
846 look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
848 struct lockdep_subclass_key *key;
849 struct hlist_head *hash_head;
850 struct lock_class *class;
852 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
855 "BUG: looking up invalid subclass: %u\n", subclass);
857 "turning off the locking correctness validator.\n");
863 * If it is not initialised then it has never been locked,
864 * so it won't be present in the hash table.
866 if (unlikely(!lock->key))
870 * NOTE: the class-key must be unique. For dynamic locks, a static
871 * lock_class_key variable is passed in through the mutex_init()
872 * (or spin_lock_init()) call - which acts as the key. For static
873 * locks we use the lock object itself as the key.
875 BUILD_BUG_ON(sizeof(struct lock_class_key) >
876 sizeof(struct lockdep_map));
878 key = lock->key->subkeys + subclass;
880 hash_head = classhashentry(key);
883 * We do an RCU walk of the hash, see lockdep_free_key_range().
885 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
888 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
889 if (class->key == key) {
891 * Huh! same key, different name? Did someone trample
892 * on some memory? We're most confused.
894 WARN_ON_ONCE(class->name != lock->name &&
895 lock->key != &__lockdep_no_validate__);
904 * Static locks do not have their class-keys yet - for them the key is
905 * the lock object itself. If the lock is in the per cpu area, the
906 * canonical address of the lock (per cpu offset removed) is used.
908 static bool assign_lock_key(struct lockdep_map *lock)
910 unsigned long can_addr, addr = (unsigned long)lock;
914 * lockdep_free_key_range() assumes that struct lock_class_key
915 * objects do not overlap. Since we use the address of lock
916 * objects as class key for static objects, check whether the
917 * size of lock_class_key objects does not exceed the size of
918 * the smallest lock object.
920 BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
923 if (__is_kernel_percpu_address(addr, &can_addr))
924 lock->key = (void *)can_addr;
925 else if (__is_module_percpu_address(addr, &can_addr))
926 lock->key = (void *)can_addr;
927 else if (static_obj(lock))
928 lock->key = (void *)lock;
930 /* Debug-check: all keys must be persistent! */
932 pr_err("INFO: trying to register non-static key.\n");
933 pr_err("the code is fine but needs lockdep annotation.\n");
934 pr_err("turning off the locking correctness validator.\n");
942 #ifdef CONFIG_DEBUG_LOCKDEP
944 /* Check whether element @e occurs in list @h */
945 static bool in_list(struct list_head *e, struct list_head *h)
949 list_for_each(f, h) {
958 * Check whether entry @e occurs in any of the locks_after or locks_before
961 static bool in_any_class_list(struct list_head *e)
963 struct lock_class *class;
966 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
967 class = &lock_classes[i];
968 if (in_list(e, &class->locks_after) ||
969 in_list(e, &class->locks_before))
975 static bool class_lock_list_valid(struct lock_class *c, struct list_head *h)
979 list_for_each_entry(e, h, entry) {
980 if (e->links_to != c) {
981 printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s",
983 (unsigned long)(e - list_entries),
984 e->links_to && e->links_to->name ?
985 e->links_to->name : "(?)",
986 e->class && e->class->name ? e->class->name :
994 #ifdef CONFIG_PROVE_LOCKING
995 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
998 static bool check_lock_chain_key(struct lock_chain *chain)
1000 #ifdef CONFIG_PROVE_LOCKING
1001 u64 chain_key = INITIAL_CHAIN_KEY;
1004 for (i = chain->base; i < chain->base + chain->depth; i++)
1005 chain_key = iterate_chain_key(chain_key, chain_hlocks[i]);
1007 * The 'unsigned long long' casts avoid that a compiler warning
1008 * is reported when building tools/lib/lockdep.
1010 if (chain->chain_key != chain_key) {
1011 printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n",
1012 (unsigned long long)(chain - lock_chains),
1013 (unsigned long long)chain->chain_key,
1014 (unsigned long long)chain_key);
1021 static bool in_any_zapped_class_list(struct lock_class *class)
1023 struct pending_free *pf;
1026 for (i = 0, pf = delayed_free.pf; i < ARRAY_SIZE(delayed_free.pf); i++, pf++) {
1027 if (in_list(&class->lock_entry, &pf->zapped))
1034 static bool __check_data_structures(void)
1036 struct lock_class *class;
1037 struct lock_chain *chain;
1038 struct hlist_head *head;
1039 struct lock_list *e;
1042 /* Check whether all classes occur in a lock list. */
1043 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1044 class = &lock_classes[i];
1045 if (!in_list(&class->lock_entry, &all_lock_classes) &&
1046 !in_list(&class->lock_entry, &free_lock_classes) &&
1047 !in_any_zapped_class_list(class)) {
1048 printk(KERN_INFO "class %px/%s is not in any class list\n",
1049 class, class->name ? : "(?)");
1054 /* Check whether all classes have valid lock lists. */
1055 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1056 class = &lock_classes[i];
1057 if (!class_lock_list_valid(class, &class->locks_before))
1059 if (!class_lock_list_valid(class, &class->locks_after))
1063 /* Check the chain_key of all lock chains. */
1064 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
1065 head = chainhash_table + i;
1066 hlist_for_each_entry_rcu(chain, head, entry) {
1067 if (!check_lock_chain_key(chain))
1073 * Check whether all list entries that are in use occur in a class
1076 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1077 e = list_entries + i;
1078 if (!in_any_class_list(&e->entry)) {
1079 printk(KERN_INFO "list entry %d is not in any class list; class %s <> %s\n",
1080 (unsigned int)(e - list_entries),
1081 e->class->name ? : "(?)",
1082 e->links_to->name ? : "(?)");
1088 * Check whether all list entries that are not in use do not occur in
1089 * a class lock list.
1091 for_each_clear_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
1092 e = list_entries + i;
1093 if (in_any_class_list(&e->entry)) {
1094 printk(KERN_INFO "list entry %d occurs in a class list; class %s <> %s\n",
1095 (unsigned int)(e - list_entries),
1096 e->class && e->class->name ? e->class->name :
1098 e->links_to && e->links_to->name ?
1099 e->links_to->name : "(?)");
1107 int check_consistency = 0;
1108 module_param(check_consistency, int, 0644);
1110 static void check_data_structures(void)
1112 static bool once = false;
1114 if (check_consistency && !once) {
1115 if (!__check_data_structures()) {
1122 #else /* CONFIG_DEBUG_LOCKDEP */
1124 static inline void check_data_structures(void) { }
1126 #endif /* CONFIG_DEBUG_LOCKDEP */
1128 static void init_chain_block_buckets(void);
1131 * Initialize the lock_classes[] array elements, the free_lock_classes list
1132 * and also the delayed_free structure.
1134 static void init_data_structures_once(void)
1136 static bool __read_mostly ds_initialized, rcu_head_initialized;
1139 if (likely(rcu_head_initialized))
1142 if (system_state >= SYSTEM_SCHEDULING) {
1143 init_rcu_head(&delayed_free.rcu_head);
1144 rcu_head_initialized = true;
1150 ds_initialized = true;
1152 INIT_LIST_HEAD(&delayed_free.pf[0].zapped);
1153 INIT_LIST_HEAD(&delayed_free.pf[1].zapped);
1155 for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
1156 list_add_tail(&lock_classes[i].lock_entry, &free_lock_classes);
1157 INIT_LIST_HEAD(&lock_classes[i].locks_after);
1158 INIT_LIST_HEAD(&lock_classes[i].locks_before);
1160 init_chain_block_buckets();
1163 static inline struct hlist_head *keyhashentry(const struct lock_class_key *key)
1165 unsigned long hash = hash_long((uintptr_t)key, KEYHASH_BITS);
1167 return lock_keys_hash + hash;
1170 /* Register a dynamically allocated key. */
1171 void lockdep_register_key(struct lock_class_key *key)
1173 struct hlist_head *hash_head;
1174 struct lock_class_key *k;
1175 unsigned long flags;
1177 if (WARN_ON_ONCE(static_obj(key)))
1179 hash_head = keyhashentry(key);
1181 raw_local_irq_save(flags);
1184 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1185 if (WARN_ON_ONCE(k == key))
1188 hlist_add_head_rcu(&key->hash_entry, hash_head);
1192 raw_local_irq_restore(flags);
1194 EXPORT_SYMBOL_GPL(lockdep_register_key);
1196 /* Check whether a key has been registered as a dynamic key. */
1197 static bool is_dynamic_key(const struct lock_class_key *key)
1199 struct hlist_head *hash_head;
1200 struct lock_class_key *k;
1203 if (WARN_ON_ONCE(static_obj(key)))
1207 * If lock debugging is disabled lock_keys_hash[] may contain
1208 * pointers to memory that has already been freed. Avoid triggering
1209 * a use-after-free in that case by returning early.
1214 hash_head = keyhashentry(key);
1217 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
1229 * Register a lock's class in the hash-table, if the class is not present
1230 * yet. Otherwise we look it up. We cache the result in the lock object
1231 * itself, so actual lookup of the hash should be once per lock object.
1233 static struct lock_class *
1234 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
1236 struct lockdep_subclass_key *key;
1237 struct hlist_head *hash_head;
1238 struct lock_class *class;
1240 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1242 class = look_up_lock_class(lock, subclass);
1244 goto out_set_class_cache;
1247 if (!assign_lock_key(lock))
1249 } else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) {
1253 key = lock->key->subkeys + subclass;
1254 hash_head = classhashentry(key);
1256 if (!graph_lock()) {
1260 * We have to do the hash-walk again, to avoid races
1263 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
1264 if (class->key == key)
1265 goto out_unlock_set;
1268 init_data_structures_once();
1270 /* Allocate a new lock class and add it to the hash. */
1271 class = list_first_entry_or_null(&free_lock_classes, typeof(*class),
1274 if (!debug_locks_off_graph_unlock()) {
1278 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
1283 __set_bit(class - lock_classes, lock_classes_in_use);
1284 debug_atomic_inc(nr_unused_locks);
1286 class->name = lock->name;
1287 class->subclass = subclass;
1288 WARN_ON_ONCE(!list_empty(&class->locks_before));
1289 WARN_ON_ONCE(!list_empty(&class->locks_after));
1290 class->name_version = count_matching_names(class);
1291 class->wait_type_inner = lock->wait_type_inner;
1292 class->wait_type_outer = lock->wait_type_outer;
1293 class->lock_type = lock->lock_type;
1295 * We use RCU's safe list-add method to make
1296 * parallel walking of the hash-list safe:
1298 hlist_add_head_rcu(&class->hash_entry, hash_head);
1300 * Remove the class from the free list and add it to the global list
1303 list_move_tail(&class->lock_entry, &all_lock_classes);
1305 if (verbose(class)) {
1308 printk("\nnew class %px: %s", class->key, class->name);
1309 if (class->name_version > 1)
1310 printk(KERN_CONT "#%d", class->name_version);
1311 printk(KERN_CONT "\n");
1314 if (!graph_lock()) {
1321 out_set_class_cache:
1322 if (!subclass || force)
1323 lock->class_cache[0] = class;
1324 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
1325 lock->class_cache[subclass] = class;
1328 * Hash collision, did we smoke some? We found a class with a matching
1329 * hash but the subclass -- which is hashed in -- didn't match.
1331 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
1337 #ifdef CONFIG_PROVE_LOCKING
1339 * Allocate a lockdep entry. (assumes the graph_lock held, returns
1340 * with NULL on failure)
1342 static struct lock_list *alloc_list_entry(void)
1344 int idx = find_first_zero_bit(list_entries_in_use,
1345 ARRAY_SIZE(list_entries));
1347 if (idx >= ARRAY_SIZE(list_entries)) {
1348 if (!debug_locks_off_graph_unlock())
1351 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
1356 __set_bit(idx, list_entries_in_use);
1357 return list_entries + idx;
1361 * Add a new dependency to the head of the list:
1363 static int add_lock_to_list(struct lock_class *this,
1364 struct lock_class *links_to, struct list_head *head,
1365 unsigned long ip, u16 distance, u8 dep,
1366 const struct lock_trace *trace)
1368 struct lock_list *entry;
1370 * Lock not present yet - get a new dependency struct and
1371 * add it to the list:
1373 entry = alloc_list_entry();
1377 entry->class = this;
1378 entry->links_to = links_to;
1380 entry->distance = distance;
1381 entry->trace = trace;
1383 * Both allocation and removal are done under the graph lock; but
1384 * iteration is under RCU-sched; see look_up_lock_class() and
1385 * lockdep_free_key_range().
1387 list_add_tail_rcu(&entry->entry, head);
1393 * For good efficiency of modular, we use power of 2
1395 #define MAX_CIRCULAR_QUEUE_SIZE 4096UL
1396 #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
1399 * The circular_queue and helpers are used to implement graph
1400 * breadth-first search (BFS) algorithm, by which we can determine
1401 * whether there is a path from a lock to another. In deadlock checks,
1402 * a path from the next lock to be acquired to a previous held lock
1403 * indicates that adding the <prev> -> <next> lock dependency will
1404 * produce a circle in the graph. Breadth-first search instead of
1405 * depth-first search is used in order to find the shortest (circular)
1408 struct circular_queue {
1409 struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE];
1410 unsigned int front, rear;
1413 static struct circular_queue lock_cq;
1415 unsigned int max_bfs_queue_depth;
1417 static unsigned int lockdep_dependency_gen_id;
1419 static inline void __cq_init(struct circular_queue *cq)
1421 cq->front = cq->rear = 0;
1422 lockdep_dependency_gen_id++;
1425 static inline int __cq_empty(struct circular_queue *cq)
1427 return (cq->front == cq->rear);
1430 static inline int __cq_full(struct circular_queue *cq)
1432 return ((cq->rear + 1) & CQ_MASK) == cq->front;
1435 static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem)
1440 cq->element[cq->rear] = elem;
1441 cq->rear = (cq->rear + 1) & CQ_MASK;
1446 * Dequeue an element from the circular_queue, return a lock_list if
1447 * the queue is not empty, or NULL if otherwise.
1449 static inline struct lock_list * __cq_dequeue(struct circular_queue *cq)
1451 struct lock_list * lock;
1456 lock = cq->element[cq->front];
1457 cq->front = (cq->front + 1) & CQ_MASK;
1462 static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
1464 return (cq->rear - cq->front) & CQ_MASK;
1467 static inline void mark_lock_accessed(struct lock_list *lock)
1469 lock->class->dep_gen_id = lockdep_dependency_gen_id;
1472 static inline void visit_lock_entry(struct lock_list *lock,
1473 struct lock_list *parent)
1475 lock->parent = parent;
1478 static inline unsigned long lock_accessed(struct lock_list *lock)
1480 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
1483 static inline struct lock_list *get_lock_parent(struct lock_list *child)
1485 return child->parent;
1488 static inline int get_lock_depth(struct lock_list *child)
1491 struct lock_list *parent;
1493 while ((parent = get_lock_parent(child))) {
1501 * Return the forward or backward dependency list.
1503 * @lock: the lock_list to get its class's dependency list
1504 * @offset: the offset to struct lock_class to determine whether it is
1505 * locks_after or locks_before
1507 static inline struct list_head *get_dep_list(struct lock_list *lock, int offset)
1509 void *lock_class = lock->class;
1511 return lock_class + offset;
1514 * Return values of a bfs search:
1516 * BFS_E* indicates an error
1517 * BFS_R* indicates a result (match or not)
1519 * BFS_EINVALIDNODE: Find a invalid node in the graph.
1521 * BFS_EQUEUEFULL: The queue is full while doing the bfs.
1523 * BFS_RMATCH: Find the matched node in the graph, and put that node into
1526 * BFS_RNOMATCH: Haven't found the matched node and keep *@target_entry
1530 BFS_EINVALIDNODE = -2,
1531 BFS_EQUEUEFULL = -1,
1537 * bfs_result < 0 means error
1539 static inline bool bfs_error(enum bfs_result res)
1545 * DEP_*_BIT in lock_list::dep
1547 * For dependency @prev -> @next:
1549 * SR: @prev is shared reader (->read != 0) and @next is recursive reader
1551 * ER: @prev is exclusive locker (->read == 0) and @next is recursive reader
1552 * SN: @prev is shared reader and @next is non-recursive locker (->read != 2)
1553 * EN: @prev is exclusive locker and @next is non-recursive locker
1555 * Note that we define the value of DEP_*_BITs so that:
1556 * bit0 is prev->read == 0
1557 * bit1 is next->read != 2
1559 #define DEP_SR_BIT (0 + (0 << 1)) /* 0 */
1560 #define DEP_ER_BIT (1 + (0 << 1)) /* 1 */
1561 #define DEP_SN_BIT (0 + (1 << 1)) /* 2 */
1562 #define DEP_EN_BIT (1 + (1 << 1)) /* 3 */
1564 #define DEP_SR_MASK (1U << (DEP_SR_BIT))
1565 #define DEP_ER_MASK (1U << (DEP_ER_BIT))
1566 #define DEP_SN_MASK (1U << (DEP_SN_BIT))
1567 #define DEP_EN_MASK (1U << (DEP_EN_BIT))
1569 static inline unsigned int
1570 __calc_dep_bit(struct held_lock *prev, struct held_lock *next)
1572 return (prev->read == 0) + ((next->read != 2) << 1);
1575 static inline u8 calc_dep(struct held_lock *prev, struct held_lock *next)
1577 return 1U << __calc_dep_bit(prev, next);
1581 * calculate the dep_bit for backwards edges. We care about whether @prev is
1582 * shared and whether @next is recursive.
1584 static inline unsigned int
1585 __calc_dep_bitb(struct held_lock *prev, struct held_lock *next)
1587 return (next->read != 2) + ((prev->read == 0) << 1);
1590 static inline u8 calc_depb(struct held_lock *prev, struct held_lock *next)
1592 return 1U << __calc_dep_bitb(prev, next);
1596 * Initialize a lock_list entry @lock belonging to @class as the root for a BFS
1599 static inline void __bfs_init_root(struct lock_list *lock,
1600 struct lock_class *class)
1602 lock->class = class;
1603 lock->parent = NULL;
1608 * Initialize a lock_list entry @lock based on a lock acquisition @hlock as the
1609 * root for a BFS search.
1611 * ->only_xr of the initial lock node is set to @hlock->read == 2, to make sure
1612 * that <prev> -> @hlock and @hlock -> <whatever __bfs() found> is not -(*R)->
1615 static inline void bfs_init_root(struct lock_list *lock,
1616 struct held_lock *hlock)
1618 __bfs_init_root(lock, hlock_class(hlock));
1619 lock->only_xr = (hlock->read == 2);
1623 * Similar to bfs_init_root() but initialize the root for backwards BFS.
1625 * ->only_xr of the initial lock node is set to @hlock->read != 0, to make sure
1626 * that <next> -> @hlock and @hlock -> <whatever backwards BFS found> is not
1627 * -(*S)-> and -(R*)-> (reverse order of -(*R)-> and -(S*)->).
1629 static inline void bfs_init_rootb(struct lock_list *lock,
1630 struct held_lock *hlock)
1632 __bfs_init_root(lock, hlock_class(hlock));
1633 lock->only_xr = (hlock->read != 0);
1636 static inline struct lock_list *__bfs_next(struct lock_list *lock, int offset)
1638 if (!lock || !lock->parent)
1641 return list_next_or_null_rcu(get_dep_list(lock->parent, offset),
1642 &lock->entry, struct lock_list, entry);
1646 * Breadth-First Search to find a strong path in the dependency graph.
1648 * @source_entry: the source of the path we are searching for.
1649 * @data: data used for the second parameter of @match function
1650 * @match: match function for the search
1651 * @target_entry: pointer to the target of a matched path
1652 * @offset: the offset to struct lock_class to determine whether it is
1653 * locks_after or locks_before
1655 * We may have multiple edges (considering different kinds of dependencies,
1656 * e.g. ER and SN) between two nodes in the dependency graph. But
1657 * only the strong dependency path in the graph is relevant to deadlocks. A
1658 * strong dependency path is a dependency path that doesn't have two adjacent
1659 * dependencies as -(*R)-> -(S*)->, please see:
1661 * Documentation/locking/lockdep-design.rst
1663 * for more explanation of the definition of strong dependency paths
1665 * In __bfs(), we only traverse in the strong dependency path:
1667 * In lock_list::only_xr, we record whether the previous dependency only
1668 * has -(*R)-> in the search, and if it does (prev only has -(*R)->), we
1669 * filter out any -(S*)-> in the current dependency and after that, the
1670 * ->only_xr is set according to whether we only have -(*R)-> left.
1672 static enum bfs_result __bfs(struct lock_list *source_entry,
1674 bool (*match)(struct lock_list *entry, void *data),
1675 bool (*skip)(struct lock_list *entry, void *data),
1676 struct lock_list **target_entry,
1679 struct circular_queue *cq = &lock_cq;
1680 struct lock_list *lock = NULL;
1681 struct lock_list *entry;
1682 struct list_head *head;
1683 unsigned int cq_depth;
1686 lockdep_assert_locked();
1689 __cq_enqueue(cq, source_entry);
1691 while ((lock = __bfs_next(lock, offset)) || (lock = __cq_dequeue(cq))) {
1693 return BFS_EINVALIDNODE;
1696 * Step 1: check whether we already finish on this one.
1698 * If we have visited all the dependencies from this @lock to
1699 * others (iow, if we have visited all lock_list entries in
1700 * @lock->class->locks_{after,before}) we skip, otherwise go
1701 * and visit all the dependencies in the list and mark this
1704 if (lock_accessed(lock))
1707 mark_lock_accessed(lock);
1710 * Step 2: check whether prev dependency and this form a strong
1713 if (lock->parent) { /* Parent exists, check prev dependency */
1715 bool prev_only_xr = lock->parent->only_xr;
1718 * Mask out all -(S*)-> if we only have *R in previous
1719 * step, because -(*R)-> -(S*)-> don't make up a strong
1723 dep &= ~(DEP_SR_MASK | DEP_SN_MASK);
1725 /* If nothing left, we skip */
1729 /* If there are only -(*R)-> left, set that for the next step */
1730 lock->only_xr = !(dep & (DEP_SN_MASK | DEP_EN_MASK));
1734 * Step 3: we haven't visited this and there is a strong
1735 * dependency path to this, so check with @match.
1736 * If @skip is provide and returns true, we skip this
1737 * lock (and any path this lock is in).
1739 if (skip && skip(lock, data))
1742 if (match(lock, data)) {
1743 *target_entry = lock;
1748 * Step 4: if not match, expand the path by adding the
1749 * forward or backwards dependencis in the search
1753 head = get_dep_list(lock, offset);
1754 list_for_each_entry_rcu(entry, head, entry) {
1755 visit_lock_entry(entry, lock);
1758 * Note we only enqueue the first of the list into the
1759 * queue, because we can always find a sibling
1760 * dependency from one (see __bfs_next()), as a result
1761 * the space of queue is saved.
1768 if (__cq_enqueue(cq, entry))
1769 return BFS_EQUEUEFULL;
1771 cq_depth = __cq_get_elem_count(cq);
1772 if (max_bfs_queue_depth < cq_depth)
1773 max_bfs_queue_depth = cq_depth;
1777 return BFS_RNOMATCH;
1780 static inline enum bfs_result
1781 __bfs_forwards(struct lock_list *src_entry,
1783 bool (*match)(struct lock_list *entry, void *data),
1784 bool (*skip)(struct lock_list *entry, void *data),
1785 struct lock_list **target_entry)
1787 return __bfs(src_entry, data, match, skip, target_entry,
1788 offsetof(struct lock_class, locks_after));
1792 static inline enum bfs_result
1793 __bfs_backwards(struct lock_list *src_entry,
1795 bool (*match)(struct lock_list *entry, void *data),
1796 bool (*skip)(struct lock_list *entry, void *data),
1797 struct lock_list **target_entry)
1799 return __bfs(src_entry, data, match, skip, target_entry,
1800 offsetof(struct lock_class, locks_before));
1804 static void print_lock_trace(const struct lock_trace *trace,
1805 unsigned int spaces)
1807 stack_trace_print(trace->entries, trace->nr_entries, spaces);
1811 * Print a dependency chain entry (this is only done when a deadlock
1812 * has been detected):
1814 static noinline void
1815 print_circular_bug_entry(struct lock_list *target, int depth)
1817 if (debug_locks_silent)
1819 printk("\n-> #%u", depth);
1820 print_lock_name(target->class);
1821 printk(KERN_CONT ":\n");
1822 print_lock_trace(target->trace, 6);
1826 print_circular_lock_scenario(struct held_lock *src,
1827 struct held_lock *tgt,
1828 struct lock_list *prt)
1830 struct lock_class *source = hlock_class(src);
1831 struct lock_class *target = hlock_class(tgt);
1832 struct lock_class *parent = prt->class;
1835 * A direct locking problem where unsafe_class lock is taken
1836 * directly by safe_class lock, then all we need to show
1837 * is the deadlock scenario, as it is obvious that the
1838 * unsafe lock is taken under the safe lock.
1840 * But if there is a chain instead, where the safe lock takes
1841 * an intermediate lock (middle_class) where this lock is
1842 * not the same as the safe lock, then the lock chain is
1843 * used to describe the problem. Otherwise we would need
1844 * to show a different CPU case for each link in the chain
1845 * from the safe_class lock to the unsafe_class lock.
1847 if (parent != source) {
1848 printk("Chain exists of:\n ");
1849 __print_lock_name(source);
1850 printk(KERN_CONT " --> ");
1851 __print_lock_name(parent);
1852 printk(KERN_CONT " --> ");
1853 __print_lock_name(target);
1854 printk(KERN_CONT "\n\n");
1857 printk(" Possible unsafe locking scenario:\n\n");
1858 printk(" CPU0 CPU1\n");
1859 printk(" ---- ----\n");
1861 __print_lock_name(target);
1862 printk(KERN_CONT ");\n");
1864 __print_lock_name(parent);
1865 printk(KERN_CONT ");\n");
1867 __print_lock_name(target);
1868 printk(KERN_CONT ");\n");
1870 __print_lock_name(source);
1871 printk(KERN_CONT ");\n");
1872 printk("\n *** DEADLOCK ***\n\n");
1876 * When a circular dependency is detected, print the
1879 static noinline void
1880 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1881 struct held_lock *check_src,
1882 struct held_lock *check_tgt)
1884 struct task_struct *curr = current;
1886 if (debug_locks_silent)
1890 pr_warn("======================================================\n");
1891 pr_warn("WARNING: possible circular locking dependency detected\n");
1892 print_kernel_ident();
1893 pr_warn("------------------------------------------------------\n");
1894 pr_warn("%s/%d is trying to acquire lock:\n",
1895 curr->comm, task_pid_nr(curr));
1896 print_lock(check_src);
1898 pr_warn("\nbut task is already holding lock:\n");
1900 print_lock(check_tgt);
1901 pr_warn("\nwhich lock already depends on the new lock.\n\n");
1902 pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1904 print_circular_bug_entry(entry, depth);
1908 * We are about to add A -> B into the dependency graph, and in __bfs() a
1909 * strong dependency path A -> .. -> B is found: hlock_class equals
1912 * If A -> .. -> B can replace A -> B in any __bfs() search (means the former
1913 * is _stronger_ than or equal to the latter), we consider A -> B as redundant.
1914 * For example if A -> .. -> B is -(EN)-> (i.e. A -(E*)-> .. -(*N)-> B), and A
1915 * -> B is -(ER)-> or -(EN)->, then we don't need to add A -> B into the
1916 * dependency graph, as any strong path ..-> A -> B ->.. we can get with
1917 * having dependency A -> B, we could already get a equivalent path ..-> A ->
1918 * .. -> B -> .. with A -> .. -> B. Therefore A -> B is reduntant.
1920 * We need to make sure both the start and the end of A -> .. -> B is not
1921 * weaker than A -> B. For the start part, please see the comment in
1922 * check_redundant(). For the end part, we need:
1926 * a) A -> B is -(*R)-> (everything is not weaker than that)
1930 * b) A -> .. -> B is -(*N)-> (nothing is stronger than this)
1933 static inline bool hlock_equal(struct lock_list *entry, void *data)
1935 struct held_lock *hlock = (struct held_lock *)data;
1937 return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */
1938 (hlock->read == 2 || /* A -> B is -(*R)-> */
1939 !entry->only_xr); /* A -> .. -> B is -(*N)-> */
1943 * We are about to add B -> A into the dependency graph, and in __bfs() a
1944 * strong dependency path A -> .. -> B is found: hlock_class equals
1947 * We will have a deadlock case (conflict) if A -> .. -> B -> A is a strong
1948 * dependency cycle, that means:
1952 * a) B -> A is -(E*)->
1956 * b) A -> .. -> B is -(*N)-> (i.e. A -> .. -(*N)-> B)
1958 * as then we don't have -(*R)-> -(S*)-> in the cycle.
1960 static inline bool hlock_conflict(struct lock_list *entry, void *data)
1962 struct held_lock *hlock = (struct held_lock *)data;
1964 return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */
1965 (hlock->read == 0 || /* B -> A is -(E*)-> */
1966 !entry->only_xr); /* A -> .. -> B is -(*N)-> */
1969 static noinline void print_circular_bug(struct lock_list *this,
1970 struct lock_list *target,
1971 struct held_lock *check_src,
1972 struct held_lock *check_tgt)
1974 struct task_struct *curr = current;
1975 struct lock_list *parent;
1976 struct lock_list *first_parent;
1979 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1982 this->trace = save_trace();
1986 depth = get_lock_depth(target);
1988 print_circular_bug_header(target, depth, check_src, check_tgt);
1990 parent = get_lock_parent(target);
1991 first_parent = parent;
1994 print_circular_bug_entry(parent, --depth);
1995 parent = get_lock_parent(parent);
1998 printk("\nother info that might help us debug this:\n\n");
1999 print_circular_lock_scenario(check_src, check_tgt,
2002 lockdep_print_held_locks(curr);
2004 printk("\nstack backtrace:\n");
2008 static noinline void print_bfs_bug(int ret)
2010 if (!debug_locks_off_graph_unlock())
2014 * Breadth-first-search failed, graph got corrupted?
2016 WARN(1, "lockdep bfs error:%d\n", ret);
2019 static bool noop_count(struct lock_list *entry, void *data)
2021 (*(unsigned long *)data)++;
2025 static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
2027 unsigned long count = 0;
2028 struct lock_list *target_entry;
2030 __bfs_forwards(this, (void *)&count, noop_count, NULL, &target_entry);
2034 unsigned long lockdep_count_forward_deps(struct lock_class *class)
2036 unsigned long ret, flags;
2037 struct lock_list this;
2039 __bfs_init_root(&this, class);
2041 raw_local_irq_save(flags);
2043 ret = __lockdep_count_forward_deps(&this);
2045 raw_local_irq_restore(flags);
2050 static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
2052 unsigned long count = 0;
2053 struct lock_list *target_entry;
2055 __bfs_backwards(this, (void *)&count, noop_count, NULL, &target_entry);
2060 unsigned long lockdep_count_backward_deps(struct lock_class *class)
2062 unsigned long ret, flags;
2063 struct lock_list this;
2065 __bfs_init_root(&this, class);
2067 raw_local_irq_save(flags);
2069 ret = __lockdep_count_backward_deps(&this);
2071 raw_local_irq_restore(flags);
2077 * Check that the dependency graph starting at <src> can lead to
2080 static noinline enum bfs_result
2081 check_path(struct held_lock *target, struct lock_list *src_entry,
2082 bool (*match)(struct lock_list *entry, void *data),
2083 bool (*skip)(struct lock_list *entry, void *data),
2084 struct lock_list **target_entry)
2086 enum bfs_result ret;
2088 ret = __bfs_forwards(src_entry, target, match, skip, target_entry);
2090 if (unlikely(bfs_error(ret)))
2097 * Prove that the dependency graph starting at <src> can not
2098 * lead to <target>. If it can, there is a circle when adding
2099 * <target> -> <src> dependency.
2101 * Print an error and return BFS_RMATCH if it does.
2103 static noinline enum bfs_result
2104 check_noncircular(struct held_lock *src, struct held_lock *target,
2105 struct lock_trace **const trace)
2107 enum bfs_result ret;
2108 struct lock_list *target_entry;
2109 struct lock_list src_entry;
2111 bfs_init_root(&src_entry, src);
2113 debug_atomic_inc(nr_cyclic_checks);
2115 ret = check_path(target, &src_entry, hlock_conflict, NULL, &target_entry);
2117 if (unlikely(ret == BFS_RMATCH)) {
2120 * If save_trace fails here, the printing might
2121 * trigger a WARN but because of the !nr_entries it
2122 * should not do bad things.
2124 *trace = save_trace();
2127 print_circular_bug(&src_entry, target_entry, src, target);
2133 #ifdef CONFIG_TRACE_IRQFLAGS
2136 * Forwards and backwards subgraph searching, for the purposes of
2137 * proving that two subgraphs can be connected by a new dependency
2138 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
2140 * A irq safe->unsafe deadlock happens with the following conditions:
2142 * 1) We have a strong dependency path A -> ... -> B
2144 * 2) and we have ENABLED_IRQ usage of B and USED_IN_IRQ usage of A, therefore
2145 * irq can create a new dependency B -> A (consider the case that a holder
2146 * of B gets interrupted by an irq whose handler will try to acquire A).
2148 * 3) the dependency circle A -> ... -> B -> A we get from 1) and 2) is a
2151 * For the usage bits of B:
2152 * a) if A -> B is -(*N)->, then B -> A could be any type, so any
2153 * ENABLED_IRQ usage suffices.
2154 * b) if A -> B is -(*R)->, then B -> A must be -(E*)->, so only
2155 * ENABLED_IRQ_*_READ usage suffices.
2157 * For the usage bits of A:
2158 * c) if A -> B is -(E*)->, then B -> A could be any type, so any
2159 * USED_IN_IRQ usage suffices.
2160 * d) if A -> B is -(S*)->, then B -> A must be -(*N)->, so only
2161 * USED_IN_IRQ_*_READ usage suffices.
2165 * There is a strong dependency path in the dependency graph: A -> B, and now
2166 * we need to decide which usage bit of A should be accumulated to detect
2167 * safe->unsafe bugs.
2169 * Note that usage_accumulate() is used in backwards search, so ->only_xr
2170 * stands for whether A -> B only has -(S*)-> (in this case ->only_xr is true).
2172 * As above, if only_xr is false, which means A -> B has -(E*)-> dependency
2173 * path, any usage of A should be considered. Otherwise, we should only
2174 * consider _READ usage.
2176 static inline bool usage_accumulate(struct lock_list *entry, void *mask)
2178 if (!entry->only_xr)
2179 *(unsigned long *)mask |= entry->class->usage_mask;
2180 else /* Mask out _READ usage bits */
2181 *(unsigned long *)mask |= (entry->class->usage_mask & LOCKF_IRQ);
2187 * There is a strong dependency path in the dependency graph: A -> B, and now
2188 * we need to decide which usage bit of B conflicts with the usage bits of A,
2189 * i.e. which usage bit of B may introduce safe->unsafe deadlocks.
2191 * As above, if only_xr is false, which means A -> B has -(*N)-> dependency
2192 * path, any usage of B should be considered. Otherwise, we should only
2193 * consider _READ usage.
2195 static inline bool usage_match(struct lock_list *entry, void *mask)
2197 if (!entry->only_xr)
2198 return !!(entry->class->usage_mask & *(unsigned long *)mask);
2199 else /* Mask out _READ usage bits */
2200 return !!((entry->class->usage_mask & LOCKF_IRQ) & *(unsigned long *)mask);
2203 static inline bool usage_skip(struct lock_list *entry, void *mask)
2206 * Skip local_lock() for irq inversion detection.
2208 * For !RT, local_lock() is not a real lock, so it won't carry any
2211 * For RT, an irq inversion happens when we have lock A and B, and on
2212 * some CPU we can have:
2218 * where lock(B) cannot sleep, and we have a dependency B -> ... -> A.
2220 * Now we prove local_lock() cannot exist in that dependency. First we
2221 * have the observation for any lock chain L1 -> ... -> Ln, for any
2222 * 1 <= i <= n, Li.inner_wait_type <= L1.inner_wait_type, otherwise
2223 * wait context check will complain. And since B is not a sleep lock,
2224 * therefore B.inner_wait_type >= 2, and since the inner_wait_type of
2225 * local_lock() is 3, which is greater than 2, therefore there is no
2226 * way the local_lock() exists in the dependency B -> ... -> A.
2228 * As a result, we will skip local_lock(), when we search for irq
2231 if (entry->class->lock_type == LD_LOCK_PERCPU) {
2232 if (DEBUG_LOCKS_WARN_ON(entry->class->wait_type_inner < LD_WAIT_CONFIG))
2242 * Find a node in the forwards-direction dependency sub-graph starting
2243 * at @root->class that matches @bit.
2245 * Return BFS_MATCH if such a node exists in the subgraph, and put that node
2246 * into *@target_entry.
2248 static enum bfs_result
2249 find_usage_forwards(struct lock_list *root, unsigned long usage_mask,
2250 struct lock_list **target_entry)
2252 enum bfs_result result;
2254 debug_atomic_inc(nr_find_usage_forwards_checks);
2256 result = __bfs_forwards(root, &usage_mask, usage_match, usage_skip, target_entry);
2262 * Find a node in the backwards-direction dependency sub-graph starting
2263 * at @root->class that matches @bit.
2265 static enum bfs_result
2266 find_usage_backwards(struct lock_list *root, unsigned long usage_mask,
2267 struct lock_list **target_entry)
2269 enum bfs_result result;
2271 debug_atomic_inc(nr_find_usage_backwards_checks);
2273 result = __bfs_backwards(root, &usage_mask, usage_match, usage_skip, target_entry);
2278 static void print_lock_class_header(struct lock_class *class, int depth)
2282 printk("%*s->", depth, "");
2283 print_lock_name(class);
2284 #ifdef CONFIG_DEBUG_LOCKDEP
2285 printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
2287 printk(KERN_CONT " {\n");
2289 for (bit = 0; bit < LOCK_TRACE_STATES; bit++) {
2290 if (class->usage_mask & (1 << bit)) {
2293 len += printk("%*s %s", depth, "", usage_str[bit]);
2294 len += printk(KERN_CONT " at:\n");
2295 print_lock_trace(class->usage_traces[bit], len);
2298 printk("%*s }\n", depth, "");
2300 printk("%*s ... key at: [<%px>] %pS\n",
2301 depth, "", class->key, class->key);
2305 * printk the shortest lock dependencies from @start to @end in reverse order:
2308 print_shortest_lock_dependencies(struct lock_list *leaf,
2309 struct lock_list *root)
2311 struct lock_list *entry = leaf;
2314 /*compute depth from generated tree by BFS*/
2315 depth = get_lock_depth(leaf);
2318 print_lock_class_header(entry->class, depth);
2319 printk("%*s ... acquired at:\n", depth, "");
2320 print_lock_trace(entry->trace, 2);
2323 if (depth == 0 && (entry != root)) {
2324 printk("lockdep:%s bad path found in chain graph\n", __func__);
2328 entry = get_lock_parent(entry);
2330 } while (entry && (depth >= 0));
2334 print_irq_lock_scenario(struct lock_list *safe_entry,
2335 struct lock_list *unsafe_entry,
2336 struct lock_class *prev_class,
2337 struct lock_class *next_class)
2339 struct lock_class *safe_class = safe_entry->class;
2340 struct lock_class *unsafe_class = unsafe_entry->class;
2341 struct lock_class *middle_class = prev_class;
2343 if (middle_class == safe_class)
2344 middle_class = next_class;
2347 * A direct locking problem where unsafe_class lock is taken
2348 * directly by safe_class lock, then all we need to show
2349 * is the deadlock scenario, as it is obvious that the
2350 * unsafe lock is taken under the safe lock.
2352 * But if there is a chain instead, where the safe lock takes
2353 * an intermediate lock (middle_class) where this lock is
2354 * not the same as the safe lock, then the lock chain is
2355 * used to describe the problem. Otherwise we would need
2356 * to show a different CPU case for each link in the chain
2357 * from the safe_class lock to the unsafe_class lock.
2359 if (middle_class != unsafe_class) {
2360 printk("Chain exists of:\n ");
2361 __print_lock_name(safe_class);
2362 printk(KERN_CONT " --> ");
2363 __print_lock_name(middle_class);
2364 printk(KERN_CONT " --> ");
2365 __print_lock_name(unsafe_class);
2366 printk(KERN_CONT "\n\n");
2369 printk(" Possible interrupt unsafe locking scenario:\n\n");
2370 printk(" CPU0 CPU1\n");
2371 printk(" ---- ----\n");
2373 __print_lock_name(unsafe_class);
2374 printk(KERN_CONT ");\n");
2375 printk(" local_irq_disable();\n");
2377 __print_lock_name(safe_class);
2378 printk(KERN_CONT ");\n");
2380 __print_lock_name(middle_class);
2381 printk(KERN_CONT ");\n");
2382 printk(" <Interrupt>\n");
2384 __print_lock_name(safe_class);
2385 printk(KERN_CONT ");\n");
2386 printk("\n *** DEADLOCK ***\n\n");
2390 print_bad_irq_dependency(struct task_struct *curr,
2391 struct lock_list *prev_root,
2392 struct lock_list *next_root,
2393 struct lock_list *backwards_entry,
2394 struct lock_list *forwards_entry,
2395 struct held_lock *prev,
2396 struct held_lock *next,
2397 enum lock_usage_bit bit1,
2398 enum lock_usage_bit bit2,
2399 const char *irqclass)
2401 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2405 pr_warn("=====================================================\n");
2406 pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
2407 irqclass, irqclass);
2408 print_kernel_ident();
2409 pr_warn("-----------------------------------------------------\n");
2410 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
2411 curr->comm, task_pid_nr(curr),
2412 lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
2413 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
2414 lockdep_hardirqs_enabled(),
2415 curr->softirqs_enabled);
2418 pr_warn("\nand this task is already holding:\n");
2420 pr_warn("which would create a new lock dependency:\n");
2421 print_lock_name(hlock_class(prev));
2423 print_lock_name(hlock_class(next));
2426 pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
2428 print_lock_name(backwards_entry->class);
2429 pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
2431 print_lock_trace(backwards_entry->class->usage_traces[bit1], 1);
2433 pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
2434 print_lock_name(forwards_entry->class);
2435 pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
2438 print_lock_trace(forwards_entry->class->usage_traces[bit2], 1);
2440 pr_warn("\nother info that might help us debug this:\n\n");
2441 print_irq_lock_scenario(backwards_entry, forwards_entry,
2442 hlock_class(prev), hlock_class(next));
2444 lockdep_print_held_locks(curr);
2446 pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
2447 prev_root->trace = save_trace();
2448 if (!prev_root->trace)
2450 print_shortest_lock_dependencies(backwards_entry, prev_root);
2452 pr_warn("\nthe dependencies between the lock to be acquired");
2453 pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
2454 next_root->trace = save_trace();
2455 if (!next_root->trace)
2457 print_shortest_lock_dependencies(forwards_entry, next_root);
2459 pr_warn("\nstack backtrace:\n");
2463 static const char *state_names[] = {
2464 #define LOCKDEP_STATE(__STATE) \
2465 __stringify(__STATE),
2466 #include "lockdep_states.h"
2467 #undef LOCKDEP_STATE
2470 static const char *state_rnames[] = {
2471 #define LOCKDEP_STATE(__STATE) \
2472 __stringify(__STATE)"-READ",
2473 #include "lockdep_states.h"
2474 #undef LOCKDEP_STATE
2477 static inline const char *state_name(enum lock_usage_bit bit)
2479 if (bit & LOCK_USAGE_READ_MASK)
2480 return state_rnames[bit >> LOCK_USAGE_DIR_MASK];
2482 return state_names[bit >> LOCK_USAGE_DIR_MASK];
2486 * The bit number is encoded like:
2488 * bit0: 0 exclusive, 1 read lock
2489 * bit1: 0 used in irq, 1 irq enabled
2492 static int exclusive_bit(int new_bit)
2494 int state = new_bit & LOCK_USAGE_STATE_MASK;
2495 int dir = new_bit & LOCK_USAGE_DIR_MASK;
2498 * keep state, bit flip the direction and strip read.
2500 return state | (dir ^ LOCK_USAGE_DIR_MASK);
2504 * Observe that when given a bitmask where each bitnr is encoded as above, a
2505 * right shift of the mask transforms the individual bitnrs as -1 and
2506 * conversely, a left shift transforms into +1 for the individual bitnrs.
2508 * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can
2509 * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0)
2510 * instead by subtracting the bit number by 2, or shifting the mask right by 2.
2512 * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2.
2514 * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is
2515 * all bits set) and recompose with bitnr1 flipped.
2517 static unsigned long invert_dir_mask(unsigned long mask)
2519 unsigned long excl = 0;
2522 excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK;
2523 excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK;
2529 * Note that a LOCK_ENABLED_IRQ_*_READ usage and a LOCK_USED_IN_IRQ_*_READ
2530 * usage may cause deadlock too, for example:
2534 * write_lock(l1); <irq enabled>
2540 * , in above case, l1 will be marked as LOCK_USED_IN_IRQ_HARDIRQ_READ and l2
2541 * will marked as LOCK_ENABLE_IRQ_HARDIRQ_READ, and this is a possible
2544 * In fact, all of the following cases may cause deadlocks:
2546 * LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_*
2547 * LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_*
2548 * LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_*_READ
2549 * LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_*_READ
2551 * As a result, to calculate the "exclusive mask", first we invert the
2552 * direction (USED_IN/ENABLED) of the original mask, and 1) for all bits with
2553 * bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*). 2) for all
2554 * bits with bitnr0 cleared (LOCK_*_READ), add those with bitnr0 set (LOCK_*).
2556 static unsigned long exclusive_mask(unsigned long mask)
2558 unsigned long excl = invert_dir_mask(mask);
2560 excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
2561 excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
2567 * Retrieve the _possible_ original mask to which @mask is
2568 * exclusive. Ie: this is the opposite of exclusive_mask().
2569 * Note that 2 possible original bits can match an exclusive
2570 * bit: one has LOCK_USAGE_READ_MASK set, the other has it
2571 * cleared. So both are returned for each exclusive bit.
2573 static unsigned long original_mask(unsigned long mask)
2575 unsigned long excl = invert_dir_mask(mask);
2577 /* Include read in existing usages */
2578 excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
2579 excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
2585 * Find the first pair of bit match between an original
2586 * usage mask and an exclusive usage mask.
2588 static int find_exclusive_match(unsigned long mask,
2589 unsigned long excl_mask,
2590 enum lock_usage_bit *bitp,
2591 enum lock_usage_bit *excl_bitp)
2593 int bit, excl, excl_read;
2595 for_each_set_bit(bit, &mask, LOCK_USED) {
2597 * exclusive_bit() strips the read bit, however,
2598 * LOCK_ENABLED_IRQ_*_READ may cause deadlocks too, so we need
2599 * to search excl | LOCK_USAGE_READ_MASK as well.
2601 excl = exclusive_bit(bit);
2602 excl_read = excl | LOCK_USAGE_READ_MASK;
2603 if (excl_mask & lock_flag(excl)) {
2607 } else if (excl_mask & lock_flag(excl_read)) {
2609 *excl_bitp = excl_read;
2617 * Prove that the new dependency does not connect a hardirq-safe(-read)
2618 * lock with a hardirq-unsafe lock - to achieve this we search
2619 * the backwards-subgraph starting at <prev>, and the
2620 * forwards-subgraph starting at <next>:
2622 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
2623 struct held_lock *next)
2625 unsigned long usage_mask = 0, forward_mask, backward_mask;
2626 enum lock_usage_bit forward_bit = 0, backward_bit = 0;
2627 struct lock_list *target_entry1;
2628 struct lock_list *target_entry;
2629 struct lock_list this, that;
2630 enum bfs_result ret;
2633 * Step 1: gather all hard/soft IRQs usages backward in an
2634 * accumulated usage mask.
2636 bfs_init_rootb(&this, prev);
2638 ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, usage_skip, NULL);
2639 if (bfs_error(ret)) {
2644 usage_mask &= LOCKF_USED_IN_IRQ_ALL;
2649 * Step 2: find exclusive uses forward that match the previous
2650 * backward accumulated mask.
2652 forward_mask = exclusive_mask(usage_mask);
2654 bfs_init_root(&that, next);
2656 ret = find_usage_forwards(&that, forward_mask, &target_entry1);
2657 if (bfs_error(ret)) {
2661 if (ret == BFS_RNOMATCH)
2665 * Step 3: we found a bad match! Now retrieve a lock from the backward
2666 * list whose usage mask matches the exclusive usage mask from the
2667 * lock found on the forward list.
2669 backward_mask = original_mask(target_entry1->class->usage_mask);
2671 ret = find_usage_backwards(&this, backward_mask, &target_entry);
2672 if (bfs_error(ret)) {
2676 if (DEBUG_LOCKS_WARN_ON(ret == BFS_RNOMATCH))
2680 * Step 4: narrow down to a pair of incompatible usage bits
2683 ret = find_exclusive_match(target_entry->class->usage_mask,
2684 target_entry1->class->usage_mask,
2685 &backward_bit, &forward_bit);
2686 if (DEBUG_LOCKS_WARN_ON(ret == -1))
2689 print_bad_irq_dependency(curr, &this, &that,
2690 target_entry, target_entry1,
2692 backward_bit, forward_bit,
2693 state_name(backward_bit));
2700 static inline int check_irq_usage(struct task_struct *curr,
2701 struct held_lock *prev, struct held_lock *next)
2706 static inline bool usage_skip(struct lock_list *entry, void *mask)
2711 #endif /* CONFIG_TRACE_IRQFLAGS */
2713 #ifdef CONFIG_LOCKDEP_SMALL
2715 * Check that the dependency graph starting at <src> can lead to
2716 * <target> or not. If it can, <src> -> <target> dependency is already
2719 * Return BFS_RMATCH if it does, or BFS_RMATCH if it does not, return BFS_E* if
2720 * any error appears in the bfs search.
2722 static noinline enum bfs_result
2723 check_redundant(struct held_lock *src, struct held_lock *target)
2725 enum bfs_result ret;
2726 struct lock_list *target_entry;
2727 struct lock_list src_entry;
2729 bfs_init_root(&src_entry, src);
2731 * Special setup for check_redundant().
2733 * To report redundant, we need to find a strong dependency path that
2734 * is equal to or stronger than <src> -> <target>. So if <src> is E,
2735 * we need to let __bfs() only search for a path starting at a -(E*)->,
2736 * we achieve this by setting the initial node's ->only_xr to true in
2737 * that case. And if <prev> is S, we set initial ->only_xr to false
2738 * because both -(S*)-> (equal) and -(E*)-> (stronger) are redundant.
2740 src_entry.only_xr = src->read == 0;
2742 debug_atomic_inc(nr_redundant_checks);
2745 * Note: we skip local_lock() for redundant check, because as the
2746 * comment in usage_skip(), A -> local_lock() -> B and A -> B are not
2749 ret = check_path(target, &src_entry, hlock_equal, usage_skip, &target_entry);
2751 if (ret == BFS_RMATCH)
2752 debug_atomic_inc(nr_redundant);
2759 static inline enum bfs_result
2760 check_redundant(struct held_lock *src, struct held_lock *target)
2762 return BFS_RNOMATCH;
2767 static void inc_chains(int irq_context)
2769 if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
2770 nr_hardirq_chains++;
2771 else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
2772 nr_softirq_chains++;
2774 nr_process_chains++;
2777 static void dec_chains(int irq_context)
2779 if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
2780 nr_hardirq_chains--;
2781 else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
2782 nr_softirq_chains--;
2784 nr_process_chains--;
2788 print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
2790 struct lock_class *next = hlock_class(nxt);
2791 struct lock_class *prev = hlock_class(prv);
2793 printk(" Possible unsafe locking scenario:\n\n");
2797 __print_lock_name(prev);
2798 printk(KERN_CONT ");\n");
2800 __print_lock_name(next);
2801 printk(KERN_CONT ");\n");
2802 printk("\n *** DEADLOCK ***\n\n");
2803 printk(" May be due to missing lock nesting notation\n\n");
2807 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
2808 struct held_lock *next)
2810 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2814 pr_warn("============================================\n");
2815 pr_warn("WARNING: possible recursive locking detected\n");
2816 print_kernel_ident();
2817 pr_warn("--------------------------------------------\n");
2818 pr_warn("%s/%d is trying to acquire lock:\n",
2819 curr->comm, task_pid_nr(curr));
2821 pr_warn("\nbut task is already holding lock:\n");
2824 pr_warn("\nother info that might help us debug this:\n");
2825 print_deadlock_scenario(next, prev);
2826 lockdep_print_held_locks(curr);
2828 pr_warn("\nstack backtrace:\n");
2833 * Check whether we are holding such a class already.
2835 * (Note that this has to be done separately, because the graph cannot
2836 * detect such classes of deadlocks.)
2838 * Returns: 0 on deadlock detected, 1 on OK, 2 if another lock with the same
2839 * lock class is held but nest_lock is also held, i.e. we rely on the
2840 * nest_lock to avoid the deadlock.
2843 check_deadlock(struct task_struct *curr, struct held_lock *next)
2845 struct held_lock *prev;
2846 struct held_lock *nest = NULL;
2849 for (i = 0; i < curr->lockdep_depth; i++) {
2850 prev = curr->held_locks + i;
2852 if (prev->instance == next->nest_lock)
2855 if (hlock_class(prev) != hlock_class(next))
2859 * Allow read-after-read recursion of the same
2860 * lock class (i.e. read_lock(lock)+read_lock(lock)):
2862 if ((next->read == 2) && prev->read)
2866 * We're holding the nest_lock, which serializes this lock's
2867 * nesting behaviour.
2872 print_deadlock_bug(curr, prev, next);
2879 * There was a chain-cache miss, and we are about to add a new dependency
2880 * to a previous lock. We validate the following rules:
2882 * - would the adding of the <prev> -> <next> dependency create a
2883 * circular dependency in the graph? [== circular deadlock]
2885 * - does the new prev->next dependency connect any hardirq-safe lock
2886 * (in the full backwards-subgraph starting at <prev>) with any
2887 * hardirq-unsafe lock (in the full forwards-subgraph starting at
2888 * <next>)? [== illegal lock inversion with hardirq contexts]
2890 * - does the new prev->next dependency connect any softirq-safe lock
2891 * (in the full backwards-subgraph starting at <prev>) with any
2892 * softirq-unsafe lock (in the full forwards-subgraph starting at
2893 * <next>)? [== illegal lock inversion with softirq contexts]
2895 * any of these scenarios could lead to a deadlock.
2897 * Then if all the validations pass, we add the forwards and backwards
2901 check_prev_add(struct task_struct *curr, struct held_lock *prev,
2902 struct held_lock *next, u16 distance,
2903 struct lock_trace **const trace)
2905 struct lock_list *entry;
2906 enum bfs_result ret;
2908 if (!hlock_class(prev)->key || !hlock_class(next)->key) {
2910 * The warning statements below may trigger a use-after-free
2911 * of the class name. It is better to trigger a use-after free
2912 * and to have the class name most of the time instead of not
2913 * having the class name available.
2915 WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key,
2916 "Detected use-after-free of lock class %px/%s\n",
2918 hlock_class(prev)->name);
2919 WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key,
2920 "Detected use-after-free of lock class %px/%s\n",
2922 hlock_class(next)->name);
2927 * Prove that the new <prev> -> <next> dependency would not
2928 * create a circular dependency in the graph. (We do this by
2929 * a breadth-first search into the graph starting at <next>,
2930 * and check whether we can reach <prev>.)
2932 * The search is limited by the size of the circular queue (i.e.,
2933 * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes
2934 * in the graph whose neighbours are to be checked.
2936 ret = check_noncircular(next, prev, trace);
2937 if (unlikely(bfs_error(ret) || ret == BFS_RMATCH))
2940 if (!check_irq_usage(curr, prev, next))
2944 * Is the <prev> -> <next> dependency already present?
2946 * (this may occur even though this is a new chain: consider
2947 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
2948 * chains - the second one will be new, but L1 already has
2949 * L2 added to its dependency list, due to the first chain.)
2951 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
2952 if (entry->class == hlock_class(next)) {
2954 entry->distance = 1;
2955 entry->dep |= calc_dep(prev, next);
2958 * Also, update the reverse dependency in @next's
2959 * ->locks_before list.
2961 * Here we reuse @entry as the cursor, which is fine
2962 * because we won't go to the next iteration of the
2965 * For normal cases, we return in the inner loop.
2967 * If we fail to return, we have inconsistency, i.e.
2968 * <prev>::locks_after contains <next> while
2969 * <next>::locks_before doesn't contain <prev>. In
2970 * that case, we return after the inner and indicate
2971 * something is wrong.
2973 list_for_each_entry(entry, &hlock_class(next)->locks_before, entry) {
2974 if (entry->class == hlock_class(prev)) {
2976 entry->distance = 1;
2977 entry->dep |= calc_depb(prev, next);
2982 /* <prev> is not found in <next>::locks_before */
2988 * Is the <prev> -> <next> link redundant?
2990 ret = check_redundant(prev, next);
2993 else if (ret == BFS_RMATCH)
2997 *trace = save_trace();
3003 * Ok, all validations passed, add the new lock
3004 * to the previous lock's dependency list:
3006 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
3007 &hlock_class(prev)->locks_after,
3008 next->acquire_ip, distance,
3009 calc_dep(prev, next),
3015 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
3016 &hlock_class(next)->locks_before,
3017 next->acquire_ip, distance,
3018 calc_depb(prev, next),
3027 * Add the dependency to all directly-previous locks that are 'relevant'.
3028 * The ones that are relevant are (in increasing distance from curr):
3029 * all consecutive trylock entries and the final non-trylock entry - or
3030 * the end of this context's lock-chain - whichever comes first.
3033 check_prevs_add(struct task_struct *curr, struct held_lock *next)
3035 struct lock_trace *trace = NULL;
3036 int depth = curr->lockdep_depth;
3037 struct held_lock *hlock;
3042 * Depth must not be zero for a non-head lock:
3047 * At least two relevant locks must exist for this
3050 if (curr->held_locks[depth].irq_context !=
3051 curr->held_locks[depth-1].irq_context)
3055 u16 distance = curr->lockdep_depth - depth + 1;
3056 hlock = curr->held_locks + depth - 1;
3059 int ret = check_prev_add(curr, hlock, next, distance, &trace);
3064 * Stop after the first non-trylock entry,
3065 * as non-trylock entries have added their
3066 * own direct dependencies already, so this
3067 * lock is connected to them indirectly:
3069 if (!hlock->trylock)
3075 * End of lock-stack?
3080 * Stop the search if we cross into another context:
3082 if (curr->held_locks[depth].irq_context !=
3083 curr->held_locks[depth-1].irq_context)
3088 if (!debug_locks_off_graph_unlock())
3092 * Clearly we all shouldn't be here, but since we made it we
3093 * can reliable say we messed up our state. See the above two
3094 * gotos for reasons why we could possibly end up here.
3101 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
3102 static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS);
3103 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
3104 unsigned long nr_zapped_lock_chains;
3105 unsigned int nr_free_chain_hlocks; /* Free chain_hlocks in buckets */
3106 unsigned int nr_lost_chain_hlocks; /* Lost chain_hlocks */
3107 unsigned int nr_large_chain_blocks; /* size > MAX_CHAIN_BUCKETS */
3110 * The first 2 chain_hlocks entries in the chain block in the bucket
3111 * list contains the following meta data:
3114 * Bit 15 - always set to 1 (it is not a class index)
3115 * Bits 0-14 - upper 15 bits of the next block index
3116 * entry[1] - lower 16 bits of next block index
3118 * A next block index of all 1 bits means it is the end of the list.
3120 * On the unsized bucket (bucket-0), the 3rd and 4th entries contain
3121 * the chain block size:
3123 * entry[2] - upper 16 bits of the chain block size
3124 * entry[3] - lower 16 bits of the chain block size
3126 #define MAX_CHAIN_BUCKETS 16
3127 #define CHAIN_BLK_FLAG (1U << 15)
3128 #define CHAIN_BLK_LIST_END 0xFFFFU
3130 static int chain_block_buckets[MAX_CHAIN_BUCKETS];
3132 static inline int size_to_bucket(int size)
3134 if (size > MAX_CHAIN_BUCKETS)
3141 * Iterate all the chain blocks in a bucket.
3143 #define for_each_chain_block(bucket, prev, curr) \
3144 for ((prev) = -1, (curr) = chain_block_buckets[bucket]; \
3146 (prev) = (curr), (curr) = chain_block_next(curr))
3151 static inline int chain_block_next(int offset)
3153 int next = chain_hlocks[offset];
3155 WARN_ON_ONCE(!(next & CHAIN_BLK_FLAG));
3157 if (next == CHAIN_BLK_LIST_END)
3160 next &= ~CHAIN_BLK_FLAG;
3162 next |= chain_hlocks[offset + 1];
3170 static inline int chain_block_size(int offset)
3172 return (chain_hlocks[offset + 2] << 16) | chain_hlocks[offset + 3];
3175 static inline void init_chain_block(int offset, int next, int bucket, int size)
3177 chain_hlocks[offset] = (next >> 16) | CHAIN_BLK_FLAG;
3178 chain_hlocks[offset + 1] = (u16)next;
3180 if (size && !bucket) {
3181 chain_hlocks[offset + 2] = size >> 16;
3182 chain_hlocks[offset + 3] = (u16)size;
3186 static inline void add_chain_block(int offset, int size)
3188 int bucket = size_to_bucket(size);
3189 int next = chain_block_buckets[bucket];
3192 if (unlikely(size < 2)) {
3194 * We can't store single entries on the freelist. Leak them.
3196 * One possible way out would be to uniquely mark them, other
3197 * than with CHAIN_BLK_FLAG, such that we can recover them when
3198 * the block before it is re-added.
3201 nr_lost_chain_hlocks++;
3205 nr_free_chain_hlocks += size;
3207 nr_large_chain_blocks++;
3210 * Variable sized, sort large to small.
3212 for_each_chain_block(0, prev, curr) {
3213 if (size >= chain_block_size(curr))
3216 init_chain_block(offset, curr, 0, size);
3218 chain_block_buckets[0] = offset;
3220 init_chain_block(prev, offset, 0, 0);
3224 * Fixed size, add to head.
3226 init_chain_block(offset, next, bucket, size);
3227 chain_block_buckets[bucket] = offset;
3231 * Only the first block in the list can be deleted.
3233 * For the variable size bucket[0], the first block (the largest one) is
3234 * returned, broken up and put back into the pool. So if a chain block of
3235 * length > MAX_CHAIN_BUCKETS is ever used and zapped, it will just be
3236 * queued up after the primordial chain block and never be used until the
3237 * hlock entries in the primordial chain block is almost used up. That
3238 * causes fragmentation and reduce allocation efficiency. That can be
3239 * monitored by looking at the "large chain blocks" number in lockdep_stats.
3241 static inline void del_chain_block(int bucket, int size, int next)
3243 nr_free_chain_hlocks -= size;
3244 chain_block_buckets[bucket] = next;
3247 nr_large_chain_blocks--;
3250 static void init_chain_block_buckets(void)
3254 for (i = 0; i < MAX_CHAIN_BUCKETS; i++)
3255 chain_block_buckets[i] = -1;
3257 add_chain_block(0, ARRAY_SIZE(chain_hlocks));
3261 * Return offset of a chain block of the right size or -1 if not found.
3263 * Fairly simple worst-fit allocator with the addition of a number of size
3264 * specific free lists.
3266 static int alloc_chain_hlocks(int req)
3268 int bucket, curr, size;
3271 * We rely on the MSB to act as an escape bit to denote freelist
3272 * pointers. Make sure this bit isn't set in 'normal' class_idx usage.
3274 BUILD_BUG_ON((MAX_LOCKDEP_KEYS-1) & CHAIN_BLK_FLAG);
3276 init_data_structures_once();
3278 if (nr_free_chain_hlocks < req)
3282 * We require a minimum of 2 (u16) entries to encode a freelist
3286 bucket = size_to_bucket(req);
3287 curr = chain_block_buckets[bucket];
3291 del_chain_block(bucket, req, chain_block_next(curr));
3295 curr = chain_block_buckets[0];
3299 * The variable sized freelist is sorted by size; the first entry is
3300 * the largest. Use it if it fits.
3303 size = chain_block_size(curr);
3304 if (likely(size >= req)) {
3305 del_chain_block(0, size, chain_block_next(curr));
3306 add_chain_block(curr + req, size - req);
3312 * Last resort, split a block in a larger sized bucket.
3314 for (size = MAX_CHAIN_BUCKETS; size > req; size--) {
3315 bucket = size_to_bucket(size);
3316 curr = chain_block_buckets[bucket];
3320 del_chain_block(bucket, size, chain_block_next(curr));
3321 add_chain_block(curr + req, size - req);
3328 static inline void free_chain_hlocks(int base, int size)
3330 add_chain_block(base, max(size, 2));
3333 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
3335 u16 chain_hlock = chain_hlocks[chain->base + i];
3336 unsigned int class_idx = chain_hlock_class_idx(chain_hlock);
3338 return lock_classes + class_idx - 1;
3342 * Returns the index of the first held_lock of the current chain
3344 static inline int get_first_held_lock(struct task_struct *curr,
3345 struct held_lock *hlock)
3348 struct held_lock *hlock_curr;
3350 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
3351 hlock_curr = curr->held_locks + i;
3352 if (hlock_curr->irq_context != hlock->irq_context)
3360 #ifdef CONFIG_DEBUG_LOCKDEP
3362 * Returns the next chain_key iteration
3364 static u64 print_chain_key_iteration(u16 hlock_id, u64 chain_key)
3366 u64 new_chain_key = iterate_chain_key(chain_key, hlock_id);
3368 printk(" hlock_id:%d -> chain_key:%016Lx",
3369 (unsigned int)hlock_id,
3370 (unsigned long long)new_chain_key);
3371 return new_chain_key;
3375 print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
3377 struct held_lock *hlock;
3378 u64 chain_key = INITIAL_CHAIN_KEY;
3379 int depth = curr->lockdep_depth;
3380 int i = get_first_held_lock(curr, hlock_next);
3382 printk("depth: %u (irq_context %u)\n", depth - i + 1,
3383 hlock_next->irq_context);
3384 for (; i < depth; i++) {
3385 hlock = curr->held_locks + i;
3386 chain_key = print_chain_key_iteration(hlock_id(hlock), chain_key);
3391 print_chain_key_iteration(hlock_id(hlock_next), chain_key);
3392 print_lock(hlock_next);
3395 static void print_chain_keys_chain(struct lock_chain *chain)
3398 u64 chain_key = INITIAL_CHAIN_KEY;
3401 printk("depth: %u\n", chain->depth);
3402 for (i = 0; i < chain->depth; i++) {
3403 hlock_id = chain_hlocks[chain->base + i];
3404 chain_key = print_chain_key_iteration(hlock_id, chain_key);
3406 print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id) - 1);
3411 static void print_collision(struct task_struct *curr,
3412 struct held_lock *hlock_next,
3413 struct lock_chain *chain)
3416 pr_warn("============================\n");
3417 pr_warn("WARNING: chain_key collision\n");
3418 print_kernel_ident();
3419 pr_warn("----------------------------\n");
3420 pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
3421 pr_warn("Hash chain already cached but the contents don't match!\n");
3423 pr_warn("Held locks:");
3424 print_chain_keys_held_locks(curr, hlock_next);
3426 pr_warn("Locks in cached chain:");
3427 print_chain_keys_chain(chain);
3429 pr_warn("\nstack backtrace:\n");
3435 * Checks whether the chain and the current held locks are consistent
3436 * in depth and also in content. If they are not it most likely means
3437 * that there was a collision during the calculation of the chain_key.
3438 * Returns: 0 not passed, 1 passed
3440 static int check_no_collision(struct task_struct *curr,
3441 struct held_lock *hlock,
3442 struct lock_chain *chain)
3444 #ifdef CONFIG_DEBUG_LOCKDEP
3447 i = get_first_held_lock(curr, hlock);
3449 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
3450 print_collision(curr, hlock, chain);
3454 for (j = 0; j < chain->depth - 1; j++, i++) {
3455 id = hlock_id(&curr->held_locks[i]);
3457 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
3458 print_collision(curr, hlock, chain);
3467 * Given an index that is >= -1, return the index of the next lock chain.
3468 * Return -2 if there is no next lock chain.
3470 long lockdep_next_lockchain(long i)
3472 i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1);
3473 return i < ARRAY_SIZE(lock_chains) ? i : -2;
3476 unsigned long lock_chain_count(void)
3478 return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains));
3481 /* Must be called with the graph lock held. */
3482 static struct lock_chain *alloc_lock_chain(void)
3484 int idx = find_first_zero_bit(lock_chains_in_use,
3485 ARRAY_SIZE(lock_chains));
3487 if (unlikely(idx >= ARRAY_SIZE(lock_chains)))
3489 __set_bit(idx, lock_chains_in_use);
3490 return lock_chains + idx;
3494 * Adds a dependency chain into chain hashtable. And must be called with
3497 * Return 0 if fail, and graph_lock is released.
3498 * Return 1 if succeed, with graph_lock held.
3500 static inline int add_chain_cache(struct task_struct *curr,
3501 struct held_lock *hlock,
3504 struct hlist_head *hash_head = chainhashentry(chain_key);
3505 struct lock_chain *chain;
3509 * The caller must hold the graph lock, ensure we've got IRQs
3510 * disabled to make this an IRQ-safe lock.. for recursion reasons
3511 * lockdep won't complain about its own locking errors.
3513 if (lockdep_assert_locked())
3516 chain = alloc_lock_chain();
3518 if (!debug_locks_off_graph_unlock())
3521 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
3525 chain->chain_key = chain_key;
3526 chain->irq_context = hlock->irq_context;
3527 i = get_first_held_lock(curr, hlock);
3528 chain->depth = curr->lockdep_depth + 1 - i;
3530 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
3531 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
3532 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
3534 j = alloc_chain_hlocks(chain->depth);
3536 if (!debug_locks_off_graph_unlock())
3539 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
3545 for (j = 0; j < chain->depth - 1; j++, i++) {
3546 int lock_id = hlock_id(curr->held_locks + i);
3548 chain_hlocks[chain->base + j] = lock_id;
3550 chain_hlocks[chain->base + j] = hlock_id(hlock);
3551 hlist_add_head_rcu(&chain->entry, hash_head);
3552 debug_atomic_inc(chain_lookup_misses);
3553 inc_chains(chain->irq_context);
3559 * Look up a dependency chain. Must be called with either the graph lock or
3560 * the RCU read lock held.
3562 static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
3564 struct hlist_head *hash_head = chainhashentry(chain_key);
3565 struct lock_chain *chain;
3567 hlist_for_each_entry_rcu(chain, hash_head, entry) {
3568 if (READ_ONCE(chain->chain_key) == chain_key) {
3569 debug_atomic_inc(chain_lookup_hits);
3577 * If the key is not present yet in dependency chain cache then
3578 * add it and return 1 - in this case the new dependency chain is
3579 * validated. If the key is already hashed, return 0.
3580 * (On return with 1 graph_lock is held.)
3582 static inline int lookup_chain_cache_add(struct task_struct *curr,
3583 struct held_lock *hlock,
3586 struct lock_class *class = hlock_class(hlock);
3587 struct lock_chain *chain = lookup_chain_cache(chain_key);
3591 if (!check_no_collision(curr, hlock, chain))
3594 if (very_verbose(class)) {
3595 printk("\nhash chain already cached, key: "
3596 "%016Lx tail class: [%px] %s\n",
3597 (unsigned long long)chain_key,
3598 class->key, class->name);
3604 if (very_verbose(class)) {
3605 printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
3606 (unsigned long long)chain_key, class->key, class->name);
3613 * We have to walk the chain again locked - to avoid duplicates:
3615 chain = lookup_chain_cache(chain_key);
3621 if (!add_chain_cache(curr, hlock, chain_key))
3627 static int validate_chain(struct task_struct *curr,
3628 struct held_lock *hlock,
3629 int chain_head, u64 chain_key)
3632 * Trylock needs to maintain the stack of held locks, but it
3633 * does not add new dependencies, because trylock can be done
3636 * We look up the chain_key and do the O(N^2) check and update of
3637 * the dependencies only if this is a new dependency chain.
3638 * (If lookup_chain_cache_add() return with 1 it acquires
3639 * graph_lock for us)
3641 if (!hlock->trylock && hlock->check &&
3642 lookup_chain_cache_add(curr, hlock, chain_key)) {
3644 * Check whether last held lock:
3646 * - is irq-safe, if this lock is irq-unsafe
3647 * - is softirq-safe, if this lock is hardirq-unsafe
3649 * And check whether the new lock's dependency graph
3650 * could lead back to the previous lock:
3652 * - within the current held-lock stack
3653 * - across our accumulated lock dependency records
3655 * any of these scenarios could lead to a deadlock.
3658 * The simple case: does the current hold the same lock
3661 int ret = check_deadlock(curr, hlock);
3666 * Add dependency only if this lock is not the head
3667 * of the chain, and if the new lock introduces no more
3668 * lock dependency (because we already hold a lock with the
3669 * same lock class) nor deadlock (because the nest_lock
3670 * serializes nesting locks), see the comments for
3673 if (!chain_head && ret != 2) {
3674 if (!check_prevs_add(curr, hlock))
3680 /* after lookup_chain_cache_add(): */
3681 if (unlikely(!debug_locks))
3688 static inline int validate_chain(struct task_struct *curr,
3689 struct held_lock *hlock,
3690 int chain_head, u64 chain_key)
3695 static void init_chain_block_buckets(void) { }
3696 #endif /* CONFIG_PROVE_LOCKING */
3699 * We are building curr_chain_key incrementally, so double-check
3700 * it from scratch, to make sure that it's done correctly:
3702 static void check_chain_key(struct task_struct *curr)
3704 #ifdef CONFIG_DEBUG_LOCKDEP
3705 struct held_lock *hlock, *prev_hlock = NULL;
3707 u64 chain_key = INITIAL_CHAIN_KEY;
3709 for (i = 0; i < curr->lockdep_depth; i++) {
3710 hlock = curr->held_locks + i;
3711 if (chain_key != hlock->prev_chain_key) {
3714 * We got mighty confused, our chain keys don't match
3715 * with what we expect, someone trample on our task state?
3717 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
3718 curr->lockdep_depth, i,
3719 (unsigned long long)chain_key,
3720 (unsigned long long)hlock->prev_chain_key);
3725 * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is
3726 * it registered lock class index?
3728 if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use)))
3731 if (prev_hlock && (prev_hlock->irq_context !=
3732 hlock->irq_context))
3733 chain_key = INITIAL_CHAIN_KEY;
3734 chain_key = iterate_chain_key(chain_key, hlock_id(hlock));
3737 if (chain_key != curr->curr_chain_key) {
3740 * More smoking hash instead of calculating it, damn see these
3741 * numbers float.. I bet that a pink elephant stepped on my memory.
3743 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
3744 curr->lockdep_depth, i,
3745 (unsigned long long)chain_key,
3746 (unsigned long long)curr->curr_chain_key);
3751 #ifdef CONFIG_PROVE_LOCKING
3752 static int mark_lock(struct task_struct *curr, struct held_lock *this,
3753 enum lock_usage_bit new_bit);
3755 static void print_usage_bug_scenario(struct held_lock *lock)
3757 struct lock_class *class = hlock_class(lock);
3759 printk(" Possible unsafe locking scenario:\n\n");
3763 __print_lock_name(class);
3764 printk(KERN_CONT ");\n");
3765 printk(" <Interrupt>\n");
3767 __print_lock_name(class);
3768 printk(KERN_CONT ");\n");
3769 printk("\n *** DEADLOCK ***\n\n");
3773 print_usage_bug(struct task_struct *curr, struct held_lock *this,
3774 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
3776 if (!debug_locks_off() || debug_locks_silent)
3780 pr_warn("================================\n");
3781 pr_warn("WARNING: inconsistent lock state\n");
3782 print_kernel_ident();
3783 pr_warn("--------------------------------\n");
3785 pr_warn("inconsistent {%s} -> {%s} usage.\n",
3786 usage_str[prev_bit], usage_str[new_bit]);
3788 pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
3789 curr->comm, task_pid_nr(curr),
3790 lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT,
3791 lockdep_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
3792 lockdep_hardirqs_enabled(),
3793 lockdep_softirqs_enabled(curr));
3796 pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
3797 print_lock_trace(hlock_class(this)->usage_traces[prev_bit], 1);
3799 print_irqtrace_events(curr);
3800 pr_warn("\nother info that might help us debug this:\n");
3801 print_usage_bug_scenario(this);
3803 lockdep_print_held_locks(curr);
3805 pr_warn("\nstack backtrace:\n");
3810 * Print out an error if an invalid bit is set:
3813 valid_state(struct task_struct *curr, struct held_lock *this,
3814 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
3816 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) {
3818 print_usage_bug(curr, this, bad_bit, new_bit);
3826 * print irq inversion bug:
3829 print_irq_inversion_bug(struct task_struct *curr,
3830 struct lock_list *root, struct lock_list *other,
3831 struct held_lock *this, int forwards,
3832 const char *irqclass)
3834 struct lock_list *entry = other;
3835 struct lock_list *middle = NULL;
3838 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
3842 pr_warn("========================================================\n");
3843 pr_warn("WARNING: possible irq lock inversion dependency detected\n");
3844 print_kernel_ident();
3845 pr_warn("--------------------------------------------------------\n");
3846 pr_warn("%s/%d just changed the state of lock:\n",
3847 curr->comm, task_pid_nr(curr));
3850 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
3852 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
3853 print_lock_name(other->class);
3854 pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
3856 pr_warn("\nother info that might help us debug this:\n");
3858 /* Find a middle lock (if one exists) */
3859 depth = get_lock_depth(other);
3861 if (depth == 0 && (entry != root)) {
3862 pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
3866 entry = get_lock_parent(entry);
3868 } while (entry && entry != root && (depth >= 0));
3870 print_irq_lock_scenario(root, other,
3871 middle ? middle->class : root->class, other->class);
3873 print_irq_lock_scenario(other, root,
3874 middle ? middle->class : other->class, root->class);
3876 lockdep_print_held_locks(curr);
3878 pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
3879 root->trace = save_trace();
3882 print_shortest_lock_dependencies(other, root);
3884 pr_warn("\nstack backtrace:\n");
3889 * Prove that in the forwards-direction subgraph starting at <this>
3890 * there is no lock matching <mask>:
3893 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
3894 enum lock_usage_bit bit)
3896 enum bfs_result ret;
3897 struct lock_list root;
3898 struct lock_list *target_entry;
3899 enum lock_usage_bit read_bit = bit + LOCK_USAGE_READ_MASK;
3900 unsigned usage_mask = lock_flag(bit) | lock_flag(read_bit);
3902 bfs_init_root(&root, this);
3903 ret = find_usage_forwards(&root, usage_mask, &target_entry);
3904 if (bfs_error(ret)) {
3908 if (ret == BFS_RNOMATCH)
3911 /* Check whether write or read usage is the match */
3912 if (target_entry->class->usage_mask & lock_flag(bit)) {
3913 print_irq_inversion_bug(curr, &root, target_entry,
3914 this, 1, state_name(bit));
3916 print_irq_inversion_bug(curr, &root, target_entry,
3917 this, 1, state_name(read_bit));
3924 * Prove that in the backwards-direction subgraph starting at <this>
3925 * there is no lock matching <mask>:
3928 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
3929 enum lock_usage_bit bit)
3931 enum bfs_result ret;
3932 struct lock_list root;
3933 struct lock_list *target_entry;
3934 enum lock_usage_bit read_bit = bit + LOCK_USAGE_READ_MASK;
3935 unsigned usage_mask = lock_flag(bit) | lock_flag(read_bit);
3937 bfs_init_rootb(&root, this);
3938 ret = find_usage_backwards(&root, usage_mask, &target_entry);
3939 if (bfs_error(ret)) {
3943 if (ret == BFS_RNOMATCH)
3946 /* Check whether write or read usage is the match */
3947 if (target_entry->class->usage_mask & lock_flag(bit)) {
3948 print_irq_inversion_bug(curr, &root, target_entry,
3949 this, 0, state_name(bit));
3951 print_irq_inversion_bug(curr, &root, target_entry,
3952 this, 0, state_name(read_bit));
3958 void print_irqtrace_events(struct task_struct *curr)
3960 const struct irqtrace_events *trace = &curr->irqtrace;
3962 printk("irq event stamp: %u\n", trace->irq_events);
3963 printk("hardirqs last enabled at (%u): [<%px>] %pS\n",
3964 trace->hardirq_enable_event, (void *)trace->hardirq_enable_ip,
3965 (void *)trace->hardirq_enable_ip);
3966 printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
3967 trace->hardirq_disable_event, (void *)trace->hardirq_disable_ip,
3968 (void *)trace->hardirq_disable_ip);
3969 printk("softirqs last enabled at (%u): [<%px>] %pS\n",
3970 trace->softirq_enable_event, (void *)trace->softirq_enable_ip,
3971 (void *)trace->softirq_enable_ip);
3972 printk("softirqs last disabled at (%u): [<%px>] %pS\n",
3973 trace->softirq_disable_event, (void *)trace->softirq_disable_ip,
3974 (void *)trace->softirq_disable_ip);
3977 static int HARDIRQ_verbose(struct lock_class *class)
3980 return class_filter(class);
3985 static int SOFTIRQ_verbose(struct lock_class *class)
3988 return class_filter(class);
3993 static int (*state_verbose_f[])(struct lock_class *class) = {
3994 #define LOCKDEP_STATE(__STATE) \
3996 #include "lockdep_states.h"
3997 #undef LOCKDEP_STATE
4000 static inline int state_verbose(enum lock_usage_bit bit,
4001 struct lock_class *class)
4003 return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class);
4006 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
4007 enum lock_usage_bit bit, const char *name);
4010 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
4011 enum lock_usage_bit new_bit)
4013 int excl_bit = exclusive_bit(new_bit);
4014 int read = new_bit & LOCK_USAGE_READ_MASK;
4015 int dir = new_bit & LOCK_USAGE_DIR_MASK;
4018 * Validate that this particular lock does not have conflicting
4021 if (!valid_state(curr, this, new_bit, excl_bit))
4025 * Check for read in write conflicts
4027 if (!read && !valid_state(curr, this, new_bit,
4028 excl_bit + LOCK_USAGE_READ_MASK))
4033 * Validate that the lock dependencies don't have conflicting usage
4038 * mark ENABLED has to look backwards -- to ensure no dependee
4039 * has USED_IN state, which, again, would allow recursion deadlocks.
4041 if (!check_usage_backwards(curr, this, excl_bit))
4045 * mark USED_IN has to look forwards -- to ensure no dependency
4046 * has ENABLED state, which would allow recursion deadlocks.
4048 if (!check_usage_forwards(curr, this, excl_bit))
4052 if (state_verbose(new_bit, hlock_class(this)))
4059 * Mark all held locks with a usage bit:
4062 mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit)
4064 struct held_lock *hlock;
4067 for (i = 0; i < curr->lockdep_depth; i++) {
4068 enum lock_usage_bit hlock_bit = base_bit;
4069 hlock = curr->held_locks + i;
4072 hlock_bit += LOCK_USAGE_READ_MASK;
4074 BUG_ON(hlock_bit >= LOCK_USAGE_STATES);
4079 if (!mark_lock(curr, hlock, hlock_bit))
4087 * Hardirqs will be enabled:
4089 static void __trace_hardirqs_on_caller(void)
4091 struct task_struct *curr = current;
4094 * We are going to turn hardirqs on, so set the
4095 * usage bit for all held locks:
4097 if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ))
4100 * If we have softirqs enabled, then set the usage
4101 * bit for all held locks. (disabled hardirqs prevented
4102 * this bit from being set before)
4104 if (curr->softirqs_enabled)
4105 mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
4109 * lockdep_hardirqs_on_prepare - Prepare for enabling interrupts
4110 * @ip: Caller address
4112 * Invoked before a possible transition to RCU idle from exit to user or
4113 * guest mode. This ensures that all RCU operations are done before RCU
4114 * stops watching. After the RCU transition lockdep_hardirqs_on() has to be
4115 * invoked to set the final state.
4117 void lockdep_hardirqs_on_prepare(unsigned long ip)
4119 if (unlikely(!debug_locks))
4123 * NMIs do not (and cannot) track lock dependencies, nothing to do.
4125 if (unlikely(in_nmi()))
4128 if (unlikely(this_cpu_read(lockdep_recursion)))
4131 if (unlikely(lockdep_hardirqs_enabled())) {
4133 * Neither irq nor preemption are disabled here
4134 * so this is racy by nature but losing one hit
4135 * in a stat is not a big deal.
4137 __debug_atomic_inc(redundant_hardirqs_on);
4142 * We're enabling irqs and according to our state above irqs weren't
4143 * already enabled, yet we find the hardware thinks they are in fact
4144 * enabled.. someone messed up their IRQ state tracing.
4146 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4150 * See the fine text that goes along with this variable definition.
4152 if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled))
4156 * Can't allow enabling interrupts while in an interrupt handler,
4157 * that's general bad form and such. Recursion, limited stack etc..
4159 if (DEBUG_LOCKS_WARN_ON(lockdep_hardirq_context()))
4162 current->hardirq_chain_key = current->curr_chain_key;
4164 lockdep_recursion_inc();
4165 __trace_hardirqs_on_caller();
4166 lockdep_recursion_finish();
4168 EXPORT_SYMBOL_GPL(lockdep_hardirqs_on_prepare);
4170 void noinstr lockdep_hardirqs_on(unsigned long ip)
4172 struct irqtrace_events *trace = ¤t->irqtrace;
4174 if (unlikely(!debug_locks))
4178 * NMIs can happen in the middle of local_irq_{en,dis}able() where the
4179 * tracking state and hardware state are out of sync.
4181 * NMIs must save lockdep_hardirqs_enabled() to restore IRQ state from,
4182 * and not rely on hardware state like normal interrupts.
4184 if (unlikely(in_nmi())) {
4185 if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
4190 * - recursion check, because NMI can hit lockdep;
4191 * - hardware state check, because above;
4192 * - chain_key check, see lockdep_hardirqs_on_prepare().
4197 if (unlikely(this_cpu_read(lockdep_recursion)))
4200 if (lockdep_hardirqs_enabled()) {
4202 * Neither irq nor preemption are disabled here
4203 * so this is racy by nature but losing one hit
4204 * in a stat is not a big deal.
4206 __debug_atomic_inc(redundant_hardirqs_on);
4211 * We're enabling irqs and according to our state above irqs weren't
4212 * already enabled, yet we find the hardware thinks they are in fact
4213 * enabled.. someone messed up their IRQ state tracing.
4215 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4219 * Ensure the lock stack remained unchanged between
4220 * lockdep_hardirqs_on_prepare() and lockdep_hardirqs_on().
4222 DEBUG_LOCKS_WARN_ON(current->hardirq_chain_key !=
4223 current->curr_chain_key);
4226 /* we'll do an OFF -> ON transition: */
4227 __this_cpu_write(hardirqs_enabled, 1);
4228 trace->hardirq_enable_ip = ip;
4229 trace->hardirq_enable_event = ++trace->irq_events;
4230 debug_atomic_inc(hardirqs_on_events);
4232 EXPORT_SYMBOL_GPL(lockdep_hardirqs_on);
4235 * Hardirqs were disabled:
4237 void noinstr lockdep_hardirqs_off(unsigned long ip)
4239 if (unlikely(!debug_locks))
4243 * Matching lockdep_hardirqs_on(), allow NMIs in the middle of lockdep;
4244 * they will restore the software state. This ensures the software
4245 * state is consistent inside NMIs as well.
4248 if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
4250 } else if (__this_cpu_read(lockdep_recursion))
4254 * So we're supposed to get called after you mask local IRQs, but for
4255 * some reason the hardware doesn't quite think you did a proper job.
4257 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4260 if (lockdep_hardirqs_enabled()) {
4261 struct irqtrace_events *trace = ¤t->irqtrace;
4264 * We have done an ON -> OFF transition:
4266 __this_cpu_write(hardirqs_enabled, 0);
4267 trace->hardirq_disable_ip = ip;
4268 trace->hardirq_disable_event = ++trace->irq_events;
4269 debug_atomic_inc(hardirqs_off_events);
4271 debug_atomic_inc(redundant_hardirqs_off);
4274 EXPORT_SYMBOL_GPL(lockdep_hardirqs_off);
4277 * Softirqs will be enabled:
4279 void lockdep_softirqs_on(unsigned long ip)
4281 struct irqtrace_events *trace = ¤t->irqtrace;
4283 if (unlikely(!lockdep_enabled()))
4287 * We fancy IRQs being disabled here, see softirq.c, avoids
4288 * funny state and nesting things.
4290 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4293 if (current->softirqs_enabled) {
4294 debug_atomic_inc(redundant_softirqs_on);
4298 lockdep_recursion_inc();
4300 * We'll do an OFF -> ON transition:
4302 current->softirqs_enabled = 1;
4303 trace->softirq_enable_ip = ip;
4304 trace->softirq_enable_event = ++trace->irq_events;
4305 debug_atomic_inc(softirqs_on_events);
4307 * We are going to turn softirqs on, so set the
4308 * usage bit for all held locks, if hardirqs are
4311 if (lockdep_hardirqs_enabled())
4312 mark_held_locks(current, LOCK_ENABLED_SOFTIRQ);
4313 lockdep_recursion_finish();
4317 * Softirqs were disabled:
4319 void lockdep_softirqs_off(unsigned long ip)
4321 if (unlikely(!lockdep_enabled()))
4325 * We fancy IRQs being disabled here, see softirq.c
4327 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
4330 if (current->softirqs_enabled) {
4331 struct irqtrace_events *trace = ¤t->irqtrace;
4334 * We have done an ON -> OFF transition:
4336 current->softirqs_enabled = 0;
4337 trace->softirq_disable_ip = ip;
4338 trace->softirq_disable_event = ++trace->irq_events;
4339 debug_atomic_inc(softirqs_off_events);
4341 * Whoops, we wanted softirqs off, so why aren't they?
4343 DEBUG_LOCKS_WARN_ON(!softirq_count());
4345 debug_atomic_inc(redundant_softirqs_off);
4349 mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
4355 * If non-trylock use in a hardirq or softirq context, then
4356 * mark the lock as used in these contexts:
4358 if (!hlock->trylock) {
4360 if (lockdep_hardirq_context())
4361 if (!mark_lock(curr, hlock,
4362 LOCK_USED_IN_HARDIRQ_READ))
4364 if (curr->softirq_context)
4365 if (!mark_lock(curr, hlock,
4366 LOCK_USED_IN_SOFTIRQ_READ))
4369 if (lockdep_hardirq_context())
4370 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
4372 if (curr->softirq_context)
4373 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
4377 if (!hlock->hardirqs_off) {
4379 if (!mark_lock(curr, hlock,
4380 LOCK_ENABLED_HARDIRQ_READ))
4382 if (curr->softirqs_enabled)
4383 if (!mark_lock(curr, hlock,
4384 LOCK_ENABLED_SOFTIRQ_READ))
4387 if (!mark_lock(curr, hlock,
4388 LOCK_ENABLED_HARDIRQ))
4390 if (curr->softirqs_enabled)
4391 if (!mark_lock(curr, hlock,
4392 LOCK_ENABLED_SOFTIRQ))
4398 /* mark it as used: */
4399 if (!mark_lock(curr, hlock, LOCK_USED))
4405 static inline unsigned int task_irq_context(struct task_struct *task)
4407 return LOCK_CHAIN_HARDIRQ_CONTEXT * !!lockdep_hardirq_context() +
4408 LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context;
4411 static int separate_irq_context(struct task_struct *curr,
4412 struct held_lock *hlock)
4414 unsigned int depth = curr->lockdep_depth;
4417 * Keep track of points where we cross into an interrupt context:
4420 struct held_lock *prev_hlock;
4422 prev_hlock = curr->held_locks + depth-1;
4424 * If we cross into another context, reset the
4425 * hash key (this also prevents the checking and the
4426 * adding of the dependency to 'prev'):
4428 if (prev_hlock->irq_context != hlock->irq_context)
4435 * Mark a lock with a usage bit, and validate the state transition:
4437 static int mark_lock(struct task_struct *curr, struct held_lock *this,
4438 enum lock_usage_bit new_bit)
4440 unsigned int new_mask, ret = 1;
4442 if (new_bit >= LOCK_USAGE_STATES) {
4443 DEBUG_LOCKS_WARN_ON(1);
4447 if (new_bit == LOCK_USED && this->read)
4448 new_bit = LOCK_USED_READ;
4450 new_mask = 1 << new_bit;
4453 * If already set then do not dirty the cacheline,
4454 * nor do any checks:
4456 if (likely(hlock_class(this)->usage_mask & new_mask))
4462 * Make sure we didn't race:
4464 if (unlikely(hlock_class(this)->usage_mask & new_mask))
4467 if (!hlock_class(this)->usage_mask)
4468 debug_atomic_dec(nr_unused_locks);
4470 hlock_class(this)->usage_mask |= new_mask;
4472 if (new_bit < LOCK_TRACE_STATES) {
4473 if (!(hlock_class(this)->usage_traces[new_bit] = save_trace()))
4477 if (new_bit < LOCK_USED) {
4478 ret = mark_lock_irq(curr, this, new_bit);
4487 * We must printk outside of the graph_lock:
4490 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
4492 print_irqtrace_events(curr);
4499 static inline short task_wait_context(struct task_struct *curr)
4502 * Set appropriate wait type for the context; for IRQs we have to take
4503 * into account force_irqthread as that is implied by PREEMPT_RT.
4505 if (lockdep_hardirq_context()) {
4507 * Check if force_irqthreads will run us threaded.
4509 if (curr->hardirq_threaded || curr->irq_config)
4510 return LD_WAIT_CONFIG;
4512 return LD_WAIT_SPIN;
4513 } else if (curr->softirq_context) {
4515 * Softirqs are always threaded.
4517 return LD_WAIT_CONFIG;
4524 print_lock_invalid_wait_context(struct task_struct *curr,
4525 struct held_lock *hlock)
4529 if (!debug_locks_off())
4531 if (debug_locks_silent)
4535 pr_warn("=============================\n");
4536 pr_warn("[ BUG: Invalid wait context ]\n");
4537 print_kernel_ident();
4538 pr_warn("-----------------------------\n");
4540 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
4543 pr_warn("other info that might help us debug this:\n");
4545 curr_inner = task_wait_context(curr);
4546 pr_warn("context-{%d:%d}\n", curr_inner, curr_inner);
4548 lockdep_print_held_locks(curr);
4550 pr_warn("stack backtrace:\n");
4557 * Verify the wait_type context.
4559 * This check validates we takes locks in the right wait-type order; that is it
4560 * ensures that we do not take mutexes inside spinlocks and do not attempt to
4561 * acquire spinlocks inside raw_spinlocks and the sort.
4563 * The entire thing is slightly more complex because of RCU, RCU is a lock that
4564 * can be taken from (pretty much) any context but also has constraints.
4565 * However when taken in a stricter environment the RCU lock does not loosen
4568 * Therefore we must look for the strictest environment in the lock stack and
4569 * compare that to the lock we're trying to acquire.
4571 static int check_wait_context(struct task_struct *curr, struct held_lock *next)
4573 u8 next_inner = hlock_class(next)->wait_type_inner;
4574 u8 next_outer = hlock_class(next)->wait_type_outer;
4578 if (!curr->lockdep_depth || !next_inner || next->trylock)
4582 next_outer = next_inner;
4585 * Find start of current irq_context..
4587 for (depth = curr->lockdep_depth - 1; depth >= 0; depth--) {
4588 struct held_lock *prev = curr->held_locks + depth;
4589 if (prev->irq_context != next->irq_context)
4594 curr_inner = task_wait_context(curr);
4596 for (; depth < curr->lockdep_depth; depth++) {
4597 struct held_lock *prev = curr->held_locks + depth;
4598 u8 prev_inner = hlock_class(prev)->wait_type_inner;
4602 * We can have a bigger inner than a previous one
4603 * when outer is smaller than inner, as with RCU.
4605 * Also due to trylocks.
4607 curr_inner = min(curr_inner, prev_inner);
4611 if (next_outer > curr_inner)
4612 return print_lock_invalid_wait_context(curr, next);
4617 #else /* CONFIG_PROVE_LOCKING */
4620 mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
4625 static inline unsigned int task_irq_context(struct task_struct *task)
4630 static inline int separate_irq_context(struct task_struct *curr,
4631 struct held_lock *hlock)
4636 static inline int check_wait_context(struct task_struct *curr,
4637 struct held_lock *next)
4642 #endif /* CONFIG_PROVE_LOCKING */
4645 * Initialize a lock instance's lock-class mapping info:
4647 void lockdep_init_map_type(struct lockdep_map *lock, const char *name,
4648 struct lock_class_key *key, int subclass,
4649 u8 inner, u8 outer, u8 lock_type)
4653 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
4654 lock->class_cache[i] = NULL;
4656 #ifdef CONFIG_LOCK_STAT
4657 lock->cpu = raw_smp_processor_id();
4661 * Can't be having no nameless bastards around this place!
4663 if (DEBUG_LOCKS_WARN_ON(!name)) {
4664 lock->name = "NULL";
4670 lock->wait_type_outer = outer;
4671 lock->wait_type_inner = inner;
4672 lock->lock_type = lock_type;
4675 * No key, no joy, we need to hash something.
4677 if (DEBUG_LOCKS_WARN_ON(!key))
4680 * Sanity check, the lock-class key must either have been allocated
4681 * statically or must have been registered as a dynamic key.
4683 if (!static_obj(key) && !is_dynamic_key(key)) {
4685 printk(KERN_ERR "BUG: key %px has not been registered!\n", key);
4686 DEBUG_LOCKS_WARN_ON(1);
4691 if (unlikely(!debug_locks))
4695 unsigned long flags;
4697 if (DEBUG_LOCKS_WARN_ON(!lockdep_enabled()))
4700 raw_local_irq_save(flags);
4701 lockdep_recursion_inc();
4702 register_lock_class(lock, subclass, 1);
4703 lockdep_recursion_finish();
4704 raw_local_irq_restore(flags);
4707 EXPORT_SYMBOL_GPL(lockdep_init_map_type);
4709 struct lock_class_key __lockdep_no_validate__;
4710 EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
4713 print_lock_nested_lock_not_held(struct task_struct *curr,
4714 struct held_lock *hlock,
4717 if (!debug_locks_off())
4719 if (debug_locks_silent)
4723 pr_warn("==================================\n");
4724 pr_warn("WARNING: Nested lock was not taken\n");
4725 print_kernel_ident();
4726 pr_warn("----------------------------------\n");
4728 pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
4731 pr_warn("\nbut this task is not holding:\n");
4732 pr_warn("%s\n", hlock->nest_lock->name);
4734 pr_warn("\nstack backtrace:\n");
4737 pr_warn("\nother info that might help us debug this:\n");
4738 lockdep_print_held_locks(curr);
4740 pr_warn("\nstack backtrace:\n");
4744 static int __lock_is_held(const struct lockdep_map *lock, int read);
4747 * This gets called for every mutex_lock*()/spin_lock*() operation.
4748 * We maintain the dependency maps and validate the locking attempt:
4750 * The callers must make sure that IRQs are disabled before calling it,
4751 * otherwise we could get an interrupt which would want to take locks,
4752 * which would end up in lockdep again.
4754 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
4755 int trylock, int read, int check, int hardirqs_off,
4756 struct lockdep_map *nest_lock, unsigned long ip,
4757 int references, int pin_count)
4759 struct task_struct *curr = current;
4760 struct lock_class *class = NULL;
4761 struct held_lock *hlock;
4767 if (unlikely(!debug_locks))
4770 if (!prove_locking || lock->key == &__lockdep_no_validate__)
4773 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
4774 class = lock->class_cache[subclass];
4778 if (unlikely(!class)) {
4779 class = register_lock_class(lock, subclass, 0);
4784 debug_class_ops_inc(class);
4786 if (very_verbose(class)) {
4787 printk("\nacquire class [%px] %s", class->key, class->name);
4788 if (class->name_version > 1)
4789 printk(KERN_CONT "#%d", class->name_version);
4790 printk(KERN_CONT "\n");
4795 * Add the lock to the list of currently held locks.
4796 * (we dont increase the depth just yet, up until the
4797 * dependency checks are done)
4799 depth = curr->lockdep_depth;
4801 * Ran out of static storage for our per-task lock stack again have we?
4803 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
4806 class_idx = class - lock_classes;
4808 if (depth) { /* we're holding locks */
4809 hlock = curr->held_locks + depth - 1;
4810 if (hlock->class_idx == class_idx && nest_lock) {
4814 if (!hlock->references)
4815 hlock->references++;
4817 hlock->references += references;
4820 if (DEBUG_LOCKS_WARN_ON(hlock->references < references))
4827 hlock = curr->held_locks + depth;
4829 * Plain impossible, we just registered it and checked it weren't no
4830 * NULL like.. I bet this mushroom I ate was good!
4832 if (DEBUG_LOCKS_WARN_ON(!class))
4834 hlock->class_idx = class_idx;
4835 hlock->acquire_ip = ip;
4836 hlock->instance = lock;
4837 hlock->nest_lock = nest_lock;
4838 hlock->irq_context = task_irq_context(curr);
4839 hlock->trylock = trylock;
4841 hlock->check = check;
4842 hlock->hardirqs_off = !!hardirqs_off;
4843 hlock->references = references;
4844 #ifdef CONFIG_LOCK_STAT
4845 hlock->waittime_stamp = 0;
4846 hlock->holdtime_stamp = lockstat_clock();
4848 hlock->pin_count = pin_count;
4850 if (check_wait_context(curr, hlock))
4853 /* Initialize the lock usage bit */
4854 if (!mark_usage(curr, hlock, check))
4858 * Calculate the chain hash: it's the combined hash of all the
4859 * lock keys along the dependency chain. We save the hash value
4860 * at every step so that we can get the current hash easily
4861 * after unlock. The chain hash is then used to cache dependency
4864 * The 'key ID' is what is the most compact key value to drive
4865 * the hash, not class->key.
4868 * Whoops, we did it again.. class_idx is invalid.
4870 if (DEBUG_LOCKS_WARN_ON(!test_bit(class_idx, lock_classes_in_use)))
4873 chain_key = curr->curr_chain_key;
4876 * How can we have a chain hash when we ain't got no keys?!
4878 if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY))
4883 hlock->prev_chain_key = chain_key;
4884 if (separate_irq_context(curr, hlock)) {
4885 chain_key = INITIAL_CHAIN_KEY;
4888 chain_key = iterate_chain_key(chain_key, hlock_id(hlock));
4890 if (nest_lock && !__lock_is_held(nest_lock, -1)) {
4891 print_lock_nested_lock_not_held(curr, hlock, ip);
4895 if (!debug_locks_silent) {
4896 WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key);
4897 WARN_ON_ONCE(!hlock_class(hlock)->key);
4900 if (!validate_chain(curr, hlock, chain_head, chain_key))
4903 curr->curr_chain_key = chain_key;
4904 curr->lockdep_depth++;
4905 check_chain_key(curr);
4906 #ifdef CONFIG_DEBUG_LOCKDEP
4907 if (unlikely(!debug_locks))
4910 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
4912 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
4913 printk(KERN_DEBUG "depth: %i max: %lu!\n",
4914 curr->lockdep_depth, MAX_LOCK_DEPTH);
4916 lockdep_print_held_locks(current);
4917 debug_show_all_locks();
4923 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
4924 max_lockdep_depth = curr->lockdep_depth;
4929 static void print_unlock_imbalance_bug(struct task_struct *curr,
4930 struct lockdep_map *lock,
4933 if (!debug_locks_off())
4935 if (debug_locks_silent)
4939 pr_warn("=====================================\n");
4940 pr_warn("WARNING: bad unlock balance detected!\n");
4941 print_kernel_ident();
4942 pr_warn("-------------------------------------\n");
4943 pr_warn("%s/%d is trying to release lock (",
4944 curr->comm, task_pid_nr(curr));
4945 print_lockdep_cache(lock);
4947 print_ip_sym(KERN_WARNING, ip);
4948 pr_warn("but there are no more locks to release!\n");
4949 pr_warn("\nother info that might help us debug this:\n");
4950 lockdep_print_held_locks(curr);
4952 pr_warn("\nstack backtrace:\n");
4956 static noinstr int match_held_lock(const struct held_lock *hlock,
4957 const struct lockdep_map *lock)
4959 if (hlock->instance == lock)
4962 if (hlock->references) {
4963 const struct lock_class *class = lock->class_cache[0];
4966 class = look_up_lock_class(lock, 0);
4969 * If look_up_lock_class() failed to find a class, we're trying
4970 * to test if we hold a lock that has never yet been acquired.
4971 * Clearly if the lock hasn't been acquired _ever_, we're not
4972 * holding it either, so report failure.
4978 * References, but not a lock we're actually ref-counting?
4979 * State got messed up, follow the sites that change ->references
4980 * and try to make sense of it.
4982 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
4985 if (hlock->class_idx == class - lock_classes)
4992 /* @depth must not be zero */
4993 static struct held_lock *find_held_lock(struct task_struct *curr,
4994 struct lockdep_map *lock,
4995 unsigned int depth, int *idx)
4997 struct held_lock *ret, *hlock, *prev_hlock;
5001 hlock = curr->held_locks + i;
5003 if (match_held_lock(hlock, lock))
5007 for (i--, prev_hlock = hlock--;
5009 i--, prev_hlock = hlock--) {
5011 * We must not cross into another context:
5013 if (prev_hlock->irq_context != hlock->irq_context) {
5017 if (match_held_lock(hlock, lock)) {
5028 static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
5029 int idx, unsigned int *merged)
5031 struct held_lock *hlock;
5032 int first_idx = idx;
5034 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
5037 for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
5038 switch (__lock_acquire(hlock->instance,
5039 hlock_class(hlock)->subclass,
5041 hlock->read, hlock->check,
5042 hlock->hardirqs_off,
5043 hlock->nest_lock, hlock->acquire_ip,
5044 hlock->references, hlock->pin_count)) {
5050 *merged += (idx == first_idx);
5061 __lock_set_class(struct lockdep_map *lock, const char *name,
5062 struct lock_class_key *key, unsigned int subclass,
5065 struct task_struct *curr = current;
5066 unsigned int depth, merged = 0;
5067 struct held_lock *hlock;
5068 struct lock_class *class;
5071 if (unlikely(!debug_locks))
5074 depth = curr->lockdep_depth;
5076 * This function is about (re)setting the class of a held lock,
5077 * yet we're not actually holding any locks. Naughty user!
5079 if (DEBUG_LOCKS_WARN_ON(!depth))
5082 hlock = find_held_lock(curr, lock, depth, &i);
5084 print_unlock_imbalance_bug(curr, lock, ip);
5088 lockdep_init_map_waits(lock, name, key, 0,
5089 lock->wait_type_inner,
5090 lock->wait_type_outer);
5091 class = register_lock_class(lock, subclass, 0);
5092 hlock->class_idx = class - lock_classes;
5094 curr->lockdep_depth = i;
5095 curr->curr_chain_key = hlock->prev_chain_key;
5097 if (reacquire_held_locks(curr, depth, i, &merged))
5101 * I took it apart and put it back together again, except now I have
5102 * these 'spare' parts.. where shall I put them.
5104 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged))
5109 static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
5111 struct task_struct *curr = current;
5112 unsigned int depth, merged = 0;
5113 struct held_lock *hlock;
5116 if (unlikely(!debug_locks))
5119 depth = curr->lockdep_depth;
5121 * This function is about (re)setting the class of a held lock,
5122 * yet we're not actually holding any locks. Naughty user!
5124 if (DEBUG_LOCKS_WARN_ON(!depth))
5127 hlock = find_held_lock(curr, lock, depth, &i);
5129 print_unlock_imbalance_bug(curr, lock, ip);
5133 curr->lockdep_depth = i;
5134 curr->curr_chain_key = hlock->prev_chain_key;
5136 WARN(hlock->read, "downgrading a read lock");
5138 hlock->acquire_ip = ip;
5140 if (reacquire_held_locks(curr, depth, i, &merged))
5143 /* Merging can't happen with unchanged classes.. */
5144 if (DEBUG_LOCKS_WARN_ON(merged))
5148 * I took it apart and put it back together again, except now I have
5149 * these 'spare' parts.. where shall I put them.
5151 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
5158 * Remove the lock from the list of currently held locks - this gets
5159 * called on mutex_unlock()/spin_unlock*() (or on a failed
5160 * mutex_lock_interruptible()).
5163 __lock_release(struct lockdep_map *lock, unsigned long ip)
5165 struct task_struct *curr = current;
5166 unsigned int depth, merged = 1;
5167 struct held_lock *hlock;
5170 if (unlikely(!debug_locks))
5173 depth = curr->lockdep_depth;
5175 * So we're all set to release this lock.. wait what lock? We don't
5176 * own any locks, you've been drinking again?
5179 print_unlock_imbalance_bug(curr, lock, ip);
5184 * Check whether the lock exists in the current stack
5187 hlock = find_held_lock(curr, lock, depth, &i);
5189 print_unlock_imbalance_bug(curr, lock, ip);
5193 if (hlock->instance == lock)
5194 lock_release_holdtime(hlock);
5196 WARN(hlock->pin_count, "releasing a pinned lock\n");
5198 if (hlock->references) {
5199 hlock->references--;
5200 if (hlock->references) {
5202 * We had, and after removing one, still have
5203 * references, the current lock stack is still
5204 * valid. We're done!
5211 * We have the right lock to unlock, 'hlock' points to it.
5212 * Now we remove it from the stack, and add back the other
5213 * entries (if any), recalculating the hash along the way:
5216 curr->lockdep_depth = i;
5217 curr->curr_chain_key = hlock->prev_chain_key;
5220 * The most likely case is when the unlock is on the innermost
5221 * lock. In this case, we are done!
5226 if (reacquire_held_locks(curr, depth, i + 1, &merged))
5230 * We had N bottles of beer on the wall, we drank one, but now
5231 * there's not N-1 bottles of beer left on the wall...
5232 * Pouring two of the bottles together is acceptable.
5234 DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged);
5237 * Since reacquire_held_locks() would have called check_chain_key()
5238 * indirectly via __lock_acquire(), we don't need to do it again
5244 static __always_inline
5245 int __lock_is_held(const struct lockdep_map *lock, int read)
5247 struct task_struct *curr = current;
5250 for (i = 0; i < curr->lockdep_depth; i++) {
5251 struct held_lock *hlock = curr->held_locks + i;
5253 if (match_held_lock(hlock, lock)) {
5254 if (read == -1 || hlock->read == read)
5264 static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
5266 struct pin_cookie cookie = NIL_COOKIE;
5267 struct task_struct *curr = current;
5270 if (unlikely(!debug_locks))
5273 for (i = 0; i < curr->lockdep_depth; i++) {
5274 struct held_lock *hlock = curr->held_locks + i;
5276 if (match_held_lock(hlock, lock)) {
5278 * Grab 16bits of randomness; this is sufficient to not
5279 * be guessable and still allows some pin nesting in
5280 * our u32 pin_count.
5282 cookie.val = 1 + (prandom_u32() >> 16);
5283 hlock->pin_count += cookie.val;
5288 WARN(1, "pinning an unheld lock\n");
5292 static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5294 struct task_struct *curr = current;
5297 if (unlikely(!debug_locks))
5300 for (i = 0; i < curr->lockdep_depth; i++) {
5301 struct held_lock *hlock = curr->held_locks + i;
5303 if (match_held_lock(hlock, lock)) {
5304 hlock->pin_count += cookie.val;
5309 WARN(1, "pinning an unheld lock\n");
5312 static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5314 struct task_struct *curr = current;
5317 if (unlikely(!debug_locks))
5320 for (i = 0; i < curr->lockdep_depth; i++) {
5321 struct held_lock *hlock = curr->held_locks + i;
5323 if (match_held_lock(hlock, lock)) {
5324 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
5327 hlock->pin_count -= cookie.val;
5329 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
5330 hlock->pin_count = 0;
5336 WARN(1, "unpinning an unheld lock\n");
5340 * Check whether we follow the irq-flags state precisely:
5342 static noinstr void check_flags(unsigned long flags)
5344 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP)
5348 /* Get the warning out.. */
5349 instrumentation_begin();
5351 if (irqs_disabled_flags(flags)) {
5352 if (DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())) {
5353 printk("possible reason: unannotated irqs-off.\n");
5356 if (DEBUG_LOCKS_WARN_ON(!lockdep_hardirqs_enabled())) {
5357 printk("possible reason: unannotated irqs-on.\n");
5362 * We dont accurately track softirq state in e.g.
5363 * hardirq contexts (such as on 4KSTACKS), so only
5364 * check if not in hardirq contexts:
5366 if (!hardirq_count()) {
5367 if (softirq_count()) {
5368 /* like the above, but with softirqs */
5369 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
5371 /* lick the above, does it taste good? */
5372 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
5377 print_irqtrace_events(current);
5379 instrumentation_end();
5383 void lock_set_class(struct lockdep_map *lock, const char *name,
5384 struct lock_class_key *key, unsigned int subclass,
5387 unsigned long flags;
5389 if (unlikely(!lockdep_enabled()))
5392 raw_local_irq_save(flags);
5393 lockdep_recursion_inc();
5395 if (__lock_set_class(lock, name, key, subclass, ip))
5396 check_chain_key(current);
5397 lockdep_recursion_finish();
5398 raw_local_irq_restore(flags);
5400 EXPORT_SYMBOL_GPL(lock_set_class);
5402 void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
5404 unsigned long flags;
5406 if (unlikely(!lockdep_enabled()))
5409 raw_local_irq_save(flags);
5410 lockdep_recursion_inc();
5412 if (__lock_downgrade(lock, ip))
5413 check_chain_key(current);
5414 lockdep_recursion_finish();
5415 raw_local_irq_restore(flags);
5417 EXPORT_SYMBOL_GPL(lock_downgrade);
5419 /* NMI context !!! */
5420 static void verify_lock_unused(struct lockdep_map *lock, struct held_lock *hlock, int subclass)
5422 #ifdef CONFIG_PROVE_LOCKING
5423 struct lock_class *class = look_up_lock_class(lock, subclass);
5424 unsigned long mask = LOCKF_USED;
5426 /* if it doesn't have a class (yet), it certainly hasn't been used yet */
5431 * READ locks only conflict with USED, such that if we only ever use
5432 * READ locks, there is no deadlock possible -- RCU.
5435 mask |= LOCKF_USED_READ;
5437 if (!(class->usage_mask & mask))
5440 hlock->class_idx = class - lock_classes;
5442 print_usage_bug(current, hlock, LOCK_USED, LOCK_USAGE_STATES);
5446 static bool lockdep_nmi(void)
5448 if (raw_cpu_read(lockdep_recursion))
5458 * read_lock() is recursive if:
5459 * 1. We force lockdep think this way in selftests or
5460 * 2. The implementation is not queued read/write lock or
5461 * 3. The locker is at an in_interrupt() context.
5463 bool read_lock_is_recursive(void)
5465 return force_read_lock_recursive ||
5466 !IS_ENABLED(CONFIG_QUEUED_RWLOCKS) ||
5469 EXPORT_SYMBOL_GPL(read_lock_is_recursive);
5472 * We are not always called with irqs disabled - do that here,
5473 * and also avoid lockdep recursion:
5475 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
5476 int trylock, int read, int check,
5477 struct lockdep_map *nest_lock, unsigned long ip)
5479 unsigned long flags;
5481 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
5486 if (unlikely(!lockdep_enabled())) {
5487 /* XXX allow trylock from NMI ?!? */
5488 if (lockdep_nmi() && !trylock) {
5489 struct held_lock hlock;
5491 hlock.acquire_ip = ip;
5492 hlock.instance = lock;
5493 hlock.nest_lock = nest_lock;
5494 hlock.irq_context = 2; // XXX
5495 hlock.trylock = trylock;
5497 hlock.check = check;
5498 hlock.hardirqs_off = true;
5499 hlock.references = 0;
5501 verify_lock_unused(lock, &hlock, subclass);
5506 raw_local_irq_save(flags);
5509 lockdep_recursion_inc();
5510 __lock_acquire(lock, subclass, trylock, read, check,
5511 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
5512 lockdep_recursion_finish();
5513 raw_local_irq_restore(flags);
5515 EXPORT_SYMBOL_GPL(lock_acquire);
5517 void lock_release(struct lockdep_map *lock, unsigned long ip)
5519 unsigned long flags;
5521 trace_lock_release(lock, ip);
5523 if (unlikely(!lockdep_enabled()))
5526 raw_local_irq_save(flags);
5529 lockdep_recursion_inc();
5530 if (__lock_release(lock, ip))
5531 check_chain_key(current);
5532 lockdep_recursion_finish();
5533 raw_local_irq_restore(flags);
5535 EXPORT_SYMBOL_GPL(lock_release);
5537 noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
5539 unsigned long flags;
5542 if (unlikely(!lockdep_enabled()))
5543 return 1; /* avoid false negative lockdep_assert_held() */
5545 raw_local_irq_save(flags);
5548 lockdep_recursion_inc();
5549 ret = __lock_is_held(lock, read);
5550 lockdep_recursion_finish();
5551 raw_local_irq_restore(flags);
5555 EXPORT_SYMBOL_GPL(lock_is_held_type);
5556 NOKPROBE_SYMBOL(lock_is_held_type);
5558 struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
5560 struct pin_cookie cookie = NIL_COOKIE;
5561 unsigned long flags;
5563 if (unlikely(!lockdep_enabled()))
5566 raw_local_irq_save(flags);
5569 lockdep_recursion_inc();
5570 cookie = __lock_pin_lock(lock);
5571 lockdep_recursion_finish();
5572 raw_local_irq_restore(flags);
5576 EXPORT_SYMBOL_GPL(lock_pin_lock);
5578 void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5580 unsigned long flags;
5582 if (unlikely(!lockdep_enabled()))
5585 raw_local_irq_save(flags);
5588 lockdep_recursion_inc();
5589 __lock_repin_lock(lock, cookie);
5590 lockdep_recursion_finish();
5591 raw_local_irq_restore(flags);
5593 EXPORT_SYMBOL_GPL(lock_repin_lock);
5595 void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
5597 unsigned long flags;
5599 if (unlikely(!lockdep_enabled()))
5602 raw_local_irq_save(flags);
5605 lockdep_recursion_inc();
5606 __lock_unpin_lock(lock, cookie);
5607 lockdep_recursion_finish();
5608 raw_local_irq_restore(flags);
5610 EXPORT_SYMBOL_GPL(lock_unpin_lock);
5612 #ifdef CONFIG_LOCK_STAT
5613 static void print_lock_contention_bug(struct task_struct *curr,
5614 struct lockdep_map *lock,
5617 if (!debug_locks_off())
5619 if (debug_locks_silent)
5623 pr_warn("=================================\n");
5624 pr_warn("WARNING: bad contention detected!\n");
5625 print_kernel_ident();
5626 pr_warn("---------------------------------\n");
5627 pr_warn("%s/%d is trying to contend lock (",
5628 curr->comm, task_pid_nr(curr));
5629 print_lockdep_cache(lock);
5631 print_ip_sym(KERN_WARNING, ip);
5632 pr_warn("but there are no locks held!\n");
5633 pr_warn("\nother info that might help us debug this:\n");
5634 lockdep_print_held_locks(curr);
5636 pr_warn("\nstack backtrace:\n");
5641 __lock_contended(struct lockdep_map *lock, unsigned long ip)
5643 struct task_struct *curr = current;
5644 struct held_lock *hlock;
5645 struct lock_class_stats *stats;
5647 int i, contention_point, contending_point;
5649 depth = curr->lockdep_depth;
5651 * Whee, we contended on this lock, except it seems we're not
5652 * actually trying to acquire anything much at all..
5654 if (DEBUG_LOCKS_WARN_ON(!depth))
5657 hlock = find_held_lock(curr, lock, depth, &i);
5659 print_lock_contention_bug(curr, lock, ip);
5663 if (hlock->instance != lock)
5666 hlock->waittime_stamp = lockstat_clock();
5668 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
5669 contending_point = lock_point(hlock_class(hlock)->contending_point,
5672 stats = get_lock_stats(hlock_class(hlock));
5673 if (contention_point < LOCKSTAT_POINTS)
5674 stats->contention_point[contention_point]++;
5675 if (contending_point < LOCKSTAT_POINTS)
5676 stats->contending_point[contending_point]++;
5677 if (lock->cpu != smp_processor_id())
5678 stats->bounces[bounce_contended + !!hlock->read]++;
5682 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
5684 struct task_struct *curr = current;
5685 struct held_lock *hlock;
5686 struct lock_class_stats *stats;
5688 u64 now, waittime = 0;
5691 depth = curr->lockdep_depth;
5693 * Yay, we acquired ownership of this lock we didn't try to
5694 * acquire, how the heck did that happen?
5696 if (DEBUG_LOCKS_WARN_ON(!depth))
5699 hlock = find_held_lock(curr, lock, depth, &i);
5701 print_lock_contention_bug(curr, lock, _RET_IP_);
5705 if (hlock->instance != lock)
5708 cpu = smp_processor_id();
5709 if (hlock->waittime_stamp) {
5710 now = lockstat_clock();
5711 waittime = now - hlock->waittime_stamp;
5712 hlock->holdtime_stamp = now;
5715 stats = get_lock_stats(hlock_class(hlock));
5718 lock_time_inc(&stats->read_waittime, waittime);
5720 lock_time_inc(&stats->write_waittime, waittime);
5722 if (lock->cpu != cpu)
5723 stats->bounces[bounce_acquired + !!hlock->read]++;
5729 void lock_contended(struct lockdep_map *lock, unsigned long ip)
5731 unsigned long flags;
5733 trace_lock_acquired(lock, ip);
5735 if (unlikely(!lock_stat || !lockdep_enabled()))
5738 raw_local_irq_save(flags);
5740 lockdep_recursion_inc();
5741 __lock_contended(lock, ip);
5742 lockdep_recursion_finish();
5743 raw_local_irq_restore(flags);
5745 EXPORT_SYMBOL_GPL(lock_contended);
5747 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
5749 unsigned long flags;
5751 trace_lock_contended(lock, ip);
5753 if (unlikely(!lock_stat || !lockdep_enabled()))
5756 raw_local_irq_save(flags);
5758 lockdep_recursion_inc();
5759 __lock_acquired(lock, ip);
5760 lockdep_recursion_finish();
5761 raw_local_irq_restore(flags);
5763 EXPORT_SYMBOL_GPL(lock_acquired);
5767 * Used by the testsuite, sanitize the validator state
5768 * after a simulated failure:
5771 void lockdep_reset(void)
5773 unsigned long flags;
5776 raw_local_irq_save(flags);
5777 lockdep_init_task(current);
5778 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
5779 nr_hardirq_chains = 0;
5780 nr_softirq_chains = 0;
5781 nr_process_chains = 0;
5783 for (i = 0; i < CHAINHASH_SIZE; i++)
5784 INIT_HLIST_HEAD(chainhash_table + i);
5785 raw_local_irq_restore(flags);
5788 /* Remove a class from a lock chain. Must be called with the graph lock held. */
5789 static void remove_class_from_lock_chain(struct pending_free *pf,
5790 struct lock_chain *chain,
5791 struct lock_class *class)
5793 #ifdef CONFIG_PROVE_LOCKING
5796 for (i = chain->base; i < chain->base + chain->depth; i++) {
5797 if (chain_hlock_class_idx(chain_hlocks[i]) != class - lock_classes)
5800 * Each lock class occurs at most once in a lock chain so once
5801 * we found a match we can break out of this loop.
5803 goto free_lock_chain;
5805 /* Since the chain has not been modified, return. */
5809 free_chain_hlocks(chain->base, chain->depth);
5810 /* Overwrite the chain key for concurrent RCU readers. */
5811 WRITE_ONCE(chain->chain_key, INITIAL_CHAIN_KEY);
5812 dec_chains(chain->irq_context);
5815 * Note: calling hlist_del_rcu() from inside a
5816 * hlist_for_each_entry_rcu() loop is safe.
5818 hlist_del_rcu(&chain->entry);
5819 __set_bit(chain - lock_chains, pf->lock_chains_being_freed);
5820 nr_zapped_lock_chains++;
5824 /* Must be called with the graph lock held. */
5825 static void remove_class_from_lock_chains(struct pending_free *pf,
5826 struct lock_class *class)
5828 struct lock_chain *chain;
5829 struct hlist_head *head;
5832 for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
5833 head = chainhash_table + i;
5834 hlist_for_each_entry_rcu(chain, head, entry) {
5835 remove_class_from_lock_chain(pf, chain, class);
5841 * Remove all references to a lock class. The caller must hold the graph lock.
5843 static void zap_class(struct pending_free *pf, struct lock_class *class)
5845 struct lock_list *entry;
5848 WARN_ON_ONCE(!class->key);
5851 * Remove all dependencies this lock is
5854 for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
5855 entry = list_entries + i;
5856 if (entry->class != class && entry->links_to != class)
5858 __clear_bit(i, list_entries_in_use);
5860 list_del_rcu(&entry->entry);
5862 if (list_empty(&class->locks_after) &&
5863 list_empty(&class->locks_before)) {
5864 list_move_tail(&class->lock_entry, &pf->zapped);
5865 hlist_del_rcu(&class->hash_entry);
5866 WRITE_ONCE(class->key, NULL);
5867 WRITE_ONCE(class->name, NULL);
5869 __clear_bit(class - lock_classes, lock_classes_in_use);
5871 WARN_ONCE(true, "%s() failed for class %s\n", __func__,
5875 remove_class_from_lock_chains(pf, class);
5876 nr_zapped_classes++;
5879 static void reinit_class(struct lock_class *class)
5881 void *const p = class;
5882 const unsigned int offset = offsetof(struct lock_class, key);
5884 WARN_ON_ONCE(!class->lock_entry.next);
5885 WARN_ON_ONCE(!list_empty(&class->locks_after));
5886 WARN_ON_ONCE(!list_empty(&class->locks_before));
5887 memset(p + offset, 0, sizeof(*class) - offset);
5888 WARN_ON_ONCE(!class->lock_entry.next);
5889 WARN_ON_ONCE(!list_empty(&class->locks_after));
5890 WARN_ON_ONCE(!list_empty(&class->locks_before));
5893 static inline int within(const void *addr, void *start, unsigned long size)
5895 return addr >= start && addr < start + size;
5898 static bool inside_selftest(void)
5900 return current == lockdep_selftest_task_struct;
5903 /* The caller must hold the graph lock. */
5904 static struct pending_free *get_pending_free(void)
5906 return delayed_free.pf + delayed_free.index;
5909 static void free_zapped_rcu(struct rcu_head *cb);
5912 * Schedule an RCU callback if no RCU callback is pending. Must be called with
5913 * the graph lock held.
5915 static void call_rcu_zapped(struct pending_free *pf)
5917 WARN_ON_ONCE(inside_selftest());
5919 if (list_empty(&pf->zapped))
5922 if (delayed_free.scheduled)
5925 delayed_free.scheduled = true;
5927 WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf);
5928 delayed_free.index ^= 1;
5930 call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
5933 /* The caller must hold the graph lock. May be called from RCU context. */
5934 static void __free_zapped_classes(struct pending_free *pf)
5936 struct lock_class *class;
5938 check_data_structures();
5940 list_for_each_entry(class, &pf->zapped, lock_entry)
5941 reinit_class(class);
5943 list_splice_init(&pf->zapped, &free_lock_classes);
5945 #ifdef CONFIG_PROVE_LOCKING
5946 bitmap_andnot(lock_chains_in_use, lock_chains_in_use,
5947 pf->lock_chains_being_freed, ARRAY_SIZE(lock_chains));
5948 bitmap_clear(pf->lock_chains_being_freed, 0, ARRAY_SIZE(lock_chains));
5952 static void free_zapped_rcu(struct rcu_head *ch)
5954 struct pending_free *pf;
5955 unsigned long flags;
5957 if (WARN_ON_ONCE(ch != &delayed_free.rcu_head))
5960 raw_local_irq_save(flags);
5964 pf = delayed_free.pf + (delayed_free.index ^ 1);
5965 __free_zapped_classes(pf);
5966 delayed_free.scheduled = false;
5969 * If there's anything on the open list, close and start a new callback.
5971 call_rcu_zapped(delayed_free.pf + delayed_free.index);
5974 raw_local_irq_restore(flags);
5978 * Remove all lock classes from the class hash table and from the
5979 * all_lock_classes list whose key or name is in the address range [start,
5980 * start + size). Move these lock classes to the zapped_classes list. Must
5981 * be called with the graph lock held.
5983 static void __lockdep_free_key_range(struct pending_free *pf, void *start,
5986 struct lock_class *class;
5987 struct hlist_head *head;
5990 /* Unhash all classes that were created by a module. */
5991 for (i = 0; i < CLASSHASH_SIZE; i++) {
5992 head = classhash_table + i;
5993 hlist_for_each_entry_rcu(class, head, hash_entry) {
5994 if (!within(class->key, start, size) &&
5995 !within(class->name, start, size))
5997 zap_class(pf, class);
6003 * Used in module.c to remove lock classes from memory that is going to be
6004 * freed; and possibly re-used by other modules.
6006 * We will have had one synchronize_rcu() before getting here, so we're
6007 * guaranteed nobody will look up these exact classes -- they're properly dead
6008 * but still allocated.
6010 static void lockdep_free_key_range_reg(void *start, unsigned long size)
6012 struct pending_free *pf;
6013 unsigned long flags;
6015 init_data_structures_once();
6017 raw_local_irq_save(flags);
6019 pf = get_pending_free();
6020 __lockdep_free_key_range(pf, start, size);
6021 call_rcu_zapped(pf);
6023 raw_local_irq_restore(flags);
6026 * Wait for any possible iterators from look_up_lock_class() to pass
6027 * before continuing to free the memory they refer to.
6033 * Free all lockdep keys in the range [start, start+size). Does not sleep.
6034 * Ignores debug_locks. Must only be used by the lockdep selftests.
6036 static void lockdep_free_key_range_imm(void *start, unsigned long size)
6038 struct pending_free *pf = delayed_free.pf;
6039 unsigned long flags;
6041 init_data_structures_once();
6043 raw_local_irq_save(flags);
6045 __lockdep_free_key_range(pf, start, size);
6046 __free_zapped_classes(pf);
6048 raw_local_irq_restore(flags);
6051 void lockdep_free_key_range(void *start, unsigned long size)
6053 init_data_structures_once();
6055 if (inside_selftest())
6056 lockdep_free_key_range_imm(start, size);
6058 lockdep_free_key_range_reg(start, size);
6062 * Check whether any element of the @lock->class_cache[] array refers to a
6063 * registered lock class. The caller must hold either the graph lock or the
6066 static bool lock_class_cache_is_registered(struct lockdep_map *lock)
6068 struct lock_class *class;
6069 struct hlist_head *head;
6072 for (i = 0; i < CLASSHASH_SIZE; i++) {
6073 head = classhash_table + i;
6074 hlist_for_each_entry_rcu(class, head, hash_entry) {
6075 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
6076 if (lock->class_cache[j] == class)
6083 /* The caller must hold the graph lock. Does not sleep. */
6084 static void __lockdep_reset_lock(struct pending_free *pf,
6085 struct lockdep_map *lock)
6087 struct lock_class *class;
6091 * Remove all classes this lock might have:
6093 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
6095 * If the class exists we look it up and zap it:
6097 class = look_up_lock_class(lock, j);
6099 zap_class(pf, class);
6102 * Debug check: in the end all mapped classes should
6105 if (WARN_ON_ONCE(lock_class_cache_is_registered(lock)))
6110 * Remove all information lockdep has about a lock if debug_locks == 1. Free
6111 * released data structures from RCU context.
6113 static void lockdep_reset_lock_reg(struct lockdep_map *lock)
6115 struct pending_free *pf;
6116 unsigned long flags;
6119 raw_local_irq_save(flags);
6120 locked = graph_lock();
6124 pf = get_pending_free();
6125 __lockdep_reset_lock(pf, lock);
6126 call_rcu_zapped(pf);
6130 raw_local_irq_restore(flags);
6134 * Reset a lock. Does not sleep. Ignores debug_locks. Must only be used by the
6135 * lockdep selftests.
6137 static void lockdep_reset_lock_imm(struct lockdep_map *lock)
6139 struct pending_free *pf = delayed_free.pf;
6140 unsigned long flags;
6142 raw_local_irq_save(flags);
6144 __lockdep_reset_lock(pf, lock);
6145 __free_zapped_classes(pf);
6147 raw_local_irq_restore(flags);
6150 void lockdep_reset_lock(struct lockdep_map *lock)
6152 init_data_structures_once();
6154 if (inside_selftest())
6155 lockdep_reset_lock_imm(lock);
6157 lockdep_reset_lock_reg(lock);
6160 /* Unregister a dynamically allocated key. */
6161 void lockdep_unregister_key(struct lock_class_key *key)
6163 struct hlist_head *hash_head = keyhashentry(key);
6164 struct lock_class_key *k;
6165 struct pending_free *pf;
6166 unsigned long flags;
6171 if (WARN_ON_ONCE(static_obj(key)))
6174 raw_local_irq_save(flags);
6178 pf = get_pending_free();
6179 hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
6181 hlist_del_rcu(&k->hash_entry);
6186 WARN_ON_ONCE(!found);
6187 __lockdep_free_key_range(pf, key, 1);
6188 call_rcu_zapped(pf);
6191 raw_local_irq_restore(flags);
6193 /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */
6196 EXPORT_SYMBOL_GPL(lockdep_unregister_key);
6198 void __init lockdep_init(void)
6200 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
6202 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
6203 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
6204 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
6205 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
6206 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
6207 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
6208 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
6210 printk(" memory used by lock dependency info: %zu kB\n",
6211 (sizeof(lock_classes) +
6212 sizeof(lock_classes_in_use) +
6213 sizeof(classhash_table) +
6214 sizeof(list_entries) +
6215 sizeof(list_entries_in_use) +
6216 sizeof(chainhash_table) +
6217 sizeof(delayed_free)
6218 #ifdef CONFIG_PROVE_LOCKING
6220 + sizeof(lock_chains)
6221 + sizeof(lock_chains_in_use)
6222 + sizeof(chain_hlocks)
6227 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
6228 printk(" memory used for stack traces: %zu kB\n",
6229 (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024
6233 printk(" per task-struct memory footprint: %zu bytes\n",
6234 sizeof(((struct task_struct *)NULL)->held_locks));
6238 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
6239 const void *mem_to, struct held_lock *hlock)
6241 if (!debug_locks_off())
6243 if (debug_locks_silent)
6247 pr_warn("=========================\n");
6248 pr_warn("WARNING: held lock freed!\n");
6249 print_kernel_ident();
6250 pr_warn("-------------------------\n");
6251 pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
6252 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
6254 lockdep_print_held_locks(curr);
6256 pr_warn("\nstack backtrace:\n");
6260 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
6261 const void* lock_from, unsigned long lock_len)
6263 return lock_from + lock_len <= mem_from ||
6264 mem_from + mem_len <= lock_from;
6268 * Called when kernel memory is freed (or unmapped), or if a lock
6269 * is destroyed or reinitialized - this code checks whether there is
6270 * any held lock in the memory range of <from> to <to>:
6272 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
6274 struct task_struct *curr = current;
6275 struct held_lock *hlock;
6276 unsigned long flags;
6279 if (unlikely(!debug_locks))
6282 raw_local_irq_save(flags);
6283 for (i = 0; i < curr->lockdep_depth; i++) {
6284 hlock = curr->held_locks + i;
6286 if (not_in_range(mem_from, mem_len, hlock->instance,
6287 sizeof(*hlock->instance)))
6290 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
6293 raw_local_irq_restore(flags);
6295 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
6297 static void print_held_locks_bug(void)
6299 if (!debug_locks_off())
6301 if (debug_locks_silent)
6305 pr_warn("====================================\n");
6306 pr_warn("WARNING: %s/%d still has locks held!\n",
6307 current->comm, task_pid_nr(current));
6308 print_kernel_ident();
6309 pr_warn("------------------------------------\n");
6310 lockdep_print_held_locks(current);
6311 pr_warn("\nstack backtrace:\n");
6315 void debug_check_no_locks_held(void)
6317 if (unlikely(current->lockdep_depth > 0))
6318 print_held_locks_bug();
6320 EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
6323 void debug_show_all_locks(void)
6325 struct task_struct *g, *p;
6327 if (unlikely(!debug_locks)) {
6328 pr_warn("INFO: lockdep is turned off.\n");
6331 pr_warn("\nShowing all locks held in the system:\n");
6334 for_each_process_thread(g, p) {
6335 if (!p->lockdep_depth)
6337 lockdep_print_held_locks(p);
6338 touch_nmi_watchdog();
6339 touch_all_softlockup_watchdogs();
6344 pr_warn("=============================================\n\n");
6346 EXPORT_SYMBOL_GPL(debug_show_all_locks);
6350 * Careful: only use this function if you are sure that
6351 * the task cannot run in parallel!
6353 void debug_show_held_locks(struct task_struct *task)
6355 if (unlikely(!debug_locks)) {
6356 printk("INFO: lockdep is turned off.\n");
6359 lockdep_print_held_locks(task);
6361 EXPORT_SYMBOL_GPL(debug_show_held_locks);
6363 asmlinkage __visible void lockdep_sys_exit(void)
6365 struct task_struct *curr = current;
6367 if (unlikely(curr->lockdep_depth)) {
6368 if (!debug_locks_off())
6371 pr_warn("================================================\n");
6372 pr_warn("WARNING: lock held when returning to user space!\n");
6373 print_kernel_ident();
6374 pr_warn("------------------------------------------------\n");
6375 pr_warn("%s/%d is leaving the kernel with locks still held!\n",
6376 curr->comm, curr->pid);
6377 lockdep_print_held_locks(curr);
6381 * The lock history for each syscall should be independent. So wipe the
6382 * slate clean on return to userspace.
6384 lockdep_invariant_state(false);
6387 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
6389 struct task_struct *curr = current;
6391 /* Note: the following can be executed concurrently, so be careful. */
6393 pr_warn("=============================\n");
6394 pr_warn("WARNING: suspicious RCU usage\n");
6395 print_kernel_ident();
6396 pr_warn("-----------------------------\n");
6397 pr_warn("%s:%d %s!\n", file, line, s);
6398 pr_warn("\nother info that might help us debug this:\n\n");
6399 pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
6400 !rcu_lockdep_current_cpu_online()
6401 ? "RCU used illegally from offline CPU!\n"
6403 rcu_scheduler_active, debug_locks);
6406 * If a CPU is in the RCU-free window in idle (ie: in the section
6407 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
6408 * considers that CPU to be in an "extended quiescent state",
6409 * which means that RCU will be completely ignoring that CPU.
6410 * Therefore, rcu_read_lock() and friends have absolutely no
6411 * effect on a CPU running in that state. In other words, even if
6412 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
6413 * delete data structures out from under it. RCU really has no
6414 * choice here: we need to keep an RCU-free window in idle where
6415 * the CPU may possibly enter into low power mode. This way we can
6416 * notice an extended quiescent state to other CPUs that started a grace
6417 * period. Otherwise we would delay any grace period as long as we run
6420 * So complain bitterly if someone does call rcu_read_lock(),
6421 * rcu_read_lock_bh() and so on from extended quiescent states.
6423 if (!rcu_is_watching())
6424 pr_warn("RCU used illegally from extended quiescent state!\n");
6426 lockdep_print_held_locks(curr);
6427 pr_warn("\nstack backtrace:\n");
6430 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);