lockdep: fix internal double unlock during self-test
[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 #include <linux/mutex.h>
29 #include <linux/sched.h>
30 #include <linux/delay.h>
31 #include <linux/module.h>
32 #include <linux/proc_fs.h>
33 #include <linux/seq_file.h>
34 #include <linux/spinlock.h>
35 #include <linux/kallsyms.h>
36 #include <linux/interrupt.h>
37 #include <linux/stacktrace.h>
38 #include <linux/debug_locks.h>
39 #include <linux/irqflags.h>
40 #include <linux/utsname.h>
41 #include <linux/hash.h>
42
43 #include <asm/sections.h>
44
45 #include "lockdep_internals.h"
46
47 #ifdef CONFIG_PROVE_LOCKING
48 int prove_locking = 1;
49 module_param(prove_locking, int, 0644);
50 #else
51 #define prove_locking 0
52 #endif
53
54 #ifdef CONFIG_LOCK_STAT
55 int lock_stat = 1;
56 module_param(lock_stat, int, 0644);
57 #else
58 #define lock_stat 0
59 #endif
60
61 /*
62  * lockdep_lock: protects the lockdep graph, the hashes and the
63  *               class/list/hash allocators.
64  *
65  * This is one of the rare exceptions where it's justified
66  * to use a raw spinlock - we really dont want the spinlock
67  * code to recurse back into the lockdep code...
68  */
69 static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
70
71 static int graph_lock(void)
72 {
73         __raw_spin_lock(&lockdep_lock);
74         /*
75          * Make sure that if another CPU detected a bug while
76          * walking the graph we dont change it (while the other
77          * CPU is busy printing out stuff with the graph lock
78          * dropped already)
79          */
80         if (!debug_locks) {
81                 __raw_spin_unlock(&lockdep_lock);
82                 return 0;
83         }
84         return 1;
85 }
86
87 static inline int graph_unlock(void)
88 {
89         if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
90                 return DEBUG_LOCKS_WARN_ON(1);
91
92         __raw_spin_unlock(&lockdep_lock);
93         return 0;
94 }
95
96 /*
97  * Turn lock debugging off and return with 0 if it was off already,
98  * and also release the graph lock:
99  */
100 static inline int debug_locks_off_graph_unlock(void)
101 {
102         int ret = debug_locks_off();
103
104         __raw_spin_unlock(&lockdep_lock);
105
106         return ret;
107 }
108
109 static int lockdep_initialized;
110
111 unsigned long nr_list_entries;
112 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
113
114 /*
115  * All data structures here are protected by the global debug_lock.
116  *
117  * Mutex key structs only get allocated, once during bootup, and never
118  * get freed - this significantly simplifies the debugging code.
119  */
120 unsigned long nr_lock_classes;
121 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
122
123 #ifdef CONFIG_LOCK_STAT
124 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
125
126 static int lock_contention_point(struct lock_class *class, unsigned long ip)
127 {
128         int i;
129
130         for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {
131                 if (class->contention_point[i] == 0) {
132                         class->contention_point[i] = ip;
133                         break;
134                 }
135                 if (class->contention_point[i] == ip)
136                         break;
137         }
138
139         return i;
140 }
141
142 static void lock_time_inc(struct lock_time *lt, s64 time)
143 {
144         if (time > lt->max)
145                 lt->max = time;
146
147         if (time < lt->min || !lt->min)
148                 lt->min = time;
149
150         lt->total += time;
151         lt->nr++;
152 }
153
154 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
155 {
156         dst->min += src->min;
157         dst->max += src->max;
158         dst->total += src->total;
159         dst->nr += src->nr;
160 }
161
162 struct lock_class_stats lock_stats(struct lock_class *class)
163 {
164         struct lock_class_stats stats;
165         int cpu, i;
166
167         memset(&stats, 0, sizeof(struct lock_class_stats));
168         for_each_possible_cpu(cpu) {
169                 struct lock_class_stats *pcs =
170                         &per_cpu(lock_stats, cpu)[class - lock_classes];
171
172                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
173                         stats.contention_point[i] += pcs->contention_point[i];
174
175                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
176                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
177
178                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
179                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
180
181                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
182                         stats.bounces[i] += pcs->bounces[i];
183         }
184
185         return stats;
186 }
187
188 void clear_lock_stats(struct lock_class *class)
189 {
190         int cpu;
191
192         for_each_possible_cpu(cpu) {
193                 struct lock_class_stats *cpu_stats =
194                         &per_cpu(lock_stats, cpu)[class - lock_classes];
195
196                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
197         }
198         memset(class->contention_point, 0, sizeof(class->contention_point));
199 }
200
201 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
202 {
203         return &get_cpu_var(lock_stats)[class - lock_classes];
204 }
205
206 static void put_lock_stats(struct lock_class_stats *stats)
207 {
208         put_cpu_var(lock_stats);
209 }
210
211 static void lock_release_holdtime(struct held_lock *hlock)
212 {
213         struct lock_class_stats *stats;
214         s64 holdtime;
215
216         if (!lock_stat)
217                 return;
218
219         holdtime = sched_clock() - hlock->holdtime_stamp;
220
221         stats = get_lock_stats(hlock->class);
222         if (hlock->read)
223                 lock_time_inc(&stats->read_holdtime, holdtime);
224         else
225                 lock_time_inc(&stats->write_holdtime, holdtime);
226         put_lock_stats(stats);
227 }
228 #else
229 static inline void lock_release_holdtime(struct held_lock *hlock)
230 {
231 }
232 #endif
233
234 /*
235  * We keep a global list of all lock classes. The list only grows,
236  * never shrinks. The list is only accessed with the lockdep
237  * spinlock lock held.
238  */
239 LIST_HEAD(all_lock_classes);
240
241 /*
242  * The lockdep classes are in a hash-table as well, for fast lookup:
243  */
244 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
245 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
246 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
247 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
248
249 static struct list_head classhash_table[CLASSHASH_SIZE];
250
251 /*
252  * We put the lock dependency chains into a hash-table as well, to cache
253  * their existence:
254  */
255 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
256 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
257 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
258 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
259
260 static struct list_head chainhash_table[CHAINHASH_SIZE];
261
262 /*
263  * The hash key of the lock dependency chains is a hash itself too:
264  * it's a hash of all locks taken up to that lock, including that lock.
265  * It's a 64-bit hash, because it's important for the keys to be
266  * unique.
267  */
268 #define iterate_chain_key(key1, key2) \
269         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
270         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
271         (key2))
272
273 void lockdep_off(void)
274 {
275         current->lockdep_recursion++;
276 }
277
278 EXPORT_SYMBOL(lockdep_off);
279
280 void lockdep_on(void)
281 {
282         current->lockdep_recursion--;
283 }
284
285 EXPORT_SYMBOL(lockdep_on);
286
287 /*
288  * Debugging switches:
289  */
290
291 #define VERBOSE                 0
292 #define VERY_VERBOSE            0
293
294 #if VERBOSE
295 # define HARDIRQ_VERBOSE        1
296 # define SOFTIRQ_VERBOSE        1
297 #else
298 # define HARDIRQ_VERBOSE        0
299 # define SOFTIRQ_VERBOSE        0
300 #endif
301
302 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
303 /*
304  * Quick filtering for interesting events:
305  */
306 static int class_filter(struct lock_class *class)
307 {
308 #if 0
309         /* Example */
310         if (class->name_version == 1 &&
311                         !strcmp(class->name, "lockname"))
312                 return 1;
313         if (class->name_version == 1 &&
314                         !strcmp(class->name, "&struct->lockfield"))
315                 return 1;
316 #endif
317         /* Filter everything else. 1 would be to allow everything else */
318         return 0;
319 }
320 #endif
321
322 static int verbose(struct lock_class *class)
323 {
324 #if VERBOSE
325         return class_filter(class);
326 #endif
327         return 0;
328 }
329
330 /*
331  * Stack-trace: tightly packed array of stack backtrace
332  * addresses. Protected by the graph_lock.
333  */
334 unsigned long nr_stack_trace_entries;
335 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
336
337 static int save_trace(struct stack_trace *trace)
338 {
339         trace->nr_entries = 0;
340         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
341         trace->entries = stack_trace + nr_stack_trace_entries;
342
343         trace->skip = 3;
344
345         save_stack_trace(trace);
346
347         trace->max_entries = trace->nr_entries;
348
349         nr_stack_trace_entries += trace->nr_entries;
350
351         if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
352                 if (!debug_locks_off_graph_unlock())
353                         return 0;
354
355                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
356                 printk("turning off the locking correctness validator.\n");
357                 dump_stack();
358
359                 return 0;
360         }
361
362         return 1;
363 }
364
365 unsigned int nr_hardirq_chains;
366 unsigned int nr_softirq_chains;
367 unsigned int nr_process_chains;
368 unsigned int max_lockdep_depth;
369 unsigned int max_recursion_depth;
370
371 #ifdef CONFIG_DEBUG_LOCKDEP
372 /*
373  * We cannot printk in early bootup code. Not even early_printk()
374  * might work. So we mark any initialization errors and printk
375  * about it later on, in lockdep_info().
376  */
377 static int lockdep_init_error;
378 static unsigned long lockdep_init_trace_data[20];
379 static struct stack_trace lockdep_init_trace = {
380         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
381         .entries = lockdep_init_trace_data,
382 };
383
384 /*
385  * Various lockdep statistics:
386  */
387 atomic_t chain_lookup_hits;
388 atomic_t chain_lookup_misses;
389 atomic_t hardirqs_on_events;
390 atomic_t hardirqs_off_events;
391 atomic_t redundant_hardirqs_on;
392 atomic_t redundant_hardirqs_off;
393 atomic_t softirqs_on_events;
394 atomic_t softirqs_off_events;
395 atomic_t redundant_softirqs_on;
396 atomic_t redundant_softirqs_off;
397 atomic_t nr_unused_locks;
398 atomic_t nr_cyclic_checks;
399 atomic_t nr_cyclic_check_recursions;
400 atomic_t nr_find_usage_forwards_checks;
401 atomic_t nr_find_usage_forwards_recursions;
402 atomic_t nr_find_usage_backwards_checks;
403 atomic_t nr_find_usage_backwards_recursions;
404 # define debug_atomic_inc(ptr)          atomic_inc(ptr)
405 # define debug_atomic_dec(ptr)          atomic_dec(ptr)
406 # define debug_atomic_read(ptr)         atomic_read(ptr)
407 #else
408 # define debug_atomic_inc(ptr)          do { } while (0)
409 # define debug_atomic_dec(ptr)          do { } while (0)
410 # define debug_atomic_read(ptr)         0
411 #endif
412
413 /*
414  * Locking printouts:
415  */
416
417 static const char *usage_str[] =
418 {
419         [LOCK_USED] =                   "initial-use ",
420         [LOCK_USED_IN_HARDIRQ] =        "in-hardirq-W",
421         [LOCK_USED_IN_SOFTIRQ] =        "in-softirq-W",
422         [LOCK_ENABLED_SOFTIRQS] =       "softirq-on-W",
423         [LOCK_ENABLED_HARDIRQS] =       "hardirq-on-W",
424         [LOCK_USED_IN_HARDIRQ_READ] =   "in-hardirq-R",
425         [LOCK_USED_IN_SOFTIRQ_READ] =   "in-softirq-R",
426         [LOCK_ENABLED_SOFTIRQS_READ] =  "softirq-on-R",
427         [LOCK_ENABLED_HARDIRQS_READ] =  "hardirq-on-R",
428 };
429
430 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
431 {
432         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
433 }
434
435 void
436 get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
437 {
438         *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
439
440         if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
441                 *c1 = '+';
442         else
443                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
444                         *c1 = '-';
445
446         if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
447                 *c2 = '+';
448         else
449                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
450                         *c2 = '-';
451
452         if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
453                 *c3 = '-';
454         if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
455                 *c3 = '+';
456                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
457                         *c3 = '?';
458         }
459
460         if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
461                 *c4 = '-';
462         if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
463                 *c4 = '+';
464                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
465                         *c4 = '?';
466         }
467 }
468
469 static void print_lock_name(struct lock_class *class)
470 {
471         char str[KSYM_NAME_LEN], c1, c2, c3, c4;
472         const char *name;
473
474         get_usage_chars(class, &c1, &c2, &c3, &c4);
475
476         name = class->name;
477         if (!name) {
478                 name = __get_key_name(class->key, str);
479                 printk(" (%s", name);
480         } else {
481                 printk(" (%s", name);
482                 if (class->name_version > 1)
483                         printk("#%d", class->name_version);
484                 if (class->subclass)
485                         printk("/%d", class->subclass);
486         }
487         printk("){%c%c%c%c}", c1, c2, c3, c4);
488 }
489
490 static void print_lockdep_cache(struct lockdep_map *lock)
491 {
492         const char *name;
493         char str[KSYM_NAME_LEN];
494
495         name = lock->name;
496         if (!name)
497                 name = __get_key_name(lock->key->subkeys, str);
498
499         printk("%s", name);
500 }
501
502 static void print_lock(struct held_lock *hlock)
503 {
504         print_lock_name(hlock->class);
505         printk(", at: ");
506         print_ip_sym(hlock->acquire_ip);
507 }
508
509 static void lockdep_print_held_locks(struct task_struct *curr)
510 {
511         int i, depth = curr->lockdep_depth;
512
513         if (!depth) {
514                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
515                 return;
516         }
517         printk("%d lock%s held by %s/%d:\n",
518                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
519
520         for (i = 0; i < depth; i++) {
521                 printk(" #%d: ", i);
522                 print_lock(curr->held_locks + i);
523         }
524 }
525
526 static void print_lock_class_header(struct lock_class *class, int depth)
527 {
528         int bit;
529
530         printk("%*s->", depth, "");
531         print_lock_name(class);
532         printk(" ops: %lu", class->ops);
533         printk(" {\n");
534
535         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
536                 if (class->usage_mask & (1 << bit)) {
537                         int len = depth;
538
539                         len += printk("%*s   %s", depth, "", usage_str[bit]);
540                         len += printk(" at:\n");
541                         print_stack_trace(class->usage_traces + bit, len);
542                 }
543         }
544         printk("%*s }\n", depth, "");
545
546         printk("%*s ... key      at: ",depth,"");
547         print_ip_sym((unsigned long)class->key);
548 }
549
550 /*
551  * printk all lock dependencies starting at <entry>:
552  */
553 static void print_lock_dependencies(struct lock_class *class, int depth)
554 {
555         struct lock_list *entry;
556
557         if (DEBUG_LOCKS_WARN_ON(depth >= 20))
558                 return;
559
560         print_lock_class_header(class, depth);
561
562         list_for_each_entry(entry, &class->locks_after, entry) {
563                 if (DEBUG_LOCKS_WARN_ON(!entry->class))
564                         return;
565
566                 print_lock_dependencies(entry->class, depth + 1);
567
568                 printk("%*s ... acquired at:\n",depth,"");
569                 print_stack_trace(&entry->trace, 2);
570                 printk("\n");
571         }
572 }
573
574 static void print_kernel_version(void)
575 {
576         printk("%s %.*s\n", init_utsname()->release,
577                 (int)strcspn(init_utsname()->version, " "),
578                 init_utsname()->version);
579 }
580
581 static int very_verbose(struct lock_class *class)
582 {
583 #if VERY_VERBOSE
584         return class_filter(class);
585 #endif
586         return 0;
587 }
588
589 /*
590  * Is this the address of a static object:
591  */
592 static int static_obj(void *obj)
593 {
594         unsigned long start = (unsigned long) &_stext,
595                       end   = (unsigned long) &_end,
596                       addr  = (unsigned long) obj;
597 #ifdef CONFIG_SMP
598         int i;
599 #endif
600
601         /*
602          * static variable?
603          */
604         if ((addr >= start) && (addr < end))
605                 return 1;
606
607 #ifdef CONFIG_SMP
608         /*
609          * percpu var?
610          */
611         for_each_possible_cpu(i) {
612                 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
613                 end   = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
614                                         + per_cpu_offset(i);
615
616                 if ((addr >= start) && (addr < end))
617                         return 1;
618         }
619 #endif
620
621         /*
622          * module var?
623          */
624         return is_module_address(addr);
625 }
626
627 /*
628  * To make lock name printouts unique, we calculate a unique
629  * class->name_version generation counter:
630  */
631 static int count_matching_names(struct lock_class *new_class)
632 {
633         struct lock_class *class;
634         int count = 0;
635
636         if (!new_class->name)
637                 return 0;
638
639         list_for_each_entry(class, &all_lock_classes, lock_entry) {
640                 if (new_class->key - new_class->subclass == class->key)
641                         return class->name_version;
642                 if (class->name && !strcmp(class->name, new_class->name))
643                         count = max(count, class->name_version);
644         }
645
646         return count + 1;
647 }
648
649 /*
650  * Register a lock's class in the hash-table, if the class is not present
651  * yet. Otherwise we look it up. We cache the result in the lock object
652  * itself, so actual lookup of the hash should be once per lock object.
653  */
654 static inline struct lock_class *
655 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
656 {
657         struct lockdep_subclass_key *key;
658         struct list_head *hash_head;
659         struct lock_class *class;
660
661 #ifdef CONFIG_DEBUG_LOCKDEP
662         /*
663          * If the architecture calls into lockdep before initializing
664          * the hashes then we'll warn about it later. (we cannot printk
665          * right now)
666          */
667         if (unlikely(!lockdep_initialized)) {
668                 lockdep_init();
669                 lockdep_init_error = 1;
670                 save_stack_trace(&lockdep_init_trace);
671         }
672 #endif
673
674         /*
675          * Static locks do not have their class-keys yet - for them the key
676          * is the lock object itself:
677          */
678         if (unlikely(!lock->key))
679                 lock->key = (void *)lock;
680
681         /*
682          * NOTE: the class-key must be unique. For dynamic locks, a static
683          * lock_class_key variable is passed in through the mutex_init()
684          * (or spin_lock_init()) call - which acts as the key. For static
685          * locks we use the lock object itself as the key.
686          */
687         BUILD_BUG_ON(sizeof(struct lock_class_key) >
688                         sizeof(struct lockdep_map));
689
690         key = lock->key->subkeys + subclass;
691
692         hash_head = classhashentry(key);
693
694         /*
695          * We can walk the hash lockfree, because the hash only
696          * grows, and we are careful when adding entries to the end:
697          */
698         list_for_each_entry(class, hash_head, hash_entry) {
699                 if (class->key == key) {
700                         WARN_ON_ONCE(class->name != lock->name);
701                         return class;
702                 }
703         }
704
705         return NULL;
706 }
707
708 /*
709  * Register a lock's class in the hash-table, if the class is not present
710  * yet. Otherwise we look it up. We cache the result in the lock object
711  * itself, so actual lookup of the hash should be once per lock object.
712  */
713 static inline struct lock_class *
714 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
715 {
716         struct lockdep_subclass_key *key;
717         struct list_head *hash_head;
718         struct lock_class *class;
719         unsigned long flags;
720
721         class = look_up_lock_class(lock, subclass);
722         if (likely(class))
723                 return class;
724
725         /*
726          * Debug-check: all keys must be persistent!
727          */
728         if (!static_obj(lock->key)) {
729                 debug_locks_off();
730                 printk("INFO: trying to register non-static key.\n");
731                 printk("the code is fine but needs lockdep annotation.\n");
732                 printk("turning off the locking correctness validator.\n");
733                 dump_stack();
734
735                 return NULL;
736         }
737
738         key = lock->key->subkeys + subclass;
739         hash_head = classhashentry(key);
740
741         raw_local_irq_save(flags);
742         if (!graph_lock()) {
743                 raw_local_irq_restore(flags);
744                 return NULL;
745         }
746         /*
747          * We have to do the hash-walk again, to avoid races
748          * with another CPU:
749          */
750         list_for_each_entry(class, hash_head, hash_entry)
751                 if (class->key == key)
752                         goto out_unlock_set;
753         /*
754          * Allocate a new key from the static array, and add it to
755          * the hash:
756          */
757         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
758                 if (!debug_locks_off_graph_unlock()) {
759                         raw_local_irq_restore(flags);
760                         return NULL;
761                 }
762                 raw_local_irq_restore(flags);
763
764                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
765                 printk("turning off the locking correctness validator.\n");
766                 return NULL;
767         }
768         class = lock_classes + nr_lock_classes++;
769         debug_atomic_inc(&nr_unused_locks);
770         class->key = key;
771         class->name = lock->name;
772         class->subclass = subclass;
773         INIT_LIST_HEAD(&class->lock_entry);
774         INIT_LIST_HEAD(&class->locks_before);
775         INIT_LIST_HEAD(&class->locks_after);
776         class->name_version = count_matching_names(class);
777         /*
778          * We use RCU's safe list-add method to make
779          * parallel walking of the hash-list safe:
780          */
781         list_add_tail_rcu(&class->hash_entry, hash_head);
782
783         if (verbose(class)) {
784                 graph_unlock();
785                 raw_local_irq_restore(flags);
786
787                 printk("\nnew class %p: %s", class->key, class->name);
788                 if (class->name_version > 1)
789                         printk("#%d", class->name_version);
790                 printk("\n");
791                 dump_stack();
792
793                 raw_local_irq_save(flags);
794                 if (!graph_lock()) {
795                         raw_local_irq_restore(flags);
796                         return NULL;
797                 }
798         }
799 out_unlock_set:
800         graph_unlock();
801         raw_local_irq_restore(flags);
802
803         if (!subclass || force)
804                 lock->class_cache = class;
805
806         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
807                 return NULL;
808
809         return class;
810 }
811
812 #ifdef CONFIG_PROVE_LOCKING
813 /*
814  * Allocate a lockdep entry. (assumes the graph_lock held, returns
815  * with NULL on failure)
816  */
817 static struct lock_list *alloc_list_entry(void)
818 {
819         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
820                 if (!debug_locks_off_graph_unlock())
821                         return NULL;
822
823                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
824                 printk("turning off the locking correctness validator.\n");
825                 return NULL;
826         }
827         return list_entries + nr_list_entries++;
828 }
829
830 /*
831  * Add a new dependency to the head of the list:
832  */
833 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
834                             struct list_head *head, unsigned long ip, int distance)
835 {
836         struct lock_list *entry;
837         /*
838          * Lock not present yet - get a new dependency struct and
839          * add it to the list:
840          */
841         entry = alloc_list_entry();
842         if (!entry)
843                 return 0;
844
845         entry->class = this;
846         entry->distance = distance;
847         if (!save_trace(&entry->trace))
848                 return 0;
849
850         /*
851          * Since we never remove from the dependency list, the list can
852          * be walked lockless by other CPUs, it's only allocation
853          * that must be protected by the spinlock. But this also means
854          * we must make new entries visible only once writes to the
855          * entry become visible - hence the RCU op:
856          */
857         list_add_tail_rcu(&entry->entry, head);
858
859         return 1;
860 }
861
862 /*
863  * Recursive, forwards-direction lock-dependency checking, used for
864  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
865  * checking.
866  *
867  * (to keep the stackframe of the recursive functions small we
868  *  use these global variables, and we also mark various helper
869  *  functions as noinline.)
870  */
871 static struct held_lock *check_source, *check_target;
872
873 /*
874  * Print a dependency chain entry (this is only done when a deadlock
875  * has been detected):
876  */
877 static noinline int
878 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
879 {
880         if (debug_locks_silent)
881                 return 0;
882         printk("\n-> #%u", depth);
883         print_lock_name(target->class);
884         printk(":\n");
885         print_stack_trace(&target->trace, 6);
886
887         return 0;
888 }
889
890 /*
891  * When a circular dependency is detected, print the
892  * header first:
893  */
894 static noinline int
895 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
896 {
897         struct task_struct *curr = current;
898
899         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
900                 return 0;
901
902         printk("\n=======================================================\n");
903         printk(  "[ INFO: possible circular locking dependency detected ]\n");
904         print_kernel_version();
905         printk(  "-------------------------------------------------------\n");
906         printk("%s/%d is trying to acquire lock:\n",
907                 curr->comm, task_pid_nr(curr));
908         print_lock(check_source);
909         printk("\nbut task is already holding lock:\n");
910         print_lock(check_target);
911         printk("\nwhich lock already depends on the new lock.\n\n");
912         printk("\nthe existing dependency chain (in reverse order) is:\n");
913
914         print_circular_bug_entry(entry, depth);
915
916         return 0;
917 }
918
919 static noinline int print_circular_bug_tail(void)
920 {
921         struct task_struct *curr = current;
922         struct lock_list this;
923
924         if (debug_locks_silent)
925                 return 0;
926
927         this.class = check_source->class;
928         if (!save_trace(&this.trace))
929                 return 0;
930
931         print_circular_bug_entry(&this, 0);
932
933         printk("\nother info that might help us debug this:\n\n");
934         lockdep_print_held_locks(curr);
935
936         printk("\nstack backtrace:\n");
937         dump_stack();
938
939         return 0;
940 }
941
942 #define RECURSION_LIMIT 40
943
944 static int noinline print_infinite_recursion_bug(void)
945 {
946         if (!debug_locks_off_graph_unlock())
947                 return 0;
948
949         WARN_ON(1);
950
951         return 0;
952 }
953
954 /*
955  * Prove that the dependency graph starting at <entry> can not
956  * lead to <target>. Print an error and return 0 if it does.
957  */
958 static noinline int
959 check_noncircular(struct lock_class *source, unsigned int depth)
960 {
961         struct lock_list *entry;
962
963         debug_atomic_inc(&nr_cyclic_check_recursions);
964         if (depth > max_recursion_depth)
965                 max_recursion_depth = depth;
966         if (depth >= RECURSION_LIMIT)
967                 return print_infinite_recursion_bug();
968         /*
969          * Check this lock's dependency list:
970          */
971         list_for_each_entry(entry, &source->locks_after, entry) {
972                 if (entry->class == check_target->class)
973                         return print_circular_bug_header(entry, depth+1);
974                 debug_atomic_inc(&nr_cyclic_checks);
975                 if (!check_noncircular(entry->class, depth+1))
976                         return print_circular_bug_entry(entry, depth+1);
977         }
978         return 1;
979 }
980
981 #ifdef CONFIG_TRACE_IRQFLAGS
982 /*
983  * Forwards and backwards subgraph searching, for the purposes of
984  * proving that two subgraphs can be connected by a new dependency
985  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
986  */
987 static enum lock_usage_bit find_usage_bit;
988 static struct lock_class *forwards_match, *backwards_match;
989
990 /*
991  * Find a node in the forwards-direction dependency sub-graph starting
992  * at <source> that matches <find_usage_bit>.
993  *
994  * Return 2 if such a node exists in the subgraph, and put that node
995  * into <forwards_match>.
996  *
997  * Return 1 otherwise and keep <forwards_match> unchanged.
998  * Return 0 on error.
999  */
1000 static noinline int
1001 find_usage_forwards(struct lock_class *source, unsigned int depth)
1002 {
1003         struct lock_list *entry;
1004         int ret;
1005
1006         if (depth > max_recursion_depth)
1007                 max_recursion_depth = depth;
1008         if (depth >= RECURSION_LIMIT)
1009                 return print_infinite_recursion_bug();
1010
1011         debug_atomic_inc(&nr_find_usage_forwards_checks);
1012         if (source->usage_mask & (1 << find_usage_bit)) {
1013                 forwards_match = source;
1014                 return 2;
1015         }
1016
1017         /*
1018          * Check this lock's dependency list:
1019          */
1020         list_for_each_entry(entry, &source->locks_after, entry) {
1021                 debug_atomic_inc(&nr_find_usage_forwards_recursions);
1022                 ret = find_usage_forwards(entry->class, depth+1);
1023                 if (ret == 2 || ret == 0)
1024                         return ret;
1025         }
1026         return 1;
1027 }
1028
1029 /*
1030  * Find a node in the backwards-direction dependency sub-graph starting
1031  * at <source> that matches <find_usage_bit>.
1032  *
1033  * Return 2 if such a node exists in the subgraph, and put that node
1034  * into <backwards_match>.
1035  *
1036  * Return 1 otherwise and keep <backwards_match> unchanged.
1037  * Return 0 on error.
1038  */
1039 static noinline int
1040 find_usage_backwards(struct lock_class *source, unsigned int depth)
1041 {
1042         struct lock_list *entry;
1043         int ret;
1044
1045         if (!__raw_spin_is_locked(&lockdep_lock))
1046                 return DEBUG_LOCKS_WARN_ON(1);
1047
1048         if (depth > max_recursion_depth)
1049                 max_recursion_depth = depth;
1050         if (depth >= RECURSION_LIMIT)
1051                 return print_infinite_recursion_bug();
1052
1053         debug_atomic_inc(&nr_find_usage_backwards_checks);
1054         if (source->usage_mask & (1 << find_usage_bit)) {
1055                 backwards_match = source;
1056                 return 2;
1057         }
1058
1059         /*
1060          * Check this lock's dependency list:
1061          */
1062         list_for_each_entry(entry, &source->locks_before, entry) {
1063                 debug_atomic_inc(&nr_find_usage_backwards_recursions);
1064                 ret = find_usage_backwards(entry->class, depth+1);
1065                 if (ret == 2 || ret == 0)
1066                         return ret;
1067         }
1068         return 1;
1069 }
1070
1071 static int
1072 print_bad_irq_dependency(struct task_struct *curr,
1073                          struct held_lock *prev,
1074                          struct held_lock *next,
1075                          enum lock_usage_bit bit1,
1076                          enum lock_usage_bit bit2,
1077                          const char *irqclass)
1078 {
1079         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1080                 return 0;
1081
1082         printk("\n======================================================\n");
1083         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1084                 irqclass, irqclass);
1085         print_kernel_version();
1086         printk(  "------------------------------------------------------\n");
1087         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1088                 curr->comm, task_pid_nr(curr),
1089                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1090                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1091                 curr->hardirqs_enabled,
1092                 curr->softirqs_enabled);
1093         print_lock(next);
1094
1095         printk("\nand this task is already holding:\n");
1096         print_lock(prev);
1097         printk("which would create a new lock dependency:\n");
1098         print_lock_name(prev->class);
1099         printk(" ->");
1100         print_lock_name(next->class);
1101         printk("\n");
1102
1103         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1104                 irqclass);
1105         print_lock_name(backwards_match);
1106         printk("\n... which became %s-irq-safe at:\n", irqclass);
1107
1108         print_stack_trace(backwards_match->usage_traces + bit1, 1);
1109
1110         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1111         print_lock_name(forwards_match);
1112         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1113         printk("...");
1114
1115         print_stack_trace(forwards_match->usage_traces + bit2, 1);
1116
1117         printk("\nother info that might help us debug this:\n\n");
1118         lockdep_print_held_locks(curr);
1119
1120         printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1121         print_lock_dependencies(backwards_match, 0);
1122
1123         printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1124         print_lock_dependencies(forwards_match, 0);
1125
1126         printk("\nstack backtrace:\n");
1127         dump_stack();
1128
1129         return 0;
1130 }
1131
1132 static int
1133 check_usage(struct task_struct *curr, struct held_lock *prev,
1134             struct held_lock *next, enum lock_usage_bit bit_backwards,
1135             enum lock_usage_bit bit_forwards, const char *irqclass)
1136 {
1137         int ret;
1138
1139         find_usage_bit = bit_backwards;
1140         /* fills in <backwards_match> */
1141         ret = find_usage_backwards(prev->class, 0);
1142         if (!ret || ret == 1)
1143                 return ret;
1144
1145         find_usage_bit = bit_forwards;
1146         ret = find_usage_forwards(next->class, 0);
1147         if (!ret || ret == 1)
1148                 return ret;
1149         /* ret == 2 */
1150         return print_bad_irq_dependency(curr, prev, next,
1151                         bit_backwards, bit_forwards, irqclass);
1152 }
1153
1154 static int
1155 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1156                 struct held_lock *next)
1157 {
1158         /*
1159          * Prove that the new dependency does not connect a hardirq-safe
1160          * lock with a hardirq-unsafe lock - to achieve this we search
1161          * the backwards-subgraph starting at <prev>, and the
1162          * forwards-subgraph starting at <next>:
1163          */
1164         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
1165                                         LOCK_ENABLED_HARDIRQS, "hard"))
1166                 return 0;
1167
1168         /*
1169          * Prove that the new dependency does not connect a hardirq-safe-read
1170          * lock with a hardirq-unsafe lock - to achieve this we search
1171          * the backwards-subgraph starting at <prev>, and the
1172          * forwards-subgraph starting at <next>:
1173          */
1174         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
1175                                         LOCK_ENABLED_HARDIRQS, "hard-read"))
1176                 return 0;
1177
1178         /*
1179          * Prove that the new dependency does not connect a softirq-safe
1180          * lock with a softirq-unsafe lock - to achieve this we search
1181          * the backwards-subgraph starting at <prev>, and the
1182          * forwards-subgraph starting at <next>:
1183          */
1184         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
1185                                         LOCK_ENABLED_SOFTIRQS, "soft"))
1186                 return 0;
1187         /*
1188          * Prove that the new dependency does not connect a softirq-safe-read
1189          * lock with a softirq-unsafe lock - to achieve this we search
1190          * the backwards-subgraph starting at <prev>, and the
1191          * forwards-subgraph starting at <next>:
1192          */
1193         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
1194                                         LOCK_ENABLED_SOFTIRQS, "soft"))
1195                 return 0;
1196
1197         return 1;
1198 }
1199
1200 static void inc_chains(void)
1201 {
1202         if (current->hardirq_context)
1203                 nr_hardirq_chains++;
1204         else {
1205                 if (current->softirq_context)
1206                         nr_softirq_chains++;
1207                 else
1208                         nr_process_chains++;
1209         }
1210 }
1211
1212 #else
1213
1214 static inline int
1215 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1216                 struct held_lock *next)
1217 {
1218         return 1;
1219 }
1220
1221 static inline void inc_chains(void)
1222 {
1223         nr_process_chains++;
1224 }
1225
1226 #endif
1227
1228 static int
1229 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1230                    struct held_lock *next)
1231 {
1232         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1233                 return 0;
1234
1235         printk("\n=============================================\n");
1236         printk(  "[ INFO: possible recursive locking detected ]\n");
1237         print_kernel_version();
1238         printk(  "---------------------------------------------\n");
1239         printk("%s/%d is trying to acquire lock:\n",
1240                 curr->comm, task_pid_nr(curr));
1241         print_lock(next);
1242         printk("\nbut task is already holding lock:\n");
1243         print_lock(prev);
1244
1245         printk("\nother info that might help us debug this:\n");
1246         lockdep_print_held_locks(curr);
1247
1248         printk("\nstack backtrace:\n");
1249         dump_stack();
1250
1251         return 0;
1252 }
1253
1254 /*
1255  * Check whether we are holding such a class already.
1256  *
1257  * (Note that this has to be done separately, because the graph cannot
1258  * detect such classes of deadlocks.)
1259  *
1260  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1261  */
1262 static int
1263 check_deadlock(struct task_struct *curr, struct held_lock *next,
1264                struct lockdep_map *next_instance, int read)
1265 {
1266         struct held_lock *prev;
1267         int i;
1268
1269         for (i = 0; i < curr->lockdep_depth; i++) {
1270                 prev = curr->held_locks + i;
1271                 if (prev->class != next->class)
1272                         continue;
1273                 /*
1274                  * Allow read-after-read recursion of the same
1275                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1276                  */
1277                 if ((read == 2) && prev->read)
1278                         return 2;
1279                 return print_deadlock_bug(curr, prev, next);
1280         }
1281         return 1;
1282 }
1283
1284 /*
1285  * There was a chain-cache miss, and we are about to add a new dependency
1286  * to a previous lock. We recursively validate the following rules:
1287  *
1288  *  - would the adding of the <prev> -> <next> dependency create a
1289  *    circular dependency in the graph? [== circular deadlock]
1290  *
1291  *  - does the new prev->next dependency connect any hardirq-safe lock
1292  *    (in the full backwards-subgraph starting at <prev>) with any
1293  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1294  *    <next>)? [== illegal lock inversion with hardirq contexts]
1295  *
1296  *  - does the new prev->next dependency connect any softirq-safe lock
1297  *    (in the full backwards-subgraph starting at <prev>) with any
1298  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1299  *    <next>)? [== illegal lock inversion with softirq contexts]
1300  *
1301  * any of these scenarios could lead to a deadlock.
1302  *
1303  * Then if all the validations pass, we add the forwards and backwards
1304  * dependency.
1305  */
1306 static int
1307 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1308                struct held_lock *next, int distance)
1309 {
1310         struct lock_list *entry;
1311         int ret;
1312
1313         /*
1314          * Prove that the new <prev> -> <next> dependency would not
1315          * create a circular dependency in the graph. (We do this by
1316          * forward-recursing into the graph starting at <next>, and
1317          * checking whether we can reach <prev>.)
1318          *
1319          * We are using global variables to control the recursion, to
1320          * keep the stackframe size of the recursive functions low:
1321          */
1322         check_source = next;
1323         check_target = prev;
1324         if (!(check_noncircular(next->class, 0)))
1325                 return print_circular_bug_tail();
1326
1327         if (!check_prev_add_irq(curr, prev, next))
1328                 return 0;
1329
1330         /*
1331          * For recursive read-locks we do all the dependency checks,
1332          * but we dont store read-triggered dependencies (only
1333          * write-triggered dependencies). This ensures that only the
1334          * write-side dependencies matter, and that if for example a
1335          * write-lock never takes any other locks, then the reads are
1336          * equivalent to a NOP.
1337          */
1338         if (next->read == 2 || prev->read == 2)
1339                 return 1;
1340         /*
1341          * Is the <prev> -> <next> dependency already present?
1342          *
1343          * (this may occur even though this is a new chain: consider
1344          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1345          *  chains - the second one will be new, but L1 already has
1346          *  L2 added to its dependency list, due to the first chain.)
1347          */
1348         list_for_each_entry(entry, &prev->class->locks_after, entry) {
1349                 if (entry->class == next->class) {
1350                         if (distance == 1)
1351                                 entry->distance = 1;
1352                         return 2;
1353                 }
1354         }
1355
1356         /*
1357          * Ok, all validations passed, add the new lock
1358          * to the previous lock's dependency list:
1359          */
1360         ret = add_lock_to_list(prev->class, next->class,
1361                                &prev->class->locks_after, next->acquire_ip, distance);
1362
1363         if (!ret)
1364                 return 0;
1365
1366         ret = add_lock_to_list(next->class, prev->class,
1367                                &next->class->locks_before, next->acquire_ip, distance);
1368         if (!ret)
1369                 return 0;
1370
1371         /*
1372          * Debugging printouts:
1373          */
1374         if (verbose(prev->class) || verbose(next->class)) {
1375                 graph_unlock();
1376                 printk("\n new dependency: ");
1377                 print_lock_name(prev->class);
1378                 printk(" => ");
1379                 print_lock_name(next->class);
1380                 printk("\n");
1381                 dump_stack();
1382                 return graph_lock();
1383         }
1384         return 1;
1385 }
1386
1387 /*
1388  * Add the dependency to all directly-previous locks that are 'relevant'.
1389  * The ones that are relevant are (in increasing distance from curr):
1390  * all consecutive trylock entries and the final non-trylock entry - or
1391  * the end of this context's lock-chain - whichever comes first.
1392  */
1393 static int
1394 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1395 {
1396         int depth = curr->lockdep_depth;
1397         struct held_lock *hlock;
1398
1399         /*
1400          * Debugging checks.
1401          *
1402          * Depth must not be zero for a non-head lock:
1403          */
1404         if (!depth)
1405                 goto out_bug;
1406         /*
1407          * At least two relevant locks must exist for this
1408          * to be a head:
1409          */
1410         if (curr->held_locks[depth].irq_context !=
1411                         curr->held_locks[depth-1].irq_context)
1412                 goto out_bug;
1413
1414         for (;;) {
1415                 int distance = curr->lockdep_depth - depth + 1;
1416                 hlock = curr->held_locks + depth-1;
1417                 /*
1418                  * Only non-recursive-read entries get new dependencies
1419                  * added:
1420                  */
1421                 if (hlock->read != 2) {
1422                         if (!check_prev_add(curr, hlock, next, distance))
1423                                 return 0;
1424                         /*
1425                          * Stop after the first non-trylock entry,
1426                          * as non-trylock entries have added their
1427                          * own direct dependencies already, so this
1428                          * lock is connected to them indirectly:
1429                          */
1430                         if (!hlock->trylock)
1431                                 break;
1432                 }
1433                 depth--;
1434                 /*
1435                  * End of lock-stack?
1436                  */
1437                 if (!depth)
1438                         break;
1439                 /*
1440                  * Stop the search if we cross into another context:
1441                  */
1442                 if (curr->held_locks[depth].irq_context !=
1443                                 curr->held_locks[depth-1].irq_context)
1444                         break;
1445         }
1446         return 1;
1447 out_bug:
1448         if (!debug_locks_off_graph_unlock())
1449                 return 0;
1450
1451         WARN_ON(1);
1452
1453         return 0;
1454 }
1455
1456 unsigned long nr_lock_chains;
1457 static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1458
1459 /*
1460  * Look up a dependency chain. If the key is not present yet then
1461  * add it and return 1 - in this case the new dependency chain is
1462  * validated. If the key is already hashed, return 0.
1463  * (On return with 1 graph_lock is held.)
1464  */
1465 static inline int lookup_chain_cache(u64 chain_key, struct lock_class *class)
1466 {
1467         struct list_head *hash_head = chainhashentry(chain_key);
1468         struct lock_chain *chain;
1469
1470         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1471                 return 0;
1472         /*
1473          * We can walk it lock-free, because entries only get added
1474          * to the hash:
1475          */
1476         list_for_each_entry(chain, hash_head, entry) {
1477                 if (chain->chain_key == chain_key) {
1478 cache_hit:
1479                         debug_atomic_inc(&chain_lookup_hits);
1480                         if (very_verbose(class))
1481                                 printk("\nhash chain already cached, key: "
1482                                         "%016Lx tail class: [%p] %s\n",
1483                                         (unsigned long long)chain_key,
1484                                         class->key, class->name);
1485                         return 0;
1486                 }
1487         }
1488         if (very_verbose(class))
1489                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1490                         (unsigned long long)chain_key, class->key, class->name);
1491         /*
1492          * Allocate a new chain entry from the static array, and add
1493          * it to the hash:
1494          */
1495         if (!graph_lock())
1496                 return 0;
1497         /*
1498          * We have to walk the chain again locked - to avoid duplicates:
1499          */
1500         list_for_each_entry(chain, hash_head, entry) {
1501                 if (chain->chain_key == chain_key) {
1502                         graph_unlock();
1503                         goto cache_hit;
1504                 }
1505         }
1506         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1507                 if (!debug_locks_off_graph_unlock())
1508                         return 0;
1509
1510                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1511                 printk("turning off the locking correctness validator.\n");
1512                 return 0;
1513         }
1514         chain = lock_chains + nr_lock_chains++;
1515         chain->chain_key = chain_key;
1516         list_add_tail_rcu(&chain->entry, hash_head);
1517         debug_atomic_inc(&chain_lookup_misses);
1518         inc_chains();
1519
1520         return 1;
1521 }
1522
1523 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1524                 struct held_lock *hlock, int chain_head, u64 chain_key)
1525 {
1526         /*
1527          * Trylock needs to maintain the stack of held locks, but it
1528          * does not add new dependencies, because trylock can be done
1529          * in any order.
1530          *
1531          * We look up the chain_key and do the O(N^2) check and update of
1532          * the dependencies only if this is a new dependency chain.
1533          * (If lookup_chain_cache() returns with 1 it acquires
1534          * graph_lock for us)
1535          */
1536         if (!hlock->trylock && (hlock->check == 2) &&
1537                         lookup_chain_cache(chain_key, hlock->class)) {
1538                 /*
1539                  * Check whether last held lock:
1540                  *
1541                  * - is irq-safe, if this lock is irq-unsafe
1542                  * - is softirq-safe, if this lock is hardirq-unsafe
1543                  *
1544                  * And check whether the new lock's dependency graph
1545                  * could lead back to the previous lock.
1546                  *
1547                  * any of these scenarios could lead to a deadlock. If
1548                  * All validations
1549                  */
1550                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1551
1552                 if (!ret)
1553                         return 0;
1554                 /*
1555                  * Mark recursive read, as we jump over it when
1556                  * building dependencies (just like we jump over
1557                  * trylock entries):
1558                  */
1559                 if (ret == 2)
1560                         hlock->read = 2;
1561                 /*
1562                  * Add dependency only if this lock is not the head
1563                  * of the chain, and if it's not a secondary read-lock:
1564                  */
1565                 if (!chain_head && ret != 2)
1566                         if (!check_prevs_add(curr, hlock))
1567                                 return 0;
1568                 graph_unlock();
1569         } else
1570                 /* after lookup_chain_cache(): */
1571                 if (unlikely(!debug_locks))
1572                         return 0;
1573
1574         return 1;
1575 }
1576 #else
1577 static inline int validate_chain(struct task_struct *curr,
1578                 struct lockdep_map *lock, struct held_lock *hlock,
1579                 int chain_head, u64 chain_key)
1580 {
1581         return 1;
1582 }
1583 #endif
1584
1585 /*
1586  * We are building curr_chain_key incrementally, so double-check
1587  * it from scratch, to make sure that it's done correctly:
1588  */
1589 static void check_chain_key(struct task_struct *curr)
1590 {
1591 #ifdef CONFIG_DEBUG_LOCKDEP
1592         struct held_lock *hlock, *prev_hlock = NULL;
1593         unsigned int i, id;
1594         u64 chain_key = 0;
1595
1596         for (i = 0; i < curr->lockdep_depth; i++) {
1597                 hlock = curr->held_locks + i;
1598                 if (chain_key != hlock->prev_chain_key) {
1599                         debug_locks_off();
1600                         printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1601                                 curr->lockdep_depth, i,
1602                                 (unsigned long long)chain_key,
1603                                 (unsigned long long)hlock->prev_chain_key);
1604                         WARN_ON(1);
1605                         return;
1606                 }
1607                 id = hlock->class - lock_classes;
1608                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1609                         return;
1610
1611                 if (prev_hlock && (prev_hlock->irq_context !=
1612                                                         hlock->irq_context))
1613                         chain_key = 0;
1614                 chain_key = iterate_chain_key(chain_key, id);
1615                 prev_hlock = hlock;
1616         }
1617         if (chain_key != curr->curr_chain_key) {
1618                 debug_locks_off();
1619                 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1620                         curr->lockdep_depth, i,
1621                         (unsigned long long)chain_key,
1622                         (unsigned long long)curr->curr_chain_key);
1623                 WARN_ON(1);
1624         }
1625 #endif
1626 }
1627
1628 static int
1629 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1630                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1631 {
1632         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1633                 return 0;
1634
1635         printk("\n=================================\n");
1636         printk(  "[ INFO: inconsistent lock state ]\n");
1637         print_kernel_version();
1638         printk(  "---------------------------------\n");
1639
1640         printk("inconsistent {%s} -> {%s} usage.\n",
1641                 usage_str[prev_bit], usage_str[new_bit]);
1642
1643         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1644                 curr->comm, task_pid_nr(curr),
1645                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1646                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1647                 trace_hardirqs_enabled(curr),
1648                 trace_softirqs_enabled(curr));
1649         print_lock(this);
1650
1651         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1652         print_stack_trace(this->class->usage_traces + prev_bit, 1);
1653
1654         print_irqtrace_events(curr);
1655         printk("\nother info that might help us debug this:\n");
1656         lockdep_print_held_locks(curr);
1657
1658         printk("\nstack backtrace:\n");
1659         dump_stack();
1660
1661         return 0;
1662 }
1663
1664 /*
1665  * Print out an error if an invalid bit is set:
1666  */
1667 static inline int
1668 valid_state(struct task_struct *curr, struct held_lock *this,
1669             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1670 {
1671         if (unlikely(this->class->usage_mask & (1 << bad_bit)))
1672                 return print_usage_bug(curr, this, bad_bit, new_bit);
1673         return 1;
1674 }
1675
1676 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1677                      enum lock_usage_bit new_bit);
1678
1679 #ifdef CONFIG_TRACE_IRQFLAGS
1680
1681 /*
1682  * print irq inversion bug:
1683  */
1684 static int
1685 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1686                         struct held_lock *this, int forwards,
1687                         const char *irqclass)
1688 {
1689         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1690                 return 0;
1691
1692         printk("\n=========================================================\n");
1693         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
1694         print_kernel_version();
1695         printk(  "---------------------------------------------------------\n");
1696         printk("%s/%d just changed the state of lock:\n",
1697                 curr->comm, task_pid_nr(curr));
1698         print_lock(this);
1699         if (forwards)
1700                 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1701         else
1702                 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1703         print_lock_name(other);
1704         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1705
1706         printk("\nother info that might help us debug this:\n");
1707         lockdep_print_held_locks(curr);
1708
1709         printk("\nthe first lock's dependencies:\n");
1710         print_lock_dependencies(this->class, 0);
1711
1712         printk("\nthe second lock's dependencies:\n");
1713         print_lock_dependencies(other, 0);
1714
1715         printk("\nstack backtrace:\n");
1716         dump_stack();
1717
1718         return 0;
1719 }
1720
1721 /*
1722  * Prove that in the forwards-direction subgraph starting at <this>
1723  * there is no lock matching <mask>:
1724  */
1725 static int
1726 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1727                      enum lock_usage_bit bit, const char *irqclass)
1728 {
1729         int ret;
1730
1731         find_usage_bit = bit;
1732         /* fills in <forwards_match> */
1733         ret = find_usage_forwards(this->class, 0);
1734         if (!ret || ret == 1)
1735                 return ret;
1736
1737         return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1738 }
1739
1740 /*
1741  * Prove that in the backwards-direction subgraph starting at <this>
1742  * there is no lock matching <mask>:
1743  */
1744 static int
1745 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1746                       enum lock_usage_bit bit, const char *irqclass)
1747 {
1748         int ret;
1749
1750         find_usage_bit = bit;
1751         /* fills in <backwards_match> */
1752         ret = find_usage_backwards(this->class, 0);
1753         if (!ret || ret == 1)
1754                 return ret;
1755
1756         return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1757 }
1758
1759 void print_irqtrace_events(struct task_struct *curr)
1760 {
1761         printk("irq event stamp: %u\n", curr->irq_events);
1762         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
1763         print_ip_sym(curr->hardirq_enable_ip);
1764         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1765         print_ip_sym(curr->hardirq_disable_ip);
1766         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
1767         print_ip_sym(curr->softirq_enable_ip);
1768         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1769         print_ip_sym(curr->softirq_disable_ip);
1770 }
1771
1772 static int hardirq_verbose(struct lock_class *class)
1773 {
1774 #if HARDIRQ_VERBOSE
1775         return class_filter(class);
1776 #endif
1777         return 0;
1778 }
1779
1780 static int softirq_verbose(struct lock_class *class)
1781 {
1782 #if SOFTIRQ_VERBOSE
1783         return class_filter(class);
1784 #endif
1785         return 0;
1786 }
1787
1788 #define STRICT_READ_CHECKS      1
1789
1790 static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
1791                 enum lock_usage_bit new_bit)
1792 {
1793         int ret = 1;
1794
1795         switch(new_bit) {
1796         case LOCK_USED_IN_HARDIRQ:
1797                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1798                         return 0;
1799                 if (!valid_state(curr, this, new_bit,
1800                                  LOCK_ENABLED_HARDIRQS_READ))
1801                         return 0;
1802                 /*
1803                  * just marked it hardirq-safe, check that this lock
1804                  * took no hardirq-unsafe lock in the past:
1805                  */
1806                 if (!check_usage_forwards(curr, this,
1807                                           LOCK_ENABLED_HARDIRQS, "hard"))
1808                         return 0;
1809 #if STRICT_READ_CHECKS
1810                 /*
1811                  * just marked it hardirq-safe, check that this lock
1812                  * took no hardirq-unsafe-read lock in the past:
1813                  */
1814                 if (!check_usage_forwards(curr, this,
1815                                 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1816                         return 0;
1817 #endif
1818                 if (hardirq_verbose(this->class))
1819                         ret = 2;
1820                 break;
1821         case LOCK_USED_IN_SOFTIRQ:
1822                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1823                         return 0;
1824                 if (!valid_state(curr, this, new_bit,
1825                                  LOCK_ENABLED_SOFTIRQS_READ))
1826                         return 0;
1827                 /*
1828                  * just marked it softirq-safe, check that this lock
1829                  * took no softirq-unsafe lock in the past:
1830                  */
1831                 if (!check_usage_forwards(curr, this,
1832                                           LOCK_ENABLED_SOFTIRQS, "soft"))
1833                         return 0;
1834 #if STRICT_READ_CHECKS
1835                 /*
1836                  * just marked it softirq-safe, check that this lock
1837                  * took no softirq-unsafe-read lock in the past:
1838                  */
1839                 if (!check_usage_forwards(curr, this,
1840                                 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
1841                         return 0;
1842 #endif
1843                 if (softirq_verbose(this->class))
1844                         ret = 2;
1845                 break;
1846         case LOCK_USED_IN_HARDIRQ_READ:
1847                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1848                         return 0;
1849                 /*
1850                  * just marked it hardirq-read-safe, check that this lock
1851                  * took no hardirq-unsafe lock in the past:
1852                  */
1853                 if (!check_usage_forwards(curr, this,
1854                                           LOCK_ENABLED_HARDIRQS, "hard"))
1855                         return 0;
1856                 if (hardirq_verbose(this->class))
1857                         ret = 2;
1858                 break;
1859         case LOCK_USED_IN_SOFTIRQ_READ:
1860                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1861                         return 0;
1862                 /*
1863                  * just marked it softirq-read-safe, check that this lock
1864                  * took no softirq-unsafe lock in the past:
1865                  */
1866                 if (!check_usage_forwards(curr, this,
1867                                           LOCK_ENABLED_SOFTIRQS, "soft"))
1868                         return 0;
1869                 if (softirq_verbose(this->class))
1870                         ret = 2;
1871                 break;
1872         case LOCK_ENABLED_HARDIRQS:
1873                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1874                         return 0;
1875                 if (!valid_state(curr, this, new_bit,
1876                                  LOCK_USED_IN_HARDIRQ_READ))
1877                         return 0;
1878                 /*
1879                  * just marked it hardirq-unsafe, check that no hardirq-safe
1880                  * lock in the system ever took it in the past:
1881                  */
1882                 if (!check_usage_backwards(curr, this,
1883                                            LOCK_USED_IN_HARDIRQ, "hard"))
1884                         return 0;
1885 #if STRICT_READ_CHECKS
1886                 /*
1887                  * just marked it hardirq-unsafe, check that no
1888                  * hardirq-safe-read lock in the system ever took
1889                  * it in the past:
1890                  */
1891                 if (!check_usage_backwards(curr, this,
1892                                    LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
1893                         return 0;
1894 #endif
1895                 if (hardirq_verbose(this->class))
1896                         ret = 2;
1897                 break;
1898         case LOCK_ENABLED_SOFTIRQS:
1899                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1900                         return 0;
1901                 if (!valid_state(curr, this, new_bit,
1902                                  LOCK_USED_IN_SOFTIRQ_READ))
1903                         return 0;
1904                 /*
1905                  * just marked it softirq-unsafe, check that no softirq-safe
1906                  * lock in the system ever took it in the past:
1907                  */
1908                 if (!check_usage_backwards(curr, this,
1909                                            LOCK_USED_IN_SOFTIRQ, "soft"))
1910                         return 0;
1911 #if STRICT_READ_CHECKS
1912                 /*
1913                  * just marked it softirq-unsafe, check that no
1914                  * softirq-safe-read lock in the system ever took
1915                  * it in the past:
1916                  */
1917                 if (!check_usage_backwards(curr, this,
1918                                    LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
1919                         return 0;
1920 #endif
1921                 if (softirq_verbose(this->class))
1922                         ret = 2;
1923                 break;
1924         case LOCK_ENABLED_HARDIRQS_READ:
1925                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1926                         return 0;
1927 #if STRICT_READ_CHECKS
1928                 /*
1929                  * just marked it hardirq-read-unsafe, check that no
1930                  * hardirq-safe lock in the system ever took it in the past:
1931                  */
1932                 if (!check_usage_backwards(curr, this,
1933                                            LOCK_USED_IN_HARDIRQ, "hard"))
1934                         return 0;
1935 #endif
1936                 if (hardirq_verbose(this->class))
1937                         ret = 2;
1938                 break;
1939         case LOCK_ENABLED_SOFTIRQS_READ:
1940                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1941                         return 0;
1942 #if STRICT_READ_CHECKS
1943                 /*
1944                  * just marked it softirq-read-unsafe, check that no
1945                  * softirq-safe lock in the system ever took it in the past:
1946                  */
1947                 if (!check_usage_backwards(curr, this,
1948                                            LOCK_USED_IN_SOFTIRQ, "soft"))
1949                         return 0;
1950 #endif
1951                 if (softirq_verbose(this->class))
1952                         ret = 2;
1953                 break;
1954         default:
1955                 WARN_ON(1);
1956                 break;
1957         }
1958
1959         return ret;
1960 }
1961
1962 /*
1963  * Mark all held locks with a usage bit:
1964  */
1965 static int
1966 mark_held_locks(struct task_struct *curr, int hardirq)
1967 {
1968         enum lock_usage_bit usage_bit;
1969         struct held_lock *hlock;
1970         int i;
1971
1972         for (i = 0; i < curr->lockdep_depth; i++) {
1973                 hlock = curr->held_locks + i;
1974
1975                 if (hardirq) {
1976                         if (hlock->read)
1977                                 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
1978                         else
1979                                 usage_bit = LOCK_ENABLED_HARDIRQS;
1980                 } else {
1981                         if (hlock->read)
1982                                 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
1983                         else
1984                                 usage_bit = LOCK_ENABLED_SOFTIRQS;
1985                 }
1986                 if (!mark_lock(curr, hlock, usage_bit))
1987                         return 0;
1988         }
1989
1990         return 1;
1991 }
1992
1993 /*
1994  * Debugging helper: via this flag we know that we are in
1995  * 'early bootup code', and will warn about any invalid irqs-on event:
1996  */
1997 static int early_boot_irqs_enabled;
1998
1999 void early_boot_irqs_off(void)
2000 {
2001         early_boot_irqs_enabled = 0;
2002 }
2003
2004 void early_boot_irqs_on(void)
2005 {
2006         early_boot_irqs_enabled = 1;
2007 }
2008
2009 /*
2010  * Hardirqs will be enabled:
2011  */
2012 void trace_hardirqs_on(void)
2013 {
2014         struct task_struct *curr = current;
2015         unsigned long ip;
2016
2017         if (unlikely(!debug_locks || current->lockdep_recursion))
2018                 return;
2019
2020         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2021                 return;
2022
2023         if (unlikely(curr->hardirqs_enabled)) {
2024                 debug_atomic_inc(&redundant_hardirqs_on);
2025                 return;
2026         }
2027         /* we'll do an OFF -> ON transition: */
2028         curr->hardirqs_enabled = 1;
2029         ip = (unsigned long) __builtin_return_address(0);
2030
2031         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2032                 return;
2033         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2034                 return;
2035         /*
2036          * We are going to turn hardirqs on, so set the
2037          * usage bit for all held locks:
2038          */
2039         if (!mark_held_locks(curr, 1))
2040                 return;
2041         /*
2042          * If we have softirqs enabled, then set the usage
2043          * bit for all held locks. (disabled hardirqs prevented
2044          * this bit from being set before)
2045          */
2046         if (curr->softirqs_enabled)
2047                 if (!mark_held_locks(curr, 0))
2048                         return;
2049
2050         curr->hardirq_enable_ip = ip;
2051         curr->hardirq_enable_event = ++curr->irq_events;
2052         debug_atomic_inc(&hardirqs_on_events);
2053 }
2054
2055 EXPORT_SYMBOL(trace_hardirqs_on);
2056
2057 /*
2058  * Hardirqs were disabled:
2059  */
2060 void trace_hardirqs_off(void)
2061 {
2062         struct task_struct *curr = current;
2063
2064         if (unlikely(!debug_locks || current->lockdep_recursion))
2065                 return;
2066
2067         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2068                 return;
2069
2070         if (curr->hardirqs_enabled) {
2071                 /*
2072                  * We have done an ON -> OFF transition:
2073                  */
2074                 curr->hardirqs_enabled = 0;
2075                 curr->hardirq_disable_ip = _RET_IP_;
2076                 curr->hardirq_disable_event = ++curr->irq_events;
2077                 debug_atomic_inc(&hardirqs_off_events);
2078         } else
2079                 debug_atomic_inc(&redundant_hardirqs_off);
2080 }
2081
2082 EXPORT_SYMBOL(trace_hardirqs_off);
2083
2084 /*
2085  * Softirqs will be enabled:
2086  */
2087 void trace_softirqs_on(unsigned long ip)
2088 {
2089         struct task_struct *curr = current;
2090
2091         if (unlikely(!debug_locks))
2092                 return;
2093
2094         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2095                 return;
2096
2097         if (curr->softirqs_enabled) {
2098                 debug_atomic_inc(&redundant_softirqs_on);
2099                 return;
2100         }
2101
2102         /*
2103          * We'll do an OFF -> ON transition:
2104          */
2105         curr->softirqs_enabled = 1;
2106         curr->softirq_enable_ip = ip;
2107         curr->softirq_enable_event = ++curr->irq_events;
2108         debug_atomic_inc(&softirqs_on_events);
2109         /*
2110          * We are going to turn softirqs on, so set the
2111          * usage bit for all held locks, if hardirqs are
2112          * enabled too:
2113          */
2114         if (curr->hardirqs_enabled)
2115                 mark_held_locks(curr, 0);
2116 }
2117
2118 /*
2119  * Softirqs were disabled:
2120  */
2121 void trace_softirqs_off(unsigned long ip)
2122 {
2123         struct task_struct *curr = current;
2124
2125         if (unlikely(!debug_locks))
2126                 return;
2127
2128         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2129                 return;
2130
2131         if (curr->softirqs_enabled) {
2132                 /*
2133                  * We have done an ON -> OFF transition:
2134                  */
2135                 curr->softirqs_enabled = 0;
2136                 curr->softirq_disable_ip = ip;
2137                 curr->softirq_disable_event = ++curr->irq_events;
2138                 debug_atomic_inc(&softirqs_off_events);
2139                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2140         } else
2141                 debug_atomic_inc(&redundant_softirqs_off);
2142 }
2143
2144 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2145 {
2146         /*
2147          * If non-trylock use in a hardirq or softirq context, then
2148          * mark the lock as used in these contexts:
2149          */
2150         if (!hlock->trylock) {
2151                 if (hlock->read) {
2152                         if (curr->hardirq_context)
2153                                 if (!mark_lock(curr, hlock,
2154                                                 LOCK_USED_IN_HARDIRQ_READ))
2155                                         return 0;
2156                         if (curr->softirq_context)
2157                                 if (!mark_lock(curr, hlock,
2158                                                 LOCK_USED_IN_SOFTIRQ_READ))
2159                                         return 0;
2160                 } else {
2161                         if (curr->hardirq_context)
2162                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2163                                         return 0;
2164                         if (curr->softirq_context)
2165                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2166                                         return 0;
2167                 }
2168         }
2169         if (!hlock->hardirqs_off) {
2170                 if (hlock->read) {
2171                         if (!mark_lock(curr, hlock,
2172                                         LOCK_ENABLED_HARDIRQS_READ))
2173                                 return 0;
2174                         if (curr->softirqs_enabled)
2175                                 if (!mark_lock(curr, hlock,
2176                                                 LOCK_ENABLED_SOFTIRQS_READ))
2177                                         return 0;
2178                 } else {
2179                         if (!mark_lock(curr, hlock,
2180                                         LOCK_ENABLED_HARDIRQS))
2181                                 return 0;
2182                         if (curr->softirqs_enabled)
2183                                 if (!mark_lock(curr, hlock,
2184                                                 LOCK_ENABLED_SOFTIRQS))
2185                                         return 0;
2186                 }
2187         }
2188
2189         return 1;
2190 }
2191
2192 static int separate_irq_context(struct task_struct *curr,
2193                 struct held_lock *hlock)
2194 {
2195         unsigned int depth = curr->lockdep_depth;
2196
2197         /*
2198          * Keep track of points where we cross into an interrupt context:
2199          */
2200         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2201                                 curr->softirq_context;
2202         if (depth) {
2203                 struct held_lock *prev_hlock;
2204
2205                 prev_hlock = curr->held_locks + depth-1;
2206                 /*
2207                  * If we cross into another context, reset the
2208                  * hash key (this also prevents the checking and the
2209                  * adding of the dependency to 'prev'):
2210                  */
2211                 if (prev_hlock->irq_context != hlock->irq_context)
2212                         return 1;
2213         }
2214         return 0;
2215 }
2216
2217 #else
2218
2219 static inline
2220 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2221                 enum lock_usage_bit new_bit)
2222 {
2223         WARN_ON(1);
2224         return 1;
2225 }
2226
2227 static inline int mark_irqflags(struct task_struct *curr,
2228                 struct held_lock *hlock)
2229 {
2230         return 1;
2231 }
2232
2233 static inline int separate_irq_context(struct task_struct *curr,
2234                 struct held_lock *hlock)
2235 {
2236         return 0;
2237 }
2238
2239 #endif
2240
2241 /*
2242  * Mark a lock with a usage bit, and validate the state transition:
2243  */
2244 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2245                      enum lock_usage_bit new_bit)
2246 {
2247         unsigned int new_mask = 1 << new_bit, ret = 1;
2248
2249         /*
2250          * If already set then do not dirty the cacheline,
2251          * nor do any checks:
2252          */
2253         if (likely(this->class->usage_mask & new_mask))
2254                 return 1;
2255
2256         if (!graph_lock())
2257                 return 0;
2258         /*
2259          * Make sure we didnt race:
2260          */
2261         if (unlikely(this->class->usage_mask & new_mask)) {
2262                 graph_unlock();
2263                 return 1;
2264         }
2265
2266         this->class->usage_mask |= new_mask;
2267
2268         if (!save_trace(this->class->usage_traces + new_bit))
2269                 return 0;
2270
2271         switch (new_bit) {
2272         case LOCK_USED_IN_HARDIRQ:
2273         case LOCK_USED_IN_SOFTIRQ:
2274         case LOCK_USED_IN_HARDIRQ_READ:
2275         case LOCK_USED_IN_SOFTIRQ_READ:
2276         case LOCK_ENABLED_HARDIRQS:
2277         case LOCK_ENABLED_SOFTIRQS:
2278         case LOCK_ENABLED_HARDIRQS_READ:
2279         case LOCK_ENABLED_SOFTIRQS_READ:
2280                 ret = mark_lock_irq(curr, this, new_bit);
2281                 if (!ret)
2282                         return 0;
2283                 break;
2284         case LOCK_USED:
2285                 /*
2286                  * Add it to the global list of classes:
2287                  */
2288                 list_add_tail_rcu(&this->class->lock_entry, &all_lock_classes);
2289                 debug_atomic_dec(&nr_unused_locks);
2290                 break;
2291         default:
2292                 if (!debug_locks_off_graph_unlock())
2293                         return 0;
2294                 WARN_ON(1);
2295                 return 0;
2296         }
2297
2298         graph_unlock();
2299
2300         /*
2301          * We must printk outside of the graph_lock:
2302          */
2303         if (ret == 2) {
2304                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2305                 print_lock(this);
2306                 print_irqtrace_events(curr);
2307                 dump_stack();
2308         }
2309
2310         return ret;
2311 }
2312
2313 /*
2314  * Initialize a lock instance's lock-class mapping info:
2315  */
2316 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2317                       struct lock_class_key *key, int subclass)
2318 {
2319         if (unlikely(!debug_locks))
2320                 return;
2321
2322         if (DEBUG_LOCKS_WARN_ON(!key))
2323                 return;
2324         if (DEBUG_LOCKS_WARN_ON(!name))
2325                 return;
2326         /*
2327          * Sanity check, the lock-class key must be persistent:
2328          */
2329         if (!static_obj(key)) {
2330                 printk("BUG: key %p not in .data!\n", key);
2331                 DEBUG_LOCKS_WARN_ON(1);
2332                 return;
2333         }
2334         lock->name = name;
2335         lock->key = key;
2336         lock->class_cache = NULL;
2337 #ifdef CONFIG_LOCK_STAT
2338         lock->cpu = raw_smp_processor_id();
2339 #endif
2340         if (subclass)
2341                 register_lock_class(lock, subclass, 1);
2342 }
2343
2344 EXPORT_SYMBOL_GPL(lockdep_init_map);
2345
2346 /*
2347  * This gets called for every mutex_lock*()/spin_lock*() operation.
2348  * We maintain the dependency maps and validate the locking attempt:
2349  */
2350 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2351                           int trylock, int read, int check, int hardirqs_off,
2352                           unsigned long ip)
2353 {
2354         struct task_struct *curr = current;
2355         struct lock_class *class = NULL;
2356         struct held_lock *hlock;
2357         unsigned int depth, id;
2358         int chain_head = 0;
2359         u64 chain_key;
2360
2361         if (!prove_locking)
2362                 check = 1;
2363
2364         if (unlikely(!debug_locks))
2365                 return 0;
2366
2367         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2368                 return 0;
2369
2370         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2371                 debug_locks_off();
2372                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2373                 printk("turning off the locking correctness validator.\n");
2374                 return 0;
2375         }
2376
2377         if (!subclass)
2378                 class = lock->class_cache;
2379         /*
2380          * Not cached yet or subclass?
2381          */
2382         if (unlikely(!class)) {
2383                 class = register_lock_class(lock, subclass, 0);
2384                 if (!class)
2385                         return 0;
2386         }
2387         debug_atomic_inc((atomic_t *)&class->ops);
2388         if (very_verbose(class)) {
2389                 printk("\nacquire class [%p] %s", class->key, class->name);
2390                 if (class->name_version > 1)
2391                         printk("#%d", class->name_version);
2392                 printk("\n");
2393                 dump_stack();
2394         }
2395
2396         /*
2397          * Add the lock to the list of currently held locks.
2398          * (we dont increase the depth just yet, up until the
2399          * dependency checks are done)
2400          */
2401         depth = curr->lockdep_depth;
2402         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2403                 return 0;
2404
2405         hlock = curr->held_locks + depth;
2406
2407         hlock->class = class;
2408         hlock->acquire_ip = ip;
2409         hlock->instance = lock;
2410         hlock->trylock = trylock;
2411         hlock->read = read;
2412         hlock->check = check;
2413         hlock->hardirqs_off = hardirqs_off;
2414 #ifdef CONFIG_LOCK_STAT
2415         hlock->waittime_stamp = 0;
2416         hlock->holdtime_stamp = sched_clock();
2417 #endif
2418
2419         if (check == 2 && !mark_irqflags(curr, hlock))
2420                 return 0;
2421
2422         /* mark it as used: */
2423         if (!mark_lock(curr, hlock, LOCK_USED))
2424                 return 0;
2425
2426         /*
2427          * Calculate the chain hash: it's the combined hash of all the
2428          * lock keys along the dependency chain. We save the hash value
2429          * at every step so that we can get the current hash easily
2430          * after unlock. The chain hash is then used to cache dependency
2431          * results.
2432          *
2433          * The 'key ID' is what is the most compact key value to drive
2434          * the hash, not class->key.
2435          */
2436         id = class - lock_classes;
2437         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2438                 return 0;
2439
2440         chain_key = curr->curr_chain_key;
2441         if (!depth) {
2442                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2443                         return 0;
2444                 chain_head = 1;
2445         }
2446
2447         hlock->prev_chain_key = chain_key;
2448         if (separate_irq_context(curr, hlock)) {
2449                 chain_key = 0;
2450                 chain_head = 1;
2451         }
2452         chain_key = iterate_chain_key(chain_key, id);
2453
2454         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2455                 return 0;
2456
2457         curr->curr_chain_key = chain_key;
2458         curr->lockdep_depth++;
2459         check_chain_key(curr);
2460 #ifdef CONFIG_DEBUG_LOCKDEP
2461         if (unlikely(!debug_locks))
2462                 return 0;
2463 #endif
2464         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2465                 debug_locks_off();
2466                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2467                 printk("turning off the locking correctness validator.\n");
2468                 return 0;
2469         }
2470
2471         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2472                 max_lockdep_depth = curr->lockdep_depth;
2473
2474         return 1;
2475 }
2476
2477 static int
2478 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2479                            unsigned long ip)
2480 {
2481         if (!debug_locks_off())
2482                 return 0;
2483         if (debug_locks_silent)
2484                 return 0;
2485
2486         printk("\n=====================================\n");
2487         printk(  "[ BUG: bad unlock balance detected! ]\n");
2488         printk(  "-------------------------------------\n");
2489         printk("%s/%d is trying to release lock (",
2490                 curr->comm, task_pid_nr(curr));
2491         print_lockdep_cache(lock);
2492         printk(") at:\n");
2493         print_ip_sym(ip);
2494         printk("but there are no more locks to release!\n");
2495         printk("\nother info that might help us debug this:\n");
2496         lockdep_print_held_locks(curr);
2497
2498         printk("\nstack backtrace:\n");
2499         dump_stack();
2500
2501         return 0;
2502 }
2503
2504 /*
2505  * Common debugging checks for both nested and non-nested unlock:
2506  */
2507 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2508                         unsigned long ip)
2509 {
2510         if (unlikely(!debug_locks))
2511                 return 0;
2512         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2513                 return 0;
2514
2515         if (curr->lockdep_depth <= 0)
2516                 return print_unlock_inbalance_bug(curr, lock, ip);
2517
2518         return 1;
2519 }
2520
2521 /*
2522  * Remove the lock to the list of currently held locks in a
2523  * potentially non-nested (out of order) manner. This is a
2524  * relatively rare operation, as all the unlock APIs default
2525  * to nested mode (which uses lock_release()):
2526  */
2527 static int
2528 lock_release_non_nested(struct task_struct *curr,
2529                         struct lockdep_map *lock, unsigned long ip)
2530 {
2531         struct held_lock *hlock, *prev_hlock;
2532         unsigned int depth;
2533         int i;
2534
2535         /*
2536          * Check whether the lock exists in the current stack
2537          * of held locks:
2538          */
2539         depth = curr->lockdep_depth;
2540         if (DEBUG_LOCKS_WARN_ON(!depth))
2541                 return 0;
2542
2543         prev_hlock = NULL;
2544         for (i = depth-1; i >= 0; i--) {
2545                 hlock = curr->held_locks + i;
2546                 /*
2547                  * We must not cross into another context:
2548                  */
2549                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2550                         break;
2551                 if (hlock->instance == lock)
2552                         goto found_it;
2553                 prev_hlock = hlock;
2554         }
2555         return print_unlock_inbalance_bug(curr, lock, ip);
2556
2557 found_it:
2558         lock_release_holdtime(hlock);
2559
2560         /*
2561          * We have the right lock to unlock, 'hlock' points to it.
2562          * Now we remove it from the stack, and add back the other
2563          * entries (if any), recalculating the hash along the way:
2564          */
2565         curr->lockdep_depth = i;
2566         curr->curr_chain_key = hlock->prev_chain_key;
2567
2568         for (i++; i < depth; i++) {
2569                 hlock = curr->held_locks + i;
2570                 if (!__lock_acquire(hlock->instance,
2571                         hlock->class->subclass, hlock->trylock,
2572                                 hlock->read, hlock->check, hlock->hardirqs_off,
2573                                 hlock->acquire_ip))
2574                         return 0;
2575         }
2576
2577         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2578                 return 0;
2579         return 1;
2580 }
2581
2582 /*
2583  * Remove the lock to the list of currently held locks - this gets
2584  * called on mutex_unlock()/spin_unlock*() (or on a failed
2585  * mutex_lock_interruptible()). This is done for unlocks that nest
2586  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2587  */
2588 static int lock_release_nested(struct task_struct *curr,
2589                                struct lockdep_map *lock, unsigned long ip)
2590 {
2591         struct held_lock *hlock;
2592         unsigned int depth;
2593
2594         /*
2595          * Pop off the top of the lock stack:
2596          */
2597         depth = curr->lockdep_depth - 1;
2598         hlock = curr->held_locks + depth;
2599
2600         /*
2601          * Is the unlock non-nested:
2602          */
2603         if (hlock->instance != lock)
2604                 return lock_release_non_nested(curr, lock, ip);
2605         curr->lockdep_depth--;
2606
2607         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2608                 return 0;
2609
2610         curr->curr_chain_key = hlock->prev_chain_key;
2611
2612         lock_release_holdtime(hlock);
2613
2614 #ifdef CONFIG_DEBUG_LOCKDEP
2615         hlock->prev_chain_key = 0;
2616         hlock->class = NULL;
2617         hlock->acquire_ip = 0;
2618         hlock->irq_context = 0;
2619 #endif
2620         return 1;
2621 }
2622
2623 /*
2624  * Remove the lock to the list of currently held locks - this gets
2625  * called on mutex_unlock()/spin_unlock*() (or on a failed
2626  * mutex_lock_interruptible()). This is done for unlocks that nest
2627  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2628  */
2629 static void
2630 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2631 {
2632         struct task_struct *curr = current;
2633
2634         if (!check_unlock(curr, lock, ip))
2635                 return;
2636
2637         if (nested) {
2638                 if (!lock_release_nested(curr, lock, ip))
2639                         return;
2640         } else {
2641                 if (!lock_release_non_nested(curr, lock, ip))
2642                         return;
2643         }
2644
2645         check_chain_key(curr);
2646 }
2647
2648 /*
2649  * Check whether we follow the irq-flags state precisely:
2650  */
2651 static void check_flags(unsigned long flags)
2652 {
2653 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2654         if (!debug_locks)
2655                 return;
2656
2657         if (irqs_disabled_flags(flags)) {
2658                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
2659                         printk("possible reason: unannotated irqs-off.\n");
2660                 }
2661         } else {
2662                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
2663                         printk("possible reason: unannotated irqs-on.\n");
2664                 }
2665         }
2666
2667         /*
2668          * We dont accurately track softirq state in e.g.
2669          * hardirq contexts (such as on 4KSTACKS), so only
2670          * check if not in hardirq contexts:
2671          */
2672         if (!hardirq_count()) {
2673                 if (softirq_count())
2674                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2675                 else
2676                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2677         }
2678
2679         if (!debug_locks)
2680                 print_irqtrace_events(current);
2681 #endif
2682 }
2683
2684 /*
2685  * We are not always called with irqs disabled - do that here,
2686  * and also avoid lockdep recursion:
2687  */
2688 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2689                   int trylock, int read, int check, unsigned long ip)
2690 {
2691         unsigned long flags;
2692
2693         if (unlikely(!lock_stat && !prove_locking))
2694                 return;
2695
2696         if (unlikely(current->lockdep_recursion))
2697                 return;
2698
2699         raw_local_irq_save(flags);
2700         check_flags(flags);
2701
2702         current->lockdep_recursion = 1;
2703         __lock_acquire(lock, subclass, trylock, read, check,
2704                        irqs_disabled_flags(flags), ip);
2705         current->lockdep_recursion = 0;
2706         raw_local_irq_restore(flags);
2707 }
2708
2709 EXPORT_SYMBOL_GPL(lock_acquire);
2710
2711 void lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2712 {
2713         unsigned long flags;
2714
2715         if (unlikely(!lock_stat && !prove_locking))
2716                 return;
2717
2718         if (unlikely(current->lockdep_recursion))
2719                 return;
2720
2721         raw_local_irq_save(flags);
2722         check_flags(flags);
2723         current->lockdep_recursion = 1;
2724         __lock_release(lock, nested, ip);
2725         current->lockdep_recursion = 0;
2726         raw_local_irq_restore(flags);
2727 }
2728
2729 EXPORT_SYMBOL_GPL(lock_release);
2730
2731 #ifdef CONFIG_LOCK_STAT
2732 static int
2733 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
2734                            unsigned long ip)
2735 {
2736         if (!debug_locks_off())
2737                 return 0;
2738         if (debug_locks_silent)
2739                 return 0;
2740
2741         printk("\n=================================\n");
2742         printk(  "[ BUG: bad contention detected! ]\n");
2743         printk(  "---------------------------------\n");
2744         printk("%s/%d is trying to contend lock (",
2745                 curr->comm, task_pid_nr(curr));
2746         print_lockdep_cache(lock);
2747         printk(") at:\n");
2748         print_ip_sym(ip);
2749         printk("but there are no locks held!\n");
2750         printk("\nother info that might help us debug this:\n");
2751         lockdep_print_held_locks(curr);
2752
2753         printk("\nstack backtrace:\n");
2754         dump_stack();
2755
2756         return 0;
2757 }
2758
2759 static void
2760 __lock_contended(struct lockdep_map *lock, unsigned long ip)
2761 {
2762         struct task_struct *curr = current;
2763         struct held_lock *hlock, *prev_hlock;
2764         struct lock_class_stats *stats;
2765         unsigned int depth;
2766         int i, point;
2767
2768         depth = curr->lockdep_depth;
2769         if (DEBUG_LOCKS_WARN_ON(!depth))
2770                 return;
2771
2772         prev_hlock = NULL;
2773         for (i = depth-1; i >= 0; i--) {
2774                 hlock = curr->held_locks + i;
2775                 /*
2776                  * We must not cross into another context:
2777                  */
2778                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2779                         break;
2780                 if (hlock->instance == lock)
2781                         goto found_it;
2782                 prev_hlock = hlock;
2783         }
2784         print_lock_contention_bug(curr, lock, ip);
2785         return;
2786
2787 found_it:
2788         hlock->waittime_stamp = sched_clock();
2789
2790         point = lock_contention_point(hlock->class, ip);
2791
2792         stats = get_lock_stats(hlock->class);
2793         if (point < ARRAY_SIZE(stats->contention_point))
2794                 stats->contention_point[i]++;
2795         if (lock->cpu != smp_processor_id())
2796                 stats->bounces[bounce_contended + !!hlock->read]++;
2797         put_lock_stats(stats);
2798 }
2799
2800 static void
2801 __lock_acquired(struct lockdep_map *lock)
2802 {
2803         struct task_struct *curr = current;
2804         struct held_lock *hlock, *prev_hlock;
2805         struct lock_class_stats *stats;
2806         unsigned int depth;
2807         u64 now;
2808         s64 waittime = 0;
2809         int i, cpu;
2810
2811         depth = curr->lockdep_depth;
2812         if (DEBUG_LOCKS_WARN_ON(!depth))
2813                 return;
2814
2815         prev_hlock = NULL;
2816         for (i = depth-1; i >= 0; i--) {
2817                 hlock = curr->held_locks + i;
2818                 /*
2819                  * We must not cross into another context:
2820                  */
2821                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2822                         break;
2823                 if (hlock->instance == lock)
2824                         goto found_it;
2825                 prev_hlock = hlock;
2826         }
2827         print_lock_contention_bug(curr, lock, _RET_IP_);
2828         return;
2829
2830 found_it:
2831         cpu = smp_processor_id();
2832         if (hlock->waittime_stamp) {
2833                 now = sched_clock();
2834                 waittime = now - hlock->waittime_stamp;
2835                 hlock->holdtime_stamp = now;
2836         }
2837
2838         stats = get_lock_stats(hlock->class);
2839         if (waittime) {
2840                 if (hlock->read)
2841                         lock_time_inc(&stats->read_waittime, waittime);
2842                 else
2843                         lock_time_inc(&stats->write_waittime, waittime);
2844         }
2845         if (lock->cpu != cpu)
2846                 stats->bounces[bounce_acquired + !!hlock->read]++;
2847         put_lock_stats(stats);
2848
2849         lock->cpu = cpu;
2850 }
2851
2852 void lock_contended(struct lockdep_map *lock, unsigned long ip)
2853 {
2854         unsigned long flags;
2855
2856         if (unlikely(!lock_stat))
2857                 return;
2858
2859         if (unlikely(current->lockdep_recursion))
2860                 return;
2861
2862         raw_local_irq_save(flags);
2863         check_flags(flags);
2864         current->lockdep_recursion = 1;
2865         __lock_contended(lock, ip);
2866         current->lockdep_recursion = 0;
2867         raw_local_irq_restore(flags);
2868 }
2869 EXPORT_SYMBOL_GPL(lock_contended);
2870
2871 void lock_acquired(struct lockdep_map *lock)
2872 {
2873         unsigned long flags;
2874
2875         if (unlikely(!lock_stat))
2876                 return;
2877
2878         if (unlikely(current->lockdep_recursion))
2879                 return;
2880
2881         raw_local_irq_save(flags);
2882         check_flags(flags);
2883         current->lockdep_recursion = 1;
2884         __lock_acquired(lock);
2885         current->lockdep_recursion = 0;
2886         raw_local_irq_restore(flags);
2887 }
2888 EXPORT_SYMBOL_GPL(lock_acquired);
2889 #endif
2890
2891 /*
2892  * Used by the testsuite, sanitize the validator state
2893  * after a simulated failure:
2894  */
2895
2896 void lockdep_reset(void)
2897 {
2898         unsigned long flags;
2899         int i;
2900
2901         raw_local_irq_save(flags);
2902         current->curr_chain_key = 0;
2903         current->lockdep_depth = 0;
2904         current->lockdep_recursion = 0;
2905         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
2906         nr_hardirq_chains = 0;
2907         nr_softirq_chains = 0;
2908         nr_process_chains = 0;
2909         debug_locks = 1;
2910         for (i = 0; i < CHAINHASH_SIZE; i++)
2911                 INIT_LIST_HEAD(chainhash_table + i);
2912         raw_local_irq_restore(flags);
2913 }
2914
2915 static void zap_class(struct lock_class *class)
2916 {
2917         int i;
2918
2919         /*
2920          * Remove all dependencies this lock is
2921          * involved in:
2922          */
2923         for (i = 0; i < nr_list_entries; i++) {
2924                 if (list_entries[i].class == class)
2925                         list_del_rcu(&list_entries[i].entry);
2926         }
2927         /*
2928          * Unhash the class and remove it from the all_lock_classes list:
2929          */
2930         list_del_rcu(&class->hash_entry);
2931         list_del_rcu(&class->lock_entry);
2932
2933 }
2934
2935 static inline int within(void *addr, void *start, unsigned long size)
2936 {
2937         return addr >= start && addr < start + size;
2938 }
2939
2940 void lockdep_free_key_range(void *start, unsigned long size)
2941 {
2942         struct lock_class *class, *next;
2943         struct list_head *head;
2944         unsigned long flags;
2945         int i;
2946         int locked;
2947
2948         raw_local_irq_save(flags);
2949         locked = graph_lock();
2950
2951         /*
2952          * Unhash all classes that were created by this module:
2953          */
2954         for (i = 0; i < CLASSHASH_SIZE; i++) {
2955                 head = classhash_table + i;
2956                 if (list_empty(head))
2957                         continue;
2958                 list_for_each_entry_safe(class, next, head, hash_entry)
2959                         if (within(class->key, start, size))
2960                                 zap_class(class);
2961         }
2962
2963         if (locked)
2964                 graph_unlock();
2965         raw_local_irq_restore(flags);
2966 }
2967
2968 void lockdep_reset_lock(struct lockdep_map *lock)
2969 {
2970         struct lock_class *class, *next;
2971         struct list_head *head;
2972         unsigned long flags;
2973         int i, j;
2974         int locked;
2975
2976         raw_local_irq_save(flags);
2977
2978         /*
2979          * Remove all classes this lock might have:
2980          */
2981         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
2982                 /*
2983                  * If the class exists we look it up and zap it:
2984                  */
2985                 class = look_up_lock_class(lock, j);
2986                 if (class)
2987                         zap_class(class);
2988         }
2989         /*
2990          * Debug check: in the end all mapped classes should
2991          * be gone.
2992          */
2993         locked = graph_lock();
2994         for (i = 0; i < CLASSHASH_SIZE; i++) {
2995                 head = classhash_table + i;
2996                 if (list_empty(head))
2997                         continue;
2998                 list_for_each_entry_safe(class, next, head, hash_entry) {
2999                         if (unlikely(class == lock->class_cache)) {
3000                                 if (debug_locks_off_graph_unlock())
3001                                         WARN_ON(1);
3002                                 goto out_restore;
3003                         }
3004                 }
3005         }
3006         if (locked)
3007                 graph_unlock();
3008
3009 out_restore:
3010         raw_local_irq_restore(flags);
3011 }
3012
3013 void lockdep_init(void)
3014 {
3015         int i;
3016
3017         /*
3018          * Some architectures have their own start_kernel()
3019          * code which calls lockdep_init(), while we also
3020          * call lockdep_init() from the start_kernel() itself,
3021          * and we want to initialize the hashes only once:
3022          */
3023         if (lockdep_initialized)
3024                 return;
3025
3026         for (i = 0; i < CLASSHASH_SIZE; i++)
3027                 INIT_LIST_HEAD(classhash_table + i);
3028
3029         for (i = 0; i < CHAINHASH_SIZE; i++)
3030                 INIT_LIST_HEAD(chainhash_table + i);
3031
3032         lockdep_initialized = 1;
3033 }
3034
3035 void __init lockdep_info(void)
3036 {
3037         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3038
3039         printk("... MAX_LOCKDEP_SUBCLASSES:    %lu\n", MAX_LOCKDEP_SUBCLASSES);
3040         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3041         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3042         printk("... CLASSHASH_SIZE:           %lu\n", CLASSHASH_SIZE);
3043         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3044         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3045         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3046
3047         printk(" memory used by lock dependency info: %lu kB\n",
3048                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3049                 sizeof(struct list_head) * CLASSHASH_SIZE +
3050                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3051                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3052                 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
3053
3054         printk(" per task-struct memory footprint: %lu bytes\n",
3055                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3056
3057 #ifdef CONFIG_DEBUG_LOCKDEP
3058         if (lockdep_init_error) {
3059                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3060                 printk("Call stack leading to lockdep invocation was:\n");
3061                 print_stack_trace(&lockdep_init_trace, 0);
3062         }
3063 #endif
3064 }
3065
3066 static void
3067 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3068                      const void *mem_to, struct held_lock *hlock)
3069 {
3070         if (!debug_locks_off())
3071                 return;
3072         if (debug_locks_silent)
3073                 return;
3074
3075         printk("\n=========================\n");
3076         printk(  "[ BUG: held lock freed! ]\n");
3077         printk(  "-------------------------\n");
3078         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3079                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3080         print_lock(hlock);
3081         lockdep_print_held_locks(curr);
3082
3083         printk("\nstack backtrace:\n");
3084         dump_stack();
3085 }
3086
3087 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3088                                 const void* lock_from, unsigned long lock_len)
3089 {
3090         return lock_from + lock_len <= mem_from ||
3091                 mem_from + mem_len <= lock_from;
3092 }
3093
3094 /*
3095  * Called when kernel memory is freed (or unmapped), or if a lock
3096  * is destroyed or reinitialized - this code checks whether there is
3097  * any held lock in the memory range of <from> to <to>:
3098  */
3099 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3100 {
3101         struct task_struct *curr = current;
3102         struct held_lock *hlock;
3103         unsigned long flags;
3104         int i;
3105
3106         if (unlikely(!debug_locks))
3107                 return;
3108
3109         local_irq_save(flags);
3110         for (i = 0; i < curr->lockdep_depth; i++) {
3111                 hlock = curr->held_locks + i;
3112
3113                 if (not_in_range(mem_from, mem_len, hlock->instance,
3114                                         sizeof(*hlock->instance)))
3115                         continue;
3116
3117                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3118                 break;
3119         }
3120         local_irq_restore(flags);
3121 }
3122 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3123
3124 static void print_held_locks_bug(struct task_struct *curr)
3125 {
3126         if (!debug_locks_off())
3127                 return;
3128         if (debug_locks_silent)
3129                 return;
3130
3131         printk("\n=====================================\n");
3132         printk(  "[ BUG: lock held at task exit time! ]\n");
3133         printk(  "-------------------------------------\n");
3134         printk("%s/%d is exiting with locks still held!\n",
3135                 curr->comm, task_pid_nr(curr));
3136         lockdep_print_held_locks(curr);
3137
3138         printk("\nstack backtrace:\n");
3139         dump_stack();
3140 }
3141
3142 void debug_check_no_locks_held(struct task_struct *task)
3143 {
3144         if (unlikely(task->lockdep_depth > 0))
3145                 print_held_locks_bug(task);
3146 }
3147
3148 void debug_show_all_locks(void)
3149 {
3150         struct task_struct *g, *p;
3151         int count = 10;
3152         int unlock = 1;
3153
3154         if (unlikely(!debug_locks)) {
3155                 printk("INFO: lockdep is turned off.\n");
3156                 return;
3157         }
3158         printk("\nShowing all locks held in the system:\n");
3159
3160         /*
3161          * Here we try to get the tasklist_lock as hard as possible,
3162          * if not successful after 2 seconds we ignore it (but keep
3163          * trying). This is to enable a debug printout even if a
3164          * tasklist_lock-holding task deadlocks or crashes.
3165          */
3166 retry:
3167         if (!read_trylock(&tasklist_lock)) {
3168                 if (count == 10)
3169                         printk("hm, tasklist_lock locked, retrying... ");
3170                 if (count) {
3171                         count--;
3172                         printk(" #%d", 10-count);
3173                         mdelay(200);
3174                         goto retry;
3175                 }
3176                 printk(" ignoring it.\n");
3177                 unlock = 0;
3178         }
3179         if (count != 10)
3180                 printk(" locked it.\n");
3181
3182         do_each_thread(g, p) {
3183                 /*
3184                  * It's not reliable to print a task's held locks
3185                  * if it's not sleeping (or if it's not the current
3186                  * task):
3187                  */
3188                 if (p->state == TASK_RUNNING && p != current)
3189                         continue;
3190                 if (p->lockdep_depth)
3191                         lockdep_print_held_locks(p);
3192                 if (!unlock)
3193                         if (read_trylock(&tasklist_lock))
3194                                 unlock = 1;
3195         } while_each_thread(g, p);
3196
3197         printk("\n");
3198         printk("=============================================\n\n");
3199
3200         if (unlock)
3201                 read_unlock(&tasklist_lock);
3202 }
3203
3204 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3205
3206 void debug_show_held_locks(struct task_struct *task)
3207 {
3208         if (unlikely(!debug_locks)) {
3209                 printk("INFO: lockdep is turned off.\n");
3210                 return;
3211         }
3212         lockdep_print_held_locks(task);
3213 }
3214
3215 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3216
3217 void lockdep_sys_exit(void)
3218 {
3219         struct task_struct *curr = current;
3220
3221         if (unlikely(curr->lockdep_depth)) {
3222                 if (!debug_locks_off())
3223                         return;
3224                 printk("\n================================================\n");
3225                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3226                 printk(  "------------------------------------------------\n");
3227                 printk("%s/%d is leaving the kernel with locks still held!\n",
3228                                 curr->comm, curr->pid);
3229                 lockdep_print_held_locks(curr);
3230         }
3231 }