Merge branch 'master' into next
[linux-2.6.git] / kernel / lockdep.c
1 /*
2  * kernel/lockdep.c
3  *
4  * Runtime locking correctness validator
5  *
6  * Started by Ingo Molnar:
7  *
8  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
10  *
11  * this code maps all the lock dependencies as they occur in a live kernel
12  * and will warn about the following classes of locking bugs:
13  *
14  * - lock inversion scenarios
15  * - circular lock dependencies
16  * - hardirq/softirq safe/unsafe locking bugs
17  *
18  * Bugs are reported even if the current locking scenario does not cause
19  * any deadlock at this point.
20  *
21  * I.e. if anytime in the past two locks were taken in a different order,
22  * even if it happened for another task, even if those were different
23  * locks (but of the same class as this lock), this code will detect it.
24  *
25  * Thanks to Arjan van de Ven for coming up with the initial idea of
26  * mapping lock dependencies runtime.
27  */
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
47
48 #include <asm/sections.h>
49
50 #include "lockdep_internals.h"
51
52 #define CREATE_TRACE_POINTS
53 #include <trace/events/lock.h>
54
55 #ifdef CONFIG_PROVE_LOCKING
56 int prove_locking = 1;
57 module_param(prove_locking, int, 0644);
58 #else
59 #define prove_locking 0
60 #endif
61
62 #ifdef CONFIG_LOCK_STAT
63 int lock_stat = 1;
64 module_param(lock_stat, int, 0644);
65 #else
66 #define lock_stat 0
67 #endif
68
69 /*
70  * lockdep_lock: protects the lockdep graph, the hashes and the
71  *               class/list/hash allocators.
72  *
73  * This is one of the rare exceptions where it's justified
74  * to use a raw spinlock - we really dont want the spinlock
75  * code to recurse back into the lockdep code...
76  */
77 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
78
79 static int graph_lock(void)
80 {
81         arch_spin_lock(&lockdep_lock);
82         /*
83          * Make sure that if another CPU detected a bug while
84          * walking the graph we dont change it (while the other
85          * CPU is busy printing out stuff with the graph lock
86          * dropped already)
87          */
88         if (!debug_locks) {
89                 arch_spin_unlock(&lockdep_lock);
90                 return 0;
91         }
92         /* prevent any recursions within lockdep from causing deadlocks */
93         current->lockdep_recursion++;
94         return 1;
95 }
96
97 static inline int graph_unlock(void)
98 {
99         if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
100                 return DEBUG_LOCKS_WARN_ON(1);
101
102         current->lockdep_recursion--;
103         arch_spin_unlock(&lockdep_lock);
104         return 0;
105 }
106
107 /*
108  * Turn lock debugging off and return with 0 if it was off already,
109  * and also release the graph lock:
110  */
111 static inline int debug_locks_off_graph_unlock(void)
112 {
113         int ret = debug_locks_off();
114
115         arch_spin_unlock(&lockdep_lock);
116
117         return ret;
118 }
119
120 static int lockdep_initialized;
121
122 unsigned long nr_list_entries;
123 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
124
125 /*
126  * All data structures here are protected by the global debug_lock.
127  *
128  * Mutex key structs only get allocated, once during bootup, and never
129  * get freed - this significantly simplifies the debugging code.
130  */
131 unsigned long nr_lock_classes;
132 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
133
134 static inline struct lock_class *hlock_class(struct held_lock *hlock)
135 {
136         if (!hlock->class_idx) {
137                 DEBUG_LOCKS_WARN_ON(1);
138                 return NULL;
139         }
140         return lock_classes + hlock->class_idx - 1;
141 }
142
143 #ifdef CONFIG_LOCK_STAT
144 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
145                       cpu_lock_stats);
146
147 static inline u64 lockstat_clock(void)
148 {
149         return local_clock();
150 }
151
152 static int lock_point(unsigned long points[], unsigned long ip)
153 {
154         int i;
155
156         for (i = 0; i < LOCKSTAT_POINTS; i++) {
157                 if (points[i] == 0) {
158                         points[i] = ip;
159                         break;
160                 }
161                 if (points[i] == ip)
162                         break;
163         }
164
165         return i;
166 }
167
168 static void lock_time_inc(struct lock_time *lt, u64 time)
169 {
170         if (time > lt->max)
171                 lt->max = time;
172
173         if (time < lt->min || !lt->nr)
174                 lt->min = time;
175
176         lt->total += time;
177         lt->nr++;
178 }
179
180 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
181 {
182         if (!src->nr)
183                 return;
184
185         if (src->max > dst->max)
186                 dst->max = src->max;
187
188         if (src->min < dst->min || !dst->nr)
189                 dst->min = src->min;
190
191         dst->total += src->total;
192         dst->nr += src->nr;
193 }
194
195 struct lock_class_stats lock_stats(struct lock_class *class)
196 {
197         struct lock_class_stats stats;
198         int cpu, i;
199
200         memset(&stats, 0, sizeof(struct lock_class_stats));
201         for_each_possible_cpu(cpu) {
202                 struct lock_class_stats *pcs =
203                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
204
205                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
206                         stats.contention_point[i] += pcs->contention_point[i];
207
208                 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
209                         stats.contending_point[i] += pcs->contending_point[i];
210
211                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
212                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
213
214                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
215                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
216
217                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
218                         stats.bounces[i] += pcs->bounces[i];
219         }
220
221         return stats;
222 }
223
224 void clear_lock_stats(struct lock_class *class)
225 {
226         int cpu;
227
228         for_each_possible_cpu(cpu) {
229                 struct lock_class_stats *cpu_stats =
230                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
231
232                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
233         }
234         memset(class->contention_point, 0, sizeof(class->contention_point));
235         memset(class->contending_point, 0, sizeof(class->contending_point));
236 }
237
238 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
239 {
240         return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
241 }
242
243 static void put_lock_stats(struct lock_class_stats *stats)
244 {
245         put_cpu_var(cpu_lock_stats);
246 }
247
248 static void lock_release_holdtime(struct held_lock *hlock)
249 {
250         struct lock_class_stats *stats;
251         u64 holdtime;
252
253         if (!lock_stat)
254                 return;
255
256         holdtime = lockstat_clock() - hlock->holdtime_stamp;
257
258         stats = get_lock_stats(hlock_class(hlock));
259         if (hlock->read)
260                 lock_time_inc(&stats->read_holdtime, holdtime);
261         else
262                 lock_time_inc(&stats->write_holdtime, holdtime);
263         put_lock_stats(stats);
264 }
265 #else
266 static inline void lock_release_holdtime(struct held_lock *hlock)
267 {
268 }
269 #endif
270
271 /*
272  * We keep a global list of all lock classes. The list only grows,
273  * never shrinks. The list is only accessed with the lockdep
274  * spinlock lock held.
275  */
276 LIST_HEAD(all_lock_classes);
277
278 /*
279  * The lockdep classes are in a hash-table as well, for fast lookup:
280  */
281 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
282 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
283 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
284 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
285
286 static struct list_head classhash_table[CLASSHASH_SIZE];
287
288 /*
289  * We put the lock dependency chains into a hash-table as well, to cache
290  * their existence:
291  */
292 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
293 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
294 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
295 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
296
297 static struct list_head chainhash_table[CHAINHASH_SIZE];
298
299 /*
300  * The hash key of the lock dependency chains is a hash itself too:
301  * it's a hash of all locks taken up to that lock, including that lock.
302  * It's a 64-bit hash, because it's important for the keys to be
303  * unique.
304  */
305 #define iterate_chain_key(key1, key2) \
306         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
307         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
308         (key2))
309
310 void lockdep_off(void)
311 {
312         current->lockdep_recursion++;
313 }
314 EXPORT_SYMBOL(lockdep_off);
315
316 void lockdep_on(void)
317 {
318         current->lockdep_recursion--;
319 }
320 EXPORT_SYMBOL(lockdep_on);
321
322 /*
323  * Debugging switches:
324  */
325
326 #define VERBOSE                 0
327 #define VERY_VERBOSE            0
328
329 #if VERBOSE
330 # define HARDIRQ_VERBOSE        1
331 # define SOFTIRQ_VERBOSE        1
332 # define RECLAIM_VERBOSE        1
333 #else
334 # define HARDIRQ_VERBOSE        0
335 # define SOFTIRQ_VERBOSE        0
336 # define RECLAIM_VERBOSE        0
337 #endif
338
339 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
340 /*
341  * Quick filtering for interesting events:
342  */
343 static int class_filter(struct lock_class *class)
344 {
345 #if 0
346         /* Example */
347         if (class->name_version == 1 &&
348                         !strcmp(class->name, "lockname"))
349                 return 1;
350         if (class->name_version == 1 &&
351                         !strcmp(class->name, "&struct->lockfield"))
352                 return 1;
353 #endif
354         /* Filter everything else. 1 would be to allow everything else */
355         return 0;
356 }
357 #endif
358
359 static int verbose(struct lock_class *class)
360 {
361 #if VERBOSE
362         return class_filter(class);
363 #endif
364         return 0;
365 }
366
367 /*
368  * Stack-trace: tightly packed array of stack backtrace
369  * addresses. Protected by the graph_lock.
370  */
371 unsigned long nr_stack_trace_entries;
372 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
373
374 static int save_trace(struct stack_trace *trace)
375 {
376         trace->nr_entries = 0;
377         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
378         trace->entries = stack_trace + nr_stack_trace_entries;
379
380         trace->skip = 3;
381
382         save_stack_trace(trace);
383
384         /*
385          * Some daft arches put -1 at the end to indicate its a full trace.
386          *
387          * <rant> this is buggy anyway, since it takes a whole extra entry so a
388          * complete trace that maxes out the entries provided will be reported
389          * as incomplete, friggin useless </rant>
390          */
391         if (trace->nr_entries != 0 &&
392             trace->entries[trace->nr_entries-1] == ULONG_MAX)
393                 trace->nr_entries--;
394
395         trace->max_entries = trace->nr_entries;
396
397         nr_stack_trace_entries += trace->nr_entries;
398
399         if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
400                 if (!debug_locks_off_graph_unlock())
401                         return 0;
402
403                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
404                 printk("turning off the locking correctness validator.\n");
405                 dump_stack();
406
407                 return 0;
408         }
409
410         return 1;
411 }
412
413 unsigned int nr_hardirq_chains;
414 unsigned int nr_softirq_chains;
415 unsigned int nr_process_chains;
416 unsigned int max_lockdep_depth;
417
418 #ifdef CONFIG_DEBUG_LOCKDEP
419 /*
420  * We cannot printk in early bootup code. Not even early_printk()
421  * might work. So we mark any initialization errors and printk
422  * about it later on, in lockdep_info().
423  */
424 static int lockdep_init_error;
425 static unsigned long lockdep_init_trace_data[20];
426 static struct stack_trace lockdep_init_trace = {
427         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
428         .entries = lockdep_init_trace_data,
429 };
430
431 /*
432  * Various lockdep statistics:
433  */
434 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
435 #endif
436
437 /*
438  * Locking printouts:
439  */
440
441 #define __USAGE(__STATE)                                                \
442         [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
443         [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
444         [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
445         [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
446
447 static const char *usage_str[] =
448 {
449 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
450 #include "lockdep_states.h"
451 #undef LOCKDEP_STATE
452         [LOCK_USED] = "INITIAL USE",
453 };
454
455 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
456 {
457         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
458 }
459
460 static inline unsigned long lock_flag(enum lock_usage_bit bit)
461 {
462         return 1UL << bit;
463 }
464
465 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
466 {
467         char c = '.';
468
469         if (class->usage_mask & lock_flag(bit + 2))
470                 c = '+';
471         if (class->usage_mask & lock_flag(bit)) {
472                 c = '-';
473                 if (class->usage_mask & lock_flag(bit + 2))
474                         c = '?';
475         }
476
477         return c;
478 }
479
480 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
481 {
482         int i = 0;
483
484 #define LOCKDEP_STATE(__STATE)                                          \
485         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
486         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
487 #include "lockdep_states.h"
488 #undef LOCKDEP_STATE
489
490         usage[i] = '\0';
491 }
492
493 static void print_lock_name(struct lock_class *class)
494 {
495         char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
496         const char *name;
497
498         get_usage_chars(class, usage);
499
500         name = class->name;
501         if (!name) {
502                 name = __get_key_name(class->key, str);
503                 printk(" (%s", name);
504         } else {
505                 printk(" (%s", name);
506                 if (class->name_version > 1)
507                         printk("#%d", class->name_version);
508                 if (class->subclass)
509                         printk("/%d", class->subclass);
510         }
511         printk("){%s}", usage);
512 }
513
514 static void print_lockdep_cache(struct lockdep_map *lock)
515 {
516         const char *name;
517         char str[KSYM_NAME_LEN];
518
519         name = lock->name;
520         if (!name)
521                 name = __get_key_name(lock->key->subkeys, str);
522
523         printk("%s", name);
524 }
525
526 static void print_lock(struct held_lock *hlock)
527 {
528         print_lock_name(hlock_class(hlock));
529         printk(", at: ");
530         print_ip_sym(hlock->acquire_ip);
531 }
532
533 static void lockdep_print_held_locks(struct task_struct *curr)
534 {
535         int i, depth = curr->lockdep_depth;
536
537         if (!depth) {
538                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
539                 return;
540         }
541         printk("%d lock%s held by %s/%d:\n",
542                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
543
544         for (i = 0; i < depth; i++) {
545                 printk(" #%d: ", i);
546                 print_lock(curr->held_locks + i);
547         }
548 }
549
550 static void print_kernel_version(void)
551 {
552         printk("%s %.*s\n", init_utsname()->release,
553                 (int)strcspn(init_utsname()->version, " "),
554                 init_utsname()->version);
555 }
556
557 static int very_verbose(struct lock_class *class)
558 {
559 #if VERY_VERBOSE
560         return class_filter(class);
561 #endif
562         return 0;
563 }
564
565 /*
566  * Is this the address of a static object:
567  */
568 static int static_obj(void *obj)
569 {
570         unsigned long start = (unsigned long) &_stext,
571                       end   = (unsigned long) &_end,
572                       addr  = (unsigned long) obj;
573
574         /*
575          * static variable?
576          */
577         if ((addr >= start) && (addr < end))
578                 return 1;
579
580         if (arch_is_kernel_data(addr))
581                 return 1;
582
583         /*
584          * in-kernel percpu var?
585          */
586         if (is_kernel_percpu_address(addr))
587                 return 1;
588
589         /*
590          * module static or percpu var?
591          */
592         return is_module_address(addr) || is_module_percpu_address(addr);
593 }
594
595 /*
596  * To make lock name printouts unique, we calculate a unique
597  * class->name_version generation counter:
598  */
599 static int count_matching_names(struct lock_class *new_class)
600 {
601         struct lock_class *class;
602         int count = 0;
603
604         if (!new_class->name)
605                 return 0;
606
607         list_for_each_entry(class, &all_lock_classes, lock_entry) {
608                 if (new_class->key - new_class->subclass == class->key)
609                         return class->name_version;
610                 if (class->name && !strcmp(class->name, new_class->name))
611                         count = max(count, class->name_version);
612         }
613
614         return count + 1;
615 }
616
617 /*
618  * Register a lock's class in the hash-table, if the class is not present
619  * yet. Otherwise we look it up. We cache the result in the lock object
620  * itself, so actual lookup of the hash should be once per lock object.
621  */
622 static inline struct lock_class *
623 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
624 {
625         struct lockdep_subclass_key *key;
626         struct list_head *hash_head;
627         struct lock_class *class;
628
629 #ifdef CONFIG_DEBUG_LOCKDEP
630         /*
631          * If the architecture calls into lockdep before initializing
632          * the hashes then we'll warn about it later. (we cannot printk
633          * right now)
634          */
635         if (unlikely(!lockdep_initialized)) {
636                 lockdep_init();
637                 lockdep_init_error = 1;
638                 save_stack_trace(&lockdep_init_trace);
639         }
640 #endif
641
642         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
643                 debug_locks_off();
644                 printk(KERN_ERR
645                         "BUG: looking up invalid subclass: %u\n", subclass);
646                 printk(KERN_ERR
647                         "turning off the locking correctness validator.\n");
648                 dump_stack();
649                 return NULL;
650         }
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[0] = class;
788         else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
789                 lock->class_cache[subclass] = class;
790
791         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
792                 return NULL;
793
794         return class;
795 }
796
797 #ifdef CONFIG_PROVE_LOCKING
798 /*
799  * Allocate a lockdep entry. (assumes the graph_lock held, returns
800  * with NULL on failure)
801  */
802 static struct lock_list *alloc_list_entry(void)
803 {
804         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
805                 if (!debug_locks_off_graph_unlock())
806                         return NULL;
807
808                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
809                 printk("turning off the locking correctness validator.\n");
810                 dump_stack();
811                 return NULL;
812         }
813         return list_entries + nr_list_entries++;
814 }
815
816 /*
817  * Add a new dependency to the head of the list:
818  */
819 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
820                             struct list_head *head, unsigned long ip,
821                             int distance, struct stack_trace *trace)
822 {
823         struct lock_list *entry;
824         /*
825          * Lock not present yet - get a new dependency struct and
826          * add it to the list:
827          */
828         entry = alloc_list_entry();
829         if (!entry)
830                 return 0;
831
832         entry->class = this;
833         entry->distance = distance;
834         entry->trace = *trace;
835         /*
836          * Since we never remove from the dependency list, the list can
837          * be walked lockless by other CPUs, it's only allocation
838          * that must be protected by the spinlock. But this also means
839          * we must make new entries visible only once writes to the
840          * entry become visible - hence the RCU op:
841          */
842         list_add_tail_rcu(&entry->entry, head);
843
844         return 1;
845 }
846
847 /*
848  * For good efficiency of modular, we use power of 2
849  */
850 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
851 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
852
853 /*
854  * The circular_queue and helpers is used to implement the
855  * breadth-first search(BFS)algorithem, by which we can build
856  * the shortest path from the next lock to be acquired to the
857  * previous held lock if there is a circular between them.
858  */
859 struct circular_queue {
860         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
861         unsigned int  front, rear;
862 };
863
864 static struct circular_queue lock_cq;
865
866 unsigned int max_bfs_queue_depth;
867
868 static unsigned int lockdep_dependency_gen_id;
869
870 static inline void __cq_init(struct circular_queue *cq)
871 {
872         cq->front = cq->rear = 0;
873         lockdep_dependency_gen_id++;
874 }
875
876 static inline int __cq_empty(struct circular_queue *cq)
877 {
878         return (cq->front == cq->rear);
879 }
880
881 static inline int __cq_full(struct circular_queue *cq)
882 {
883         return ((cq->rear + 1) & CQ_MASK) == cq->front;
884 }
885
886 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
887 {
888         if (__cq_full(cq))
889                 return -1;
890
891         cq->element[cq->rear] = elem;
892         cq->rear = (cq->rear + 1) & CQ_MASK;
893         return 0;
894 }
895
896 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
897 {
898         if (__cq_empty(cq))
899                 return -1;
900
901         *elem = cq->element[cq->front];
902         cq->front = (cq->front + 1) & CQ_MASK;
903         return 0;
904 }
905
906 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
907 {
908         return (cq->rear - cq->front) & CQ_MASK;
909 }
910
911 static inline void mark_lock_accessed(struct lock_list *lock,
912                                         struct lock_list *parent)
913 {
914         unsigned long nr;
915
916         nr = lock - list_entries;
917         WARN_ON(nr >= nr_list_entries);
918         lock->parent = parent;
919         lock->class->dep_gen_id = lockdep_dependency_gen_id;
920 }
921
922 static inline unsigned long lock_accessed(struct lock_list *lock)
923 {
924         unsigned long nr;
925
926         nr = lock - list_entries;
927         WARN_ON(nr >= nr_list_entries);
928         return lock->class->dep_gen_id == lockdep_dependency_gen_id;
929 }
930
931 static inline struct lock_list *get_lock_parent(struct lock_list *child)
932 {
933         return child->parent;
934 }
935
936 static inline int get_lock_depth(struct lock_list *child)
937 {
938         int depth = 0;
939         struct lock_list *parent;
940
941         while ((parent = get_lock_parent(child))) {
942                 child = parent;
943                 depth++;
944         }
945         return depth;
946 }
947
948 static int __bfs(struct lock_list *source_entry,
949                  void *data,
950                  int (*match)(struct lock_list *entry, void *data),
951                  struct lock_list **target_entry,
952                  int forward)
953 {
954         struct lock_list *entry;
955         struct list_head *head;
956         struct circular_queue *cq = &lock_cq;
957         int ret = 1;
958
959         if (match(source_entry, data)) {
960                 *target_entry = source_entry;
961                 ret = 0;
962                 goto exit;
963         }
964
965         if (forward)
966                 head = &source_entry->class->locks_after;
967         else
968                 head = &source_entry->class->locks_before;
969
970         if (list_empty(head))
971                 goto exit;
972
973         __cq_init(cq);
974         __cq_enqueue(cq, (unsigned long)source_entry);
975
976         while (!__cq_empty(cq)) {
977                 struct lock_list *lock;
978
979                 __cq_dequeue(cq, (unsigned long *)&lock);
980
981                 if (!lock->class) {
982                         ret = -2;
983                         goto exit;
984                 }
985
986                 if (forward)
987                         head = &lock->class->locks_after;
988                 else
989                         head = &lock->class->locks_before;
990
991                 list_for_each_entry(entry, head, entry) {
992                         if (!lock_accessed(entry)) {
993                                 unsigned int cq_depth;
994                                 mark_lock_accessed(entry, lock);
995                                 if (match(entry, data)) {
996                                         *target_entry = entry;
997                                         ret = 0;
998                                         goto exit;
999                                 }
1000
1001                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
1002                                         ret = -1;
1003                                         goto exit;
1004                                 }
1005                                 cq_depth = __cq_get_elem_count(cq);
1006                                 if (max_bfs_queue_depth < cq_depth)
1007                                         max_bfs_queue_depth = cq_depth;
1008                         }
1009                 }
1010         }
1011 exit:
1012         return ret;
1013 }
1014
1015 static inline int __bfs_forwards(struct lock_list *src_entry,
1016                         void *data,
1017                         int (*match)(struct lock_list *entry, void *data),
1018                         struct lock_list **target_entry)
1019 {
1020         return __bfs(src_entry, data, match, target_entry, 1);
1021
1022 }
1023
1024 static inline int __bfs_backwards(struct lock_list *src_entry,
1025                         void *data,
1026                         int (*match)(struct lock_list *entry, void *data),
1027                         struct lock_list **target_entry)
1028 {
1029         return __bfs(src_entry, data, match, target_entry, 0);
1030
1031 }
1032
1033 /*
1034  * Recursive, forwards-direction lock-dependency checking, used for
1035  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1036  * checking.
1037  */
1038
1039 /*
1040  * Print a dependency chain entry (this is only done when a deadlock
1041  * has been detected):
1042  */
1043 static noinline int
1044 print_circular_bug_entry(struct lock_list *target, int depth)
1045 {
1046         if (debug_locks_silent)
1047                 return 0;
1048         printk("\n-> #%u", depth);
1049         print_lock_name(target->class);
1050         printk(":\n");
1051         print_stack_trace(&target->trace, 6);
1052
1053         return 0;
1054 }
1055
1056 /*
1057  * When a circular dependency is detected, print the
1058  * header first:
1059  */
1060 static noinline int
1061 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1062                         struct held_lock *check_src,
1063                         struct held_lock *check_tgt)
1064 {
1065         struct task_struct *curr = current;
1066
1067         if (debug_locks_silent)
1068                 return 0;
1069
1070         printk("\n=======================================================\n");
1071         printk(  "[ INFO: possible circular locking dependency detected ]\n");
1072         print_kernel_version();
1073         printk(  "-------------------------------------------------------\n");
1074         printk("%s/%d is trying to acquire lock:\n",
1075                 curr->comm, task_pid_nr(curr));
1076         print_lock(check_src);
1077         printk("\nbut task is already holding lock:\n");
1078         print_lock(check_tgt);
1079         printk("\nwhich lock already depends on the new lock.\n\n");
1080         printk("\nthe existing dependency chain (in reverse order) is:\n");
1081
1082         print_circular_bug_entry(entry, depth);
1083
1084         return 0;
1085 }
1086
1087 static inline int class_equal(struct lock_list *entry, void *data)
1088 {
1089         return entry->class == data;
1090 }
1091
1092 static noinline int print_circular_bug(struct lock_list *this,
1093                                 struct lock_list *target,
1094                                 struct held_lock *check_src,
1095                                 struct held_lock *check_tgt)
1096 {
1097         struct task_struct *curr = current;
1098         struct lock_list *parent;
1099         int depth;
1100
1101         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1102                 return 0;
1103
1104         if (!save_trace(&this->trace))
1105                 return 0;
1106
1107         depth = get_lock_depth(target);
1108
1109         print_circular_bug_header(target, depth, check_src, check_tgt);
1110
1111         parent = get_lock_parent(target);
1112
1113         while (parent) {
1114                 print_circular_bug_entry(parent, --depth);
1115                 parent = get_lock_parent(parent);
1116         }
1117
1118         printk("\nother info that might help us debug this:\n\n");
1119         lockdep_print_held_locks(curr);
1120
1121         printk("\nstack backtrace:\n");
1122         dump_stack();
1123
1124         return 0;
1125 }
1126
1127 static noinline int print_bfs_bug(int ret)
1128 {
1129         if (!debug_locks_off_graph_unlock())
1130                 return 0;
1131
1132         WARN(1, "lockdep bfs error:%d\n", ret);
1133
1134         return 0;
1135 }
1136
1137 static int noop_count(struct lock_list *entry, void *data)
1138 {
1139         (*(unsigned long *)data)++;
1140         return 0;
1141 }
1142
1143 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1144 {
1145         unsigned long  count = 0;
1146         struct lock_list *uninitialized_var(target_entry);
1147
1148         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1149
1150         return count;
1151 }
1152 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1153 {
1154         unsigned long ret, flags;
1155         struct lock_list this;
1156
1157         this.parent = NULL;
1158         this.class = class;
1159
1160         local_irq_save(flags);
1161         arch_spin_lock(&lockdep_lock);
1162         ret = __lockdep_count_forward_deps(&this);
1163         arch_spin_unlock(&lockdep_lock);
1164         local_irq_restore(flags);
1165
1166         return ret;
1167 }
1168
1169 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1170 {
1171         unsigned long  count = 0;
1172         struct lock_list *uninitialized_var(target_entry);
1173
1174         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1175
1176         return count;
1177 }
1178
1179 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1180 {
1181         unsigned long ret, flags;
1182         struct lock_list this;
1183
1184         this.parent = NULL;
1185         this.class = class;
1186
1187         local_irq_save(flags);
1188         arch_spin_lock(&lockdep_lock);
1189         ret = __lockdep_count_backward_deps(&this);
1190         arch_spin_unlock(&lockdep_lock);
1191         local_irq_restore(flags);
1192
1193         return ret;
1194 }
1195
1196 /*
1197  * Prove that the dependency graph starting at <entry> can not
1198  * lead to <target>. Print an error and return 0 if it does.
1199  */
1200 static noinline int
1201 check_noncircular(struct lock_list *root, struct lock_class *target,
1202                 struct lock_list **target_entry)
1203 {
1204         int result;
1205
1206         debug_atomic_inc(nr_cyclic_checks);
1207
1208         result = __bfs_forwards(root, target, class_equal, target_entry);
1209
1210         return result;
1211 }
1212
1213 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1214 /*
1215  * Forwards and backwards subgraph searching, for the purposes of
1216  * proving that two subgraphs can be connected by a new dependency
1217  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1218  */
1219
1220 static inline int usage_match(struct lock_list *entry, void *bit)
1221 {
1222         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1223 }
1224
1225
1226
1227 /*
1228  * Find a node in the forwards-direction dependency sub-graph starting
1229  * at @root->class that matches @bit.
1230  *
1231  * Return 0 if such a node exists in the subgraph, and put that node
1232  * into *@target_entry.
1233  *
1234  * Return 1 otherwise and keep *@target_entry unchanged.
1235  * Return <0 on error.
1236  */
1237 static int
1238 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1239                         struct lock_list **target_entry)
1240 {
1241         int result;
1242
1243         debug_atomic_inc(nr_find_usage_forwards_checks);
1244
1245         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1246
1247         return result;
1248 }
1249
1250 /*
1251  * Find a node in the backwards-direction dependency sub-graph starting
1252  * at @root->class that matches @bit.
1253  *
1254  * Return 0 if such a node exists in the subgraph, and put that node
1255  * into *@target_entry.
1256  *
1257  * Return 1 otherwise and keep *@target_entry unchanged.
1258  * Return <0 on error.
1259  */
1260 static int
1261 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1262                         struct lock_list **target_entry)
1263 {
1264         int result;
1265
1266         debug_atomic_inc(nr_find_usage_backwards_checks);
1267
1268         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1269
1270         return result;
1271 }
1272
1273 static void print_lock_class_header(struct lock_class *class, int depth)
1274 {
1275         int bit;
1276
1277         printk("%*s->", depth, "");
1278         print_lock_name(class);
1279         printk(" ops: %lu", class->ops);
1280         printk(" {\n");
1281
1282         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1283                 if (class->usage_mask & (1 << bit)) {
1284                         int len = depth;
1285
1286                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1287                         len += printk(" at:\n");
1288                         print_stack_trace(class->usage_traces + bit, len);
1289                 }
1290         }
1291         printk("%*s }\n", depth, "");
1292
1293         printk("%*s ... key      at: ",depth,"");
1294         print_ip_sym((unsigned long)class->key);
1295 }
1296
1297 /*
1298  * printk the shortest lock dependencies from @start to @end in reverse order:
1299  */
1300 static void __used
1301 print_shortest_lock_dependencies(struct lock_list *leaf,
1302                                 struct lock_list *root)
1303 {
1304         struct lock_list *entry = leaf;
1305         int depth;
1306
1307         /*compute depth from generated tree by BFS*/
1308         depth = get_lock_depth(leaf);
1309
1310         do {
1311                 print_lock_class_header(entry->class, depth);
1312                 printk("%*s ... acquired at:\n", depth, "");
1313                 print_stack_trace(&entry->trace, 2);
1314                 printk("\n");
1315
1316                 if (depth == 0 && (entry != root)) {
1317                         printk("lockdep:%s bad BFS generated tree\n", __func__);
1318                         break;
1319                 }
1320
1321                 entry = get_lock_parent(entry);
1322                 depth--;
1323         } while (entry && (depth >= 0));
1324
1325         return;
1326 }
1327
1328 static int
1329 print_bad_irq_dependency(struct task_struct *curr,
1330                          struct lock_list *prev_root,
1331                          struct lock_list *next_root,
1332                          struct lock_list *backwards_entry,
1333                          struct lock_list *forwards_entry,
1334                          struct held_lock *prev,
1335                          struct held_lock *next,
1336                          enum lock_usage_bit bit1,
1337                          enum lock_usage_bit bit2,
1338                          const char *irqclass)
1339 {
1340         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1341                 return 0;
1342
1343         printk("\n======================================================\n");
1344         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1345                 irqclass, irqclass);
1346         print_kernel_version();
1347         printk(  "------------------------------------------------------\n");
1348         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1349                 curr->comm, task_pid_nr(curr),
1350                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1351                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1352                 curr->hardirqs_enabled,
1353                 curr->softirqs_enabled);
1354         print_lock(next);
1355
1356         printk("\nand this task is already holding:\n");
1357         print_lock(prev);
1358         printk("which would create a new lock dependency:\n");
1359         print_lock_name(hlock_class(prev));
1360         printk(" ->");
1361         print_lock_name(hlock_class(next));
1362         printk("\n");
1363
1364         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1365                 irqclass);
1366         print_lock_name(backwards_entry->class);
1367         printk("\n... which became %s-irq-safe at:\n", irqclass);
1368
1369         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1370
1371         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1372         print_lock_name(forwards_entry->class);
1373         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1374         printk("...");
1375
1376         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1377
1378         printk("\nother info that might help us debug this:\n\n");
1379         lockdep_print_held_locks(curr);
1380
1381         printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1382         printk(" and the holding lock:\n");
1383         if (!save_trace(&prev_root->trace))
1384                 return 0;
1385         print_shortest_lock_dependencies(backwards_entry, prev_root);
1386
1387         printk("\nthe dependencies between the lock to be acquired");
1388         printk(" and %s-irq-unsafe lock:\n", irqclass);
1389         if (!save_trace(&next_root->trace))
1390                 return 0;
1391         print_shortest_lock_dependencies(forwards_entry, next_root);
1392
1393         printk("\nstack backtrace:\n");
1394         dump_stack();
1395
1396         return 0;
1397 }
1398
1399 static int
1400 check_usage(struct task_struct *curr, struct held_lock *prev,
1401             struct held_lock *next, enum lock_usage_bit bit_backwards,
1402             enum lock_usage_bit bit_forwards, const char *irqclass)
1403 {
1404         int ret;
1405         struct lock_list this, that;
1406         struct lock_list *uninitialized_var(target_entry);
1407         struct lock_list *uninitialized_var(target_entry1);
1408
1409         this.parent = NULL;
1410
1411         this.class = hlock_class(prev);
1412         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1413         if (ret < 0)
1414                 return print_bfs_bug(ret);
1415         if (ret == 1)
1416                 return ret;
1417
1418         that.parent = NULL;
1419         that.class = hlock_class(next);
1420         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1421         if (ret < 0)
1422                 return print_bfs_bug(ret);
1423         if (ret == 1)
1424                 return ret;
1425
1426         return print_bad_irq_dependency(curr, &this, &that,
1427                         target_entry, target_entry1,
1428                         prev, next,
1429                         bit_backwards, bit_forwards, irqclass);
1430 }
1431
1432 static const char *state_names[] = {
1433 #define LOCKDEP_STATE(__STATE) \
1434         __stringify(__STATE),
1435 #include "lockdep_states.h"
1436 #undef LOCKDEP_STATE
1437 };
1438
1439 static const char *state_rnames[] = {
1440 #define LOCKDEP_STATE(__STATE) \
1441         __stringify(__STATE)"-READ",
1442 #include "lockdep_states.h"
1443 #undef LOCKDEP_STATE
1444 };
1445
1446 static inline const char *state_name(enum lock_usage_bit bit)
1447 {
1448         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1449 }
1450
1451 static int exclusive_bit(int new_bit)
1452 {
1453         /*
1454          * USED_IN
1455          * USED_IN_READ
1456          * ENABLED
1457          * ENABLED_READ
1458          *
1459          * bit 0 - write/read
1460          * bit 1 - used_in/enabled
1461          * bit 2+  state
1462          */
1463
1464         int state = new_bit & ~3;
1465         int dir = new_bit & 2;
1466
1467         /*
1468          * keep state, bit flip the direction and strip read.
1469          */
1470         return state | (dir ^ 2);
1471 }
1472
1473 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1474                            struct held_lock *next, enum lock_usage_bit bit)
1475 {
1476         /*
1477          * Prove that the new dependency does not connect a hardirq-safe
1478          * lock with a hardirq-unsafe lock - to achieve this we search
1479          * the backwards-subgraph starting at <prev>, and the
1480          * forwards-subgraph starting at <next>:
1481          */
1482         if (!check_usage(curr, prev, next, bit,
1483                            exclusive_bit(bit), state_name(bit)))
1484                 return 0;
1485
1486         bit++; /* _READ */
1487
1488         /*
1489          * Prove that the new dependency does not connect a hardirq-safe-read
1490          * lock with a hardirq-unsafe lock - to achieve this we search
1491          * the backwards-subgraph starting at <prev>, and the
1492          * forwards-subgraph starting at <next>:
1493          */
1494         if (!check_usage(curr, prev, next, bit,
1495                            exclusive_bit(bit), state_name(bit)))
1496                 return 0;
1497
1498         return 1;
1499 }
1500
1501 static int
1502 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1503                 struct held_lock *next)
1504 {
1505 #define LOCKDEP_STATE(__STATE)                                          \
1506         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1507                 return 0;
1508 #include "lockdep_states.h"
1509 #undef LOCKDEP_STATE
1510
1511         return 1;
1512 }
1513
1514 static void inc_chains(void)
1515 {
1516         if (current->hardirq_context)
1517                 nr_hardirq_chains++;
1518         else {
1519                 if (current->softirq_context)
1520                         nr_softirq_chains++;
1521                 else
1522                         nr_process_chains++;
1523         }
1524 }
1525
1526 #else
1527
1528 static inline int
1529 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1530                 struct held_lock *next)
1531 {
1532         return 1;
1533 }
1534
1535 static inline void inc_chains(void)
1536 {
1537         nr_process_chains++;
1538 }
1539
1540 #endif
1541
1542 static int
1543 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1544                    struct held_lock *next)
1545 {
1546         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1547                 return 0;
1548
1549         printk("\n=============================================\n");
1550         printk(  "[ INFO: possible recursive locking detected ]\n");
1551         print_kernel_version();
1552         printk(  "---------------------------------------------\n");
1553         printk("%s/%d is trying to acquire lock:\n",
1554                 curr->comm, task_pid_nr(curr));
1555         print_lock(next);
1556         printk("\nbut task is already holding lock:\n");
1557         print_lock(prev);
1558
1559         printk("\nother info that might help us debug this:\n");
1560         lockdep_print_held_locks(curr);
1561
1562         printk("\nstack backtrace:\n");
1563         dump_stack();
1564
1565         return 0;
1566 }
1567
1568 /*
1569  * Check whether we are holding such a class already.
1570  *
1571  * (Note that this has to be done separately, because the graph cannot
1572  * detect such classes of deadlocks.)
1573  *
1574  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1575  */
1576 static int
1577 check_deadlock(struct task_struct *curr, struct held_lock *next,
1578                struct lockdep_map *next_instance, int read)
1579 {
1580         struct held_lock *prev;
1581         struct held_lock *nest = NULL;
1582         int i;
1583
1584         for (i = 0; i < curr->lockdep_depth; i++) {
1585                 prev = curr->held_locks + i;
1586
1587                 if (prev->instance == next->nest_lock)
1588                         nest = prev;
1589
1590                 if (hlock_class(prev) != hlock_class(next))
1591                         continue;
1592
1593                 /*
1594                  * Allow read-after-read recursion of the same
1595                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1596                  */
1597                 if ((read == 2) && prev->read)
1598                         return 2;
1599
1600                 /*
1601                  * We're holding the nest_lock, which serializes this lock's
1602                  * nesting behaviour.
1603                  */
1604                 if (nest)
1605                         return 2;
1606
1607                 return print_deadlock_bug(curr, prev, next);
1608         }
1609         return 1;
1610 }
1611
1612 /*
1613  * There was a chain-cache miss, and we are about to add a new dependency
1614  * to a previous lock. We recursively validate the following rules:
1615  *
1616  *  - would the adding of the <prev> -> <next> dependency create a
1617  *    circular dependency in the graph? [== circular deadlock]
1618  *
1619  *  - does the new prev->next dependency connect any hardirq-safe lock
1620  *    (in the full backwards-subgraph starting at <prev>) with any
1621  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1622  *    <next>)? [== illegal lock inversion with hardirq contexts]
1623  *
1624  *  - does the new prev->next dependency connect any softirq-safe lock
1625  *    (in the full backwards-subgraph starting at <prev>) with any
1626  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1627  *    <next>)? [== illegal lock inversion with softirq contexts]
1628  *
1629  * any of these scenarios could lead to a deadlock.
1630  *
1631  * Then if all the validations pass, we add the forwards and backwards
1632  * dependency.
1633  */
1634 static int
1635 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1636                struct held_lock *next, int distance, int trylock_loop)
1637 {
1638         struct lock_list *entry;
1639         int ret;
1640         struct lock_list this;
1641         struct lock_list *uninitialized_var(target_entry);
1642         /*
1643          * Static variable, serialized by the graph_lock().
1644          *
1645          * We use this static variable to save the stack trace in case
1646          * we call into this function multiple times due to encountering
1647          * trylocks in the held lock stack.
1648          */
1649         static struct stack_trace trace;
1650
1651         /*
1652          * Prove that the new <prev> -> <next> dependency would not
1653          * create a circular dependency in the graph. (We do this by
1654          * forward-recursing into the graph starting at <next>, and
1655          * checking whether we can reach <prev>.)
1656          *
1657          * We are using global variables to control the recursion, to
1658          * keep the stackframe size of the recursive functions low:
1659          */
1660         this.class = hlock_class(next);
1661         this.parent = NULL;
1662         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1663         if (unlikely(!ret))
1664                 return print_circular_bug(&this, target_entry, next, prev);
1665         else if (unlikely(ret < 0))
1666                 return print_bfs_bug(ret);
1667
1668         if (!check_prev_add_irq(curr, prev, next))
1669                 return 0;
1670
1671         /*
1672          * For recursive read-locks we do all the dependency checks,
1673          * but we dont store read-triggered dependencies (only
1674          * write-triggered dependencies). This ensures that only the
1675          * write-side dependencies matter, and that if for example a
1676          * write-lock never takes any other locks, then the reads are
1677          * equivalent to a NOP.
1678          */
1679         if (next->read == 2 || prev->read == 2)
1680                 return 1;
1681         /*
1682          * Is the <prev> -> <next> dependency already present?
1683          *
1684          * (this may occur even though this is a new chain: consider
1685          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1686          *  chains - the second one will be new, but L1 already has
1687          *  L2 added to its dependency list, due to the first chain.)
1688          */
1689         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1690                 if (entry->class == hlock_class(next)) {
1691                         if (distance == 1)
1692                                 entry->distance = 1;
1693                         return 2;
1694                 }
1695         }
1696
1697         if (!trylock_loop && !save_trace(&trace))
1698                 return 0;
1699
1700         /*
1701          * Ok, all validations passed, add the new lock
1702          * to the previous lock's dependency list:
1703          */
1704         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1705                                &hlock_class(prev)->locks_after,
1706                                next->acquire_ip, distance, &trace);
1707
1708         if (!ret)
1709                 return 0;
1710
1711         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1712                                &hlock_class(next)->locks_before,
1713                                next->acquire_ip, distance, &trace);
1714         if (!ret)
1715                 return 0;
1716
1717         /*
1718          * Debugging printouts:
1719          */
1720         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1721                 graph_unlock();
1722                 printk("\n new dependency: ");
1723                 print_lock_name(hlock_class(prev));
1724                 printk(" => ");
1725                 print_lock_name(hlock_class(next));
1726                 printk("\n");
1727                 dump_stack();
1728                 return graph_lock();
1729         }
1730         return 1;
1731 }
1732
1733 /*
1734  * Add the dependency to all directly-previous locks that are 'relevant'.
1735  * The ones that are relevant are (in increasing distance from curr):
1736  * all consecutive trylock entries and the final non-trylock entry - or
1737  * the end of this context's lock-chain - whichever comes first.
1738  */
1739 static int
1740 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1741 {
1742         int depth = curr->lockdep_depth;
1743         int trylock_loop = 0;
1744         struct held_lock *hlock;
1745
1746         /*
1747          * Debugging checks.
1748          *
1749          * Depth must not be zero for a non-head lock:
1750          */
1751         if (!depth)
1752                 goto out_bug;
1753         /*
1754          * At least two relevant locks must exist for this
1755          * to be a head:
1756          */
1757         if (curr->held_locks[depth].irq_context !=
1758                         curr->held_locks[depth-1].irq_context)
1759                 goto out_bug;
1760
1761         for (;;) {
1762                 int distance = curr->lockdep_depth - depth + 1;
1763                 hlock = curr->held_locks + depth-1;
1764                 /*
1765                  * Only non-recursive-read entries get new dependencies
1766                  * added:
1767                  */
1768                 if (hlock->read != 2) {
1769                         if (!check_prev_add(curr, hlock, next,
1770                                                 distance, trylock_loop))
1771                                 return 0;
1772                         /*
1773                          * Stop after the first non-trylock entry,
1774                          * as non-trylock entries have added their
1775                          * own direct dependencies already, so this
1776                          * lock is connected to them indirectly:
1777                          */
1778                         if (!hlock->trylock)
1779                                 break;
1780                 }
1781                 depth--;
1782                 /*
1783                  * End of lock-stack?
1784                  */
1785                 if (!depth)
1786                         break;
1787                 /*
1788                  * Stop the search if we cross into another context:
1789                  */
1790                 if (curr->held_locks[depth].irq_context !=
1791                                 curr->held_locks[depth-1].irq_context)
1792                         break;
1793                 trylock_loop = 1;
1794         }
1795         return 1;
1796 out_bug:
1797         if (!debug_locks_off_graph_unlock())
1798                 return 0;
1799
1800         WARN_ON(1);
1801
1802         return 0;
1803 }
1804
1805 unsigned long nr_lock_chains;
1806 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1807 int nr_chain_hlocks;
1808 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1809
1810 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1811 {
1812         return lock_classes + chain_hlocks[chain->base + i];
1813 }
1814
1815 /*
1816  * Look up a dependency chain. If the key is not present yet then
1817  * add it and return 1 - in this case the new dependency chain is
1818  * validated. If the key is already hashed, return 0.
1819  * (On return with 1 graph_lock is held.)
1820  */
1821 static inline int lookup_chain_cache(struct task_struct *curr,
1822                                      struct held_lock *hlock,
1823                                      u64 chain_key)
1824 {
1825         struct lock_class *class = hlock_class(hlock);
1826         struct list_head *hash_head = chainhashentry(chain_key);
1827         struct lock_chain *chain;
1828         struct held_lock *hlock_curr, *hlock_next;
1829         int i, j, n, cn;
1830
1831         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1832                 return 0;
1833         /*
1834          * We can walk it lock-free, because entries only get added
1835          * to the hash:
1836          */
1837         list_for_each_entry(chain, hash_head, entry) {
1838                 if (chain->chain_key == chain_key) {
1839 cache_hit:
1840                         debug_atomic_inc(chain_lookup_hits);
1841                         if (very_verbose(class))
1842                                 printk("\nhash chain already cached, key: "
1843                                         "%016Lx tail class: [%p] %s\n",
1844                                         (unsigned long long)chain_key,
1845                                         class->key, class->name);
1846                         return 0;
1847                 }
1848         }
1849         if (very_verbose(class))
1850                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1851                         (unsigned long long)chain_key, class->key, class->name);
1852         /*
1853          * Allocate a new chain entry from the static array, and add
1854          * it to the hash:
1855          */
1856         if (!graph_lock())
1857                 return 0;
1858         /*
1859          * We have to walk the chain again locked - to avoid duplicates:
1860          */
1861         list_for_each_entry(chain, hash_head, entry) {
1862                 if (chain->chain_key == chain_key) {
1863                         graph_unlock();
1864                         goto cache_hit;
1865                 }
1866         }
1867         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1868                 if (!debug_locks_off_graph_unlock())
1869                         return 0;
1870
1871                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1872                 printk("turning off the locking correctness validator.\n");
1873                 dump_stack();
1874                 return 0;
1875         }
1876         chain = lock_chains + nr_lock_chains++;
1877         chain->chain_key = chain_key;
1878         chain->irq_context = hlock->irq_context;
1879         /* Find the first held_lock of current chain */
1880         hlock_next = hlock;
1881         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1882                 hlock_curr = curr->held_locks + i;
1883                 if (hlock_curr->irq_context != hlock_next->irq_context)
1884                         break;
1885                 hlock_next = hlock;
1886         }
1887         i++;
1888         chain->depth = curr->lockdep_depth + 1 - i;
1889         cn = nr_chain_hlocks;
1890         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1891                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1892                 if (n == cn)
1893                         break;
1894                 cn = n;
1895         }
1896         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1897                 chain->base = cn;
1898                 for (j = 0; j < chain->depth - 1; j++, i++) {
1899                         int lock_id = curr->held_locks[i].class_idx - 1;
1900                         chain_hlocks[chain->base + j] = lock_id;
1901                 }
1902                 chain_hlocks[chain->base + j] = class - lock_classes;
1903         }
1904         list_add_tail_rcu(&chain->entry, hash_head);
1905         debug_atomic_inc(chain_lookup_misses);
1906         inc_chains();
1907
1908         return 1;
1909 }
1910
1911 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1912                 struct held_lock *hlock, int chain_head, u64 chain_key)
1913 {
1914         /*
1915          * Trylock needs to maintain the stack of held locks, but it
1916          * does not add new dependencies, because trylock can be done
1917          * in any order.
1918          *
1919          * We look up the chain_key and do the O(N^2) check and update of
1920          * the dependencies only if this is a new dependency chain.
1921          * (If lookup_chain_cache() returns with 1 it acquires
1922          * graph_lock for us)
1923          */
1924         if (!hlock->trylock && (hlock->check == 2) &&
1925             lookup_chain_cache(curr, hlock, chain_key)) {
1926                 /*
1927                  * Check whether last held lock:
1928                  *
1929                  * - is irq-safe, if this lock is irq-unsafe
1930                  * - is softirq-safe, if this lock is hardirq-unsafe
1931                  *
1932                  * And check whether the new lock's dependency graph
1933                  * could lead back to the previous lock.
1934                  *
1935                  * any of these scenarios could lead to a deadlock. If
1936                  * All validations
1937                  */
1938                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1939
1940                 if (!ret)
1941                         return 0;
1942                 /*
1943                  * Mark recursive read, as we jump over it when
1944                  * building dependencies (just like we jump over
1945                  * trylock entries):
1946                  */
1947                 if (ret == 2)
1948                         hlock->read = 2;
1949                 /*
1950                  * Add dependency only if this lock is not the head
1951                  * of the chain, and if it's not a secondary read-lock:
1952                  */
1953                 if (!chain_head && ret != 2)
1954                         if (!check_prevs_add(curr, hlock))
1955                                 return 0;
1956                 graph_unlock();
1957         } else
1958                 /* after lookup_chain_cache(): */
1959                 if (unlikely(!debug_locks))
1960                         return 0;
1961
1962         return 1;
1963 }
1964 #else
1965 static inline int validate_chain(struct task_struct *curr,
1966                 struct lockdep_map *lock, struct held_lock *hlock,
1967                 int chain_head, u64 chain_key)
1968 {
1969         return 1;
1970 }
1971 #endif
1972
1973 /*
1974  * We are building curr_chain_key incrementally, so double-check
1975  * it from scratch, to make sure that it's done correctly:
1976  */
1977 static void check_chain_key(struct task_struct *curr)
1978 {
1979 #ifdef CONFIG_DEBUG_LOCKDEP
1980         struct held_lock *hlock, *prev_hlock = NULL;
1981         unsigned int i, id;
1982         u64 chain_key = 0;
1983
1984         for (i = 0; i < curr->lockdep_depth; i++) {
1985                 hlock = curr->held_locks + i;
1986                 if (chain_key != hlock->prev_chain_key) {
1987                         debug_locks_off();
1988                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1989                                 curr->lockdep_depth, i,
1990                                 (unsigned long long)chain_key,
1991                                 (unsigned long long)hlock->prev_chain_key);
1992                         return;
1993                 }
1994                 id = hlock->class_idx - 1;
1995                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1996                         return;
1997
1998                 if (prev_hlock && (prev_hlock->irq_context !=
1999                                                         hlock->irq_context))
2000                         chain_key = 0;
2001                 chain_key = iterate_chain_key(chain_key, id);
2002                 prev_hlock = hlock;
2003         }
2004         if (chain_key != curr->curr_chain_key) {
2005                 debug_locks_off();
2006                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2007                         curr->lockdep_depth, i,
2008                         (unsigned long long)chain_key,
2009                         (unsigned long long)curr->curr_chain_key);
2010         }
2011 #endif
2012 }
2013
2014 static int
2015 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2016                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2017 {
2018         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2019                 return 0;
2020
2021         printk("\n=================================\n");
2022         printk(  "[ INFO: inconsistent lock state ]\n");
2023         print_kernel_version();
2024         printk(  "---------------------------------\n");
2025
2026         printk("inconsistent {%s} -> {%s} usage.\n",
2027                 usage_str[prev_bit], usage_str[new_bit]);
2028
2029         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2030                 curr->comm, task_pid_nr(curr),
2031                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2032                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2033                 trace_hardirqs_enabled(curr),
2034                 trace_softirqs_enabled(curr));
2035         print_lock(this);
2036
2037         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2038         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2039
2040         print_irqtrace_events(curr);
2041         printk("\nother info that might help us debug this:\n");
2042         lockdep_print_held_locks(curr);
2043
2044         printk("\nstack backtrace:\n");
2045         dump_stack();
2046
2047         return 0;
2048 }
2049
2050 /*
2051  * Print out an error if an invalid bit is set:
2052  */
2053 static inline int
2054 valid_state(struct task_struct *curr, struct held_lock *this,
2055             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2056 {
2057         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2058                 return print_usage_bug(curr, this, bad_bit, new_bit);
2059         return 1;
2060 }
2061
2062 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2063                      enum lock_usage_bit new_bit);
2064
2065 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2066
2067 /*
2068  * print irq inversion bug:
2069  */
2070 static int
2071 print_irq_inversion_bug(struct task_struct *curr,
2072                         struct lock_list *root, struct lock_list *other,
2073                         struct held_lock *this, int forwards,
2074                         const char *irqclass)
2075 {
2076         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2077                 return 0;
2078
2079         printk("\n=========================================================\n");
2080         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2081         print_kernel_version();
2082         printk(  "---------------------------------------------------------\n");
2083         printk("%s/%d just changed the state of lock:\n",
2084                 curr->comm, task_pid_nr(curr));
2085         print_lock(this);
2086         if (forwards)
2087                 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2088         else
2089                 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2090         print_lock_name(other->class);
2091         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2092
2093         printk("\nother info that might help us debug this:\n");
2094         lockdep_print_held_locks(curr);
2095
2096         printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2097         if (!save_trace(&root->trace))
2098                 return 0;
2099         print_shortest_lock_dependencies(other, root);
2100
2101         printk("\nstack backtrace:\n");
2102         dump_stack();
2103
2104         return 0;
2105 }
2106
2107 /*
2108  * Prove that in the forwards-direction subgraph starting at <this>
2109  * there is no lock matching <mask>:
2110  */
2111 static int
2112 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2113                      enum lock_usage_bit bit, const char *irqclass)
2114 {
2115         int ret;
2116         struct lock_list root;
2117         struct lock_list *uninitialized_var(target_entry);
2118
2119         root.parent = NULL;
2120         root.class = hlock_class(this);
2121         ret = find_usage_forwards(&root, bit, &target_entry);
2122         if (ret < 0)
2123                 return print_bfs_bug(ret);
2124         if (ret == 1)
2125                 return ret;
2126
2127         return print_irq_inversion_bug(curr, &root, target_entry,
2128                                         this, 1, irqclass);
2129 }
2130
2131 /*
2132  * Prove that in the backwards-direction subgraph starting at <this>
2133  * there is no lock matching <mask>:
2134  */
2135 static int
2136 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2137                       enum lock_usage_bit bit, const char *irqclass)
2138 {
2139         int ret;
2140         struct lock_list root;
2141         struct lock_list *uninitialized_var(target_entry);
2142
2143         root.parent = NULL;
2144         root.class = hlock_class(this);
2145         ret = find_usage_backwards(&root, bit, &target_entry);
2146         if (ret < 0)
2147                 return print_bfs_bug(ret);
2148         if (ret == 1)
2149                 return ret;
2150
2151         return print_irq_inversion_bug(curr, &root, target_entry,
2152                                         this, 0, irqclass);
2153 }
2154
2155 void print_irqtrace_events(struct task_struct *curr)
2156 {
2157         printk("irq event stamp: %u\n", curr->irq_events);
2158         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2159         print_ip_sym(curr->hardirq_enable_ip);
2160         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2161         print_ip_sym(curr->hardirq_disable_ip);
2162         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2163         print_ip_sym(curr->softirq_enable_ip);
2164         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2165         print_ip_sym(curr->softirq_disable_ip);
2166 }
2167
2168 static int HARDIRQ_verbose(struct lock_class *class)
2169 {
2170 #if HARDIRQ_VERBOSE
2171         return class_filter(class);
2172 #endif
2173         return 0;
2174 }
2175
2176 static int SOFTIRQ_verbose(struct lock_class *class)
2177 {
2178 #if SOFTIRQ_VERBOSE
2179         return class_filter(class);
2180 #endif
2181         return 0;
2182 }
2183
2184 static int RECLAIM_FS_verbose(struct lock_class *class)
2185 {
2186 #if RECLAIM_VERBOSE
2187         return class_filter(class);
2188 #endif
2189         return 0;
2190 }
2191
2192 #define STRICT_READ_CHECKS      1
2193
2194 static int (*state_verbose_f[])(struct lock_class *class) = {
2195 #define LOCKDEP_STATE(__STATE) \
2196         __STATE##_verbose,
2197 #include "lockdep_states.h"
2198 #undef LOCKDEP_STATE
2199 };
2200
2201 static inline int state_verbose(enum lock_usage_bit bit,
2202                                 struct lock_class *class)
2203 {
2204         return state_verbose_f[bit >> 2](class);
2205 }
2206
2207 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2208                              enum lock_usage_bit bit, const char *name);
2209
2210 static int
2211 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2212                 enum lock_usage_bit new_bit)
2213 {
2214         int excl_bit = exclusive_bit(new_bit);
2215         int read = new_bit & 1;
2216         int dir = new_bit & 2;
2217
2218         /*
2219          * mark USED_IN has to look forwards -- to ensure no dependency
2220          * has ENABLED state, which would allow recursion deadlocks.
2221          *
2222          * mark ENABLED has to look backwards -- to ensure no dependee
2223          * has USED_IN state, which, again, would allow  recursion deadlocks.
2224          */
2225         check_usage_f usage = dir ?
2226                 check_usage_backwards : check_usage_forwards;
2227
2228         /*
2229          * Validate that this particular lock does not have conflicting
2230          * usage states.
2231          */
2232         if (!valid_state(curr, this, new_bit, excl_bit))
2233                 return 0;
2234
2235         /*
2236          * Validate that the lock dependencies don't have conflicting usage
2237          * states.
2238          */
2239         if ((!read || !dir || STRICT_READ_CHECKS) &&
2240                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2241                 return 0;
2242
2243         /*
2244          * Check for read in write conflicts
2245          */
2246         if (!read) {
2247                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2248                         return 0;
2249
2250                 if (STRICT_READ_CHECKS &&
2251                         !usage(curr, this, excl_bit + 1,
2252                                 state_name(new_bit + 1)))
2253                         return 0;
2254         }
2255
2256         if (state_verbose(new_bit, hlock_class(this)))
2257                 return 2;
2258
2259         return 1;
2260 }
2261
2262 enum mark_type {
2263 #define LOCKDEP_STATE(__STATE)  __STATE,
2264 #include "lockdep_states.h"
2265 #undef LOCKDEP_STATE
2266 };
2267
2268 /*
2269  * Mark all held locks with a usage bit:
2270  */
2271 static int
2272 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2273 {
2274         enum lock_usage_bit usage_bit;
2275         struct held_lock *hlock;
2276         int i;
2277
2278         for (i = 0; i < curr->lockdep_depth; i++) {
2279                 hlock = curr->held_locks + i;
2280
2281                 usage_bit = 2 + (mark << 2); /* ENABLED */
2282                 if (hlock->read)
2283                         usage_bit += 1; /* READ */
2284
2285                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2286
2287                 if (!mark_lock(curr, hlock, usage_bit))
2288                         return 0;
2289         }
2290
2291         return 1;
2292 }
2293
2294 /*
2295  * Debugging helper: via this flag we know that we are in
2296  * 'early bootup code', and will warn about any invalid irqs-on event:
2297  */
2298 static int early_boot_irqs_enabled;
2299
2300 void early_boot_irqs_off(void)
2301 {
2302         early_boot_irqs_enabled = 0;
2303 }
2304
2305 void early_boot_irqs_on(void)
2306 {
2307         early_boot_irqs_enabled = 1;
2308 }
2309
2310 /*
2311  * Hardirqs will be enabled:
2312  */
2313 void trace_hardirqs_on_caller(unsigned long ip)
2314 {
2315         struct task_struct *curr = current;
2316
2317         time_hardirqs_on(CALLER_ADDR0, ip);
2318
2319         if (unlikely(!debug_locks || current->lockdep_recursion))
2320                 return;
2321
2322         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2323                 return;
2324
2325         if (unlikely(curr->hardirqs_enabled)) {
2326                 /*
2327                  * Neither irq nor preemption are disabled here
2328                  * so this is racy by nature but loosing one hit
2329                  * in a stat is not a big deal.
2330                  */
2331                 __debug_atomic_inc(redundant_hardirqs_on);
2332                 return;
2333         }
2334         /* we'll do an OFF -> ON transition: */
2335         curr->hardirqs_enabled = 1;
2336
2337         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2338                 return;
2339         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2340                 return;
2341         /*
2342          * We are going to turn hardirqs on, so set the
2343          * usage bit for all held locks:
2344          */
2345         if (!mark_held_locks(curr, HARDIRQ))
2346                 return;
2347         /*
2348          * If we have softirqs enabled, then set the usage
2349          * bit for all held locks. (disabled hardirqs prevented
2350          * this bit from being set before)
2351          */
2352         if (curr->softirqs_enabled)
2353                 if (!mark_held_locks(curr, SOFTIRQ))
2354                         return;
2355
2356         curr->hardirq_enable_ip = ip;
2357         curr->hardirq_enable_event = ++curr->irq_events;
2358         debug_atomic_inc(hardirqs_on_events);
2359 }
2360 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2361
2362 void trace_hardirqs_on(void)
2363 {
2364         trace_hardirqs_on_caller(CALLER_ADDR0);
2365 }
2366 EXPORT_SYMBOL(trace_hardirqs_on);
2367
2368 /*
2369  * Hardirqs were disabled:
2370  */
2371 void trace_hardirqs_off_caller(unsigned long ip)
2372 {
2373         struct task_struct *curr = current;
2374
2375         time_hardirqs_off(CALLER_ADDR0, ip);
2376
2377         if (unlikely(!debug_locks || current->lockdep_recursion))
2378                 return;
2379
2380         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2381                 return;
2382
2383         if (curr->hardirqs_enabled) {
2384                 /*
2385                  * We have done an ON -> OFF transition:
2386                  */
2387                 curr->hardirqs_enabled = 0;
2388                 curr->hardirq_disable_ip = ip;
2389                 curr->hardirq_disable_event = ++curr->irq_events;
2390                 debug_atomic_inc(hardirqs_off_events);
2391         } else
2392                 debug_atomic_inc(redundant_hardirqs_off);
2393 }
2394 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2395
2396 void trace_hardirqs_off(void)
2397 {
2398         trace_hardirqs_off_caller(CALLER_ADDR0);
2399 }
2400 EXPORT_SYMBOL(trace_hardirqs_off);
2401
2402 /*
2403  * Softirqs will be enabled:
2404  */
2405 void trace_softirqs_on(unsigned long ip)
2406 {
2407         struct task_struct *curr = current;
2408
2409         if (unlikely(!debug_locks))
2410                 return;
2411
2412         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2413                 return;
2414
2415         if (curr->softirqs_enabled) {
2416                 debug_atomic_inc(redundant_softirqs_on);
2417                 return;
2418         }
2419
2420         /*
2421          * We'll do an OFF -> ON transition:
2422          */
2423         curr->softirqs_enabled = 1;
2424         curr->softirq_enable_ip = ip;
2425         curr->softirq_enable_event = ++curr->irq_events;
2426         debug_atomic_inc(softirqs_on_events);
2427         /*
2428          * We are going to turn softirqs on, so set the
2429          * usage bit for all held locks, if hardirqs are
2430          * enabled too:
2431          */
2432         if (curr->hardirqs_enabled)
2433                 mark_held_locks(curr, SOFTIRQ);
2434 }
2435
2436 /*
2437  * Softirqs were disabled:
2438  */
2439 void trace_softirqs_off(unsigned long ip)
2440 {
2441         struct task_struct *curr = current;
2442
2443         if (unlikely(!debug_locks))
2444                 return;
2445
2446         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2447                 return;
2448
2449         if (curr->softirqs_enabled) {
2450                 /*
2451                  * We have done an ON -> OFF transition:
2452                  */
2453                 curr->softirqs_enabled = 0;
2454                 curr->softirq_disable_ip = ip;
2455                 curr->softirq_disable_event = ++curr->irq_events;
2456                 debug_atomic_inc(softirqs_off_events);
2457                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2458         } else
2459                 debug_atomic_inc(redundant_softirqs_off);
2460 }
2461
2462 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2463 {
2464         struct task_struct *curr = current;
2465
2466         if (unlikely(!debug_locks))
2467                 return;
2468
2469         /* no reclaim without waiting on it */
2470         if (!(gfp_mask & __GFP_WAIT))
2471                 return;
2472
2473         /* this guy won't enter reclaim */
2474         if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2475                 return;
2476
2477         /* We're only interested __GFP_FS allocations for now */
2478         if (!(gfp_mask & __GFP_FS))
2479                 return;
2480
2481         if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2482                 return;
2483
2484         mark_held_locks(curr, RECLAIM_FS);
2485 }
2486
2487 static void check_flags(unsigned long flags);
2488
2489 void lockdep_trace_alloc(gfp_t gfp_mask)
2490 {
2491         unsigned long flags;
2492
2493         if (unlikely(current->lockdep_recursion))
2494                 return;
2495
2496         raw_local_irq_save(flags);
2497         check_flags(flags);
2498         current->lockdep_recursion = 1;
2499         __lockdep_trace_alloc(gfp_mask, flags);
2500         current->lockdep_recursion = 0;
2501         raw_local_irq_restore(flags);
2502 }
2503
2504 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2505 {
2506         /*
2507          * If non-trylock use in a hardirq or softirq context, then
2508          * mark the lock as used in these contexts:
2509          */
2510         if (!hlock->trylock) {
2511                 if (hlock->read) {
2512                         if (curr->hardirq_context)
2513                                 if (!mark_lock(curr, hlock,
2514                                                 LOCK_USED_IN_HARDIRQ_READ))
2515                                         return 0;
2516                         if (curr->softirq_context)
2517                                 if (!mark_lock(curr, hlock,
2518                                                 LOCK_USED_IN_SOFTIRQ_READ))
2519                                         return 0;
2520                 } else {
2521                         if (curr->hardirq_context)
2522                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2523                                         return 0;
2524                         if (curr->softirq_context)
2525                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2526                                         return 0;
2527                 }
2528         }
2529         if (!hlock->hardirqs_off) {
2530                 if (hlock->read) {
2531                         if (!mark_lock(curr, hlock,
2532                                         LOCK_ENABLED_HARDIRQ_READ))
2533                                 return 0;
2534                         if (curr->softirqs_enabled)
2535                                 if (!mark_lock(curr, hlock,
2536                                                 LOCK_ENABLED_SOFTIRQ_READ))
2537                                         return 0;
2538                 } else {
2539                         if (!mark_lock(curr, hlock,
2540                                         LOCK_ENABLED_HARDIRQ))
2541                                 return 0;
2542                         if (curr->softirqs_enabled)
2543                                 if (!mark_lock(curr, hlock,
2544                                                 LOCK_ENABLED_SOFTIRQ))
2545                                         return 0;
2546                 }
2547         }
2548
2549         /*
2550          * We reuse the irq context infrastructure more broadly as a general
2551          * context checking code. This tests GFP_FS recursion (a lock taken
2552          * during reclaim for a GFP_FS allocation is held over a GFP_FS
2553          * allocation).
2554          */
2555         if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2556                 if (hlock->read) {
2557                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2558                                         return 0;
2559                 } else {
2560                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2561                                         return 0;
2562                 }
2563         }
2564
2565         return 1;
2566 }
2567
2568 static int separate_irq_context(struct task_struct *curr,
2569                 struct held_lock *hlock)
2570 {
2571         unsigned int depth = curr->lockdep_depth;
2572
2573         /*
2574          * Keep track of points where we cross into an interrupt context:
2575          */
2576         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2577                                 curr->softirq_context;
2578         if (depth) {
2579                 struct held_lock *prev_hlock;
2580
2581                 prev_hlock = curr->held_locks + depth-1;
2582                 /*
2583                  * If we cross into another context, reset the
2584                  * hash key (this also prevents the checking and the
2585                  * adding of the dependency to 'prev'):
2586                  */
2587                 if (prev_hlock->irq_context != hlock->irq_context)
2588                         return 1;
2589         }
2590         return 0;
2591 }
2592
2593 #else
2594
2595 static inline
2596 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2597                 enum lock_usage_bit new_bit)
2598 {
2599         WARN_ON(1);
2600         return 1;
2601 }
2602
2603 static inline int mark_irqflags(struct task_struct *curr,
2604                 struct held_lock *hlock)
2605 {
2606         return 1;
2607 }
2608
2609 static inline int separate_irq_context(struct task_struct *curr,
2610                 struct held_lock *hlock)
2611 {
2612         return 0;
2613 }
2614
2615 void lockdep_trace_alloc(gfp_t gfp_mask)
2616 {
2617 }
2618
2619 #endif
2620
2621 /*
2622  * Mark a lock with a usage bit, and validate the state transition:
2623  */
2624 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2625                              enum lock_usage_bit new_bit)
2626 {
2627         unsigned int new_mask = 1 << new_bit, ret = 1;
2628
2629         /*
2630          * If already set then do not dirty the cacheline,
2631          * nor do any checks:
2632          */
2633         if (likely(hlock_class(this)->usage_mask & new_mask))
2634                 return 1;
2635
2636         if (!graph_lock())
2637                 return 0;
2638         /*
2639          * Make sure we didnt race:
2640          */
2641         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2642                 graph_unlock();
2643                 return 1;
2644         }
2645
2646         hlock_class(this)->usage_mask |= new_mask;
2647
2648         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2649                 return 0;
2650
2651         switch (new_bit) {
2652 #define LOCKDEP_STATE(__STATE)                  \
2653         case LOCK_USED_IN_##__STATE:            \
2654         case LOCK_USED_IN_##__STATE##_READ:     \
2655         case LOCK_ENABLED_##__STATE:            \
2656         case LOCK_ENABLED_##__STATE##_READ:
2657 #include "lockdep_states.h"
2658 #undef LOCKDEP_STATE
2659                 ret = mark_lock_irq(curr, this, new_bit);
2660                 if (!ret)
2661                         return 0;
2662                 break;
2663         case LOCK_USED:
2664                 debug_atomic_dec(nr_unused_locks);
2665                 break;
2666         default:
2667                 if (!debug_locks_off_graph_unlock())
2668                         return 0;
2669                 WARN_ON(1);
2670                 return 0;
2671         }
2672
2673         graph_unlock();
2674
2675         /*
2676          * We must printk outside of the graph_lock:
2677          */
2678         if (ret == 2) {
2679                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2680                 print_lock(this);
2681                 print_irqtrace_events(curr);
2682                 dump_stack();
2683         }
2684
2685         return ret;
2686 }
2687
2688 /*
2689  * Initialize a lock instance's lock-class mapping info:
2690  */
2691 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2692                       struct lock_class_key *key, int subclass)
2693 {
2694         int i;
2695
2696         for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2697                 lock->class_cache[i] = NULL;
2698
2699 #ifdef CONFIG_LOCK_STAT
2700         lock->cpu = raw_smp_processor_id();
2701 #endif
2702
2703         if (DEBUG_LOCKS_WARN_ON(!name)) {
2704                 lock->name = "NULL";
2705                 return;
2706         }
2707
2708         lock->name = name;
2709
2710         if (DEBUG_LOCKS_WARN_ON(!key))
2711                 return;
2712         /*
2713          * Sanity check, the lock-class key must be persistent:
2714          */
2715         if (!static_obj(key)) {
2716                 printk("BUG: key %p not in .data!\n", key);
2717                 DEBUG_LOCKS_WARN_ON(1);
2718                 return;
2719         }
2720         lock->key = key;
2721
2722         if (unlikely(!debug_locks))
2723                 return;
2724
2725         if (subclass)
2726                 register_lock_class(lock, subclass, 1);
2727 }
2728 EXPORT_SYMBOL_GPL(lockdep_init_map);
2729
2730 struct lock_class_key __lockdep_no_validate__;
2731
2732 /*
2733  * This gets called for every mutex_lock*()/spin_lock*() operation.
2734  * We maintain the dependency maps and validate the locking attempt:
2735  */
2736 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2737                           int trylock, int read, int check, int hardirqs_off,
2738                           struct lockdep_map *nest_lock, unsigned long ip,
2739                           int references)
2740 {
2741         struct task_struct *curr = current;
2742         struct lock_class *class = NULL;
2743         struct held_lock *hlock;
2744         unsigned int depth, id;
2745         int chain_head = 0;
2746         int class_idx;
2747         u64 chain_key;
2748
2749         if (!prove_locking)
2750                 check = 1;
2751
2752         if (unlikely(!debug_locks))
2753                 return 0;
2754
2755         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2756                 return 0;
2757
2758         if (lock->key == &__lockdep_no_validate__)
2759                 check = 1;
2760
2761         if (subclass < NR_LOCKDEP_CACHING_CLASSES)
2762                 class = lock->class_cache[subclass];
2763         /*
2764          * Not cached?
2765          */
2766         if (unlikely(!class)) {
2767                 class = register_lock_class(lock, subclass, 0);
2768                 if (!class)
2769                         return 0;
2770         }
2771         atomic_inc((atomic_t *)&class->ops);
2772         if (very_verbose(class)) {
2773                 printk("\nacquire class [%p] %s", class->key, class->name);
2774                 if (class->name_version > 1)
2775                         printk("#%d", class->name_version);
2776                 printk("\n");
2777                 dump_stack();
2778         }
2779
2780         /*
2781          * Add the lock to the list of currently held locks.
2782          * (we dont increase the depth just yet, up until the
2783          * dependency checks are done)
2784          */
2785         depth = curr->lockdep_depth;
2786         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2787                 return 0;
2788
2789         class_idx = class - lock_classes + 1;
2790
2791         if (depth) {
2792                 hlock = curr->held_locks + depth - 1;
2793                 if (hlock->class_idx == class_idx && nest_lock) {
2794                         if (hlock->references)
2795                                 hlock->references++;
2796                         else
2797                                 hlock->references = 2;
2798
2799                         return 1;
2800                 }
2801         }
2802
2803         hlock = curr->held_locks + depth;
2804         if (DEBUG_LOCKS_WARN_ON(!class))
2805                 return 0;
2806         hlock->class_idx = class_idx;
2807         hlock->acquire_ip = ip;
2808         hlock->instance = lock;
2809         hlock->nest_lock = nest_lock;
2810         hlock->trylock = trylock;
2811         hlock->read = read;
2812         hlock->check = check;
2813         hlock->hardirqs_off = !!hardirqs_off;
2814         hlock->references = references;
2815 #ifdef CONFIG_LOCK_STAT
2816         hlock->waittime_stamp = 0;
2817         hlock->holdtime_stamp = lockstat_clock();
2818 #endif
2819
2820         if (check == 2 && !mark_irqflags(curr, hlock))
2821                 return 0;
2822
2823         /* mark it as used: */
2824         if (!mark_lock(curr, hlock, LOCK_USED))
2825                 return 0;
2826
2827         /*
2828          * Calculate the chain hash: it's the combined hash of all the
2829          * lock keys along the dependency chain. We save the hash value
2830          * at every step so that we can get the current hash easily
2831          * after unlock. The chain hash is then used to cache dependency
2832          * results.
2833          *
2834          * The 'key ID' is what is the most compact key value to drive
2835          * the hash, not class->key.
2836          */
2837         id = class - lock_classes;
2838         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2839                 return 0;
2840
2841         chain_key = curr->curr_chain_key;
2842         if (!depth) {
2843                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2844                         return 0;
2845                 chain_head = 1;
2846         }
2847
2848         hlock->prev_chain_key = chain_key;
2849         if (separate_irq_context(curr, hlock)) {
2850                 chain_key = 0;
2851                 chain_head = 1;
2852         }
2853         chain_key = iterate_chain_key(chain_key, id);
2854
2855         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2856                 return 0;
2857
2858         curr->curr_chain_key = chain_key;
2859         curr->lockdep_depth++;
2860         check_chain_key(curr);
2861 #ifdef CONFIG_DEBUG_LOCKDEP
2862         if (unlikely(!debug_locks))
2863                 return 0;
2864 #endif
2865         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2866                 debug_locks_off();
2867                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2868                 printk("turning off the locking correctness validator.\n");
2869                 dump_stack();
2870                 return 0;
2871         }
2872
2873         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2874                 max_lockdep_depth = curr->lockdep_depth;
2875
2876         return 1;
2877 }
2878
2879 static int
2880 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2881                            unsigned long ip)
2882 {
2883         if (!debug_locks_off())
2884                 return 0;
2885         if (debug_locks_silent)
2886                 return 0;
2887
2888         printk("\n=====================================\n");
2889         printk(  "[ BUG: bad unlock balance detected! ]\n");
2890         printk(  "-------------------------------------\n");
2891         printk("%s/%d is trying to release lock (",
2892                 curr->comm, task_pid_nr(curr));
2893         print_lockdep_cache(lock);
2894         printk(") at:\n");
2895         print_ip_sym(ip);
2896         printk("but there are no more locks to release!\n");
2897         printk("\nother info that might help us debug this:\n");
2898         lockdep_print_held_locks(curr);
2899
2900         printk("\nstack backtrace:\n");
2901         dump_stack();
2902
2903         return 0;
2904 }
2905
2906 /*
2907  * Common debugging checks for both nested and non-nested unlock:
2908  */
2909 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2910                         unsigned long ip)
2911 {
2912         if (unlikely(!debug_locks))
2913                 return 0;
2914         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2915                 return 0;
2916
2917         if (curr->lockdep_depth <= 0)
2918                 return print_unlock_inbalance_bug(curr, lock, ip);
2919
2920         return 1;
2921 }
2922
2923 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
2924 {
2925         if (hlock->instance == lock)
2926                 return 1;
2927
2928         if (hlock->references) {
2929                 struct lock_class *class = lock->class_cache[0];
2930
2931                 if (!class)
2932                         class = look_up_lock_class(lock, 0);
2933
2934                 if (DEBUG_LOCKS_WARN_ON(!class))
2935                         return 0;
2936
2937                 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
2938                         return 0;
2939
2940                 if (hlock->class_idx == class - lock_classes + 1)
2941                         return 1;
2942         }
2943
2944         return 0;
2945 }
2946
2947 static int
2948 __lock_set_class(struct lockdep_map *lock, const char *name,
2949                  struct lock_class_key *key, unsigned int subclass,
2950                  unsigned long ip)
2951 {
2952         struct task_struct *curr = current;
2953         struct held_lock *hlock, *prev_hlock;
2954         struct lock_class *class;
2955         unsigned int depth;
2956         int i;
2957
2958         depth = curr->lockdep_depth;
2959         if (DEBUG_LOCKS_WARN_ON(!depth))
2960                 return 0;
2961
2962         prev_hlock = NULL;
2963         for (i = depth-1; i >= 0; i--) {
2964                 hlock = curr->held_locks + i;
2965                 /*
2966                  * We must not cross into another context:
2967                  */
2968                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2969                         break;
2970                 if (match_held_lock(hlock, lock))
2971                         goto found_it;
2972                 prev_hlock = hlock;
2973         }
2974         return print_unlock_inbalance_bug(curr, lock, ip);
2975
2976 found_it:
2977         lockdep_init_map(lock, name, key, 0);
2978         class = register_lock_class(lock, subclass, 0);
2979         hlock->class_idx = class - lock_classes + 1;
2980
2981         curr->lockdep_depth = i;
2982         curr->curr_chain_key = hlock->prev_chain_key;
2983
2984         for (; i < depth; i++) {
2985                 hlock = curr->held_locks + i;
2986                 if (!__lock_acquire(hlock->instance,
2987                         hlock_class(hlock)->subclass, hlock->trylock,
2988                                 hlock->read, hlock->check, hlock->hardirqs_off,
2989                                 hlock->nest_lock, hlock->acquire_ip,
2990                                 hlock->references))
2991                         return 0;
2992         }
2993
2994         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2995                 return 0;
2996         return 1;
2997 }
2998
2999 /*
3000  * Remove the lock to the list of currently held locks in a
3001  * potentially non-nested (out of order) manner. This is a
3002  * relatively rare operation, as all the unlock APIs default
3003  * to nested mode (which uses lock_release()):
3004  */
3005 static int
3006 lock_release_non_nested(struct task_struct *curr,
3007                         struct lockdep_map *lock, unsigned long ip)
3008 {
3009         struct held_lock *hlock, *prev_hlock;
3010         unsigned int depth;
3011         int i;
3012
3013         /*
3014          * Check whether the lock exists in the current stack
3015          * of held locks:
3016          */
3017         depth = curr->lockdep_depth;
3018         if (DEBUG_LOCKS_WARN_ON(!depth))
3019                 return 0;
3020
3021         prev_hlock = NULL;
3022         for (i = depth-1; i >= 0; i--) {
3023                 hlock = curr->held_locks + i;
3024                 /*
3025                  * We must not cross into another context:
3026                  */
3027                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3028                         break;
3029                 if (match_held_lock(hlock, lock))
3030                         goto found_it;
3031                 prev_hlock = hlock;
3032         }
3033         return print_unlock_inbalance_bug(curr, lock, ip);
3034
3035 found_it:
3036         if (hlock->instance == lock)
3037                 lock_release_holdtime(hlock);
3038
3039         if (hlock->references) {
3040                 hlock->references--;
3041                 if (hlock->references) {
3042                         /*
3043                          * We had, and after removing one, still have
3044                          * references, the current lock stack is still
3045                          * valid. We're done!
3046                          */
3047                         return 1;
3048                 }
3049         }
3050
3051         /*
3052          * We have the right lock to unlock, 'hlock' points to it.
3053          * Now we remove it from the stack, and add back the other
3054          * entries (if any), recalculating the hash along the way:
3055          */
3056
3057         curr->lockdep_depth = i;
3058         curr->curr_chain_key = hlock->prev_chain_key;
3059
3060         for (i++; i < depth; i++) {
3061                 hlock = curr->held_locks + i;
3062                 if (!__lock_acquire(hlock->instance,
3063                         hlock_class(hlock)->subclass, hlock->trylock,
3064                                 hlock->read, hlock->check, hlock->hardirqs_off,
3065                                 hlock->nest_lock, hlock->acquire_ip,
3066                                 hlock->references))
3067                         return 0;
3068         }
3069
3070         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3071                 return 0;
3072         return 1;
3073 }
3074
3075 /*
3076  * Remove the lock to the list of currently held locks - this gets
3077  * called on mutex_unlock()/spin_unlock*() (or on a failed
3078  * mutex_lock_interruptible()). This is done for unlocks that nest
3079  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3080  */
3081 static int lock_release_nested(struct task_struct *curr,
3082                                struct lockdep_map *lock, unsigned long ip)
3083 {
3084         struct held_lock *hlock;
3085         unsigned int depth;
3086
3087         /*
3088          * Pop off the top of the lock stack:
3089          */
3090         depth = curr->lockdep_depth - 1;
3091         hlock = curr->held_locks + depth;
3092
3093         /*
3094          * Is the unlock non-nested:
3095          */
3096         if (hlock->instance != lock || hlock->references)
3097                 return lock_release_non_nested(curr, lock, ip);
3098         curr->lockdep_depth--;
3099
3100         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3101                 return 0;
3102
3103         curr->curr_chain_key = hlock->prev_chain_key;
3104
3105         lock_release_holdtime(hlock);
3106
3107 #ifdef CONFIG_DEBUG_LOCKDEP
3108         hlock->prev_chain_key = 0;
3109         hlock->class_idx = 0;
3110         hlock->acquire_ip = 0;
3111         hlock->irq_context = 0;
3112 #endif
3113         return 1;
3114 }
3115
3116 /*
3117  * Remove the lock to the list of currently held locks - this gets
3118  * called on mutex_unlock()/spin_unlock*() (or on a failed
3119  * mutex_lock_interruptible()). This is done for unlocks that nest
3120  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3121  */
3122 static void
3123 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3124 {
3125         struct task_struct *curr = current;
3126
3127         if (!check_unlock(curr, lock, ip))
3128                 return;
3129
3130         if (nested) {
3131                 if (!lock_release_nested(curr, lock, ip))
3132                         return;
3133         } else {
3134                 if (!lock_release_non_nested(curr, lock, ip))
3135                         return;
3136         }
3137
3138         check_chain_key(curr);
3139 }
3140
3141 static int __lock_is_held(struct lockdep_map *lock)
3142 {
3143         struct task_struct *curr = current;
3144         int i;
3145
3146         for (i = 0; i < curr->lockdep_depth; i++) {
3147                 struct held_lock *hlock = curr->held_locks + i;
3148
3149                 if (match_held_lock(hlock, lock))
3150                         return 1;
3151         }
3152
3153         return 0;
3154 }
3155
3156 /*
3157  * Check whether we follow the irq-flags state precisely:
3158  */
3159 static void check_flags(unsigned long flags)
3160 {
3161 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3162     defined(CONFIG_TRACE_IRQFLAGS)
3163         if (!debug_locks)
3164                 return;
3165
3166         if (irqs_disabled_flags(flags)) {
3167                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3168                         printk("possible reason: unannotated irqs-off.\n");
3169                 }
3170         } else {
3171                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3172                         printk("possible reason: unannotated irqs-on.\n");
3173                 }
3174         }
3175
3176         /*
3177          * We dont accurately track softirq state in e.g.
3178          * hardirq contexts (such as on 4KSTACKS), so only
3179          * check if not in hardirq contexts:
3180          */
3181         if (!hardirq_count()) {
3182                 if (softirq_count())
3183                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3184                 else
3185                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3186         }
3187
3188         if (!debug_locks)
3189                 print_irqtrace_events(current);
3190 #endif
3191 }
3192
3193 void lock_set_class(struct lockdep_map *lock, const char *name,
3194                     struct lock_class_key *key, unsigned int subclass,
3195                     unsigned long ip)
3196 {
3197         unsigned long flags;
3198
3199         if (unlikely(current->lockdep_recursion))
3200                 return;
3201
3202         raw_local_irq_save(flags);
3203         current->lockdep_recursion = 1;
3204         check_flags(flags);
3205         if (__lock_set_class(lock, name, key, subclass, ip))
3206                 check_chain_key(current);
3207         current->lockdep_recursion = 0;
3208         raw_local_irq_restore(flags);
3209 }
3210 EXPORT_SYMBOL_GPL(lock_set_class);
3211
3212 /*
3213  * We are not always called with irqs disabled - do that here,
3214  * and also avoid lockdep recursion:
3215  */
3216 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3217                           int trylock, int read, int check,
3218                           struct lockdep_map *nest_lock, unsigned long ip)
3219 {
3220         unsigned long flags;
3221
3222         if (unlikely(current->lockdep_recursion))
3223                 return;
3224
3225         raw_local_irq_save(flags);
3226         check_flags(flags);
3227
3228         current->lockdep_recursion = 1;
3229         trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3230         __lock_acquire(lock, subclass, trylock, read, check,
3231                        irqs_disabled_flags(flags), nest_lock, ip, 0);
3232         current->lockdep_recursion = 0;
3233         raw_local_irq_restore(flags);
3234 }
3235 EXPORT_SYMBOL_GPL(lock_acquire);
3236
3237 void lock_release(struct lockdep_map *lock, int nested,
3238                           unsigned long ip)
3239 {
3240         unsigned long flags;
3241
3242         if (unlikely(current->lockdep_recursion))
3243                 return;
3244
3245         raw_local_irq_save(flags);
3246         check_flags(flags);
3247         current->lockdep_recursion = 1;
3248         trace_lock_release(lock, ip);
3249         __lock_release(lock, nested, ip);
3250         current->lockdep_recursion = 0;
3251         raw_local_irq_restore(flags);
3252 }
3253 EXPORT_SYMBOL_GPL(lock_release);
3254
3255 int lock_is_held(struct lockdep_map *lock)
3256 {
3257         unsigned long flags;
3258         int ret = 0;
3259
3260         if (unlikely(current->lockdep_recursion))
3261                 return ret;
3262
3263         raw_local_irq_save(flags);
3264         check_flags(flags);
3265
3266         current->lockdep_recursion = 1;
3267         ret = __lock_is_held(lock);
3268         current->lockdep_recursion = 0;
3269         raw_local_irq_restore(flags);
3270
3271         return ret;
3272 }
3273 EXPORT_SYMBOL_GPL(lock_is_held);
3274
3275 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3276 {
3277         current->lockdep_reclaim_gfp = gfp_mask;
3278 }
3279
3280 void lockdep_clear_current_reclaim_state(void)
3281 {
3282         current->lockdep_reclaim_gfp = 0;
3283 }
3284
3285 #ifdef CONFIG_LOCK_STAT
3286 static int
3287 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3288                            unsigned long ip)
3289 {
3290         if (!debug_locks_off())
3291                 return 0;
3292         if (debug_locks_silent)
3293                 return 0;
3294
3295         printk("\n=================================\n");
3296         printk(  "[ BUG: bad contention detected! ]\n");
3297         printk(  "---------------------------------\n");
3298         printk("%s/%d is trying to contend lock (",
3299                 curr->comm, task_pid_nr(curr));
3300         print_lockdep_cache(lock);
3301         printk(") at:\n");
3302         print_ip_sym(ip);
3303         printk("but there are no locks held!\n");
3304         printk("\nother info that might help us debug this:\n");
3305         lockdep_print_held_locks(curr);
3306
3307         printk("\nstack backtrace:\n");
3308         dump_stack();
3309
3310         return 0;
3311 }
3312
3313 static void
3314 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3315 {
3316         struct task_struct *curr = current;
3317         struct held_lock *hlock, *prev_hlock;
3318         struct lock_class_stats *stats;
3319         unsigned int depth;
3320         int i, contention_point, contending_point;
3321
3322         depth = curr->lockdep_depth;
3323         if (DEBUG_LOCKS_WARN_ON(!depth))
3324                 return;
3325
3326         prev_hlock = NULL;
3327         for (i = depth-1; i >= 0; i--) {
3328                 hlock = curr->held_locks + i;
3329                 /*
3330                  * We must not cross into another context:
3331                  */
3332                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3333                         break;
3334                 if (match_held_lock(hlock, lock))
3335                         goto found_it;
3336                 prev_hlock = hlock;
3337         }
3338         print_lock_contention_bug(curr, lock, ip);
3339         return;
3340
3341 found_it:
3342         if (hlock->instance != lock)
3343                 return;
3344
3345         hlock->waittime_stamp = lockstat_clock();
3346
3347         contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3348         contending_point = lock_point(hlock_class(hlock)->contending_point,
3349                                       lock->ip);
3350
3351         stats = get_lock_stats(hlock_class(hlock));
3352         if (contention_point < LOCKSTAT_POINTS)
3353                 stats->contention_point[contention_point]++;
3354         if (contending_point < LOCKSTAT_POINTS)
3355                 stats->contending_point[contending_point]++;
3356         if (lock->cpu != smp_processor_id())
3357                 stats->bounces[bounce_contended + !!hlock->read]++;
3358         put_lock_stats(stats);
3359 }
3360
3361 static void
3362 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3363 {
3364         struct task_struct *curr = current;
3365         struct held_lock *hlock, *prev_hlock;
3366         struct lock_class_stats *stats;
3367         unsigned int depth;
3368         u64 now, waittime = 0;
3369         int i, cpu;
3370
3371         depth = curr->lockdep_depth;
3372         if (DEBUG_LOCKS_WARN_ON(!depth))
3373                 return;
3374
3375         prev_hlock = NULL;
3376         for (i = depth-1; i >= 0; i--) {
3377                 hlock = curr->held_locks + i;
3378                 /*
3379                  * We must not cross into another context:
3380                  */
3381                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3382                         break;
3383                 if (match_held_lock(hlock, lock))
3384                         goto found_it;
3385                 prev_hlock = hlock;
3386         }
3387         print_lock_contention_bug(curr, lock, _RET_IP_);
3388         return;
3389
3390 found_it:
3391         if (hlock->instance != lock)
3392                 return;
3393
3394         cpu = smp_processor_id();
3395         if (hlock->waittime_stamp) {
3396                 now = lockstat_clock();
3397                 waittime = now - hlock->waittime_stamp;
3398                 hlock->holdtime_stamp = now;
3399         }
3400
3401         trace_lock_acquired(lock, ip);
3402
3403         stats = get_lock_stats(hlock_class(hlock));
3404         if (waittime) {
3405                 if (hlock->read)
3406                         lock_time_inc(&stats->read_waittime, waittime);
3407                 else
3408                         lock_time_inc(&stats->write_waittime, waittime);
3409         }
3410         if (lock->cpu != cpu)
3411                 stats->bounces[bounce_acquired + !!hlock->read]++;
3412         put_lock_stats(stats);
3413
3414         lock->cpu = cpu;
3415         lock->ip = ip;
3416 }
3417
3418 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3419 {
3420         unsigned long flags;
3421
3422         if (unlikely(!lock_stat))
3423                 return;
3424
3425         if (unlikely(current->lockdep_recursion))
3426                 return;
3427
3428         raw_local_irq_save(flags);
3429         check_flags(flags);
3430         current->lockdep_recursion = 1;
3431         trace_lock_contended(lock, ip);
3432         __lock_contended(lock, ip);
3433         current->lockdep_recursion = 0;
3434         raw_local_irq_restore(flags);
3435 }
3436 EXPORT_SYMBOL_GPL(lock_contended);
3437
3438 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3439 {
3440         unsigned long flags;
3441
3442         if (unlikely(!lock_stat))
3443                 return;
3444
3445         if (unlikely(current->lockdep_recursion))
3446                 return;
3447
3448         raw_local_irq_save(flags);
3449         check_flags(flags);
3450         current->lockdep_recursion = 1;
3451         __lock_acquired(lock, ip);
3452         current->lockdep_recursion = 0;
3453         raw_local_irq_restore(flags);
3454 }
3455 EXPORT_SYMBOL_GPL(lock_acquired);
3456 #endif
3457
3458 /*
3459  * Used by the testsuite, sanitize the validator state
3460  * after a simulated failure:
3461  */
3462
3463 void lockdep_reset(void)
3464 {
3465         unsigned long flags;
3466         int i;
3467
3468         raw_local_irq_save(flags);
3469         current->curr_chain_key = 0;
3470         current->lockdep_depth = 0;
3471         current->lockdep_recursion = 0;
3472         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3473         nr_hardirq_chains = 0;
3474         nr_softirq_chains = 0;
3475         nr_process_chains = 0;
3476         debug_locks = 1;
3477         for (i = 0; i < CHAINHASH_SIZE; i++)
3478                 INIT_LIST_HEAD(chainhash_table + i);
3479         raw_local_irq_restore(flags);
3480 }
3481
3482 static void zap_class(struct lock_class *class)
3483 {
3484         int i;
3485
3486         /*
3487          * Remove all dependencies this lock is
3488          * involved in:
3489          */
3490         for (i = 0; i < nr_list_entries; i++) {
3491                 if (list_entries[i].class == class)
3492                         list_del_rcu(&list_entries[i].entry);
3493         }
3494         /*
3495          * Unhash the class and remove it from the all_lock_classes list:
3496          */
3497         list_del_rcu(&class->hash_entry);
3498         list_del_rcu(&class->lock_entry);
3499
3500         class->key = NULL;
3501 }
3502
3503 static inline int within(const void *addr, void *start, unsigned long size)
3504 {
3505         return addr >= start && addr < start + size;
3506 }
3507
3508 void lockdep_free_key_range(void *start, unsigned long size)
3509 {
3510         struct lock_class *class, *next;
3511         struct list_head *head;
3512         unsigned long flags;
3513         int i;
3514         int locked;
3515
3516         raw_local_irq_save(flags);
3517         locked = graph_lock();
3518
3519         /*
3520          * Unhash all classes that were created by this module:
3521          */
3522         for (i = 0; i < CLASSHASH_SIZE; i++) {
3523                 head = classhash_table + i;
3524                 if (list_empty(head))
3525                         continue;
3526                 list_for_each_entry_safe(class, next, head, hash_entry) {
3527                         if (within(class->key, start, size))
3528                                 zap_class(class);
3529                         else if (within(class->name, start, size))
3530                                 zap_class(class);
3531                 }
3532         }
3533
3534         if (locked)
3535                 graph_unlock();
3536         raw_local_irq_restore(flags);
3537 }
3538
3539 void lockdep_reset_lock(struct lockdep_map *lock)
3540 {
3541         struct lock_class *class, *next;
3542         struct list_head *head;
3543         unsigned long flags;
3544         int i, j;
3545         int locked;
3546
3547         raw_local_irq_save(flags);
3548
3549         /*
3550          * Remove all classes this lock might have:
3551          */
3552         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3553                 /*
3554                  * If the class exists we look it up and zap it:
3555                  */
3556                 class = look_up_lock_class(lock, j);
3557                 if (class)
3558                         zap_class(class);
3559         }
3560         /*
3561          * Debug check: in the end all mapped classes should
3562          * be gone.
3563          */
3564         locked = graph_lock();
3565         for (i = 0; i < CLASSHASH_SIZE; i++) {
3566                 head = classhash_table + i;
3567                 if (list_empty(head))
3568                         continue;
3569                 list_for_each_entry_safe(class, next, head, hash_entry) {
3570                         int match = 0;
3571
3572                         for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3573                                 match |= class == lock->class_cache[j];
3574
3575                         if (unlikely(match)) {
3576                                 if (debug_locks_off_graph_unlock())
3577                                         WARN_ON(1);
3578                                 goto out_restore;
3579                         }
3580                 }
3581         }
3582         if (locked)
3583                 graph_unlock();
3584
3585 out_restore:
3586         raw_local_irq_restore(flags);
3587 }
3588
3589 void lockdep_init(void)
3590 {
3591         int i;
3592
3593         /*
3594          * Some architectures have their own start_kernel()
3595          * code which calls lockdep_init(), while we also
3596          * call lockdep_init() from the start_kernel() itself,
3597          * and we want to initialize the hashes only once:
3598          */
3599         if (lockdep_initialized)
3600                 return;
3601
3602         for (i = 0; i < CLASSHASH_SIZE; i++)
3603                 INIT_LIST_HEAD(classhash_table + i);
3604
3605         for (i = 0; i < CHAINHASH_SIZE; i++)
3606                 INIT_LIST_HEAD(chainhash_table + i);
3607
3608         lockdep_initialized = 1;
3609 }
3610
3611 void __init lockdep_info(void)
3612 {
3613         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3614
3615         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3616         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3617         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3618         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3619         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3620         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3621         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3622
3623         printk(" memory used by lock dependency info: %lu kB\n",
3624                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3625                 sizeof(struct list_head) * CLASSHASH_SIZE +
3626                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3627                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3628                 sizeof(struct list_head) * CHAINHASH_SIZE
3629 #ifdef CONFIG_PROVE_LOCKING
3630                 + sizeof(struct circular_queue)
3631 #endif
3632                 ) / 1024
3633                 );
3634
3635         printk(" per task-struct memory footprint: %lu bytes\n",
3636                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3637
3638 #ifdef CONFIG_DEBUG_LOCKDEP
3639         if (lockdep_init_error) {
3640                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3641                 printk("Call stack leading to lockdep invocation was:\n");
3642                 print_stack_trace(&lockdep_init_trace, 0);
3643         }
3644 #endif
3645 }
3646
3647 static void
3648 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3649                      const void *mem_to, struct held_lock *hlock)
3650 {
3651         if (!debug_locks_off())
3652                 return;
3653         if (debug_locks_silent)
3654                 return;
3655
3656         printk("\n=========================\n");
3657         printk(  "[ BUG: held lock freed! ]\n");
3658         printk(  "-------------------------\n");
3659         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3660                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3661         print_lock(hlock);
3662         lockdep_print_held_locks(curr);
3663
3664         printk("\nstack backtrace:\n");
3665         dump_stack();
3666 }
3667
3668 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3669                                 const void* lock_from, unsigned long lock_len)
3670 {
3671         return lock_from + lock_len <= mem_from ||
3672                 mem_from + mem_len <= lock_from;
3673 }
3674
3675 /*
3676  * Called when kernel memory is freed (or unmapped), or if a lock
3677  * is destroyed or reinitialized - this code checks whether there is
3678  * any held lock in the memory range of <from> to <to>:
3679  */
3680 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3681 {
3682         struct task_struct *curr = current;
3683         struct held_lock *hlock;
3684         unsigned long flags;
3685         int i;
3686
3687         if (unlikely(!debug_locks))
3688                 return;
3689
3690         local_irq_save(flags);
3691         for (i = 0; i < curr->lockdep_depth; i++) {
3692                 hlock = curr->held_locks + i;
3693
3694                 if (not_in_range(mem_from, mem_len, hlock->instance,
3695                                         sizeof(*hlock->instance)))
3696                         continue;
3697
3698                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3699                 break;
3700         }
3701         local_irq_restore(flags);
3702 }
3703 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3704
3705 static void print_held_locks_bug(struct task_struct *curr)
3706 {
3707         if (!debug_locks_off())
3708                 return;
3709         if (debug_locks_silent)
3710                 return;
3711
3712         printk("\n=====================================\n");
3713         printk(  "[ BUG: lock held at task exit time! ]\n");
3714         printk(  "-------------------------------------\n");
3715         printk("%s/%d is exiting with locks still held!\n",
3716                 curr->comm, task_pid_nr(curr));
3717         lockdep_print_held_locks(curr);
3718
3719         printk("\nstack backtrace:\n");
3720         dump_stack();
3721 }
3722
3723 void debug_check_no_locks_held(struct task_struct *task)
3724 {
3725         if (unlikely(task->lockdep_depth > 0))
3726                 print_held_locks_bug(task);
3727 }
3728
3729 void debug_show_all_locks(void)
3730 {
3731         struct task_struct *g, *p;
3732         int count = 10;
3733         int unlock = 1;
3734
3735         if (unlikely(!debug_locks)) {
3736                 printk("INFO: lockdep is turned off.\n");
3737                 return;
3738         }
3739         printk("\nShowing all locks held in the system:\n");
3740
3741         /*
3742          * Here we try to get the tasklist_lock as hard as possible,
3743          * if not successful after 2 seconds we ignore it (but keep
3744          * trying). This is to enable a debug printout even if a
3745          * tasklist_lock-holding task deadlocks or crashes.
3746          */
3747 retry:
3748         if (!read_trylock(&tasklist_lock)) {
3749                 if (count == 10)
3750                         printk("hm, tasklist_lock locked, retrying... ");
3751                 if (count) {
3752                         count--;
3753                         printk(" #%d", 10-count);
3754                         mdelay(200);
3755                         goto retry;
3756                 }
3757                 printk(" ignoring it.\n");
3758                 unlock = 0;
3759         } else {
3760                 if (count != 10)
3761                         printk(KERN_CONT " locked it.\n");
3762         }
3763
3764         do_each_thread(g, p) {
3765                 /*
3766                  * It's not reliable to print a task's held locks
3767                  * if it's not sleeping (or if it's not the current
3768                  * task):
3769                  */
3770                 if (p->state == TASK_RUNNING && p != current)
3771                         continue;
3772                 if (p->lockdep_depth)
3773                         lockdep_print_held_locks(p);
3774                 if (!unlock)
3775                         if (read_trylock(&tasklist_lock))
3776                                 unlock = 1;
3777         } while_each_thread(g, p);
3778
3779         printk("\n");
3780         printk("=============================================\n\n");
3781
3782         if (unlock)
3783                 read_unlock(&tasklist_lock);
3784 }
3785 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3786
3787 /*
3788  * Careful: only use this function if you are sure that
3789  * the task cannot run in parallel!
3790  */
3791 void debug_show_held_locks(struct task_struct *task)
3792 {
3793         if (unlikely(!debug_locks)) {
3794                 printk("INFO: lockdep is turned off.\n");
3795                 return;
3796         }
3797         lockdep_print_held_locks(task);
3798 }
3799 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3800
3801 void lockdep_sys_exit(void)
3802 {
3803         struct task_struct *curr = current;
3804
3805         if (unlikely(curr->lockdep_depth)) {
3806                 if (!debug_locks_off())
3807                         return;
3808                 printk("\n================================================\n");
3809                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3810                 printk(  "------------------------------------------------\n");
3811                 printk("%s/%d is leaving the kernel with locks still held!\n",
3812                                 curr->comm, curr->pid);
3813                 lockdep_print_held_locks(curr);
3814         }
3815 }
3816
3817 void lockdep_rcu_dereference(const char *file, const int line)
3818 {
3819         struct task_struct *curr = current;
3820
3821 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
3822         if (!debug_locks_off())
3823                 return;
3824 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
3825         /* Note: the following can be executed concurrently, so be careful. */
3826         printk("\n===================================================\n");
3827         printk(  "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3828         printk(  "---------------------------------------------------\n");
3829         printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3830                         file, line);
3831         printk("\nother info that might help us debug this:\n\n");
3832         printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
3833         lockdep_print_held_locks(curr);
3834         printk("\nstack backtrace:\n");
3835         dump_stack();
3836 }
3837 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);