tracing: Drop the nested field from lock_release event
[linux-2.6.git] / kernel / lockdep.c
1 /*
2  * kernel/lockdep.c
3  *
4  * Runtime locking correctness validator
5  *
6  * Started by Ingo Molnar:
7  *
8  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
10  *
11  * this code maps all the lock dependencies as they occur in a live kernel
12  * and will warn about the following classes of locking bugs:
13  *
14  * - lock inversion scenarios
15  * - circular lock dependencies
16  * - hardirq/softirq safe/unsafe locking bugs
17  *
18  * Bugs are reported even if the current locking scenario does not cause
19  * any deadlock at this point.
20  *
21  * I.e. if anytime in the past two locks were taken in a different order,
22  * even if it happened for another task, even if those were different
23  * locks (but of the same class as this lock), this code will detect it.
24  *
25  * Thanks to Arjan van de Ven for coming up with the initial idea of
26  * mapping lock dependencies runtime.
27  */
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
47
48 #include <asm/sections.h>
49
50 #include "lockdep_internals.h"
51
52 #define CREATE_TRACE_POINTS
53 #include <trace/events/lock.h>
54
55 #ifdef CONFIG_PROVE_LOCKING
56 int prove_locking = 1;
57 module_param(prove_locking, int, 0644);
58 #else
59 #define prove_locking 0
60 #endif
61
62 #ifdef CONFIG_LOCK_STAT
63 int lock_stat = 1;
64 module_param(lock_stat, int, 0644);
65 #else
66 #define lock_stat 0
67 #endif
68
69 /*
70  * lockdep_lock: protects the lockdep graph, the hashes and the
71  *               class/list/hash allocators.
72  *
73  * This is one of the rare exceptions where it's justified
74  * to use a raw spinlock - we really dont want the spinlock
75  * code to recurse back into the lockdep code...
76  */
77 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
78
79 static int graph_lock(void)
80 {
81         arch_spin_lock(&lockdep_lock);
82         /*
83          * Make sure that if another CPU detected a bug while
84          * walking the graph we dont change it (while the other
85          * CPU is busy printing out stuff with the graph lock
86          * dropped already)
87          */
88         if (!debug_locks) {
89                 arch_spin_unlock(&lockdep_lock);
90                 return 0;
91         }
92         /* prevent any recursions within lockdep from causing deadlocks */
93         current->lockdep_recursion++;
94         return 1;
95 }
96
97 static inline int graph_unlock(void)
98 {
99         if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
100                 return DEBUG_LOCKS_WARN_ON(1);
101
102         current->lockdep_recursion--;
103         arch_spin_unlock(&lockdep_lock);
104         return 0;
105 }
106
107 /*
108  * Turn lock debugging off and return with 0 if it was off already,
109  * and also release the graph lock:
110  */
111 static inline int debug_locks_off_graph_unlock(void)
112 {
113         int ret = debug_locks_off();
114
115         arch_spin_unlock(&lockdep_lock);
116
117         return ret;
118 }
119
120 static int lockdep_initialized;
121
122 unsigned long nr_list_entries;
123 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
124
125 /*
126  * All data structures here are protected by the global debug_lock.
127  *
128  * Mutex key structs only get allocated, once during bootup, and never
129  * get freed - this significantly simplifies the debugging code.
130  */
131 unsigned long nr_lock_classes;
132 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
133
134 static inline struct lock_class *hlock_class(struct held_lock *hlock)
135 {
136         if (!hlock->class_idx) {
137                 DEBUG_LOCKS_WARN_ON(1);
138                 return NULL;
139         }
140         return lock_classes + hlock->class_idx - 1;
141 }
142
143 #ifdef CONFIG_LOCK_STAT
144 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
145                       cpu_lock_stats);
146
147 static inline u64 lockstat_clock(void)
148 {
149         return cpu_clock(smp_processor_id());
150 }
151
152 static int lock_point(unsigned long points[], unsigned long ip)
153 {
154         int i;
155
156         for (i = 0; i < LOCKSTAT_POINTS; i++) {
157                 if (points[i] == 0) {
158                         points[i] = ip;
159                         break;
160                 }
161                 if (points[i] == ip)
162                         break;
163         }
164
165         return i;
166 }
167
168 static void lock_time_inc(struct lock_time *lt, u64 time)
169 {
170         if (time > lt->max)
171                 lt->max = time;
172
173         if (time < lt->min || !lt->nr)
174                 lt->min = time;
175
176         lt->total += time;
177         lt->nr++;
178 }
179
180 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
181 {
182         if (!src->nr)
183                 return;
184
185         if (src->max > dst->max)
186                 dst->max = src->max;
187
188         if (src->min < dst->min || !dst->nr)
189                 dst->min = src->min;
190
191         dst->total += src->total;
192         dst->nr += src->nr;
193 }
194
195 struct lock_class_stats lock_stats(struct lock_class *class)
196 {
197         struct lock_class_stats stats;
198         int cpu, i;
199
200         memset(&stats, 0, sizeof(struct lock_class_stats));
201         for_each_possible_cpu(cpu) {
202                 struct lock_class_stats *pcs =
203                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
204
205                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
206                         stats.contention_point[i] += pcs->contention_point[i];
207
208                 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
209                         stats.contending_point[i] += pcs->contending_point[i];
210
211                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
212                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
213
214                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
215                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
216
217                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
218                         stats.bounces[i] += pcs->bounces[i];
219         }
220
221         return stats;
222 }
223
224 void clear_lock_stats(struct lock_class *class)
225 {
226         int cpu;
227
228         for_each_possible_cpu(cpu) {
229                 struct lock_class_stats *cpu_stats =
230                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
231
232                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
233         }
234         memset(class->contention_point, 0, sizeof(class->contention_point));
235         memset(class->contending_point, 0, sizeof(class->contending_point));
236 }
237
238 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
239 {
240         return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
241 }
242
243 static void put_lock_stats(struct lock_class_stats *stats)
244 {
245         put_cpu_var(cpu_lock_stats);
246 }
247
248 static void lock_release_holdtime(struct held_lock *hlock)
249 {
250         struct lock_class_stats *stats;
251         u64 holdtime;
252
253         if (!lock_stat)
254                 return;
255
256         holdtime = lockstat_clock() - hlock->holdtime_stamp;
257
258         stats = get_lock_stats(hlock_class(hlock));
259         if (hlock->read)
260                 lock_time_inc(&stats->read_holdtime, holdtime);
261         else
262                 lock_time_inc(&stats->write_holdtime, holdtime);
263         put_lock_stats(stats);
264 }
265 #else
266 static inline void lock_release_holdtime(struct held_lock *hlock)
267 {
268 }
269 #endif
270
271 /*
272  * We keep a global list of all lock classes. The list only grows,
273  * never shrinks. The list is only accessed with the lockdep
274  * spinlock lock held.
275  */
276 LIST_HEAD(all_lock_classes);
277
278 /*
279  * The lockdep classes are in a hash-table as well, for fast lookup:
280  */
281 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
282 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
283 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
284 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
285
286 static struct list_head classhash_table[CLASSHASH_SIZE];
287
288 /*
289  * We put the lock dependency chains into a hash-table as well, to cache
290  * their existence:
291  */
292 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
293 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
294 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
295 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
296
297 static struct list_head chainhash_table[CHAINHASH_SIZE];
298
299 /*
300  * The hash key of the lock dependency chains is a hash itself too:
301  * it's a hash of all locks taken up to that lock, including that lock.
302  * It's a 64-bit hash, because it's important for the keys to be
303  * unique.
304  */
305 #define iterate_chain_key(key1, key2) \
306         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
307         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
308         (key2))
309
310 void lockdep_off(void)
311 {
312         current->lockdep_recursion++;
313 }
314 EXPORT_SYMBOL(lockdep_off);
315
316 void lockdep_on(void)
317 {
318         current->lockdep_recursion--;
319 }
320 EXPORT_SYMBOL(lockdep_on);
321
322 /*
323  * Debugging switches:
324  */
325
326 #define VERBOSE                 0
327 #define VERY_VERBOSE            0
328
329 #if VERBOSE
330 # define HARDIRQ_VERBOSE        1
331 # define SOFTIRQ_VERBOSE        1
332 # define RECLAIM_VERBOSE        1
333 #else
334 # define HARDIRQ_VERBOSE        0
335 # define SOFTIRQ_VERBOSE        0
336 # define RECLAIM_VERBOSE        0
337 #endif
338
339 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
340 /*
341  * Quick filtering for interesting events:
342  */
343 static int class_filter(struct lock_class *class)
344 {
345 #if 0
346         /* Example */
347         if (class->name_version == 1 &&
348                         !strcmp(class->name, "lockname"))
349                 return 1;
350         if (class->name_version == 1 &&
351                         !strcmp(class->name, "&struct->lockfield"))
352                 return 1;
353 #endif
354         /* Filter everything else. 1 would be to allow everything else */
355         return 0;
356 }
357 #endif
358
359 static int verbose(struct lock_class *class)
360 {
361 #if VERBOSE
362         return class_filter(class);
363 #endif
364         return 0;
365 }
366
367 /*
368  * Stack-trace: tightly packed array of stack backtrace
369  * addresses. Protected by the graph_lock.
370  */
371 unsigned long nr_stack_trace_entries;
372 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
373
374 static int save_trace(struct stack_trace *trace)
375 {
376         trace->nr_entries = 0;
377         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
378         trace->entries = stack_trace + nr_stack_trace_entries;
379
380         trace->skip = 3;
381
382         save_stack_trace(trace);
383
384         /*
385          * Some daft arches put -1 at the end to indicate its a full trace.
386          *
387          * <rant> this is buggy anyway, since it takes a whole extra entry so a
388          * complete trace that maxes out the entries provided will be reported
389          * as incomplete, friggin useless </rant>
390          */
391         if (trace->nr_entries != 0 &&
392             trace->entries[trace->nr_entries-1] == ULONG_MAX)
393                 trace->nr_entries--;
394
395         trace->max_entries = trace->nr_entries;
396
397         nr_stack_trace_entries += trace->nr_entries;
398
399         if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
400                 if (!debug_locks_off_graph_unlock())
401                         return 0;
402
403                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
404                 printk("turning off the locking correctness validator.\n");
405                 dump_stack();
406
407                 return 0;
408         }
409
410         return 1;
411 }
412
413 unsigned int nr_hardirq_chains;
414 unsigned int nr_softirq_chains;
415 unsigned int nr_process_chains;
416 unsigned int max_lockdep_depth;
417
418 #ifdef CONFIG_DEBUG_LOCKDEP
419 /*
420  * We cannot printk in early bootup code. Not even early_printk()
421  * might work. So we mark any initialization errors and printk
422  * about it later on, in lockdep_info().
423  */
424 static int lockdep_init_error;
425 static unsigned long lockdep_init_trace_data[20];
426 static struct stack_trace lockdep_init_trace = {
427         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
428         .entries = lockdep_init_trace_data,
429 };
430
431 /*
432  * Various lockdep statistics:
433  */
434 atomic_t chain_lookup_hits;
435 atomic_t chain_lookup_misses;
436 atomic_t hardirqs_on_events;
437 atomic_t hardirqs_off_events;
438 atomic_t redundant_hardirqs_on;
439 atomic_t redundant_hardirqs_off;
440 atomic_t softirqs_on_events;
441 atomic_t softirqs_off_events;
442 atomic_t redundant_softirqs_on;
443 atomic_t redundant_softirqs_off;
444 atomic_t nr_unused_locks;
445 atomic_t nr_cyclic_checks;
446 atomic_t nr_find_usage_forwards_checks;
447 atomic_t nr_find_usage_backwards_checks;
448 #endif
449
450 /*
451  * Locking printouts:
452  */
453
454 #define __USAGE(__STATE)                                                \
455         [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
456         [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
457         [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
458         [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
459
460 static const char *usage_str[] =
461 {
462 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
463 #include "lockdep_states.h"
464 #undef LOCKDEP_STATE
465         [LOCK_USED] = "INITIAL USE",
466 };
467
468 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
469 {
470         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
471 }
472
473 static inline unsigned long lock_flag(enum lock_usage_bit bit)
474 {
475         return 1UL << bit;
476 }
477
478 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
479 {
480         char c = '.';
481
482         if (class->usage_mask & lock_flag(bit + 2))
483                 c = '+';
484         if (class->usage_mask & lock_flag(bit)) {
485                 c = '-';
486                 if (class->usage_mask & lock_flag(bit + 2))
487                         c = '?';
488         }
489
490         return c;
491 }
492
493 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
494 {
495         int i = 0;
496
497 #define LOCKDEP_STATE(__STATE)                                          \
498         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
499         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
500 #include "lockdep_states.h"
501 #undef LOCKDEP_STATE
502
503         usage[i] = '\0';
504 }
505
506 static void print_lock_name(struct lock_class *class)
507 {
508         char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
509         const char *name;
510
511         get_usage_chars(class, usage);
512
513         name = class->name;
514         if (!name) {
515                 name = __get_key_name(class->key, str);
516                 printk(" (%s", name);
517         } else {
518                 printk(" (%s", name);
519                 if (class->name_version > 1)
520                         printk("#%d", class->name_version);
521                 if (class->subclass)
522                         printk("/%d", class->subclass);
523         }
524         printk("){%s}", usage);
525 }
526
527 static void print_lockdep_cache(struct lockdep_map *lock)
528 {
529         const char *name;
530         char str[KSYM_NAME_LEN];
531
532         name = lock->name;
533         if (!name)
534                 name = __get_key_name(lock->key->subkeys, str);
535
536         printk("%s", name);
537 }
538
539 static void print_lock(struct held_lock *hlock)
540 {
541         print_lock_name(hlock_class(hlock));
542         printk(", at: ");
543         print_ip_sym(hlock->acquire_ip);
544 }
545
546 static void lockdep_print_held_locks(struct task_struct *curr)
547 {
548         int i, depth = curr->lockdep_depth;
549
550         if (!depth) {
551                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
552                 return;
553         }
554         printk("%d lock%s held by %s/%d:\n",
555                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
556
557         for (i = 0; i < depth; i++) {
558                 printk(" #%d: ", i);
559                 print_lock(curr->held_locks + i);
560         }
561 }
562
563 static void print_kernel_version(void)
564 {
565         printk("%s %.*s\n", init_utsname()->release,
566                 (int)strcspn(init_utsname()->version, " "),
567                 init_utsname()->version);
568 }
569
570 static int very_verbose(struct lock_class *class)
571 {
572 #if VERY_VERBOSE
573         return class_filter(class);
574 #endif
575         return 0;
576 }
577
578 /*
579  * Is this the address of a static object:
580  */
581 static int static_obj(void *obj)
582 {
583         unsigned long start = (unsigned long) &_stext,
584                       end   = (unsigned long) &_end,
585                       addr  = (unsigned long) obj;
586
587         /*
588          * static variable?
589          */
590         if ((addr >= start) && (addr < end))
591                 return 1;
592
593         if (arch_is_kernel_data(addr))
594                 return 1;
595
596         /*
597          * in-kernel percpu var?
598          */
599         if (is_kernel_percpu_address(addr))
600                 return 1;
601
602         /*
603          * module static or percpu var?
604          */
605         return is_module_address(addr) || is_module_percpu_address(addr);
606 }
607
608 /*
609  * To make lock name printouts unique, we calculate a unique
610  * class->name_version generation counter:
611  */
612 static int count_matching_names(struct lock_class *new_class)
613 {
614         struct lock_class *class;
615         int count = 0;
616
617         if (!new_class->name)
618                 return 0;
619
620         list_for_each_entry(class, &all_lock_classes, lock_entry) {
621                 if (new_class->key - new_class->subclass == class->key)
622                         return class->name_version;
623                 if (class->name && !strcmp(class->name, new_class->name))
624                         count = max(count, class->name_version);
625         }
626
627         return count + 1;
628 }
629
630 /*
631  * Register a lock's class in the hash-table, if the class is not present
632  * yet. Otherwise we look it up. We cache the result in the lock object
633  * itself, so actual lookup of the hash should be once per lock object.
634  */
635 static inline struct lock_class *
636 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
637 {
638         struct lockdep_subclass_key *key;
639         struct list_head *hash_head;
640         struct lock_class *class;
641
642 #ifdef CONFIG_DEBUG_LOCKDEP
643         /*
644          * If the architecture calls into lockdep before initializing
645          * the hashes then we'll warn about it later. (we cannot printk
646          * right now)
647          */
648         if (unlikely(!lockdep_initialized)) {
649                 lockdep_init();
650                 lockdep_init_error = 1;
651                 save_stack_trace(&lockdep_init_trace);
652         }
653 #endif
654
655         /*
656          * Static locks do not have their class-keys yet - for them the key
657          * is the lock object itself:
658          */
659         if (unlikely(!lock->key))
660                 lock->key = (void *)lock;
661
662         /*
663          * NOTE: the class-key must be unique. For dynamic locks, a static
664          * lock_class_key variable is passed in through the mutex_init()
665          * (or spin_lock_init()) call - which acts as the key. For static
666          * locks we use the lock object itself as the key.
667          */
668         BUILD_BUG_ON(sizeof(struct lock_class_key) >
669                         sizeof(struct lockdep_map));
670
671         key = lock->key->subkeys + subclass;
672
673         hash_head = classhashentry(key);
674
675         /*
676          * We can walk the hash lockfree, because the hash only
677          * grows, and we are careful when adding entries to the end:
678          */
679         list_for_each_entry(class, hash_head, hash_entry) {
680                 if (class->key == key) {
681                         WARN_ON_ONCE(class->name != lock->name);
682                         return class;
683                 }
684         }
685
686         return NULL;
687 }
688
689 /*
690  * Register a lock's class in the hash-table, if the class is not present
691  * yet. Otherwise we look it up. We cache the result in the lock object
692  * itself, so actual lookup of the hash should be once per lock object.
693  */
694 static inline struct lock_class *
695 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
696 {
697         struct lockdep_subclass_key *key;
698         struct list_head *hash_head;
699         struct lock_class *class;
700         unsigned long flags;
701
702         class = look_up_lock_class(lock, subclass);
703         if (likely(class))
704                 return class;
705
706         /*
707          * Debug-check: all keys must be persistent!
708          */
709         if (!static_obj(lock->key)) {
710                 debug_locks_off();
711                 printk("INFO: trying to register non-static key.\n");
712                 printk("the code is fine but needs lockdep annotation.\n");
713                 printk("turning off the locking correctness validator.\n");
714                 dump_stack();
715
716                 return NULL;
717         }
718
719         key = lock->key->subkeys + subclass;
720         hash_head = classhashentry(key);
721
722         raw_local_irq_save(flags);
723         if (!graph_lock()) {
724                 raw_local_irq_restore(flags);
725                 return NULL;
726         }
727         /*
728          * We have to do the hash-walk again, to avoid races
729          * with another CPU:
730          */
731         list_for_each_entry(class, hash_head, hash_entry)
732                 if (class->key == key)
733                         goto out_unlock_set;
734         /*
735          * Allocate a new key from the static array, and add it to
736          * the hash:
737          */
738         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
739                 if (!debug_locks_off_graph_unlock()) {
740                         raw_local_irq_restore(flags);
741                         return NULL;
742                 }
743                 raw_local_irq_restore(flags);
744
745                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
746                 printk("turning off the locking correctness validator.\n");
747                 dump_stack();
748                 return NULL;
749         }
750         class = lock_classes + nr_lock_classes++;
751         debug_atomic_inc(&nr_unused_locks);
752         class->key = key;
753         class->name = lock->name;
754         class->subclass = subclass;
755         INIT_LIST_HEAD(&class->lock_entry);
756         INIT_LIST_HEAD(&class->locks_before);
757         INIT_LIST_HEAD(&class->locks_after);
758         class->name_version = count_matching_names(class);
759         /*
760          * We use RCU's safe list-add method to make
761          * parallel walking of the hash-list safe:
762          */
763         list_add_tail_rcu(&class->hash_entry, hash_head);
764         /*
765          * Add it to the global list of classes:
766          */
767         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
768
769         if (verbose(class)) {
770                 graph_unlock();
771                 raw_local_irq_restore(flags);
772
773                 printk("\nnew class %p: %s", class->key, class->name);
774                 if (class->name_version > 1)
775                         printk("#%d", class->name_version);
776                 printk("\n");
777                 dump_stack();
778
779                 raw_local_irq_save(flags);
780                 if (!graph_lock()) {
781                         raw_local_irq_restore(flags);
782                         return NULL;
783                 }
784         }
785 out_unlock_set:
786         graph_unlock();
787         raw_local_irq_restore(flags);
788
789         if (!subclass || force)
790                 lock->class_cache = class;
791
792         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
793                 return NULL;
794
795         return class;
796 }
797
798 #ifdef CONFIG_PROVE_LOCKING
799 /*
800  * Allocate a lockdep entry. (assumes the graph_lock held, returns
801  * with NULL on failure)
802  */
803 static struct lock_list *alloc_list_entry(void)
804 {
805         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
806                 if (!debug_locks_off_graph_unlock())
807                         return NULL;
808
809                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
810                 printk("turning off the locking correctness validator.\n");
811                 dump_stack();
812                 return NULL;
813         }
814         return list_entries + nr_list_entries++;
815 }
816
817 /*
818  * Add a new dependency to the head of the list:
819  */
820 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
821                             struct list_head *head, unsigned long ip, int distance)
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         if (!save_trace(&entry->trace))
833                 return 0;
834
835         entry->class = this;
836         entry->distance = distance;
837         /*
838          * Since we never remove from the dependency list, the list can
839          * be walked lockless by other CPUs, it's only allocation
840          * that must be protected by the spinlock. But this also means
841          * we must make new entries visible only once writes to the
842          * entry become visible - hence the RCU op:
843          */
844         list_add_tail_rcu(&entry->entry, head);
845
846         return 1;
847 }
848
849 /*
850  * For good efficiency of modular, we use power of 2
851  */
852 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
853 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
854
855 /*
856  * The circular_queue and helpers is used to implement the
857  * breadth-first search(BFS)algorithem, by which we can build
858  * the shortest path from the next lock to be acquired to the
859  * previous held lock if there is a circular between them.
860  */
861 struct circular_queue {
862         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
863         unsigned int  front, rear;
864 };
865
866 static struct circular_queue lock_cq;
867
868 unsigned int max_bfs_queue_depth;
869
870 static unsigned int lockdep_dependency_gen_id;
871
872 static inline void __cq_init(struct circular_queue *cq)
873 {
874         cq->front = cq->rear = 0;
875         lockdep_dependency_gen_id++;
876 }
877
878 static inline int __cq_empty(struct circular_queue *cq)
879 {
880         return (cq->front == cq->rear);
881 }
882
883 static inline int __cq_full(struct circular_queue *cq)
884 {
885         return ((cq->rear + 1) & CQ_MASK) == cq->front;
886 }
887
888 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
889 {
890         if (__cq_full(cq))
891                 return -1;
892
893         cq->element[cq->rear] = elem;
894         cq->rear = (cq->rear + 1) & CQ_MASK;
895         return 0;
896 }
897
898 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
899 {
900         if (__cq_empty(cq))
901                 return -1;
902
903         *elem = cq->element[cq->front];
904         cq->front = (cq->front + 1) & CQ_MASK;
905         return 0;
906 }
907
908 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
909 {
910         return (cq->rear - cq->front) & CQ_MASK;
911 }
912
913 static inline void mark_lock_accessed(struct lock_list *lock,
914                                         struct lock_list *parent)
915 {
916         unsigned long nr;
917
918         nr = lock - list_entries;
919         WARN_ON(nr >= nr_list_entries);
920         lock->parent = parent;
921         lock->class->dep_gen_id = lockdep_dependency_gen_id;
922 }
923
924 static inline unsigned long lock_accessed(struct lock_list *lock)
925 {
926         unsigned long nr;
927
928         nr = lock - list_entries;
929         WARN_ON(nr >= nr_list_entries);
930         return lock->class->dep_gen_id == lockdep_dependency_gen_id;
931 }
932
933 static inline struct lock_list *get_lock_parent(struct lock_list *child)
934 {
935         return child->parent;
936 }
937
938 static inline int get_lock_depth(struct lock_list *child)
939 {
940         int depth = 0;
941         struct lock_list *parent;
942
943         while ((parent = get_lock_parent(child))) {
944                 child = parent;
945                 depth++;
946         }
947         return depth;
948 }
949
950 static int __bfs(struct lock_list *source_entry,
951                  void *data,
952                  int (*match)(struct lock_list *entry, void *data),
953                  struct lock_list **target_entry,
954                  int forward)
955 {
956         struct lock_list *entry;
957         struct list_head *head;
958         struct circular_queue *cq = &lock_cq;
959         int ret = 1;
960
961         if (match(source_entry, data)) {
962                 *target_entry = source_entry;
963                 ret = 0;
964                 goto exit;
965         }
966
967         if (forward)
968                 head = &source_entry->class->locks_after;
969         else
970                 head = &source_entry->class->locks_before;
971
972         if (list_empty(head))
973                 goto exit;
974
975         __cq_init(cq);
976         __cq_enqueue(cq, (unsigned long)source_entry);
977
978         while (!__cq_empty(cq)) {
979                 struct lock_list *lock;
980
981                 __cq_dequeue(cq, (unsigned long *)&lock);
982
983                 if (!lock->class) {
984                         ret = -2;
985                         goto exit;
986                 }
987
988                 if (forward)
989                         head = &lock->class->locks_after;
990                 else
991                         head = &lock->class->locks_before;
992
993                 list_for_each_entry(entry, head, entry) {
994                         if (!lock_accessed(entry)) {
995                                 unsigned int cq_depth;
996                                 mark_lock_accessed(entry, lock);
997                                 if (match(entry, data)) {
998                                         *target_entry = entry;
999                                         ret = 0;
1000                                         goto exit;
1001                                 }
1002
1003                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
1004                                         ret = -1;
1005                                         goto exit;
1006                                 }
1007                                 cq_depth = __cq_get_elem_count(cq);
1008                                 if (max_bfs_queue_depth < cq_depth)
1009                                         max_bfs_queue_depth = cq_depth;
1010                         }
1011                 }
1012         }
1013 exit:
1014         return ret;
1015 }
1016
1017 static inline int __bfs_forwards(struct lock_list *src_entry,
1018                         void *data,
1019                         int (*match)(struct lock_list *entry, void *data),
1020                         struct lock_list **target_entry)
1021 {
1022         return __bfs(src_entry, data, match, target_entry, 1);
1023
1024 }
1025
1026 static inline int __bfs_backwards(struct lock_list *src_entry,
1027                         void *data,
1028                         int (*match)(struct lock_list *entry, void *data),
1029                         struct lock_list **target_entry)
1030 {
1031         return __bfs(src_entry, data, match, target_entry, 0);
1032
1033 }
1034
1035 /*
1036  * Recursive, forwards-direction lock-dependency checking, used for
1037  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1038  * checking.
1039  */
1040
1041 /*
1042  * Print a dependency chain entry (this is only done when a deadlock
1043  * has been detected):
1044  */
1045 static noinline int
1046 print_circular_bug_entry(struct lock_list *target, int depth)
1047 {
1048         if (debug_locks_silent)
1049                 return 0;
1050         printk("\n-> #%u", depth);
1051         print_lock_name(target->class);
1052         printk(":\n");
1053         print_stack_trace(&target->trace, 6);
1054
1055         return 0;
1056 }
1057
1058 /*
1059  * When a circular dependency is detected, print the
1060  * header first:
1061  */
1062 static noinline int
1063 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1064                         struct held_lock *check_src,
1065                         struct held_lock *check_tgt)
1066 {
1067         struct task_struct *curr = current;
1068
1069         if (debug_locks_silent)
1070                 return 0;
1071
1072         printk("\n=======================================================\n");
1073         printk(  "[ INFO: possible circular locking dependency detected ]\n");
1074         print_kernel_version();
1075         printk(  "-------------------------------------------------------\n");
1076         printk("%s/%d is trying to acquire lock:\n",
1077                 curr->comm, task_pid_nr(curr));
1078         print_lock(check_src);
1079         printk("\nbut task is already holding lock:\n");
1080         print_lock(check_tgt);
1081         printk("\nwhich lock already depends on the new lock.\n\n");
1082         printk("\nthe existing dependency chain (in reverse order) is:\n");
1083
1084         print_circular_bug_entry(entry, depth);
1085
1086         return 0;
1087 }
1088
1089 static inline int class_equal(struct lock_list *entry, void *data)
1090 {
1091         return entry->class == data;
1092 }
1093
1094 static noinline int print_circular_bug(struct lock_list *this,
1095                                 struct lock_list *target,
1096                                 struct held_lock *check_src,
1097                                 struct held_lock *check_tgt)
1098 {
1099         struct task_struct *curr = current;
1100         struct lock_list *parent;
1101         int depth;
1102
1103         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1104                 return 0;
1105
1106         if (!save_trace(&this->trace))
1107                 return 0;
1108
1109         depth = get_lock_depth(target);
1110
1111         print_circular_bug_header(target, depth, check_src, check_tgt);
1112
1113         parent = get_lock_parent(target);
1114
1115         while (parent) {
1116                 print_circular_bug_entry(parent, --depth);
1117                 parent = get_lock_parent(parent);
1118         }
1119
1120         printk("\nother info that might help us debug this:\n\n");
1121         lockdep_print_held_locks(curr);
1122
1123         printk("\nstack backtrace:\n");
1124         dump_stack();
1125
1126         return 0;
1127 }
1128
1129 static noinline int print_bfs_bug(int ret)
1130 {
1131         if (!debug_locks_off_graph_unlock())
1132                 return 0;
1133
1134         WARN(1, "lockdep bfs error:%d\n", ret);
1135
1136         return 0;
1137 }
1138
1139 static int noop_count(struct lock_list *entry, void *data)
1140 {
1141         (*(unsigned long *)data)++;
1142         return 0;
1143 }
1144
1145 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1146 {
1147         unsigned long  count = 0;
1148         struct lock_list *uninitialized_var(target_entry);
1149
1150         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1151
1152         return count;
1153 }
1154 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1155 {
1156         unsigned long ret, flags;
1157         struct lock_list this;
1158
1159         this.parent = NULL;
1160         this.class = class;
1161
1162         local_irq_save(flags);
1163         arch_spin_lock(&lockdep_lock);
1164         ret = __lockdep_count_forward_deps(&this);
1165         arch_spin_unlock(&lockdep_lock);
1166         local_irq_restore(flags);
1167
1168         return ret;
1169 }
1170
1171 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1172 {
1173         unsigned long  count = 0;
1174         struct lock_list *uninitialized_var(target_entry);
1175
1176         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1177
1178         return count;
1179 }
1180
1181 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1182 {
1183         unsigned long ret, flags;
1184         struct lock_list this;
1185
1186         this.parent = NULL;
1187         this.class = class;
1188
1189         local_irq_save(flags);
1190         arch_spin_lock(&lockdep_lock);
1191         ret = __lockdep_count_backward_deps(&this);
1192         arch_spin_unlock(&lockdep_lock);
1193         local_irq_restore(flags);
1194
1195         return ret;
1196 }
1197
1198 /*
1199  * Prove that the dependency graph starting at <entry> can not
1200  * lead to <target>. Print an error and return 0 if it does.
1201  */
1202 static noinline int
1203 check_noncircular(struct lock_list *root, struct lock_class *target,
1204                 struct lock_list **target_entry)
1205 {
1206         int result;
1207
1208         debug_atomic_inc(&nr_cyclic_checks);
1209
1210         result = __bfs_forwards(root, target, class_equal, target_entry);
1211
1212         return result;
1213 }
1214
1215 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1216 /*
1217  * Forwards and backwards subgraph searching, for the purposes of
1218  * proving that two subgraphs can be connected by a new dependency
1219  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1220  */
1221
1222 static inline int usage_match(struct lock_list *entry, void *bit)
1223 {
1224         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1225 }
1226
1227
1228
1229 /*
1230  * Find a node in the forwards-direction dependency sub-graph starting
1231  * at @root->class that matches @bit.
1232  *
1233  * Return 0 if such a node exists in the subgraph, and put that node
1234  * into *@target_entry.
1235  *
1236  * Return 1 otherwise and keep *@target_entry unchanged.
1237  * Return <0 on error.
1238  */
1239 static int
1240 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1241                         struct lock_list **target_entry)
1242 {
1243         int result;
1244
1245         debug_atomic_inc(&nr_find_usage_forwards_checks);
1246
1247         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1248
1249         return result;
1250 }
1251
1252 /*
1253  * Find a node in the backwards-direction dependency sub-graph starting
1254  * at @root->class that matches @bit.
1255  *
1256  * Return 0 if such a node exists in the subgraph, and put that node
1257  * into *@target_entry.
1258  *
1259  * Return 1 otherwise and keep *@target_entry unchanged.
1260  * Return <0 on error.
1261  */
1262 static int
1263 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1264                         struct lock_list **target_entry)
1265 {
1266         int result;
1267
1268         debug_atomic_inc(&nr_find_usage_backwards_checks);
1269
1270         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1271
1272         return result;
1273 }
1274
1275 static void print_lock_class_header(struct lock_class *class, int depth)
1276 {
1277         int bit;
1278
1279         printk("%*s->", depth, "");
1280         print_lock_name(class);
1281         printk(" ops: %lu", class->ops);
1282         printk(" {\n");
1283
1284         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1285                 if (class->usage_mask & (1 << bit)) {
1286                         int len = depth;
1287
1288                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1289                         len += printk(" at:\n");
1290                         print_stack_trace(class->usage_traces + bit, len);
1291                 }
1292         }
1293         printk("%*s }\n", depth, "");
1294
1295         printk("%*s ... key      at: ",depth,"");
1296         print_ip_sym((unsigned long)class->key);
1297 }
1298
1299 /*
1300  * printk the shortest lock dependencies from @start to @end in reverse order:
1301  */
1302 static void __used
1303 print_shortest_lock_dependencies(struct lock_list *leaf,
1304                                 struct lock_list *root)
1305 {
1306         struct lock_list *entry = leaf;
1307         int depth;
1308
1309         /*compute depth from generated tree by BFS*/
1310         depth = get_lock_depth(leaf);
1311
1312         do {
1313                 print_lock_class_header(entry->class, depth);
1314                 printk("%*s ... acquired at:\n", depth, "");
1315                 print_stack_trace(&entry->trace, 2);
1316                 printk("\n");
1317
1318                 if (depth == 0 && (entry != root)) {
1319                         printk("lockdep:%s bad BFS generated tree\n", __func__);
1320                         break;
1321                 }
1322
1323                 entry = get_lock_parent(entry);
1324                 depth--;
1325         } while (entry && (depth >= 0));
1326
1327         return;
1328 }
1329
1330 static int
1331 print_bad_irq_dependency(struct task_struct *curr,
1332                          struct lock_list *prev_root,
1333                          struct lock_list *next_root,
1334                          struct lock_list *backwards_entry,
1335                          struct lock_list *forwards_entry,
1336                          struct held_lock *prev,
1337                          struct held_lock *next,
1338                          enum lock_usage_bit bit1,
1339                          enum lock_usage_bit bit2,
1340                          const char *irqclass)
1341 {
1342         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1343                 return 0;
1344
1345         printk("\n======================================================\n");
1346         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1347                 irqclass, irqclass);
1348         print_kernel_version();
1349         printk(  "------------------------------------------------------\n");
1350         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1351                 curr->comm, task_pid_nr(curr),
1352                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1353                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1354                 curr->hardirqs_enabled,
1355                 curr->softirqs_enabled);
1356         print_lock(next);
1357
1358         printk("\nand this task is already holding:\n");
1359         print_lock(prev);
1360         printk("which would create a new lock dependency:\n");
1361         print_lock_name(hlock_class(prev));
1362         printk(" ->");
1363         print_lock_name(hlock_class(next));
1364         printk("\n");
1365
1366         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1367                 irqclass);
1368         print_lock_name(backwards_entry->class);
1369         printk("\n... which became %s-irq-safe at:\n", irqclass);
1370
1371         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1372
1373         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1374         print_lock_name(forwards_entry->class);
1375         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1376         printk("...");
1377
1378         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1379
1380         printk("\nother info that might help us debug this:\n\n");
1381         lockdep_print_held_locks(curr);
1382
1383         printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1384         printk(" and the holding lock:\n");
1385         if (!save_trace(&prev_root->trace))
1386                 return 0;
1387         print_shortest_lock_dependencies(backwards_entry, prev_root);
1388
1389         printk("\nthe dependencies between the lock to be acquired");
1390         printk(" and %s-irq-unsafe lock:\n", irqclass);
1391         if (!save_trace(&next_root->trace))
1392                 return 0;
1393         print_shortest_lock_dependencies(forwards_entry, next_root);
1394
1395         printk("\nstack backtrace:\n");
1396         dump_stack();
1397
1398         return 0;
1399 }
1400
1401 static int
1402 check_usage(struct task_struct *curr, struct held_lock *prev,
1403             struct held_lock *next, enum lock_usage_bit bit_backwards,
1404             enum lock_usage_bit bit_forwards, const char *irqclass)
1405 {
1406         int ret;
1407         struct lock_list this, that;
1408         struct lock_list *uninitialized_var(target_entry);
1409         struct lock_list *uninitialized_var(target_entry1);
1410
1411         this.parent = NULL;
1412
1413         this.class = hlock_class(prev);
1414         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1415         if (ret < 0)
1416                 return print_bfs_bug(ret);
1417         if (ret == 1)
1418                 return ret;
1419
1420         that.parent = NULL;
1421         that.class = hlock_class(next);
1422         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1423         if (ret < 0)
1424                 return print_bfs_bug(ret);
1425         if (ret == 1)
1426                 return ret;
1427
1428         return print_bad_irq_dependency(curr, &this, &that,
1429                         target_entry, target_entry1,
1430                         prev, next,
1431                         bit_backwards, bit_forwards, irqclass);
1432 }
1433
1434 static const char *state_names[] = {
1435 #define LOCKDEP_STATE(__STATE) \
1436         __stringify(__STATE),
1437 #include "lockdep_states.h"
1438 #undef LOCKDEP_STATE
1439 };
1440
1441 static const char *state_rnames[] = {
1442 #define LOCKDEP_STATE(__STATE) \
1443         __stringify(__STATE)"-READ",
1444 #include "lockdep_states.h"
1445 #undef LOCKDEP_STATE
1446 };
1447
1448 static inline const char *state_name(enum lock_usage_bit bit)
1449 {
1450         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1451 }
1452
1453 static int exclusive_bit(int new_bit)
1454 {
1455         /*
1456          * USED_IN
1457          * USED_IN_READ
1458          * ENABLED
1459          * ENABLED_READ
1460          *
1461          * bit 0 - write/read
1462          * bit 1 - used_in/enabled
1463          * bit 2+  state
1464          */
1465
1466         int state = new_bit & ~3;
1467         int dir = new_bit & 2;
1468
1469         /*
1470          * keep state, bit flip the direction and strip read.
1471          */
1472         return state | (dir ^ 2);
1473 }
1474
1475 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1476                            struct held_lock *next, enum lock_usage_bit bit)
1477 {
1478         /*
1479          * Prove that the new dependency does not connect a hardirq-safe
1480          * lock with a hardirq-unsafe lock - to achieve this we search
1481          * the backwards-subgraph starting at <prev>, and the
1482          * forwards-subgraph starting at <next>:
1483          */
1484         if (!check_usage(curr, prev, next, bit,
1485                            exclusive_bit(bit), state_name(bit)))
1486                 return 0;
1487
1488         bit++; /* _READ */
1489
1490         /*
1491          * Prove that the new dependency does not connect a hardirq-safe-read
1492          * lock with a hardirq-unsafe lock - to achieve this we search
1493          * the backwards-subgraph starting at <prev>, and the
1494          * forwards-subgraph starting at <next>:
1495          */
1496         if (!check_usage(curr, prev, next, bit,
1497                            exclusive_bit(bit), state_name(bit)))
1498                 return 0;
1499
1500         return 1;
1501 }
1502
1503 static int
1504 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1505                 struct held_lock *next)
1506 {
1507 #define LOCKDEP_STATE(__STATE)                                          \
1508         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1509                 return 0;
1510 #include "lockdep_states.h"
1511 #undef LOCKDEP_STATE
1512
1513         return 1;
1514 }
1515
1516 static void inc_chains(void)
1517 {
1518         if (current->hardirq_context)
1519                 nr_hardirq_chains++;
1520         else {
1521                 if (current->softirq_context)
1522                         nr_softirq_chains++;
1523                 else
1524                         nr_process_chains++;
1525         }
1526 }
1527
1528 #else
1529
1530 static inline int
1531 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1532                 struct held_lock *next)
1533 {
1534         return 1;
1535 }
1536
1537 static inline void inc_chains(void)
1538 {
1539         nr_process_chains++;
1540 }
1541
1542 #endif
1543
1544 static int
1545 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1546                    struct held_lock *next)
1547 {
1548         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1549                 return 0;
1550
1551         printk("\n=============================================\n");
1552         printk(  "[ INFO: possible recursive locking detected ]\n");
1553         print_kernel_version();
1554         printk(  "---------------------------------------------\n");
1555         printk("%s/%d is trying to acquire lock:\n",
1556                 curr->comm, task_pid_nr(curr));
1557         print_lock(next);
1558         printk("\nbut task is already holding lock:\n");
1559         print_lock(prev);
1560
1561         printk("\nother info that might help us debug this:\n");
1562         lockdep_print_held_locks(curr);
1563
1564         printk("\nstack backtrace:\n");
1565         dump_stack();
1566
1567         return 0;
1568 }
1569
1570 /*
1571  * Check whether we are holding such a class already.
1572  *
1573  * (Note that this has to be done separately, because the graph cannot
1574  * detect such classes of deadlocks.)
1575  *
1576  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1577  */
1578 static int
1579 check_deadlock(struct task_struct *curr, struct held_lock *next,
1580                struct lockdep_map *next_instance, int read)
1581 {
1582         struct held_lock *prev;
1583         struct held_lock *nest = NULL;
1584         int i;
1585
1586         for (i = 0; i < curr->lockdep_depth; i++) {
1587                 prev = curr->held_locks + i;
1588
1589                 if (prev->instance == next->nest_lock)
1590                         nest = prev;
1591
1592                 if (hlock_class(prev) != hlock_class(next))
1593                         continue;
1594
1595                 /*
1596                  * Allow read-after-read recursion of the same
1597                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1598                  */
1599                 if ((read == 2) && prev->read)
1600                         return 2;
1601
1602                 /*
1603                  * We're holding the nest_lock, which serializes this lock's
1604                  * nesting behaviour.
1605                  */
1606                 if (nest)
1607                         return 2;
1608
1609                 return print_deadlock_bug(curr, prev, next);
1610         }
1611         return 1;
1612 }
1613
1614 /*
1615  * There was a chain-cache miss, and we are about to add a new dependency
1616  * to a previous lock. We recursively validate the following rules:
1617  *
1618  *  - would the adding of the <prev> -> <next> dependency create a
1619  *    circular dependency in the graph? [== circular deadlock]
1620  *
1621  *  - does the new prev->next dependency connect any hardirq-safe lock
1622  *    (in the full backwards-subgraph starting at <prev>) with any
1623  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1624  *    <next>)? [== illegal lock inversion with hardirq contexts]
1625  *
1626  *  - does the new prev->next dependency connect any softirq-safe lock
1627  *    (in the full backwards-subgraph starting at <prev>) with any
1628  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1629  *    <next>)? [== illegal lock inversion with softirq contexts]
1630  *
1631  * any of these scenarios could lead to a deadlock.
1632  *
1633  * Then if all the validations pass, we add the forwards and backwards
1634  * dependency.
1635  */
1636 static int
1637 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1638                struct held_lock *next, int distance)
1639 {
1640         struct lock_list *entry;
1641         int ret;
1642         struct lock_list this;
1643         struct lock_list *uninitialized_var(target_entry);
1644
1645         /*
1646          * Prove that the new <prev> -> <next> dependency would not
1647          * create a circular dependency in the graph. (We do this by
1648          * forward-recursing into the graph starting at <next>, and
1649          * checking whether we can reach <prev>.)
1650          *
1651          * We are using global variables to control the recursion, to
1652          * keep the stackframe size of the recursive functions low:
1653          */
1654         this.class = hlock_class(next);
1655         this.parent = NULL;
1656         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1657         if (unlikely(!ret))
1658                 return print_circular_bug(&this, target_entry, next, prev);
1659         else if (unlikely(ret < 0))
1660                 return print_bfs_bug(ret);
1661
1662         if (!check_prev_add_irq(curr, prev, next))
1663                 return 0;
1664
1665         /*
1666          * For recursive read-locks we do all the dependency checks,
1667          * but we dont store read-triggered dependencies (only
1668          * write-triggered dependencies). This ensures that only the
1669          * write-side dependencies matter, and that if for example a
1670          * write-lock never takes any other locks, then the reads are
1671          * equivalent to a NOP.
1672          */
1673         if (next->read == 2 || prev->read == 2)
1674                 return 1;
1675         /*
1676          * Is the <prev> -> <next> dependency already present?
1677          *
1678          * (this may occur even though this is a new chain: consider
1679          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1680          *  chains - the second one will be new, but L1 already has
1681          *  L2 added to its dependency list, due to the first chain.)
1682          */
1683         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1684                 if (entry->class == hlock_class(next)) {
1685                         if (distance == 1)
1686                                 entry->distance = 1;
1687                         return 2;
1688                 }
1689         }
1690
1691         /*
1692          * Ok, all validations passed, add the new lock
1693          * to the previous lock's dependency list:
1694          */
1695         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1696                                &hlock_class(prev)->locks_after,
1697                                next->acquire_ip, distance);
1698
1699         if (!ret)
1700                 return 0;
1701
1702         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1703                                &hlock_class(next)->locks_before,
1704                                next->acquire_ip, distance);
1705         if (!ret)
1706                 return 0;
1707
1708         /*
1709          * Debugging printouts:
1710          */
1711         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1712                 graph_unlock();
1713                 printk("\n new dependency: ");
1714                 print_lock_name(hlock_class(prev));
1715                 printk(" => ");
1716                 print_lock_name(hlock_class(next));
1717                 printk("\n");
1718                 dump_stack();
1719                 return graph_lock();
1720         }
1721         return 1;
1722 }
1723
1724 /*
1725  * Add the dependency to all directly-previous locks that are 'relevant'.
1726  * The ones that are relevant are (in increasing distance from curr):
1727  * all consecutive trylock entries and the final non-trylock entry - or
1728  * the end of this context's lock-chain - whichever comes first.
1729  */
1730 static int
1731 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1732 {
1733         int depth = curr->lockdep_depth;
1734         struct held_lock *hlock;
1735
1736         /*
1737          * Debugging checks.
1738          *
1739          * Depth must not be zero for a non-head lock:
1740          */
1741         if (!depth)
1742                 goto out_bug;
1743         /*
1744          * At least two relevant locks must exist for this
1745          * to be a head:
1746          */
1747         if (curr->held_locks[depth].irq_context !=
1748                         curr->held_locks[depth-1].irq_context)
1749                 goto out_bug;
1750
1751         for (;;) {
1752                 int distance = curr->lockdep_depth - depth + 1;
1753                 hlock = curr->held_locks + depth-1;
1754                 /*
1755                  * Only non-recursive-read entries get new dependencies
1756                  * added:
1757                  */
1758                 if (hlock->read != 2) {
1759                         if (!check_prev_add(curr, hlock, next, distance))
1760                                 return 0;
1761                         /*
1762                          * Stop after the first non-trylock entry,
1763                          * as non-trylock entries have added their
1764                          * own direct dependencies already, so this
1765                          * lock is connected to them indirectly:
1766                          */
1767                         if (!hlock->trylock)
1768                                 break;
1769                 }
1770                 depth--;
1771                 /*
1772                  * End of lock-stack?
1773                  */
1774                 if (!depth)
1775                         break;
1776                 /*
1777                  * Stop the search if we cross into another context:
1778                  */
1779                 if (curr->held_locks[depth].irq_context !=
1780                                 curr->held_locks[depth-1].irq_context)
1781                         break;
1782         }
1783         return 1;
1784 out_bug:
1785         if (!debug_locks_off_graph_unlock())
1786                 return 0;
1787
1788         WARN_ON(1);
1789
1790         return 0;
1791 }
1792
1793 unsigned long nr_lock_chains;
1794 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1795 int nr_chain_hlocks;
1796 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1797
1798 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1799 {
1800         return lock_classes + chain_hlocks[chain->base + i];
1801 }
1802
1803 /*
1804  * Look up a dependency chain. If the key is not present yet then
1805  * add it and return 1 - in this case the new dependency chain is
1806  * validated. If the key is already hashed, return 0.
1807  * (On return with 1 graph_lock is held.)
1808  */
1809 static inline int lookup_chain_cache(struct task_struct *curr,
1810                                      struct held_lock *hlock,
1811                                      u64 chain_key)
1812 {
1813         struct lock_class *class = hlock_class(hlock);
1814         struct list_head *hash_head = chainhashentry(chain_key);
1815         struct lock_chain *chain;
1816         struct held_lock *hlock_curr, *hlock_next;
1817         int i, j, n, cn;
1818
1819         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1820                 return 0;
1821         /*
1822          * We can walk it lock-free, because entries only get added
1823          * to the hash:
1824          */
1825         list_for_each_entry(chain, hash_head, entry) {
1826                 if (chain->chain_key == chain_key) {
1827 cache_hit:
1828                         debug_atomic_inc(&chain_lookup_hits);
1829                         if (very_verbose(class))
1830                                 printk("\nhash chain already cached, key: "
1831                                         "%016Lx tail class: [%p] %s\n",
1832                                         (unsigned long long)chain_key,
1833                                         class->key, class->name);
1834                         return 0;
1835                 }
1836         }
1837         if (very_verbose(class))
1838                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1839                         (unsigned long long)chain_key, class->key, class->name);
1840         /*
1841          * Allocate a new chain entry from the static array, and add
1842          * it to the hash:
1843          */
1844         if (!graph_lock())
1845                 return 0;
1846         /*
1847          * We have to walk the chain again locked - to avoid duplicates:
1848          */
1849         list_for_each_entry(chain, hash_head, entry) {
1850                 if (chain->chain_key == chain_key) {
1851                         graph_unlock();
1852                         goto cache_hit;
1853                 }
1854         }
1855         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1856                 if (!debug_locks_off_graph_unlock())
1857                         return 0;
1858
1859                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1860                 printk("turning off the locking correctness validator.\n");
1861                 dump_stack();
1862                 return 0;
1863         }
1864         chain = lock_chains + nr_lock_chains++;
1865         chain->chain_key = chain_key;
1866         chain->irq_context = hlock->irq_context;
1867         /* Find the first held_lock of current chain */
1868         hlock_next = hlock;
1869         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1870                 hlock_curr = curr->held_locks + i;
1871                 if (hlock_curr->irq_context != hlock_next->irq_context)
1872                         break;
1873                 hlock_next = hlock;
1874         }
1875         i++;
1876         chain->depth = curr->lockdep_depth + 1 - i;
1877         cn = nr_chain_hlocks;
1878         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1879                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1880                 if (n == cn)
1881                         break;
1882                 cn = n;
1883         }
1884         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1885                 chain->base = cn;
1886                 for (j = 0; j < chain->depth - 1; j++, i++) {
1887                         int lock_id = curr->held_locks[i].class_idx - 1;
1888                         chain_hlocks[chain->base + j] = lock_id;
1889                 }
1890                 chain_hlocks[chain->base + j] = class - lock_classes;
1891         }
1892         list_add_tail_rcu(&chain->entry, hash_head);
1893         debug_atomic_inc(&chain_lookup_misses);
1894         inc_chains();
1895
1896         return 1;
1897 }
1898
1899 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1900                 struct held_lock *hlock, int chain_head, u64 chain_key)
1901 {
1902         /*
1903          * Trylock needs to maintain the stack of held locks, but it
1904          * does not add new dependencies, because trylock can be done
1905          * in any order.
1906          *
1907          * We look up the chain_key and do the O(N^2) check and update of
1908          * the dependencies only if this is a new dependency chain.
1909          * (If lookup_chain_cache() returns with 1 it acquires
1910          * graph_lock for us)
1911          */
1912         if (!hlock->trylock && (hlock->check == 2) &&
1913             lookup_chain_cache(curr, hlock, chain_key)) {
1914                 /*
1915                  * Check whether last held lock:
1916                  *
1917                  * - is irq-safe, if this lock is irq-unsafe
1918                  * - is softirq-safe, if this lock is hardirq-unsafe
1919                  *
1920                  * And check whether the new lock's dependency graph
1921                  * could lead back to the previous lock.
1922                  *
1923                  * any of these scenarios could lead to a deadlock. If
1924                  * All validations
1925                  */
1926                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1927
1928                 if (!ret)
1929                         return 0;
1930                 /*
1931                  * Mark recursive read, as we jump over it when
1932                  * building dependencies (just like we jump over
1933                  * trylock entries):
1934                  */
1935                 if (ret == 2)
1936                         hlock->read = 2;
1937                 /*
1938                  * Add dependency only if this lock is not the head
1939                  * of the chain, and if it's not a secondary read-lock:
1940                  */
1941                 if (!chain_head && ret != 2)
1942                         if (!check_prevs_add(curr, hlock))
1943                                 return 0;
1944                 graph_unlock();
1945         } else
1946                 /* after lookup_chain_cache(): */
1947                 if (unlikely(!debug_locks))
1948                         return 0;
1949
1950         return 1;
1951 }
1952 #else
1953 static inline int validate_chain(struct task_struct *curr,
1954                 struct lockdep_map *lock, struct held_lock *hlock,
1955                 int chain_head, u64 chain_key)
1956 {
1957         return 1;
1958 }
1959 #endif
1960
1961 /*
1962  * We are building curr_chain_key incrementally, so double-check
1963  * it from scratch, to make sure that it's done correctly:
1964  */
1965 static void check_chain_key(struct task_struct *curr)
1966 {
1967 #ifdef CONFIG_DEBUG_LOCKDEP
1968         struct held_lock *hlock, *prev_hlock = NULL;
1969         unsigned int i, id;
1970         u64 chain_key = 0;
1971
1972         for (i = 0; i < curr->lockdep_depth; i++) {
1973                 hlock = curr->held_locks + i;
1974                 if (chain_key != hlock->prev_chain_key) {
1975                         debug_locks_off();
1976                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1977                                 curr->lockdep_depth, i,
1978                                 (unsigned long long)chain_key,
1979                                 (unsigned long long)hlock->prev_chain_key);
1980                         return;
1981                 }
1982                 id = hlock->class_idx - 1;
1983                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1984                         return;
1985
1986                 if (prev_hlock && (prev_hlock->irq_context !=
1987                                                         hlock->irq_context))
1988                         chain_key = 0;
1989                 chain_key = iterate_chain_key(chain_key, id);
1990                 prev_hlock = hlock;
1991         }
1992         if (chain_key != curr->curr_chain_key) {
1993                 debug_locks_off();
1994                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1995                         curr->lockdep_depth, i,
1996                         (unsigned long long)chain_key,
1997                         (unsigned long long)curr->curr_chain_key);
1998         }
1999 #endif
2000 }
2001
2002 static int
2003 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2004                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2005 {
2006         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2007                 return 0;
2008
2009         printk("\n=================================\n");
2010         printk(  "[ INFO: inconsistent lock state ]\n");
2011         print_kernel_version();
2012         printk(  "---------------------------------\n");
2013
2014         printk("inconsistent {%s} -> {%s} usage.\n",
2015                 usage_str[prev_bit], usage_str[new_bit]);
2016
2017         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2018                 curr->comm, task_pid_nr(curr),
2019                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2020                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2021                 trace_hardirqs_enabled(curr),
2022                 trace_softirqs_enabled(curr));
2023         print_lock(this);
2024
2025         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2026         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2027
2028         print_irqtrace_events(curr);
2029         printk("\nother info that might help us debug this:\n");
2030         lockdep_print_held_locks(curr);
2031
2032         printk("\nstack backtrace:\n");
2033         dump_stack();
2034
2035         return 0;
2036 }
2037
2038 /*
2039  * Print out an error if an invalid bit is set:
2040  */
2041 static inline int
2042 valid_state(struct task_struct *curr, struct held_lock *this,
2043             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2044 {
2045         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2046                 return print_usage_bug(curr, this, bad_bit, new_bit);
2047         return 1;
2048 }
2049
2050 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2051                      enum lock_usage_bit new_bit);
2052
2053 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2054
2055 /*
2056  * print irq inversion bug:
2057  */
2058 static int
2059 print_irq_inversion_bug(struct task_struct *curr,
2060                         struct lock_list *root, struct lock_list *other,
2061                         struct held_lock *this, int forwards,
2062                         const char *irqclass)
2063 {
2064         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2065                 return 0;
2066
2067         printk("\n=========================================================\n");
2068         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2069         print_kernel_version();
2070         printk(  "---------------------------------------------------------\n");
2071         printk("%s/%d just changed the state of lock:\n",
2072                 curr->comm, task_pid_nr(curr));
2073         print_lock(this);
2074         if (forwards)
2075                 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2076         else
2077                 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2078         print_lock_name(other->class);
2079         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2080
2081         printk("\nother info that might help us debug this:\n");
2082         lockdep_print_held_locks(curr);
2083
2084         printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2085         if (!save_trace(&root->trace))
2086                 return 0;
2087         print_shortest_lock_dependencies(other, root);
2088
2089         printk("\nstack backtrace:\n");
2090         dump_stack();
2091
2092         return 0;
2093 }
2094
2095 /*
2096  * Prove that in the forwards-direction subgraph starting at <this>
2097  * there is no lock matching <mask>:
2098  */
2099 static int
2100 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2101                      enum lock_usage_bit bit, const char *irqclass)
2102 {
2103         int ret;
2104         struct lock_list root;
2105         struct lock_list *uninitialized_var(target_entry);
2106
2107         root.parent = NULL;
2108         root.class = hlock_class(this);
2109         ret = find_usage_forwards(&root, bit, &target_entry);
2110         if (ret < 0)
2111                 return print_bfs_bug(ret);
2112         if (ret == 1)
2113                 return ret;
2114
2115         return print_irq_inversion_bug(curr, &root, target_entry,
2116                                         this, 1, irqclass);
2117 }
2118
2119 /*
2120  * Prove that in the backwards-direction subgraph starting at <this>
2121  * there is no lock matching <mask>:
2122  */
2123 static int
2124 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2125                       enum lock_usage_bit bit, const char *irqclass)
2126 {
2127         int ret;
2128         struct lock_list root;
2129         struct lock_list *uninitialized_var(target_entry);
2130
2131         root.parent = NULL;
2132         root.class = hlock_class(this);
2133         ret = find_usage_backwards(&root, bit, &target_entry);
2134         if (ret < 0)
2135                 return print_bfs_bug(ret);
2136         if (ret == 1)
2137                 return ret;
2138
2139         return print_irq_inversion_bug(curr, &root, target_entry,
2140                                         this, 0, irqclass);
2141 }
2142
2143 void print_irqtrace_events(struct task_struct *curr)
2144 {
2145         printk("irq event stamp: %u\n", curr->irq_events);
2146         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2147         print_ip_sym(curr->hardirq_enable_ip);
2148         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2149         print_ip_sym(curr->hardirq_disable_ip);
2150         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2151         print_ip_sym(curr->softirq_enable_ip);
2152         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2153         print_ip_sym(curr->softirq_disable_ip);
2154 }
2155
2156 static int HARDIRQ_verbose(struct lock_class *class)
2157 {
2158 #if HARDIRQ_VERBOSE
2159         return class_filter(class);
2160 #endif
2161         return 0;
2162 }
2163
2164 static int SOFTIRQ_verbose(struct lock_class *class)
2165 {
2166 #if SOFTIRQ_VERBOSE
2167         return class_filter(class);
2168 #endif
2169         return 0;
2170 }
2171
2172 static int RECLAIM_FS_verbose(struct lock_class *class)
2173 {
2174 #if RECLAIM_VERBOSE
2175         return class_filter(class);
2176 #endif
2177         return 0;
2178 }
2179
2180 #define STRICT_READ_CHECKS      1
2181
2182 static int (*state_verbose_f[])(struct lock_class *class) = {
2183 #define LOCKDEP_STATE(__STATE) \
2184         __STATE##_verbose,
2185 #include "lockdep_states.h"
2186 #undef LOCKDEP_STATE
2187 };
2188
2189 static inline int state_verbose(enum lock_usage_bit bit,
2190                                 struct lock_class *class)
2191 {
2192         return state_verbose_f[bit >> 2](class);
2193 }
2194
2195 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2196                              enum lock_usage_bit bit, const char *name);
2197
2198 static int
2199 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2200                 enum lock_usage_bit new_bit)
2201 {
2202         int excl_bit = exclusive_bit(new_bit);
2203         int read = new_bit & 1;
2204         int dir = new_bit & 2;
2205
2206         /*
2207          * mark USED_IN has to look forwards -- to ensure no dependency
2208          * has ENABLED state, which would allow recursion deadlocks.
2209          *
2210          * mark ENABLED has to look backwards -- to ensure no dependee
2211          * has USED_IN state, which, again, would allow  recursion deadlocks.
2212          */
2213         check_usage_f usage = dir ?
2214                 check_usage_backwards : check_usage_forwards;
2215
2216         /*
2217          * Validate that this particular lock does not have conflicting
2218          * usage states.
2219          */
2220         if (!valid_state(curr, this, new_bit, excl_bit))
2221                 return 0;
2222
2223         /*
2224          * Validate that the lock dependencies don't have conflicting usage
2225          * states.
2226          */
2227         if ((!read || !dir || STRICT_READ_CHECKS) &&
2228                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2229                 return 0;
2230
2231         /*
2232          * Check for read in write conflicts
2233          */
2234         if (!read) {
2235                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2236                         return 0;
2237
2238                 if (STRICT_READ_CHECKS &&
2239                         !usage(curr, this, excl_bit + 1,
2240                                 state_name(new_bit + 1)))
2241                         return 0;
2242         }
2243
2244         if (state_verbose(new_bit, hlock_class(this)))
2245                 return 2;
2246
2247         return 1;
2248 }
2249
2250 enum mark_type {
2251 #define LOCKDEP_STATE(__STATE)  __STATE,
2252 #include "lockdep_states.h"
2253 #undef LOCKDEP_STATE
2254 };
2255
2256 /*
2257  * Mark all held locks with a usage bit:
2258  */
2259 static int
2260 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2261 {
2262         enum lock_usage_bit usage_bit;
2263         struct held_lock *hlock;
2264         int i;
2265
2266         for (i = 0; i < curr->lockdep_depth; i++) {
2267                 hlock = curr->held_locks + i;
2268
2269                 usage_bit = 2 + (mark << 2); /* ENABLED */
2270                 if (hlock->read)
2271                         usage_bit += 1; /* READ */
2272
2273                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2274
2275                 if (!mark_lock(curr, hlock, usage_bit))
2276                         return 0;
2277         }
2278
2279         return 1;
2280 }
2281
2282 /*
2283  * Debugging helper: via this flag we know that we are in
2284  * 'early bootup code', and will warn about any invalid irqs-on event:
2285  */
2286 static int early_boot_irqs_enabled;
2287
2288 void early_boot_irqs_off(void)
2289 {
2290         early_boot_irqs_enabled = 0;
2291 }
2292
2293 void early_boot_irqs_on(void)
2294 {
2295         early_boot_irqs_enabled = 1;
2296 }
2297
2298 /*
2299  * Hardirqs will be enabled:
2300  */
2301 void trace_hardirqs_on_caller(unsigned long ip)
2302 {
2303         struct task_struct *curr = current;
2304
2305         time_hardirqs_on(CALLER_ADDR0, ip);
2306
2307         if (unlikely(!debug_locks || current->lockdep_recursion))
2308                 return;
2309
2310         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2311                 return;
2312
2313         if (unlikely(curr->hardirqs_enabled)) {
2314                 debug_atomic_inc(&redundant_hardirqs_on);
2315                 return;
2316         }
2317         /* we'll do an OFF -> ON transition: */
2318         curr->hardirqs_enabled = 1;
2319
2320         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2321                 return;
2322         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2323                 return;
2324         /*
2325          * We are going to turn hardirqs on, so set the
2326          * usage bit for all held locks:
2327          */
2328         if (!mark_held_locks(curr, HARDIRQ))
2329                 return;
2330         /*
2331          * If we have softirqs enabled, then set the usage
2332          * bit for all held locks. (disabled hardirqs prevented
2333          * this bit from being set before)
2334          */
2335         if (curr->softirqs_enabled)
2336                 if (!mark_held_locks(curr, SOFTIRQ))
2337                         return;
2338
2339         curr->hardirq_enable_ip = ip;
2340         curr->hardirq_enable_event = ++curr->irq_events;
2341         debug_atomic_inc(&hardirqs_on_events);
2342 }
2343 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2344
2345 void trace_hardirqs_on(void)
2346 {
2347         trace_hardirqs_on_caller(CALLER_ADDR0);
2348 }
2349 EXPORT_SYMBOL(trace_hardirqs_on);
2350
2351 /*
2352  * Hardirqs were disabled:
2353  */
2354 void trace_hardirqs_off_caller(unsigned long ip)
2355 {
2356         struct task_struct *curr = current;
2357
2358         time_hardirqs_off(CALLER_ADDR0, ip);
2359
2360         if (unlikely(!debug_locks || current->lockdep_recursion))
2361                 return;
2362
2363         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2364                 return;
2365
2366         if (curr->hardirqs_enabled) {
2367                 /*
2368                  * We have done an ON -> OFF transition:
2369                  */
2370                 curr->hardirqs_enabled = 0;
2371                 curr->hardirq_disable_ip = ip;
2372                 curr->hardirq_disable_event = ++curr->irq_events;
2373                 debug_atomic_inc(&hardirqs_off_events);
2374         } else
2375                 debug_atomic_inc(&redundant_hardirqs_off);
2376 }
2377 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2378
2379 void trace_hardirqs_off(void)
2380 {
2381         trace_hardirqs_off_caller(CALLER_ADDR0);
2382 }
2383 EXPORT_SYMBOL(trace_hardirqs_off);
2384
2385 /*
2386  * Softirqs will be enabled:
2387  */
2388 void trace_softirqs_on(unsigned long ip)
2389 {
2390         struct task_struct *curr = current;
2391
2392         if (unlikely(!debug_locks))
2393                 return;
2394
2395         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2396                 return;
2397
2398         if (curr->softirqs_enabled) {
2399                 debug_atomic_inc(&redundant_softirqs_on);
2400                 return;
2401         }
2402
2403         /*
2404          * We'll do an OFF -> ON transition:
2405          */
2406         curr->softirqs_enabled = 1;
2407         curr->softirq_enable_ip = ip;
2408         curr->softirq_enable_event = ++curr->irq_events;
2409         debug_atomic_inc(&softirqs_on_events);
2410         /*
2411          * We are going to turn softirqs on, so set the
2412          * usage bit for all held locks, if hardirqs are
2413          * enabled too:
2414          */
2415         if (curr->hardirqs_enabled)
2416                 mark_held_locks(curr, SOFTIRQ);
2417 }
2418
2419 /*
2420  * Softirqs were disabled:
2421  */
2422 void trace_softirqs_off(unsigned long ip)
2423 {
2424         struct task_struct *curr = current;
2425
2426         if (unlikely(!debug_locks))
2427                 return;
2428
2429         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2430                 return;
2431
2432         if (curr->softirqs_enabled) {
2433                 /*
2434                  * We have done an ON -> OFF transition:
2435                  */
2436                 curr->softirqs_enabled = 0;
2437                 curr->softirq_disable_ip = ip;
2438                 curr->softirq_disable_event = ++curr->irq_events;
2439                 debug_atomic_inc(&softirqs_off_events);
2440                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2441         } else
2442                 debug_atomic_inc(&redundant_softirqs_off);
2443 }
2444
2445 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2446 {
2447         struct task_struct *curr = current;
2448
2449         if (unlikely(!debug_locks))
2450                 return;
2451
2452         /* no reclaim without waiting on it */
2453         if (!(gfp_mask & __GFP_WAIT))
2454                 return;
2455
2456         /* this guy won't enter reclaim */
2457         if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2458                 return;
2459
2460         /* We're only interested __GFP_FS allocations for now */
2461         if (!(gfp_mask & __GFP_FS))
2462                 return;
2463
2464         if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2465                 return;
2466
2467         mark_held_locks(curr, RECLAIM_FS);
2468 }
2469
2470 static void check_flags(unsigned long flags);
2471
2472 void lockdep_trace_alloc(gfp_t gfp_mask)
2473 {
2474         unsigned long flags;
2475
2476         if (unlikely(current->lockdep_recursion))
2477                 return;
2478
2479         raw_local_irq_save(flags);
2480         check_flags(flags);
2481         current->lockdep_recursion = 1;
2482         __lockdep_trace_alloc(gfp_mask, flags);
2483         current->lockdep_recursion = 0;
2484         raw_local_irq_restore(flags);
2485 }
2486
2487 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2488 {
2489         /*
2490          * If non-trylock use in a hardirq or softirq context, then
2491          * mark the lock as used in these contexts:
2492          */
2493         if (!hlock->trylock) {
2494                 if (hlock->read) {
2495                         if (curr->hardirq_context)
2496                                 if (!mark_lock(curr, hlock,
2497                                                 LOCK_USED_IN_HARDIRQ_READ))
2498                                         return 0;
2499                         if (curr->softirq_context)
2500                                 if (!mark_lock(curr, hlock,
2501                                                 LOCK_USED_IN_SOFTIRQ_READ))
2502                                         return 0;
2503                 } else {
2504                         if (curr->hardirq_context)
2505                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2506                                         return 0;
2507                         if (curr->softirq_context)
2508                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2509                                         return 0;
2510                 }
2511         }
2512         if (!hlock->hardirqs_off) {
2513                 if (hlock->read) {
2514                         if (!mark_lock(curr, hlock,
2515                                         LOCK_ENABLED_HARDIRQ_READ))
2516                                 return 0;
2517                         if (curr->softirqs_enabled)
2518                                 if (!mark_lock(curr, hlock,
2519                                                 LOCK_ENABLED_SOFTIRQ_READ))
2520                                         return 0;
2521                 } else {
2522                         if (!mark_lock(curr, hlock,
2523                                         LOCK_ENABLED_HARDIRQ))
2524                                 return 0;
2525                         if (curr->softirqs_enabled)
2526                                 if (!mark_lock(curr, hlock,
2527                                                 LOCK_ENABLED_SOFTIRQ))
2528                                         return 0;
2529                 }
2530         }
2531
2532         /*
2533          * We reuse the irq context infrastructure more broadly as a general
2534          * context checking code. This tests GFP_FS recursion (a lock taken
2535          * during reclaim for a GFP_FS allocation is held over a GFP_FS
2536          * allocation).
2537          */
2538         if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2539                 if (hlock->read) {
2540                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2541                                         return 0;
2542                 } else {
2543                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2544                                         return 0;
2545                 }
2546         }
2547
2548         return 1;
2549 }
2550
2551 static int separate_irq_context(struct task_struct *curr,
2552                 struct held_lock *hlock)
2553 {
2554         unsigned int depth = curr->lockdep_depth;
2555
2556         /*
2557          * Keep track of points where we cross into an interrupt context:
2558          */
2559         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2560                                 curr->softirq_context;
2561         if (depth) {
2562                 struct held_lock *prev_hlock;
2563
2564                 prev_hlock = curr->held_locks + depth-1;
2565                 /*
2566                  * If we cross into another context, reset the
2567                  * hash key (this also prevents the checking and the
2568                  * adding of the dependency to 'prev'):
2569                  */
2570                 if (prev_hlock->irq_context != hlock->irq_context)
2571                         return 1;
2572         }
2573         return 0;
2574 }
2575
2576 #else
2577
2578 static inline
2579 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2580                 enum lock_usage_bit new_bit)
2581 {
2582         WARN_ON(1);
2583         return 1;
2584 }
2585
2586 static inline int mark_irqflags(struct task_struct *curr,
2587                 struct held_lock *hlock)
2588 {
2589         return 1;
2590 }
2591
2592 static inline int separate_irq_context(struct task_struct *curr,
2593                 struct held_lock *hlock)
2594 {
2595         return 0;
2596 }
2597
2598 void lockdep_trace_alloc(gfp_t gfp_mask)
2599 {
2600 }
2601
2602 #endif
2603
2604 /*
2605  * Mark a lock with a usage bit, and validate the state transition:
2606  */
2607 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2608                              enum lock_usage_bit new_bit)
2609 {
2610         unsigned int new_mask = 1 << new_bit, ret = 1;
2611
2612         /*
2613          * If already set then do not dirty the cacheline,
2614          * nor do any checks:
2615          */
2616         if (likely(hlock_class(this)->usage_mask & new_mask))
2617                 return 1;
2618
2619         if (!graph_lock())
2620                 return 0;
2621         /*
2622          * Make sure we didnt race:
2623          */
2624         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2625                 graph_unlock();
2626                 return 1;
2627         }
2628
2629         hlock_class(this)->usage_mask |= new_mask;
2630
2631         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2632                 return 0;
2633
2634         switch (new_bit) {
2635 #define LOCKDEP_STATE(__STATE)                  \
2636         case LOCK_USED_IN_##__STATE:            \
2637         case LOCK_USED_IN_##__STATE##_READ:     \
2638         case LOCK_ENABLED_##__STATE:            \
2639         case LOCK_ENABLED_##__STATE##_READ:
2640 #include "lockdep_states.h"
2641 #undef LOCKDEP_STATE
2642                 ret = mark_lock_irq(curr, this, new_bit);
2643                 if (!ret)
2644                         return 0;
2645                 break;
2646         case LOCK_USED:
2647                 debug_atomic_dec(&nr_unused_locks);
2648                 break;
2649         default:
2650                 if (!debug_locks_off_graph_unlock())
2651                         return 0;
2652                 WARN_ON(1);
2653                 return 0;
2654         }
2655
2656         graph_unlock();
2657
2658         /*
2659          * We must printk outside of the graph_lock:
2660          */
2661         if (ret == 2) {
2662                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2663                 print_lock(this);
2664                 print_irqtrace_events(curr);
2665                 dump_stack();
2666         }
2667
2668         return ret;
2669 }
2670
2671 /*
2672  * Initialize a lock instance's lock-class mapping info:
2673  */
2674 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2675                       struct lock_class_key *key, int subclass)
2676 {
2677         lock->class_cache = NULL;
2678 #ifdef CONFIG_LOCK_STAT
2679         lock->cpu = raw_smp_processor_id();
2680 #endif
2681
2682         if (DEBUG_LOCKS_WARN_ON(!name)) {
2683                 lock->name = "NULL";
2684                 return;
2685         }
2686
2687         lock->name = name;
2688
2689         if (DEBUG_LOCKS_WARN_ON(!key))
2690                 return;
2691         /*
2692          * Sanity check, the lock-class key must be persistent:
2693          */
2694         if (!static_obj(key)) {
2695                 printk("BUG: key %p not in .data!\n", key);
2696                 DEBUG_LOCKS_WARN_ON(1);
2697                 return;
2698         }
2699         lock->key = key;
2700
2701         if (unlikely(!debug_locks))
2702                 return;
2703
2704         if (subclass)
2705                 register_lock_class(lock, subclass, 1);
2706 }
2707 EXPORT_SYMBOL_GPL(lockdep_init_map);
2708
2709 /*
2710  * This gets called for every mutex_lock*()/spin_lock*() operation.
2711  * We maintain the dependency maps and validate the locking attempt:
2712  */
2713 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2714                           int trylock, int read, int check, int hardirqs_off,
2715                           struct lockdep_map *nest_lock, unsigned long ip,
2716                           int references)
2717 {
2718         struct task_struct *curr = current;
2719         struct lock_class *class = NULL;
2720         struct held_lock *hlock;
2721         unsigned int depth, id;
2722         int chain_head = 0;
2723         int class_idx;
2724         u64 chain_key;
2725
2726         if (!prove_locking)
2727                 check = 1;
2728
2729         if (unlikely(!debug_locks))
2730                 return 0;
2731
2732         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2733                 return 0;
2734
2735         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2736                 debug_locks_off();
2737                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2738                 printk("turning off the locking correctness validator.\n");
2739                 dump_stack();
2740                 return 0;
2741         }
2742
2743         if (!subclass)
2744                 class = lock->class_cache;
2745         /*
2746          * Not cached yet or subclass?
2747          */
2748         if (unlikely(!class)) {
2749                 class = register_lock_class(lock, subclass, 0);
2750                 if (!class)
2751                         return 0;
2752         }
2753         debug_atomic_inc((atomic_t *)&class->ops);
2754         if (very_verbose(class)) {
2755                 printk("\nacquire class [%p] %s", class->key, class->name);
2756                 if (class->name_version > 1)
2757                         printk("#%d", class->name_version);
2758                 printk("\n");
2759                 dump_stack();
2760         }
2761
2762         /*
2763          * Add the lock to the list of currently held locks.
2764          * (we dont increase the depth just yet, up until the
2765          * dependency checks are done)
2766          */
2767         depth = curr->lockdep_depth;
2768         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2769                 return 0;
2770
2771         class_idx = class - lock_classes + 1;
2772
2773         if (depth) {
2774                 hlock = curr->held_locks + depth - 1;
2775                 if (hlock->class_idx == class_idx && nest_lock) {
2776                         if (hlock->references)
2777                                 hlock->references++;
2778                         else
2779                                 hlock->references = 2;
2780
2781                         return 1;
2782                 }
2783         }
2784
2785         hlock = curr->held_locks + depth;
2786         if (DEBUG_LOCKS_WARN_ON(!class))
2787                 return 0;
2788         hlock->class_idx = class_idx;
2789         hlock->acquire_ip = ip;
2790         hlock->instance = lock;
2791         hlock->nest_lock = nest_lock;
2792         hlock->trylock = trylock;
2793         hlock->read = read;
2794         hlock->check = check;
2795         hlock->hardirqs_off = !!hardirqs_off;
2796         hlock->references = references;
2797 #ifdef CONFIG_LOCK_STAT
2798         hlock->waittime_stamp = 0;
2799         hlock->holdtime_stamp = lockstat_clock();
2800 #endif
2801
2802         if (check == 2 && !mark_irqflags(curr, hlock))
2803                 return 0;
2804
2805         /* mark it as used: */
2806         if (!mark_lock(curr, hlock, LOCK_USED))
2807                 return 0;
2808
2809         /*
2810          * Calculate the chain hash: it's the combined hash of all the
2811          * lock keys along the dependency chain. We save the hash value
2812          * at every step so that we can get the current hash easily
2813          * after unlock. The chain hash is then used to cache dependency
2814          * results.
2815          *
2816          * The 'key ID' is what is the most compact key value to drive
2817          * the hash, not class->key.
2818          */
2819         id = class - lock_classes;
2820         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2821                 return 0;
2822
2823         chain_key = curr->curr_chain_key;
2824         if (!depth) {
2825                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2826                         return 0;
2827                 chain_head = 1;
2828         }
2829
2830         hlock->prev_chain_key = chain_key;
2831         if (separate_irq_context(curr, hlock)) {
2832                 chain_key = 0;
2833                 chain_head = 1;
2834         }
2835         chain_key = iterate_chain_key(chain_key, id);
2836
2837         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2838                 return 0;
2839
2840         curr->curr_chain_key = chain_key;
2841         curr->lockdep_depth++;
2842         check_chain_key(curr);
2843 #ifdef CONFIG_DEBUG_LOCKDEP
2844         if (unlikely(!debug_locks))
2845                 return 0;
2846 #endif
2847         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2848                 debug_locks_off();
2849                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2850                 printk("turning off the locking correctness validator.\n");
2851                 dump_stack();
2852                 return 0;
2853         }
2854
2855         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2856                 max_lockdep_depth = curr->lockdep_depth;
2857
2858         return 1;
2859 }
2860
2861 static int
2862 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2863                            unsigned long ip)
2864 {
2865         if (!debug_locks_off())
2866                 return 0;
2867         if (debug_locks_silent)
2868                 return 0;
2869
2870         printk("\n=====================================\n");
2871         printk(  "[ BUG: bad unlock balance detected! ]\n");
2872         printk(  "-------------------------------------\n");
2873         printk("%s/%d is trying to release lock (",
2874                 curr->comm, task_pid_nr(curr));
2875         print_lockdep_cache(lock);
2876         printk(") at:\n");
2877         print_ip_sym(ip);
2878         printk("but there are no more locks to release!\n");
2879         printk("\nother info that might help us debug this:\n");
2880         lockdep_print_held_locks(curr);
2881
2882         printk("\nstack backtrace:\n");
2883         dump_stack();
2884
2885         return 0;
2886 }
2887
2888 /*
2889  * Common debugging checks for both nested and non-nested unlock:
2890  */
2891 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2892                         unsigned long ip)
2893 {
2894         if (unlikely(!debug_locks))
2895                 return 0;
2896         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2897                 return 0;
2898
2899         if (curr->lockdep_depth <= 0)
2900                 return print_unlock_inbalance_bug(curr, lock, ip);
2901
2902         return 1;
2903 }
2904
2905 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
2906 {
2907         if (hlock->instance == lock)
2908                 return 1;
2909
2910         if (hlock->references) {
2911                 struct lock_class *class = lock->class_cache;
2912
2913                 if (!class)
2914                         class = look_up_lock_class(lock, 0);
2915
2916                 if (DEBUG_LOCKS_WARN_ON(!class))
2917                         return 0;
2918
2919                 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
2920                         return 0;
2921
2922                 if (hlock->class_idx == class - lock_classes + 1)
2923                         return 1;
2924         }
2925
2926         return 0;
2927 }
2928
2929 static int
2930 __lock_set_class(struct lockdep_map *lock, const char *name,
2931                  struct lock_class_key *key, unsigned int subclass,
2932                  unsigned long ip)
2933 {
2934         struct task_struct *curr = current;
2935         struct held_lock *hlock, *prev_hlock;
2936         struct lock_class *class;
2937         unsigned int depth;
2938         int i;
2939
2940         depth = curr->lockdep_depth;
2941         if (DEBUG_LOCKS_WARN_ON(!depth))
2942                 return 0;
2943
2944         prev_hlock = NULL;
2945         for (i = depth-1; i >= 0; i--) {
2946                 hlock = curr->held_locks + i;
2947                 /*
2948                  * We must not cross into another context:
2949                  */
2950                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2951                         break;
2952                 if (match_held_lock(hlock, lock))
2953                         goto found_it;
2954                 prev_hlock = hlock;
2955         }
2956         return print_unlock_inbalance_bug(curr, lock, ip);
2957
2958 found_it:
2959         lockdep_init_map(lock, name, key, 0);
2960         class = register_lock_class(lock, subclass, 0);
2961         hlock->class_idx = class - lock_classes + 1;
2962
2963         curr->lockdep_depth = i;
2964         curr->curr_chain_key = hlock->prev_chain_key;
2965
2966         for (; i < depth; i++) {
2967                 hlock = curr->held_locks + i;
2968                 if (!__lock_acquire(hlock->instance,
2969                         hlock_class(hlock)->subclass, hlock->trylock,
2970                                 hlock->read, hlock->check, hlock->hardirqs_off,
2971                                 hlock->nest_lock, hlock->acquire_ip,
2972                                 hlock->references))
2973                         return 0;
2974         }
2975
2976         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2977                 return 0;
2978         return 1;
2979 }
2980
2981 /*
2982  * Remove the lock to the list of currently held locks in a
2983  * potentially non-nested (out of order) manner. This is a
2984  * relatively rare operation, as all the unlock APIs default
2985  * to nested mode (which uses lock_release()):
2986  */
2987 static int
2988 lock_release_non_nested(struct task_struct *curr,
2989                         struct lockdep_map *lock, unsigned long ip)
2990 {
2991         struct held_lock *hlock, *prev_hlock;
2992         unsigned int depth;
2993         int i;
2994
2995         /*
2996          * Check whether the lock exists in the current stack
2997          * of held locks:
2998          */
2999         depth = curr->lockdep_depth;
3000         if (DEBUG_LOCKS_WARN_ON(!depth))
3001                 return 0;
3002
3003         prev_hlock = NULL;
3004         for (i = depth-1; i >= 0; i--) {
3005                 hlock = curr->held_locks + i;
3006                 /*
3007                  * We must not cross into another context:
3008                  */
3009                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3010                         break;
3011                 if (match_held_lock(hlock, lock))
3012                         goto found_it;
3013                 prev_hlock = hlock;
3014         }
3015         return print_unlock_inbalance_bug(curr, lock, ip);
3016
3017 found_it:
3018         if (hlock->instance == lock)
3019                 lock_release_holdtime(hlock);
3020
3021         if (hlock->references) {
3022                 hlock->references--;
3023                 if (hlock->references) {
3024                         /*
3025                          * We had, and after removing one, still have
3026                          * references, the current lock stack is still
3027                          * valid. We're done!
3028                          */
3029                         return 1;
3030                 }
3031         }
3032
3033         /*
3034          * We have the right lock to unlock, 'hlock' points to it.
3035          * Now we remove it from the stack, and add back the other
3036          * entries (if any), recalculating the hash along the way:
3037          */
3038
3039         curr->lockdep_depth = i;
3040         curr->curr_chain_key = hlock->prev_chain_key;
3041
3042         for (i++; i < depth; i++) {
3043                 hlock = curr->held_locks + i;
3044                 if (!__lock_acquire(hlock->instance,
3045                         hlock_class(hlock)->subclass, hlock->trylock,
3046                                 hlock->read, hlock->check, hlock->hardirqs_off,
3047                                 hlock->nest_lock, hlock->acquire_ip,
3048                                 hlock->references))
3049                         return 0;
3050         }
3051
3052         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3053                 return 0;
3054         return 1;
3055 }
3056
3057 /*
3058  * Remove the lock to the list of currently held locks - this gets
3059  * called on mutex_unlock()/spin_unlock*() (or on a failed
3060  * mutex_lock_interruptible()). This is done for unlocks that nest
3061  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3062  */
3063 static int lock_release_nested(struct task_struct *curr,
3064                                struct lockdep_map *lock, unsigned long ip)
3065 {
3066         struct held_lock *hlock;
3067         unsigned int depth;
3068
3069         /*
3070          * Pop off the top of the lock stack:
3071          */
3072         depth = curr->lockdep_depth - 1;
3073         hlock = curr->held_locks + depth;
3074
3075         /*
3076          * Is the unlock non-nested:
3077          */
3078         if (hlock->instance != lock || hlock->references)
3079                 return lock_release_non_nested(curr, lock, ip);
3080         curr->lockdep_depth--;
3081
3082         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3083                 return 0;
3084
3085         curr->curr_chain_key = hlock->prev_chain_key;
3086
3087         lock_release_holdtime(hlock);
3088
3089 #ifdef CONFIG_DEBUG_LOCKDEP
3090         hlock->prev_chain_key = 0;
3091         hlock->class_idx = 0;
3092         hlock->acquire_ip = 0;
3093         hlock->irq_context = 0;
3094 #endif
3095         return 1;
3096 }
3097
3098 /*
3099  * Remove the lock to the list of currently held locks - this gets
3100  * called on mutex_unlock()/spin_unlock*() (or on a failed
3101  * mutex_lock_interruptible()). This is done for unlocks that nest
3102  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3103  */
3104 static void
3105 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3106 {
3107         struct task_struct *curr = current;
3108
3109         if (!check_unlock(curr, lock, ip))
3110                 return;
3111
3112         if (nested) {
3113                 if (!lock_release_nested(curr, lock, ip))
3114                         return;
3115         } else {
3116                 if (!lock_release_non_nested(curr, lock, ip))
3117                         return;
3118         }
3119
3120         check_chain_key(curr);
3121 }
3122
3123 static int __lock_is_held(struct lockdep_map *lock)
3124 {
3125         struct task_struct *curr = current;
3126         int i;
3127
3128         for (i = 0; i < curr->lockdep_depth; i++) {
3129                 struct held_lock *hlock = curr->held_locks + i;
3130
3131                 if (match_held_lock(hlock, lock))
3132                         return 1;
3133         }
3134
3135         return 0;
3136 }
3137
3138 /*
3139  * Check whether we follow the irq-flags state precisely:
3140  */
3141 static void check_flags(unsigned long flags)
3142 {
3143 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3144     defined(CONFIG_TRACE_IRQFLAGS)
3145         if (!debug_locks)
3146                 return;
3147
3148         if (irqs_disabled_flags(flags)) {
3149                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3150                         printk("possible reason: unannotated irqs-off.\n");
3151                 }
3152         } else {
3153                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3154                         printk("possible reason: unannotated irqs-on.\n");
3155                 }
3156         }
3157
3158         /*
3159          * We dont accurately track softirq state in e.g.
3160          * hardirq contexts (such as on 4KSTACKS), so only
3161          * check if not in hardirq contexts:
3162          */
3163         if (!hardirq_count()) {
3164                 if (softirq_count())
3165                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3166                 else
3167                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3168         }
3169
3170         if (!debug_locks)
3171                 print_irqtrace_events(current);
3172 #endif
3173 }
3174
3175 void lock_set_class(struct lockdep_map *lock, const char *name,
3176                     struct lock_class_key *key, unsigned int subclass,
3177                     unsigned long ip)
3178 {
3179         unsigned long flags;
3180
3181         if (unlikely(current->lockdep_recursion))
3182                 return;
3183
3184         raw_local_irq_save(flags);
3185         current->lockdep_recursion = 1;
3186         check_flags(flags);
3187         if (__lock_set_class(lock, name, key, subclass, ip))
3188                 check_chain_key(current);
3189         current->lockdep_recursion = 0;
3190         raw_local_irq_restore(flags);
3191 }
3192 EXPORT_SYMBOL_GPL(lock_set_class);
3193
3194 /*
3195  * We are not always called with irqs disabled - do that here,
3196  * and also avoid lockdep recursion:
3197  */
3198 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3199                           int trylock, int read, int check,
3200                           struct lockdep_map *nest_lock, unsigned long ip)
3201 {
3202         unsigned long flags;
3203
3204         if (unlikely(current->lockdep_recursion))
3205                 return;
3206
3207         raw_local_irq_save(flags);
3208         check_flags(flags);
3209
3210         current->lockdep_recursion = 1;
3211         trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3212         __lock_acquire(lock, subclass, trylock, read, check,
3213                        irqs_disabled_flags(flags), nest_lock, ip, 0);
3214         current->lockdep_recursion = 0;
3215         raw_local_irq_restore(flags);
3216 }
3217 EXPORT_SYMBOL_GPL(lock_acquire);
3218
3219 void lock_release(struct lockdep_map *lock, int nested,
3220                           unsigned long ip)
3221 {
3222         unsigned long flags;
3223
3224         if (unlikely(current->lockdep_recursion))
3225                 return;
3226
3227         raw_local_irq_save(flags);
3228         check_flags(flags);
3229         current->lockdep_recursion = 1;
3230         trace_lock_release(lock, ip);
3231         __lock_release(lock, nested, ip);
3232         current->lockdep_recursion = 0;
3233         raw_local_irq_restore(flags);
3234 }
3235 EXPORT_SYMBOL_GPL(lock_release);
3236
3237 int lock_is_held(struct lockdep_map *lock)
3238 {
3239         unsigned long flags;
3240         int ret = 0;
3241
3242         if (unlikely(current->lockdep_recursion))
3243                 return ret;
3244
3245         raw_local_irq_save(flags);
3246         check_flags(flags);
3247
3248         current->lockdep_recursion = 1;
3249         ret = __lock_is_held(lock);
3250         current->lockdep_recursion = 0;
3251         raw_local_irq_restore(flags);
3252
3253         return ret;
3254 }
3255 EXPORT_SYMBOL_GPL(lock_is_held);
3256
3257 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3258 {
3259         current->lockdep_reclaim_gfp = gfp_mask;
3260 }
3261
3262 void lockdep_clear_current_reclaim_state(void)
3263 {
3264         current->lockdep_reclaim_gfp = 0;
3265 }
3266
3267 #ifdef CONFIG_LOCK_STAT
3268 static int
3269 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3270                            unsigned long ip)
3271 {
3272         if (!debug_locks_off())
3273                 return 0;
3274         if (debug_locks_silent)
3275                 return 0;
3276
3277         printk("\n=================================\n");
3278         printk(  "[ BUG: bad contention detected! ]\n");
3279         printk(  "---------------------------------\n");
3280         printk("%s/%d is trying to contend lock (",
3281                 curr->comm, task_pid_nr(curr));
3282         print_lockdep_cache(lock);
3283         printk(") at:\n");
3284         print_ip_sym(ip);
3285         printk("but there are no locks held!\n");
3286         printk("\nother info that might help us debug this:\n");
3287         lockdep_print_held_locks(curr);
3288
3289         printk("\nstack backtrace:\n");
3290         dump_stack();
3291
3292         return 0;
3293 }
3294
3295 static void
3296 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3297 {
3298         struct task_struct *curr = current;
3299         struct held_lock *hlock, *prev_hlock;
3300         struct lock_class_stats *stats;
3301         unsigned int depth;
3302         int i, contention_point, contending_point;
3303
3304         depth = curr->lockdep_depth;
3305         if (DEBUG_LOCKS_WARN_ON(!depth))
3306                 return;
3307
3308         prev_hlock = NULL;
3309         for (i = depth-1; i >= 0; i--) {
3310                 hlock = curr->held_locks + i;
3311                 /*
3312                  * We must not cross into another context:
3313                  */
3314                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3315                         break;
3316                 if (match_held_lock(hlock, lock))
3317                         goto found_it;
3318                 prev_hlock = hlock;
3319         }
3320         print_lock_contention_bug(curr, lock, ip);
3321         return;
3322
3323 found_it:
3324         if (hlock->instance != lock)
3325                 return;
3326
3327         hlock->waittime_stamp = lockstat_clock();
3328
3329         contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3330         contending_point = lock_point(hlock_class(hlock)->contending_point,
3331                                       lock->ip);
3332
3333         stats = get_lock_stats(hlock_class(hlock));
3334         if (contention_point < LOCKSTAT_POINTS)
3335                 stats->contention_point[contention_point]++;
3336         if (contending_point < LOCKSTAT_POINTS)
3337                 stats->contending_point[contending_point]++;
3338         if (lock->cpu != smp_processor_id())
3339                 stats->bounces[bounce_contended + !!hlock->read]++;
3340         put_lock_stats(stats);
3341 }
3342
3343 static void
3344 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3345 {
3346         struct task_struct *curr = current;
3347         struct held_lock *hlock, *prev_hlock;
3348         struct lock_class_stats *stats;
3349         unsigned int depth;
3350         u64 now, waittime = 0;
3351         int i, cpu;
3352
3353         depth = curr->lockdep_depth;
3354         if (DEBUG_LOCKS_WARN_ON(!depth))
3355                 return;
3356
3357         prev_hlock = NULL;
3358         for (i = depth-1; i >= 0; i--) {
3359                 hlock = curr->held_locks + i;
3360                 /*
3361                  * We must not cross into another context:
3362                  */
3363                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3364                         break;
3365                 if (match_held_lock(hlock, lock))
3366                         goto found_it;
3367                 prev_hlock = hlock;
3368         }
3369         print_lock_contention_bug(curr, lock, _RET_IP_);
3370         return;
3371
3372 found_it:
3373         if (hlock->instance != lock)
3374                 return;
3375
3376         cpu = smp_processor_id();
3377         if (hlock->waittime_stamp) {
3378                 now = lockstat_clock();
3379                 waittime = now - hlock->waittime_stamp;
3380                 hlock->holdtime_stamp = now;
3381         }
3382
3383         trace_lock_acquired(lock, ip);
3384
3385         stats = get_lock_stats(hlock_class(hlock));
3386         if (waittime) {
3387                 if (hlock->read)
3388                         lock_time_inc(&stats->read_waittime, waittime);
3389                 else
3390                         lock_time_inc(&stats->write_waittime, waittime);
3391         }
3392         if (lock->cpu != cpu)
3393                 stats->bounces[bounce_acquired + !!hlock->read]++;
3394         put_lock_stats(stats);
3395
3396         lock->cpu = cpu;
3397         lock->ip = ip;
3398 }
3399
3400 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3401 {
3402         unsigned long flags;
3403
3404         if (unlikely(!lock_stat))
3405                 return;
3406
3407         if (unlikely(current->lockdep_recursion))
3408                 return;
3409
3410         raw_local_irq_save(flags);
3411         check_flags(flags);
3412         current->lockdep_recursion = 1;
3413         trace_lock_contended(lock, ip);
3414         __lock_contended(lock, ip);
3415         current->lockdep_recursion = 0;
3416         raw_local_irq_restore(flags);
3417 }
3418 EXPORT_SYMBOL_GPL(lock_contended);
3419
3420 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3421 {
3422         unsigned long flags;
3423
3424         if (unlikely(!lock_stat))
3425                 return;
3426
3427         if (unlikely(current->lockdep_recursion))
3428                 return;
3429
3430         raw_local_irq_save(flags);
3431         check_flags(flags);
3432         current->lockdep_recursion = 1;
3433         __lock_acquired(lock, ip);
3434         current->lockdep_recursion = 0;
3435         raw_local_irq_restore(flags);
3436 }
3437 EXPORT_SYMBOL_GPL(lock_acquired);
3438 #endif
3439
3440 /*
3441  * Used by the testsuite, sanitize the validator state
3442  * after a simulated failure:
3443  */
3444
3445 void lockdep_reset(void)
3446 {
3447         unsigned long flags;
3448         int i;
3449
3450         raw_local_irq_save(flags);
3451         current->curr_chain_key = 0;
3452         current->lockdep_depth = 0;
3453         current->lockdep_recursion = 0;
3454         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3455         nr_hardirq_chains = 0;
3456         nr_softirq_chains = 0;
3457         nr_process_chains = 0;
3458         debug_locks = 1;
3459         for (i = 0; i < CHAINHASH_SIZE; i++)
3460                 INIT_LIST_HEAD(chainhash_table + i);
3461         raw_local_irq_restore(flags);
3462 }
3463
3464 static void zap_class(struct lock_class *class)
3465 {
3466         int i;
3467
3468         /*
3469          * Remove all dependencies this lock is
3470          * involved in:
3471          */
3472         for (i = 0; i < nr_list_entries; i++) {
3473                 if (list_entries[i].class == class)
3474                         list_del_rcu(&list_entries[i].entry);
3475         }
3476         /*
3477          * Unhash the class and remove it from the all_lock_classes list:
3478          */
3479         list_del_rcu(&class->hash_entry);
3480         list_del_rcu(&class->lock_entry);
3481
3482         class->key = NULL;
3483 }
3484
3485 static inline int within(const void *addr, void *start, unsigned long size)
3486 {
3487         return addr >= start && addr < start + size;
3488 }
3489
3490 void lockdep_free_key_range(void *start, unsigned long size)
3491 {
3492         struct lock_class *class, *next;
3493         struct list_head *head;
3494         unsigned long flags;
3495         int i;
3496         int locked;
3497
3498         raw_local_irq_save(flags);
3499         locked = graph_lock();
3500
3501         /*
3502          * Unhash all classes that were created by this module:
3503          */
3504         for (i = 0; i < CLASSHASH_SIZE; i++) {
3505                 head = classhash_table + i;
3506                 if (list_empty(head))
3507                         continue;
3508                 list_for_each_entry_safe(class, next, head, hash_entry) {
3509                         if (within(class->key, start, size))
3510                                 zap_class(class);
3511                         else if (within(class->name, start, size))
3512                                 zap_class(class);
3513                 }
3514         }
3515
3516         if (locked)
3517                 graph_unlock();
3518         raw_local_irq_restore(flags);
3519 }
3520
3521 void lockdep_reset_lock(struct lockdep_map *lock)
3522 {
3523         struct lock_class *class, *next;
3524         struct list_head *head;
3525         unsigned long flags;
3526         int i, j;
3527         int locked;
3528
3529         raw_local_irq_save(flags);
3530
3531         /*
3532          * Remove all classes this lock might have:
3533          */
3534         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3535                 /*
3536                  * If the class exists we look it up and zap it:
3537                  */
3538                 class = look_up_lock_class(lock, j);
3539                 if (class)
3540                         zap_class(class);
3541         }
3542         /*
3543          * Debug check: in the end all mapped classes should
3544          * be gone.
3545          */
3546         locked = graph_lock();
3547         for (i = 0; i < CLASSHASH_SIZE; i++) {
3548                 head = classhash_table + i;
3549                 if (list_empty(head))
3550                         continue;
3551                 list_for_each_entry_safe(class, next, head, hash_entry) {
3552                         if (unlikely(class == lock->class_cache)) {
3553                                 if (debug_locks_off_graph_unlock())
3554                                         WARN_ON(1);
3555                                 goto out_restore;
3556                         }
3557                 }
3558         }
3559         if (locked)
3560                 graph_unlock();
3561
3562 out_restore:
3563         raw_local_irq_restore(flags);
3564 }
3565
3566 void lockdep_init(void)
3567 {
3568         int i;
3569
3570         /*
3571          * Some architectures have their own start_kernel()
3572          * code which calls lockdep_init(), while we also
3573          * call lockdep_init() from the start_kernel() itself,
3574          * and we want to initialize the hashes only once:
3575          */
3576         if (lockdep_initialized)
3577                 return;
3578
3579         for (i = 0; i < CLASSHASH_SIZE; i++)
3580                 INIT_LIST_HEAD(classhash_table + i);
3581
3582         for (i = 0; i < CHAINHASH_SIZE; i++)
3583                 INIT_LIST_HEAD(chainhash_table + i);
3584
3585         lockdep_initialized = 1;
3586 }
3587
3588 void __init lockdep_info(void)
3589 {
3590         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3591
3592         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3593         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3594         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3595         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3596         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3597         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3598         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3599
3600         printk(" memory used by lock dependency info: %lu kB\n",
3601                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3602                 sizeof(struct list_head) * CLASSHASH_SIZE +
3603                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3604                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3605                 sizeof(struct list_head) * CHAINHASH_SIZE
3606 #ifdef CONFIG_PROVE_LOCKING
3607                 + sizeof(struct circular_queue)
3608 #endif
3609                 ) / 1024
3610                 );
3611
3612         printk(" per task-struct memory footprint: %lu bytes\n",
3613                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3614
3615 #ifdef CONFIG_DEBUG_LOCKDEP
3616         if (lockdep_init_error) {
3617                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3618                 printk("Call stack leading to lockdep invocation was:\n");
3619                 print_stack_trace(&lockdep_init_trace, 0);
3620         }
3621 #endif
3622 }
3623
3624 static void
3625 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3626                      const void *mem_to, struct held_lock *hlock)
3627 {
3628         if (!debug_locks_off())
3629                 return;
3630         if (debug_locks_silent)
3631                 return;
3632
3633         printk("\n=========================\n");
3634         printk(  "[ BUG: held lock freed! ]\n");
3635         printk(  "-------------------------\n");
3636         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3637                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3638         print_lock(hlock);
3639         lockdep_print_held_locks(curr);
3640
3641         printk("\nstack backtrace:\n");
3642         dump_stack();
3643 }
3644
3645 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3646                                 const void* lock_from, unsigned long lock_len)
3647 {
3648         return lock_from + lock_len <= mem_from ||
3649                 mem_from + mem_len <= lock_from;
3650 }
3651
3652 /*
3653  * Called when kernel memory is freed (or unmapped), or if a lock
3654  * is destroyed or reinitialized - this code checks whether there is
3655  * any held lock in the memory range of <from> to <to>:
3656  */
3657 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3658 {
3659         struct task_struct *curr = current;
3660         struct held_lock *hlock;
3661         unsigned long flags;
3662         int i;
3663
3664         if (unlikely(!debug_locks))
3665                 return;
3666
3667         local_irq_save(flags);
3668         for (i = 0; i < curr->lockdep_depth; i++) {
3669                 hlock = curr->held_locks + i;
3670
3671                 if (not_in_range(mem_from, mem_len, hlock->instance,
3672                                         sizeof(*hlock->instance)))
3673                         continue;
3674
3675                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3676                 break;
3677         }
3678         local_irq_restore(flags);
3679 }
3680 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3681
3682 static void print_held_locks_bug(struct task_struct *curr)
3683 {
3684         if (!debug_locks_off())
3685                 return;
3686         if (debug_locks_silent)
3687                 return;
3688
3689         printk("\n=====================================\n");
3690         printk(  "[ BUG: lock held at task exit time! ]\n");
3691         printk(  "-------------------------------------\n");
3692         printk("%s/%d is exiting with locks still held!\n",
3693                 curr->comm, task_pid_nr(curr));
3694         lockdep_print_held_locks(curr);
3695
3696         printk("\nstack backtrace:\n");
3697         dump_stack();
3698 }
3699
3700 void debug_check_no_locks_held(struct task_struct *task)
3701 {
3702         if (unlikely(task->lockdep_depth > 0))
3703                 print_held_locks_bug(task);
3704 }
3705
3706 void debug_show_all_locks(void)
3707 {
3708         struct task_struct *g, *p;
3709         int count = 10;
3710         int unlock = 1;
3711
3712         if (unlikely(!debug_locks)) {
3713                 printk("INFO: lockdep is turned off.\n");
3714                 return;
3715         }
3716         printk("\nShowing all locks held in the system:\n");
3717
3718         /*
3719          * Here we try to get the tasklist_lock as hard as possible,
3720          * if not successful after 2 seconds we ignore it (but keep
3721          * trying). This is to enable a debug printout even if a
3722          * tasklist_lock-holding task deadlocks or crashes.
3723          */
3724 retry:
3725         if (!read_trylock(&tasklist_lock)) {
3726                 if (count == 10)
3727                         printk("hm, tasklist_lock locked, retrying... ");
3728                 if (count) {
3729                         count--;
3730                         printk(" #%d", 10-count);
3731                         mdelay(200);
3732                         goto retry;
3733                 }
3734                 printk(" ignoring it.\n");
3735                 unlock = 0;
3736         } else {
3737                 if (count != 10)
3738                         printk(KERN_CONT " locked it.\n");
3739         }
3740
3741         do_each_thread(g, p) {
3742                 /*
3743                  * It's not reliable to print a task's held locks
3744                  * if it's not sleeping (or if it's not the current
3745                  * task):
3746                  */
3747                 if (p->state == TASK_RUNNING && p != current)
3748                         continue;
3749                 if (p->lockdep_depth)
3750                         lockdep_print_held_locks(p);
3751                 if (!unlock)
3752                         if (read_trylock(&tasklist_lock))
3753                                 unlock = 1;
3754         } while_each_thread(g, p);
3755
3756         printk("\n");
3757         printk("=============================================\n\n");
3758
3759         if (unlock)
3760                 read_unlock(&tasklist_lock);
3761 }
3762 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3763
3764 /*
3765  * Careful: only use this function if you are sure that
3766  * the task cannot run in parallel!
3767  */
3768 void __debug_show_held_locks(struct task_struct *task)
3769 {
3770         if (unlikely(!debug_locks)) {
3771                 printk("INFO: lockdep is turned off.\n");
3772                 return;
3773         }
3774         lockdep_print_held_locks(task);
3775 }
3776 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3777
3778 void debug_show_held_locks(struct task_struct *task)
3779 {
3780                 __debug_show_held_locks(task);
3781 }
3782 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3783
3784 void lockdep_sys_exit(void)
3785 {
3786         struct task_struct *curr = current;
3787
3788         if (unlikely(curr->lockdep_depth)) {
3789                 if (!debug_locks_off())
3790                         return;
3791                 printk("\n================================================\n");
3792                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3793                 printk(  "------------------------------------------------\n");
3794                 printk("%s/%d is leaving the kernel with locks still held!\n",
3795                                 curr->comm, curr->pid);
3796                 lockdep_print_held_locks(curr);
3797         }
3798 }
3799
3800 void lockdep_rcu_dereference(const char *file, const int line)
3801 {
3802         struct task_struct *curr = current;
3803
3804         if (!debug_locks_off())
3805                 return;
3806         printk("\n===================================================\n");
3807         printk(  "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3808         printk(  "---------------------------------------------------\n");
3809         printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3810                         file, line);
3811         printk("\nother info that might help us debug this:\n\n");
3812         printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
3813         lockdep_print_held_locks(curr);
3814         printk("\nstack backtrace:\n");
3815         dump_stack();
3816 }
3817 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);