Merge commit 'v2.6.34-rc6' into core/locking
[linux-3.10.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 cpu_clock(smp_processor_id());
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, int distance)
809 {
810         struct lock_list *entry;
811         /*
812          * Lock not present yet - get a new dependency struct and
813          * add it to the list:
814          */
815         entry = alloc_list_entry();
816         if (!entry)
817                 return 0;
818
819         if (!save_trace(&entry->trace))
820                 return 0;
821
822         entry->class = this;
823         entry->distance = distance;
824         /*
825          * Since we never remove from the dependency list, the list can
826          * be walked lockless by other CPUs, it's only allocation
827          * that must be protected by the spinlock. But this also means
828          * we must make new entries visible only once writes to the
829          * entry become visible - hence the RCU op:
830          */
831         list_add_tail_rcu(&entry->entry, head);
832
833         return 1;
834 }
835
836 /*
837  * For good efficiency of modular, we use power of 2
838  */
839 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
840 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
841
842 /*
843  * The circular_queue and helpers is used to implement the
844  * breadth-first search(BFS)algorithem, by which we can build
845  * the shortest path from the next lock to be acquired to the
846  * previous held lock if there is a circular between them.
847  */
848 struct circular_queue {
849         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
850         unsigned int  front, rear;
851 };
852
853 static struct circular_queue lock_cq;
854
855 unsigned int max_bfs_queue_depth;
856
857 static unsigned int lockdep_dependency_gen_id;
858
859 static inline void __cq_init(struct circular_queue *cq)
860 {
861         cq->front = cq->rear = 0;
862         lockdep_dependency_gen_id++;
863 }
864
865 static inline int __cq_empty(struct circular_queue *cq)
866 {
867         return (cq->front == cq->rear);
868 }
869
870 static inline int __cq_full(struct circular_queue *cq)
871 {
872         return ((cq->rear + 1) & CQ_MASK) == cq->front;
873 }
874
875 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
876 {
877         if (__cq_full(cq))
878                 return -1;
879
880         cq->element[cq->rear] = elem;
881         cq->rear = (cq->rear + 1) & CQ_MASK;
882         return 0;
883 }
884
885 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
886 {
887         if (__cq_empty(cq))
888                 return -1;
889
890         *elem = cq->element[cq->front];
891         cq->front = (cq->front + 1) & CQ_MASK;
892         return 0;
893 }
894
895 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
896 {
897         return (cq->rear - cq->front) & CQ_MASK;
898 }
899
900 static inline void mark_lock_accessed(struct lock_list *lock,
901                                         struct lock_list *parent)
902 {
903         unsigned long nr;
904
905         nr = lock - list_entries;
906         WARN_ON(nr >= nr_list_entries);
907         lock->parent = parent;
908         lock->class->dep_gen_id = lockdep_dependency_gen_id;
909 }
910
911 static inline unsigned long lock_accessed(struct lock_list *lock)
912 {
913         unsigned long nr;
914
915         nr = lock - list_entries;
916         WARN_ON(nr >= nr_list_entries);
917         return lock->class->dep_gen_id == lockdep_dependency_gen_id;
918 }
919
920 static inline struct lock_list *get_lock_parent(struct lock_list *child)
921 {
922         return child->parent;
923 }
924
925 static inline int get_lock_depth(struct lock_list *child)
926 {
927         int depth = 0;
928         struct lock_list *parent;
929
930         while ((parent = get_lock_parent(child))) {
931                 child = parent;
932                 depth++;
933         }
934         return depth;
935 }
936
937 static int __bfs(struct lock_list *source_entry,
938                  void *data,
939                  int (*match)(struct lock_list *entry, void *data),
940                  struct lock_list **target_entry,
941                  int forward)
942 {
943         struct lock_list *entry;
944         struct list_head *head;
945         struct circular_queue *cq = &lock_cq;
946         int ret = 1;
947
948         if (match(source_entry, data)) {
949                 *target_entry = source_entry;
950                 ret = 0;
951                 goto exit;
952         }
953
954         if (forward)
955                 head = &source_entry->class->locks_after;
956         else
957                 head = &source_entry->class->locks_before;
958
959         if (list_empty(head))
960                 goto exit;
961
962         __cq_init(cq);
963         __cq_enqueue(cq, (unsigned long)source_entry);
964
965         while (!__cq_empty(cq)) {
966                 struct lock_list *lock;
967
968                 __cq_dequeue(cq, (unsigned long *)&lock);
969
970                 if (!lock->class) {
971                         ret = -2;
972                         goto exit;
973                 }
974
975                 if (forward)
976                         head = &lock->class->locks_after;
977                 else
978                         head = &lock->class->locks_before;
979
980                 list_for_each_entry(entry, head, entry) {
981                         if (!lock_accessed(entry)) {
982                                 unsigned int cq_depth;
983                                 mark_lock_accessed(entry, lock);
984                                 if (match(entry, data)) {
985                                         *target_entry = entry;
986                                         ret = 0;
987                                         goto exit;
988                                 }
989
990                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
991                                         ret = -1;
992                                         goto exit;
993                                 }
994                                 cq_depth = __cq_get_elem_count(cq);
995                                 if (max_bfs_queue_depth < cq_depth)
996                                         max_bfs_queue_depth = cq_depth;
997                         }
998                 }
999         }
1000 exit:
1001         return ret;
1002 }
1003
1004 static inline int __bfs_forwards(struct lock_list *src_entry,
1005                         void *data,
1006                         int (*match)(struct lock_list *entry, void *data),
1007                         struct lock_list **target_entry)
1008 {
1009         return __bfs(src_entry, data, match, target_entry, 1);
1010
1011 }
1012
1013 static inline int __bfs_backwards(struct lock_list *src_entry,
1014                         void *data,
1015                         int (*match)(struct lock_list *entry, void *data),
1016                         struct lock_list **target_entry)
1017 {
1018         return __bfs(src_entry, data, match, target_entry, 0);
1019
1020 }
1021
1022 /*
1023  * Recursive, forwards-direction lock-dependency checking, used for
1024  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1025  * checking.
1026  */
1027
1028 /*
1029  * Print a dependency chain entry (this is only done when a deadlock
1030  * has been detected):
1031  */
1032 static noinline int
1033 print_circular_bug_entry(struct lock_list *target, int depth)
1034 {
1035         if (debug_locks_silent)
1036                 return 0;
1037         printk("\n-> #%u", depth);
1038         print_lock_name(target->class);
1039         printk(":\n");
1040         print_stack_trace(&target->trace, 6);
1041
1042         return 0;
1043 }
1044
1045 /*
1046  * When a circular dependency is detected, print the
1047  * header first:
1048  */
1049 static noinline int
1050 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1051                         struct held_lock *check_src,
1052                         struct held_lock *check_tgt)
1053 {
1054         struct task_struct *curr = current;
1055
1056         if (debug_locks_silent)
1057                 return 0;
1058
1059         printk("\n=======================================================\n");
1060         printk(  "[ INFO: possible circular locking dependency detected ]\n");
1061         print_kernel_version();
1062         printk(  "-------------------------------------------------------\n");
1063         printk("%s/%d is trying to acquire lock:\n",
1064                 curr->comm, task_pid_nr(curr));
1065         print_lock(check_src);
1066         printk("\nbut task is already holding lock:\n");
1067         print_lock(check_tgt);
1068         printk("\nwhich lock already depends on the new lock.\n\n");
1069         printk("\nthe existing dependency chain (in reverse order) is:\n");
1070
1071         print_circular_bug_entry(entry, depth);
1072
1073         return 0;
1074 }
1075
1076 static inline int class_equal(struct lock_list *entry, void *data)
1077 {
1078         return entry->class == data;
1079 }
1080
1081 static noinline int print_circular_bug(struct lock_list *this,
1082                                 struct lock_list *target,
1083                                 struct held_lock *check_src,
1084                                 struct held_lock *check_tgt)
1085 {
1086         struct task_struct *curr = current;
1087         struct lock_list *parent;
1088         int depth;
1089
1090         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1091                 return 0;
1092
1093         if (!save_trace(&this->trace))
1094                 return 0;
1095
1096         depth = get_lock_depth(target);
1097
1098         print_circular_bug_header(target, depth, check_src, check_tgt);
1099
1100         parent = get_lock_parent(target);
1101
1102         while (parent) {
1103                 print_circular_bug_entry(parent, --depth);
1104                 parent = get_lock_parent(parent);
1105         }
1106
1107         printk("\nother info that might help us debug this:\n\n");
1108         lockdep_print_held_locks(curr);
1109
1110         printk("\nstack backtrace:\n");
1111         dump_stack();
1112
1113         return 0;
1114 }
1115
1116 static noinline int print_bfs_bug(int ret)
1117 {
1118         if (!debug_locks_off_graph_unlock())
1119                 return 0;
1120
1121         WARN(1, "lockdep bfs error:%d\n", ret);
1122
1123         return 0;
1124 }
1125
1126 static int noop_count(struct lock_list *entry, void *data)
1127 {
1128         (*(unsigned long *)data)++;
1129         return 0;
1130 }
1131
1132 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1133 {
1134         unsigned long  count = 0;
1135         struct lock_list *uninitialized_var(target_entry);
1136
1137         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1138
1139         return count;
1140 }
1141 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1142 {
1143         unsigned long ret, flags;
1144         struct lock_list this;
1145
1146         this.parent = NULL;
1147         this.class = class;
1148
1149         local_irq_save(flags);
1150         arch_spin_lock(&lockdep_lock);
1151         ret = __lockdep_count_forward_deps(&this);
1152         arch_spin_unlock(&lockdep_lock);
1153         local_irq_restore(flags);
1154
1155         return ret;
1156 }
1157
1158 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1159 {
1160         unsigned long  count = 0;
1161         struct lock_list *uninitialized_var(target_entry);
1162
1163         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1164
1165         return count;
1166 }
1167
1168 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1169 {
1170         unsigned long ret, flags;
1171         struct lock_list this;
1172
1173         this.parent = NULL;
1174         this.class = class;
1175
1176         local_irq_save(flags);
1177         arch_spin_lock(&lockdep_lock);
1178         ret = __lockdep_count_backward_deps(&this);
1179         arch_spin_unlock(&lockdep_lock);
1180         local_irq_restore(flags);
1181
1182         return ret;
1183 }
1184
1185 /*
1186  * Prove that the dependency graph starting at <entry> can not
1187  * lead to <target>. Print an error and return 0 if it does.
1188  */
1189 static noinline int
1190 check_noncircular(struct lock_list *root, struct lock_class *target,
1191                 struct lock_list **target_entry)
1192 {
1193         int result;
1194
1195         debug_atomic_inc(nr_cyclic_checks);
1196
1197         result = __bfs_forwards(root, target, class_equal, target_entry);
1198
1199         return result;
1200 }
1201
1202 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1203 /*
1204  * Forwards and backwards subgraph searching, for the purposes of
1205  * proving that two subgraphs can be connected by a new dependency
1206  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1207  */
1208
1209 static inline int usage_match(struct lock_list *entry, void *bit)
1210 {
1211         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1212 }
1213
1214
1215
1216 /*
1217  * Find a node in the forwards-direction dependency sub-graph starting
1218  * at @root->class that matches @bit.
1219  *
1220  * Return 0 if such a node exists in the subgraph, and put that node
1221  * into *@target_entry.
1222  *
1223  * Return 1 otherwise and keep *@target_entry unchanged.
1224  * Return <0 on error.
1225  */
1226 static int
1227 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1228                         struct lock_list **target_entry)
1229 {
1230         int result;
1231
1232         debug_atomic_inc(nr_find_usage_forwards_checks);
1233
1234         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1235
1236         return result;
1237 }
1238
1239 /*
1240  * Find a node in the backwards-direction dependency sub-graph starting
1241  * at @root->class that matches @bit.
1242  *
1243  * Return 0 if such a node exists in the subgraph, and put that node
1244  * into *@target_entry.
1245  *
1246  * Return 1 otherwise and keep *@target_entry unchanged.
1247  * Return <0 on error.
1248  */
1249 static int
1250 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1251                         struct lock_list **target_entry)
1252 {
1253         int result;
1254
1255         debug_atomic_inc(nr_find_usage_backwards_checks);
1256
1257         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1258
1259         return result;
1260 }
1261
1262 static void print_lock_class_header(struct lock_class *class, int depth)
1263 {
1264         int bit;
1265
1266         printk("%*s->", depth, "");
1267         print_lock_name(class);
1268         printk(" ops: %lu", class->ops);
1269         printk(" {\n");
1270
1271         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1272                 if (class->usage_mask & (1 << bit)) {
1273                         int len = depth;
1274
1275                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1276                         len += printk(" at:\n");
1277                         print_stack_trace(class->usage_traces + bit, len);
1278                 }
1279         }
1280         printk("%*s }\n", depth, "");
1281
1282         printk("%*s ... key      at: ",depth,"");
1283         print_ip_sym((unsigned long)class->key);
1284 }
1285
1286 /*
1287  * printk the shortest lock dependencies from @start to @end in reverse order:
1288  */
1289 static void __used
1290 print_shortest_lock_dependencies(struct lock_list *leaf,
1291                                 struct lock_list *root)
1292 {
1293         struct lock_list *entry = leaf;
1294         int depth;
1295
1296         /*compute depth from generated tree by BFS*/
1297         depth = get_lock_depth(leaf);
1298
1299         do {
1300                 print_lock_class_header(entry->class, depth);
1301                 printk("%*s ... acquired at:\n", depth, "");
1302                 print_stack_trace(&entry->trace, 2);
1303                 printk("\n");
1304
1305                 if (depth == 0 && (entry != root)) {
1306                         printk("lockdep:%s bad BFS generated tree\n", __func__);
1307                         break;
1308                 }
1309
1310                 entry = get_lock_parent(entry);
1311                 depth--;
1312         } while (entry && (depth >= 0));
1313
1314         return;
1315 }
1316
1317 static int
1318 print_bad_irq_dependency(struct task_struct *curr,
1319                          struct lock_list *prev_root,
1320                          struct lock_list *next_root,
1321                          struct lock_list *backwards_entry,
1322                          struct lock_list *forwards_entry,
1323                          struct held_lock *prev,
1324                          struct held_lock *next,
1325                          enum lock_usage_bit bit1,
1326                          enum lock_usage_bit bit2,
1327                          const char *irqclass)
1328 {
1329         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1330                 return 0;
1331
1332         printk("\n======================================================\n");
1333         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1334                 irqclass, irqclass);
1335         print_kernel_version();
1336         printk(  "------------------------------------------------------\n");
1337         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1338                 curr->comm, task_pid_nr(curr),
1339                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1340                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1341                 curr->hardirqs_enabled,
1342                 curr->softirqs_enabled);
1343         print_lock(next);
1344
1345         printk("\nand this task is already holding:\n");
1346         print_lock(prev);
1347         printk("which would create a new lock dependency:\n");
1348         print_lock_name(hlock_class(prev));
1349         printk(" ->");
1350         print_lock_name(hlock_class(next));
1351         printk("\n");
1352
1353         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1354                 irqclass);
1355         print_lock_name(backwards_entry->class);
1356         printk("\n... which became %s-irq-safe at:\n", irqclass);
1357
1358         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1359
1360         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1361         print_lock_name(forwards_entry->class);
1362         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1363         printk("...");
1364
1365         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1366
1367         printk("\nother info that might help us debug this:\n\n");
1368         lockdep_print_held_locks(curr);
1369
1370         printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1371         printk(" and the holding lock:\n");
1372         if (!save_trace(&prev_root->trace))
1373                 return 0;
1374         print_shortest_lock_dependencies(backwards_entry, prev_root);
1375
1376         printk("\nthe dependencies between the lock to be acquired");
1377         printk(" and %s-irq-unsafe lock:\n", irqclass);
1378         if (!save_trace(&next_root->trace))
1379                 return 0;
1380         print_shortest_lock_dependencies(forwards_entry, next_root);
1381
1382         printk("\nstack backtrace:\n");
1383         dump_stack();
1384
1385         return 0;
1386 }
1387
1388 static int
1389 check_usage(struct task_struct *curr, struct held_lock *prev,
1390             struct held_lock *next, enum lock_usage_bit bit_backwards,
1391             enum lock_usage_bit bit_forwards, const char *irqclass)
1392 {
1393         int ret;
1394         struct lock_list this, that;
1395         struct lock_list *uninitialized_var(target_entry);
1396         struct lock_list *uninitialized_var(target_entry1);
1397
1398         this.parent = NULL;
1399
1400         this.class = hlock_class(prev);
1401         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1402         if (ret < 0)
1403                 return print_bfs_bug(ret);
1404         if (ret == 1)
1405                 return ret;
1406
1407         that.parent = NULL;
1408         that.class = hlock_class(next);
1409         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1410         if (ret < 0)
1411                 return print_bfs_bug(ret);
1412         if (ret == 1)
1413                 return ret;
1414
1415         return print_bad_irq_dependency(curr, &this, &that,
1416                         target_entry, target_entry1,
1417                         prev, next,
1418                         bit_backwards, bit_forwards, irqclass);
1419 }
1420
1421 static const char *state_names[] = {
1422 #define LOCKDEP_STATE(__STATE) \
1423         __stringify(__STATE),
1424 #include "lockdep_states.h"
1425 #undef LOCKDEP_STATE
1426 };
1427
1428 static const char *state_rnames[] = {
1429 #define LOCKDEP_STATE(__STATE) \
1430         __stringify(__STATE)"-READ",
1431 #include "lockdep_states.h"
1432 #undef LOCKDEP_STATE
1433 };
1434
1435 static inline const char *state_name(enum lock_usage_bit bit)
1436 {
1437         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1438 }
1439
1440 static int exclusive_bit(int new_bit)
1441 {
1442         /*
1443          * USED_IN
1444          * USED_IN_READ
1445          * ENABLED
1446          * ENABLED_READ
1447          *
1448          * bit 0 - write/read
1449          * bit 1 - used_in/enabled
1450          * bit 2+  state
1451          */
1452
1453         int state = new_bit & ~3;
1454         int dir = new_bit & 2;
1455
1456         /*
1457          * keep state, bit flip the direction and strip read.
1458          */
1459         return state | (dir ^ 2);
1460 }
1461
1462 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1463                            struct held_lock *next, enum lock_usage_bit bit)
1464 {
1465         /*
1466          * Prove that the new dependency does not connect a hardirq-safe
1467          * lock with a hardirq-unsafe lock - to achieve this we search
1468          * the backwards-subgraph starting at <prev>, and the
1469          * forwards-subgraph starting at <next>:
1470          */
1471         if (!check_usage(curr, prev, next, bit,
1472                            exclusive_bit(bit), state_name(bit)))
1473                 return 0;
1474
1475         bit++; /* _READ */
1476
1477         /*
1478          * Prove that the new dependency does not connect a hardirq-safe-read
1479          * lock with a hardirq-unsafe lock - to achieve this we search
1480          * the backwards-subgraph starting at <prev>, and the
1481          * forwards-subgraph starting at <next>:
1482          */
1483         if (!check_usage(curr, prev, next, bit,
1484                            exclusive_bit(bit), state_name(bit)))
1485                 return 0;
1486
1487         return 1;
1488 }
1489
1490 static int
1491 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1492                 struct held_lock *next)
1493 {
1494 #define LOCKDEP_STATE(__STATE)                                          \
1495         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1496                 return 0;
1497 #include "lockdep_states.h"
1498 #undef LOCKDEP_STATE
1499
1500         return 1;
1501 }
1502
1503 static void inc_chains(void)
1504 {
1505         if (current->hardirq_context)
1506                 nr_hardirq_chains++;
1507         else {
1508                 if (current->softirq_context)
1509                         nr_softirq_chains++;
1510                 else
1511                         nr_process_chains++;
1512         }
1513 }
1514
1515 #else
1516
1517 static inline int
1518 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1519                 struct held_lock *next)
1520 {
1521         return 1;
1522 }
1523
1524 static inline void inc_chains(void)
1525 {
1526         nr_process_chains++;
1527 }
1528
1529 #endif
1530
1531 static int
1532 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1533                    struct held_lock *next)
1534 {
1535         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1536                 return 0;
1537
1538         printk("\n=============================================\n");
1539         printk(  "[ INFO: possible recursive locking detected ]\n");
1540         print_kernel_version();
1541         printk(  "---------------------------------------------\n");
1542         printk("%s/%d is trying to acquire lock:\n",
1543                 curr->comm, task_pid_nr(curr));
1544         print_lock(next);
1545         printk("\nbut task is already holding lock:\n");
1546         print_lock(prev);
1547
1548         printk("\nother info that might help us debug this:\n");
1549         lockdep_print_held_locks(curr);
1550
1551         printk("\nstack backtrace:\n");
1552         dump_stack();
1553
1554         return 0;
1555 }
1556
1557 /*
1558  * Check whether we are holding such a class already.
1559  *
1560  * (Note that this has to be done separately, because the graph cannot
1561  * detect such classes of deadlocks.)
1562  *
1563  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1564  */
1565 static int
1566 check_deadlock(struct task_struct *curr, struct held_lock *next,
1567                struct lockdep_map *next_instance, int read)
1568 {
1569         struct held_lock *prev;
1570         struct held_lock *nest = NULL;
1571         int i;
1572
1573         for (i = 0; i < curr->lockdep_depth; i++) {
1574                 prev = curr->held_locks + i;
1575
1576                 if (prev->instance == next->nest_lock)
1577                         nest = prev;
1578
1579                 if (hlock_class(prev) != hlock_class(next))
1580                         continue;
1581
1582                 /*
1583                  * Allow read-after-read recursion of the same
1584                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1585                  */
1586                 if ((read == 2) && prev->read)
1587                         return 2;
1588
1589                 /*
1590                  * We're holding the nest_lock, which serializes this lock's
1591                  * nesting behaviour.
1592                  */
1593                 if (nest)
1594                         return 2;
1595
1596                 return print_deadlock_bug(curr, prev, next);
1597         }
1598         return 1;
1599 }
1600
1601 /*
1602  * There was a chain-cache miss, and we are about to add a new dependency
1603  * to a previous lock. We recursively validate the following rules:
1604  *
1605  *  - would the adding of the <prev> -> <next> dependency create a
1606  *    circular dependency in the graph? [== circular deadlock]
1607  *
1608  *  - does the new prev->next dependency connect any hardirq-safe lock
1609  *    (in the full backwards-subgraph starting at <prev>) with any
1610  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1611  *    <next>)? [== illegal lock inversion with hardirq contexts]
1612  *
1613  *  - does the new prev->next dependency connect any softirq-safe lock
1614  *    (in the full backwards-subgraph starting at <prev>) with any
1615  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1616  *    <next>)? [== illegal lock inversion with softirq contexts]
1617  *
1618  * any of these scenarios could lead to a deadlock.
1619  *
1620  * Then if all the validations pass, we add the forwards and backwards
1621  * dependency.
1622  */
1623 static int
1624 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1625                struct held_lock *next, int distance)
1626 {
1627         struct lock_list *entry;
1628         int ret;
1629         struct lock_list this;
1630         struct lock_list *uninitialized_var(target_entry);
1631
1632         /*
1633          * Prove that the new <prev> -> <next> dependency would not
1634          * create a circular dependency in the graph. (We do this by
1635          * forward-recursing into the graph starting at <next>, and
1636          * checking whether we can reach <prev>.)
1637          *
1638          * We are using global variables to control the recursion, to
1639          * keep the stackframe size of the recursive functions low:
1640          */
1641         this.class = hlock_class(next);
1642         this.parent = NULL;
1643         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1644         if (unlikely(!ret))
1645                 return print_circular_bug(&this, target_entry, next, prev);
1646         else if (unlikely(ret < 0))
1647                 return print_bfs_bug(ret);
1648
1649         if (!check_prev_add_irq(curr, prev, next))
1650                 return 0;
1651
1652         /*
1653          * For recursive read-locks we do all the dependency checks,
1654          * but we dont store read-triggered dependencies (only
1655          * write-triggered dependencies). This ensures that only the
1656          * write-side dependencies matter, and that if for example a
1657          * write-lock never takes any other locks, then the reads are
1658          * equivalent to a NOP.
1659          */
1660         if (next->read == 2 || prev->read == 2)
1661                 return 1;
1662         /*
1663          * Is the <prev> -> <next> dependency already present?
1664          *
1665          * (this may occur even though this is a new chain: consider
1666          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1667          *  chains - the second one will be new, but L1 already has
1668          *  L2 added to its dependency list, due to the first chain.)
1669          */
1670         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1671                 if (entry->class == hlock_class(next)) {
1672                         if (distance == 1)
1673                                 entry->distance = 1;
1674                         return 2;
1675                 }
1676         }
1677
1678         /*
1679          * Ok, all validations passed, add the new lock
1680          * to the previous lock's dependency list:
1681          */
1682         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1683                                &hlock_class(prev)->locks_after,
1684                                next->acquire_ip, distance);
1685
1686         if (!ret)
1687                 return 0;
1688
1689         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1690                                &hlock_class(next)->locks_before,
1691                                next->acquire_ip, distance);
1692         if (!ret)
1693                 return 0;
1694
1695         /*
1696          * Debugging printouts:
1697          */
1698         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1699                 graph_unlock();
1700                 printk("\n new dependency: ");
1701                 print_lock_name(hlock_class(prev));
1702                 printk(" => ");
1703                 print_lock_name(hlock_class(next));
1704                 printk("\n");
1705                 dump_stack();
1706                 return graph_lock();
1707         }
1708         return 1;
1709 }
1710
1711 /*
1712  * Add the dependency to all directly-previous locks that are 'relevant'.
1713  * The ones that are relevant are (in increasing distance from curr):
1714  * all consecutive trylock entries and the final non-trylock entry - or
1715  * the end of this context's lock-chain - whichever comes first.
1716  */
1717 static int
1718 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1719 {
1720         int depth = curr->lockdep_depth;
1721         struct held_lock *hlock;
1722
1723         /*
1724          * Debugging checks.
1725          *
1726          * Depth must not be zero for a non-head lock:
1727          */
1728         if (!depth)
1729                 goto out_bug;
1730         /*
1731          * At least two relevant locks must exist for this
1732          * to be a head:
1733          */
1734         if (curr->held_locks[depth].irq_context !=
1735                         curr->held_locks[depth-1].irq_context)
1736                 goto out_bug;
1737
1738         for (;;) {
1739                 int distance = curr->lockdep_depth - depth + 1;
1740                 hlock = curr->held_locks + depth-1;
1741                 /*
1742                  * Only non-recursive-read entries get new dependencies
1743                  * added:
1744                  */
1745                 if (hlock->read != 2) {
1746                         if (!check_prev_add(curr, hlock, next, distance))
1747                                 return 0;
1748                         /*
1749                          * Stop after the first non-trylock entry,
1750                          * as non-trylock entries have added their
1751                          * own direct dependencies already, so this
1752                          * lock is connected to them indirectly:
1753                          */
1754                         if (!hlock->trylock)
1755                                 break;
1756                 }
1757                 depth--;
1758                 /*
1759                  * End of lock-stack?
1760                  */
1761                 if (!depth)
1762                         break;
1763                 /*
1764                  * Stop the search if we cross into another context:
1765                  */
1766                 if (curr->held_locks[depth].irq_context !=
1767                                 curr->held_locks[depth-1].irq_context)
1768                         break;
1769         }
1770         return 1;
1771 out_bug:
1772         if (!debug_locks_off_graph_unlock())
1773                 return 0;
1774
1775         WARN_ON(1);
1776
1777         return 0;
1778 }
1779
1780 unsigned long nr_lock_chains;
1781 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1782 int nr_chain_hlocks;
1783 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1784
1785 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1786 {
1787         return lock_classes + chain_hlocks[chain->base + i];
1788 }
1789
1790 /*
1791  * Look up a dependency chain. If the key is not present yet then
1792  * add it and return 1 - in this case the new dependency chain is
1793  * validated. If the key is already hashed, return 0.
1794  * (On return with 1 graph_lock is held.)
1795  */
1796 static inline int lookup_chain_cache(struct task_struct *curr,
1797                                      struct held_lock *hlock,
1798                                      u64 chain_key)
1799 {
1800         struct lock_class *class = hlock_class(hlock);
1801         struct list_head *hash_head = chainhashentry(chain_key);
1802         struct lock_chain *chain;
1803         struct held_lock *hlock_curr, *hlock_next;
1804         int i, j, n, cn;
1805
1806         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1807                 return 0;
1808         /*
1809          * We can walk it lock-free, because entries only get added
1810          * to the hash:
1811          */
1812         list_for_each_entry(chain, hash_head, entry) {
1813                 if (chain->chain_key == chain_key) {
1814 cache_hit:
1815                         debug_atomic_inc(chain_lookup_hits);
1816                         if (very_verbose(class))
1817                                 printk("\nhash chain already cached, key: "
1818                                         "%016Lx tail class: [%p] %s\n",
1819                                         (unsigned long long)chain_key,
1820                                         class->key, class->name);
1821                         return 0;
1822                 }
1823         }
1824         if (very_verbose(class))
1825                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1826                         (unsigned long long)chain_key, class->key, class->name);
1827         /*
1828          * Allocate a new chain entry from the static array, and add
1829          * it to the hash:
1830          */
1831         if (!graph_lock())
1832                 return 0;
1833         /*
1834          * We have to walk the chain again locked - to avoid duplicates:
1835          */
1836         list_for_each_entry(chain, hash_head, entry) {
1837                 if (chain->chain_key == chain_key) {
1838                         graph_unlock();
1839                         goto cache_hit;
1840                 }
1841         }
1842         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1843                 if (!debug_locks_off_graph_unlock())
1844                         return 0;
1845
1846                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1847                 printk("turning off the locking correctness validator.\n");
1848                 dump_stack();
1849                 return 0;
1850         }
1851         chain = lock_chains + nr_lock_chains++;
1852         chain->chain_key = chain_key;
1853         chain->irq_context = hlock->irq_context;
1854         /* Find the first held_lock of current chain */
1855         hlock_next = hlock;
1856         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1857                 hlock_curr = curr->held_locks + i;
1858                 if (hlock_curr->irq_context != hlock_next->irq_context)
1859                         break;
1860                 hlock_next = hlock;
1861         }
1862         i++;
1863         chain->depth = curr->lockdep_depth + 1 - i;
1864         cn = nr_chain_hlocks;
1865         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1866                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1867                 if (n == cn)
1868                         break;
1869                 cn = n;
1870         }
1871         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1872                 chain->base = cn;
1873                 for (j = 0; j < chain->depth - 1; j++, i++) {
1874                         int lock_id = curr->held_locks[i].class_idx - 1;
1875                         chain_hlocks[chain->base + j] = lock_id;
1876                 }
1877                 chain_hlocks[chain->base + j] = class - lock_classes;
1878         }
1879         list_add_tail_rcu(&chain->entry, hash_head);
1880         debug_atomic_inc(chain_lookup_misses);
1881         inc_chains();
1882
1883         return 1;
1884 }
1885
1886 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1887                 struct held_lock *hlock, int chain_head, u64 chain_key)
1888 {
1889         /*
1890          * Trylock needs to maintain the stack of held locks, but it
1891          * does not add new dependencies, because trylock can be done
1892          * in any order.
1893          *
1894          * We look up the chain_key and do the O(N^2) check and update of
1895          * the dependencies only if this is a new dependency chain.
1896          * (If lookup_chain_cache() returns with 1 it acquires
1897          * graph_lock for us)
1898          */
1899         if (!hlock->trylock && (hlock->check == 2) &&
1900             lookup_chain_cache(curr, hlock, chain_key)) {
1901                 /*
1902                  * Check whether last held lock:
1903                  *
1904                  * - is irq-safe, if this lock is irq-unsafe
1905                  * - is softirq-safe, if this lock is hardirq-unsafe
1906                  *
1907                  * And check whether the new lock's dependency graph
1908                  * could lead back to the previous lock.
1909                  *
1910                  * any of these scenarios could lead to a deadlock. If
1911                  * All validations
1912                  */
1913                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1914
1915                 if (!ret)
1916                         return 0;
1917                 /*
1918                  * Mark recursive read, as we jump over it when
1919                  * building dependencies (just like we jump over
1920                  * trylock entries):
1921                  */
1922                 if (ret == 2)
1923                         hlock->read = 2;
1924                 /*
1925                  * Add dependency only if this lock is not the head
1926                  * of the chain, and if it's not a secondary read-lock:
1927                  */
1928                 if (!chain_head && ret != 2)
1929                         if (!check_prevs_add(curr, hlock))
1930                                 return 0;
1931                 graph_unlock();
1932         } else
1933                 /* after lookup_chain_cache(): */
1934                 if (unlikely(!debug_locks))
1935                         return 0;
1936
1937         return 1;
1938 }
1939 #else
1940 static inline int validate_chain(struct task_struct *curr,
1941                 struct lockdep_map *lock, struct held_lock *hlock,
1942                 int chain_head, u64 chain_key)
1943 {
1944         return 1;
1945 }
1946 #endif
1947
1948 /*
1949  * We are building curr_chain_key incrementally, so double-check
1950  * it from scratch, to make sure that it's done correctly:
1951  */
1952 static void check_chain_key(struct task_struct *curr)
1953 {
1954 #ifdef CONFIG_DEBUG_LOCKDEP
1955         struct held_lock *hlock, *prev_hlock = NULL;
1956         unsigned int i, id;
1957         u64 chain_key = 0;
1958
1959         for (i = 0; i < curr->lockdep_depth; i++) {
1960                 hlock = curr->held_locks + i;
1961                 if (chain_key != hlock->prev_chain_key) {
1962                         debug_locks_off();
1963                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1964                                 curr->lockdep_depth, i,
1965                                 (unsigned long long)chain_key,
1966                                 (unsigned long long)hlock->prev_chain_key);
1967                         return;
1968                 }
1969                 id = hlock->class_idx - 1;
1970                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1971                         return;
1972
1973                 if (prev_hlock && (prev_hlock->irq_context !=
1974                                                         hlock->irq_context))
1975                         chain_key = 0;
1976                 chain_key = iterate_chain_key(chain_key, id);
1977                 prev_hlock = hlock;
1978         }
1979         if (chain_key != curr->curr_chain_key) {
1980                 debug_locks_off();
1981                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1982                         curr->lockdep_depth, i,
1983                         (unsigned long long)chain_key,
1984                         (unsigned long long)curr->curr_chain_key);
1985         }
1986 #endif
1987 }
1988
1989 static int
1990 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1991                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1992 {
1993         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1994                 return 0;
1995
1996         printk("\n=================================\n");
1997         printk(  "[ INFO: inconsistent lock state ]\n");
1998         print_kernel_version();
1999         printk(  "---------------------------------\n");
2000
2001         printk("inconsistent {%s} -> {%s} usage.\n",
2002                 usage_str[prev_bit], usage_str[new_bit]);
2003
2004         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2005                 curr->comm, task_pid_nr(curr),
2006                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2007                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2008                 trace_hardirqs_enabled(curr),
2009                 trace_softirqs_enabled(curr));
2010         print_lock(this);
2011
2012         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2013         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2014
2015         print_irqtrace_events(curr);
2016         printk("\nother info that might help us debug this:\n");
2017         lockdep_print_held_locks(curr);
2018
2019         printk("\nstack backtrace:\n");
2020         dump_stack();
2021
2022         return 0;
2023 }
2024
2025 /*
2026  * Print out an error if an invalid bit is set:
2027  */
2028 static inline int
2029 valid_state(struct task_struct *curr, struct held_lock *this,
2030             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2031 {
2032         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2033                 return print_usage_bug(curr, this, bad_bit, new_bit);
2034         return 1;
2035 }
2036
2037 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2038                      enum lock_usage_bit new_bit);
2039
2040 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2041
2042 /*
2043  * print irq inversion bug:
2044  */
2045 static int
2046 print_irq_inversion_bug(struct task_struct *curr,
2047                         struct lock_list *root, struct lock_list *other,
2048                         struct held_lock *this, int forwards,
2049                         const char *irqclass)
2050 {
2051         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2052                 return 0;
2053
2054         printk("\n=========================================================\n");
2055         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2056         print_kernel_version();
2057         printk(  "---------------------------------------------------------\n");
2058         printk("%s/%d just changed the state of lock:\n",
2059                 curr->comm, task_pid_nr(curr));
2060         print_lock(this);
2061         if (forwards)
2062                 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2063         else
2064                 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2065         print_lock_name(other->class);
2066         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2067
2068         printk("\nother info that might help us debug this:\n");
2069         lockdep_print_held_locks(curr);
2070
2071         printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2072         if (!save_trace(&root->trace))
2073                 return 0;
2074         print_shortest_lock_dependencies(other, root);
2075
2076         printk("\nstack backtrace:\n");
2077         dump_stack();
2078
2079         return 0;
2080 }
2081
2082 /*
2083  * Prove that in the forwards-direction subgraph starting at <this>
2084  * there is no lock matching <mask>:
2085  */
2086 static int
2087 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2088                      enum lock_usage_bit bit, const char *irqclass)
2089 {
2090         int ret;
2091         struct lock_list root;
2092         struct lock_list *uninitialized_var(target_entry);
2093
2094         root.parent = NULL;
2095         root.class = hlock_class(this);
2096         ret = find_usage_forwards(&root, bit, &target_entry);
2097         if (ret < 0)
2098                 return print_bfs_bug(ret);
2099         if (ret == 1)
2100                 return ret;
2101
2102         return print_irq_inversion_bug(curr, &root, target_entry,
2103                                         this, 1, irqclass);
2104 }
2105
2106 /*
2107  * Prove that in the backwards-direction subgraph starting at <this>
2108  * there is no lock matching <mask>:
2109  */
2110 static int
2111 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2112                       enum lock_usage_bit bit, const char *irqclass)
2113 {
2114         int ret;
2115         struct lock_list root;
2116         struct lock_list *uninitialized_var(target_entry);
2117
2118         root.parent = NULL;
2119         root.class = hlock_class(this);
2120         ret = find_usage_backwards(&root, bit, &target_entry);
2121         if (ret < 0)
2122                 return print_bfs_bug(ret);
2123         if (ret == 1)
2124                 return ret;
2125
2126         return print_irq_inversion_bug(curr, &root, target_entry,
2127                                         this, 0, irqclass);
2128 }
2129
2130 void print_irqtrace_events(struct task_struct *curr)
2131 {
2132         printk("irq event stamp: %u\n", curr->irq_events);
2133         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2134         print_ip_sym(curr->hardirq_enable_ip);
2135         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2136         print_ip_sym(curr->hardirq_disable_ip);
2137         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2138         print_ip_sym(curr->softirq_enable_ip);
2139         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2140         print_ip_sym(curr->softirq_disable_ip);
2141 }
2142
2143 static int HARDIRQ_verbose(struct lock_class *class)
2144 {
2145 #if HARDIRQ_VERBOSE
2146         return class_filter(class);
2147 #endif
2148         return 0;
2149 }
2150
2151 static int SOFTIRQ_verbose(struct lock_class *class)
2152 {
2153 #if SOFTIRQ_VERBOSE
2154         return class_filter(class);
2155 #endif
2156         return 0;
2157 }
2158
2159 static int RECLAIM_FS_verbose(struct lock_class *class)
2160 {
2161 #if RECLAIM_VERBOSE
2162         return class_filter(class);
2163 #endif
2164         return 0;
2165 }
2166
2167 #define STRICT_READ_CHECKS      1
2168
2169 static int (*state_verbose_f[])(struct lock_class *class) = {
2170 #define LOCKDEP_STATE(__STATE) \
2171         __STATE##_verbose,
2172 #include "lockdep_states.h"
2173 #undef LOCKDEP_STATE
2174 };
2175
2176 static inline int state_verbose(enum lock_usage_bit bit,
2177                                 struct lock_class *class)
2178 {
2179         return state_verbose_f[bit >> 2](class);
2180 }
2181
2182 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2183                              enum lock_usage_bit bit, const char *name);
2184
2185 static int
2186 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2187                 enum lock_usage_bit new_bit)
2188 {
2189         int excl_bit = exclusive_bit(new_bit);
2190         int read = new_bit & 1;
2191         int dir = new_bit & 2;
2192
2193         /*
2194          * mark USED_IN has to look forwards -- to ensure no dependency
2195          * has ENABLED state, which would allow recursion deadlocks.
2196          *
2197          * mark ENABLED has to look backwards -- to ensure no dependee
2198          * has USED_IN state, which, again, would allow  recursion deadlocks.
2199          */
2200         check_usage_f usage = dir ?
2201                 check_usage_backwards : check_usage_forwards;
2202
2203         /*
2204          * Validate that this particular lock does not have conflicting
2205          * usage states.
2206          */
2207         if (!valid_state(curr, this, new_bit, excl_bit))
2208                 return 0;
2209
2210         /*
2211          * Validate that the lock dependencies don't have conflicting usage
2212          * states.
2213          */
2214         if ((!read || !dir || STRICT_READ_CHECKS) &&
2215                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2216                 return 0;
2217
2218         /*
2219          * Check for read in write conflicts
2220          */
2221         if (!read) {
2222                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2223                         return 0;
2224
2225                 if (STRICT_READ_CHECKS &&
2226                         !usage(curr, this, excl_bit + 1,
2227                                 state_name(new_bit + 1)))
2228                         return 0;
2229         }
2230
2231         if (state_verbose(new_bit, hlock_class(this)))
2232                 return 2;
2233
2234         return 1;
2235 }
2236
2237 enum mark_type {
2238 #define LOCKDEP_STATE(__STATE)  __STATE,
2239 #include "lockdep_states.h"
2240 #undef LOCKDEP_STATE
2241 };
2242
2243 /*
2244  * Mark all held locks with a usage bit:
2245  */
2246 static int
2247 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2248 {
2249         enum lock_usage_bit usage_bit;
2250         struct held_lock *hlock;
2251         int i;
2252
2253         for (i = 0; i < curr->lockdep_depth; i++) {
2254                 hlock = curr->held_locks + i;
2255
2256                 usage_bit = 2 + (mark << 2); /* ENABLED */
2257                 if (hlock->read)
2258                         usage_bit += 1; /* READ */
2259
2260                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2261
2262                 if (!mark_lock(curr, hlock, usage_bit))
2263                         return 0;
2264         }
2265
2266         return 1;
2267 }
2268
2269 /*
2270  * Debugging helper: via this flag we know that we are in
2271  * 'early bootup code', and will warn about any invalid irqs-on event:
2272  */
2273 static int early_boot_irqs_enabled;
2274
2275 void early_boot_irqs_off(void)
2276 {
2277         early_boot_irqs_enabled = 0;
2278 }
2279
2280 void early_boot_irqs_on(void)
2281 {
2282         early_boot_irqs_enabled = 1;
2283 }
2284
2285 /*
2286  * Hardirqs will be enabled:
2287  */
2288 void trace_hardirqs_on_caller(unsigned long ip)
2289 {
2290         struct task_struct *curr = current;
2291
2292         time_hardirqs_on(CALLER_ADDR0, ip);
2293
2294         if (unlikely(!debug_locks || current->lockdep_recursion))
2295                 return;
2296
2297         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2298                 return;
2299
2300         if (unlikely(curr->hardirqs_enabled)) {
2301                 debug_atomic_inc(redundant_hardirqs_on);
2302                 return;
2303         }
2304         /* we'll do an OFF -> ON transition: */
2305         curr->hardirqs_enabled = 1;
2306
2307         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2308                 return;
2309         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2310                 return;
2311         /*
2312          * We are going to turn hardirqs on, so set the
2313          * usage bit for all held locks:
2314          */
2315         if (!mark_held_locks(curr, HARDIRQ))
2316                 return;
2317         /*
2318          * If we have softirqs enabled, then set the usage
2319          * bit for all held locks. (disabled hardirqs prevented
2320          * this bit from being set before)
2321          */
2322         if (curr->softirqs_enabled)
2323                 if (!mark_held_locks(curr, SOFTIRQ))
2324                         return;
2325
2326         curr->hardirq_enable_ip = ip;
2327         curr->hardirq_enable_event = ++curr->irq_events;
2328         debug_atomic_inc(hardirqs_on_events);
2329 }
2330 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2331
2332 void trace_hardirqs_on(void)
2333 {
2334         trace_hardirqs_on_caller(CALLER_ADDR0);
2335 }
2336 EXPORT_SYMBOL(trace_hardirqs_on);
2337
2338 /*
2339  * Hardirqs were disabled:
2340  */
2341 void trace_hardirqs_off_caller(unsigned long ip)
2342 {
2343         struct task_struct *curr = current;
2344
2345         time_hardirqs_off(CALLER_ADDR0, ip);
2346
2347         if (unlikely(!debug_locks || current->lockdep_recursion))
2348                 return;
2349
2350         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2351                 return;
2352
2353         if (curr->hardirqs_enabled) {
2354                 /*
2355                  * We have done an ON -> OFF transition:
2356                  */
2357                 curr->hardirqs_enabled = 0;
2358                 curr->hardirq_disable_ip = ip;
2359                 curr->hardirq_disable_event = ++curr->irq_events;
2360                 debug_atomic_inc(hardirqs_off_events);
2361         } else
2362                 debug_atomic_inc(redundant_hardirqs_off);
2363 }
2364 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2365
2366 void trace_hardirqs_off(void)
2367 {
2368         trace_hardirqs_off_caller(CALLER_ADDR0);
2369 }
2370 EXPORT_SYMBOL(trace_hardirqs_off);
2371
2372 /*
2373  * Softirqs will be enabled:
2374  */
2375 void trace_softirqs_on(unsigned long ip)
2376 {
2377         struct task_struct *curr = current;
2378
2379         if (unlikely(!debug_locks))
2380                 return;
2381
2382         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2383                 return;
2384
2385         if (curr->softirqs_enabled) {
2386                 debug_atomic_inc(redundant_softirqs_on);
2387                 return;
2388         }
2389
2390         /*
2391          * We'll do an OFF -> ON transition:
2392          */
2393         curr->softirqs_enabled = 1;
2394         curr->softirq_enable_ip = ip;
2395         curr->softirq_enable_event = ++curr->irq_events;
2396         debug_atomic_inc(softirqs_on_events);
2397         /*
2398          * We are going to turn softirqs on, so set the
2399          * usage bit for all held locks, if hardirqs are
2400          * enabled too:
2401          */
2402         if (curr->hardirqs_enabled)
2403                 mark_held_locks(curr, SOFTIRQ);
2404 }
2405
2406 /*
2407  * Softirqs were disabled:
2408  */
2409 void trace_softirqs_off(unsigned long ip)
2410 {
2411         struct task_struct *curr = current;
2412
2413         if (unlikely(!debug_locks))
2414                 return;
2415
2416         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2417                 return;
2418
2419         if (curr->softirqs_enabled) {
2420                 /*
2421                  * We have done an ON -> OFF transition:
2422                  */
2423                 curr->softirqs_enabled = 0;
2424                 curr->softirq_disable_ip = ip;
2425                 curr->softirq_disable_event = ++curr->irq_events;
2426                 debug_atomic_inc(softirqs_off_events);
2427                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2428         } else
2429                 debug_atomic_inc(redundant_softirqs_off);
2430 }
2431
2432 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2433 {
2434         struct task_struct *curr = current;
2435
2436         if (unlikely(!debug_locks))
2437                 return;
2438
2439         /* no reclaim without waiting on it */
2440         if (!(gfp_mask & __GFP_WAIT))
2441                 return;
2442
2443         /* this guy won't enter reclaim */
2444         if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2445                 return;
2446
2447         /* We're only interested __GFP_FS allocations for now */
2448         if (!(gfp_mask & __GFP_FS))
2449                 return;
2450
2451         if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2452                 return;
2453
2454         mark_held_locks(curr, RECLAIM_FS);
2455 }
2456
2457 static void check_flags(unsigned long flags);
2458
2459 void lockdep_trace_alloc(gfp_t gfp_mask)
2460 {
2461         unsigned long flags;
2462
2463         if (unlikely(current->lockdep_recursion))
2464                 return;
2465
2466         raw_local_irq_save(flags);
2467         check_flags(flags);
2468         current->lockdep_recursion = 1;
2469         __lockdep_trace_alloc(gfp_mask, flags);
2470         current->lockdep_recursion = 0;
2471         raw_local_irq_restore(flags);
2472 }
2473
2474 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2475 {
2476         /*
2477          * If non-trylock use in a hardirq or softirq context, then
2478          * mark the lock as used in these contexts:
2479          */
2480         if (!hlock->trylock) {
2481                 if (hlock->read) {
2482                         if (curr->hardirq_context)
2483                                 if (!mark_lock(curr, hlock,
2484                                                 LOCK_USED_IN_HARDIRQ_READ))
2485                                         return 0;
2486                         if (curr->softirq_context)
2487                                 if (!mark_lock(curr, hlock,
2488                                                 LOCK_USED_IN_SOFTIRQ_READ))
2489                                         return 0;
2490                 } else {
2491                         if (curr->hardirq_context)
2492                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2493                                         return 0;
2494                         if (curr->softirq_context)
2495                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2496                                         return 0;
2497                 }
2498         }
2499         if (!hlock->hardirqs_off) {
2500                 if (hlock->read) {
2501                         if (!mark_lock(curr, hlock,
2502                                         LOCK_ENABLED_HARDIRQ_READ))
2503                                 return 0;
2504                         if (curr->softirqs_enabled)
2505                                 if (!mark_lock(curr, hlock,
2506                                                 LOCK_ENABLED_SOFTIRQ_READ))
2507                                         return 0;
2508                 } else {
2509                         if (!mark_lock(curr, hlock,
2510                                         LOCK_ENABLED_HARDIRQ))
2511                                 return 0;
2512                         if (curr->softirqs_enabled)
2513                                 if (!mark_lock(curr, hlock,
2514                                                 LOCK_ENABLED_SOFTIRQ))
2515                                         return 0;
2516                 }
2517         }
2518
2519         /*
2520          * We reuse the irq context infrastructure more broadly as a general
2521          * context checking code. This tests GFP_FS recursion (a lock taken
2522          * during reclaim for a GFP_FS allocation is held over a GFP_FS
2523          * allocation).
2524          */
2525         if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2526                 if (hlock->read) {
2527                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2528                                         return 0;
2529                 } else {
2530                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2531                                         return 0;
2532                 }
2533         }
2534
2535         return 1;
2536 }
2537
2538 static int separate_irq_context(struct task_struct *curr,
2539                 struct held_lock *hlock)
2540 {
2541         unsigned int depth = curr->lockdep_depth;
2542
2543         /*
2544          * Keep track of points where we cross into an interrupt context:
2545          */
2546         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2547                                 curr->softirq_context;
2548         if (depth) {
2549                 struct held_lock *prev_hlock;
2550
2551                 prev_hlock = curr->held_locks + depth-1;
2552                 /*
2553                  * If we cross into another context, reset the
2554                  * hash key (this also prevents the checking and the
2555                  * adding of the dependency to 'prev'):
2556                  */
2557                 if (prev_hlock->irq_context != hlock->irq_context)
2558                         return 1;
2559         }
2560         return 0;
2561 }
2562
2563 #else
2564
2565 static inline
2566 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2567                 enum lock_usage_bit new_bit)
2568 {
2569         WARN_ON(1);
2570         return 1;
2571 }
2572
2573 static inline int mark_irqflags(struct task_struct *curr,
2574                 struct held_lock *hlock)
2575 {
2576         return 1;
2577 }
2578
2579 static inline int separate_irq_context(struct task_struct *curr,
2580                 struct held_lock *hlock)
2581 {
2582         return 0;
2583 }
2584
2585 void lockdep_trace_alloc(gfp_t gfp_mask)
2586 {
2587 }
2588
2589 #endif
2590
2591 /*
2592  * Mark a lock with a usage bit, and validate the state transition:
2593  */
2594 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2595                              enum lock_usage_bit new_bit)
2596 {
2597         unsigned int new_mask = 1 << new_bit, ret = 1;
2598
2599         /*
2600          * If already set then do not dirty the cacheline,
2601          * nor do any checks:
2602          */
2603         if (likely(hlock_class(this)->usage_mask & new_mask))
2604                 return 1;
2605
2606         if (!graph_lock())
2607                 return 0;
2608         /*
2609          * Make sure we didnt race:
2610          */
2611         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2612                 graph_unlock();
2613                 return 1;
2614         }
2615
2616         hlock_class(this)->usage_mask |= new_mask;
2617
2618         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2619                 return 0;
2620
2621         switch (new_bit) {
2622 #define LOCKDEP_STATE(__STATE)                  \
2623         case LOCK_USED_IN_##__STATE:            \
2624         case LOCK_USED_IN_##__STATE##_READ:     \
2625         case LOCK_ENABLED_##__STATE:            \
2626         case LOCK_ENABLED_##__STATE##_READ:
2627 #include "lockdep_states.h"
2628 #undef LOCKDEP_STATE
2629                 ret = mark_lock_irq(curr, this, new_bit);
2630                 if (!ret)
2631                         return 0;
2632                 break;
2633         case LOCK_USED:
2634                 debug_atomic_dec(nr_unused_locks);
2635                 break;
2636         default:
2637                 if (!debug_locks_off_graph_unlock())
2638                         return 0;
2639                 WARN_ON(1);
2640                 return 0;
2641         }
2642
2643         graph_unlock();
2644
2645         /*
2646          * We must printk outside of the graph_lock:
2647          */
2648         if (ret == 2) {
2649                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2650                 print_lock(this);
2651                 print_irqtrace_events(curr);
2652                 dump_stack();
2653         }
2654
2655         return ret;
2656 }
2657
2658 /*
2659  * Initialize a lock instance's lock-class mapping info:
2660  */
2661 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2662                       struct lock_class_key *key, int subclass)
2663 {
2664         lock->class_cache = NULL;
2665 #ifdef CONFIG_LOCK_STAT
2666         lock->cpu = raw_smp_processor_id();
2667 #endif
2668
2669         if (DEBUG_LOCKS_WARN_ON(!name)) {
2670                 lock->name = "NULL";
2671                 return;
2672         }
2673
2674         lock->name = name;
2675
2676         if (DEBUG_LOCKS_WARN_ON(!key))
2677                 return;
2678         /*
2679          * Sanity check, the lock-class key must be persistent:
2680          */
2681         if (!static_obj(key)) {
2682                 printk("BUG: key %p not in .data!\n", key);
2683                 DEBUG_LOCKS_WARN_ON(1);
2684                 return;
2685         }
2686         lock->key = key;
2687
2688         if (unlikely(!debug_locks))
2689                 return;
2690
2691         if (subclass)
2692                 register_lock_class(lock, subclass, 1);
2693 }
2694 EXPORT_SYMBOL_GPL(lockdep_init_map);
2695
2696 /*
2697  * This gets called for every mutex_lock*()/spin_lock*() operation.
2698  * We maintain the dependency maps and validate the locking attempt:
2699  */
2700 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2701                           int trylock, int read, int check, int hardirqs_off,
2702                           struct lockdep_map *nest_lock, unsigned long ip,
2703                           int references)
2704 {
2705         struct task_struct *curr = current;
2706         struct lock_class *class = NULL;
2707         struct held_lock *hlock;
2708         unsigned int depth, id;
2709         int chain_head = 0;
2710         int class_idx;
2711         u64 chain_key;
2712
2713         if (!prove_locking)
2714                 check = 1;
2715
2716         if (unlikely(!debug_locks))
2717                 return 0;
2718
2719         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2720                 return 0;
2721
2722         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2723                 debug_locks_off();
2724                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2725                 printk("turning off the locking correctness validator.\n");
2726                 dump_stack();
2727                 return 0;
2728         }
2729
2730         if (!subclass)
2731                 class = lock->class_cache;
2732         /*
2733          * Not cached yet or subclass?
2734          */
2735         if (unlikely(!class)) {
2736                 class = register_lock_class(lock, subclass, 0);
2737                 if (!class)
2738                         return 0;
2739         }
2740         atomic_inc((atomic_t *)&class->ops);
2741         if (very_verbose(class)) {
2742                 printk("\nacquire class [%p] %s", class->key, class->name);
2743                 if (class->name_version > 1)
2744                         printk("#%d", class->name_version);
2745                 printk("\n");
2746                 dump_stack();
2747         }
2748
2749         /*
2750          * Add the lock to the list of currently held locks.
2751          * (we dont increase the depth just yet, up until the
2752          * dependency checks are done)
2753          */
2754         depth = curr->lockdep_depth;
2755         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2756                 return 0;
2757
2758         class_idx = class - lock_classes + 1;
2759
2760         if (depth) {
2761                 hlock = curr->held_locks + depth - 1;
2762                 if (hlock->class_idx == class_idx && nest_lock) {
2763                         if (hlock->references)
2764                                 hlock->references++;
2765                         else
2766                                 hlock->references = 2;
2767
2768                         return 1;
2769                 }
2770         }
2771
2772         hlock = curr->held_locks + depth;
2773         if (DEBUG_LOCKS_WARN_ON(!class))
2774                 return 0;
2775         hlock->class_idx = class_idx;
2776         hlock->acquire_ip = ip;
2777         hlock->instance = lock;
2778         hlock->nest_lock = nest_lock;
2779         hlock->trylock = trylock;
2780         hlock->read = read;
2781         hlock->check = check;
2782         hlock->hardirqs_off = !!hardirqs_off;
2783         hlock->references = references;
2784 #ifdef CONFIG_LOCK_STAT
2785         hlock->waittime_stamp = 0;
2786         hlock->holdtime_stamp = lockstat_clock();
2787 #endif
2788
2789         if (check == 2 && !mark_irqflags(curr, hlock))
2790                 return 0;
2791
2792         /* mark it as used: */
2793         if (!mark_lock(curr, hlock, LOCK_USED))
2794                 return 0;
2795
2796         /*
2797          * Calculate the chain hash: it's the combined hash of all the
2798          * lock keys along the dependency chain. We save the hash value
2799          * at every step so that we can get the current hash easily
2800          * after unlock. The chain hash is then used to cache dependency
2801          * results.
2802          *
2803          * The 'key ID' is what is the most compact key value to drive
2804          * the hash, not class->key.
2805          */
2806         id = class - lock_classes;
2807         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2808                 return 0;
2809
2810         chain_key = curr->curr_chain_key;
2811         if (!depth) {
2812                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2813                         return 0;
2814                 chain_head = 1;
2815         }
2816
2817         hlock->prev_chain_key = chain_key;
2818         if (separate_irq_context(curr, hlock)) {
2819                 chain_key = 0;
2820                 chain_head = 1;
2821         }
2822         chain_key = iterate_chain_key(chain_key, id);
2823
2824         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2825                 return 0;
2826
2827         curr->curr_chain_key = chain_key;
2828         curr->lockdep_depth++;
2829         check_chain_key(curr);
2830 #ifdef CONFIG_DEBUG_LOCKDEP
2831         if (unlikely(!debug_locks))
2832                 return 0;
2833 #endif
2834         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2835                 debug_locks_off();
2836                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2837                 printk("turning off the locking correctness validator.\n");
2838                 dump_stack();
2839                 return 0;
2840         }
2841
2842         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2843                 max_lockdep_depth = curr->lockdep_depth;
2844
2845         return 1;
2846 }
2847
2848 static int
2849 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2850                            unsigned long ip)
2851 {
2852         if (!debug_locks_off())
2853                 return 0;
2854         if (debug_locks_silent)
2855                 return 0;
2856
2857         printk("\n=====================================\n");
2858         printk(  "[ BUG: bad unlock balance detected! ]\n");
2859         printk(  "-------------------------------------\n");
2860         printk("%s/%d is trying to release lock (",
2861                 curr->comm, task_pid_nr(curr));
2862         print_lockdep_cache(lock);
2863         printk(") at:\n");
2864         print_ip_sym(ip);
2865         printk("but there are no more locks to release!\n");
2866         printk("\nother info that might help us debug this:\n");
2867         lockdep_print_held_locks(curr);
2868
2869         printk("\nstack backtrace:\n");
2870         dump_stack();
2871
2872         return 0;
2873 }
2874
2875 /*
2876  * Common debugging checks for both nested and non-nested unlock:
2877  */
2878 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2879                         unsigned long ip)
2880 {
2881         if (unlikely(!debug_locks))
2882                 return 0;
2883         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2884                 return 0;
2885
2886         if (curr->lockdep_depth <= 0)
2887                 return print_unlock_inbalance_bug(curr, lock, ip);
2888
2889         return 1;
2890 }
2891
2892 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
2893 {
2894         if (hlock->instance == lock)
2895                 return 1;
2896
2897         if (hlock->references) {
2898                 struct lock_class *class = lock->class_cache;
2899
2900                 if (!class)
2901                         class = look_up_lock_class(lock, 0);
2902
2903                 if (DEBUG_LOCKS_WARN_ON(!class))
2904                         return 0;
2905
2906                 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
2907                         return 0;
2908
2909                 if (hlock->class_idx == class - lock_classes + 1)
2910                         return 1;
2911         }
2912
2913         return 0;
2914 }
2915
2916 static int
2917 __lock_set_class(struct lockdep_map *lock, const char *name,
2918                  struct lock_class_key *key, unsigned int subclass,
2919                  unsigned long ip)
2920 {
2921         struct task_struct *curr = current;
2922         struct held_lock *hlock, *prev_hlock;
2923         struct lock_class *class;
2924         unsigned int depth;
2925         int i;
2926
2927         depth = curr->lockdep_depth;
2928         if (DEBUG_LOCKS_WARN_ON(!depth))
2929                 return 0;
2930
2931         prev_hlock = NULL;
2932         for (i = depth-1; i >= 0; i--) {
2933                 hlock = curr->held_locks + i;
2934                 /*
2935                  * We must not cross into another context:
2936                  */
2937                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2938                         break;
2939                 if (match_held_lock(hlock, lock))
2940                         goto found_it;
2941                 prev_hlock = hlock;
2942         }
2943         return print_unlock_inbalance_bug(curr, lock, ip);
2944
2945 found_it:
2946         lockdep_init_map(lock, name, key, 0);
2947         class = register_lock_class(lock, subclass, 0);
2948         hlock->class_idx = class - lock_classes + 1;
2949
2950         curr->lockdep_depth = i;
2951         curr->curr_chain_key = hlock->prev_chain_key;
2952
2953         for (; i < depth; i++) {
2954                 hlock = curr->held_locks + i;
2955                 if (!__lock_acquire(hlock->instance,
2956                         hlock_class(hlock)->subclass, hlock->trylock,
2957                                 hlock->read, hlock->check, hlock->hardirqs_off,
2958                                 hlock->nest_lock, hlock->acquire_ip,
2959                                 hlock->references))
2960                         return 0;
2961         }
2962
2963         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2964                 return 0;
2965         return 1;
2966 }
2967
2968 /*
2969  * Remove the lock to the list of currently held locks in a
2970  * potentially non-nested (out of order) manner. This is a
2971  * relatively rare operation, as all the unlock APIs default
2972  * to nested mode (which uses lock_release()):
2973  */
2974 static int
2975 lock_release_non_nested(struct task_struct *curr,
2976                         struct lockdep_map *lock, unsigned long ip)
2977 {
2978         struct held_lock *hlock, *prev_hlock;
2979         unsigned int depth;
2980         int i;
2981
2982         /*
2983          * Check whether the lock exists in the current stack
2984          * of held locks:
2985          */
2986         depth = curr->lockdep_depth;
2987         if (DEBUG_LOCKS_WARN_ON(!depth))
2988                 return 0;
2989
2990         prev_hlock = NULL;
2991         for (i = depth-1; i >= 0; i--) {
2992                 hlock = curr->held_locks + i;
2993                 /*
2994                  * We must not cross into another context:
2995                  */
2996                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2997                         break;
2998                 if (match_held_lock(hlock, lock))
2999                         goto found_it;
3000                 prev_hlock = hlock;
3001         }
3002         return print_unlock_inbalance_bug(curr, lock, ip);
3003
3004 found_it:
3005         if (hlock->instance == lock)
3006                 lock_release_holdtime(hlock);
3007
3008         if (hlock->references) {
3009                 hlock->references--;
3010                 if (hlock->references) {
3011                         /*
3012                          * We had, and after removing one, still have
3013                          * references, the current lock stack is still
3014                          * valid. We're done!
3015                          */
3016                         return 1;
3017                 }
3018         }
3019
3020         /*
3021          * We have the right lock to unlock, 'hlock' points to it.
3022          * Now we remove it from the stack, and add back the other
3023          * entries (if any), recalculating the hash along the way:
3024          */
3025
3026         curr->lockdep_depth = i;
3027         curr->curr_chain_key = hlock->prev_chain_key;
3028
3029         for (i++; i < depth; i++) {
3030                 hlock = curr->held_locks + i;
3031                 if (!__lock_acquire(hlock->instance,
3032                         hlock_class(hlock)->subclass, hlock->trylock,
3033                                 hlock->read, hlock->check, hlock->hardirqs_off,
3034                                 hlock->nest_lock, hlock->acquire_ip,
3035                                 hlock->references))
3036                         return 0;
3037         }
3038
3039         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3040                 return 0;
3041         return 1;
3042 }
3043
3044 /*
3045  * Remove the lock to the list of currently held locks - this gets
3046  * called on mutex_unlock()/spin_unlock*() (or on a failed
3047  * mutex_lock_interruptible()). This is done for unlocks that nest
3048  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3049  */
3050 static int lock_release_nested(struct task_struct *curr,
3051                                struct lockdep_map *lock, unsigned long ip)
3052 {
3053         struct held_lock *hlock;
3054         unsigned int depth;
3055
3056         /*
3057          * Pop off the top of the lock stack:
3058          */
3059         depth = curr->lockdep_depth - 1;
3060         hlock = curr->held_locks + depth;
3061
3062         /*
3063          * Is the unlock non-nested:
3064          */
3065         if (hlock->instance != lock || hlock->references)
3066                 return lock_release_non_nested(curr, lock, ip);
3067         curr->lockdep_depth--;
3068
3069         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3070                 return 0;
3071
3072         curr->curr_chain_key = hlock->prev_chain_key;
3073
3074         lock_release_holdtime(hlock);
3075
3076 #ifdef CONFIG_DEBUG_LOCKDEP
3077         hlock->prev_chain_key = 0;
3078         hlock->class_idx = 0;
3079         hlock->acquire_ip = 0;
3080         hlock->irq_context = 0;
3081 #endif
3082         return 1;
3083 }
3084
3085 /*
3086  * Remove the lock to the list of currently held locks - this gets
3087  * called on mutex_unlock()/spin_unlock*() (or on a failed
3088  * mutex_lock_interruptible()). This is done for unlocks that nest
3089  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3090  */
3091 static void
3092 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3093 {
3094         struct task_struct *curr = current;
3095
3096         if (!check_unlock(curr, lock, ip))
3097                 return;
3098
3099         if (nested) {
3100                 if (!lock_release_nested(curr, lock, ip))
3101                         return;
3102         } else {
3103                 if (!lock_release_non_nested(curr, lock, ip))
3104                         return;
3105         }
3106
3107         check_chain_key(curr);
3108 }
3109
3110 static int __lock_is_held(struct lockdep_map *lock)
3111 {
3112         struct task_struct *curr = current;
3113         int i;
3114
3115         for (i = 0; i < curr->lockdep_depth; i++) {
3116                 struct held_lock *hlock = curr->held_locks + i;
3117
3118                 if (match_held_lock(hlock, lock))
3119                         return 1;
3120         }
3121
3122         return 0;
3123 }
3124
3125 /*
3126  * Check whether we follow the irq-flags state precisely:
3127  */
3128 static void check_flags(unsigned long flags)
3129 {
3130 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3131     defined(CONFIG_TRACE_IRQFLAGS)
3132         if (!debug_locks)
3133                 return;
3134
3135         if (irqs_disabled_flags(flags)) {
3136                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3137                         printk("possible reason: unannotated irqs-off.\n");
3138                 }
3139         } else {
3140                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3141                         printk("possible reason: unannotated irqs-on.\n");
3142                 }
3143         }
3144
3145         /*
3146          * We dont accurately track softirq state in e.g.
3147          * hardirq contexts (such as on 4KSTACKS), so only
3148          * check if not in hardirq contexts:
3149          */
3150         if (!hardirq_count()) {
3151                 if (softirq_count())
3152                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3153                 else
3154                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3155         }
3156
3157         if (!debug_locks)
3158                 print_irqtrace_events(current);
3159 #endif
3160 }
3161
3162 void lock_set_class(struct lockdep_map *lock, const char *name,
3163                     struct lock_class_key *key, unsigned int subclass,
3164                     unsigned long ip)
3165 {
3166         unsigned long flags;
3167
3168         if (unlikely(current->lockdep_recursion))
3169                 return;
3170
3171         raw_local_irq_save(flags);
3172         current->lockdep_recursion = 1;
3173         check_flags(flags);
3174         if (__lock_set_class(lock, name, key, subclass, ip))
3175                 check_chain_key(current);
3176         current->lockdep_recursion = 0;
3177         raw_local_irq_restore(flags);
3178 }
3179 EXPORT_SYMBOL_GPL(lock_set_class);
3180
3181 /*
3182  * We are not always called with irqs disabled - do that here,
3183  * and also avoid lockdep recursion:
3184  */
3185 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3186                           int trylock, int read, int check,
3187                           struct lockdep_map *nest_lock, 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         check_flags(flags);
3196
3197         current->lockdep_recursion = 1;
3198         trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3199         __lock_acquire(lock, subclass, trylock, read, check,
3200                        irqs_disabled_flags(flags), nest_lock, ip, 0);
3201         current->lockdep_recursion = 0;
3202         raw_local_irq_restore(flags);
3203 }
3204 EXPORT_SYMBOL_GPL(lock_acquire);
3205
3206 void lock_release(struct lockdep_map *lock, int nested,
3207                           unsigned long ip)
3208 {
3209         unsigned long flags;
3210
3211         if (unlikely(current->lockdep_recursion))
3212                 return;
3213
3214         raw_local_irq_save(flags);
3215         check_flags(flags);
3216         current->lockdep_recursion = 1;
3217         trace_lock_release(lock, nested, ip);
3218         __lock_release(lock, nested, ip);
3219         current->lockdep_recursion = 0;
3220         raw_local_irq_restore(flags);
3221 }
3222 EXPORT_SYMBOL_GPL(lock_release);
3223
3224 int lock_is_held(struct lockdep_map *lock)
3225 {
3226         unsigned long flags;
3227         int ret = 0;
3228
3229         if (unlikely(current->lockdep_recursion))
3230                 return ret;
3231
3232         raw_local_irq_save(flags);
3233         check_flags(flags);
3234
3235         current->lockdep_recursion = 1;
3236         ret = __lock_is_held(lock);
3237         current->lockdep_recursion = 0;
3238         raw_local_irq_restore(flags);
3239
3240         return ret;
3241 }
3242 EXPORT_SYMBOL_GPL(lock_is_held);
3243
3244 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3245 {
3246         current->lockdep_reclaim_gfp = gfp_mask;
3247 }
3248
3249 void lockdep_clear_current_reclaim_state(void)
3250 {
3251         current->lockdep_reclaim_gfp = 0;
3252 }
3253
3254 #ifdef CONFIG_LOCK_STAT
3255 static int
3256 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3257                            unsigned long ip)
3258 {
3259         if (!debug_locks_off())
3260                 return 0;
3261         if (debug_locks_silent)
3262                 return 0;
3263
3264         printk("\n=================================\n");
3265         printk(  "[ BUG: bad contention detected! ]\n");
3266         printk(  "---------------------------------\n");
3267         printk("%s/%d is trying to contend lock (",
3268                 curr->comm, task_pid_nr(curr));
3269         print_lockdep_cache(lock);
3270         printk(") at:\n");
3271         print_ip_sym(ip);
3272         printk("but there are no locks held!\n");
3273         printk("\nother info that might help us debug this:\n");
3274         lockdep_print_held_locks(curr);
3275
3276         printk("\nstack backtrace:\n");
3277         dump_stack();
3278
3279         return 0;
3280 }
3281
3282 static void
3283 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3284 {
3285         struct task_struct *curr = current;
3286         struct held_lock *hlock, *prev_hlock;
3287         struct lock_class_stats *stats;
3288         unsigned int depth;
3289         int i, contention_point, contending_point;
3290
3291         depth = curr->lockdep_depth;
3292         if (DEBUG_LOCKS_WARN_ON(!depth))
3293                 return;
3294
3295         prev_hlock = NULL;
3296         for (i = depth-1; i >= 0; i--) {
3297                 hlock = curr->held_locks + i;
3298                 /*
3299                  * We must not cross into another context:
3300                  */
3301                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3302                         break;
3303                 if (match_held_lock(hlock, lock))
3304                         goto found_it;
3305                 prev_hlock = hlock;
3306         }
3307         print_lock_contention_bug(curr, lock, ip);
3308         return;
3309
3310 found_it:
3311         if (hlock->instance != lock)
3312                 return;
3313
3314         hlock->waittime_stamp = lockstat_clock();
3315
3316         contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3317         contending_point = lock_point(hlock_class(hlock)->contending_point,
3318                                       lock->ip);
3319
3320         stats = get_lock_stats(hlock_class(hlock));
3321         if (contention_point < LOCKSTAT_POINTS)
3322                 stats->contention_point[contention_point]++;
3323         if (contending_point < LOCKSTAT_POINTS)
3324                 stats->contending_point[contending_point]++;
3325         if (lock->cpu != smp_processor_id())
3326                 stats->bounces[bounce_contended + !!hlock->read]++;
3327         put_lock_stats(stats);
3328 }
3329
3330 static void
3331 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3332 {
3333         struct task_struct *curr = current;
3334         struct held_lock *hlock, *prev_hlock;
3335         struct lock_class_stats *stats;
3336         unsigned int depth;
3337         u64 now, waittime = 0;
3338         int i, cpu;
3339
3340         depth = curr->lockdep_depth;
3341         if (DEBUG_LOCKS_WARN_ON(!depth))
3342                 return;
3343
3344         prev_hlock = NULL;
3345         for (i = depth-1; i >= 0; i--) {
3346                 hlock = curr->held_locks + i;
3347                 /*
3348                  * We must not cross into another context:
3349                  */
3350                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3351                         break;
3352                 if (match_held_lock(hlock, lock))
3353                         goto found_it;
3354                 prev_hlock = hlock;
3355         }
3356         print_lock_contention_bug(curr, lock, _RET_IP_);
3357         return;
3358
3359 found_it:
3360         if (hlock->instance != lock)
3361                 return;
3362
3363         cpu = smp_processor_id();
3364         if (hlock->waittime_stamp) {
3365                 now = lockstat_clock();
3366                 waittime = now - hlock->waittime_stamp;
3367                 hlock->holdtime_stamp = now;
3368         }
3369
3370         trace_lock_acquired(lock, ip, waittime);
3371
3372         stats = get_lock_stats(hlock_class(hlock));
3373         if (waittime) {
3374                 if (hlock->read)
3375                         lock_time_inc(&stats->read_waittime, waittime);
3376                 else
3377                         lock_time_inc(&stats->write_waittime, waittime);
3378         }
3379         if (lock->cpu != cpu)
3380                 stats->bounces[bounce_acquired + !!hlock->read]++;
3381         put_lock_stats(stats);
3382
3383         lock->cpu = cpu;
3384         lock->ip = ip;
3385 }
3386
3387 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3388 {
3389         unsigned long flags;
3390
3391         if (unlikely(!lock_stat))
3392                 return;
3393
3394         if (unlikely(current->lockdep_recursion))
3395                 return;
3396
3397         raw_local_irq_save(flags);
3398         check_flags(flags);
3399         current->lockdep_recursion = 1;
3400         trace_lock_contended(lock, ip);
3401         __lock_contended(lock, ip);
3402         current->lockdep_recursion = 0;
3403         raw_local_irq_restore(flags);
3404 }
3405 EXPORT_SYMBOL_GPL(lock_contended);
3406
3407 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3408 {
3409         unsigned long flags;
3410
3411         if (unlikely(!lock_stat))
3412                 return;
3413
3414         if (unlikely(current->lockdep_recursion))
3415                 return;
3416
3417         raw_local_irq_save(flags);
3418         check_flags(flags);
3419         current->lockdep_recursion = 1;
3420         __lock_acquired(lock, ip);
3421         current->lockdep_recursion = 0;
3422         raw_local_irq_restore(flags);
3423 }
3424 EXPORT_SYMBOL_GPL(lock_acquired);
3425 #endif
3426
3427 /*
3428  * Used by the testsuite, sanitize the validator state
3429  * after a simulated failure:
3430  */
3431
3432 void lockdep_reset(void)
3433 {
3434         unsigned long flags;
3435         int i;
3436
3437         raw_local_irq_save(flags);
3438         current->curr_chain_key = 0;
3439         current->lockdep_depth = 0;
3440         current->lockdep_recursion = 0;
3441         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3442         nr_hardirq_chains = 0;
3443         nr_softirq_chains = 0;
3444         nr_process_chains = 0;
3445         debug_locks = 1;
3446         for (i = 0; i < CHAINHASH_SIZE; i++)
3447                 INIT_LIST_HEAD(chainhash_table + i);
3448         raw_local_irq_restore(flags);
3449 }
3450
3451 static void zap_class(struct lock_class *class)
3452 {
3453         int i;
3454
3455         /*
3456          * Remove all dependencies this lock is
3457          * involved in:
3458          */
3459         for (i = 0; i < nr_list_entries; i++) {
3460                 if (list_entries[i].class == class)
3461                         list_del_rcu(&list_entries[i].entry);
3462         }
3463         /*
3464          * Unhash the class and remove it from the all_lock_classes list:
3465          */
3466         list_del_rcu(&class->hash_entry);
3467         list_del_rcu(&class->lock_entry);
3468
3469         class->key = NULL;
3470 }
3471
3472 static inline int within(const void *addr, void *start, unsigned long size)
3473 {
3474         return addr >= start && addr < start + size;
3475 }
3476
3477 void lockdep_free_key_range(void *start, unsigned long size)
3478 {
3479         struct lock_class *class, *next;
3480         struct list_head *head;
3481         unsigned long flags;
3482         int i;
3483         int locked;
3484
3485         raw_local_irq_save(flags);
3486         locked = graph_lock();
3487
3488         /*
3489          * Unhash all classes that were created by this module:
3490          */
3491         for (i = 0; i < CLASSHASH_SIZE; i++) {
3492                 head = classhash_table + i;
3493                 if (list_empty(head))
3494                         continue;
3495                 list_for_each_entry_safe(class, next, head, hash_entry) {
3496                         if (within(class->key, start, size))
3497                                 zap_class(class);
3498                         else if (within(class->name, start, size))
3499                                 zap_class(class);
3500                 }
3501         }
3502
3503         if (locked)
3504                 graph_unlock();
3505         raw_local_irq_restore(flags);
3506 }
3507
3508 void lockdep_reset_lock(struct lockdep_map *lock)
3509 {
3510         struct lock_class *class, *next;
3511         struct list_head *head;
3512         unsigned long flags;
3513         int i, j;
3514         int locked;
3515
3516         raw_local_irq_save(flags);
3517
3518         /*
3519          * Remove all classes this lock might have:
3520          */
3521         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3522                 /*
3523                  * If the class exists we look it up and zap it:
3524                  */
3525                 class = look_up_lock_class(lock, j);
3526                 if (class)
3527                         zap_class(class);
3528         }
3529         /*
3530          * Debug check: in the end all mapped classes should
3531          * be gone.
3532          */
3533         locked = graph_lock();
3534         for (i = 0; i < CLASSHASH_SIZE; i++) {
3535                 head = classhash_table + i;
3536                 if (list_empty(head))
3537                         continue;
3538                 list_for_each_entry_safe(class, next, head, hash_entry) {
3539                         if (unlikely(class == lock->class_cache)) {
3540                                 if (debug_locks_off_graph_unlock())
3541                                         WARN_ON(1);
3542                                 goto out_restore;
3543                         }
3544                 }
3545         }
3546         if (locked)
3547                 graph_unlock();
3548
3549 out_restore:
3550         raw_local_irq_restore(flags);
3551 }
3552
3553 void lockdep_init(void)
3554 {
3555         int i;
3556
3557         /*
3558          * Some architectures have their own start_kernel()
3559          * code which calls lockdep_init(), while we also
3560          * call lockdep_init() from the start_kernel() itself,
3561          * and we want to initialize the hashes only once:
3562          */
3563         if (lockdep_initialized)
3564                 return;
3565
3566         for (i = 0; i < CLASSHASH_SIZE; i++)
3567                 INIT_LIST_HEAD(classhash_table + i);
3568
3569         for (i = 0; i < CHAINHASH_SIZE; i++)
3570                 INIT_LIST_HEAD(chainhash_table + i);
3571
3572         lockdep_initialized = 1;
3573 }
3574
3575 void __init lockdep_info(void)
3576 {
3577         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3578
3579         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3580         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3581         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3582         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3583         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3584         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3585         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3586
3587         printk(" memory used by lock dependency info: %lu kB\n",
3588                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3589                 sizeof(struct list_head) * CLASSHASH_SIZE +
3590                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3591                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3592                 sizeof(struct list_head) * CHAINHASH_SIZE
3593 #ifdef CONFIG_PROVE_LOCKING
3594                 + sizeof(struct circular_queue)
3595 #endif
3596                 ) / 1024
3597                 );
3598
3599         printk(" per task-struct memory footprint: %lu bytes\n",
3600                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3601
3602 #ifdef CONFIG_DEBUG_LOCKDEP
3603         if (lockdep_init_error) {
3604                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3605                 printk("Call stack leading to lockdep invocation was:\n");
3606                 print_stack_trace(&lockdep_init_trace, 0);
3607         }
3608 #endif
3609 }
3610
3611 static void
3612 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3613                      const void *mem_to, struct held_lock *hlock)
3614 {
3615         if (!debug_locks_off())
3616                 return;
3617         if (debug_locks_silent)
3618                 return;
3619
3620         printk("\n=========================\n");
3621         printk(  "[ BUG: held lock freed! ]\n");
3622         printk(  "-------------------------\n");
3623         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3624                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3625         print_lock(hlock);
3626         lockdep_print_held_locks(curr);
3627
3628         printk("\nstack backtrace:\n");
3629         dump_stack();
3630 }
3631
3632 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3633                                 const void* lock_from, unsigned long lock_len)
3634 {
3635         return lock_from + lock_len <= mem_from ||
3636                 mem_from + mem_len <= lock_from;
3637 }
3638
3639 /*
3640  * Called when kernel memory is freed (or unmapped), or if a lock
3641  * is destroyed or reinitialized - this code checks whether there is
3642  * any held lock in the memory range of <from> to <to>:
3643  */
3644 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3645 {
3646         struct task_struct *curr = current;
3647         struct held_lock *hlock;
3648         unsigned long flags;
3649         int i;
3650
3651         if (unlikely(!debug_locks))
3652                 return;
3653
3654         local_irq_save(flags);
3655         for (i = 0; i < curr->lockdep_depth; i++) {
3656                 hlock = curr->held_locks + i;
3657
3658                 if (not_in_range(mem_from, mem_len, hlock->instance,
3659                                         sizeof(*hlock->instance)))
3660                         continue;
3661
3662                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3663                 break;
3664         }
3665         local_irq_restore(flags);
3666 }
3667 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3668
3669 static void print_held_locks_bug(struct task_struct *curr)
3670 {
3671         if (!debug_locks_off())
3672                 return;
3673         if (debug_locks_silent)
3674                 return;
3675
3676         printk("\n=====================================\n");
3677         printk(  "[ BUG: lock held at task exit time! ]\n");
3678         printk(  "-------------------------------------\n");
3679         printk("%s/%d is exiting with locks still held!\n",
3680                 curr->comm, task_pid_nr(curr));
3681         lockdep_print_held_locks(curr);
3682
3683         printk("\nstack backtrace:\n");
3684         dump_stack();
3685 }
3686
3687 void debug_check_no_locks_held(struct task_struct *task)
3688 {
3689         if (unlikely(task->lockdep_depth > 0))
3690                 print_held_locks_bug(task);
3691 }
3692
3693 void debug_show_all_locks(void)
3694 {
3695         struct task_struct *g, *p;
3696         int count = 10;
3697         int unlock = 1;
3698
3699         if (unlikely(!debug_locks)) {
3700                 printk("INFO: lockdep is turned off.\n");
3701                 return;
3702         }
3703         printk("\nShowing all locks held in the system:\n");
3704
3705         /*
3706          * Here we try to get the tasklist_lock as hard as possible,
3707          * if not successful after 2 seconds we ignore it (but keep
3708          * trying). This is to enable a debug printout even if a
3709          * tasklist_lock-holding task deadlocks or crashes.
3710          */
3711 retry:
3712         if (!read_trylock(&tasklist_lock)) {
3713                 if (count == 10)
3714                         printk("hm, tasklist_lock locked, retrying... ");
3715                 if (count) {
3716                         count--;
3717                         printk(" #%d", 10-count);
3718                         mdelay(200);
3719                         goto retry;
3720                 }
3721                 printk(" ignoring it.\n");
3722                 unlock = 0;
3723         } else {
3724                 if (count != 10)
3725                         printk(KERN_CONT " locked it.\n");
3726         }
3727
3728         do_each_thread(g, p) {
3729                 /*
3730                  * It's not reliable to print a task's held locks
3731                  * if it's not sleeping (or if it's not the current
3732                  * task):
3733                  */
3734                 if (p->state == TASK_RUNNING && p != current)
3735                         continue;
3736                 if (p->lockdep_depth)
3737                         lockdep_print_held_locks(p);
3738                 if (!unlock)
3739                         if (read_trylock(&tasklist_lock))
3740                                 unlock = 1;
3741         } while_each_thread(g, p);
3742
3743         printk("\n");
3744         printk("=============================================\n\n");
3745
3746         if (unlock)
3747                 read_unlock(&tasklist_lock);
3748 }
3749 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3750
3751 /*
3752  * Careful: only use this function if you are sure that
3753  * the task cannot run in parallel!
3754  */
3755 void __debug_show_held_locks(struct task_struct *task)
3756 {
3757         if (unlikely(!debug_locks)) {
3758                 printk("INFO: lockdep is turned off.\n");
3759                 return;
3760         }
3761         lockdep_print_held_locks(task);
3762 }
3763 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3764
3765 void debug_show_held_locks(struct task_struct *task)
3766 {
3767                 __debug_show_held_locks(task);
3768 }
3769 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3770
3771 void lockdep_sys_exit(void)
3772 {
3773         struct task_struct *curr = current;
3774
3775         if (unlikely(curr->lockdep_depth)) {
3776                 if (!debug_locks_off())
3777                         return;
3778                 printk("\n================================================\n");
3779                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3780                 printk(  "------------------------------------------------\n");
3781                 printk("%s/%d is leaving the kernel with locks still held!\n",
3782                                 curr->comm, curr->pid);
3783                 lockdep_print_held_locks(curr);
3784         }
3785 }
3786
3787 void lockdep_rcu_dereference(const char *file, const int line)
3788 {
3789         struct task_struct *curr = current;
3790
3791         if (!debug_locks_off())
3792                 return;
3793         printk("\n===================================================\n");
3794         printk(  "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3795         printk(  "---------------------------------------------------\n");
3796         printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3797                         file, line);
3798         printk("\nother info that might help us debug this:\n\n");
3799         printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
3800         lockdep_print_held_locks(curr);
3801         printk("\nstack backtrace:\n");
3802         dump_stack();
3803 }
3804 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);