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1/*
2 * kernel/lockdep.c
3 *
4 * Runtime locking correctness validator
5 *
6 * Started by Ingo Molnar:
7 *
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
10 *
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
13 *
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
17 *
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
20 *
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
24 *
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
27 */
28#define DISABLE_BRANCH_PROFILING
29#include <linux/mutex.h>
30#include <linux/sched.h>
31#include <linux/delay.h>
32#include <linux/module.h>
33#include <linux/proc_fs.h>
34#include <linux/seq_file.h>
35#include <linux/spinlock.h>
36#include <linux/kallsyms.h>
37#include <linux/interrupt.h>
38#include <linux/stacktrace.h>
39#include <linux/debug_locks.h>
40#include <linux/irqflags.h>
41#include <linux/utsname.h>
42#include <linux/hash.h>
43#include <linux/ftrace.h>
44#include <linux/stringify.h>
45#include <linux/bitops.h>
46#include <linux/gfp.h>
47#include <linux/kmemcheck.h>
48#include <linux/random.h>
49#include <linux/jhash.h>
50
51#include <asm/sections.h>
52
53#include "lockdep_internals.h"
54
55#define CREATE_TRACE_POINTS
56#include <trace/events/lock.h>
57
58#ifdef CONFIG_PROVE_LOCKING
59int prove_locking = 1;
60module_param(prove_locking, int, 0644);
61#else
62#define prove_locking 0
63#endif
64
65#ifdef CONFIG_LOCK_STAT
66int lock_stat = 1;
67module_param(lock_stat, int, 0644);
68#else
69#define lock_stat 0
70#endif
71
72/*
73 * lockdep_lock: protects the lockdep graph, the hashes and the
74 * class/list/hash allocators.
75 *
76 * This is one of the rare exceptions where it's justified
77 * to use a raw spinlock - we really dont want the spinlock
78 * code to recurse back into the lockdep code...
79 */
80static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
81
82static int graph_lock(void)
83{
84 arch_spin_lock(&lockdep_lock);
85 /*
86 * Make sure that if another CPU detected a bug while
87 * walking the graph we dont change it (while the other
88 * CPU is busy printing out stuff with the graph lock
89 * dropped already)
90 */
91 if (!debug_locks) {
92 arch_spin_unlock(&lockdep_lock);
93 return 0;
94 }
95 /* prevent any recursions within lockdep from causing deadlocks */
96 current->lockdep_recursion++;
97 return 1;
98}
99
100static inline int graph_unlock(void)
101{
102 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
103 /*
104 * The lockdep graph lock isn't locked while we expect it to
105 * be, we're confused now, bye!
106 */
107 return DEBUG_LOCKS_WARN_ON(1);
108 }
109
110 current->lockdep_recursion--;
111 arch_spin_unlock(&lockdep_lock);
112 return 0;
113}
114
115/*
116 * Turn lock debugging off and return with 0 if it was off already,
117 * and also release the graph lock:
118 */
119static inline int debug_locks_off_graph_unlock(void)
120{
121 int ret = debug_locks_off();
122
123 arch_spin_unlock(&lockdep_lock);
124
125 return ret;
126}
127
128unsigned long nr_list_entries;
129static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
130
131/*
132 * All data structures here are protected by the global debug_lock.
133 *
134 * Mutex key structs only get allocated, once during bootup, and never
135 * get freed - this significantly simplifies the debugging code.
136 */
137unsigned long nr_lock_classes;
138static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
139
140static inline struct lock_class *hlock_class(struct held_lock *hlock)
141{
142 if (!hlock->class_idx) {
143 /*
144 * Someone passed in garbage, we give up.
145 */
146 DEBUG_LOCKS_WARN_ON(1);
147 return NULL;
148 }
149 return lock_classes + hlock->class_idx - 1;
150}
151
152#ifdef CONFIG_LOCK_STAT
153static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
154
155static inline u64 lockstat_clock(void)
156{
157 return local_clock();
158}
159
160static int lock_point(unsigned long points[], unsigned long ip)
161{
162 int i;
163
164 for (i = 0; i < LOCKSTAT_POINTS; i++) {
165 if (points[i] == 0) {
166 points[i] = ip;
167 break;
168 }
169 if (points[i] == ip)
170 break;
171 }
172
173 return i;
174}
175
176static void lock_time_inc(struct lock_time *lt, u64 time)
177{
178 if (time > lt->max)
179 lt->max = time;
180
181 if (time < lt->min || !lt->nr)
182 lt->min = time;
183
184 lt->total += time;
185 lt->nr++;
186}
187
188static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
189{
190 if (!src->nr)
191 return;
192
193 if (src->max > dst->max)
194 dst->max = src->max;
195
196 if (src->min < dst->min || !dst->nr)
197 dst->min = src->min;
198
199 dst->total += src->total;
200 dst->nr += src->nr;
201}
202
203struct lock_class_stats lock_stats(struct lock_class *class)
204{
205 struct lock_class_stats stats;
206 int cpu, i;
207
208 memset(&stats, 0, sizeof(struct lock_class_stats));
209 for_each_possible_cpu(cpu) {
210 struct lock_class_stats *pcs =
211 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
212
213 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
214 stats.contention_point[i] += pcs->contention_point[i];
215
216 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
217 stats.contending_point[i] += pcs->contending_point[i];
218
219 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
220 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
221
222 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
223 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
224
225 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
226 stats.bounces[i] += pcs->bounces[i];
227 }
228
229 return stats;
230}
231
232void clear_lock_stats(struct lock_class *class)
233{
234 int cpu;
235
236 for_each_possible_cpu(cpu) {
237 struct lock_class_stats *cpu_stats =
238 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
239
240 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
241 }
242 memset(class->contention_point, 0, sizeof(class->contention_point));
243 memset(class->contending_point, 0, sizeof(class->contending_point));
244}
245
246static struct lock_class_stats *get_lock_stats(struct lock_class *class)
247{
248 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
249}
250
251static void put_lock_stats(struct lock_class_stats *stats)
252{
253 put_cpu_var(cpu_lock_stats);
254}
255
256static void lock_release_holdtime(struct held_lock *hlock)
257{
258 struct lock_class_stats *stats;
259 u64 holdtime;
260
261 if (!lock_stat)
262 return;
263
264 holdtime = lockstat_clock() - hlock->holdtime_stamp;
265
266 stats = get_lock_stats(hlock_class(hlock));
267 if (hlock->read)
268 lock_time_inc(&stats->read_holdtime, holdtime);
269 else
270 lock_time_inc(&stats->write_holdtime, holdtime);
271 put_lock_stats(stats);
272}
273#else
274static inline void lock_release_holdtime(struct held_lock *hlock)
275{
276}
277#endif
278
279/*
280 * We keep a global list of all lock classes. The list only grows,
281 * never shrinks. The list is only accessed with the lockdep
282 * spinlock lock held.
283 */
284LIST_HEAD(all_lock_classes);
285
286/*
287 * The lockdep classes are in a hash-table as well, for fast lookup:
288 */
289#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
290#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
291#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
292#define classhashentry(key) (classhash_table + __classhashfn((key)))
293
294static struct hlist_head classhash_table[CLASSHASH_SIZE];
295
296/*
297 * We put the lock dependency chains into a hash-table as well, to cache
298 * their existence:
299 */
300#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
301#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
302#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
303#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
304
305static struct hlist_head chainhash_table[CHAINHASH_SIZE];
306
307/*
308 * The hash key of the lock dependency chains is a hash itself too:
309 * it's a hash of all locks taken up to that lock, including that lock.
310 * It's a 64-bit hash, because it's important for the keys to be
311 * unique.
312 */
313static inline u64 iterate_chain_key(u64 key, u32 idx)
314{
315 u32 k0 = key, k1 = key >> 32;
316
317 __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
318
319 return k0 | (u64)k1 << 32;
320}
321
322void lockdep_off(void)
323{
324 current->lockdep_recursion++;
325}
326EXPORT_SYMBOL(lockdep_off);
327
328void lockdep_on(void)
329{
330 current->lockdep_recursion--;
331}
332EXPORT_SYMBOL(lockdep_on);
333
334/*
335 * Debugging switches:
336 */
337
338#define VERBOSE 0
339#define VERY_VERBOSE 0
340
341#if VERBOSE
342# define HARDIRQ_VERBOSE 1
343# define SOFTIRQ_VERBOSE 1
344# define RECLAIM_VERBOSE 1
345#else
346# define HARDIRQ_VERBOSE 0
347# define SOFTIRQ_VERBOSE 0
348# define RECLAIM_VERBOSE 0
349#endif
350
351#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
352/*
353 * Quick filtering for interesting events:
354 */
355static int class_filter(struct lock_class *class)
356{
357#if 0
358 /* Example */
359 if (class->name_version == 1 &&
360 !strcmp(class->name, "lockname"))
361 return 1;
362 if (class->name_version == 1 &&
363 !strcmp(class->name, "&struct->lockfield"))
364 return 1;
365#endif
366 /* Filter everything else. 1 would be to allow everything else */
367 return 0;
368}
369#endif
370
371static int verbose(struct lock_class *class)
372{
373#if VERBOSE
374 return class_filter(class);
375#endif
376 return 0;
377}
378
379/*
380 * Stack-trace: tightly packed array of stack backtrace
381 * addresses. Protected by the graph_lock.
382 */
383unsigned long nr_stack_trace_entries;
384static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
385
386static void print_lockdep_off(const char *bug_msg)
387{
388 printk(KERN_DEBUG "%s\n", bug_msg);
389 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
390#ifdef CONFIG_LOCK_STAT
391 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
392#endif
393}
394
395static int save_trace(struct stack_trace *trace)
396{
397 trace->nr_entries = 0;
398 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
399 trace->entries = stack_trace + nr_stack_trace_entries;
400
401 trace->skip = 3;
402
403 save_stack_trace(trace);
404
405 /*
406 * Some daft arches put -1 at the end to indicate its a full trace.
407 *
408 * <rant> this is buggy anyway, since it takes a whole extra entry so a
409 * complete trace that maxes out the entries provided will be reported
410 * as incomplete, friggin useless </rant>
411 */
412 if (trace->nr_entries != 0 &&
413 trace->entries[trace->nr_entries-1] == ULONG_MAX)
414 trace->nr_entries--;
415
416 trace->max_entries = trace->nr_entries;
417
418 nr_stack_trace_entries += trace->nr_entries;
419
420 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
421 if (!debug_locks_off_graph_unlock())
422 return 0;
423
424 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
425 dump_stack();
426
427 return 0;
428 }
429
430 return 1;
431}
432
433unsigned int nr_hardirq_chains;
434unsigned int nr_softirq_chains;
435unsigned int nr_process_chains;
436unsigned int max_lockdep_depth;
437
438#ifdef CONFIG_DEBUG_LOCKDEP
439/*
440 * Various lockdep statistics:
441 */
442DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
443#endif
444
445/*
446 * Locking printouts:
447 */
448
449#define __USAGE(__STATE) \
450 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
451 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
452 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
453 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
454
455static const char *usage_str[] =
456{
457#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
458#include "lockdep_states.h"
459#undef LOCKDEP_STATE
460 [LOCK_USED] = "INITIAL USE",
461};
462
463const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
464{
465 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
466}
467
468static inline unsigned long lock_flag(enum lock_usage_bit bit)
469{
470 return 1UL << bit;
471}
472
473static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
474{
475 char c = '.';
476
477 if (class->usage_mask & lock_flag(bit + 2))
478 c = '+';
479 if (class->usage_mask & lock_flag(bit)) {
480 c = '-';
481 if (class->usage_mask & lock_flag(bit + 2))
482 c = '?';
483 }
484
485 return c;
486}
487
488void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
489{
490 int i = 0;
491
492#define LOCKDEP_STATE(__STATE) \
493 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
494 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
495#include "lockdep_states.h"
496#undef LOCKDEP_STATE
497
498 usage[i] = '\0';
499}
500
501static void __print_lock_name(struct lock_class *class)
502{
503 char str[KSYM_NAME_LEN];
504 const char *name;
505
506 name = class->name;
507 if (!name) {
508 name = __get_key_name(class->key, str);
509 printk(KERN_CONT "%s", name);
510 } else {
511 printk(KERN_CONT "%s", name);
512 if (class->name_version > 1)
513 printk(KERN_CONT "#%d", class->name_version);
514 if (class->subclass)
515 printk(KERN_CONT "/%d", class->subclass);
516 }
517}
518
519static void print_lock_name(struct lock_class *class)
520{
521 char usage[LOCK_USAGE_CHARS];
522
523 get_usage_chars(class, usage);
524
525 printk(KERN_CONT " (");
526 __print_lock_name(class);
527 printk(KERN_CONT "){%s}", usage);
528}
529
530static void print_lockdep_cache(struct lockdep_map *lock)
531{
532 const char *name;
533 char str[KSYM_NAME_LEN];
534
535 name = lock->name;
536 if (!name)
537 name = __get_key_name(lock->key->subkeys, str);
538
539 printk(KERN_CONT "%s", name);
540}
541
542static void print_lock(struct held_lock *hlock)
543{
544 /*
545 * We can be called locklessly through debug_show_all_locks() so be
546 * extra careful, the hlock might have been released and cleared.
547 */
548 unsigned int class_idx = hlock->class_idx;
549
550 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
551 barrier();
552
553 if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
554 printk(KERN_CONT "<RELEASED>\n");
555 return;
556 }
557
558 print_lock_name(lock_classes + class_idx - 1);
559 printk(KERN_CONT ", at: [<%p>] %pS\n",
560 (void *)hlock->acquire_ip, (void *)hlock->acquire_ip);
561}
562
563static void lockdep_print_held_locks(struct task_struct *curr)
564{
565 int i, depth = curr->lockdep_depth;
566
567 if (!depth) {
568 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
569 return;
570 }
571 printk("%d lock%s held by %s/%d:\n",
572 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
573
574 for (i = 0; i < depth; i++) {
575 printk(" #%d: ", i);
576 print_lock(curr->held_locks + i);
577 }
578}
579
580static void print_kernel_ident(void)
581{
582 printk("%s %.*s %s\n", init_utsname()->release,
583 (int)strcspn(init_utsname()->version, " "),
584 init_utsname()->version,
585 print_tainted());
586}
587
588static int very_verbose(struct lock_class *class)
589{
590#if VERY_VERBOSE
591 return class_filter(class);
592#endif
593 return 0;
594}
595
596/*
597 * Is this the address of a static object:
598 */
599#ifdef __KERNEL__
600static int static_obj(void *obj)
601{
602 unsigned long start = (unsigned long) &_stext,
603 end = (unsigned long) &_end,
604 addr = (unsigned long) obj;
605
606 /*
607 * static variable?
608 */
609 if ((addr >= start) && (addr < end))
610 return 1;
611
612 if (arch_is_kernel_data(addr))
613 return 1;
614
615 /*
616 * in-kernel percpu var?
617 */
618 if (is_kernel_percpu_address(addr))
619 return 1;
620
621 /*
622 * module static or percpu var?
623 */
624 return is_module_address(addr) || is_module_percpu_address(addr);
625}
626#endif
627
628/*
629 * To make lock name printouts unique, we calculate a unique
630 * class->name_version generation counter:
631 */
632static int count_matching_names(struct lock_class *new_class)
633{
634 struct lock_class *class;
635 int count = 0;
636
637 if (!new_class->name)
638 return 0;
639
640 list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
641 if (new_class->key - new_class->subclass == class->key)
642 return class->name_version;
643 if (class->name && !strcmp(class->name, new_class->name))
644 count = max(count, class->name_version);
645 }
646
647 return count + 1;
648}
649
650/*
651 * Register a lock's class in the hash-table, if the class is not present
652 * yet. Otherwise we look it up. We cache the result in the lock object
653 * itself, so actual lookup of the hash should be once per lock object.
654 */
655static inline struct lock_class *
656look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
657{
658 struct lockdep_subclass_key *key;
659 struct hlist_head *hash_head;
660 struct lock_class *class;
661
662 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
663 debug_locks_off();
664 printk(KERN_ERR
665 "BUG: looking up invalid subclass: %u\n", subclass);
666 printk(KERN_ERR
667 "turning off the locking correctness validator.\n");
668 dump_stack();
669 return NULL;
670 }
671
672 /*
673 * Static locks do not have their class-keys yet - for them the key
674 * is the lock object itself:
675 */
676 if (unlikely(!lock->key))
677 lock->key = (void *)lock;
678
679 /*
680 * NOTE: the class-key must be unique. For dynamic locks, a static
681 * lock_class_key variable is passed in through the mutex_init()
682 * (or spin_lock_init()) call - which acts as the key. For static
683 * locks we use the lock object itself as the key.
684 */
685 BUILD_BUG_ON(sizeof(struct lock_class_key) >
686 sizeof(struct lockdep_map));
687
688 key = lock->key->subkeys + subclass;
689
690 hash_head = classhashentry(key);
691
692 /*
693 * We do an RCU walk of the hash, see lockdep_free_key_range().
694 */
695 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
696 return NULL;
697
698 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
699 if (class->key == key) {
700 /*
701 * Huh! same key, different name? Did someone trample
702 * on some memory? We're most confused.
703 */
704 WARN_ON_ONCE(class->name != lock->name);
705 return class;
706 }
707 }
708
709 return NULL;
710}
711
712/*
713 * Register a lock's class in the hash-table, if the class is not present
714 * yet. Otherwise we look it up. We cache the result in the lock object
715 * itself, so actual lookup of the hash should be once per lock object.
716 */
717static struct lock_class *
718register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
719{
720 struct lockdep_subclass_key *key;
721 struct hlist_head *hash_head;
722 struct lock_class *class;
723
724 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
725
726 class = look_up_lock_class(lock, subclass);
727 if (likely(class))
728 goto out_set_class_cache;
729
730 /*
731 * Debug-check: all keys must be persistent!
732 */
733 if (!static_obj(lock->key)) {
734 debug_locks_off();
735 printk("INFO: trying to register non-static key.\n");
736 printk("the code is fine but needs lockdep annotation.\n");
737 printk("turning off the locking correctness validator.\n");
738 dump_stack();
739
740 return NULL;
741 }
742
743 key = lock->key->subkeys + subclass;
744 hash_head = classhashentry(key);
745
746 if (!graph_lock()) {
747 return NULL;
748 }
749 /*
750 * We have to do the hash-walk again, to avoid races
751 * with another CPU:
752 */
753 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
754 if (class->key == key)
755 goto out_unlock_set;
756 }
757
758 /*
759 * Allocate a new key from the static array, and add it to
760 * the hash:
761 */
762 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
763 if (!debug_locks_off_graph_unlock()) {
764 return NULL;
765 }
766
767 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
768 dump_stack();
769 return NULL;
770 }
771 class = lock_classes + nr_lock_classes++;
772 debug_atomic_inc(nr_unused_locks);
773 class->key = key;
774 class->name = lock->name;
775 class->subclass = subclass;
776 INIT_LIST_HEAD(&class->lock_entry);
777 INIT_LIST_HEAD(&class->locks_before);
778 INIT_LIST_HEAD(&class->locks_after);
779 class->name_version = count_matching_names(class);
780 /*
781 * We use RCU's safe list-add method to make
782 * parallel walking of the hash-list safe:
783 */
784 hlist_add_head_rcu(&class->hash_entry, hash_head);
785 /*
786 * Add it to the global list of classes:
787 */
788 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
789
790 if (verbose(class)) {
791 graph_unlock();
792
793 printk("\nnew class %p: %s", class->key, class->name);
794 if (class->name_version > 1)
795 printk(KERN_CONT "#%d", class->name_version);
796 printk(KERN_CONT "\n");
797 dump_stack();
798
799 if (!graph_lock()) {
800 return NULL;
801 }
802 }
803out_unlock_set:
804 graph_unlock();
805
806out_set_class_cache:
807 if (!subclass || force)
808 lock->class_cache[0] = class;
809 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
810 lock->class_cache[subclass] = class;
811
812 /*
813 * Hash collision, did we smoke some? We found a class with a matching
814 * hash but the subclass -- which is hashed in -- didn't match.
815 */
816 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
817 return NULL;
818
819 return class;
820}
821
822#ifdef CONFIG_PROVE_LOCKING
823/*
824 * Allocate a lockdep entry. (assumes the graph_lock held, returns
825 * with NULL on failure)
826 */
827static struct lock_list *alloc_list_entry(void)
828{
829 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
830 if (!debug_locks_off_graph_unlock())
831 return NULL;
832
833 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
834 dump_stack();
835 return NULL;
836 }
837 return list_entries + nr_list_entries++;
838}
839
840/*
841 * Add a new dependency to the head of the list:
842 */
843static int add_lock_to_list(struct lock_class *this, struct list_head *head,
844 unsigned long ip, int distance,
845 struct stack_trace *trace)
846{
847 struct lock_list *entry;
848 /*
849 * Lock not present yet - get a new dependency struct and
850 * add it to the list:
851 */
852 entry = alloc_list_entry();
853 if (!entry)
854 return 0;
855
856 entry->class = this;
857 entry->distance = distance;
858 entry->trace = *trace;
859 /*
860 * Both allocation and removal are done under the graph lock; but
861 * iteration is under RCU-sched; see look_up_lock_class() and
862 * lockdep_free_key_range().
863 */
864 list_add_tail_rcu(&entry->entry, head);
865
866 return 1;
867}
868
869/*
870 * For good efficiency of modular, we use power of 2
871 */
872#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
873#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
874
875/*
876 * The circular_queue and helpers is used to implement the
877 * breadth-first search(BFS)algorithem, by which we can build
878 * the shortest path from the next lock to be acquired to the
879 * previous held lock if there is a circular between them.
880 */
881struct circular_queue {
882 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
883 unsigned int front, rear;
884};
885
886static struct circular_queue lock_cq;
887
888unsigned int max_bfs_queue_depth;
889
890static unsigned int lockdep_dependency_gen_id;
891
892static inline void __cq_init(struct circular_queue *cq)
893{
894 cq->front = cq->rear = 0;
895 lockdep_dependency_gen_id++;
896}
897
898static inline int __cq_empty(struct circular_queue *cq)
899{
900 return (cq->front == cq->rear);
901}
902
903static inline int __cq_full(struct circular_queue *cq)
904{
905 return ((cq->rear + 1) & CQ_MASK) == cq->front;
906}
907
908static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
909{
910 if (__cq_full(cq))
911 return -1;
912
913 cq->element[cq->rear] = elem;
914 cq->rear = (cq->rear + 1) & CQ_MASK;
915 return 0;
916}
917
918static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
919{
920 if (__cq_empty(cq))
921 return -1;
922
923 *elem = cq->element[cq->front];
924 cq->front = (cq->front + 1) & CQ_MASK;
925 return 0;
926}
927
928static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
929{
930 return (cq->rear - cq->front) & CQ_MASK;
931}
932
933static inline void mark_lock_accessed(struct lock_list *lock,
934 struct lock_list *parent)
935{
936 unsigned long nr;
937
938 nr = lock - list_entries;
939 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
940 lock->parent = parent;
941 lock->class->dep_gen_id = lockdep_dependency_gen_id;
942}
943
944static inline unsigned long lock_accessed(struct lock_list *lock)
945{
946 unsigned long nr;
947
948 nr = lock - list_entries;
949 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
950 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
951}
952
953static inline struct lock_list *get_lock_parent(struct lock_list *child)
954{
955 return child->parent;
956}
957
958static inline int get_lock_depth(struct lock_list *child)
959{
960 int depth = 0;
961 struct lock_list *parent;
962
963 while ((parent = get_lock_parent(child))) {
964 child = parent;
965 depth++;
966 }
967 return depth;
968}
969
970static int __bfs(struct lock_list *source_entry,
971 void *data,
972 int (*match)(struct lock_list *entry, void *data),
973 struct lock_list **target_entry,
974 int forward)
975{
976 struct lock_list *entry;
977 struct list_head *head;
978 struct circular_queue *cq = &lock_cq;
979 int ret = 1;
980
981 if (match(source_entry, data)) {
982 *target_entry = source_entry;
983 ret = 0;
984 goto exit;
985 }
986
987 if (forward)
988 head = &source_entry->class->locks_after;
989 else
990 head = &source_entry->class->locks_before;
991
992 if (list_empty(head))
993 goto exit;
994
995 __cq_init(cq);
996 __cq_enqueue(cq, (unsigned long)source_entry);
997
998 while (!__cq_empty(cq)) {
999 struct lock_list *lock;
1000
1001 __cq_dequeue(cq, (unsigned long *)&lock);
1002
1003 if (!lock->class) {
1004 ret = -2;
1005 goto exit;
1006 }
1007
1008 if (forward)
1009 head = &lock->class->locks_after;
1010 else
1011 head = &lock->class->locks_before;
1012
1013 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1014
1015 list_for_each_entry_rcu(entry, head, entry) {
1016 if (!lock_accessed(entry)) {
1017 unsigned int cq_depth;
1018 mark_lock_accessed(entry, lock);
1019 if (match(entry, data)) {
1020 *target_entry = entry;
1021 ret = 0;
1022 goto exit;
1023 }
1024
1025 if (__cq_enqueue(cq, (unsigned long)entry)) {
1026 ret = -1;
1027 goto exit;
1028 }
1029 cq_depth = __cq_get_elem_count(cq);
1030 if (max_bfs_queue_depth < cq_depth)
1031 max_bfs_queue_depth = cq_depth;
1032 }
1033 }
1034 }
1035exit:
1036 return ret;
1037}
1038
1039static inline int __bfs_forwards(struct lock_list *src_entry,
1040 void *data,
1041 int (*match)(struct lock_list *entry, void *data),
1042 struct lock_list **target_entry)
1043{
1044 return __bfs(src_entry, data, match, target_entry, 1);
1045
1046}
1047
1048static inline int __bfs_backwards(struct lock_list *src_entry,
1049 void *data,
1050 int (*match)(struct lock_list *entry, void *data),
1051 struct lock_list **target_entry)
1052{
1053 return __bfs(src_entry, data, match, target_entry, 0);
1054
1055}
1056
1057/*
1058 * Recursive, forwards-direction lock-dependency checking, used for
1059 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1060 * checking.
1061 */
1062
1063/*
1064 * Print a dependency chain entry (this is only done when a deadlock
1065 * has been detected):
1066 */
1067static noinline int
1068print_circular_bug_entry(struct lock_list *target, int depth)
1069{
1070 if (debug_locks_silent)
1071 return 0;
1072 printk("\n-> #%u", depth);
1073 print_lock_name(target->class);
1074 printk(KERN_CONT ":\n");
1075 print_stack_trace(&target->trace, 6);
1076
1077 return 0;
1078}
1079
1080static void
1081print_circular_lock_scenario(struct held_lock *src,
1082 struct held_lock *tgt,
1083 struct lock_list *prt)
1084{
1085 struct lock_class *source = hlock_class(src);
1086 struct lock_class *target = hlock_class(tgt);
1087 struct lock_class *parent = prt->class;
1088
1089 /*
1090 * A direct locking problem where unsafe_class lock is taken
1091 * directly by safe_class lock, then all we need to show
1092 * is the deadlock scenario, as it is obvious that the
1093 * unsafe lock is taken under the safe lock.
1094 *
1095 * But if there is a chain instead, where the safe lock takes
1096 * an intermediate lock (middle_class) where this lock is
1097 * not the same as the safe lock, then the lock chain is
1098 * used to describe the problem. Otherwise we would need
1099 * to show a different CPU case for each link in the chain
1100 * from the safe_class lock to the unsafe_class lock.
1101 */
1102 if (parent != source) {
1103 printk("Chain exists of:\n ");
1104 __print_lock_name(source);
1105 printk(KERN_CONT " --> ");
1106 __print_lock_name(parent);
1107 printk(KERN_CONT " --> ");
1108 __print_lock_name(target);
1109 printk(KERN_CONT "\n\n");
1110 }
1111
1112 printk(" Possible unsafe locking scenario:\n\n");
1113 printk(" CPU0 CPU1\n");
1114 printk(" ---- ----\n");
1115 printk(" lock(");
1116 __print_lock_name(target);
1117 printk(KERN_CONT ");\n");
1118 printk(" lock(");
1119 __print_lock_name(parent);
1120 printk(KERN_CONT ");\n");
1121 printk(" lock(");
1122 __print_lock_name(target);
1123 printk(KERN_CONT ");\n");
1124 printk(" lock(");
1125 __print_lock_name(source);
1126 printk(KERN_CONT ");\n");
1127 printk("\n *** DEADLOCK ***\n\n");
1128}
1129
1130/*
1131 * When a circular dependency is detected, print the
1132 * header first:
1133 */
1134static noinline int
1135print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1136 struct held_lock *check_src,
1137 struct held_lock *check_tgt)
1138{
1139 struct task_struct *curr = current;
1140
1141 if (debug_locks_silent)
1142 return 0;
1143
1144 printk("\n");
1145 printk("======================================================\n");
1146 printk("[ INFO: possible circular locking dependency detected ]\n");
1147 print_kernel_ident();
1148 printk("-------------------------------------------------------\n");
1149 printk("%s/%d is trying to acquire lock:\n",
1150 curr->comm, task_pid_nr(curr));
1151 print_lock(check_src);
1152 printk("\nbut task is already holding lock:\n");
1153 print_lock(check_tgt);
1154 printk("\nwhich lock already depends on the new lock.\n\n");
1155 printk("\nthe existing dependency chain (in reverse order) is:\n");
1156
1157 print_circular_bug_entry(entry, depth);
1158
1159 return 0;
1160}
1161
1162static inline int class_equal(struct lock_list *entry, void *data)
1163{
1164 return entry->class == data;
1165}
1166
1167static noinline int print_circular_bug(struct lock_list *this,
1168 struct lock_list *target,
1169 struct held_lock *check_src,
1170 struct held_lock *check_tgt)
1171{
1172 struct task_struct *curr = current;
1173 struct lock_list *parent;
1174 struct lock_list *first_parent;
1175 int depth;
1176
1177 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1178 return 0;
1179
1180 if (!save_trace(&this->trace))
1181 return 0;
1182
1183 depth = get_lock_depth(target);
1184
1185 print_circular_bug_header(target, depth, check_src, check_tgt);
1186
1187 parent = get_lock_parent(target);
1188 first_parent = parent;
1189
1190 while (parent) {
1191 print_circular_bug_entry(parent, --depth);
1192 parent = get_lock_parent(parent);
1193 }
1194
1195 printk("\nother info that might help us debug this:\n\n");
1196 print_circular_lock_scenario(check_src, check_tgt,
1197 first_parent);
1198
1199 lockdep_print_held_locks(curr);
1200
1201 printk("\nstack backtrace:\n");
1202 dump_stack();
1203
1204 return 0;
1205}
1206
1207static noinline int print_bfs_bug(int ret)
1208{
1209 if (!debug_locks_off_graph_unlock())
1210 return 0;
1211
1212 /*
1213 * Breadth-first-search failed, graph got corrupted?
1214 */
1215 WARN(1, "lockdep bfs error:%d\n", ret);
1216
1217 return 0;
1218}
1219
1220static int noop_count(struct lock_list *entry, void *data)
1221{
1222 (*(unsigned long *)data)++;
1223 return 0;
1224}
1225
1226static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1227{
1228 unsigned long count = 0;
1229 struct lock_list *uninitialized_var(target_entry);
1230
1231 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1232
1233 return count;
1234}
1235unsigned long lockdep_count_forward_deps(struct lock_class *class)
1236{
1237 unsigned long ret, flags;
1238 struct lock_list this;
1239
1240 this.parent = NULL;
1241 this.class = class;
1242
1243 local_irq_save(flags);
1244 arch_spin_lock(&lockdep_lock);
1245 ret = __lockdep_count_forward_deps(&this);
1246 arch_spin_unlock(&lockdep_lock);
1247 local_irq_restore(flags);
1248
1249 return ret;
1250}
1251
1252static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1253{
1254 unsigned long count = 0;
1255 struct lock_list *uninitialized_var(target_entry);
1256
1257 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1258
1259 return count;
1260}
1261
1262unsigned long lockdep_count_backward_deps(struct lock_class *class)
1263{
1264 unsigned long ret, flags;
1265 struct lock_list this;
1266
1267 this.parent = NULL;
1268 this.class = class;
1269
1270 local_irq_save(flags);
1271 arch_spin_lock(&lockdep_lock);
1272 ret = __lockdep_count_backward_deps(&this);
1273 arch_spin_unlock(&lockdep_lock);
1274 local_irq_restore(flags);
1275
1276 return ret;
1277}
1278
1279/*
1280 * Prove that the dependency graph starting at <entry> can not
1281 * lead to <target>. Print an error and return 0 if it does.
1282 */
1283static noinline int
1284check_noncircular(struct lock_list *root, struct lock_class *target,
1285 struct lock_list **target_entry)
1286{
1287 int result;
1288
1289 debug_atomic_inc(nr_cyclic_checks);
1290
1291 result = __bfs_forwards(root, target, class_equal, target_entry);
1292
1293 return result;
1294}
1295
1296#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1297/*
1298 * Forwards and backwards subgraph searching, for the purposes of
1299 * proving that two subgraphs can be connected by a new dependency
1300 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1301 */
1302
1303static inline int usage_match(struct lock_list *entry, void *bit)
1304{
1305 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1306}
1307
1308
1309
1310/*
1311 * Find a node in the forwards-direction dependency sub-graph starting
1312 * at @root->class that matches @bit.
1313 *
1314 * Return 0 if such a node exists in the subgraph, and put that node
1315 * into *@target_entry.
1316 *
1317 * Return 1 otherwise and keep *@target_entry unchanged.
1318 * Return <0 on error.
1319 */
1320static int
1321find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1322 struct lock_list **target_entry)
1323{
1324 int result;
1325
1326 debug_atomic_inc(nr_find_usage_forwards_checks);
1327
1328 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1329
1330 return result;
1331}
1332
1333/*
1334 * Find a node in the backwards-direction dependency sub-graph starting
1335 * at @root->class that matches @bit.
1336 *
1337 * Return 0 if such a node exists in the subgraph, and put that node
1338 * into *@target_entry.
1339 *
1340 * Return 1 otherwise and keep *@target_entry unchanged.
1341 * Return <0 on error.
1342 */
1343static int
1344find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1345 struct lock_list **target_entry)
1346{
1347 int result;
1348
1349 debug_atomic_inc(nr_find_usage_backwards_checks);
1350
1351 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1352
1353 return result;
1354}
1355
1356static void print_lock_class_header(struct lock_class *class, int depth)
1357{
1358 int bit;
1359
1360 printk("%*s->", depth, "");
1361 print_lock_name(class);
1362 printk(KERN_CONT " ops: %lu", class->ops);
1363 printk(KERN_CONT " {\n");
1364
1365 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1366 if (class->usage_mask & (1 << bit)) {
1367 int len = depth;
1368
1369 len += printk("%*s %s", depth, "", usage_str[bit]);
1370 len += printk(KERN_CONT " at:\n");
1371 print_stack_trace(class->usage_traces + bit, len);
1372 }
1373 }
1374 printk("%*s }\n", depth, "");
1375
1376 printk("%*s ... key at: [<%p>] %pS\n",
1377 depth, "", class->key, class->key);
1378}
1379
1380/*
1381 * printk the shortest lock dependencies from @start to @end in reverse order:
1382 */
1383static void __used
1384print_shortest_lock_dependencies(struct lock_list *leaf,
1385 struct lock_list *root)
1386{
1387 struct lock_list *entry = leaf;
1388 int depth;
1389
1390 /*compute depth from generated tree by BFS*/
1391 depth = get_lock_depth(leaf);
1392
1393 do {
1394 print_lock_class_header(entry->class, depth);
1395 printk("%*s ... acquired at:\n", depth, "");
1396 print_stack_trace(&entry->trace, 2);
1397 printk("\n");
1398
1399 if (depth == 0 && (entry != root)) {
1400 printk("lockdep:%s bad path found in chain graph\n", __func__);
1401 break;
1402 }
1403
1404 entry = get_lock_parent(entry);
1405 depth--;
1406 } while (entry && (depth >= 0));
1407
1408 return;
1409}
1410
1411static void
1412print_irq_lock_scenario(struct lock_list *safe_entry,
1413 struct lock_list *unsafe_entry,
1414 struct lock_class *prev_class,
1415 struct lock_class *next_class)
1416{
1417 struct lock_class *safe_class = safe_entry->class;
1418 struct lock_class *unsafe_class = unsafe_entry->class;
1419 struct lock_class *middle_class = prev_class;
1420
1421 if (middle_class == safe_class)
1422 middle_class = next_class;
1423
1424 /*
1425 * A direct locking problem where unsafe_class lock is taken
1426 * directly by safe_class lock, then all we need to show
1427 * is the deadlock scenario, as it is obvious that the
1428 * unsafe lock is taken under the safe lock.
1429 *
1430 * But if there is a chain instead, where the safe lock takes
1431 * an intermediate lock (middle_class) where this lock is
1432 * not the same as the safe lock, then the lock chain is
1433 * used to describe the problem. Otherwise we would need
1434 * to show a different CPU case for each link in the chain
1435 * from the safe_class lock to the unsafe_class lock.
1436 */
1437 if (middle_class != unsafe_class) {
1438 printk("Chain exists of:\n ");
1439 __print_lock_name(safe_class);
1440 printk(KERN_CONT " --> ");
1441 __print_lock_name(middle_class);
1442 printk(KERN_CONT " --> ");
1443 __print_lock_name(unsafe_class);
1444 printk(KERN_CONT "\n\n");
1445 }
1446
1447 printk(" Possible interrupt unsafe locking scenario:\n\n");
1448 printk(" CPU0 CPU1\n");
1449 printk(" ---- ----\n");
1450 printk(" lock(");
1451 __print_lock_name(unsafe_class);
1452 printk(KERN_CONT ");\n");
1453 printk(" local_irq_disable();\n");
1454 printk(" lock(");
1455 __print_lock_name(safe_class);
1456 printk(KERN_CONT ");\n");
1457 printk(" lock(");
1458 __print_lock_name(middle_class);
1459 printk(KERN_CONT ");\n");
1460 printk(" <Interrupt>\n");
1461 printk(" lock(");
1462 __print_lock_name(safe_class);
1463 printk(KERN_CONT ");\n");
1464 printk("\n *** DEADLOCK ***\n\n");
1465}
1466
1467static int
1468print_bad_irq_dependency(struct task_struct *curr,
1469 struct lock_list *prev_root,
1470 struct lock_list *next_root,
1471 struct lock_list *backwards_entry,
1472 struct lock_list *forwards_entry,
1473 struct held_lock *prev,
1474 struct held_lock *next,
1475 enum lock_usage_bit bit1,
1476 enum lock_usage_bit bit2,
1477 const char *irqclass)
1478{
1479 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1480 return 0;
1481
1482 printk("\n");
1483 printk("======================================================\n");
1484 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1485 irqclass, irqclass);
1486 print_kernel_ident();
1487 printk("------------------------------------------------------\n");
1488 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1489 curr->comm, task_pid_nr(curr),
1490 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1491 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1492 curr->hardirqs_enabled,
1493 curr->softirqs_enabled);
1494 print_lock(next);
1495
1496 printk("\nand this task is already holding:\n");
1497 print_lock(prev);
1498 printk("which would create a new lock dependency:\n");
1499 print_lock_name(hlock_class(prev));
1500 printk(KERN_CONT " ->");
1501 print_lock_name(hlock_class(next));
1502 printk(KERN_CONT "\n");
1503
1504 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1505 irqclass);
1506 print_lock_name(backwards_entry->class);
1507 printk("\n... which became %s-irq-safe at:\n", irqclass);
1508
1509 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1510
1511 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1512 print_lock_name(forwards_entry->class);
1513 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1514 printk("...");
1515
1516 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1517
1518 printk("\nother info that might help us debug this:\n\n");
1519 print_irq_lock_scenario(backwards_entry, forwards_entry,
1520 hlock_class(prev), hlock_class(next));
1521
1522 lockdep_print_held_locks(curr);
1523
1524 printk("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
1525 if (!save_trace(&prev_root->trace))
1526 return 0;
1527 print_shortest_lock_dependencies(backwards_entry, prev_root);
1528
1529 printk("\nthe dependencies between the lock to be acquired");
1530 printk(" and %s-irq-unsafe lock:\n", irqclass);
1531 if (!save_trace(&next_root->trace))
1532 return 0;
1533 print_shortest_lock_dependencies(forwards_entry, next_root);
1534
1535 printk("\nstack backtrace:\n");
1536 dump_stack();
1537
1538 return 0;
1539}
1540
1541static int
1542check_usage(struct task_struct *curr, struct held_lock *prev,
1543 struct held_lock *next, enum lock_usage_bit bit_backwards,
1544 enum lock_usage_bit bit_forwards, const char *irqclass)
1545{
1546 int ret;
1547 struct lock_list this, that;
1548 struct lock_list *uninitialized_var(target_entry);
1549 struct lock_list *uninitialized_var(target_entry1);
1550
1551 this.parent = NULL;
1552
1553 this.class = hlock_class(prev);
1554 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1555 if (ret < 0)
1556 return print_bfs_bug(ret);
1557 if (ret == 1)
1558 return ret;
1559
1560 that.parent = NULL;
1561 that.class = hlock_class(next);
1562 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1563 if (ret < 0)
1564 return print_bfs_bug(ret);
1565 if (ret == 1)
1566 return ret;
1567
1568 return print_bad_irq_dependency(curr, &this, &that,
1569 target_entry, target_entry1,
1570 prev, next,
1571 bit_backwards, bit_forwards, irqclass);
1572}
1573
1574static const char *state_names[] = {
1575#define LOCKDEP_STATE(__STATE) \
1576 __stringify(__STATE),
1577#include "lockdep_states.h"
1578#undef LOCKDEP_STATE
1579};
1580
1581static const char *state_rnames[] = {
1582#define LOCKDEP_STATE(__STATE) \
1583 __stringify(__STATE)"-READ",
1584#include "lockdep_states.h"
1585#undef LOCKDEP_STATE
1586};
1587
1588static inline const char *state_name(enum lock_usage_bit bit)
1589{
1590 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1591}
1592
1593static int exclusive_bit(int new_bit)
1594{
1595 /*
1596 * USED_IN
1597 * USED_IN_READ
1598 * ENABLED
1599 * ENABLED_READ
1600 *
1601 * bit 0 - write/read
1602 * bit 1 - used_in/enabled
1603 * bit 2+ state
1604 */
1605
1606 int state = new_bit & ~3;
1607 int dir = new_bit & 2;
1608
1609 /*
1610 * keep state, bit flip the direction and strip read.
1611 */
1612 return state | (dir ^ 2);
1613}
1614
1615static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1616 struct held_lock *next, enum lock_usage_bit bit)
1617{
1618 /*
1619 * Prove that the new dependency does not connect a hardirq-safe
1620 * lock with a hardirq-unsafe lock - to achieve this we search
1621 * the backwards-subgraph starting at <prev>, and the
1622 * forwards-subgraph starting at <next>:
1623 */
1624 if (!check_usage(curr, prev, next, bit,
1625 exclusive_bit(bit), state_name(bit)))
1626 return 0;
1627
1628 bit++; /* _READ */
1629
1630 /*
1631 * Prove that the new dependency does not connect a hardirq-safe-read
1632 * lock with a hardirq-unsafe lock - to achieve this we search
1633 * the backwards-subgraph starting at <prev>, and the
1634 * forwards-subgraph starting at <next>:
1635 */
1636 if (!check_usage(curr, prev, next, bit,
1637 exclusive_bit(bit), state_name(bit)))
1638 return 0;
1639
1640 return 1;
1641}
1642
1643static int
1644check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1645 struct held_lock *next)
1646{
1647#define LOCKDEP_STATE(__STATE) \
1648 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1649 return 0;
1650#include "lockdep_states.h"
1651#undef LOCKDEP_STATE
1652
1653 return 1;
1654}
1655
1656static void inc_chains(void)
1657{
1658 if (current->hardirq_context)
1659 nr_hardirq_chains++;
1660 else {
1661 if (current->softirq_context)
1662 nr_softirq_chains++;
1663 else
1664 nr_process_chains++;
1665 }
1666}
1667
1668#else
1669
1670static inline int
1671check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1672 struct held_lock *next)
1673{
1674 return 1;
1675}
1676
1677static inline void inc_chains(void)
1678{
1679 nr_process_chains++;
1680}
1681
1682#endif
1683
1684static void
1685print_deadlock_scenario(struct held_lock *nxt,
1686 struct held_lock *prv)
1687{
1688 struct lock_class *next = hlock_class(nxt);
1689 struct lock_class *prev = hlock_class(prv);
1690
1691 printk(" Possible unsafe locking scenario:\n\n");
1692 printk(" CPU0\n");
1693 printk(" ----\n");
1694 printk(" lock(");
1695 __print_lock_name(prev);
1696 printk(KERN_CONT ");\n");
1697 printk(" lock(");
1698 __print_lock_name(next);
1699 printk(KERN_CONT ");\n");
1700 printk("\n *** DEADLOCK ***\n\n");
1701 printk(" May be due to missing lock nesting notation\n\n");
1702}
1703
1704static int
1705print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1706 struct held_lock *next)
1707{
1708 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1709 return 0;
1710
1711 printk("\n");
1712 printk("=============================================\n");
1713 printk("[ INFO: possible recursive locking detected ]\n");
1714 print_kernel_ident();
1715 printk("---------------------------------------------\n");
1716 printk("%s/%d is trying to acquire lock:\n",
1717 curr->comm, task_pid_nr(curr));
1718 print_lock(next);
1719 printk("\nbut task is already holding lock:\n");
1720 print_lock(prev);
1721
1722 printk("\nother info that might help us debug this:\n");
1723 print_deadlock_scenario(next, prev);
1724 lockdep_print_held_locks(curr);
1725
1726 printk("\nstack backtrace:\n");
1727 dump_stack();
1728
1729 return 0;
1730}
1731
1732/*
1733 * Check whether we are holding such a class already.
1734 *
1735 * (Note that this has to be done separately, because the graph cannot
1736 * detect such classes of deadlocks.)
1737 *
1738 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1739 */
1740static int
1741check_deadlock(struct task_struct *curr, struct held_lock *next,
1742 struct lockdep_map *next_instance, int read)
1743{
1744 struct held_lock *prev;
1745 struct held_lock *nest = NULL;
1746 int i;
1747
1748 for (i = 0; i < curr->lockdep_depth; i++) {
1749 prev = curr->held_locks + i;
1750
1751 if (prev->instance == next->nest_lock)
1752 nest = prev;
1753
1754 if (hlock_class(prev) != hlock_class(next))
1755 continue;
1756
1757 /*
1758 * Allow read-after-read recursion of the same
1759 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1760 */
1761 if ((read == 2) && prev->read)
1762 return 2;
1763
1764 /*
1765 * We're holding the nest_lock, which serializes this lock's
1766 * nesting behaviour.
1767 */
1768 if (nest)
1769 return 2;
1770
1771 return print_deadlock_bug(curr, prev, next);
1772 }
1773 return 1;
1774}
1775
1776/*
1777 * There was a chain-cache miss, and we are about to add a new dependency
1778 * to a previous lock. We recursively validate the following rules:
1779 *
1780 * - would the adding of the <prev> -> <next> dependency create a
1781 * circular dependency in the graph? [== circular deadlock]
1782 *
1783 * - does the new prev->next dependency connect any hardirq-safe lock
1784 * (in the full backwards-subgraph starting at <prev>) with any
1785 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1786 * <next>)? [== illegal lock inversion with hardirq contexts]
1787 *
1788 * - does the new prev->next dependency connect any softirq-safe lock
1789 * (in the full backwards-subgraph starting at <prev>) with any
1790 * softirq-unsafe lock (in the full forwards-subgraph starting at
1791 * <next>)? [== illegal lock inversion with softirq contexts]
1792 *
1793 * any of these scenarios could lead to a deadlock.
1794 *
1795 * Then if all the validations pass, we add the forwards and backwards
1796 * dependency.
1797 */
1798static int
1799check_prev_add(struct task_struct *curr, struct held_lock *prev,
1800 struct held_lock *next, int distance, int *stack_saved)
1801{
1802 struct lock_list *entry;
1803 int ret;
1804 struct lock_list this;
1805 struct lock_list *uninitialized_var(target_entry);
1806 /*
1807 * Static variable, serialized by the graph_lock().
1808 *
1809 * We use this static variable to save the stack trace in case
1810 * we call into this function multiple times due to encountering
1811 * trylocks in the held lock stack.
1812 */
1813 static struct stack_trace trace;
1814
1815 /*
1816 * Prove that the new <prev> -> <next> dependency would not
1817 * create a circular dependency in the graph. (We do this by
1818 * forward-recursing into the graph starting at <next>, and
1819 * checking whether we can reach <prev>.)
1820 *
1821 * We are using global variables to control the recursion, to
1822 * keep the stackframe size of the recursive functions low:
1823 */
1824 this.class = hlock_class(next);
1825 this.parent = NULL;
1826 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1827 if (unlikely(!ret))
1828 return print_circular_bug(&this, target_entry, next, prev);
1829 else if (unlikely(ret < 0))
1830 return print_bfs_bug(ret);
1831
1832 if (!check_prev_add_irq(curr, prev, next))
1833 return 0;
1834
1835 /*
1836 * For recursive read-locks we do all the dependency checks,
1837 * but we dont store read-triggered dependencies (only
1838 * write-triggered dependencies). This ensures that only the
1839 * write-side dependencies matter, and that if for example a
1840 * write-lock never takes any other locks, then the reads are
1841 * equivalent to a NOP.
1842 */
1843 if (next->read == 2 || prev->read == 2)
1844 return 1;
1845 /*
1846 * Is the <prev> -> <next> dependency already present?
1847 *
1848 * (this may occur even though this is a new chain: consider
1849 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1850 * chains - the second one will be new, but L1 already has
1851 * L2 added to its dependency list, due to the first chain.)
1852 */
1853 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1854 if (entry->class == hlock_class(next)) {
1855 if (distance == 1)
1856 entry->distance = 1;
1857 return 2;
1858 }
1859 }
1860
1861 if (!*stack_saved) {
1862 if (!save_trace(&trace))
1863 return 0;
1864 *stack_saved = 1;
1865 }
1866
1867 /*
1868 * Ok, all validations passed, add the new lock
1869 * to the previous lock's dependency list:
1870 */
1871 ret = add_lock_to_list(hlock_class(next),
1872 &hlock_class(prev)->locks_after,
1873 next->acquire_ip, distance, &trace);
1874
1875 if (!ret)
1876 return 0;
1877
1878 ret = add_lock_to_list(hlock_class(prev),
1879 &hlock_class(next)->locks_before,
1880 next->acquire_ip, distance, &trace);
1881 if (!ret)
1882 return 0;
1883
1884 /*
1885 * Debugging printouts:
1886 */
1887 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1888 /* We drop graph lock, so another thread can overwrite trace. */
1889 *stack_saved = 0;
1890 graph_unlock();
1891 printk("\n new dependency: ");
1892 print_lock_name(hlock_class(prev));
1893 printk(KERN_CONT " => ");
1894 print_lock_name(hlock_class(next));
1895 printk(KERN_CONT "\n");
1896 dump_stack();
1897 return graph_lock();
1898 }
1899 return 1;
1900}
1901
1902/*
1903 * Add the dependency to all directly-previous locks that are 'relevant'.
1904 * The ones that are relevant are (in increasing distance from curr):
1905 * all consecutive trylock entries and the final non-trylock entry - or
1906 * the end of this context's lock-chain - whichever comes first.
1907 */
1908static int
1909check_prevs_add(struct task_struct *curr, struct held_lock *next)
1910{
1911 int depth = curr->lockdep_depth;
1912 int stack_saved = 0;
1913 struct held_lock *hlock;
1914
1915 /*
1916 * Debugging checks.
1917 *
1918 * Depth must not be zero for a non-head lock:
1919 */
1920 if (!depth)
1921 goto out_bug;
1922 /*
1923 * At least two relevant locks must exist for this
1924 * to be a head:
1925 */
1926 if (curr->held_locks[depth].irq_context !=
1927 curr->held_locks[depth-1].irq_context)
1928 goto out_bug;
1929
1930 for (;;) {
1931 int distance = curr->lockdep_depth - depth + 1;
1932 hlock = curr->held_locks + depth - 1;
1933 /*
1934 * Only non-recursive-read entries get new dependencies
1935 * added:
1936 */
1937 if (hlock->read != 2 && hlock->check) {
1938 if (!check_prev_add(curr, hlock, next,
1939 distance, &stack_saved))
1940 return 0;
1941 /*
1942 * Stop after the first non-trylock entry,
1943 * as non-trylock entries have added their
1944 * own direct dependencies already, so this
1945 * lock is connected to them indirectly:
1946 */
1947 if (!hlock->trylock)
1948 break;
1949 }
1950 depth--;
1951 /*
1952 * End of lock-stack?
1953 */
1954 if (!depth)
1955 break;
1956 /*
1957 * Stop the search if we cross into another context:
1958 */
1959 if (curr->held_locks[depth].irq_context !=
1960 curr->held_locks[depth-1].irq_context)
1961 break;
1962 }
1963 return 1;
1964out_bug:
1965 if (!debug_locks_off_graph_unlock())
1966 return 0;
1967
1968 /*
1969 * Clearly we all shouldn't be here, but since we made it we
1970 * can reliable say we messed up our state. See the above two
1971 * gotos for reasons why we could possibly end up here.
1972 */
1973 WARN_ON(1);
1974
1975 return 0;
1976}
1977
1978unsigned long nr_lock_chains;
1979struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1980int nr_chain_hlocks;
1981static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1982
1983struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1984{
1985 return lock_classes + chain_hlocks[chain->base + i];
1986}
1987
1988/*
1989 * Returns the index of the first held_lock of the current chain
1990 */
1991static inline int get_first_held_lock(struct task_struct *curr,
1992 struct held_lock *hlock)
1993{
1994 int i;
1995 struct held_lock *hlock_curr;
1996
1997 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1998 hlock_curr = curr->held_locks + i;
1999 if (hlock_curr->irq_context != hlock->irq_context)
2000 break;
2001
2002 }
2003
2004 return ++i;
2005}
2006
2007#ifdef CONFIG_DEBUG_LOCKDEP
2008/*
2009 * Returns the next chain_key iteration
2010 */
2011static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2012{
2013 u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2014
2015 printk(" class_idx:%d -> chain_key:%016Lx",
2016 class_idx,
2017 (unsigned long long)new_chain_key);
2018 return new_chain_key;
2019}
2020
2021static void
2022print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2023{
2024 struct held_lock *hlock;
2025 u64 chain_key = 0;
2026 int depth = curr->lockdep_depth;
2027 int i;
2028
2029 printk("depth: %u\n", depth + 1);
2030 for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
2031 hlock = curr->held_locks + i;
2032 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2033
2034 print_lock(hlock);
2035 }
2036
2037 print_chain_key_iteration(hlock_next->class_idx, chain_key);
2038 print_lock(hlock_next);
2039}
2040
2041static void print_chain_keys_chain(struct lock_chain *chain)
2042{
2043 int i;
2044 u64 chain_key = 0;
2045 int class_id;
2046
2047 printk("depth: %u\n", chain->depth);
2048 for (i = 0; i < chain->depth; i++) {
2049 class_id = chain_hlocks[chain->base + i];
2050 chain_key = print_chain_key_iteration(class_id + 1, chain_key);
2051
2052 print_lock_name(lock_classes + class_id);
2053 printk("\n");
2054 }
2055}
2056
2057static void print_collision(struct task_struct *curr,
2058 struct held_lock *hlock_next,
2059 struct lock_chain *chain)
2060{
2061 printk("\n");
2062 printk("======================\n");
2063 printk("[chain_key collision ]\n");
2064 print_kernel_ident();
2065 printk("----------------------\n");
2066 printk("%s/%d: ", current->comm, task_pid_nr(current));
2067 printk("Hash chain already cached but the contents don't match!\n");
2068
2069 printk("Held locks:");
2070 print_chain_keys_held_locks(curr, hlock_next);
2071
2072 printk("Locks in cached chain:");
2073 print_chain_keys_chain(chain);
2074
2075 printk("\nstack backtrace:\n");
2076 dump_stack();
2077}
2078#endif
2079
2080/*
2081 * Checks whether the chain and the current held locks are consistent
2082 * in depth and also in content. If they are not it most likely means
2083 * that there was a collision during the calculation of the chain_key.
2084 * Returns: 0 not passed, 1 passed
2085 */
2086static int check_no_collision(struct task_struct *curr,
2087 struct held_lock *hlock,
2088 struct lock_chain *chain)
2089{
2090#ifdef CONFIG_DEBUG_LOCKDEP
2091 int i, j, id;
2092
2093 i = get_first_held_lock(curr, hlock);
2094
2095 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2096 print_collision(curr, hlock, chain);
2097 return 0;
2098 }
2099
2100 for (j = 0; j < chain->depth - 1; j++, i++) {
2101 id = curr->held_locks[i].class_idx - 1;
2102
2103 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2104 print_collision(curr, hlock, chain);
2105 return 0;
2106 }
2107 }
2108#endif
2109 return 1;
2110}
2111
2112/*
2113 * Look up a dependency chain. If the key is not present yet then
2114 * add it and return 1 - in this case the new dependency chain is
2115 * validated. If the key is already hashed, return 0.
2116 * (On return with 1 graph_lock is held.)
2117 */
2118static inline int lookup_chain_cache(struct task_struct *curr,
2119 struct held_lock *hlock,
2120 u64 chain_key)
2121{
2122 struct lock_class *class = hlock_class(hlock);
2123 struct hlist_head *hash_head = chainhashentry(chain_key);
2124 struct lock_chain *chain;
2125 int i, j;
2126
2127 /*
2128 * We might need to take the graph lock, ensure we've got IRQs
2129 * disabled to make this an IRQ-safe lock.. for recursion reasons
2130 * lockdep won't complain about its own locking errors.
2131 */
2132 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2133 return 0;
2134 /*
2135 * We can walk it lock-free, because entries only get added
2136 * to the hash:
2137 */
2138 hlist_for_each_entry_rcu(chain, hash_head, entry) {
2139 if (chain->chain_key == chain_key) {
2140cache_hit:
2141 debug_atomic_inc(chain_lookup_hits);
2142 if (!check_no_collision(curr, hlock, chain))
2143 return 0;
2144
2145 if (very_verbose(class))
2146 printk("\nhash chain already cached, key: "
2147 "%016Lx tail class: [%p] %s\n",
2148 (unsigned long long)chain_key,
2149 class->key, class->name);
2150 return 0;
2151 }
2152 }
2153 if (very_verbose(class))
2154 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2155 (unsigned long long)chain_key, class->key, class->name);
2156 /*
2157 * Allocate a new chain entry from the static array, and add
2158 * it to the hash:
2159 */
2160 if (!graph_lock())
2161 return 0;
2162 /*
2163 * We have to walk the chain again locked - to avoid duplicates:
2164 */
2165 hlist_for_each_entry(chain, hash_head, entry) {
2166 if (chain->chain_key == chain_key) {
2167 graph_unlock();
2168 goto cache_hit;
2169 }
2170 }
2171 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2172 if (!debug_locks_off_graph_unlock())
2173 return 0;
2174
2175 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2176 dump_stack();
2177 return 0;
2178 }
2179 chain = lock_chains + nr_lock_chains++;
2180 chain->chain_key = chain_key;
2181 chain->irq_context = hlock->irq_context;
2182 i = get_first_held_lock(curr, hlock);
2183 chain->depth = curr->lockdep_depth + 1 - i;
2184
2185 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2186 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
2187 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2188
2189 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2190 chain->base = nr_chain_hlocks;
2191 for (j = 0; j < chain->depth - 1; j++, i++) {
2192 int lock_id = curr->held_locks[i].class_idx - 1;
2193 chain_hlocks[chain->base + j] = lock_id;
2194 }
2195 chain_hlocks[chain->base + j] = class - lock_classes;
2196 }
2197
2198 if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
2199 nr_chain_hlocks += chain->depth;
2200
2201#ifdef CONFIG_DEBUG_LOCKDEP
2202 /*
2203 * Important for check_no_collision().
2204 */
2205 if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
2206 if (debug_locks_off_graph_unlock())
2207 return 0;
2208
2209 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2210 dump_stack();
2211 return 0;
2212 }
2213#endif
2214
2215 hlist_add_head_rcu(&chain->entry, hash_head);
2216 debug_atomic_inc(chain_lookup_misses);
2217 inc_chains();
2218
2219 return 1;
2220}
2221
2222static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2223 struct held_lock *hlock, int chain_head, u64 chain_key)
2224{
2225 /*
2226 * Trylock needs to maintain the stack of held locks, but it
2227 * does not add new dependencies, because trylock can be done
2228 * in any order.
2229 *
2230 * We look up the chain_key and do the O(N^2) check and update of
2231 * the dependencies only if this is a new dependency chain.
2232 * (If lookup_chain_cache() returns with 1 it acquires
2233 * graph_lock for us)
2234 */
2235 if (!hlock->trylock && hlock->check &&
2236 lookup_chain_cache(curr, hlock, chain_key)) {
2237 /*
2238 * Check whether last held lock:
2239 *
2240 * - is irq-safe, if this lock is irq-unsafe
2241 * - is softirq-safe, if this lock is hardirq-unsafe
2242 *
2243 * And check whether the new lock's dependency graph
2244 * could lead back to the previous lock.
2245 *
2246 * any of these scenarios could lead to a deadlock. If
2247 * All validations
2248 */
2249 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2250
2251 if (!ret)
2252 return 0;
2253 /*
2254 * Mark recursive read, as we jump over it when
2255 * building dependencies (just like we jump over
2256 * trylock entries):
2257 */
2258 if (ret == 2)
2259 hlock->read = 2;
2260 /*
2261 * Add dependency only if this lock is not the head
2262 * of the chain, and if it's not a secondary read-lock:
2263 */
2264 if (!chain_head && ret != 2)
2265 if (!check_prevs_add(curr, hlock))
2266 return 0;
2267 graph_unlock();
2268 } else
2269 /* after lookup_chain_cache(): */
2270 if (unlikely(!debug_locks))
2271 return 0;
2272
2273 return 1;
2274}
2275#else
2276static inline int validate_chain(struct task_struct *curr,
2277 struct lockdep_map *lock, struct held_lock *hlock,
2278 int chain_head, u64 chain_key)
2279{
2280 return 1;
2281}
2282#endif
2283
2284/*
2285 * We are building curr_chain_key incrementally, so double-check
2286 * it from scratch, to make sure that it's done correctly:
2287 */
2288static void check_chain_key(struct task_struct *curr)
2289{
2290#ifdef CONFIG_DEBUG_LOCKDEP
2291 struct held_lock *hlock, *prev_hlock = NULL;
2292 unsigned int i;
2293 u64 chain_key = 0;
2294
2295 for (i = 0; i < curr->lockdep_depth; i++) {
2296 hlock = curr->held_locks + i;
2297 if (chain_key != hlock->prev_chain_key) {
2298 debug_locks_off();
2299 /*
2300 * We got mighty confused, our chain keys don't match
2301 * with what we expect, someone trample on our task state?
2302 */
2303 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2304 curr->lockdep_depth, i,
2305 (unsigned long long)chain_key,
2306 (unsigned long long)hlock->prev_chain_key);
2307 return;
2308 }
2309 /*
2310 * Whoops ran out of static storage again?
2311 */
2312 if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
2313 return;
2314
2315 if (prev_hlock && (prev_hlock->irq_context !=
2316 hlock->irq_context))
2317 chain_key = 0;
2318 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
2319 prev_hlock = hlock;
2320 }
2321 if (chain_key != curr->curr_chain_key) {
2322 debug_locks_off();
2323 /*
2324 * More smoking hash instead of calculating it, damn see these
2325 * numbers float.. I bet that a pink elephant stepped on my memory.
2326 */
2327 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2328 curr->lockdep_depth, i,
2329 (unsigned long long)chain_key,
2330 (unsigned long long)curr->curr_chain_key);
2331 }
2332#endif
2333}
2334
2335static void
2336print_usage_bug_scenario(struct held_lock *lock)
2337{
2338 struct lock_class *class = hlock_class(lock);
2339
2340 printk(" Possible unsafe locking scenario:\n\n");
2341 printk(" CPU0\n");
2342 printk(" ----\n");
2343 printk(" lock(");
2344 __print_lock_name(class);
2345 printk(KERN_CONT ");\n");
2346 printk(" <Interrupt>\n");
2347 printk(" lock(");
2348 __print_lock_name(class);
2349 printk(KERN_CONT ");\n");
2350 printk("\n *** DEADLOCK ***\n\n");
2351}
2352
2353static int
2354print_usage_bug(struct task_struct *curr, struct held_lock *this,
2355 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2356{
2357 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2358 return 0;
2359
2360 printk("\n");
2361 printk("=================================\n");
2362 printk("[ INFO: inconsistent lock state ]\n");
2363 print_kernel_ident();
2364 printk("---------------------------------\n");
2365
2366 printk("inconsistent {%s} -> {%s} usage.\n",
2367 usage_str[prev_bit], usage_str[new_bit]);
2368
2369 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2370 curr->comm, task_pid_nr(curr),
2371 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2372 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2373 trace_hardirqs_enabled(curr),
2374 trace_softirqs_enabled(curr));
2375 print_lock(this);
2376
2377 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2378 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2379
2380 print_irqtrace_events(curr);
2381 printk("\nother info that might help us debug this:\n");
2382 print_usage_bug_scenario(this);
2383
2384 lockdep_print_held_locks(curr);
2385
2386 printk("\nstack backtrace:\n");
2387 dump_stack();
2388
2389 return 0;
2390}
2391
2392/*
2393 * Print out an error if an invalid bit is set:
2394 */
2395static inline int
2396valid_state(struct task_struct *curr, struct held_lock *this,
2397 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2398{
2399 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2400 return print_usage_bug(curr, this, bad_bit, new_bit);
2401 return 1;
2402}
2403
2404static int mark_lock(struct task_struct *curr, struct held_lock *this,
2405 enum lock_usage_bit new_bit);
2406
2407#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2408
2409/*
2410 * print irq inversion bug:
2411 */
2412static int
2413print_irq_inversion_bug(struct task_struct *curr,
2414 struct lock_list *root, struct lock_list *other,
2415 struct held_lock *this, int forwards,
2416 const char *irqclass)
2417{
2418 struct lock_list *entry = other;
2419 struct lock_list *middle = NULL;
2420 int depth;
2421
2422 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2423 return 0;
2424
2425 printk("\n");
2426 printk("=========================================================\n");
2427 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2428 print_kernel_ident();
2429 printk("---------------------------------------------------------\n");
2430 printk("%s/%d just changed the state of lock:\n",
2431 curr->comm, task_pid_nr(curr));
2432 print_lock(this);
2433 if (forwards)
2434 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2435 else
2436 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2437 print_lock_name(other->class);
2438 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2439
2440 printk("\nother info that might help us debug this:\n");
2441
2442 /* Find a middle lock (if one exists) */
2443 depth = get_lock_depth(other);
2444 do {
2445 if (depth == 0 && (entry != root)) {
2446 printk("lockdep:%s bad path found in chain graph\n", __func__);
2447 break;
2448 }
2449 middle = entry;
2450 entry = get_lock_parent(entry);
2451 depth--;
2452 } while (entry && entry != root && (depth >= 0));
2453 if (forwards)
2454 print_irq_lock_scenario(root, other,
2455 middle ? middle->class : root->class, other->class);
2456 else
2457 print_irq_lock_scenario(other, root,
2458 middle ? middle->class : other->class, root->class);
2459
2460 lockdep_print_held_locks(curr);
2461
2462 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2463 if (!save_trace(&root->trace))
2464 return 0;
2465 print_shortest_lock_dependencies(other, root);
2466
2467 printk("\nstack backtrace:\n");
2468 dump_stack();
2469
2470 return 0;
2471}
2472
2473/*
2474 * Prove that in the forwards-direction subgraph starting at <this>
2475 * there is no lock matching <mask>:
2476 */
2477static int
2478check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2479 enum lock_usage_bit bit, const char *irqclass)
2480{
2481 int ret;
2482 struct lock_list root;
2483 struct lock_list *uninitialized_var(target_entry);
2484
2485 root.parent = NULL;
2486 root.class = hlock_class(this);
2487 ret = find_usage_forwards(&root, bit, &target_entry);
2488 if (ret < 0)
2489 return print_bfs_bug(ret);
2490 if (ret == 1)
2491 return ret;
2492
2493 return print_irq_inversion_bug(curr, &root, target_entry,
2494 this, 1, irqclass);
2495}
2496
2497/*
2498 * Prove that in the backwards-direction subgraph starting at <this>
2499 * there is no lock matching <mask>:
2500 */
2501static int
2502check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2503 enum lock_usage_bit bit, const char *irqclass)
2504{
2505 int ret;
2506 struct lock_list root;
2507 struct lock_list *uninitialized_var(target_entry);
2508
2509 root.parent = NULL;
2510 root.class = hlock_class(this);
2511 ret = find_usage_backwards(&root, bit, &target_entry);
2512 if (ret < 0)
2513 return print_bfs_bug(ret);
2514 if (ret == 1)
2515 return ret;
2516
2517 return print_irq_inversion_bug(curr, &root, target_entry,
2518 this, 0, irqclass);
2519}
2520
2521void print_irqtrace_events(struct task_struct *curr)
2522{
2523 printk("irq event stamp: %u\n", curr->irq_events);
2524 printk("hardirqs last enabled at (%u): [<%p>] %pS\n",
2525 curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
2526 (void *)curr->hardirq_enable_ip);
2527 printk("hardirqs last disabled at (%u): [<%p>] %pS\n",
2528 curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
2529 (void *)curr->hardirq_disable_ip);
2530 printk("softirqs last enabled at (%u): [<%p>] %pS\n",
2531 curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
2532 (void *)curr->softirq_enable_ip);
2533 printk("softirqs last disabled at (%u): [<%p>] %pS\n",
2534 curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
2535 (void *)curr->softirq_disable_ip);
2536}
2537
2538static int HARDIRQ_verbose(struct lock_class *class)
2539{
2540#if HARDIRQ_VERBOSE
2541 return class_filter(class);
2542#endif
2543 return 0;
2544}
2545
2546static int SOFTIRQ_verbose(struct lock_class *class)
2547{
2548#if SOFTIRQ_VERBOSE
2549 return class_filter(class);
2550#endif
2551 return 0;
2552}
2553
2554static int RECLAIM_FS_verbose(struct lock_class *class)
2555{
2556#if RECLAIM_VERBOSE
2557 return class_filter(class);
2558#endif
2559 return 0;
2560}
2561
2562#define STRICT_READ_CHECKS 1
2563
2564static int (*state_verbose_f[])(struct lock_class *class) = {
2565#define LOCKDEP_STATE(__STATE) \
2566 __STATE##_verbose,
2567#include "lockdep_states.h"
2568#undef LOCKDEP_STATE
2569};
2570
2571static inline int state_verbose(enum lock_usage_bit bit,
2572 struct lock_class *class)
2573{
2574 return state_verbose_f[bit >> 2](class);
2575}
2576
2577typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2578 enum lock_usage_bit bit, const char *name);
2579
2580static int
2581mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2582 enum lock_usage_bit new_bit)
2583{
2584 int excl_bit = exclusive_bit(new_bit);
2585 int read = new_bit & 1;
2586 int dir = new_bit & 2;
2587
2588 /*
2589 * mark USED_IN has to look forwards -- to ensure no dependency
2590 * has ENABLED state, which would allow recursion deadlocks.
2591 *
2592 * mark ENABLED has to look backwards -- to ensure no dependee
2593 * has USED_IN state, which, again, would allow recursion deadlocks.
2594 */
2595 check_usage_f usage = dir ?
2596 check_usage_backwards : check_usage_forwards;
2597
2598 /*
2599 * Validate that this particular lock does not have conflicting
2600 * usage states.
2601 */
2602 if (!valid_state(curr, this, new_bit, excl_bit))
2603 return 0;
2604
2605 /*
2606 * Validate that the lock dependencies don't have conflicting usage
2607 * states.
2608 */
2609 if ((!read || !dir || STRICT_READ_CHECKS) &&
2610 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2611 return 0;
2612
2613 /*
2614 * Check for read in write conflicts
2615 */
2616 if (!read) {
2617 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2618 return 0;
2619
2620 if (STRICT_READ_CHECKS &&
2621 !usage(curr, this, excl_bit + 1,
2622 state_name(new_bit + 1)))
2623 return 0;
2624 }
2625
2626 if (state_verbose(new_bit, hlock_class(this)))
2627 return 2;
2628
2629 return 1;
2630}
2631
2632enum mark_type {
2633#define LOCKDEP_STATE(__STATE) __STATE,
2634#include "lockdep_states.h"
2635#undef LOCKDEP_STATE
2636};
2637
2638/*
2639 * Mark all held locks with a usage bit:
2640 */
2641static int
2642mark_held_locks(struct task_struct *curr, enum mark_type mark)
2643{
2644 enum lock_usage_bit usage_bit;
2645 struct held_lock *hlock;
2646 int i;
2647
2648 for (i = 0; i < curr->lockdep_depth; i++) {
2649 hlock = curr->held_locks + i;
2650
2651 usage_bit = 2 + (mark << 2); /* ENABLED */
2652 if (hlock->read)
2653 usage_bit += 1; /* READ */
2654
2655 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2656
2657 if (!hlock->check)
2658 continue;
2659
2660 if (!mark_lock(curr, hlock, usage_bit))
2661 return 0;
2662 }
2663
2664 return 1;
2665}
2666
2667/*
2668 * Hardirqs will be enabled:
2669 */
2670static void __trace_hardirqs_on_caller(unsigned long ip)
2671{
2672 struct task_struct *curr = current;
2673
2674 /* we'll do an OFF -> ON transition: */
2675 curr->hardirqs_enabled = 1;
2676
2677 /*
2678 * We are going to turn hardirqs on, so set the
2679 * usage bit for all held locks:
2680 */
2681 if (!mark_held_locks(curr, HARDIRQ))
2682 return;
2683 /*
2684 * If we have softirqs enabled, then set the usage
2685 * bit for all held locks. (disabled hardirqs prevented
2686 * this bit from being set before)
2687 */
2688 if (curr->softirqs_enabled)
2689 if (!mark_held_locks(curr, SOFTIRQ))
2690 return;
2691
2692 curr->hardirq_enable_ip = ip;
2693 curr->hardirq_enable_event = ++curr->irq_events;
2694 debug_atomic_inc(hardirqs_on_events);
2695}
2696
2697__visible void trace_hardirqs_on_caller(unsigned long ip)
2698{
2699 time_hardirqs_on(CALLER_ADDR0, ip);
2700
2701 if (unlikely(!debug_locks || current->lockdep_recursion))
2702 return;
2703
2704 if (unlikely(current->hardirqs_enabled)) {
2705 /*
2706 * Neither irq nor preemption are disabled here
2707 * so this is racy by nature but losing one hit
2708 * in a stat is not a big deal.
2709 */
2710 __debug_atomic_inc(redundant_hardirqs_on);
2711 return;
2712 }
2713
2714 /*
2715 * We're enabling irqs and according to our state above irqs weren't
2716 * already enabled, yet we find the hardware thinks they are in fact
2717 * enabled.. someone messed up their IRQ state tracing.
2718 */
2719 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2720 return;
2721
2722 /*
2723 * See the fine text that goes along with this variable definition.
2724 */
2725 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2726 return;
2727
2728 /*
2729 * Can't allow enabling interrupts while in an interrupt handler,
2730 * that's general bad form and such. Recursion, limited stack etc..
2731 */
2732 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2733 return;
2734
2735 current->lockdep_recursion = 1;
2736 __trace_hardirqs_on_caller(ip);
2737 current->lockdep_recursion = 0;
2738}
2739EXPORT_SYMBOL(trace_hardirqs_on_caller);
2740
2741void trace_hardirqs_on(void)
2742{
2743 trace_hardirqs_on_caller(CALLER_ADDR0);
2744}
2745EXPORT_SYMBOL(trace_hardirqs_on);
2746
2747/*
2748 * Hardirqs were disabled:
2749 */
2750__visible void trace_hardirqs_off_caller(unsigned long ip)
2751{
2752 struct task_struct *curr = current;
2753
2754 time_hardirqs_off(CALLER_ADDR0, ip);
2755
2756 if (unlikely(!debug_locks || current->lockdep_recursion))
2757 return;
2758
2759 /*
2760 * So we're supposed to get called after you mask local IRQs, but for
2761 * some reason the hardware doesn't quite think you did a proper job.
2762 */
2763 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2764 return;
2765
2766 if (curr->hardirqs_enabled) {
2767 /*
2768 * We have done an ON -> OFF transition:
2769 */
2770 curr->hardirqs_enabled = 0;
2771 curr->hardirq_disable_ip = ip;
2772 curr->hardirq_disable_event = ++curr->irq_events;
2773 debug_atomic_inc(hardirqs_off_events);
2774 } else
2775 debug_atomic_inc(redundant_hardirqs_off);
2776}
2777EXPORT_SYMBOL(trace_hardirqs_off_caller);
2778
2779void trace_hardirqs_off(void)
2780{
2781 trace_hardirqs_off_caller(CALLER_ADDR0);
2782}
2783EXPORT_SYMBOL(trace_hardirqs_off);
2784
2785/*
2786 * Softirqs will be enabled:
2787 */
2788void trace_softirqs_on(unsigned long ip)
2789{
2790 struct task_struct *curr = current;
2791
2792 if (unlikely(!debug_locks || current->lockdep_recursion))
2793 return;
2794
2795 /*
2796 * We fancy IRQs being disabled here, see softirq.c, avoids
2797 * funny state and nesting things.
2798 */
2799 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2800 return;
2801
2802 if (curr->softirqs_enabled) {
2803 debug_atomic_inc(redundant_softirqs_on);
2804 return;
2805 }
2806
2807 current->lockdep_recursion = 1;
2808 /*
2809 * We'll do an OFF -> ON transition:
2810 */
2811 curr->softirqs_enabled = 1;
2812 curr->softirq_enable_ip = ip;
2813 curr->softirq_enable_event = ++curr->irq_events;
2814 debug_atomic_inc(softirqs_on_events);
2815 /*
2816 * We are going to turn softirqs on, so set the
2817 * usage bit for all held locks, if hardirqs are
2818 * enabled too:
2819 */
2820 if (curr->hardirqs_enabled)
2821 mark_held_locks(curr, SOFTIRQ);
2822 current->lockdep_recursion = 0;
2823}
2824
2825/*
2826 * Softirqs were disabled:
2827 */
2828void trace_softirqs_off(unsigned long ip)
2829{
2830 struct task_struct *curr = current;
2831
2832 if (unlikely(!debug_locks || current->lockdep_recursion))
2833 return;
2834
2835 /*
2836 * We fancy IRQs being disabled here, see softirq.c
2837 */
2838 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2839 return;
2840
2841 if (curr->softirqs_enabled) {
2842 /*
2843 * We have done an ON -> OFF transition:
2844 */
2845 curr->softirqs_enabled = 0;
2846 curr->softirq_disable_ip = ip;
2847 curr->softirq_disable_event = ++curr->irq_events;
2848 debug_atomic_inc(softirqs_off_events);
2849 /*
2850 * Whoops, we wanted softirqs off, so why aren't they?
2851 */
2852 DEBUG_LOCKS_WARN_ON(!softirq_count());
2853 } else
2854 debug_atomic_inc(redundant_softirqs_off);
2855}
2856
2857static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2858{
2859 struct task_struct *curr = current;
2860
2861 if (unlikely(!debug_locks))
2862 return;
2863
2864 /* no reclaim without waiting on it */
2865 if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
2866 return;
2867
2868 /* this guy won't enter reclaim */
2869 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2870 return;
2871
2872 /* We're only interested __GFP_FS allocations for now */
2873 if (!(gfp_mask & __GFP_FS))
2874 return;
2875
2876 /*
2877 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2878 */
2879 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2880 return;
2881
2882 mark_held_locks(curr, RECLAIM_FS);
2883}
2884
2885static void check_flags(unsigned long flags);
2886
2887void lockdep_trace_alloc(gfp_t gfp_mask)
2888{
2889 unsigned long flags;
2890
2891 if (unlikely(current->lockdep_recursion))
2892 return;
2893
2894 raw_local_irq_save(flags);
2895 check_flags(flags);
2896 current->lockdep_recursion = 1;
2897 __lockdep_trace_alloc(gfp_mask, flags);
2898 current->lockdep_recursion = 0;
2899 raw_local_irq_restore(flags);
2900}
2901
2902static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2903{
2904 /*
2905 * If non-trylock use in a hardirq or softirq context, then
2906 * mark the lock as used in these contexts:
2907 */
2908 if (!hlock->trylock) {
2909 if (hlock->read) {
2910 if (curr->hardirq_context)
2911 if (!mark_lock(curr, hlock,
2912 LOCK_USED_IN_HARDIRQ_READ))
2913 return 0;
2914 if (curr->softirq_context)
2915 if (!mark_lock(curr, hlock,
2916 LOCK_USED_IN_SOFTIRQ_READ))
2917 return 0;
2918 } else {
2919 if (curr->hardirq_context)
2920 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2921 return 0;
2922 if (curr->softirq_context)
2923 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2924 return 0;
2925 }
2926 }
2927 if (!hlock->hardirqs_off) {
2928 if (hlock->read) {
2929 if (!mark_lock(curr, hlock,
2930 LOCK_ENABLED_HARDIRQ_READ))
2931 return 0;
2932 if (curr->softirqs_enabled)
2933 if (!mark_lock(curr, hlock,
2934 LOCK_ENABLED_SOFTIRQ_READ))
2935 return 0;
2936 } else {
2937 if (!mark_lock(curr, hlock,
2938 LOCK_ENABLED_HARDIRQ))
2939 return 0;
2940 if (curr->softirqs_enabled)
2941 if (!mark_lock(curr, hlock,
2942 LOCK_ENABLED_SOFTIRQ))
2943 return 0;
2944 }
2945 }
2946
2947 /*
2948 * We reuse the irq context infrastructure more broadly as a general
2949 * context checking code. This tests GFP_FS recursion (a lock taken
2950 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2951 * allocation).
2952 */
2953 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2954 if (hlock->read) {
2955 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2956 return 0;
2957 } else {
2958 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2959 return 0;
2960 }
2961 }
2962
2963 return 1;
2964}
2965
2966static inline unsigned int task_irq_context(struct task_struct *task)
2967{
2968 return 2 * !!task->hardirq_context + !!task->softirq_context;
2969}
2970
2971static int separate_irq_context(struct task_struct *curr,
2972 struct held_lock *hlock)
2973{
2974 unsigned int depth = curr->lockdep_depth;
2975
2976 /*
2977 * Keep track of points where we cross into an interrupt context:
2978 */
2979 if (depth) {
2980 struct held_lock *prev_hlock;
2981
2982 prev_hlock = curr->held_locks + depth-1;
2983 /*
2984 * If we cross into another context, reset the
2985 * hash key (this also prevents the checking and the
2986 * adding of the dependency to 'prev'):
2987 */
2988 if (prev_hlock->irq_context != hlock->irq_context)
2989 return 1;
2990 }
2991 return 0;
2992}
2993
2994#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2995
2996static inline
2997int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2998 enum lock_usage_bit new_bit)
2999{
3000 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
3001 return 1;
3002}
3003
3004static inline int mark_irqflags(struct task_struct *curr,
3005 struct held_lock *hlock)
3006{
3007 return 1;
3008}
3009
3010static inline unsigned int task_irq_context(struct task_struct *task)
3011{
3012 return 0;
3013}
3014
3015static inline int separate_irq_context(struct task_struct *curr,
3016 struct held_lock *hlock)
3017{
3018 return 0;
3019}
3020
3021void lockdep_trace_alloc(gfp_t gfp_mask)
3022{
3023}
3024
3025#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3026
3027/*
3028 * Mark a lock with a usage bit, and validate the state transition:
3029 */
3030static int mark_lock(struct task_struct *curr, struct held_lock *this,
3031 enum lock_usage_bit new_bit)
3032{
3033 unsigned int new_mask = 1 << new_bit, ret = 1;
3034
3035 /*
3036 * If already set then do not dirty the cacheline,
3037 * nor do any checks:
3038 */
3039 if (likely(hlock_class(this)->usage_mask & new_mask))
3040 return 1;
3041
3042 if (!graph_lock())
3043 return 0;
3044 /*
3045 * Make sure we didn't race:
3046 */
3047 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3048 graph_unlock();
3049 return 1;
3050 }
3051
3052 hlock_class(this)->usage_mask |= new_mask;
3053
3054 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
3055 return 0;
3056
3057 switch (new_bit) {
3058#define LOCKDEP_STATE(__STATE) \
3059 case LOCK_USED_IN_##__STATE: \
3060 case LOCK_USED_IN_##__STATE##_READ: \
3061 case LOCK_ENABLED_##__STATE: \
3062 case LOCK_ENABLED_##__STATE##_READ:
3063#include "lockdep_states.h"
3064#undef LOCKDEP_STATE
3065 ret = mark_lock_irq(curr, this, new_bit);
3066 if (!ret)
3067 return 0;
3068 break;
3069 case LOCK_USED:
3070 debug_atomic_dec(nr_unused_locks);
3071 break;
3072 default:
3073 if (!debug_locks_off_graph_unlock())
3074 return 0;
3075 WARN_ON(1);
3076 return 0;
3077 }
3078
3079 graph_unlock();
3080
3081 /*
3082 * We must printk outside of the graph_lock:
3083 */
3084 if (ret == 2) {
3085 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3086 print_lock(this);
3087 print_irqtrace_events(curr);
3088 dump_stack();
3089 }
3090
3091 return ret;
3092}
3093
3094/*
3095 * Initialize a lock instance's lock-class mapping info:
3096 */
3097void lockdep_init_map(struct lockdep_map *lock, const char *name,
3098 struct lock_class_key *key, int subclass)
3099{
3100 int i;
3101
3102 kmemcheck_mark_initialized(lock, sizeof(*lock));
3103
3104 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3105 lock->class_cache[i] = NULL;
3106
3107#ifdef CONFIG_LOCK_STAT
3108 lock->cpu = raw_smp_processor_id();
3109#endif
3110
3111 /*
3112 * Can't be having no nameless bastards around this place!
3113 */
3114 if (DEBUG_LOCKS_WARN_ON(!name)) {
3115 lock->name = "NULL";
3116 return;
3117 }
3118
3119 lock->name = name;
3120
3121 /*
3122 * No key, no joy, we need to hash something.
3123 */
3124 if (DEBUG_LOCKS_WARN_ON(!key))
3125 return;
3126 /*
3127 * Sanity check, the lock-class key must be persistent:
3128 */
3129 if (!static_obj(key)) {
3130 printk("BUG: key %p not in .data!\n", key);
3131 /*
3132 * What it says above ^^^^^, I suggest you read it.
3133 */
3134 DEBUG_LOCKS_WARN_ON(1);
3135 return;
3136 }
3137 lock->key = key;
3138
3139 if (unlikely(!debug_locks))
3140 return;
3141
3142 if (subclass) {
3143 unsigned long flags;
3144
3145 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3146 return;
3147
3148 raw_local_irq_save(flags);
3149 current->lockdep_recursion = 1;
3150 register_lock_class(lock, subclass, 1);
3151 current->lockdep_recursion = 0;
3152 raw_local_irq_restore(flags);
3153 }
3154}
3155EXPORT_SYMBOL_GPL(lockdep_init_map);
3156
3157struct lock_class_key __lockdep_no_validate__;
3158EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3159
3160static int
3161print_lock_nested_lock_not_held(struct task_struct *curr,
3162 struct held_lock *hlock,
3163 unsigned long ip)
3164{
3165 if (!debug_locks_off())
3166 return 0;
3167 if (debug_locks_silent)
3168 return 0;
3169
3170 printk("\n");
3171 printk("==================================\n");
3172 printk("[ BUG: Nested lock was not taken ]\n");
3173 print_kernel_ident();
3174 printk("----------------------------------\n");
3175
3176 printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3177 print_lock(hlock);
3178
3179 printk("\nbut this task is not holding:\n");
3180 printk("%s\n", hlock->nest_lock->name);
3181
3182 printk("\nstack backtrace:\n");
3183 dump_stack();
3184
3185 printk("\nother info that might help us debug this:\n");
3186 lockdep_print_held_locks(curr);
3187
3188 printk("\nstack backtrace:\n");
3189 dump_stack();
3190
3191 return 0;
3192}
3193
3194static int __lock_is_held(struct lockdep_map *lock, int read);
3195
3196/*
3197 * This gets called for every mutex_lock*()/spin_lock*() operation.
3198 * We maintain the dependency maps and validate the locking attempt:
3199 */
3200static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3201 int trylock, int read, int check, int hardirqs_off,
3202 struct lockdep_map *nest_lock, unsigned long ip,
3203 int references, int pin_count)
3204{
3205 struct task_struct *curr = current;
3206 struct lock_class *class = NULL;
3207 struct held_lock *hlock;
3208 unsigned int depth;
3209 int chain_head = 0;
3210 int class_idx;
3211 u64 chain_key;
3212
3213 if (unlikely(!debug_locks))
3214 return 0;
3215
3216 /*
3217 * Lockdep should run with IRQs disabled, otherwise we could
3218 * get an interrupt which would want to take locks, which would
3219 * end up in lockdep and have you got a head-ache already?
3220 */
3221 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3222 return 0;
3223
3224 if (!prove_locking || lock->key == &__lockdep_no_validate__)
3225 check = 0;
3226
3227 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3228 class = lock->class_cache[subclass];
3229 /*
3230 * Not cached?
3231 */
3232 if (unlikely(!class)) {
3233 class = register_lock_class(lock, subclass, 0);
3234 if (!class)
3235 return 0;
3236 }
3237 atomic_inc((atomic_t *)&class->ops);
3238 if (very_verbose(class)) {
3239 printk("\nacquire class [%p] %s", class->key, class->name);
3240 if (class->name_version > 1)
3241 printk(KERN_CONT "#%d", class->name_version);
3242 printk(KERN_CONT "\n");
3243 dump_stack();
3244 }
3245
3246 /*
3247 * Add the lock to the list of currently held locks.
3248 * (we dont increase the depth just yet, up until the
3249 * dependency checks are done)
3250 */
3251 depth = curr->lockdep_depth;
3252 /*
3253 * Ran out of static storage for our per-task lock stack again have we?
3254 */
3255 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3256 return 0;
3257
3258 class_idx = class - lock_classes + 1;
3259
3260 if (depth) {
3261 hlock = curr->held_locks + depth - 1;
3262 if (hlock->class_idx == class_idx && nest_lock) {
3263 if (hlock->references)
3264 hlock->references++;
3265 else
3266 hlock->references = 2;
3267
3268 return 1;
3269 }
3270 }
3271
3272 hlock = curr->held_locks + depth;
3273 /*
3274 * Plain impossible, we just registered it and checked it weren't no
3275 * NULL like.. I bet this mushroom I ate was good!
3276 */
3277 if (DEBUG_LOCKS_WARN_ON(!class))
3278 return 0;
3279 hlock->class_idx = class_idx;
3280 hlock->acquire_ip = ip;
3281 hlock->instance = lock;
3282 hlock->nest_lock = nest_lock;
3283 hlock->irq_context = task_irq_context(curr);
3284 hlock->trylock = trylock;
3285 hlock->read = read;
3286 hlock->check = check;
3287 hlock->hardirqs_off = !!hardirqs_off;
3288 hlock->references = references;
3289#ifdef CONFIG_LOCK_STAT
3290 hlock->waittime_stamp = 0;
3291 hlock->holdtime_stamp = lockstat_clock();
3292#endif
3293 hlock->pin_count = pin_count;
3294
3295 if (check && !mark_irqflags(curr, hlock))
3296 return 0;
3297
3298 /* mark it as used: */
3299 if (!mark_lock(curr, hlock, LOCK_USED))
3300 return 0;
3301
3302 /*
3303 * Calculate the chain hash: it's the combined hash of all the
3304 * lock keys along the dependency chain. We save the hash value
3305 * at every step so that we can get the current hash easily
3306 * after unlock. The chain hash is then used to cache dependency
3307 * results.
3308 *
3309 * The 'key ID' is what is the most compact key value to drive
3310 * the hash, not class->key.
3311 */
3312 /*
3313 * Whoops, we did it again.. ran straight out of our static allocation.
3314 */
3315 if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
3316 return 0;
3317
3318 chain_key = curr->curr_chain_key;
3319 if (!depth) {
3320 /*
3321 * How can we have a chain hash when we ain't got no keys?!
3322 */
3323 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3324 return 0;
3325 chain_head = 1;
3326 }
3327
3328 hlock->prev_chain_key = chain_key;
3329 if (separate_irq_context(curr, hlock)) {
3330 chain_key = 0;
3331 chain_head = 1;
3332 }
3333 chain_key = iterate_chain_key(chain_key, class_idx);
3334
3335 if (nest_lock && !__lock_is_held(nest_lock, -1))
3336 return print_lock_nested_lock_not_held(curr, hlock, ip);
3337
3338 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3339 return 0;
3340
3341 curr->curr_chain_key = chain_key;
3342 curr->lockdep_depth++;
3343 check_chain_key(curr);
3344#ifdef CONFIG_DEBUG_LOCKDEP
3345 if (unlikely(!debug_locks))
3346 return 0;
3347#endif
3348 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3349 debug_locks_off();
3350 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3351 printk(KERN_DEBUG "depth: %i max: %lu!\n",
3352 curr->lockdep_depth, MAX_LOCK_DEPTH);
3353
3354 lockdep_print_held_locks(current);
3355 debug_show_all_locks();
3356 dump_stack();
3357
3358 return 0;
3359 }
3360
3361 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3362 max_lockdep_depth = curr->lockdep_depth;
3363
3364 return 1;
3365}
3366
3367static int
3368print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3369 unsigned long ip)
3370{
3371 if (!debug_locks_off())
3372 return 0;
3373 if (debug_locks_silent)
3374 return 0;
3375
3376 printk("\n");
3377 printk("=====================================\n");
3378 printk("[ BUG: bad unlock balance detected! ]\n");
3379 print_kernel_ident();
3380 printk("-------------------------------------\n");
3381 printk("%s/%d is trying to release lock (",
3382 curr->comm, task_pid_nr(curr));
3383 print_lockdep_cache(lock);
3384 printk(KERN_CONT ") at:\n");
3385 print_ip_sym(ip);
3386 printk("but there are no more locks to release!\n");
3387 printk("\nother info that might help us debug this:\n");
3388 lockdep_print_held_locks(curr);
3389
3390 printk("\nstack backtrace:\n");
3391 dump_stack();
3392
3393 return 0;
3394}
3395
3396static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3397{
3398 if (hlock->instance == lock)
3399 return 1;
3400
3401 if (hlock->references) {
3402 struct lock_class *class = lock->class_cache[0];
3403
3404 if (!class)
3405 class = look_up_lock_class(lock, 0);
3406
3407 /*
3408 * If look_up_lock_class() failed to find a class, we're trying
3409 * to test if we hold a lock that has never yet been acquired.
3410 * Clearly if the lock hasn't been acquired _ever_, we're not
3411 * holding it either, so report failure.
3412 */
3413 if (!class)
3414 return 0;
3415
3416 /*
3417 * References, but not a lock we're actually ref-counting?
3418 * State got messed up, follow the sites that change ->references
3419 * and try to make sense of it.
3420 */
3421 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3422 return 0;
3423
3424 if (hlock->class_idx == class - lock_classes + 1)
3425 return 1;
3426 }
3427
3428 return 0;
3429}
3430
3431static int
3432__lock_set_class(struct lockdep_map *lock, const char *name,
3433 struct lock_class_key *key, unsigned int subclass,
3434 unsigned long ip)
3435{
3436 struct task_struct *curr = current;
3437 struct held_lock *hlock, *prev_hlock;
3438 struct lock_class *class;
3439 unsigned int depth;
3440 int i;
3441
3442 depth = curr->lockdep_depth;
3443 /*
3444 * This function is about (re)setting the class of a held lock,
3445 * yet we're not actually holding any locks. Naughty user!
3446 */
3447 if (DEBUG_LOCKS_WARN_ON(!depth))
3448 return 0;
3449
3450 prev_hlock = NULL;
3451 for (i = depth-1; i >= 0; i--) {
3452 hlock = curr->held_locks + i;
3453 /*
3454 * We must not cross into another context:
3455 */
3456 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3457 break;
3458 if (match_held_lock(hlock, lock))
3459 goto found_it;
3460 prev_hlock = hlock;
3461 }
3462 return print_unlock_imbalance_bug(curr, lock, ip);
3463
3464found_it:
3465 lockdep_init_map(lock, name, key, 0);
3466 class = register_lock_class(lock, subclass, 0);
3467 hlock->class_idx = class - lock_classes + 1;
3468
3469 curr->lockdep_depth = i;
3470 curr->curr_chain_key = hlock->prev_chain_key;
3471
3472 for (; i < depth; i++) {
3473 hlock = curr->held_locks + i;
3474 if (!__lock_acquire(hlock->instance,
3475 hlock_class(hlock)->subclass, hlock->trylock,
3476 hlock->read, hlock->check, hlock->hardirqs_off,
3477 hlock->nest_lock, hlock->acquire_ip,
3478 hlock->references, hlock->pin_count))
3479 return 0;
3480 }
3481
3482 /*
3483 * I took it apart and put it back together again, except now I have
3484 * these 'spare' parts.. where shall I put them.
3485 */
3486 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3487 return 0;
3488 return 1;
3489}
3490
3491/*
3492 * Remove the lock to the list of currently held locks - this gets
3493 * called on mutex_unlock()/spin_unlock*() (or on a failed
3494 * mutex_lock_interruptible()).
3495 *
3496 * @nested is an hysterical artifact, needs a tree wide cleanup.
3497 */
3498static int
3499__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3500{
3501 struct task_struct *curr = current;
3502 struct held_lock *hlock, *prev_hlock;
3503 unsigned int depth;
3504 int i;
3505
3506 if (unlikely(!debug_locks))
3507 return 0;
3508
3509 depth = curr->lockdep_depth;
3510 /*
3511 * So we're all set to release this lock.. wait what lock? We don't
3512 * own any locks, you've been drinking again?
3513 */
3514 if (DEBUG_LOCKS_WARN_ON(depth <= 0))
3515 return print_unlock_imbalance_bug(curr, lock, ip);
3516
3517 /*
3518 * Check whether the lock exists in the current stack
3519 * of held locks:
3520 */
3521 prev_hlock = NULL;
3522 for (i = depth-1; i >= 0; i--) {
3523 hlock = curr->held_locks + i;
3524 /*
3525 * We must not cross into another context:
3526 */
3527 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3528 break;
3529 if (match_held_lock(hlock, lock))
3530 goto found_it;
3531 prev_hlock = hlock;
3532 }
3533 return print_unlock_imbalance_bug(curr, lock, ip);
3534
3535found_it:
3536 if (hlock->instance == lock)
3537 lock_release_holdtime(hlock);
3538
3539 WARN(hlock->pin_count, "releasing a pinned lock\n");
3540
3541 if (hlock->references) {
3542 hlock->references--;
3543 if (hlock->references) {
3544 /*
3545 * We had, and after removing one, still have
3546 * references, the current lock stack is still
3547 * valid. We're done!
3548 */
3549 return 1;
3550 }
3551 }
3552
3553 /*
3554 * We have the right lock to unlock, 'hlock' points to it.
3555 * Now we remove it from the stack, and add back the other
3556 * entries (if any), recalculating the hash along the way:
3557 */
3558
3559 curr->lockdep_depth = i;
3560 curr->curr_chain_key = hlock->prev_chain_key;
3561
3562 for (i++; i < depth; i++) {
3563 hlock = curr->held_locks + i;
3564 if (!__lock_acquire(hlock->instance,
3565 hlock_class(hlock)->subclass, hlock->trylock,
3566 hlock->read, hlock->check, hlock->hardirqs_off,
3567 hlock->nest_lock, hlock->acquire_ip,
3568 hlock->references, hlock->pin_count))
3569 return 0;
3570 }
3571
3572 /*
3573 * We had N bottles of beer on the wall, we drank one, but now
3574 * there's not N-1 bottles of beer left on the wall...
3575 */
3576 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3577 return 0;
3578
3579 return 1;
3580}
3581
3582static int __lock_is_held(struct lockdep_map *lock, int read)
3583{
3584 struct task_struct *curr = current;
3585 int i;
3586
3587 for (i = 0; i < curr->lockdep_depth; i++) {
3588 struct held_lock *hlock = curr->held_locks + i;
3589
3590 if (match_held_lock(hlock, lock)) {
3591 if (read == -1 || hlock->read == read)
3592 return 1;
3593
3594 return 0;
3595 }
3596 }
3597
3598 return 0;
3599}
3600
3601static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
3602{
3603 struct pin_cookie cookie = NIL_COOKIE;
3604 struct task_struct *curr = current;
3605 int i;
3606
3607 if (unlikely(!debug_locks))
3608 return cookie;
3609
3610 for (i = 0; i < curr->lockdep_depth; i++) {
3611 struct held_lock *hlock = curr->held_locks + i;
3612
3613 if (match_held_lock(hlock, lock)) {
3614 /*
3615 * Grab 16bits of randomness; this is sufficient to not
3616 * be guessable and still allows some pin nesting in
3617 * our u32 pin_count.
3618 */
3619 cookie.val = 1 + (prandom_u32() >> 16);
3620 hlock->pin_count += cookie.val;
3621 return cookie;
3622 }
3623 }
3624
3625 WARN(1, "pinning an unheld lock\n");
3626 return cookie;
3627}
3628
3629static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3630{
3631 struct task_struct *curr = current;
3632 int i;
3633
3634 if (unlikely(!debug_locks))
3635 return;
3636
3637 for (i = 0; i < curr->lockdep_depth; i++) {
3638 struct held_lock *hlock = curr->held_locks + i;
3639
3640 if (match_held_lock(hlock, lock)) {
3641 hlock->pin_count += cookie.val;
3642 return;
3643 }
3644 }
3645
3646 WARN(1, "pinning an unheld lock\n");
3647}
3648
3649static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3650{
3651 struct task_struct *curr = current;
3652 int i;
3653
3654 if (unlikely(!debug_locks))
3655 return;
3656
3657 for (i = 0; i < curr->lockdep_depth; i++) {
3658 struct held_lock *hlock = curr->held_locks + i;
3659
3660 if (match_held_lock(hlock, lock)) {
3661 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
3662 return;
3663
3664 hlock->pin_count -= cookie.val;
3665
3666 if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
3667 hlock->pin_count = 0;
3668
3669 return;
3670 }
3671 }
3672
3673 WARN(1, "unpinning an unheld lock\n");
3674}
3675
3676/*
3677 * Check whether we follow the irq-flags state precisely:
3678 */
3679static void check_flags(unsigned long flags)
3680{
3681#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3682 defined(CONFIG_TRACE_IRQFLAGS)
3683 if (!debug_locks)
3684 return;
3685
3686 if (irqs_disabled_flags(flags)) {
3687 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3688 printk("possible reason: unannotated irqs-off.\n");
3689 }
3690 } else {
3691 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3692 printk("possible reason: unannotated irqs-on.\n");
3693 }
3694 }
3695
3696 /*
3697 * We dont accurately track softirq state in e.g.
3698 * hardirq contexts (such as on 4KSTACKS), so only
3699 * check if not in hardirq contexts:
3700 */
3701 if (!hardirq_count()) {
3702 if (softirq_count()) {
3703 /* like the above, but with softirqs */
3704 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3705 } else {
3706 /* lick the above, does it taste good? */
3707 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3708 }
3709 }
3710
3711 if (!debug_locks)
3712 print_irqtrace_events(current);
3713#endif
3714}
3715
3716void lock_set_class(struct lockdep_map *lock, const char *name,
3717 struct lock_class_key *key, unsigned int subclass,
3718 unsigned long ip)
3719{
3720 unsigned long flags;
3721
3722 if (unlikely(current->lockdep_recursion))
3723 return;
3724
3725 raw_local_irq_save(flags);
3726 current->lockdep_recursion = 1;
3727 check_flags(flags);
3728 if (__lock_set_class(lock, name, key, subclass, ip))
3729 check_chain_key(current);
3730 current->lockdep_recursion = 0;
3731 raw_local_irq_restore(flags);
3732}
3733EXPORT_SYMBOL_GPL(lock_set_class);
3734
3735/*
3736 * We are not always called with irqs disabled - do that here,
3737 * and also avoid lockdep recursion:
3738 */
3739void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3740 int trylock, int read, int check,
3741 struct lockdep_map *nest_lock, unsigned long ip)
3742{
3743 unsigned long flags;
3744
3745 if (unlikely(current->lockdep_recursion))
3746 return;
3747
3748 raw_local_irq_save(flags);
3749 check_flags(flags);
3750
3751 current->lockdep_recursion = 1;
3752 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3753 __lock_acquire(lock, subclass, trylock, read, check,
3754 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
3755 current->lockdep_recursion = 0;
3756 raw_local_irq_restore(flags);
3757}
3758EXPORT_SYMBOL_GPL(lock_acquire);
3759
3760void lock_release(struct lockdep_map *lock, int nested,
3761 unsigned long ip)
3762{
3763 unsigned long flags;
3764
3765 if (unlikely(current->lockdep_recursion))
3766 return;
3767
3768 raw_local_irq_save(flags);
3769 check_flags(flags);
3770 current->lockdep_recursion = 1;
3771 trace_lock_release(lock, ip);
3772 if (__lock_release(lock, nested, ip))
3773 check_chain_key(current);
3774 current->lockdep_recursion = 0;
3775 raw_local_irq_restore(flags);
3776}
3777EXPORT_SYMBOL_GPL(lock_release);
3778
3779int lock_is_held_type(struct lockdep_map *lock, int read)
3780{
3781 unsigned long flags;
3782 int ret = 0;
3783
3784 if (unlikely(current->lockdep_recursion))
3785 return 1; /* avoid false negative lockdep_assert_held() */
3786
3787 raw_local_irq_save(flags);
3788 check_flags(flags);
3789
3790 current->lockdep_recursion = 1;
3791 ret = __lock_is_held(lock, read);
3792 current->lockdep_recursion = 0;
3793 raw_local_irq_restore(flags);
3794
3795 return ret;
3796}
3797EXPORT_SYMBOL_GPL(lock_is_held_type);
3798
3799struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
3800{
3801 struct pin_cookie cookie = NIL_COOKIE;
3802 unsigned long flags;
3803
3804 if (unlikely(current->lockdep_recursion))
3805 return cookie;
3806
3807 raw_local_irq_save(flags);
3808 check_flags(flags);
3809
3810 current->lockdep_recursion = 1;
3811 cookie = __lock_pin_lock(lock);
3812 current->lockdep_recursion = 0;
3813 raw_local_irq_restore(flags);
3814
3815 return cookie;
3816}
3817EXPORT_SYMBOL_GPL(lock_pin_lock);
3818
3819void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3820{
3821 unsigned long flags;
3822
3823 if (unlikely(current->lockdep_recursion))
3824 return;
3825
3826 raw_local_irq_save(flags);
3827 check_flags(flags);
3828
3829 current->lockdep_recursion = 1;
3830 __lock_repin_lock(lock, cookie);
3831 current->lockdep_recursion = 0;
3832 raw_local_irq_restore(flags);
3833}
3834EXPORT_SYMBOL_GPL(lock_repin_lock);
3835
3836void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3837{
3838 unsigned long flags;
3839
3840 if (unlikely(current->lockdep_recursion))
3841 return;
3842
3843 raw_local_irq_save(flags);
3844 check_flags(flags);
3845
3846 current->lockdep_recursion = 1;
3847 __lock_unpin_lock(lock, cookie);
3848 current->lockdep_recursion = 0;
3849 raw_local_irq_restore(flags);
3850}
3851EXPORT_SYMBOL_GPL(lock_unpin_lock);
3852
3853void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3854{
3855 current->lockdep_reclaim_gfp = gfp_mask;
3856}
3857
3858void lockdep_clear_current_reclaim_state(void)
3859{
3860 current->lockdep_reclaim_gfp = 0;
3861}
3862
3863#ifdef CONFIG_LOCK_STAT
3864static int
3865print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3866 unsigned long ip)
3867{
3868 if (!debug_locks_off())
3869 return 0;
3870 if (debug_locks_silent)
3871 return 0;
3872
3873 printk("\n");
3874 printk("=================================\n");
3875 printk("[ BUG: bad contention detected! ]\n");
3876 print_kernel_ident();
3877 printk("---------------------------------\n");
3878 printk("%s/%d is trying to contend lock (",
3879 curr->comm, task_pid_nr(curr));
3880 print_lockdep_cache(lock);
3881 printk(KERN_CONT ") at:\n");
3882 print_ip_sym(ip);
3883 printk("but there are no locks held!\n");
3884 printk("\nother info that might help us debug this:\n");
3885 lockdep_print_held_locks(curr);
3886
3887 printk("\nstack backtrace:\n");
3888 dump_stack();
3889
3890 return 0;
3891}
3892
3893static void
3894__lock_contended(struct lockdep_map *lock, unsigned long ip)
3895{
3896 struct task_struct *curr = current;
3897 struct held_lock *hlock, *prev_hlock;
3898 struct lock_class_stats *stats;
3899 unsigned int depth;
3900 int i, contention_point, contending_point;
3901
3902 depth = curr->lockdep_depth;
3903 /*
3904 * Whee, we contended on this lock, except it seems we're not
3905 * actually trying to acquire anything much at all..
3906 */
3907 if (DEBUG_LOCKS_WARN_ON(!depth))
3908 return;
3909
3910 prev_hlock = NULL;
3911 for (i = depth-1; i >= 0; i--) {
3912 hlock = curr->held_locks + i;
3913 /*
3914 * We must not cross into another context:
3915 */
3916 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3917 break;
3918 if (match_held_lock(hlock, lock))
3919 goto found_it;
3920 prev_hlock = hlock;
3921 }
3922 print_lock_contention_bug(curr, lock, ip);
3923 return;
3924
3925found_it:
3926 if (hlock->instance != lock)
3927 return;
3928
3929 hlock->waittime_stamp = lockstat_clock();
3930
3931 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3932 contending_point = lock_point(hlock_class(hlock)->contending_point,
3933 lock->ip);
3934
3935 stats = get_lock_stats(hlock_class(hlock));
3936 if (contention_point < LOCKSTAT_POINTS)
3937 stats->contention_point[contention_point]++;
3938 if (contending_point < LOCKSTAT_POINTS)
3939 stats->contending_point[contending_point]++;
3940 if (lock->cpu != smp_processor_id())
3941 stats->bounces[bounce_contended + !!hlock->read]++;
3942 put_lock_stats(stats);
3943}
3944
3945static void
3946__lock_acquired(struct lockdep_map *lock, unsigned long ip)
3947{
3948 struct task_struct *curr = current;
3949 struct held_lock *hlock, *prev_hlock;
3950 struct lock_class_stats *stats;
3951 unsigned int depth;
3952 u64 now, waittime = 0;
3953 int i, cpu;
3954
3955 depth = curr->lockdep_depth;
3956 /*
3957 * Yay, we acquired ownership of this lock we didn't try to
3958 * acquire, how the heck did that happen?
3959 */
3960 if (DEBUG_LOCKS_WARN_ON(!depth))
3961 return;
3962
3963 prev_hlock = NULL;
3964 for (i = depth-1; i >= 0; i--) {
3965 hlock = curr->held_locks + i;
3966 /*
3967 * We must not cross into another context:
3968 */
3969 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3970 break;
3971 if (match_held_lock(hlock, lock))
3972 goto found_it;
3973 prev_hlock = hlock;
3974 }
3975 print_lock_contention_bug(curr, lock, _RET_IP_);
3976 return;
3977
3978found_it:
3979 if (hlock->instance != lock)
3980 return;
3981
3982 cpu = smp_processor_id();
3983 if (hlock->waittime_stamp) {
3984 now = lockstat_clock();
3985 waittime = now - hlock->waittime_stamp;
3986 hlock->holdtime_stamp = now;
3987 }
3988
3989 trace_lock_acquired(lock, ip);
3990
3991 stats = get_lock_stats(hlock_class(hlock));
3992 if (waittime) {
3993 if (hlock->read)
3994 lock_time_inc(&stats->read_waittime, waittime);
3995 else
3996 lock_time_inc(&stats->write_waittime, waittime);
3997 }
3998 if (lock->cpu != cpu)
3999 stats->bounces[bounce_acquired + !!hlock->read]++;
4000 put_lock_stats(stats);
4001
4002 lock->cpu = cpu;
4003 lock->ip = ip;
4004}
4005
4006void lock_contended(struct lockdep_map *lock, unsigned long ip)
4007{
4008 unsigned long flags;
4009
4010 if (unlikely(!lock_stat))
4011 return;
4012
4013 if (unlikely(current->lockdep_recursion))
4014 return;
4015
4016 raw_local_irq_save(flags);
4017 check_flags(flags);
4018 current->lockdep_recursion = 1;
4019 trace_lock_contended(lock, ip);
4020 __lock_contended(lock, ip);
4021 current->lockdep_recursion = 0;
4022 raw_local_irq_restore(flags);
4023}
4024EXPORT_SYMBOL_GPL(lock_contended);
4025
4026void lock_acquired(struct lockdep_map *lock, unsigned long ip)
4027{
4028 unsigned long flags;
4029
4030 if (unlikely(!lock_stat))
4031 return;
4032
4033 if (unlikely(current->lockdep_recursion))
4034 return;
4035
4036 raw_local_irq_save(flags);
4037 check_flags(flags);
4038 current->lockdep_recursion = 1;
4039 __lock_acquired(lock, ip);
4040 current->lockdep_recursion = 0;
4041 raw_local_irq_restore(flags);
4042}
4043EXPORT_SYMBOL_GPL(lock_acquired);
4044#endif
4045
4046/*
4047 * Used by the testsuite, sanitize the validator state
4048 * after a simulated failure:
4049 */
4050
4051void lockdep_reset(void)
4052{
4053 unsigned long flags;
4054 int i;
4055
4056 raw_local_irq_save(flags);
4057 current->curr_chain_key = 0;
4058 current->lockdep_depth = 0;
4059 current->lockdep_recursion = 0;
4060 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
4061 nr_hardirq_chains = 0;
4062 nr_softirq_chains = 0;
4063 nr_process_chains = 0;
4064 debug_locks = 1;
4065 for (i = 0; i < CHAINHASH_SIZE; i++)
4066 INIT_HLIST_HEAD(chainhash_table + i);
4067 raw_local_irq_restore(flags);
4068}
4069
4070static void zap_class(struct lock_class *class)
4071{
4072 int i;
4073
4074 /*
4075 * Remove all dependencies this lock is
4076 * involved in:
4077 */
4078 for (i = 0; i < nr_list_entries; i++) {
4079 if (list_entries[i].class == class)
4080 list_del_rcu(&list_entries[i].entry);
4081 }
4082 /*
4083 * Unhash the class and remove it from the all_lock_classes list:
4084 */
4085 hlist_del_rcu(&class->hash_entry);
4086 list_del_rcu(&class->lock_entry);
4087
4088 RCU_INIT_POINTER(class->key, NULL);
4089 RCU_INIT_POINTER(class->name, NULL);
4090}
4091
4092static inline int within(const void *addr, void *start, unsigned long size)
4093{
4094 return addr >= start && addr < start + size;
4095}
4096
4097/*
4098 * Used in module.c to remove lock classes from memory that is going to be
4099 * freed; and possibly re-used by other modules.
4100 *
4101 * We will have had one sync_sched() before getting here, so we're guaranteed
4102 * nobody will look up these exact classes -- they're properly dead but still
4103 * allocated.
4104 */
4105void lockdep_free_key_range(void *start, unsigned long size)
4106{
4107 struct lock_class *class;
4108 struct hlist_head *head;
4109 unsigned long flags;
4110 int i;
4111 int locked;
4112
4113 raw_local_irq_save(flags);
4114 locked = graph_lock();
4115
4116 /*
4117 * Unhash all classes that were created by this module:
4118 */
4119 for (i = 0; i < CLASSHASH_SIZE; i++) {
4120 head = classhash_table + i;
4121 hlist_for_each_entry_rcu(class, head, hash_entry) {
4122 if (within(class->key, start, size))
4123 zap_class(class);
4124 else if (within(class->name, start, size))
4125 zap_class(class);
4126 }
4127 }
4128
4129 if (locked)
4130 graph_unlock();
4131 raw_local_irq_restore(flags);
4132
4133 /*
4134 * Wait for any possible iterators from look_up_lock_class() to pass
4135 * before continuing to free the memory they refer to.
4136 *
4137 * sync_sched() is sufficient because the read-side is IRQ disable.
4138 */
4139 synchronize_sched();
4140
4141 /*
4142 * XXX at this point we could return the resources to the pool;
4143 * instead we leak them. We would need to change to bitmap allocators
4144 * instead of the linear allocators we have now.
4145 */
4146}
4147
4148void lockdep_reset_lock(struct lockdep_map *lock)
4149{
4150 struct lock_class *class;
4151 struct hlist_head *head;
4152 unsigned long flags;
4153 int i, j;
4154 int locked;
4155
4156 raw_local_irq_save(flags);
4157
4158 /*
4159 * Remove all classes this lock might have:
4160 */
4161 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
4162 /*
4163 * If the class exists we look it up and zap it:
4164 */
4165 class = look_up_lock_class(lock, j);
4166 if (class)
4167 zap_class(class);
4168 }
4169 /*
4170 * Debug check: in the end all mapped classes should
4171 * be gone.
4172 */
4173 locked = graph_lock();
4174 for (i = 0; i < CLASSHASH_SIZE; i++) {
4175 head = classhash_table + i;
4176 hlist_for_each_entry_rcu(class, head, hash_entry) {
4177 int match = 0;
4178
4179 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
4180 match |= class == lock->class_cache[j];
4181
4182 if (unlikely(match)) {
4183 if (debug_locks_off_graph_unlock()) {
4184 /*
4185 * We all just reset everything, how did it match?
4186 */
4187 WARN_ON(1);
4188 }
4189 goto out_restore;
4190 }
4191 }
4192 }
4193 if (locked)
4194 graph_unlock();
4195
4196out_restore:
4197 raw_local_irq_restore(flags);
4198}
4199
4200void __init lockdep_info(void)
4201{
4202 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4203
4204 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
4205 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
4206 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
4207 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
4208 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
4209 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
4210 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
4211
4212 printk(" memory used by lock dependency info: %lu kB\n",
4213 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4214 sizeof(struct list_head) * CLASSHASH_SIZE +
4215 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4216 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4217 sizeof(struct list_head) * CHAINHASH_SIZE
4218#ifdef CONFIG_PROVE_LOCKING
4219 + sizeof(struct circular_queue)
4220#endif
4221 ) / 1024
4222 );
4223
4224 printk(" per task-struct memory footprint: %lu bytes\n",
4225 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4226}
4227
4228static void
4229print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4230 const void *mem_to, struct held_lock *hlock)
4231{
4232 if (!debug_locks_off())
4233 return;
4234 if (debug_locks_silent)
4235 return;
4236
4237 printk("\n");
4238 printk("=========================\n");
4239 printk("[ BUG: held lock freed! ]\n");
4240 print_kernel_ident();
4241 printk("-------------------------\n");
4242 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4243 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4244 print_lock(hlock);
4245 lockdep_print_held_locks(curr);
4246
4247 printk("\nstack backtrace:\n");
4248 dump_stack();
4249}
4250
4251static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4252 const void* lock_from, unsigned long lock_len)
4253{
4254 return lock_from + lock_len <= mem_from ||
4255 mem_from + mem_len <= lock_from;
4256}
4257
4258/*
4259 * Called when kernel memory is freed (or unmapped), or if a lock
4260 * is destroyed or reinitialized - this code checks whether there is
4261 * any held lock in the memory range of <from> to <to>:
4262 */
4263void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4264{
4265 struct task_struct *curr = current;
4266 struct held_lock *hlock;
4267 unsigned long flags;
4268 int i;
4269
4270 if (unlikely(!debug_locks))
4271 return;
4272
4273 local_irq_save(flags);
4274 for (i = 0; i < curr->lockdep_depth; i++) {
4275 hlock = curr->held_locks + i;
4276
4277 if (not_in_range(mem_from, mem_len, hlock->instance,
4278 sizeof(*hlock->instance)))
4279 continue;
4280
4281 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4282 break;
4283 }
4284 local_irq_restore(flags);
4285}
4286EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4287
4288static void print_held_locks_bug(void)
4289{
4290 if (!debug_locks_off())
4291 return;
4292 if (debug_locks_silent)
4293 return;
4294
4295 printk("\n");
4296 printk("=====================================\n");
4297 printk("[ BUG: %s/%d still has locks held! ]\n",
4298 current->comm, task_pid_nr(current));
4299 print_kernel_ident();
4300 printk("-------------------------------------\n");
4301 lockdep_print_held_locks(current);
4302 printk("\nstack backtrace:\n");
4303 dump_stack();
4304}
4305
4306void debug_check_no_locks_held(void)
4307{
4308 if (unlikely(current->lockdep_depth > 0))
4309 print_held_locks_bug();
4310}
4311EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
4312
4313#ifdef __KERNEL__
4314void debug_show_all_locks(void)
4315{
4316 struct task_struct *g, *p;
4317 int count = 10;
4318 int unlock = 1;
4319
4320 if (unlikely(!debug_locks)) {
4321 printk("INFO: lockdep is turned off.\n");
4322 return;
4323 }
4324 printk("\nShowing all locks held in the system:\n");
4325
4326 /*
4327 * Here we try to get the tasklist_lock as hard as possible,
4328 * if not successful after 2 seconds we ignore it (but keep
4329 * trying). This is to enable a debug printout even if a
4330 * tasklist_lock-holding task deadlocks or crashes.
4331 */
4332retry:
4333 if (!read_trylock(&tasklist_lock)) {
4334 if (count == 10)
4335 printk("hm, tasklist_lock locked, retrying... ");
4336 if (count) {
4337 count--;
4338 printk(" #%d", 10-count);
4339 mdelay(200);
4340 goto retry;
4341 }
4342 printk(" ignoring it.\n");
4343 unlock = 0;
4344 } else {
4345 if (count != 10)
4346 printk(KERN_CONT " locked it.\n");
4347 }
4348
4349 do_each_thread(g, p) {
4350 /*
4351 * It's not reliable to print a task's held locks
4352 * if it's not sleeping (or if it's not the current
4353 * task):
4354 */
4355 if (p->state == TASK_RUNNING && p != current)
4356 continue;
4357 if (p->lockdep_depth)
4358 lockdep_print_held_locks(p);
4359 if (!unlock)
4360 if (read_trylock(&tasklist_lock))
4361 unlock = 1;
4362 } while_each_thread(g, p);
4363
4364 printk("\n");
4365 printk("=============================================\n\n");
4366
4367 if (unlock)
4368 read_unlock(&tasklist_lock);
4369}
4370EXPORT_SYMBOL_GPL(debug_show_all_locks);
4371#endif
4372
4373/*
4374 * Careful: only use this function if you are sure that
4375 * the task cannot run in parallel!
4376 */
4377void debug_show_held_locks(struct task_struct *task)
4378{
4379 if (unlikely(!debug_locks)) {
4380 printk("INFO: lockdep is turned off.\n");
4381 return;
4382 }
4383 lockdep_print_held_locks(task);
4384}
4385EXPORT_SYMBOL_GPL(debug_show_held_locks);
4386
4387asmlinkage __visible void lockdep_sys_exit(void)
4388{
4389 struct task_struct *curr = current;
4390
4391 if (unlikely(curr->lockdep_depth)) {
4392 if (!debug_locks_off())
4393 return;
4394 printk("\n");
4395 printk("================================================\n");
4396 printk("[ BUG: lock held when returning to user space! ]\n");
4397 print_kernel_ident();
4398 printk("------------------------------------------------\n");
4399 printk("%s/%d is leaving the kernel with locks still held!\n",
4400 curr->comm, curr->pid);
4401 lockdep_print_held_locks(curr);
4402 }
4403}
4404
4405void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4406{
4407 struct task_struct *curr = current;
4408
4409#ifndef CONFIG_PROVE_RCU_REPEATEDLY
4410 if (!debug_locks_off())
4411 return;
4412#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4413 /* Note: the following can be executed concurrently, so be careful. */
4414 printk("\n");
4415 printk("===============================\n");
4416 printk("[ INFO: suspicious RCU usage. ]\n");
4417 print_kernel_ident();
4418 printk("-------------------------------\n");
4419 printk("%s:%d %s!\n", file, line, s);
4420 printk("\nother info that might help us debug this:\n\n");
4421 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4422 !rcu_lockdep_current_cpu_online()
4423 ? "RCU used illegally from offline CPU!\n"
4424 : !rcu_is_watching()
4425 ? "RCU used illegally from idle CPU!\n"
4426 : "",
4427 rcu_scheduler_active, debug_locks);
4428
4429 /*
4430 * If a CPU is in the RCU-free window in idle (ie: in the section
4431 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4432 * considers that CPU to be in an "extended quiescent state",
4433 * which means that RCU will be completely ignoring that CPU.
4434 * Therefore, rcu_read_lock() and friends have absolutely no
4435 * effect on a CPU running in that state. In other words, even if
4436 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4437 * delete data structures out from under it. RCU really has no
4438 * choice here: we need to keep an RCU-free window in idle where
4439 * the CPU may possibly enter into low power mode. This way we can
4440 * notice an extended quiescent state to other CPUs that started a grace
4441 * period. Otherwise we would delay any grace period as long as we run
4442 * in the idle task.
4443 *
4444 * So complain bitterly if someone does call rcu_read_lock(),
4445 * rcu_read_lock_bh() and so on from extended quiescent states.
4446 */
4447 if (!rcu_is_watching())
4448 printk("RCU used illegally from extended quiescent state!\n");
4449
4450 lockdep_print_held_locks(curr);
4451 printk("\nstack backtrace:\n");
4452 dump_stack();
4453}
4454EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
1/*
2 * kernel/lockdep.c
3 *
4 * Runtime locking correctness validator
5 *
6 * Started by Ingo Molnar:
7 *
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
10 *
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
13 *
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
17 *
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
20 *
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
24 *
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
27 */
28#define DISABLE_BRANCH_PROFILING
29#include <linux/mutex.h>
30#include <linux/sched.h>
31#include <linux/delay.h>
32#include <linux/module.h>
33#include <linux/proc_fs.h>
34#include <linux/seq_file.h>
35#include <linux/spinlock.h>
36#include <linux/kallsyms.h>
37#include <linux/interrupt.h>
38#include <linux/stacktrace.h>
39#include <linux/debug_locks.h>
40#include <linux/irqflags.h>
41#include <linux/utsname.h>
42#include <linux/hash.h>
43#include <linux/ftrace.h>
44#include <linux/stringify.h>
45#include <linux/bitops.h>
46#include <linux/gfp.h>
47#include <linux/kmemcheck.h>
48
49#include <asm/sections.h>
50
51#include "lockdep_internals.h"
52
53#define CREATE_TRACE_POINTS
54#include <trace/events/lock.h>
55
56#ifdef CONFIG_PROVE_LOCKING
57int prove_locking = 1;
58module_param(prove_locking, int, 0644);
59#else
60#define prove_locking 0
61#endif
62
63#ifdef CONFIG_LOCK_STAT
64int lock_stat = 1;
65module_param(lock_stat, int, 0644);
66#else
67#define lock_stat 0
68#endif
69
70/*
71 * lockdep_lock: protects the lockdep graph, the hashes and the
72 * class/list/hash allocators.
73 *
74 * This is one of the rare exceptions where it's justified
75 * to use a raw spinlock - we really dont want the spinlock
76 * code to recurse back into the lockdep code...
77 */
78static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
79
80static int graph_lock(void)
81{
82 arch_spin_lock(&lockdep_lock);
83 /*
84 * Make sure that if another CPU detected a bug while
85 * walking the graph we dont change it (while the other
86 * CPU is busy printing out stuff with the graph lock
87 * dropped already)
88 */
89 if (!debug_locks) {
90 arch_spin_unlock(&lockdep_lock);
91 return 0;
92 }
93 /* prevent any recursions within lockdep from causing deadlocks */
94 current->lockdep_recursion++;
95 return 1;
96}
97
98static inline int graph_unlock(void)
99{
100 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
101 /*
102 * The lockdep graph lock isn't locked while we expect it to
103 * be, we're confused now, bye!
104 */
105 return DEBUG_LOCKS_WARN_ON(1);
106 }
107
108 current->lockdep_recursion--;
109 arch_spin_unlock(&lockdep_lock);
110 return 0;
111}
112
113/*
114 * Turn lock debugging off and return with 0 if it was off already,
115 * and also release the graph lock:
116 */
117static inline int debug_locks_off_graph_unlock(void)
118{
119 int ret = debug_locks_off();
120
121 arch_spin_unlock(&lockdep_lock);
122
123 return ret;
124}
125
126unsigned long nr_list_entries;
127static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
128
129/*
130 * All data structures here are protected by the global debug_lock.
131 *
132 * Mutex key structs only get allocated, once during bootup, and never
133 * get freed - this significantly simplifies the debugging code.
134 */
135unsigned long nr_lock_classes;
136static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
137
138static inline struct lock_class *hlock_class(struct held_lock *hlock)
139{
140 if (!hlock->class_idx) {
141 /*
142 * Someone passed in garbage, we give up.
143 */
144 DEBUG_LOCKS_WARN_ON(1);
145 return NULL;
146 }
147 return lock_classes + hlock->class_idx - 1;
148}
149
150#ifdef CONFIG_LOCK_STAT
151static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
152
153static inline u64 lockstat_clock(void)
154{
155 return local_clock();
156}
157
158static int lock_point(unsigned long points[], unsigned long ip)
159{
160 int i;
161
162 for (i = 0; i < LOCKSTAT_POINTS; i++) {
163 if (points[i] == 0) {
164 points[i] = ip;
165 break;
166 }
167 if (points[i] == ip)
168 break;
169 }
170
171 return i;
172}
173
174static void lock_time_inc(struct lock_time *lt, u64 time)
175{
176 if (time > lt->max)
177 lt->max = time;
178
179 if (time < lt->min || !lt->nr)
180 lt->min = time;
181
182 lt->total += time;
183 lt->nr++;
184}
185
186static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
187{
188 if (!src->nr)
189 return;
190
191 if (src->max > dst->max)
192 dst->max = src->max;
193
194 if (src->min < dst->min || !dst->nr)
195 dst->min = src->min;
196
197 dst->total += src->total;
198 dst->nr += src->nr;
199}
200
201struct lock_class_stats lock_stats(struct lock_class *class)
202{
203 struct lock_class_stats stats;
204 int cpu, i;
205
206 memset(&stats, 0, sizeof(struct lock_class_stats));
207 for_each_possible_cpu(cpu) {
208 struct lock_class_stats *pcs =
209 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
210
211 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
212 stats.contention_point[i] += pcs->contention_point[i];
213
214 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
215 stats.contending_point[i] += pcs->contending_point[i];
216
217 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
218 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
219
220 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
221 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
222
223 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
224 stats.bounces[i] += pcs->bounces[i];
225 }
226
227 return stats;
228}
229
230void clear_lock_stats(struct lock_class *class)
231{
232 int cpu;
233
234 for_each_possible_cpu(cpu) {
235 struct lock_class_stats *cpu_stats =
236 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
237
238 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
239 }
240 memset(class->contention_point, 0, sizeof(class->contention_point));
241 memset(class->contending_point, 0, sizeof(class->contending_point));
242}
243
244static struct lock_class_stats *get_lock_stats(struct lock_class *class)
245{
246 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
247}
248
249static void put_lock_stats(struct lock_class_stats *stats)
250{
251 put_cpu_var(cpu_lock_stats);
252}
253
254static void lock_release_holdtime(struct held_lock *hlock)
255{
256 struct lock_class_stats *stats;
257 u64 holdtime;
258
259 if (!lock_stat)
260 return;
261
262 holdtime = lockstat_clock() - hlock->holdtime_stamp;
263
264 stats = get_lock_stats(hlock_class(hlock));
265 if (hlock->read)
266 lock_time_inc(&stats->read_holdtime, holdtime);
267 else
268 lock_time_inc(&stats->write_holdtime, holdtime);
269 put_lock_stats(stats);
270}
271#else
272static inline void lock_release_holdtime(struct held_lock *hlock)
273{
274}
275#endif
276
277/*
278 * We keep a global list of all lock classes. The list only grows,
279 * never shrinks. The list is only accessed with the lockdep
280 * spinlock lock held.
281 */
282LIST_HEAD(all_lock_classes);
283
284/*
285 * The lockdep classes are in a hash-table as well, for fast lookup:
286 */
287#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
288#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
289#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
290#define classhashentry(key) (classhash_table + __classhashfn((key)))
291
292static struct hlist_head classhash_table[CLASSHASH_SIZE];
293
294/*
295 * We put the lock dependency chains into a hash-table as well, to cache
296 * their existence:
297 */
298#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
299#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
300#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
301#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
302
303static struct hlist_head chainhash_table[CHAINHASH_SIZE];
304
305/*
306 * The hash key of the lock dependency chains is a hash itself too:
307 * it's a hash of all locks taken up to that lock, including that lock.
308 * It's a 64-bit hash, because it's important for the keys to be
309 * unique.
310 */
311#define iterate_chain_key(key1, key2) \
312 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
313 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
314 (key2))
315
316void lockdep_off(void)
317{
318 current->lockdep_recursion++;
319}
320EXPORT_SYMBOL(lockdep_off);
321
322void lockdep_on(void)
323{
324 current->lockdep_recursion--;
325}
326EXPORT_SYMBOL(lockdep_on);
327
328/*
329 * Debugging switches:
330 */
331
332#define VERBOSE 0
333#define VERY_VERBOSE 0
334
335#if VERBOSE
336# define HARDIRQ_VERBOSE 1
337# define SOFTIRQ_VERBOSE 1
338# define RECLAIM_VERBOSE 1
339#else
340# define HARDIRQ_VERBOSE 0
341# define SOFTIRQ_VERBOSE 0
342# define RECLAIM_VERBOSE 0
343#endif
344
345#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
346/*
347 * Quick filtering for interesting events:
348 */
349static int class_filter(struct lock_class *class)
350{
351#if 0
352 /* Example */
353 if (class->name_version == 1 &&
354 !strcmp(class->name, "lockname"))
355 return 1;
356 if (class->name_version == 1 &&
357 !strcmp(class->name, "&struct->lockfield"))
358 return 1;
359#endif
360 /* Filter everything else. 1 would be to allow everything else */
361 return 0;
362}
363#endif
364
365static int verbose(struct lock_class *class)
366{
367#if VERBOSE
368 return class_filter(class);
369#endif
370 return 0;
371}
372
373/*
374 * Stack-trace: tightly packed array of stack backtrace
375 * addresses. Protected by the graph_lock.
376 */
377unsigned long nr_stack_trace_entries;
378static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
379
380static void print_lockdep_off(const char *bug_msg)
381{
382 printk(KERN_DEBUG "%s\n", bug_msg);
383 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
384#ifdef CONFIG_LOCK_STAT
385 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
386#endif
387}
388
389static int save_trace(struct stack_trace *trace)
390{
391 trace->nr_entries = 0;
392 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
393 trace->entries = stack_trace + nr_stack_trace_entries;
394
395 trace->skip = 3;
396
397 save_stack_trace(trace);
398
399 /*
400 * Some daft arches put -1 at the end to indicate its a full trace.
401 *
402 * <rant> this is buggy anyway, since it takes a whole extra entry so a
403 * complete trace that maxes out the entries provided will be reported
404 * as incomplete, friggin useless </rant>
405 */
406 if (trace->nr_entries != 0 &&
407 trace->entries[trace->nr_entries-1] == ULONG_MAX)
408 trace->nr_entries--;
409
410 trace->max_entries = trace->nr_entries;
411
412 nr_stack_trace_entries += trace->nr_entries;
413
414 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
415 if (!debug_locks_off_graph_unlock())
416 return 0;
417
418 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
419 dump_stack();
420
421 return 0;
422 }
423
424 return 1;
425}
426
427unsigned int nr_hardirq_chains;
428unsigned int nr_softirq_chains;
429unsigned int nr_process_chains;
430unsigned int max_lockdep_depth;
431
432#ifdef CONFIG_DEBUG_LOCKDEP
433/*
434 * Various lockdep statistics:
435 */
436DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
437#endif
438
439/*
440 * Locking printouts:
441 */
442
443#define __USAGE(__STATE) \
444 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
445 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
446 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
447 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
448
449static const char *usage_str[] =
450{
451#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
452#include "lockdep_states.h"
453#undef LOCKDEP_STATE
454 [LOCK_USED] = "INITIAL USE",
455};
456
457const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
458{
459 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
460}
461
462static inline unsigned long lock_flag(enum lock_usage_bit bit)
463{
464 return 1UL << bit;
465}
466
467static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
468{
469 char c = '.';
470
471 if (class->usage_mask & lock_flag(bit + 2))
472 c = '+';
473 if (class->usage_mask & lock_flag(bit)) {
474 c = '-';
475 if (class->usage_mask & lock_flag(bit + 2))
476 c = '?';
477 }
478
479 return c;
480}
481
482void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
483{
484 int i = 0;
485
486#define LOCKDEP_STATE(__STATE) \
487 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
488 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
489#include "lockdep_states.h"
490#undef LOCKDEP_STATE
491
492 usage[i] = '\0';
493}
494
495static void __print_lock_name(struct lock_class *class)
496{
497 char str[KSYM_NAME_LEN];
498 const char *name;
499
500 name = class->name;
501 if (!name) {
502 name = __get_key_name(class->key, str);
503 printk("%s", name);
504 } else {
505 printk("%s", name);
506 if (class->name_version > 1)
507 printk("#%d", class->name_version);
508 if (class->subclass)
509 printk("/%d", class->subclass);
510 }
511}
512
513static void print_lock_name(struct lock_class *class)
514{
515 char usage[LOCK_USAGE_CHARS];
516
517 get_usage_chars(class, usage);
518
519 printk(" (");
520 __print_lock_name(class);
521 printk("){%s}", usage);
522}
523
524static void print_lockdep_cache(struct lockdep_map *lock)
525{
526 const char *name;
527 char str[KSYM_NAME_LEN];
528
529 name = lock->name;
530 if (!name)
531 name = __get_key_name(lock->key->subkeys, str);
532
533 printk("%s", name);
534}
535
536static void print_lock(struct held_lock *hlock)
537{
538 /*
539 * We can be called locklessly through debug_show_all_locks() so be
540 * extra careful, the hlock might have been released and cleared.
541 */
542 unsigned int class_idx = hlock->class_idx;
543
544 /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
545 barrier();
546
547 if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
548 printk("<RELEASED>\n");
549 return;
550 }
551
552 print_lock_name(lock_classes + class_idx - 1);
553 printk(", at: ");
554 print_ip_sym(hlock->acquire_ip);
555}
556
557static void lockdep_print_held_locks(struct task_struct *curr)
558{
559 int i, depth = curr->lockdep_depth;
560
561 if (!depth) {
562 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
563 return;
564 }
565 printk("%d lock%s held by %s/%d:\n",
566 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
567
568 for (i = 0; i < depth; i++) {
569 printk(" #%d: ", i);
570 print_lock(curr->held_locks + i);
571 }
572}
573
574static void print_kernel_ident(void)
575{
576 printk("%s %.*s %s\n", init_utsname()->release,
577 (int)strcspn(init_utsname()->version, " "),
578 init_utsname()->version,
579 print_tainted());
580}
581
582static int very_verbose(struct lock_class *class)
583{
584#if VERY_VERBOSE
585 return class_filter(class);
586#endif
587 return 0;
588}
589
590/*
591 * Is this the address of a static object:
592 */
593#ifdef __KERNEL__
594static int static_obj(void *obj)
595{
596 unsigned long start = (unsigned long) &_stext,
597 end = (unsigned long) &_end,
598 addr = (unsigned long) obj;
599
600 /*
601 * static variable?
602 */
603 if ((addr >= start) && (addr < end))
604 return 1;
605
606 if (arch_is_kernel_data(addr))
607 return 1;
608
609 /*
610 * in-kernel percpu var?
611 */
612 if (is_kernel_percpu_address(addr))
613 return 1;
614
615 /*
616 * module static or percpu var?
617 */
618 return is_module_address(addr) || is_module_percpu_address(addr);
619}
620#endif
621
622/*
623 * To make lock name printouts unique, we calculate a unique
624 * class->name_version generation counter:
625 */
626static int count_matching_names(struct lock_class *new_class)
627{
628 struct lock_class *class;
629 int count = 0;
630
631 if (!new_class->name)
632 return 0;
633
634 list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
635 if (new_class->key - new_class->subclass == class->key)
636 return class->name_version;
637 if (class->name && !strcmp(class->name, new_class->name))
638 count = max(count, class->name_version);
639 }
640
641 return count + 1;
642}
643
644/*
645 * Register a lock's class in the hash-table, if the class is not present
646 * yet. Otherwise we look it up. We cache the result in the lock object
647 * itself, so actual lookup of the hash should be once per lock object.
648 */
649static inline struct lock_class *
650look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
651{
652 struct lockdep_subclass_key *key;
653 struct hlist_head *hash_head;
654 struct lock_class *class;
655
656 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
657 debug_locks_off();
658 printk(KERN_ERR
659 "BUG: looking up invalid subclass: %u\n", subclass);
660 printk(KERN_ERR
661 "turning off the locking correctness validator.\n");
662 dump_stack();
663 return NULL;
664 }
665
666 /*
667 * Static locks do not have their class-keys yet - for them the key
668 * is the lock object itself:
669 */
670 if (unlikely(!lock->key))
671 lock->key = (void *)lock;
672
673 /*
674 * NOTE: the class-key must be unique. For dynamic locks, a static
675 * lock_class_key variable is passed in through the mutex_init()
676 * (or spin_lock_init()) call - which acts as the key. For static
677 * locks we use the lock object itself as the key.
678 */
679 BUILD_BUG_ON(sizeof(struct lock_class_key) >
680 sizeof(struct lockdep_map));
681
682 key = lock->key->subkeys + subclass;
683
684 hash_head = classhashentry(key);
685
686 /*
687 * We do an RCU walk of the hash, see lockdep_free_key_range().
688 */
689 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
690 return NULL;
691
692 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
693 if (class->key == key) {
694 /*
695 * Huh! same key, different name? Did someone trample
696 * on some memory? We're most confused.
697 */
698 WARN_ON_ONCE(class->name != lock->name);
699 return class;
700 }
701 }
702
703 return NULL;
704}
705
706/*
707 * Register a lock's class in the hash-table, if the class is not present
708 * yet. Otherwise we look it up. We cache the result in the lock object
709 * itself, so actual lookup of the hash should be once per lock object.
710 */
711static inline struct lock_class *
712register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
713{
714 struct lockdep_subclass_key *key;
715 struct hlist_head *hash_head;
716 struct lock_class *class;
717
718 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
719
720 class = look_up_lock_class(lock, subclass);
721 if (likely(class))
722 goto out_set_class_cache;
723
724 /*
725 * Debug-check: all keys must be persistent!
726 */
727 if (!static_obj(lock->key)) {
728 debug_locks_off();
729 printk("INFO: trying to register non-static key.\n");
730 printk("the code is fine but needs lockdep annotation.\n");
731 printk("turning off the locking correctness validator.\n");
732 dump_stack();
733
734 return NULL;
735 }
736
737 key = lock->key->subkeys + subclass;
738 hash_head = classhashentry(key);
739
740 if (!graph_lock()) {
741 return NULL;
742 }
743 /*
744 * We have to do the hash-walk again, to avoid races
745 * with another CPU:
746 */
747 hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
748 if (class->key == key)
749 goto out_unlock_set;
750 }
751
752 /*
753 * Allocate a new key from the static array, and add it to
754 * the hash:
755 */
756 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
757 if (!debug_locks_off_graph_unlock()) {
758 return NULL;
759 }
760
761 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
762 dump_stack();
763 return NULL;
764 }
765 class = lock_classes + nr_lock_classes++;
766 debug_atomic_inc(nr_unused_locks);
767 class->key = key;
768 class->name = lock->name;
769 class->subclass = subclass;
770 INIT_LIST_HEAD(&class->lock_entry);
771 INIT_LIST_HEAD(&class->locks_before);
772 INIT_LIST_HEAD(&class->locks_after);
773 class->name_version = count_matching_names(class);
774 /*
775 * We use RCU's safe list-add method to make
776 * parallel walking of the hash-list safe:
777 */
778 hlist_add_head_rcu(&class->hash_entry, hash_head);
779 /*
780 * Add it to the global list of classes:
781 */
782 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
783
784 if (verbose(class)) {
785 graph_unlock();
786
787 printk("\nnew class %p: %s", class->key, class->name);
788 if (class->name_version > 1)
789 printk("#%d", class->name_version);
790 printk("\n");
791 dump_stack();
792
793 if (!graph_lock()) {
794 return NULL;
795 }
796 }
797out_unlock_set:
798 graph_unlock();
799
800out_set_class_cache:
801 if (!subclass || force)
802 lock->class_cache[0] = class;
803 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
804 lock->class_cache[subclass] = class;
805
806 /*
807 * Hash collision, did we smoke some? We found a class with a matching
808 * hash but the subclass -- which is hashed in -- didn't match.
809 */
810 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
811 return NULL;
812
813 return class;
814}
815
816#ifdef CONFIG_PROVE_LOCKING
817/*
818 * Allocate a lockdep entry. (assumes the graph_lock held, returns
819 * with NULL on failure)
820 */
821static struct lock_list *alloc_list_entry(void)
822{
823 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
824 if (!debug_locks_off_graph_unlock())
825 return NULL;
826
827 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
828 dump_stack();
829 return NULL;
830 }
831 return list_entries + nr_list_entries++;
832}
833
834/*
835 * Add a new dependency to the head of the list:
836 */
837static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
838 struct list_head *head, unsigned long ip,
839 int distance, struct stack_trace *trace)
840{
841 struct lock_list *entry;
842 /*
843 * Lock not present yet - get a new dependency struct and
844 * add it to the list:
845 */
846 entry = alloc_list_entry();
847 if (!entry)
848 return 0;
849
850 entry->class = this;
851 entry->distance = distance;
852 entry->trace = *trace;
853 /*
854 * Both allocation and removal are done under the graph lock; but
855 * iteration is under RCU-sched; see look_up_lock_class() and
856 * lockdep_free_key_range().
857 */
858 list_add_tail_rcu(&entry->entry, head);
859
860 return 1;
861}
862
863/*
864 * For good efficiency of modular, we use power of 2
865 */
866#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
867#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
868
869/*
870 * The circular_queue and helpers is used to implement the
871 * breadth-first search(BFS)algorithem, by which we can build
872 * the shortest path from the next lock to be acquired to the
873 * previous held lock if there is a circular between them.
874 */
875struct circular_queue {
876 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
877 unsigned int front, rear;
878};
879
880static struct circular_queue lock_cq;
881
882unsigned int max_bfs_queue_depth;
883
884static unsigned int lockdep_dependency_gen_id;
885
886static inline void __cq_init(struct circular_queue *cq)
887{
888 cq->front = cq->rear = 0;
889 lockdep_dependency_gen_id++;
890}
891
892static inline int __cq_empty(struct circular_queue *cq)
893{
894 return (cq->front == cq->rear);
895}
896
897static inline int __cq_full(struct circular_queue *cq)
898{
899 return ((cq->rear + 1) & CQ_MASK) == cq->front;
900}
901
902static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
903{
904 if (__cq_full(cq))
905 return -1;
906
907 cq->element[cq->rear] = elem;
908 cq->rear = (cq->rear + 1) & CQ_MASK;
909 return 0;
910}
911
912static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
913{
914 if (__cq_empty(cq))
915 return -1;
916
917 *elem = cq->element[cq->front];
918 cq->front = (cq->front + 1) & CQ_MASK;
919 return 0;
920}
921
922static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
923{
924 return (cq->rear - cq->front) & CQ_MASK;
925}
926
927static inline void mark_lock_accessed(struct lock_list *lock,
928 struct lock_list *parent)
929{
930 unsigned long nr;
931
932 nr = lock - list_entries;
933 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
934 lock->parent = parent;
935 lock->class->dep_gen_id = lockdep_dependency_gen_id;
936}
937
938static inline unsigned long lock_accessed(struct lock_list *lock)
939{
940 unsigned long nr;
941
942 nr = lock - list_entries;
943 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
944 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
945}
946
947static inline struct lock_list *get_lock_parent(struct lock_list *child)
948{
949 return child->parent;
950}
951
952static inline int get_lock_depth(struct lock_list *child)
953{
954 int depth = 0;
955 struct lock_list *parent;
956
957 while ((parent = get_lock_parent(child))) {
958 child = parent;
959 depth++;
960 }
961 return depth;
962}
963
964static int __bfs(struct lock_list *source_entry,
965 void *data,
966 int (*match)(struct lock_list *entry, void *data),
967 struct lock_list **target_entry,
968 int forward)
969{
970 struct lock_list *entry;
971 struct list_head *head;
972 struct circular_queue *cq = &lock_cq;
973 int ret = 1;
974
975 if (match(source_entry, data)) {
976 *target_entry = source_entry;
977 ret = 0;
978 goto exit;
979 }
980
981 if (forward)
982 head = &source_entry->class->locks_after;
983 else
984 head = &source_entry->class->locks_before;
985
986 if (list_empty(head))
987 goto exit;
988
989 __cq_init(cq);
990 __cq_enqueue(cq, (unsigned long)source_entry);
991
992 while (!__cq_empty(cq)) {
993 struct lock_list *lock;
994
995 __cq_dequeue(cq, (unsigned long *)&lock);
996
997 if (!lock->class) {
998 ret = -2;
999 goto exit;
1000 }
1001
1002 if (forward)
1003 head = &lock->class->locks_after;
1004 else
1005 head = &lock->class->locks_before;
1006
1007 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1008
1009 list_for_each_entry_rcu(entry, head, entry) {
1010 if (!lock_accessed(entry)) {
1011 unsigned int cq_depth;
1012 mark_lock_accessed(entry, lock);
1013 if (match(entry, data)) {
1014 *target_entry = entry;
1015 ret = 0;
1016 goto exit;
1017 }
1018
1019 if (__cq_enqueue(cq, (unsigned long)entry)) {
1020 ret = -1;
1021 goto exit;
1022 }
1023 cq_depth = __cq_get_elem_count(cq);
1024 if (max_bfs_queue_depth < cq_depth)
1025 max_bfs_queue_depth = cq_depth;
1026 }
1027 }
1028 }
1029exit:
1030 return ret;
1031}
1032
1033static inline int __bfs_forwards(struct lock_list *src_entry,
1034 void *data,
1035 int (*match)(struct lock_list *entry, void *data),
1036 struct lock_list **target_entry)
1037{
1038 return __bfs(src_entry, data, match, target_entry, 1);
1039
1040}
1041
1042static inline int __bfs_backwards(struct lock_list *src_entry,
1043 void *data,
1044 int (*match)(struct lock_list *entry, void *data),
1045 struct lock_list **target_entry)
1046{
1047 return __bfs(src_entry, data, match, target_entry, 0);
1048
1049}
1050
1051/*
1052 * Recursive, forwards-direction lock-dependency checking, used for
1053 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1054 * checking.
1055 */
1056
1057/*
1058 * Print a dependency chain entry (this is only done when a deadlock
1059 * has been detected):
1060 */
1061static noinline int
1062print_circular_bug_entry(struct lock_list *target, int depth)
1063{
1064 if (debug_locks_silent)
1065 return 0;
1066 printk("\n-> #%u", depth);
1067 print_lock_name(target->class);
1068 printk(":\n");
1069 print_stack_trace(&target->trace, 6);
1070
1071 return 0;
1072}
1073
1074static void
1075print_circular_lock_scenario(struct held_lock *src,
1076 struct held_lock *tgt,
1077 struct lock_list *prt)
1078{
1079 struct lock_class *source = hlock_class(src);
1080 struct lock_class *target = hlock_class(tgt);
1081 struct lock_class *parent = prt->class;
1082
1083 /*
1084 * A direct locking problem where unsafe_class lock is taken
1085 * directly by safe_class lock, then all we need to show
1086 * is the deadlock scenario, as it is obvious that the
1087 * unsafe lock is taken under the safe lock.
1088 *
1089 * But if there is a chain instead, where the safe lock takes
1090 * an intermediate lock (middle_class) where this lock is
1091 * not the same as the safe lock, then the lock chain is
1092 * used to describe the problem. Otherwise we would need
1093 * to show a different CPU case for each link in the chain
1094 * from the safe_class lock to the unsafe_class lock.
1095 */
1096 if (parent != source) {
1097 printk("Chain exists of:\n ");
1098 __print_lock_name(source);
1099 printk(" --> ");
1100 __print_lock_name(parent);
1101 printk(" --> ");
1102 __print_lock_name(target);
1103 printk("\n\n");
1104 }
1105
1106 printk(" Possible unsafe locking scenario:\n\n");
1107 printk(" CPU0 CPU1\n");
1108 printk(" ---- ----\n");
1109 printk(" lock(");
1110 __print_lock_name(target);
1111 printk(");\n");
1112 printk(" lock(");
1113 __print_lock_name(parent);
1114 printk(");\n");
1115 printk(" lock(");
1116 __print_lock_name(target);
1117 printk(");\n");
1118 printk(" lock(");
1119 __print_lock_name(source);
1120 printk(");\n");
1121 printk("\n *** DEADLOCK ***\n\n");
1122}
1123
1124/*
1125 * When a circular dependency is detected, print the
1126 * header first:
1127 */
1128static noinline int
1129print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1130 struct held_lock *check_src,
1131 struct held_lock *check_tgt)
1132{
1133 struct task_struct *curr = current;
1134
1135 if (debug_locks_silent)
1136 return 0;
1137
1138 printk("\n");
1139 printk("======================================================\n");
1140 printk("[ INFO: possible circular locking dependency detected ]\n");
1141 print_kernel_ident();
1142 printk("-------------------------------------------------------\n");
1143 printk("%s/%d is trying to acquire lock:\n",
1144 curr->comm, task_pid_nr(curr));
1145 print_lock(check_src);
1146 printk("\nbut task is already holding lock:\n");
1147 print_lock(check_tgt);
1148 printk("\nwhich lock already depends on the new lock.\n\n");
1149 printk("\nthe existing dependency chain (in reverse order) is:\n");
1150
1151 print_circular_bug_entry(entry, depth);
1152
1153 return 0;
1154}
1155
1156static inline int class_equal(struct lock_list *entry, void *data)
1157{
1158 return entry->class == data;
1159}
1160
1161static noinline int print_circular_bug(struct lock_list *this,
1162 struct lock_list *target,
1163 struct held_lock *check_src,
1164 struct held_lock *check_tgt)
1165{
1166 struct task_struct *curr = current;
1167 struct lock_list *parent;
1168 struct lock_list *first_parent;
1169 int depth;
1170
1171 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1172 return 0;
1173
1174 if (!save_trace(&this->trace))
1175 return 0;
1176
1177 depth = get_lock_depth(target);
1178
1179 print_circular_bug_header(target, depth, check_src, check_tgt);
1180
1181 parent = get_lock_parent(target);
1182 first_parent = parent;
1183
1184 while (parent) {
1185 print_circular_bug_entry(parent, --depth);
1186 parent = get_lock_parent(parent);
1187 }
1188
1189 printk("\nother info that might help us debug this:\n\n");
1190 print_circular_lock_scenario(check_src, check_tgt,
1191 first_parent);
1192
1193 lockdep_print_held_locks(curr);
1194
1195 printk("\nstack backtrace:\n");
1196 dump_stack();
1197
1198 return 0;
1199}
1200
1201static noinline int print_bfs_bug(int ret)
1202{
1203 if (!debug_locks_off_graph_unlock())
1204 return 0;
1205
1206 /*
1207 * Breadth-first-search failed, graph got corrupted?
1208 */
1209 WARN(1, "lockdep bfs error:%d\n", ret);
1210
1211 return 0;
1212}
1213
1214static int noop_count(struct lock_list *entry, void *data)
1215{
1216 (*(unsigned long *)data)++;
1217 return 0;
1218}
1219
1220static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1221{
1222 unsigned long count = 0;
1223 struct lock_list *uninitialized_var(target_entry);
1224
1225 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1226
1227 return count;
1228}
1229unsigned long lockdep_count_forward_deps(struct lock_class *class)
1230{
1231 unsigned long ret, flags;
1232 struct lock_list this;
1233
1234 this.parent = NULL;
1235 this.class = class;
1236
1237 local_irq_save(flags);
1238 arch_spin_lock(&lockdep_lock);
1239 ret = __lockdep_count_forward_deps(&this);
1240 arch_spin_unlock(&lockdep_lock);
1241 local_irq_restore(flags);
1242
1243 return ret;
1244}
1245
1246static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1247{
1248 unsigned long count = 0;
1249 struct lock_list *uninitialized_var(target_entry);
1250
1251 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1252
1253 return count;
1254}
1255
1256unsigned long lockdep_count_backward_deps(struct lock_class *class)
1257{
1258 unsigned long ret, flags;
1259 struct lock_list this;
1260
1261 this.parent = NULL;
1262 this.class = class;
1263
1264 local_irq_save(flags);
1265 arch_spin_lock(&lockdep_lock);
1266 ret = __lockdep_count_backward_deps(&this);
1267 arch_spin_unlock(&lockdep_lock);
1268 local_irq_restore(flags);
1269
1270 return ret;
1271}
1272
1273/*
1274 * Prove that the dependency graph starting at <entry> can not
1275 * lead to <target>. Print an error and return 0 if it does.
1276 */
1277static noinline int
1278check_noncircular(struct lock_list *root, struct lock_class *target,
1279 struct lock_list **target_entry)
1280{
1281 int result;
1282
1283 debug_atomic_inc(nr_cyclic_checks);
1284
1285 result = __bfs_forwards(root, target, class_equal, target_entry);
1286
1287 return result;
1288}
1289
1290#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1291/*
1292 * Forwards and backwards subgraph searching, for the purposes of
1293 * proving that two subgraphs can be connected by a new dependency
1294 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1295 */
1296
1297static inline int usage_match(struct lock_list *entry, void *bit)
1298{
1299 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1300}
1301
1302
1303
1304/*
1305 * Find a node in the forwards-direction dependency sub-graph starting
1306 * at @root->class that matches @bit.
1307 *
1308 * Return 0 if such a node exists in the subgraph, and put that node
1309 * into *@target_entry.
1310 *
1311 * Return 1 otherwise and keep *@target_entry unchanged.
1312 * Return <0 on error.
1313 */
1314static int
1315find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1316 struct lock_list **target_entry)
1317{
1318 int result;
1319
1320 debug_atomic_inc(nr_find_usage_forwards_checks);
1321
1322 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1323
1324 return result;
1325}
1326
1327/*
1328 * Find a node in the backwards-direction dependency sub-graph starting
1329 * at @root->class that matches @bit.
1330 *
1331 * Return 0 if such a node exists in the subgraph, and put that node
1332 * into *@target_entry.
1333 *
1334 * Return 1 otherwise and keep *@target_entry unchanged.
1335 * Return <0 on error.
1336 */
1337static int
1338find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1339 struct lock_list **target_entry)
1340{
1341 int result;
1342
1343 debug_atomic_inc(nr_find_usage_backwards_checks);
1344
1345 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1346
1347 return result;
1348}
1349
1350static void print_lock_class_header(struct lock_class *class, int depth)
1351{
1352 int bit;
1353
1354 printk("%*s->", depth, "");
1355 print_lock_name(class);
1356 printk(" ops: %lu", class->ops);
1357 printk(" {\n");
1358
1359 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1360 if (class->usage_mask & (1 << bit)) {
1361 int len = depth;
1362
1363 len += printk("%*s %s", depth, "", usage_str[bit]);
1364 len += printk(" at:\n");
1365 print_stack_trace(class->usage_traces + bit, len);
1366 }
1367 }
1368 printk("%*s }\n", depth, "");
1369
1370 printk("%*s ... key at: ",depth,"");
1371 print_ip_sym((unsigned long)class->key);
1372}
1373
1374/*
1375 * printk the shortest lock dependencies from @start to @end in reverse order:
1376 */
1377static void __used
1378print_shortest_lock_dependencies(struct lock_list *leaf,
1379 struct lock_list *root)
1380{
1381 struct lock_list *entry = leaf;
1382 int depth;
1383
1384 /*compute depth from generated tree by BFS*/
1385 depth = get_lock_depth(leaf);
1386
1387 do {
1388 print_lock_class_header(entry->class, depth);
1389 printk("%*s ... acquired at:\n", depth, "");
1390 print_stack_trace(&entry->trace, 2);
1391 printk("\n");
1392
1393 if (depth == 0 && (entry != root)) {
1394 printk("lockdep:%s bad path found in chain graph\n", __func__);
1395 break;
1396 }
1397
1398 entry = get_lock_parent(entry);
1399 depth--;
1400 } while (entry && (depth >= 0));
1401
1402 return;
1403}
1404
1405static void
1406print_irq_lock_scenario(struct lock_list *safe_entry,
1407 struct lock_list *unsafe_entry,
1408 struct lock_class *prev_class,
1409 struct lock_class *next_class)
1410{
1411 struct lock_class *safe_class = safe_entry->class;
1412 struct lock_class *unsafe_class = unsafe_entry->class;
1413 struct lock_class *middle_class = prev_class;
1414
1415 if (middle_class == safe_class)
1416 middle_class = next_class;
1417
1418 /*
1419 * A direct locking problem where unsafe_class lock is taken
1420 * directly by safe_class lock, then all we need to show
1421 * is the deadlock scenario, as it is obvious that the
1422 * unsafe lock is taken under the safe lock.
1423 *
1424 * But if there is a chain instead, where the safe lock takes
1425 * an intermediate lock (middle_class) where this lock is
1426 * not the same as the safe lock, then the lock chain is
1427 * used to describe the problem. Otherwise we would need
1428 * to show a different CPU case for each link in the chain
1429 * from the safe_class lock to the unsafe_class lock.
1430 */
1431 if (middle_class != unsafe_class) {
1432 printk("Chain exists of:\n ");
1433 __print_lock_name(safe_class);
1434 printk(" --> ");
1435 __print_lock_name(middle_class);
1436 printk(" --> ");
1437 __print_lock_name(unsafe_class);
1438 printk("\n\n");
1439 }
1440
1441 printk(" Possible interrupt unsafe locking scenario:\n\n");
1442 printk(" CPU0 CPU1\n");
1443 printk(" ---- ----\n");
1444 printk(" lock(");
1445 __print_lock_name(unsafe_class);
1446 printk(");\n");
1447 printk(" local_irq_disable();\n");
1448 printk(" lock(");
1449 __print_lock_name(safe_class);
1450 printk(");\n");
1451 printk(" lock(");
1452 __print_lock_name(middle_class);
1453 printk(");\n");
1454 printk(" <Interrupt>\n");
1455 printk(" lock(");
1456 __print_lock_name(safe_class);
1457 printk(");\n");
1458 printk("\n *** DEADLOCK ***\n\n");
1459}
1460
1461static int
1462print_bad_irq_dependency(struct task_struct *curr,
1463 struct lock_list *prev_root,
1464 struct lock_list *next_root,
1465 struct lock_list *backwards_entry,
1466 struct lock_list *forwards_entry,
1467 struct held_lock *prev,
1468 struct held_lock *next,
1469 enum lock_usage_bit bit1,
1470 enum lock_usage_bit bit2,
1471 const char *irqclass)
1472{
1473 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1474 return 0;
1475
1476 printk("\n");
1477 printk("======================================================\n");
1478 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1479 irqclass, irqclass);
1480 print_kernel_ident();
1481 printk("------------------------------------------------------\n");
1482 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1483 curr->comm, task_pid_nr(curr),
1484 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1485 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1486 curr->hardirqs_enabled,
1487 curr->softirqs_enabled);
1488 print_lock(next);
1489
1490 printk("\nand this task is already holding:\n");
1491 print_lock(prev);
1492 printk("which would create a new lock dependency:\n");
1493 print_lock_name(hlock_class(prev));
1494 printk(" ->");
1495 print_lock_name(hlock_class(next));
1496 printk("\n");
1497
1498 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1499 irqclass);
1500 print_lock_name(backwards_entry->class);
1501 printk("\n... which became %s-irq-safe at:\n", irqclass);
1502
1503 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1504
1505 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1506 print_lock_name(forwards_entry->class);
1507 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1508 printk("...");
1509
1510 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1511
1512 printk("\nother info that might help us debug this:\n\n");
1513 print_irq_lock_scenario(backwards_entry, forwards_entry,
1514 hlock_class(prev), hlock_class(next));
1515
1516 lockdep_print_held_locks(curr);
1517
1518 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1519 printk(" and the holding lock:\n");
1520 if (!save_trace(&prev_root->trace))
1521 return 0;
1522 print_shortest_lock_dependencies(backwards_entry, prev_root);
1523
1524 printk("\nthe dependencies between the lock to be acquired");
1525 printk(" and %s-irq-unsafe lock:\n", irqclass);
1526 if (!save_trace(&next_root->trace))
1527 return 0;
1528 print_shortest_lock_dependencies(forwards_entry, next_root);
1529
1530 printk("\nstack backtrace:\n");
1531 dump_stack();
1532
1533 return 0;
1534}
1535
1536static int
1537check_usage(struct task_struct *curr, struct held_lock *prev,
1538 struct held_lock *next, enum lock_usage_bit bit_backwards,
1539 enum lock_usage_bit bit_forwards, const char *irqclass)
1540{
1541 int ret;
1542 struct lock_list this, that;
1543 struct lock_list *uninitialized_var(target_entry);
1544 struct lock_list *uninitialized_var(target_entry1);
1545
1546 this.parent = NULL;
1547
1548 this.class = hlock_class(prev);
1549 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1550 if (ret < 0)
1551 return print_bfs_bug(ret);
1552 if (ret == 1)
1553 return ret;
1554
1555 that.parent = NULL;
1556 that.class = hlock_class(next);
1557 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1558 if (ret < 0)
1559 return print_bfs_bug(ret);
1560 if (ret == 1)
1561 return ret;
1562
1563 return print_bad_irq_dependency(curr, &this, &that,
1564 target_entry, target_entry1,
1565 prev, next,
1566 bit_backwards, bit_forwards, irqclass);
1567}
1568
1569static const char *state_names[] = {
1570#define LOCKDEP_STATE(__STATE) \
1571 __stringify(__STATE),
1572#include "lockdep_states.h"
1573#undef LOCKDEP_STATE
1574};
1575
1576static const char *state_rnames[] = {
1577#define LOCKDEP_STATE(__STATE) \
1578 __stringify(__STATE)"-READ",
1579#include "lockdep_states.h"
1580#undef LOCKDEP_STATE
1581};
1582
1583static inline const char *state_name(enum lock_usage_bit bit)
1584{
1585 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1586}
1587
1588static int exclusive_bit(int new_bit)
1589{
1590 /*
1591 * USED_IN
1592 * USED_IN_READ
1593 * ENABLED
1594 * ENABLED_READ
1595 *
1596 * bit 0 - write/read
1597 * bit 1 - used_in/enabled
1598 * bit 2+ state
1599 */
1600
1601 int state = new_bit & ~3;
1602 int dir = new_bit & 2;
1603
1604 /*
1605 * keep state, bit flip the direction and strip read.
1606 */
1607 return state | (dir ^ 2);
1608}
1609
1610static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1611 struct held_lock *next, enum lock_usage_bit bit)
1612{
1613 /*
1614 * Prove that the new dependency does not connect a hardirq-safe
1615 * lock with a hardirq-unsafe lock - to achieve this we search
1616 * the backwards-subgraph starting at <prev>, and the
1617 * forwards-subgraph starting at <next>:
1618 */
1619 if (!check_usage(curr, prev, next, bit,
1620 exclusive_bit(bit), state_name(bit)))
1621 return 0;
1622
1623 bit++; /* _READ */
1624
1625 /*
1626 * Prove that the new dependency does not connect a hardirq-safe-read
1627 * lock with a hardirq-unsafe lock - to achieve this we search
1628 * the backwards-subgraph starting at <prev>, and the
1629 * forwards-subgraph starting at <next>:
1630 */
1631 if (!check_usage(curr, prev, next, bit,
1632 exclusive_bit(bit), state_name(bit)))
1633 return 0;
1634
1635 return 1;
1636}
1637
1638static int
1639check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1640 struct held_lock *next)
1641{
1642#define LOCKDEP_STATE(__STATE) \
1643 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1644 return 0;
1645#include "lockdep_states.h"
1646#undef LOCKDEP_STATE
1647
1648 return 1;
1649}
1650
1651static void inc_chains(void)
1652{
1653 if (current->hardirq_context)
1654 nr_hardirq_chains++;
1655 else {
1656 if (current->softirq_context)
1657 nr_softirq_chains++;
1658 else
1659 nr_process_chains++;
1660 }
1661}
1662
1663#else
1664
1665static inline int
1666check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1667 struct held_lock *next)
1668{
1669 return 1;
1670}
1671
1672static inline void inc_chains(void)
1673{
1674 nr_process_chains++;
1675}
1676
1677#endif
1678
1679static void
1680print_deadlock_scenario(struct held_lock *nxt,
1681 struct held_lock *prv)
1682{
1683 struct lock_class *next = hlock_class(nxt);
1684 struct lock_class *prev = hlock_class(prv);
1685
1686 printk(" Possible unsafe locking scenario:\n\n");
1687 printk(" CPU0\n");
1688 printk(" ----\n");
1689 printk(" lock(");
1690 __print_lock_name(prev);
1691 printk(");\n");
1692 printk(" lock(");
1693 __print_lock_name(next);
1694 printk(");\n");
1695 printk("\n *** DEADLOCK ***\n\n");
1696 printk(" May be due to missing lock nesting notation\n\n");
1697}
1698
1699static int
1700print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1701 struct held_lock *next)
1702{
1703 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1704 return 0;
1705
1706 printk("\n");
1707 printk("=============================================\n");
1708 printk("[ INFO: possible recursive locking detected ]\n");
1709 print_kernel_ident();
1710 printk("---------------------------------------------\n");
1711 printk("%s/%d is trying to acquire lock:\n",
1712 curr->comm, task_pid_nr(curr));
1713 print_lock(next);
1714 printk("\nbut task is already holding lock:\n");
1715 print_lock(prev);
1716
1717 printk("\nother info that might help us debug this:\n");
1718 print_deadlock_scenario(next, prev);
1719 lockdep_print_held_locks(curr);
1720
1721 printk("\nstack backtrace:\n");
1722 dump_stack();
1723
1724 return 0;
1725}
1726
1727/*
1728 * Check whether we are holding such a class already.
1729 *
1730 * (Note that this has to be done separately, because the graph cannot
1731 * detect such classes of deadlocks.)
1732 *
1733 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1734 */
1735static int
1736check_deadlock(struct task_struct *curr, struct held_lock *next,
1737 struct lockdep_map *next_instance, int read)
1738{
1739 struct held_lock *prev;
1740 struct held_lock *nest = NULL;
1741 int i;
1742
1743 for (i = 0; i < curr->lockdep_depth; i++) {
1744 prev = curr->held_locks + i;
1745
1746 if (prev->instance == next->nest_lock)
1747 nest = prev;
1748
1749 if (hlock_class(prev) != hlock_class(next))
1750 continue;
1751
1752 /*
1753 * Allow read-after-read recursion of the same
1754 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1755 */
1756 if ((read == 2) && prev->read)
1757 return 2;
1758
1759 /*
1760 * We're holding the nest_lock, which serializes this lock's
1761 * nesting behaviour.
1762 */
1763 if (nest)
1764 return 2;
1765
1766 return print_deadlock_bug(curr, prev, next);
1767 }
1768 return 1;
1769}
1770
1771/*
1772 * There was a chain-cache miss, and we are about to add a new dependency
1773 * to a previous lock. We recursively validate the following rules:
1774 *
1775 * - would the adding of the <prev> -> <next> dependency create a
1776 * circular dependency in the graph? [== circular deadlock]
1777 *
1778 * - does the new prev->next dependency connect any hardirq-safe lock
1779 * (in the full backwards-subgraph starting at <prev>) with any
1780 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1781 * <next>)? [== illegal lock inversion with hardirq contexts]
1782 *
1783 * - does the new prev->next dependency connect any softirq-safe lock
1784 * (in the full backwards-subgraph starting at <prev>) with any
1785 * softirq-unsafe lock (in the full forwards-subgraph starting at
1786 * <next>)? [== illegal lock inversion with softirq contexts]
1787 *
1788 * any of these scenarios could lead to a deadlock.
1789 *
1790 * Then if all the validations pass, we add the forwards and backwards
1791 * dependency.
1792 */
1793static int
1794check_prev_add(struct task_struct *curr, struct held_lock *prev,
1795 struct held_lock *next, int distance, int *stack_saved)
1796{
1797 struct lock_list *entry;
1798 int ret;
1799 struct lock_list this;
1800 struct lock_list *uninitialized_var(target_entry);
1801 /*
1802 * Static variable, serialized by the graph_lock().
1803 *
1804 * We use this static variable to save the stack trace in case
1805 * we call into this function multiple times due to encountering
1806 * trylocks in the held lock stack.
1807 */
1808 static struct stack_trace trace;
1809
1810 /*
1811 * Prove that the new <prev> -> <next> dependency would not
1812 * create a circular dependency in the graph. (We do this by
1813 * forward-recursing into the graph starting at <next>, and
1814 * checking whether we can reach <prev>.)
1815 *
1816 * We are using global variables to control the recursion, to
1817 * keep the stackframe size of the recursive functions low:
1818 */
1819 this.class = hlock_class(next);
1820 this.parent = NULL;
1821 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1822 if (unlikely(!ret))
1823 return print_circular_bug(&this, target_entry, next, prev);
1824 else if (unlikely(ret < 0))
1825 return print_bfs_bug(ret);
1826
1827 if (!check_prev_add_irq(curr, prev, next))
1828 return 0;
1829
1830 /*
1831 * For recursive read-locks we do all the dependency checks,
1832 * but we dont store read-triggered dependencies (only
1833 * write-triggered dependencies). This ensures that only the
1834 * write-side dependencies matter, and that if for example a
1835 * write-lock never takes any other locks, then the reads are
1836 * equivalent to a NOP.
1837 */
1838 if (next->read == 2 || prev->read == 2)
1839 return 1;
1840 /*
1841 * Is the <prev> -> <next> dependency already present?
1842 *
1843 * (this may occur even though this is a new chain: consider
1844 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1845 * chains - the second one will be new, but L1 already has
1846 * L2 added to its dependency list, due to the first chain.)
1847 */
1848 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1849 if (entry->class == hlock_class(next)) {
1850 if (distance == 1)
1851 entry->distance = 1;
1852 return 2;
1853 }
1854 }
1855
1856 if (!*stack_saved) {
1857 if (!save_trace(&trace))
1858 return 0;
1859 *stack_saved = 1;
1860 }
1861
1862 /*
1863 * Ok, all validations passed, add the new lock
1864 * to the previous lock's dependency list:
1865 */
1866 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1867 &hlock_class(prev)->locks_after,
1868 next->acquire_ip, distance, &trace);
1869
1870 if (!ret)
1871 return 0;
1872
1873 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1874 &hlock_class(next)->locks_before,
1875 next->acquire_ip, distance, &trace);
1876 if (!ret)
1877 return 0;
1878
1879 /*
1880 * Debugging printouts:
1881 */
1882 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1883 /* We drop graph lock, so another thread can overwrite trace. */
1884 *stack_saved = 0;
1885 graph_unlock();
1886 printk("\n new dependency: ");
1887 print_lock_name(hlock_class(prev));
1888 printk(" => ");
1889 print_lock_name(hlock_class(next));
1890 printk("\n");
1891 dump_stack();
1892 return graph_lock();
1893 }
1894 return 1;
1895}
1896
1897/*
1898 * Add the dependency to all directly-previous locks that are 'relevant'.
1899 * The ones that are relevant are (in increasing distance from curr):
1900 * all consecutive trylock entries and the final non-trylock entry - or
1901 * the end of this context's lock-chain - whichever comes first.
1902 */
1903static int
1904check_prevs_add(struct task_struct *curr, struct held_lock *next)
1905{
1906 int depth = curr->lockdep_depth;
1907 int stack_saved = 0;
1908 struct held_lock *hlock;
1909
1910 /*
1911 * Debugging checks.
1912 *
1913 * Depth must not be zero for a non-head lock:
1914 */
1915 if (!depth)
1916 goto out_bug;
1917 /*
1918 * At least two relevant locks must exist for this
1919 * to be a head:
1920 */
1921 if (curr->held_locks[depth].irq_context !=
1922 curr->held_locks[depth-1].irq_context)
1923 goto out_bug;
1924
1925 for (;;) {
1926 int distance = curr->lockdep_depth - depth + 1;
1927 hlock = curr->held_locks + depth - 1;
1928 /*
1929 * Only non-recursive-read entries get new dependencies
1930 * added:
1931 */
1932 if (hlock->read != 2 && hlock->check) {
1933 if (!check_prev_add(curr, hlock, next,
1934 distance, &stack_saved))
1935 return 0;
1936 /*
1937 * Stop after the first non-trylock entry,
1938 * as non-trylock entries have added their
1939 * own direct dependencies already, so this
1940 * lock is connected to them indirectly:
1941 */
1942 if (!hlock->trylock)
1943 break;
1944 }
1945 depth--;
1946 /*
1947 * End of lock-stack?
1948 */
1949 if (!depth)
1950 break;
1951 /*
1952 * Stop the search if we cross into another context:
1953 */
1954 if (curr->held_locks[depth].irq_context !=
1955 curr->held_locks[depth-1].irq_context)
1956 break;
1957 }
1958 return 1;
1959out_bug:
1960 if (!debug_locks_off_graph_unlock())
1961 return 0;
1962
1963 /*
1964 * Clearly we all shouldn't be here, but since we made it we
1965 * can reliable say we messed up our state. See the above two
1966 * gotos for reasons why we could possibly end up here.
1967 */
1968 WARN_ON(1);
1969
1970 return 0;
1971}
1972
1973unsigned long nr_lock_chains;
1974struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1975int nr_chain_hlocks;
1976static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1977
1978struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1979{
1980 return lock_classes + chain_hlocks[chain->base + i];
1981}
1982
1983/*
1984 * Returns the index of the first held_lock of the current chain
1985 */
1986static inline int get_first_held_lock(struct task_struct *curr,
1987 struct held_lock *hlock)
1988{
1989 int i;
1990 struct held_lock *hlock_curr;
1991
1992 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1993 hlock_curr = curr->held_locks + i;
1994 if (hlock_curr->irq_context != hlock->irq_context)
1995 break;
1996
1997 }
1998
1999 return ++i;
2000}
2001
2002#ifdef CONFIG_DEBUG_LOCKDEP
2003/*
2004 * Returns the next chain_key iteration
2005 */
2006static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2007{
2008 u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2009
2010 printk(" class_idx:%d -> chain_key:%016Lx",
2011 class_idx,
2012 (unsigned long long)new_chain_key);
2013 return new_chain_key;
2014}
2015
2016static void
2017print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2018{
2019 struct held_lock *hlock;
2020 u64 chain_key = 0;
2021 int depth = curr->lockdep_depth;
2022 int i;
2023
2024 printk("depth: %u\n", depth + 1);
2025 for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
2026 hlock = curr->held_locks + i;
2027 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2028
2029 print_lock(hlock);
2030 }
2031
2032 print_chain_key_iteration(hlock_next->class_idx, chain_key);
2033 print_lock(hlock_next);
2034}
2035
2036static void print_chain_keys_chain(struct lock_chain *chain)
2037{
2038 int i;
2039 u64 chain_key = 0;
2040 int class_id;
2041
2042 printk("depth: %u\n", chain->depth);
2043 for (i = 0; i < chain->depth; i++) {
2044 class_id = chain_hlocks[chain->base + i];
2045 chain_key = print_chain_key_iteration(class_id + 1, chain_key);
2046
2047 print_lock_name(lock_classes + class_id);
2048 printk("\n");
2049 }
2050}
2051
2052static void print_collision(struct task_struct *curr,
2053 struct held_lock *hlock_next,
2054 struct lock_chain *chain)
2055{
2056 printk("\n");
2057 printk("======================\n");
2058 printk("[chain_key collision ]\n");
2059 print_kernel_ident();
2060 printk("----------------------\n");
2061 printk("%s/%d: ", current->comm, task_pid_nr(current));
2062 printk("Hash chain already cached but the contents don't match!\n");
2063
2064 printk("Held locks:");
2065 print_chain_keys_held_locks(curr, hlock_next);
2066
2067 printk("Locks in cached chain:");
2068 print_chain_keys_chain(chain);
2069
2070 printk("\nstack backtrace:\n");
2071 dump_stack();
2072}
2073#endif
2074
2075/*
2076 * Checks whether the chain and the current held locks are consistent
2077 * in depth and also in content. If they are not it most likely means
2078 * that there was a collision during the calculation of the chain_key.
2079 * Returns: 0 not passed, 1 passed
2080 */
2081static int check_no_collision(struct task_struct *curr,
2082 struct held_lock *hlock,
2083 struct lock_chain *chain)
2084{
2085#ifdef CONFIG_DEBUG_LOCKDEP
2086 int i, j, id;
2087
2088 i = get_first_held_lock(curr, hlock);
2089
2090 if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2091 print_collision(curr, hlock, chain);
2092 return 0;
2093 }
2094
2095 for (j = 0; j < chain->depth - 1; j++, i++) {
2096 id = curr->held_locks[i].class_idx - 1;
2097
2098 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2099 print_collision(curr, hlock, chain);
2100 return 0;
2101 }
2102 }
2103#endif
2104 return 1;
2105}
2106
2107/*
2108 * Look up a dependency chain. If the key is not present yet then
2109 * add it and return 1 - in this case the new dependency chain is
2110 * validated. If the key is already hashed, return 0.
2111 * (On return with 1 graph_lock is held.)
2112 */
2113static inline int lookup_chain_cache(struct task_struct *curr,
2114 struct held_lock *hlock,
2115 u64 chain_key)
2116{
2117 struct lock_class *class = hlock_class(hlock);
2118 struct hlist_head *hash_head = chainhashentry(chain_key);
2119 struct lock_chain *chain;
2120 int i, j;
2121
2122 /*
2123 * We might need to take the graph lock, ensure we've got IRQs
2124 * disabled to make this an IRQ-safe lock.. for recursion reasons
2125 * lockdep won't complain about its own locking errors.
2126 */
2127 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2128 return 0;
2129 /*
2130 * We can walk it lock-free, because entries only get added
2131 * to the hash:
2132 */
2133 hlist_for_each_entry_rcu(chain, hash_head, entry) {
2134 if (chain->chain_key == chain_key) {
2135cache_hit:
2136 debug_atomic_inc(chain_lookup_hits);
2137 if (!check_no_collision(curr, hlock, chain))
2138 return 0;
2139
2140 if (very_verbose(class))
2141 printk("\nhash chain already cached, key: "
2142 "%016Lx tail class: [%p] %s\n",
2143 (unsigned long long)chain_key,
2144 class->key, class->name);
2145 return 0;
2146 }
2147 }
2148 if (very_verbose(class))
2149 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2150 (unsigned long long)chain_key, class->key, class->name);
2151 /*
2152 * Allocate a new chain entry from the static array, and add
2153 * it to the hash:
2154 */
2155 if (!graph_lock())
2156 return 0;
2157 /*
2158 * We have to walk the chain again locked - to avoid duplicates:
2159 */
2160 hlist_for_each_entry(chain, hash_head, entry) {
2161 if (chain->chain_key == chain_key) {
2162 graph_unlock();
2163 goto cache_hit;
2164 }
2165 }
2166 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2167 if (!debug_locks_off_graph_unlock())
2168 return 0;
2169
2170 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2171 dump_stack();
2172 return 0;
2173 }
2174 chain = lock_chains + nr_lock_chains++;
2175 chain->chain_key = chain_key;
2176 chain->irq_context = hlock->irq_context;
2177 i = get_first_held_lock(curr, hlock);
2178 chain->depth = curr->lockdep_depth + 1 - i;
2179
2180 BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2181 BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
2182 BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2183
2184 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2185 chain->base = nr_chain_hlocks;
2186 for (j = 0; j < chain->depth - 1; j++, i++) {
2187 int lock_id = curr->held_locks[i].class_idx - 1;
2188 chain_hlocks[chain->base + j] = lock_id;
2189 }
2190 chain_hlocks[chain->base + j] = class - lock_classes;
2191 }
2192
2193 if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
2194 nr_chain_hlocks += chain->depth;
2195
2196#ifdef CONFIG_DEBUG_LOCKDEP
2197 /*
2198 * Important for check_no_collision().
2199 */
2200 if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
2201 if (debug_locks_off_graph_unlock())
2202 return 0;
2203
2204 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2205 dump_stack();
2206 return 0;
2207 }
2208#endif
2209
2210 hlist_add_head_rcu(&chain->entry, hash_head);
2211 debug_atomic_inc(chain_lookup_misses);
2212 inc_chains();
2213
2214 return 1;
2215}
2216
2217static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2218 struct held_lock *hlock, int chain_head, u64 chain_key)
2219{
2220 /*
2221 * Trylock needs to maintain the stack of held locks, but it
2222 * does not add new dependencies, because trylock can be done
2223 * in any order.
2224 *
2225 * We look up the chain_key and do the O(N^2) check and update of
2226 * the dependencies only if this is a new dependency chain.
2227 * (If lookup_chain_cache() returns with 1 it acquires
2228 * graph_lock for us)
2229 */
2230 if (!hlock->trylock && hlock->check &&
2231 lookup_chain_cache(curr, hlock, chain_key)) {
2232 /*
2233 * Check whether last held lock:
2234 *
2235 * - is irq-safe, if this lock is irq-unsafe
2236 * - is softirq-safe, if this lock is hardirq-unsafe
2237 *
2238 * And check whether the new lock's dependency graph
2239 * could lead back to the previous lock.
2240 *
2241 * any of these scenarios could lead to a deadlock. If
2242 * All validations
2243 */
2244 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2245
2246 if (!ret)
2247 return 0;
2248 /*
2249 * Mark recursive read, as we jump over it when
2250 * building dependencies (just like we jump over
2251 * trylock entries):
2252 */
2253 if (ret == 2)
2254 hlock->read = 2;
2255 /*
2256 * Add dependency only if this lock is not the head
2257 * of the chain, and if it's not a secondary read-lock:
2258 */
2259 if (!chain_head && ret != 2)
2260 if (!check_prevs_add(curr, hlock))
2261 return 0;
2262 graph_unlock();
2263 } else
2264 /* after lookup_chain_cache(): */
2265 if (unlikely(!debug_locks))
2266 return 0;
2267
2268 return 1;
2269}
2270#else
2271static inline int validate_chain(struct task_struct *curr,
2272 struct lockdep_map *lock, struct held_lock *hlock,
2273 int chain_head, u64 chain_key)
2274{
2275 return 1;
2276}
2277#endif
2278
2279/*
2280 * We are building curr_chain_key incrementally, so double-check
2281 * it from scratch, to make sure that it's done correctly:
2282 */
2283static void check_chain_key(struct task_struct *curr)
2284{
2285#ifdef CONFIG_DEBUG_LOCKDEP
2286 struct held_lock *hlock, *prev_hlock = NULL;
2287 unsigned int i;
2288 u64 chain_key = 0;
2289
2290 for (i = 0; i < curr->lockdep_depth; i++) {
2291 hlock = curr->held_locks + i;
2292 if (chain_key != hlock->prev_chain_key) {
2293 debug_locks_off();
2294 /*
2295 * We got mighty confused, our chain keys don't match
2296 * with what we expect, someone trample on our task state?
2297 */
2298 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2299 curr->lockdep_depth, i,
2300 (unsigned long long)chain_key,
2301 (unsigned long long)hlock->prev_chain_key);
2302 return;
2303 }
2304 /*
2305 * Whoops ran out of static storage again?
2306 */
2307 if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
2308 return;
2309
2310 if (prev_hlock && (prev_hlock->irq_context !=
2311 hlock->irq_context))
2312 chain_key = 0;
2313 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
2314 prev_hlock = hlock;
2315 }
2316 if (chain_key != curr->curr_chain_key) {
2317 debug_locks_off();
2318 /*
2319 * More smoking hash instead of calculating it, damn see these
2320 * numbers float.. I bet that a pink elephant stepped on my memory.
2321 */
2322 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2323 curr->lockdep_depth, i,
2324 (unsigned long long)chain_key,
2325 (unsigned long long)curr->curr_chain_key);
2326 }
2327#endif
2328}
2329
2330static void
2331print_usage_bug_scenario(struct held_lock *lock)
2332{
2333 struct lock_class *class = hlock_class(lock);
2334
2335 printk(" Possible unsafe locking scenario:\n\n");
2336 printk(" CPU0\n");
2337 printk(" ----\n");
2338 printk(" lock(");
2339 __print_lock_name(class);
2340 printk(");\n");
2341 printk(" <Interrupt>\n");
2342 printk(" lock(");
2343 __print_lock_name(class);
2344 printk(");\n");
2345 printk("\n *** DEADLOCK ***\n\n");
2346}
2347
2348static int
2349print_usage_bug(struct task_struct *curr, struct held_lock *this,
2350 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2351{
2352 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2353 return 0;
2354
2355 printk("\n");
2356 printk("=================================\n");
2357 printk("[ INFO: inconsistent lock state ]\n");
2358 print_kernel_ident();
2359 printk("---------------------------------\n");
2360
2361 printk("inconsistent {%s} -> {%s} usage.\n",
2362 usage_str[prev_bit], usage_str[new_bit]);
2363
2364 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2365 curr->comm, task_pid_nr(curr),
2366 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2367 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2368 trace_hardirqs_enabled(curr),
2369 trace_softirqs_enabled(curr));
2370 print_lock(this);
2371
2372 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2373 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2374
2375 print_irqtrace_events(curr);
2376 printk("\nother info that might help us debug this:\n");
2377 print_usage_bug_scenario(this);
2378
2379 lockdep_print_held_locks(curr);
2380
2381 printk("\nstack backtrace:\n");
2382 dump_stack();
2383
2384 return 0;
2385}
2386
2387/*
2388 * Print out an error if an invalid bit is set:
2389 */
2390static inline int
2391valid_state(struct task_struct *curr, struct held_lock *this,
2392 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2393{
2394 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2395 return print_usage_bug(curr, this, bad_bit, new_bit);
2396 return 1;
2397}
2398
2399static int mark_lock(struct task_struct *curr, struct held_lock *this,
2400 enum lock_usage_bit new_bit);
2401
2402#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2403
2404/*
2405 * print irq inversion bug:
2406 */
2407static int
2408print_irq_inversion_bug(struct task_struct *curr,
2409 struct lock_list *root, struct lock_list *other,
2410 struct held_lock *this, int forwards,
2411 const char *irqclass)
2412{
2413 struct lock_list *entry = other;
2414 struct lock_list *middle = NULL;
2415 int depth;
2416
2417 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2418 return 0;
2419
2420 printk("\n");
2421 printk("=========================================================\n");
2422 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2423 print_kernel_ident();
2424 printk("---------------------------------------------------------\n");
2425 printk("%s/%d just changed the state of lock:\n",
2426 curr->comm, task_pid_nr(curr));
2427 print_lock(this);
2428 if (forwards)
2429 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2430 else
2431 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2432 print_lock_name(other->class);
2433 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2434
2435 printk("\nother info that might help us debug this:\n");
2436
2437 /* Find a middle lock (if one exists) */
2438 depth = get_lock_depth(other);
2439 do {
2440 if (depth == 0 && (entry != root)) {
2441 printk("lockdep:%s bad path found in chain graph\n", __func__);
2442 break;
2443 }
2444 middle = entry;
2445 entry = get_lock_parent(entry);
2446 depth--;
2447 } while (entry && entry != root && (depth >= 0));
2448 if (forwards)
2449 print_irq_lock_scenario(root, other,
2450 middle ? middle->class : root->class, other->class);
2451 else
2452 print_irq_lock_scenario(other, root,
2453 middle ? middle->class : other->class, root->class);
2454
2455 lockdep_print_held_locks(curr);
2456
2457 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2458 if (!save_trace(&root->trace))
2459 return 0;
2460 print_shortest_lock_dependencies(other, root);
2461
2462 printk("\nstack backtrace:\n");
2463 dump_stack();
2464
2465 return 0;
2466}
2467
2468/*
2469 * Prove that in the forwards-direction subgraph starting at <this>
2470 * there is no lock matching <mask>:
2471 */
2472static int
2473check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2474 enum lock_usage_bit bit, const char *irqclass)
2475{
2476 int ret;
2477 struct lock_list root;
2478 struct lock_list *uninitialized_var(target_entry);
2479
2480 root.parent = NULL;
2481 root.class = hlock_class(this);
2482 ret = find_usage_forwards(&root, bit, &target_entry);
2483 if (ret < 0)
2484 return print_bfs_bug(ret);
2485 if (ret == 1)
2486 return ret;
2487
2488 return print_irq_inversion_bug(curr, &root, target_entry,
2489 this, 1, irqclass);
2490}
2491
2492/*
2493 * Prove that in the backwards-direction subgraph starting at <this>
2494 * there is no lock matching <mask>:
2495 */
2496static int
2497check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2498 enum lock_usage_bit bit, const char *irqclass)
2499{
2500 int ret;
2501 struct lock_list root;
2502 struct lock_list *uninitialized_var(target_entry);
2503
2504 root.parent = NULL;
2505 root.class = hlock_class(this);
2506 ret = find_usage_backwards(&root, bit, &target_entry);
2507 if (ret < 0)
2508 return print_bfs_bug(ret);
2509 if (ret == 1)
2510 return ret;
2511
2512 return print_irq_inversion_bug(curr, &root, target_entry,
2513 this, 0, irqclass);
2514}
2515
2516void print_irqtrace_events(struct task_struct *curr)
2517{
2518 printk("irq event stamp: %u\n", curr->irq_events);
2519 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2520 print_ip_sym(curr->hardirq_enable_ip);
2521 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2522 print_ip_sym(curr->hardirq_disable_ip);
2523 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2524 print_ip_sym(curr->softirq_enable_ip);
2525 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2526 print_ip_sym(curr->softirq_disable_ip);
2527}
2528
2529static int HARDIRQ_verbose(struct lock_class *class)
2530{
2531#if HARDIRQ_VERBOSE
2532 return class_filter(class);
2533#endif
2534 return 0;
2535}
2536
2537static int SOFTIRQ_verbose(struct lock_class *class)
2538{
2539#if SOFTIRQ_VERBOSE
2540 return class_filter(class);
2541#endif
2542 return 0;
2543}
2544
2545static int RECLAIM_FS_verbose(struct lock_class *class)
2546{
2547#if RECLAIM_VERBOSE
2548 return class_filter(class);
2549#endif
2550 return 0;
2551}
2552
2553#define STRICT_READ_CHECKS 1
2554
2555static int (*state_verbose_f[])(struct lock_class *class) = {
2556#define LOCKDEP_STATE(__STATE) \
2557 __STATE##_verbose,
2558#include "lockdep_states.h"
2559#undef LOCKDEP_STATE
2560};
2561
2562static inline int state_verbose(enum lock_usage_bit bit,
2563 struct lock_class *class)
2564{
2565 return state_verbose_f[bit >> 2](class);
2566}
2567
2568typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2569 enum lock_usage_bit bit, const char *name);
2570
2571static int
2572mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2573 enum lock_usage_bit new_bit)
2574{
2575 int excl_bit = exclusive_bit(new_bit);
2576 int read = new_bit & 1;
2577 int dir = new_bit & 2;
2578
2579 /*
2580 * mark USED_IN has to look forwards -- to ensure no dependency
2581 * has ENABLED state, which would allow recursion deadlocks.
2582 *
2583 * mark ENABLED has to look backwards -- to ensure no dependee
2584 * has USED_IN state, which, again, would allow recursion deadlocks.
2585 */
2586 check_usage_f usage = dir ?
2587 check_usage_backwards : check_usage_forwards;
2588
2589 /*
2590 * Validate that this particular lock does not have conflicting
2591 * usage states.
2592 */
2593 if (!valid_state(curr, this, new_bit, excl_bit))
2594 return 0;
2595
2596 /*
2597 * Validate that the lock dependencies don't have conflicting usage
2598 * states.
2599 */
2600 if ((!read || !dir || STRICT_READ_CHECKS) &&
2601 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2602 return 0;
2603
2604 /*
2605 * Check for read in write conflicts
2606 */
2607 if (!read) {
2608 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2609 return 0;
2610
2611 if (STRICT_READ_CHECKS &&
2612 !usage(curr, this, excl_bit + 1,
2613 state_name(new_bit + 1)))
2614 return 0;
2615 }
2616
2617 if (state_verbose(new_bit, hlock_class(this)))
2618 return 2;
2619
2620 return 1;
2621}
2622
2623enum mark_type {
2624#define LOCKDEP_STATE(__STATE) __STATE,
2625#include "lockdep_states.h"
2626#undef LOCKDEP_STATE
2627};
2628
2629/*
2630 * Mark all held locks with a usage bit:
2631 */
2632static int
2633mark_held_locks(struct task_struct *curr, enum mark_type mark)
2634{
2635 enum lock_usage_bit usage_bit;
2636 struct held_lock *hlock;
2637 int i;
2638
2639 for (i = 0; i < curr->lockdep_depth; i++) {
2640 hlock = curr->held_locks + i;
2641
2642 usage_bit = 2 + (mark << 2); /* ENABLED */
2643 if (hlock->read)
2644 usage_bit += 1; /* READ */
2645
2646 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2647
2648 if (!hlock->check)
2649 continue;
2650
2651 if (!mark_lock(curr, hlock, usage_bit))
2652 return 0;
2653 }
2654
2655 return 1;
2656}
2657
2658/*
2659 * Hardirqs will be enabled:
2660 */
2661static void __trace_hardirqs_on_caller(unsigned long ip)
2662{
2663 struct task_struct *curr = current;
2664
2665 /* we'll do an OFF -> ON transition: */
2666 curr->hardirqs_enabled = 1;
2667
2668 /*
2669 * We are going to turn hardirqs on, so set the
2670 * usage bit for all held locks:
2671 */
2672 if (!mark_held_locks(curr, HARDIRQ))
2673 return;
2674 /*
2675 * If we have softirqs enabled, then set the usage
2676 * bit for all held locks. (disabled hardirqs prevented
2677 * this bit from being set before)
2678 */
2679 if (curr->softirqs_enabled)
2680 if (!mark_held_locks(curr, SOFTIRQ))
2681 return;
2682
2683 curr->hardirq_enable_ip = ip;
2684 curr->hardirq_enable_event = ++curr->irq_events;
2685 debug_atomic_inc(hardirqs_on_events);
2686}
2687
2688__visible void trace_hardirqs_on_caller(unsigned long ip)
2689{
2690 time_hardirqs_on(CALLER_ADDR0, ip);
2691
2692 if (unlikely(!debug_locks || current->lockdep_recursion))
2693 return;
2694
2695 if (unlikely(current->hardirqs_enabled)) {
2696 /*
2697 * Neither irq nor preemption are disabled here
2698 * so this is racy by nature but losing one hit
2699 * in a stat is not a big deal.
2700 */
2701 __debug_atomic_inc(redundant_hardirqs_on);
2702 return;
2703 }
2704
2705 /*
2706 * We're enabling irqs and according to our state above irqs weren't
2707 * already enabled, yet we find the hardware thinks they are in fact
2708 * enabled.. someone messed up their IRQ state tracing.
2709 */
2710 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2711 return;
2712
2713 /*
2714 * See the fine text that goes along with this variable definition.
2715 */
2716 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2717 return;
2718
2719 /*
2720 * Can't allow enabling interrupts while in an interrupt handler,
2721 * that's general bad form and such. Recursion, limited stack etc..
2722 */
2723 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2724 return;
2725
2726 current->lockdep_recursion = 1;
2727 __trace_hardirqs_on_caller(ip);
2728 current->lockdep_recursion = 0;
2729}
2730EXPORT_SYMBOL(trace_hardirqs_on_caller);
2731
2732void trace_hardirqs_on(void)
2733{
2734 trace_hardirqs_on_caller(CALLER_ADDR0);
2735}
2736EXPORT_SYMBOL(trace_hardirqs_on);
2737
2738/*
2739 * Hardirqs were disabled:
2740 */
2741__visible void trace_hardirqs_off_caller(unsigned long ip)
2742{
2743 struct task_struct *curr = current;
2744
2745 time_hardirqs_off(CALLER_ADDR0, ip);
2746
2747 if (unlikely(!debug_locks || current->lockdep_recursion))
2748 return;
2749
2750 /*
2751 * So we're supposed to get called after you mask local IRQs, but for
2752 * some reason the hardware doesn't quite think you did a proper job.
2753 */
2754 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2755 return;
2756
2757 if (curr->hardirqs_enabled) {
2758 /*
2759 * We have done an ON -> OFF transition:
2760 */
2761 curr->hardirqs_enabled = 0;
2762 curr->hardirq_disable_ip = ip;
2763 curr->hardirq_disable_event = ++curr->irq_events;
2764 debug_atomic_inc(hardirqs_off_events);
2765 } else
2766 debug_atomic_inc(redundant_hardirqs_off);
2767}
2768EXPORT_SYMBOL(trace_hardirqs_off_caller);
2769
2770void trace_hardirqs_off(void)
2771{
2772 trace_hardirqs_off_caller(CALLER_ADDR0);
2773}
2774EXPORT_SYMBOL(trace_hardirqs_off);
2775
2776/*
2777 * Softirqs will be enabled:
2778 */
2779void trace_softirqs_on(unsigned long ip)
2780{
2781 struct task_struct *curr = current;
2782
2783 if (unlikely(!debug_locks || current->lockdep_recursion))
2784 return;
2785
2786 /*
2787 * We fancy IRQs being disabled here, see softirq.c, avoids
2788 * funny state and nesting things.
2789 */
2790 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2791 return;
2792
2793 if (curr->softirqs_enabled) {
2794 debug_atomic_inc(redundant_softirqs_on);
2795 return;
2796 }
2797
2798 current->lockdep_recursion = 1;
2799 /*
2800 * We'll do an OFF -> ON transition:
2801 */
2802 curr->softirqs_enabled = 1;
2803 curr->softirq_enable_ip = ip;
2804 curr->softirq_enable_event = ++curr->irq_events;
2805 debug_atomic_inc(softirqs_on_events);
2806 /*
2807 * We are going to turn softirqs on, so set the
2808 * usage bit for all held locks, if hardirqs are
2809 * enabled too:
2810 */
2811 if (curr->hardirqs_enabled)
2812 mark_held_locks(curr, SOFTIRQ);
2813 current->lockdep_recursion = 0;
2814}
2815
2816/*
2817 * Softirqs were disabled:
2818 */
2819void trace_softirqs_off(unsigned long ip)
2820{
2821 struct task_struct *curr = current;
2822
2823 if (unlikely(!debug_locks || current->lockdep_recursion))
2824 return;
2825
2826 /*
2827 * We fancy IRQs being disabled here, see softirq.c
2828 */
2829 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2830 return;
2831
2832 if (curr->softirqs_enabled) {
2833 /*
2834 * We have done an ON -> OFF transition:
2835 */
2836 curr->softirqs_enabled = 0;
2837 curr->softirq_disable_ip = ip;
2838 curr->softirq_disable_event = ++curr->irq_events;
2839 debug_atomic_inc(softirqs_off_events);
2840 /*
2841 * Whoops, we wanted softirqs off, so why aren't they?
2842 */
2843 DEBUG_LOCKS_WARN_ON(!softirq_count());
2844 } else
2845 debug_atomic_inc(redundant_softirqs_off);
2846}
2847
2848static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2849{
2850 struct task_struct *curr = current;
2851
2852 if (unlikely(!debug_locks))
2853 return;
2854
2855 /* no reclaim without waiting on it */
2856 if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
2857 return;
2858
2859 /* this guy won't enter reclaim */
2860 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2861 return;
2862
2863 /* We're only interested __GFP_FS allocations for now */
2864 if (!(gfp_mask & __GFP_FS))
2865 return;
2866
2867 /*
2868 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2869 */
2870 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2871 return;
2872
2873 mark_held_locks(curr, RECLAIM_FS);
2874}
2875
2876static void check_flags(unsigned long flags);
2877
2878void lockdep_trace_alloc(gfp_t gfp_mask)
2879{
2880 unsigned long flags;
2881
2882 if (unlikely(current->lockdep_recursion))
2883 return;
2884
2885 raw_local_irq_save(flags);
2886 check_flags(flags);
2887 current->lockdep_recursion = 1;
2888 __lockdep_trace_alloc(gfp_mask, flags);
2889 current->lockdep_recursion = 0;
2890 raw_local_irq_restore(flags);
2891}
2892
2893static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2894{
2895 /*
2896 * If non-trylock use in a hardirq or softirq context, then
2897 * mark the lock as used in these contexts:
2898 */
2899 if (!hlock->trylock) {
2900 if (hlock->read) {
2901 if (curr->hardirq_context)
2902 if (!mark_lock(curr, hlock,
2903 LOCK_USED_IN_HARDIRQ_READ))
2904 return 0;
2905 if (curr->softirq_context)
2906 if (!mark_lock(curr, hlock,
2907 LOCK_USED_IN_SOFTIRQ_READ))
2908 return 0;
2909 } else {
2910 if (curr->hardirq_context)
2911 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2912 return 0;
2913 if (curr->softirq_context)
2914 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2915 return 0;
2916 }
2917 }
2918 if (!hlock->hardirqs_off) {
2919 if (hlock->read) {
2920 if (!mark_lock(curr, hlock,
2921 LOCK_ENABLED_HARDIRQ_READ))
2922 return 0;
2923 if (curr->softirqs_enabled)
2924 if (!mark_lock(curr, hlock,
2925 LOCK_ENABLED_SOFTIRQ_READ))
2926 return 0;
2927 } else {
2928 if (!mark_lock(curr, hlock,
2929 LOCK_ENABLED_HARDIRQ))
2930 return 0;
2931 if (curr->softirqs_enabled)
2932 if (!mark_lock(curr, hlock,
2933 LOCK_ENABLED_SOFTIRQ))
2934 return 0;
2935 }
2936 }
2937
2938 /*
2939 * We reuse the irq context infrastructure more broadly as a general
2940 * context checking code. This tests GFP_FS recursion (a lock taken
2941 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2942 * allocation).
2943 */
2944 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2945 if (hlock->read) {
2946 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2947 return 0;
2948 } else {
2949 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2950 return 0;
2951 }
2952 }
2953
2954 return 1;
2955}
2956
2957static inline unsigned int task_irq_context(struct task_struct *task)
2958{
2959 return 2 * !!task->hardirq_context + !!task->softirq_context;
2960}
2961
2962static int separate_irq_context(struct task_struct *curr,
2963 struct held_lock *hlock)
2964{
2965 unsigned int depth = curr->lockdep_depth;
2966
2967 /*
2968 * Keep track of points where we cross into an interrupt context:
2969 */
2970 if (depth) {
2971 struct held_lock *prev_hlock;
2972
2973 prev_hlock = curr->held_locks + depth-1;
2974 /*
2975 * If we cross into another context, reset the
2976 * hash key (this also prevents the checking and the
2977 * adding of the dependency to 'prev'):
2978 */
2979 if (prev_hlock->irq_context != hlock->irq_context)
2980 return 1;
2981 }
2982 return 0;
2983}
2984
2985#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2986
2987static inline
2988int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2989 enum lock_usage_bit new_bit)
2990{
2991 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2992 return 1;
2993}
2994
2995static inline int mark_irqflags(struct task_struct *curr,
2996 struct held_lock *hlock)
2997{
2998 return 1;
2999}
3000
3001static inline unsigned int task_irq_context(struct task_struct *task)
3002{
3003 return 0;
3004}
3005
3006static inline int separate_irq_context(struct task_struct *curr,
3007 struct held_lock *hlock)
3008{
3009 return 0;
3010}
3011
3012void lockdep_trace_alloc(gfp_t gfp_mask)
3013{
3014}
3015
3016#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3017
3018/*
3019 * Mark a lock with a usage bit, and validate the state transition:
3020 */
3021static int mark_lock(struct task_struct *curr, struct held_lock *this,
3022 enum lock_usage_bit new_bit)
3023{
3024 unsigned int new_mask = 1 << new_bit, ret = 1;
3025
3026 /*
3027 * If already set then do not dirty the cacheline,
3028 * nor do any checks:
3029 */
3030 if (likely(hlock_class(this)->usage_mask & new_mask))
3031 return 1;
3032
3033 if (!graph_lock())
3034 return 0;
3035 /*
3036 * Make sure we didn't race:
3037 */
3038 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3039 graph_unlock();
3040 return 1;
3041 }
3042
3043 hlock_class(this)->usage_mask |= new_mask;
3044
3045 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
3046 return 0;
3047
3048 switch (new_bit) {
3049#define LOCKDEP_STATE(__STATE) \
3050 case LOCK_USED_IN_##__STATE: \
3051 case LOCK_USED_IN_##__STATE##_READ: \
3052 case LOCK_ENABLED_##__STATE: \
3053 case LOCK_ENABLED_##__STATE##_READ:
3054#include "lockdep_states.h"
3055#undef LOCKDEP_STATE
3056 ret = mark_lock_irq(curr, this, new_bit);
3057 if (!ret)
3058 return 0;
3059 break;
3060 case LOCK_USED:
3061 debug_atomic_dec(nr_unused_locks);
3062 break;
3063 default:
3064 if (!debug_locks_off_graph_unlock())
3065 return 0;
3066 WARN_ON(1);
3067 return 0;
3068 }
3069
3070 graph_unlock();
3071
3072 /*
3073 * We must printk outside of the graph_lock:
3074 */
3075 if (ret == 2) {
3076 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3077 print_lock(this);
3078 print_irqtrace_events(curr);
3079 dump_stack();
3080 }
3081
3082 return ret;
3083}
3084
3085/*
3086 * Initialize a lock instance's lock-class mapping info:
3087 */
3088void lockdep_init_map(struct lockdep_map *lock, const char *name,
3089 struct lock_class_key *key, int subclass)
3090{
3091 int i;
3092
3093 kmemcheck_mark_initialized(lock, sizeof(*lock));
3094
3095 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3096 lock->class_cache[i] = NULL;
3097
3098#ifdef CONFIG_LOCK_STAT
3099 lock->cpu = raw_smp_processor_id();
3100#endif
3101
3102 /*
3103 * Can't be having no nameless bastards around this place!
3104 */
3105 if (DEBUG_LOCKS_WARN_ON(!name)) {
3106 lock->name = "NULL";
3107 return;
3108 }
3109
3110 lock->name = name;
3111
3112 /*
3113 * No key, no joy, we need to hash something.
3114 */
3115 if (DEBUG_LOCKS_WARN_ON(!key))
3116 return;
3117 /*
3118 * Sanity check, the lock-class key must be persistent:
3119 */
3120 if (!static_obj(key)) {
3121 printk("BUG: key %p not in .data!\n", key);
3122 /*
3123 * What it says above ^^^^^, I suggest you read it.
3124 */
3125 DEBUG_LOCKS_WARN_ON(1);
3126 return;
3127 }
3128 lock->key = key;
3129
3130 if (unlikely(!debug_locks))
3131 return;
3132
3133 if (subclass) {
3134 unsigned long flags;
3135
3136 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3137 return;
3138
3139 raw_local_irq_save(flags);
3140 current->lockdep_recursion = 1;
3141 register_lock_class(lock, subclass, 1);
3142 current->lockdep_recursion = 0;
3143 raw_local_irq_restore(flags);
3144 }
3145}
3146EXPORT_SYMBOL_GPL(lockdep_init_map);
3147
3148struct lock_class_key __lockdep_no_validate__;
3149EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3150
3151static int
3152print_lock_nested_lock_not_held(struct task_struct *curr,
3153 struct held_lock *hlock,
3154 unsigned long ip)
3155{
3156 if (!debug_locks_off())
3157 return 0;
3158 if (debug_locks_silent)
3159 return 0;
3160
3161 printk("\n");
3162 printk("==================================\n");
3163 printk("[ BUG: Nested lock was not taken ]\n");
3164 print_kernel_ident();
3165 printk("----------------------------------\n");
3166
3167 printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3168 print_lock(hlock);
3169
3170 printk("\nbut this task is not holding:\n");
3171 printk("%s\n", hlock->nest_lock->name);
3172
3173 printk("\nstack backtrace:\n");
3174 dump_stack();
3175
3176 printk("\nother info that might help us debug this:\n");
3177 lockdep_print_held_locks(curr);
3178
3179 printk("\nstack backtrace:\n");
3180 dump_stack();
3181
3182 return 0;
3183}
3184
3185static int __lock_is_held(struct lockdep_map *lock);
3186
3187/*
3188 * This gets called for every mutex_lock*()/spin_lock*() operation.
3189 * We maintain the dependency maps and validate the locking attempt:
3190 */
3191static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3192 int trylock, int read, int check, int hardirqs_off,
3193 struct lockdep_map *nest_lock, unsigned long ip,
3194 int references, int pin_count)
3195{
3196 struct task_struct *curr = current;
3197 struct lock_class *class = NULL;
3198 struct held_lock *hlock;
3199 unsigned int depth;
3200 int chain_head = 0;
3201 int class_idx;
3202 u64 chain_key;
3203
3204 if (unlikely(!debug_locks))
3205 return 0;
3206
3207 /*
3208 * Lockdep should run with IRQs disabled, otherwise we could
3209 * get an interrupt which would want to take locks, which would
3210 * end up in lockdep and have you got a head-ache already?
3211 */
3212 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3213 return 0;
3214
3215 if (!prove_locking || lock->key == &__lockdep_no_validate__)
3216 check = 0;
3217
3218 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3219 class = lock->class_cache[subclass];
3220 /*
3221 * Not cached?
3222 */
3223 if (unlikely(!class)) {
3224 class = register_lock_class(lock, subclass, 0);
3225 if (!class)
3226 return 0;
3227 }
3228 atomic_inc((atomic_t *)&class->ops);
3229 if (very_verbose(class)) {
3230 printk("\nacquire class [%p] %s", class->key, class->name);
3231 if (class->name_version > 1)
3232 printk("#%d", class->name_version);
3233 printk("\n");
3234 dump_stack();
3235 }
3236
3237 /*
3238 * Add the lock to the list of currently held locks.
3239 * (we dont increase the depth just yet, up until the
3240 * dependency checks are done)
3241 */
3242 depth = curr->lockdep_depth;
3243 /*
3244 * Ran out of static storage for our per-task lock stack again have we?
3245 */
3246 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3247 return 0;
3248
3249 class_idx = class - lock_classes + 1;
3250
3251 if (depth) {
3252 hlock = curr->held_locks + depth - 1;
3253 if (hlock->class_idx == class_idx && nest_lock) {
3254 if (hlock->references)
3255 hlock->references++;
3256 else
3257 hlock->references = 2;
3258
3259 return 1;
3260 }
3261 }
3262
3263 hlock = curr->held_locks + depth;
3264 /*
3265 * Plain impossible, we just registered it and checked it weren't no
3266 * NULL like.. I bet this mushroom I ate was good!
3267 */
3268 if (DEBUG_LOCKS_WARN_ON(!class))
3269 return 0;
3270 hlock->class_idx = class_idx;
3271 hlock->acquire_ip = ip;
3272 hlock->instance = lock;
3273 hlock->nest_lock = nest_lock;
3274 hlock->irq_context = task_irq_context(curr);
3275 hlock->trylock = trylock;
3276 hlock->read = read;
3277 hlock->check = check;
3278 hlock->hardirqs_off = !!hardirqs_off;
3279 hlock->references = references;
3280#ifdef CONFIG_LOCK_STAT
3281 hlock->waittime_stamp = 0;
3282 hlock->holdtime_stamp = lockstat_clock();
3283#endif
3284 hlock->pin_count = pin_count;
3285
3286 if (check && !mark_irqflags(curr, hlock))
3287 return 0;
3288
3289 /* mark it as used: */
3290 if (!mark_lock(curr, hlock, LOCK_USED))
3291 return 0;
3292
3293 /*
3294 * Calculate the chain hash: it's the combined hash of all the
3295 * lock keys along the dependency chain. We save the hash value
3296 * at every step so that we can get the current hash easily
3297 * after unlock. The chain hash is then used to cache dependency
3298 * results.
3299 *
3300 * The 'key ID' is what is the most compact key value to drive
3301 * the hash, not class->key.
3302 */
3303 /*
3304 * Whoops, we did it again.. ran straight out of our static allocation.
3305 */
3306 if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
3307 return 0;
3308
3309 chain_key = curr->curr_chain_key;
3310 if (!depth) {
3311 /*
3312 * How can we have a chain hash when we ain't got no keys?!
3313 */
3314 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3315 return 0;
3316 chain_head = 1;
3317 }
3318
3319 hlock->prev_chain_key = chain_key;
3320 if (separate_irq_context(curr, hlock)) {
3321 chain_key = 0;
3322 chain_head = 1;
3323 }
3324 chain_key = iterate_chain_key(chain_key, class_idx);
3325
3326 if (nest_lock && !__lock_is_held(nest_lock))
3327 return print_lock_nested_lock_not_held(curr, hlock, ip);
3328
3329 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3330 return 0;
3331
3332 curr->curr_chain_key = chain_key;
3333 curr->lockdep_depth++;
3334 check_chain_key(curr);
3335#ifdef CONFIG_DEBUG_LOCKDEP
3336 if (unlikely(!debug_locks))
3337 return 0;
3338#endif
3339 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3340 debug_locks_off();
3341 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3342 printk(KERN_DEBUG "depth: %i max: %lu!\n",
3343 curr->lockdep_depth, MAX_LOCK_DEPTH);
3344
3345 lockdep_print_held_locks(current);
3346 debug_show_all_locks();
3347 dump_stack();
3348
3349 return 0;
3350 }
3351
3352 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3353 max_lockdep_depth = curr->lockdep_depth;
3354
3355 return 1;
3356}
3357
3358static int
3359print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3360 unsigned long ip)
3361{
3362 if (!debug_locks_off())
3363 return 0;
3364 if (debug_locks_silent)
3365 return 0;
3366
3367 printk("\n");
3368 printk("=====================================\n");
3369 printk("[ BUG: bad unlock balance detected! ]\n");
3370 print_kernel_ident();
3371 printk("-------------------------------------\n");
3372 printk("%s/%d is trying to release lock (",
3373 curr->comm, task_pid_nr(curr));
3374 print_lockdep_cache(lock);
3375 printk(") at:\n");
3376 print_ip_sym(ip);
3377 printk("but there are no more locks to release!\n");
3378 printk("\nother info that might help us debug this:\n");
3379 lockdep_print_held_locks(curr);
3380
3381 printk("\nstack backtrace:\n");
3382 dump_stack();
3383
3384 return 0;
3385}
3386
3387static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3388{
3389 if (hlock->instance == lock)
3390 return 1;
3391
3392 if (hlock->references) {
3393 struct lock_class *class = lock->class_cache[0];
3394
3395 if (!class)
3396 class = look_up_lock_class(lock, 0);
3397
3398 /*
3399 * If look_up_lock_class() failed to find a class, we're trying
3400 * to test if we hold a lock that has never yet been acquired.
3401 * Clearly if the lock hasn't been acquired _ever_, we're not
3402 * holding it either, so report failure.
3403 */
3404 if (!class)
3405 return 0;
3406
3407 /*
3408 * References, but not a lock we're actually ref-counting?
3409 * State got messed up, follow the sites that change ->references
3410 * and try to make sense of it.
3411 */
3412 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3413 return 0;
3414
3415 if (hlock->class_idx == class - lock_classes + 1)
3416 return 1;
3417 }
3418
3419 return 0;
3420}
3421
3422static int
3423__lock_set_class(struct lockdep_map *lock, const char *name,
3424 struct lock_class_key *key, unsigned int subclass,
3425 unsigned long ip)
3426{
3427 struct task_struct *curr = current;
3428 struct held_lock *hlock, *prev_hlock;
3429 struct lock_class *class;
3430 unsigned int depth;
3431 int i;
3432
3433 depth = curr->lockdep_depth;
3434 /*
3435 * This function is about (re)setting the class of a held lock,
3436 * yet we're not actually holding any locks. Naughty user!
3437 */
3438 if (DEBUG_LOCKS_WARN_ON(!depth))
3439 return 0;
3440
3441 prev_hlock = NULL;
3442 for (i = depth-1; i >= 0; i--) {
3443 hlock = curr->held_locks + i;
3444 /*
3445 * We must not cross into another context:
3446 */
3447 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3448 break;
3449 if (match_held_lock(hlock, lock))
3450 goto found_it;
3451 prev_hlock = hlock;
3452 }
3453 return print_unlock_imbalance_bug(curr, lock, ip);
3454
3455found_it:
3456 lockdep_init_map(lock, name, key, 0);
3457 class = register_lock_class(lock, subclass, 0);
3458 hlock->class_idx = class - lock_classes + 1;
3459
3460 curr->lockdep_depth = i;
3461 curr->curr_chain_key = hlock->prev_chain_key;
3462
3463 for (; i < depth; i++) {
3464 hlock = curr->held_locks + i;
3465 if (!__lock_acquire(hlock->instance,
3466 hlock_class(hlock)->subclass, hlock->trylock,
3467 hlock->read, hlock->check, hlock->hardirqs_off,
3468 hlock->nest_lock, hlock->acquire_ip,
3469 hlock->references, hlock->pin_count))
3470 return 0;
3471 }
3472
3473 /*
3474 * I took it apart and put it back together again, except now I have
3475 * these 'spare' parts.. where shall I put them.
3476 */
3477 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3478 return 0;
3479 return 1;
3480}
3481
3482/*
3483 * Remove the lock to the list of currently held locks - this gets
3484 * called on mutex_unlock()/spin_unlock*() (or on a failed
3485 * mutex_lock_interruptible()).
3486 *
3487 * @nested is an hysterical artifact, needs a tree wide cleanup.
3488 */
3489static int
3490__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3491{
3492 struct task_struct *curr = current;
3493 struct held_lock *hlock, *prev_hlock;
3494 unsigned int depth;
3495 int i;
3496
3497 if (unlikely(!debug_locks))
3498 return 0;
3499
3500 depth = curr->lockdep_depth;
3501 /*
3502 * So we're all set to release this lock.. wait what lock? We don't
3503 * own any locks, you've been drinking again?
3504 */
3505 if (DEBUG_LOCKS_WARN_ON(depth <= 0))
3506 return print_unlock_imbalance_bug(curr, lock, ip);
3507
3508 /*
3509 * Check whether the lock exists in the current stack
3510 * of held locks:
3511 */
3512 prev_hlock = NULL;
3513 for (i = depth-1; i >= 0; i--) {
3514 hlock = curr->held_locks + i;
3515 /*
3516 * We must not cross into another context:
3517 */
3518 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3519 break;
3520 if (match_held_lock(hlock, lock))
3521 goto found_it;
3522 prev_hlock = hlock;
3523 }
3524 return print_unlock_imbalance_bug(curr, lock, ip);
3525
3526found_it:
3527 if (hlock->instance == lock)
3528 lock_release_holdtime(hlock);
3529
3530 WARN(hlock->pin_count, "releasing a pinned lock\n");
3531
3532 if (hlock->references) {
3533 hlock->references--;
3534 if (hlock->references) {
3535 /*
3536 * We had, and after removing one, still have
3537 * references, the current lock stack is still
3538 * valid. We're done!
3539 */
3540 return 1;
3541 }
3542 }
3543
3544 /*
3545 * We have the right lock to unlock, 'hlock' points to it.
3546 * Now we remove it from the stack, and add back the other
3547 * entries (if any), recalculating the hash along the way:
3548 */
3549
3550 curr->lockdep_depth = i;
3551 curr->curr_chain_key = hlock->prev_chain_key;
3552
3553 for (i++; i < depth; i++) {
3554 hlock = curr->held_locks + i;
3555 if (!__lock_acquire(hlock->instance,
3556 hlock_class(hlock)->subclass, hlock->trylock,
3557 hlock->read, hlock->check, hlock->hardirqs_off,
3558 hlock->nest_lock, hlock->acquire_ip,
3559 hlock->references, hlock->pin_count))
3560 return 0;
3561 }
3562
3563 /*
3564 * We had N bottles of beer on the wall, we drank one, but now
3565 * there's not N-1 bottles of beer left on the wall...
3566 */
3567 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3568 return 0;
3569
3570 return 1;
3571}
3572
3573static int __lock_is_held(struct lockdep_map *lock)
3574{
3575 struct task_struct *curr = current;
3576 int i;
3577
3578 for (i = 0; i < curr->lockdep_depth; i++) {
3579 struct held_lock *hlock = curr->held_locks + i;
3580
3581 if (match_held_lock(hlock, lock))
3582 return 1;
3583 }
3584
3585 return 0;
3586}
3587
3588static void __lock_pin_lock(struct lockdep_map *lock)
3589{
3590 struct task_struct *curr = current;
3591 int i;
3592
3593 if (unlikely(!debug_locks))
3594 return;
3595
3596 for (i = 0; i < curr->lockdep_depth; i++) {
3597 struct held_lock *hlock = curr->held_locks + i;
3598
3599 if (match_held_lock(hlock, lock)) {
3600 hlock->pin_count++;
3601 return;
3602 }
3603 }
3604
3605 WARN(1, "pinning an unheld lock\n");
3606}
3607
3608static void __lock_unpin_lock(struct lockdep_map *lock)
3609{
3610 struct task_struct *curr = current;
3611 int i;
3612
3613 if (unlikely(!debug_locks))
3614 return;
3615
3616 for (i = 0; i < curr->lockdep_depth; i++) {
3617 struct held_lock *hlock = curr->held_locks + i;
3618
3619 if (match_held_lock(hlock, lock)) {
3620 if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
3621 return;
3622
3623 hlock->pin_count--;
3624 return;
3625 }
3626 }
3627
3628 WARN(1, "unpinning an unheld lock\n");
3629}
3630
3631/*
3632 * Check whether we follow the irq-flags state precisely:
3633 */
3634static void check_flags(unsigned long flags)
3635{
3636#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3637 defined(CONFIG_TRACE_IRQFLAGS)
3638 if (!debug_locks)
3639 return;
3640
3641 if (irqs_disabled_flags(flags)) {
3642 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3643 printk("possible reason: unannotated irqs-off.\n");
3644 }
3645 } else {
3646 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3647 printk("possible reason: unannotated irqs-on.\n");
3648 }
3649 }
3650
3651 /*
3652 * We dont accurately track softirq state in e.g.
3653 * hardirq contexts (such as on 4KSTACKS), so only
3654 * check if not in hardirq contexts:
3655 */
3656 if (!hardirq_count()) {
3657 if (softirq_count()) {
3658 /* like the above, but with softirqs */
3659 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3660 } else {
3661 /* lick the above, does it taste good? */
3662 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3663 }
3664 }
3665
3666 if (!debug_locks)
3667 print_irqtrace_events(current);
3668#endif
3669}
3670
3671void lock_set_class(struct lockdep_map *lock, const char *name,
3672 struct lock_class_key *key, unsigned int subclass,
3673 unsigned long ip)
3674{
3675 unsigned long flags;
3676
3677 if (unlikely(current->lockdep_recursion))
3678 return;
3679
3680 raw_local_irq_save(flags);
3681 current->lockdep_recursion = 1;
3682 check_flags(flags);
3683 if (__lock_set_class(lock, name, key, subclass, ip))
3684 check_chain_key(current);
3685 current->lockdep_recursion = 0;
3686 raw_local_irq_restore(flags);
3687}
3688EXPORT_SYMBOL_GPL(lock_set_class);
3689
3690/*
3691 * We are not always called with irqs disabled - do that here,
3692 * and also avoid lockdep recursion:
3693 */
3694void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3695 int trylock, int read, int check,
3696 struct lockdep_map *nest_lock, unsigned long ip)
3697{
3698 unsigned long flags;
3699
3700 if (unlikely(current->lockdep_recursion))
3701 return;
3702
3703 raw_local_irq_save(flags);
3704 check_flags(flags);
3705
3706 current->lockdep_recursion = 1;
3707 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3708 __lock_acquire(lock, subclass, trylock, read, check,
3709 irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
3710 current->lockdep_recursion = 0;
3711 raw_local_irq_restore(flags);
3712}
3713EXPORT_SYMBOL_GPL(lock_acquire);
3714
3715void lock_release(struct lockdep_map *lock, int nested,
3716 unsigned long ip)
3717{
3718 unsigned long flags;
3719
3720 if (unlikely(current->lockdep_recursion))
3721 return;
3722
3723 raw_local_irq_save(flags);
3724 check_flags(flags);
3725 current->lockdep_recursion = 1;
3726 trace_lock_release(lock, ip);
3727 if (__lock_release(lock, nested, ip))
3728 check_chain_key(current);
3729 current->lockdep_recursion = 0;
3730 raw_local_irq_restore(flags);
3731}
3732EXPORT_SYMBOL_GPL(lock_release);
3733
3734int lock_is_held(struct lockdep_map *lock)
3735{
3736 unsigned long flags;
3737 int ret = 0;
3738
3739 if (unlikely(current->lockdep_recursion))
3740 return 1; /* avoid false negative lockdep_assert_held() */
3741
3742 raw_local_irq_save(flags);
3743 check_flags(flags);
3744
3745 current->lockdep_recursion = 1;
3746 ret = __lock_is_held(lock);
3747 current->lockdep_recursion = 0;
3748 raw_local_irq_restore(flags);
3749
3750 return ret;
3751}
3752EXPORT_SYMBOL_GPL(lock_is_held);
3753
3754void lock_pin_lock(struct lockdep_map *lock)
3755{
3756 unsigned long flags;
3757
3758 if (unlikely(current->lockdep_recursion))
3759 return;
3760
3761 raw_local_irq_save(flags);
3762 check_flags(flags);
3763
3764 current->lockdep_recursion = 1;
3765 __lock_pin_lock(lock);
3766 current->lockdep_recursion = 0;
3767 raw_local_irq_restore(flags);
3768}
3769EXPORT_SYMBOL_GPL(lock_pin_lock);
3770
3771void lock_unpin_lock(struct lockdep_map *lock)
3772{
3773 unsigned long flags;
3774
3775 if (unlikely(current->lockdep_recursion))
3776 return;
3777
3778 raw_local_irq_save(flags);
3779 check_flags(flags);
3780
3781 current->lockdep_recursion = 1;
3782 __lock_unpin_lock(lock);
3783 current->lockdep_recursion = 0;
3784 raw_local_irq_restore(flags);
3785}
3786EXPORT_SYMBOL_GPL(lock_unpin_lock);
3787
3788void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3789{
3790 current->lockdep_reclaim_gfp = gfp_mask;
3791}
3792
3793void lockdep_clear_current_reclaim_state(void)
3794{
3795 current->lockdep_reclaim_gfp = 0;
3796}
3797
3798#ifdef CONFIG_LOCK_STAT
3799static int
3800print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3801 unsigned long ip)
3802{
3803 if (!debug_locks_off())
3804 return 0;
3805 if (debug_locks_silent)
3806 return 0;
3807
3808 printk("\n");
3809 printk("=================================\n");
3810 printk("[ BUG: bad contention detected! ]\n");
3811 print_kernel_ident();
3812 printk("---------------------------------\n");
3813 printk("%s/%d is trying to contend lock (",
3814 curr->comm, task_pid_nr(curr));
3815 print_lockdep_cache(lock);
3816 printk(") at:\n");
3817 print_ip_sym(ip);
3818 printk("but there are no locks held!\n");
3819 printk("\nother info that might help us debug this:\n");
3820 lockdep_print_held_locks(curr);
3821
3822 printk("\nstack backtrace:\n");
3823 dump_stack();
3824
3825 return 0;
3826}
3827
3828static void
3829__lock_contended(struct lockdep_map *lock, unsigned long ip)
3830{
3831 struct task_struct *curr = current;
3832 struct held_lock *hlock, *prev_hlock;
3833 struct lock_class_stats *stats;
3834 unsigned int depth;
3835 int i, contention_point, contending_point;
3836
3837 depth = curr->lockdep_depth;
3838 /*
3839 * Whee, we contended on this lock, except it seems we're not
3840 * actually trying to acquire anything much at all..
3841 */
3842 if (DEBUG_LOCKS_WARN_ON(!depth))
3843 return;
3844
3845 prev_hlock = NULL;
3846 for (i = depth-1; i >= 0; i--) {
3847 hlock = curr->held_locks + i;
3848 /*
3849 * We must not cross into another context:
3850 */
3851 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3852 break;
3853 if (match_held_lock(hlock, lock))
3854 goto found_it;
3855 prev_hlock = hlock;
3856 }
3857 print_lock_contention_bug(curr, lock, ip);
3858 return;
3859
3860found_it:
3861 if (hlock->instance != lock)
3862 return;
3863
3864 hlock->waittime_stamp = lockstat_clock();
3865
3866 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3867 contending_point = lock_point(hlock_class(hlock)->contending_point,
3868 lock->ip);
3869
3870 stats = get_lock_stats(hlock_class(hlock));
3871 if (contention_point < LOCKSTAT_POINTS)
3872 stats->contention_point[contention_point]++;
3873 if (contending_point < LOCKSTAT_POINTS)
3874 stats->contending_point[contending_point]++;
3875 if (lock->cpu != smp_processor_id())
3876 stats->bounces[bounce_contended + !!hlock->read]++;
3877 put_lock_stats(stats);
3878}
3879
3880static void
3881__lock_acquired(struct lockdep_map *lock, unsigned long ip)
3882{
3883 struct task_struct *curr = current;
3884 struct held_lock *hlock, *prev_hlock;
3885 struct lock_class_stats *stats;
3886 unsigned int depth;
3887 u64 now, waittime = 0;
3888 int i, cpu;
3889
3890 depth = curr->lockdep_depth;
3891 /*
3892 * Yay, we acquired ownership of this lock we didn't try to
3893 * acquire, how the heck did that happen?
3894 */
3895 if (DEBUG_LOCKS_WARN_ON(!depth))
3896 return;
3897
3898 prev_hlock = NULL;
3899 for (i = depth-1; i >= 0; i--) {
3900 hlock = curr->held_locks + i;
3901 /*
3902 * We must not cross into another context:
3903 */
3904 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3905 break;
3906 if (match_held_lock(hlock, lock))
3907 goto found_it;
3908 prev_hlock = hlock;
3909 }
3910 print_lock_contention_bug(curr, lock, _RET_IP_);
3911 return;
3912
3913found_it:
3914 if (hlock->instance != lock)
3915 return;
3916
3917 cpu = smp_processor_id();
3918 if (hlock->waittime_stamp) {
3919 now = lockstat_clock();
3920 waittime = now - hlock->waittime_stamp;
3921 hlock->holdtime_stamp = now;
3922 }
3923
3924 trace_lock_acquired(lock, ip);
3925
3926 stats = get_lock_stats(hlock_class(hlock));
3927 if (waittime) {
3928 if (hlock->read)
3929 lock_time_inc(&stats->read_waittime, waittime);
3930 else
3931 lock_time_inc(&stats->write_waittime, waittime);
3932 }
3933 if (lock->cpu != cpu)
3934 stats->bounces[bounce_acquired + !!hlock->read]++;
3935 put_lock_stats(stats);
3936
3937 lock->cpu = cpu;
3938 lock->ip = ip;
3939}
3940
3941void lock_contended(struct lockdep_map *lock, unsigned long ip)
3942{
3943 unsigned long flags;
3944
3945 if (unlikely(!lock_stat))
3946 return;
3947
3948 if (unlikely(current->lockdep_recursion))
3949 return;
3950
3951 raw_local_irq_save(flags);
3952 check_flags(flags);
3953 current->lockdep_recursion = 1;
3954 trace_lock_contended(lock, ip);
3955 __lock_contended(lock, ip);
3956 current->lockdep_recursion = 0;
3957 raw_local_irq_restore(flags);
3958}
3959EXPORT_SYMBOL_GPL(lock_contended);
3960
3961void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3962{
3963 unsigned long flags;
3964
3965 if (unlikely(!lock_stat))
3966 return;
3967
3968 if (unlikely(current->lockdep_recursion))
3969 return;
3970
3971 raw_local_irq_save(flags);
3972 check_flags(flags);
3973 current->lockdep_recursion = 1;
3974 __lock_acquired(lock, ip);
3975 current->lockdep_recursion = 0;
3976 raw_local_irq_restore(flags);
3977}
3978EXPORT_SYMBOL_GPL(lock_acquired);
3979#endif
3980
3981/*
3982 * Used by the testsuite, sanitize the validator state
3983 * after a simulated failure:
3984 */
3985
3986void lockdep_reset(void)
3987{
3988 unsigned long flags;
3989 int i;
3990
3991 raw_local_irq_save(flags);
3992 current->curr_chain_key = 0;
3993 current->lockdep_depth = 0;
3994 current->lockdep_recursion = 0;
3995 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3996 nr_hardirq_chains = 0;
3997 nr_softirq_chains = 0;
3998 nr_process_chains = 0;
3999 debug_locks = 1;
4000 for (i = 0; i < CHAINHASH_SIZE; i++)
4001 INIT_HLIST_HEAD(chainhash_table + i);
4002 raw_local_irq_restore(flags);
4003}
4004
4005static void zap_class(struct lock_class *class)
4006{
4007 int i;
4008
4009 /*
4010 * Remove all dependencies this lock is
4011 * involved in:
4012 */
4013 for (i = 0; i < nr_list_entries; i++) {
4014 if (list_entries[i].class == class)
4015 list_del_rcu(&list_entries[i].entry);
4016 }
4017 /*
4018 * Unhash the class and remove it from the all_lock_classes list:
4019 */
4020 hlist_del_rcu(&class->hash_entry);
4021 list_del_rcu(&class->lock_entry);
4022
4023 RCU_INIT_POINTER(class->key, NULL);
4024 RCU_INIT_POINTER(class->name, NULL);
4025}
4026
4027static inline int within(const void *addr, void *start, unsigned long size)
4028{
4029 return addr >= start && addr < start + size;
4030}
4031
4032/*
4033 * Used in module.c to remove lock classes from memory that is going to be
4034 * freed; and possibly re-used by other modules.
4035 *
4036 * We will have had one sync_sched() before getting here, so we're guaranteed
4037 * nobody will look up these exact classes -- they're properly dead but still
4038 * allocated.
4039 */
4040void lockdep_free_key_range(void *start, unsigned long size)
4041{
4042 struct lock_class *class;
4043 struct hlist_head *head;
4044 unsigned long flags;
4045 int i;
4046 int locked;
4047
4048 raw_local_irq_save(flags);
4049 locked = graph_lock();
4050
4051 /*
4052 * Unhash all classes that were created by this module:
4053 */
4054 for (i = 0; i < CLASSHASH_SIZE; i++) {
4055 head = classhash_table + i;
4056 hlist_for_each_entry_rcu(class, head, hash_entry) {
4057 if (within(class->key, start, size))
4058 zap_class(class);
4059 else if (within(class->name, start, size))
4060 zap_class(class);
4061 }
4062 }
4063
4064 if (locked)
4065 graph_unlock();
4066 raw_local_irq_restore(flags);
4067
4068 /*
4069 * Wait for any possible iterators from look_up_lock_class() to pass
4070 * before continuing to free the memory they refer to.
4071 *
4072 * sync_sched() is sufficient because the read-side is IRQ disable.
4073 */
4074 synchronize_sched();
4075
4076 /*
4077 * XXX at this point we could return the resources to the pool;
4078 * instead we leak them. We would need to change to bitmap allocators
4079 * instead of the linear allocators we have now.
4080 */
4081}
4082
4083void lockdep_reset_lock(struct lockdep_map *lock)
4084{
4085 struct lock_class *class;
4086 struct hlist_head *head;
4087 unsigned long flags;
4088 int i, j;
4089 int locked;
4090
4091 raw_local_irq_save(flags);
4092
4093 /*
4094 * Remove all classes this lock might have:
4095 */
4096 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
4097 /*
4098 * If the class exists we look it up and zap it:
4099 */
4100 class = look_up_lock_class(lock, j);
4101 if (class)
4102 zap_class(class);
4103 }
4104 /*
4105 * Debug check: in the end all mapped classes should
4106 * be gone.
4107 */
4108 locked = graph_lock();
4109 for (i = 0; i < CLASSHASH_SIZE; i++) {
4110 head = classhash_table + i;
4111 hlist_for_each_entry_rcu(class, head, hash_entry) {
4112 int match = 0;
4113
4114 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
4115 match |= class == lock->class_cache[j];
4116
4117 if (unlikely(match)) {
4118 if (debug_locks_off_graph_unlock()) {
4119 /*
4120 * We all just reset everything, how did it match?
4121 */
4122 WARN_ON(1);
4123 }
4124 goto out_restore;
4125 }
4126 }
4127 }
4128 if (locked)
4129 graph_unlock();
4130
4131out_restore:
4132 raw_local_irq_restore(flags);
4133}
4134
4135void __init lockdep_info(void)
4136{
4137 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
4138
4139 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
4140 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
4141 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
4142 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
4143 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
4144 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
4145 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
4146
4147 printk(" memory used by lock dependency info: %lu kB\n",
4148 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4149 sizeof(struct list_head) * CLASSHASH_SIZE +
4150 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4151 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
4152 sizeof(struct list_head) * CHAINHASH_SIZE
4153#ifdef CONFIG_PROVE_LOCKING
4154 + sizeof(struct circular_queue)
4155#endif
4156 ) / 1024
4157 );
4158
4159 printk(" per task-struct memory footprint: %lu bytes\n",
4160 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4161}
4162
4163static void
4164print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4165 const void *mem_to, struct held_lock *hlock)
4166{
4167 if (!debug_locks_off())
4168 return;
4169 if (debug_locks_silent)
4170 return;
4171
4172 printk("\n");
4173 printk("=========================\n");
4174 printk("[ BUG: held lock freed! ]\n");
4175 print_kernel_ident();
4176 printk("-------------------------\n");
4177 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4178 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4179 print_lock(hlock);
4180 lockdep_print_held_locks(curr);
4181
4182 printk("\nstack backtrace:\n");
4183 dump_stack();
4184}
4185
4186static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4187 const void* lock_from, unsigned long lock_len)
4188{
4189 return lock_from + lock_len <= mem_from ||
4190 mem_from + mem_len <= lock_from;
4191}
4192
4193/*
4194 * Called when kernel memory is freed (or unmapped), or if a lock
4195 * is destroyed or reinitialized - this code checks whether there is
4196 * any held lock in the memory range of <from> to <to>:
4197 */
4198void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4199{
4200 struct task_struct *curr = current;
4201 struct held_lock *hlock;
4202 unsigned long flags;
4203 int i;
4204
4205 if (unlikely(!debug_locks))
4206 return;
4207
4208 local_irq_save(flags);
4209 for (i = 0; i < curr->lockdep_depth; i++) {
4210 hlock = curr->held_locks + i;
4211
4212 if (not_in_range(mem_from, mem_len, hlock->instance,
4213 sizeof(*hlock->instance)))
4214 continue;
4215
4216 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4217 break;
4218 }
4219 local_irq_restore(flags);
4220}
4221EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4222
4223static void print_held_locks_bug(void)
4224{
4225 if (!debug_locks_off())
4226 return;
4227 if (debug_locks_silent)
4228 return;
4229
4230 printk("\n");
4231 printk("=====================================\n");
4232 printk("[ BUG: %s/%d still has locks held! ]\n",
4233 current->comm, task_pid_nr(current));
4234 print_kernel_ident();
4235 printk("-------------------------------------\n");
4236 lockdep_print_held_locks(current);
4237 printk("\nstack backtrace:\n");
4238 dump_stack();
4239}
4240
4241void debug_check_no_locks_held(void)
4242{
4243 if (unlikely(current->lockdep_depth > 0))
4244 print_held_locks_bug();
4245}
4246EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
4247
4248#ifdef __KERNEL__
4249void debug_show_all_locks(void)
4250{
4251 struct task_struct *g, *p;
4252 int count = 10;
4253 int unlock = 1;
4254
4255 if (unlikely(!debug_locks)) {
4256 printk("INFO: lockdep is turned off.\n");
4257 return;
4258 }
4259 printk("\nShowing all locks held in the system:\n");
4260
4261 /*
4262 * Here we try to get the tasklist_lock as hard as possible,
4263 * if not successful after 2 seconds we ignore it (but keep
4264 * trying). This is to enable a debug printout even if a
4265 * tasklist_lock-holding task deadlocks or crashes.
4266 */
4267retry:
4268 if (!read_trylock(&tasklist_lock)) {
4269 if (count == 10)
4270 printk("hm, tasklist_lock locked, retrying... ");
4271 if (count) {
4272 count--;
4273 printk(" #%d", 10-count);
4274 mdelay(200);
4275 goto retry;
4276 }
4277 printk(" ignoring it.\n");
4278 unlock = 0;
4279 } else {
4280 if (count != 10)
4281 printk(KERN_CONT " locked it.\n");
4282 }
4283
4284 do_each_thread(g, p) {
4285 /*
4286 * It's not reliable to print a task's held locks
4287 * if it's not sleeping (or if it's not the current
4288 * task):
4289 */
4290 if (p->state == TASK_RUNNING && p != current)
4291 continue;
4292 if (p->lockdep_depth)
4293 lockdep_print_held_locks(p);
4294 if (!unlock)
4295 if (read_trylock(&tasklist_lock))
4296 unlock = 1;
4297 } while_each_thread(g, p);
4298
4299 printk("\n");
4300 printk("=============================================\n\n");
4301
4302 if (unlock)
4303 read_unlock(&tasklist_lock);
4304}
4305EXPORT_SYMBOL_GPL(debug_show_all_locks);
4306#endif
4307
4308/*
4309 * Careful: only use this function if you are sure that
4310 * the task cannot run in parallel!
4311 */
4312void debug_show_held_locks(struct task_struct *task)
4313{
4314 if (unlikely(!debug_locks)) {
4315 printk("INFO: lockdep is turned off.\n");
4316 return;
4317 }
4318 lockdep_print_held_locks(task);
4319}
4320EXPORT_SYMBOL_GPL(debug_show_held_locks);
4321
4322asmlinkage __visible void lockdep_sys_exit(void)
4323{
4324 struct task_struct *curr = current;
4325
4326 if (unlikely(curr->lockdep_depth)) {
4327 if (!debug_locks_off())
4328 return;
4329 printk("\n");
4330 printk("================================================\n");
4331 printk("[ BUG: lock held when returning to user space! ]\n");
4332 print_kernel_ident();
4333 printk("------------------------------------------------\n");
4334 printk("%s/%d is leaving the kernel with locks still held!\n",
4335 curr->comm, curr->pid);
4336 lockdep_print_held_locks(curr);
4337 }
4338}
4339
4340void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4341{
4342 struct task_struct *curr = current;
4343
4344#ifndef CONFIG_PROVE_RCU_REPEATEDLY
4345 if (!debug_locks_off())
4346 return;
4347#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4348 /* Note: the following can be executed concurrently, so be careful. */
4349 printk("\n");
4350 printk("===============================\n");
4351 printk("[ INFO: suspicious RCU usage. ]\n");
4352 print_kernel_ident();
4353 printk("-------------------------------\n");
4354 printk("%s:%d %s!\n", file, line, s);
4355 printk("\nother info that might help us debug this:\n\n");
4356 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4357 !rcu_lockdep_current_cpu_online()
4358 ? "RCU used illegally from offline CPU!\n"
4359 : !rcu_is_watching()
4360 ? "RCU used illegally from idle CPU!\n"
4361 : "",
4362 rcu_scheduler_active, debug_locks);
4363
4364 /*
4365 * If a CPU is in the RCU-free window in idle (ie: in the section
4366 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4367 * considers that CPU to be in an "extended quiescent state",
4368 * which means that RCU will be completely ignoring that CPU.
4369 * Therefore, rcu_read_lock() and friends have absolutely no
4370 * effect on a CPU running in that state. In other words, even if
4371 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4372 * delete data structures out from under it. RCU really has no
4373 * choice here: we need to keep an RCU-free window in idle where
4374 * the CPU may possibly enter into low power mode. This way we can
4375 * notice an extended quiescent state to other CPUs that started a grace
4376 * period. Otherwise we would delay any grace period as long as we run
4377 * in the idle task.
4378 *
4379 * So complain bitterly if someone does call rcu_read_lock(),
4380 * rcu_read_lock_bh() and so on from extended quiescent states.
4381 */
4382 if (!rcu_is_watching())
4383 printk("RCU used illegally from extended quiescent state!\n");
4384
4385 lockdep_print_held_locks(curr);
4386 printk("\nstack backtrace:\n");
4387 dump_stack();
4388}
4389EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);