367f72452ff4abbe0d036d5b2b5b85601ac39963
[linux-2.6.git] / kernel / lockdep.c
1 /*
2  * kernel/lockdep.c
3  *
4  * Runtime locking correctness validator
5  *
6  * Started by Ingo Molnar:
7  *
8  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
10  *
11  * this code maps all the lock dependencies as they occur in a live kernel
12  * and will warn about the following classes of locking bugs:
13  *
14  * - lock inversion scenarios
15  * - circular lock dependencies
16  * - hardirq/softirq safe/unsafe locking bugs
17  *
18  * Bugs are reported even if the current locking scenario does not cause
19  * any deadlock at this point.
20  *
21  * I.e. if anytime in the past two locks were taken in a different order,
22  * even if it happened for another task, even if those were different
23  * locks (but of the same class as this lock), this code will detect it.
24  *
25  * Thanks to Arjan van de Ven for coming up with the initial idea of
26  * mapping lock dependencies runtime.
27  */
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
47
48 #include <asm/sections.h>
49
50 #include "lockdep_internals.h"
51
52 #define CREATE_TRACE_POINTS
53 #include <trace/events/lock.h>
54
55 #ifdef CONFIG_PROVE_LOCKING
56 int prove_locking = 1;
57 module_param(prove_locking, int, 0644);
58 #else
59 #define prove_locking 0
60 #endif
61
62 #ifdef CONFIG_LOCK_STAT
63 int lock_stat = 1;
64 module_param(lock_stat, int, 0644);
65 #else
66 #define lock_stat 0
67 #endif
68
69 /*
70  * lockdep_lock: protects the lockdep graph, the hashes and the
71  *               class/list/hash allocators.
72  *
73  * This is one of the rare exceptions where it's justified
74  * to use a raw spinlock - we really dont want the spinlock
75  * code to recurse back into the lockdep code...
76  */
77 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
78
79 static int graph_lock(void)
80 {
81         arch_spin_lock(&lockdep_lock);
82         /*
83          * Make sure that if another CPU detected a bug while
84          * walking the graph we dont change it (while the other
85          * CPU is busy printing out stuff with the graph lock
86          * dropped already)
87          */
88         if (!debug_locks) {
89                 arch_spin_unlock(&lockdep_lock);
90                 return 0;
91         }
92         /* prevent any recursions within lockdep from causing deadlocks */
93         current->lockdep_recursion++;
94         return 1;
95 }
96
97 static inline int graph_unlock(void)
98 {
99         if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
100                 return DEBUG_LOCKS_WARN_ON(1);
101
102         current->lockdep_recursion--;
103         arch_spin_unlock(&lockdep_lock);
104         return 0;
105 }
106
107 /*
108  * Turn lock debugging off and return with 0 if it was off already,
109  * and also release the graph lock:
110  */
111 static inline int debug_locks_off_graph_unlock(void)
112 {
113         int ret = debug_locks_off();
114
115         arch_spin_unlock(&lockdep_lock);
116
117         return ret;
118 }
119
120 static int lockdep_initialized;
121
122 unsigned long nr_list_entries;
123 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
124
125 /*
126  * All data structures here are protected by the global debug_lock.
127  *
128  * Mutex key structs only get allocated, once during bootup, and never
129  * get freed - this significantly simplifies the debugging code.
130  */
131 unsigned long nr_lock_classes;
132 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
133
134 static inline struct lock_class *hlock_class(struct held_lock *hlock)
135 {
136         if (!hlock->class_idx) {
137                 DEBUG_LOCKS_WARN_ON(1);
138                 return NULL;
139         }
140         return lock_classes + hlock->class_idx - 1;
141 }
142
143 #ifdef CONFIG_LOCK_STAT
144 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
145                       cpu_lock_stats);
146
147 static inline u64 lockstat_clock(void)
148 {
149         return 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 atomic_t chain_lookup_hits;
435 atomic_t chain_lookup_misses;
436 atomic_t hardirqs_on_events;
437 atomic_t hardirqs_off_events;
438 atomic_t redundant_hardirqs_on;
439 atomic_t redundant_hardirqs_off;
440 atomic_t softirqs_on_events;
441 atomic_t softirqs_off_events;
442 atomic_t redundant_softirqs_on;
443 atomic_t redundant_softirqs_off;
444 atomic_t nr_unused_locks;
445 atomic_t nr_cyclic_checks;
446 atomic_t nr_find_usage_forwards_checks;
447 atomic_t nr_find_usage_backwards_checks;
448 #endif
449
450 /*
451  * Locking printouts:
452  */
453
454 #define __USAGE(__STATE)                                                \
455         [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
456         [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
457         [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
458         [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
459
460 static const char *usage_str[] =
461 {
462 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
463 #include "lockdep_states.h"
464 #undef LOCKDEP_STATE
465         [LOCK_USED] = "INITIAL USE",
466 };
467
468 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
469 {
470         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
471 }
472
473 static inline unsigned long lock_flag(enum lock_usage_bit bit)
474 {
475         return 1UL << bit;
476 }
477
478 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
479 {
480         char c = '.';
481
482         if (class->usage_mask & lock_flag(bit + 2))
483                 c = '+';
484         if (class->usage_mask & lock_flag(bit)) {
485                 c = '-';
486                 if (class->usage_mask & lock_flag(bit + 2))
487                         c = '?';
488         }
489
490         return c;
491 }
492
493 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
494 {
495         int i = 0;
496
497 #define LOCKDEP_STATE(__STATE)                                          \
498         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
499         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
500 #include "lockdep_states.h"
501 #undef LOCKDEP_STATE
502
503         usage[i] = '\0';
504 }
505
506 static void print_lock_name(struct lock_class *class)
507 {
508         char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
509         const char *name;
510
511         get_usage_chars(class, usage);
512
513         name = class->name;
514         if (!name) {
515                 name = __get_key_name(class->key, str);
516                 printk(" (%s", name);
517         } else {
518                 printk(" (%s", name);
519                 if (class->name_version > 1)
520                         printk("#%d", class->name_version);
521                 if (class->subclass)
522                         printk("/%d", class->subclass);
523         }
524         printk("){%s}", usage);
525 }
526
527 static void print_lockdep_cache(struct lockdep_map *lock)
528 {
529         const char *name;
530         char str[KSYM_NAME_LEN];
531
532         name = lock->name;
533         if (!name)
534                 name = __get_key_name(lock->key->subkeys, str);
535
536         printk("%s", name);
537 }
538
539 static void print_lock(struct held_lock *hlock)
540 {
541         print_lock_name(hlock_class(hlock));
542         printk(", at: ");
543         print_ip_sym(hlock->acquire_ip);
544 }
545
546 static void lockdep_print_held_locks(struct task_struct *curr)
547 {
548         int i, depth = curr->lockdep_depth;
549
550         if (!depth) {
551                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
552                 return;
553         }
554         printk("%d lock%s held by %s/%d:\n",
555                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
556
557         for (i = 0; i < depth; i++) {
558                 printk(" #%d: ", i);
559                 print_lock(curr->held_locks + i);
560         }
561 }
562
563 static void print_kernel_version(void)
564 {
565         printk("%s %.*s\n", init_utsname()->release,
566                 (int)strcspn(init_utsname()->version, " "),
567                 init_utsname()->version);
568 }
569
570 static int very_verbose(struct lock_class *class)
571 {
572 #if VERY_VERBOSE
573         return class_filter(class);
574 #endif
575         return 0;
576 }
577
578 /*
579  * Is this the address of a static object:
580  */
581 static int static_obj(void *obj)
582 {
583         unsigned long start = (unsigned long) &_stext,
584                       end   = (unsigned long) &_end,
585                       addr  = (unsigned long) obj;
586 #ifdef CONFIG_SMP
587         int i;
588 #endif
589
590         /*
591          * static variable?
592          */
593         if ((addr >= start) && (addr < end))
594                 return 1;
595
596         if (arch_is_kernel_data(addr))
597                 return 1;
598
599 #ifdef CONFIG_SMP
600         /*
601          * percpu var?
602          */
603         for_each_possible_cpu(i) {
604                 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
605                 end   = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
606                                         + per_cpu_offset(i);
607
608                 if ((addr >= start) && (addr < end))
609                         return 1;
610         }
611 #endif
612
613         /*
614          * module var?
615          */
616         return is_module_address(addr);
617 }
618
619 /*
620  * To make lock name printouts unique, we calculate a unique
621  * class->name_version generation counter:
622  */
623 static int count_matching_names(struct lock_class *new_class)
624 {
625         struct lock_class *class;
626         int count = 0;
627
628         if (!new_class->name)
629                 return 0;
630
631         list_for_each_entry(class, &all_lock_classes, lock_entry) {
632                 if (new_class->key - new_class->subclass == class->key)
633                         return class->name_version;
634                 if (class->name && !strcmp(class->name, new_class->name))
635                         count = max(count, class->name_version);
636         }
637
638         return count + 1;
639 }
640
641 /*
642  * Register a lock's class in the hash-table, if the class is not present
643  * yet. Otherwise we look it up. We cache the result in the lock object
644  * itself, so actual lookup of the hash should be once per lock object.
645  */
646 static inline struct lock_class *
647 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
648 {
649         struct lockdep_subclass_key *key;
650         struct list_head *hash_head;
651         struct lock_class *class;
652
653 #ifdef CONFIG_DEBUG_LOCKDEP
654         /*
655          * If the architecture calls into lockdep before initializing
656          * the hashes then we'll warn about it later. (we cannot printk
657          * right now)
658          */
659         if (unlikely(!lockdep_initialized)) {
660                 lockdep_init();
661                 lockdep_init_error = 1;
662                 save_stack_trace(&lockdep_init_trace);
663         }
664 #endif
665
666         /*
667          * Static locks do not have their class-keys yet - for them the key
668          * is the lock object itself:
669          */
670         if (unlikely(!lock->key))
671                 lock->key = (void *)lock;
672
673         /*
674          * NOTE: the class-key must be unique. For dynamic locks, a static
675          * lock_class_key variable is passed in through the mutex_init()
676          * (or spin_lock_init()) call - which acts as the key. For static
677          * locks we use the lock object itself as the key.
678          */
679         BUILD_BUG_ON(sizeof(struct lock_class_key) >
680                         sizeof(struct lockdep_map));
681
682         key = lock->key->subkeys + subclass;
683
684         hash_head = classhashentry(key);
685
686         /*
687          * We can walk the hash lockfree, because the hash only
688          * grows, and we are careful when adding entries to the end:
689          */
690         list_for_each_entry(class, hash_head, hash_entry) {
691                 if (class->key == key) {
692                         WARN_ON_ONCE(class->name != lock->name);
693                         return class;
694                 }
695         }
696
697         return NULL;
698 }
699
700 /*
701  * Register a lock's class in the hash-table, if the class is not present
702  * yet. Otherwise we look it up. We cache the result in the lock object
703  * itself, so actual lookup of the hash should be once per lock object.
704  */
705 static inline struct lock_class *
706 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
707 {
708         struct lockdep_subclass_key *key;
709         struct list_head *hash_head;
710         struct lock_class *class;
711         unsigned long flags;
712
713         class = look_up_lock_class(lock, subclass);
714         if (likely(class))
715                 return class;
716
717         /*
718          * Debug-check: all keys must be persistent!
719          */
720         if (!static_obj(lock->key)) {
721                 debug_locks_off();
722                 printk("INFO: trying to register non-static key.\n");
723                 printk("the code is fine but needs lockdep annotation.\n");
724                 printk("turning off the locking correctness validator.\n");
725                 dump_stack();
726
727                 return NULL;
728         }
729
730         key = lock->key->subkeys + subclass;
731         hash_head = classhashentry(key);
732
733         raw_local_irq_save(flags);
734         if (!graph_lock()) {
735                 raw_local_irq_restore(flags);
736                 return NULL;
737         }
738         /*
739          * We have to do the hash-walk again, to avoid races
740          * with another CPU:
741          */
742         list_for_each_entry(class, hash_head, hash_entry)
743                 if (class->key == key)
744                         goto out_unlock_set;
745         /*
746          * Allocate a new key from the static array, and add it to
747          * the hash:
748          */
749         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
750                 if (!debug_locks_off_graph_unlock()) {
751                         raw_local_irq_restore(flags);
752                         return NULL;
753                 }
754                 raw_local_irq_restore(flags);
755
756                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
757                 printk("turning off the locking correctness validator.\n");
758                 dump_stack();
759                 return NULL;
760         }
761         class = lock_classes + nr_lock_classes++;
762         debug_atomic_inc(&nr_unused_locks);
763         class->key = key;
764         class->name = lock->name;
765         class->subclass = subclass;
766         INIT_LIST_HEAD(&class->lock_entry);
767         INIT_LIST_HEAD(&class->locks_before);
768         INIT_LIST_HEAD(&class->locks_after);
769         class->name_version = count_matching_names(class);
770         /*
771          * We use RCU's safe list-add method to make
772          * parallel walking of the hash-list safe:
773          */
774         list_add_tail_rcu(&class->hash_entry, hash_head);
775         /*
776          * Add it to the global list of classes:
777          */
778         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
779
780         if (verbose(class)) {
781                 graph_unlock();
782                 raw_local_irq_restore(flags);
783
784                 printk("\nnew class %p: %s", class->key, class->name);
785                 if (class->name_version > 1)
786                         printk("#%d", class->name_version);
787                 printk("\n");
788                 dump_stack();
789
790                 raw_local_irq_save(flags);
791                 if (!graph_lock()) {
792                         raw_local_irq_restore(flags);
793                         return NULL;
794                 }
795         }
796 out_unlock_set:
797         graph_unlock();
798         raw_local_irq_restore(flags);
799
800         if (!subclass || force)
801                 lock->class_cache = class;
802
803         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
804                 return NULL;
805
806         return class;
807 }
808
809 #ifdef CONFIG_PROVE_LOCKING
810 /*
811  * Allocate a lockdep entry. (assumes the graph_lock held, returns
812  * with NULL on failure)
813  */
814 static struct lock_list *alloc_list_entry(void)
815 {
816         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
817                 if (!debug_locks_off_graph_unlock())
818                         return NULL;
819
820                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
821                 printk("turning off the locking correctness validator.\n");
822                 dump_stack();
823                 return NULL;
824         }
825         return list_entries + nr_list_entries++;
826 }
827
828 /*
829  * Add a new dependency to the head of the list:
830  */
831 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
832                             struct list_head *head, unsigned long ip, int distance)
833 {
834         struct lock_list *entry;
835         /*
836          * Lock not present yet - get a new dependency struct and
837          * add it to the list:
838          */
839         entry = alloc_list_entry();
840         if (!entry)
841                 return 0;
842
843         if (!save_trace(&entry->trace))
844                 return 0;
845
846         entry->class = this;
847         entry->distance = distance;
848         /*
849          * Since we never remove from the dependency list, the list can
850          * be walked lockless by other CPUs, it's only allocation
851          * that must be protected by the spinlock. But this also means
852          * we must make new entries visible only once writes to the
853          * entry become visible - hence the RCU op:
854          */
855         list_add_tail_rcu(&entry->entry, head);
856
857         return 1;
858 }
859
860 /*
861  * For good efficiency of modular, we use power of 2
862  */
863 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
864 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
865
866 /*
867  * The circular_queue and helpers is used to implement the
868  * breadth-first search(BFS)algorithem, by which we can build
869  * the shortest path from the next lock to be acquired to the
870  * previous held lock if there is a circular between them.
871  */
872 struct circular_queue {
873         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
874         unsigned int  front, rear;
875 };
876
877 static struct circular_queue lock_cq;
878
879 unsigned int max_bfs_queue_depth;
880
881 static unsigned int lockdep_dependency_gen_id;
882
883 static inline void __cq_init(struct circular_queue *cq)
884 {
885         cq->front = cq->rear = 0;
886         lockdep_dependency_gen_id++;
887 }
888
889 static inline int __cq_empty(struct circular_queue *cq)
890 {
891         return (cq->front == cq->rear);
892 }
893
894 static inline int __cq_full(struct circular_queue *cq)
895 {
896         return ((cq->rear + 1) & CQ_MASK) == cq->front;
897 }
898
899 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
900 {
901         if (__cq_full(cq))
902                 return -1;
903
904         cq->element[cq->rear] = elem;
905         cq->rear = (cq->rear + 1) & CQ_MASK;
906         return 0;
907 }
908
909 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
910 {
911         if (__cq_empty(cq))
912                 return -1;
913
914         *elem = cq->element[cq->front];
915         cq->front = (cq->front + 1) & CQ_MASK;
916         return 0;
917 }
918
919 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
920 {
921         return (cq->rear - cq->front) & CQ_MASK;
922 }
923
924 static inline void mark_lock_accessed(struct lock_list *lock,
925                                         struct lock_list *parent)
926 {
927         unsigned long nr;
928
929         nr = lock - list_entries;
930         WARN_ON(nr >= nr_list_entries);
931         lock->parent = parent;
932         lock->class->dep_gen_id = lockdep_dependency_gen_id;
933 }
934
935 static inline unsigned long lock_accessed(struct lock_list *lock)
936 {
937         unsigned long nr;
938
939         nr = lock - list_entries;
940         WARN_ON(nr >= nr_list_entries);
941         return lock->class->dep_gen_id == lockdep_dependency_gen_id;
942 }
943
944 static inline struct lock_list *get_lock_parent(struct lock_list *child)
945 {
946         return child->parent;
947 }
948
949 static inline int get_lock_depth(struct lock_list *child)
950 {
951         int depth = 0;
952         struct lock_list *parent;
953
954         while ((parent = get_lock_parent(child))) {
955                 child = parent;
956                 depth++;
957         }
958         return depth;
959 }
960
961 static int __bfs(struct lock_list *source_entry,
962                  void *data,
963                  int (*match)(struct lock_list *entry, void *data),
964                  struct lock_list **target_entry,
965                  int forward)
966 {
967         struct lock_list *entry;
968         struct list_head *head;
969         struct circular_queue *cq = &lock_cq;
970         int ret = 1;
971
972         if (match(source_entry, data)) {
973                 *target_entry = source_entry;
974                 ret = 0;
975                 goto exit;
976         }
977
978         if (forward)
979                 head = &source_entry->class->locks_after;
980         else
981                 head = &source_entry->class->locks_before;
982
983         if (list_empty(head))
984                 goto exit;
985
986         __cq_init(cq);
987         __cq_enqueue(cq, (unsigned long)source_entry);
988
989         while (!__cq_empty(cq)) {
990                 struct lock_list *lock;
991
992                 __cq_dequeue(cq, (unsigned long *)&lock);
993
994                 if (!lock->class) {
995                         ret = -2;
996                         goto exit;
997                 }
998
999                 if (forward)
1000                         head = &lock->class->locks_after;
1001                 else
1002                         head = &lock->class->locks_before;
1003
1004                 list_for_each_entry(entry, head, entry) {
1005                         if (!lock_accessed(entry)) {
1006                                 unsigned int cq_depth;
1007                                 mark_lock_accessed(entry, lock);
1008                                 if (match(entry, data)) {
1009                                         *target_entry = entry;
1010                                         ret = 0;
1011                                         goto exit;
1012                                 }
1013
1014                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
1015                                         ret = -1;
1016                                         goto exit;
1017                                 }
1018                                 cq_depth = __cq_get_elem_count(cq);
1019                                 if (max_bfs_queue_depth < cq_depth)
1020                                         max_bfs_queue_depth = cq_depth;
1021                         }
1022                 }
1023         }
1024 exit:
1025         return ret;
1026 }
1027
1028 static inline int __bfs_forwards(struct lock_list *src_entry,
1029                         void *data,
1030                         int (*match)(struct lock_list *entry, void *data),
1031                         struct lock_list **target_entry)
1032 {
1033         return __bfs(src_entry, data, match, target_entry, 1);
1034
1035 }
1036
1037 static inline int __bfs_backwards(struct lock_list *src_entry,
1038                         void *data,
1039                         int (*match)(struct lock_list *entry, void *data),
1040                         struct lock_list **target_entry)
1041 {
1042         return __bfs(src_entry, data, match, target_entry, 0);
1043
1044 }
1045
1046 /*
1047  * Recursive, forwards-direction lock-dependency checking, used for
1048  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1049  * checking.
1050  */
1051
1052 /*
1053  * Print a dependency chain entry (this is only done when a deadlock
1054  * has been detected):
1055  */
1056 static noinline int
1057 print_circular_bug_entry(struct lock_list *target, int depth)
1058 {
1059         if (debug_locks_silent)
1060                 return 0;
1061         printk("\n-> #%u", depth);
1062         print_lock_name(target->class);
1063         printk(":\n");
1064         print_stack_trace(&target->trace, 6);
1065
1066         return 0;
1067 }
1068
1069 /*
1070  * When a circular dependency is detected, print the
1071  * header first:
1072  */
1073 static noinline int
1074 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1075                         struct held_lock *check_src,
1076                         struct held_lock *check_tgt)
1077 {
1078         struct task_struct *curr = current;
1079
1080         if (debug_locks_silent)
1081                 return 0;
1082
1083         printk("\n=======================================================\n");
1084         printk(  "[ INFO: possible circular locking dependency detected ]\n");
1085         print_kernel_version();
1086         printk(  "-------------------------------------------------------\n");
1087         printk("%s/%d is trying to acquire lock:\n",
1088                 curr->comm, task_pid_nr(curr));
1089         print_lock(check_src);
1090         printk("\nbut task is already holding lock:\n");
1091         print_lock(check_tgt);
1092         printk("\nwhich lock already depends on the new lock.\n\n");
1093         printk("\nthe existing dependency chain (in reverse order) is:\n");
1094
1095         print_circular_bug_entry(entry, depth);
1096
1097         return 0;
1098 }
1099
1100 static inline int class_equal(struct lock_list *entry, void *data)
1101 {
1102         return entry->class == data;
1103 }
1104
1105 static noinline int print_circular_bug(struct lock_list *this,
1106                                 struct lock_list *target,
1107                                 struct held_lock *check_src,
1108                                 struct held_lock *check_tgt)
1109 {
1110         struct task_struct *curr = current;
1111         struct lock_list *parent;
1112         int depth;
1113
1114         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1115                 return 0;
1116
1117         if (!save_trace(&this->trace))
1118                 return 0;
1119
1120         depth = get_lock_depth(target);
1121
1122         print_circular_bug_header(target, depth, check_src, check_tgt);
1123
1124         parent = get_lock_parent(target);
1125
1126         while (parent) {
1127                 print_circular_bug_entry(parent, --depth);
1128                 parent = get_lock_parent(parent);
1129         }
1130
1131         printk("\nother info that might help us debug this:\n\n");
1132         lockdep_print_held_locks(curr);
1133
1134         printk("\nstack backtrace:\n");
1135         dump_stack();
1136
1137         return 0;
1138 }
1139
1140 static noinline int print_bfs_bug(int ret)
1141 {
1142         if (!debug_locks_off_graph_unlock())
1143                 return 0;
1144
1145         WARN(1, "lockdep bfs error:%d\n", ret);
1146
1147         return 0;
1148 }
1149
1150 static int noop_count(struct lock_list *entry, void *data)
1151 {
1152         (*(unsigned long *)data)++;
1153         return 0;
1154 }
1155
1156 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1157 {
1158         unsigned long  count = 0;
1159         struct lock_list *uninitialized_var(target_entry);
1160
1161         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1162
1163         return count;
1164 }
1165 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1166 {
1167         unsigned long ret, flags;
1168         struct lock_list this;
1169
1170         this.parent = NULL;
1171         this.class = class;
1172
1173         local_irq_save(flags);
1174         arch_spin_lock(&lockdep_lock);
1175         ret = __lockdep_count_forward_deps(&this);
1176         arch_spin_unlock(&lockdep_lock);
1177         local_irq_restore(flags);
1178
1179         return ret;
1180 }
1181
1182 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1183 {
1184         unsigned long  count = 0;
1185         struct lock_list *uninitialized_var(target_entry);
1186
1187         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1188
1189         return count;
1190 }
1191
1192 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1193 {
1194         unsigned long ret, flags;
1195         struct lock_list this;
1196
1197         this.parent = NULL;
1198         this.class = class;
1199
1200         local_irq_save(flags);
1201         arch_spin_lock(&lockdep_lock);
1202         ret = __lockdep_count_backward_deps(&this);
1203         arch_spin_unlock(&lockdep_lock);
1204         local_irq_restore(flags);
1205
1206         return ret;
1207 }
1208
1209 /*
1210  * Prove that the dependency graph starting at <entry> can not
1211  * lead to <target>. Print an error and return 0 if it does.
1212  */
1213 static noinline int
1214 check_noncircular(struct lock_list *root, struct lock_class *target,
1215                 struct lock_list **target_entry)
1216 {
1217         int result;
1218
1219         debug_atomic_inc(&nr_cyclic_checks);
1220
1221         result = __bfs_forwards(root, target, class_equal, target_entry);
1222
1223         return result;
1224 }
1225
1226 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1227 /*
1228  * Forwards and backwards subgraph searching, for the purposes of
1229  * proving that two subgraphs can be connected by a new dependency
1230  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1231  */
1232
1233 static inline int usage_match(struct lock_list *entry, void *bit)
1234 {
1235         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1236 }
1237
1238
1239
1240 /*
1241  * Find a node in the forwards-direction dependency sub-graph starting
1242  * at @root->class that matches @bit.
1243  *
1244  * Return 0 if such a node exists in the subgraph, and put that node
1245  * into *@target_entry.
1246  *
1247  * Return 1 otherwise and keep *@target_entry unchanged.
1248  * Return <0 on error.
1249  */
1250 static int
1251 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1252                         struct lock_list **target_entry)
1253 {
1254         int result;
1255
1256         debug_atomic_inc(&nr_find_usage_forwards_checks);
1257
1258         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1259
1260         return result;
1261 }
1262
1263 /*
1264  * Find a node in the backwards-direction dependency sub-graph starting
1265  * at @root->class that matches @bit.
1266  *
1267  * Return 0 if such a node exists in the subgraph, and put that node
1268  * into *@target_entry.
1269  *
1270  * Return 1 otherwise and keep *@target_entry unchanged.
1271  * Return <0 on error.
1272  */
1273 static int
1274 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1275                         struct lock_list **target_entry)
1276 {
1277         int result;
1278
1279         debug_atomic_inc(&nr_find_usage_backwards_checks);
1280
1281         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1282
1283         return result;
1284 }
1285
1286 static void print_lock_class_header(struct lock_class *class, int depth)
1287 {
1288         int bit;
1289
1290         printk("%*s->", depth, "");
1291         print_lock_name(class);
1292         printk(" ops: %lu", class->ops);
1293         printk(" {\n");
1294
1295         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1296                 if (class->usage_mask & (1 << bit)) {
1297                         int len = depth;
1298
1299                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1300                         len += printk(" at:\n");
1301                         print_stack_trace(class->usage_traces + bit, len);
1302                 }
1303         }
1304         printk("%*s }\n", depth, "");
1305
1306         printk("%*s ... key      at: ",depth,"");
1307         print_ip_sym((unsigned long)class->key);
1308 }
1309
1310 /*
1311  * printk the shortest lock dependencies from @start to @end in reverse order:
1312  */
1313 static void __used
1314 print_shortest_lock_dependencies(struct lock_list *leaf,
1315                                 struct lock_list *root)
1316 {
1317         struct lock_list *entry = leaf;
1318         int depth;
1319
1320         /*compute depth from generated tree by BFS*/
1321         depth = get_lock_depth(leaf);
1322
1323         do {
1324                 print_lock_class_header(entry->class, depth);
1325                 printk("%*s ... acquired at:\n", depth, "");
1326                 print_stack_trace(&entry->trace, 2);
1327                 printk("\n");
1328
1329                 if (depth == 0 && (entry != root)) {
1330                         printk("lockdep:%s bad BFS generated tree\n", __func__);
1331                         break;
1332                 }
1333
1334                 entry = get_lock_parent(entry);
1335                 depth--;
1336         } while (entry && (depth >= 0));
1337
1338         return;
1339 }
1340
1341 static int
1342 print_bad_irq_dependency(struct task_struct *curr,
1343                          struct lock_list *prev_root,
1344                          struct lock_list *next_root,
1345                          struct lock_list *backwards_entry,
1346                          struct lock_list *forwards_entry,
1347                          struct held_lock *prev,
1348                          struct held_lock *next,
1349                          enum lock_usage_bit bit1,
1350                          enum lock_usage_bit bit2,
1351                          const char *irqclass)
1352 {
1353         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1354                 return 0;
1355
1356         printk("\n======================================================\n");
1357         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1358                 irqclass, irqclass);
1359         print_kernel_version();
1360         printk(  "------------------------------------------------------\n");
1361         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1362                 curr->comm, task_pid_nr(curr),
1363                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1364                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1365                 curr->hardirqs_enabled,
1366                 curr->softirqs_enabled);
1367         print_lock(next);
1368
1369         printk("\nand this task is already holding:\n");
1370         print_lock(prev);
1371         printk("which would create a new lock dependency:\n");
1372         print_lock_name(hlock_class(prev));
1373         printk(" ->");
1374         print_lock_name(hlock_class(next));
1375         printk("\n");
1376
1377         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1378                 irqclass);
1379         print_lock_name(backwards_entry->class);
1380         printk("\n... which became %s-irq-safe at:\n", irqclass);
1381
1382         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1383
1384         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1385         print_lock_name(forwards_entry->class);
1386         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1387         printk("...");
1388
1389         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1390
1391         printk("\nother info that might help us debug this:\n\n");
1392         lockdep_print_held_locks(curr);
1393
1394         printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1395         printk(" and the holding lock:\n");
1396         if (!save_trace(&prev_root->trace))
1397                 return 0;
1398         print_shortest_lock_dependencies(backwards_entry, prev_root);
1399
1400         printk("\nthe dependencies between the lock to be acquired");
1401         printk(" and %s-irq-unsafe lock:\n", irqclass);
1402         if (!save_trace(&next_root->trace))
1403                 return 0;
1404         print_shortest_lock_dependencies(forwards_entry, next_root);
1405
1406         printk("\nstack backtrace:\n");
1407         dump_stack();
1408
1409         return 0;
1410 }
1411
1412 static int
1413 check_usage(struct task_struct *curr, struct held_lock *prev,
1414             struct held_lock *next, enum lock_usage_bit bit_backwards,
1415             enum lock_usage_bit bit_forwards, const char *irqclass)
1416 {
1417         int ret;
1418         struct lock_list this, that;
1419         struct lock_list *uninitialized_var(target_entry);
1420         struct lock_list *uninitialized_var(target_entry1);
1421
1422         this.parent = NULL;
1423
1424         this.class = hlock_class(prev);
1425         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1426         if (ret < 0)
1427                 return print_bfs_bug(ret);
1428         if (ret == 1)
1429                 return ret;
1430
1431         that.parent = NULL;
1432         that.class = hlock_class(next);
1433         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1434         if (ret < 0)
1435                 return print_bfs_bug(ret);
1436         if (ret == 1)
1437                 return ret;
1438
1439         return print_bad_irq_dependency(curr, &this, &that,
1440                         target_entry, target_entry1,
1441                         prev, next,
1442                         bit_backwards, bit_forwards, irqclass);
1443 }
1444
1445 static const char *state_names[] = {
1446 #define LOCKDEP_STATE(__STATE) \
1447         __stringify(__STATE),
1448 #include "lockdep_states.h"
1449 #undef LOCKDEP_STATE
1450 };
1451
1452 static const char *state_rnames[] = {
1453 #define LOCKDEP_STATE(__STATE) \
1454         __stringify(__STATE)"-READ",
1455 #include "lockdep_states.h"
1456 #undef LOCKDEP_STATE
1457 };
1458
1459 static inline const char *state_name(enum lock_usage_bit bit)
1460 {
1461         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1462 }
1463
1464 static int exclusive_bit(int new_bit)
1465 {
1466         /*
1467          * USED_IN
1468          * USED_IN_READ
1469          * ENABLED
1470          * ENABLED_READ
1471          *
1472          * bit 0 - write/read
1473          * bit 1 - used_in/enabled
1474          * bit 2+  state
1475          */
1476
1477         int state = new_bit & ~3;
1478         int dir = new_bit & 2;
1479
1480         /*
1481          * keep state, bit flip the direction and strip read.
1482          */
1483         return state | (dir ^ 2);
1484 }
1485
1486 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1487                            struct held_lock *next, enum lock_usage_bit bit)
1488 {
1489         /*
1490          * Prove that the new dependency does not connect a hardirq-safe
1491          * lock with a hardirq-unsafe lock - to achieve this we search
1492          * the backwards-subgraph starting at <prev>, and the
1493          * forwards-subgraph starting at <next>:
1494          */
1495         if (!check_usage(curr, prev, next, bit,
1496                            exclusive_bit(bit), state_name(bit)))
1497                 return 0;
1498
1499         bit++; /* _READ */
1500
1501         /*
1502          * Prove that the new dependency does not connect a hardirq-safe-read
1503          * lock with a hardirq-unsafe lock - to achieve this we search
1504          * the backwards-subgraph starting at <prev>, and the
1505          * forwards-subgraph starting at <next>:
1506          */
1507         if (!check_usage(curr, prev, next, bit,
1508                            exclusive_bit(bit), state_name(bit)))
1509                 return 0;
1510
1511         return 1;
1512 }
1513
1514 static int
1515 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1516                 struct held_lock *next)
1517 {
1518 #define LOCKDEP_STATE(__STATE)                                          \
1519         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1520                 return 0;
1521 #include "lockdep_states.h"
1522 #undef LOCKDEP_STATE
1523
1524         return 1;
1525 }
1526
1527 static void inc_chains(void)
1528 {
1529         if (current->hardirq_context)
1530                 nr_hardirq_chains++;
1531         else {
1532                 if (current->softirq_context)
1533                         nr_softirq_chains++;
1534                 else
1535                         nr_process_chains++;
1536         }
1537 }
1538
1539 #else
1540
1541 static inline int
1542 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1543                 struct held_lock *next)
1544 {
1545         return 1;
1546 }
1547
1548 static inline void inc_chains(void)
1549 {
1550         nr_process_chains++;
1551 }
1552
1553 #endif
1554
1555 static int
1556 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1557                    struct held_lock *next)
1558 {
1559         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1560                 return 0;
1561
1562         printk("\n=============================================\n");
1563         printk(  "[ INFO: possible recursive locking detected ]\n");
1564         print_kernel_version();
1565         printk(  "---------------------------------------------\n");
1566         printk("%s/%d is trying to acquire lock:\n",
1567                 curr->comm, task_pid_nr(curr));
1568         print_lock(next);
1569         printk("\nbut task is already holding lock:\n");
1570         print_lock(prev);
1571
1572         printk("\nother info that might help us debug this:\n");
1573         lockdep_print_held_locks(curr);
1574
1575         printk("\nstack backtrace:\n");
1576         dump_stack();
1577
1578         return 0;
1579 }
1580
1581 /*
1582  * Check whether we are holding such a class already.
1583  *
1584  * (Note that this has to be done separately, because the graph cannot
1585  * detect such classes of deadlocks.)
1586  *
1587  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1588  */
1589 static int
1590 check_deadlock(struct task_struct *curr, struct held_lock *next,
1591                struct lockdep_map *next_instance, int read)
1592 {
1593         struct held_lock *prev;
1594         struct held_lock *nest = NULL;
1595         int i;
1596
1597         for (i = 0; i < curr->lockdep_depth; i++) {
1598                 prev = curr->held_locks + i;
1599
1600                 if (prev->instance == next->nest_lock)
1601                         nest = prev;
1602
1603                 if (hlock_class(prev) != hlock_class(next))
1604                         continue;
1605
1606                 /*
1607                  * Allow read-after-read recursion of the same
1608                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1609                  */
1610                 if ((read == 2) && prev->read)
1611                         return 2;
1612
1613                 /*
1614                  * We're holding the nest_lock, which serializes this lock's
1615                  * nesting behaviour.
1616                  */
1617                 if (nest)
1618                         return 2;
1619
1620                 return print_deadlock_bug(curr, prev, next);
1621         }
1622         return 1;
1623 }
1624
1625 /*
1626  * There was a chain-cache miss, and we are about to add a new dependency
1627  * to a previous lock. We recursively validate the following rules:
1628  *
1629  *  - would the adding of the <prev> -> <next> dependency create a
1630  *    circular dependency in the graph? [== circular deadlock]
1631  *
1632  *  - does the new prev->next dependency connect any hardirq-safe lock
1633  *    (in the full backwards-subgraph starting at <prev>) with any
1634  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1635  *    <next>)? [== illegal lock inversion with hardirq contexts]
1636  *
1637  *  - does the new prev->next dependency connect any softirq-safe lock
1638  *    (in the full backwards-subgraph starting at <prev>) with any
1639  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1640  *    <next>)? [== illegal lock inversion with softirq contexts]
1641  *
1642  * any of these scenarios could lead to a deadlock.
1643  *
1644  * Then if all the validations pass, we add the forwards and backwards
1645  * dependency.
1646  */
1647 static int
1648 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1649                struct held_lock *next, int distance)
1650 {
1651         struct lock_list *entry;
1652         int ret;
1653         struct lock_list this;
1654         struct lock_list *uninitialized_var(target_entry);
1655
1656         /*
1657          * Prove that the new <prev> -> <next> dependency would not
1658          * create a circular dependency in the graph. (We do this by
1659          * forward-recursing into the graph starting at <next>, and
1660          * checking whether we can reach <prev>.)
1661          *
1662          * We are using global variables to control the recursion, to
1663          * keep the stackframe size of the recursive functions low:
1664          */
1665         this.class = hlock_class(next);
1666         this.parent = NULL;
1667         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1668         if (unlikely(!ret))
1669                 return print_circular_bug(&this, target_entry, next, prev);
1670         else if (unlikely(ret < 0))
1671                 return print_bfs_bug(ret);
1672
1673         if (!check_prev_add_irq(curr, prev, next))
1674                 return 0;
1675
1676         /*
1677          * For recursive read-locks we do all the dependency checks,
1678          * but we dont store read-triggered dependencies (only
1679          * write-triggered dependencies). This ensures that only the
1680          * write-side dependencies matter, and that if for example a
1681          * write-lock never takes any other locks, then the reads are
1682          * equivalent to a NOP.
1683          */
1684         if (next->read == 2 || prev->read == 2)
1685                 return 1;
1686         /*
1687          * Is the <prev> -> <next> dependency already present?
1688          *
1689          * (this may occur even though this is a new chain: consider
1690          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1691          *  chains - the second one will be new, but L1 already has
1692          *  L2 added to its dependency list, due to the first chain.)
1693          */
1694         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1695                 if (entry->class == hlock_class(next)) {
1696                         if (distance == 1)
1697                                 entry->distance = 1;
1698                         return 2;
1699                 }
1700         }
1701
1702         /*
1703          * Ok, all validations passed, add the new lock
1704          * to the previous lock's dependency list:
1705          */
1706         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1707                                &hlock_class(prev)->locks_after,
1708                                next->acquire_ip, distance);
1709
1710         if (!ret)
1711                 return 0;
1712
1713         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1714                                &hlock_class(next)->locks_before,
1715                                next->acquire_ip, distance);
1716         if (!ret)
1717                 return 0;
1718
1719         /*
1720          * Debugging printouts:
1721          */
1722         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1723                 graph_unlock();
1724                 printk("\n new dependency: ");
1725                 print_lock_name(hlock_class(prev));
1726                 printk(" => ");
1727                 print_lock_name(hlock_class(next));
1728                 printk("\n");
1729                 dump_stack();
1730                 return graph_lock();
1731         }
1732         return 1;
1733 }
1734
1735 /*
1736  * Add the dependency to all directly-previous locks that are 'relevant'.
1737  * The ones that are relevant are (in increasing distance from curr):
1738  * all consecutive trylock entries and the final non-trylock entry - or
1739  * the end of this context's lock-chain - whichever comes first.
1740  */
1741 static int
1742 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1743 {
1744         int depth = curr->lockdep_depth;
1745         struct held_lock *hlock;
1746
1747         /*
1748          * Debugging checks.
1749          *
1750          * Depth must not be zero for a non-head lock:
1751          */
1752         if (!depth)
1753                 goto out_bug;
1754         /*
1755          * At least two relevant locks must exist for this
1756          * to be a head:
1757          */
1758         if (curr->held_locks[depth].irq_context !=
1759                         curr->held_locks[depth-1].irq_context)
1760                 goto out_bug;
1761
1762         for (;;) {
1763                 int distance = curr->lockdep_depth - depth + 1;
1764                 hlock = curr->held_locks + depth-1;
1765                 /*
1766                  * Only non-recursive-read entries get new dependencies
1767                  * added:
1768                  */
1769                 if (hlock->read != 2) {
1770                         if (!check_prev_add(curr, hlock, next, distance))
1771                                 return 0;
1772                         /*
1773                          * Stop after the first non-trylock entry,
1774                          * as non-trylock entries have added their
1775                          * own direct dependencies already, so this
1776                          * lock is connected to them indirectly:
1777                          */
1778                         if (!hlock->trylock)
1779                                 break;
1780                 }
1781                 depth--;
1782                 /*
1783                  * End of lock-stack?
1784                  */
1785                 if (!depth)
1786                         break;
1787                 /*
1788                  * Stop the search if we cross into another context:
1789                  */
1790                 if (curr->held_locks[depth].irq_context !=
1791                                 curr->held_locks[depth-1].irq_context)
1792                         break;
1793         }
1794         return 1;
1795 out_bug:
1796         if (!debug_locks_off_graph_unlock())
1797                 return 0;
1798
1799         WARN_ON(1);
1800
1801         return 0;
1802 }
1803
1804 unsigned long nr_lock_chains;
1805 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1806 int nr_chain_hlocks;
1807 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1808
1809 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1810 {
1811         return lock_classes + chain_hlocks[chain->base + i];
1812 }
1813
1814 /*
1815  * Look up a dependency chain. If the key is not present yet then
1816  * add it and return 1 - in this case the new dependency chain is
1817  * validated. If the key is already hashed, return 0.
1818  * (On return with 1 graph_lock is held.)
1819  */
1820 static inline int lookup_chain_cache(struct task_struct *curr,
1821                                      struct held_lock *hlock,
1822                                      u64 chain_key)
1823 {
1824         struct lock_class *class = hlock_class(hlock);
1825         struct list_head *hash_head = chainhashentry(chain_key);
1826         struct lock_chain *chain;
1827         struct held_lock *hlock_curr, *hlock_next;
1828         int i, j, n, cn;
1829
1830         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1831                 return 0;
1832         /*
1833          * We can walk it lock-free, because entries only get added
1834          * to the hash:
1835          */
1836         list_for_each_entry(chain, hash_head, entry) {
1837                 if (chain->chain_key == chain_key) {
1838 cache_hit:
1839                         debug_atomic_inc(&chain_lookup_hits);
1840                         if (very_verbose(class))
1841                                 printk("\nhash chain already cached, key: "
1842                                         "%016Lx tail class: [%p] %s\n",
1843                                         (unsigned long long)chain_key,
1844                                         class->key, class->name);
1845                         return 0;
1846                 }
1847         }
1848         if (very_verbose(class))
1849                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1850                         (unsigned long long)chain_key, class->key, class->name);
1851         /*
1852          * Allocate a new chain entry from the static array, and add
1853          * it to the hash:
1854          */
1855         if (!graph_lock())
1856                 return 0;
1857         /*
1858          * We have to walk the chain again locked - to avoid duplicates:
1859          */
1860         list_for_each_entry(chain, hash_head, entry) {
1861                 if (chain->chain_key == chain_key) {
1862                         graph_unlock();
1863                         goto cache_hit;
1864                 }
1865         }
1866         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1867                 if (!debug_locks_off_graph_unlock())
1868                         return 0;
1869
1870                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1871                 printk("turning off the locking correctness validator.\n");
1872                 dump_stack();
1873                 return 0;
1874         }
1875         chain = lock_chains + nr_lock_chains++;
1876         chain->chain_key = chain_key;
1877         chain->irq_context = hlock->irq_context;
1878         /* Find the first held_lock of current chain */
1879         hlock_next = hlock;
1880         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1881                 hlock_curr = curr->held_locks + i;
1882                 if (hlock_curr->irq_context != hlock_next->irq_context)
1883                         break;
1884                 hlock_next = hlock;
1885         }
1886         i++;
1887         chain->depth = curr->lockdep_depth + 1 - i;
1888         cn = nr_chain_hlocks;
1889         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1890                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1891                 if (n == cn)
1892                         break;
1893                 cn = n;
1894         }
1895         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1896                 chain->base = cn;
1897                 for (j = 0; j < chain->depth - 1; j++, i++) {
1898                         int lock_id = curr->held_locks[i].class_idx - 1;
1899                         chain_hlocks[chain->base + j] = lock_id;
1900                 }
1901                 chain_hlocks[chain->base + j] = class - lock_classes;
1902         }
1903         list_add_tail_rcu(&chain->entry, hash_head);
1904         debug_atomic_inc(&chain_lookup_misses);
1905         inc_chains();
1906
1907         return 1;
1908 }
1909
1910 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1911                 struct held_lock *hlock, int chain_head, u64 chain_key)
1912 {
1913         /*
1914          * Trylock needs to maintain the stack of held locks, but it
1915          * does not add new dependencies, because trylock can be done
1916          * in any order.
1917          *
1918          * We look up the chain_key and do the O(N^2) check and update of
1919          * the dependencies only if this is a new dependency chain.
1920          * (If lookup_chain_cache() returns with 1 it acquires
1921          * graph_lock for us)
1922          */
1923         if (!hlock->trylock && (hlock->check == 2) &&
1924             lookup_chain_cache(curr, hlock, chain_key)) {
1925                 /*
1926                  * Check whether last held lock:
1927                  *
1928                  * - is irq-safe, if this lock is irq-unsafe
1929                  * - is softirq-safe, if this lock is hardirq-unsafe
1930                  *
1931                  * And check whether the new lock's dependency graph
1932                  * could lead back to the previous lock.
1933                  *
1934                  * any of these scenarios could lead to a deadlock. If
1935                  * All validations
1936                  */
1937                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1938
1939                 if (!ret)
1940                         return 0;
1941                 /*
1942                  * Mark recursive read, as we jump over it when
1943                  * building dependencies (just like we jump over
1944                  * trylock entries):
1945                  */
1946                 if (ret == 2)
1947                         hlock->read = 2;
1948                 /*
1949                  * Add dependency only if this lock is not the head
1950                  * of the chain, and if it's not a secondary read-lock:
1951                  */
1952                 if (!chain_head && ret != 2)
1953                         if (!check_prevs_add(curr, hlock))
1954                                 return 0;
1955                 graph_unlock();
1956         } else
1957                 /* after lookup_chain_cache(): */
1958                 if (unlikely(!debug_locks))
1959                         return 0;
1960
1961         return 1;
1962 }
1963 #else
1964 static inline int validate_chain(struct task_struct *curr,
1965                 struct lockdep_map *lock, struct held_lock *hlock,
1966                 int chain_head, u64 chain_key)
1967 {
1968         return 1;
1969 }
1970 #endif
1971
1972 /*
1973  * We are building curr_chain_key incrementally, so double-check
1974  * it from scratch, to make sure that it's done correctly:
1975  */
1976 static void check_chain_key(struct task_struct *curr)
1977 {
1978 #ifdef CONFIG_DEBUG_LOCKDEP
1979         struct held_lock *hlock, *prev_hlock = NULL;
1980         unsigned int i, id;
1981         u64 chain_key = 0;
1982
1983         for (i = 0; i < curr->lockdep_depth; i++) {
1984                 hlock = curr->held_locks + i;
1985                 if (chain_key != hlock->prev_chain_key) {
1986                         debug_locks_off();
1987                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1988                                 curr->lockdep_depth, i,
1989                                 (unsigned long long)chain_key,
1990                                 (unsigned long long)hlock->prev_chain_key);
1991                         return;
1992                 }
1993                 id = hlock->class_idx - 1;
1994                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1995                         return;
1996
1997                 if (prev_hlock && (prev_hlock->irq_context !=
1998                                                         hlock->irq_context))
1999                         chain_key = 0;
2000                 chain_key = iterate_chain_key(chain_key, id);
2001                 prev_hlock = hlock;
2002         }
2003         if (chain_key != curr->curr_chain_key) {
2004                 debug_locks_off();
2005                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2006                         curr->lockdep_depth, i,
2007                         (unsigned long long)chain_key,
2008                         (unsigned long long)curr->curr_chain_key);
2009         }
2010 #endif
2011 }
2012
2013 static int
2014 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2015                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2016 {
2017         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2018                 return 0;
2019
2020         printk("\n=================================\n");
2021         printk(  "[ INFO: inconsistent lock state ]\n");
2022         print_kernel_version();
2023         printk(  "---------------------------------\n");
2024
2025         printk("inconsistent {%s} -> {%s} usage.\n",
2026                 usage_str[prev_bit], usage_str[new_bit]);
2027
2028         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2029                 curr->comm, task_pid_nr(curr),
2030                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2031                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2032                 trace_hardirqs_enabled(curr),
2033                 trace_softirqs_enabled(curr));
2034         print_lock(this);
2035
2036         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2037         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2038
2039         print_irqtrace_events(curr);
2040         printk("\nother info that might help us debug this:\n");
2041         lockdep_print_held_locks(curr);
2042
2043         printk("\nstack backtrace:\n");
2044         dump_stack();
2045
2046         return 0;
2047 }
2048
2049 /*
2050  * Print out an error if an invalid bit is set:
2051  */
2052 static inline int
2053 valid_state(struct task_struct *curr, struct held_lock *this,
2054             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2055 {
2056         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2057                 return print_usage_bug(curr, this, bad_bit, new_bit);
2058         return 1;
2059 }
2060
2061 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2062                      enum lock_usage_bit new_bit);
2063
2064 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2065
2066 /*
2067  * print irq inversion bug:
2068  */
2069 static int
2070 print_irq_inversion_bug(struct task_struct *curr,
2071                         struct lock_list *root, struct lock_list *other,
2072                         struct held_lock *this, int forwards,
2073                         const char *irqclass)
2074 {
2075         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2076                 return 0;
2077
2078         printk("\n=========================================================\n");
2079         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2080         print_kernel_version();
2081         printk(  "---------------------------------------------------------\n");
2082         printk("%s/%d just changed the state of lock:\n",
2083                 curr->comm, task_pid_nr(curr));
2084         print_lock(this);
2085         if (forwards)
2086                 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2087         else
2088                 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2089         print_lock_name(other->class);
2090         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2091
2092         printk("\nother info that might help us debug this:\n");
2093         lockdep_print_held_locks(curr);
2094
2095         printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2096         if (!save_trace(&root->trace))
2097                 return 0;
2098         print_shortest_lock_dependencies(other, root);
2099
2100         printk("\nstack backtrace:\n");
2101         dump_stack();
2102
2103         return 0;
2104 }
2105
2106 /*
2107  * Prove that in the forwards-direction subgraph starting at <this>
2108  * there is no lock matching <mask>:
2109  */
2110 static int
2111 check_usage_forwards(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_forwards(&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, 1, irqclass);
2128 }
2129
2130 /*
2131  * Prove that in the backwards-direction subgraph starting at <this>
2132  * there is no lock matching <mask>:
2133  */
2134 static int
2135 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2136                       enum lock_usage_bit bit, const char *irqclass)
2137 {
2138         int ret;
2139         struct lock_list root;
2140         struct lock_list *uninitialized_var(target_entry);
2141
2142         root.parent = NULL;
2143         root.class = hlock_class(this);
2144         ret = find_usage_backwards(&root, bit, &target_entry);
2145         if (ret < 0)
2146                 return print_bfs_bug(ret);
2147         if (ret == 1)
2148                 return ret;
2149
2150         return print_irq_inversion_bug(curr, &root, target_entry,
2151                                         this, 0, irqclass);
2152 }
2153
2154 void print_irqtrace_events(struct task_struct *curr)
2155 {
2156         printk("irq event stamp: %u\n", curr->irq_events);
2157         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2158         print_ip_sym(curr->hardirq_enable_ip);
2159         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2160         print_ip_sym(curr->hardirq_disable_ip);
2161         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2162         print_ip_sym(curr->softirq_enable_ip);
2163         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2164         print_ip_sym(curr->softirq_disable_ip);
2165 }
2166
2167 static int HARDIRQ_verbose(struct lock_class *class)
2168 {
2169 #if HARDIRQ_VERBOSE
2170         return class_filter(class);
2171 #endif
2172         return 0;
2173 }
2174
2175 static int SOFTIRQ_verbose(struct lock_class *class)
2176 {
2177 #if SOFTIRQ_VERBOSE
2178         return class_filter(class);
2179 #endif
2180         return 0;
2181 }
2182
2183 static int RECLAIM_FS_verbose(struct lock_class *class)
2184 {
2185 #if RECLAIM_VERBOSE
2186         return class_filter(class);
2187 #endif
2188         return 0;
2189 }
2190
2191 #define STRICT_READ_CHECKS      1
2192
2193 static int (*state_verbose_f[])(struct lock_class *class) = {
2194 #define LOCKDEP_STATE(__STATE) \
2195         __STATE##_verbose,
2196 #include "lockdep_states.h"
2197 #undef LOCKDEP_STATE
2198 };
2199
2200 static inline int state_verbose(enum lock_usage_bit bit,
2201                                 struct lock_class *class)
2202 {
2203         return state_verbose_f[bit >> 2](class);
2204 }
2205
2206 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2207                              enum lock_usage_bit bit, const char *name);
2208
2209 static int
2210 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2211                 enum lock_usage_bit new_bit)
2212 {
2213         int excl_bit = exclusive_bit(new_bit);
2214         int read = new_bit & 1;
2215         int dir = new_bit & 2;
2216
2217         /*
2218          * mark USED_IN has to look forwards -- to ensure no dependency
2219          * has ENABLED state, which would allow recursion deadlocks.
2220          *
2221          * mark ENABLED has to look backwards -- to ensure no dependee
2222          * has USED_IN state, which, again, would allow  recursion deadlocks.
2223          */
2224         check_usage_f usage = dir ?
2225                 check_usage_backwards : check_usage_forwards;
2226
2227         /*
2228          * Validate that this particular lock does not have conflicting
2229          * usage states.
2230          */
2231         if (!valid_state(curr, this, new_bit, excl_bit))
2232                 return 0;
2233
2234         /*
2235          * Validate that the lock dependencies don't have conflicting usage
2236          * states.
2237          */
2238         if ((!read || !dir || STRICT_READ_CHECKS) &&
2239                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2240                 return 0;
2241
2242         /*
2243          * Check for read in write conflicts
2244          */
2245         if (!read) {
2246                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2247                         return 0;
2248
2249                 if (STRICT_READ_CHECKS &&
2250                         !usage(curr, this, excl_bit + 1,
2251                                 state_name(new_bit + 1)))
2252                         return 0;
2253         }
2254
2255         if (state_verbose(new_bit, hlock_class(this)))
2256                 return 2;
2257
2258         return 1;
2259 }
2260
2261 enum mark_type {
2262 #define LOCKDEP_STATE(__STATE)  __STATE,
2263 #include "lockdep_states.h"
2264 #undef LOCKDEP_STATE
2265 };
2266
2267 /*
2268  * Mark all held locks with a usage bit:
2269  */
2270 static int
2271 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2272 {
2273         enum lock_usage_bit usage_bit;
2274         struct held_lock *hlock;
2275         int i;
2276
2277         for (i = 0; i < curr->lockdep_depth; i++) {
2278                 hlock = curr->held_locks + i;
2279
2280                 usage_bit = 2 + (mark << 2); /* ENABLED */
2281                 if (hlock->read)
2282                         usage_bit += 1; /* READ */
2283
2284                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2285
2286                 if (!mark_lock(curr, hlock, usage_bit))
2287                         return 0;
2288         }
2289
2290         return 1;
2291 }
2292
2293 /*
2294  * Debugging helper: via this flag we know that we are in
2295  * 'early bootup code', and will warn about any invalid irqs-on event:
2296  */
2297 static int early_boot_irqs_enabled;
2298
2299 void early_boot_irqs_off(void)
2300 {
2301         early_boot_irqs_enabled = 0;
2302 }
2303
2304 void early_boot_irqs_on(void)
2305 {
2306         early_boot_irqs_enabled = 1;
2307 }
2308
2309 /*
2310  * Hardirqs will be enabled:
2311  */
2312 void trace_hardirqs_on_caller(unsigned long ip)
2313 {
2314         struct task_struct *curr = current;
2315
2316         time_hardirqs_on(CALLER_ADDR0, ip);
2317
2318         if (unlikely(!debug_locks || current->lockdep_recursion))
2319                 return;
2320
2321         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2322                 return;
2323
2324         if (unlikely(curr->hardirqs_enabled)) {
2325                 debug_atomic_inc(&redundant_hardirqs_on);
2326                 return;
2327         }
2328         /* we'll do an OFF -> ON transition: */
2329         curr->hardirqs_enabled = 1;
2330
2331         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2332                 return;
2333         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2334                 return;
2335         /*
2336          * We are going to turn hardirqs on, so set the
2337          * usage bit for all held locks:
2338          */
2339         if (!mark_held_locks(curr, HARDIRQ))
2340                 return;
2341         /*
2342          * If we have softirqs enabled, then set the usage
2343          * bit for all held locks. (disabled hardirqs prevented
2344          * this bit from being set before)
2345          */
2346         if (curr->softirqs_enabled)
2347                 if (!mark_held_locks(curr, SOFTIRQ))
2348                         return;
2349
2350         curr->hardirq_enable_ip = ip;
2351         curr->hardirq_enable_event = ++curr->irq_events;
2352         debug_atomic_inc(&hardirqs_on_events);
2353 }
2354 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2355
2356 void trace_hardirqs_on(void)
2357 {
2358         trace_hardirqs_on_caller(CALLER_ADDR0);
2359 }
2360 EXPORT_SYMBOL(trace_hardirqs_on);
2361
2362 /*
2363  * Hardirqs were disabled:
2364  */
2365 void trace_hardirqs_off_caller(unsigned long ip)
2366 {
2367         struct task_struct *curr = current;
2368
2369         time_hardirqs_off(CALLER_ADDR0, ip);
2370
2371         if (unlikely(!debug_locks || current->lockdep_recursion))
2372                 return;
2373
2374         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2375                 return;
2376
2377         if (curr->hardirqs_enabled) {
2378                 /*
2379                  * We have done an ON -> OFF transition:
2380                  */
2381                 curr->hardirqs_enabled = 0;
2382                 curr->hardirq_disable_ip = ip;
2383                 curr->hardirq_disable_event = ++curr->irq_events;
2384                 debug_atomic_inc(&hardirqs_off_events);
2385         } else
2386                 debug_atomic_inc(&redundant_hardirqs_off);
2387 }
2388 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2389
2390 void trace_hardirqs_off(void)
2391 {
2392         trace_hardirqs_off_caller(CALLER_ADDR0);
2393 }
2394 EXPORT_SYMBOL(trace_hardirqs_off);
2395
2396 /*
2397  * Softirqs will be enabled:
2398  */
2399 void trace_softirqs_on(unsigned long ip)
2400 {
2401         struct task_struct *curr = current;
2402
2403         if (unlikely(!debug_locks))
2404                 return;
2405
2406         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2407                 return;
2408
2409         if (curr->softirqs_enabled) {
2410                 debug_atomic_inc(&redundant_softirqs_on);
2411                 return;
2412         }
2413
2414         /*
2415          * We'll do an OFF -> ON transition:
2416          */
2417         curr->softirqs_enabled = 1;
2418         curr->softirq_enable_ip = ip;
2419         curr->softirq_enable_event = ++curr->irq_events;
2420         debug_atomic_inc(&softirqs_on_events);
2421         /*
2422          * We are going to turn softirqs on, so set the
2423          * usage bit for all held locks, if hardirqs are
2424          * enabled too:
2425          */
2426         if (curr->hardirqs_enabled)
2427                 mark_held_locks(curr, SOFTIRQ);
2428 }
2429
2430 /*
2431  * Softirqs were disabled:
2432  */
2433 void trace_softirqs_off(unsigned long ip)
2434 {
2435         struct task_struct *curr = current;
2436
2437         if (unlikely(!debug_locks))
2438                 return;
2439
2440         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2441                 return;
2442
2443         if (curr->softirqs_enabled) {
2444                 /*
2445                  * We have done an ON -> OFF transition:
2446                  */
2447                 curr->softirqs_enabled = 0;
2448                 curr->softirq_disable_ip = ip;
2449                 curr->softirq_disable_event = ++curr->irq_events;
2450                 debug_atomic_inc(&softirqs_off_events);
2451                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2452         } else
2453                 debug_atomic_inc(&redundant_softirqs_off);
2454 }
2455
2456 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2457 {
2458         struct task_struct *curr = current;
2459
2460         if (unlikely(!debug_locks))
2461                 return;
2462
2463         /* no reclaim without waiting on it */
2464         if (!(gfp_mask & __GFP_WAIT))
2465                 return;
2466
2467         /* this guy won't enter reclaim */
2468         if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2469                 return;
2470
2471         /* We're only interested __GFP_FS allocations for now */
2472         if (!(gfp_mask & __GFP_FS))
2473                 return;
2474
2475         if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2476                 return;
2477
2478         mark_held_locks(curr, RECLAIM_FS);
2479 }
2480
2481 static void check_flags(unsigned long flags);
2482
2483 void lockdep_trace_alloc(gfp_t gfp_mask)
2484 {
2485         unsigned long flags;
2486
2487         if (unlikely(current->lockdep_recursion))
2488                 return;
2489
2490         raw_local_irq_save(flags);
2491         check_flags(flags);
2492         current->lockdep_recursion = 1;
2493         __lockdep_trace_alloc(gfp_mask, flags);
2494         current->lockdep_recursion = 0;
2495         raw_local_irq_restore(flags);
2496 }
2497
2498 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2499 {
2500         /*
2501          * If non-trylock use in a hardirq or softirq context, then
2502          * mark the lock as used in these contexts:
2503          */
2504         if (!hlock->trylock) {
2505                 if (hlock->read) {
2506                         if (curr->hardirq_context)
2507                                 if (!mark_lock(curr, hlock,
2508                                                 LOCK_USED_IN_HARDIRQ_READ))
2509                                         return 0;
2510                         if (curr->softirq_context)
2511                                 if (!mark_lock(curr, hlock,
2512                                                 LOCK_USED_IN_SOFTIRQ_READ))
2513                                         return 0;
2514                 } else {
2515                         if (curr->hardirq_context)
2516                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2517                                         return 0;
2518                         if (curr->softirq_context)
2519                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2520                                         return 0;
2521                 }
2522         }
2523         if (!hlock->hardirqs_off) {
2524                 if (hlock->read) {
2525                         if (!mark_lock(curr, hlock,
2526                                         LOCK_ENABLED_HARDIRQ_READ))
2527                                 return 0;
2528                         if (curr->softirqs_enabled)
2529                                 if (!mark_lock(curr, hlock,
2530                                                 LOCK_ENABLED_SOFTIRQ_READ))
2531                                         return 0;
2532                 } else {
2533                         if (!mark_lock(curr, hlock,
2534                                         LOCK_ENABLED_HARDIRQ))
2535                                 return 0;
2536                         if (curr->softirqs_enabled)
2537                                 if (!mark_lock(curr, hlock,
2538                                                 LOCK_ENABLED_SOFTIRQ))
2539                                         return 0;
2540                 }
2541         }
2542
2543         /*
2544          * We reuse the irq context infrastructure more broadly as a general
2545          * context checking code. This tests GFP_FS recursion (a lock taken
2546          * during reclaim for a GFP_FS allocation is held over a GFP_FS
2547          * allocation).
2548          */
2549         if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2550                 if (hlock->read) {
2551                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2552                                         return 0;
2553                 } else {
2554                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2555                                         return 0;
2556                 }
2557         }
2558
2559         return 1;
2560 }
2561
2562 static int separate_irq_context(struct task_struct *curr,
2563                 struct held_lock *hlock)
2564 {
2565         unsigned int depth = curr->lockdep_depth;
2566
2567         /*
2568          * Keep track of points where we cross into an interrupt context:
2569          */
2570         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2571                                 curr->softirq_context;
2572         if (depth) {
2573                 struct held_lock *prev_hlock;
2574
2575                 prev_hlock = curr->held_locks + depth-1;
2576                 /*
2577                  * If we cross into another context, reset the
2578                  * hash key (this also prevents the checking and the
2579                  * adding of the dependency to 'prev'):
2580                  */
2581                 if (prev_hlock->irq_context != hlock->irq_context)
2582                         return 1;
2583         }
2584         return 0;
2585 }
2586
2587 #else
2588
2589 static inline
2590 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2591                 enum lock_usage_bit new_bit)
2592 {
2593         WARN_ON(1);
2594         return 1;
2595 }
2596
2597 static inline int mark_irqflags(struct task_struct *curr,
2598                 struct held_lock *hlock)
2599 {
2600         return 1;
2601 }
2602
2603 static inline int separate_irq_context(struct task_struct *curr,
2604                 struct held_lock *hlock)
2605 {
2606         return 0;
2607 }
2608
2609 void lockdep_trace_alloc(gfp_t gfp_mask)
2610 {
2611 }
2612
2613 #endif
2614
2615 /*
2616  * Mark a lock with a usage bit, and validate the state transition:
2617  */
2618 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2619                              enum lock_usage_bit new_bit)
2620 {
2621         unsigned int new_mask = 1 << new_bit, ret = 1;
2622
2623         /*
2624          * If already set then do not dirty the cacheline,
2625          * nor do any checks:
2626          */
2627         if (likely(hlock_class(this)->usage_mask & new_mask))
2628                 return 1;
2629
2630         if (!graph_lock())
2631                 return 0;
2632         /*
2633          * Make sure we didnt race:
2634          */
2635         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2636                 graph_unlock();
2637                 return 1;
2638         }
2639
2640         hlock_class(this)->usage_mask |= new_mask;
2641
2642         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2643                 return 0;
2644
2645         switch (new_bit) {
2646 #define LOCKDEP_STATE(__STATE)                  \
2647         case LOCK_USED_IN_##__STATE:            \
2648         case LOCK_USED_IN_##__STATE##_READ:     \
2649         case LOCK_ENABLED_##__STATE:            \
2650         case LOCK_ENABLED_##__STATE##_READ:
2651 #include "lockdep_states.h"
2652 #undef LOCKDEP_STATE
2653                 ret = mark_lock_irq(curr, this, new_bit);
2654                 if (!ret)
2655                         return 0;
2656                 break;
2657         case LOCK_USED:
2658                 debug_atomic_dec(&nr_unused_locks);
2659                 break;
2660         default:
2661                 if (!debug_locks_off_graph_unlock())
2662                         return 0;
2663                 WARN_ON(1);
2664                 return 0;
2665         }
2666
2667         graph_unlock();
2668
2669         /*
2670          * We must printk outside of the graph_lock:
2671          */
2672         if (ret == 2) {
2673                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2674                 print_lock(this);
2675                 print_irqtrace_events(curr);
2676                 dump_stack();
2677         }
2678
2679         return ret;
2680 }
2681
2682 /*
2683  * Initialize a lock instance's lock-class mapping info:
2684  */
2685 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2686                       struct lock_class_key *key, int subclass)
2687 {
2688         lock->class_cache = NULL;
2689 #ifdef CONFIG_LOCK_STAT
2690         lock->cpu = raw_smp_processor_id();
2691 #endif
2692
2693         if (DEBUG_LOCKS_WARN_ON(!name)) {
2694                 lock->name = "NULL";
2695                 return;
2696         }
2697
2698         lock->name = name;
2699
2700         if (DEBUG_LOCKS_WARN_ON(!key))
2701                 return;
2702         /*
2703          * Sanity check, the lock-class key must be persistent:
2704          */
2705         if (!static_obj(key)) {
2706                 printk("BUG: key %p not in .data!\n", key);
2707                 DEBUG_LOCKS_WARN_ON(1);
2708                 return;
2709         }
2710         lock->key = key;
2711
2712         if (unlikely(!debug_locks))
2713                 return;
2714
2715         if (subclass)
2716                 register_lock_class(lock, subclass, 1);
2717 }
2718 EXPORT_SYMBOL_GPL(lockdep_init_map);
2719
2720 /*
2721  * This gets called for every mutex_lock*()/spin_lock*() operation.
2722  * We maintain the dependency maps and validate the locking attempt:
2723  */
2724 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2725                           int trylock, int read, int check, int hardirqs_off,
2726                           struct lockdep_map *nest_lock, unsigned long ip,
2727                           int references)
2728 {
2729         struct task_struct *curr = current;
2730         struct lock_class *class = NULL;
2731         struct held_lock *hlock;
2732         unsigned int depth, id;
2733         int chain_head = 0;
2734         int class_idx;
2735         u64 chain_key;
2736
2737         if (!prove_locking)
2738                 check = 1;
2739
2740         if (unlikely(!debug_locks))
2741                 return 0;
2742
2743         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2744                 return 0;
2745
2746         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2747                 debug_locks_off();
2748                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2749                 printk("turning off the locking correctness validator.\n");
2750                 dump_stack();
2751                 return 0;
2752         }
2753
2754         if (!subclass)
2755                 class = lock->class_cache;
2756         /*
2757          * Not cached yet or subclass?
2758          */
2759         if (unlikely(!class)) {
2760                 class = register_lock_class(lock, subclass, 0);
2761                 if (!class)
2762                         return 0;
2763         }
2764         debug_atomic_inc((atomic_t *)&class->ops);
2765         if (very_verbose(class)) {
2766                 printk("\nacquire class [%p] %s", class->key, class->name);
2767                 if (class->name_version > 1)
2768                         printk("#%d", class->name_version);
2769                 printk("\n");
2770                 dump_stack();
2771         }
2772
2773         /*
2774          * Add the lock to the list of currently held locks.
2775          * (we dont increase the depth just yet, up until the
2776          * dependency checks are done)
2777          */
2778         depth = curr->lockdep_depth;
2779         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2780                 return 0;
2781
2782         class_idx = class - lock_classes + 1;
2783
2784         if (depth) {
2785                 hlock = curr->held_locks + depth - 1;
2786                 if (hlock->class_idx == class_idx && nest_lock) {
2787                         if (hlock->references)
2788                                 hlock->references++;
2789                         else
2790                                 hlock->references = 2;
2791
2792                         return 1;
2793                 }
2794         }
2795
2796         hlock = curr->held_locks + depth;
2797         if (DEBUG_LOCKS_WARN_ON(!class))
2798                 return 0;
2799         hlock->class_idx = class_idx;
2800         hlock->acquire_ip = ip;
2801         hlock->instance = lock;
2802         hlock->nest_lock = nest_lock;
2803         hlock->trylock = trylock;
2804         hlock->read = read;
2805         hlock->check = check;
2806         hlock->hardirqs_off = !!hardirqs_off;
2807         hlock->references = references;
2808 #ifdef CONFIG_LOCK_STAT
2809         hlock->waittime_stamp = 0;
2810         hlock->holdtime_stamp = lockstat_clock();
2811 #endif
2812
2813         if (check == 2 && !mark_irqflags(curr, hlock))
2814                 return 0;
2815
2816         /* mark it as used: */
2817         if (!mark_lock(curr, hlock, LOCK_USED))
2818                 return 0;
2819
2820         /*
2821          * Calculate the chain hash: it's the combined hash of all the
2822          * lock keys along the dependency chain. We save the hash value
2823          * at every step so that we can get the current hash easily
2824          * after unlock. The chain hash is then used to cache dependency
2825          * results.
2826          *
2827          * The 'key ID' is what is the most compact key value to drive
2828          * the hash, not class->key.
2829          */
2830         id = class - lock_classes;
2831         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2832                 return 0;
2833
2834         chain_key = curr->curr_chain_key;
2835         if (!depth) {
2836                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2837                         return 0;
2838                 chain_head = 1;
2839         }
2840
2841         hlock->prev_chain_key = chain_key;
2842         if (separate_irq_context(curr, hlock)) {
2843                 chain_key = 0;
2844                 chain_head = 1;
2845         }
2846         chain_key = iterate_chain_key(chain_key, id);
2847
2848         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2849                 return 0;
2850
2851         curr->curr_chain_key = chain_key;
2852         curr->lockdep_depth++;
2853         check_chain_key(curr);
2854 #ifdef CONFIG_DEBUG_LOCKDEP
2855         if (unlikely(!debug_locks))
2856                 return 0;
2857 #endif
2858         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2859                 debug_locks_off();
2860                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2861                 printk("turning off the locking correctness validator.\n");
2862                 dump_stack();
2863                 return 0;
2864         }
2865
2866         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2867                 max_lockdep_depth = curr->lockdep_depth;
2868
2869         return 1;
2870 }
2871
2872 static int
2873 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2874                            unsigned long ip)
2875 {
2876         if (!debug_locks_off())
2877                 return 0;
2878         if (debug_locks_silent)
2879                 return 0;
2880
2881         printk("\n=====================================\n");
2882         printk(  "[ BUG: bad unlock balance detected! ]\n");
2883         printk(  "-------------------------------------\n");
2884         printk("%s/%d is trying to release lock (",
2885                 curr->comm, task_pid_nr(curr));
2886         print_lockdep_cache(lock);
2887         printk(") at:\n");
2888         print_ip_sym(ip);
2889         printk("but there are no more locks to release!\n");
2890         printk("\nother info that might help us debug this:\n");
2891         lockdep_print_held_locks(curr);
2892
2893         printk("\nstack backtrace:\n");
2894         dump_stack();
2895
2896         return 0;
2897 }
2898
2899 /*
2900  * Common debugging checks for both nested and non-nested unlock:
2901  */
2902 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2903                         unsigned long ip)
2904 {
2905         if (unlikely(!debug_locks))
2906                 return 0;
2907         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2908                 return 0;
2909
2910         if (curr->lockdep_depth <= 0)
2911                 return print_unlock_inbalance_bug(curr, lock, ip);
2912
2913         return 1;
2914 }
2915
2916 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
2917 {
2918         if (hlock->instance == lock)
2919                 return 1;
2920
2921         if (hlock->references) {
2922                 struct lock_class *class = lock->class_cache;
2923
2924                 if (!class)
2925                         class = look_up_lock_class(lock, 0);
2926
2927                 if (DEBUG_LOCKS_WARN_ON(!class))
2928                         return 0;
2929
2930                 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
2931                         return 0;
2932
2933                 if (hlock->class_idx == class - lock_classes + 1)
2934                         return 1;
2935         }
2936
2937         return 0;
2938 }
2939
2940 static int
2941 __lock_set_class(struct lockdep_map *lock, const char *name,
2942                  struct lock_class_key *key, unsigned int subclass,
2943                  unsigned long ip)
2944 {
2945         struct task_struct *curr = current;
2946         struct held_lock *hlock, *prev_hlock;
2947         struct lock_class *class;
2948         unsigned int depth;
2949         int i;
2950
2951         depth = curr->lockdep_depth;
2952         if (DEBUG_LOCKS_WARN_ON(!depth))
2953                 return 0;
2954
2955         prev_hlock = NULL;
2956         for (i = depth-1; i >= 0; i--) {
2957                 hlock = curr->held_locks + i;
2958                 /*
2959                  * We must not cross into another context:
2960                  */
2961                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2962                         break;
2963                 if (match_held_lock(hlock, lock))
2964                         goto found_it;
2965                 prev_hlock = hlock;
2966         }
2967         return print_unlock_inbalance_bug(curr, lock, ip);
2968
2969 found_it:
2970         lockdep_init_map(lock, name, key, 0);
2971         class = register_lock_class(lock, subclass, 0);
2972         hlock->class_idx = class - lock_classes + 1;
2973
2974         curr->lockdep_depth = i;
2975         curr->curr_chain_key = hlock->prev_chain_key;
2976
2977         for (; i < depth; i++) {
2978                 hlock = curr->held_locks + i;
2979                 if (!__lock_acquire(hlock->instance,
2980                         hlock_class(hlock)->subclass, hlock->trylock,
2981                                 hlock->read, hlock->check, hlock->hardirqs_off,
2982                                 hlock->nest_lock, hlock->acquire_ip,
2983                                 hlock->references))
2984                         return 0;
2985         }
2986
2987         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2988                 return 0;
2989         return 1;
2990 }
2991
2992 /*
2993  * Remove the lock to the list of currently held locks in a
2994  * potentially non-nested (out of order) manner. This is a
2995  * relatively rare operation, as all the unlock APIs default
2996  * to nested mode (which uses lock_release()):
2997  */
2998 static int
2999 lock_release_non_nested(struct task_struct *curr,
3000                         struct lockdep_map *lock, unsigned long ip)
3001 {
3002         struct held_lock *hlock, *prev_hlock;
3003         unsigned int depth;
3004         int i;
3005
3006         /*
3007          * Check whether the lock exists in the current stack
3008          * of held locks:
3009          */
3010         depth = curr->lockdep_depth;
3011         if (DEBUG_LOCKS_WARN_ON(!depth))
3012                 return 0;
3013
3014         prev_hlock = NULL;
3015         for (i = depth-1; i >= 0; i--) {
3016                 hlock = curr->held_locks + i;
3017                 /*
3018                  * We must not cross into another context:
3019                  */
3020                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3021                         break;
3022                 if (match_held_lock(hlock, lock))
3023                         goto found_it;
3024                 prev_hlock = hlock;
3025         }
3026         return print_unlock_inbalance_bug(curr, lock, ip);
3027
3028 found_it:
3029         if (hlock->instance == lock)
3030                 lock_release_holdtime(hlock);
3031
3032         if (hlock->references) {
3033                 hlock->references--;
3034                 if (hlock->references) {
3035                         /*
3036                          * We had, and after removing one, still have
3037                          * references, the current lock stack is still
3038                          * valid. We're done!
3039                          */
3040                         return 1;
3041                 }
3042         }
3043
3044         /*
3045          * We have the right lock to unlock, 'hlock' points to it.
3046          * Now we remove it from the stack, and add back the other
3047          * entries (if any), recalculating the hash along the way:
3048          */
3049
3050         curr->lockdep_depth = i;
3051         curr->curr_chain_key = hlock->prev_chain_key;
3052
3053         for (i++; i < depth; i++) {
3054                 hlock = curr->held_locks + i;
3055                 if (!__lock_acquire(hlock->instance,
3056                         hlock_class(hlock)->subclass, hlock->trylock,
3057                                 hlock->read, hlock->check, hlock->hardirqs_off,
3058                                 hlock->nest_lock, hlock->acquire_ip,
3059                                 hlock->references))
3060                         return 0;
3061         }
3062
3063         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3064                 return 0;
3065         return 1;
3066 }
3067
3068 /*
3069  * Remove the lock to the list of currently held locks - this gets
3070  * called on mutex_unlock()/spin_unlock*() (or on a failed
3071  * mutex_lock_interruptible()). This is done for unlocks that nest
3072  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3073  */
3074 static int lock_release_nested(struct task_struct *curr,
3075                                struct lockdep_map *lock, unsigned long ip)
3076 {
3077         struct held_lock *hlock;
3078         unsigned int depth;
3079
3080         /*
3081          * Pop off the top of the lock stack:
3082          */
3083         depth = curr->lockdep_depth - 1;
3084         hlock = curr->held_locks + depth;
3085
3086         /*
3087          * Is the unlock non-nested:
3088          */
3089         if (hlock->instance != lock || hlock->references)
3090                 return lock_release_non_nested(curr, lock, ip);
3091         curr->lockdep_depth--;
3092
3093         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3094                 return 0;
3095
3096         curr->curr_chain_key = hlock->prev_chain_key;
3097
3098         lock_release_holdtime(hlock);
3099
3100 #ifdef CONFIG_DEBUG_LOCKDEP
3101         hlock->prev_chain_key = 0;
3102         hlock->class_idx = 0;
3103         hlock->acquire_ip = 0;
3104         hlock->irq_context = 0;
3105 #endif
3106         return 1;
3107 }
3108
3109 /*
3110  * Remove the lock to the list of currently held locks - this gets
3111  * called on mutex_unlock()/spin_unlock*() (or on a failed
3112  * mutex_lock_interruptible()). This is done for unlocks that nest
3113  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3114  */
3115 static void
3116 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3117 {
3118         struct task_struct *curr = current;
3119
3120         if (!check_unlock(curr, lock, ip))
3121                 return;
3122
3123         if (nested) {
3124                 if (!lock_release_nested(curr, lock, ip))
3125                         return;
3126         } else {
3127                 if (!lock_release_non_nested(curr, lock, ip))
3128                         return;
3129         }
3130
3131         check_chain_key(curr);
3132 }
3133
3134 static int __lock_is_held(struct lockdep_map *lock)
3135 {
3136         struct task_struct *curr = current;
3137         int i;
3138
3139         for (i = 0; i < curr->lockdep_depth; i++) {
3140                 struct held_lock *hlock = curr->held_locks + i;
3141
3142                 if (match_held_lock(hlock, lock))
3143                         return 1;
3144         }
3145
3146         return 0;
3147 }
3148
3149 /*
3150  * Check whether we follow the irq-flags state precisely:
3151  */
3152 static void check_flags(unsigned long flags)
3153 {
3154 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3155     defined(CONFIG_TRACE_IRQFLAGS)
3156         if (!debug_locks)
3157                 return;
3158
3159         if (irqs_disabled_flags(flags)) {
3160                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3161                         printk("possible reason: unannotated irqs-off.\n");
3162                 }
3163         } else {
3164                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3165                         printk("possible reason: unannotated irqs-on.\n");
3166                 }
3167         }
3168
3169         /*
3170          * We dont accurately track softirq state in e.g.
3171          * hardirq contexts (such as on 4KSTACKS), so only
3172          * check if not in hardirq contexts:
3173          */
3174         if (!hardirq_count()) {
3175                 if (softirq_count())
3176                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3177                 else
3178                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3179         }
3180
3181         if (!debug_locks)
3182                 print_irqtrace_events(current);
3183 #endif
3184 }
3185
3186 void lock_set_class(struct lockdep_map *lock, const char *name,
3187                     struct lock_class_key *key, unsigned int subclass,
3188                     unsigned long ip)
3189 {
3190         unsigned long flags;
3191
3192         if (unlikely(current->lockdep_recursion))
3193                 return;
3194
3195         raw_local_irq_save(flags);
3196         current->lockdep_recursion = 1;
3197         check_flags(flags);
3198         if (__lock_set_class(lock, name, key, subclass, ip))
3199                 check_chain_key(current);
3200         current->lockdep_recursion = 0;
3201         raw_local_irq_restore(flags);
3202 }
3203 EXPORT_SYMBOL_GPL(lock_set_class);
3204
3205 /*
3206  * We are not always called with irqs disabled - do that here,
3207  * and also avoid lockdep recursion:
3208  */
3209 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3210                           int trylock, int read, int check,
3211                           struct lockdep_map *nest_lock, unsigned long ip)
3212 {
3213         unsigned long flags;
3214
3215         if (unlikely(current->lockdep_recursion))
3216                 return;
3217
3218         raw_local_irq_save(flags);
3219         check_flags(flags);
3220
3221         current->lockdep_recursion = 1;
3222         trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3223         __lock_acquire(lock, subclass, trylock, read, check,
3224                        irqs_disabled_flags(flags), nest_lock, ip, 0);
3225         current->lockdep_recursion = 0;
3226         raw_local_irq_restore(flags);
3227 }
3228 EXPORT_SYMBOL_GPL(lock_acquire);
3229
3230 void lock_release(struct lockdep_map *lock, int nested,
3231                           unsigned long ip)
3232 {
3233         unsigned long flags;
3234
3235         if (unlikely(current->lockdep_recursion))
3236                 return;
3237
3238         raw_local_irq_save(flags);
3239         check_flags(flags);
3240         current->lockdep_recursion = 1;
3241         trace_lock_release(lock, nested, ip);
3242         __lock_release(lock, nested, ip);
3243         current->lockdep_recursion = 0;
3244         raw_local_irq_restore(flags);
3245 }
3246 EXPORT_SYMBOL_GPL(lock_release);
3247
3248 int lock_is_held(struct lockdep_map *lock)
3249 {
3250         unsigned long flags;
3251         int ret = 0;
3252
3253         if (unlikely(current->lockdep_recursion))
3254                 return ret;
3255
3256         raw_local_irq_save(flags);
3257         check_flags(flags);
3258
3259         current->lockdep_recursion = 1;
3260         ret = __lock_is_held(lock);
3261         current->lockdep_recursion = 0;
3262         raw_local_irq_restore(flags);
3263
3264         return ret;
3265 }
3266 EXPORT_SYMBOL_GPL(lock_is_held);
3267
3268 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3269 {
3270         current->lockdep_reclaim_gfp = gfp_mask;
3271 }
3272
3273 void lockdep_clear_current_reclaim_state(void)
3274 {
3275         current->lockdep_reclaim_gfp = 0;
3276 }
3277
3278 #ifdef CONFIG_LOCK_STAT
3279 static int
3280 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3281                            unsigned long ip)
3282 {
3283         if (!debug_locks_off())
3284                 return 0;
3285         if (debug_locks_silent)
3286                 return 0;
3287
3288         printk("\n=================================\n");
3289         printk(  "[ BUG: bad contention detected! ]\n");
3290         printk(  "---------------------------------\n");
3291         printk("%s/%d is trying to contend lock (",
3292                 curr->comm, task_pid_nr(curr));
3293         print_lockdep_cache(lock);
3294         printk(") at:\n");
3295         print_ip_sym(ip);
3296         printk("but there are no locks held!\n");
3297         printk("\nother info that might help us debug this:\n");
3298         lockdep_print_held_locks(curr);
3299
3300         printk("\nstack backtrace:\n");
3301         dump_stack();
3302
3303         return 0;
3304 }
3305
3306 static void
3307 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3308 {
3309         struct task_struct *curr = current;
3310         struct held_lock *hlock, *prev_hlock;
3311         struct lock_class_stats *stats;
3312         unsigned int depth;
3313         int i, contention_point, contending_point;
3314
3315         depth = curr->lockdep_depth;
3316         if (DEBUG_LOCKS_WARN_ON(!depth))
3317                 return;
3318
3319         prev_hlock = NULL;
3320         for (i = depth-1; i >= 0; i--) {
3321                 hlock = curr->held_locks + i;
3322                 /*
3323                  * We must not cross into another context:
3324                  */
3325                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3326                         break;
3327                 if (match_held_lock(hlock, lock))
3328                         goto found_it;
3329                 prev_hlock = hlock;
3330         }
3331         print_lock_contention_bug(curr, lock, ip);
3332         return;
3333
3334 found_it:
3335         if (hlock->instance != lock)
3336                 return;
3337
3338         hlock->waittime_stamp = lockstat_clock();
3339
3340         contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3341         contending_point = lock_point(hlock_class(hlock)->contending_point,
3342                                       lock->ip);
3343
3344         stats = get_lock_stats(hlock_class(hlock));
3345         if (contention_point < LOCKSTAT_POINTS)
3346                 stats->contention_point[contention_point]++;
3347         if (contending_point < LOCKSTAT_POINTS)
3348                 stats->contending_point[contending_point]++;
3349         if (lock->cpu != smp_processor_id())
3350                 stats->bounces[bounce_contended + !!hlock->read]++;
3351         put_lock_stats(stats);
3352 }
3353
3354 static void
3355 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3356 {
3357         struct task_struct *curr = current;
3358         struct held_lock *hlock, *prev_hlock;
3359         struct lock_class_stats *stats;
3360         unsigned int depth;
3361         u64 now, waittime = 0;
3362         int i, cpu;
3363
3364         depth = curr->lockdep_depth;
3365         if (DEBUG_LOCKS_WARN_ON(!depth))
3366                 return;
3367
3368         prev_hlock = NULL;
3369         for (i = depth-1; i >= 0; i--) {
3370                 hlock = curr->held_locks + i;
3371                 /*
3372                  * We must not cross into another context:
3373                  */
3374                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3375                         break;
3376                 if (match_held_lock(hlock, lock))
3377                         goto found_it;
3378                 prev_hlock = hlock;
3379         }
3380         print_lock_contention_bug(curr, lock, _RET_IP_);
3381         return;
3382
3383 found_it:
3384         if (hlock->instance != lock)
3385                 return;
3386
3387         cpu = smp_processor_id();
3388         if (hlock->waittime_stamp) {
3389                 now = lockstat_clock();
3390                 waittime = now - hlock->waittime_stamp;
3391                 hlock->holdtime_stamp = now;
3392         }
3393
3394         trace_lock_acquired(lock, ip, waittime);
3395
3396         stats = get_lock_stats(hlock_class(hlock));
3397         if (waittime) {
3398                 if (hlock->read)
3399                         lock_time_inc(&stats->read_waittime, waittime);
3400                 else
3401                         lock_time_inc(&stats->write_waittime, waittime);
3402         }
3403         if (lock->cpu != cpu)
3404                 stats->bounces[bounce_acquired + !!hlock->read]++;
3405         put_lock_stats(stats);
3406
3407         lock->cpu = cpu;
3408         lock->ip = ip;
3409 }
3410
3411 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3412 {
3413         unsigned long flags;
3414
3415         if (unlikely(!lock_stat))
3416                 return;
3417
3418         if (unlikely(current->lockdep_recursion))
3419                 return;
3420
3421         raw_local_irq_save(flags);
3422         check_flags(flags);
3423         current->lockdep_recursion = 1;
3424         trace_lock_contended(lock, ip);
3425         __lock_contended(lock, ip);
3426         current->lockdep_recursion = 0;
3427         raw_local_irq_restore(flags);
3428 }
3429 EXPORT_SYMBOL_GPL(lock_contended);
3430
3431 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3432 {
3433         unsigned long flags;
3434
3435         if (unlikely(!lock_stat))
3436                 return;
3437
3438         if (unlikely(current->lockdep_recursion))
3439                 return;
3440
3441         raw_local_irq_save(flags);
3442         check_flags(flags);
3443         current->lockdep_recursion = 1;
3444         __lock_acquired(lock, ip);
3445         current->lockdep_recursion = 0;
3446         raw_local_irq_restore(flags);
3447 }
3448 EXPORT_SYMBOL_GPL(lock_acquired);
3449 #endif
3450
3451 /*
3452  * Used by the testsuite, sanitize the validator state
3453  * after a simulated failure:
3454  */
3455
3456 void lockdep_reset(void)
3457 {
3458         unsigned long flags;
3459         int i;
3460
3461         raw_local_irq_save(flags);
3462         current->curr_chain_key = 0;
3463         current->lockdep_depth = 0;
3464         current->lockdep_recursion = 0;
3465         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3466         nr_hardirq_chains = 0;
3467         nr_softirq_chains = 0;
3468         nr_process_chains = 0;
3469         debug_locks = 1;
3470         for (i = 0; i < CHAINHASH_SIZE; i++)
3471                 INIT_LIST_HEAD(chainhash_table + i);
3472         raw_local_irq_restore(flags);
3473 }
3474
3475 static void zap_class(struct lock_class *class)
3476 {
3477         int i;
3478
3479         /*
3480          * Remove all dependencies this lock is
3481          * involved in:
3482          */
3483         for (i = 0; i < nr_list_entries; i++) {
3484                 if (list_entries[i].class == class)
3485                         list_del_rcu(&list_entries[i].entry);
3486         }
3487         /*
3488          * Unhash the class and remove it from the all_lock_classes list:
3489          */
3490         list_del_rcu(&class->hash_entry);
3491         list_del_rcu(&class->lock_entry);
3492
3493         class->key = NULL;
3494 }
3495
3496 static inline int within(const void *addr, void *start, unsigned long size)
3497 {
3498         return addr >= start && addr < start + size;
3499 }
3500
3501 void lockdep_free_key_range(void *start, unsigned long size)
3502 {
3503         struct lock_class *class, *next;
3504         struct list_head *head;
3505         unsigned long flags;
3506         int i;
3507         int locked;
3508
3509         raw_local_irq_save(flags);
3510         locked = graph_lock();
3511
3512         /*
3513          * Unhash all classes that were created by this module:
3514          */
3515         for (i = 0; i < CLASSHASH_SIZE; i++) {
3516                 head = classhash_table + i;
3517                 if (list_empty(head))
3518                         continue;
3519                 list_for_each_entry_safe(class, next, head, hash_entry) {
3520                         if (within(class->key, start, size))
3521                                 zap_class(class);
3522                         else if (within(class->name, start, size))
3523                                 zap_class(class);
3524                 }
3525         }
3526
3527         if (locked)
3528                 graph_unlock();
3529         raw_local_irq_restore(flags);
3530 }
3531
3532 void lockdep_reset_lock(struct lockdep_map *lock)
3533 {
3534         struct lock_class *class, *next;
3535         struct list_head *head;
3536         unsigned long flags;
3537         int i, j;
3538         int locked;
3539
3540         raw_local_irq_save(flags);
3541
3542         /*
3543          * Remove all classes this lock might have:
3544          */
3545         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3546                 /*
3547                  * If the class exists we look it up and zap it:
3548                  */
3549                 class = look_up_lock_class(lock, j);
3550                 if (class)
3551                         zap_class(class);
3552         }
3553         /*
3554          * Debug check: in the end all mapped classes should
3555          * be gone.
3556          */
3557         locked = graph_lock();
3558         for (i = 0; i < CLASSHASH_SIZE; i++) {
3559                 head = classhash_table + i;
3560                 if (list_empty(head))
3561                         continue;
3562                 list_for_each_entry_safe(class, next, head, hash_entry) {
3563                         if (unlikely(class == lock->class_cache)) {
3564                                 if (debug_locks_off_graph_unlock())
3565                                         WARN_ON(1);
3566                                 goto out_restore;
3567                         }
3568                 }
3569         }
3570         if (locked)
3571                 graph_unlock();
3572
3573 out_restore:
3574         raw_local_irq_restore(flags);
3575 }
3576
3577 void lockdep_init(void)
3578 {
3579         int i;
3580
3581         /*
3582          * Some architectures have their own start_kernel()
3583          * code which calls lockdep_init(), while we also
3584          * call lockdep_init() from the start_kernel() itself,
3585          * and we want to initialize the hashes only once:
3586          */
3587         if (lockdep_initialized)
3588                 return;
3589
3590         for (i = 0; i < CLASSHASH_SIZE; i++)
3591                 INIT_LIST_HEAD(classhash_table + i);
3592
3593         for (i = 0; i < CHAINHASH_SIZE; i++)
3594                 INIT_LIST_HEAD(chainhash_table + i);
3595
3596         lockdep_initialized = 1;
3597 }
3598
3599 void __init lockdep_info(void)
3600 {
3601         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3602
3603         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3604         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3605         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3606         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3607         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3608         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3609         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3610
3611         printk(" memory used by lock dependency info: %lu kB\n",
3612                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3613                 sizeof(struct list_head) * CLASSHASH_SIZE +
3614                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3615                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3616                 sizeof(struct list_head) * CHAINHASH_SIZE
3617 #ifdef CONFIG_PROVE_LOCKING
3618                 + sizeof(struct circular_queue)
3619 #endif
3620                 ) / 1024
3621                 );
3622
3623         printk(" per task-struct memory footprint: %lu bytes\n",
3624                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3625
3626 #ifdef CONFIG_DEBUG_LOCKDEP
3627         if (lockdep_init_error) {
3628                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3629                 printk("Call stack leading to lockdep invocation was:\n");
3630                 print_stack_trace(&lockdep_init_trace, 0);
3631         }
3632 #endif
3633 }
3634
3635 static void
3636 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3637                      const void *mem_to, struct held_lock *hlock)
3638 {
3639         if (!debug_locks_off())
3640                 return;
3641         if (debug_locks_silent)
3642                 return;
3643
3644         printk("\n=========================\n");
3645         printk(  "[ BUG: held lock freed! ]\n");
3646         printk(  "-------------------------\n");
3647         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3648                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3649         print_lock(hlock);
3650         lockdep_print_held_locks(curr);
3651
3652         printk("\nstack backtrace:\n");
3653         dump_stack();
3654 }
3655
3656 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3657                                 const void* lock_from, unsigned long lock_len)
3658 {
3659         return lock_from + lock_len <= mem_from ||
3660                 mem_from + mem_len <= lock_from;
3661 }
3662
3663 /*
3664  * Called when kernel memory is freed (or unmapped), or if a lock
3665  * is destroyed or reinitialized - this code checks whether there is
3666  * any held lock in the memory range of <from> to <to>:
3667  */
3668 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3669 {
3670         struct task_struct *curr = current;
3671         struct held_lock *hlock;
3672         unsigned long flags;
3673         int i;
3674
3675         if (unlikely(!debug_locks))
3676                 return;
3677
3678         local_irq_save(flags);
3679         for (i = 0; i < curr->lockdep_depth; i++) {
3680                 hlock = curr->held_locks + i;
3681
3682                 if (not_in_range(mem_from, mem_len, hlock->instance,
3683                                         sizeof(*hlock->instance)))
3684                         continue;
3685
3686                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3687                 break;
3688         }
3689         local_irq_restore(flags);
3690 }
3691 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3692
3693 static void print_held_locks_bug(struct task_struct *curr)
3694 {
3695         if (!debug_locks_off())
3696                 return;
3697         if (debug_locks_silent)
3698                 return;
3699
3700         printk("\n=====================================\n");
3701         printk(  "[ BUG: lock held at task exit time! ]\n");
3702         printk(  "-------------------------------------\n");
3703         printk("%s/%d is exiting with locks still held!\n",
3704                 curr->comm, task_pid_nr(curr));
3705         lockdep_print_held_locks(curr);
3706
3707         printk("\nstack backtrace:\n");
3708         dump_stack();
3709 }
3710
3711 void debug_check_no_locks_held(struct task_struct *task)
3712 {
3713         if (unlikely(task->lockdep_depth > 0))
3714                 print_held_locks_bug(task);
3715 }
3716
3717 void debug_show_all_locks(void)
3718 {
3719         struct task_struct *g, *p;
3720         int count = 10;
3721         int unlock = 1;
3722
3723         if (unlikely(!debug_locks)) {
3724                 printk("INFO: lockdep is turned off.\n");
3725                 return;
3726         }
3727         printk("\nShowing all locks held in the system:\n");
3728
3729         /*
3730          * Here we try to get the tasklist_lock as hard as possible,
3731          * if not successful after 2 seconds we ignore it (but keep
3732          * trying). This is to enable a debug printout even if a
3733          * tasklist_lock-holding task deadlocks or crashes.
3734          */
3735 retry:
3736         if (!read_trylock(&tasklist_lock)) {
3737                 if (count == 10)
3738                         printk("hm, tasklist_lock locked, retrying... ");
3739                 if (count) {
3740                         count--;
3741                         printk(" #%d", 10-count);
3742                         mdelay(200);
3743                         goto retry;
3744                 }
3745                 printk(" ignoring it.\n");
3746                 unlock = 0;
3747         } else {
3748                 if (count != 10)
3749                         printk(KERN_CONT " locked it.\n");
3750         }
3751
3752         do_each_thread(g, p) {
3753                 /*
3754                  * It's not reliable to print a task's held locks
3755                  * if it's not sleeping (or if it's not the current
3756                  * task):
3757                  */
3758                 if (p->state == TASK_RUNNING && p != current)
3759                         continue;
3760                 if (p->lockdep_depth)
3761                         lockdep_print_held_locks(p);
3762                 if (!unlock)
3763                         if (read_trylock(&tasklist_lock))
3764                                 unlock = 1;
3765         } while_each_thread(g, p);
3766
3767         printk("\n");
3768         printk("=============================================\n\n");
3769
3770         if (unlock)
3771                 read_unlock(&tasklist_lock);
3772 }
3773 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3774
3775 /*
3776  * Careful: only use this function if you are sure that
3777  * the task cannot run in parallel!
3778  */
3779 void __debug_show_held_locks(struct task_struct *task)
3780 {
3781         if (unlikely(!debug_locks)) {
3782                 printk("INFO: lockdep is turned off.\n");
3783                 return;
3784         }
3785         lockdep_print_held_locks(task);
3786 }
3787 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3788
3789 void debug_show_held_locks(struct task_struct *task)
3790 {
3791                 __debug_show_held_locks(task);
3792 }
3793 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3794
3795 void lockdep_sys_exit(void)
3796 {
3797         struct task_struct *curr = current;
3798
3799         if (unlikely(curr->lockdep_depth)) {
3800                 if (!debug_locks_off())
3801                         return;
3802                 printk("\n================================================\n");
3803                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3804                 printk(  "------------------------------------------------\n");
3805                 printk("%s/%d is leaving the kernel with locks still held!\n",
3806                                 curr->comm, curr->pid);
3807                 lockdep_print_held_locks(curr);
3808         }
3809 }
3810
3811 void lockdep_rcu_dereference(const char *file, const int line)
3812 {
3813         struct task_struct *curr = current;
3814
3815         if (!debug_locks_off())
3816                 return;
3817         printk("\n===================================================\n");
3818         printk(  "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3819         printk(  "---------------------------------------------------\n");
3820         printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3821                         file, line);
3822         printk("\nother info that might help us debug this:\n\n");
3823         printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
3824         lockdep_print_held_locks(curr);
3825         printk("\nstack backtrace:\n");
3826         dump_stack();
3827 }
3828 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);