7553a28b99cdd3b832eec916b5f3a2f9ea84157a
[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          * Add it to the global list of classes:
784          */
785         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
786
787         if (verbose(class)) {
788                 graph_unlock();
789                 raw_local_irq_restore(flags);
790
791                 printk("\nnew class %p: %s", class->key, class->name);
792                 if (class->name_version > 1)
793                         printk("#%d", class->name_version);
794                 printk("\n");
795                 dump_stack();
796
797                 raw_local_irq_save(flags);
798                 if (!graph_lock()) {
799                         raw_local_irq_restore(flags);
800                         return NULL;
801                 }
802         }
803 out_unlock_set:
804         graph_unlock();
805         raw_local_irq_restore(flags);
806
807         if (!subclass || force)
808                 lock->class_cache = class;
809
810         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
811                 return NULL;
812
813         return class;
814 }
815
816 #ifdef CONFIG_PROVE_LOCKING
817 /*
818  * Allocate a lockdep entry. (assumes the graph_lock held, returns
819  * with NULL on failure)
820  */
821 static struct lock_list *alloc_list_entry(void)
822 {
823         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
824                 if (!debug_locks_off_graph_unlock())
825                         return NULL;
826
827                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
828                 printk("turning off the locking correctness validator.\n");
829                 return NULL;
830         }
831         return list_entries + nr_list_entries++;
832 }
833
834 /*
835  * Add a new dependency to the head of the list:
836  */
837 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
838                             struct list_head *head, unsigned long ip, int distance)
839 {
840         struct lock_list *entry;
841         /*
842          * Lock not present yet - get a new dependency struct and
843          * add it to the list:
844          */
845         entry = alloc_list_entry();
846         if (!entry)
847                 return 0;
848
849         entry->class = this;
850         entry->distance = distance;
851         if (!save_trace(&entry->trace))
852                 return 0;
853
854         /*
855          * Since we never remove from the dependency list, the list can
856          * be walked lockless by other CPUs, it's only allocation
857          * that must be protected by the spinlock. But this also means
858          * we must make new entries visible only once writes to the
859          * entry become visible - hence the RCU op:
860          */
861         list_add_tail_rcu(&entry->entry, head);
862
863         return 1;
864 }
865
866 /*
867  * Recursive, forwards-direction lock-dependency checking, used for
868  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
869  * checking.
870  *
871  * (to keep the stackframe of the recursive functions small we
872  *  use these global variables, and we also mark various helper
873  *  functions as noinline.)
874  */
875 static struct held_lock *check_source, *check_target;
876
877 /*
878  * Print a dependency chain entry (this is only done when a deadlock
879  * has been detected):
880  */
881 static noinline int
882 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
883 {
884         if (debug_locks_silent)
885                 return 0;
886         printk("\n-> #%u", depth);
887         print_lock_name(target->class);
888         printk(":\n");
889         print_stack_trace(&target->trace, 6);
890
891         return 0;
892 }
893
894 /*
895  * When a circular dependency is detected, print the
896  * header first:
897  */
898 static noinline int
899 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
900 {
901         struct task_struct *curr = current;
902
903         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
904                 return 0;
905
906         printk("\n=======================================================\n");
907         printk(  "[ INFO: possible circular locking dependency detected ]\n");
908         print_kernel_version();
909         printk(  "-------------------------------------------------------\n");
910         printk("%s/%d is trying to acquire lock:\n",
911                 curr->comm, task_pid_nr(curr));
912         print_lock(check_source);
913         printk("\nbut task is already holding lock:\n");
914         print_lock(check_target);
915         printk("\nwhich lock already depends on the new lock.\n\n");
916         printk("\nthe existing dependency chain (in reverse order) is:\n");
917
918         print_circular_bug_entry(entry, depth);
919
920         return 0;
921 }
922
923 static noinline int print_circular_bug_tail(void)
924 {
925         struct task_struct *curr = current;
926         struct lock_list this;
927
928         if (debug_locks_silent)
929                 return 0;
930
931         this.class = check_source->class;
932         if (!save_trace(&this.trace))
933                 return 0;
934
935         print_circular_bug_entry(&this, 0);
936
937         printk("\nother info that might help us debug this:\n\n");
938         lockdep_print_held_locks(curr);
939
940         printk("\nstack backtrace:\n");
941         dump_stack();
942
943         return 0;
944 }
945
946 #define RECURSION_LIMIT 40
947
948 static int noinline print_infinite_recursion_bug(void)
949 {
950         if (!debug_locks_off_graph_unlock())
951                 return 0;
952
953         WARN_ON(1);
954
955         return 0;
956 }
957
958 /*
959  * Prove that the dependency graph starting at <entry> can not
960  * lead to <target>. Print an error and return 0 if it does.
961  */
962 static noinline int
963 check_noncircular(struct lock_class *source, unsigned int depth)
964 {
965         struct lock_list *entry;
966
967         debug_atomic_inc(&nr_cyclic_check_recursions);
968         if (depth > max_recursion_depth)
969                 max_recursion_depth = depth;
970         if (depth >= RECURSION_LIMIT)
971                 return print_infinite_recursion_bug();
972         /*
973          * Check this lock's dependency list:
974          */
975         list_for_each_entry(entry, &source->locks_after, entry) {
976                 if (entry->class == check_target->class)
977                         return print_circular_bug_header(entry, depth+1);
978                 debug_atomic_inc(&nr_cyclic_checks);
979                 if (!check_noncircular(entry->class, depth+1))
980                         return print_circular_bug_entry(entry, depth+1);
981         }
982         return 1;
983 }
984
985 #ifdef CONFIG_TRACE_IRQFLAGS
986 /*
987  * Forwards and backwards subgraph searching, for the purposes of
988  * proving that two subgraphs can be connected by a new dependency
989  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
990  */
991 static enum lock_usage_bit find_usage_bit;
992 static struct lock_class *forwards_match, *backwards_match;
993
994 /*
995  * Find a node in the forwards-direction dependency sub-graph starting
996  * at <source> that matches <find_usage_bit>.
997  *
998  * Return 2 if such a node exists in the subgraph, and put that node
999  * into <forwards_match>.
1000  *
1001  * Return 1 otherwise and keep <forwards_match> unchanged.
1002  * Return 0 on error.
1003  */
1004 static noinline int
1005 find_usage_forwards(struct lock_class *source, unsigned int depth)
1006 {
1007         struct lock_list *entry;
1008         int ret;
1009
1010         if (depth > max_recursion_depth)
1011                 max_recursion_depth = depth;
1012         if (depth >= RECURSION_LIMIT)
1013                 return print_infinite_recursion_bug();
1014
1015         debug_atomic_inc(&nr_find_usage_forwards_checks);
1016         if (source->usage_mask & (1 << find_usage_bit)) {
1017                 forwards_match = source;
1018                 return 2;
1019         }
1020
1021         /*
1022          * Check this lock's dependency list:
1023          */
1024         list_for_each_entry(entry, &source->locks_after, entry) {
1025                 debug_atomic_inc(&nr_find_usage_forwards_recursions);
1026                 ret = find_usage_forwards(entry->class, depth+1);
1027                 if (ret == 2 || ret == 0)
1028                         return ret;
1029         }
1030         return 1;
1031 }
1032
1033 /*
1034  * Find a node in the backwards-direction dependency sub-graph starting
1035  * at <source> that matches <find_usage_bit>.
1036  *
1037  * Return 2 if such a node exists in the subgraph, and put that node
1038  * into <backwards_match>.
1039  *
1040  * Return 1 otherwise and keep <backwards_match> unchanged.
1041  * Return 0 on error.
1042  */
1043 static noinline int
1044 find_usage_backwards(struct lock_class *source, unsigned int depth)
1045 {
1046         struct lock_list *entry;
1047         int ret;
1048
1049         if (!__raw_spin_is_locked(&lockdep_lock))
1050                 return DEBUG_LOCKS_WARN_ON(1);
1051
1052         if (depth > max_recursion_depth)
1053                 max_recursion_depth = depth;
1054         if (depth >= RECURSION_LIMIT)
1055                 return print_infinite_recursion_bug();
1056
1057         debug_atomic_inc(&nr_find_usage_backwards_checks);
1058         if (source->usage_mask & (1 << find_usage_bit)) {
1059                 backwards_match = source;
1060                 return 2;
1061         }
1062
1063         /*
1064          * Check this lock's dependency list:
1065          */
1066         list_for_each_entry(entry, &source->locks_before, entry) {
1067                 debug_atomic_inc(&nr_find_usage_backwards_recursions);
1068                 ret = find_usage_backwards(entry->class, depth+1);
1069                 if (ret == 2 || ret == 0)
1070                         return ret;
1071         }
1072         return 1;
1073 }
1074
1075 static int
1076 print_bad_irq_dependency(struct task_struct *curr,
1077                          struct held_lock *prev,
1078                          struct held_lock *next,
1079                          enum lock_usage_bit bit1,
1080                          enum lock_usage_bit bit2,
1081                          const char *irqclass)
1082 {
1083         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1084                 return 0;
1085
1086         printk("\n======================================================\n");
1087         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1088                 irqclass, irqclass);
1089         print_kernel_version();
1090         printk(  "------------------------------------------------------\n");
1091         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1092                 curr->comm, task_pid_nr(curr),
1093                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1094                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1095                 curr->hardirqs_enabled,
1096                 curr->softirqs_enabled);
1097         print_lock(next);
1098
1099         printk("\nand this task is already holding:\n");
1100         print_lock(prev);
1101         printk("which would create a new lock dependency:\n");
1102         print_lock_name(prev->class);
1103         printk(" ->");
1104         print_lock_name(next->class);
1105         printk("\n");
1106
1107         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1108                 irqclass);
1109         print_lock_name(backwards_match);
1110         printk("\n... which became %s-irq-safe at:\n", irqclass);
1111
1112         print_stack_trace(backwards_match->usage_traces + bit1, 1);
1113
1114         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1115         print_lock_name(forwards_match);
1116         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1117         printk("...");
1118
1119         print_stack_trace(forwards_match->usage_traces + bit2, 1);
1120
1121         printk("\nother info that might help us debug this:\n\n");
1122         lockdep_print_held_locks(curr);
1123
1124         printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1125         print_lock_dependencies(backwards_match, 0);
1126
1127         printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1128         print_lock_dependencies(forwards_match, 0);
1129
1130         printk("\nstack backtrace:\n");
1131         dump_stack();
1132
1133         return 0;
1134 }
1135
1136 static int
1137 check_usage(struct task_struct *curr, struct held_lock *prev,
1138             struct held_lock *next, enum lock_usage_bit bit_backwards,
1139             enum lock_usage_bit bit_forwards, const char *irqclass)
1140 {
1141         int ret;
1142
1143         find_usage_bit = bit_backwards;
1144         /* fills in <backwards_match> */
1145         ret = find_usage_backwards(prev->class, 0);
1146         if (!ret || ret == 1)
1147                 return ret;
1148
1149         find_usage_bit = bit_forwards;
1150         ret = find_usage_forwards(next->class, 0);
1151         if (!ret || ret == 1)
1152                 return ret;
1153         /* ret == 2 */
1154         return print_bad_irq_dependency(curr, prev, next,
1155                         bit_backwards, bit_forwards, irqclass);
1156 }
1157
1158 static int
1159 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1160                 struct held_lock *next)
1161 {
1162         /*
1163          * Prove that the new dependency does not connect a hardirq-safe
1164          * lock with a hardirq-unsafe lock - to achieve this we search
1165          * the backwards-subgraph starting at <prev>, and the
1166          * forwards-subgraph starting at <next>:
1167          */
1168         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
1169                                         LOCK_ENABLED_HARDIRQS, "hard"))
1170                 return 0;
1171
1172         /*
1173          * Prove that the new dependency does not connect a hardirq-safe-read
1174          * lock with a hardirq-unsafe lock - to achieve this we search
1175          * the backwards-subgraph starting at <prev>, and the
1176          * forwards-subgraph starting at <next>:
1177          */
1178         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
1179                                         LOCK_ENABLED_HARDIRQS, "hard-read"))
1180                 return 0;
1181
1182         /*
1183          * Prove that the new dependency does not connect a softirq-safe
1184          * lock with a softirq-unsafe lock - to achieve this we search
1185          * the backwards-subgraph starting at <prev>, and the
1186          * forwards-subgraph starting at <next>:
1187          */
1188         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
1189                                         LOCK_ENABLED_SOFTIRQS, "soft"))
1190                 return 0;
1191         /*
1192          * Prove that the new dependency does not connect a softirq-safe-read
1193          * lock with a softirq-unsafe lock - to achieve this we search
1194          * the backwards-subgraph starting at <prev>, and the
1195          * forwards-subgraph starting at <next>:
1196          */
1197         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
1198                                         LOCK_ENABLED_SOFTIRQS, "soft"))
1199                 return 0;
1200
1201         return 1;
1202 }
1203
1204 static void inc_chains(void)
1205 {
1206         if (current->hardirq_context)
1207                 nr_hardirq_chains++;
1208         else {
1209                 if (current->softirq_context)
1210                         nr_softirq_chains++;
1211                 else
1212                         nr_process_chains++;
1213         }
1214 }
1215
1216 #else
1217
1218 static inline int
1219 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1220                 struct held_lock *next)
1221 {
1222         return 1;
1223 }
1224
1225 static inline void inc_chains(void)
1226 {
1227         nr_process_chains++;
1228 }
1229
1230 #endif
1231
1232 static int
1233 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1234                    struct held_lock *next)
1235 {
1236         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1237                 return 0;
1238
1239         printk("\n=============================================\n");
1240         printk(  "[ INFO: possible recursive locking detected ]\n");
1241         print_kernel_version();
1242         printk(  "---------------------------------------------\n");
1243         printk("%s/%d is trying to acquire lock:\n",
1244                 curr->comm, task_pid_nr(curr));
1245         print_lock(next);
1246         printk("\nbut task is already holding lock:\n");
1247         print_lock(prev);
1248
1249         printk("\nother info that might help us debug this:\n");
1250         lockdep_print_held_locks(curr);
1251
1252         printk("\nstack backtrace:\n");
1253         dump_stack();
1254
1255         return 0;
1256 }
1257
1258 /*
1259  * Check whether we are holding such a class already.
1260  *
1261  * (Note that this has to be done separately, because the graph cannot
1262  * detect such classes of deadlocks.)
1263  *
1264  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1265  */
1266 static int
1267 check_deadlock(struct task_struct *curr, struct held_lock *next,
1268                struct lockdep_map *next_instance, int read)
1269 {
1270         struct held_lock *prev;
1271         int i;
1272
1273         for (i = 0; i < curr->lockdep_depth; i++) {
1274                 prev = curr->held_locks + i;
1275                 if (prev->class != next->class)
1276                         continue;
1277                 /*
1278                  * Allow read-after-read recursion of the same
1279                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1280                  */
1281                 if ((read == 2) && prev->read)
1282                         return 2;
1283                 return print_deadlock_bug(curr, prev, next);
1284         }
1285         return 1;
1286 }
1287
1288 /*
1289  * There was a chain-cache miss, and we are about to add a new dependency
1290  * to a previous lock. We recursively validate the following rules:
1291  *
1292  *  - would the adding of the <prev> -> <next> dependency create a
1293  *    circular dependency in the graph? [== circular deadlock]
1294  *
1295  *  - does the new prev->next dependency connect any hardirq-safe lock
1296  *    (in the full backwards-subgraph starting at <prev>) with any
1297  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1298  *    <next>)? [== illegal lock inversion with hardirq contexts]
1299  *
1300  *  - does the new prev->next dependency connect any softirq-safe lock
1301  *    (in the full backwards-subgraph starting at <prev>) with any
1302  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1303  *    <next>)? [== illegal lock inversion with softirq contexts]
1304  *
1305  * any of these scenarios could lead to a deadlock.
1306  *
1307  * Then if all the validations pass, we add the forwards and backwards
1308  * dependency.
1309  */
1310 static int
1311 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1312                struct held_lock *next, int distance)
1313 {
1314         struct lock_list *entry;
1315         int ret;
1316
1317         /*
1318          * Prove that the new <prev> -> <next> dependency would not
1319          * create a circular dependency in the graph. (We do this by
1320          * forward-recursing into the graph starting at <next>, and
1321          * checking whether we can reach <prev>.)
1322          *
1323          * We are using global variables to control the recursion, to
1324          * keep the stackframe size of the recursive functions low:
1325          */
1326         check_source = next;
1327         check_target = prev;
1328         if (!(check_noncircular(next->class, 0)))
1329                 return print_circular_bug_tail();
1330
1331         if (!check_prev_add_irq(curr, prev, next))
1332                 return 0;
1333
1334         /*
1335          * For recursive read-locks we do all the dependency checks,
1336          * but we dont store read-triggered dependencies (only
1337          * write-triggered dependencies). This ensures that only the
1338          * write-side dependencies matter, and that if for example a
1339          * write-lock never takes any other locks, then the reads are
1340          * equivalent to a NOP.
1341          */
1342         if (next->read == 2 || prev->read == 2)
1343                 return 1;
1344         /*
1345          * Is the <prev> -> <next> dependency already present?
1346          *
1347          * (this may occur even though this is a new chain: consider
1348          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1349          *  chains - the second one will be new, but L1 already has
1350          *  L2 added to its dependency list, due to the first chain.)
1351          */
1352         list_for_each_entry(entry, &prev->class->locks_after, entry) {
1353                 if (entry->class == next->class) {
1354                         if (distance == 1)
1355                                 entry->distance = 1;
1356                         return 2;
1357                 }
1358         }
1359
1360         /*
1361          * Ok, all validations passed, add the new lock
1362          * to the previous lock's dependency list:
1363          */
1364         ret = add_lock_to_list(prev->class, next->class,
1365                                &prev->class->locks_after, next->acquire_ip, distance);
1366
1367         if (!ret)
1368                 return 0;
1369
1370         ret = add_lock_to_list(next->class, prev->class,
1371                                &next->class->locks_before, next->acquire_ip, distance);
1372         if (!ret)
1373                 return 0;
1374
1375         /*
1376          * Debugging printouts:
1377          */
1378         if (verbose(prev->class) || verbose(next->class)) {
1379                 graph_unlock();
1380                 printk("\n new dependency: ");
1381                 print_lock_name(prev->class);
1382                 printk(" => ");
1383                 print_lock_name(next->class);
1384                 printk("\n");
1385                 dump_stack();
1386                 return graph_lock();
1387         }
1388         return 1;
1389 }
1390
1391 /*
1392  * Add the dependency to all directly-previous locks that are 'relevant'.
1393  * The ones that are relevant are (in increasing distance from curr):
1394  * all consecutive trylock entries and the final non-trylock entry - or
1395  * the end of this context's lock-chain - whichever comes first.
1396  */
1397 static int
1398 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1399 {
1400         int depth = curr->lockdep_depth;
1401         struct held_lock *hlock;
1402
1403         /*
1404          * Debugging checks.
1405          *
1406          * Depth must not be zero for a non-head lock:
1407          */
1408         if (!depth)
1409                 goto out_bug;
1410         /*
1411          * At least two relevant locks must exist for this
1412          * to be a head:
1413          */
1414         if (curr->held_locks[depth].irq_context !=
1415                         curr->held_locks[depth-1].irq_context)
1416                 goto out_bug;
1417
1418         for (;;) {
1419                 int distance = curr->lockdep_depth - depth + 1;
1420                 hlock = curr->held_locks + depth-1;
1421                 /*
1422                  * Only non-recursive-read entries get new dependencies
1423                  * added:
1424                  */
1425                 if (hlock->read != 2) {
1426                         if (!check_prev_add(curr, hlock, next, distance))
1427                                 return 0;
1428                         /*
1429                          * Stop after the first non-trylock entry,
1430                          * as non-trylock entries have added their
1431                          * own direct dependencies already, so this
1432                          * lock is connected to them indirectly:
1433                          */
1434                         if (!hlock->trylock)
1435                                 break;
1436                 }
1437                 depth--;
1438                 /*
1439                  * End of lock-stack?
1440                  */
1441                 if (!depth)
1442                         break;
1443                 /*
1444                  * Stop the search if we cross into another context:
1445                  */
1446                 if (curr->held_locks[depth].irq_context !=
1447                                 curr->held_locks[depth-1].irq_context)
1448                         break;
1449         }
1450         return 1;
1451 out_bug:
1452         if (!debug_locks_off_graph_unlock())
1453                 return 0;
1454
1455         WARN_ON(1);
1456
1457         return 0;
1458 }
1459
1460 unsigned long nr_lock_chains;
1461 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1462 int nr_chain_hlocks;
1463 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1464
1465 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1466 {
1467         return lock_classes + chain_hlocks[chain->base + i];
1468 }
1469
1470 /*
1471  * Look up a dependency chain. If the key is not present yet then
1472  * add it and return 1 - in this case the new dependency chain is
1473  * validated. If the key is already hashed, return 0.
1474  * (On return with 1 graph_lock is held.)
1475  */
1476 static inline int lookup_chain_cache(struct task_struct *curr,
1477                                      struct held_lock *hlock,
1478                                      u64 chain_key)
1479 {
1480         struct lock_class *class = hlock->class;
1481         struct list_head *hash_head = chainhashentry(chain_key);
1482         struct lock_chain *chain;
1483         struct held_lock *hlock_curr, *hlock_next;
1484         int i, j, n, cn;
1485
1486         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1487                 return 0;
1488         /*
1489          * We can walk it lock-free, because entries only get added
1490          * to the hash:
1491          */
1492         list_for_each_entry(chain, hash_head, entry) {
1493                 if (chain->chain_key == chain_key) {
1494 cache_hit:
1495                         debug_atomic_inc(&chain_lookup_hits);
1496                         if (very_verbose(class))
1497                                 printk("\nhash chain already cached, key: "
1498                                         "%016Lx tail class: [%p] %s\n",
1499                                         (unsigned long long)chain_key,
1500                                         class->key, class->name);
1501                         return 0;
1502                 }
1503         }
1504         if (very_verbose(class))
1505                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1506                         (unsigned long long)chain_key, class->key, class->name);
1507         /*
1508          * Allocate a new chain entry from the static array, and add
1509          * it to the hash:
1510          */
1511         if (!graph_lock())
1512                 return 0;
1513         /*
1514          * We have to walk the chain again locked - to avoid duplicates:
1515          */
1516         list_for_each_entry(chain, hash_head, entry) {
1517                 if (chain->chain_key == chain_key) {
1518                         graph_unlock();
1519                         goto cache_hit;
1520                 }
1521         }
1522         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1523                 if (!debug_locks_off_graph_unlock())
1524                         return 0;
1525
1526                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1527                 printk("turning off the locking correctness validator.\n");
1528                 return 0;
1529         }
1530         chain = lock_chains + nr_lock_chains++;
1531         chain->chain_key = chain_key;
1532         chain->irq_context = hlock->irq_context;
1533         /* Find the first held_lock of current chain */
1534         hlock_next = hlock;
1535         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1536                 hlock_curr = curr->held_locks + i;
1537                 if (hlock_curr->irq_context != hlock_next->irq_context)
1538                         break;
1539                 hlock_next = hlock;
1540         }
1541         i++;
1542         chain->depth = curr->lockdep_depth + 1 - i;
1543         cn = nr_chain_hlocks;
1544         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1545                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1546                 if (n == cn)
1547                         break;
1548                 cn = n;
1549         }
1550         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1551                 chain->base = cn;
1552                 for (j = 0; j < chain->depth - 1; j++, i++) {
1553                         int lock_id = curr->held_locks[i].class - lock_classes;
1554                         chain_hlocks[chain->base + j] = lock_id;
1555                 }
1556                 chain_hlocks[chain->base + j] = class - lock_classes;
1557         }
1558         list_add_tail_rcu(&chain->entry, hash_head);
1559         debug_atomic_inc(&chain_lookup_misses);
1560         inc_chains();
1561
1562         return 1;
1563 }
1564
1565 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1566                 struct held_lock *hlock, int chain_head, u64 chain_key)
1567 {
1568         /*
1569          * Trylock needs to maintain the stack of held locks, but it
1570          * does not add new dependencies, because trylock can be done
1571          * in any order.
1572          *
1573          * We look up the chain_key and do the O(N^2) check and update of
1574          * the dependencies only if this is a new dependency chain.
1575          * (If lookup_chain_cache() returns with 1 it acquires
1576          * graph_lock for us)
1577          */
1578         if (!hlock->trylock && (hlock->check == 2) &&
1579             lookup_chain_cache(curr, hlock, chain_key)) {
1580                 /*
1581                  * Check whether last held lock:
1582                  *
1583                  * - is irq-safe, if this lock is irq-unsafe
1584                  * - is softirq-safe, if this lock is hardirq-unsafe
1585                  *
1586                  * And check whether the new lock's dependency graph
1587                  * could lead back to the previous lock.
1588                  *
1589                  * any of these scenarios could lead to a deadlock. If
1590                  * All validations
1591                  */
1592                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1593
1594                 if (!ret)
1595                         return 0;
1596                 /*
1597                  * Mark recursive read, as we jump over it when
1598                  * building dependencies (just like we jump over
1599                  * trylock entries):
1600                  */
1601                 if (ret == 2)
1602                         hlock->read = 2;
1603                 /*
1604                  * Add dependency only if this lock is not the head
1605                  * of the chain, and if it's not a secondary read-lock:
1606                  */
1607                 if (!chain_head && ret != 2)
1608                         if (!check_prevs_add(curr, hlock))
1609                                 return 0;
1610                 graph_unlock();
1611         } else
1612                 /* after lookup_chain_cache(): */
1613                 if (unlikely(!debug_locks))
1614                         return 0;
1615
1616         return 1;
1617 }
1618 #else
1619 static inline int validate_chain(struct task_struct *curr,
1620                 struct lockdep_map *lock, struct held_lock *hlock,
1621                 int chain_head, u64 chain_key)
1622 {
1623         return 1;
1624 }
1625 #endif
1626
1627 /*
1628  * We are building curr_chain_key incrementally, so double-check
1629  * it from scratch, to make sure that it's done correctly:
1630  */
1631 static void check_chain_key(struct task_struct *curr)
1632 {
1633 #ifdef CONFIG_DEBUG_LOCKDEP
1634         struct held_lock *hlock, *prev_hlock = NULL;
1635         unsigned int i, id;
1636         u64 chain_key = 0;
1637
1638         for (i = 0; i < curr->lockdep_depth; i++) {
1639                 hlock = curr->held_locks + i;
1640                 if (chain_key != hlock->prev_chain_key) {
1641                         debug_locks_off();
1642                         printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1643                                 curr->lockdep_depth, i,
1644                                 (unsigned long long)chain_key,
1645                                 (unsigned long long)hlock->prev_chain_key);
1646                         WARN_ON(1);
1647                         return;
1648                 }
1649                 id = hlock->class - lock_classes;
1650                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1651                         return;
1652
1653                 if (prev_hlock && (prev_hlock->irq_context !=
1654                                                         hlock->irq_context))
1655                         chain_key = 0;
1656                 chain_key = iterate_chain_key(chain_key, id);
1657                 prev_hlock = hlock;
1658         }
1659         if (chain_key != curr->curr_chain_key) {
1660                 debug_locks_off();
1661                 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1662                         curr->lockdep_depth, i,
1663                         (unsigned long long)chain_key,
1664                         (unsigned long long)curr->curr_chain_key);
1665                 WARN_ON(1);
1666         }
1667 #endif
1668 }
1669
1670 static int
1671 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1672                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1673 {
1674         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1675                 return 0;
1676
1677         printk("\n=================================\n");
1678         printk(  "[ INFO: inconsistent lock state ]\n");
1679         print_kernel_version();
1680         printk(  "---------------------------------\n");
1681
1682         printk("inconsistent {%s} -> {%s} usage.\n",
1683                 usage_str[prev_bit], usage_str[new_bit]);
1684
1685         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1686                 curr->comm, task_pid_nr(curr),
1687                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1688                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1689                 trace_hardirqs_enabled(curr),
1690                 trace_softirqs_enabled(curr));
1691         print_lock(this);
1692
1693         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1694         print_stack_trace(this->class->usage_traces + prev_bit, 1);
1695
1696         print_irqtrace_events(curr);
1697         printk("\nother info that might help us debug this:\n");
1698         lockdep_print_held_locks(curr);
1699
1700         printk("\nstack backtrace:\n");
1701         dump_stack();
1702
1703         return 0;
1704 }
1705
1706 /*
1707  * Print out an error if an invalid bit is set:
1708  */
1709 static inline int
1710 valid_state(struct task_struct *curr, struct held_lock *this,
1711             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1712 {
1713         if (unlikely(this->class->usage_mask & (1 << bad_bit)))
1714                 return print_usage_bug(curr, this, bad_bit, new_bit);
1715         return 1;
1716 }
1717
1718 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1719                      enum lock_usage_bit new_bit);
1720
1721 #ifdef CONFIG_TRACE_IRQFLAGS
1722
1723 /*
1724  * print irq inversion bug:
1725  */
1726 static int
1727 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1728                         struct held_lock *this, int forwards,
1729                         const char *irqclass)
1730 {
1731         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1732                 return 0;
1733
1734         printk("\n=========================================================\n");
1735         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
1736         print_kernel_version();
1737         printk(  "---------------------------------------------------------\n");
1738         printk("%s/%d just changed the state of lock:\n",
1739                 curr->comm, task_pid_nr(curr));
1740         print_lock(this);
1741         if (forwards)
1742                 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1743         else
1744                 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1745         print_lock_name(other);
1746         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1747
1748         printk("\nother info that might help us debug this:\n");
1749         lockdep_print_held_locks(curr);
1750
1751         printk("\nthe first lock's dependencies:\n");
1752         print_lock_dependencies(this->class, 0);
1753
1754         printk("\nthe second lock's dependencies:\n");
1755         print_lock_dependencies(other, 0);
1756
1757         printk("\nstack backtrace:\n");
1758         dump_stack();
1759
1760         return 0;
1761 }
1762
1763 /*
1764  * Prove that in the forwards-direction subgraph starting at <this>
1765  * there is no lock matching <mask>:
1766  */
1767 static int
1768 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1769                      enum lock_usage_bit bit, const char *irqclass)
1770 {
1771         int ret;
1772
1773         find_usage_bit = bit;
1774         /* fills in <forwards_match> */
1775         ret = find_usage_forwards(this->class, 0);
1776         if (!ret || ret == 1)
1777                 return ret;
1778
1779         return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1780 }
1781
1782 /*
1783  * Prove that in the backwards-direction subgraph starting at <this>
1784  * there is no lock matching <mask>:
1785  */
1786 static int
1787 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1788                       enum lock_usage_bit bit, const char *irqclass)
1789 {
1790         int ret;
1791
1792         find_usage_bit = bit;
1793         /* fills in <backwards_match> */
1794         ret = find_usage_backwards(this->class, 0);
1795         if (!ret || ret == 1)
1796                 return ret;
1797
1798         return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1799 }
1800
1801 void print_irqtrace_events(struct task_struct *curr)
1802 {
1803         printk("irq event stamp: %u\n", curr->irq_events);
1804         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
1805         print_ip_sym(curr->hardirq_enable_ip);
1806         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1807         print_ip_sym(curr->hardirq_disable_ip);
1808         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
1809         print_ip_sym(curr->softirq_enable_ip);
1810         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1811         print_ip_sym(curr->softirq_disable_ip);
1812 }
1813
1814 static int hardirq_verbose(struct lock_class *class)
1815 {
1816 #if HARDIRQ_VERBOSE
1817         return class_filter(class);
1818 #endif
1819         return 0;
1820 }
1821
1822 static int softirq_verbose(struct lock_class *class)
1823 {
1824 #if SOFTIRQ_VERBOSE
1825         return class_filter(class);
1826 #endif
1827         return 0;
1828 }
1829
1830 #define STRICT_READ_CHECKS      1
1831
1832 static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
1833                 enum lock_usage_bit new_bit)
1834 {
1835         int ret = 1;
1836
1837         switch(new_bit) {
1838         case LOCK_USED_IN_HARDIRQ:
1839                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1840                         return 0;
1841                 if (!valid_state(curr, this, new_bit,
1842                                  LOCK_ENABLED_HARDIRQS_READ))
1843                         return 0;
1844                 /*
1845                  * just marked it hardirq-safe, check that this lock
1846                  * took no hardirq-unsafe lock in the past:
1847                  */
1848                 if (!check_usage_forwards(curr, this,
1849                                           LOCK_ENABLED_HARDIRQS, "hard"))
1850                         return 0;
1851 #if STRICT_READ_CHECKS
1852                 /*
1853                  * just marked it hardirq-safe, check that this lock
1854                  * took no hardirq-unsafe-read lock in the past:
1855                  */
1856                 if (!check_usage_forwards(curr, this,
1857                                 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1858                         return 0;
1859 #endif
1860                 if (hardirq_verbose(this->class))
1861                         ret = 2;
1862                 break;
1863         case LOCK_USED_IN_SOFTIRQ:
1864                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1865                         return 0;
1866                 if (!valid_state(curr, this, new_bit,
1867                                  LOCK_ENABLED_SOFTIRQS_READ))
1868                         return 0;
1869                 /*
1870                  * just marked it softirq-safe, check that this lock
1871                  * took no softirq-unsafe lock in the past:
1872                  */
1873                 if (!check_usage_forwards(curr, this,
1874                                           LOCK_ENABLED_SOFTIRQS, "soft"))
1875                         return 0;
1876 #if STRICT_READ_CHECKS
1877                 /*
1878                  * just marked it softirq-safe, check that this lock
1879                  * took no softirq-unsafe-read lock in the past:
1880                  */
1881                 if (!check_usage_forwards(curr, this,
1882                                 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
1883                         return 0;
1884 #endif
1885                 if (softirq_verbose(this->class))
1886                         ret = 2;
1887                 break;
1888         case LOCK_USED_IN_HARDIRQ_READ:
1889                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1890                         return 0;
1891                 /*
1892                  * just marked it hardirq-read-safe, check that this lock
1893                  * took no hardirq-unsafe lock in the past:
1894                  */
1895                 if (!check_usage_forwards(curr, this,
1896                                           LOCK_ENABLED_HARDIRQS, "hard"))
1897                         return 0;
1898                 if (hardirq_verbose(this->class))
1899                         ret = 2;
1900                 break;
1901         case LOCK_USED_IN_SOFTIRQ_READ:
1902                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1903                         return 0;
1904                 /*
1905                  * just marked it softirq-read-safe, check that this lock
1906                  * took no softirq-unsafe lock in the past:
1907                  */
1908                 if (!check_usage_forwards(curr, this,
1909                                           LOCK_ENABLED_SOFTIRQS, "soft"))
1910                         return 0;
1911                 if (softirq_verbose(this->class))
1912                         ret = 2;
1913                 break;
1914         case LOCK_ENABLED_HARDIRQS:
1915                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1916                         return 0;
1917                 if (!valid_state(curr, this, new_bit,
1918                                  LOCK_USED_IN_HARDIRQ_READ))
1919                         return 0;
1920                 /*
1921                  * just marked it hardirq-unsafe, check that no hardirq-safe
1922                  * lock in the system ever took it in the past:
1923                  */
1924                 if (!check_usage_backwards(curr, this,
1925                                            LOCK_USED_IN_HARDIRQ, "hard"))
1926                         return 0;
1927 #if STRICT_READ_CHECKS
1928                 /*
1929                  * just marked it hardirq-unsafe, check that no
1930                  * hardirq-safe-read lock in the system ever took
1931                  * it in the past:
1932                  */
1933                 if (!check_usage_backwards(curr, this,
1934                                    LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
1935                         return 0;
1936 #endif
1937                 if (hardirq_verbose(this->class))
1938                         ret = 2;
1939                 break;
1940         case LOCK_ENABLED_SOFTIRQS:
1941                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1942                         return 0;
1943                 if (!valid_state(curr, this, new_bit,
1944                                  LOCK_USED_IN_SOFTIRQ_READ))
1945                         return 0;
1946                 /*
1947                  * just marked it softirq-unsafe, check that no softirq-safe
1948                  * lock in the system ever took it in the past:
1949                  */
1950                 if (!check_usage_backwards(curr, this,
1951                                            LOCK_USED_IN_SOFTIRQ, "soft"))
1952                         return 0;
1953 #if STRICT_READ_CHECKS
1954                 /*
1955                  * just marked it softirq-unsafe, check that no
1956                  * softirq-safe-read lock in the system ever took
1957                  * it in the past:
1958                  */
1959                 if (!check_usage_backwards(curr, this,
1960                                    LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
1961                         return 0;
1962 #endif
1963                 if (softirq_verbose(this->class))
1964                         ret = 2;
1965                 break;
1966         case LOCK_ENABLED_HARDIRQS_READ:
1967                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1968                         return 0;
1969 #if STRICT_READ_CHECKS
1970                 /*
1971                  * just marked it hardirq-read-unsafe, check that no
1972                  * hardirq-safe lock in the system ever took it in the past:
1973                  */
1974                 if (!check_usage_backwards(curr, this,
1975                                            LOCK_USED_IN_HARDIRQ, "hard"))
1976                         return 0;
1977 #endif
1978                 if (hardirq_verbose(this->class))
1979                         ret = 2;
1980                 break;
1981         case LOCK_ENABLED_SOFTIRQS_READ:
1982                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1983                         return 0;
1984 #if STRICT_READ_CHECKS
1985                 /*
1986                  * just marked it softirq-read-unsafe, check that no
1987                  * softirq-safe lock in the system ever took it in the past:
1988                  */
1989                 if (!check_usage_backwards(curr, this,
1990                                            LOCK_USED_IN_SOFTIRQ, "soft"))
1991                         return 0;
1992 #endif
1993                 if (softirq_verbose(this->class))
1994                         ret = 2;
1995                 break;
1996         default:
1997                 WARN_ON(1);
1998                 break;
1999         }
2000
2001         return ret;
2002 }
2003
2004 /*
2005  * Mark all held locks with a usage bit:
2006  */
2007 static int
2008 mark_held_locks(struct task_struct *curr, int hardirq)
2009 {
2010         enum lock_usage_bit usage_bit;
2011         struct held_lock *hlock;
2012         int i;
2013
2014         for (i = 0; i < curr->lockdep_depth; i++) {
2015                 hlock = curr->held_locks + i;
2016
2017                 if (hardirq) {
2018                         if (hlock->read)
2019                                 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
2020                         else
2021                                 usage_bit = LOCK_ENABLED_HARDIRQS;
2022                 } else {
2023                         if (hlock->read)
2024                                 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
2025                         else
2026                                 usage_bit = LOCK_ENABLED_SOFTIRQS;
2027                 }
2028                 if (!mark_lock(curr, hlock, usage_bit))
2029                         return 0;
2030         }
2031
2032         return 1;
2033 }
2034
2035 /*
2036  * Debugging helper: via this flag we know that we are in
2037  * 'early bootup code', and will warn about any invalid irqs-on event:
2038  */
2039 static int early_boot_irqs_enabled;
2040
2041 void early_boot_irqs_off(void)
2042 {
2043         early_boot_irqs_enabled = 0;
2044 }
2045
2046 void early_boot_irqs_on(void)
2047 {
2048         early_boot_irqs_enabled = 1;
2049 }
2050
2051 /*
2052  * Hardirqs will be enabled:
2053  */
2054 void trace_hardirqs_on(void)
2055 {
2056         struct task_struct *curr = current;
2057         unsigned long ip;
2058
2059         if (unlikely(!debug_locks || current->lockdep_recursion))
2060                 return;
2061
2062         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2063                 return;
2064
2065         if (unlikely(curr->hardirqs_enabled)) {
2066                 debug_atomic_inc(&redundant_hardirqs_on);
2067                 return;
2068         }
2069         /* we'll do an OFF -> ON transition: */
2070         curr->hardirqs_enabled = 1;
2071         ip = (unsigned long) __builtin_return_address(0);
2072
2073         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2074                 return;
2075         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2076                 return;
2077         /*
2078          * We are going to turn hardirqs on, so set the
2079          * usage bit for all held locks:
2080          */
2081         if (!mark_held_locks(curr, 1))
2082                 return;
2083         /*
2084          * If we have softirqs enabled, then set the usage
2085          * bit for all held locks. (disabled hardirqs prevented
2086          * this bit from being set before)
2087          */
2088         if (curr->softirqs_enabled)
2089                 if (!mark_held_locks(curr, 0))
2090                         return;
2091
2092         curr->hardirq_enable_ip = ip;
2093         curr->hardirq_enable_event = ++curr->irq_events;
2094         debug_atomic_inc(&hardirqs_on_events);
2095 }
2096
2097 EXPORT_SYMBOL(trace_hardirqs_on);
2098
2099 /*
2100  * Hardirqs were disabled:
2101  */
2102 void trace_hardirqs_off(void)
2103 {
2104         struct task_struct *curr = current;
2105
2106         if (unlikely(!debug_locks || current->lockdep_recursion))
2107                 return;
2108
2109         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2110                 return;
2111
2112         if (curr->hardirqs_enabled) {
2113                 /*
2114                  * We have done an ON -> OFF transition:
2115                  */
2116                 curr->hardirqs_enabled = 0;
2117                 curr->hardirq_disable_ip = _RET_IP_;
2118                 curr->hardirq_disable_event = ++curr->irq_events;
2119                 debug_atomic_inc(&hardirqs_off_events);
2120         } else
2121                 debug_atomic_inc(&redundant_hardirqs_off);
2122 }
2123
2124 EXPORT_SYMBOL(trace_hardirqs_off);
2125
2126 /*
2127  * Softirqs will be enabled:
2128  */
2129 void trace_softirqs_on(unsigned long ip)
2130 {
2131         struct task_struct *curr = current;
2132
2133         if (unlikely(!debug_locks))
2134                 return;
2135
2136         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2137                 return;
2138
2139         if (curr->softirqs_enabled) {
2140                 debug_atomic_inc(&redundant_softirqs_on);
2141                 return;
2142         }
2143
2144         /*
2145          * We'll do an OFF -> ON transition:
2146          */
2147         curr->softirqs_enabled = 1;
2148         curr->softirq_enable_ip = ip;
2149         curr->softirq_enable_event = ++curr->irq_events;
2150         debug_atomic_inc(&softirqs_on_events);
2151         /*
2152          * We are going to turn softirqs on, so set the
2153          * usage bit for all held locks, if hardirqs are
2154          * enabled too:
2155          */
2156         if (curr->hardirqs_enabled)
2157                 mark_held_locks(curr, 0);
2158 }
2159
2160 /*
2161  * Softirqs were disabled:
2162  */
2163 void trace_softirqs_off(unsigned long ip)
2164 {
2165         struct task_struct *curr = current;
2166
2167         if (unlikely(!debug_locks))
2168                 return;
2169
2170         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2171                 return;
2172
2173         if (curr->softirqs_enabled) {
2174                 /*
2175                  * We have done an ON -> OFF transition:
2176                  */
2177                 curr->softirqs_enabled = 0;
2178                 curr->softirq_disable_ip = ip;
2179                 curr->softirq_disable_event = ++curr->irq_events;
2180                 debug_atomic_inc(&softirqs_off_events);
2181                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2182         } else
2183                 debug_atomic_inc(&redundant_softirqs_off);
2184 }
2185
2186 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2187 {
2188         /*
2189          * If non-trylock use in a hardirq or softirq context, then
2190          * mark the lock as used in these contexts:
2191          */
2192         if (!hlock->trylock) {
2193                 if (hlock->read) {
2194                         if (curr->hardirq_context)
2195                                 if (!mark_lock(curr, hlock,
2196                                                 LOCK_USED_IN_HARDIRQ_READ))
2197                                         return 0;
2198                         if (curr->softirq_context)
2199                                 if (!mark_lock(curr, hlock,
2200                                                 LOCK_USED_IN_SOFTIRQ_READ))
2201                                         return 0;
2202                 } else {
2203                         if (curr->hardirq_context)
2204                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2205                                         return 0;
2206                         if (curr->softirq_context)
2207                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2208                                         return 0;
2209                 }
2210         }
2211         if (!hlock->hardirqs_off) {
2212                 if (hlock->read) {
2213                         if (!mark_lock(curr, hlock,
2214                                         LOCK_ENABLED_HARDIRQS_READ))
2215                                 return 0;
2216                         if (curr->softirqs_enabled)
2217                                 if (!mark_lock(curr, hlock,
2218                                                 LOCK_ENABLED_SOFTIRQS_READ))
2219                                         return 0;
2220                 } else {
2221                         if (!mark_lock(curr, hlock,
2222                                         LOCK_ENABLED_HARDIRQS))
2223                                 return 0;
2224                         if (curr->softirqs_enabled)
2225                                 if (!mark_lock(curr, hlock,
2226                                                 LOCK_ENABLED_SOFTIRQS))
2227                                         return 0;
2228                 }
2229         }
2230
2231         return 1;
2232 }
2233
2234 static int separate_irq_context(struct task_struct *curr,
2235                 struct held_lock *hlock)
2236 {
2237         unsigned int depth = curr->lockdep_depth;
2238
2239         /*
2240          * Keep track of points where we cross into an interrupt context:
2241          */
2242         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2243                                 curr->softirq_context;
2244         if (depth) {
2245                 struct held_lock *prev_hlock;
2246
2247                 prev_hlock = curr->held_locks + depth-1;
2248                 /*
2249                  * If we cross into another context, reset the
2250                  * hash key (this also prevents the checking and the
2251                  * adding of the dependency to 'prev'):
2252                  */
2253                 if (prev_hlock->irq_context != hlock->irq_context)
2254                         return 1;
2255         }
2256         return 0;
2257 }
2258
2259 #else
2260
2261 static inline
2262 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2263                 enum lock_usage_bit new_bit)
2264 {
2265         WARN_ON(1);
2266         return 1;
2267 }
2268
2269 static inline int mark_irqflags(struct task_struct *curr,
2270                 struct held_lock *hlock)
2271 {
2272         return 1;
2273 }
2274
2275 static inline int separate_irq_context(struct task_struct *curr,
2276                 struct held_lock *hlock)
2277 {
2278         return 0;
2279 }
2280
2281 #endif
2282
2283 /*
2284  * Mark a lock with a usage bit, and validate the state transition:
2285  */
2286 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2287                      enum lock_usage_bit new_bit)
2288 {
2289         unsigned int new_mask = 1 << new_bit, ret = 1;
2290
2291         /*
2292          * If already set then do not dirty the cacheline,
2293          * nor do any checks:
2294          */
2295         if (likely(this->class->usage_mask & new_mask))
2296                 return 1;
2297
2298         if (!graph_lock())
2299                 return 0;
2300         /*
2301          * Make sure we didnt race:
2302          */
2303         if (unlikely(this->class->usage_mask & new_mask)) {
2304                 graph_unlock();
2305                 return 1;
2306         }
2307
2308         this->class->usage_mask |= new_mask;
2309
2310         if (!save_trace(this->class->usage_traces + new_bit))
2311                 return 0;
2312
2313         switch (new_bit) {
2314         case LOCK_USED_IN_HARDIRQ:
2315         case LOCK_USED_IN_SOFTIRQ:
2316         case LOCK_USED_IN_HARDIRQ_READ:
2317         case LOCK_USED_IN_SOFTIRQ_READ:
2318         case LOCK_ENABLED_HARDIRQS:
2319         case LOCK_ENABLED_SOFTIRQS:
2320         case LOCK_ENABLED_HARDIRQS_READ:
2321         case LOCK_ENABLED_SOFTIRQS_READ:
2322                 ret = mark_lock_irq(curr, this, new_bit);
2323                 if (!ret)
2324                         return 0;
2325                 break;
2326         case LOCK_USED:
2327                 debug_atomic_dec(&nr_unused_locks);
2328                 break;
2329         default:
2330                 if (!debug_locks_off_graph_unlock())
2331                         return 0;
2332                 WARN_ON(1);
2333                 return 0;
2334         }
2335
2336         graph_unlock();
2337
2338         /*
2339          * We must printk outside of the graph_lock:
2340          */
2341         if (ret == 2) {
2342                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2343                 print_lock(this);
2344                 print_irqtrace_events(curr);
2345                 dump_stack();
2346         }
2347
2348         return ret;
2349 }
2350
2351 /*
2352  * Initialize a lock instance's lock-class mapping info:
2353  */
2354 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2355                       struct lock_class_key *key, int subclass)
2356 {
2357         if (unlikely(!debug_locks))
2358                 return;
2359
2360         if (DEBUG_LOCKS_WARN_ON(!key))
2361                 return;
2362         if (DEBUG_LOCKS_WARN_ON(!name))
2363                 return;
2364         /*
2365          * Sanity check, the lock-class key must be persistent:
2366          */
2367         if (!static_obj(key)) {
2368                 printk("BUG: key %p not in .data!\n", key);
2369                 DEBUG_LOCKS_WARN_ON(1);
2370                 return;
2371         }
2372         lock->name = name;
2373         lock->key = key;
2374         lock->class_cache = NULL;
2375 #ifdef CONFIG_LOCK_STAT
2376         lock->cpu = raw_smp_processor_id();
2377 #endif
2378         if (subclass)
2379                 register_lock_class(lock, subclass, 1);
2380 }
2381
2382 EXPORT_SYMBOL_GPL(lockdep_init_map);
2383
2384 /*
2385  * This gets called for every mutex_lock*()/spin_lock*() operation.
2386  * We maintain the dependency maps and validate the locking attempt:
2387  */
2388 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2389                           int trylock, int read, int check, int hardirqs_off,
2390                           unsigned long ip)
2391 {
2392         struct task_struct *curr = current;
2393         struct lock_class *class = NULL;
2394         struct held_lock *hlock;
2395         unsigned int depth, id;
2396         int chain_head = 0;
2397         u64 chain_key;
2398
2399         if (!prove_locking)
2400                 check = 1;
2401
2402         if (unlikely(!debug_locks))
2403                 return 0;
2404
2405         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2406                 return 0;
2407
2408         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2409                 debug_locks_off();
2410                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2411                 printk("turning off the locking correctness validator.\n");
2412                 return 0;
2413         }
2414
2415         if (!subclass)
2416                 class = lock->class_cache;
2417         /*
2418          * Not cached yet or subclass?
2419          */
2420         if (unlikely(!class)) {
2421                 class = register_lock_class(lock, subclass, 0);
2422                 if (!class)
2423                         return 0;
2424         }
2425         debug_atomic_inc((atomic_t *)&class->ops);
2426         if (very_verbose(class)) {
2427                 printk("\nacquire class [%p] %s", class->key, class->name);
2428                 if (class->name_version > 1)
2429                         printk("#%d", class->name_version);
2430                 printk("\n");
2431                 dump_stack();
2432         }
2433
2434         /*
2435          * Add the lock to the list of currently held locks.
2436          * (we dont increase the depth just yet, up until the
2437          * dependency checks are done)
2438          */
2439         depth = curr->lockdep_depth;
2440         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2441                 return 0;
2442
2443         hlock = curr->held_locks + depth;
2444
2445         hlock->class = class;
2446         hlock->acquire_ip = ip;
2447         hlock->instance = lock;
2448         hlock->trylock = trylock;
2449         hlock->read = read;
2450         hlock->check = check;
2451         hlock->hardirqs_off = hardirqs_off;
2452 #ifdef CONFIG_LOCK_STAT
2453         hlock->waittime_stamp = 0;
2454         hlock->holdtime_stamp = sched_clock();
2455 #endif
2456
2457         if (check == 2 && !mark_irqflags(curr, hlock))
2458                 return 0;
2459
2460         /* mark it as used: */
2461         if (!mark_lock(curr, hlock, LOCK_USED))
2462                 return 0;
2463
2464         /*
2465          * Calculate the chain hash: it's the combined hash of all the
2466          * lock keys along the dependency chain. We save the hash value
2467          * at every step so that we can get the current hash easily
2468          * after unlock. The chain hash is then used to cache dependency
2469          * results.
2470          *
2471          * The 'key ID' is what is the most compact key value to drive
2472          * the hash, not class->key.
2473          */
2474         id = class - lock_classes;
2475         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2476                 return 0;
2477
2478         chain_key = curr->curr_chain_key;
2479         if (!depth) {
2480                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2481                         return 0;
2482                 chain_head = 1;
2483         }
2484
2485         hlock->prev_chain_key = chain_key;
2486         if (separate_irq_context(curr, hlock)) {
2487                 chain_key = 0;
2488                 chain_head = 1;
2489         }
2490         chain_key = iterate_chain_key(chain_key, id);
2491
2492         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2493                 return 0;
2494
2495         curr->curr_chain_key = chain_key;
2496         curr->lockdep_depth++;
2497         check_chain_key(curr);
2498 #ifdef CONFIG_DEBUG_LOCKDEP
2499         if (unlikely(!debug_locks))
2500                 return 0;
2501 #endif
2502         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2503                 debug_locks_off();
2504                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2505                 printk("turning off the locking correctness validator.\n");
2506                 return 0;
2507         }
2508
2509         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2510                 max_lockdep_depth = curr->lockdep_depth;
2511
2512         return 1;
2513 }
2514
2515 static int
2516 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2517                            unsigned long ip)
2518 {
2519         if (!debug_locks_off())
2520                 return 0;
2521         if (debug_locks_silent)
2522                 return 0;
2523
2524         printk("\n=====================================\n");
2525         printk(  "[ BUG: bad unlock balance detected! ]\n");
2526         printk(  "-------------------------------------\n");
2527         printk("%s/%d is trying to release lock (",
2528                 curr->comm, task_pid_nr(curr));
2529         print_lockdep_cache(lock);
2530         printk(") at:\n");
2531         print_ip_sym(ip);
2532         printk("but there are no more locks to release!\n");
2533         printk("\nother info that might help us debug this:\n");
2534         lockdep_print_held_locks(curr);
2535
2536         printk("\nstack backtrace:\n");
2537         dump_stack();
2538
2539         return 0;
2540 }
2541
2542 /*
2543  * Common debugging checks for both nested and non-nested unlock:
2544  */
2545 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2546                         unsigned long ip)
2547 {
2548         if (unlikely(!debug_locks))
2549                 return 0;
2550         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2551                 return 0;
2552
2553         if (curr->lockdep_depth <= 0)
2554                 return print_unlock_inbalance_bug(curr, lock, ip);
2555
2556         return 1;
2557 }
2558
2559 /*
2560  * Remove the lock to the list of currently held locks in a
2561  * potentially non-nested (out of order) manner. This is a
2562  * relatively rare operation, as all the unlock APIs default
2563  * to nested mode (which uses lock_release()):
2564  */
2565 static int
2566 lock_release_non_nested(struct task_struct *curr,
2567                         struct lockdep_map *lock, unsigned long ip)
2568 {
2569         struct held_lock *hlock, *prev_hlock;
2570         unsigned int depth;
2571         int i;
2572
2573         /*
2574          * Check whether the lock exists in the current stack
2575          * of held locks:
2576          */
2577         depth = curr->lockdep_depth;
2578         if (DEBUG_LOCKS_WARN_ON(!depth))
2579                 return 0;
2580
2581         prev_hlock = NULL;
2582         for (i = depth-1; i >= 0; i--) {
2583                 hlock = curr->held_locks + i;
2584                 /*
2585                  * We must not cross into another context:
2586                  */
2587                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2588                         break;
2589                 if (hlock->instance == lock)
2590                         goto found_it;
2591                 prev_hlock = hlock;
2592         }
2593         return print_unlock_inbalance_bug(curr, lock, ip);
2594
2595 found_it:
2596         lock_release_holdtime(hlock);
2597
2598         /*
2599          * We have the right lock to unlock, 'hlock' points to it.
2600          * Now we remove it from the stack, and add back the other
2601          * entries (if any), recalculating the hash along the way:
2602          */
2603         curr->lockdep_depth = i;
2604         curr->curr_chain_key = hlock->prev_chain_key;
2605
2606         for (i++; i < depth; i++) {
2607                 hlock = curr->held_locks + i;
2608                 if (!__lock_acquire(hlock->instance,
2609                         hlock->class->subclass, hlock->trylock,
2610                                 hlock->read, hlock->check, hlock->hardirqs_off,
2611                                 hlock->acquire_ip))
2612                         return 0;
2613         }
2614
2615         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2616                 return 0;
2617         return 1;
2618 }
2619
2620 /*
2621  * Remove the lock to the list of currently held locks - this gets
2622  * called on mutex_unlock()/spin_unlock*() (or on a failed
2623  * mutex_lock_interruptible()). This is done for unlocks that nest
2624  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2625  */
2626 static int lock_release_nested(struct task_struct *curr,
2627                                struct lockdep_map *lock, unsigned long ip)
2628 {
2629         struct held_lock *hlock;
2630         unsigned int depth;
2631
2632         /*
2633          * Pop off the top of the lock stack:
2634          */
2635         depth = curr->lockdep_depth - 1;
2636         hlock = curr->held_locks + depth;
2637
2638         /*
2639          * Is the unlock non-nested:
2640          */
2641         if (hlock->instance != lock)
2642                 return lock_release_non_nested(curr, lock, ip);
2643         curr->lockdep_depth--;
2644
2645         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2646                 return 0;
2647
2648         curr->curr_chain_key = hlock->prev_chain_key;
2649
2650         lock_release_holdtime(hlock);
2651
2652 #ifdef CONFIG_DEBUG_LOCKDEP
2653         hlock->prev_chain_key = 0;
2654         hlock->class = NULL;
2655         hlock->acquire_ip = 0;
2656         hlock->irq_context = 0;
2657 #endif
2658         return 1;
2659 }
2660
2661 /*
2662  * Remove the lock to the list of currently held locks - this gets
2663  * called on mutex_unlock()/spin_unlock*() (or on a failed
2664  * mutex_lock_interruptible()). This is done for unlocks that nest
2665  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2666  */
2667 static void
2668 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2669 {
2670         struct task_struct *curr = current;
2671
2672         if (!check_unlock(curr, lock, ip))
2673                 return;
2674
2675         if (nested) {
2676                 if (!lock_release_nested(curr, lock, ip))
2677                         return;
2678         } else {
2679                 if (!lock_release_non_nested(curr, lock, ip))
2680                         return;
2681         }
2682
2683         check_chain_key(curr);
2684 }
2685
2686 /*
2687  * Check whether we follow the irq-flags state precisely:
2688  */
2689 static void check_flags(unsigned long flags)
2690 {
2691 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2692         if (!debug_locks)
2693                 return;
2694
2695         if (irqs_disabled_flags(flags)) {
2696                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
2697                         printk("possible reason: unannotated irqs-off.\n");
2698                 }
2699         } else {
2700                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
2701                         printk("possible reason: unannotated irqs-on.\n");
2702                 }
2703         }
2704
2705         /*
2706          * We dont accurately track softirq state in e.g.
2707          * hardirq contexts (such as on 4KSTACKS), so only
2708          * check if not in hardirq contexts:
2709          */
2710         if (!hardirq_count()) {
2711                 if (softirq_count())
2712                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2713                 else
2714                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2715         }
2716
2717         if (!debug_locks)
2718                 print_irqtrace_events(current);
2719 #endif
2720 }
2721
2722 /*
2723  * We are not always called with irqs disabled - do that here,
2724  * and also avoid lockdep recursion:
2725  */
2726 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2727                   int trylock, int read, int check, unsigned long ip)
2728 {
2729         unsigned long flags;
2730
2731         if (unlikely(!lock_stat && !prove_locking))
2732                 return;
2733
2734         if (unlikely(current->lockdep_recursion))
2735                 return;
2736
2737         raw_local_irq_save(flags);
2738         check_flags(flags);
2739
2740         current->lockdep_recursion = 1;
2741         __lock_acquire(lock, subclass, trylock, read, check,
2742                        irqs_disabled_flags(flags), ip);
2743         current->lockdep_recursion = 0;
2744         raw_local_irq_restore(flags);
2745 }
2746
2747 EXPORT_SYMBOL_GPL(lock_acquire);
2748
2749 void lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2750 {
2751         unsigned long flags;
2752
2753         if (unlikely(!lock_stat && !prove_locking))
2754                 return;
2755
2756         if (unlikely(current->lockdep_recursion))
2757                 return;
2758
2759         raw_local_irq_save(flags);
2760         check_flags(flags);
2761         current->lockdep_recursion = 1;
2762         __lock_release(lock, nested, ip);
2763         current->lockdep_recursion = 0;
2764         raw_local_irq_restore(flags);
2765 }
2766
2767 EXPORT_SYMBOL_GPL(lock_release);
2768
2769 #ifdef CONFIG_LOCK_STAT
2770 static int
2771 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
2772                            unsigned long ip)
2773 {
2774         if (!debug_locks_off())
2775                 return 0;
2776         if (debug_locks_silent)
2777                 return 0;
2778
2779         printk("\n=================================\n");
2780         printk(  "[ BUG: bad contention detected! ]\n");
2781         printk(  "---------------------------------\n");
2782         printk("%s/%d is trying to contend lock (",
2783                 curr->comm, task_pid_nr(curr));
2784         print_lockdep_cache(lock);
2785         printk(") at:\n");
2786         print_ip_sym(ip);
2787         printk("but there are no locks held!\n");
2788         printk("\nother info that might help us debug this:\n");
2789         lockdep_print_held_locks(curr);
2790
2791         printk("\nstack backtrace:\n");
2792         dump_stack();
2793
2794         return 0;
2795 }
2796
2797 static void
2798 __lock_contended(struct lockdep_map *lock, unsigned long ip)
2799 {
2800         struct task_struct *curr = current;
2801         struct held_lock *hlock, *prev_hlock;
2802         struct lock_class_stats *stats;
2803         unsigned int depth;
2804         int i, point;
2805
2806         depth = curr->lockdep_depth;
2807         if (DEBUG_LOCKS_WARN_ON(!depth))
2808                 return;
2809
2810         prev_hlock = NULL;
2811         for (i = depth-1; i >= 0; i--) {
2812                 hlock = curr->held_locks + i;
2813                 /*
2814                  * We must not cross into another context:
2815                  */
2816                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2817                         break;
2818                 if (hlock->instance == lock)
2819                         goto found_it;
2820                 prev_hlock = hlock;
2821         }
2822         print_lock_contention_bug(curr, lock, ip);
2823         return;
2824
2825 found_it:
2826         hlock->waittime_stamp = sched_clock();
2827
2828         point = lock_contention_point(hlock->class, ip);
2829
2830         stats = get_lock_stats(hlock->class);
2831         if (point < ARRAY_SIZE(stats->contention_point))
2832                 stats->contention_point[i]++;
2833         if (lock->cpu != smp_processor_id())
2834                 stats->bounces[bounce_contended + !!hlock->read]++;
2835         put_lock_stats(stats);
2836 }
2837
2838 static void
2839 __lock_acquired(struct lockdep_map *lock)
2840 {
2841         struct task_struct *curr = current;
2842         struct held_lock *hlock, *prev_hlock;
2843         struct lock_class_stats *stats;
2844         unsigned int depth;
2845         u64 now;
2846         s64 waittime = 0;
2847         int i, cpu;
2848
2849         depth = curr->lockdep_depth;
2850         if (DEBUG_LOCKS_WARN_ON(!depth))
2851                 return;
2852
2853         prev_hlock = NULL;
2854         for (i = depth-1; i >= 0; i--) {
2855                 hlock = curr->held_locks + i;
2856                 /*
2857                  * We must not cross into another context:
2858                  */
2859                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2860                         break;
2861                 if (hlock->instance == lock)
2862                         goto found_it;
2863                 prev_hlock = hlock;
2864         }
2865         print_lock_contention_bug(curr, lock, _RET_IP_);
2866         return;
2867
2868 found_it:
2869         cpu = smp_processor_id();
2870         if (hlock->waittime_stamp) {
2871                 now = sched_clock();
2872                 waittime = now - hlock->waittime_stamp;
2873                 hlock->holdtime_stamp = now;
2874         }
2875
2876         stats = get_lock_stats(hlock->class);
2877         if (waittime) {
2878                 if (hlock->read)
2879                         lock_time_inc(&stats->read_waittime, waittime);
2880                 else
2881                         lock_time_inc(&stats->write_waittime, waittime);
2882         }
2883         if (lock->cpu != cpu)
2884                 stats->bounces[bounce_acquired + !!hlock->read]++;
2885         put_lock_stats(stats);
2886
2887         lock->cpu = cpu;
2888 }
2889
2890 void lock_contended(struct lockdep_map *lock, unsigned long ip)
2891 {
2892         unsigned long flags;
2893
2894         if (unlikely(!lock_stat))
2895                 return;
2896
2897         if (unlikely(current->lockdep_recursion))
2898                 return;
2899
2900         raw_local_irq_save(flags);
2901         check_flags(flags);
2902         current->lockdep_recursion = 1;
2903         __lock_contended(lock, ip);
2904         current->lockdep_recursion = 0;
2905         raw_local_irq_restore(flags);
2906 }
2907 EXPORT_SYMBOL_GPL(lock_contended);
2908
2909 void lock_acquired(struct lockdep_map *lock)
2910 {
2911         unsigned long flags;
2912
2913         if (unlikely(!lock_stat))
2914                 return;
2915
2916         if (unlikely(current->lockdep_recursion))
2917                 return;
2918
2919         raw_local_irq_save(flags);
2920         check_flags(flags);
2921         current->lockdep_recursion = 1;
2922         __lock_acquired(lock);
2923         current->lockdep_recursion = 0;
2924         raw_local_irq_restore(flags);
2925 }
2926 EXPORT_SYMBOL_GPL(lock_acquired);
2927 #endif
2928
2929 /*
2930  * Used by the testsuite, sanitize the validator state
2931  * after a simulated failure:
2932  */
2933
2934 void lockdep_reset(void)
2935 {
2936         unsigned long flags;
2937         int i;
2938
2939         raw_local_irq_save(flags);
2940         current->curr_chain_key = 0;
2941         current->lockdep_depth = 0;
2942         current->lockdep_recursion = 0;
2943         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
2944         nr_hardirq_chains = 0;
2945         nr_softirq_chains = 0;
2946         nr_process_chains = 0;
2947         debug_locks = 1;
2948         for (i = 0; i < CHAINHASH_SIZE; i++)
2949                 INIT_LIST_HEAD(chainhash_table + i);
2950         raw_local_irq_restore(flags);
2951 }
2952
2953 static void zap_class(struct lock_class *class)
2954 {
2955         int i;
2956
2957         /*
2958          * Remove all dependencies this lock is
2959          * involved in:
2960          */
2961         for (i = 0; i < nr_list_entries; i++) {
2962                 if (list_entries[i].class == class)
2963                         list_del_rcu(&list_entries[i].entry);
2964         }
2965         /*
2966          * Unhash the class and remove it from the all_lock_classes list:
2967          */
2968         list_del_rcu(&class->hash_entry);
2969         list_del_rcu(&class->lock_entry);
2970
2971 }
2972
2973 static inline int within(const void *addr, void *start, unsigned long size)
2974 {
2975         return addr >= start && addr < start + size;
2976 }
2977
2978 void lockdep_free_key_range(void *start, unsigned long size)
2979 {
2980         struct lock_class *class, *next;
2981         struct list_head *head;
2982         unsigned long flags;
2983         int i;
2984         int locked;
2985
2986         raw_local_irq_save(flags);
2987         locked = graph_lock();
2988
2989         /*
2990          * Unhash all classes that were created by this module:
2991          */
2992         for (i = 0; i < CLASSHASH_SIZE; i++) {
2993                 head = classhash_table + i;
2994                 if (list_empty(head))
2995                         continue;
2996                 list_for_each_entry_safe(class, next, head, hash_entry) {
2997                         if (within(class->key, start, size))
2998                                 zap_class(class);
2999                         else if (within(class->name, start, size))
3000                                 zap_class(class);
3001                 }
3002         }
3003
3004         if (locked)
3005                 graph_unlock();
3006         raw_local_irq_restore(flags);
3007 }
3008
3009 void lockdep_reset_lock(struct lockdep_map *lock)
3010 {
3011         struct lock_class *class, *next;
3012         struct list_head *head;
3013         unsigned long flags;
3014         int i, j;
3015         int locked;
3016
3017         raw_local_irq_save(flags);
3018
3019         /*
3020          * Remove all classes this lock might have:
3021          */
3022         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3023                 /*
3024                  * If the class exists we look it up and zap it:
3025                  */
3026                 class = look_up_lock_class(lock, j);
3027                 if (class)
3028                         zap_class(class);
3029         }
3030         /*
3031          * Debug check: in the end all mapped classes should
3032          * be gone.
3033          */
3034         locked = graph_lock();
3035         for (i = 0; i < CLASSHASH_SIZE; i++) {
3036                 head = classhash_table + i;
3037                 if (list_empty(head))
3038                         continue;
3039                 list_for_each_entry_safe(class, next, head, hash_entry) {
3040                         if (unlikely(class == lock->class_cache)) {
3041                                 if (debug_locks_off_graph_unlock())
3042                                         WARN_ON(1);
3043                                 goto out_restore;
3044                         }
3045                 }
3046         }
3047         if (locked)
3048                 graph_unlock();
3049
3050 out_restore:
3051         raw_local_irq_restore(flags);
3052 }
3053
3054 void lockdep_init(void)
3055 {
3056         int i;
3057
3058         /*
3059          * Some architectures have their own start_kernel()
3060          * code which calls lockdep_init(), while we also
3061          * call lockdep_init() from the start_kernel() itself,
3062          * and we want to initialize the hashes only once:
3063          */
3064         if (lockdep_initialized)
3065                 return;
3066
3067         for (i = 0; i < CLASSHASH_SIZE; i++)
3068                 INIT_LIST_HEAD(classhash_table + i);
3069
3070         for (i = 0; i < CHAINHASH_SIZE; i++)
3071                 INIT_LIST_HEAD(chainhash_table + i);
3072
3073         lockdep_initialized = 1;
3074 }
3075
3076 void __init lockdep_info(void)
3077 {
3078         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3079
3080         printk("... MAX_LOCKDEP_SUBCLASSES:    %lu\n", MAX_LOCKDEP_SUBCLASSES);
3081         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3082         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3083         printk("... CLASSHASH_SIZE:           %lu\n", CLASSHASH_SIZE);
3084         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3085         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3086         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3087
3088         printk(" memory used by lock dependency info: %lu kB\n",
3089                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3090                 sizeof(struct list_head) * CLASSHASH_SIZE +
3091                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3092                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3093                 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
3094
3095         printk(" per task-struct memory footprint: %lu bytes\n",
3096                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3097
3098 #ifdef CONFIG_DEBUG_LOCKDEP
3099         if (lockdep_init_error) {
3100                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3101                 printk("Call stack leading to lockdep invocation was:\n");
3102                 print_stack_trace(&lockdep_init_trace, 0);
3103         }
3104 #endif
3105 }
3106
3107 static void
3108 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3109                      const void *mem_to, struct held_lock *hlock)
3110 {
3111         if (!debug_locks_off())
3112                 return;
3113         if (debug_locks_silent)
3114                 return;
3115
3116         printk("\n=========================\n");
3117         printk(  "[ BUG: held lock freed! ]\n");
3118         printk(  "-------------------------\n");
3119         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3120                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3121         print_lock(hlock);
3122         lockdep_print_held_locks(curr);
3123
3124         printk("\nstack backtrace:\n");
3125         dump_stack();
3126 }
3127
3128 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3129                                 const void* lock_from, unsigned long lock_len)
3130 {
3131         return lock_from + lock_len <= mem_from ||
3132                 mem_from + mem_len <= lock_from;
3133 }
3134
3135 /*
3136  * Called when kernel memory is freed (or unmapped), or if a lock
3137  * is destroyed or reinitialized - this code checks whether there is
3138  * any held lock in the memory range of <from> to <to>:
3139  */
3140 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3141 {
3142         struct task_struct *curr = current;
3143         struct held_lock *hlock;
3144         unsigned long flags;
3145         int i;
3146
3147         if (unlikely(!debug_locks))
3148                 return;
3149
3150         local_irq_save(flags);
3151         for (i = 0; i < curr->lockdep_depth; i++) {
3152                 hlock = curr->held_locks + i;
3153
3154                 if (not_in_range(mem_from, mem_len, hlock->instance,
3155                                         sizeof(*hlock->instance)))
3156                         continue;
3157
3158                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3159                 break;
3160         }
3161         local_irq_restore(flags);
3162 }
3163 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3164
3165 static void print_held_locks_bug(struct task_struct *curr)
3166 {
3167         if (!debug_locks_off())
3168                 return;
3169         if (debug_locks_silent)
3170                 return;
3171
3172         printk("\n=====================================\n");
3173         printk(  "[ BUG: lock held at task exit time! ]\n");
3174         printk(  "-------------------------------------\n");
3175         printk("%s/%d is exiting with locks still held!\n",
3176                 curr->comm, task_pid_nr(curr));
3177         lockdep_print_held_locks(curr);
3178
3179         printk("\nstack backtrace:\n");
3180         dump_stack();
3181 }
3182
3183 void debug_check_no_locks_held(struct task_struct *task)
3184 {
3185         if (unlikely(task->lockdep_depth > 0))
3186                 print_held_locks_bug(task);
3187 }
3188
3189 void debug_show_all_locks(void)
3190 {
3191         struct task_struct *g, *p;
3192         int count = 10;
3193         int unlock = 1;
3194
3195         if (unlikely(!debug_locks)) {
3196                 printk("INFO: lockdep is turned off.\n");
3197                 return;
3198         }
3199         printk("\nShowing all locks held in the system:\n");
3200
3201         /*
3202          * Here we try to get the tasklist_lock as hard as possible,
3203          * if not successful after 2 seconds we ignore it (but keep
3204          * trying). This is to enable a debug printout even if a
3205          * tasklist_lock-holding task deadlocks or crashes.
3206          */
3207 retry:
3208         if (!read_trylock(&tasklist_lock)) {
3209                 if (count == 10)
3210                         printk("hm, tasklist_lock locked, retrying... ");
3211                 if (count) {
3212                         count--;
3213                         printk(" #%d", 10-count);
3214                         mdelay(200);
3215                         goto retry;
3216                 }
3217                 printk(" ignoring it.\n");
3218                 unlock = 0;
3219         }
3220         if (count != 10)
3221                 printk(" locked it.\n");
3222
3223         do_each_thread(g, p) {
3224                 /*
3225                  * It's not reliable to print a task's held locks
3226                  * if it's not sleeping (or if it's not the current
3227                  * task):
3228                  */
3229                 if (p->state == TASK_RUNNING && p != current)
3230                         continue;
3231                 if (p->lockdep_depth)
3232                         lockdep_print_held_locks(p);
3233                 if (!unlock)
3234                         if (read_trylock(&tasklist_lock))
3235                                 unlock = 1;
3236         } while_each_thread(g, p);
3237
3238         printk("\n");
3239         printk("=============================================\n\n");
3240
3241         if (unlock)
3242                 read_unlock(&tasklist_lock);
3243 }
3244
3245 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3246
3247 /*
3248  * Careful: only use this function if you are sure that
3249  * the task cannot run in parallel!
3250  */
3251 void __debug_show_held_locks(struct task_struct *task)
3252 {
3253         if (unlikely(!debug_locks)) {
3254                 printk("INFO: lockdep is turned off.\n");
3255                 return;
3256         }
3257         lockdep_print_held_locks(task);
3258 }
3259 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3260
3261 void debug_show_held_locks(struct task_struct *task)
3262 {
3263                 __debug_show_held_locks(task);
3264 }
3265
3266 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3267
3268 void lockdep_sys_exit(void)
3269 {
3270         struct task_struct *curr = current;
3271
3272         if (unlikely(curr->lockdep_depth)) {
3273                 if (!debug_locks_off())
3274                         return;
3275                 printk("\n================================================\n");
3276                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3277                 printk(  "------------------------------------------------\n");
3278                 printk("%s/%d is leaving the kernel with locks still held!\n",
3279                                 curr->comm, curr->pid);
3280                 lockdep_print_held_locks(curr);
3281         }
3282 }