sched_clock: Add local_clock() API and improve documentation
[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 #include <linux/gfp.h>
47
48 #include <asm/sections.h>
49
50 #include "lockdep_internals.h"
51
52 #define CREATE_TRACE_POINTS
53 #include <trace/events/lock.h>
54
55 #ifdef CONFIG_PROVE_LOCKING
56 int prove_locking = 1;
57 module_param(prove_locking, int, 0644);
58 #else
59 #define prove_locking 0
60 #endif
61
62 #ifdef CONFIG_LOCK_STAT
63 int lock_stat = 1;
64 module_param(lock_stat, int, 0644);
65 #else
66 #define lock_stat 0
67 #endif
68
69 /*
70  * lockdep_lock: protects the lockdep graph, the hashes and the
71  *               class/list/hash allocators.
72  *
73  * This is one of the rare exceptions where it's justified
74  * to use a raw spinlock - we really dont want the spinlock
75  * code to recurse back into the lockdep code...
76  */
77 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
78
79 static int graph_lock(void)
80 {
81         arch_spin_lock(&lockdep_lock);
82         /*
83          * Make sure that if another CPU detected a bug while
84          * walking the graph we dont change it (while the other
85          * CPU is busy printing out stuff with the graph lock
86          * dropped already)
87          */
88         if (!debug_locks) {
89                 arch_spin_unlock(&lockdep_lock);
90                 return 0;
91         }
92         /* prevent any recursions within lockdep from causing deadlocks */
93         current->lockdep_recursion++;
94         return 1;
95 }
96
97 static inline int graph_unlock(void)
98 {
99         if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
100                 return DEBUG_LOCKS_WARN_ON(1);
101
102         current->lockdep_recursion--;
103         arch_spin_unlock(&lockdep_lock);
104         return 0;
105 }
106
107 /*
108  * Turn lock debugging off and return with 0 if it was off already,
109  * and also release the graph lock:
110  */
111 static inline int debug_locks_off_graph_unlock(void)
112 {
113         int ret = debug_locks_off();
114
115         arch_spin_unlock(&lockdep_lock);
116
117         return ret;
118 }
119
120 static int lockdep_initialized;
121
122 unsigned long nr_list_entries;
123 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
124
125 /*
126  * All data structures here are protected by the global debug_lock.
127  *
128  * Mutex key structs only get allocated, once during bootup, and never
129  * get freed - this significantly simplifies the debugging code.
130  */
131 unsigned long nr_lock_classes;
132 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
133
134 static inline struct lock_class *hlock_class(struct held_lock *hlock)
135 {
136         if (!hlock->class_idx) {
137                 DEBUG_LOCKS_WARN_ON(1);
138                 return NULL;
139         }
140         return lock_classes + hlock->class_idx - 1;
141 }
142
143 #ifdef CONFIG_LOCK_STAT
144 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
145                       cpu_lock_stats);
146
147 static inline u64 lockstat_clock(void)
148 {
149         return local_clock();
150 }
151
152 static int lock_point(unsigned long points[], unsigned long ip)
153 {
154         int i;
155
156         for (i = 0; i < LOCKSTAT_POINTS; i++) {
157                 if (points[i] == 0) {
158                         points[i] = ip;
159                         break;
160                 }
161                 if (points[i] == ip)
162                         break;
163         }
164
165         return i;
166 }
167
168 static void lock_time_inc(struct lock_time *lt, u64 time)
169 {
170         if (time > lt->max)
171                 lt->max = time;
172
173         if (time < lt->min || !lt->nr)
174                 lt->min = time;
175
176         lt->total += time;
177         lt->nr++;
178 }
179
180 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
181 {
182         if (!src->nr)
183                 return;
184
185         if (src->max > dst->max)
186                 dst->max = src->max;
187
188         if (src->min < dst->min || !dst->nr)
189                 dst->min = src->min;
190
191         dst->total += src->total;
192         dst->nr += src->nr;
193 }
194
195 struct lock_class_stats lock_stats(struct lock_class *class)
196 {
197         struct lock_class_stats stats;
198         int cpu, i;
199
200         memset(&stats, 0, sizeof(struct lock_class_stats));
201         for_each_possible_cpu(cpu) {
202                 struct lock_class_stats *pcs =
203                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
204
205                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
206                         stats.contention_point[i] += pcs->contention_point[i];
207
208                 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
209                         stats.contending_point[i] += pcs->contending_point[i];
210
211                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
212                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
213
214                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
215                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
216
217                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
218                         stats.bounces[i] += pcs->bounces[i];
219         }
220
221         return stats;
222 }
223
224 void clear_lock_stats(struct lock_class *class)
225 {
226         int cpu;
227
228         for_each_possible_cpu(cpu) {
229                 struct lock_class_stats *cpu_stats =
230                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
231
232                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
233         }
234         memset(class->contention_point, 0, sizeof(class->contention_point));
235         memset(class->contending_point, 0, sizeof(class->contending_point));
236 }
237
238 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
239 {
240         return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
241 }
242
243 static void put_lock_stats(struct lock_class_stats *stats)
244 {
245         put_cpu_var(cpu_lock_stats);
246 }
247
248 static void lock_release_holdtime(struct held_lock *hlock)
249 {
250         struct lock_class_stats *stats;
251         u64 holdtime;
252
253         if (!lock_stat)
254                 return;
255
256         holdtime = lockstat_clock() - hlock->holdtime_stamp;
257
258         stats = get_lock_stats(hlock_class(hlock));
259         if (hlock->read)
260                 lock_time_inc(&stats->read_holdtime, holdtime);
261         else
262                 lock_time_inc(&stats->write_holdtime, holdtime);
263         put_lock_stats(stats);
264 }
265 #else
266 static inline void lock_release_holdtime(struct held_lock *hlock)
267 {
268 }
269 #endif
270
271 /*
272  * We keep a global list of all lock classes. The list only grows,
273  * never shrinks. The list is only accessed with the lockdep
274  * spinlock lock held.
275  */
276 LIST_HEAD(all_lock_classes);
277
278 /*
279  * The lockdep classes are in a hash-table as well, for fast lookup:
280  */
281 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
282 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
283 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
284 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
285
286 static struct list_head classhash_table[CLASSHASH_SIZE];
287
288 /*
289  * We put the lock dependency chains into a hash-table as well, to cache
290  * their existence:
291  */
292 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
293 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
294 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
295 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
296
297 static struct list_head chainhash_table[CHAINHASH_SIZE];
298
299 /*
300  * The hash key of the lock dependency chains is a hash itself too:
301  * it's a hash of all locks taken up to that lock, including that lock.
302  * It's a 64-bit hash, because it's important for the keys to be
303  * unique.
304  */
305 #define iterate_chain_key(key1, key2) \
306         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
307         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
308         (key2))
309
310 void lockdep_off(void)
311 {
312         current->lockdep_recursion++;
313 }
314 EXPORT_SYMBOL(lockdep_off);
315
316 void lockdep_on(void)
317 {
318         current->lockdep_recursion--;
319 }
320 EXPORT_SYMBOL(lockdep_on);
321
322 /*
323  * Debugging switches:
324  */
325
326 #define VERBOSE                 0
327 #define VERY_VERBOSE            0
328
329 #if VERBOSE
330 # define HARDIRQ_VERBOSE        1
331 # define SOFTIRQ_VERBOSE        1
332 # define RECLAIM_VERBOSE        1
333 #else
334 # define HARDIRQ_VERBOSE        0
335 # define SOFTIRQ_VERBOSE        0
336 # define RECLAIM_VERBOSE        0
337 #endif
338
339 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
340 /*
341  * Quick filtering for interesting events:
342  */
343 static int class_filter(struct lock_class *class)
344 {
345 #if 0
346         /* Example */
347         if (class->name_version == 1 &&
348                         !strcmp(class->name, "lockname"))
349                 return 1;
350         if (class->name_version == 1 &&
351                         !strcmp(class->name, "&struct->lockfield"))
352                 return 1;
353 #endif
354         /* Filter everything else. 1 would be to allow everything else */
355         return 0;
356 }
357 #endif
358
359 static int verbose(struct lock_class *class)
360 {
361 #if VERBOSE
362         return class_filter(class);
363 #endif
364         return 0;
365 }
366
367 /*
368  * Stack-trace: tightly packed array of stack backtrace
369  * addresses. Protected by the graph_lock.
370  */
371 unsigned long nr_stack_trace_entries;
372 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
373
374 static int save_trace(struct stack_trace *trace)
375 {
376         trace->nr_entries = 0;
377         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
378         trace->entries = stack_trace + nr_stack_trace_entries;
379
380         trace->skip = 3;
381
382         save_stack_trace(trace);
383
384         /*
385          * Some daft arches put -1 at the end to indicate its a full trace.
386          *
387          * <rant> this is buggy anyway, since it takes a whole extra entry so a
388          * complete trace that maxes out the entries provided will be reported
389          * as incomplete, friggin useless </rant>
390          */
391         if (trace->nr_entries != 0 &&
392             trace->entries[trace->nr_entries-1] == ULONG_MAX)
393                 trace->nr_entries--;
394
395         trace->max_entries = trace->nr_entries;
396
397         nr_stack_trace_entries += trace->nr_entries;
398
399         if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
400                 if (!debug_locks_off_graph_unlock())
401                         return 0;
402
403                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
404                 printk("turning off the locking correctness validator.\n");
405                 dump_stack();
406
407                 return 0;
408         }
409
410         return 1;
411 }
412
413 unsigned int nr_hardirq_chains;
414 unsigned int nr_softirq_chains;
415 unsigned int nr_process_chains;
416 unsigned int max_lockdep_depth;
417
418 #ifdef CONFIG_DEBUG_LOCKDEP
419 /*
420  * We cannot printk in early bootup code. Not even early_printk()
421  * might work. So we mark any initialization errors and printk
422  * about it later on, in lockdep_info().
423  */
424 static int lockdep_init_error;
425 static unsigned long lockdep_init_trace_data[20];
426 static struct stack_trace lockdep_init_trace = {
427         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
428         .entries = lockdep_init_trace_data,
429 };
430
431 /*
432  * Various lockdep statistics:
433  */
434 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
435 #endif
436
437 /*
438  * Locking printouts:
439  */
440
441 #define __USAGE(__STATE)                                                \
442         [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
443         [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
444         [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
445         [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
446
447 static const char *usage_str[] =
448 {
449 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
450 #include "lockdep_states.h"
451 #undef LOCKDEP_STATE
452         [LOCK_USED] = "INITIAL USE",
453 };
454
455 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
456 {
457         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
458 }
459
460 static inline unsigned long lock_flag(enum lock_usage_bit bit)
461 {
462         return 1UL << bit;
463 }
464
465 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
466 {
467         char c = '.';
468
469         if (class->usage_mask & lock_flag(bit + 2))
470                 c = '+';
471         if (class->usage_mask & lock_flag(bit)) {
472                 c = '-';
473                 if (class->usage_mask & lock_flag(bit + 2))
474                         c = '?';
475         }
476
477         return c;
478 }
479
480 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
481 {
482         int i = 0;
483
484 #define LOCKDEP_STATE(__STATE)                                          \
485         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
486         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
487 #include "lockdep_states.h"
488 #undef LOCKDEP_STATE
489
490         usage[i] = '\0';
491 }
492
493 static void print_lock_name(struct lock_class *class)
494 {
495         char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
496         const char *name;
497
498         get_usage_chars(class, usage);
499
500         name = class->name;
501         if (!name) {
502                 name = __get_key_name(class->key, str);
503                 printk(" (%s", name);
504         } else {
505                 printk(" (%s", name);
506                 if (class->name_version > 1)
507                         printk("#%d", class->name_version);
508                 if (class->subclass)
509                         printk("/%d", class->subclass);
510         }
511         printk("){%s}", usage);
512 }
513
514 static void print_lockdep_cache(struct lockdep_map *lock)
515 {
516         const char *name;
517         char str[KSYM_NAME_LEN];
518
519         name = lock->name;
520         if (!name)
521                 name = __get_key_name(lock->key->subkeys, str);
522
523         printk("%s", name);
524 }
525
526 static void print_lock(struct held_lock *hlock)
527 {
528         print_lock_name(hlock_class(hlock));
529         printk(", at: ");
530         print_ip_sym(hlock->acquire_ip);
531 }
532
533 static void lockdep_print_held_locks(struct task_struct *curr)
534 {
535         int i, depth = curr->lockdep_depth;
536
537         if (!depth) {
538                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
539                 return;
540         }
541         printk("%d lock%s held by %s/%d:\n",
542                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
543
544         for (i = 0; i < depth; i++) {
545                 printk(" #%d: ", i);
546                 print_lock(curr->held_locks + i);
547         }
548 }
549
550 static void print_kernel_version(void)
551 {
552         printk("%s %.*s\n", init_utsname()->release,
553                 (int)strcspn(init_utsname()->version, " "),
554                 init_utsname()->version);
555 }
556
557 static int very_verbose(struct lock_class *class)
558 {
559 #if VERY_VERBOSE
560         return class_filter(class);
561 #endif
562         return 0;
563 }
564
565 /*
566  * Is this the address of a static object:
567  */
568 static int static_obj(void *obj)
569 {
570         unsigned long start = (unsigned long) &_stext,
571                       end   = (unsigned long) &_end,
572                       addr  = (unsigned long) obj;
573
574         /*
575          * static variable?
576          */
577         if ((addr >= start) && (addr < end))
578                 return 1;
579
580         if (arch_is_kernel_data(addr))
581                 return 1;
582
583         /*
584          * in-kernel percpu var?
585          */
586         if (is_kernel_percpu_address(addr))
587                 return 1;
588
589         /*
590          * module static or percpu var?
591          */
592         return is_module_address(addr) || is_module_percpu_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,
809                             int distance, struct stack_trace *trace)
810 {
811         struct lock_list *entry;
812         /*
813          * Lock not present yet - get a new dependency struct and
814          * add it to the list:
815          */
816         entry = alloc_list_entry();
817         if (!entry)
818                 return 0;
819
820         entry->class = this;
821         entry->distance = distance;
822         entry->trace = *trace;
823         /*
824          * Since we never remove from the dependency list, the list can
825          * be walked lockless by other CPUs, it's only allocation
826          * that must be protected by the spinlock. But this also means
827          * we must make new entries visible only once writes to the
828          * entry become visible - hence the RCU op:
829          */
830         list_add_tail_rcu(&entry->entry, head);
831
832         return 1;
833 }
834
835 /*
836  * For good efficiency of modular, we use power of 2
837  */
838 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
839 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
840
841 /*
842  * The circular_queue and helpers is used to implement the
843  * breadth-first search(BFS)algorithem, by which we can build
844  * the shortest path from the next lock to be acquired to the
845  * previous held lock if there is a circular between them.
846  */
847 struct circular_queue {
848         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
849         unsigned int  front, rear;
850 };
851
852 static struct circular_queue lock_cq;
853
854 unsigned int max_bfs_queue_depth;
855
856 static unsigned int lockdep_dependency_gen_id;
857
858 static inline void __cq_init(struct circular_queue *cq)
859 {
860         cq->front = cq->rear = 0;
861         lockdep_dependency_gen_id++;
862 }
863
864 static inline int __cq_empty(struct circular_queue *cq)
865 {
866         return (cq->front == cq->rear);
867 }
868
869 static inline int __cq_full(struct circular_queue *cq)
870 {
871         return ((cq->rear + 1) & CQ_MASK) == cq->front;
872 }
873
874 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
875 {
876         if (__cq_full(cq))
877                 return -1;
878
879         cq->element[cq->rear] = elem;
880         cq->rear = (cq->rear + 1) & CQ_MASK;
881         return 0;
882 }
883
884 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
885 {
886         if (__cq_empty(cq))
887                 return -1;
888
889         *elem = cq->element[cq->front];
890         cq->front = (cq->front + 1) & CQ_MASK;
891         return 0;
892 }
893
894 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
895 {
896         return (cq->rear - cq->front) & CQ_MASK;
897 }
898
899 static inline void mark_lock_accessed(struct lock_list *lock,
900                                         struct lock_list *parent)
901 {
902         unsigned long nr;
903
904         nr = lock - list_entries;
905         WARN_ON(nr >= nr_list_entries);
906         lock->parent = parent;
907         lock->class->dep_gen_id = lockdep_dependency_gen_id;
908 }
909
910 static inline unsigned long lock_accessed(struct lock_list *lock)
911 {
912         unsigned long nr;
913
914         nr = lock - list_entries;
915         WARN_ON(nr >= nr_list_entries);
916         return lock->class->dep_gen_id == lockdep_dependency_gen_id;
917 }
918
919 static inline struct lock_list *get_lock_parent(struct lock_list *child)
920 {
921         return child->parent;
922 }
923
924 static inline int get_lock_depth(struct lock_list *child)
925 {
926         int depth = 0;
927         struct lock_list *parent;
928
929         while ((parent = get_lock_parent(child))) {
930                 child = parent;
931                 depth++;
932         }
933         return depth;
934 }
935
936 static int __bfs(struct lock_list *source_entry,
937                  void *data,
938                  int (*match)(struct lock_list *entry, void *data),
939                  struct lock_list **target_entry,
940                  int forward)
941 {
942         struct lock_list *entry;
943         struct list_head *head;
944         struct circular_queue *cq = &lock_cq;
945         int ret = 1;
946
947         if (match(source_entry, data)) {
948                 *target_entry = source_entry;
949                 ret = 0;
950                 goto exit;
951         }
952
953         if (forward)
954                 head = &source_entry->class->locks_after;
955         else
956                 head = &source_entry->class->locks_before;
957
958         if (list_empty(head))
959                 goto exit;
960
961         __cq_init(cq);
962         __cq_enqueue(cq, (unsigned long)source_entry);
963
964         while (!__cq_empty(cq)) {
965                 struct lock_list *lock;
966
967                 __cq_dequeue(cq, (unsigned long *)&lock);
968
969                 if (!lock->class) {
970                         ret = -2;
971                         goto exit;
972                 }
973
974                 if (forward)
975                         head = &lock->class->locks_after;
976                 else
977                         head = &lock->class->locks_before;
978
979                 list_for_each_entry(entry, head, entry) {
980                         if (!lock_accessed(entry)) {
981                                 unsigned int cq_depth;
982                                 mark_lock_accessed(entry, lock);
983                                 if (match(entry, data)) {
984                                         *target_entry = entry;
985                                         ret = 0;
986                                         goto exit;
987                                 }
988
989                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
990                                         ret = -1;
991                                         goto exit;
992                                 }
993                                 cq_depth = __cq_get_elem_count(cq);
994                                 if (max_bfs_queue_depth < cq_depth)
995                                         max_bfs_queue_depth = cq_depth;
996                         }
997                 }
998         }
999 exit:
1000         return ret;
1001 }
1002
1003 static inline int __bfs_forwards(struct lock_list *src_entry,
1004                         void *data,
1005                         int (*match)(struct lock_list *entry, void *data),
1006                         struct lock_list **target_entry)
1007 {
1008         return __bfs(src_entry, data, match, target_entry, 1);
1009
1010 }
1011
1012 static inline int __bfs_backwards(struct lock_list *src_entry,
1013                         void *data,
1014                         int (*match)(struct lock_list *entry, void *data),
1015                         struct lock_list **target_entry)
1016 {
1017         return __bfs(src_entry, data, match, target_entry, 0);
1018
1019 }
1020
1021 /*
1022  * Recursive, forwards-direction lock-dependency checking, used for
1023  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1024  * checking.
1025  */
1026
1027 /*
1028  * Print a dependency chain entry (this is only done when a deadlock
1029  * has been detected):
1030  */
1031 static noinline int
1032 print_circular_bug_entry(struct lock_list *target, int depth)
1033 {
1034         if (debug_locks_silent)
1035                 return 0;
1036         printk("\n-> #%u", depth);
1037         print_lock_name(target->class);
1038         printk(":\n");
1039         print_stack_trace(&target->trace, 6);
1040
1041         return 0;
1042 }
1043
1044 /*
1045  * When a circular dependency is detected, print the
1046  * header first:
1047  */
1048 static noinline int
1049 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1050                         struct held_lock *check_src,
1051                         struct held_lock *check_tgt)
1052 {
1053         struct task_struct *curr = current;
1054
1055         if (debug_locks_silent)
1056                 return 0;
1057
1058         printk("\n=======================================================\n");
1059         printk(  "[ INFO: possible circular locking dependency detected ]\n");
1060         print_kernel_version();
1061         printk(  "-------------------------------------------------------\n");
1062         printk("%s/%d is trying to acquire lock:\n",
1063                 curr->comm, task_pid_nr(curr));
1064         print_lock(check_src);
1065         printk("\nbut task is already holding lock:\n");
1066         print_lock(check_tgt);
1067         printk("\nwhich lock already depends on the new lock.\n\n");
1068         printk("\nthe existing dependency chain (in reverse order) is:\n");
1069
1070         print_circular_bug_entry(entry, depth);
1071
1072         return 0;
1073 }
1074
1075 static inline int class_equal(struct lock_list *entry, void *data)
1076 {
1077         return entry->class == data;
1078 }
1079
1080 static noinline int print_circular_bug(struct lock_list *this,
1081                                 struct lock_list *target,
1082                                 struct held_lock *check_src,
1083                                 struct held_lock *check_tgt)
1084 {
1085         struct task_struct *curr = current;
1086         struct lock_list *parent;
1087         int depth;
1088
1089         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1090                 return 0;
1091
1092         if (!save_trace(&this->trace))
1093                 return 0;
1094
1095         depth = get_lock_depth(target);
1096
1097         print_circular_bug_header(target, depth, check_src, check_tgt);
1098
1099         parent = get_lock_parent(target);
1100
1101         while (parent) {
1102                 print_circular_bug_entry(parent, --depth);
1103                 parent = get_lock_parent(parent);
1104         }
1105
1106         printk("\nother info that might help us debug this:\n\n");
1107         lockdep_print_held_locks(curr);
1108
1109         printk("\nstack backtrace:\n");
1110         dump_stack();
1111
1112         return 0;
1113 }
1114
1115 static noinline int print_bfs_bug(int ret)
1116 {
1117         if (!debug_locks_off_graph_unlock())
1118                 return 0;
1119
1120         WARN(1, "lockdep bfs error:%d\n", ret);
1121
1122         return 0;
1123 }
1124
1125 static int noop_count(struct lock_list *entry, void *data)
1126 {
1127         (*(unsigned long *)data)++;
1128         return 0;
1129 }
1130
1131 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1132 {
1133         unsigned long  count = 0;
1134         struct lock_list *uninitialized_var(target_entry);
1135
1136         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1137
1138         return count;
1139 }
1140 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1141 {
1142         unsigned long ret, flags;
1143         struct lock_list this;
1144
1145         this.parent = NULL;
1146         this.class = class;
1147
1148         local_irq_save(flags);
1149         arch_spin_lock(&lockdep_lock);
1150         ret = __lockdep_count_forward_deps(&this);
1151         arch_spin_unlock(&lockdep_lock);
1152         local_irq_restore(flags);
1153
1154         return ret;
1155 }
1156
1157 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1158 {
1159         unsigned long  count = 0;
1160         struct lock_list *uninitialized_var(target_entry);
1161
1162         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1163
1164         return count;
1165 }
1166
1167 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1168 {
1169         unsigned long ret, flags;
1170         struct lock_list this;
1171
1172         this.parent = NULL;
1173         this.class = class;
1174
1175         local_irq_save(flags);
1176         arch_spin_lock(&lockdep_lock);
1177         ret = __lockdep_count_backward_deps(&this);
1178         arch_spin_unlock(&lockdep_lock);
1179         local_irq_restore(flags);
1180
1181         return ret;
1182 }
1183
1184 /*
1185  * Prove that the dependency graph starting at <entry> can not
1186  * lead to <target>. Print an error and return 0 if it does.
1187  */
1188 static noinline int
1189 check_noncircular(struct lock_list *root, struct lock_class *target,
1190                 struct lock_list **target_entry)
1191 {
1192         int result;
1193
1194         debug_atomic_inc(nr_cyclic_checks);
1195
1196         result = __bfs_forwards(root, target, class_equal, target_entry);
1197
1198         return result;
1199 }
1200
1201 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1202 /*
1203  * Forwards and backwards subgraph searching, for the purposes of
1204  * proving that two subgraphs can be connected by a new dependency
1205  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1206  */
1207
1208 static inline int usage_match(struct lock_list *entry, void *bit)
1209 {
1210         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1211 }
1212
1213
1214
1215 /*
1216  * Find a node in the forwards-direction dependency sub-graph starting
1217  * at @root->class that matches @bit.
1218  *
1219  * Return 0 if such a node exists in the subgraph, and put that node
1220  * into *@target_entry.
1221  *
1222  * Return 1 otherwise and keep *@target_entry unchanged.
1223  * Return <0 on error.
1224  */
1225 static int
1226 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1227                         struct lock_list **target_entry)
1228 {
1229         int result;
1230
1231         debug_atomic_inc(nr_find_usage_forwards_checks);
1232
1233         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1234
1235         return result;
1236 }
1237
1238 /*
1239  * Find a node in the backwards-direction dependency sub-graph starting
1240  * at @root->class that matches @bit.
1241  *
1242  * Return 0 if such a node exists in the subgraph, and put that node
1243  * into *@target_entry.
1244  *
1245  * Return 1 otherwise and keep *@target_entry unchanged.
1246  * Return <0 on error.
1247  */
1248 static int
1249 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1250                         struct lock_list **target_entry)
1251 {
1252         int result;
1253
1254         debug_atomic_inc(nr_find_usage_backwards_checks);
1255
1256         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1257
1258         return result;
1259 }
1260
1261 static void print_lock_class_header(struct lock_class *class, int depth)
1262 {
1263         int bit;
1264
1265         printk("%*s->", depth, "");
1266         print_lock_name(class);
1267         printk(" ops: %lu", class->ops);
1268         printk(" {\n");
1269
1270         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1271                 if (class->usage_mask & (1 << bit)) {
1272                         int len = depth;
1273
1274                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1275                         len += printk(" at:\n");
1276                         print_stack_trace(class->usage_traces + bit, len);
1277                 }
1278         }
1279         printk("%*s }\n", depth, "");
1280
1281         printk("%*s ... key      at: ",depth,"");
1282         print_ip_sym((unsigned long)class->key);
1283 }
1284
1285 /*
1286  * printk the shortest lock dependencies from @start to @end in reverse order:
1287  */
1288 static void __used
1289 print_shortest_lock_dependencies(struct lock_list *leaf,
1290                                 struct lock_list *root)
1291 {
1292         struct lock_list *entry = leaf;
1293         int depth;
1294
1295         /*compute depth from generated tree by BFS*/
1296         depth = get_lock_depth(leaf);
1297
1298         do {
1299                 print_lock_class_header(entry->class, depth);
1300                 printk("%*s ... acquired at:\n", depth, "");
1301                 print_stack_trace(&entry->trace, 2);
1302                 printk("\n");
1303
1304                 if (depth == 0 && (entry != root)) {
1305                         printk("lockdep:%s bad BFS generated tree\n", __func__);
1306                         break;
1307                 }
1308
1309                 entry = get_lock_parent(entry);
1310                 depth--;
1311         } while (entry && (depth >= 0));
1312
1313         return;
1314 }
1315
1316 static int
1317 print_bad_irq_dependency(struct task_struct *curr,
1318                          struct lock_list *prev_root,
1319                          struct lock_list *next_root,
1320                          struct lock_list *backwards_entry,
1321                          struct lock_list *forwards_entry,
1322                          struct held_lock *prev,
1323                          struct held_lock *next,
1324                          enum lock_usage_bit bit1,
1325                          enum lock_usage_bit bit2,
1326                          const char *irqclass)
1327 {
1328         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1329                 return 0;
1330
1331         printk("\n======================================================\n");
1332         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1333                 irqclass, irqclass);
1334         print_kernel_version();
1335         printk(  "------------------------------------------------------\n");
1336         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1337                 curr->comm, task_pid_nr(curr),
1338                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1339                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1340                 curr->hardirqs_enabled,
1341                 curr->softirqs_enabled);
1342         print_lock(next);
1343
1344         printk("\nand this task is already holding:\n");
1345         print_lock(prev);
1346         printk("which would create a new lock dependency:\n");
1347         print_lock_name(hlock_class(prev));
1348         printk(" ->");
1349         print_lock_name(hlock_class(next));
1350         printk("\n");
1351
1352         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1353                 irqclass);
1354         print_lock_name(backwards_entry->class);
1355         printk("\n... which became %s-irq-safe at:\n", irqclass);
1356
1357         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1358
1359         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1360         print_lock_name(forwards_entry->class);
1361         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1362         printk("...");
1363
1364         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1365
1366         printk("\nother info that might help us debug this:\n\n");
1367         lockdep_print_held_locks(curr);
1368
1369         printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1370         printk(" and the holding lock:\n");
1371         if (!save_trace(&prev_root->trace))
1372                 return 0;
1373         print_shortest_lock_dependencies(backwards_entry, prev_root);
1374
1375         printk("\nthe dependencies between the lock to be acquired");
1376         printk(" and %s-irq-unsafe lock:\n", irqclass);
1377         if (!save_trace(&next_root->trace))
1378                 return 0;
1379         print_shortest_lock_dependencies(forwards_entry, next_root);
1380
1381         printk("\nstack backtrace:\n");
1382         dump_stack();
1383
1384         return 0;
1385 }
1386
1387 static int
1388 check_usage(struct task_struct *curr, struct held_lock *prev,
1389             struct held_lock *next, enum lock_usage_bit bit_backwards,
1390             enum lock_usage_bit bit_forwards, const char *irqclass)
1391 {
1392         int ret;
1393         struct lock_list this, that;
1394         struct lock_list *uninitialized_var(target_entry);
1395         struct lock_list *uninitialized_var(target_entry1);
1396
1397         this.parent = NULL;
1398
1399         this.class = hlock_class(prev);
1400         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1401         if (ret < 0)
1402                 return print_bfs_bug(ret);
1403         if (ret == 1)
1404                 return ret;
1405
1406         that.parent = NULL;
1407         that.class = hlock_class(next);
1408         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1409         if (ret < 0)
1410                 return print_bfs_bug(ret);
1411         if (ret == 1)
1412                 return ret;
1413
1414         return print_bad_irq_dependency(curr, &this, &that,
1415                         target_entry, target_entry1,
1416                         prev, next,
1417                         bit_backwards, bit_forwards, irqclass);
1418 }
1419
1420 static const char *state_names[] = {
1421 #define LOCKDEP_STATE(__STATE) \
1422         __stringify(__STATE),
1423 #include "lockdep_states.h"
1424 #undef LOCKDEP_STATE
1425 };
1426
1427 static const char *state_rnames[] = {
1428 #define LOCKDEP_STATE(__STATE) \
1429         __stringify(__STATE)"-READ",
1430 #include "lockdep_states.h"
1431 #undef LOCKDEP_STATE
1432 };
1433
1434 static inline const char *state_name(enum lock_usage_bit bit)
1435 {
1436         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1437 }
1438
1439 static int exclusive_bit(int new_bit)
1440 {
1441         /*
1442          * USED_IN
1443          * USED_IN_READ
1444          * ENABLED
1445          * ENABLED_READ
1446          *
1447          * bit 0 - write/read
1448          * bit 1 - used_in/enabled
1449          * bit 2+  state
1450          */
1451
1452         int state = new_bit & ~3;
1453         int dir = new_bit & 2;
1454
1455         /*
1456          * keep state, bit flip the direction and strip read.
1457          */
1458         return state | (dir ^ 2);
1459 }
1460
1461 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1462                            struct held_lock *next, enum lock_usage_bit bit)
1463 {
1464         /*
1465          * Prove that the new dependency does not connect a hardirq-safe
1466          * lock with a hardirq-unsafe lock - to achieve this we search
1467          * the backwards-subgraph starting at <prev>, and the
1468          * forwards-subgraph starting at <next>:
1469          */
1470         if (!check_usage(curr, prev, next, bit,
1471                            exclusive_bit(bit), state_name(bit)))
1472                 return 0;
1473
1474         bit++; /* _READ */
1475
1476         /*
1477          * Prove that the new dependency does not connect a hardirq-safe-read
1478          * lock with a hardirq-unsafe lock - to achieve this we search
1479          * the backwards-subgraph starting at <prev>, and the
1480          * forwards-subgraph starting at <next>:
1481          */
1482         if (!check_usage(curr, prev, next, bit,
1483                            exclusive_bit(bit), state_name(bit)))
1484                 return 0;
1485
1486         return 1;
1487 }
1488
1489 static int
1490 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1491                 struct held_lock *next)
1492 {
1493 #define LOCKDEP_STATE(__STATE)                                          \
1494         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1495                 return 0;
1496 #include "lockdep_states.h"
1497 #undef LOCKDEP_STATE
1498
1499         return 1;
1500 }
1501
1502 static void inc_chains(void)
1503 {
1504         if (current->hardirq_context)
1505                 nr_hardirq_chains++;
1506         else {
1507                 if (current->softirq_context)
1508                         nr_softirq_chains++;
1509                 else
1510                         nr_process_chains++;
1511         }
1512 }
1513
1514 #else
1515
1516 static inline int
1517 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1518                 struct held_lock *next)
1519 {
1520         return 1;
1521 }
1522
1523 static inline void inc_chains(void)
1524 {
1525         nr_process_chains++;
1526 }
1527
1528 #endif
1529
1530 static int
1531 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1532                    struct held_lock *next)
1533 {
1534         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1535                 return 0;
1536
1537         printk("\n=============================================\n");
1538         printk(  "[ INFO: possible recursive locking detected ]\n");
1539         print_kernel_version();
1540         printk(  "---------------------------------------------\n");
1541         printk("%s/%d is trying to acquire lock:\n",
1542                 curr->comm, task_pid_nr(curr));
1543         print_lock(next);
1544         printk("\nbut task is already holding lock:\n");
1545         print_lock(prev);
1546
1547         printk("\nother info that might help us debug this:\n");
1548         lockdep_print_held_locks(curr);
1549
1550         printk("\nstack backtrace:\n");
1551         dump_stack();
1552
1553         return 0;
1554 }
1555
1556 /*
1557  * Check whether we are holding such a class already.
1558  *
1559  * (Note that this has to be done separately, because the graph cannot
1560  * detect such classes of deadlocks.)
1561  *
1562  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1563  */
1564 static int
1565 check_deadlock(struct task_struct *curr, struct held_lock *next,
1566                struct lockdep_map *next_instance, int read)
1567 {
1568         struct held_lock *prev;
1569         struct held_lock *nest = NULL;
1570         int i;
1571
1572         for (i = 0; i < curr->lockdep_depth; i++) {
1573                 prev = curr->held_locks + i;
1574
1575                 if (prev->instance == next->nest_lock)
1576                         nest = prev;
1577
1578                 if (hlock_class(prev) != hlock_class(next))
1579                         continue;
1580
1581                 /*
1582                  * Allow read-after-read recursion of the same
1583                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1584                  */
1585                 if ((read == 2) && prev->read)
1586                         return 2;
1587
1588                 /*
1589                  * We're holding the nest_lock, which serializes this lock's
1590                  * nesting behaviour.
1591                  */
1592                 if (nest)
1593                         return 2;
1594
1595                 return print_deadlock_bug(curr, prev, next);
1596         }
1597         return 1;
1598 }
1599
1600 /*
1601  * There was a chain-cache miss, and we are about to add a new dependency
1602  * to a previous lock. We recursively validate the following rules:
1603  *
1604  *  - would the adding of the <prev> -> <next> dependency create a
1605  *    circular dependency in the graph? [== circular deadlock]
1606  *
1607  *  - does the new prev->next dependency connect any hardirq-safe lock
1608  *    (in the full backwards-subgraph starting at <prev>) with any
1609  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1610  *    <next>)? [== illegal lock inversion with hardirq contexts]
1611  *
1612  *  - does the new prev->next dependency connect any softirq-safe lock
1613  *    (in the full backwards-subgraph starting at <prev>) with any
1614  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1615  *    <next>)? [== illegal lock inversion with softirq contexts]
1616  *
1617  * any of these scenarios could lead to a deadlock.
1618  *
1619  * Then if all the validations pass, we add the forwards and backwards
1620  * dependency.
1621  */
1622 static int
1623 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1624                struct held_lock *next, int distance, int trylock_loop)
1625 {
1626         struct lock_list *entry;
1627         int ret;
1628         struct lock_list this;
1629         struct lock_list *uninitialized_var(target_entry);
1630         /*
1631          * Static variable, serialized by the graph_lock().
1632          *
1633          * We use this static variable to save the stack trace in case
1634          * we call into this function multiple times due to encountering
1635          * trylocks in the held lock stack.
1636          */
1637         static struct stack_trace trace;
1638
1639         /*
1640          * Prove that the new <prev> -> <next> dependency would not
1641          * create a circular dependency in the graph. (We do this by
1642          * forward-recursing into the graph starting at <next>, and
1643          * checking whether we can reach <prev>.)
1644          *
1645          * We are using global variables to control the recursion, to
1646          * keep the stackframe size of the recursive functions low:
1647          */
1648         this.class = hlock_class(next);
1649         this.parent = NULL;
1650         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1651         if (unlikely(!ret))
1652                 return print_circular_bug(&this, target_entry, next, prev);
1653         else if (unlikely(ret < 0))
1654                 return print_bfs_bug(ret);
1655
1656         if (!check_prev_add_irq(curr, prev, next))
1657                 return 0;
1658
1659         /*
1660          * For recursive read-locks we do all the dependency checks,
1661          * but we dont store read-triggered dependencies (only
1662          * write-triggered dependencies). This ensures that only the
1663          * write-side dependencies matter, and that if for example a
1664          * write-lock never takes any other locks, then the reads are
1665          * equivalent to a NOP.
1666          */
1667         if (next->read == 2 || prev->read == 2)
1668                 return 1;
1669         /*
1670          * Is the <prev> -> <next> dependency already present?
1671          *
1672          * (this may occur even though this is a new chain: consider
1673          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1674          *  chains - the second one will be new, but L1 already has
1675          *  L2 added to its dependency list, due to the first chain.)
1676          */
1677         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1678                 if (entry->class == hlock_class(next)) {
1679                         if (distance == 1)
1680                                 entry->distance = 1;
1681                         return 2;
1682                 }
1683         }
1684
1685         if (!trylock_loop && !save_trace(&trace))
1686                 return 0;
1687
1688         /*
1689          * Ok, all validations passed, add the new lock
1690          * to the previous lock's dependency list:
1691          */
1692         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1693                                &hlock_class(prev)->locks_after,
1694                                next->acquire_ip, distance, &trace);
1695
1696         if (!ret)
1697                 return 0;
1698
1699         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1700                                &hlock_class(next)->locks_before,
1701                                next->acquire_ip, distance, &trace);
1702         if (!ret)
1703                 return 0;
1704
1705         /*
1706          * Debugging printouts:
1707          */
1708         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1709                 graph_unlock();
1710                 printk("\n new dependency: ");
1711                 print_lock_name(hlock_class(prev));
1712                 printk(" => ");
1713                 print_lock_name(hlock_class(next));
1714                 printk("\n");
1715                 dump_stack();
1716                 return graph_lock();
1717         }
1718         return 1;
1719 }
1720
1721 /*
1722  * Add the dependency to all directly-previous locks that are 'relevant'.
1723  * The ones that are relevant are (in increasing distance from curr):
1724  * all consecutive trylock entries and the final non-trylock entry - or
1725  * the end of this context's lock-chain - whichever comes first.
1726  */
1727 static int
1728 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1729 {
1730         int depth = curr->lockdep_depth;
1731         int trylock_loop = 0;
1732         struct held_lock *hlock;
1733
1734         /*
1735          * Debugging checks.
1736          *
1737          * Depth must not be zero for a non-head lock:
1738          */
1739         if (!depth)
1740                 goto out_bug;
1741         /*
1742          * At least two relevant locks must exist for this
1743          * to be a head:
1744          */
1745         if (curr->held_locks[depth].irq_context !=
1746                         curr->held_locks[depth-1].irq_context)
1747                 goto out_bug;
1748
1749         for (;;) {
1750                 int distance = curr->lockdep_depth - depth + 1;
1751                 hlock = curr->held_locks + depth-1;
1752                 /*
1753                  * Only non-recursive-read entries get new dependencies
1754                  * added:
1755                  */
1756                 if (hlock->read != 2) {
1757                         if (!check_prev_add(curr, hlock, next,
1758                                                 distance, trylock_loop))
1759                                 return 0;
1760                         /*
1761                          * Stop after the first non-trylock entry,
1762                          * as non-trylock entries have added their
1763                          * own direct dependencies already, so this
1764                          * lock is connected to them indirectly:
1765                          */
1766                         if (!hlock->trylock)
1767                                 break;
1768                 }
1769                 depth--;
1770                 /*
1771                  * End of lock-stack?
1772                  */
1773                 if (!depth)
1774                         break;
1775                 /*
1776                  * Stop the search if we cross into another context:
1777                  */
1778                 if (curr->held_locks[depth].irq_context !=
1779                                 curr->held_locks[depth-1].irq_context)
1780                         break;
1781                 trylock_loop = 1;
1782         }
1783         return 1;
1784 out_bug:
1785         if (!debug_locks_off_graph_unlock())
1786                 return 0;
1787
1788         WARN_ON(1);
1789
1790         return 0;
1791 }
1792
1793 unsigned long nr_lock_chains;
1794 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1795 int nr_chain_hlocks;
1796 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1797
1798 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1799 {
1800         return lock_classes + chain_hlocks[chain->base + i];
1801 }
1802
1803 /*
1804  * Look up a dependency chain. If the key is not present yet then
1805  * add it and return 1 - in this case the new dependency chain is
1806  * validated. If the key is already hashed, return 0.
1807  * (On return with 1 graph_lock is held.)
1808  */
1809 static inline int lookup_chain_cache(struct task_struct *curr,
1810                                      struct held_lock *hlock,
1811                                      u64 chain_key)
1812 {
1813         struct lock_class *class = hlock_class(hlock);
1814         struct list_head *hash_head = chainhashentry(chain_key);
1815         struct lock_chain *chain;
1816         struct held_lock *hlock_curr, *hlock_next;
1817         int i, j, n, cn;
1818
1819         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1820                 return 0;
1821         /*
1822          * We can walk it lock-free, because entries only get added
1823          * to the hash:
1824          */
1825         list_for_each_entry(chain, hash_head, entry) {
1826                 if (chain->chain_key == chain_key) {
1827 cache_hit:
1828                         debug_atomic_inc(chain_lookup_hits);
1829                         if (very_verbose(class))
1830                                 printk("\nhash chain already cached, key: "
1831                                         "%016Lx tail class: [%p] %s\n",
1832                                         (unsigned long long)chain_key,
1833                                         class->key, class->name);
1834                         return 0;
1835                 }
1836         }
1837         if (very_verbose(class))
1838                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1839                         (unsigned long long)chain_key, class->key, class->name);
1840         /*
1841          * Allocate a new chain entry from the static array, and add
1842          * it to the hash:
1843          */
1844         if (!graph_lock())
1845                 return 0;
1846         /*
1847          * We have to walk the chain again locked - to avoid duplicates:
1848          */
1849         list_for_each_entry(chain, hash_head, entry) {
1850                 if (chain->chain_key == chain_key) {
1851                         graph_unlock();
1852                         goto cache_hit;
1853                 }
1854         }
1855         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1856                 if (!debug_locks_off_graph_unlock())
1857                         return 0;
1858
1859                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1860                 printk("turning off the locking correctness validator.\n");
1861                 dump_stack();
1862                 return 0;
1863         }
1864         chain = lock_chains + nr_lock_chains++;
1865         chain->chain_key = chain_key;
1866         chain->irq_context = hlock->irq_context;
1867         /* Find the first held_lock of current chain */
1868         hlock_next = hlock;
1869         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1870                 hlock_curr = curr->held_locks + i;
1871                 if (hlock_curr->irq_context != hlock_next->irq_context)
1872                         break;
1873                 hlock_next = hlock;
1874         }
1875         i++;
1876         chain->depth = curr->lockdep_depth + 1 - i;
1877         cn = nr_chain_hlocks;
1878         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1879                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1880                 if (n == cn)
1881                         break;
1882                 cn = n;
1883         }
1884         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1885                 chain->base = cn;
1886                 for (j = 0; j < chain->depth - 1; j++, i++) {
1887                         int lock_id = curr->held_locks[i].class_idx - 1;
1888                         chain_hlocks[chain->base + j] = lock_id;
1889                 }
1890                 chain_hlocks[chain->base + j] = class - lock_classes;
1891         }
1892         list_add_tail_rcu(&chain->entry, hash_head);
1893         debug_atomic_inc(chain_lookup_misses);
1894         inc_chains();
1895
1896         return 1;
1897 }
1898
1899 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1900                 struct held_lock *hlock, int chain_head, u64 chain_key)
1901 {
1902         /*
1903          * Trylock needs to maintain the stack of held locks, but it
1904          * does not add new dependencies, because trylock can be done
1905          * in any order.
1906          *
1907          * We look up the chain_key and do the O(N^2) check and update of
1908          * the dependencies only if this is a new dependency chain.
1909          * (If lookup_chain_cache() returns with 1 it acquires
1910          * graph_lock for us)
1911          */
1912         if (!hlock->trylock && (hlock->check == 2) &&
1913             lookup_chain_cache(curr, hlock, chain_key)) {
1914                 /*
1915                  * Check whether last held lock:
1916                  *
1917                  * - is irq-safe, if this lock is irq-unsafe
1918                  * - is softirq-safe, if this lock is hardirq-unsafe
1919                  *
1920                  * And check whether the new lock's dependency graph
1921                  * could lead back to the previous lock.
1922                  *
1923                  * any of these scenarios could lead to a deadlock. If
1924                  * All validations
1925                  */
1926                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1927
1928                 if (!ret)
1929                         return 0;
1930                 /*
1931                  * Mark recursive read, as we jump over it when
1932                  * building dependencies (just like we jump over
1933                  * trylock entries):
1934                  */
1935                 if (ret == 2)
1936                         hlock->read = 2;
1937                 /*
1938                  * Add dependency only if this lock is not the head
1939                  * of the chain, and if it's not a secondary read-lock:
1940                  */
1941                 if (!chain_head && ret != 2)
1942                         if (!check_prevs_add(curr, hlock))
1943                                 return 0;
1944                 graph_unlock();
1945         } else
1946                 /* after lookup_chain_cache(): */
1947                 if (unlikely(!debug_locks))
1948                         return 0;
1949
1950         return 1;
1951 }
1952 #else
1953 static inline int validate_chain(struct task_struct *curr,
1954                 struct lockdep_map *lock, struct held_lock *hlock,
1955                 int chain_head, u64 chain_key)
1956 {
1957         return 1;
1958 }
1959 #endif
1960
1961 /*
1962  * We are building curr_chain_key incrementally, so double-check
1963  * it from scratch, to make sure that it's done correctly:
1964  */
1965 static void check_chain_key(struct task_struct *curr)
1966 {
1967 #ifdef CONFIG_DEBUG_LOCKDEP
1968         struct held_lock *hlock, *prev_hlock = NULL;
1969         unsigned int i, id;
1970         u64 chain_key = 0;
1971
1972         for (i = 0; i < curr->lockdep_depth; i++) {
1973                 hlock = curr->held_locks + i;
1974                 if (chain_key != hlock->prev_chain_key) {
1975                         debug_locks_off();
1976                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1977                                 curr->lockdep_depth, i,
1978                                 (unsigned long long)chain_key,
1979                                 (unsigned long long)hlock->prev_chain_key);
1980                         return;
1981                 }
1982                 id = hlock->class_idx - 1;
1983                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1984                         return;
1985
1986                 if (prev_hlock && (prev_hlock->irq_context !=
1987                                                         hlock->irq_context))
1988                         chain_key = 0;
1989                 chain_key = iterate_chain_key(chain_key, id);
1990                 prev_hlock = hlock;
1991         }
1992         if (chain_key != curr->curr_chain_key) {
1993                 debug_locks_off();
1994                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1995                         curr->lockdep_depth, i,
1996                         (unsigned long long)chain_key,
1997                         (unsigned long long)curr->curr_chain_key);
1998         }
1999 #endif
2000 }
2001
2002 static int
2003 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2004                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2005 {
2006         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2007                 return 0;
2008
2009         printk("\n=================================\n");
2010         printk(  "[ INFO: inconsistent lock state ]\n");
2011         print_kernel_version();
2012         printk(  "---------------------------------\n");
2013
2014         printk("inconsistent {%s} -> {%s} usage.\n",
2015                 usage_str[prev_bit], usage_str[new_bit]);
2016
2017         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2018                 curr->comm, task_pid_nr(curr),
2019                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2020                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2021                 trace_hardirqs_enabled(curr),
2022                 trace_softirqs_enabled(curr));
2023         print_lock(this);
2024
2025         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2026         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2027
2028         print_irqtrace_events(curr);
2029         printk("\nother info that might help us debug this:\n");
2030         lockdep_print_held_locks(curr);
2031
2032         printk("\nstack backtrace:\n");
2033         dump_stack();
2034
2035         return 0;
2036 }
2037
2038 /*
2039  * Print out an error if an invalid bit is set:
2040  */
2041 static inline int
2042 valid_state(struct task_struct *curr, struct held_lock *this,
2043             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2044 {
2045         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2046                 return print_usage_bug(curr, this, bad_bit, new_bit);
2047         return 1;
2048 }
2049
2050 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2051                      enum lock_usage_bit new_bit);
2052
2053 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2054
2055 /*
2056  * print irq inversion bug:
2057  */
2058 static int
2059 print_irq_inversion_bug(struct task_struct *curr,
2060                         struct lock_list *root, struct lock_list *other,
2061                         struct held_lock *this, int forwards,
2062                         const char *irqclass)
2063 {
2064         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2065                 return 0;
2066
2067         printk("\n=========================================================\n");
2068         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2069         print_kernel_version();
2070         printk(  "---------------------------------------------------------\n");
2071         printk("%s/%d just changed the state of lock:\n",
2072                 curr->comm, task_pid_nr(curr));
2073         print_lock(this);
2074         if (forwards)
2075                 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2076         else
2077                 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2078         print_lock_name(other->class);
2079         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2080
2081         printk("\nother info that might help us debug this:\n");
2082         lockdep_print_held_locks(curr);
2083
2084         printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2085         if (!save_trace(&root->trace))
2086                 return 0;
2087         print_shortest_lock_dependencies(other, root);
2088
2089         printk("\nstack backtrace:\n");
2090         dump_stack();
2091
2092         return 0;
2093 }
2094
2095 /*
2096  * Prove that in the forwards-direction subgraph starting at <this>
2097  * there is no lock matching <mask>:
2098  */
2099 static int
2100 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2101                      enum lock_usage_bit bit, const char *irqclass)
2102 {
2103         int ret;
2104         struct lock_list root;
2105         struct lock_list *uninitialized_var(target_entry);
2106
2107         root.parent = NULL;
2108         root.class = hlock_class(this);
2109         ret = find_usage_forwards(&root, bit, &target_entry);
2110         if (ret < 0)
2111                 return print_bfs_bug(ret);
2112         if (ret == 1)
2113                 return ret;
2114
2115         return print_irq_inversion_bug(curr, &root, target_entry,
2116                                         this, 1, irqclass);
2117 }
2118
2119 /*
2120  * Prove that in the backwards-direction subgraph starting at <this>
2121  * there is no lock matching <mask>:
2122  */
2123 static int
2124 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2125                       enum lock_usage_bit bit, const char *irqclass)
2126 {
2127         int ret;
2128         struct lock_list root;
2129         struct lock_list *uninitialized_var(target_entry);
2130
2131         root.parent = NULL;
2132         root.class = hlock_class(this);
2133         ret = find_usage_backwards(&root, bit, &target_entry);
2134         if (ret < 0)
2135                 return print_bfs_bug(ret);
2136         if (ret == 1)
2137                 return ret;
2138
2139         return print_irq_inversion_bug(curr, &root, target_entry,
2140                                         this, 0, irqclass);
2141 }
2142
2143 void print_irqtrace_events(struct task_struct *curr)
2144 {
2145         printk("irq event stamp: %u\n", curr->irq_events);
2146         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2147         print_ip_sym(curr->hardirq_enable_ip);
2148         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2149         print_ip_sym(curr->hardirq_disable_ip);
2150         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2151         print_ip_sym(curr->softirq_enable_ip);
2152         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2153         print_ip_sym(curr->softirq_disable_ip);
2154 }
2155
2156 static int HARDIRQ_verbose(struct lock_class *class)
2157 {
2158 #if HARDIRQ_VERBOSE
2159         return class_filter(class);
2160 #endif
2161         return 0;
2162 }
2163
2164 static int SOFTIRQ_verbose(struct lock_class *class)
2165 {
2166 #if SOFTIRQ_VERBOSE
2167         return class_filter(class);
2168 #endif
2169         return 0;
2170 }
2171
2172 static int RECLAIM_FS_verbose(struct lock_class *class)
2173 {
2174 #if RECLAIM_VERBOSE
2175         return class_filter(class);
2176 #endif
2177         return 0;
2178 }
2179
2180 #define STRICT_READ_CHECKS      1
2181
2182 static int (*state_verbose_f[])(struct lock_class *class) = {
2183 #define LOCKDEP_STATE(__STATE) \
2184         __STATE##_verbose,
2185 #include "lockdep_states.h"
2186 #undef LOCKDEP_STATE
2187 };
2188
2189 static inline int state_verbose(enum lock_usage_bit bit,
2190                                 struct lock_class *class)
2191 {
2192         return state_verbose_f[bit >> 2](class);
2193 }
2194
2195 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2196                              enum lock_usage_bit bit, const char *name);
2197
2198 static int
2199 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2200                 enum lock_usage_bit new_bit)
2201 {
2202         int excl_bit = exclusive_bit(new_bit);
2203         int read = new_bit & 1;
2204         int dir = new_bit & 2;
2205
2206         /*
2207          * mark USED_IN has to look forwards -- to ensure no dependency
2208          * has ENABLED state, which would allow recursion deadlocks.
2209          *
2210          * mark ENABLED has to look backwards -- to ensure no dependee
2211          * has USED_IN state, which, again, would allow  recursion deadlocks.
2212          */
2213         check_usage_f usage = dir ?
2214                 check_usage_backwards : check_usage_forwards;
2215
2216         /*
2217          * Validate that this particular lock does not have conflicting
2218          * usage states.
2219          */
2220         if (!valid_state(curr, this, new_bit, excl_bit))
2221                 return 0;
2222
2223         /*
2224          * Validate that the lock dependencies don't have conflicting usage
2225          * states.
2226          */
2227         if ((!read || !dir || STRICT_READ_CHECKS) &&
2228                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2229                 return 0;
2230
2231         /*
2232          * Check for read in write conflicts
2233          */
2234         if (!read) {
2235                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2236                         return 0;
2237
2238                 if (STRICT_READ_CHECKS &&
2239                         !usage(curr, this, excl_bit + 1,
2240                                 state_name(new_bit + 1)))
2241                         return 0;
2242         }
2243
2244         if (state_verbose(new_bit, hlock_class(this)))
2245                 return 2;
2246
2247         return 1;
2248 }
2249
2250 enum mark_type {
2251 #define LOCKDEP_STATE(__STATE)  __STATE,
2252 #include "lockdep_states.h"
2253 #undef LOCKDEP_STATE
2254 };
2255
2256 /*
2257  * Mark all held locks with a usage bit:
2258  */
2259 static int
2260 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2261 {
2262         enum lock_usage_bit usage_bit;
2263         struct held_lock *hlock;
2264         int i;
2265
2266         for (i = 0; i < curr->lockdep_depth; i++) {
2267                 hlock = curr->held_locks + i;
2268
2269                 usage_bit = 2 + (mark << 2); /* ENABLED */
2270                 if (hlock->read)
2271                         usage_bit += 1; /* READ */
2272
2273                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2274
2275                 if (!mark_lock(curr, hlock, usage_bit))
2276                         return 0;
2277         }
2278
2279         return 1;
2280 }
2281
2282 /*
2283  * Debugging helper: via this flag we know that we are in
2284  * 'early bootup code', and will warn about any invalid irqs-on event:
2285  */
2286 static int early_boot_irqs_enabled;
2287
2288 void early_boot_irqs_off(void)
2289 {
2290         early_boot_irqs_enabled = 0;
2291 }
2292
2293 void early_boot_irqs_on(void)
2294 {
2295         early_boot_irqs_enabled = 1;
2296 }
2297
2298 /*
2299  * Hardirqs will be enabled:
2300  */
2301 void trace_hardirqs_on_caller(unsigned long ip)
2302 {
2303         struct task_struct *curr = current;
2304
2305         time_hardirqs_on(CALLER_ADDR0, ip);
2306
2307         if (unlikely(!debug_locks || current->lockdep_recursion))
2308                 return;
2309
2310         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2311                 return;
2312
2313         if (unlikely(curr->hardirqs_enabled)) {
2314                 /*
2315                  * Neither irq nor preemption are disabled here
2316                  * so this is racy by nature but loosing one hit
2317                  * in a stat is not a big deal.
2318                  */
2319                 __debug_atomic_inc(redundant_hardirqs_on);
2320                 return;
2321         }
2322         /* we'll do an OFF -> ON transition: */
2323         curr->hardirqs_enabled = 1;
2324
2325         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2326                 return;
2327         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2328                 return;
2329         /*
2330          * We are going to turn hardirqs on, so set the
2331          * usage bit for all held locks:
2332          */
2333         if (!mark_held_locks(curr, HARDIRQ))
2334                 return;
2335         /*
2336          * If we have softirqs enabled, then set the usage
2337          * bit for all held locks. (disabled hardirqs prevented
2338          * this bit from being set before)
2339          */
2340         if (curr->softirqs_enabled)
2341                 if (!mark_held_locks(curr, SOFTIRQ))
2342                         return;
2343
2344         curr->hardirq_enable_ip = ip;
2345         curr->hardirq_enable_event = ++curr->irq_events;
2346         debug_atomic_inc(hardirqs_on_events);
2347 }
2348 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2349
2350 void trace_hardirqs_on(void)
2351 {
2352         trace_hardirqs_on_caller(CALLER_ADDR0);
2353 }
2354 EXPORT_SYMBOL(trace_hardirqs_on);
2355
2356 /*
2357  * Hardirqs were disabled:
2358  */
2359 void trace_hardirqs_off_caller(unsigned long ip)
2360 {
2361         struct task_struct *curr = current;
2362
2363         time_hardirqs_off(CALLER_ADDR0, ip);
2364
2365         if (unlikely(!debug_locks || current->lockdep_recursion))
2366                 return;
2367
2368         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2369                 return;
2370
2371         if (curr->hardirqs_enabled) {
2372                 /*
2373                  * We have done an ON -> OFF transition:
2374                  */
2375                 curr->hardirqs_enabled = 0;
2376                 curr->hardirq_disable_ip = ip;
2377                 curr->hardirq_disable_event = ++curr->irq_events;
2378                 debug_atomic_inc(hardirqs_off_events);
2379         } else
2380                 debug_atomic_inc(redundant_hardirqs_off);
2381 }
2382 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2383
2384 void trace_hardirqs_off(void)
2385 {
2386         trace_hardirqs_off_caller(CALLER_ADDR0);
2387 }
2388 EXPORT_SYMBOL(trace_hardirqs_off);
2389
2390 /*
2391  * Softirqs will be enabled:
2392  */
2393 void trace_softirqs_on(unsigned long ip)
2394 {
2395         struct task_struct *curr = current;
2396
2397         if (unlikely(!debug_locks))
2398                 return;
2399
2400         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2401                 return;
2402
2403         if (curr->softirqs_enabled) {
2404                 debug_atomic_inc(redundant_softirqs_on);
2405                 return;
2406         }
2407
2408         /*
2409          * We'll do an OFF -> ON transition:
2410          */
2411         curr->softirqs_enabled = 1;
2412         curr->softirq_enable_ip = ip;
2413         curr->softirq_enable_event = ++curr->irq_events;
2414         debug_atomic_inc(softirqs_on_events);
2415         /*
2416          * We are going to turn softirqs on, so set the
2417          * usage bit for all held locks, if hardirqs are
2418          * enabled too:
2419          */
2420         if (curr->hardirqs_enabled)
2421                 mark_held_locks(curr, SOFTIRQ);
2422 }
2423
2424 /*
2425  * Softirqs were disabled:
2426  */
2427 void trace_softirqs_off(unsigned long ip)
2428 {
2429         struct task_struct *curr = current;
2430
2431         if (unlikely(!debug_locks))
2432                 return;
2433
2434         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2435                 return;
2436
2437         if (curr->softirqs_enabled) {
2438                 /*
2439                  * We have done an ON -> OFF transition:
2440                  */
2441                 curr->softirqs_enabled = 0;
2442                 curr->softirq_disable_ip = ip;
2443                 curr->softirq_disable_event = ++curr->irq_events;
2444                 debug_atomic_inc(softirqs_off_events);
2445                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2446         } else
2447                 debug_atomic_inc(redundant_softirqs_off);
2448 }
2449
2450 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2451 {
2452         struct task_struct *curr = current;
2453
2454         if (unlikely(!debug_locks))
2455                 return;
2456
2457         /* no reclaim without waiting on it */
2458         if (!(gfp_mask & __GFP_WAIT))
2459                 return;
2460
2461         /* this guy won't enter reclaim */
2462         if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2463                 return;
2464
2465         /* We're only interested __GFP_FS allocations for now */
2466         if (!(gfp_mask & __GFP_FS))
2467                 return;
2468
2469         if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2470                 return;
2471
2472         mark_held_locks(curr, RECLAIM_FS);
2473 }
2474
2475 static void check_flags(unsigned long flags);
2476
2477 void lockdep_trace_alloc(gfp_t gfp_mask)
2478 {
2479         unsigned long flags;
2480
2481         if (unlikely(current->lockdep_recursion))
2482                 return;
2483
2484         raw_local_irq_save(flags);
2485         check_flags(flags);
2486         current->lockdep_recursion = 1;
2487         __lockdep_trace_alloc(gfp_mask, flags);
2488         current->lockdep_recursion = 0;
2489         raw_local_irq_restore(flags);
2490 }
2491
2492 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2493 {
2494         /*
2495          * If non-trylock use in a hardirq or softirq context, then
2496          * mark the lock as used in these contexts:
2497          */
2498         if (!hlock->trylock) {
2499                 if (hlock->read) {
2500                         if (curr->hardirq_context)
2501                                 if (!mark_lock(curr, hlock,
2502                                                 LOCK_USED_IN_HARDIRQ_READ))
2503                                         return 0;
2504                         if (curr->softirq_context)
2505                                 if (!mark_lock(curr, hlock,
2506                                                 LOCK_USED_IN_SOFTIRQ_READ))
2507                                         return 0;
2508                 } else {
2509                         if (curr->hardirq_context)
2510                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2511                                         return 0;
2512                         if (curr->softirq_context)
2513                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2514                                         return 0;
2515                 }
2516         }
2517         if (!hlock->hardirqs_off) {
2518                 if (hlock->read) {
2519                         if (!mark_lock(curr, hlock,
2520                                         LOCK_ENABLED_HARDIRQ_READ))
2521                                 return 0;
2522                         if (curr->softirqs_enabled)
2523                                 if (!mark_lock(curr, hlock,
2524                                                 LOCK_ENABLED_SOFTIRQ_READ))
2525                                         return 0;
2526                 } else {
2527                         if (!mark_lock(curr, hlock,
2528                                         LOCK_ENABLED_HARDIRQ))
2529                                 return 0;
2530                         if (curr->softirqs_enabled)
2531                                 if (!mark_lock(curr, hlock,
2532                                                 LOCK_ENABLED_SOFTIRQ))
2533                                         return 0;
2534                 }
2535         }
2536
2537         /*
2538          * We reuse the irq context infrastructure more broadly as a general
2539          * context checking code. This tests GFP_FS recursion (a lock taken
2540          * during reclaim for a GFP_FS allocation is held over a GFP_FS
2541          * allocation).
2542          */
2543         if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2544                 if (hlock->read) {
2545                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2546                                         return 0;
2547                 } else {
2548                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2549                                         return 0;
2550                 }
2551         }
2552
2553         return 1;
2554 }
2555
2556 static int separate_irq_context(struct task_struct *curr,
2557                 struct held_lock *hlock)
2558 {
2559         unsigned int depth = curr->lockdep_depth;
2560
2561         /*
2562          * Keep track of points where we cross into an interrupt context:
2563          */
2564         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2565                                 curr->softirq_context;
2566         if (depth) {
2567                 struct held_lock *prev_hlock;
2568
2569                 prev_hlock = curr->held_locks + depth-1;
2570                 /*
2571                  * If we cross into another context, reset the
2572                  * hash key (this also prevents the checking and the
2573                  * adding of the dependency to 'prev'):
2574                  */
2575                 if (prev_hlock->irq_context != hlock->irq_context)
2576                         return 1;
2577         }
2578         return 0;
2579 }
2580
2581 #else
2582
2583 static inline
2584 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2585                 enum lock_usage_bit new_bit)
2586 {
2587         WARN_ON(1);
2588         return 1;
2589 }
2590
2591 static inline int mark_irqflags(struct task_struct *curr,
2592                 struct held_lock *hlock)
2593 {
2594         return 1;
2595 }
2596
2597 static inline int separate_irq_context(struct task_struct *curr,
2598                 struct held_lock *hlock)
2599 {
2600         return 0;
2601 }
2602
2603 void lockdep_trace_alloc(gfp_t gfp_mask)
2604 {
2605 }
2606
2607 #endif
2608
2609 /*
2610  * Mark a lock with a usage bit, and validate the state transition:
2611  */
2612 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2613                              enum lock_usage_bit new_bit)
2614 {
2615         unsigned int new_mask = 1 << new_bit, ret = 1;
2616
2617         /*
2618          * If already set then do not dirty the cacheline,
2619          * nor do any checks:
2620          */
2621         if (likely(hlock_class(this)->usage_mask & new_mask))
2622                 return 1;
2623
2624         if (!graph_lock())
2625                 return 0;
2626         /*
2627          * Make sure we didnt race:
2628          */
2629         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2630                 graph_unlock();
2631                 return 1;
2632         }
2633
2634         hlock_class(this)->usage_mask |= new_mask;
2635
2636         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2637                 return 0;
2638
2639         switch (new_bit) {
2640 #define LOCKDEP_STATE(__STATE)                  \
2641         case LOCK_USED_IN_##__STATE:            \
2642         case LOCK_USED_IN_##__STATE##_READ:     \
2643         case LOCK_ENABLED_##__STATE:            \
2644         case LOCK_ENABLED_##__STATE##_READ:
2645 #include "lockdep_states.h"
2646 #undef LOCKDEP_STATE
2647                 ret = mark_lock_irq(curr, this, new_bit);
2648                 if (!ret)
2649                         return 0;
2650                 break;
2651         case LOCK_USED:
2652                 debug_atomic_dec(nr_unused_locks);
2653                 break;
2654         default:
2655                 if (!debug_locks_off_graph_unlock())
2656                         return 0;
2657                 WARN_ON(1);
2658                 return 0;
2659         }
2660
2661         graph_unlock();
2662
2663         /*
2664          * We must printk outside of the graph_lock:
2665          */
2666         if (ret == 2) {
2667                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2668                 print_lock(this);
2669                 print_irqtrace_events(curr);
2670                 dump_stack();
2671         }
2672
2673         return ret;
2674 }
2675
2676 /*
2677  * Initialize a lock instance's lock-class mapping info:
2678  */
2679 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2680                       struct lock_class_key *key, int subclass)
2681 {
2682         lock->class_cache = NULL;
2683 #ifdef CONFIG_LOCK_STAT
2684         lock->cpu = raw_smp_processor_id();
2685 #endif
2686
2687         if (DEBUG_LOCKS_WARN_ON(!name)) {
2688                 lock->name = "NULL";
2689                 return;
2690         }
2691
2692         lock->name = name;
2693
2694         if (DEBUG_LOCKS_WARN_ON(!key))
2695                 return;
2696         /*
2697          * Sanity check, the lock-class key must be persistent:
2698          */
2699         if (!static_obj(key)) {
2700                 printk("BUG: key %p not in .data!\n", key);
2701                 DEBUG_LOCKS_WARN_ON(1);
2702                 return;
2703         }
2704         lock->key = key;
2705
2706         if (unlikely(!debug_locks))
2707                 return;
2708
2709         if (subclass)
2710                 register_lock_class(lock, subclass, 1);
2711 }
2712 EXPORT_SYMBOL_GPL(lockdep_init_map);
2713
2714 struct lock_class_key __lockdep_no_validate__;
2715
2716 /*
2717  * This gets called for every mutex_lock*()/spin_lock*() operation.
2718  * We maintain the dependency maps and validate the locking attempt:
2719  */
2720 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2721                           int trylock, int read, int check, int hardirqs_off,
2722                           struct lockdep_map *nest_lock, unsigned long ip,
2723                           int references)
2724 {
2725         struct task_struct *curr = current;
2726         struct lock_class *class = NULL;
2727         struct held_lock *hlock;
2728         unsigned int depth, id;
2729         int chain_head = 0;
2730         int class_idx;
2731         u64 chain_key;
2732
2733         if (!prove_locking)
2734                 check = 1;
2735
2736         if (unlikely(!debug_locks))
2737                 return 0;
2738
2739         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2740                 return 0;
2741
2742         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2743                 debug_locks_off();
2744                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2745                 printk("turning off the locking correctness validator.\n");
2746                 dump_stack();
2747                 return 0;
2748         }
2749
2750         if (lock->key == &__lockdep_no_validate__)
2751                 check = 1;
2752
2753         if (!subclass)
2754                 class = lock->class_cache;
2755         /*
2756          * Not cached yet or subclass?
2757          */
2758         if (unlikely(!class)) {
2759                 class = register_lock_class(lock, subclass, 0);
2760                 if (!class)
2761                         return 0;
2762         }
2763         atomic_inc((atomic_t *)&class->ops);
2764         if (very_verbose(class)) {
2765                 printk("\nacquire class [%p] %s", class->key, class->name);
2766                 if (class->name_version > 1)
2767                         printk("#%d", class->name_version);
2768                 printk("\n");
2769                 dump_stack();
2770         }
2771
2772         /*
2773          * Add the lock to the list of currently held locks.
2774          * (we dont increase the depth just yet, up until the
2775          * dependency checks are done)
2776          */
2777         depth = curr->lockdep_depth;
2778         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2779                 return 0;
2780
2781         class_idx = class - lock_classes + 1;
2782
2783         if (depth) {
2784                 hlock = curr->held_locks + depth - 1;
2785                 if (hlock->class_idx == class_idx && nest_lock) {
2786                         if (hlock->references)
2787                                 hlock->references++;
2788                         else
2789                                 hlock->references = 2;
2790
2791                         return 1;
2792                 }
2793         }
2794
2795         hlock = curr->held_locks + depth;
2796         if (DEBUG_LOCKS_WARN_ON(!class))
2797                 return 0;
2798         hlock->class_idx = class_idx;
2799         hlock->acquire_ip = ip;
2800         hlock->instance = lock;
2801         hlock->nest_lock = nest_lock;
2802         hlock->trylock = trylock;
2803         hlock->read = read;
2804         hlock->check = check;
2805         hlock->hardirqs_off = !!hardirqs_off;
2806         hlock->references = references;
2807 #ifdef CONFIG_LOCK_STAT
2808         hlock->waittime_stamp = 0;
2809         hlock->holdtime_stamp = lockstat_clock();
2810 #endif
2811
2812         if (check == 2 && !mark_irqflags(curr, hlock))
2813                 return 0;
2814
2815         /* mark it as used: */
2816         if (!mark_lock(curr, hlock, LOCK_USED))
2817                 return 0;
2818
2819         /*
2820          * Calculate the chain hash: it's the combined hash of all the
2821          * lock keys along the dependency chain. We save the hash value
2822          * at every step so that we can get the current hash easily
2823          * after unlock. The chain hash is then used to cache dependency
2824          * results.
2825          *
2826          * The 'key ID' is what is the most compact key value to drive
2827          * the hash, not class->key.
2828          */
2829         id = class - lock_classes;
2830         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2831                 return 0;
2832
2833         chain_key = curr->curr_chain_key;
2834         if (!depth) {
2835                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2836                         return 0;
2837                 chain_head = 1;
2838         }
2839
2840         hlock->prev_chain_key = chain_key;
2841         if (separate_irq_context(curr, hlock)) {
2842                 chain_key = 0;
2843                 chain_head = 1;
2844         }
2845         chain_key = iterate_chain_key(chain_key, id);
2846
2847         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2848                 return 0;
2849
2850         curr->curr_chain_key = chain_key;
2851         curr->lockdep_depth++;
2852         check_chain_key(curr);
2853 #ifdef CONFIG_DEBUG_LOCKDEP
2854         if (unlikely(!debug_locks))
2855                 return 0;
2856 #endif
2857         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2858                 debug_locks_off();
2859                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2860                 printk("turning off the locking correctness validator.\n");
2861                 dump_stack();
2862                 return 0;
2863         }
2864
2865         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2866                 max_lockdep_depth = curr->lockdep_depth;
2867
2868         return 1;
2869 }
2870
2871 static int
2872 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2873                            unsigned long ip)
2874 {
2875         if (!debug_locks_off())
2876                 return 0;
2877         if (debug_locks_silent)
2878                 return 0;
2879
2880         printk("\n=====================================\n");
2881         printk(  "[ BUG: bad unlock balance detected! ]\n");
2882         printk(  "-------------------------------------\n");
2883         printk("%s/%d is trying to release lock (",
2884                 curr->comm, task_pid_nr(curr));
2885         print_lockdep_cache(lock);
2886         printk(") at:\n");
2887         print_ip_sym(ip);
2888         printk("but there are no more locks to release!\n");
2889         printk("\nother info that might help us debug this:\n");
2890         lockdep_print_held_locks(curr);
2891
2892         printk("\nstack backtrace:\n");
2893         dump_stack();
2894
2895         return 0;
2896 }
2897
2898 /*
2899  * Common debugging checks for both nested and non-nested unlock:
2900  */
2901 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2902                         unsigned long ip)
2903 {
2904         if (unlikely(!debug_locks))
2905                 return 0;
2906         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2907                 return 0;
2908
2909         if (curr->lockdep_depth <= 0)
2910                 return print_unlock_inbalance_bug(curr, lock, ip);
2911
2912         return 1;
2913 }
2914
2915 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
2916 {
2917         if (hlock->instance == lock)
2918                 return 1;
2919
2920         if (hlock->references) {
2921                 struct lock_class *class = lock->class_cache;
2922
2923                 if (!class)
2924                         class = look_up_lock_class(lock, 0);
2925
2926                 if (DEBUG_LOCKS_WARN_ON(!class))
2927                         return 0;
2928
2929                 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
2930                         return 0;
2931
2932                 if (hlock->class_idx == class - lock_classes + 1)
2933                         return 1;
2934         }
2935
2936         return 0;
2937 }
2938
2939 static int
2940 __lock_set_class(struct lockdep_map *lock, const char *name,
2941                  struct lock_class_key *key, unsigned int subclass,
2942                  unsigned long ip)
2943 {
2944         struct task_struct *curr = current;
2945         struct held_lock *hlock, *prev_hlock;
2946         struct lock_class *class;
2947         unsigned int depth;
2948         int i;
2949
2950         depth = curr->lockdep_depth;
2951         if (DEBUG_LOCKS_WARN_ON(!depth))
2952                 return 0;
2953
2954         prev_hlock = NULL;
2955         for (i = depth-1; i >= 0; i--) {
2956                 hlock = curr->held_locks + i;
2957                 /*
2958                  * We must not cross into another context:
2959                  */
2960                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2961                         break;
2962                 if (match_held_lock(hlock, lock))
2963                         goto found_it;
2964                 prev_hlock = hlock;
2965         }
2966         return print_unlock_inbalance_bug(curr, lock, ip);
2967
2968 found_it:
2969         lockdep_init_map(lock, name, key, 0);
2970         class = register_lock_class(lock, subclass, 0);
2971         hlock->class_idx = class - lock_classes + 1;
2972
2973         curr->lockdep_depth = i;
2974         curr->curr_chain_key = hlock->prev_chain_key;
2975
2976         for (; i < depth; i++) {
2977                 hlock = curr->held_locks + i;
2978                 if (!__lock_acquire(hlock->instance,
2979                         hlock_class(hlock)->subclass, hlock->trylock,
2980                                 hlock->read, hlock->check, hlock->hardirqs_off,
2981                                 hlock->nest_lock, hlock->acquire_ip,
2982                                 hlock->references))
2983                         return 0;
2984         }
2985
2986         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2987                 return 0;
2988         return 1;
2989 }
2990
2991 /*
2992  * Remove the lock to the list of currently held locks in a
2993  * potentially non-nested (out of order) manner. This is a
2994  * relatively rare operation, as all the unlock APIs default
2995  * to nested mode (which uses lock_release()):
2996  */
2997 static int
2998 lock_release_non_nested(struct task_struct *curr,
2999                         struct lockdep_map *lock, unsigned long ip)
3000 {
3001         struct held_lock *hlock, *prev_hlock;
3002         unsigned int depth;
3003         int i;
3004
3005         /*
3006          * Check whether the lock exists in the current stack
3007          * of held locks:
3008          */
3009         depth = curr->lockdep_depth;
3010         if (DEBUG_LOCKS_WARN_ON(!depth))
3011                 return 0;
3012
3013         prev_hlock = NULL;
3014         for (i = depth-1; i >= 0; i--) {
3015                 hlock = curr->held_locks + i;
3016                 /*
3017                  * We must not cross into another context:
3018                  */
3019                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3020                         break;
3021                 if (match_held_lock(hlock, lock))
3022                         goto found_it;
3023                 prev_hlock = hlock;
3024         }
3025         return print_unlock_inbalance_bug(curr, lock, ip);
3026
3027 found_it:
3028         if (hlock->instance == lock)
3029                 lock_release_holdtime(hlock);
3030
3031         if (hlock->references) {
3032                 hlock->references--;
3033                 if (hlock->references) {
3034                         /*
3035                          * We had, and after removing one, still have
3036                          * references, the current lock stack is still
3037                          * valid. We're done!
3038                          */
3039                         return 1;
3040                 }
3041         }
3042
3043         /*
3044          * We have the right lock to unlock, 'hlock' points to it.
3045          * Now we remove it from the stack, and add back the other
3046          * entries (if any), recalculating the hash along the way:
3047          */
3048
3049         curr->lockdep_depth = i;
3050         curr->curr_chain_key = hlock->prev_chain_key;
3051
3052         for (i++; i < depth; i++) {
3053                 hlock = curr->held_locks + i;
3054                 if (!__lock_acquire(hlock->instance,
3055                         hlock_class(hlock)->subclass, hlock->trylock,
3056                                 hlock->read, hlock->check, hlock->hardirqs_off,
3057                                 hlock->nest_lock, hlock->acquire_ip,
3058                                 hlock->references))
3059                         return 0;
3060         }
3061
3062         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3063                 return 0;
3064         return 1;
3065 }
3066
3067 /*
3068  * Remove the lock to the list of currently held locks - this gets
3069  * called on mutex_unlock()/spin_unlock*() (or on a failed
3070  * mutex_lock_interruptible()). This is done for unlocks that nest
3071  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3072  */
3073 static int lock_release_nested(struct task_struct *curr,
3074                                struct lockdep_map *lock, unsigned long ip)
3075 {
3076         struct held_lock *hlock;
3077         unsigned int depth;
3078
3079         /*
3080          * Pop off the top of the lock stack:
3081          */
3082         depth = curr->lockdep_depth - 1;
3083         hlock = curr->held_locks + depth;
3084
3085         /*
3086          * Is the unlock non-nested:
3087          */
3088         if (hlock->instance != lock || hlock->references)
3089                 return lock_release_non_nested(curr, lock, ip);
3090         curr->lockdep_depth--;
3091
3092         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3093                 return 0;
3094
3095         curr->curr_chain_key = hlock->prev_chain_key;
3096
3097         lock_release_holdtime(hlock);
3098
3099 #ifdef CONFIG_DEBUG_LOCKDEP
3100         hlock->prev_chain_key = 0;
3101         hlock->class_idx = 0;
3102         hlock->acquire_ip = 0;
3103         hlock->irq_context = 0;
3104 #endif
3105         return 1;
3106 }
3107
3108 /*
3109  * Remove the lock to the list of currently held locks - this gets
3110  * called on mutex_unlock()/spin_unlock*() (or on a failed
3111  * mutex_lock_interruptible()). This is done for unlocks that nest
3112  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3113  */
3114 static void
3115 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3116 {
3117         struct task_struct *curr = current;
3118
3119         if (!check_unlock(curr, lock, ip))
3120                 return;
3121
3122         if (nested) {
3123                 if (!lock_release_nested(curr, lock, ip))
3124                         return;
3125         } else {
3126                 if (!lock_release_non_nested(curr, lock, ip))
3127                         return;
3128         }
3129
3130         check_chain_key(curr);
3131 }
3132
3133 static int __lock_is_held(struct lockdep_map *lock)
3134 {
3135         struct task_struct *curr = current;
3136         int i;
3137
3138         for (i = 0; i < curr->lockdep_depth; i++) {
3139                 struct held_lock *hlock = curr->held_locks + i;
3140
3141                 if (match_held_lock(hlock, lock))
3142                         return 1;
3143         }
3144
3145         return 0;
3146 }
3147
3148 /*
3149  * Check whether we follow the irq-flags state precisely:
3150  */
3151 static void check_flags(unsigned long flags)
3152 {
3153 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3154     defined(CONFIG_TRACE_IRQFLAGS)
3155         if (!debug_locks)
3156                 return;
3157
3158         if (irqs_disabled_flags(flags)) {
3159                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3160                         printk("possible reason: unannotated irqs-off.\n");
3161                 }
3162         } else {
3163                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3164                         printk("possible reason: unannotated irqs-on.\n");
3165                 }
3166         }
3167
3168         /*
3169          * We dont accurately track softirq state in e.g.
3170          * hardirq contexts (such as on 4KSTACKS), so only
3171          * check if not in hardirq contexts:
3172          */
3173         if (!hardirq_count()) {
3174                 if (softirq_count())
3175                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3176                 else
3177                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3178         }
3179
3180         if (!debug_locks)
3181                 print_irqtrace_events(current);
3182 #endif
3183 }
3184
3185 void lock_set_class(struct lockdep_map *lock, const char *name,
3186                     struct lock_class_key *key, unsigned int subclass,
3187                     unsigned long ip)
3188 {
3189         unsigned long flags;
3190
3191         if (unlikely(current->lockdep_recursion))
3192                 return;
3193
3194         raw_local_irq_save(flags);
3195         current->lockdep_recursion = 1;
3196         check_flags(flags);
3197         if (__lock_set_class(lock, name, key, subclass, ip))
3198                 check_chain_key(current);
3199         current->lockdep_recursion = 0;
3200         raw_local_irq_restore(flags);
3201 }
3202 EXPORT_SYMBOL_GPL(lock_set_class);
3203
3204 /*
3205  * We are not always called with irqs disabled - do that here,
3206  * and also avoid lockdep recursion:
3207  */
3208 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3209                           int trylock, int read, int check,
3210                           struct lockdep_map *nest_lock, unsigned long ip)
3211 {
3212         unsigned long flags;
3213
3214         if (unlikely(current->lockdep_recursion))
3215                 return;
3216
3217         raw_local_irq_save(flags);
3218         check_flags(flags);
3219
3220         current->lockdep_recursion = 1;
3221         trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3222         __lock_acquire(lock, subclass, trylock, read, check,
3223                        irqs_disabled_flags(flags), nest_lock, ip, 0);
3224         current->lockdep_recursion = 0;
3225         raw_local_irq_restore(flags);
3226 }
3227 EXPORT_SYMBOL_GPL(lock_acquire);
3228
3229 void lock_release(struct lockdep_map *lock, int nested,
3230                           unsigned long ip)
3231 {
3232         unsigned long flags;
3233
3234         if (unlikely(current->lockdep_recursion))
3235                 return;
3236
3237         raw_local_irq_save(flags);
3238         check_flags(flags);
3239         current->lockdep_recursion = 1;
3240         trace_lock_release(lock, ip);
3241         __lock_release(lock, nested, ip);
3242         current->lockdep_recursion = 0;
3243         raw_local_irq_restore(flags);
3244 }
3245 EXPORT_SYMBOL_GPL(lock_release);
3246
3247 int lock_is_held(struct lockdep_map *lock)
3248 {
3249         unsigned long flags;
3250         int ret = 0;
3251
3252         if (unlikely(current->lockdep_recursion))
3253                 return ret;
3254
3255         raw_local_irq_save(flags);
3256         check_flags(flags);
3257
3258         current->lockdep_recursion = 1;
3259         ret = __lock_is_held(lock);
3260         current->lockdep_recursion = 0;
3261         raw_local_irq_restore(flags);
3262
3263         return ret;
3264 }
3265 EXPORT_SYMBOL_GPL(lock_is_held);
3266
3267 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3268 {
3269         current->lockdep_reclaim_gfp = gfp_mask;
3270 }
3271
3272 void lockdep_clear_current_reclaim_state(void)
3273 {
3274         current->lockdep_reclaim_gfp = 0;
3275 }
3276
3277 #ifdef CONFIG_LOCK_STAT
3278 static int
3279 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3280                            unsigned long ip)
3281 {
3282         if (!debug_locks_off())
3283                 return 0;
3284         if (debug_locks_silent)
3285                 return 0;
3286
3287         printk("\n=================================\n");
3288         printk(  "[ BUG: bad contention detected! ]\n");
3289         printk(  "---------------------------------\n");
3290         printk("%s/%d is trying to contend lock (",
3291                 curr->comm, task_pid_nr(curr));
3292         print_lockdep_cache(lock);
3293         printk(") at:\n");
3294         print_ip_sym(ip);
3295         printk("but there are no locks held!\n");
3296         printk("\nother info that might help us debug this:\n");
3297         lockdep_print_held_locks(curr);
3298
3299         printk("\nstack backtrace:\n");
3300         dump_stack();
3301
3302         return 0;
3303 }
3304
3305 static void
3306 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3307 {
3308         struct task_struct *curr = current;
3309         struct held_lock *hlock, *prev_hlock;
3310         struct lock_class_stats *stats;
3311         unsigned int depth;
3312         int i, contention_point, contending_point;
3313
3314         depth = curr->lockdep_depth;
3315         if (DEBUG_LOCKS_WARN_ON(!depth))
3316                 return;
3317
3318         prev_hlock = NULL;
3319         for (i = depth-1; i >= 0; i--) {
3320                 hlock = curr->held_locks + i;
3321                 /*
3322                  * We must not cross into another context:
3323                  */
3324                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3325                         break;
3326                 if (match_held_lock(hlock, lock))
3327                         goto found_it;
3328                 prev_hlock = hlock;
3329         }
3330         print_lock_contention_bug(curr, lock, ip);
3331         return;
3332
3333 found_it:
3334         if (hlock->instance != lock)
3335                 return;
3336
3337         hlock->waittime_stamp = lockstat_clock();
3338
3339         contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3340         contending_point = lock_point(hlock_class(hlock)->contending_point,
3341                                       lock->ip);
3342
3343         stats = get_lock_stats(hlock_class(hlock));
3344         if (contention_point < LOCKSTAT_POINTS)
3345                 stats->contention_point[contention_point]++;
3346         if (contending_point < LOCKSTAT_POINTS)
3347                 stats->contending_point[contending_point]++;
3348         if (lock->cpu != smp_processor_id())
3349                 stats->bounces[bounce_contended + !!hlock->read]++;
3350         put_lock_stats(stats);
3351 }
3352
3353 static void
3354 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3355 {
3356         struct task_struct *curr = current;
3357         struct held_lock *hlock, *prev_hlock;
3358         struct lock_class_stats *stats;
3359         unsigned int depth;
3360         u64 now, waittime = 0;
3361         int i, cpu;
3362
3363         depth = curr->lockdep_depth;
3364         if (DEBUG_LOCKS_WARN_ON(!depth))
3365                 return;
3366
3367         prev_hlock = NULL;
3368         for (i = depth-1; i >= 0; i--) {
3369                 hlock = curr->held_locks + i;
3370                 /*
3371                  * We must not cross into another context:
3372                  */
3373                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3374                         break;
3375                 if (match_held_lock(hlock, lock))
3376                         goto found_it;
3377                 prev_hlock = hlock;
3378         }
3379         print_lock_contention_bug(curr, lock, _RET_IP_);
3380         return;
3381
3382 found_it:
3383         if (hlock->instance != lock)
3384                 return;
3385
3386         cpu = smp_processor_id();
3387         if (hlock->waittime_stamp) {
3388                 now = lockstat_clock();
3389                 waittime = now - hlock->waittime_stamp;
3390                 hlock->holdtime_stamp = now;
3391         }
3392
3393         trace_lock_acquired(lock, ip);
3394
3395         stats = get_lock_stats(hlock_class(hlock));
3396         if (waittime) {
3397                 if (hlock->read)
3398                         lock_time_inc(&stats->read_waittime, waittime);
3399                 else
3400                         lock_time_inc(&stats->write_waittime, waittime);
3401         }
3402         if (lock->cpu != cpu)
3403                 stats->bounces[bounce_acquired + !!hlock->read]++;
3404         put_lock_stats(stats);
3405
3406         lock->cpu = cpu;
3407         lock->ip = ip;
3408 }
3409
3410 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3411 {
3412         unsigned long flags;
3413
3414         if (unlikely(!lock_stat))
3415                 return;
3416
3417         if (unlikely(current->lockdep_recursion))
3418                 return;
3419
3420         raw_local_irq_save(flags);
3421         check_flags(flags);
3422         current->lockdep_recursion = 1;
3423         trace_lock_contended(lock, ip);
3424         __lock_contended(lock, ip);
3425         current->lockdep_recursion = 0;
3426         raw_local_irq_restore(flags);
3427 }
3428 EXPORT_SYMBOL_GPL(lock_contended);
3429
3430 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3431 {
3432         unsigned long flags;
3433
3434         if (unlikely(!lock_stat))
3435                 return;
3436
3437         if (unlikely(current->lockdep_recursion))
3438                 return;
3439
3440         raw_local_irq_save(flags);
3441         check_flags(flags);
3442         current->lockdep_recursion = 1;
3443         __lock_acquired(lock, ip);
3444         current->lockdep_recursion = 0;
3445         raw_local_irq_restore(flags);
3446 }
3447 EXPORT_SYMBOL_GPL(lock_acquired);
3448 #endif
3449
3450 /*
3451  * Used by the testsuite, sanitize the validator state
3452  * after a simulated failure:
3453  */
3454
3455 void lockdep_reset(void)
3456 {
3457         unsigned long flags;
3458         int i;
3459
3460         raw_local_irq_save(flags);
3461         current->curr_chain_key = 0;
3462         current->lockdep_depth = 0;
3463         current->lockdep_recursion = 0;
3464         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3465         nr_hardirq_chains = 0;
3466         nr_softirq_chains = 0;
3467         nr_process_chains = 0;
3468         debug_locks = 1;
3469         for (i = 0; i < CHAINHASH_SIZE; i++)
3470                 INIT_LIST_HEAD(chainhash_table + i);
3471         raw_local_irq_restore(flags);
3472 }
3473
3474 static void zap_class(struct lock_class *class)
3475 {
3476         int i;
3477
3478         /*
3479          * Remove all dependencies this lock is
3480          * involved in:
3481          */
3482         for (i = 0; i < nr_list_entries; i++) {
3483                 if (list_entries[i].class == class)
3484                         list_del_rcu(&list_entries[i].entry);
3485         }
3486         /*
3487          * Unhash the class and remove it from the all_lock_classes list:
3488          */
3489         list_del_rcu(&class->hash_entry);
3490         list_del_rcu(&class->lock_entry);
3491
3492         class->key = NULL;
3493 }
3494
3495 static inline int within(const void *addr, void *start, unsigned long size)
3496 {
3497         return addr >= start && addr < start + size;
3498 }
3499
3500 void lockdep_free_key_range(void *start, unsigned long size)
3501 {
3502         struct lock_class *class, *next;
3503         struct list_head *head;
3504         unsigned long flags;
3505         int i;
3506         int locked;
3507
3508         raw_local_irq_save(flags);
3509         locked = graph_lock();
3510
3511         /*
3512          * Unhash all classes that were created by this module:
3513          */
3514         for (i = 0; i < CLASSHASH_SIZE; i++) {
3515                 head = classhash_table + i;
3516                 if (list_empty(head))
3517                         continue;
3518                 list_for_each_entry_safe(class, next, head, hash_entry) {
3519                         if (within(class->key, start, size))
3520                                 zap_class(class);
3521                         else if (within(class->name, start, size))
3522                                 zap_class(class);
3523                 }
3524         }
3525
3526         if (locked)
3527                 graph_unlock();
3528         raw_local_irq_restore(flags);
3529 }
3530
3531 void lockdep_reset_lock(struct lockdep_map *lock)
3532 {
3533         struct lock_class *class, *next;
3534         struct list_head *head;
3535         unsigned long flags;
3536         int i, j;
3537         int locked;
3538
3539         raw_local_irq_save(flags);
3540
3541         /*
3542          * Remove all classes this lock might have:
3543          */
3544         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3545                 /*
3546                  * If the class exists we look it up and zap it:
3547                  */
3548                 class = look_up_lock_class(lock, j);
3549                 if (class)
3550                         zap_class(class);
3551         }
3552         /*
3553          * Debug check: in the end all mapped classes should
3554          * be gone.
3555          */
3556         locked = graph_lock();
3557         for (i = 0; i < CLASSHASH_SIZE; i++) {
3558                 head = classhash_table + i;
3559                 if (list_empty(head))
3560                         continue;
3561                 list_for_each_entry_safe(class, next, head, hash_entry) {
3562                         if (unlikely(class == lock->class_cache)) {
3563                                 if (debug_locks_off_graph_unlock())
3564                                         WARN_ON(1);
3565                                 goto out_restore;
3566                         }
3567                 }
3568         }
3569         if (locked)
3570                 graph_unlock();
3571
3572 out_restore:
3573         raw_local_irq_restore(flags);
3574 }
3575
3576 void lockdep_init(void)
3577 {
3578         int i;
3579
3580         /*
3581          * Some architectures have their own start_kernel()
3582          * code which calls lockdep_init(), while we also
3583          * call lockdep_init() from the start_kernel() itself,
3584          * and we want to initialize the hashes only once:
3585          */
3586         if (lockdep_initialized)
3587                 return;
3588
3589         for (i = 0; i < CLASSHASH_SIZE; i++)
3590                 INIT_LIST_HEAD(classhash_table + i);
3591
3592         for (i = 0; i < CHAINHASH_SIZE; i++)
3593                 INIT_LIST_HEAD(chainhash_table + i);
3594
3595         lockdep_initialized = 1;
3596 }
3597
3598 void __init lockdep_info(void)
3599 {
3600         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3601
3602         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3603         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3604         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3605         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3606         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3607         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3608         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3609
3610         printk(" memory used by lock dependency info: %lu kB\n",
3611                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3612                 sizeof(struct list_head) * CLASSHASH_SIZE +
3613                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3614                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3615                 sizeof(struct list_head) * CHAINHASH_SIZE
3616 #ifdef CONFIG_PROVE_LOCKING
3617                 + sizeof(struct circular_queue)
3618 #endif
3619                 ) / 1024
3620                 );
3621
3622         printk(" per task-struct memory footprint: %lu bytes\n",
3623                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3624
3625 #ifdef CONFIG_DEBUG_LOCKDEP
3626         if (lockdep_init_error) {
3627                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3628                 printk("Call stack leading to lockdep invocation was:\n");
3629                 print_stack_trace(&lockdep_init_trace, 0);
3630         }
3631 #endif
3632 }
3633
3634 static void
3635 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3636                      const void *mem_to, struct held_lock *hlock)
3637 {
3638         if (!debug_locks_off())
3639                 return;
3640         if (debug_locks_silent)
3641                 return;
3642
3643         printk("\n=========================\n");
3644         printk(  "[ BUG: held lock freed! ]\n");
3645         printk(  "-------------------------\n");
3646         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3647                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3648         print_lock(hlock);
3649         lockdep_print_held_locks(curr);
3650
3651         printk("\nstack backtrace:\n");
3652         dump_stack();
3653 }
3654
3655 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3656                                 const void* lock_from, unsigned long lock_len)
3657 {
3658         return lock_from + lock_len <= mem_from ||
3659                 mem_from + mem_len <= lock_from;
3660 }
3661
3662 /*
3663  * Called when kernel memory is freed (or unmapped), or if a lock
3664  * is destroyed or reinitialized - this code checks whether there is
3665  * any held lock in the memory range of <from> to <to>:
3666  */
3667 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3668 {
3669         struct task_struct *curr = current;
3670         struct held_lock *hlock;
3671         unsigned long flags;
3672         int i;
3673
3674         if (unlikely(!debug_locks))
3675                 return;
3676
3677         local_irq_save(flags);
3678         for (i = 0; i < curr->lockdep_depth; i++) {
3679                 hlock = curr->held_locks + i;
3680
3681                 if (not_in_range(mem_from, mem_len, hlock->instance,
3682                                         sizeof(*hlock->instance)))
3683                         continue;
3684
3685                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3686                 break;
3687         }
3688         local_irq_restore(flags);
3689 }
3690 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3691
3692 static void print_held_locks_bug(struct task_struct *curr)
3693 {
3694         if (!debug_locks_off())
3695                 return;
3696         if (debug_locks_silent)
3697                 return;
3698
3699         printk("\n=====================================\n");
3700         printk(  "[ BUG: lock held at task exit time! ]\n");
3701         printk(  "-------------------------------------\n");
3702         printk("%s/%d is exiting with locks still held!\n",
3703                 curr->comm, task_pid_nr(curr));
3704         lockdep_print_held_locks(curr);
3705
3706         printk("\nstack backtrace:\n");
3707         dump_stack();
3708 }
3709
3710 void debug_check_no_locks_held(struct task_struct *task)
3711 {
3712         if (unlikely(task->lockdep_depth > 0))
3713                 print_held_locks_bug(task);
3714 }
3715
3716 void debug_show_all_locks(void)
3717 {
3718         struct task_struct *g, *p;
3719         int count = 10;
3720         int unlock = 1;
3721
3722         if (unlikely(!debug_locks)) {
3723                 printk("INFO: lockdep is turned off.\n");
3724                 return;
3725         }
3726         printk("\nShowing all locks held in the system:\n");
3727
3728         /*
3729          * Here we try to get the tasklist_lock as hard as possible,
3730          * if not successful after 2 seconds we ignore it (but keep
3731          * trying). This is to enable a debug printout even if a
3732          * tasklist_lock-holding task deadlocks or crashes.
3733          */
3734 retry:
3735         if (!read_trylock(&tasklist_lock)) {
3736                 if (count == 10)
3737                         printk("hm, tasklist_lock locked, retrying... ");
3738                 if (count) {
3739                         count--;
3740                         printk(" #%d", 10-count);
3741                         mdelay(200);
3742                         goto retry;
3743                 }
3744                 printk(" ignoring it.\n");
3745                 unlock = 0;
3746         } else {
3747                 if (count != 10)
3748                         printk(KERN_CONT " locked it.\n");
3749         }
3750
3751         do_each_thread(g, p) {
3752                 /*
3753                  * It's not reliable to print a task's held locks
3754                  * if it's not sleeping (or if it's not the current
3755                  * task):
3756                  */
3757                 if (p->state == TASK_RUNNING && p != current)
3758                         continue;
3759                 if (p->lockdep_depth)
3760                         lockdep_print_held_locks(p);
3761                 if (!unlock)
3762                         if (read_trylock(&tasklist_lock))
3763                                 unlock = 1;
3764         } while_each_thread(g, p);
3765
3766         printk("\n");
3767         printk("=============================================\n\n");
3768
3769         if (unlock)
3770                 read_unlock(&tasklist_lock);
3771 }
3772 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3773
3774 /*
3775  * Careful: only use this function if you are sure that
3776  * the task cannot run in parallel!
3777  */
3778 void __debug_show_held_locks(struct task_struct *task)
3779 {
3780         if (unlikely(!debug_locks)) {
3781                 printk("INFO: lockdep is turned off.\n");
3782                 return;
3783         }
3784         lockdep_print_held_locks(task);
3785 }
3786 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3787
3788 void debug_show_held_locks(struct task_struct *task)
3789 {
3790                 __debug_show_held_locks(task);
3791 }
3792 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3793
3794 void lockdep_sys_exit(void)
3795 {
3796         struct task_struct *curr = current;
3797
3798         if (unlikely(curr->lockdep_depth)) {
3799                 if (!debug_locks_off())
3800                         return;
3801                 printk("\n================================================\n");
3802                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3803                 printk(  "------------------------------------------------\n");
3804                 printk("%s/%d is leaving the kernel with locks still held!\n",
3805                                 curr->comm, curr->pid);
3806                 lockdep_print_held_locks(curr);
3807         }
3808 }
3809
3810 void lockdep_rcu_dereference(const char *file, const int line)
3811 {
3812         struct task_struct *curr = current;
3813
3814 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
3815         if (!debug_locks_off())
3816                 return;
3817 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
3818         /* Note: the following can be executed concurrently, so be careful. */
3819         printk("\n===================================================\n");
3820         printk(  "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3821         printk(  "---------------------------------------------------\n");
3822         printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3823                         file, line);
3824         printk("\nother info that might help us debug this:\n\n");
3825         printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
3826         lockdep_print_held_locks(curr);
3827         printk("\nstack backtrace:\n");
3828         dump_stack();
3829 }
3830 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);