lockdep: BFS cleanup
[linux-2.6.git] / kernel / lockdep.c
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 <pzijlstr@redhat.com>
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
47 #include <asm/sections.h>
48
49 #include "lockdep_internals.h"
50
51 #define CREATE_TRACE_POINTS
52 #include <trace/events/lockdep.h>
53
54 #ifdef CONFIG_PROVE_LOCKING
55 int prove_locking = 1;
56 module_param(prove_locking, int, 0644);
57 #else
58 #define prove_locking 0
59 #endif
60
61 #ifdef CONFIG_LOCK_STAT
62 int lock_stat = 1;
63 module_param(lock_stat, int, 0644);
64 #else
65 #define lock_stat 0
66 #endif
67
68 /*
69  * lockdep_lock: protects the lockdep graph, the hashes and the
70  *               class/list/hash allocators.
71  *
72  * This is one of the rare exceptions where it's justified
73  * to use a raw spinlock - we really dont want the spinlock
74  * code to recurse back into the lockdep code...
75  */
76 static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
77
78 static int graph_lock(void)
79 {
80         __raw_spin_lock(&lockdep_lock);
81         /*
82          * Make sure that if another CPU detected a bug while
83          * walking the graph we dont change it (while the other
84          * CPU is busy printing out stuff with the graph lock
85          * dropped already)
86          */
87         if (!debug_locks) {
88                 __raw_spin_unlock(&lockdep_lock);
89                 return 0;
90         }
91         /* prevent any recursions within lockdep from causing deadlocks */
92         current->lockdep_recursion++;
93         return 1;
94 }
95
96 static inline int graph_unlock(void)
97 {
98         if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
99                 return DEBUG_LOCKS_WARN_ON(1);
100
101         current->lockdep_recursion--;
102         __raw_spin_unlock(&lockdep_lock);
103         return 0;
104 }
105
106 /*
107  * Turn lock debugging off and return with 0 if it was off already,
108  * and also release the graph lock:
109  */
110 static inline int debug_locks_off_graph_unlock(void)
111 {
112         int ret = debug_locks_off();
113
114         __raw_spin_unlock(&lockdep_lock);
115
116         return ret;
117 }
118
119 static int lockdep_initialized;
120
121 unsigned long nr_list_entries;
122 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
123
124 /*
125  * All data structures here are protected by the global debug_lock.
126  *
127  * Mutex key structs only get allocated, once during bootup, and never
128  * get freed - this significantly simplifies the debugging code.
129  */
130 unsigned long nr_lock_classes;
131 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
132
133 static inline struct lock_class *hlock_class(struct held_lock *hlock)
134 {
135         if (!hlock->class_idx) {
136                 DEBUG_LOCKS_WARN_ON(1);
137                 return NULL;
138         }
139         return lock_classes + hlock->class_idx - 1;
140 }
141
142 #ifdef CONFIG_LOCK_STAT
143 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
144
145 static int lock_point(unsigned long points[], unsigned long ip)
146 {
147         int i;
148
149         for (i = 0; i < LOCKSTAT_POINTS; i++) {
150                 if (points[i] == 0) {
151                         points[i] = ip;
152                         break;
153                 }
154                 if (points[i] == ip)
155                         break;
156         }
157
158         return i;
159 }
160
161 static void lock_time_inc(struct lock_time *lt, s64 time)
162 {
163         if (time > lt->max)
164                 lt->max = time;
165
166         if (time < lt->min || !lt->min)
167                 lt->min = time;
168
169         lt->total += time;
170         lt->nr++;
171 }
172
173 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
174 {
175         dst->min += src->min;
176         dst->max += src->max;
177         dst->total += src->total;
178         dst->nr += src->nr;
179 }
180
181 struct lock_class_stats lock_stats(struct lock_class *class)
182 {
183         struct lock_class_stats stats;
184         int cpu, i;
185
186         memset(&stats, 0, sizeof(struct lock_class_stats));
187         for_each_possible_cpu(cpu) {
188                 struct lock_class_stats *pcs =
189                         &per_cpu(lock_stats, cpu)[class - lock_classes];
190
191                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
192                         stats.contention_point[i] += pcs->contention_point[i];
193
194                 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
195                         stats.contending_point[i] += pcs->contending_point[i];
196
197                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
198                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
199
200                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
201                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
202
203                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
204                         stats.bounces[i] += pcs->bounces[i];
205         }
206
207         return stats;
208 }
209
210 void clear_lock_stats(struct lock_class *class)
211 {
212         int cpu;
213
214         for_each_possible_cpu(cpu) {
215                 struct lock_class_stats *cpu_stats =
216                         &per_cpu(lock_stats, cpu)[class - lock_classes];
217
218                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
219         }
220         memset(class->contention_point, 0, sizeof(class->contention_point));
221         memset(class->contending_point, 0, sizeof(class->contending_point));
222 }
223
224 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
225 {
226         return &get_cpu_var(lock_stats)[class - lock_classes];
227 }
228
229 static void put_lock_stats(struct lock_class_stats *stats)
230 {
231         put_cpu_var(lock_stats);
232 }
233
234 static void lock_release_holdtime(struct held_lock *hlock)
235 {
236         struct lock_class_stats *stats;
237         s64 holdtime;
238
239         if (!lock_stat)
240                 return;
241
242         holdtime = sched_clock() - hlock->holdtime_stamp;
243
244         stats = get_lock_stats(hlock_class(hlock));
245         if (hlock->read)
246                 lock_time_inc(&stats->read_holdtime, holdtime);
247         else
248                 lock_time_inc(&stats->write_holdtime, holdtime);
249         put_lock_stats(stats);
250 }
251 #else
252 static inline void lock_release_holdtime(struct held_lock *hlock)
253 {
254 }
255 #endif
256
257 /*
258  * We keep a global list of all lock classes. The list only grows,
259  * never shrinks. The list is only accessed with the lockdep
260  * spinlock lock held.
261  */
262 LIST_HEAD(all_lock_classes);
263
264 /*
265  * The lockdep classes are in a hash-table as well, for fast lookup:
266  */
267 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
268 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
269 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
270 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
271
272 static struct list_head classhash_table[CLASSHASH_SIZE];
273
274 /*
275  * We put the lock dependency chains into a hash-table as well, to cache
276  * their existence:
277  */
278 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
279 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
280 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
281 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
282
283 static struct list_head chainhash_table[CHAINHASH_SIZE];
284
285 /*
286  * The hash key of the lock dependency chains is a hash itself too:
287  * it's a hash of all locks taken up to that lock, including that lock.
288  * It's a 64-bit hash, because it's important for the keys to be
289  * unique.
290  */
291 #define iterate_chain_key(key1, key2) \
292         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
293         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
294         (key2))
295
296 void lockdep_off(void)
297 {
298         current->lockdep_recursion++;
299 }
300 EXPORT_SYMBOL(lockdep_off);
301
302 void lockdep_on(void)
303 {
304         current->lockdep_recursion--;
305 }
306 EXPORT_SYMBOL(lockdep_on);
307
308 /*
309  * Debugging switches:
310  */
311
312 #define VERBOSE                 0
313 #define VERY_VERBOSE            0
314
315 #if VERBOSE
316 # define HARDIRQ_VERBOSE        1
317 # define SOFTIRQ_VERBOSE        1
318 # define RECLAIM_VERBOSE        1
319 #else
320 # define HARDIRQ_VERBOSE        0
321 # define SOFTIRQ_VERBOSE        0
322 # define RECLAIM_VERBOSE        0
323 #endif
324
325 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
326 /*
327  * Quick filtering for interesting events:
328  */
329 static int class_filter(struct lock_class *class)
330 {
331 #if 0
332         /* Example */
333         if (class->name_version == 1 &&
334                         !strcmp(class->name, "lockname"))
335                 return 1;
336         if (class->name_version == 1 &&
337                         !strcmp(class->name, "&struct->lockfield"))
338                 return 1;
339 #endif
340         /* Filter everything else. 1 would be to allow everything else */
341         return 0;
342 }
343 #endif
344
345 static int verbose(struct lock_class *class)
346 {
347 #if VERBOSE
348         return class_filter(class);
349 #endif
350         return 0;
351 }
352
353 /*
354  * Stack-trace: tightly packed array of stack backtrace
355  * addresses. Protected by the graph_lock.
356  */
357 unsigned long nr_stack_trace_entries;
358 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
359
360 static int save_trace(struct stack_trace *trace)
361 {
362         trace->nr_entries = 0;
363         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
364         trace->entries = stack_trace + nr_stack_trace_entries;
365
366         trace->skip = 3;
367
368         save_stack_trace(trace);
369
370         trace->max_entries = trace->nr_entries;
371
372         nr_stack_trace_entries += trace->nr_entries;
373
374         if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
375                 if (!debug_locks_off_graph_unlock())
376                         return 0;
377
378                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
379                 printk("turning off the locking correctness validator.\n");
380                 dump_stack();
381
382                 return 0;
383         }
384
385         return 1;
386 }
387
388 unsigned int nr_hardirq_chains;
389 unsigned int nr_softirq_chains;
390 unsigned int nr_process_chains;
391 unsigned int max_lockdep_depth;
392 unsigned int max_recursion_depth;
393
394 #ifdef CONFIG_DEBUG_LOCKDEP
395 /*
396  * We cannot printk in early bootup code. Not even early_printk()
397  * might work. So we mark any initialization errors and printk
398  * about it later on, in lockdep_info().
399  */
400 static int lockdep_init_error;
401 static unsigned long lockdep_init_trace_data[20];
402 static struct stack_trace lockdep_init_trace = {
403         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
404         .entries = lockdep_init_trace_data,
405 };
406
407 /*
408  * Various lockdep statistics:
409  */
410 atomic_t chain_lookup_hits;
411 atomic_t chain_lookup_misses;
412 atomic_t hardirqs_on_events;
413 atomic_t hardirqs_off_events;
414 atomic_t redundant_hardirqs_on;
415 atomic_t redundant_hardirqs_off;
416 atomic_t softirqs_on_events;
417 atomic_t softirqs_off_events;
418 atomic_t redundant_softirqs_on;
419 atomic_t redundant_softirqs_off;
420 atomic_t nr_unused_locks;
421 atomic_t nr_cyclic_checks;
422 atomic_t nr_cyclic_check_recursions;
423 atomic_t nr_find_usage_forwards_checks;
424 atomic_t nr_find_usage_forwards_recursions;
425 atomic_t nr_find_usage_backwards_checks;
426 atomic_t nr_find_usage_backwards_recursions;
427 #endif
428
429 /*
430  * Locking printouts:
431  */
432
433 #define __USAGE(__STATE)                                                \
434         [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
435         [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
436         [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
437         [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
438
439 static const char *usage_str[] =
440 {
441 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
442 #include "lockdep_states.h"
443 #undef LOCKDEP_STATE
444         [LOCK_USED] = "INITIAL USE",
445 };
446
447 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
448 {
449         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
450 }
451
452 static inline unsigned long lock_flag(enum lock_usage_bit bit)
453 {
454         return 1UL << bit;
455 }
456
457 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
458 {
459         char c = '.';
460
461         if (class->usage_mask & lock_flag(bit + 2))
462                 c = '+';
463         if (class->usage_mask & lock_flag(bit)) {
464                 c = '-';
465                 if (class->usage_mask & lock_flag(bit + 2))
466                         c = '?';
467         }
468
469         return c;
470 }
471
472 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
473 {
474         int i = 0;
475
476 #define LOCKDEP_STATE(__STATE)                                          \
477         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
478         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
479 #include "lockdep_states.h"
480 #undef LOCKDEP_STATE
481
482         usage[i] = '\0';
483 }
484
485 static void print_lock_name(struct lock_class *class)
486 {
487         char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
488         const char *name;
489
490         get_usage_chars(class, usage);
491
492         name = class->name;
493         if (!name) {
494                 name = __get_key_name(class->key, str);
495                 printk(" (%s", name);
496         } else {
497                 printk(" (%s", name);
498                 if (class->name_version > 1)
499                         printk("#%d", class->name_version);
500                 if (class->subclass)
501                         printk("/%d", class->subclass);
502         }
503         printk("){%s}", usage);
504 }
505
506 static void print_lockdep_cache(struct lockdep_map *lock)
507 {
508         const char *name;
509         char str[KSYM_NAME_LEN];
510
511         name = lock->name;
512         if (!name)
513                 name = __get_key_name(lock->key->subkeys, str);
514
515         printk("%s", name);
516 }
517
518 static void print_lock(struct held_lock *hlock)
519 {
520         print_lock_name(hlock_class(hlock));
521         printk(", at: ");
522         print_ip_sym(hlock->acquire_ip);
523 }
524
525 static void lockdep_print_held_locks(struct task_struct *curr)
526 {
527         int i, depth = curr->lockdep_depth;
528
529         if (!depth) {
530                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
531                 return;
532         }
533         printk("%d lock%s held by %s/%d:\n",
534                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
535
536         for (i = 0; i < depth; i++) {
537                 printk(" #%d: ", i);
538                 print_lock(curr->held_locks + i);
539         }
540 }
541
542 static void print_kernel_version(void)
543 {
544         printk("%s %.*s\n", init_utsname()->release,
545                 (int)strcspn(init_utsname()->version, " "),
546                 init_utsname()->version);
547 }
548
549 static int very_verbose(struct lock_class *class)
550 {
551 #if VERY_VERBOSE
552         return class_filter(class);
553 #endif
554         return 0;
555 }
556
557 /*
558  * Is this the address of a static object:
559  */
560 static int static_obj(void *obj)
561 {
562         unsigned long start = (unsigned long) &_stext,
563                       end   = (unsigned long) &_end,
564                       addr  = (unsigned long) obj;
565 #ifdef CONFIG_SMP
566         int i;
567 #endif
568
569         /*
570          * static variable?
571          */
572         if ((addr >= start) && (addr < end))
573                 return 1;
574
575 #ifdef CONFIG_SMP
576         /*
577          * percpu var?
578          */
579         for_each_possible_cpu(i) {
580                 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
581                 end   = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
582                                         + per_cpu_offset(i);
583
584                 if ((addr >= start) && (addr < end))
585                         return 1;
586         }
587 #endif
588
589         /*
590          * module var?
591          */
592         return is_module_address(addr);
593 }
594
595 /*
596  * To make lock name printouts unique, we calculate a unique
597  * class->name_version generation counter:
598  */
599 static int count_matching_names(struct lock_class *new_class)
600 {
601         struct lock_class *class;
602         int count = 0;
603
604         if (!new_class->name)
605                 return 0;
606
607         list_for_each_entry(class, &all_lock_classes, lock_entry) {
608                 if (new_class->key - new_class->subclass == class->key)
609                         return class->name_version;
610                 if (class->name && !strcmp(class->name, new_class->name))
611                         count = max(count, class->name_version);
612         }
613
614         return count + 1;
615 }
616
617 /*
618  * Register a lock's class in the hash-table, if the class is not present
619  * yet. Otherwise we look it up. We cache the result in the lock object
620  * itself, so actual lookup of the hash should be once per lock object.
621  */
622 static inline struct lock_class *
623 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
624 {
625         struct lockdep_subclass_key *key;
626         struct list_head *hash_head;
627         struct lock_class *class;
628
629 #ifdef CONFIG_DEBUG_LOCKDEP
630         /*
631          * If the architecture calls into lockdep before initializing
632          * the hashes then we'll warn about it later. (we cannot printk
633          * right now)
634          */
635         if (unlikely(!lockdep_initialized)) {
636                 lockdep_init();
637                 lockdep_init_error = 1;
638                 save_stack_trace(&lockdep_init_trace);
639         }
640 #endif
641
642         /*
643          * Static locks do not have their class-keys yet - for them the key
644          * is the lock object itself:
645          */
646         if (unlikely(!lock->key))
647                 lock->key = (void *)lock;
648
649         /*
650          * NOTE: the class-key must be unique. For dynamic locks, a static
651          * lock_class_key variable is passed in through the mutex_init()
652          * (or spin_lock_init()) call - which acts as the key. For static
653          * locks we use the lock object itself as the key.
654          */
655         BUILD_BUG_ON(sizeof(struct lock_class_key) >
656                         sizeof(struct lockdep_map));
657
658         key = lock->key->subkeys + subclass;
659
660         hash_head = classhashentry(key);
661
662         /*
663          * We can walk the hash lockfree, because the hash only
664          * grows, and we are careful when adding entries to the end:
665          */
666         list_for_each_entry(class, hash_head, hash_entry) {
667                 if (class->key == key) {
668                         WARN_ON_ONCE(class->name != lock->name);
669                         return class;
670                 }
671         }
672
673         return NULL;
674 }
675
676 /*
677  * Register a lock's class in the hash-table, if the class is not present
678  * yet. Otherwise we look it up. We cache the result in the lock object
679  * itself, so actual lookup of the hash should be once per lock object.
680  */
681 static inline struct lock_class *
682 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
683 {
684         struct lockdep_subclass_key *key;
685         struct list_head *hash_head;
686         struct lock_class *class;
687         unsigned long flags;
688
689         class = look_up_lock_class(lock, subclass);
690         if (likely(class))
691                 return class;
692
693         /*
694          * Debug-check: all keys must be persistent!
695          */
696         if (!static_obj(lock->key)) {
697                 debug_locks_off();
698                 printk("INFO: trying to register non-static key.\n");
699                 printk("the code is fine but needs lockdep annotation.\n");
700                 printk("turning off the locking correctness validator.\n");
701                 dump_stack();
702
703                 return NULL;
704         }
705
706         key = lock->key->subkeys + subclass;
707         hash_head = classhashentry(key);
708
709         raw_local_irq_save(flags);
710         if (!graph_lock()) {
711                 raw_local_irq_restore(flags);
712                 return NULL;
713         }
714         /*
715          * We have to do the hash-walk again, to avoid races
716          * with another CPU:
717          */
718         list_for_each_entry(class, hash_head, hash_entry)
719                 if (class->key == key)
720                         goto out_unlock_set;
721         /*
722          * Allocate a new key from the static array, and add it to
723          * the hash:
724          */
725         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
726                 if (!debug_locks_off_graph_unlock()) {
727                         raw_local_irq_restore(flags);
728                         return NULL;
729                 }
730                 raw_local_irq_restore(flags);
731
732                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
733                 printk("turning off the locking correctness validator.\n");
734                 dump_stack();
735                 return NULL;
736         }
737         class = lock_classes + nr_lock_classes++;
738         debug_atomic_inc(&nr_unused_locks);
739         class->key = key;
740         class->name = lock->name;
741         class->subclass = subclass;
742         INIT_LIST_HEAD(&class->lock_entry);
743         INIT_LIST_HEAD(&class->locks_before);
744         INIT_LIST_HEAD(&class->locks_after);
745         class->name_version = count_matching_names(class);
746         /*
747          * We use RCU's safe list-add method to make
748          * parallel walking of the hash-list safe:
749          */
750         list_add_tail_rcu(&class->hash_entry, hash_head);
751         /*
752          * Add it to the global list of classes:
753          */
754         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
755
756         if (verbose(class)) {
757                 graph_unlock();
758                 raw_local_irq_restore(flags);
759
760                 printk("\nnew class %p: %s", class->key, class->name);
761                 if (class->name_version > 1)
762                         printk("#%d", class->name_version);
763                 printk("\n");
764                 dump_stack();
765
766                 raw_local_irq_save(flags);
767                 if (!graph_lock()) {
768                         raw_local_irq_restore(flags);
769                         return NULL;
770                 }
771         }
772 out_unlock_set:
773         graph_unlock();
774         raw_local_irq_restore(flags);
775
776         if (!subclass || force)
777                 lock->class_cache = class;
778
779         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
780                 return NULL;
781
782         return class;
783 }
784
785 #ifdef CONFIG_PROVE_LOCKING
786 /*
787  * Allocate a lockdep entry. (assumes the graph_lock held, returns
788  * with NULL on failure)
789  */
790 static struct lock_list *alloc_list_entry(void)
791 {
792         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
793                 if (!debug_locks_off_graph_unlock())
794                         return NULL;
795
796                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
797                 printk("turning off the locking correctness validator.\n");
798                 dump_stack();
799                 return NULL;
800         }
801         return list_entries + nr_list_entries++;
802 }
803
804 /*
805  * Add a new dependency to the head of the list:
806  */
807 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
808                             struct list_head *head, unsigned long ip, int distance)
809 {
810         struct lock_list *entry;
811         /*
812          * Lock not present yet - get a new dependency struct and
813          * add it to the list:
814          */
815         entry = alloc_list_entry();
816         if (!entry)
817                 return 0;
818
819         if (!save_trace(&entry->trace))
820                 return 0;
821
822         entry->class = this;
823         entry->distance = distance;
824         /*
825          * Since we never remove from the dependency list, the list can
826          * be walked lockless by other CPUs, it's only allocation
827          * that must be protected by the spinlock. But this also means
828          * we must make new entries visible only once writes to the
829          * entry become visible - hence the RCU op:
830          */
831         list_add_tail_rcu(&entry->entry, head);
832
833         return 1;
834 }
835
836 /*For good efficiency of modular, we use power of 2*/
837 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
838 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
839
840 /* The circular_queue and helpers is used to implement the
841  * breadth-first search(BFS)algorithem, by which we can build
842  * the shortest path from the next lock to be acquired to the
843  * previous held lock if there is a circular between them.
844  * */
845 struct circular_queue {
846         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
847         unsigned int  front, rear;
848 };
849
850 static struct circular_queue lock_cq;
851 static unsigned long bfs_accessed[BITS_TO_LONGS(MAX_LOCKDEP_ENTRIES)];
852
853 unsigned int max_bfs_queue_depth;
854
855 static inline void __cq_init(struct circular_queue *cq)
856 {
857         cq->front = cq->rear = 0;
858         bitmap_zero(bfs_accessed, MAX_LOCKDEP_ENTRIES);
859 }
860
861 static inline int __cq_empty(struct circular_queue *cq)
862 {
863         return (cq->front == cq->rear);
864 }
865
866 static inline int __cq_full(struct circular_queue *cq)
867 {
868         return ((cq->rear + 1) & CQ_MASK) == cq->front;
869 }
870
871 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
872 {
873         if (__cq_full(cq))
874                 return -1;
875
876         cq->element[cq->rear] = elem;
877         cq->rear = (cq->rear + 1) & CQ_MASK;
878         return 0;
879 }
880
881 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
882 {
883         if (__cq_empty(cq))
884                 return -1;
885
886         *elem = cq->element[cq->front];
887         cq->front = (cq->front + 1) & CQ_MASK;
888         return 0;
889 }
890
891 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
892 {
893         return (cq->rear - cq->front) & CQ_MASK;
894 }
895
896 static inline void mark_lock_accessed(struct lock_list *lock,
897                                         struct lock_list *parent)
898 {
899         unsigned long nr;
900         nr = lock - list_entries;
901         WARN_ON(nr >= nr_list_entries);
902         lock->parent = parent;
903         set_bit(nr, bfs_accessed);
904 }
905
906 static inline unsigned long lock_accessed(struct lock_list *lock)
907 {
908         unsigned long nr;
909         nr = lock - list_entries;
910         WARN_ON(nr >= nr_list_entries);
911         return test_bit(nr, bfs_accessed);
912 }
913
914 static inline struct lock_list *get_lock_parent(struct lock_list *child)
915 {
916         return child->parent;
917 }
918
919 static inline int get_lock_depth(struct lock_list *child)
920 {
921         int depth = 0;
922         struct lock_list *parent;
923
924         while ((parent = get_lock_parent(child))) {
925                 child = parent;
926                 depth++;
927         }
928         return depth;
929 }
930
931 static int __bfs(struct lock_list *source_entry,
932                  void *data,
933                  int (*match)(struct lock_list *entry, void *data),
934                  struct lock_list **target_entry,
935                  int forward)
936 {
937         struct lock_list *entry;
938         struct list_head *head;
939         struct circular_queue *cq = &lock_cq;
940         int ret = 1;
941
942         if (match(source_entry, data)) {
943                 *target_entry = source_entry;
944                 ret = 0;
945                 goto exit;
946         }
947
948         if (forward)
949                 head = &source_entry->class->locks_after;
950         else
951                 head = &source_entry->class->locks_before;
952
953         if (list_empty(head))
954                 goto exit;
955
956         __cq_init(cq);
957         __cq_enqueue(cq, (unsigned long)source_entry);
958
959         while (!__cq_empty(cq)) {
960                 struct lock_list *lock;
961
962                 __cq_dequeue(cq, (unsigned long *)&lock);
963
964                 if (!lock->class) {
965                         ret = -2;
966                         goto exit;
967                 }
968
969                 if (forward)
970                         head = &lock->class->locks_after;
971                 else
972                         head = &lock->class->locks_before;
973
974                 list_for_each_entry(entry, head, entry) {
975                         if (!lock_accessed(entry)) {
976                                 unsigned int cq_depth;
977                                 mark_lock_accessed(entry, lock);
978                                 if (match(entry, data)) {
979                                         *target_entry = entry;
980                                         ret = 0;
981                                         goto exit;
982                                 }
983
984                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
985                                         ret = -1;
986                                         goto exit;
987                                 }
988                                 cq_depth = __cq_get_elem_count(cq);
989                                 if (max_bfs_queue_depth < cq_depth)
990                                         max_bfs_queue_depth = cq_depth;
991                         }
992                 }
993         }
994 exit:
995         return ret;
996 }
997
998 static inline int __bfs_forwards(struct lock_list *src_entry,
999                         void *data,
1000                         int (*match)(struct lock_list *entry, void *data),
1001                         struct lock_list **target_entry)
1002 {
1003         return __bfs(src_entry, data, match, target_entry, 1);
1004
1005 }
1006
1007 static inline int __bfs_backwards(struct lock_list *src_entry,
1008                         void *data,
1009                         int (*match)(struct lock_list *entry, void *data),
1010                         struct lock_list **target_entry)
1011 {
1012         return __bfs(src_entry, data, match, target_entry, 0);
1013
1014 }
1015
1016 /*
1017  * Recursive, forwards-direction lock-dependency checking, used for
1018  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1019  * checking.
1020  */
1021
1022 /*
1023  * Print a dependency chain entry (this is only done when a deadlock
1024  * has been detected):
1025  */
1026 static noinline int
1027 print_circular_bug_entry(struct lock_list *target, int depth)
1028 {
1029         if (debug_locks_silent)
1030                 return 0;
1031         printk("\n-> #%u", depth);
1032         print_lock_name(target->class);
1033         printk(":\n");
1034         print_stack_trace(&target->trace, 6);
1035
1036         return 0;
1037 }
1038
1039 /*
1040  * When a circular dependency is detected, print the
1041  * header first:
1042  */
1043 static noinline int
1044 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1045                         struct held_lock *check_src,
1046                         struct held_lock *check_tgt)
1047 {
1048         struct task_struct *curr = current;
1049
1050         if (debug_locks_silent)
1051                 return 0;
1052
1053         printk("\n=======================================================\n");
1054         printk(  "[ INFO: possible circular locking dependency detected ]\n");
1055         print_kernel_version();
1056         printk(  "-------------------------------------------------------\n");
1057         printk("%s/%d is trying to acquire lock:\n",
1058                 curr->comm, task_pid_nr(curr));
1059         print_lock(check_src);
1060         printk("\nbut task is already holding lock:\n");
1061         print_lock(check_tgt);
1062         printk("\nwhich lock already depends on the new lock.\n\n");
1063         printk("\nthe existing dependency chain (in reverse order) is:\n");
1064
1065         print_circular_bug_entry(entry, depth);
1066
1067         return 0;
1068 }
1069
1070 static inline int class_equal(struct lock_list *entry, void *data)
1071 {
1072         return entry->class == data;
1073 }
1074
1075 static noinline int print_circular_bug(struct lock_list *this,
1076                                 struct lock_list *target,
1077                                 struct held_lock *check_src,
1078                                 struct held_lock *check_tgt)
1079 {
1080         struct task_struct *curr = current;
1081         struct lock_list *parent;
1082         int depth;
1083
1084         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1085                 return 0;
1086
1087         if (!save_trace(&this->trace))
1088                 return 0;
1089
1090         depth = get_lock_depth(target);
1091
1092         print_circular_bug_header(target, depth, check_src, check_tgt);
1093
1094         parent = get_lock_parent(target);
1095
1096         while (parent) {
1097                 print_circular_bug_entry(parent, --depth);
1098                 parent = get_lock_parent(parent);
1099         }
1100
1101         printk("\nother info that might help us debug this:\n\n");
1102         lockdep_print_held_locks(curr);
1103
1104         printk("\nstack backtrace:\n");
1105         dump_stack();
1106
1107         return 0;
1108 }
1109
1110 static noinline int print_bfs_bug(int ret)
1111 {
1112         if (!debug_locks_off_graph_unlock())
1113                 return 0;
1114
1115         WARN(1, "lockdep bfs error:%d\n", ret);
1116
1117         return 0;
1118 }
1119
1120 static int noop_count(struct lock_list *entry, void *data)
1121 {
1122         (*(unsigned long *)data)++;
1123         return 0;
1124 }
1125
1126 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1127 {
1128         unsigned long  count = 0;
1129         struct lock_list *uninitialized_var(target_entry);
1130
1131         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1132
1133         return count;
1134 }
1135 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1136 {
1137         unsigned long ret, flags;
1138         struct lock_list this;
1139
1140         this.parent = NULL;
1141         this.class = class;
1142
1143         local_irq_save(flags);
1144         __raw_spin_lock(&lockdep_lock);
1145         ret = __lockdep_count_forward_deps(&this);
1146         __raw_spin_unlock(&lockdep_lock);
1147         local_irq_restore(flags);
1148
1149         return ret;
1150 }
1151
1152 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1153 {
1154         unsigned long  count = 0;
1155         struct lock_list *uninitialized_var(target_entry);
1156
1157         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1158
1159         return count;
1160 }
1161
1162 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1163 {
1164         unsigned long ret, flags;
1165         struct lock_list this;
1166
1167         this.parent = NULL;
1168         this.class = class;
1169
1170         local_irq_save(flags);
1171         __raw_spin_lock(&lockdep_lock);
1172         ret = __lockdep_count_backward_deps(&this);
1173         __raw_spin_unlock(&lockdep_lock);
1174         local_irq_restore(flags);
1175
1176         return ret;
1177 }
1178
1179 /*
1180  * Prove that the dependency graph starting at <entry> can not
1181  * lead to <target>. Print an error and return 0 if it does.
1182  */
1183 static noinline int
1184 check_noncircular(struct lock_list *root, struct lock_class *target,
1185                 struct lock_list **target_entry)
1186 {
1187         int result;
1188
1189         debug_atomic_inc(&nr_cyclic_checks);
1190
1191         result = __bfs_forwards(root, target, class_equal, target_entry);
1192
1193         return result;
1194 }
1195
1196 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1197 /*
1198  * Forwards and backwards subgraph searching, for the purposes of
1199  * proving that two subgraphs can be connected by a new dependency
1200  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1201  */
1202
1203 static inline int usage_match(struct lock_list *entry, void *bit)
1204 {
1205         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1206 }
1207
1208
1209
1210 /*
1211  * Find a node in the forwards-direction dependency sub-graph starting
1212  * at @root->class that matches @bit.
1213  *
1214  * Return 0 if such a node exists in the subgraph, and put that node
1215  * into *@target_entry.
1216  *
1217  * Return 1 otherwise and keep *@target_entry unchanged.
1218  * Return <0 on error.
1219  */
1220 static int
1221 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1222                         struct lock_list **target_entry)
1223 {
1224         int result;
1225
1226         debug_atomic_inc(&nr_find_usage_forwards_checks);
1227
1228         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1229
1230         return result;
1231 }
1232
1233 /*
1234  * Find a node in the backwards-direction dependency sub-graph starting
1235  * at @root->class that matches @bit.
1236  *
1237  * Return 0 if such a node exists in the subgraph, and put that node
1238  * into *@target_entry.
1239  *
1240  * Return 1 otherwise and keep *@target_entry unchanged.
1241  * Return <0 on error.
1242  */
1243 static int
1244 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1245                         struct lock_list **target_entry)
1246 {
1247         int result;
1248
1249         debug_atomic_inc(&nr_find_usage_backwards_checks);
1250
1251         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1252
1253         return result;
1254 }
1255
1256 static void print_lock_class_header(struct lock_class *class, int depth)
1257 {
1258         int bit;
1259
1260         printk("%*s->", depth, "");
1261         print_lock_name(class);
1262         printk(" ops: %lu", class->ops);
1263         printk(" {\n");
1264
1265         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1266                 if (class->usage_mask & (1 << bit)) {
1267                         int len = depth;
1268
1269                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1270                         len += printk(" at:\n");
1271                         print_stack_trace(class->usage_traces + bit, len);
1272                 }
1273         }
1274         printk("%*s }\n", depth, "");
1275
1276         printk("%*s ... key      at: ",depth,"");
1277         print_ip_sym((unsigned long)class->key);
1278 }
1279
1280 /*
1281  * printk the shortest lock dependencies from @start to @end in reverse order:
1282  */
1283 static void __used
1284 print_shortest_lock_dependencies(struct lock_list *leaf,
1285                                 struct lock_list *root)
1286 {
1287         struct lock_list *entry = leaf;
1288         int depth;
1289
1290         /*compute depth from generated tree by BFS*/
1291         depth = get_lock_depth(leaf);
1292
1293         do {
1294                 print_lock_class_header(entry->class, depth);
1295                 printk("%*s ... acquired at:\n", depth, "");
1296                 print_stack_trace(&entry->trace, 2);
1297                 printk("\n");
1298
1299                 if (depth == 0 && (entry != root)) {
1300                         printk("lockdep:%s bad BFS generated tree\n", __func__);
1301                         break;
1302                 }
1303
1304                 entry = get_lock_parent(entry);
1305                 depth--;
1306         } while (entry && (depth >= 0));
1307
1308         return;
1309 }
1310
1311 static int
1312 print_bad_irq_dependency(struct task_struct *curr,
1313                          struct lock_list *prev_root,
1314                          struct lock_list *next_root,
1315                          struct lock_list *backwards_entry,
1316                          struct lock_list *forwards_entry,
1317                          struct held_lock *prev,
1318                          struct held_lock *next,
1319                          enum lock_usage_bit bit1,
1320                          enum lock_usage_bit bit2,
1321                          const char *irqclass)
1322 {
1323         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1324                 return 0;
1325
1326         printk("\n======================================================\n");
1327         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1328                 irqclass, irqclass);
1329         print_kernel_version();
1330         printk(  "------------------------------------------------------\n");
1331         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1332                 curr->comm, task_pid_nr(curr),
1333                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1334                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1335                 curr->hardirqs_enabled,
1336                 curr->softirqs_enabled);
1337         print_lock(next);
1338
1339         printk("\nand this task is already holding:\n");
1340         print_lock(prev);
1341         printk("which would create a new lock dependency:\n");
1342         print_lock_name(hlock_class(prev));
1343         printk(" ->");
1344         print_lock_name(hlock_class(next));
1345         printk("\n");
1346
1347         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1348                 irqclass);
1349         print_lock_name(backwards_entry->class);
1350         printk("\n... which became %s-irq-safe at:\n", irqclass);
1351
1352         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1353
1354         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1355         print_lock_name(forwards_entry->class);
1356         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1357         printk("...");
1358
1359         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1360
1361         printk("\nother info that might help us debug this:\n\n");
1362         lockdep_print_held_locks(curr);
1363
1364         printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1365         printk(" and the holding lock:\n");
1366         if (!save_trace(&prev_root->trace))
1367                 return 0;
1368         print_shortest_lock_dependencies(backwards_entry, prev_root);
1369
1370         printk("\nthe dependencies between the lock to be acquired");
1371         printk(" and %s-irq-unsafe lock:\n", irqclass);
1372         if (!save_trace(&next_root->trace))
1373                 return 0;
1374         print_shortest_lock_dependencies(forwards_entry, next_root);
1375
1376         printk("\nstack backtrace:\n");
1377         dump_stack();
1378
1379         return 0;
1380 }
1381
1382 static int
1383 check_usage(struct task_struct *curr, struct held_lock *prev,
1384             struct held_lock *next, enum lock_usage_bit bit_backwards,
1385             enum lock_usage_bit bit_forwards, const char *irqclass)
1386 {
1387         int ret;
1388         struct lock_list this, that;
1389         struct lock_list *uninitialized_var(target_entry);
1390         struct lock_list *uninitialized_var(target_entry1);
1391
1392         this.parent = NULL;
1393
1394         this.class = hlock_class(prev);
1395         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1396         if (ret < 0)
1397                 return print_bfs_bug(ret);
1398         if (ret == 1)
1399                 return ret;
1400
1401         that.parent = NULL;
1402         that.class = hlock_class(next);
1403         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1404         if (ret < 0)
1405                 return print_bfs_bug(ret);
1406         if (ret == 1)
1407                 return ret;
1408
1409         return print_bad_irq_dependency(curr, &this, &that,
1410                         target_entry, target_entry1,
1411                         prev, next,
1412                         bit_backwards, bit_forwards, irqclass);
1413 }
1414
1415 static const char *state_names[] = {
1416 #define LOCKDEP_STATE(__STATE) \
1417         __stringify(__STATE),
1418 #include "lockdep_states.h"
1419 #undef LOCKDEP_STATE
1420 };
1421
1422 static const char *state_rnames[] = {
1423 #define LOCKDEP_STATE(__STATE) \
1424         __stringify(__STATE)"-READ",
1425 #include "lockdep_states.h"
1426 #undef LOCKDEP_STATE
1427 };
1428
1429 static inline const char *state_name(enum lock_usage_bit bit)
1430 {
1431         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1432 }
1433
1434 static int exclusive_bit(int new_bit)
1435 {
1436         /*
1437          * USED_IN
1438          * USED_IN_READ
1439          * ENABLED
1440          * ENABLED_READ
1441          *
1442          * bit 0 - write/read
1443          * bit 1 - used_in/enabled
1444          * bit 2+  state
1445          */
1446
1447         int state = new_bit & ~3;
1448         int dir = new_bit & 2;
1449
1450         /*
1451          * keep state, bit flip the direction and strip read.
1452          */
1453         return state | (dir ^ 2);
1454 }
1455
1456 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1457                            struct held_lock *next, enum lock_usage_bit bit)
1458 {
1459         /*
1460          * Prove that the new dependency does not connect a hardirq-safe
1461          * lock with a hardirq-unsafe lock - to achieve this we search
1462          * the backwards-subgraph starting at <prev>, and the
1463          * forwards-subgraph starting at <next>:
1464          */
1465         if (!check_usage(curr, prev, next, bit,
1466                            exclusive_bit(bit), state_name(bit)))
1467                 return 0;
1468
1469         bit++; /* _READ */
1470
1471         /*
1472          * Prove that the new dependency does not connect a hardirq-safe-read
1473          * lock with a hardirq-unsafe lock - to achieve this we search
1474          * the backwards-subgraph starting at <prev>, and the
1475          * forwards-subgraph starting at <next>:
1476          */
1477         if (!check_usage(curr, prev, next, bit,
1478                            exclusive_bit(bit), state_name(bit)))
1479                 return 0;
1480
1481         return 1;
1482 }
1483
1484 static int
1485 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1486                 struct held_lock *next)
1487 {
1488 #define LOCKDEP_STATE(__STATE)                                          \
1489         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1490                 return 0;
1491 #include "lockdep_states.h"
1492 #undef LOCKDEP_STATE
1493
1494         return 1;
1495 }
1496
1497 static void inc_chains(void)
1498 {
1499         if (current->hardirq_context)
1500                 nr_hardirq_chains++;
1501         else {
1502                 if (current->softirq_context)
1503                         nr_softirq_chains++;
1504                 else
1505                         nr_process_chains++;
1506         }
1507 }
1508
1509 #else
1510
1511 static inline int
1512 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1513                 struct held_lock *next)
1514 {
1515         return 1;
1516 }
1517
1518 static inline void inc_chains(void)
1519 {
1520         nr_process_chains++;
1521 }
1522
1523 #endif
1524
1525 static int
1526 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1527                    struct held_lock *next)
1528 {
1529         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1530                 return 0;
1531
1532         printk("\n=============================================\n");
1533         printk(  "[ INFO: possible recursive locking detected ]\n");
1534         print_kernel_version();
1535         printk(  "---------------------------------------------\n");
1536         printk("%s/%d is trying to acquire lock:\n",
1537                 curr->comm, task_pid_nr(curr));
1538         print_lock(next);
1539         printk("\nbut task is already holding lock:\n");
1540         print_lock(prev);
1541
1542         printk("\nother info that might help us debug this:\n");
1543         lockdep_print_held_locks(curr);
1544
1545         printk("\nstack backtrace:\n");
1546         dump_stack();
1547
1548         return 0;
1549 }
1550
1551 /*
1552  * Check whether we are holding such a class already.
1553  *
1554  * (Note that this has to be done separately, because the graph cannot
1555  * detect such classes of deadlocks.)
1556  *
1557  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1558  */
1559 static int
1560 check_deadlock(struct task_struct *curr, struct held_lock *next,
1561                struct lockdep_map *next_instance, int read)
1562 {
1563         struct held_lock *prev;
1564         struct held_lock *nest = NULL;
1565         int i;
1566
1567         for (i = 0; i < curr->lockdep_depth; i++) {
1568                 prev = curr->held_locks + i;
1569
1570                 if (prev->instance == next->nest_lock)
1571                         nest = prev;
1572
1573                 if (hlock_class(prev) != hlock_class(next))
1574                         continue;
1575
1576                 /*
1577                  * Allow read-after-read recursion of the same
1578                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1579                  */
1580                 if ((read == 2) && prev->read)
1581                         return 2;
1582
1583                 /*
1584                  * We're holding the nest_lock, which serializes this lock's
1585                  * nesting behaviour.
1586                  */
1587                 if (nest)
1588                         return 2;
1589
1590                 return print_deadlock_bug(curr, prev, next);
1591         }
1592         return 1;
1593 }
1594
1595 /*
1596  * There was a chain-cache miss, and we are about to add a new dependency
1597  * to a previous lock. We recursively validate the following rules:
1598  *
1599  *  - would the adding of the <prev> -> <next> dependency create a
1600  *    circular dependency in the graph? [== circular deadlock]
1601  *
1602  *  - does the new prev->next dependency connect any hardirq-safe lock
1603  *    (in the full backwards-subgraph starting at <prev>) with any
1604  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1605  *    <next>)? [== illegal lock inversion with hardirq contexts]
1606  *
1607  *  - does the new prev->next dependency connect any softirq-safe lock
1608  *    (in the full backwards-subgraph starting at <prev>) with any
1609  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1610  *    <next>)? [== illegal lock inversion with softirq contexts]
1611  *
1612  * any of these scenarios could lead to a deadlock.
1613  *
1614  * Then if all the validations pass, we add the forwards and backwards
1615  * dependency.
1616  */
1617 static int
1618 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1619                struct held_lock *next, int distance)
1620 {
1621         struct lock_list *entry;
1622         int ret;
1623         struct lock_list this;
1624         struct lock_list *uninitialized_var(target_entry);
1625
1626         /*
1627          * Prove that the new <prev> -> <next> dependency would not
1628          * create a circular dependency in the graph. (We do this by
1629          * forward-recursing into the graph starting at <next>, and
1630          * checking whether we can reach <prev>.)
1631          *
1632          * We are using global variables to control the recursion, to
1633          * keep the stackframe size of the recursive functions low:
1634          */
1635         this.class = hlock_class(next);
1636         this.parent = NULL;
1637         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1638         if (unlikely(!ret))
1639                 return print_circular_bug(&this, target_entry, next, prev);
1640         else if (unlikely(ret < 0))
1641                 return print_bfs_bug(ret);
1642
1643         if (!check_prev_add_irq(curr, prev, next))
1644                 return 0;
1645
1646         /*
1647          * For recursive read-locks we do all the dependency checks,
1648          * but we dont store read-triggered dependencies (only
1649          * write-triggered dependencies). This ensures that only the
1650          * write-side dependencies matter, and that if for example a
1651          * write-lock never takes any other locks, then the reads are
1652          * equivalent to a NOP.
1653          */
1654         if (next->read == 2 || prev->read == 2)
1655                 return 1;
1656         /*
1657          * Is the <prev> -> <next> dependency already present?
1658          *
1659          * (this may occur even though this is a new chain: consider
1660          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1661          *  chains - the second one will be new, but L1 already has
1662          *  L2 added to its dependency list, due to the first chain.)
1663          */
1664         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1665                 if (entry->class == hlock_class(next)) {
1666                         if (distance == 1)
1667                                 entry->distance = 1;
1668                         return 2;
1669                 }
1670         }
1671
1672         /*
1673          * Ok, all validations passed, add the new lock
1674          * to the previous lock's dependency list:
1675          */
1676         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1677                                &hlock_class(prev)->locks_after,
1678                                next->acquire_ip, distance);
1679
1680         if (!ret)
1681                 return 0;
1682
1683         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1684                                &hlock_class(next)->locks_before,
1685                                next->acquire_ip, distance);
1686         if (!ret)
1687                 return 0;
1688
1689         /*
1690          * Debugging printouts:
1691          */
1692         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1693                 graph_unlock();
1694                 printk("\n new dependency: ");
1695                 print_lock_name(hlock_class(prev));
1696                 printk(" => ");
1697                 print_lock_name(hlock_class(next));
1698                 printk("\n");
1699                 dump_stack();
1700                 return graph_lock();
1701         }
1702         return 1;
1703 }
1704
1705 /*
1706  * Add the dependency to all directly-previous locks that are 'relevant'.
1707  * The ones that are relevant are (in increasing distance from curr):
1708  * all consecutive trylock entries and the final non-trylock entry - or
1709  * the end of this context's lock-chain - whichever comes first.
1710  */
1711 static int
1712 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1713 {
1714         int depth = curr->lockdep_depth;
1715         struct held_lock *hlock;
1716
1717         /*
1718          * Debugging checks.
1719          *
1720          * Depth must not be zero for a non-head lock:
1721          */
1722         if (!depth)
1723                 goto out_bug;
1724         /*
1725          * At least two relevant locks must exist for this
1726          * to be a head:
1727          */
1728         if (curr->held_locks[depth].irq_context !=
1729                         curr->held_locks[depth-1].irq_context)
1730                 goto out_bug;
1731
1732         for (;;) {
1733                 int distance = curr->lockdep_depth - depth + 1;
1734                 hlock = curr->held_locks + depth-1;
1735                 /*
1736                  * Only non-recursive-read entries get new dependencies
1737                  * added:
1738                  */
1739                 if (hlock->read != 2) {
1740                         if (!check_prev_add(curr, hlock, next, distance))
1741                                 return 0;
1742                         /*
1743                          * Stop after the first non-trylock entry,
1744                          * as non-trylock entries have added their
1745                          * own direct dependencies already, so this
1746                          * lock is connected to them indirectly:
1747                          */
1748                         if (!hlock->trylock)
1749                                 break;
1750                 }
1751                 depth--;
1752                 /*
1753                  * End of lock-stack?
1754                  */
1755                 if (!depth)
1756                         break;
1757                 /*
1758                  * Stop the search if we cross into another context:
1759                  */
1760                 if (curr->held_locks[depth].irq_context !=
1761                                 curr->held_locks[depth-1].irq_context)
1762                         break;
1763         }
1764         return 1;
1765 out_bug:
1766         if (!debug_locks_off_graph_unlock())
1767                 return 0;
1768
1769         WARN_ON(1);
1770
1771         return 0;
1772 }
1773
1774 unsigned long nr_lock_chains;
1775 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1776 int nr_chain_hlocks;
1777 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1778
1779 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1780 {
1781         return lock_classes + chain_hlocks[chain->base + i];
1782 }
1783
1784 /*
1785  * Look up a dependency chain. If the key is not present yet then
1786  * add it and return 1 - in this case the new dependency chain is
1787  * validated. If the key is already hashed, return 0.
1788  * (On return with 1 graph_lock is held.)
1789  */
1790 static inline int lookup_chain_cache(struct task_struct *curr,
1791                                      struct held_lock *hlock,
1792                                      u64 chain_key)
1793 {
1794         struct lock_class *class = hlock_class(hlock);
1795         struct list_head *hash_head = chainhashentry(chain_key);
1796         struct lock_chain *chain;
1797         struct held_lock *hlock_curr, *hlock_next;
1798         int i, j, n, cn;
1799
1800         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1801                 return 0;
1802         /*
1803          * We can walk it lock-free, because entries only get added
1804          * to the hash:
1805          */
1806         list_for_each_entry(chain, hash_head, entry) {
1807                 if (chain->chain_key == chain_key) {
1808 cache_hit:
1809                         debug_atomic_inc(&chain_lookup_hits);
1810                         if (very_verbose(class))
1811                                 printk("\nhash chain already cached, key: "
1812                                         "%016Lx tail class: [%p] %s\n",
1813                                         (unsigned long long)chain_key,
1814                                         class->key, class->name);
1815                         return 0;
1816                 }
1817         }
1818         if (very_verbose(class))
1819                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1820                         (unsigned long long)chain_key, class->key, class->name);
1821         /*
1822          * Allocate a new chain entry from the static array, and add
1823          * it to the hash:
1824          */
1825         if (!graph_lock())
1826                 return 0;
1827         /*
1828          * We have to walk the chain again locked - to avoid duplicates:
1829          */
1830         list_for_each_entry(chain, hash_head, entry) {
1831                 if (chain->chain_key == chain_key) {
1832                         graph_unlock();
1833                         goto cache_hit;
1834                 }
1835         }
1836         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1837                 if (!debug_locks_off_graph_unlock())
1838                         return 0;
1839
1840                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1841                 printk("turning off the locking correctness validator.\n");
1842                 dump_stack();
1843                 return 0;
1844         }
1845         chain = lock_chains + nr_lock_chains++;
1846         chain->chain_key = chain_key;
1847         chain->irq_context = hlock->irq_context;
1848         /* Find the first held_lock of current chain */
1849         hlock_next = hlock;
1850         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1851                 hlock_curr = curr->held_locks + i;
1852                 if (hlock_curr->irq_context != hlock_next->irq_context)
1853                         break;
1854                 hlock_next = hlock;
1855         }
1856         i++;
1857         chain->depth = curr->lockdep_depth + 1 - i;
1858         cn = nr_chain_hlocks;
1859         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1860                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1861                 if (n == cn)
1862                         break;
1863                 cn = n;
1864         }
1865         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1866                 chain->base = cn;
1867                 for (j = 0; j < chain->depth - 1; j++, i++) {
1868                         int lock_id = curr->held_locks[i].class_idx - 1;
1869                         chain_hlocks[chain->base + j] = lock_id;
1870                 }
1871                 chain_hlocks[chain->base + j] = class - lock_classes;
1872         }
1873         list_add_tail_rcu(&chain->entry, hash_head);
1874         debug_atomic_inc(&chain_lookup_misses);
1875         inc_chains();
1876
1877         return 1;
1878 }
1879
1880 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1881                 struct held_lock *hlock, int chain_head, u64 chain_key)
1882 {
1883         /*
1884          * Trylock needs to maintain the stack of held locks, but it
1885          * does not add new dependencies, because trylock can be done
1886          * in any order.
1887          *
1888          * We look up the chain_key and do the O(N^2) check and update of
1889          * the dependencies only if this is a new dependency chain.
1890          * (If lookup_chain_cache() returns with 1 it acquires
1891          * graph_lock for us)
1892          */
1893         if (!hlock->trylock && (hlock->check == 2) &&
1894             lookup_chain_cache(curr, hlock, chain_key)) {
1895                 /*
1896                  * Check whether last held lock:
1897                  *
1898                  * - is irq-safe, if this lock is irq-unsafe
1899                  * - is softirq-safe, if this lock is hardirq-unsafe
1900                  *
1901                  * And check whether the new lock's dependency graph
1902                  * could lead back to the previous lock.
1903                  *
1904                  * any of these scenarios could lead to a deadlock. If
1905                  * All validations
1906                  */
1907                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1908
1909                 if (!ret)
1910                         return 0;
1911                 /*
1912                  * Mark recursive read, as we jump over it when
1913                  * building dependencies (just like we jump over
1914                  * trylock entries):
1915                  */
1916                 if (ret == 2)
1917                         hlock->read = 2;
1918                 /*
1919                  * Add dependency only if this lock is not the head
1920                  * of the chain, and if it's not a secondary read-lock:
1921                  */
1922                 if (!chain_head && ret != 2)
1923                         if (!check_prevs_add(curr, hlock))
1924                                 return 0;
1925                 graph_unlock();
1926         } else
1927                 /* after lookup_chain_cache(): */
1928                 if (unlikely(!debug_locks))
1929                         return 0;
1930
1931         return 1;
1932 }
1933 #else
1934 static inline int validate_chain(struct task_struct *curr,
1935                 struct lockdep_map *lock, struct held_lock *hlock,
1936                 int chain_head, u64 chain_key)
1937 {
1938         return 1;
1939 }
1940 #endif
1941
1942 /*
1943  * We are building curr_chain_key incrementally, so double-check
1944  * it from scratch, to make sure that it's done correctly:
1945  */
1946 static void check_chain_key(struct task_struct *curr)
1947 {
1948 #ifdef CONFIG_DEBUG_LOCKDEP
1949         struct held_lock *hlock, *prev_hlock = NULL;
1950         unsigned int i, id;
1951         u64 chain_key = 0;
1952
1953         for (i = 0; i < curr->lockdep_depth; i++) {
1954                 hlock = curr->held_locks + i;
1955                 if (chain_key != hlock->prev_chain_key) {
1956                         debug_locks_off();
1957                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1958                                 curr->lockdep_depth, i,
1959                                 (unsigned long long)chain_key,
1960                                 (unsigned long long)hlock->prev_chain_key);
1961                         return;
1962                 }
1963                 id = hlock->class_idx - 1;
1964                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1965                         return;
1966
1967                 if (prev_hlock && (prev_hlock->irq_context !=
1968                                                         hlock->irq_context))
1969                         chain_key = 0;
1970                 chain_key = iterate_chain_key(chain_key, id);
1971                 prev_hlock = hlock;
1972         }
1973         if (chain_key != curr->curr_chain_key) {
1974                 debug_locks_off();
1975                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1976                         curr->lockdep_depth, i,
1977                         (unsigned long long)chain_key,
1978                         (unsigned long long)curr->curr_chain_key);
1979         }
1980 #endif
1981 }
1982
1983 static int
1984 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1985                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1986 {
1987         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1988                 return 0;
1989
1990         printk("\n=================================\n");
1991         printk(  "[ INFO: inconsistent lock state ]\n");
1992         print_kernel_version();
1993         printk(  "---------------------------------\n");
1994
1995         printk("inconsistent {%s} -> {%s} usage.\n",
1996                 usage_str[prev_bit], usage_str[new_bit]);
1997
1998         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1999                 curr->comm, task_pid_nr(curr),
2000                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2001                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2002                 trace_hardirqs_enabled(curr),
2003                 trace_softirqs_enabled(curr));
2004         print_lock(this);
2005
2006         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2007         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2008
2009         print_irqtrace_events(curr);
2010         printk("\nother info that might help us debug this:\n");
2011         lockdep_print_held_locks(curr);
2012
2013         printk("\nstack backtrace:\n");
2014         dump_stack();
2015
2016         return 0;
2017 }
2018
2019 /*
2020  * Print out an error if an invalid bit is set:
2021  */
2022 static inline int
2023 valid_state(struct task_struct *curr, struct held_lock *this,
2024             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2025 {
2026         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2027                 return print_usage_bug(curr, this, bad_bit, new_bit);
2028         return 1;
2029 }
2030
2031 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2032                      enum lock_usage_bit new_bit);
2033
2034 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2035
2036 /*
2037  * print irq inversion bug:
2038  */
2039 static int
2040 print_irq_inversion_bug(struct task_struct *curr,
2041                         struct lock_list *root, struct lock_list *other,
2042                         struct held_lock *this, int forwards,
2043                         const char *irqclass)
2044 {
2045         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2046                 return 0;
2047
2048         printk("\n=========================================================\n");
2049         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2050         print_kernel_version();
2051         printk(  "---------------------------------------------------------\n");
2052         printk("%s/%d just changed the state of lock:\n",
2053                 curr->comm, task_pid_nr(curr));
2054         print_lock(this);
2055         if (forwards)
2056                 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2057         else
2058                 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2059         print_lock_name(other->class);
2060         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2061
2062         printk("\nother info that might help us debug this:\n");
2063         lockdep_print_held_locks(curr);
2064
2065         printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2066         if (!save_trace(&root->trace))
2067                 return 0;
2068         print_shortest_lock_dependencies(other, root);
2069
2070         printk("\nstack backtrace:\n");
2071         dump_stack();
2072
2073         return 0;
2074 }
2075
2076 /*
2077  * Prove that in the forwards-direction subgraph starting at <this>
2078  * there is no lock matching <mask>:
2079  */
2080 static int
2081 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2082                      enum lock_usage_bit bit, const char *irqclass)
2083 {
2084         int ret;
2085         struct lock_list root;
2086         struct lock_list *uninitialized_var(target_entry);
2087
2088         root.parent = NULL;
2089         root.class = hlock_class(this);
2090         ret = find_usage_forwards(&root, bit, &target_entry);
2091         if (ret < 0)
2092                 return print_bfs_bug(ret);
2093         if (ret == 1)
2094                 return ret;
2095
2096         return print_irq_inversion_bug(curr, &root, target_entry,
2097                                         this, 1, irqclass);
2098 }
2099
2100 /*
2101  * Prove that in the backwards-direction subgraph starting at <this>
2102  * there is no lock matching <mask>:
2103  */
2104 static int
2105 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2106                       enum lock_usage_bit bit, const char *irqclass)
2107 {
2108         int ret;
2109         struct lock_list root;
2110         struct lock_list *uninitialized_var(target_entry);
2111
2112         root.parent = NULL;
2113         root.class = hlock_class(this);
2114         ret = find_usage_backwards(&root, bit, &target_entry);
2115         if (ret < 0)
2116                 return print_bfs_bug(ret);
2117         if (ret == 1)
2118                 return ret;
2119
2120         return print_irq_inversion_bug(curr, &root, target_entry,
2121                                         this, 1, irqclass);
2122 }
2123
2124 void print_irqtrace_events(struct task_struct *curr)
2125 {
2126         printk("irq event stamp: %u\n", curr->irq_events);
2127         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2128         print_ip_sym(curr->hardirq_enable_ip);
2129         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2130         print_ip_sym(curr->hardirq_disable_ip);
2131         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2132         print_ip_sym(curr->softirq_enable_ip);
2133         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2134         print_ip_sym(curr->softirq_disable_ip);
2135 }
2136
2137 static int HARDIRQ_verbose(struct lock_class *class)
2138 {
2139 #if HARDIRQ_VERBOSE
2140         return class_filter(class);
2141 #endif
2142         return 0;
2143 }
2144
2145 static int SOFTIRQ_verbose(struct lock_class *class)
2146 {
2147 #if SOFTIRQ_VERBOSE
2148         return class_filter(class);
2149 #endif
2150         return 0;
2151 }
2152
2153 static int RECLAIM_FS_verbose(struct lock_class *class)
2154 {
2155 #if RECLAIM_VERBOSE
2156         return class_filter(class);
2157 #endif
2158         return 0;
2159 }
2160
2161 #define STRICT_READ_CHECKS      1
2162
2163 static int (*state_verbose_f[])(struct lock_class *class) = {
2164 #define LOCKDEP_STATE(__STATE) \
2165         __STATE##_verbose,
2166 #include "lockdep_states.h"
2167 #undef LOCKDEP_STATE
2168 };
2169
2170 static inline int state_verbose(enum lock_usage_bit bit,
2171                                 struct lock_class *class)
2172 {
2173         return state_verbose_f[bit >> 2](class);
2174 }
2175
2176 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2177                              enum lock_usage_bit bit, const char *name);
2178
2179 static int
2180 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2181                 enum lock_usage_bit new_bit)
2182 {
2183         int excl_bit = exclusive_bit(new_bit);
2184         int read = new_bit & 1;
2185         int dir = new_bit & 2;
2186
2187         /*
2188          * mark USED_IN has to look forwards -- to ensure no dependency
2189          * has ENABLED state, which would allow recursion deadlocks.
2190          *
2191          * mark ENABLED has to look backwards -- to ensure no dependee
2192          * has USED_IN state, which, again, would allow  recursion deadlocks.
2193          */
2194         check_usage_f usage = dir ?
2195                 check_usage_backwards : check_usage_forwards;
2196
2197         /*
2198          * Validate that this particular lock does not have conflicting
2199          * usage states.
2200          */
2201         if (!valid_state(curr, this, new_bit, excl_bit))
2202                 return 0;
2203
2204         /*
2205          * Validate that the lock dependencies don't have conflicting usage
2206          * states.
2207          */
2208         if ((!read || !dir || STRICT_READ_CHECKS) &&
2209                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2210                 return 0;
2211
2212         /*
2213          * Check for read in write conflicts
2214          */
2215         if (!read) {
2216                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2217                         return 0;
2218
2219                 if (STRICT_READ_CHECKS &&
2220                         !usage(curr, this, excl_bit + 1,
2221                                 state_name(new_bit + 1)))
2222                         return 0;
2223         }
2224
2225         if (state_verbose(new_bit, hlock_class(this)))
2226                 return 2;
2227
2228         return 1;
2229 }
2230
2231 enum mark_type {
2232 #define LOCKDEP_STATE(__STATE)  __STATE,
2233 #include "lockdep_states.h"
2234 #undef LOCKDEP_STATE
2235 };
2236
2237 /*
2238  * Mark all held locks with a usage bit:
2239  */
2240 static int
2241 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2242 {
2243         enum lock_usage_bit usage_bit;
2244         struct held_lock *hlock;
2245         int i;
2246
2247         for (i = 0; i < curr->lockdep_depth; i++) {
2248                 hlock = curr->held_locks + i;
2249
2250                 usage_bit = 2 + (mark << 2); /* ENABLED */
2251                 if (hlock->read)
2252                         usage_bit += 1; /* READ */
2253
2254                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2255
2256                 if (!mark_lock(curr, hlock, usage_bit))
2257                         return 0;
2258         }
2259
2260         return 1;
2261 }
2262
2263 /*
2264  * Debugging helper: via this flag we know that we are in
2265  * 'early bootup code', and will warn about any invalid irqs-on event:
2266  */
2267 static int early_boot_irqs_enabled;
2268
2269 void early_boot_irqs_off(void)
2270 {
2271         early_boot_irqs_enabled = 0;
2272 }
2273
2274 void early_boot_irqs_on(void)
2275 {
2276         early_boot_irqs_enabled = 1;
2277 }
2278
2279 /*
2280  * Hardirqs will be enabled:
2281  */
2282 void trace_hardirqs_on_caller(unsigned long ip)
2283 {
2284         struct task_struct *curr = current;
2285
2286         time_hardirqs_on(CALLER_ADDR0, ip);
2287
2288         if (unlikely(!debug_locks || current->lockdep_recursion))
2289                 return;
2290
2291         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2292                 return;
2293
2294         if (unlikely(curr->hardirqs_enabled)) {
2295                 debug_atomic_inc(&redundant_hardirqs_on);
2296                 return;
2297         }
2298         /* we'll do an OFF -> ON transition: */
2299         curr->hardirqs_enabled = 1;
2300
2301         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2302                 return;
2303         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2304                 return;
2305         /*
2306          * We are going to turn hardirqs on, so set the
2307          * usage bit for all held locks:
2308          */
2309         if (!mark_held_locks(curr, HARDIRQ))
2310                 return;
2311         /*
2312          * If we have softirqs enabled, then set the usage
2313          * bit for all held locks. (disabled hardirqs prevented
2314          * this bit from being set before)
2315          */
2316         if (curr->softirqs_enabled)
2317                 if (!mark_held_locks(curr, SOFTIRQ))
2318                         return;
2319
2320         curr->hardirq_enable_ip = ip;
2321         curr->hardirq_enable_event = ++curr->irq_events;
2322         debug_atomic_inc(&hardirqs_on_events);
2323 }
2324 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2325
2326 void trace_hardirqs_on(void)
2327 {
2328         trace_hardirqs_on_caller(CALLER_ADDR0);
2329 }
2330 EXPORT_SYMBOL(trace_hardirqs_on);
2331
2332 /*
2333  * Hardirqs were disabled:
2334  */
2335 void trace_hardirqs_off_caller(unsigned long ip)
2336 {
2337         struct task_struct *curr = current;
2338
2339         time_hardirqs_off(CALLER_ADDR0, ip);
2340
2341         if (unlikely(!debug_locks || current->lockdep_recursion))
2342                 return;
2343
2344         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2345                 return;
2346
2347         if (curr->hardirqs_enabled) {
2348                 /*
2349                  * We have done an ON -> OFF transition:
2350                  */
2351                 curr->hardirqs_enabled = 0;
2352                 curr->hardirq_disable_ip = ip;
2353                 curr->hardirq_disable_event = ++curr->irq_events;
2354                 debug_atomic_inc(&hardirqs_off_events);
2355         } else
2356                 debug_atomic_inc(&redundant_hardirqs_off);
2357 }
2358 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2359
2360 void trace_hardirqs_off(void)
2361 {
2362         trace_hardirqs_off_caller(CALLER_ADDR0);
2363 }
2364 EXPORT_SYMBOL(trace_hardirqs_off);
2365
2366 /*
2367  * Softirqs will be enabled:
2368  */
2369 void trace_softirqs_on(unsigned long ip)
2370 {
2371         struct task_struct *curr = current;
2372
2373         if (unlikely(!debug_locks))
2374                 return;
2375
2376         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2377                 return;
2378
2379         if (curr->softirqs_enabled) {
2380                 debug_atomic_inc(&redundant_softirqs_on);
2381                 return;
2382         }
2383
2384         /*
2385          * We'll do an OFF -> ON transition:
2386          */
2387         curr->softirqs_enabled = 1;
2388         curr->softirq_enable_ip = ip;
2389         curr->softirq_enable_event = ++curr->irq_events;
2390         debug_atomic_inc(&softirqs_on_events);
2391         /*
2392          * We are going to turn softirqs on, so set the
2393          * usage bit for all held locks, if hardirqs are
2394          * enabled too:
2395          */
2396         if (curr->hardirqs_enabled)
2397                 mark_held_locks(curr, SOFTIRQ);
2398 }
2399
2400 /*
2401  * Softirqs were disabled:
2402  */
2403 void trace_softirqs_off(unsigned long ip)
2404 {
2405         struct task_struct *curr = current;
2406
2407         if (unlikely(!debug_locks))
2408                 return;
2409
2410         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2411                 return;
2412
2413         if (curr->softirqs_enabled) {
2414                 /*
2415                  * We have done an ON -> OFF transition:
2416                  */
2417                 curr->softirqs_enabled = 0;
2418                 curr->softirq_disable_ip = ip;
2419                 curr->softirq_disable_event = ++curr->irq_events;
2420                 debug_atomic_inc(&softirqs_off_events);
2421                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2422         } else
2423                 debug_atomic_inc(&redundant_softirqs_off);
2424 }
2425
2426 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2427 {
2428         struct task_struct *curr = current;
2429
2430         if (unlikely(!debug_locks))
2431                 return;
2432
2433         /* no reclaim without waiting on it */
2434         if (!(gfp_mask & __GFP_WAIT))
2435                 return;
2436
2437         /* this guy won't enter reclaim */
2438         if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2439                 return;
2440
2441         /* We're only interested __GFP_FS allocations for now */
2442         if (!(gfp_mask & __GFP_FS))
2443                 return;
2444
2445         if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2446                 return;
2447
2448         mark_held_locks(curr, RECLAIM_FS);
2449 }
2450
2451 static void check_flags(unsigned long flags);
2452
2453 void lockdep_trace_alloc(gfp_t gfp_mask)
2454 {
2455         unsigned long flags;
2456
2457         if (unlikely(current->lockdep_recursion))
2458                 return;
2459
2460         raw_local_irq_save(flags);
2461         check_flags(flags);
2462         current->lockdep_recursion = 1;
2463         __lockdep_trace_alloc(gfp_mask, flags);
2464         current->lockdep_recursion = 0;
2465         raw_local_irq_restore(flags);
2466 }
2467
2468 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2469 {
2470         /*
2471          * If non-trylock use in a hardirq or softirq context, then
2472          * mark the lock as used in these contexts:
2473          */
2474         if (!hlock->trylock) {
2475                 if (hlock->read) {
2476                         if (curr->hardirq_context)
2477                                 if (!mark_lock(curr, hlock,
2478                                                 LOCK_USED_IN_HARDIRQ_READ))
2479                                         return 0;
2480                         if (curr->softirq_context)
2481                                 if (!mark_lock(curr, hlock,
2482                                                 LOCK_USED_IN_SOFTIRQ_READ))
2483                                         return 0;
2484                 } else {
2485                         if (curr->hardirq_context)
2486                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2487                                         return 0;
2488                         if (curr->softirq_context)
2489                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2490                                         return 0;
2491                 }
2492         }
2493         if (!hlock->hardirqs_off) {
2494                 if (hlock->read) {
2495                         if (!mark_lock(curr, hlock,
2496                                         LOCK_ENABLED_HARDIRQ_READ))
2497                                 return 0;
2498                         if (curr->softirqs_enabled)
2499                                 if (!mark_lock(curr, hlock,
2500                                                 LOCK_ENABLED_SOFTIRQ_READ))
2501                                         return 0;
2502                 } else {
2503                         if (!mark_lock(curr, hlock,
2504                                         LOCK_ENABLED_HARDIRQ))
2505                                 return 0;
2506                         if (curr->softirqs_enabled)
2507                                 if (!mark_lock(curr, hlock,
2508                                                 LOCK_ENABLED_SOFTIRQ))
2509                                         return 0;
2510                 }
2511         }
2512
2513         /*
2514          * We reuse the irq context infrastructure more broadly as a general
2515          * context checking code. This tests GFP_FS recursion (a lock taken
2516          * during reclaim for a GFP_FS allocation is held over a GFP_FS
2517          * allocation).
2518          */
2519         if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2520                 if (hlock->read) {
2521                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2522                                         return 0;
2523                 } else {
2524                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2525                                         return 0;
2526                 }
2527         }
2528
2529         return 1;
2530 }
2531
2532 static int separate_irq_context(struct task_struct *curr,
2533                 struct held_lock *hlock)
2534 {
2535         unsigned int depth = curr->lockdep_depth;
2536
2537         /*
2538          * Keep track of points where we cross into an interrupt context:
2539          */
2540         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2541                                 curr->softirq_context;
2542         if (depth) {
2543                 struct held_lock *prev_hlock;
2544
2545                 prev_hlock = curr->held_locks + depth-1;
2546                 /*
2547                  * If we cross into another context, reset the
2548                  * hash key (this also prevents the checking and the
2549                  * adding of the dependency to 'prev'):
2550                  */
2551                 if (prev_hlock->irq_context != hlock->irq_context)
2552                         return 1;
2553         }
2554         return 0;
2555 }
2556
2557 #else
2558
2559 static inline
2560 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2561                 enum lock_usage_bit new_bit)
2562 {
2563         WARN_ON(1);
2564         return 1;
2565 }
2566
2567 static inline int mark_irqflags(struct task_struct *curr,
2568                 struct held_lock *hlock)
2569 {
2570         return 1;
2571 }
2572
2573 static inline int separate_irq_context(struct task_struct *curr,
2574                 struct held_lock *hlock)
2575 {
2576         return 0;
2577 }
2578
2579 void lockdep_trace_alloc(gfp_t gfp_mask)
2580 {
2581 }
2582
2583 #endif
2584
2585 /*
2586  * Mark a lock with a usage bit, and validate the state transition:
2587  */
2588 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2589                              enum lock_usage_bit new_bit)
2590 {
2591         unsigned int new_mask = 1 << new_bit, ret = 1;
2592
2593         /*
2594          * If already set then do not dirty the cacheline,
2595          * nor do any checks:
2596          */
2597         if (likely(hlock_class(this)->usage_mask & new_mask))
2598                 return 1;
2599
2600         if (!graph_lock())
2601                 return 0;
2602         /*
2603          * Make sure we didnt race:
2604          */
2605         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2606                 graph_unlock();
2607                 return 1;
2608         }
2609
2610         hlock_class(this)->usage_mask |= new_mask;
2611
2612         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2613                 return 0;
2614
2615         switch (new_bit) {
2616 #define LOCKDEP_STATE(__STATE)                  \
2617         case LOCK_USED_IN_##__STATE:            \
2618         case LOCK_USED_IN_##__STATE##_READ:     \
2619         case LOCK_ENABLED_##__STATE:            \
2620         case LOCK_ENABLED_##__STATE##_READ:
2621 #include "lockdep_states.h"
2622 #undef LOCKDEP_STATE
2623                 ret = mark_lock_irq(curr, this, new_bit);
2624                 if (!ret)
2625                         return 0;
2626                 break;
2627         case LOCK_USED:
2628                 debug_atomic_dec(&nr_unused_locks);
2629                 break;
2630         default:
2631                 if (!debug_locks_off_graph_unlock())
2632                         return 0;
2633                 WARN_ON(1);
2634                 return 0;
2635         }
2636
2637         graph_unlock();
2638
2639         /*
2640          * We must printk outside of the graph_lock:
2641          */
2642         if (ret == 2) {
2643                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2644                 print_lock(this);
2645                 print_irqtrace_events(curr);
2646                 dump_stack();
2647         }
2648
2649         return ret;
2650 }
2651
2652 /*
2653  * Initialize a lock instance's lock-class mapping info:
2654  */
2655 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2656                       struct lock_class_key *key, int subclass)
2657 {
2658         lock->class_cache = NULL;
2659 #ifdef CONFIG_LOCK_STAT
2660         lock->cpu = raw_smp_processor_id();
2661 #endif
2662
2663         if (DEBUG_LOCKS_WARN_ON(!name)) {
2664                 lock->name = "NULL";
2665                 return;
2666         }
2667
2668         lock->name = name;
2669
2670         if (DEBUG_LOCKS_WARN_ON(!key))
2671                 return;
2672         /*
2673          * Sanity check, the lock-class key must be persistent:
2674          */
2675         if (!static_obj(key)) {
2676                 printk("BUG: key %p not in .data!\n", key);
2677                 DEBUG_LOCKS_WARN_ON(1);
2678                 return;
2679         }
2680         lock->key = key;
2681
2682         if (unlikely(!debug_locks))
2683                 return;
2684
2685         if (subclass)
2686                 register_lock_class(lock, subclass, 1);
2687 }
2688 EXPORT_SYMBOL_GPL(lockdep_init_map);
2689
2690 /*
2691  * This gets called for every mutex_lock*()/spin_lock*() operation.
2692  * We maintain the dependency maps and validate the locking attempt:
2693  */
2694 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2695                           int trylock, int read, int check, int hardirqs_off,
2696                           struct lockdep_map *nest_lock, unsigned long ip)
2697 {
2698         struct task_struct *curr = current;
2699         struct lock_class *class = NULL;
2700         struct held_lock *hlock;
2701         unsigned int depth, id;
2702         int chain_head = 0;
2703         u64 chain_key;
2704
2705         if (!prove_locking)
2706                 check = 1;
2707
2708         if (unlikely(!debug_locks))
2709                 return 0;
2710
2711         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2712                 return 0;
2713
2714         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2715                 debug_locks_off();
2716                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2717                 printk("turning off the locking correctness validator.\n");
2718                 dump_stack();
2719                 return 0;
2720         }
2721
2722         if (!subclass)
2723                 class = lock->class_cache;
2724         /*
2725          * Not cached yet or subclass?
2726          */
2727         if (unlikely(!class)) {
2728                 class = register_lock_class(lock, subclass, 0);
2729                 if (!class)
2730                         return 0;
2731         }
2732         debug_atomic_inc((atomic_t *)&class->ops);
2733         if (very_verbose(class)) {
2734                 printk("\nacquire class [%p] %s", class->key, class->name);
2735                 if (class->name_version > 1)
2736                         printk("#%d", class->name_version);
2737                 printk("\n");
2738                 dump_stack();
2739         }
2740
2741         /*
2742          * Add the lock to the list of currently held locks.
2743          * (we dont increase the depth just yet, up until the
2744          * dependency checks are done)
2745          */
2746         depth = curr->lockdep_depth;
2747         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2748                 return 0;
2749
2750         hlock = curr->held_locks + depth;
2751         if (DEBUG_LOCKS_WARN_ON(!class))
2752                 return 0;
2753         hlock->class_idx = class - lock_classes + 1;
2754         hlock->acquire_ip = ip;
2755         hlock->instance = lock;
2756         hlock->nest_lock = nest_lock;
2757         hlock->trylock = trylock;
2758         hlock->read = read;
2759         hlock->check = check;
2760         hlock->hardirqs_off = !!hardirqs_off;
2761 #ifdef CONFIG_LOCK_STAT
2762         hlock->waittime_stamp = 0;
2763         hlock->holdtime_stamp = sched_clock();
2764 #endif
2765
2766         if (check == 2 && !mark_irqflags(curr, hlock))
2767                 return 0;
2768
2769         /* mark it as used: */
2770         if (!mark_lock(curr, hlock, LOCK_USED))
2771                 return 0;
2772
2773         /*
2774          * Calculate the chain hash: it's the combined hash of all the
2775          * lock keys along the dependency chain. We save the hash value
2776          * at every step so that we can get the current hash easily
2777          * after unlock. The chain hash is then used to cache dependency
2778          * results.
2779          *
2780          * The 'key ID' is what is the most compact key value to drive
2781          * the hash, not class->key.
2782          */
2783         id = class - lock_classes;
2784         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2785                 return 0;
2786
2787         chain_key = curr->curr_chain_key;
2788         if (!depth) {
2789                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2790                         return 0;
2791                 chain_head = 1;
2792         }
2793
2794         hlock->prev_chain_key = chain_key;
2795         if (separate_irq_context(curr, hlock)) {
2796                 chain_key = 0;
2797                 chain_head = 1;
2798         }
2799         chain_key = iterate_chain_key(chain_key, id);
2800
2801         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2802                 return 0;
2803
2804         curr->curr_chain_key = chain_key;
2805         curr->lockdep_depth++;
2806         check_chain_key(curr);
2807 #ifdef CONFIG_DEBUG_LOCKDEP
2808         if (unlikely(!debug_locks))
2809                 return 0;
2810 #endif
2811         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2812                 debug_locks_off();
2813                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2814                 printk("turning off the locking correctness validator.\n");
2815                 dump_stack();
2816                 return 0;
2817         }
2818
2819         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2820                 max_lockdep_depth = curr->lockdep_depth;
2821
2822         return 1;
2823 }
2824
2825 static int
2826 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2827                            unsigned long ip)
2828 {
2829         if (!debug_locks_off())
2830                 return 0;
2831         if (debug_locks_silent)
2832                 return 0;
2833
2834         printk("\n=====================================\n");
2835         printk(  "[ BUG: bad unlock balance detected! ]\n");
2836         printk(  "-------------------------------------\n");
2837         printk("%s/%d is trying to release lock (",
2838                 curr->comm, task_pid_nr(curr));
2839         print_lockdep_cache(lock);
2840         printk(") at:\n");
2841         print_ip_sym(ip);
2842         printk("but there are no more locks to release!\n");
2843         printk("\nother info that might help us debug this:\n");
2844         lockdep_print_held_locks(curr);
2845
2846         printk("\nstack backtrace:\n");
2847         dump_stack();
2848
2849         return 0;
2850 }
2851
2852 /*
2853  * Common debugging checks for both nested and non-nested unlock:
2854  */
2855 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2856                         unsigned long ip)
2857 {
2858         if (unlikely(!debug_locks))
2859                 return 0;
2860         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2861                 return 0;
2862
2863         if (curr->lockdep_depth <= 0)
2864                 return print_unlock_inbalance_bug(curr, lock, ip);
2865
2866         return 1;
2867 }
2868
2869 static int
2870 __lock_set_class(struct lockdep_map *lock, const char *name,
2871                  struct lock_class_key *key, unsigned int subclass,
2872                  unsigned long ip)
2873 {
2874         struct task_struct *curr = current;
2875         struct held_lock *hlock, *prev_hlock;
2876         struct lock_class *class;
2877         unsigned int depth;
2878         int i;
2879
2880         depth = curr->lockdep_depth;
2881         if (DEBUG_LOCKS_WARN_ON(!depth))
2882                 return 0;
2883
2884         prev_hlock = NULL;
2885         for (i = depth-1; i >= 0; i--) {
2886                 hlock = curr->held_locks + i;
2887                 /*
2888                  * We must not cross into another context:
2889                  */
2890                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2891                         break;
2892                 if (hlock->instance == lock)
2893                         goto found_it;
2894                 prev_hlock = hlock;
2895         }
2896         return print_unlock_inbalance_bug(curr, lock, ip);
2897
2898 found_it:
2899         lockdep_init_map(lock, name, key, 0);
2900         class = register_lock_class(lock, subclass, 0);
2901         hlock->class_idx = class - lock_classes + 1;
2902
2903         curr->lockdep_depth = i;
2904         curr->curr_chain_key = hlock->prev_chain_key;
2905
2906         for (; i < depth; i++) {
2907                 hlock = curr->held_locks + i;
2908                 if (!__lock_acquire(hlock->instance,
2909                         hlock_class(hlock)->subclass, hlock->trylock,
2910                                 hlock->read, hlock->check, hlock->hardirqs_off,
2911                                 hlock->nest_lock, hlock->acquire_ip))
2912                         return 0;
2913         }
2914
2915         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2916                 return 0;
2917         return 1;
2918 }
2919
2920 /*
2921  * Remove the lock to the list of currently held locks in a
2922  * potentially non-nested (out of order) manner. This is a
2923  * relatively rare operation, as all the unlock APIs default
2924  * to nested mode (which uses lock_release()):
2925  */
2926 static int
2927 lock_release_non_nested(struct task_struct *curr,
2928                         struct lockdep_map *lock, unsigned long ip)
2929 {
2930         struct held_lock *hlock, *prev_hlock;
2931         unsigned int depth;
2932         int i;
2933
2934         /*
2935          * Check whether the lock exists in the current stack
2936          * of held locks:
2937          */
2938         depth = curr->lockdep_depth;
2939         if (DEBUG_LOCKS_WARN_ON(!depth))
2940                 return 0;
2941
2942         prev_hlock = NULL;
2943         for (i = depth-1; i >= 0; i--) {
2944                 hlock = curr->held_locks + i;
2945                 /*
2946                  * We must not cross into another context:
2947                  */
2948                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2949                         break;
2950                 if (hlock->instance == lock)
2951                         goto found_it;
2952                 prev_hlock = hlock;
2953         }
2954         return print_unlock_inbalance_bug(curr, lock, ip);
2955
2956 found_it:
2957         lock_release_holdtime(hlock);
2958
2959         /*
2960          * We have the right lock to unlock, 'hlock' points to it.
2961          * Now we remove it from the stack, and add back the other
2962          * entries (if any), recalculating the hash along the way:
2963          */
2964         curr->lockdep_depth = i;
2965         curr->curr_chain_key = hlock->prev_chain_key;
2966
2967         for (i++; i < depth; i++) {
2968                 hlock = curr->held_locks + i;
2969                 if (!__lock_acquire(hlock->instance,
2970                         hlock_class(hlock)->subclass, hlock->trylock,
2971                                 hlock->read, hlock->check, hlock->hardirqs_off,
2972                                 hlock->nest_lock, hlock->acquire_ip))
2973                         return 0;
2974         }
2975
2976         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2977                 return 0;
2978         return 1;
2979 }
2980
2981 /*
2982  * Remove the lock to the list of currently held locks - this gets
2983  * called on mutex_unlock()/spin_unlock*() (or on a failed
2984  * mutex_lock_interruptible()). This is done for unlocks that nest
2985  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2986  */
2987 static int lock_release_nested(struct task_struct *curr,
2988                                struct lockdep_map *lock, unsigned long ip)
2989 {
2990         struct held_lock *hlock;
2991         unsigned int depth;
2992
2993         /*
2994          * Pop off the top of the lock stack:
2995          */
2996         depth = curr->lockdep_depth - 1;
2997         hlock = curr->held_locks + depth;
2998
2999         /*
3000          * Is the unlock non-nested:
3001          */
3002         if (hlock->instance != lock)
3003                 return lock_release_non_nested(curr, lock, ip);
3004         curr->lockdep_depth--;
3005
3006         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3007                 return 0;
3008
3009         curr->curr_chain_key = hlock->prev_chain_key;
3010
3011         lock_release_holdtime(hlock);
3012
3013 #ifdef CONFIG_DEBUG_LOCKDEP
3014         hlock->prev_chain_key = 0;
3015         hlock->class_idx = 0;
3016         hlock->acquire_ip = 0;
3017         hlock->irq_context = 0;
3018 #endif
3019         return 1;
3020 }
3021
3022 /*
3023  * Remove the lock to the list of currently held locks - this gets
3024  * called on mutex_unlock()/spin_unlock*() (or on a failed
3025  * mutex_lock_interruptible()). This is done for unlocks that nest
3026  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3027  */
3028 static void
3029 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3030 {
3031         struct task_struct *curr = current;
3032
3033         if (!check_unlock(curr, lock, ip))
3034                 return;
3035
3036         if (nested) {
3037                 if (!lock_release_nested(curr, lock, ip))
3038                         return;
3039         } else {
3040                 if (!lock_release_non_nested(curr, lock, ip))
3041                         return;
3042         }
3043
3044         check_chain_key(curr);
3045 }
3046
3047 /*
3048  * Check whether we follow the irq-flags state precisely:
3049  */
3050 static void check_flags(unsigned long flags)
3051 {
3052 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3053     defined(CONFIG_TRACE_IRQFLAGS)
3054         if (!debug_locks)
3055                 return;
3056
3057         if (irqs_disabled_flags(flags)) {
3058                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3059                         printk("possible reason: unannotated irqs-off.\n");
3060                 }
3061         } else {
3062                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3063                         printk("possible reason: unannotated irqs-on.\n");
3064                 }
3065         }
3066
3067         /*
3068          * We dont accurately track softirq state in e.g.
3069          * hardirq contexts (such as on 4KSTACKS), so only
3070          * check if not in hardirq contexts:
3071          */
3072         if (!hardirq_count()) {
3073                 if (softirq_count())
3074                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3075                 else
3076                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3077         }
3078
3079         if (!debug_locks)
3080                 print_irqtrace_events(current);
3081 #endif
3082 }
3083
3084 void lock_set_class(struct lockdep_map *lock, const char *name,
3085                     struct lock_class_key *key, unsigned int subclass,
3086                     unsigned long ip)
3087 {
3088         unsigned long flags;
3089
3090         if (unlikely(current->lockdep_recursion))
3091                 return;
3092
3093         raw_local_irq_save(flags);
3094         current->lockdep_recursion = 1;
3095         check_flags(flags);
3096         if (__lock_set_class(lock, name, key, subclass, ip))
3097                 check_chain_key(current);
3098         current->lockdep_recursion = 0;
3099         raw_local_irq_restore(flags);
3100 }
3101 EXPORT_SYMBOL_GPL(lock_set_class);
3102
3103 /*
3104  * We are not always called with irqs disabled - do that here,
3105  * and also avoid lockdep recursion:
3106  */
3107 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3108                           int trylock, int read, int check,
3109                           struct lockdep_map *nest_lock, unsigned long ip)
3110 {
3111         unsigned long flags;
3112
3113         trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3114
3115         if (unlikely(current->lockdep_recursion))
3116                 return;
3117
3118         raw_local_irq_save(flags);
3119         check_flags(flags);
3120
3121         current->lockdep_recursion = 1;
3122         __lock_acquire(lock, subclass, trylock, read, check,
3123                        irqs_disabled_flags(flags), nest_lock, ip);
3124         current->lockdep_recursion = 0;
3125         raw_local_irq_restore(flags);
3126 }
3127 EXPORT_SYMBOL_GPL(lock_acquire);
3128
3129 void lock_release(struct lockdep_map *lock, int nested,
3130                           unsigned long ip)
3131 {
3132         unsigned long flags;
3133
3134         trace_lock_release(lock, nested, ip);
3135
3136         if (unlikely(current->lockdep_recursion))
3137                 return;
3138
3139         raw_local_irq_save(flags);
3140         check_flags(flags);
3141         current->lockdep_recursion = 1;
3142         __lock_release(lock, nested, ip);
3143         current->lockdep_recursion = 0;
3144         raw_local_irq_restore(flags);
3145 }
3146 EXPORT_SYMBOL_GPL(lock_release);
3147
3148 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3149 {
3150         current->lockdep_reclaim_gfp = gfp_mask;
3151 }
3152
3153 void lockdep_clear_current_reclaim_state(void)
3154 {
3155         current->lockdep_reclaim_gfp = 0;
3156 }
3157
3158 #ifdef CONFIG_LOCK_STAT
3159 static int
3160 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3161                            unsigned long ip)
3162 {
3163         if (!debug_locks_off())
3164                 return 0;
3165         if (debug_locks_silent)
3166                 return 0;
3167
3168         printk("\n=================================\n");
3169         printk(  "[ BUG: bad contention detected! ]\n");
3170         printk(  "---------------------------------\n");
3171         printk("%s/%d is trying to contend lock (",
3172                 curr->comm, task_pid_nr(curr));
3173         print_lockdep_cache(lock);
3174         printk(") at:\n");
3175         print_ip_sym(ip);
3176         printk("but there are no locks held!\n");
3177         printk("\nother info that might help us debug this:\n");
3178         lockdep_print_held_locks(curr);
3179
3180         printk("\nstack backtrace:\n");
3181         dump_stack();
3182
3183         return 0;
3184 }
3185
3186 static void
3187 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3188 {
3189         struct task_struct *curr = current;
3190         struct held_lock *hlock, *prev_hlock;
3191         struct lock_class_stats *stats;
3192         unsigned int depth;
3193         int i, contention_point, contending_point;
3194
3195         depth = curr->lockdep_depth;
3196         if (DEBUG_LOCKS_WARN_ON(!depth))
3197                 return;
3198
3199         prev_hlock = NULL;
3200         for (i = depth-1; i >= 0; i--) {
3201                 hlock = curr->held_locks + i;
3202                 /*
3203                  * We must not cross into another context:
3204                  */
3205                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3206                         break;
3207                 if (hlock->instance == lock)
3208                         goto found_it;
3209                 prev_hlock = hlock;
3210         }
3211         print_lock_contention_bug(curr, lock, ip);
3212         return;
3213
3214 found_it:
3215         hlock->waittime_stamp = sched_clock();
3216
3217         contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3218         contending_point = lock_point(hlock_class(hlock)->contending_point,
3219                                       lock->ip);
3220
3221         stats = get_lock_stats(hlock_class(hlock));
3222         if (contention_point < LOCKSTAT_POINTS)
3223                 stats->contention_point[contention_point]++;
3224         if (contending_point < LOCKSTAT_POINTS)
3225                 stats->contending_point[contending_point]++;
3226         if (lock->cpu != smp_processor_id())
3227                 stats->bounces[bounce_contended + !!hlock->read]++;
3228         put_lock_stats(stats);
3229 }
3230
3231 static void
3232 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3233 {
3234         struct task_struct *curr = current;
3235         struct held_lock *hlock, *prev_hlock;
3236         struct lock_class_stats *stats;
3237         unsigned int depth;
3238         u64 now;
3239         s64 waittime = 0;
3240         int i, cpu;
3241
3242         depth = curr->lockdep_depth;
3243         if (DEBUG_LOCKS_WARN_ON(!depth))
3244                 return;
3245
3246         prev_hlock = NULL;
3247         for (i = depth-1; i >= 0; i--) {
3248                 hlock = curr->held_locks + i;
3249                 /*
3250                  * We must not cross into another context:
3251                  */
3252                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3253                         break;
3254                 if (hlock->instance == lock)
3255                         goto found_it;
3256                 prev_hlock = hlock;
3257         }
3258         print_lock_contention_bug(curr, lock, _RET_IP_);
3259         return;
3260
3261 found_it:
3262         cpu = smp_processor_id();
3263         if (hlock->waittime_stamp) {
3264                 now = sched_clock();
3265                 waittime = now - hlock->waittime_stamp;
3266                 hlock->holdtime_stamp = now;
3267         }
3268
3269         trace_lock_acquired(lock, ip, waittime);
3270
3271         stats = get_lock_stats(hlock_class(hlock));
3272         if (waittime) {
3273                 if (hlock->read)
3274                         lock_time_inc(&stats->read_waittime, waittime);
3275                 else
3276                         lock_time_inc(&stats->write_waittime, waittime);
3277         }
3278         if (lock->cpu != cpu)
3279                 stats->bounces[bounce_acquired + !!hlock->read]++;
3280         put_lock_stats(stats);
3281
3282         lock->cpu = cpu;
3283         lock->ip = ip;
3284 }
3285
3286 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3287 {
3288         unsigned long flags;
3289
3290         trace_lock_contended(lock, ip);
3291
3292         if (unlikely(!lock_stat))
3293                 return;
3294
3295         if (unlikely(current->lockdep_recursion))
3296                 return;
3297
3298         raw_local_irq_save(flags);
3299         check_flags(flags);
3300         current->lockdep_recursion = 1;
3301         __lock_contended(lock, ip);
3302         current->lockdep_recursion = 0;
3303         raw_local_irq_restore(flags);
3304 }
3305 EXPORT_SYMBOL_GPL(lock_contended);
3306
3307 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3308 {
3309         unsigned long flags;
3310
3311         if (unlikely(!lock_stat))
3312                 return;
3313
3314         if (unlikely(current->lockdep_recursion))
3315                 return;
3316
3317         raw_local_irq_save(flags);
3318         check_flags(flags);
3319         current->lockdep_recursion = 1;
3320         __lock_acquired(lock, ip);
3321         current->lockdep_recursion = 0;
3322         raw_local_irq_restore(flags);
3323 }
3324 EXPORT_SYMBOL_GPL(lock_acquired);
3325 #endif
3326
3327 /*
3328  * Used by the testsuite, sanitize the validator state
3329  * after a simulated failure:
3330  */
3331
3332 void lockdep_reset(void)
3333 {
3334         unsigned long flags;
3335         int i;
3336
3337         raw_local_irq_save(flags);
3338         current->curr_chain_key = 0;
3339         current->lockdep_depth = 0;
3340         current->lockdep_recursion = 0;
3341         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3342         nr_hardirq_chains = 0;
3343         nr_softirq_chains = 0;
3344         nr_process_chains = 0;
3345         debug_locks = 1;
3346         for (i = 0; i < CHAINHASH_SIZE; i++)
3347                 INIT_LIST_HEAD(chainhash_table + i);
3348         raw_local_irq_restore(flags);
3349 }
3350
3351 static void zap_class(struct lock_class *class)
3352 {
3353         int i;
3354
3355         /*
3356          * Remove all dependencies this lock is
3357          * involved in:
3358          */
3359         for (i = 0; i < nr_list_entries; i++) {
3360                 if (list_entries[i].class == class)
3361                         list_del_rcu(&list_entries[i].entry);
3362         }
3363         /*
3364          * Unhash the class and remove it from the all_lock_classes list:
3365          */
3366         list_del_rcu(&class->hash_entry);
3367         list_del_rcu(&class->lock_entry);
3368
3369         class->key = NULL;
3370 }
3371
3372 static inline int within(const void *addr, void *start, unsigned long size)
3373 {
3374         return addr >= start && addr < start + size;
3375 }
3376
3377 void lockdep_free_key_range(void *start, unsigned long size)
3378 {
3379         struct lock_class *class, *next;
3380         struct list_head *head;
3381         unsigned long flags;
3382         int i;
3383         int locked;
3384
3385         raw_local_irq_save(flags);
3386         locked = graph_lock();
3387
3388         /*
3389          * Unhash all classes that were created by this module:
3390          */
3391         for (i = 0; i < CLASSHASH_SIZE; i++) {
3392                 head = classhash_table + i;
3393                 if (list_empty(head))
3394                         continue;
3395                 list_for_each_entry_safe(class, next, head, hash_entry) {
3396                         if (within(class->key, start, size))
3397                                 zap_class(class);
3398                         else if (within(class->name, start, size))
3399                                 zap_class(class);
3400                 }
3401         }
3402
3403         if (locked)
3404                 graph_unlock();
3405         raw_local_irq_restore(flags);
3406 }
3407
3408 void lockdep_reset_lock(struct lockdep_map *lock)
3409 {
3410         struct lock_class *class, *next;
3411         struct list_head *head;
3412         unsigned long flags;
3413         int i, j;
3414         int locked;
3415
3416         raw_local_irq_save(flags);
3417
3418         /*
3419          * Remove all classes this lock might have:
3420          */
3421         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3422                 /*
3423                  * If the class exists we look it up and zap it:
3424                  */
3425                 class = look_up_lock_class(lock, j);
3426                 if (class)
3427                         zap_class(class);
3428         }
3429         /*
3430          * Debug check: in the end all mapped classes should
3431          * be gone.
3432          */
3433         locked = graph_lock();
3434         for (i = 0; i < CLASSHASH_SIZE; i++) {
3435                 head = classhash_table + i;
3436                 if (list_empty(head))
3437                         continue;
3438                 list_for_each_entry_safe(class, next, head, hash_entry) {
3439                         if (unlikely(class == lock->class_cache)) {
3440                                 if (debug_locks_off_graph_unlock())
3441                                         WARN_ON(1);
3442                                 goto out_restore;
3443                         }
3444                 }
3445         }
3446         if (locked)
3447                 graph_unlock();
3448
3449 out_restore:
3450         raw_local_irq_restore(flags);
3451 }
3452
3453 void lockdep_init(void)
3454 {
3455         int i;
3456
3457         /*
3458          * Some architectures have their own start_kernel()
3459          * code which calls lockdep_init(), while we also
3460          * call lockdep_init() from the start_kernel() itself,
3461          * and we want to initialize the hashes only once:
3462          */
3463         if (lockdep_initialized)
3464                 return;
3465
3466         for (i = 0; i < CLASSHASH_SIZE; i++)
3467                 INIT_LIST_HEAD(classhash_table + i);
3468
3469         for (i = 0; i < CHAINHASH_SIZE; i++)
3470                 INIT_LIST_HEAD(chainhash_table + i);
3471
3472         lockdep_initialized = 1;
3473 }
3474
3475 void __init lockdep_info(void)
3476 {
3477         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3478
3479         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3480         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3481         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3482         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3483         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3484         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3485         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3486
3487         printk(" memory used by lock dependency info: %lu kB\n",
3488                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3489                 sizeof(struct list_head) * CLASSHASH_SIZE +
3490                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3491                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3492                 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024
3493 #ifdef CONFIG_PROVE_LOCKING
3494                 + sizeof(struct circular_queue) + sizeof(bfs_accessed)
3495 #endif
3496                 );
3497
3498         printk(" per task-struct memory footprint: %lu bytes\n",
3499                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3500
3501 #ifdef CONFIG_DEBUG_LOCKDEP
3502         if (lockdep_init_error) {
3503                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3504                 printk("Call stack leading to lockdep invocation was:\n");
3505                 print_stack_trace(&lockdep_init_trace, 0);
3506         }
3507 #endif
3508 }
3509
3510 static void
3511 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3512                      const void *mem_to, struct held_lock *hlock)
3513 {
3514         if (!debug_locks_off())
3515                 return;
3516         if (debug_locks_silent)
3517                 return;
3518
3519         printk("\n=========================\n");
3520         printk(  "[ BUG: held lock freed! ]\n");
3521         printk(  "-------------------------\n");
3522         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3523                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3524         print_lock(hlock);
3525         lockdep_print_held_locks(curr);
3526
3527         printk("\nstack backtrace:\n");
3528         dump_stack();
3529 }
3530
3531 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3532                                 const void* lock_from, unsigned long lock_len)
3533 {
3534         return lock_from + lock_len <= mem_from ||
3535                 mem_from + mem_len <= lock_from;
3536 }
3537
3538 /*
3539  * Called when kernel memory is freed (or unmapped), or if a lock
3540  * is destroyed or reinitialized - this code checks whether there is
3541  * any held lock in the memory range of <from> to <to>:
3542  */
3543 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3544 {
3545         struct task_struct *curr = current;
3546         struct held_lock *hlock;
3547         unsigned long flags;
3548         int i;
3549
3550         if (unlikely(!debug_locks))
3551                 return;
3552
3553         local_irq_save(flags);
3554         for (i = 0; i < curr->lockdep_depth; i++) {
3555                 hlock = curr->held_locks + i;
3556
3557                 if (not_in_range(mem_from, mem_len, hlock->instance,
3558                                         sizeof(*hlock->instance)))
3559                         continue;
3560
3561                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3562                 break;
3563         }
3564         local_irq_restore(flags);
3565 }
3566 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3567
3568 static void print_held_locks_bug(struct task_struct *curr)
3569 {
3570         if (!debug_locks_off())
3571                 return;
3572         if (debug_locks_silent)
3573                 return;
3574
3575         printk("\n=====================================\n");
3576         printk(  "[ BUG: lock held at task exit time! ]\n");
3577         printk(  "-------------------------------------\n");
3578         printk("%s/%d is exiting with locks still held!\n",
3579                 curr->comm, task_pid_nr(curr));
3580         lockdep_print_held_locks(curr);
3581
3582         printk("\nstack backtrace:\n");
3583         dump_stack();
3584 }
3585
3586 void debug_check_no_locks_held(struct task_struct *task)
3587 {
3588         if (unlikely(task->lockdep_depth > 0))
3589                 print_held_locks_bug(task);
3590 }
3591
3592 void debug_show_all_locks(void)
3593 {
3594         struct task_struct *g, *p;
3595         int count = 10;
3596         int unlock = 1;
3597
3598         if (unlikely(!debug_locks)) {
3599                 printk("INFO: lockdep is turned off.\n");
3600                 return;
3601         }
3602         printk("\nShowing all locks held in the system:\n");
3603
3604         /*
3605          * Here we try to get the tasklist_lock as hard as possible,
3606          * if not successful after 2 seconds we ignore it (but keep
3607          * trying). This is to enable a debug printout even if a
3608          * tasklist_lock-holding task deadlocks or crashes.
3609          */
3610 retry:
3611         if (!read_trylock(&tasklist_lock)) {
3612                 if (count == 10)
3613                         printk("hm, tasklist_lock locked, retrying... ");
3614                 if (count) {
3615                         count--;
3616                         printk(" #%d", 10-count);
3617                         mdelay(200);
3618                         goto retry;
3619                 }
3620                 printk(" ignoring it.\n");
3621                 unlock = 0;
3622         } else {
3623                 if (count != 10)
3624                         printk(KERN_CONT " locked it.\n");
3625         }
3626
3627         do_each_thread(g, p) {
3628                 /*
3629                  * It's not reliable to print a task's held locks
3630                  * if it's not sleeping (or if it's not the current
3631                  * task):
3632                  */
3633                 if (p->state == TASK_RUNNING && p != current)
3634                         continue;
3635                 if (p->lockdep_depth)
3636                         lockdep_print_held_locks(p);
3637                 if (!unlock)
3638                         if (read_trylock(&tasklist_lock))
3639                                 unlock = 1;
3640         } while_each_thread(g, p);
3641
3642         printk("\n");
3643         printk("=============================================\n\n");
3644
3645         if (unlock)
3646                 read_unlock(&tasklist_lock);
3647 }
3648 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3649
3650 /*
3651  * Careful: only use this function if you are sure that
3652  * the task cannot run in parallel!
3653  */
3654 void __debug_show_held_locks(struct task_struct *task)
3655 {
3656         if (unlikely(!debug_locks)) {
3657                 printk("INFO: lockdep is turned off.\n");
3658                 return;
3659         }
3660         lockdep_print_held_locks(task);
3661 }
3662 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3663
3664 void debug_show_held_locks(struct task_struct *task)
3665 {
3666                 __debug_show_held_locks(task);
3667 }
3668 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3669
3670 void lockdep_sys_exit(void)
3671 {
3672         struct task_struct *curr = current;
3673
3674         if (unlikely(curr->lockdep_depth)) {
3675                 if (!debug_locks_off())
3676                         return;
3677                 printk("\n================================================\n");
3678                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3679                 printk(  "------------------------------------------------\n");
3680                 printk("%s/%d is leaving the kernel with locks still held!\n",
3681                                 curr->comm, curr->pid);
3682                 lockdep_print_held_locks(curr);
3683         }
3684 }