media: tegra: Tegra videobuf2
[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 #include <linux/kmemcheck.h>
48
49 #include <asm/sections.h>
50
51 #include "lockdep_internals.h"
52
53 #define CREATE_TRACE_POINTS
54 #include <trace/events/lock.h>
55
56 #ifdef CONFIG_PROVE_LOCKING
57 int prove_locking = 1;
58 module_param(prove_locking, int, 0644);
59 #else
60 #define prove_locking 0
61 #endif
62
63 #ifdef CONFIG_LOCK_STAT
64 int lock_stat = 1;
65 module_param(lock_stat, int, 0644);
66 #else
67 #define lock_stat 0
68 #endif
69
70 /*
71  * lockdep_lock: protects the lockdep graph, the hashes and the
72  *               class/list/hash allocators.
73  *
74  * This is one of the rare exceptions where it's justified
75  * to use a raw spinlock - we really dont want the spinlock
76  * code to recurse back into the lockdep code...
77  */
78 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
79
80 static int graph_lock(void)
81 {
82         arch_spin_lock(&lockdep_lock);
83         /*
84          * Make sure that if another CPU detected a bug while
85          * walking the graph we dont change it (while the other
86          * CPU is busy printing out stuff with the graph lock
87          * dropped already)
88          */
89         if (!debug_locks) {
90                 arch_spin_unlock(&lockdep_lock);
91                 return 0;
92         }
93         /* prevent any recursions within lockdep from causing deadlocks */
94         current->lockdep_recursion++;
95         return 1;
96 }
97
98 static inline int graph_unlock(void)
99 {
100         if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
101                 return DEBUG_LOCKS_WARN_ON(1);
102
103         current->lockdep_recursion--;
104         arch_spin_unlock(&lockdep_lock);
105         return 0;
106 }
107
108 /*
109  * Turn lock debugging off and return with 0 if it was off already,
110  * and also release the graph lock:
111  */
112 static inline int debug_locks_off_graph_unlock(void)
113 {
114         int ret = debug_locks_off();
115
116         arch_spin_unlock(&lockdep_lock);
117
118         return ret;
119 }
120
121 static int lockdep_initialized;
122
123 unsigned long nr_list_entries;
124 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
125
126 /*
127  * All data structures here are protected by the global debug_lock.
128  *
129  * Mutex key structs only get allocated, once during bootup, and never
130  * get freed - this significantly simplifies the debugging code.
131  */
132 unsigned long nr_lock_classes;
133 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
134
135 static inline struct lock_class *hlock_class(struct held_lock *hlock)
136 {
137         if (!hlock->class_idx) {
138                 DEBUG_LOCKS_WARN_ON(1);
139                 return NULL;
140         }
141         return lock_classes + hlock->class_idx - 1;
142 }
143
144 #ifdef CONFIG_LOCK_STAT
145 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
146                       cpu_lock_stats);
147
148 static inline u64 lockstat_clock(void)
149 {
150         return local_clock();
151 }
152
153 static int lock_point(unsigned long points[], unsigned long ip)
154 {
155         int i;
156
157         for (i = 0; i < LOCKSTAT_POINTS; i++) {
158                 if (points[i] == 0) {
159                         points[i] = ip;
160                         break;
161                 }
162                 if (points[i] == ip)
163                         break;
164         }
165
166         return i;
167 }
168
169 static void lock_time_inc(struct lock_time *lt, u64 time)
170 {
171         if (time > lt->max)
172                 lt->max = time;
173
174         if (time < lt->min || !lt->nr)
175                 lt->min = time;
176
177         lt->total += time;
178         lt->nr++;
179 }
180
181 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
182 {
183         if (!src->nr)
184                 return;
185
186         if (src->max > dst->max)
187                 dst->max = src->max;
188
189         if (src->min < dst->min || !dst->nr)
190                 dst->min = src->min;
191
192         dst->total += src->total;
193         dst->nr += src->nr;
194 }
195
196 struct lock_class_stats lock_stats(struct lock_class *class)
197 {
198         struct lock_class_stats stats;
199         int cpu, i;
200
201         memset(&stats, 0, sizeof(struct lock_class_stats));
202         for_each_possible_cpu(cpu) {
203                 struct lock_class_stats *pcs =
204                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
205
206                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
207                         stats.contention_point[i] += pcs->contention_point[i];
208
209                 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
210                         stats.contending_point[i] += pcs->contending_point[i];
211
212                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
213                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
214
215                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
216                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
217
218                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
219                         stats.bounces[i] += pcs->bounces[i];
220         }
221
222         return stats;
223 }
224
225 void clear_lock_stats(struct lock_class *class)
226 {
227         int cpu;
228
229         for_each_possible_cpu(cpu) {
230                 struct lock_class_stats *cpu_stats =
231                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
232
233                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
234         }
235         memset(class->contention_point, 0, sizeof(class->contention_point));
236         memset(class->contending_point, 0, sizeof(class->contending_point));
237 }
238
239 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
240 {
241         return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
242 }
243
244 static void put_lock_stats(struct lock_class_stats *stats)
245 {
246         put_cpu_var(cpu_lock_stats);
247 }
248
249 static void lock_release_holdtime(struct held_lock *hlock)
250 {
251         struct lock_class_stats *stats;
252         u64 holdtime;
253
254         if (!lock_stat)
255                 return;
256
257         holdtime = lockstat_clock() - hlock->holdtime_stamp;
258
259         stats = get_lock_stats(hlock_class(hlock));
260         if (hlock->read)
261                 lock_time_inc(&stats->read_holdtime, holdtime);
262         else
263                 lock_time_inc(&stats->write_holdtime, holdtime);
264         put_lock_stats(stats);
265 }
266 #else
267 static inline void lock_release_holdtime(struct held_lock *hlock)
268 {
269 }
270 #endif
271
272 /*
273  * We keep a global list of all lock classes. The list only grows,
274  * never shrinks. The list is only accessed with the lockdep
275  * spinlock lock held.
276  */
277 LIST_HEAD(all_lock_classes);
278
279 /*
280  * The lockdep classes are in a hash-table as well, for fast lookup:
281  */
282 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
283 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
284 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
285 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
286
287 static struct list_head classhash_table[CLASSHASH_SIZE];
288
289 /*
290  * We put the lock dependency chains into a hash-table as well, to cache
291  * their existence:
292  */
293 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
294 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
295 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
296 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
297
298 static struct list_head chainhash_table[CHAINHASH_SIZE];
299
300 /*
301  * The hash key of the lock dependency chains is a hash itself too:
302  * it's a hash of all locks taken up to that lock, including that lock.
303  * It's a 64-bit hash, because it's important for the keys to be
304  * unique.
305  */
306 #define iterate_chain_key(key1, key2) \
307         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
308         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
309         (key2))
310
311 void lockdep_off(void)
312 {
313         current->lockdep_recursion++;
314 }
315 EXPORT_SYMBOL(lockdep_off);
316
317 void lockdep_on(void)
318 {
319         current->lockdep_recursion--;
320 }
321 EXPORT_SYMBOL(lockdep_on);
322
323 /*
324  * Debugging switches:
325  */
326
327 #define VERBOSE                 0
328 #define VERY_VERBOSE            0
329
330 #if VERBOSE
331 # define HARDIRQ_VERBOSE        1
332 # define SOFTIRQ_VERBOSE        1
333 # define RECLAIM_VERBOSE        1
334 #else
335 # define HARDIRQ_VERBOSE        0
336 # define SOFTIRQ_VERBOSE        0
337 # define RECLAIM_VERBOSE        0
338 #endif
339
340 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
341 /*
342  * Quick filtering for interesting events:
343  */
344 static int class_filter(struct lock_class *class)
345 {
346 #if 0
347         /* Example */
348         if (class->name_version == 1 &&
349                         !strcmp(class->name, "lockname"))
350                 return 1;
351         if (class->name_version == 1 &&
352                         !strcmp(class->name, "&struct->lockfield"))
353                 return 1;
354 #endif
355         /* Filter everything else. 1 would be to allow everything else */
356         return 0;
357 }
358 #endif
359
360 static int verbose(struct lock_class *class)
361 {
362 #if VERBOSE
363         return class_filter(class);
364 #endif
365         return 0;
366 }
367
368 /*
369  * Stack-trace: tightly packed array of stack backtrace
370  * addresses. Protected by the graph_lock.
371  */
372 unsigned long nr_stack_trace_entries;
373 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
374
375 static int save_trace(struct stack_trace *trace)
376 {
377         trace->nr_entries = 0;
378         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
379         trace->entries = stack_trace + nr_stack_trace_entries;
380
381         trace->skip = 3;
382
383         save_stack_trace(trace);
384
385         /*
386          * Some daft arches put -1 at the end to indicate its a full trace.
387          *
388          * <rant> this is buggy anyway, since it takes a whole extra entry so a
389          * complete trace that maxes out the entries provided will be reported
390          * as incomplete, friggin useless </rant>
391          */
392         if (trace->nr_entries != 0 &&
393             trace->entries[trace->nr_entries-1] == ULONG_MAX)
394                 trace->nr_entries--;
395
396         trace->max_entries = trace->nr_entries;
397
398         nr_stack_trace_entries += trace->nr_entries;
399
400         if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
401                 if (!debug_locks_off_graph_unlock())
402                         return 0;
403
404                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
405                 printk("turning off the locking correctness validator.\n");
406                 dump_stack();
407
408                 return 0;
409         }
410
411         return 1;
412 }
413
414 unsigned int nr_hardirq_chains;
415 unsigned int nr_softirq_chains;
416 unsigned int nr_process_chains;
417 unsigned int max_lockdep_depth;
418
419 #ifdef CONFIG_DEBUG_LOCKDEP
420 /*
421  * We cannot printk in early bootup code. Not even early_printk()
422  * might work. So we mark any initialization errors and printk
423  * about it later on, in lockdep_info().
424  */
425 static int lockdep_init_error;
426 static unsigned long lockdep_init_trace_data[20];
427 static struct stack_trace lockdep_init_trace = {
428         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
429         .entries = lockdep_init_trace_data,
430 };
431
432 /*
433  * Various lockdep statistics:
434  */
435 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
436 #endif
437
438 /*
439  * Locking printouts:
440  */
441
442 #define __USAGE(__STATE)                                                \
443         [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
444         [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
445         [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
446         [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
447
448 static const char *usage_str[] =
449 {
450 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
451 #include "lockdep_states.h"
452 #undef LOCKDEP_STATE
453         [LOCK_USED] = "INITIAL USE",
454 };
455
456 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
457 {
458         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
459 }
460
461 static inline unsigned long lock_flag(enum lock_usage_bit bit)
462 {
463         return 1UL << bit;
464 }
465
466 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
467 {
468         char c = '.';
469
470         if (class->usage_mask & lock_flag(bit + 2))
471                 c = '+';
472         if (class->usage_mask & lock_flag(bit)) {
473                 c = '-';
474                 if (class->usage_mask & lock_flag(bit + 2))
475                         c = '?';
476         }
477
478         return c;
479 }
480
481 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
482 {
483         int i = 0;
484
485 #define LOCKDEP_STATE(__STATE)                                          \
486         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
487         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
488 #include "lockdep_states.h"
489 #undef LOCKDEP_STATE
490
491         usage[i] = '\0';
492 }
493
494 static int __print_lock_name(struct lock_class *class)
495 {
496         char str[KSYM_NAME_LEN];
497         const char *name;
498
499         name = class->name;
500         if (!name)
501                 name = __get_key_name(class->key, str);
502
503         return printk("%s", name);
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         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
656                 debug_locks_off();
657                 printk(KERN_ERR
658                         "BUG: looking up invalid subclass: %u\n", subclass);
659                 printk(KERN_ERR
660                         "turning off the locking correctness validator.\n");
661                 dump_stack();
662                 return NULL;
663         }
664
665         /*
666          * Static locks do not have their class-keys yet - for them the key
667          * is the lock object itself:
668          */
669         if (unlikely(!lock->key))
670                 lock->key = (void *)lock;
671
672         /*
673          * NOTE: the class-key must be unique. For dynamic locks, a static
674          * lock_class_key variable is passed in through the mutex_init()
675          * (or spin_lock_init()) call - which acts as the key. For static
676          * locks we use the lock object itself as the key.
677          */
678         BUILD_BUG_ON(sizeof(struct lock_class_key) >
679                         sizeof(struct lockdep_map));
680
681         key = lock->key->subkeys + subclass;
682
683         hash_head = classhashentry(key);
684
685         /*
686          * We can walk the hash lockfree, because the hash only
687          * grows, and we are careful when adding entries to the end:
688          */
689         list_for_each_entry(class, hash_head, hash_entry) {
690                 if (class->key == key) {
691                         WARN_ON_ONCE(class->name != lock->name);
692                         return class;
693                 }
694         }
695
696         return NULL;
697 }
698
699 /*
700  * Register a lock's class in the hash-table, if the class is not present
701  * yet. Otherwise we look it up. We cache the result in the lock object
702  * itself, so actual lookup of the hash should be once per lock object.
703  */
704 static inline struct lock_class *
705 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
706 {
707         struct lockdep_subclass_key *key;
708         struct list_head *hash_head;
709         struct lock_class *class;
710         unsigned long flags;
711
712         class = look_up_lock_class(lock, subclass);
713         if (likely(class))
714                 return class;
715
716         /*
717          * Debug-check: all keys must be persistent!
718          */
719         if (!static_obj(lock->key)) {
720                 debug_locks_off();
721                 printk("INFO: trying to register non-static key.\n");
722                 printk("the code is fine but needs lockdep annotation.\n");
723                 printk("turning off the locking correctness validator.\n");
724                 dump_stack();
725
726                 return NULL;
727         }
728
729         key = lock->key->subkeys + subclass;
730         hash_head = classhashentry(key);
731
732         raw_local_irq_save(flags);
733         if (!graph_lock()) {
734                 raw_local_irq_restore(flags);
735                 return NULL;
736         }
737         /*
738          * We have to do the hash-walk again, to avoid races
739          * with another CPU:
740          */
741         list_for_each_entry(class, hash_head, hash_entry)
742                 if (class->key == key)
743                         goto out_unlock_set;
744         /*
745          * Allocate a new key from the static array, and add it to
746          * the hash:
747          */
748         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
749                 if (!debug_locks_off_graph_unlock()) {
750                         raw_local_irq_restore(flags);
751                         return NULL;
752                 }
753                 raw_local_irq_restore(flags);
754
755                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
756                 printk("turning off the locking correctness validator.\n");
757                 dump_stack();
758                 return NULL;
759         }
760         class = lock_classes + nr_lock_classes++;
761         debug_atomic_inc(nr_unused_locks);
762         class->key = key;
763         class->name = lock->name;
764         class->subclass = subclass;
765         INIT_LIST_HEAD(&class->lock_entry);
766         INIT_LIST_HEAD(&class->locks_before);
767         INIT_LIST_HEAD(&class->locks_after);
768         class->name_version = count_matching_names(class);
769         /*
770          * We use RCU's safe list-add method to make
771          * parallel walking of the hash-list safe:
772          */
773         list_add_tail_rcu(&class->hash_entry, hash_head);
774         /*
775          * Add it to the global list of classes:
776          */
777         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
778
779         if (verbose(class)) {
780                 graph_unlock();
781                 raw_local_irq_restore(flags);
782
783                 printk("\nnew class %p: %s", class->key, class->name);
784                 if (class->name_version > 1)
785                         printk("#%d", class->name_version);
786                 printk("\n");
787                 dump_stack();
788
789                 raw_local_irq_save(flags);
790                 if (!graph_lock()) {
791                         raw_local_irq_restore(flags);
792                         return NULL;
793                 }
794         }
795 out_unlock_set:
796         graph_unlock();
797         raw_local_irq_restore(flags);
798
799         if (!subclass || force)
800                 lock->class_cache[0] = class;
801         else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
802                 lock->class_cache[subclass] = class;
803
804         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
805                 return NULL;
806
807         return class;
808 }
809
810 #ifdef CONFIG_PROVE_LOCKING
811 /*
812  * Allocate a lockdep entry. (assumes the graph_lock held, returns
813  * with NULL on failure)
814  */
815 static struct lock_list *alloc_list_entry(void)
816 {
817         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
818                 if (!debug_locks_off_graph_unlock())
819                         return NULL;
820
821                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
822                 printk("turning off the locking correctness validator.\n");
823                 dump_stack();
824                 return NULL;
825         }
826         return list_entries + nr_list_entries++;
827 }
828
829 /*
830  * Add a new dependency to the head of the list:
831  */
832 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
833                             struct list_head *head, unsigned long ip,
834                             int distance, struct stack_trace *trace)
835 {
836         struct lock_list *entry;
837         /*
838          * Lock not present yet - get a new dependency struct and
839          * add it to the list:
840          */
841         entry = alloc_list_entry();
842         if (!entry)
843                 return 0;
844
845         entry->class = this;
846         entry->distance = distance;
847         entry->trace = *trace;
848         /*
849          * Since we never remove from the dependency list, the list can
850          * be walked lockless by other CPUs, it's only allocation
851          * that must be protected by the spinlock. But this also means
852          * we must make new entries visible only once writes to the
853          * entry become visible - hence the RCU op:
854          */
855         list_add_tail_rcu(&entry->entry, head);
856
857         return 1;
858 }
859
860 /*
861  * For good efficiency of modular, we use power of 2
862  */
863 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
864 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
865
866 /*
867  * The circular_queue and helpers is used to implement the
868  * breadth-first search(BFS)algorithem, by which we can build
869  * the shortest path from the next lock to be acquired to the
870  * previous held lock if there is a circular between them.
871  */
872 struct circular_queue {
873         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
874         unsigned int  front, rear;
875 };
876
877 static struct circular_queue lock_cq;
878
879 unsigned int max_bfs_queue_depth;
880
881 static unsigned int lockdep_dependency_gen_id;
882
883 static inline void __cq_init(struct circular_queue *cq)
884 {
885         cq->front = cq->rear = 0;
886         lockdep_dependency_gen_id++;
887 }
888
889 static inline int __cq_empty(struct circular_queue *cq)
890 {
891         return (cq->front == cq->rear);
892 }
893
894 static inline int __cq_full(struct circular_queue *cq)
895 {
896         return ((cq->rear + 1) & CQ_MASK) == cq->front;
897 }
898
899 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
900 {
901         if (__cq_full(cq))
902                 return -1;
903
904         cq->element[cq->rear] = elem;
905         cq->rear = (cq->rear + 1) & CQ_MASK;
906         return 0;
907 }
908
909 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
910 {
911         if (__cq_empty(cq))
912                 return -1;
913
914         *elem = cq->element[cq->front];
915         cq->front = (cq->front + 1) & CQ_MASK;
916         return 0;
917 }
918
919 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
920 {
921         return (cq->rear - cq->front) & CQ_MASK;
922 }
923
924 static inline void mark_lock_accessed(struct lock_list *lock,
925                                         struct lock_list *parent)
926 {
927         unsigned long nr;
928
929         nr = lock - list_entries;
930         WARN_ON(nr >= nr_list_entries);
931         lock->parent = parent;
932         lock->class->dep_gen_id = lockdep_dependency_gen_id;
933 }
934
935 static inline unsigned long lock_accessed(struct lock_list *lock)
936 {
937         unsigned long nr;
938
939         nr = lock - list_entries;
940         WARN_ON(nr >= nr_list_entries);
941         return lock->class->dep_gen_id == lockdep_dependency_gen_id;
942 }
943
944 static inline struct lock_list *get_lock_parent(struct lock_list *child)
945 {
946         return child->parent;
947 }
948
949 static inline int get_lock_depth(struct lock_list *child)
950 {
951         int depth = 0;
952         struct lock_list *parent;
953
954         while ((parent = get_lock_parent(child))) {
955                 child = parent;
956                 depth++;
957         }
958         return depth;
959 }
960
961 static int __bfs(struct lock_list *source_entry,
962                  void *data,
963                  int (*match)(struct lock_list *entry, void *data),
964                  struct lock_list **target_entry,
965                  int forward)
966 {
967         struct lock_list *entry;
968         struct list_head *head;
969         struct circular_queue *cq = &lock_cq;
970         int ret = 1;
971
972         if (match(source_entry, data)) {
973                 *target_entry = source_entry;
974                 ret = 0;
975                 goto exit;
976         }
977
978         if (forward)
979                 head = &source_entry->class->locks_after;
980         else
981                 head = &source_entry->class->locks_before;
982
983         if (list_empty(head))
984                 goto exit;
985
986         __cq_init(cq);
987         __cq_enqueue(cq, (unsigned long)source_entry);
988
989         while (!__cq_empty(cq)) {
990                 struct lock_list *lock;
991
992                 __cq_dequeue(cq, (unsigned long *)&lock);
993
994                 if (!lock->class) {
995                         ret = -2;
996                         goto exit;
997                 }
998
999                 if (forward)
1000                         head = &lock->class->locks_after;
1001                 else
1002                         head = &lock->class->locks_before;
1003
1004                 list_for_each_entry(entry, head, entry) {
1005                         if (!lock_accessed(entry)) {
1006                                 unsigned int cq_depth;
1007                                 mark_lock_accessed(entry, lock);
1008                                 if (match(entry, data)) {
1009                                         *target_entry = entry;
1010                                         ret = 0;
1011                                         goto exit;
1012                                 }
1013
1014                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
1015                                         ret = -1;
1016                                         goto exit;
1017                                 }
1018                                 cq_depth = __cq_get_elem_count(cq);
1019                                 if (max_bfs_queue_depth < cq_depth)
1020                                         max_bfs_queue_depth = cq_depth;
1021                         }
1022                 }
1023         }
1024 exit:
1025         return ret;
1026 }
1027
1028 static inline int __bfs_forwards(struct lock_list *src_entry,
1029                         void *data,
1030                         int (*match)(struct lock_list *entry, void *data),
1031                         struct lock_list **target_entry)
1032 {
1033         return __bfs(src_entry, data, match, target_entry, 1);
1034
1035 }
1036
1037 static inline int __bfs_backwards(struct lock_list *src_entry,
1038                         void *data,
1039                         int (*match)(struct lock_list *entry, void *data),
1040                         struct lock_list **target_entry)
1041 {
1042         return __bfs(src_entry, data, match, target_entry, 0);
1043
1044 }
1045
1046 /*
1047  * Recursive, forwards-direction lock-dependency checking, used for
1048  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1049  * checking.
1050  */
1051
1052 /*
1053  * Print a dependency chain entry (this is only done when a deadlock
1054  * has been detected):
1055  */
1056 static noinline int
1057 print_circular_bug_entry(struct lock_list *target, int depth)
1058 {
1059         if (debug_locks_silent)
1060                 return 0;
1061         printk("\n-> #%u", depth);
1062         print_lock_name(target->class);
1063         printk(":\n");
1064         print_stack_trace(&target->trace, 6);
1065
1066         return 0;
1067 }
1068
1069 static void
1070 print_circular_lock_scenario(struct held_lock *src,
1071                              struct held_lock *tgt,
1072                              struct lock_list *prt)
1073 {
1074         struct lock_class *source = hlock_class(src);
1075         struct lock_class *target = hlock_class(tgt);
1076         struct lock_class *parent = prt->class;
1077
1078         /*
1079          * A direct locking problem where unsafe_class lock is taken
1080          * directly by safe_class lock, then all we need to show
1081          * is the deadlock scenario, as it is obvious that the
1082          * unsafe lock is taken under the safe lock.
1083          *
1084          * But if there is a chain instead, where the safe lock takes
1085          * an intermediate lock (middle_class) where this lock is
1086          * not the same as the safe lock, then the lock chain is
1087          * used to describe the problem. Otherwise we would need
1088          * to show a different CPU case for each link in the chain
1089          * from the safe_class lock to the unsafe_class lock.
1090          */
1091         if (parent != source) {
1092                 printk("Chain exists of:\n  ");
1093                 __print_lock_name(source);
1094                 printk(" --> ");
1095                 __print_lock_name(parent);
1096                 printk(" --> ");
1097                 __print_lock_name(target);
1098                 printk("\n\n");
1099         }
1100
1101         printk(" Possible unsafe locking scenario:\n\n");
1102         printk("       CPU0                    CPU1\n");
1103         printk("       ----                    ----\n");
1104         printk("  lock(");
1105         __print_lock_name(target);
1106         printk(");\n");
1107         printk("                               lock(");
1108         __print_lock_name(parent);
1109         printk(");\n");
1110         printk("                               lock(");
1111         __print_lock_name(target);
1112         printk(");\n");
1113         printk("  lock(");
1114         __print_lock_name(source);
1115         printk(");\n");
1116         printk("\n *** DEADLOCK ***\n\n");
1117 }
1118
1119 /*
1120  * When a circular dependency is detected, print the
1121  * header first:
1122  */
1123 static noinline int
1124 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1125                         struct held_lock *check_src,
1126                         struct held_lock *check_tgt)
1127 {
1128         struct task_struct *curr = current;
1129
1130         if (debug_locks_silent)
1131                 return 0;
1132
1133         printk("\n=======================================================\n");
1134         printk(  "[ INFO: possible circular locking dependency detected ]\n");
1135         print_kernel_version();
1136         printk(  "-------------------------------------------------------\n");
1137         printk("%s/%d is trying to acquire lock:\n",
1138                 curr->comm, task_pid_nr(curr));
1139         print_lock(check_src);
1140         printk("\nbut task is already holding lock:\n");
1141         print_lock(check_tgt);
1142         printk("\nwhich lock already depends on the new lock.\n\n");
1143         printk("\nthe existing dependency chain (in reverse order) is:\n");
1144
1145         print_circular_bug_entry(entry, depth);
1146
1147         return 0;
1148 }
1149
1150 static inline int class_equal(struct lock_list *entry, void *data)
1151 {
1152         return entry->class == data;
1153 }
1154
1155 static noinline int print_circular_bug(struct lock_list *this,
1156                                 struct lock_list *target,
1157                                 struct held_lock *check_src,
1158                                 struct held_lock *check_tgt)
1159 {
1160         struct task_struct *curr = current;
1161         struct lock_list *parent;
1162         struct lock_list *first_parent;
1163         int depth;
1164
1165         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1166                 return 0;
1167
1168         if (!save_trace(&this->trace))
1169                 return 0;
1170
1171         depth = get_lock_depth(target);
1172
1173         print_circular_bug_header(target, depth, check_src, check_tgt);
1174
1175         parent = get_lock_parent(target);
1176         first_parent = parent;
1177
1178         while (parent) {
1179                 print_circular_bug_entry(parent, --depth);
1180                 parent = get_lock_parent(parent);
1181         }
1182
1183         printk("\nother info that might help us debug this:\n\n");
1184         print_circular_lock_scenario(check_src, check_tgt,
1185                                      first_parent);
1186
1187         lockdep_print_held_locks(curr);
1188
1189         printk("\nstack backtrace:\n");
1190         dump_stack();
1191
1192         return 0;
1193 }
1194
1195 static noinline int print_bfs_bug(int ret)
1196 {
1197         if (!debug_locks_off_graph_unlock())
1198                 return 0;
1199
1200         WARN(1, "lockdep bfs error:%d\n", ret);
1201
1202         return 0;
1203 }
1204
1205 static int noop_count(struct lock_list *entry, void *data)
1206 {
1207         (*(unsigned long *)data)++;
1208         return 0;
1209 }
1210
1211 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1212 {
1213         unsigned long  count = 0;
1214         struct lock_list *uninitialized_var(target_entry);
1215
1216         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1217
1218         return count;
1219 }
1220 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1221 {
1222         unsigned long ret, flags;
1223         struct lock_list this;
1224
1225         this.parent = NULL;
1226         this.class = class;
1227
1228         local_irq_save(flags);
1229         arch_spin_lock(&lockdep_lock);
1230         ret = __lockdep_count_forward_deps(&this);
1231         arch_spin_unlock(&lockdep_lock);
1232         local_irq_restore(flags);
1233
1234         return ret;
1235 }
1236
1237 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1238 {
1239         unsigned long  count = 0;
1240         struct lock_list *uninitialized_var(target_entry);
1241
1242         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1243
1244         return count;
1245 }
1246
1247 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1248 {
1249         unsigned long ret, flags;
1250         struct lock_list this;
1251
1252         this.parent = NULL;
1253         this.class = class;
1254
1255         local_irq_save(flags);
1256         arch_spin_lock(&lockdep_lock);
1257         ret = __lockdep_count_backward_deps(&this);
1258         arch_spin_unlock(&lockdep_lock);
1259         local_irq_restore(flags);
1260
1261         return ret;
1262 }
1263
1264 /*
1265  * Prove that the dependency graph starting at <entry> can not
1266  * lead to <target>. Print an error and return 0 if it does.
1267  */
1268 static noinline int
1269 check_noncircular(struct lock_list *root, struct lock_class *target,
1270                 struct lock_list **target_entry)
1271 {
1272         int result;
1273
1274         debug_atomic_inc(nr_cyclic_checks);
1275
1276         result = __bfs_forwards(root, target, class_equal, target_entry);
1277
1278         return result;
1279 }
1280
1281 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1282 /*
1283  * Forwards and backwards subgraph searching, for the purposes of
1284  * proving that two subgraphs can be connected by a new dependency
1285  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1286  */
1287
1288 static inline int usage_match(struct lock_list *entry, void *bit)
1289 {
1290         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1291 }
1292
1293
1294
1295 /*
1296  * Find a node in the forwards-direction dependency sub-graph starting
1297  * at @root->class that matches @bit.
1298  *
1299  * Return 0 if such a node exists in the subgraph, and put that node
1300  * into *@target_entry.
1301  *
1302  * Return 1 otherwise and keep *@target_entry unchanged.
1303  * Return <0 on error.
1304  */
1305 static int
1306 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1307                         struct lock_list **target_entry)
1308 {
1309         int result;
1310
1311         debug_atomic_inc(nr_find_usage_forwards_checks);
1312
1313         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1314
1315         return result;
1316 }
1317
1318 /*
1319  * Find a node in the backwards-direction dependency sub-graph starting
1320  * at @root->class that matches @bit.
1321  *
1322  * Return 0 if such a node exists in the subgraph, and put that node
1323  * into *@target_entry.
1324  *
1325  * Return 1 otherwise and keep *@target_entry unchanged.
1326  * Return <0 on error.
1327  */
1328 static int
1329 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1330                         struct lock_list **target_entry)
1331 {
1332         int result;
1333
1334         debug_atomic_inc(nr_find_usage_backwards_checks);
1335
1336         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1337
1338         return result;
1339 }
1340
1341 static void print_lock_class_header(struct lock_class *class, int depth)
1342 {
1343         int bit;
1344
1345         printk("%*s->", depth, "");
1346         print_lock_name(class);
1347         printk(" ops: %lu", class->ops);
1348         printk(" {\n");
1349
1350         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1351                 if (class->usage_mask & (1 << bit)) {
1352                         int len = depth;
1353
1354                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1355                         len += printk(" at:\n");
1356                         print_stack_trace(class->usage_traces + bit, len);
1357                 }
1358         }
1359         printk("%*s }\n", depth, "");
1360
1361         printk("%*s ... key      at: ",depth,"");
1362         print_ip_sym((unsigned long)class->key);
1363 }
1364
1365 /*
1366  * printk the shortest lock dependencies from @start to @end in reverse order:
1367  */
1368 static void __used
1369 print_shortest_lock_dependencies(struct lock_list *leaf,
1370                                 struct lock_list *root)
1371 {
1372         struct lock_list *entry = leaf;
1373         int depth;
1374
1375         /*compute depth from generated tree by BFS*/
1376         depth = get_lock_depth(leaf);
1377
1378         do {
1379                 print_lock_class_header(entry->class, depth);
1380                 printk("%*s ... acquired at:\n", depth, "");
1381                 print_stack_trace(&entry->trace, 2);
1382                 printk("\n");
1383
1384                 if (depth == 0 && (entry != root)) {
1385                         printk("lockdep:%s bad path found in chain graph\n", __func__);
1386                         break;
1387                 }
1388
1389                 entry = get_lock_parent(entry);
1390                 depth--;
1391         } while (entry && (depth >= 0));
1392
1393         return;
1394 }
1395
1396 static void
1397 print_irq_lock_scenario(struct lock_list *safe_entry,
1398                         struct lock_list *unsafe_entry,
1399                         struct lock_class *prev_class,
1400                         struct lock_class *next_class)
1401 {
1402         struct lock_class *safe_class = safe_entry->class;
1403         struct lock_class *unsafe_class = unsafe_entry->class;
1404         struct lock_class *middle_class = prev_class;
1405
1406         if (middle_class == safe_class)
1407                 middle_class = next_class;
1408
1409         /*
1410          * A direct locking problem where unsafe_class lock is taken
1411          * directly by safe_class lock, then all we need to show
1412          * is the deadlock scenario, as it is obvious that the
1413          * unsafe lock is taken under the safe lock.
1414          *
1415          * But if there is a chain instead, where the safe lock takes
1416          * an intermediate lock (middle_class) where this lock is
1417          * not the same as the safe lock, then the lock chain is
1418          * used to describe the problem. Otherwise we would need
1419          * to show a different CPU case for each link in the chain
1420          * from the safe_class lock to the unsafe_class lock.
1421          */
1422         if (middle_class != unsafe_class) {
1423                 printk("Chain exists of:\n  ");
1424                 __print_lock_name(safe_class);
1425                 printk(" --> ");
1426                 __print_lock_name(middle_class);
1427                 printk(" --> ");
1428                 __print_lock_name(unsafe_class);
1429                 printk("\n\n");
1430         }
1431
1432         printk(" Possible interrupt unsafe locking scenario:\n\n");
1433         printk("       CPU0                    CPU1\n");
1434         printk("       ----                    ----\n");
1435         printk("  lock(");
1436         __print_lock_name(unsafe_class);
1437         printk(");\n");
1438         printk("                               local_irq_disable();\n");
1439         printk("                               lock(");
1440         __print_lock_name(safe_class);
1441         printk(");\n");
1442         printk("                               lock(");
1443         __print_lock_name(middle_class);
1444         printk(");\n");
1445         printk("  <Interrupt>\n");
1446         printk("    lock(");
1447         __print_lock_name(safe_class);
1448         printk(");\n");
1449         printk("\n *** DEADLOCK ***\n\n");
1450 }
1451
1452 static int
1453 print_bad_irq_dependency(struct task_struct *curr,
1454                          struct lock_list *prev_root,
1455                          struct lock_list *next_root,
1456                          struct lock_list *backwards_entry,
1457                          struct lock_list *forwards_entry,
1458                          struct held_lock *prev,
1459                          struct held_lock *next,
1460                          enum lock_usage_bit bit1,
1461                          enum lock_usage_bit bit2,
1462                          const char *irqclass)
1463 {
1464         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1465                 return 0;
1466
1467         printk("\n======================================================\n");
1468         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1469                 irqclass, irqclass);
1470         print_kernel_version();
1471         printk(  "------------------------------------------------------\n");
1472         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1473                 curr->comm, task_pid_nr(curr),
1474                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1475                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1476                 curr->hardirqs_enabled,
1477                 curr->softirqs_enabled);
1478         print_lock(next);
1479
1480         printk("\nand this task is already holding:\n");
1481         print_lock(prev);
1482         printk("which would create a new lock dependency:\n");
1483         print_lock_name(hlock_class(prev));
1484         printk(" ->");
1485         print_lock_name(hlock_class(next));
1486         printk("\n");
1487
1488         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1489                 irqclass);
1490         print_lock_name(backwards_entry->class);
1491         printk("\n... which became %s-irq-safe at:\n", irqclass);
1492
1493         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1494
1495         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1496         print_lock_name(forwards_entry->class);
1497         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1498         printk("...");
1499
1500         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1501
1502         printk("\nother info that might help us debug this:\n\n");
1503         print_irq_lock_scenario(backwards_entry, forwards_entry,
1504                                 hlock_class(prev), hlock_class(next));
1505
1506         lockdep_print_held_locks(curr);
1507
1508         printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1509         printk(" and the holding lock:\n");
1510         if (!save_trace(&prev_root->trace))
1511                 return 0;
1512         print_shortest_lock_dependencies(backwards_entry, prev_root);
1513
1514         printk("\nthe dependencies between the lock to be acquired");
1515         printk(" and %s-irq-unsafe lock:\n", irqclass);
1516         if (!save_trace(&next_root->trace))
1517                 return 0;
1518         print_shortest_lock_dependencies(forwards_entry, next_root);
1519
1520         printk("\nstack backtrace:\n");
1521         dump_stack();
1522
1523         return 0;
1524 }
1525
1526 static int
1527 check_usage(struct task_struct *curr, struct held_lock *prev,
1528             struct held_lock *next, enum lock_usage_bit bit_backwards,
1529             enum lock_usage_bit bit_forwards, const char *irqclass)
1530 {
1531         int ret;
1532         struct lock_list this, that;
1533         struct lock_list *uninitialized_var(target_entry);
1534         struct lock_list *uninitialized_var(target_entry1);
1535
1536         this.parent = NULL;
1537
1538         this.class = hlock_class(prev);
1539         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1540         if (ret < 0)
1541                 return print_bfs_bug(ret);
1542         if (ret == 1)
1543                 return ret;
1544
1545         that.parent = NULL;
1546         that.class = hlock_class(next);
1547         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1548         if (ret < 0)
1549                 return print_bfs_bug(ret);
1550         if (ret == 1)
1551                 return ret;
1552
1553         return print_bad_irq_dependency(curr, &this, &that,
1554                         target_entry, target_entry1,
1555                         prev, next,
1556                         bit_backwards, bit_forwards, irqclass);
1557 }
1558
1559 static const char *state_names[] = {
1560 #define LOCKDEP_STATE(__STATE) \
1561         __stringify(__STATE),
1562 #include "lockdep_states.h"
1563 #undef LOCKDEP_STATE
1564 };
1565
1566 static const char *state_rnames[] = {
1567 #define LOCKDEP_STATE(__STATE) \
1568         __stringify(__STATE)"-READ",
1569 #include "lockdep_states.h"
1570 #undef LOCKDEP_STATE
1571 };
1572
1573 static inline const char *state_name(enum lock_usage_bit bit)
1574 {
1575         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1576 }
1577
1578 static int exclusive_bit(int new_bit)
1579 {
1580         /*
1581          * USED_IN
1582          * USED_IN_READ
1583          * ENABLED
1584          * ENABLED_READ
1585          *
1586          * bit 0 - write/read
1587          * bit 1 - used_in/enabled
1588          * bit 2+  state
1589          */
1590
1591         int state = new_bit & ~3;
1592         int dir = new_bit & 2;
1593
1594         /*
1595          * keep state, bit flip the direction and strip read.
1596          */
1597         return state | (dir ^ 2);
1598 }
1599
1600 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1601                            struct held_lock *next, enum lock_usage_bit bit)
1602 {
1603         /*
1604          * Prove that the new dependency does not connect a hardirq-safe
1605          * lock with a hardirq-unsafe lock - to achieve this we search
1606          * the backwards-subgraph starting at <prev>, and the
1607          * forwards-subgraph starting at <next>:
1608          */
1609         if (!check_usage(curr, prev, next, bit,
1610                            exclusive_bit(bit), state_name(bit)))
1611                 return 0;
1612
1613         bit++; /* _READ */
1614
1615         /*
1616          * Prove that the new dependency does not connect a hardirq-safe-read
1617          * lock with a hardirq-unsafe lock - to achieve this we search
1618          * the backwards-subgraph starting at <prev>, and the
1619          * forwards-subgraph starting at <next>:
1620          */
1621         if (!check_usage(curr, prev, next, bit,
1622                            exclusive_bit(bit), state_name(bit)))
1623                 return 0;
1624
1625         return 1;
1626 }
1627
1628 static int
1629 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1630                 struct held_lock *next)
1631 {
1632 #define LOCKDEP_STATE(__STATE)                                          \
1633         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1634                 return 0;
1635 #include "lockdep_states.h"
1636 #undef LOCKDEP_STATE
1637
1638         return 1;
1639 }
1640
1641 static void inc_chains(void)
1642 {
1643         if (current->hardirq_context)
1644                 nr_hardirq_chains++;
1645         else {
1646                 if (current->softirq_context)
1647                         nr_softirq_chains++;
1648                 else
1649                         nr_process_chains++;
1650         }
1651 }
1652
1653 #else
1654
1655 static inline int
1656 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1657                 struct held_lock *next)
1658 {
1659         return 1;
1660 }
1661
1662 static inline void inc_chains(void)
1663 {
1664         nr_process_chains++;
1665 }
1666
1667 #endif
1668
1669 static void
1670 print_deadlock_scenario(struct held_lock *nxt,
1671                              struct held_lock *prv)
1672 {
1673         struct lock_class *next = hlock_class(nxt);
1674         struct lock_class *prev = hlock_class(prv);
1675
1676         printk(" Possible unsafe locking scenario:\n\n");
1677         printk("       CPU0\n");
1678         printk("       ----\n");
1679         printk("  lock(");
1680         __print_lock_name(prev);
1681         printk(");\n");
1682         printk("  lock(");
1683         __print_lock_name(next);
1684         printk(");\n");
1685         printk("\n *** DEADLOCK ***\n\n");
1686         printk(" May be due to missing lock nesting notation\n\n");
1687 }
1688
1689 static int
1690 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1691                    struct held_lock *next)
1692 {
1693         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1694                 return 0;
1695
1696         printk("\n=============================================\n");
1697         printk(  "[ INFO: possible recursive locking detected ]\n");
1698         print_kernel_version();
1699         printk(  "---------------------------------------------\n");
1700         printk("%s/%d is trying to acquire lock:\n",
1701                 curr->comm, task_pid_nr(curr));
1702         print_lock(next);
1703         printk("\nbut task is already holding lock:\n");
1704         print_lock(prev);
1705
1706         printk("\nother info that might help us debug this:\n");
1707         print_deadlock_scenario(next, prev);
1708         lockdep_print_held_locks(curr);
1709
1710         printk("\nstack backtrace:\n");
1711         dump_stack();
1712
1713         return 0;
1714 }
1715
1716 /*
1717  * Check whether we are holding such a class already.
1718  *
1719  * (Note that this has to be done separately, because the graph cannot
1720  * detect such classes of deadlocks.)
1721  *
1722  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1723  */
1724 static int
1725 check_deadlock(struct task_struct *curr, struct held_lock *next,
1726                struct lockdep_map *next_instance, int read)
1727 {
1728         struct held_lock *prev;
1729         struct held_lock *nest = NULL;
1730         int i;
1731
1732         for (i = 0; i < curr->lockdep_depth; i++) {
1733                 prev = curr->held_locks + i;
1734
1735                 if (prev->instance == next->nest_lock)
1736                         nest = prev;
1737
1738                 if (hlock_class(prev) != hlock_class(next))
1739                         continue;
1740
1741                 /*
1742                  * Allow read-after-read recursion of the same
1743                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1744                  */
1745                 if ((read == 2) && prev->read)
1746                         return 2;
1747
1748                 /*
1749                  * We're holding the nest_lock, which serializes this lock's
1750                  * nesting behaviour.
1751                  */
1752                 if (nest)
1753                         return 2;
1754
1755                 return print_deadlock_bug(curr, prev, next);
1756         }
1757         return 1;
1758 }
1759
1760 /*
1761  * There was a chain-cache miss, and we are about to add a new dependency
1762  * to a previous lock. We recursively validate the following rules:
1763  *
1764  *  - would the adding of the <prev> -> <next> dependency create a
1765  *    circular dependency in the graph? [== circular deadlock]
1766  *
1767  *  - does the new prev->next dependency connect any hardirq-safe lock
1768  *    (in the full backwards-subgraph starting at <prev>) with any
1769  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1770  *    <next>)? [== illegal lock inversion with hardirq contexts]
1771  *
1772  *  - does the new prev->next dependency connect any softirq-safe lock
1773  *    (in the full backwards-subgraph starting at <prev>) with any
1774  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1775  *    <next>)? [== illegal lock inversion with softirq contexts]
1776  *
1777  * any of these scenarios could lead to a deadlock.
1778  *
1779  * Then if all the validations pass, we add the forwards and backwards
1780  * dependency.
1781  */
1782 static int
1783 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1784                struct held_lock *next, int distance, int trylock_loop)
1785 {
1786         struct lock_list *entry;
1787         int ret;
1788         struct lock_list this;
1789         struct lock_list *uninitialized_var(target_entry);
1790         /*
1791          * Static variable, serialized by the graph_lock().
1792          *
1793          * We use this static variable to save the stack trace in case
1794          * we call into this function multiple times due to encountering
1795          * trylocks in the held lock stack.
1796          */
1797         static struct stack_trace trace;
1798
1799         /*
1800          * Prove that the new <prev> -> <next> dependency would not
1801          * create a circular dependency in the graph. (We do this by
1802          * forward-recursing into the graph starting at <next>, and
1803          * checking whether we can reach <prev>.)
1804          *
1805          * We are using global variables to control the recursion, to
1806          * keep the stackframe size of the recursive functions low:
1807          */
1808         this.class = hlock_class(next);
1809         this.parent = NULL;
1810         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1811         if (unlikely(!ret))
1812                 return print_circular_bug(&this, target_entry, next, prev);
1813         else if (unlikely(ret < 0))
1814                 return print_bfs_bug(ret);
1815
1816         if (!check_prev_add_irq(curr, prev, next))
1817                 return 0;
1818
1819         /*
1820          * For recursive read-locks we do all the dependency checks,
1821          * but we dont store read-triggered dependencies (only
1822          * write-triggered dependencies). This ensures that only the
1823          * write-side dependencies matter, and that if for example a
1824          * write-lock never takes any other locks, then the reads are
1825          * equivalent to a NOP.
1826          */
1827         if (next->read == 2 || prev->read == 2)
1828                 return 1;
1829         /*
1830          * Is the <prev> -> <next> dependency already present?
1831          *
1832          * (this may occur even though this is a new chain: consider
1833          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1834          *  chains - the second one will be new, but L1 already has
1835          *  L2 added to its dependency list, due to the first chain.)
1836          */
1837         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1838                 if (entry->class == hlock_class(next)) {
1839                         if (distance == 1)
1840                                 entry->distance = 1;
1841                         return 2;
1842                 }
1843         }
1844
1845         if (!trylock_loop && !save_trace(&trace))
1846                 return 0;
1847
1848         /*
1849          * Ok, all validations passed, add the new lock
1850          * to the previous lock's dependency list:
1851          */
1852         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1853                                &hlock_class(prev)->locks_after,
1854                                next->acquire_ip, distance, &trace);
1855
1856         if (!ret)
1857                 return 0;
1858
1859         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1860                                &hlock_class(next)->locks_before,
1861                                next->acquire_ip, distance, &trace);
1862         if (!ret)
1863                 return 0;
1864
1865         /*
1866          * Debugging printouts:
1867          */
1868         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1869                 graph_unlock();
1870                 printk("\n new dependency: ");
1871                 print_lock_name(hlock_class(prev));
1872                 printk(" => ");
1873                 print_lock_name(hlock_class(next));
1874                 printk("\n");
1875                 dump_stack();
1876                 return graph_lock();
1877         }
1878         return 1;
1879 }
1880
1881 /*
1882  * Add the dependency to all directly-previous locks that are 'relevant'.
1883  * The ones that are relevant are (in increasing distance from curr):
1884  * all consecutive trylock entries and the final non-trylock entry - or
1885  * the end of this context's lock-chain - whichever comes first.
1886  */
1887 static int
1888 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1889 {
1890         int depth = curr->lockdep_depth;
1891         int trylock_loop = 0;
1892         struct held_lock *hlock;
1893
1894         /*
1895          * Debugging checks.
1896          *
1897          * Depth must not be zero for a non-head lock:
1898          */
1899         if (!depth)
1900                 goto out_bug;
1901         /*
1902          * At least two relevant locks must exist for this
1903          * to be a head:
1904          */
1905         if (curr->held_locks[depth].irq_context !=
1906                         curr->held_locks[depth-1].irq_context)
1907                 goto out_bug;
1908
1909         for (;;) {
1910                 int distance = curr->lockdep_depth - depth + 1;
1911                 hlock = curr->held_locks + depth-1;
1912                 /*
1913                  * Only non-recursive-read entries get new dependencies
1914                  * added:
1915                  */
1916                 if (hlock->read != 2) {
1917                         if (!check_prev_add(curr, hlock, next,
1918                                                 distance, trylock_loop))
1919                                 return 0;
1920                         /*
1921                          * Stop after the first non-trylock entry,
1922                          * as non-trylock entries have added their
1923                          * own direct dependencies already, so this
1924                          * lock is connected to them indirectly:
1925                          */
1926                         if (!hlock->trylock)
1927                                 break;
1928                 }
1929                 depth--;
1930                 /*
1931                  * End of lock-stack?
1932                  */
1933                 if (!depth)
1934                         break;
1935                 /*
1936                  * Stop the search if we cross into another context:
1937                  */
1938                 if (curr->held_locks[depth].irq_context !=
1939                                 curr->held_locks[depth-1].irq_context)
1940                         break;
1941                 trylock_loop = 1;
1942         }
1943         return 1;
1944 out_bug:
1945         if (!debug_locks_off_graph_unlock())
1946                 return 0;
1947
1948         WARN_ON(1);
1949
1950         return 0;
1951 }
1952
1953 unsigned long nr_lock_chains;
1954 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1955 int nr_chain_hlocks;
1956 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1957
1958 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1959 {
1960         return lock_classes + chain_hlocks[chain->base + i];
1961 }
1962
1963 /*
1964  * Look up a dependency chain. If the key is not present yet then
1965  * add it and return 1 - in this case the new dependency chain is
1966  * validated. If the key is already hashed, return 0.
1967  * (On return with 1 graph_lock is held.)
1968  */
1969 static inline int lookup_chain_cache(struct task_struct *curr,
1970                                      struct held_lock *hlock,
1971                                      u64 chain_key)
1972 {
1973         struct lock_class *class = hlock_class(hlock);
1974         struct list_head *hash_head = chainhashentry(chain_key);
1975         struct lock_chain *chain;
1976         struct held_lock *hlock_curr, *hlock_next;
1977         int i, j;
1978
1979         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1980                 return 0;
1981         /*
1982          * We can walk it lock-free, because entries only get added
1983          * to the hash:
1984          */
1985         list_for_each_entry(chain, hash_head, entry) {
1986                 if (chain->chain_key == chain_key) {
1987 cache_hit:
1988                         debug_atomic_inc(chain_lookup_hits);
1989                         if (very_verbose(class))
1990                                 printk("\nhash chain already cached, key: "
1991                                         "%016Lx tail class: [%p] %s\n",
1992                                         (unsigned long long)chain_key,
1993                                         class->key, class->name);
1994                         return 0;
1995                 }
1996         }
1997         if (very_verbose(class))
1998                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1999                         (unsigned long long)chain_key, class->key, class->name);
2000         /*
2001          * Allocate a new chain entry from the static array, and add
2002          * it to the hash:
2003          */
2004         if (!graph_lock())
2005                 return 0;
2006         /*
2007          * We have to walk the chain again locked - to avoid duplicates:
2008          */
2009         list_for_each_entry(chain, hash_head, entry) {
2010                 if (chain->chain_key == chain_key) {
2011                         graph_unlock();
2012                         goto cache_hit;
2013                 }
2014         }
2015         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2016                 if (!debug_locks_off_graph_unlock())
2017                         return 0;
2018
2019                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2020                 printk("turning off the locking correctness validator.\n");
2021                 dump_stack();
2022                 return 0;
2023         }
2024         chain = lock_chains + nr_lock_chains++;
2025         chain->chain_key = chain_key;
2026         chain->irq_context = hlock->irq_context;
2027         /* Find the first held_lock of current chain */
2028         hlock_next = hlock;
2029         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2030                 hlock_curr = curr->held_locks + i;
2031                 if (hlock_curr->irq_context != hlock_next->irq_context)
2032                         break;
2033                 hlock_next = hlock;
2034         }
2035         i++;
2036         chain->depth = curr->lockdep_depth + 1 - i;
2037         if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2038                 chain->base = nr_chain_hlocks;
2039                 nr_chain_hlocks += chain->depth;
2040                 for (j = 0; j < chain->depth - 1; j++, i++) {
2041                         int lock_id = curr->held_locks[i].class_idx - 1;
2042                         chain_hlocks[chain->base + j] = lock_id;
2043                 }
2044                 chain_hlocks[chain->base + j] = class - lock_classes;
2045         }
2046         list_add_tail_rcu(&chain->entry, hash_head);
2047         debug_atomic_inc(chain_lookup_misses);
2048         inc_chains();
2049
2050         return 1;
2051 }
2052
2053 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2054                 struct held_lock *hlock, int chain_head, u64 chain_key)
2055 {
2056         /*
2057          * Trylock needs to maintain the stack of held locks, but it
2058          * does not add new dependencies, because trylock can be done
2059          * in any order.
2060          *
2061          * We look up the chain_key and do the O(N^2) check and update of
2062          * the dependencies only if this is a new dependency chain.
2063          * (If lookup_chain_cache() returns with 1 it acquires
2064          * graph_lock for us)
2065          */
2066         if (!hlock->trylock && (hlock->check == 2) &&
2067             lookup_chain_cache(curr, hlock, chain_key)) {
2068                 /*
2069                  * Check whether last held lock:
2070                  *
2071                  * - is irq-safe, if this lock is irq-unsafe
2072                  * - is softirq-safe, if this lock is hardirq-unsafe
2073                  *
2074                  * And check whether the new lock's dependency graph
2075                  * could lead back to the previous lock.
2076                  *
2077                  * any of these scenarios could lead to a deadlock. If
2078                  * All validations
2079                  */
2080                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2081
2082                 if (!ret)
2083                         return 0;
2084                 /*
2085                  * Mark recursive read, as we jump over it when
2086                  * building dependencies (just like we jump over
2087                  * trylock entries):
2088                  */
2089                 if (ret == 2)
2090                         hlock->read = 2;
2091                 /*
2092                  * Add dependency only if this lock is not the head
2093                  * of the chain, and if it's not a secondary read-lock:
2094                  */
2095                 if (!chain_head && ret != 2)
2096                         if (!check_prevs_add(curr, hlock))
2097                                 return 0;
2098                 graph_unlock();
2099         } else
2100                 /* after lookup_chain_cache(): */
2101                 if (unlikely(!debug_locks))
2102                         return 0;
2103
2104         return 1;
2105 }
2106 #else
2107 static inline int validate_chain(struct task_struct *curr,
2108                 struct lockdep_map *lock, struct held_lock *hlock,
2109                 int chain_head, u64 chain_key)
2110 {
2111         return 1;
2112 }
2113 #endif
2114
2115 /*
2116  * We are building curr_chain_key incrementally, so double-check
2117  * it from scratch, to make sure that it's done correctly:
2118  */
2119 static void check_chain_key(struct task_struct *curr)
2120 {
2121 #ifdef CONFIG_DEBUG_LOCKDEP
2122         struct held_lock *hlock, *prev_hlock = NULL;
2123         unsigned int i, id;
2124         u64 chain_key = 0;
2125
2126         for (i = 0; i < curr->lockdep_depth; i++) {
2127                 hlock = curr->held_locks + i;
2128                 if (chain_key != hlock->prev_chain_key) {
2129                         debug_locks_off();
2130                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2131                                 curr->lockdep_depth, i,
2132                                 (unsigned long long)chain_key,
2133                                 (unsigned long long)hlock->prev_chain_key);
2134                         return;
2135                 }
2136                 id = hlock->class_idx - 1;
2137                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2138                         return;
2139
2140                 if (prev_hlock && (prev_hlock->irq_context !=
2141                                                         hlock->irq_context))
2142                         chain_key = 0;
2143                 chain_key = iterate_chain_key(chain_key, id);
2144                 prev_hlock = hlock;
2145         }
2146         if (chain_key != curr->curr_chain_key) {
2147                 debug_locks_off();
2148                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2149                         curr->lockdep_depth, i,
2150                         (unsigned long long)chain_key,
2151                         (unsigned long long)curr->curr_chain_key);
2152         }
2153 #endif
2154 }
2155
2156 static void
2157 print_usage_bug_scenario(struct held_lock *lock)
2158 {
2159         struct lock_class *class = hlock_class(lock);
2160
2161         printk(" Possible unsafe locking scenario:\n\n");
2162         printk("       CPU0\n");
2163         printk("       ----\n");
2164         printk("  lock(");
2165         __print_lock_name(class);
2166         printk(");\n");
2167         printk("  <Interrupt>\n");
2168         printk("    lock(");
2169         __print_lock_name(class);
2170         printk(");\n");
2171         printk("\n *** DEADLOCK ***\n\n");
2172 }
2173
2174 static int
2175 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2176                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2177 {
2178         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2179                 return 0;
2180
2181         printk("\n=================================\n");
2182         printk(  "[ INFO: inconsistent lock state ]\n");
2183         print_kernel_version();
2184         printk(  "---------------------------------\n");
2185
2186         printk("inconsistent {%s} -> {%s} usage.\n",
2187                 usage_str[prev_bit], usage_str[new_bit]);
2188
2189         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2190                 curr->comm, task_pid_nr(curr),
2191                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2192                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2193                 trace_hardirqs_enabled(curr),
2194                 trace_softirqs_enabled(curr));
2195         print_lock(this);
2196
2197         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2198         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2199
2200         print_irqtrace_events(curr);
2201         printk("\nother info that might help us debug this:\n");
2202         print_usage_bug_scenario(this);
2203
2204         lockdep_print_held_locks(curr);
2205
2206         printk("\nstack backtrace:\n");
2207         dump_stack();
2208
2209         return 0;
2210 }
2211
2212 /*
2213  * Print out an error if an invalid bit is set:
2214  */
2215 static inline int
2216 valid_state(struct task_struct *curr, struct held_lock *this,
2217             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2218 {
2219         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2220                 return print_usage_bug(curr, this, bad_bit, new_bit);
2221         return 1;
2222 }
2223
2224 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2225                      enum lock_usage_bit new_bit);
2226
2227 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2228
2229 /*
2230  * print irq inversion bug:
2231  */
2232 static int
2233 print_irq_inversion_bug(struct task_struct *curr,
2234                         struct lock_list *root, struct lock_list *other,
2235                         struct held_lock *this, int forwards,
2236                         const char *irqclass)
2237 {
2238         struct lock_list *entry = other;
2239         struct lock_list *middle = NULL;
2240         int depth;
2241
2242         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2243                 return 0;
2244
2245         printk("\n=========================================================\n");
2246         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2247         print_kernel_version();
2248         printk(  "---------------------------------------------------------\n");
2249         printk("%s/%d just changed the state of lock:\n",
2250                 curr->comm, task_pid_nr(curr));
2251         print_lock(this);
2252         if (forwards)
2253                 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2254         else
2255                 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2256         print_lock_name(other->class);
2257         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2258
2259         printk("\nother info that might help us debug this:\n");
2260
2261         /* Find a middle lock (if one exists) */
2262         depth = get_lock_depth(other);
2263         do {
2264                 if (depth == 0 && (entry != root)) {
2265                         printk("lockdep:%s bad path found in chain graph\n", __func__);
2266                         break;
2267                 }
2268                 middle = entry;
2269                 entry = get_lock_parent(entry);
2270                 depth--;
2271         } while (entry && entry != root && (depth >= 0));
2272         if (forwards)
2273                 print_irq_lock_scenario(root, other,
2274                         middle ? middle->class : root->class, other->class);
2275         else
2276                 print_irq_lock_scenario(other, root,
2277                         middle ? middle->class : other->class, root->class);
2278
2279         lockdep_print_held_locks(curr);
2280
2281         printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2282         if (!save_trace(&root->trace))
2283                 return 0;
2284         print_shortest_lock_dependencies(other, root);
2285
2286         printk("\nstack backtrace:\n");
2287         dump_stack();
2288
2289         return 0;
2290 }
2291
2292 /*
2293  * Prove that in the forwards-direction subgraph starting at <this>
2294  * there is no lock matching <mask>:
2295  */
2296 static int
2297 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2298                      enum lock_usage_bit bit, const char *irqclass)
2299 {
2300         int ret;
2301         struct lock_list root;
2302         struct lock_list *uninitialized_var(target_entry);
2303
2304         root.parent = NULL;
2305         root.class = hlock_class(this);
2306         ret = find_usage_forwards(&root, bit, &target_entry);
2307         if (ret < 0)
2308                 return print_bfs_bug(ret);
2309         if (ret == 1)
2310                 return ret;
2311
2312         return print_irq_inversion_bug(curr, &root, target_entry,
2313                                         this, 1, irqclass);
2314 }
2315
2316 /*
2317  * Prove that in the backwards-direction subgraph starting at <this>
2318  * there is no lock matching <mask>:
2319  */
2320 static int
2321 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2322                       enum lock_usage_bit bit, const char *irqclass)
2323 {
2324         int ret;
2325         struct lock_list root;
2326         struct lock_list *uninitialized_var(target_entry);
2327
2328         root.parent = NULL;
2329         root.class = hlock_class(this);
2330         ret = find_usage_backwards(&root, bit, &target_entry);
2331         if (ret < 0)
2332                 return print_bfs_bug(ret);
2333         if (ret == 1)
2334                 return ret;
2335
2336         return print_irq_inversion_bug(curr, &root, target_entry,
2337                                         this, 0, irqclass);
2338 }
2339
2340 void print_irqtrace_events(struct task_struct *curr)
2341 {
2342         printk("irq event stamp: %u\n", curr->irq_events);
2343         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2344         print_ip_sym(curr->hardirq_enable_ip);
2345         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2346         print_ip_sym(curr->hardirq_disable_ip);
2347         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2348         print_ip_sym(curr->softirq_enable_ip);
2349         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2350         print_ip_sym(curr->softirq_disable_ip);
2351 }
2352
2353 static int HARDIRQ_verbose(struct lock_class *class)
2354 {
2355 #if HARDIRQ_VERBOSE
2356         return class_filter(class);
2357 #endif
2358         return 0;
2359 }
2360
2361 static int SOFTIRQ_verbose(struct lock_class *class)
2362 {
2363 #if SOFTIRQ_VERBOSE
2364         return class_filter(class);
2365 #endif
2366         return 0;
2367 }
2368
2369 static int RECLAIM_FS_verbose(struct lock_class *class)
2370 {
2371 #if RECLAIM_VERBOSE
2372         return class_filter(class);
2373 #endif
2374         return 0;
2375 }
2376
2377 #define STRICT_READ_CHECKS      1
2378
2379 static int (*state_verbose_f[])(struct lock_class *class) = {
2380 #define LOCKDEP_STATE(__STATE) \
2381         __STATE##_verbose,
2382 #include "lockdep_states.h"
2383 #undef LOCKDEP_STATE
2384 };
2385
2386 static inline int state_verbose(enum lock_usage_bit bit,
2387                                 struct lock_class *class)
2388 {
2389         return state_verbose_f[bit >> 2](class);
2390 }
2391
2392 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2393                              enum lock_usage_bit bit, const char *name);
2394
2395 static int
2396 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2397                 enum lock_usage_bit new_bit)
2398 {
2399         int excl_bit = exclusive_bit(new_bit);
2400         int read = new_bit & 1;
2401         int dir = new_bit & 2;
2402
2403         /*
2404          * mark USED_IN has to look forwards -- to ensure no dependency
2405          * has ENABLED state, which would allow recursion deadlocks.
2406          *
2407          * mark ENABLED has to look backwards -- to ensure no dependee
2408          * has USED_IN state, which, again, would allow  recursion deadlocks.
2409          */
2410         check_usage_f usage = dir ?
2411                 check_usage_backwards : check_usage_forwards;
2412
2413         /*
2414          * Validate that this particular lock does not have conflicting
2415          * usage states.
2416          */
2417         if (!valid_state(curr, this, new_bit, excl_bit))
2418                 return 0;
2419
2420         /*
2421          * Validate that the lock dependencies don't have conflicting usage
2422          * states.
2423          */
2424         if ((!read || !dir || STRICT_READ_CHECKS) &&
2425                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2426                 return 0;
2427
2428         /*
2429          * Check for read in write conflicts
2430          */
2431         if (!read) {
2432                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2433                         return 0;
2434
2435                 if (STRICT_READ_CHECKS &&
2436                         !usage(curr, this, excl_bit + 1,
2437                                 state_name(new_bit + 1)))
2438                         return 0;
2439         }
2440
2441         if (state_verbose(new_bit, hlock_class(this)))
2442                 return 2;
2443
2444         return 1;
2445 }
2446
2447 enum mark_type {
2448 #define LOCKDEP_STATE(__STATE)  __STATE,
2449 #include "lockdep_states.h"
2450 #undef LOCKDEP_STATE
2451 };
2452
2453 /*
2454  * Mark all held locks with a usage bit:
2455  */
2456 static int
2457 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2458 {
2459         enum lock_usage_bit usage_bit;
2460         struct held_lock *hlock;
2461         int i;
2462
2463         for (i = 0; i < curr->lockdep_depth; i++) {
2464                 hlock = curr->held_locks + i;
2465
2466                 usage_bit = 2 + (mark << 2); /* ENABLED */
2467                 if (hlock->read)
2468                         usage_bit += 1; /* READ */
2469
2470                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2471
2472                 if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
2473                         continue;
2474
2475                 if (!mark_lock(curr, hlock, usage_bit))
2476                         return 0;
2477         }
2478
2479         return 1;
2480 }
2481
2482 /*
2483  * Hardirqs will be enabled:
2484  */
2485 static void __trace_hardirqs_on_caller(unsigned long ip)
2486 {
2487         struct task_struct *curr = current;
2488
2489         /* we'll do an OFF -> ON transition: */
2490         curr->hardirqs_enabled = 1;
2491
2492         /*
2493          * We are going to turn hardirqs on, so set the
2494          * usage bit for all held locks:
2495          */
2496         if (!mark_held_locks(curr, HARDIRQ))
2497                 return;
2498         /*
2499          * If we have softirqs enabled, then set the usage
2500          * bit for all held locks. (disabled hardirqs prevented
2501          * this bit from being set before)
2502          */
2503         if (curr->softirqs_enabled)
2504                 if (!mark_held_locks(curr, SOFTIRQ))
2505                         return;
2506
2507         curr->hardirq_enable_ip = ip;
2508         curr->hardirq_enable_event = ++curr->irq_events;
2509         debug_atomic_inc(hardirqs_on_events);
2510 }
2511
2512 void trace_hardirqs_on_caller(unsigned long ip)
2513 {
2514         time_hardirqs_on(CALLER_ADDR0, ip);
2515
2516         if (unlikely(!debug_locks || current->lockdep_recursion))
2517                 return;
2518
2519         if (unlikely(current->hardirqs_enabled)) {
2520                 /*
2521                  * Neither irq nor preemption are disabled here
2522                  * so this is racy by nature but losing one hit
2523                  * in a stat is not a big deal.
2524                  */
2525                 __debug_atomic_inc(redundant_hardirqs_on);
2526                 return;
2527         }
2528
2529         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2530                 return;
2531
2532         if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2533                 return;
2534
2535         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2536                 return;
2537
2538         current->lockdep_recursion = 1;
2539         __trace_hardirqs_on_caller(ip);
2540         current->lockdep_recursion = 0;
2541 }
2542 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2543
2544 void trace_hardirqs_on(void)
2545 {
2546         trace_hardirqs_on_caller(CALLER_ADDR0);
2547 }
2548 EXPORT_SYMBOL(trace_hardirqs_on);
2549
2550 /*
2551  * Hardirqs were disabled:
2552  */
2553 void trace_hardirqs_off_caller(unsigned long ip)
2554 {
2555         struct task_struct *curr = current;
2556
2557         time_hardirqs_off(CALLER_ADDR0, ip);
2558
2559         if (unlikely(!debug_locks || current->lockdep_recursion))
2560                 return;
2561
2562         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2563                 return;
2564
2565         if (curr->hardirqs_enabled) {
2566                 /*
2567                  * We have done an ON -> OFF transition:
2568                  */
2569                 curr->hardirqs_enabled = 0;
2570                 curr->hardirq_disable_ip = ip;
2571                 curr->hardirq_disable_event = ++curr->irq_events;
2572                 debug_atomic_inc(hardirqs_off_events);
2573         } else
2574                 debug_atomic_inc(redundant_hardirqs_off);
2575 }
2576 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2577
2578 void trace_hardirqs_off(void)
2579 {
2580         trace_hardirqs_off_caller(CALLER_ADDR0);
2581 }
2582 EXPORT_SYMBOL(trace_hardirqs_off);
2583
2584 /*
2585  * Softirqs will be enabled:
2586  */
2587 void trace_softirqs_on(unsigned long ip)
2588 {
2589         struct task_struct *curr = current;
2590
2591         if (unlikely(!debug_locks || current->lockdep_recursion))
2592                 return;
2593
2594         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2595                 return;
2596
2597         if (curr->softirqs_enabled) {
2598                 debug_atomic_inc(redundant_softirqs_on);
2599                 return;
2600         }
2601
2602         current->lockdep_recursion = 1;
2603         /*
2604          * We'll do an OFF -> ON transition:
2605          */
2606         curr->softirqs_enabled = 1;
2607         curr->softirq_enable_ip = ip;
2608         curr->softirq_enable_event = ++curr->irq_events;
2609         debug_atomic_inc(softirqs_on_events);
2610         /*
2611          * We are going to turn softirqs on, so set the
2612          * usage bit for all held locks, if hardirqs are
2613          * enabled too:
2614          */
2615         if (curr->hardirqs_enabled)
2616                 mark_held_locks(curr, SOFTIRQ);
2617         current->lockdep_recursion = 0;
2618 }
2619
2620 /*
2621  * Softirqs were disabled:
2622  */
2623 void trace_softirqs_off(unsigned long ip)
2624 {
2625         struct task_struct *curr = current;
2626
2627         if (unlikely(!debug_locks || current->lockdep_recursion))
2628                 return;
2629
2630         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2631                 return;
2632
2633         if (curr->softirqs_enabled) {
2634                 /*
2635                  * We have done an ON -> OFF transition:
2636                  */
2637                 curr->softirqs_enabled = 0;
2638                 curr->softirq_disable_ip = ip;
2639                 curr->softirq_disable_event = ++curr->irq_events;
2640                 debug_atomic_inc(softirqs_off_events);
2641                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2642         } else
2643                 debug_atomic_inc(redundant_softirqs_off);
2644 }
2645
2646 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2647 {
2648         struct task_struct *curr = current;
2649
2650         if (unlikely(!debug_locks))
2651                 return;
2652
2653         /* no reclaim without waiting on it */
2654         if (!(gfp_mask & __GFP_WAIT))
2655                 return;
2656
2657         /* this guy won't enter reclaim */
2658         if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2659                 return;
2660
2661         /* We're only interested __GFP_FS allocations for now */
2662         if (!(gfp_mask & __GFP_FS))
2663                 return;
2664
2665         if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2666                 return;
2667
2668         mark_held_locks(curr, RECLAIM_FS);
2669 }
2670
2671 static void check_flags(unsigned long flags);
2672
2673 void lockdep_trace_alloc(gfp_t gfp_mask)
2674 {
2675         unsigned long flags;
2676
2677         if (unlikely(current->lockdep_recursion))
2678                 return;
2679
2680         raw_local_irq_save(flags);
2681         check_flags(flags);
2682         current->lockdep_recursion = 1;
2683         __lockdep_trace_alloc(gfp_mask, flags);
2684         current->lockdep_recursion = 0;
2685         raw_local_irq_restore(flags);
2686 }
2687
2688 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2689 {
2690         /*
2691          * If non-trylock use in a hardirq or softirq context, then
2692          * mark the lock as used in these contexts:
2693          */
2694         if (!hlock->trylock) {
2695                 if (hlock->read) {
2696                         if (curr->hardirq_context)
2697                                 if (!mark_lock(curr, hlock,
2698                                                 LOCK_USED_IN_HARDIRQ_READ))
2699                                         return 0;
2700                         if (curr->softirq_context)
2701                                 if (!mark_lock(curr, hlock,
2702                                                 LOCK_USED_IN_SOFTIRQ_READ))
2703                                         return 0;
2704                 } else {
2705                         if (curr->hardirq_context)
2706                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2707                                         return 0;
2708                         if (curr->softirq_context)
2709                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2710                                         return 0;
2711                 }
2712         }
2713         if (!hlock->hardirqs_off) {
2714                 if (hlock->read) {
2715                         if (!mark_lock(curr, hlock,
2716                                         LOCK_ENABLED_HARDIRQ_READ))
2717                                 return 0;
2718                         if (curr->softirqs_enabled)
2719                                 if (!mark_lock(curr, hlock,
2720                                                 LOCK_ENABLED_SOFTIRQ_READ))
2721                                         return 0;
2722                 } else {
2723                         if (!mark_lock(curr, hlock,
2724                                         LOCK_ENABLED_HARDIRQ))
2725                                 return 0;
2726                         if (curr->softirqs_enabled)
2727                                 if (!mark_lock(curr, hlock,
2728                                                 LOCK_ENABLED_SOFTIRQ))
2729                                         return 0;
2730                 }
2731         }
2732
2733         /*
2734          * We reuse the irq context infrastructure more broadly as a general
2735          * context checking code. This tests GFP_FS recursion (a lock taken
2736          * during reclaim for a GFP_FS allocation is held over a GFP_FS
2737          * allocation).
2738          */
2739         if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2740                 if (hlock->read) {
2741                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2742                                         return 0;
2743                 } else {
2744                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2745                                         return 0;
2746                 }
2747         }
2748
2749         return 1;
2750 }
2751
2752 static int separate_irq_context(struct task_struct *curr,
2753                 struct held_lock *hlock)
2754 {
2755         unsigned int depth = curr->lockdep_depth;
2756
2757         /*
2758          * Keep track of points where we cross into an interrupt context:
2759          */
2760         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2761                                 curr->softirq_context;
2762         if (depth) {
2763                 struct held_lock *prev_hlock;
2764
2765                 prev_hlock = curr->held_locks + depth-1;
2766                 /*
2767                  * If we cross into another context, reset the
2768                  * hash key (this also prevents the checking and the
2769                  * adding of the dependency to 'prev'):
2770                  */
2771                 if (prev_hlock->irq_context != hlock->irq_context)
2772                         return 1;
2773         }
2774         return 0;
2775 }
2776
2777 #else
2778
2779 static inline
2780 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2781                 enum lock_usage_bit new_bit)
2782 {
2783         WARN_ON(1);
2784         return 1;
2785 }
2786
2787 static inline int mark_irqflags(struct task_struct *curr,
2788                 struct held_lock *hlock)
2789 {
2790         return 1;
2791 }
2792
2793 static inline int separate_irq_context(struct task_struct *curr,
2794                 struct held_lock *hlock)
2795 {
2796         return 0;
2797 }
2798
2799 void lockdep_trace_alloc(gfp_t gfp_mask)
2800 {
2801 }
2802
2803 #endif
2804
2805 /*
2806  * Mark a lock with a usage bit, and validate the state transition:
2807  */
2808 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2809                              enum lock_usage_bit new_bit)
2810 {
2811         unsigned int new_mask = 1 << new_bit, ret = 1;
2812
2813         /*
2814          * If already set then do not dirty the cacheline,
2815          * nor do any checks:
2816          */
2817         if (likely(hlock_class(this)->usage_mask & new_mask))
2818                 return 1;
2819
2820         if (!graph_lock())
2821                 return 0;
2822         /*
2823          * Make sure we didn't race:
2824          */
2825         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2826                 graph_unlock();
2827                 return 1;
2828         }
2829
2830         hlock_class(this)->usage_mask |= new_mask;
2831
2832         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2833                 return 0;
2834
2835         switch (new_bit) {
2836 #define LOCKDEP_STATE(__STATE)                  \
2837         case LOCK_USED_IN_##__STATE:            \
2838         case LOCK_USED_IN_##__STATE##_READ:     \
2839         case LOCK_ENABLED_##__STATE:            \
2840         case LOCK_ENABLED_##__STATE##_READ:
2841 #include "lockdep_states.h"
2842 #undef LOCKDEP_STATE
2843                 ret = mark_lock_irq(curr, this, new_bit);
2844                 if (!ret)
2845                         return 0;
2846                 break;
2847         case LOCK_USED:
2848                 debug_atomic_dec(nr_unused_locks);
2849                 break;
2850         default:
2851                 if (!debug_locks_off_graph_unlock())
2852                         return 0;
2853                 WARN_ON(1);
2854                 return 0;
2855         }
2856
2857         graph_unlock();
2858
2859         /*
2860          * We must printk outside of the graph_lock:
2861          */
2862         if (ret == 2) {
2863                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2864                 print_lock(this);
2865                 print_irqtrace_events(curr);
2866                 dump_stack();
2867         }
2868
2869         return ret;
2870 }
2871
2872 /*
2873  * Initialize a lock instance's lock-class mapping info:
2874  */
2875 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2876                       struct lock_class_key *key, int subclass)
2877 {
2878         int i;
2879
2880         kmemcheck_mark_initialized(lock, sizeof(*lock));
2881
2882         for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2883                 lock->class_cache[i] = NULL;
2884
2885 #ifdef CONFIG_LOCK_STAT
2886         lock->cpu = raw_smp_processor_id();
2887 #endif
2888
2889         if (DEBUG_LOCKS_WARN_ON(!name)) {
2890                 lock->name = "NULL";
2891                 return;
2892         }
2893
2894         lock->name = name;
2895
2896         if (DEBUG_LOCKS_WARN_ON(!key))
2897                 return;
2898         /*
2899          * Sanity check, the lock-class key must be persistent:
2900          */
2901         if (!static_obj(key)) {
2902                 printk("BUG: key %p not in .data!\n", key);
2903                 DEBUG_LOCKS_WARN_ON(1);
2904                 return;
2905         }
2906         lock->key = key;
2907
2908         if (unlikely(!debug_locks))
2909                 return;
2910
2911         if (subclass)
2912                 register_lock_class(lock, subclass, 1);
2913 }
2914 EXPORT_SYMBOL_GPL(lockdep_init_map);
2915
2916 struct lock_class_key __lockdep_no_validate__;
2917
2918 /*
2919  * This gets called for every mutex_lock*()/spin_lock*() operation.
2920  * We maintain the dependency maps and validate the locking attempt:
2921  */
2922 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2923                           int trylock, int read, int check, int hardirqs_off,
2924                           struct lockdep_map *nest_lock, unsigned long ip,
2925                           int references)
2926 {
2927         struct task_struct *curr = current;
2928         struct lock_class *class = NULL;
2929         struct held_lock *hlock;
2930         unsigned int depth, id;
2931         int chain_head = 0;
2932         int class_idx;
2933         u64 chain_key;
2934
2935         if (!prove_locking)
2936                 check = 1;
2937
2938         if (unlikely(!debug_locks))
2939                 return 0;
2940
2941         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2942                 return 0;
2943
2944         if (lock->key == &__lockdep_no_validate__)
2945                 check = 1;
2946
2947         if (subclass < NR_LOCKDEP_CACHING_CLASSES)
2948                 class = lock->class_cache[subclass];
2949         /*
2950          * Not cached?
2951          */
2952         if (unlikely(!class)) {
2953                 class = register_lock_class(lock, subclass, 0);
2954                 if (!class)
2955                         return 0;
2956         }
2957         atomic_inc((atomic_t *)&class->ops);
2958         if (very_verbose(class)) {
2959                 printk("\nacquire class [%p] %s", class->key, class->name);
2960                 if (class->name_version > 1)
2961                         printk("#%d", class->name_version);
2962                 printk("\n");
2963                 dump_stack();
2964         }
2965
2966         /*
2967          * Add the lock to the list of currently held locks.
2968          * (we dont increase the depth just yet, up until the
2969          * dependency checks are done)
2970          */
2971         depth = curr->lockdep_depth;
2972         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2973                 return 0;
2974
2975         class_idx = class - lock_classes + 1;
2976
2977         if (depth) {
2978                 hlock = curr->held_locks + depth - 1;
2979                 if (hlock->class_idx == class_idx && nest_lock) {
2980                         if (hlock->references)
2981                                 hlock->references++;
2982                         else
2983                                 hlock->references = 2;
2984
2985                         return 1;
2986                 }
2987         }
2988
2989         hlock = curr->held_locks + depth;
2990         if (DEBUG_LOCKS_WARN_ON(!class))
2991                 return 0;
2992         hlock->class_idx = class_idx;
2993         hlock->acquire_ip = ip;
2994         hlock->instance = lock;
2995         hlock->nest_lock = nest_lock;
2996         hlock->trylock = trylock;
2997         hlock->read = read;
2998         hlock->check = check;
2999         hlock->hardirqs_off = !!hardirqs_off;
3000         hlock->references = references;
3001 #ifdef CONFIG_LOCK_STAT
3002         hlock->waittime_stamp = 0;
3003         hlock->holdtime_stamp = lockstat_clock();
3004 #endif
3005
3006         if (check == 2 && !mark_irqflags(curr, hlock))
3007                 return 0;
3008
3009         /* mark it as used: */
3010         if (!mark_lock(curr, hlock, LOCK_USED))
3011                 return 0;
3012
3013         /*
3014          * Calculate the chain hash: it's the combined hash of all the
3015          * lock keys along the dependency chain. We save the hash value
3016          * at every step so that we can get the current hash easily
3017          * after unlock. The chain hash is then used to cache dependency
3018          * results.
3019          *
3020          * The 'key ID' is what is the most compact key value to drive
3021          * the hash, not class->key.
3022          */
3023         id = class - lock_classes;
3024         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3025                 return 0;
3026
3027         chain_key = curr->curr_chain_key;
3028         if (!depth) {
3029                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3030                         return 0;
3031                 chain_head = 1;
3032         }
3033
3034         hlock->prev_chain_key = chain_key;
3035         if (separate_irq_context(curr, hlock)) {
3036                 chain_key = 0;
3037                 chain_head = 1;
3038         }
3039         chain_key = iterate_chain_key(chain_key, id);
3040
3041         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3042                 return 0;
3043
3044         curr->curr_chain_key = chain_key;
3045         curr->lockdep_depth++;
3046         check_chain_key(curr);
3047 #ifdef CONFIG_DEBUG_LOCKDEP
3048         if (unlikely(!debug_locks))
3049                 return 0;
3050 #endif
3051         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3052                 debug_locks_off();
3053                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
3054                 printk("turning off the locking correctness validator.\n");
3055                 dump_stack();
3056                 return 0;
3057         }
3058
3059         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3060                 max_lockdep_depth = curr->lockdep_depth;
3061
3062         return 1;
3063 }
3064
3065 static int
3066 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3067                            unsigned long ip)
3068 {
3069         if (!debug_locks_off())
3070                 return 0;
3071         if (debug_locks_silent)
3072                 return 0;
3073
3074         printk("\n=====================================\n");
3075         printk(  "[ BUG: bad unlock balance detected! ]\n");
3076         printk(  "-------------------------------------\n");
3077         printk("%s/%d is trying to release lock (",
3078                 curr->comm, task_pid_nr(curr));
3079         print_lockdep_cache(lock);
3080         printk(") at:\n");
3081         print_ip_sym(ip);
3082         printk("but there are no more locks to release!\n");
3083         printk("\nother info that might help us debug this:\n");
3084         lockdep_print_held_locks(curr);
3085
3086         printk("\nstack backtrace:\n");
3087         dump_stack();
3088
3089         return 0;
3090 }
3091
3092 /*
3093  * Common debugging checks for both nested and non-nested unlock:
3094  */
3095 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3096                         unsigned long ip)
3097 {
3098         if (unlikely(!debug_locks))
3099                 return 0;
3100         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3101                 return 0;
3102
3103         if (curr->lockdep_depth <= 0)
3104                 return print_unlock_inbalance_bug(curr, lock, ip);
3105
3106         return 1;
3107 }
3108
3109 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3110 {
3111         if (hlock->instance == lock)
3112                 return 1;
3113
3114         if (hlock->references) {
3115                 struct lock_class *class = lock->class_cache[0];
3116
3117                 if (!class)
3118                         class = look_up_lock_class(lock, 0);
3119
3120                 /*
3121                  * If look_up_lock_class() failed to find a class, we're trying
3122                  * to test if we hold a lock that has never yet been acquired.
3123                  * Clearly if the lock hasn't been acquired _ever_, we're not
3124                  * holding it either, so report failure.
3125                  */
3126                 if (!class)
3127                         return 0;
3128
3129                 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3130                         return 0;
3131
3132                 if (hlock->class_idx == class - lock_classes + 1)
3133                         return 1;
3134         }
3135
3136         return 0;
3137 }
3138
3139 static int
3140 __lock_set_class(struct lockdep_map *lock, const char *name,
3141                  struct lock_class_key *key, unsigned int subclass,
3142                  unsigned long ip)
3143 {
3144         struct task_struct *curr = current;
3145         struct held_lock *hlock, *prev_hlock;
3146         struct lock_class *class;
3147         unsigned int depth;
3148         int i;
3149
3150         depth = curr->lockdep_depth;
3151         if (DEBUG_LOCKS_WARN_ON(!depth))
3152                 return 0;
3153
3154         prev_hlock = NULL;
3155         for (i = depth-1; i >= 0; i--) {
3156                 hlock = curr->held_locks + i;
3157                 /*
3158                  * We must not cross into another context:
3159                  */
3160                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3161                         break;
3162                 if (match_held_lock(hlock, lock))
3163                         goto found_it;
3164                 prev_hlock = hlock;
3165         }
3166         return print_unlock_inbalance_bug(curr, lock, ip);
3167
3168 found_it:
3169         lockdep_init_map(lock, name, key, 0);
3170         class = register_lock_class(lock, subclass, 0);
3171         hlock->class_idx = class - lock_classes + 1;
3172
3173         curr->lockdep_depth = i;
3174         curr->curr_chain_key = hlock->prev_chain_key;
3175
3176         for (; i < depth; i++) {
3177                 hlock = curr->held_locks + i;
3178                 if (!__lock_acquire(hlock->instance,
3179                         hlock_class(hlock)->subclass, hlock->trylock,
3180                                 hlock->read, hlock->check, hlock->hardirqs_off,
3181                                 hlock->nest_lock, hlock->acquire_ip,
3182                                 hlock->references))
3183                         return 0;
3184         }
3185
3186         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3187                 return 0;
3188         return 1;
3189 }
3190
3191 /*
3192  * Remove the lock to the list of currently held locks in a
3193  * potentially non-nested (out of order) manner. This is a
3194  * relatively rare operation, as all the unlock APIs default
3195  * to nested mode (which uses lock_release()):
3196  */
3197 static int
3198 lock_release_non_nested(struct task_struct *curr,
3199                         struct lockdep_map *lock, unsigned long ip)
3200 {
3201         struct held_lock *hlock, *prev_hlock;
3202         unsigned int depth;
3203         int i;
3204
3205         /*
3206          * Check whether the lock exists in the current stack
3207          * of held locks:
3208          */
3209         depth = curr->lockdep_depth;
3210         if (DEBUG_LOCKS_WARN_ON(!depth))
3211                 return 0;
3212
3213         prev_hlock = NULL;
3214         for (i = depth-1; i >= 0; i--) {
3215                 hlock = curr->held_locks + i;
3216                 /*
3217                  * We must not cross into another context:
3218                  */
3219                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3220                         break;
3221                 if (match_held_lock(hlock, lock))
3222                         goto found_it;
3223                 prev_hlock = hlock;
3224         }
3225         return print_unlock_inbalance_bug(curr, lock, ip);
3226
3227 found_it:
3228         if (hlock->instance == lock)
3229                 lock_release_holdtime(hlock);
3230
3231         if (hlock->references) {
3232                 hlock->references--;
3233                 if (hlock->references) {
3234                         /*
3235                          * We had, and after removing one, still have
3236                          * references, the current lock stack is still
3237                          * valid. We're done!
3238                          */
3239                         return 1;
3240                 }
3241         }
3242
3243         /*
3244          * We have the right lock to unlock, 'hlock' points to it.
3245          * Now we remove it from the stack, and add back the other
3246          * entries (if any), recalculating the hash along the way:
3247          */
3248
3249         curr->lockdep_depth = i;
3250         curr->curr_chain_key = hlock->prev_chain_key;
3251
3252         for (i++; i < depth; i++) {
3253                 hlock = curr->held_locks + i;
3254                 if (!__lock_acquire(hlock->instance,
3255                         hlock_class(hlock)->subclass, hlock->trylock,
3256                                 hlock->read, hlock->check, hlock->hardirqs_off,
3257                                 hlock->nest_lock, hlock->acquire_ip,
3258                                 hlock->references))
3259                         return 0;
3260         }
3261
3262         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3263                 return 0;
3264         return 1;
3265 }
3266
3267 /*
3268  * Remove the lock to the list of currently held locks - this gets
3269  * called on mutex_unlock()/spin_unlock*() (or on a failed
3270  * mutex_lock_interruptible()). This is done for unlocks that nest
3271  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3272  */
3273 static int lock_release_nested(struct task_struct *curr,
3274                                struct lockdep_map *lock, unsigned long ip)
3275 {
3276         struct held_lock *hlock;
3277         unsigned int depth;
3278
3279         /*
3280          * Pop off the top of the lock stack:
3281          */
3282         depth = curr->lockdep_depth - 1;
3283         hlock = curr->held_locks + depth;
3284
3285         /*
3286          * Is the unlock non-nested:
3287          */
3288         if (hlock->instance != lock || hlock->references)
3289                 return lock_release_non_nested(curr, lock, ip);
3290         curr->lockdep_depth--;
3291
3292         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3293                 return 0;
3294
3295         curr->curr_chain_key = hlock->prev_chain_key;
3296
3297         lock_release_holdtime(hlock);
3298
3299 #ifdef CONFIG_DEBUG_LOCKDEP
3300         hlock->prev_chain_key = 0;
3301         hlock->class_idx = 0;
3302         hlock->acquire_ip = 0;
3303         hlock->irq_context = 0;
3304 #endif
3305         return 1;
3306 }
3307
3308 /*
3309  * Remove the lock to the list of currently held locks - this gets
3310  * called on mutex_unlock()/spin_unlock*() (or on a failed
3311  * mutex_lock_interruptible()). This is done for unlocks that nest
3312  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3313  */
3314 static void
3315 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3316 {
3317         struct task_struct *curr = current;
3318
3319         if (!check_unlock(curr, lock, ip))
3320                 return;
3321
3322         if (nested) {
3323                 if (!lock_release_nested(curr, lock, ip))
3324                         return;
3325         } else {
3326                 if (!lock_release_non_nested(curr, lock, ip))
3327                         return;
3328         }
3329
3330         check_chain_key(curr);
3331 }
3332
3333 static int __lock_is_held(struct lockdep_map *lock)
3334 {
3335         struct task_struct *curr = current;
3336         int i;
3337
3338         for (i = 0; i < curr->lockdep_depth; i++) {
3339                 struct held_lock *hlock = curr->held_locks + i;
3340
3341                 if (match_held_lock(hlock, lock))
3342                         return 1;
3343         }
3344
3345         return 0;
3346 }
3347
3348 /*
3349  * Check whether we follow the irq-flags state precisely:
3350  */
3351 static void check_flags(unsigned long flags)
3352 {
3353 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3354     defined(CONFIG_TRACE_IRQFLAGS)
3355         if (!debug_locks)
3356                 return;
3357
3358         if (irqs_disabled_flags(flags)) {
3359                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3360                         printk("possible reason: unannotated irqs-off.\n");
3361                 }
3362         } else {
3363                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3364                         printk("possible reason: unannotated irqs-on.\n");
3365                 }
3366         }
3367
3368         /*
3369          * We dont accurately track softirq state in e.g.
3370          * hardirq contexts (such as on 4KSTACKS), so only
3371          * check if not in hardirq contexts:
3372          */
3373         if (!hardirq_count()) {
3374                 if (softirq_count())
3375                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3376                 else
3377                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3378         }
3379
3380         if (!debug_locks)
3381                 print_irqtrace_events(current);
3382 #endif
3383 }
3384
3385 void lock_set_class(struct lockdep_map *lock, const char *name,
3386                     struct lock_class_key *key, unsigned int subclass,
3387                     unsigned long ip)
3388 {
3389         unsigned long flags;
3390
3391         if (unlikely(current->lockdep_recursion))
3392                 return;
3393
3394         raw_local_irq_save(flags);
3395         current->lockdep_recursion = 1;
3396         check_flags(flags);
3397         if (__lock_set_class(lock, name, key, subclass, ip))
3398                 check_chain_key(current);
3399         current->lockdep_recursion = 0;
3400         raw_local_irq_restore(flags);
3401 }
3402 EXPORT_SYMBOL_GPL(lock_set_class);
3403
3404 /*
3405  * We are not always called with irqs disabled - do that here,
3406  * and also avoid lockdep recursion:
3407  */
3408 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3409                           int trylock, int read, int check,
3410                           struct lockdep_map *nest_lock, unsigned long ip)
3411 {
3412         unsigned long flags;
3413
3414         if (unlikely(current->lockdep_recursion))
3415                 return;
3416
3417         raw_local_irq_save(flags);
3418         check_flags(flags);
3419
3420         current->lockdep_recursion = 1;
3421         trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3422         __lock_acquire(lock, subclass, trylock, read, check,
3423                        irqs_disabled_flags(flags), nest_lock, ip, 0);
3424         current->lockdep_recursion = 0;
3425         raw_local_irq_restore(flags);
3426 }
3427 EXPORT_SYMBOL_GPL(lock_acquire);
3428
3429 void lock_release(struct lockdep_map *lock, int nested,
3430                           unsigned long ip)
3431 {
3432         unsigned long flags;
3433
3434         if (unlikely(current->lockdep_recursion))
3435                 return;
3436
3437         raw_local_irq_save(flags);
3438         check_flags(flags);
3439         current->lockdep_recursion = 1;
3440         trace_lock_release(lock, ip);
3441         __lock_release(lock, nested, ip);
3442         current->lockdep_recursion = 0;
3443         raw_local_irq_restore(flags);
3444 }
3445 EXPORT_SYMBOL_GPL(lock_release);
3446
3447 int lock_is_held(struct lockdep_map *lock)
3448 {
3449         unsigned long flags;
3450         int ret = 0;
3451
3452         if (unlikely(current->lockdep_recursion))
3453                 return 1; /* avoid false negative lockdep_assert_held() */
3454
3455         raw_local_irq_save(flags);
3456         check_flags(flags);
3457
3458         current->lockdep_recursion = 1;
3459         ret = __lock_is_held(lock);
3460         current->lockdep_recursion = 0;
3461         raw_local_irq_restore(flags);
3462
3463         return ret;
3464 }
3465 EXPORT_SYMBOL_GPL(lock_is_held);
3466
3467 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3468 {
3469         current->lockdep_reclaim_gfp = gfp_mask;
3470 }
3471
3472 void lockdep_clear_current_reclaim_state(void)
3473 {
3474         current->lockdep_reclaim_gfp = 0;
3475 }
3476
3477 #ifdef CONFIG_LOCK_STAT
3478 static int
3479 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3480                            unsigned long ip)
3481 {
3482         if (!debug_locks_off())
3483                 return 0;
3484         if (debug_locks_silent)
3485                 return 0;
3486
3487         printk("\n=================================\n");
3488         printk(  "[ BUG: bad contention detected! ]\n");
3489         printk(  "---------------------------------\n");
3490         printk("%s/%d is trying to contend lock (",
3491                 curr->comm, task_pid_nr(curr));
3492         print_lockdep_cache(lock);
3493         printk(") at:\n");
3494         print_ip_sym(ip);
3495         printk("but there are no locks held!\n");
3496         printk("\nother info that might help us debug this:\n");
3497         lockdep_print_held_locks(curr);
3498
3499         printk("\nstack backtrace:\n");
3500         dump_stack();
3501
3502         return 0;
3503 }
3504
3505 static void
3506 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3507 {
3508         struct task_struct *curr = current;
3509         struct held_lock *hlock, *prev_hlock;
3510         struct lock_class_stats *stats;
3511         unsigned int depth;
3512         int i, contention_point, contending_point;
3513
3514         depth = curr->lockdep_depth;
3515         if (DEBUG_LOCKS_WARN_ON(!depth))
3516                 return;
3517
3518         prev_hlock = NULL;
3519         for (i = depth-1; i >= 0; i--) {
3520                 hlock = curr->held_locks + i;
3521                 /*
3522                  * We must not cross into another context:
3523                  */
3524                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3525                         break;
3526                 if (match_held_lock(hlock, lock))
3527                         goto found_it;
3528                 prev_hlock = hlock;
3529         }
3530         print_lock_contention_bug(curr, lock, ip);
3531         return;
3532
3533 found_it:
3534         if (hlock->instance != lock)
3535                 return;
3536
3537         hlock->waittime_stamp = lockstat_clock();
3538
3539         contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3540         contending_point = lock_point(hlock_class(hlock)->contending_point,
3541                                       lock->ip);
3542
3543         stats = get_lock_stats(hlock_class(hlock));
3544         if (contention_point < LOCKSTAT_POINTS)
3545                 stats->contention_point[contention_point]++;
3546         if (contending_point < LOCKSTAT_POINTS)
3547                 stats->contending_point[contending_point]++;
3548         if (lock->cpu != smp_processor_id())
3549                 stats->bounces[bounce_contended + !!hlock->read]++;
3550         put_lock_stats(stats);
3551 }
3552
3553 static void
3554 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3555 {
3556         struct task_struct *curr = current;
3557         struct held_lock *hlock, *prev_hlock;
3558         struct lock_class_stats *stats;
3559         unsigned int depth;
3560         u64 now, waittime = 0;
3561         int i, cpu;
3562
3563         depth = curr->lockdep_depth;
3564         if (DEBUG_LOCKS_WARN_ON(!depth))
3565                 return;
3566
3567         prev_hlock = NULL;
3568         for (i = depth-1; i >= 0; i--) {
3569                 hlock = curr->held_locks + i;
3570                 /*
3571                  * We must not cross into another context:
3572                  */
3573                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3574                         break;
3575                 if (match_held_lock(hlock, lock))
3576                         goto found_it;
3577                 prev_hlock = hlock;
3578         }
3579         print_lock_contention_bug(curr, lock, _RET_IP_);
3580         return;
3581
3582 found_it:
3583         if (hlock->instance != lock)
3584                 return;
3585
3586         cpu = smp_processor_id();
3587         if (hlock->waittime_stamp) {
3588                 now = lockstat_clock();
3589                 waittime = now - hlock->waittime_stamp;
3590                 hlock->holdtime_stamp = now;
3591         }
3592
3593         trace_lock_acquired(lock, ip);
3594
3595         stats = get_lock_stats(hlock_class(hlock));
3596         if (waittime) {
3597                 if (hlock->read)
3598                         lock_time_inc(&stats->read_waittime, waittime);
3599                 else
3600                         lock_time_inc(&stats->write_waittime, waittime);
3601         }
3602         if (lock->cpu != cpu)
3603                 stats->bounces[bounce_acquired + !!hlock->read]++;
3604         put_lock_stats(stats);
3605
3606         lock->cpu = cpu;
3607         lock->ip = ip;
3608 }
3609
3610 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3611 {
3612         unsigned long flags;
3613
3614         if (unlikely(!lock_stat))
3615                 return;
3616
3617         if (unlikely(current->lockdep_recursion))
3618                 return;
3619
3620         raw_local_irq_save(flags);
3621         check_flags(flags);
3622         current->lockdep_recursion = 1;
3623         trace_lock_contended(lock, ip);
3624         __lock_contended(lock, ip);
3625         current->lockdep_recursion = 0;
3626         raw_local_irq_restore(flags);
3627 }
3628 EXPORT_SYMBOL_GPL(lock_contended);
3629
3630 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3631 {
3632         unsigned long flags;
3633
3634         if (unlikely(!lock_stat))
3635                 return;
3636
3637         if (unlikely(current->lockdep_recursion))
3638                 return;
3639
3640         raw_local_irq_save(flags);
3641         check_flags(flags);
3642         current->lockdep_recursion = 1;
3643         __lock_acquired(lock, ip);
3644         current->lockdep_recursion = 0;
3645         raw_local_irq_restore(flags);
3646 }
3647 EXPORT_SYMBOL_GPL(lock_acquired);
3648 #endif
3649
3650 /*
3651  * Used by the testsuite, sanitize the validator state
3652  * after a simulated failure:
3653  */
3654
3655 void lockdep_reset(void)
3656 {
3657         unsigned long flags;
3658         int i;
3659
3660         raw_local_irq_save(flags);
3661         current->curr_chain_key = 0;
3662         current->lockdep_depth = 0;
3663         current->lockdep_recursion = 0;
3664         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3665         nr_hardirq_chains = 0;
3666         nr_softirq_chains = 0;
3667         nr_process_chains = 0;
3668         debug_locks = 1;
3669         for (i = 0; i < CHAINHASH_SIZE; i++)
3670                 INIT_LIST_HEAD(chainhash_table + i);
3671         raw_local_irq_restore(flags);
3672 }
3673
3674 static void zap_class(struct lock_class *class)
3675 {
3676         int i;
3677
3678         /*
3679          * Remove all dependencies this lock is
3680          * involved in:
3681          */
3682         for (i = 0; i < nr_list_entries; i++) {
3683                 if (list_entries[i].class == class)
3684                         list_del_rcu(&list_entries[i].entry);
3685         }
3686         /*
3687          * Unhash the class and remove it from the all_lock_classes list:
3688          */
3689         list_del_rcu(&class->hash_entry);
3690         list_del_rcu(&class->lock_entry);
3691
3692         class->key = NULL;
3693 }
3694
3695 static inline int within(const void *addr, void *start, unsigned long size)
3696 {
3697         return addr >= start && addr < start + size;
3698 }
3699
3700 void lockdep_free_key_range(void *start, unsigned long size)
3701 {
3702         struct lock_class *class, *next;
3703         struct list_head *head;
3704         unsigned long flags;
3705         int i;
3706         int locked;
3707
3708         raw_local_irq_save(flags);
3709         locked = graph_lock();
3710
3711         /*
3712          * Unhash all classes that were created by this module:
3713          */
3714         for (i = 0; i < CLASSHASH_SIZE; i++) {
3715                 head = classhash_table + i;
3716                 if (list_empty(head))
3717                         continue;
3718                 list_for_each_entry_safe(class, next, head, hash_entry) {
3719                         if (within(class->key, start, size))
3720                                 zap_class(class);
3721                         else if (within(class->name, start, size))
3722                                 zap_class(class);
3723                 }
3724         }
3725
3726         if (locked)
3727                 graph_unlock();
3728         raw_local_irq_restore(flags);
3729 }
3730
3731 void lockdep_reset_lock(struct lockdep_map *lock)
3732 {
3733         struct lock_class *class, *next;
3734         struct list_head *head;
3735         unsigned long flags;
3736         int i, j;
3737         int locked;
3738
3739         raw_local_irq_save(flags);
3740
3741         /*
3742          * Remove all classes this lock might have:
3743          */
3744         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3745                 /*
3746                  * If the class exists we look it up and zap it:
3747                  */
3748                 class = look_up_lock_class(lock, j);
3749                 if (class)
3750                         zap_class(class);
3751         }
3752         /*
3753          * Debug check: in the end all mapped classes should
3754          * be gone.
3755          */
3756         locked = graph_lock();
3757         for (i = 0; i < CLASSHASH_SIZE; i++) {
3758                 head = classhash_table + i;
3759                 if (list_empty(head))
3760                         continue;
3761                 list_for_each_entry_safe(class, next, head, hash_entry) {
3762                         int match = 0;
3763
3764                         for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3765                                 match |= class == lock->class_cache[j];
3766
3767                         if (unlikely(match)) {
3768                                 if (debug_locks_off_graph_unlock())
3769                                         WARN_ON(1);
3770                                 goto out_restore;
3771                         }
3772                 }
3773         }
3774         if (locked)
3775                 graph_unlock();
3776
3777 out_restore:
3778         raw_local_irq_restore(flags);
3779 }
3780
3781 void lockdep_init(void)
3782 {
3783         int i;
3784
3785         /*
3786          * Some architectures have their own start_kernel()
3787          * code which calls lockdep_init(), while we also
3788          * call lockdep_init() from the start_kernel() itself,
3789          * and we want to initialize the hashes only once:
3790          */
3791         if (lockdep_initialized)
3792                 return;
3793
3794         for (i = 0; i < CLASSHASH_SIZE; i++)
3795                 INIT_LIST_HEAD(classhash_table + i);
3796
3797         for (i = 0; i < CHAINHASH_SIZE; i++)
3798                 INIT_LIST_HEAD(chainhash_table + i);
3799
3800         lockdep_initialized = 1;
3801 }
3802
3803 void __init lockdep_info(void)
3804 {
3805         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3806
3807         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3808         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3809         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3810         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3811         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3812         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3813         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3814
3815         printk(" memory used by lock dependency info: %lu kB\n",
3816                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3817                 sizeof(struct list_head) * CLASSHASH_SIZE +
3818                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3819                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3820                 sizeof(struct list_head) * CHAINHASH_SIZE
3821 #ifdef CONFIG_PROVE_LOCKING
3822                 + sizeof(struct circular_queue)
3823 #endif
3824                 ) / 1024
3825                 );
3826
3827         printk(" per task-struct memory footprint: %lu bytes\n",
3828                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3829
3830 #ifdef CONFIG_DEBUG_LOCKDEP
3831         if (lockdep_init_error) {
3832                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3833                 printk("Call stack leading to lockdep invocation was:\n");
3834                 print_stack_trace(&lockdep_init_trace, 0);
3835         }
3836 #endif
3837 }
3838
3839 static void
3840 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3841                      const void *mem_to, struct held_lock *hlock)
3842 {
3843         if (!debug_locks_off())
3844                 return;
3845         if (debug_locks_silent)
3846                 return;
3847
3848         printk("\n=========================\n");
3849         printk(  "[ BUG: held lock freed! ]\n");
3850         printk(  "-------------------------\n");
3851         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3852                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3853         print_lock(hlock);
3854         lockdep_print_held_locks(curr);
3855
3856         printk("\nstack backtrace:\n");
3857         dump_stack();
3858 }
3859
3860 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3861                                 const void* lock_from, unsigned long lock_len)
3862 {
3863         return lock_from + lock_len <= mem_from ||
3864                 mem_from + mem_len <= lock_from;
3865 }
3866
3867 /*
3868  * Called when kernel memory is freed (or unmapped), or if a lock
3869  * is destroyed or reinitialized - this code checks whether there is
3870  * any held lock in the memory range of <from> to <to>:
3871  */
3872 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3873 {
3874         struct task_struct *curr = current;
3875         struct held_lock *hlock;
3876         unsigned long flags;
3877         int i;
3878
3879         if (unlikely(!debug_locks))
3880                 return;
3881
3882         local_irq_save(flags);
3883         for (i = 0; i < curr->lockdep_depth; i++) {
3884                 hlock = curr->held_locks + i;
3885
3886                 if (not_in_range(mem_from, mem_len, hlock->instance,
3887                                         sizeof(*hlock->instance)))
3888                         continue;
3889
3890                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3891                 break;
3892         }
3893         local_irq_restore(flags);
3894 }
3895 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3896
3897 static void print_held_locks_bug(struct task_struct *curr)
3898 {
3899         if (!debug_locks_off())
3900                 return;
3901         if (debug_locks_silent)
3902                 return;
3903
3904         printk("\n=====================================\n");
3905         printk(  "[ BUG: lock held at task exit time! ]\n");
3906         printk(  "-------------------------------------\n");
3907         printk("%s/%d is exiting with locks still held!\n",
3908                 curr->comm, task_pid_nr(curr));
3909         lockdep_print_held_locks(curr);
3910
3911         printk("\nstack backtrace:\n");
3912         dump_stack();
3913 }
3914
3915 void debug_check_no_locks_held(struct task_struct *task)
3916 {
3917         if (unlikely(task->lockdep_depth > 0))
3918                 print_held_locks_bug(task);
3919 }
3920
3921 void debug_show_all_locks(void)
3922 {
3923         struct task_struct *g, *p;
3924         int count = 10;
3925         int unlock = 1;
3926
3927         if (unlikely(!debug_locks)) {
3928                 printk("INFO: lockdep is turned off.\n");
3929                 return;
3930         }
3931         printk("\nShowing all locks held in the system:\n");
3932
3933         /*
3934          * Here we try to get the tasklist_lock as hard as possible,
3935          * if not successful after 2 seconds we ignore it (but keep
3936          * trying). This is to enable a debug printout even if a
3937          * tasklist_lock-holding task deadlocks or crashes.
3938          */
3939 retry:
3940         if (!read_trylock(&tasklist_lock)) {
3941                 if (count == 10)
3942                         printk("hm, tasklist_lock locked, retrying... ");
3943                 if (count) {
3944                         count--;
3945                         printk(" #%d", 10-count);
3946                         mdelay(200);
3947                         goto retry;
3948                 }
3949                 printk(" ignoring it.\n");
3950                 unlock = 0;
3951         } else {
3952                 if (count != 10)
3953                         printk(KERN_CONT " locked it.\n");
3954         }
3955
3956         do_each_thread(g, p) {
3957                 /*
3958                  * It's not reliable to print a task's held locks
3959                  * if it's not sleeping (or if it's not the current
3960                  * task):
3961                  */
3962                 if (p->state == TASK_RUNNING && p != current)
3963                         continue;
3964                 if (p->lockdep_depth)
3965                         lockdep_print_held_locks(p);
3966                 if (!unlock)
3967                         if (read_trylock(&tasklist_lock))
3968                                 unlock = 1;
3969         } while_each_thread(g, p);
3970
3971         printk("\n");
3972         printk("=============================================\n\n");
3973
3974         if (unlock)
3975                 read_unlock(&tasklist_lock);
3976 }
3977 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3978
3979 /*
3980  * Careful: only use this function if you are sure that
3981  * the task cannot run in parallel!
3982  */
3983 void debug_show_held_locks(struct task_struct *task)
3984 {
3985         if (unlikely(!debug_locks)) {
3986                 printk("INFO: lockdep is turned off.\n");
3987                 return;
3988         }
3989         lockdep_print_held_locks(task);
3990 }
3991 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3992
3993 void lockdep_sys_exit(void)
3994 {
3995         struct task_struct *curr = current;
3996
3997         if (unlikely(curr->lockdep_depth)) {
3998                 if (!debug_locks_off())
3999                         return;
4000                 printk("\n================================================\n");
4001                 printk(  "[ BUG: lock held when returning to user space! ]\n");
4002                 printk(  "------------------------------------------------\n");
4003                 printk("%s/%d is leaving the kernel with locks still held!\n",
4004                                 curr->comm, curr->pid);
4005                 lockdep_print_held_locks(curr);
4006         }
4007 }
4008
4009 void lockdep_rcu_dereference(const char *file, const int line)
4010 {
4011         struct task_struct *curr = current;
4012
4013 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4014         if (!debug_locks_off())
4015                 return;
4016 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4017         /* Note: the following can be executed concurrently, so be careful. */
4018         printk("\n===================================================\n");
4019         printk(  "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
4020         printk(  "---------------------------------------------------\n");
4021         printk("%s:%d invoked rcu_dereference_check() without protection!\n",
4022                         file, line);
4023         printk("\nother info that might help us debug this:\n\n");
4024         printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
4025         lockdep_print_held_locks(curr);
4026         printk("\nstack backtrace:\n");
4027         dump_stack();
4028 }
4029 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);