lockstat: Make lockstat counting per cpu
[linux-3.10.git] / kernel / lockdep.c
1 /*
2  * kernel/lockdep.c
3  *
4  * Runtime locking correctness validator
5  *
6  * Started by Ingo Molnar:
7  *
8  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
10  *
11  * this code maps all the lock dependencies as they occur in a live kernel
12  * and will warn about the following classes of locking bugs:
13  *
14  * - lock inversion scenarios
15  * - circular lock dependencies
16  * - hardirq/softirq safe/unsafe locking bugs
17  *
18  * Bugs are reported even if the current locking scenario does not cause
19  * any deadlock at this point.
20  *
21  * I.e. if anytime in the past two locks were taken in a different order,
22  * even if it happened for another task, even if those were different
23  * locks (but of the same class as this lock), this code will detect it.
24  *
25  * Thanks to Arjan van de Ven for coming up with the initial idea of
26  * mapping lock dependencies runtime.
27  */
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46
47 #include <asm/sections.h>
48
49 #include "lockdep_internals.h"
50
51 #define CREATE_TRACE_POINTS
52 #include <trace/events/lock.h>
53
54 #ifdef CONFIG_PROVE_LOCKING
55 int prove_locking = 1;
56 module_param(prove_locking, int, 0644);
57 #else
58 #define prove_locking 0
59 #endif
60
61 #ifdef CONFIG_LOCK_STAT
62 int lock_stat = 1;
63 module_param(lock_stat, int, 0644);
64 #else
65 #define lock_stat 0
66 #endif
67
68 /*
69  * lockdep_lock: protects the lockdep graph, the hashes and the
70  *               class/list/hash allocators.
71  *
72  * This is one of the rare exceptions where it's justified
73  * to use a raw spinlock - we really dont want the spinlock
74  * code to recurse back into the lockdep code...
75  */
76 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
77
78 static int graph_lock(void)
79 {
80         arch_spin_lock(&lockdep_lock);
81         /*
82          * Make sure that if another CPU detected a bug while
83          * walking the graph we dont change it (while the other
84          * CPU is busy printing out stuff with the graph lock
85          * dropped already)
86          */
87         if (!debug_locks) {
88                 arch_spin_unlock(&lockdep_lock);
89                 return 0;
90         }
91         /* prevent any recursions within lockdep from causing deadlocks */
92         current->lockdep_recursion++;
93         return 1;
94 }
95
96 static inline int graph_unlock(void)
97 {
98         if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
99                 return DEBUG_LOCKS_WARN_ON(1);
100
101         current->lockdep_recursion--;
102         arch_spin_unlock(&lockdep_lock);
103         return 0;
104 }
105
106 /*
107  * Turn lock debugging off and return with 0 if it was off already,
108  * and also release the graph lock:
109  */
110 static inline int debug_locks_off_graph_unlock(void)
111 {
112         int ret = debug_locks_off();
113
114         arch_spin_unlock(&lockdep_lock);
115
116         return ret;
117 }
118
119 static int lockdep_initialized;
120
121 unsigned long nr_list_entries;
122 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
123
124 /*
125  * All data structures here are protected by the global debug_lock.
126  *
127  * Mutex key structs only get allocated, once during bootup, and never
128  * get freed - this significantly simplifies the debugging code.
129  */
130 unsigned long nr_lock_classes;
131 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
132
133 static inline struct lock_class *hlock_class(struct held_lock *hlock)
134 {
135         if (!hlock->class_idx) {
136                 DEBUG_LOCKS_WARN_ON(1);
137                 return NULL;
138         }
139         return lock_classes + hlock->class_idx - 1;
140 }
141
142 #ifdef CONFIG_LOCK_STAT
143 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
144                       cpu_lock_stats);
145
146 static inline u64 lockstat_clock(void)
147 {
148         return cpu_clock(smp_processor_id());
149 }
150
151 static int lock_point(unsigned long points[], unsigned long ip)
152 {
153         int i;
154
155         for (i = 0; i < LOCKSTAT_POINTS; i++) {
156                 if (points[i] == 0) {
157                         points[i] = ip;
158                         break;
159                 }
160                 if (points[i] == ip)
161                         break;
162         }
163
164         return i;
165 }
166
167 static void lock_time_inc(struct lock_time *lt, u64 time)
168 {
169         if (time > lt->max)
170                 lt->max = time;
171
172         if (time < lt->min || !lt->nr)
173                 lt->min = time;
174
175         lt->total += time;
176         lt->nr++;
177 }
178
179 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
180 {
181         if (!src->nr)
182                 return;
183
184         if (src->max > dst->max)
185                 dst->max = src->max;
186
187         if (src->min < dst->min || !dst->nr)
188                 dst->min = src->min;
189
190         dst->total += src->total;
191         dst->nr += src->nr;
192 }
193
194 struct lock_class_stats lock_stats(struct lock_class *class)
195 {
196         struct lock_class_stats stats;
197         int cpu, i;
198
199         memset(&stats, 0, sizeof(struct lock_class_stats));
200         for_each_possible_cpu(cpu) {
201                 struct lock_class_stats *pcs =
202                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
203
204                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
205                         stats.contention_point[i] += pcs->contention_point[i];
206
207                 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
208                         stats.contending_point[i] += pcs->contending_point[i];
209
210                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
211                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
212
213                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
214                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
215
216                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
217                         stats.bounces[i] += pcs->bounces[i];
218         }
219
220         return stats;
221 }
222
223 void clear_lock_stats(struct lock_class *class)
224 {
225         int cpu;
226
227         for_each_possible_cpu(cpu) {
228                 struct lock_class_stats *cpu_stats =
229                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
230
231                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
232         }
233         memset(class->contention_point, 0, sizeof(class->contention_point));
234         memset(class->contending_point, 0, sizeof(class->contending_point));
235 }
236
237 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
238 {
239         return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
240 }
241
242 static void put_lock_stats(struct lock_class_stats *stats)
243 {
244         put_cpu_var(cpu_lock_stats);
245 }
246
247 static void lock_release_holdtime(struct held_lock *hlock)
248 {
249         struct lock_class_stats *stats;
250         u64 holdtime;
251
252         if (!lock_stat)
253                 return;
254
255         holdtime = lockstat_clock() - hlock->holdtime_stamp;
256
257         stats = get_lock_stats(hlock_class(hlock));
258         if (hlock->read)
259                 lock_time_inc(&stats->read_holdtime, holdtime);
260         else
261                 lock_time_inc(&stats->write_holdtime, holdtime);
262         put_lock_stats(stats);
263 }
264 #else
265 static inline void lock_release_holdtime(struct held_lock *hlock)
266 {
267 }
268 #endif
269
270 /*
271  * We keep a global list of all lock classes. The list only grows,
272  * never shrinks. The list is only accessed with the lockdep
273  * spinlock lock held.
274  */
275 LIST_HEAD(all_lock_classes);
276
277 /*
278  * The lockdep classes are in a hash-table as well, for fast lookup:
279  */
280 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
281 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
282 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
283 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
284
285 static struct list_head classhash_table[CLASSHASH_SIZE];
286
287 /*
288  * We put the lock dependency chains into a hash-table as well, to cache
289  * their existence:
290  */
291 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
292 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
293 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
294 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
295
296 static struct list_head chainhash_table[CHAINHASH_SIZE];
297
298 /*
299  * The hash key of the lock dependency chains is a hash itself too:
300  * it's a hash of all locks taken up to that lock, including that lock.
301  * It's a 64-bit hash, because it's important for the keys to be
302  * unique.
303  */
304 #define iterate_chain_key(key1, key2) \
305         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
306         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
307         (key2))
308
309 void lockdep_off(void)
310 {
311         current->lockdep_recursion++;
312 }
313 EXPORT_SYMBOL(lockdep_off);
314
315 void lockdep_on(void)
316 {
317         current->lockdep_recursion--;
318 }
319 EXPORT_SYMBOL(lockdep_on);
320
321 /*
322  * Debugging switches:
323  */
324
325 #define VERBOSE                 0
326 #define VERY_VERBOSE            0
327
328 #if VERBOSE
329 # define HARDIRQ_VERBOSE        1
330 # define SOFTIRQ_VERBOSE        1
331 # define RECLAIM_VERBOSE        1
332 #else
333 # define HARDIRQ_VERBOSE        0
334 # define SOFTIRQ_VERBOSE        0
335 # define RECLAIM_VERBOSE        0
336 #endif
337
338 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
339 /*
340  * Quick filtering for interesting events:
341  */
342 static int class_filter(struct lock_class *class)
343 {
344 #if 0
345         /* Example */
346         if (class->name_version == 1 &&
347                         !strcmp(class->name, "lockname"))
348                 return 1;
349         if (class->name_version == 1 &&
350                         !strcmp(class->name, "&struct->lockfield"))
351                 return 1;
352 #endif
353         /* Filter everything else. 1 would be to allow everything else */
354         return 0;
355 }
356 #endif
357
358 static int verbose(struct lock_class *class)
359 {
360 #if VERBOSE
361         return class_filter(class);
362 #endif
363         return 0;
364 }
365
366 /*
367  * Stack-trace: tightly packed array of stack backtrace
368  * addresses. Protected by the graph_lock.
369  */
370 unsigned long nr_stack_trace_entries;
371 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
372
373 static int save_trace(struct stack_trace *trace)
374 {
375         trace->nr_entries = 0;
376         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
377         trace->entries = stack_trace + nr_stack_trace_entries;
378
379         trace->skip = 3;
380
381         save_stack_trace(trace);
382
383         /*
384          * Some daft arches put -1 at the end to indicate its a full trace.
385          *
386          * <rant> this is buggy anyway, since it takes a whole extra entry so a
387          * complete trace that maxes out the entries provided will be reported
388          * as incomplete, friggin useless </rant>
389          */
390         if (trace->nr_entries != 0 &&
391             trace->entries[trace->nr_entries-1] == ULONG_MAX)
392                 trace->nr_entries--;
393
394         trace->max_entries = trace->nr_entries;
395
396         nr_stack_trace_entries += trace->nr_entries;
397
398         if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
399                 if (!debug_locks_off_graph_unlock())
400                         return 0;
401
402                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
403                 printk("turning off the locking correctness validator.\n");
404                 dump_stack();
405
406                 return 0;
407         }
408
409         return 1;
410 }
411
412 unsigned int nr_hardirq_chains;
413 unsigned int nr_softirq_chains;
414 unsigned int nr_process_chains;
415 unsigned int max_lockdep_depth;
416
417 #ifdef CONFIG_DEBUG_LOCKDEP
418 /*
419  * We cannot printk in early bootup code. Not even early_printk()
420  * might work. So we mark any initialization errors and printk
421  * about it later on, in lockdep_info().
422  */
423 static int lockdep_init_error;
424 static unsigned long lockdep_init_trace_data[20];
425 static struct stack_trace lockdep_init_trace = {
426         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
427         .entries = lockdep_init_trace_data,
428 };
429
430 /*
431  * Various lockdep statistics:
432  */
433 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
434 #endif
435
436 /*
437  * Locking printouts:
438  */
439
440 #define __USAGE(__STATE)                                                \
441         [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
442         [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
443         [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
444         [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
445
446 static const char *usage_str[] =
447 {
448 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
449 #include "lockdep_states.h"
450 #undef LOCKDEP_STATE
451         [LOCK_USED] = "INITIAL USE",
452 };
453
454 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
455 {
456         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
457 }
458
459 static inline unsigned long lock_flag(enum lock_usage_bit bit)
460 {
461         return 1UL << bit;
462 }
463
464 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
465 {
466         char c = '.';
467
468         if (class->usage_mask & lock_flag(bit + 2))
469                 c = '+';
470         if (class->usage_mask & lock_flag(bit)) {
471                 c = '-';
472                 if (class->usage_mask & lock_flag(bit + 2))
473                         c = '?';
474         }
475
476         return c;
477 }
478
479 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
480 {
481         int i = 0;
482
483 #define LOCKDEP_STATE(__STATE)                                          \
484         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
485         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
486 #include "lockdep_states.h"
487 #undef LOCKDEP_STATE
488
489         usage[i] = '\0';
490 }
491
492 static void print_lock_name(struct lock_class *class)
493 {
494         char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
495         const char *name;
496
497         get_usage_chars(class, usage);
498
499         name = class->name;
500         if (!name) {
501                 name = __get_key_name(class->key, str);
502                 printk(" (%s", name);
503         } else {
504                 printk(" (%s", name);
505                 if (class->name_version > 1)
506                         printk("#%d", class->name_version);
507                 if (class->subclass)
508                         printk("/%d", class->subclass);
509         }
510         printk("){%s}", usage);
511 }
512
513 static void print_lockdep_cache(struct lockdep_map *lock)
514 {
515         const char *name;
516         char str[KSYM_NAME_LEN];
517
518         name = lock->name;
519         if (!name)
520                 name = __get_key_name(lock->key->subkeys, str);
521
522         printk("%s", name);
523 }
524
525 static void print_lock(struct held_lock *hlock)
526 {
527         print_lock_name(hlock_class(hlock));
528         printk(", at: ");
529         print_ip_sym(hlock->acquire_ip);
530 }
531
532 static void lockdep_print_held_locks(struct task_struct *curr)
533 {
534         int i, depth = curr->lockdep_depth;
535
536         if (!depth) {
537                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
538                 return;
539         }
540         printk("%d lock%s held by %s/%d:\n",
541                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
542
543         for (i = 0; i < depth; i++) {
544                 printk(" #%d: ", i);
545                 print_lock(curr->held_locks + i);
546         }
547 }
548
549 static void print_kernel_version(void)
550 {
551         printk("%s %.*s\n", init_utsname()->release,
552                 (int)strcspn(init_utsname()->version, " "),
553                 init_utsname()->version);
554 }
555
556 static int very_verbose(struct lock_class *class)
557 {
558 #if VERY_VERBOSE
559         return class_filter(class);
560 #endif
561         return 0;
562 }
563
564 /*
565  * Is this the address of a static object:
566  */
567 static int static_obj(void *obj)
568 {
569         unsigned long start = (unsigned long) &_stext,
570                       end   = (unsigned long) &_end,
571                       addr  = (unsigned long) obj;
572 #ifdef CONFIG_SMP
573         int i;
574 #endif
575
576         /*
577          * static variable?
578          */
579         if ((addr >= start) && (addr < end))
580                 return 1;
581
582         if (arch_is_kernel_data(addr))
583                 return 1;
584
585 #ifdef CONFIG_SMP
586         /*
587          * percpu var?
588          */
589         for_each_possible_cpu(i) {
590                 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
591                 end   = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
592                                         + per_cpu_offset(i);
593
594                 if ((addr >= start) && (addr < end))
595                         return 1;
596         }
597 #endif
598
599         /*
600          * module var?
601          */
602         return is_module_address(addr);
603 }
604
605 /*
606  * To make lock name printouts unique, we calculate a unique
607  * class->name_version generation counter:
608  */
609 static int count_matching_names(struct lock_class *new_class)
610 {
611         struct lock_class *class;
612         int count = 0;
613
614         if (!new_class->name)
615                 return 0;
616
617         list_for_each_entry(class, &all_lock_classes, lock_entry) {
618                 if (new_class->key - new_class->subclass == class->key)
619                         return class->name_version;
620                 if (class->name && !strcmp(class->name, new_class->name))
621                         count = max(count, class->name_version);
622         }
623
624         return count + 1;
625 }
626
627 /*
628  * Register a lock's class in the hash-table, if the class is not present
629  * yet. Otherwise we look it up. We cache the result in the lock object
630  * itself, so actual lookup of the hash should be once per lock object.
631  */
632 static inline struct lock_class *
633 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
634 {
635         struct lockdep_subclass_key *key;
636         struct list_head *hash_head;
637         struct lock_class *class;
638
639 #ifdef CONFIG_DEBUG_LOCKDEP
640         /*
641          * If the architecture calls into lockdep before initializing
642          * the hashes then we'll warn about it later. (we cannot printk
643          * right now)
644          */
645         if (unlikely(!lockdep_initialized)) {
646                 lockdep_init();
647                 lockdep_init_error = 1;
648                 save_stack_trace(&lockdep_init_trace);
649         }
650 #endif
651
652         /*
653          * Static locks do not have their class-keys yet - for them the key
654          * is the lock object itself:
655          */
656         if (unlikely(!lock->key))
657                 lock->key = (void *)lock;
658
659         /*
660          * NOTE: the class-key must be unique. For dynamic locks, a static
661          * lock_class_key variable is passed in through the mutex_init()
662          * (or spin_lock_init()) call - which acts as the key. For static
663          * locks we use the lock object itself as the key.
664          */
665         BUILD_BUG_ON(sizeof(struct lock_class_key) >
666                         sizeof(struct lockdep_map));
667
668         key = lock->key->subkeys + subclass;
669
670         hash_head = classhashentry(key);
671
672         /*
673          * We can walk the hash lockfree, because the hash only
674          * grows, and we are careful when adding entries to the end:
675          */
676         list_for_each_entry(class, hash_head, hash_entry) {
677                 if (class->key == key) {
678                         WARN_ON_ONCE(class->name != lock->name);
679                         return class;
680                 }
681         }
682
683         return NULL;
684 }
685
686 /*
687  * Register a lock's class in the hash-table, if the class is not present
688  * yet. Otherwise we look it up. We cache the result in the lock object
689  * itself, so actual lookup of the hash should be once per lock object.
690  */
691 static inline struct lock_class *
692 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
693 {
694         struct lockdep_subclass_key *key;
695         struct list_head *hash_head;
696         struct lock_class *class;
697         unsigned long flags;
698
699         class = look_up_lock_class(lock, subclass);
700         if (likely(class))
701                 return class;
702
703         /*
704          * Debug-check: all keys must be persistent!
705          */
706         if (!static_obj(lock->key)) {
707                 debug_locks_off();
708                 printk("INFO: trying to register non-static key.\n");
709                 printk("the code is fine but needs lockdep annotation.\n");
710                 printk("turning off the locking correctness validator.\n");
711                 dump_stack();
712
713                 return NULL;
714         }
715
716         key = lock->key->subkeys + subclass;
717         hash_head = classhashentry(key);
718
719         raw_local_irq_save(flags);
720         if (!graph_lock()) {
721                 raw_local_irq_restore(flags);
722                 return NULL;
723         }
724         /*
725          * We have to do the hash-walk again, to avoid races
726          * with another CPU:
727          */
728         list_for_each_entry(class, hash_head, hash_entry)
729                 if (class->key == key)
730                         goto out_unlock_set;
731         /*
732          * Allocate a new key from the static array, and add it to
733          * the hash:
734          */
735         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
736                 if (!debug_locks_off_graph_unlock()) {
737                         raw_local_irq_restore(flags);
738                         return NULL;
739                 }
740                 raw_local_irq_restore(flags);
741
742                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
743                 printk("turning off the locking correctness validator.\n");
744                 dump_stack();
745                 return NULL;
746         }
747         class = lock_classes + nr_lock_classes++;
748         debug_atomic_inc(nr_unused_locks);
749         class->key = key;
750         class->name = lock->name;
751         class->subclass = subclass;
752         INIT_LIST_HEAD(&class->lock_entry);
753         INIT_LIST_HEAD(&class->locks_before);
754         INIT_LIST_HEAD(&class->locks_after);
755         class->name_version = count_matching_names(class);
756         /*
757          * We use RCU's safe list-add method to make
758          * parallel walking of the hash-list safe:
759          */
760         list_add_tail_rcu(&class->hash_entry, hash_head);
761         /*
762          * Add it to the global list of classes:
763          */
764         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
765
766         if (verbose(class)) {
767                 graph_unlock();
768                 raw_local_irq_restore(flags);
769
770                 printk("\nnew class %p: %s", class->key, class->name);
771                 if (class->name_version > 1)
772                         printk("#%d", class->name_version);
773                 printk("\n");
774                 dump_stack();
775
776                 raw_local_irq_save(flags);
777                 if (!graph_lock()) {
778                         raw_local_irq_restore(flags);
779                         return NULL;
780                 }
781         }
782 out_unlock_set:
783         graph_unlock();
784         raw_local_irq_restore(flags);
785
786         if (!subclass || force)
787                 lock->class_cache = class;
788
789         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
790                 return NULL;
791
792         return class;
793 }
794
795 #ifdef CONFIG_PROVE_LOCKING
796 /*
797  * Allocate a lockdep entry. (assumes the graph_lock held, returns
798  * with NULL on failure)
799  */
800 static struct lock_list *alloc_list_entry(void)
801 {
802         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
803                 if (!debug_locks_off_graph_unlock())
804                         return NULL;
805
806                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
807                 printk("turning off the locking correctness validator.\n");
808                 dump_stack();
809                 return NULL;
810         }
811         return list_entries + nr_list_entries++;
812 }
813
814 /*
815  * Add a new dependency to the head of the list:
816  */
817 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
818                             struct list_head *head, unsigned long ip, int distance)
819 {
820         struct lock_list *entry;
821         /*
822          * Lock not present yet - get a new dependency struct and
823          * add it to the list:
824          */
825         entry = alloc_list_entry();
826         if (!entry)
827                 return 0;
828
829         if (!save_trace(&entry->trace))
830                 return 0;
831
832         entry->class = this;
833         entry->distance = distance;
834         /*
835          * Since we never remove from the dependency list, the list can
836          * be walked lockless by other CPUs, it's only allocation
837          * that must be protected by the spinlock. But this also means
838          * we must make new entries visible only once writes to the
839          * entry become visible - hence the RCU op:
840          */
841         list_add_tail_rcu(&entry->entry, head);
842
843         return 1;
844 }
845
846 /*
847  * For good efficiency of modular, we use power of 2
848  */
849 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
850 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
851
852 /*
853  * The circular_queue and helpers is used to implement the
854  * breadth-first search(BFS)algorithem, by which we can build
855  * the shortest path from the next lock to be acquired to the
856  * previous held lock if there is a circular between them.
857  */
858 struct circular_queue {
859         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
860         unsigned int  front, rear;
861 };
862
863 static struct circular_queue lock_cq;
864
865 unsigned int max_bfs_queue_depth;
866
867 static unsigned int lockdep_dependency_gen_id;
868
869 static inline void __cq_init(struct circular_queue *cq)
870 {
871         cq->front = cq->rear = 0;
872         lockdep_dependency_gen_id++;
873 }
874
875 static inline int __cq_empty(struct circular_queue *cq)
876 {
877         return (cq->front == cq->rear);
878 }
879
880 static inline int __cq_full(struct circular_queue *cq)
881 {
882         return ((cq->rear + 1) & CQ_MASK) == cq->front;
883 }
884
885 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
886 {
887         if (__cq_full(cq))
888                 return -1;
889
890         cq->element[cq->rear] = elem;
891         cq->rear = (cq->rear + 1) & CQ_MASK;
892         return 0;
893 }
894
895 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
896 {
897         if (__cq_empty(cq))
898                 return -1;
899
900         *elem = cq->element[cq->front];
901         cq->front = (cq->front + 1) & CQ_MASK;
902         return 0;
903 }
904
905 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
906 {
907         return (cq->rear - cq->front) & CQ_MASK;
908 }
909
910 static inline void mark_lock_accessed(struct lock_list *lock,
911                                         struct lock_list *parent)
912 {
913         unsigned long nr;
914
915         nr = lock - list_entries;
916         WARN_ON(nr >= nr_list_entries);
917         lock->parent = parent;
918         lock->class->dep_gen_id = lockdep_dependency_gen_id;
919 }
920
921 static inline unsigned long lock_accessed(struct lock_list *lock)
922 {
923         unsigned long nr;
924
925         nr = lock - list_entries;
926         WARN_ON(nr >= nr_list_entries);
927         return lock->class->dep_gen_id == lockdep_dependency_gen_id;
928 }
929
930 static inline struct lock_list *get_lock_parent(struct lock_list *child)
931 {
932         return child->parent;
933 }
934
935 static inline int get_lock_depth(struct lock_list *child)
936 {
937         int depth = 0;
938         struct lock_list *parent;
939
940         while ((parent = get_lock_parent(child))) {
941                 child = parent;
942                 depth++;
943         }
944         return depth;
945 }
946
947 static int __bfs(struct lock_list *source_entry,
948                  void *data,
949                  int (*match)(struct lock_list *entry, void *data),
950                  struct lock_list **target_entry,
951                  int forward)
952 {
953         struct lock_list *entry;
954         struct list_head *head;
955         struct circular_queue *cq = &lock_cq;
956         int ret = 1;
957
958         if (match(source_entry, data)) {
959                 *target_entry = source_entry;
960                 ret = 0;
961                 goto exit;
962         }
963
964         if (forward)
965                 head = &source_entry->class->locks_after;
966         else
967                 head = &source_entry->class->locks_before;
968
969         if (list_empty(head))
970                 goto exit;
971
972         __cq_init(cq);
973         __cq_enqueue(cq, (unsigned long)source_entry);
974
975         while (!__cq_empty(cq)) {
976                 struct lock_list *lock;
977
978                 __cq_dequeue(cq, (unsigned long *)&lock);
979
980                 if (!lock->class) {
981                         ret = -2;
982                         goto exit;
983                 }
984
985                 if (forward)
986                         head = &lock->class->locks_after;
987                 else
988                         head = &lock->class->locks_before;
989
990                 list_for_each_entry(entry, head, entry) {
991                         if (!lock_accessed(entry)) {
992                                 unsigned int cq_depth;
993                                 mark_lock_accessed(entry, lock);
994                                 if (match(entry, data)) {
995                                         *target_entry = entry;
996                                         ret = 0;
997                                         goto exit;
998                                 }
999
1000                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
1001                                         ret = -1;
1002                                         goto exit;
1003                                 }
1004                                 cq_depth = __cq_get_elem_count(cq);
1005                                 if (max_bfs_queue_depth < cq_depth)
1006                                         max_bfs_queue_depth = cq_depth;
1007                         }
1008                 }
1009         }
1010 exit:
1011         return ret;
1012 }
1013
1014 static inline int __bfs_forwards(struct lock_list *src_entry,
1015                         void *data,
1016                         int (*match)(struct lock_list *entry, void *data),
1017                         struct lock_list **target_entry)
1018 {
1019         return __bfs(src_entry, data, match, target_entry, 1);
1020
1021 }
1022
1023 static inline int __bfs_backwards(struct lock_list *src_entry,
1024                         void *data,
1025                         int (*match)(struct lock_list *entry, void *data),
1026                         struct lock_list **target_entry)
1027 {
1028         return __bfs(src_entry, data, match, target_entry, 0);
1029
1030 }
1031
1032 /*
1033  * Recursive, forwards-direction lock-dependency checking, used for
1034  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1035  * checking.
1036  */
1037
1038 /*
1039  * Print a dependency chain entry (this is only done when a deadlock
1040  * has been detected):
1041  */
1042 static noinline int
1043 print_circular_bug_entry(struct lock_list *target, int depth)
1044 {
1045         if (debug_locks_silent)
1046                 return 0;
1047         printk("\n-> #%u", depth);
1048         print_lock_name(target->class);
1049         printk(":\n");
1050         print_stack_trace(&target->trace, 6);
1051
1052         return 0;
1053 }
1054
1055 /*
1056  * When a circular dependency is detected, print the
1057  * header first:
1058  */
1059 static noinline int
1060 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1061                         struct held_lock *check_src,
1062                         struct held_lock *check_tgt)
1063 {
1064         struct task_struct *curr = current;
1065
1066         if (debug_locks_silent)
1067                 return 0;
1068
1069         printk("\n=======================================================\n");
1070         printk(  "[ INFO: possible circular locking dependency detected ]\n");
1071         print_kernel_version();
1072         printk(  "-------------------------------------------------------\n");
1073         printk("%s/%d is trying to acquire lock:\n",
1074                 curr->comm, task_pid_nr(curr));
1075         print_lock(check_src);
1076         printk("\nbut task is already holding lock:\n");
1077         print_lock(check_tgt);
1078         printk("\nwhich lock already depends on the new lock.\n\n");
1079         printk("\nthe existing dependency chain (in reverse order) is:\n");
1080
1081         print_circular_bug_entry(entry, depth);
1082
1083         return 0;
1084 }
1085
1086 static inline int class_equal(struct lock_list *entry, void *data)
1087 {
1088         return entry->class == data;
1089 }
1090
1091 static noinline int print_circular_bug(struct lock_list *this,
1092                                 struct lock_list *target,
1093                                 struct held_lock *check_src,
1094                                 struct held_lock *check_tgt)
1095 {
1096         struct task_struct *curr = current;
1097         struct lock_list *parent;
1098         int depth;
1099
1100         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1101                 return 0;
1102
1103         if (!save_trace(&this->trace))
1104                 return 0;
1105
1106         depth = get_lock_depth(target);
1107
1108         print_circular_bug_header(target, depth, check_src, check_tgt);
1109
1110         parent = get_lock_parent(target);
1111
1112         while (parent) {
1113                 print_circular_bug_entry(parent, --depth);
1114                 parent = get_lock_parent(parent);
1115         }
1116
1117         printk("\nother info that might help us debug this:\n\n");
1118         lockdep_print_held_locks(curr);
1119
1120         printk("\nstack backtrace:\n");
1121         dump_stack();
1122
1123         return 0;
1124 }
1125
1126 static noinline int print_bfs_bug(int ret)
1127 {
1128         if (!debug_locks_off_graph_unlock())
1129                 return 0;
1130
1131         WARN(1, "lockdep bfs error:%d\n", ret);
1132
1133         return 0;
1134 }
1135
1136 static int noop_count(struct lock_list *entry, void *data)
1137 {
1138         (*(unsigned long *)data)++;
1139         return 0;
1140 }
1141
1142 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1143 {
1144         unsigned long  count = 0;
1145         struct lock_list *uninitialized_var(target_entry);
1146
1147         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1148
1149         return count;
1150 }
1151 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1152 {
1153         unsigned long ret, flags;
1154         struct lock_list this;
1155
1156         this.parent = NULL;
1157         this.class = class;
1158
1159         local_irq_save(flags);
1160         arch_spin_lock(&lockdep_lock);
1161         ret = __lockdep_count_forward_deps(&this);
1162         arch_spin_unlock(&lockdep_lock);
1163         local_irq_restore(flags);
1164
1165         return ret;
1166 }
1167
1168 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1169 {
1170         unsigned long  count = 0;
1171         struct lock_list *uninitialized_var(target_entry);
1172
1173         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1174
1175         return count;
1176 }
1177
1178 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1179 {
1180         unsigned long ret, flags;
1181         struct lock_list this;
1182
1183         this.parent = NULL;
1184         this.class = class;
1185
1186         local_irq_save(flags);
1187         arch_spin_lock(&lockdep_lock);
1188         ret = __lockdep_count_backward_deps(&this);
1189         arch_spin_unlock(&lockdep_lock);
1190         local_irq_restore(flags);
1191
1192         return ret;
1193 }
1194
1195 /*
1196  * Prove that the dependency graph starting at <entry> can not
1197  * lead to <target>. Print an error and return 0 if it does.
1198  */
1199 static noinline int
1200 check_noncircular(struct lock_list *root, struct lock_class *target,
1201                 struct lock_list **target_entry)
1202 {
1203         int result;
1204
1205         debug_atomic_inc(nr_cyclic_checks);
1206
1207         result = __bfs_forwards(root, target, class_equal, target_entry);
1208
1209         return result;
1210 }
1211
1212 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1213 /*
1214  * Forwards and backwards subgraph searching, for the purposes of
1215  * proving that two subgraphs can be connected by a new dependency
1216  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1217  */
1218
1219 static inline int usage_match(struct lock_list *entry, void *bit)
1220 {
1221         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1222 }
1223
1224
1225
1226 /*
1227  * Find a node in the forwards-direction dependency sub-graph starting
1228  * at @root->class that matches @bit.
1229  *
1230  * Return 0 if such a node exists in the subgraph, and put that node
1231  * into *@target_entry.
1232  *
1233  * Return 1 otherwise and keep *@target_entry unchanged.
1234  * Return <0 on error.
1235  */
1236 static int
1237 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1238                         struct lock_list **target_entry)
1239 {
1240         int result;
1241
1242         debug_atomic_inc(nr_find_usage_forwards_checks);
1243
1244         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1245
1246         return result;
1247 }
1248
1249 /*
1250  * Find a node in the backwards-direction dependency sub-graph starting
1251  * at @root->class that matches @bit.
1252  *
1253  * Return 0 if such a node exists in the subgraph, and put that node
1254  * into *@target_entry.
1255  *
1256  * Return 1 otherwise and keep *@target_entry unchanged.
1257  * Return <0 on error.
1258  */
1259 static int
1260 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1261                         struct lock_list **target_entry)
1262 {
1263         int result;
1264
1265         debug_atomic_inc(nr_find_usage_backwards_checks);
1266
1267         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1268
1269         return result;
1270 }
1271
1272 static void print_lock_class_header(struct lock_class *class, int depth)
1273 {
1274         int bit;
1275
1276         printk("%*s->", depth, "");
1277         print_lock_name(class);
1278         printk(" ops: %lu", class->ops);
1279         printk(" {\n");
1280
1281         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1282                 if (class->usage_mask & (1 << bit)) {
1283                         int len = depth;
1284
1285                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1286                         len += printk(" at:\n");
1287                         print_stack_trace(class->usage_traces + bit, len);
1288                 }
1289         }
1290         printk("%*s }\n", depth, "");
1291
1292         printk("%*s ... key      at: ",depth,"");
1293         print_ip_sym((unsigned long)class->key);
1294 }
1295
1296 /*
1297  * printk the shortest lock dependencies from @start to @end in reverse order:
1298  */
1299 static void __used
1300 print_shortest_lock_dependencies(struct lock_list *leaf,
1301                                 struct lock_list *root)
1302 {
1303         struct lock_list *entry = leaf;
1304         int depth;
1305
1306         /*compute depth from generated tree by BFS*/
1307         depth = get_lock_depth(leaf);
1308
1309         do {
1310                 print_lock_class_header(entry->class, depth);
1311                 printk("%*s ... acquired at:\n", depth, "");
1312                 print_stack_trace(&entry->trace, 2);
1313                 printk("\n");
1314
1315                 if (depth == 0 && (entry != root)) {
1316                         printk("lockdep:%s bad BFS generated tree\n", __func__);
1317                         break;
1318                 }
1319
1320                 entry = get_lock_parent(entry);
1321                 depth--;
1322         } while (entry && (depth >= 0));
1323
1324         return;
1325 }
1326
1327 static int
1328 print_bad_irq_dependency(struct task_struct *curr,
1329                          struct lock_list *prev_root,
1330                          struct lock_list *next_root,
1331                          struct lock_list *backwards_entry,
1332                          struct lock_list *forwards_entry,
1333                          struct held_lock *prev,
1334                          struct held_lock *next,
1335                          enum lock_usage_bit bit1,
1336                          enum lock_usage_bit bit2,
1337                          const char *irqclass)
1338 {
1339         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1340                 return 0;
1341
1342         printk("\n======================================================\n");
1343         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1344                 irqclass, irqclass);
1345         print_kernel_version();
1346         printk(  "------------------------------------------------------\n");
1347         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1348                 curr->comm, task_pid_nr(curr),
1349                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1350                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1351                 curr->hardirqs_enabled,
1352                 curr->softirqs_enabled);
1353         print_lock(next);
1354
1355         printk("\nand this task is already holding:\n");
1356         print_lock(prev);
1357         printk("which would create a new lock dependency:\n");
1358         print_lock_name(hlock_class(prev));
1359         printk(" ->");
1360         print_lock_name(hlock_class(next));
1361         printk("\n");
1362
1363         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1364                 irqclass);
1365         print_lock_name(backwards_entry->class);
1366         printk("\n... which became %s-irq-safe at:\n", irqclass);
1367
1368         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1369
1370         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1371         print_lock_name(forwards_entry->class);
1372         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1373         printk("...");
1374
1375         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1376
1377         printk("\nother info that might help us debug this:\n\n");
1378         lockdep_print_held_locks(curr);
1379
1380         printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1381         printk(" and the holding lock:\n");
1382         if (!save_trace(&prev_root->trace))
1383                 return 0;
1384         print_shortest_lock_dependencies(backwards_entry, prev_root);
1385
1386         printk("\nthe dependencies between the lock to be acquired");
1387         printk(" and %s-irq-unsafe lock:\n", irqclass);
1388         if (!save_trace(&next_root->trace))
1389                 return 0;
1390         print_shortest_lock_dependencies(forwards_entry, next_root);
1391
1392         printk("\nstack backtrace:\n");
1393         dump_stack();
1394
1395         return 0;
1396 }
1397
1398 static int
1399 check_usage(struct task_struct *curr, struct held_lock *prev,
1400             struct held_lock *next, enum lock_usage_bit bit_backwards,
1401             enum lock_usage_bit bit_forwards, const char *irqclass)
1402 {
1403         int ret;
1404         struct lock_list this, that;
1405         struct lock_list *uninitialized_var(target_entry);
1406         struct lock_list *uninitialized_var(target_entry1);
1407
1408         this.parent = NULL;
1409
1410         this.class = hlock_class(prev);
1411         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1412         if (ret < 0)
1413                 return print_bfs_bug(ret);
1414         if (ret == 1)
1415                 return ret;
1416
1417         that.parent = NULL;
1418         that.class = hlock_class(next);
1419         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1420         if (ret < 0)
1421                 return print_bfs_bug(ret);
1422         if (ret == 1)
1423                 return ret;
1424
1425         return print_bad_irq_dependency(curr, &this, &that,
1426                         target_entry, target_entry1,
1427                         prev, next,
1428                         bit_backwards, bit_forwards, irqclass);
1429 }
1430
1431 static const char *state_names[] = {
1432 #define LOCKDEP_STATE(__STATE) \
1433         __stringify(__STATE),
1434 #include "lockdep_states.h"
1435 #undef LOCKDEP_STATE
1436 };
1437
1438 static const char *state_rnames[] = {
1439 #define LOCKDEP_STATE(__STATE) \
1440         __stringify(__STATE)"-READ",
1441 #include "lockdep_states.h"
1442 #undef LOCKDEP_STATE
1443 };
1444
1445 static inline const char *state_name(enum lock_usage_bit bit)
1446 {
1447         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1448 }
1449
1450 static int exclusive_bit(int new_bit)
1451 {
1452         /*
1453          * USED_IN
1454          * USED_IN_READ
1455          * ENABLED
1456          * ENABLED_READ
1457          *
1458          * bit 0 - write/read
1459          * bit 1 - used_in/enabled
1460          * bit 2+  state
1461          */
1462
1463         int state = new_bit & ~3;
1464         int dir = new_bit & 2;
1465
1466         /*
1467          * keep state, bit flip the direction and strip read.
1468          */
1469         return state | (dir ^ 2);
1470 }
1471
1472 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1473                            struct held_lock *next, enum lock_usage_bit bit)
1474 {
1475         /*
1476          * Prove that the new dependency does not connect a hardirq-safe
1477          * lock with a hardirq-unsafe lock - to achieve this we search
1478          * the backwards-subgraph starting at <prev>, and the
1479          * forwards-subgraph starting at <next>:
1480          */
1481         if (!check_usage(curr, prev, next, bit,
1482                            exclusive_bit(bit), state_name(bit)))
1483                 return 0;
1484
1485         bit++; /* _READ */
1486
1487         /*
1488          * Prove that the new dependency does not connect a hardirq-safe-read
1489          * lock with a hardirq-unsafe lock - to achieve this we search
1490          * the backwards-subgraph starting at <prev>, and the
1491          * forwards-subgraph starting at <next>:
1492          */
1493         if (!check_usage(curr, prev, next, bit,
1494                            exclusive_bit(bit), state_name(bit)))
1495                 return 0;
1496
1497         return 1;
1498 }
1499
1500 static int
1501 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1502                 struct held_lock *next)
1503 {
1504 #define LOCKDEP_STATE(__STATE)                                          \
1505         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1506                 return 0;
1507 #include "lockdep_states.h"
1508 #undef LOCKDEP_STATE
1509
1510         return 1;
1511 }
1512
1513 static void inc_chains(void)
1514 {
1515         if (current->hardirq_context)
1516                 nr_hardirq_chains++;
1517         else {
1518                 if (current->softirq_context)
1519                         nr_softirq_chains++;
1520                 else
1521                         nr_process_chains++;
1522         }
1523 }
1524
1525 #else
1526
1527 static inline int
1528 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1529                 struct held_lock *next)
1530 {
1531         return 1;
1532 }
1533
1534 static inline void inc_chains(void)
1535 {
1536         nr_process_chains++;
1537 }
1538
1539 #endif
1540
1541 static int
1542 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1543                    struct held_lock *next)
1544 {
1545         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1546                 return 0;
1547
1548         printk("\n=============================================\n");
1549         printk(  "[ INFO: possible recursive locking detected ]\n");
1550         print_kernel_version();
1551         printk(  "---------------------------------------------\n");
1552         printk("%s/%d is trying to acquire lock:\n",
1553                 curr->comm, task_pid_nr(curr));
1554         print_lock(next);
1555         printk("\nbut task is already holding lock:\n");
1556         print_lock(prev);
1557
1558         printk("\nother info that might help us debug this:\n");
1559         lockdep_print_held_locks(curr);
1560
1561         printk("\nstack backtrace:\n");
1562         dump_stack();
1563
1564         return 0;
1565 }
1566
1567 /*
1568  * Check whether we are holding such a class already.
1569  *
1570  * (Note that this has to be done separately, because the graph cannot
1571  * detect such classes of deadlocks.)
1572  *
1573  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1574  */
1575 static int
1576 check_deadlock(struct task_struct *curr, struct held_lock *next,
1577                struct lockdep_map *next_instance, int read)
1578 {
1579         struct held_lock *prev;
1580         struct held_lock *nest = NULL;
1581         int i;
1582
1583         for (i = 0; i < curr->lockdep_depth; i++) {
1584                 prev = curr->held_locks + i;
1585
1586                 if (prev->instance == next->nest_lock)
1587                         nest = prev;
1588
1589                 if (hlock_class(prev) != hlock_class(next))
1590                         continue;
1591
1592                 /*
1593                  * Allow read-after-read recursion of the same
1594                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1595                  */
1596                 if ((read == 2) && prev->read)
1597                         return 2;
1598
1599                 /*
1600                  * We're holding the nest_lock, which serializes this lock's
1601                  * nesting behaviour.
1602                  */
1603                 if (nest)
1604                         return 2;
1605
1606                 return print_deadlock_bug(curr, prev, next);
1607         }
1608         return 1;
1609 }
1610
1611 /*
1612  * There was a chain-cache miss, and we are about to add a new dependency
1613  * to a previous lock. We recursively validate the following rules:
1614  *
1615  *  - would the adding of the <prev> -> <next> dependency create a
1616  *    circular dependency in the graph? [== circular deadlock]
1617  *
1618  *  - does the new prev->next dependency connect any hardirq-safe lock
1619  *    (in the full backwards-subgraph starting at <prev>) with any
1620  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1621  *    <next>)? [== illegal lock inversion with hardirq contexts]
1622  *
1623  *  - does the new prev->next dependency connect any softirq-safe lock
1624  *    (in the full backwards-subgraph starting at <prev>) with any
1625  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1626  *    <next>)? [== illegal lock inversion with softirq contexts]
1627  *
1628  * any of these scenarios could lead to a deadlock.
1629  *
1630  * Then if all the validations pass, we add the forwards and backwards
1631  * dependency.
1632  */
1633 static int
1634 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1635                struct held_lock *next, int distance)
1636 {
1637         struct lock_list *entry;
1638         int ret;
1639         struct lock_list this;
1640         struct lock_list *uninitialized_var(target_entry);
1641
1642         /*
1643          * Prove that the new <prev> -> <next> dependency would not
1644          * create a circular dependency in the graph. (We do this by
1645          * forward-recursing into the graph starting at <next>, and
1646          * checking whether we can reach <prev>.)
1647          *
1648          * We are using global variables to control the recursion, to
1649          * keep the stackframe size of the recursive functions low:
1650          */
1651         this.class = hlock_class(next);
1652         this.parent = NULL;
1653         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1654         if (unlikely(!ret))
1655                 return print_circular_bug(&this, target_entry, next, prev);
1656         else if (unlikely(ret < 0))
1657                 return print_bfs_bug(ret);
1658
1659         if (!check_prev_add_irq(curr, prev, next))
1660                 return 0;
1661
1662         /*
1663          * For recursive read-locks we do all the dependency checks,
1664          * but we dont store read-triggered dependencies (only
1665          * write-triggered dependencies). This ensures that only the
1666          * write-side dependencies matter, and that if for example a
1667          * write-lock never takes any other locks, then the reads are
1668          * equivalent to a NOP.
1669          */
1670         if (next->read == 2 || prev->read == 2)
1671                 return 1;
1672         /*
1673          * Is the <prev> -> <next> dependency already present?
1674          *
1675          * (this may occur even though this is a new chain: consider
1676          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1677          *  chains - the second one will be new, but L1 already has
1678          *  L2 added to its dependency list, due to the first chain.)
1679          */
1680         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1681                 if (entry->class == hlock_class(next)) {
1682                         if (distance == 1)
1683                                 entry->distance = 1;
1684                         return 2;
1685                 }
1686         }
1687
1688         /*
1689          * Ok, all validations passed, add the new lock
1690          * to the previous lock's dependency list:
1691          */
1692         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1693                                &hlock_class(prev)->locks_after,
1694                                next->acquire_ip, distance);
1695
1696         if (!ret)
1697                 return 0;
1698
1699         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1700                                &hlock_class(next)->locks_before,
1701                                next->acquire_ip, distance);
1702         if (!ret)
1703                 return 0;
1704
1705         /*
1706          * Debugging printouts:
1707          */
1708         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1709                 graph_unlock();
1710                 printk("\n new dependency: ");
1711                 print_lock_name(hlock_class(prev));
1712                 printk(" => ");
1713                 print_lock_name(hlock_class(next));
1714                 printk("\n");
1715                 dump_stack();
1716                 return graph_lock();
1717         }
1718         return 1;
1719 }
1720
1721 /*
1722  * Add the dependency to all directly-previous locks that are 'relevant'.
1723  * The ones that are relevant are (in increasing distance from curr):
1724  * all consecutive trylock entries and the final non-trylock entry - or
1725  * the end of this context's lock-chain - whichever comes first.
1726  */
1727 static int
1728 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1729 {
1730         int depth = curr->lockdep_depth;
1731         struct held_lock *hlock;
1732
1733         /*
1734          * Debugging checks.
1735          *
1736          * Depth must not be zero for a non-head lock:
1737          */
1738         if (!depth)
1739                 goto out_bug;
1740         /*
1741          * At least two relevant locks must exist for this
1742          * to be a head:
1743          */
1744         if (curr->held_locks[depth].irq_context !=
1745                         curr->held_locks[depth-1].irq_context)
1746                 goto out_bug;
1747
1748         for (;;) {
1749                 int distance = curr->lockdep_depth - depth + 1;
1750                 hlock = curr->held_locks + depth-1;
1751                 /*
1752                  * Only non-recursive-read entries get new dependencies
1753                  * added:
1754                  */
1755                 if (hlock->read != 2) {
1756                         if (!check_prev_add(curr, hlock, next, distance))
1757                                 return 0;
1758                         /*
1759                          * Stop after the first non-trylock entry,
1760                          * as non-trylock entries have added their
1761                          * own direct dependencies already, so this
1762                          * lock is connected to them indirectly:
1763                          */
1764                         if (!hlock->trylock)
1765                                 break;
1766                 }
1767                 depth--;
1768                 /*
1769                  * End of lock-stack?
1770                  */
1771                 if (!depth)
1772                         break;
1773                 /*
1774                  * Stop the search if we cross into another context:
1775                  */
1776                 if (curr->held_locks[depth].irq_context !=
1777                                 curr->held_locks[depth-1].irq_context)
1778                         break;
1779         }
1780         return 1;
1781 out_bug:
1782         if (!debug_locks_off_graph_unlock())
1783                 return 0;
1784
1785         WARN_ON(1);
1786
1787         return 0;
1788 }
1789
1790 unsigned long nr_lock_chains;
1791 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1792 int nr_chain_hlocks;
1793 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1794
1795 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1796 {
1797         return lock_classes + chain_hlocks[chain->base + i];
1798 }
1799
1800 /*
1801  * Look up a dependency chain. If the key is not present yet then
1802  * add it and return 1 - in this case the new dependency chain is
1803  * validated. If the key is already hashed, return 0.
1804  * (On return with 1 graph_lock is held.)
1805  */
1806 static inline int lookup_chain_cache(struct task_struct *curr,
1807                                      struct held_lock *hlock,
1808                                      u64 chain_key)
1809 {
1810         struct lock_class *class = hlock_class(hlock);
1811         struct list_head *hash_head = chainhashentry(chain_key);
1812         struct lock_chain *chain;
1813         struct held_lock *hlock_curr, *hlock_next;
1814         int i, j, n, cn;
1815
1816         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1817                 return 0;
1818         /*
1819          * We can walk it lock-free, because entries only get added
1820          * to the hash:
1821          */
1822         list_for_each_entry(chain, hash_head, entry) {
1823                 if (chain->chain_key == chain_key) {
1824 cache_hit:
1825                         debug_atomic_inc(chain_lookup_hits);
1826                         if (very_verbose(class))
1827                                 printk("\nhash chain already cached, key: "
1828                                         "%016Lx tail class: [%p] %s\n",
1829                                         (unsigned long long)chain_key,
1830                                         class->key, class->name);
1831                         return 0;
1832                 }
1833         }
1834         if (very_verbose(class))
1835                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1836                         (unsigned long long)chain_key, class->key, class->name);
1837         /*
1838          * Allocate a new chain entry from the static array, and add
1839          * it to the hash:
1840          */
1841         if (!graph_lock())
1842                 return 0;
1843         /*
1844          * We have to walk the chain again locked - to avoid duplicates:
1845          */
1846         list_for_each_entry(chain, hash_head, entry) {
1847                 if (chain->chain_key == chain_key) {
1848                         graph_unlock();
1849                         goto cache_hit;
1850                 }
1851         }
1852         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1853                 if (!debug_locks_off_graph_unlock())
1854                         return 0;
1855
1856                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1857                 printk("turning off the locking correctness validator.\n");
1858                 dump_stack();
1859                 return 0;
1860         }
1861         chain = lock_chains + nr_lock_chains++;
1862         chain->chain_key = chain_key;
1863         chain->irq_context = hlock->irq_context;
1864         /* Find the first held_lock of current chain */
1865         hlock_next = hlock;
1866         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1867                 hlock_curr = curr->held_locks + i;
1868                 if (hlock_curr->irq_context != hlock_next->irq_context)
1869                         break;
1870                 hlock_next = hlock;
1871         }
1872         i++;
1873         chain->depth = curr->lockdep_depth + 1 - i;
1874         cn = nr_chain_hlocks;
1875         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1876                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1877                 if (n == cn)
1878                         break;
1879                 cn = n;
1880         }
1881         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1882                 chain->base = cn;
1883                 for (j = 0; j < chain->depth - 1; j++, i++) {
1884                         int lock_id = curr->held_locks[i].class_idx - 1;
1885                         chain_hlocks[chain->base + j] = lock_id;
1886                 }
1887                 chain_hlocks[chain->base + j] = class - lock_classes;
1888         }
1889         list_add_tail_rcu(&chain->entry, hash_head);
1890         debug_atomic_inc(chain_lookup_misses);
1891         inc_chains();
1892
1893         return 1;
1894 }
1895
1896 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1897                 struct held_lock *hlock, int chain_head, u64 chain_key)
1898 {
1899         /*
1900          * Trylock needs to maintain the stack of held locks, but it
1901          * does not add new dependencies, because trylock can be done
1902          * in any order.
1903          *
1904          * We look up the chain_key and do the O(N^2) check and update of
1905          * the dependencies only if this is a new dependency chain.
1906          * (If lookup_chain_cache() returns with 1 it acquires
1907          * graph_lock for us)
1908          */
1909         if (!hlock->trylock && (hlock->check == 2) &&
1910             lookup_chain_cache(curr, hlock, chain_key)) {
1911                 /*
1912                  * Check whether last held lock:
1913                  *
1914                  * - is irq-safe, if this lock is irq-unsafe
1915                  * - is softirq-safe, if this lock is hardirq-unsafe
1916                  *
1917                  * And check whether the new lock's dependency graph
1918                  * could lead back to the previous lock.
1919                  *
1920                  * any of these scenarios could lead to a deadlock. If
1921                  * All validations
1922                  */
1923                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1924
1925                 if (!ret)
1926                         return 0;
1927                 /*
1928                  * Mark recursive read, as we jump over it when
1929                  * building dependencies (just like we jump over
1930                  * trylock entries):
1931                  */
1932                 if (ret == 2)
1933                         hlock->read = 2;
1934                 /*
1935                  * Add dependency only if this lock is not the head
1936                  * of the chain, and if it's not a secondary read-lock:
1937                  */
1938                 if (!chain_head && ret != 2)
1939                         if (!check_prevs_add(curr, hlock))
1940                                 return 0;
1941                 graph_unlock();
1942         } else
1943                 /* after lookup_chain_cache(): */
1944                 if (unlikely(!debug_locks))
1945                         return 0;
1946
1947         return 1;
1948 }
1949 #else
1950 static inline int validate_chain(struct task_struct *curr,
1951                 struct lockdep_map *lock, struct held_lock *hlock,
1952                 int chain_head, u64 chain_key)
1953 {
1954         return 1;
1955 }
1956 #endif
1957
1958 /*
1959  * We are building curr_chain_key incrementally, so double-check
1960  * it from scratch, to make sure that it's done correctly:
1961  */
1962 static void check_chain_key(struct task_struct *curr)
1963 {
1964 #ifdef CONFIG_DEBUG_LOCKDEP
1965         struct held_lock *hlock, *prev_hlock = NULL;
1966         unsigned int i, id;
1967         u64 chain_key = 0;
1968
1969         for (i = 0; i < curr->lockdep_depth; i++) {
1970                 hlock = curr->held_locks + i;
1971                 if (chain_key != hlock->prev_chain_key) {
1972                         debug_locks_off();
1973                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1974                                 curr->lockdep_depth, i,
1975                                 (unsigned long long)chain_key,
1976                                 (unsigned long long)hlock->prev_chain_key);
1977                         return;
1978                 }
1979                 id = hlock->class_idx - 1;
1980                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1981                         return;
1982
1983                 if (prev_hlock && (prev_hlock->irq_context !=
1984                                                         hlock->irq_context))
1985                         chain_key = 0;
1986                 chain_key = iterate_chain_key(chain_key, id);
1987                 prev_hlock = hlock;
1988         }
1989         if (chain_key != curr->curr_chain_key) {
1990                 debug_locks_off();
1991                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1992                         curr->lockdep_depth, i,
1993                         (unsigned long long)chain_key,
1994                         (unsigned long long)curr->curr_chain_key);
1995         }
1996 #endif
1997 }
1998
1999 static int
2000 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2001                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2002 {
2003         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2004                 return 0;
2005
2006         printk("\n=================================\n");
2007         printk(  "[ INFO: inconsistent lock state ]\n");
2008         print_kernel_version();
2009         printk(  "---------------------------------\n");
2010
2011         printk("inconsistent {%s} -> {%s} usage.\n",
2012                 usage_str[prev_bit], usage_str[new_bit]);
2013
2014         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2015                 curr->comm, task_pid_nr(curr),
2016                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2017                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2018                 trace_hardirqs_enabled(curr),
2019                 trace_softirqs_enabled(curr));
2020         print_lock(this);
2021
2022         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2023         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2024
2025         print_irqtrace_events(curr);
2026         printk("\nother info that might help us debug this:\n");
2027         lockdep_print_held_locks(curr);
2028
2029         printk("\nstack backtrace:\n");
2030         dump_stack();
2031
2032         return 0;
2033 }
2034
2035 /*
2036  * Print out an error if an invalid bit is set:
2037  */
2038 static inline int
2039 valid_state(struct task_struct *curr, struct held_lock *this,
2040             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2041 {
2042         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2043                 return print_usage_bug(curr, this, bad_bit, new_bit);
2044         return 1;
2045 }
2046
2047 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2048                      enum lock_usage_bit new_bit);
2049
2050 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2051
2052 /*
2053  * print irq inversion bug:
2054  */
2055 static int
2056 print_irq_inversion_bug(struct task_struct *curr,
2057                         struct lock_list *root, struct lock_list *other,
2058                         struct held_lock *this, int forwards,
2059                         const char *irqclass)
2060 {
2061         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2062                 return 0;
2063
2064         printk("\n=========================================================\n");
2065         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2066         print_kernel_version();
2067         printk(  "---------------------------------------------------------\n");
2068         printk("%s/%d just changed the state of lock:\n",
2069                 curr->comm, task_pid_nr(curr));
2070         print_lock(this);
2071         if (forwards)
2072                 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2073         else
2074                 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2075         print_lock_name(other->class);
2076         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2077
2078         printk("\nother info that might help us debug this:\n");
2079         lockdep_print_held_locks(curr);
2080
2081         printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2082         if (!save_trace(&root->trace))
2083                 return 0;
2084         print_shortest_lock_dependencies(other, root);
2085
2086         printk("\nstack backtrace:\n");
2087         dump_stack();
2088
2089         return 0;
2090 }
2091
2092 /*
2093  * Prove that in the forwards-direction subgraph starting at <this>
2094  * there is no lock matching <mask>:
2095  */
2096 static int
2097 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2098                      enum lock_usage_bit bit, const char *irqclass)
2099 {
2100         int ret;
2101         struct lock_list root;
2102         struct lock_list *uninitialized_var(target_entry);
2103
2104         root.parent = NULL;
2105         root.class = hlock_class(this);
2106         ret = find_usage_forwards(&root, bit, &target_entry);
2107         if (ret < 0)
2108                 return print_bfs_bug(ret);
2109         if (ret == 1)
2110                 return ret;
2111
2112         return print_irq_inversion_bug(curr, &root, target_entry,
2113                                         this, 1, irqclass);
2114 }
2115
2116 /*
2117  * Prove that in the backwards-direction subgraph starting at <this>
2118  * there is no lock matching <mask>:
2119  */
2120 static int
2121 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2122                       enum lock_usage_bit bit, const char *irqclass)
2123 {
2124         int ret;
2125         struct lock_list root;
2126         struct lock_list *uninitialized_var(target_entry);
2127
2128         root.parent = NULL;
2129         root.class = hlock_class(this);
2130         ret = find_usage_backwards(&root, bit, &target_entry);
2131         if (ret < 0)
2132                 return print_bfs_bug(ret);
2133         if (ret == 1)
2134                 return ret;
2135
2136         return print_irq_inversion_bug(curr, &root, target_entry,
2137                                         this, 0, irqclass);
2138 }
2139
2140 void print_irqtrace_events(struct task_struct *curr)
2141 {
2142         printk("irq event stamp: %u\n", curr->irq_events);
2143         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2144         print_ip_sym(curr->hardirq_enable_ip);
2145         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2146         print_ip_sym(curr->hardirq_disable_ip);
2147         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2148         print_ip_sym(curr->softirq_enable_ip);
2149         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2150         print_ip_sym(curr->softirq_disable_ip);
2151 }
2152
2153 static int HARDIRQ_verbose(struct lock_class *class)
2154 {
2155 #if HARDIRQ_VERBOSE
2156         return class_filter(class);
2157 #endif
2158         return 0;
2159 }
2160
2161 static int SOFTIRQ_verbose(struct lock_class *class)
2162 {
2163 #if SOFTIRQ_VERBOSE
2164         return class_filter(class);
2165 #endif
2166         return 0;
2167 }
2168
2169 static int RECLAIM_FS_verbose(struct lock_class *class)
2170 {
2171 #if RECLAIM_VERBOSE
2172         return class_filter(class);
2173 #endif
2174         return 0;
2175 }
2176
2177 #define STRICT_READ_CHECKS      1
2178
2179 static int (*state_verbose_f[])(struct lock_class *class) = {
2180 #define LOCKDEP_STATE(__STATE) \
2181         __STATE##_verbose,
2182 #include "lockdep_states.h"
2183 #undef LOCKDEP_STATE
2184 };
2185
2186 static inline int state_verbose(enum lock_usage_bit bit,
2187                                 struct lock_class *class)
2188 {
2189         return state_verbose_f[bit >> 2](class);
2190 }
2191
2192 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2193                              enum lock_usage_bit bit, const char *name);
2194
2195 static int
2196 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2197                 enum lock_usage_bit new_bit)
2198 {
2199         int excl_bit = exclusive_bit(new_bit);
2200         int read = new_bit & 1;
2201         int dir = new_bit & 2;
2202
2203         /*
2204          * mark USED_IN has to look forwards -- to ensure no dependency
2205          * has ENABLED state, which would allow recursion deadlocks.
2206          *
2207          * mark ENABLED has to look backwards -- to ensure no dependee
2208          * has USED_IN state, which, again, would allow  recursion deadlocks.
2209          */
2210         check_usage_f usage = dir ?
2211                 check_usage_backwards : check_usage_forwards;
2212
2213         /*
2214          * Validate that this particular lock does not have conflicting
2215          * usage states.
2216          */
2217         if (!valid_state(curr, this, new_bit, excl_bit))
2218                 return 0;
2219
2220         /*
2221          * Validate that the lock dependencies don't have conflicting usage
2222          * states.
2223          */
2224         if ((!read || !dir || STRICT_READ_CHECKS) &&
2225                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2226                 return 0;
2227
2228         /*
2229          * Check for read in write conflicts
2230          */
2231         if (!read) {
2232                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2233                         return 0;
2234
2235                 if (STRICT_READ_CHECKS &&
2236                         !usage(curr, this, excl_bit + 1,
2237                                 state_name(new_bit + 1)))
2238                         return 0;
2239         }
2240
2241         if (state_verbose(new_bit, hlock_class(this)))
2242                 return 2;
2243
2244         return 1;
2245 }
2246
2247 enum mark_type {
2248 #define LOCKDEP_STATE(__STATE)  __STATE,
2249 #include "lockdep_states.h"
2250 #undef LOCKDEP_STATE
2251 };
2252
2253 /*
2254  * Mark all held locks with a usage bit:
2255  */
2256 static int
2257 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2258 {
2259         enum lock_usage_bit usage_bit;
2260         struct held_lock *hlock;
2261         int i;
2262
2263         for (i = 0; i < curr->lockdep_depth; i++) {
2264                 hlock = curr->held_locks + i;
2265
2266                 usage_bit = 2 + (mark << 2); /* ENABLED */
2267                 if (hlock->read)
2268                         usage_bit += 1; /* READ */
2269
2270                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2271
2272                 if (!mark_lock(curr, hlock, usage_bit))
2273                         return 0;
2274         }
2275
2276         return 1;
2277 }
2278
2279 /*
2280  * Debugging helper: via this flag we know that we are in
2281  * 'early bootup code', and will warn about any invalid irqs-on event:
2282  */
2283 static int early_boot_irqs_enabled;
2284
2285 void early_boot_irqs_off(void)
2286 {
2287         early_boot_irqs_enabled = 0;
2288 }
2289
2290 void early_boot_irqs_on(void)
2291 {
2292         early_boot_irqs_enabled = 1;
2293 }
2294
2295 /*
2296  * Hardirqs will be enabled:
2297  */
2298 void trace_hardirqs_on_caller(unsigned long ip)
2299 {
2300         struct task_struct *curr = current;
2301
2302         time_hardirqs_on(CALLER_ADDR0, ip);
2303
2304         if (unlikely(!debug_locks || current->lockdep_recursion))
2305                 return;
2306
2307         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2308                 return;
2309
2310         if (unlikely(curr->hardirqs_enabled)) {
2311                 debug_atomic_inc(redundant_hardirqs_on);
2312                 return;
2313         }
2314         /* we'll do an OFF -> ON transition: */
2315         curr->hardirqs_enabled = 1;
2316
2317         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2318                 return;
2319         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2320                 return;
2321         /*
2322          * We are going to turn hardirqs on, so set the
2323          * usage bit for all held locks:
2324          */
2325         if (!mark_held_locks(curr, HARDIRQ))
2326                 return;
2327         /*
2328          * If we have softirqs enabled, then set the usage
2329          * bit for all held locks. (disabled hardirqs prevented
2330          * this bit from being set before)
2331          */
2332         if (curr->softirqs_enabled)
2333                 if (!mark_held_locks(curr, SOFTIRQ))
2334                         return;
2335
2336         curr->hardirq_enable_ip = ip;
2337         curr->hardirq_enable_event = ++curr->irq_events;
2338         debug_atomic_inc(hardirqs_on_events);
2339 }
2340 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2341
2342 void trace_hardirqs_on(void)
2343 {
2344         trace_hardirqs_on_caller(CALLER_ADDR0);
2345 }
2346 EXPORT_SYMBOL(trace_hardirqs_on);
2347
2348 /*
2349  * Hardirqs were disabled:
2350  */
2351 void trace_hardirqs_off_caller(unsigned long ip)
2352 {
2353         struct task_struct *curr = current;
2354
2355         time_hardirqs_off(CALLER_ADDR0, ip);
2356
2357         if (unlikely(!debug_locks || current->lockdep_recursion))
2358                 return;
2359
2360         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2361                 return;
2362
2363         if (curr->hardirqs_enabled) {
2364                 /*
2365                  * We have done an ON -> OFF transition:
2366                  */
2367                 curr->hardirqs_enabled = 0;
2368                 curr->hardirq_disable_ip = ip;
2369                 curr->hardirq_disable_event = ++curr->irq_events;
2370                 debug_atomic_inc(hardirqs_off_events);
2371         } else
2372                 debug_atomic_inc(redundant_hardirqs_off);
2373 }
2374 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2375
2376 void trace_hardirqs_off(void)
2377 {
2378         trace_hardirqs_off_caller(CALLER_ADDR0);
2379 }
2380 EXPORT_SYMBOL(trace_hardirqs_off);
2381
2382 /*
2383  * Softirqs will be enabled:
2384  */
2385 void trace_softirqs_on(unsigned long ip)
2386 {
2387         struct task_struct *curr = current;
2388
2389         if (unlikely(!debug_locks))
2390                 return;
2391
2392         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2393                 return;
2394
2395         if (curr->softirqs_enabled) {
2396                 debug_atomic_inc(redundant_softirqs_on);
2397                 return;
2398         }
2399
2400         /*
2401          * We'll do an OFF -> ON transition:
2402          */
2403         curr->softirqs_enabled = 1;
2404         curr->softirq_enable_ip = ip;
2405         curr->softirq_enable_event = ++curr->irq_events;
2406         debug_atomic_inc(softirqs_on_events);
2407         /*
2408          * We are going to turn softirqs on, so set the
2409          * usage bit for all held locks, if hardirqs are
2410          * enabled too:
2411          */
2412         if (curr->hardirqs_enabled)
2413                 mark_held_locks(curr, SOFTIRQ);
2414 }
2415
2416 /*
2417  * Softirqs were disabled:
2418  */
2419 void trace_softirqs_off(unsigned long ip)
2420 {
2421         struct task_struct *curr = current;
2422
2423         if (unlikely(!debug_locks))
2424                 return;
2425
2426         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2427                 return;
2428
2429         if (curr->softirqs_enabled) {
2430                 /*
2431                  * We have done an ON -> OFF transition:
2432                  */
2433                 curr->softirqs_enabled = 0;
2434                 curr->softirq_disable_ip = ip;
2435                 curr->softirq_disable_event = ++curr->irq_events;
2436                 debug_atomic_inc(softirqs_off_events);
2437                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2438         } else
2439                 debug_atomic_inc(redundant_softirqs_off);
2440 }
2441
2442 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2443 {
2444         struct task_struct *curr = current;
2445
2446         if (unlikely(!debug_locks))
2447                 return;
2448
2449         /* no reclaim without waiting on it */
2450         if (!(gfp_mask & __GFP_WAIT))
2451                 return;
2452
2453         /* this guy won't enter reclaim */
2454         if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2455                 return;
2456
2457         /* We're only interested __GFP_FS allocations for now */
2458         if (!(gfp_mask & __GFP_FS))
2459                 return;
2460
2461         if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2462                 return;
2463
2464         mark_held_locks(curr, RECLAIM_FS);
2465 }
2466
2467 static void check_flags(unsigned long flags);
2468
2469 void lockdep_trace_alloc(gfp_t gfp_mask)
2470 {
2471         unsigned long flags;
2472
2473         if (unlikely(current->lockdep_recursion))
2474                 return;
2475
2476         raw_local_irq_save(flags);
2477         check_flags(flags);
2478         current->lockdep_recursion = 1;
2479         __lockdep_trace_alloc(gfp_mask, flags);
2480         current->lockdep_recursion = 0;
2481         raw_local_irq_restore(flags);
2482 }
2483
2484 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2485 {
2486         /*
2487          * If non-trylock use in a hardirq or softirq context, then
2488          * mark the lock as used in these contexts:
2489          */
2490         if (!hlock->trylock) {
2491                 if (hlock->read) {
2492                         if (curr->hardirq_context)
2493                                 if (!mark_lock(curr, hlock,
2494                                                 LOCK_USED_IN_HARDIRQ_READ))
2495                                         return 0;
2496                         if (curr->softirq_context)
2497                                 if (!mark_lock(curr, hlock,
2498                                                 LOCK_USED_IN_SOFTIRQ_READ))
2499                                         return 0;
2500                 } else {
2501                         if (curr->hardirq_context)
2502                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2503                                         return 0;
2504                         if (curr->softirq_context)
2505                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2506                                         return 0;
2507                 }
2508         }
2509         if (!hlock->hardirqs_off) {
2510                 if (hlock->read) {
2511                         if (!mark_lock(curr, hlock,
2512                                         LOCK_ENABLED_HARDIRQ_READ))
2513                                 return 0;
2514                         if (curr->softirqs_enabled)
2515                                 if (!mark_lock(curr, hlock,
2516                                                 LOCK_ENABLED_SOFTIRQ_READ))
2517                                         return 0;
2518                 } else {
2519                         if (!mark_lock(curr, hlock,
2520                                         LOCK_ENABLED_HARDIRQ))
2521                                 return 0;
2522                         if (curr->softirqs_enabled)
2523                                 if (!mark_lock(curr, hlock,
2524                                                 LOCK_ENABLED_SOFTIRQ))
2525                                         return 0;
2526                 }
2527         }
2528
2529         /*
2530          * We reuse the irq context infrastructure more broadly as a general
2531          * context checking code. This tests GFP_FS recursion (a lock taken
2532          * during reclaim for a GFP_FS allocation is held over a GFP_FS
2533          * allocation).
2534          */
2535         if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2536                 if (hlock->read) {
2537                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2538                                         return 0;
2539                 } else {
2540                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2541                                         return 0;
2542                 }
2543         }
2544
2545         return 1;
2546 }
2547
2548 static int separate_irq_context(struct task_struct *curr,
2549                 struct held_lock *hlock)
2550 {
2551         unsigned int depth = curr->lockdep_depth;
2552
2553         /*
2554          * Keep track of points where we cross into an interrupt context:
2555          */
2556         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2557                                 curr->softirq_context;
2558         if (depth) {
2559                 struct held_lock *prev_hlock;
2560
2561                 prev_hlock = curr->held_locks + depth-1;
2562                 /*
2563                  * If we cross into another context, reset the
2564                  * hash key (this also prevents the checking and the
2565                  * adding of the dependency to 'prev'):
2566                  */
2567                 if (prev_hlock->irq_context != hlock->irq_context)
2568                         return 1;
2569         }
2570         return 0;
2571 }
2572
2573 #else
2574
2575 static inline
2576 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2577                 enum lock_usage_bit new_bit)
2578 {
2579         WARN_ON(1);
2580         return 1;
2581 }
2582
2583 static inline int mark_irqflags(struct task_struct *curr,
2584                 struct held_lock *hlock)
2585 {
2586         return 1;
2587 }
2588
2589 static inline int separate_irq_context(struct task_struct *curr,
2590                 struct held_lock *hlock)
2591 {
2592         return 0;
2593 }
2594
2595 void lockdep_trace_alloc(gfp_t gfp_mask)
2596 {
2597 }
2598
2599 #endif
2600
2601 /*
2602  * Mark a lock with a usage bit, and validate the state transition:
2603  */
2604 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2605                              enum lock_usage_bit new_bit)
2606 {
2607         unsigned int new_mask = 1 << new_bit, ret = 1;
2608
2609         /*
2610          * If already set then do not dirty the cacheline,
2611          * nor do any checks:
2612          */
2613         if (likely(hlock_class(this)->usage_mask & new_mask))
2614                 return 1;
2615
2616         if (!graph_lock())
2617                 return 0;
2618         /*
2619          * Make sure we didnt race:
2620          */
2621         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2622                 graph_unlock();
2623                 return 1;
2624         }
2625
2626         hlock_class(this)->usage_mask |= new_mask;
2627
2628         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2629                 return 0;
2630
2631         switch (new_bit) {
2632 #define LOCKDEP_STATE(__STATE)                  \
2633         case LOCK_USED_IN_##__STATE:            \
2634         case LOCK_USED_IN_##__STATE##_READ:     \
2635         case LOCK_ENABLED_##__STATE:            \
2636         case LOCK_ENABLED_##__STATE##_READ:
2637 #include "lockdep_states.h"
2638 #undef LOCKDEP_STATE
2639                 ret = mark_lock_irq(curr, this, new_bit);
2640                 if (!ret)
2641                         return 0;
2642                 break;
2643         case LOCK_USED:
2644                 debug_atomic_dec(nr_unused_locks);
2645                 break;
2646         default:
2647                 if (!debug_locks_off_graph_unlock())
2648                         return 0;
2649                 WARN_ON(1);
2650                 return 0;
2651         }
2652
2653         graph_unlock();
2654
2655         /*
2656          * We must printk outside of the graph_lock:
2657          */
2658         if (ret == 2) {
2659                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2660                 print_lock(this);
2661                 print_irqtrace_events(curr);
2662                 dump_stack();
2663         }
2664
2665         return ret;
2666 }
2667
2668 /*
2669  * Initialize a lock instance's lock-class mapping info:
2670  */
2671 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2672                       struct lock_class_key *key, int subclass)
2673 {
2674         lock->class_cache = NULL;
2675 #ifdef CONFIG_LOCK_STAT
2676         lock->cpu = raw_smp_processor_id();
2677 #endif
2678
2679         if (DEBUG_LOCKS_WARN_ON(!name)) {
2680                 lock->name = "NULL";
2681                 return;
2682         }
2683
2684         lock->name = name;
2685
2686         if (DEBUG_LOCKS_WARN_ON(!key))
2687                 return;
2688         /*
2689          * Sanity check, the lock-class key must be persistent:
2690          */
2691         if (!static_obj(key)) {
2692                 printk("BUG: key %p not in .data!\n", key);
2693                 DEBUG_LOCKS_WARN_ON(1);
2694                 return;
2695         }
2696         lock->key = key;
2697
2698         if (unlikely(!debug_locks))
2699                 return;
2700
2701         if (subclass)
2702                 register_lock_class(lock, subclass, 1);
2703 }
2704 EXPORT_SYMBOL_GPL(lockdep_init_map);
2705
2706 /*
2707  * This gets called for every mutex_lock*()/spin_lock*() operation.
2708  * We maintain the dependency maps and validate the locking attempt:
2709  */
2710 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2711                           int trylock, int read, int check, int hardirqs_off,
2712                           struct lockdep_map *nest_lock, unsigned long ip,
2713                           int references)
2714 {
2715         struct task_struct *curr = current;
2716         struct lock_class *class = NULL;
2717         struct held_lock *hlock;
2718         unsigned int depth, id;
2719         int chain_head = 0;
2720         int class_idx;
2721         u64 chain_key;
2722
2723         if (!prove_locking)
2724                 check = 1;
2725
2726         if (unlikely(!debug_locks))
2727                 return 0;
2728
2729         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2730                 return 0;
2731
2732         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2733                 debug_locks_off();
2734                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2735                 printk("turning off the locking correctness validator.\n");
2736                 dump_stack();
2737                 return 0;
2738         }
2739
2740         if (!subclass)
2741                 class = lock->class_cache;
2742         /*
2743          * Not cached yet or subclass?
2744          */
2745         if (unlikely(!class)) {
2746                 class = register_lock_class(lock, subclass, 0);
2747                 if (!class)
2748                         return 0;
2749         }
2750         atomic_inc((atomic_t *)&class->ops);
2751         if (very_verbose(class)) {
2752                 printk("\nacquire class [%p] %s", class->key, class->name);
2753                 if (class->name_version > 1)
2754                         printk("#%d", class->name_version);
2755                 printk("\n");
2756                 dump_stack();
2757         }
2758
2759         /*
2760          * Add the lock to the list of currently held locks.
2761          * (we dont increase the depth just yet, up until the
2762          * dependency checks are done)
2763          */
2764         depth = curr->lockdep_depth;
2765         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2766                 return 0;
2767
2768         class_idx = class - lock_classes + 1;
2769
2770         if (depth) {
2771                 hlock = curr->held_locks + depth - 1;
2772                 if (hlock->class_idx == class_idx && nest_lock) {
2773                         if (hlock->references)
2774                                 hlock->references++;
2775                         else
2776                                 hlock->references = 2;
2777
2778                         return 1;
2779                 }
2780         }
2781
2782         hlock = curr->held_locks + depth;
2783         if (DEBUG_LOCKS_WARN_ON(!class))
2784                 return 0;
2785         hlock->class_idx = class_idx;
2786         hlock->acquire_ip = ip;
2787         hlock->instance = lock;
2788         hlock->nest_lock = nest_lock;
2789         hlock->trylock = trylock;
2790         hlock->read = read;
2791         hlock->check = check;
2792         hlock->hardirqs_off = !!hardirqs_off;
2793         hlock->references = references;
2794 #ifdef CONFIG_LOCK_STAT
2795         hlock->waittime_stamp = 0;
2796         hlock->holdtime_stamp = lockstat_clock();
2797 #endif
2798
2799         if (check == 2 && !mark_irqflags(curr, hlock))
2800                 return 0;
2801
2802         /* mark it as used: */
2803         if (!mark_lock(curr, hlock, LOCK_USED))
2804                 return 0;
2805
2806         /*
2807          * Calculate the chain hash: it's the combined hash of all the
2808          * lock keys along the dependency chain. We save the hash value
2809          * at every step so that we can get the current hash easily
2810          * after unlock. The chain hash is then used to cache dependency
2811          * results.
2812          *
2813          * The 'key ID' is what is the most compact key value to drive
2814          * the hash, not class->key.
2815          */
2816         id = class - lock_classes;
2817         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2818                 return 0;
2819
2820         chain_key = curr->curr_chain_key;
2821         if (!depth) {
2822                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2823                         return 0;
2824                 chain_head = 1;
2825         }
2826
2827         hlock->prev_chain_key = chain_key;
2828         if (separate_irq_context(curr, hlock)) {
2829                 chain_key = 0;
2830                 chain_head = 1;
2831         }
2832         chain_key = iterate_chain_key(chain_key, id);
2833
2834         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2835                 return 0;
2836
2837         curr->curr_chain_key = chain_key;
2838         curr->lockdep_depth++;
2839         check_chain_key(curr);
2840 #ifdef CONFIG_DEBUG_LOCKDEP
2841         if (unlikely(!debug_locks))
2842                 return 0;
2843 #endif
2844         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2845                 debug_locks_off();
2846                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2847                 printk("turning off the locking correctness validator.\n");
2848                 dump_stack();
2849                 return 0;
2850         }
2851
2852         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2853                 max_lockdep_depth = curr->lockdep_depth;
2854
2855         return 1;
2856 }
2857
2858 static int
2859 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2860                            unsigned long ip)
2861 {
2862         if (!debug_locks_off())
2863                 return 0;
2864         if (debug_locks_silent)
2865                 return 0;
2866
2867         printk("\n=====================================\n");
2868         printk(  "[ BUG: bad unlock balance detected! ]\n");
2869         printk(  "-------------------------------------\n");
2870         printk("%s/%d is trying to release lock (",
2871                 curr->comm, task_pid_nr(curr));
2872         print_lockdep_cache(lock);
2873         printk(") at:\n");
2874         print_ip_sym(ip);
2875         printk("but there are no more locks to release!\n");
2876         printk("\nother info that might help us debug this:\n");
2877         lockdep_print_held_locks(curr);
2878
2879         printk("\nstack backtrace:\n");
2880         dump_stack();
2881
2882         return 0;
2883 }
2884
2885 /*
2886  * Common debugging checks for both nested and non-nested unlock:
2887  */
2888 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2889                         unsigned long ip)
2890 {
2891         if (unlikely(!debug_locks))
2892                 return 0;
2893         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2894                 return 0;
2895
2896         if (curr->lockdep_depth <= 0)
2897                 return print_unlock_inbalance_bug(curr, lock, ip);
2898
2899         return 1;
2900 }
2901
2902 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
2903 {
2904         if (hlock->instance == lock)
2905                 return 1;
2906
2907         if (hlock->references) {
2908                 struct lock_class *class = lock->class_cache;
2909
2910                 if (!class)
2911                         class = look_up_lock_class(lock, 0);
2912
2913                 if (DEBUG_LOCKS_WARN_ON(!class))
2914                         return 0;
2915
2916                 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
2917                         return 0;
2918
2919                 if (hlock->class_idx == class - lock_classes + 1)
2920                         return 1;
2921         }
2922
2923         return 0;
2924 }
2925
2926 static int
2927 __lock_set_class(struct lockdep_map *lock, const char *name,
2928                  struct lock_class_key *key, unsigned int subclass,
2929                  unsigned long ip)
2930 {
2931         struct task_struct *curr = current;
2932         struct held_lock *hlock, *prev_hlock;
2933         struct lock_class *class;
2934         unsigned int depth;
2935         int i;
2936
2937         depth = curr->lockdep_depth;
2938         if (DEBUG_LOCKS_WARN_ON(!depth))
2939                 return 0;
2940
2941         prev_hlock = NULL;
2942         for (i = depth-1; i >= 0; i--) {
2943                 hlock = curr->held_locks + i;
2944                 /*
2945                  * We must not cross into another context:
2946                  */
2947                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2948                         break;
2949                 if (match_held_lock(hlock, lock))
2950                         goto found_it;
2951                 prev_hlock = hlock;
2952         }
2953         return print_unlock_inbalance_bug(curr, lock, ip);
2954
2955 found_it:
2956         lockdep_init_map(lock, name, key, 0);
2957         class = register_lock_class(lock, subclass, 0);
2958         hlock->class_idx = class - lock_classes + 1;
2959
2960         curr->lockdep_depth = i;
2961         curr->curr_chain_key = hlock->prev_chain_key;
2962
2963         for (; i < depth; i++) {
2964                 hlock = curr->held_locks + i;
2965                 if (!__lock_acquire(hlock->instance,
2966                         hlock_class(hlock)->subclass, hlock->trylock,
2967                                 hlock->read, hlock->check, hlock->hardirqs_off,
2968                                 hlock->nest_lock, hlock->acquire_ip,
2969                                 hlock->references))
2970                         return 0;
2971         }
2972
2973         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2974                 return 0;
2975         return 1;
2976 }
2977
2978 /*
2979  * Remove the lock to the list of currently held locks in a
2980  * potentially non-nested (out of order) manner. This is a
2981  * relatively rare operation, as all the unlock APIs default
2982  * to nested mode (which uses lock_release()):
2983  */
2984 static int
2985 lock_release_non_nested(struct task_struct *curr,
2986                         struct lockdep_map *lock, unsigned long ip)
2987 {
2988         struct held_lock *hlock, *prev_hlock;
2989         unsigned int depth;
2990         int i;
2991
2992         /*
2993          * Check whether the lock exists in the current stack
2994          * of held locks:
2995          */
2996         depth = curr->lockdep_depth;
2997         if (DEBUG_LOCKS_WARN_ON(!depth))
2998                 return 0;
2999
3000         prev_hlock = NULL;
3001         for (i = depth-1; i >= 0; i--) {
3002                 hlock = curr->held_locks + i;
3003                 /*
3004                  * We must not cross into another context:
3005                  */
3006                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3007                         break;
3008                 if (match_held_lock(hlock, lock))
3009                         goto found_it;
3010                 prev_hlock = hlock;
3011         }
3012         return print_unlock_inbalance_bug(curr, lock, ip);
3013
3014 found_it:
3015         if (hlock->instance == lock)
3016                 lock_release_holdtime(hlock);
3017
3018         if (hlock->references) {
3019                 hlock->references--;
3020                 if (hlock->references) {
3021                         /*
3022                          * We had, and after removing one, still have
3023                          * references, the current lock stack is still
3024                          * valid. We're done!
3025                          */
3026                         return 1;
3027                 }
3028         }
3029
3030         /*
3031          * We have the right lock to unlock, 'hlock' points to it.
3032          * Now we remove it from the stack, and add back the other
3033          * entries (if any), recalculating the hash along the way:
3034          */
3035
3036         curr->lockdep_depth = i;
3037         curr->curr_chain_key = hlock->prev_chain_key;
3038
3039         for (i++; i < depth; i++) {
3040                 hlock = curr->held_locks + i;
3041                 if (!__lock_acquire(hlock->instance,
3042                         hlock_class(hlock)->subclass, hlock->trylock,
3043                                 hlock->read, hlock->check, hlock->hardirqs_off,
3044                                 hlock->nest_lock, hlock->acquire_ip,
3045                                 hlock->references))
3046                         return 0;
3047         }
3048
3049         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3050                 return 0;
3051         return 1;
3052 }
3053
3054 /*
3055  * Remove the lock to the list of currently held locks - this gets
3056  * called on mutex_unlock()/spin_unlock*() (or on a failed
3057  * mutex_lock_interruptible()). This is done for unlocks that nest
3058  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3059  */
3060 static int lock_release_nested(struct task_struct *curr,
3061                                struct lockdep_map *lock, unsigned long ip)
3062 {
3063         struct held_lock *hlock;
3064         unsigned int depth;
3065
3066         /*
3067          * Pop off the top of the lock stack:
3068          */
3069         depth = curr->lockdep_depth - 1;
3070         hlock = curr->held_locks + depth;
3071
3072         /*
3073          * Is the unlock non-nested:
3074          */
3075         if (hlock->instance != lock || hlock->references)
3076                 return lock_release_non_nested(curr, lock, ip);
3077         curr->lockdep_depth--;
3078
3079         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3080                 return 0;
3081
3082         curr->curr_chain_key = hlock->prev_chain_key;
3083
3084         lock_release_holdtime(hlock);
3085
3086 #ifdef CONFIG_DEBUG_LOCKDEP
3087         hlock->prev_chain_key = 0;
3088         hlock->class_idx = 0;
3089         hlock->acquire_ip = 0;
3090         hlock->irq_context = 0;
3091 #endif
3092         return 1;
3093 }
3094
3095 /*
3096  * Remove the lock to the list of currently held locks - this gets
3097  * called on mutex_unlock()/spin_unlock*() (or on a failed
3098  * mutex_lock_interruptible()). This is done for unlocks that nest
3099  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3100  */
3101 static void
3102 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3103 {
3104         struct task_struct *curr = current;
3105
3106         if (!check_unlock(curr, lock, ip))
3107                 return;
3108
3109         if (nested) {
3110                 if (!lock_release_nested(curr, lock, ip))
3111                         return;
3112         } else {
3113                 if (!lock_release_non_nested(curr, lock, ip))
3114                         return;
3115         }
3116
3117         check_chain_key(curr);
3118 }
3119
3120 static int __lock_is_held(struct lockdep_map *lock)
3121 {
3122         struct task_struct *curr = current;
3123         int i;
3124
3125         for (i = 0; i < curr->lockdep_depth; i++) {
3126                 struct held_lock *hlock = curr->held_locks + i;
3127
3128                 if (match_held_lock(hlock, lock))
3129                         return 1;
3130         }
3131
3132         return 0;
3133 }
3134
3135 /*
3136  * Check whether we follow the irq-flags state precisely:
3137  */
3138 static void check_flags(unsigned long flags)
3139 {
3140 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3141     defined(CONFIG_TRACE_IRQFLAGS)
3142         if (!debug_locks)
3143                 return;
3144
3145         if (irqs_disabled_flags(flags)) {
3146                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3147                         printk("possible reason: unannotated irqs-off.\n");
3148                 }
3149         } else {
3150                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3151                         printk("possible reason: unannotated irqs-on.\n");
3152                 }
3153         }
3154
3155         /*
3156          * We dont accurately track softirq state in e.g.
3157          * hardirq contexts (such as on 4KSTACKS), so only
3158          * check if not in hardirq contexts:
3159          */
3160         if (!hardirq_count()) {
3161                 if (softirq_count())
3162                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3163                 else
3164                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3165         }
3166
3167         if (!debug_locks)
3168                 print_irqtrace_events(current);
3169 #endif
3170 }
3171
3172 void lock_set_class(struct lockdep_map *lock, const char *name,
3173                     struct lock_class_key *key, unsigned int subclass,
3174                     unsigned long ip)
3175 {
3176         unsigned long flags;
3177
3178         if (unlikely(current->lockdep_recursion))
3179                 return;
3180
3181         raw_local_irq_save(flags);
3182         current->lockdep_recursion = 1;
3183         check_flags(flags);
3184         if (__lock_set_class(lock, name, key, subclass, ip))
3185                 check_chain_key(current);
3186         current->lockdep_recursion = 0;
3187         raw_local_irq_restore(flags);
3188 }
3189 EXPORT_SYMBOL_GPL(lock_set_class);
3190
3191 /*
3192  * We are not always called with irqs disabled - do that here,
3193  * and also avoid lockdep recursion:
3194  */
3195 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3196                           int trylock, int read, int check,
3197                           struct lockdep_map *nest_lock, unsigned long ip)
3198 {
3199         unsigned long flags;
3200
3201         trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3202
3203         if (unlikely(current->lockdep_recursion))
3204                 return;
3205
3206         raw_local_irq_save(flags);
3207         check_flags(flags);
3208
3209         current->lockdep_recursion = 1;
3210         __lock_acquire(lock, subclass, trylock, read, check,
3211                        irqs_disabled_flags(flags), nest_lock, ip, 0);
3212         current->lockdep_recursion = 0;
3213         raw_local_irq_restore(flags);
3214 }
3215 EXPORT_SYMBOL_GPL(lock_acquire);
3216
3217 void lock_release(struct lockdep_map *lock, int nested,
3218                           unsigned long ip)
3219 {
3220         unsigned long flags;
3221
3222         trace_lock_release(lock, nested, ip);
3223
3224         if (unlikely(current->lockdep_recursion))
3225                 return;
3226
3227         raw_local_irq_save(flags);
3228         check_flags(flags);
3229         current->lockdep_recursion = 1;
3230         __lock_release(lock, nested, ip);
3231         current->lockdep_recursion = 0;
3232         raw_local_irq_restore(flags);
3233 }
3234 EXPORT_SYMBOL_GPL(lock_release);
3235
3236 int lock_is_held(struct lockdep_map *lock)
3237 {
3238         unsigned long flags;
3239         int ret = 0;
3240
3241         if (unlikely(current->lockdep_recursion))
3242                 return ret;
3243
3244         raw_local_irq_save(flags);
3245         check_flags(flags);
3246
3247         current->lockdep_recursion = 1;
3248         ret = __lock_is_held(lock);
3249         current->lockdep_recursion = 0;
3250         raw_local_irq_restore(flags);
3251
3252         return ret;
3253 }
3254 EXPORT_SYMBOL_GPL(lock_is_held);
3255
3256 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3257 {
3258         current->lockdep_reclaim_gfp = gfp_mask;
3259 }
3260
3261 void lockdep_clear_current_reclaim_state(void)
3262 {
3263         current->lockdep_reclaim_gfp = 0;
3264 }
3265
3266 #ifdef CONFIG_LOCK_STAT
3267 static int
3268 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3269                            unsigned long ip)
3270 {
3271         if (!debug_locks_off())
3272                 return 0;
3273         if (debug_locks_silent)
3274                 return 0;
3275
3276         printk("\n=================================\n");
3277         printk(  "[ BUG: bad contention detected! ]\n");
3278         printk(  "---------------------------------\n");
3279         printk("%s/%d is trying to contend lock (",
3280                 curr->comm, task_pid_nr(curr));
3281         print_lockdep_cache(lock);
3282         printk(") at:\n");
3283         print_ip_sym(ip);
3284         printk("but there are no locks held!\n");
3285         printk("\nother info that might help us debug this:\n");
3286         lockdep_print_held_locks(curr);
3287
3288         printk("\nstack backtrace:\n");
3289         dump_stack();
3290
3291         return 0;
3292 }
3293
3294 static void
3295 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3296 {
3297         struct task_struct *curr = current;
3298         struct held_lock *hlock, *prev_hlock;
3299         struct lock_class_stats *stats;
3300         unsigned int depth;
3301         int i, contention_point, contending_point;
3302
3303         depth = curr->lockdep_depth;
3304         if (DEBUG_LOCKS_WARN_ON(!depth))
3305                 return;
3306
3307         prev_hlock = NULL;
3308         for (i = depth-1; i >= 0; i--) {
3309                 hlock = curr->held_locks + i;
3310                 /*
3311                  * We must not cross into another context:
3312                  */
3313                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3314                         break;
3315                 if (match_held_lock(hlock, lock))
3316                         goto found_it;
3317                 prev_hlock = hlock;
3318         }
3319         print_lock_contention_bug(curr, lock, ip);
3320         return;
3321
3322 found_it:
3323         if (hlock->instance != lock)
3324                 return;
3325
3326         hlock->waittime_stamp = lockstat_clock();
3327
3328         contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3329         contending_point = lock_point(hlock_class(hlock)->contending_point,
3330                                       lock->ip);
3331
3332         stats = get_lock_stats(hlock_class(hlock));
3333         if (contention_point < LOCKSTAT_POINTS)
3334                 stats->contention_point[contention_point]++;
3335         if (contending_point < LOCKSTAT_POINTS)
3336                 stats->contending_point[contending_point]++;
3337         if (lock->cpu != smp_processor_id())
3338                 stats->bounces[bounce_contended + !!hlock->read]++;
3339         put_lock_stats(stats);
3340 }
3341
3342 static void
3343 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3344 {
3345         struct task_struct *curr = current;
3346         struct held_lock *hlock, *prev_hlock;
3347         struct lock_class_stats *stats;
3348         unsigned int depth;
3349         u64 now, waittime = 0;
3350         int i, cpu;
3351
3352         depth = curr->lockdep_depth;
3353         if (DEBUG_LOCKS_WARN_ON(!depth))
3354                 return;
3355
3356         prev_hlock = NULL;
3357         for (i = depth-1; i >= 0; i--) {
3358                 hlock = curr->held_locks + i;
3359                 /*
3360                  * We must not cross into another context:
3361                  */
3362                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3363                         break;
3364                 if (match_held_lock(hlock, lock))
3365                         goto found_it;
3366                 prev_hlock = hlock;
3367         }
3368         print_lock_contention_bug(curr, lock, _RET_IP_);
3369         return;
3370
3371 found_it:
3372         if (hlock->instance != lock)
3373                 return;
3374
3375         cpu = smp_processor_id();
3376         if (hlock->waittime_stamp) {
3377                 now = lockstat_clock();
3378                 waittime = now - hlock->waittime_stamp;
3379                 hlock->holdtime_stamp = now;
3380         }
3381
3382         trace_lock_acquired(lock, ip, waittime);
3383
3384         stats = get_lock_stats(hlock_class(hlock));
3385         if (waittime) {
3386                 if (hlock->read)
3387                         lock_time_inc(&stats->read_waittime, waittime);
3388                 else
3389                         lock_time_inc(&stats->write_waittime, waittime);
3390         }
3391         if (lock->cpu != cpu)
3392                 stats->bounces[bounce_acquired + !!hlock->read]++;
3393         put_lock_stats(stats);
3394
3395         lock->cpu = cpu;
3396         lock->ip = ip;
3397 }
3398
3399 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3400 {
3401         unsigned long flags;
3402
3403         trace_lock_contended(lock, ip);
3404
3405         if (unlikely(!lock_stat))
3406                 return;
3407
3408         if (unlikely(current->lockdep_recursion))
3409                 return;
3410
3411         raw_local_irq_save(flags);
3412         check_flags(flags);
3413         current->lockdep_recursion = 1;
3414         __lock_contended(lock, ip);
3415         current->lockdep_recursion = 0;
3416         raw_local_irq_restore(flags);
3417 }
3418 EXPORT_SYMBOL_GPL(lock_contended);
3419
3420 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3421 {
3422         unsigned long flags;
3423
3424         if (unlikely(!lock_stat))
3425                 return;
3426
3427         if (unlikely(current->lockdep_recursion))
3428                 return;
3429
3430         raw_local_irq_save(flags);
3431         check_flags(flags);
3432         current->lockdep_recursion = 1;
3433         __lock_acquired(lock, ip);
3434         current->lockdep_recursion = 0;
3435         raw_local_irq_restore(flags);
3436 }
3437 EXPORT_SYMBOL_GPL(lock_acquired);
3438 #endif
3439
3440 /*
3441  * Used by the testsuite, sanitize the validator state
3442  * after a simulated failure:
3443  */
3444
3445 void lockdep_reset(void)
3446 {
3447         unsigned long flags;
3448         int i;
3449
3450         raw_local_irq_save(flags);
3451         current->curr_chain_key = 0;
3452         current->lockdep_depth = 0;
3453         current->lockdep_recursion = 0;
3454         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3455         nr_hardirq_chains = 0;
3456         nr_softirq_chains = 0;
3457         nr_process_chains = 0;
3458         debug_locks = 1;
3459         for (i = 0; i < CHAINHASH_SIZE; i++)
3460                 INIT_LIST_HEAD(chainhash_table + i);
3461         raw_local_irq_restore(flags);
3462 }
3463
3464 static void zap_class(struct lock_class *class)
3465 {
3466         int i;
3467
3468         /*
3469          * Remove all dependencies this lock is
3470          * involved in:
3471          */
3472         for (i = 0; i < nr_list_entries; i++) {
3473                 if (list_entries[i].class == class)
3474                         list_del_rcu(&list_entries[i].entry);
3475         }
3476         /*
3477          * Unhash the class and remove it from the all_lock_classes list:
3478          */
3479         list_del_rcu(&class->hash_entry);
3480         list_del_rcu(&class->lock_entry);
3481
3482         class->key = NULL;
3483 }
3484
3485 static inline int within(const void *addr, void *start, unsigned long size)
3486 {
3487         return addr >= start && addr < start + size;
3488 }
3489
3490 void lockdep_free_key_range(void *start, unsigned long size)
3491 {
3492         struct lock_class *class, *next;
3493         struct list_head *head;
3494         unsigned long flags;
3495         int i;
3496         int locked;
3497
3498         raw_local_irq_save(flags);
3499         locked = graph_lock();
3500
3501         /*
3502          * Unhash all classes that were created by this module:
3503          */
3504         for (i = 0; i < CLASSHASH_SIZE; i++) {
3505                 head = classhash_table + i;
3506                 if (list_empty(head))
3507                         continue;
3508                 list_for_each_entry_safe(class, next, head, hash_entry) {
3509                         if (within(class->key, start, size))
3510                                 zap_class(class);
3511                         else if (within(class->name, start, size))
3512                                 zap_class(class);
3513                 }
3514         }
3515
3516         if (locked)
3517                 graph_unlock();
3518         raw_local_irq_restore(flags);
3519 }
3520
3521 void lockdep_reset_lock(struct lockdep_map *lock)
3522 {
3523         struct lock_class *class, *next;
3524         struct list_head *head;
3525         unsigned long flags;
3526         int i, j;
3527         int locked;
3528
3529         raw_local_irq_save(flags);
3530
3531         /*
3532          * Remove all classes this lock might have:
3533          */
3534         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3535                 /*
3536                  * If the class exists we look it up and zap it:
3537                  */
3538                 class = look_up_lock_class(lock, j);
3539                 if (class)
3540                         zap_class(class);
3541         }
3542         /*
3543          * Debug check: in the end all mapped classes should
3544          * be gone.
3545          */
3546         locked = graph_lock();
3547         for (i = 0; i < CLASSHASH_SIZE; i++) {
3548                 head = classhash_table + i;
3549                 if (list_empty(head))
3550                         continue;
3551                 list_for_each_entry_safe(class, next, head, hash_entry) {
3552                         if (unlikely(class == lock->class_cache)) {
3553                                 if (debug_locks_off_graph_unlock())
3554                                         WARN_ON(1);
3555                                 goto out_restore;
3556                         }
3557                 }
3558         }
3559         if (locked)
3560                 graph_unlock();
3561
3562 out_restore:
3563         raw_local_irq_restore(flags);
3564 }
3565
3566 void lockdep_init(void)
3567 {
3568         int i;
3569
3570         /*
3571          * Some architectures have their own start_kernel()
3572          * code which calls lockdep_init(), while we also
3573          * call lockdep_init() from the start_kernel() itself,
3574          * and we want to initialize the hashes only once:
3575          */
3576         if (lockdep_initialized)
3577                 return;
3578
3579         for (i = 0; i < CLASSHASH_SIZE; i++)
3580                 INIT_LIST_HEAD(classhash_table + i);
3581
3582         for (i = 0; i < CHAINHASH_SIZE; i++)
3583                 INIT_LIST_HEAD(chainhash_table + i);
3584
3585         lockdep_initialized = 1;
3586 }
3587
3588 void __init lockdep_info(void)
3589 {
3590         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3591
3592         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3593         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3594         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3595         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3596         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3597         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3598         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3599
3600         printk(" memory used by lock dependency info: %lu kB\n",
3601                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3602                 sizeof(struct list_head) * CLASSHASH_SIZE +
3603                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3604                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3605                 sizeof(struct list_head) * CHAINHASH_SIZE
3606 #ifdef CONFIG_PROVE_LOCKING
3607                 + sizeof(struct circular_queue)
3608 #endif
3609                 ) / 1024
3610                 );
3611
3612         printk(" per task-struct memory footprint: %lu bytes\n",
3613                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3614
3615 #ifdef CONFIG_DEBUG_LOCKDEP
3616         if (lockdep_init_error) {
3617                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3618                 printk("Call stack leading to lockdep invocation was:\n");
3619                 print_stack_trace(&lockdep_init_trace, 0);
3620         }
3621 #endif
3622 }
3623
3624 static void
3625 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3626                      const void *mem_to, struct held_lock *hlock)
3627 {
3628         if (!debug_locks_off())
3629                 return;
3630         if (debug_locks_silent)
3631                 return;
3632
3633         printk("\n=========================\n");
3634         printk(  "[ BUG: held lock freed! ]\n");
3635         printk(  "-------------------------\n");
3636         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3637                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3638         print_lock(hlock);
3639         lockdep_print_held_locks(curr);
3640
3641         printk("\nstack backtrace:\n");
3642         dump_stack();
3643 }
3644
3645 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3646                                 const void* lock_from, unsigned long lock_len)
3647 {
3648         return lock_from + lock_len <= mem_from ||
3649                 mem_from + mem_len <= lock_from;
3650 }
3651
3652 /*
3653  * Called when kernel memory is freed (or unmapped), or if a lock
3654  * is destroyed or reinitialized - this code checks whether there is
3655  * any held lock in the memory range of <from> to <to>:
3656  */
3657 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3658 {
3659         struct task_struct *curr = current;
3660         struct held_lock *hlock;
3661         unsigned long flags;
3662         int i;
3663
3664         if (unlikely(!debug_locks))
3665                 return;
3666
3667         local_irq_save(flags);
3668         for (i = 0; i < curr->lockdep_depth; i++) {
3669                 hlock = curr->held_locks + i;
3670
3671                 if (not_in_range(mem_from, mem_len, hlock->instance,
3672                                         sizeof(*hlock->instance)))
3673                         continue;
3674
3675                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3676                 break;
3677         }
3678         local_irq_restore(flags);
3679 }
3680 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3681
3682 static void print_held_locks_bug(struct task_struct *curr)
3683 {
3684         if (!debug_locks_off())
3685                 return;
3686         if (debug_locks_silent)
3687                 return;
3688
3689         printk("\n=====================================\n");
3690         printk(  "[ BUG: lock held at task exit time! ]\n");
3691         printk(  "-------------------------------------\n");
3692         printk("%s/%d is exiting with locks still held!\n",
3693                 curr->comm, task_pid_nr(curr));
3694         lockdep_print_held_locks(curr);
3695
3696         printk("\nstack backtrace:\n");
3697         dump_stack();
3698 }
3699
3700 void debug_check_no_locks_held(struct task_struct *task)
3701 {
3702         if (unlikely(task->lockdep_depth > 0))
3703                 print_held_locks_bug(task);
3704 }
3705
3706 void debug_show_all_locks(void)
3707 {
3708         struct task_struct *g, *p;
3709         int count = 10;
3710         int unlock = 1;
3711
3712         if (unlikely(!debug_locks)) {
3713                 printk("INFO: lockdep is turned off.\n");
3714                 return;
3715         }
3716         printk("\nShowing all locks held in the system:\n");
3717
3718         /*
3719          * Here we try to get the tasklist_lock as hard as possible,
3720          * if not successful after 2 seconds we ignore it (but keep
3721          * trying). This is to enable a debug printout even if a
3722          * tasklist_lock-holding task deadlocks or crashes.
3723          */
3724 retry:
3725         if (!read_trylock(&tasklist_lock)) {
3726                 if (count == 10)
3727                         printk("hm, tasklist_lock locked, retrying... ");
3728                 if (count) {
3729                         count--;
3730                         printk(" #%d", 10-count);
3731                         mdelay(200);
3732                         goto retry;
3733                 }
3734                 printk(" ignoring it.\n");
3735                 unlock = 0;
3736         } else {
3737                 if (count != 10)
3738                         printk(KERN_CONT " locked it.\n");
3739         }
3740
3741         do_each_thread(g, p) {
3742                 /*
3743                  * It's not reliable to print a task's held locks
3744                  * if it's not sleeping (or if it's not the current
3745                  * task):
3746                  */
3747                 if (p->state == TASK_RUNNING && p != current)
3748                         continue;
3749                 if (p->lockdep_depth)
3750                         lockdep_print_held_locks(p);
3751                 if (!unlock)
3752                         if (read_trylock(&tasklist_lock))
3753                                 unlock = 1;
3754         } while_each_thread(g, p);
3755
3756         printk("\n");
3757         printk("=============================================\n\n");
3758
3759         if (unlock)
3760                 read_unlock(&tasklist_lock);
3761 }
3762 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3763
3764 /*
3765  * Careful: only use this function if you are sure that
3766  * the task cannot run in parallel!
3767  */
3768 void __debug_show_held_locks(struct task_struct *task)
3769 {
3770         if (unlikely(!debug_locks)) {
3771                 printk("INFO: lockdep is turned off.\n");
3772                 return;
3773         }
3774         lockdep_print_held_locks(task);
3775 }
3776 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3777
3778 void debug_show_held_locks(struct task_struct *task)
3779 {
3780                 __debug_show_held_locks(task);
3781 }
3782 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3783
3784 void lockdep_sys_exit(void)
3785 {
3786         struct task_struct *curr = current;
3787
3788         if (unlikely(curr->lockdep_depth)) {
3789                 if (!debug_locks_off())
3790                         return;
3791                 printk("\n================================================\n");
3792                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3793                 printk(  "------------------------------------------------\n");
3794                 printk("%s/%d is leaving the kernel with locks still held!\n",
3795                                 curr->comm, curr->pid);
3796                 lockdep_print_held_locks(curr);
3797         }
3798 }
3799
3800 void lockdep_rcu_dereference(const char *file, const int line)
3801 {
3802         struct task_struct *curr = current;
3803
3804         if (!debug_locks_off())
3805                 return;
3806         printk("\n===================================================\n");
3807         printk(  "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3808         printk(  "---------------------------------------------------\n");
3809         printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3810                         file, line);
3811         printk("\nother info that might help us debug this:\n\n");
3812         lockdep_print_held_locks(curr);
3813         printk("\nstack backtrace:\n");
3814         dump_stack();
3815 }
3816 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);