lockdep: Print a nicer description for simple irq lock inversions
[linux-3.10.git] / kernel / lockdep.c
1 /*
2  * kernel/lockdep.c
3  *
4  * Runtime locking correctness validator
5  *
6  * Started by Ingo Molnar:
7  *
8  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
10  *
11  * this code maps all the lock dependencies as they occur in a live kernel
12  * and will warn about the following classes of locking bugs:
13  *
14  * - lock inversion scenarios
15  * - circular lock dependencies
16  * - hardirq/softirq safe/unsafe locking bugs
17  *
18  * Bugs are reported even if the current locking scenario does not cause
19  * any deadlock at this point.
20  *
21  * I.e. if anytime in the past two locks were taken in a different order,
22  * even if it happened for another task, even if those were different
23  * locks (but of the same class as this lock), this code will detect it.
24  *
25  * Thanks to Arjan van de Ven for coming up with the initial idea of
26  * mapping lock dependencies runtime.
27  */
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46 #include <linux/gfp.h>
47
48 #include <asm/sections.h>
49
50 #include "lockdep_internals.h"
51
52 #define CREATE_TRACE_POINTS
53 #include <trace/events/lock.h>
54
55 #ifdef CONFIG_PROVE_LOCKING
56 int prove_locking = 1;
57 module_param(prove_locking, int, 0644);
58 #else
59 #define prove_locking 0
60 #endif
61
62 #ifdef CONFIG_LOCK_STAT
63 int lock_stat = 1;
64 module_param(lock_stat, int, 0644);
65 #else
66 #define lock_stat 0
67 #endif
68
69 /*
70  * lockdep_lock: protects the lockdep graph, the hashes and the
71  *               class/list/hash allocators.
72  *
73  * This is one of the rare exceptions where it's justified
74  * to use a raw spinlock - we really dont want the spinlock
75  * code to recurse back into the lockdep code...
76  */
77 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
78
79 static int graph_lock(void)
80 {
81         arch_spin_lock(&lockdep_lock);
82         /*
83          * Make sure that if another CPU detected a bug while
84          * walking the graph we dont change it (while the other
85          * CPU is busy printing out stuff with the graph lock
86          * dropped already)
87          */
88         if (!debug_locks) {
89                 arch_spin_unlock(&lockdep_lock);
90                 return 0;
91         }
92         /* prevent any recursions within lockdep from causing deadlocks */
93         current->lockdep_recursion++;
94         return 1;
95 }
96
97 static inline int graph_unlock(void)
98 {
99         if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
100                 return DEBUG_LOCKS_WARN_ON(1);
101
102         current->lockdep_recursion--;
103         arch_spin_unlock(&lockdep_lock);
104         return 0;
105 }
106
107 /*
108  * Turn lock debugging off and return with 0 if it was off already,
109  * and also release the graph lock:
110  */
111 static inline int debug_locks_off_graph_unlock(void)
112 {
113         int ret = debug_locks_off();
114
115         arch_spin_unlock(&lockdep_lock);
116
117         return ret;
118 }
119
120 static int lockdep_initialized;
121
122 unsigned long nr_list_entries;
123 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
124
125 /*
126  * All data structures here are protected by the global debug_lock.
127  *
128  * Mutex key structs only get allocated, once during bootup, and never
129  * get freed - this significantly simplifies the debugging code.
130  */
131 unsigned long nr_lock_classes;
132 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
133
134 static inline struct lock_class *hlock_class(struct held_lock *hlock)
135 {
136         if (!hlock->class_idx) {
137                 DEBUG_LOCKS_WARN_ON(1);
138                 return NULL;
139         }
140         return lock_classes + hlock->class_idx - 1;
141 }
142
143 #ifdef CONFIG_LOCK_STAT
144 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
145                       cpu_lock_stats);
146
147 static inline u64 lockstat_clock(void)
148 {
149         return local_clock();
150 }
151
152 static int lock_point(unsigned long points[], unsigned long ip)
153 {
154         int i;
155
156         for (i = 0; i < LOCKSTAT_POINTS; i++) {
157                 if (points[i] == 0) {
158                         points[i] = ip;
159                         break;
160                 }
161                 if (points[i] == ip)
162                         break;
163         }
164
165         return i;
166 }
167
168 static void lock_time_inc(struct lock_time *lt, u64 time)
169 {
170         if (time > lt->max)
171                 lt->max = time;
172
173         if (time < lt->min || !lt->nr)
174                 lt->min = time;
175
176         lt->total += time;
177         lt->nr++;
178 }
179
180 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
181 {
182         if (!src->nr)
183                 return;
184
185         if (src->max > dst->max)
186                 dst->max = src->max;
187
188         if (src->min < dst->min || !dst->nr)
189                 dst->min = src->min;
190
191         dst->total += src->total;
192         dst->nr += src->nr;
193 }
194
195 struct lock_class_stats lock_stats(struct lock_class *class)
196 {
197         struct lock_class_stats stats;
198         int cpu, i;
199
200         memset(&stats, 0, sizeof(struct lock_class_stats));
201         for_each_possible_cpu(cpu) {
202                 struct lock_class_stats *pcs =
203                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
204
205                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
206                         stats.contention_point[i] += pcs->contention_point[i];
207
208                 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
209                         stats.contending_point[i] += pcs->contending_point[i];
210
211                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
212                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
213
214                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
215                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
216
217                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
218                         stats.bounces[i] += pcs->bounces[i];
219         }
220
221         return stats;
222 }
223
224 void clear_lock_stats(struct lock_class *class)
225 {
226         int cpu;
227
228         for_each_possible_cpu(cpu) {
229                 struct lock_class_stats *cpu_stats =
230                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
231
232                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
233         }
234         memset(class->contention_point, 0, sizeof(class->contention_point));
235         memset(class->contending_point, 0, sizeof(class->contending_point));
236 }
237
238 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
239 {
240         return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
241 }
242
243 static void put_lock_stats(struct lock_class_stats *stats)
244 {
245         put_cpu_var(cpu_lock_stats);
246 }
247
248 static void lock_release_holdtime(struct held_lock *hlock)
249 {
250         struct lock_class_stats *stats;
251         u64 holdtime;
252
253         if (!lock_stat)
254                 return;
255
256         holdtime = lockstat_clock() - hlock->holdtime_stamp;
257
258         stats = get_lock_stats(hlock_class(hlock));
259         if (hlock->read)
260                 lock_time_inc(&stats->read_holdtime, holdtime);
261         else
262                 lock_time_inc(&stats->write_holdtime, holdtime);
263         put_lock_stats(stats);
264 }
265 #else
266 static inline void lock_release_holdtime(struct held_lock *hlock)
267 {
268 }
269 #endif
270
271 /*
272  * We keep a global list of all lock classes. The list only grows,
273  * never shrinks. The list is only accessed with the lockdep
274  * spinlock lock held.
275  */
276 LIST_HEAD(all_lock_classes);
277
278 /*
279  * The lockdep classes are in a hash-table as well, for fast lookup:
280  */
281 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
282 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
283 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
284 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
285
286 static struct list_head classhash_table[CLASSHASH_SIZE];
287
288 /*
289  * We put the lock dependency chains into a hash-table as well, to cache
290  * their existence:
291  */
292 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
293 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
294 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
295 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
296
297 static struct list_head chainhash_table[CHAINHASH_SIZE];
298
299 /*
300  * The hash key of the lock dependency chains is a hash itself too:
301  * it's a hash of all locks taken up to that lock, including that lock.
302  * It's a 64-bit hash, because it's important for the keys to be
303  * unique.
304  */
305 #define iterate_chain_key(key1, key2) \
306         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
307         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
308         (key2))
309
310 void lockdep_off(void)
311 {
312         current->lockdep_recursion++;
313 }
314 EXPORT_SYMBOL(lockdep_off);
315
316 void lockdep_on(void)
317 {
318         current->lockdep_recursion--;
319 }
320 EXPORT_SYMBOL(lockdep_on);
321
322 /*
323  * Debugging switches:
324  */
325
326 #define VERBOSE                 0
327 #define VERY_VERBOSE            0
328
329 #if VERBOSE
330 # define HARDIRQ_VERBOSE        1
331 # define SOFTIRQ_VERBOSE        1
332 # define RECLAIM_VERBOSE        1
333 #else
334 # define HARDIRQ_VERBOSE        0
335 # define SOFTIRQ_VERBOSE        0
336 # define RECLAIM_VERBOSE        0
337 #endif
338
339 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
340 /*
341  * Quick filtering for interesting events:
342  */
343 static int class_filter(struct lock_class *class)
344 {
345 #if 0
346         /* Example */
347         if (class->name_version == 1 &&
348                         !strcmp(class->name, "lockname"))
349                 return 1;
350         if (class->name_version == 1 &&
351                         !strcmp(class->name, "&struct->lockfield"))
352                 return 1;
353 #endif
354         /* Filter everything else. 1 would be to allow everything else */
355         return 0;
356 }
357 #endif
358
359 static int verbose(struct lock_class *class)
360 {
361 #if VERBOSE
362         return class_filter(class);
363 #endif
364         return 0;
365 }
366
367 /*
368  * Stack-trace: tightly packed array of stack backtrace
369  * addresses. Protected by the graph_lock.
370  */
371 unsigned long nr_stack_trace_entries;
372 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
373
374 static int save_trace(struct stack_trace *trace)
375 {
376         trace->nr_entries = 0;
377         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
378         trace->entries = stack_trace + nr_stack_trace_entries;
379
380         trace->skip = 3;
381
382         save_stack_trace(trace);
383
384         /*
385          * Some daft arches put -1 at the end to indicate its a full trace.
386          *
387          * <rant> this is buggy anyway, since it takes a whole extra entry so a
388          * complete trace that maxes out the entries provided will be reported
389          * as incomplete, friggin useless </rant>
390          */
391         if (trace->nr_entries != 0 &&
392             trace->entries[trace->nr_entries-1] == ULONG_MAX)
393                 trace->nr_entries--;
394
395         trace->max_entries = trace->nr_entries;
396
397         nr_stack_trace_entries += trace->nr_entries;
398
399         if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
400                 if (!debug_locks_off_graph_unlock())
401                         return 0;
402
403                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
404                 printk("turning off the locking correctness validator.\n");
405                 dump_stack();
406
407                 return 0;
408         }
409
410         return 1;
411 }
412
413 unsigned int nr_hardirq_chains;
414 unsigned int nr_softirq_chains;
415 unsigned int nr_process_chains;
416 unsigned int max_lockdep_depth;
417
418 #ifdef CONFIG_DEBUG_LOCKDEP
419 /*
420  * We cannot printk in early bootup code. Not even early_printk()
421  * might work. So we mark any initialization errors and printk
422  * about it later on, in lockdep_info().
423  */
424 static int lockdep_init_error;
425 static unsigned long lockdep_init_trace_data[20];
426 static struct stack_trace lockdep_init_trace = {
427         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
428         .entries = lockdep_init_trace_data,
429 };
430
431 /*
432  * Various lockdep statistics:
433  */
434 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
435 #endif
436
437 /*
438  * Locking printouts:
439  */
440
441 #define __USAGE(__STATE)                                                \
442         [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
443         [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
444         [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
445         [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
446
447 static const char *usage_str[] =
448 {
449 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
450 #include "lockdep_states.h"
451 #undef LOCKDEP_STATE
452         [LOCK_USED] = "INITIAL USE",
453 };
454
455 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
456 {
457         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
458 }
459
460 static inline unsigned long lock_flag(enum lock_usage_bit bit)
461 {
462         return 1UL << bit;
463 }
464
465 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
466 {
467         char c = '.';
468
469         if (class->usage_mask & lock_flag(bit + 2))
470                 c = '+';
471         if (class->usage_mask & lock_flag(bit)) {
472                 c = '-';
473                 if (class->usage_mask & lock_flag(bit + 2))
474                         c = '?';
475         }
476
477         return c;
478 }
479
480 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
481 {
482         int i = 0;
483
484 #define LOCKDEP_STATE(__STATE)                                          \
485         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
486         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
487 #include "lockdep_states.h"
488 #undef LOCKDEP_STATE
489
490         usage[i] = '\0';
491 }
492
493 static int __print_lock_name(struct lock_class *class)
494 {
495         char str[KSYM_NAME_LEN];
496         const char *name;
497
498         name = class->name;
499         if (!name)
500                 name = __get_key_name(class->key, str);
501
502         return printk("%s", name);
503 }
504
505 static void print_lock_name(struct lock_class *class)
506 {
507         char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
508         const char *name;
509
510         get_usage_chars(class, usage);
511
512         name = class->name;
513         if (!name) {
514                 name = __get_key_name(class->key, str);
515                 printk(" (%s", name);
516         } else {
517                 printk(" (%s", name);
518                 if (class->name_version > 1)
519                         printk("#%d", class->name_version);
520                 if (class->subclass)
521                         printk("/%d", class->subclass);
522         }
523         printk("){%s}", usage);
524 }
525
526 static void print_lockdep_cache(struct lockdep_map *lock)
527 {
528         const char *name;
529         char str[KSYM_NAME_LEN];
530
531         name = lock->name;
532         if (!name)
533                 name = __get_key_name(lock->key->subkeys, str);
534
535         printk("%s", name);
536 }
537
538 static void print_lock(struct held_lock *hlock)
539 {
540         print_lock_name(hlock_class(hlock));
541         printk(", at: ");
542         print_ip_sym(hlock->acquire_ip);
543 }
544
545 static void lockdep_print_held_locks(struct task_struct *curr)
546 {
547         int i, depth = curr->lockdep_depth;
548
549         if (!depth) {
550                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
551                 return;
552         }
553         printk("%d lock%s held by %s/%d:\n",
554                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
555
556         for (i = 0; i < depth; i++) {
557                 printk(" #%d: ", i);
558                 print_lock(curr->held_locks + i);
559         }
560 }
561
562 static void print_kernel_version(void)
563 {
564         printk("%s %.*s\n", init_utsname()->release,
565                 (int)strcspn(init_utsname()->version, " "),
566                 init_utsname()->version);
567 }
568
569 static int very_verbose(struct lock_class *class)
570 {
571 #if VERY_VERBOSE
572         return class_filter(class);
573 #endif
574         return 0;
575 }
576
577 /*
578  * Is this the address of a static object:
579  */
580 static int static_obj(void *obj)
581 {
582         unsigned long start = (unsigned long) &_stext,
583                       end   = (unsigned long) &_end,
584                       addr  = (unsigned long) obj;
585
586         /*
587          * static variable?
588          */
589         if ((addr >= start) && (addr < end))
590                 return 1;
591
592         if (arch_is_kernel_data(addr))
593                 return 1;
594
595         /*
596          * in-kernel percpu var?
597          */
598         if (is_kernel_percpu_address(addr))
599                 return 1;
600
601         /*
602          * module static or percpu var?
603          */
604         return is_module_address(addr) || is_module_percpu_address(addr);
605 }
606
607 /*
608  * To make lock name printouts unique, we calculate a unique
609  * class->name_version generation counter:
610  */
611 static int count_matching_names(struct lock_class *new_class)
612 {
613         struct lock_class *class;
614         int count = 0;
615
616         if (!new_class->name)
617                 return 0;
618
619         list_for_each_entry(class, &all_lock_classes, lock_entry) {
620                 if (new_class->key - new_class->subclass == class->key)
621                         return class->name_version;
622                 if (class->name && !strcmp(class->name, new_class->name))
623                         count = max(count, class->name_version);
624         }
625
626         return count + 1;
627 }
628
629 /*
630  * Register a lock's class in the hash-table, if the class is not present
631  * yet. Otherwise we look it up. We cache the result in the lock object
632  * itself, so actual lookup of the hash should be once per lock object.
633  */
634 static inline struct lock_class *
635 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
636 {
637         struct lockdep_subclass_key *key;
638         struct list_head *hash_head;
639         struct lock_class *class;
640
641 #ifdef CONFIG_DEBUG_LOCKDEP
642         /*
643          * If the architecture calls into lockdep before initializing
644          * the hashes then we'll warn about it later. (we cannot printk
645          * right now)
646          */
647         if (unlikely(!lockdep_initialized)) {
648                 lockdep_init();
649                 lockdep_init_error = 1;
650                 save_stack_trace(&lockdep_init_trace);
651         }
652 #endif
653
654         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
655                 debug_locks_off();
656                 printk(KERN_ERR
657                         "BUG: looking up invalid subclass: %u\n", subclass);
658                 printk(KERN_ERR
659                         "turning off the locking correctness validator.\n");
660                 dump_stack();
661                 return NULL;
662         }
663
664         /*
665          * Static locks do not have their class-keys yet - for them the key
666          * is the lock object itself:
667          */
668         if (unlikely(!lock->key))
669                 lock->key = (void *)lock;
670
671         /*
672          * NOTE: the class-key must be unique. For dynamic locks, a static
673          * lock_class_key variable is passed in through the mutex_init()
674          * (or spin_lock_init()) call - which acts as the key. For static
675          * locks we use the lock object itself as the key.
676          */
677         BUILD_BUG_ON(sizeof(struct lock_class_key) >
678                         sizeof(struct lockdep_map));
679
680         key = lock->key->subkeys + subclass;
681
682         hash_head = classhashentry(key);
683
684         /*
685          * We can walk the hash lockfree, because the hash only
686          * grows, and we are careful when adding entries to the end:
687          */
688         list_for_each_entry(class, hash_head, hash_entry) {
689                 if (class->key == key) {
690                         WARN_ON_ONCE(class->name != lock->name);
691                         return class;
692                 }
693         }
694
695         return NULL;
696 }
697
698 /*
699  * Register a lock's class in the hash-table, if the class is not present
700  * yet. Otherwise we look it up. We cache the result in the lock object
701  * itself, so actual lookup of the hash should be once per lock object.
702  */
703 static inline struct lock_class *
704 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
705 {
706         struct lockdep_subclass_key *key;
707         struct list_head *hash_head;
708         struct lock_class *class;
709         unsigned long flags;
710
711         class = look_up_lock_class(lock, subclass);
712         if (likely(class))
713                 return class;
714
715         /*
716          * Debug-check: all keys must be persistent!
717          */
718         if (!static_obj(lock->key)) {
719                 debug_locks_off();
720                 printk("INFO: trying to register non-static key.\n");
721                 printk("the code is fine but needs lockdep annotation.\n");
722                 printk("turning off the locking correctness validator.\n");
723                 dump_stack();
724
725                 return NULL;
726         }
727
728         key = lock->key->subkeys + subclass;
729         hash_head = classhashentry(key);
730
731         raw_local_irq_save(flags);
732         if (!graph_lock()) {
733                 raw_local_irq_restore(flags);
734                 return NULL;
735         }
736         /*
737          * We have to do the hash-walk again, to avoid races
738          * with another CPU:
739          */
740         list_for_each_entry(class, hash_head, hash_entry)
741                 if (class->key == key)
742                         goto out_unlock_set;
743         /*
744          * Allocate a new key from the static array, and add it to
745          * the hash:
746          */
747         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
748                 if (!debug_locks_off_graph_unlock()) {
749                         raw_local_irq_restore(flags);
750                         return NULL;
751                 }
752                 raw_local_irq_restore(flags);
753
754                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
755                 printk("turning off the locking correctness validator.\n");
756                 dump_stack();
757                 return NULL;
758         }
759         class = lock_classes + nr_lock_classes++;
760         debug_atomic_inc(nr_unused_locks);
761         class->key = key;
762         class->name = lock->name;
763         class->subclass = subclass;
764         INIT_LIST_HEAD(&class->lock_entry);
765         INIT_LIST_HEAD(&class->locks_before);
766         INIT_LIST_HEAD(&class->locks_after);
767         class->name_version = count_matching_names(class);
768         /*
769          * We use RCU's safe list-add method to make
770          * parallel walking of the hash-list safe:
771          */
772         list_add_tail_rcu(&class->hash_entry, hash_head);
773         /*
774          * Add it to the global list of classes:
775          */
776         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
777
778         if (verbose(class)) {
779                 graph_unlock();
780                 raw_local_irq_restore(flags);
781
782                 printk("\nnew class %p: %s", class->key, class->name);
783                 if (class->name_version > 1)
784                         printk("#%d", class->name_version);
785                 printk("\n");
786                 dump_stack();
787
788                 raw_local_irq_save(flags);
789                 if (!graph_lock()) {
790                         raw_local_irq_restore(flags);
791                         return NULL;
792                 }
793         }
794 out_unlock_set:
795         graph_unlock();
796         raw_local_irq_restore(flags);
797
798         if (!subclass || force)
799                 lock->class_cache[0] = class;
800         else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
801                 lock->class_cache[subclass] = class;
802
803         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
804                 return NULL;
805
806         return class;
807 }
808
809 #ifdef CONFIG_PROVE_LOCKING
810 /*
811  * Allocate a lockdep entry. (assumes the graph_lock held, returns
812  * with NULL on failure)
813  */
814 static struct lock_list *alloc_list_entry(void)
815 {
816         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
817                 if (!debug_locks_off_graph_unlock())
818                         return NULL;
819
820                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
821                 printk("turning off the locking correctness validator.\n");
822                 dump_stack();
823                 return NULL;
824         }
825         return list_entries + nr_list_entries++;
826 }
827
828 /*
829  * Add a new dependency to the head of the list:
830  */
831 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
832                             struct list_head *head, unsigned long ip,
833                             int distance, struct stack_trace *trace)
834 {
835         struct lock_list *entry;
836         /*
837          * Lock not present yet - get a new dependency struct and
838          * add it to the list:
839          */
840         entry = alloc_list_entry();
841         if (!entry)
842                 return 0;
843
844         entry->class = this;
845         entry->distance = distance;
846         entry->trace = *trace;
847         /*
848          * Since we never remove from the dependency list, the list can
849          * be walked lockless by other CPUs, it's only allocation
850          * that must be protected by the spinlock. But this also means
851          * we must make new entries visible only once writes to the
852          * entry become visible - hence the RCU op:
853          */
854         list_add_tail_rcu(&entry->entry, head);
855
856         return 1;
857 }
858
859 /*
860  * For good efficiency of modular, we use power of 2
861  */
862 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
863 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
864
865 /*
866  * The circular_queue and helpers is used to implement the
867  * breadth-first search(BFS)algorithem, by which we can build
868  * the shortest path from the next lock to be acquired to the
869  * previous held lock if there is a circular between them.
870  */
871 struct circular_queue {
872         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
873         unsigned int  front, rear;
874 };
875
876 static struct circular_queue lock_cq;
877
878 unsigned int max_bfs_queue_depth;
879
880 static unsigned int lockdep_dependency_gen_id;
881
882 static inline void __cq_init(struct circular_queue *cq)
883 {
884         cq->front = cq->rear = 0;
885         lockdep_dependency_gen_id++;
886 }
887
888 static inline int __cq_empty(struct circular_queue *cq)
889 {
890         return (cq->front == cq->rear);
891 }
892
893 static inline int __cq_full(struct circular_queue *cq)
894 {
895         return ((cq->rear + 1) & CQ_MASK) == cq->front;
896 }
897
898 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
899 {
900         if (__cq_full(cq))
901                 return -1;
902
903         cq->element[cq->rear] = elem;
904         cq->rear = (cq->rear + 1) & CQ_MASK;
905         return 0;
906 }
907
908 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
909 {
910         if (__cq_empty(cq))
911                 return -1;
912
913         *elem = cq->element[cq->front];
914         cq->front = (cq->front + 1) & CQ_MASK;
915         return 0;
916 }
917
918 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
919 {
920         return (cq->rear - cq->front) & CQ_MASK;
921 }
922
923 static inline void mark_lock_accessed(struct lock_list *lock,
924                                         struct lock_list *parent)
925 {
926         unsigned long nr;
927
928         nr = lock - list_entries;
929         WARN_ON(nr >= nr_list_entries);
930         lock->parent = parent;
931         lock->class->dep_gen_id = lockdep_dependency_gen_id;
932 }
933
934 static inline unsigned long lock_accessed(struct lock_list *lock)
935 {
936         unsigned long nr;
937
938         nr = lock - list_entries;
939         WARN_ON(nr >= nr_list_entries);
940         return lock->class->dep_gen_id == lockdep_dependency_gen_id;
941 }
942
943 static inline struct lock_list *get_lock_parent(struct lock_list *child)
944 {
945         return child->parent;
946 }
947
948 static inline int get_lock_depth(struct lock_list *child)
949 {
950         int depth = 0;
951         struct lock_list *parent;
952
953         while ((parent = get_lock_parent(child))) {
954                 child = parent;
955                 depth++;
956         }
957         return depth;
958 }
959
960 static int __bfs(struct lock_list *source_entry,
961                  void *data,
962                  int (*match)(struct lock_list *entry, void *data),
963                  struct lock_list **target_entry,
964                  int forward)
965 {
966         struct lock_list *entry;
967         struct list_head *head;
968         struct circular_queue *cq = &lock_cq;
969         int ret = 1;
970
971         if (match(source_entry, data)) {
972                 *target_entry = source_entry;
973                 ret = 0;
974                 goto exit;
975         }
976
977         if (forward)
978                 head = &source_entry->class->locks_after;
979         else
980                 head = &source_entry->class->locks_before;
981
982         if (list_empty(head))
983                 goto exit;
984
985         __cq_init(cq);
986         __cq_enqueue(cq, (unsigned long)source_entry);
987
988         while (!__cq_empty(cq)) {
989                 struct lock_list *lock;
990
991                 __cq_dequeue(cq, (unsigned long *)&lock);
992
993                 if (!lock->class) {
994                         ret = -2;
995                         goto exit;
996                 }
997
998                 if (forward)
999                         head = &lock->class->locks_after;
1000                 else
1001                         head = &lock->class->locks_before;
1002
1003                 list_for_each_entry(entry, head, entry) {
1004                         if (!lock_accessed(entry)) {
1005                                 unsigned int cq_depth;
1006                                 mark_lock_accessed(entry, lock);
1007                                 if (match(entry, data)) {
1008                                         *target_entry = entry;
1009                                         ret = 0;
1010                                         goto exit;
1011                                 }
1012
1013                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
1014                                         ret = -1;
1015                                         goto exit;
1016                                 }
1017                                 cq_depth = __cq_get_elem_count(cq);
1018                                 if (max_bfs_queue_depth < cq_depth)
1019                                         max_bfs_queue_depth = cq_depth;
1020                         }
1021                 }
1022         }
1023 exit:
1024         return ret;
1025 }
1026
1027 static inline int __bfs_forwards(struct lock_list *src_entry,
1028                         void *data,
1029                         int (*match)(struct lock_list *entry, void *data),
1030                         struct lock_list **target_entry)
1031 {
1032         return __bfs(src_entry, data, match, target_entry, 1);
1033
1034 }
1035
1036 static inline int __bfs_backwards(struct lock_list *src_entry,
1037                         void *data,
1038                         int (*match)(struct lock_list *entry, void *data),
1039                         struct lock_list **target_entry)
1040 {
1041         return __bfs(src_entry, data, match, target_entry, 0);
1042
1043 }
1044
1045 /*
1046  * Recursive, forwards-direction lock-dependency checking, used for
1047  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1048  * checking.
1049  */
1050
1051 /*
1052  * Print a dependency chain entry (this is only done when a deadlock
1053  * has been detected):
1054  */
1055 static noinline int
1056 print_circular_bug_entry(struct lock_list *target, int depth)
1057 {
1058         if (debug_locks_silent)
1059                 return 0;
1060         printk("\n-> #%u", depth);
1061         print_lock_name(target->class);
1062         printk(":\n");
1063         print_stack_trace(&target->trace, 6);
1064
1065         return 0;
1066 }
1067
1068 static void
1069 print_circular_lock_scenario(struct held_lock *src,
1070                              struct held_lock *tgt,
1071                              struct lock_list *prt)
1072 {
1073         struct lock_class *source = hlock_class(src);
1074         struct lock_class *target = hlock_class(tgt);
1075         struct lock_class *parent = prt->class;
1076
1077         /*
1078          * A direct locking problem where unsafe_class lock is taken
1079          * directly by safe_class lock, then all we need to show
1080          * is the deadlock scenario, as it is obvious that the
1081          * unsafe lock is taken under the safe lock.
1082          *
1083          * But if there is a chain instead, where the safe lock takes
1084          * an intermediate lock (middle_class) where this lock is
1085          * not the same as the safe lock, then the lock chain is
1086          * used to describe the problem. Otherwise we would need
1087          * to show a different CPU case for each link in the chain
1088          * from the safe_class lock to the unsafe_class lock.
1089          */
1090         if (parent != source) {
1091                 printk("Chain exists of:\n  ");
1092                 __print_lock_name(source);
1093                 printk(" --> ");
1094                 __print_lock_name(parent);
1095                 printk(" --> ");
1096                 __print_lock_name(target);
1097                 printk("\n\n");
1098         }
1099
1100         printk(" Possible unsafe locking scenario:\n\n");
1101         printk("       CPU0                    CPU1\n");
1102         printk("       ----                    ----\n");
1103         printk("  lock(");
1104         __print_lock_name(target);
1105         printk(");\n");
1106         printk("                               lock(");
1107         __print_lock_name(parent);
1108         printk(");\n");
1109         printk("                               lock(");
1110         __print_lock_name(target);
1111         printk(");\n");
1112         printk("  lock(");
1113         __print_lock_name(source);
1114         printk(");\n");
1115         printk("\n *** DEADLOCK ***\n\n");
1116 }
1117
1118 /*
1119  * When a circular dependency is detected, print the
1120  * header first:
1121  */
1122 static noinline int
1123 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1124                         struct held_lock *check_src,
1125                         struct held_lock *check_tgt)
1126 {
1127         struct task_struct *curr = current;
1128
1129         if (debug_locks_silent)
1130                 return 0;
1131
1132         printk("\n=======================================================\n");
1133         printk(  "[ INFO: possible circular locking dependency detected ]\n");
1134         print_kernel_version();
1135         printk(  "-------------------------------------------------------\n");
1136         printk("%s/%d is trying to acquire lock:\n",
1137                 curr->comm, task_pid_nr(curr));
1138         print_lock(check_src);
1139         printk("\nbut task is already holding lock:\n");
1140         print_lock(check_tgt);
1141         printk("\nwhich lock already depends on the new lock.\n\n");
1142         printk("\nthe existing dependency chain (in reverse order) is:\n");
1143
1144         print_circular_bug_entry(entry, depth);
1145
1146         return 0;
1147 }
1148
1149 static inline int class_equal(struct lock_list *entry, void *data)
1150 {
1151         return entry->class == data;
1152 }
1153
1154 static noinline int print_circular_bug(struct lock_list *this,
1155                                 struct lock_list *target,
1156                                 struct held_lock *check_src,
1157                                 struct held_lock *check_tgt)
1158 {
1159         struct task_struct *curr = current;
1160         struct lock_list *parent;
1161         struct lock_list *first_parent;
1162         int depth;
1163
1164         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1165                 return 0;
1166
1167         if (!save_trace(&this->trace))
1168                 return 0;
1169
1170         depth = get_lock_depth(target);
1171
1172         print_circular_bug_header(target, depth, check_src, check_tgt);
1173
1174         parent = get_lock_parent(target);
1175         first_parent = parent;
1176
1177         while (parent) {
1178                 print_circular_bug_entry(parent, --depth);
1179                 parent = get_lock_parent(parent);
1180         }
1181
1182         printk("\nother info that might help us debug this:\n\n");
1183         print_circular_lock_scenario(check_src, check_tgt,
1184                                      first_parent);
1185
1186         lockdep_print_held_locks(curr);
1187
1188         printk("\nstack backtrace:\n");
1189         dump_stack();
1190
1191         return 0;
1192 }
1193
1194 static noinline int print_bfs_bug(int ret)
1195 {
1196         if (!debug_locks_off_graph_unlock())
1197                 return 0;
1198
1199         WARN(1, "lockdep bfs error:%d\n", ret);
1200
1201         return 0;
1202 }
1203
1204 static int noop_count(struct lock_list *entry, void *data)
1205 {
1206         (*(unsigned long *)data)++;
1207         return 0;
1208 }
1209
1210 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1211 {
1212         unsigned long  count = 0;
1213         struct lock_list *uninitialized_var(target_entry);
1214
1215         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1216
1217         return count;
1218 }
1219 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1220 {
1221         unsigned long ret, flags;
1222         struct lock_list this;
1223
1224         this.parent = NULL;
1225         this.class = class;
1226
1227         local_irq_save(flags);
1228         arch_spin_lock(&lockdep_lock);
1229         ret = __lockdep_count_forward_deps(&this);
1230         arch_spin_unlock(&lockdep_lock);
1231         local_irq_restore(flags);
1232
1233         return ret;
1234 }
1235
1236 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1237 {
1238         unsigned long  count = 0;
1239         struct lock_list *uninitialized_var(target_entry);
1240
1241         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1242
1243         return count;
1244 }
1245
1246 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1247 {
1248         unsigned long ret, flags;
1249         struct lock_list this;
1250
1251         this.parent = NULL;
1252         this.class = class;
1253
1254         local_irq_save(flags);
1255         arch_spin_lock(&lockdep_lock);
1256         ret = __lockdep_count_backward_deps(&this);
1257         arch_spin_unlock(&lockdep_lock);
1258         local_irq_restore(flags);
1259
1260         return ret;
1261 }
1262
1263 /*
1264  * Prove that the dependency graph starting at <entry> can not
1265  * lead to <target>. Print an error and return 0 if it does.
1266  */
1267 static noinline int
1268 check_noncircular(struct lock_list *root, struct lock_class *target,
1269                 struct lock_list **target_entry)
1270 {
1271         int result;
1272
1273         debug_atomic_inc(nr_cyclic_checks);
1274
1275         result = __bfs_forwards(root, target, class_equal, target_entry);
1276
1277         return result;
1278 }
1279
1280 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1281 /*
1282  * Forwards and backwards subgraph searching, for the purposes of
1283  * proving that two subgraphs can be connected by a new dependency
1284  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1285  */
1286
1287 static inline int usage_match(struct lock_list *entry, void *bit)
1288 {
1289         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1290 }
1291
1292
1293
1294 /*
1295  * Find a node in the forwards-direction dependency sub-graph starting
1296  * at @root->class that matches @bit.
1297  *
1298  * Return 0 if such a node exists in the subgraph, and put that node
1299  * into *@target_entry.
1300  *
1301  * Return 1 otherwise and keep *@target_entry unchanged.
1302  * Return <0 on error.
1303  */
1304 static int
1305 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1306                         struct lock_list **target_entry)
1307 {
1308         int result;
1309
1310         debug_atomic_inc(nr_find_usage_forwards_checks);
1311
1312         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1313
1314         return result;
1315 }
1316
1317 /*
1318  * Find a node in the backwards-direction dependency sub-graph starting
1319  * at @root->class that matches @bit.
1320  *
1321  * Return 0 if such a node exists in the subgraph, and put that node
1322  * into *@target_entry.
1323  *
1324  * Return 1 otherwise and keep *@target_entry unchanged.
1325  * Return <0 on error.
1326  */
1327 static int
1328 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1329                         struct lock_list **target_entry)
1330 {
1331         int result;
1332
1333         debug_atomic_inc(nr_find_usage_backwards_checks);
1334
1335         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1336
1337         return result;
1338 }
1339
1340 static void print_lock_class_header(struct lock_class *class, int depth)
1341 {
1342         int bit;
1343
1344         printk("%*s->", depth, "");
1345         print_lock_name(class);
1346         printk(" ops: %lu", class->ops);
1347         printk(" {\n");
1348
1349         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1350                 if (class->usage_mask & (1 << bit)) {
1351                         int len = depth;
1352
1353                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1354                         len += printk(" at:\n");
1355                         print_stack_trace(class->usage_traces + bit, len);
1356                 }
1357         }
1358         printk("%*s }\n", depth, "");
1359
1360         printk("%*s ... key      at: ",depth,"");
1361         print_ip_sym((unsigned long)class->key);
1362 }
1363
1364 /*
1365  * printk the shortest lock dependencies from @start to @end in reverse order:
1366  */
1367 static void __used
1368 print_shortest_lock_dependencies(struct lock_list *leaf,
1369                                 struct lock_list *root)
1370 {
1371         struct lock_list *entry = leaf;
1372         int depth;
1373
1374         /*compute depth from generated tree by BFS*/
1375         depth = get_lock_depth(leaf);
1376
1377         do {
1378                 print_lock_class_header(entry->class, depth);
1379                 printk("%*s ... acquired at:\n", depth, "");
1380                 print_stack_trace(&entry->trace, 2);
1381                 printk("\n");
1382
1383                 if (depth == 0 && (entry != root)) {
1384                         printk("lockdep:%s bad path found in chain graph\n", __func__);
1385                         break;
1386                 }
1387
1388                 entry = get_lock_parent(entry);
1389                 depth--;
1390         } while (entry && (depth >= 0));
1391
1392         return;
1393 }
1394
1395 static void
1396 print_irq_lock_scenario(struct lock_list *safe_entry,
1397                         struct lock_list *unsafe_entry,
1398                         struct lock_class *prev_class,
1399                         struct lock_class *next_class)
1400 {
1401         struct lock_class *safe_class = safe_entry->class;
1402         struct lock_class *unsafe_class = unsafe_entry->class;
1403         struct lock_class *middle_class = prev_class;
1404
1405         if (middle_class == safe_class)
1406                 middle_class = next_class;
1407
1408         /*
1409          * A direct locking problem where unsafe_class lock is taken
1410          * directly by safe_class lock, then all we need to show
1411          * is the deadlock scenario, as it is obvious that the
1412          * unsafe lock is taken under the safe lock.
1413          *
1414          * But if there is a chain instead, where the safe lock takes
1415          * an intermediate lock (middle_class) where this lock is
1416          * not the same as the safe lock, then the lock chain is
1417          * used to describe the problem. Otherwise we would need
1418          * to show a different CPU case for each link in the chain
1419          * from the safe_class lock to the unsafe_class lock.
1420          */
1421         if (middle_class != unsafe_class) {
1422                 printk("Chain exists of:\n  ");
1423                 __print_lock_name(safe_class);
1424                 printk(" --> ");
1425                 __print_lock_name(middle_class);
1426                 printk(" --> ");
1427                 __print_lock_name(unsafe_class);
1428                 printk("\n\n");
1429         }
1430
1431         printk(" Possible interrupt unsafe locking scenario:\n\n");
1432         printk("       CPU0                    CPU1\n");
1433         printk("       ----                    ----\n");
1434         printk("  lock(");
1435         __print_lock_name(unsafe_class);
1436         printk(");\n");
1437         printk("                               local_irq_disable();\n");
1438         printk("                               lock(");
1439         __print_lock_name(safe_class);
1440         printk(");\n");
1441         printk("                               lock(");
1442         __print_lock_name(middle_class);
1443         printk(");\n");
1444         printk("  <Interrupt>\n");
1445         printk("    lock(");
1446         __print_lock_name(safe_class);
1447         printk(");\n");
1448         printk("\n *** DEADLOCK ***\n\n");
1449 }
1450
1451 static int
1452 print_bad_irq_dependency(struct task_struct *curr,
1453                          struct lock_list *prev_root,
1454                          struct lock_list *next_root,
1455                          struct lock_list *backwards_entry,
1456                          struct lock_list *forwards_entry,
1457                          struct held_lock *prev,
1458                          struct held_lock *next,
1459                          enum lock_usage_bit bit1,
1460                          enum lock_usage_bit bit2,
1461                          const char *irqclass)
1462 {
1463         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1464                 return 0;
1465
1466         printk("\n======================================================\n");
1467         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1468                 irqclass, irqclass);
1469         print_kernel_version();
1470         printk(  "------------------------------------------------------\n");
1471         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1472                 curr->comm, task_pid_nr(curr),
1473                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1474                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1475                 curr->hardirqs_enabled,
1476                 curr->softirqs_enabled);
1477         print_lock(next);
1478
1479         printk("\nand this task is already holding:\n");
1480         print_lock(prev);
1481         printk("which would create a new lock dependency:\n");
1482         print_lock_name(hlock_class(prev));
1483         printk(" ->");
1484         print_lock_name(hlock_class(next));
1485         printk("\n");
1486
1487         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1488                 irqclass);
1489         print_lock_name(backwards_entry->class);
1490         printk("\n... which became %s-irq-safe at:\n", irqclass);
1491
1492         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1493
1494         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1495         print_lock_name(forwards_entry->class);
1496         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1497         printk("...");
1498
1499         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1500
1501         printk("\nother info that might help us debug this:\n\n");
1502         print_irq_lock_scenario(backwards_entry, forwards_entry,
1503                                 hlock_class(prev), hlock_class(next));
1504
1505         lockdep_print_held_locks(curr);
1506
1507         printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1508         printk(" and the holding lock:\n");
1509         if (!save_trace(&prev_root->trace))
1510                 return 0;
1511         print_shortest_lock_dependencies(backwards_entry, prev_root);
1512
1513         printk("\nthe dependencies between the lock to be acquired");
1514         printk(" and %s-irq-unsafe lock:\n", irqclass);
1515         if (!save_trace(&next_root->trace))
1516                 return 0;
1517         print_shortest_lock_dependencies(forwards_entry, next_root);
1518
1519         printk("\nstack backtrace:\n");
1520         dump_stack();
1521
1522         return 0;
1523 }
1524
1525 static int
1526 check_usage(struct task_struct *curr, struct held_lock *prev,
1527             struct held_lock *next, enum lock_usage_bit bit_backwards,
1528             enum lock_usage_bit bit_forwards, const char *irqclass)
1529 {
1530         int ret;
1531         struct lock_list this, that;
1532         struct lock_list *uninitialized_var(target_entry);
1533         struct lock_list *uninitialized_var(target_entry1);
1534
1535         this.parent = NULL;
1536
1537         this.class = hlock_class(prev);
1538         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1539         if (ret < 0)
1540                 return print_bfs_bug(ret);
1541         if (ret == 1)
1542                 return ret;
1543
1544         that.parent = NULL;
1545         that.class = hlock_class(next);
1546         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1547         if (ret < 0)
1548                 return print_bfs_bug(ret);
1549         if (ret == 1)
1550                 return ret;
1551
1552         return print_bad_irq_dependency(curr, &this, &that,
1553                         target_entry, target_entry1,
1554                         prev, next,
1555                         bit_backwards, bit_forwards, irqclass);
1556 }
1557
1558 static const char *state_names[] = {
1559 #define LOCKDEP_STATE(__STATE) \
1560         __stringify(__STATE),
1561 #include "lockdep_states.h"
1562 #undef LOCKDEP_STATE
1563 };
1564
1565 static const char *state_rnames[] = {
1566 #define LOCKDEP_STATE(__STATE) \
1567         __stringify(__STATE)"-READ",
1568 #include "lockdep_states.h"
1569 #undef LOCKDEP_STATE
1570 };
1571
1572 static inline const char *state_name(enum lock_usage_bit bit)
1573 {
1574         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1575 }
1576
1577 static int exclusive_bit(int new_bit)
1578 {
1579         /*
1580          * USED_IN
1581          * USED_IN_READ
1582          * ENABLED
1583          * ENABLED_READ
1584          *
1585          * bit 0 - write/read
1586          * bit 1 - used_in/enabled
1587          * bit 2+  state
1588          */
1589
1590         int state = new_bit & ~3;
1591         int dir = new_bit & 2;
1592
1593         /*
1594          * keep state, bit flip the direction and strip read.
1595          */
1596         return state | (dir ^ 2);
1597 }
1598
1599 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1600                            struct held_lock *next, enum lock_usage_bit bit)
1601 {
1602         /*
1603          * Prove that the new dependency does not connect a hardirq-safe
1604          * lock with a hardirq-unsafe lock - to achieve this we search
1605          * the backwards-subgraph starting at <prev>, and the
1606          * forwards-subgraph starting at <next>:
1607          */
1608         if (!check_usage(curr, prev, next, bit,
1609                            exclusive_bit(bit), state_name(bit)))
1610                 return 0;
1611
1612         bit++; /* _READ */
1613
1614         /*
1615          * Prove that the new dependency does not connect a hardirq-safe-read
1616          * lock with a hardirq-unsafe lock - to achieve this we search
1617          * the backwards-subgraph starting at <prev>, and the
1618          * forwards-subgraph starting at <next>:
1619          */
1620         if (!check_usage(curr, prev, next, bit,
1621                            exclusive_bit(bit), state_name(bit)))
1622                 return 0;
1623
1624         return 1;
1625 }
1626
1627 static int
1628 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1629                 struct held_lock *next)
1630 {
1631 #define LOCKDEP_STATE(__STATE)                                          \
1632         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1633                 return 0;
1634 #include "lockdep_states.h"
1635 #undef LOCKDEP_STATE
1636
1637         return 1;
1638 }
1639
1640 static void inc_chains(void)
1641 {
1642         if (current->hardirq_context)
1643                 nr_hardirq_chains++;
1644         else {
1645                 if (current->softirq_context)
1646                         nr_softirq_chains++;
1647                 else
1648                         nr_process_chains++;
1649         }
1650 }
1651
1652 #else
1653
1654 static inline int
1655 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1656                 struct held_lock *next)
1657 {
1658         return 1;
1659 }
1660
1661 static inline void inc_chains(void)
1662 {
1663         nr_process_chains++;
1664 }
1665
1666 #endif
1667
1668 static void
1669 print_deadlock_scenario(struct held_lock *nxt,
1670                              struct held_lock *prv)
1671 {
1672         struct lock_class *next = hlock_class(nxt);
1673         struct lock_class *prev = hlock_class(prv);
1674
1675         printk(" Possible unsafe locking scenario:\n\n");
1676         printk("       CPU0\n");
1677         printk("       ----\n");
1678         printk("  lock(");
1679         __print_lock_name(prev);
1680         printk(");\n");
1681         printk("  lock(");
1682         __print_lock_name(next);
1683         printk(");\n");
1684         printk("\n *** DEADLOCK ***\n\n");
1685         printk(" May be due to missing lock nesting notation\n\n");
1686 }
1687
1688 static int
1689 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1690                    struct held_lock *next)
1691 {
1692         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1693                 return 0;
1694
1695         printk("\n=============================================\n");
1696         printk(  "[ INFO: possible recursive locking detected ]\n");
1697         print_kernel_version();
1698         printk(  "---------------------------------------------\n");
1699         printk("%s/%d is trying to acquire lock:\n",
1700                 curr->comm, task_pid_nr(curr));
1701         print_lock(next);
1702         printk("\nbut task is already holding lock:\n");
1703         print_lock(prev);
1704
1705         printk("\nother info that might help us debug this:\n");
1706         print_deadlock_scenario(next, prev);
1707         lockdep_print_held_locks(curr);
1708
1709         printk("\nstack backtrace:\n");
1710         dump_stack();
1711
1712         return 0;
1713 }
1714
1715 /*
1716  * Check whether we are holding such a class already.
1717  *
1718  * (Note that this has to be done separately, because the graph cannot
1719  * detect such classes of deadlocks.)
1720  *
1721  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1722  */
1723 static int
1724 check_deadlock(struct task_struct *curr, struct held_lock *next,
1725                struct lockdep_map *next_instance, int read)
1726 {
1727         struct held_lock *prev;
1728         struct held_lock *nest = NULL;
1729         int i;
1730
1731         for (i = 0; i < curr->lockdep_depth; i++) {
1732                 prev = curr->held_locks + i;
1733
1734                 if (prev->instance == next->nest_lock)
1735                         nest = prev;
1736
1737                 if (hlock_class(prev) != hlock_class(next))
1738                         continue;
1739
1740                 /*
1741                  * Allow read-after-read recursion of the same
1742                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1743                  */
1744                 if ((read == 2) && prev->read)
1745                         return 2;
1746
1747                 /*
1748                  * We're holding the nest_lock, which serializes this lock's
1749                  * nesting behaviour.
1750                  */
1751                 if (nest)
1752                         return 2;
1753
1754                 return print_deadlock_bug(curr, prev, next);
1755         }
1756         return 1;
1757 }
1758
1759 /*
1760  * There was a chain-cache miss, and we are about to add a new dependency
1761  * to a previous lock. We recursively validate the following rules:
1762  *
1763  *  - would the adding of the <prev> -> <next> dependency create a
1764  *    circular dependency in the graph? [== circular deadlock]
1765  *
1766  *  - does the new prev->next dependency connect any hardirq-safe lock
1767  *    (in the full backwards-subgraph starting at <prev>) with any
1768  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1769  *    <next>)? [== illegal lock inversion with hardirq contexts]
1770  *
1771  *  - does the new prev->next dependency connect any softirq-safe lock
1772  *    (in the full backwards-subgraph starting at <prev>) with any
1773  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1774  *    <next>)? [== illegal lock inversion with softirq contexts]
1775  *
1776  * any of these scenarios could lead to a deadlock.
1777  *
1778  * Then if all the validations pass, we add the forwards and backwards
1779  * dependency.
1780  */
1781 static int
1782 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1783                struct held_lock *next, int distance, int trylock_loop)
1784 {
1785         struct lock_list *entry;
1786         int ret;
1787         struct lock_list this;
1788         struct lock_list *uninitialized_var(target_entry);
1789         /*
1790          * Static variable, serialized by the graph_lock().
1791          *
1792          * We use this static variable to save the stack trace in case
1793          * we call into this function multiple times due to encountering
1794          * trylocks in the held lock stack.
1795          */
1796         static struct stack_trace trace;
1797
1798         /*
1799          * Prove that the new <prev> -> <next> dependency would not
1800          * create a circular dependency in the graph. (We do this by
1801          * forward-recursing into the graph starting at <next>, and
1802          * checking whether we can reach <prev>.)
1803          *
1804          * We are using global variables to control the recursion, to
1805          * keep the stackframe size of the recursive functions low:
1806          */
1807         this.class = hlock_class(next);
1808         this.parent = NULL;
1809         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1810         if (unlikely(!ret))
1811                 return print_circular_bug(&this, target_entry, next, prev);
1812         else if (unlikely(ret < 0))
1813                 return print_bfs_bug(ret);
1814
1815         if (!check_prev_add_irq(curr, prev, next))
1816                 return 0;
1817
1818         /*
1819          * For recursive read-locks we do all the dependency checks,
1820          * but we dont store read-triggered dependencies (only
1821          * write-triggered dependencies). This ensures that only the
1822          * write-side dependencies matter, and that if for example a
1823          * write-lock never takes any other locks, then the reads are
1824          * equivalent to a NOP.
1825          */
1826         if (next->read == 2 || prev->read == 2)
1827                 return 1;
1828         /*
1829          * Is the <prev> -> <next> dependency already present?
1830          *
1831          * (this may occur even though this is a new chain: consider
1832          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1833          *  chains - the second one will be new, but L1 already has
1834          *  L2 added to its dependency list, due to the first chain.)
1835          */
1836         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1837                 if (entry->class == hlock_class(next)) {
1838                         if (distance == 1)
1839                                 entry->distance = 1;
1840                         return 2;
1841                 }
1842         }
1843
1844         if (!trylock_loop && !save_trace(&trace))
1845                 return 0;
1846
1847         /*
1848          * Ok, all validations passed, add the new lock
1849          * to the previous lock's dependency list:
1850          */
1851         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1852                                &hlock_class(prev)->locks_after,
1853                                next->acquire_ip, distance, &trace);
1854
1855         if (!ret)
1856                 return 0;
1857
1858         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1859                                &hlock_class(next)->locks_before,
1860                                next->acquire_ip, distance, &trace);
1861         if (!ret)
1862                 return 0;
1863
1864         /*
1865          * Debugging printouts:
1866          */
1867         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1868                 graph_unlock();
1869                 printk("\n new dependency: ");
1870                 print_lock_name(hlock_class(prev));
1871                 printk(" => ");
1872                 print_lock_name(hlock_class(next));
1873                 printk("\n");
1874                 dump_stack();
1875                 return graph_lock();
1876         }
1877         return 1;
1878 }
1879
1880 /*
1881  * Add the dependency to all directly-previous locks that are 'relevant'.
1882  * The ones that are relevant are (in increasing distance from curr):
1883  * all consecutive trylock entries and the final non-trylock entry - or
1884  * the end of this context's lock-chain - whichever comes first.
1885  */
1886 static int
1887 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1888 {
1889         int depth = curr->lockdep_depth;
1890         int trylock_loop = 0;
1891         struct held_lock *hlock;
1892
1893         /*
1894          * Debugging checks.
1895          *
1896          * Depth must not be zero for a non-head lock:
1897          */
1898         if (!depth)
1899                 goto out_bug;
1900         /*
1901          * At least two relevant locks must exist for this
1902          * to be a head:
1903          */
1904         if (curr->held_locks[depth].irq_context !=
1905                         curr->held_locks[depth-1].irq_context)
1906                 goto out_bug;
1907
1908         for (;;) {
1909                 int distance = curr->lockdep_depth - depth + 1;
1910                 hlock = curr->held_locks + depth-1;
1911                 /*
1912                  * Only non-recursive-read entries get new dependencies
1913                  * added:
1914                  */
1915                 if (hlock->read != 2) {
1916                         if (!check_prev_add(curr, hlock, next,
1917                                                 distance, trylock_loop))
1918                                 return 0;
1919                         /*
1920                          * Stop after the first non-trylock entry,
1921                          * as non-trylock entries have added their
1922                          * own direct dependencies already, so this
1923                          * lock is connected to them indirectly:
1924                          */
1925                         if (!hlock->trylock)
1926                                 break;
1927                 }
1928                 depth--;
1929                 /*
1930                  * End of lock-stack?
1931                  */
1932                 if (!depth)
1933                         break;
1934                 /*
1935                  * Stop the search if we cross into another context:
1936                  */
1937                 if (curr->held_locks[depth].irq_context !=
1938                                 curr->held_locks[depth-1].irq_context)
1939                         break;
1940                 trylock_loop = 1;
1941         }
1942         return 1;
1943 out_bug:
1944         if (!debug_locks_off_graph_unlock())
1945                 return 0;
1946
1947         WARN_ON(1);
1948
1949         return 0;
1950 }
1951
1952 unsigned long nr_lock_chains;
1953 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1954 int nr_chain_hlocks;
1955 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1956
1957 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1958 {
1959         return lock_classes + chain_hlocks[chain->base + i];
1960 }
1961
1962 /*
1963  * Look up a dependency chain. If the key is not present yet then
1964  * add it and return 1 - in this case the new dependency chain is
1965  * validated. If the key is already hashed, return 0.
1966  * (On return with 1 graph_lock is held.)
1967  */
1968 static inline int lookup_chain_cache(struct task_struct *curr,
1969                                      struct held_lock *hlock,
1970                                      u64 chain_key)
1971 {
1972         struct lock_class *class = hlock_class(hlock);
1973         struct list_head *hash_head = chainhashentry(chain_key);
1974         struct lock_chain *chain;
1975         struct held_lock *hlock_curr, *hlock_next;
1976         int i, j, n, cn;
1977
1978         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1979                 return 0;
1980         /*
1981          * We can walk it lock-free, because entries only get added
1982          * to the hash:
1983          */
1984         list_for_each_entry(chain, hash_head, entry) {
1985                 if (chain->chain_key == chain_key) {
1986 cache_hit:
1987                         debug_atomic_inc(chain_lookup_hits);
1988                         if (very_verbose(class))
1989                                 printk("\nhash chain already cached, key: "
1990                                         "%016Lx tail class: [%p] %s\n",
1991                                         (unsigned long long)chain_key,
1992                                         class->key, class->name);
1993                         return 0;
1994                 }
1995         }
1996         if (very_verbose(class))
1997                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1998                         (unsigned long long)chain_key, class->key, class->name);
1999         /*
2000          * Allocate a new chain entry from the static array, and add
2001          * it to the hash:
2002          */
2003         if (!graph_lock())
2004                 return 0;
2005         /*
2006          * We have to walk the chain again locked - to avoid duplicates:
2007          */
2008         list_for_each_entry(chain, hash_head, entry) {
2009                 if (chain->chain_key == chain_key) {
2010                         graph_unlock();
2011                         goto cache_hit;
2012                 }
2013         }
2014         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2015                 if (!debug_locks_off_graph_unlock())
2016                         return 0;
2017
2018                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2019                 printk("turning off the locking correctness validator.\n");
2020                 dump_stack();
2021                 return 0;
2022         }
2023         chain = lock_chains + nr_lock_chains++;
2024         chain->chain_key = chain_key;
2025         chain->irq_context = hlock->irq_context;
2026         /* Find the first held_lock of current chain */
2027         hlock_next = hlock;
2028         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2029                 hlock_curr = curr->held_locks + i;
2030                 if (hlock_curr->irq_context != hlock_next->irq_context)
2031                         break;
2032                 hlock_next = hlock;
2033         }
2034         i++;
2035         chain->depth = curr->lockdep_depth + 1 - i;
2036         cn = nr_chain_hlocks;
2037         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
2038                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
2039                 if (n == cn)
2040                         break;
2041                 cn = n;
2042         }
2043         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2044                 chain->base = cn;
2045                 for (j = 0; j < chain->depth - 1; j++, i++) {
2046                         int lock_id = curr->held_locks[i].class_idx - 1;
2047                         chain_hlocks[chain->base + j] = lock_id;
2048                 }
2049                 chain_hlocks[chain->base + j] = class - lock_classes;
2050         }
2051         list_add_tail_rcu(&chain->entry, hash_head);
2052         debug_atomic_inc(chain_lookup_misses);
2053         inc_chains();
2054
2055         return 1;
2056 }
2057
2058 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2059                 struct held_lock *hlock, int chain_head, u64 chain_key)
2060 {
2061         /*
2062          * Trylock needs to maintain the stack of held locks, but it
2063          * does not add new dependencies, because trylock can be done
2064          * in any order.
2065          *
2066          * We look up the chain_key and do the O(N^2) check and update of
2067          * the dependencies only if this is a new dependency chain.
2068          * (If lookup_chain_cache() returns with 1 it acquires
2069          * graph_lock for us)
2070          */
2071         if (!hlock->trylock && (hlock->check == 2) &&
2072             lookup_chain_cache(curr, hlock, chain_key)) {
2073                 /*
2074                  * Check whether last held lock:
2075                  *
2076                  * - is irq-safe, if this lock is irq-unsafe
2077                  * - is softirq-safe, if this lock is hardirq-unsafe
2078                  *
2079                  * And check whether the new lock's dependency graph
2080                  * could lead back to the previous lock.
2081                  *
2082                  * any of these scenarios could lead to a deadlock. If
2083                  * All validations
2084                  */
2085                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2086
2087                 if (!ret)
2088                         return 0;
2089                 /*
2090                  * Mark recursive read, as we jump over it when
2091                  * building dependencies (just like we jump over
2092                  * trylock entries):
2093                  */
2094                 if (ret == 2)
2095                         hlock->read = 2;
2096                 /*
2097                  * Add dependency only if this lock is not the head
2098                  * of the chain, and if it's not a secondary read-lock:
2099                  */
2100                 if (!chain_head && ret != 2)
2101                         if (!check_prevs_add(curr, hlock))
2102                                 return 0;
2103                 graph_unlock();
2104         } else
2105                 /* after lookup_chain_cache(): */
2106                 if (unlikely(!debug_locks))
2107                         return 0;
2108
2109         return 1;
2110 }
2111 #else
2112 static inline int validate_chain(struct task_struct *curr,
2113                 struct lockdep_map *lock, struct held_lock *hlock,
2114                 int chain_head, u64 chain_key)
2115 {
2116         return 1;
2117 }
2118 #endif
2119
2120 /*
2121  * We are building curr_chain_key incrementally, so double-check
2122  * it from scratch, to make sure that it's done correctly:
2123  */
2124 static void check_chain_key(struct task_struct *curr)
2125 {
2126 #ifdef CONFIG_DEBUG_LOCKDEP
2127         struct held_lock *hlock, *prev_hlock = NULL;
2128         unsigned int i, id;
2129         u64 chain_key = 0;
2130
2131         for (i = 0; i < curr->lockdep_depth; i++) {
2132                 hlock = curr->held_locks + i;
2133                 if (chain_key != hlock->prev_chain_key) {
2134                         debug_locks_off();
2135                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2136                                 curr->lockdep_depth, i,
2137                                 (unsigned long long)chain_key,
2138                                 (unsigned long long)hlock->prev_chain_key);
2139                         return;
2140                 }
2141                 id = hlock->class_idx - 1;
2142                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2143                         return;
2144
2145                 if (prev_hlock && (prev_hlock->irq_context !=
2146                                                         hlock->irq_context))
2147                         chain_key = 0;
2148                 chain_key = iterate_chain_key(chain_key, id);
2149                 prev_hlock = hlock;
2150         }
2151         if (chain_key != curr->curr_chain_key) {
2152                 debug_locks_off();
2153                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2154                         curr->lockdep_depth, i,
2155                         (unsigned long long)chain_key,
2156                         (unsigned long long)curr->curr_chain_key);
2157         }
2158 #endif
2159 }
2160
2161 static void
2162 print_usage_bug_scenario(struct held_lock *lock)
2163 {
2164         struct lock_class *class = hlock_class(lock);
2165
2166         printk(" Possible unsafe locking scenario:\n\n");
2167         printk("       CPU0\n");
2168         printk("       ----\n");
2169         printk("  lock(");
2170         __print_lock_name(class);
2171         printk(");\n");
2172         printk("  <Interrupt>\n");
2173         printk("    lock(");
2174         __print_lock_name(class);
2175         printk(");\n");
2176         printk("\n *** DEADLOCK ***\n\n");
2177 }
2178
2179 static int
2180 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2181                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2182 {
2183         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2184                 return 0;
2185
2186         printk("\n=================================\n");
2187         printk(  "[ INFO: inconsistent lock state ]\n");
2188         print_kernel_version();
2189         printk(  "---------------------------------\n");
2190
2191         printk("inconsistent {%s} -> {%s} usage.\n",
2192                 usage_str[prev_bit], usage_str[new_bit]);
2193
2194         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2195                 curr->comm, task_pid_nr(curr),
2196                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2197                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2198                 trace_hardirqs_enabled(curr),
2199                 trace_softirqs_enabled(curr));
2200         print_lock(this);
2201
2202         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2203         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2204
2205         print_irqtrace_events(curr);
2206         printk("\nother info that might help us debug this:\n");
2207         print_usage_bug_scenario(this);
2208
2209         lockdep_print_held_locks(curr);
2210
2211         printk("\nstack backtrace:\n");
2212         dump_stack();
2213
2214         return 0;
2215 }
2216
2217 /*
2218  * Print out an error if an invalid bit is set:
2219  */
2220 static inline int
2221 valid_state(struct task_struct *curr, struct held_lock *this,
2222             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2223 {
2224         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2225                 return print_usage_bug(curr, this, bad_bit, new_bit);
2226         return 1;
2227 }
2228
2229 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2230                      enum lock_usage_bit new_bit);
2231
2232 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2233
2234 /*
2235  * print irq inversion bug:
2236  */
2237 static int
2238 print_irq_inversion_bug(struct task_struct *curr,
2239                         struct lock_list *root, struct lock_list *other,
2240                         struct held_lock *this, int forwards,
2241                         const char *irqclass)
2242 {
2243         struct lock_list *entry = other;
2244         struct lock_list *middle = NULL;
2245         int depth;
2246
2247         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2248                 return 0;
2249
2250         printk("\n=========================================================\n");
2251         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2252         print_kernel_version();
2253         printk(  "---------------------------------------------------------\n");
2254         printk("%s/%d just changed the state of lock:\n",
2255                 curr->comm, task_pid_nr(curr));
2256         print_lock(this);
2257         if (forwards)
2258                 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2259         else
2260                 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2261         print_lock_name(other->class);
2262         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2263
2264         printk("\nother info that might help us debug this:\n");
2265
2266         /* Find a middle lock (if one exists) */
2267         depth = get_lock_depth(other);
2268         do {
2269                 if (depth == 0 && (entry != root)) {
2270                         printk("lockdep:%s bad path found in chain graph\n", __func__);
2271                         break;
2272                 }
2273                 middle = entry;
2274                 entry = get_lock_parent(entry);
2275                 depth--;
2276         } while (entry && entry != root && (depth >= 0));
2277         if (forwards)
2278                 print_irq_lock_scenario(root, other,
2279                         middle ? middle->class : root->class, other->class);
2280         else
2281                 print_irq_lock_scenario(other, root,
2282                         middle ? middle->class : other->class, root->class);
2283
2284         lockdep_print_held_locks(curr);
2285
2286         printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2287         if (!save_trace(&root->trace))
2288                 return 0;
2289         print_shortest_lock_dependencies(other, root);
2290
2291         printk("\nstack backtrace:\n");
2292         dump_stack();
2293
2294         return 0;
2295 }
2296
2297 /*
2298  * Prove that in the forwards-direction subgraph starting at <this>
2299  * there is no lock matching <mask>:
2300  */
2301 static int
2302 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2303                      enum lock_usage_bit bit, const char *irqclass)
2304 {
2305         int ret;
2306         struct lock_list root;
2307         struct lock_list *uninitialized_var(target_entry);
2308
2309         root.parent = NULL;
2310         root.class = hlock_class(this);
2311         ret = find_usage_forwards(&root, bit, &target_entry);
2312         if (ret < 0)
2313                 return print_bfs_bug(ret);
2314         if (ret == 1)
2315                 return ret;
2316
2317         return print_irq_inversion_bug(curr, &root, target_entry,
2318                                         this, 1, irqclass);
2319 }
2320
2321 /*
2322  * Prove that in the backwards-direction subgraph starting at <this>
2323  * there is no lock matching <mask>:
2324  */
2325 static int
2326 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2327                       enum lock_usage_bit bit, const char *irqclass)
2328 {
2329         int ret;
2330         struct lock_list root;
2331         struct lock_list *uninitialized_var(target_entry);
2332
2333         root.parent = NULL;
2334         root.class = hlock_class(this);
2335         ret = find_usage_backwards(&root, bit, &target_entry);
2336         if (ret < 0)
2337                 return print_bfs_bug(ret);
2338         if (ret == 1)
2339                 return ret;
2340
2341         return print_irq_inversion_bug(curr, &root, target_entry,
2342                                         this, 0, irqclass);
2343 }
2344
2345 void print_irqtrace_events(struct task_struct *curr)
2346 {
2347         printk("irq event stamp: %u\n", curr->irq_events);
2348         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2349         print_ip_sym(curr->hardirq_enable_ip);
2350         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2351         print_ip_sym(curr->hardirq_disable_ip);
2352         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2353         print_ip_sym(curr->softirq_enable_ip);
2354         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2355         print_ip_sym(curr->softirq_disable_ip);
2356 }
2357
2358 static int HARDIRQ_verbose(struct lock_class *class)
2359 {
2360 #if HARDIRQ_VERBOSE
2361         return class_filter(class);
2362 #endif
2363         return 0;
2364 }
2365
2366 static int SOFTIRQ_verbose(struct lock_class *class)
2367 {
2368 #if SOFTIRQ_VERBOSE
2369         return class_filter(class);
2370 #endif
2371         return 0;
2372 }
2373
2374 static int RECLAIM_FS_verbose(struct lock_class *class)
2375 {
2376 #if RECLAIM_VERBOSE
2377         return class_filter(class);
2378 #endif
2379         return 0;
2380 }
2381
2382 #define STRICT_READ_CHECKS      1
2383
2384 static int (*state_verbose_f[])(struct lock_class *class) = {
2385 #define LOCKDEP_STATE(__STATE) \
2386         __STATE##_verbose,
2387 #include "lockdep_states.h"
2388 #undef LOCKDEP_STATE
2389 };
2390
2391 static inline int state_verbose(enum lock_usage_bit bit,
2392                                 struct lock_class *class)
2393 {
2394         return state_verbose_f[bit >> 2](class);
2395 }
2396
2397 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2398                              enum lock_usage_bit bit, const char *name);
2399
2400 static int
2401 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2402                 enum lock_usage_bit new_bit)
2403 {
2404         int excl_bit = exclusive_bit(new_bit);
2405         int read = new_bit & 1;
2406         int dir = new_bit & 2;
2407
2408         /*
2409          * mark USED_IN has to look forwards -- to ensure no dependency
2410          * has ENABLED state, which would allow recursion deadlocks.
2411          *
2412          * mark ENABLED has to look backwards -- to ensure no dependee
2413          * has USED_IN state, which, again, would allow  recursion deadlocks.
2414          */
2415         check_usage_f usage = dir ?
2416                 check_usage_backwards : check_usage_forwards;
2417
2418         /*
2419          * Validate that this particular lock does not have conflicting
2420          * usage states.
2421          */
2422         if (!valid_state(curr, this, new_bit, excl_bit))
2423                 return 0;
2424
2425         /*
2426          * Validate that the lock dependencies don't have conflicting usage
2427          * states.
2428          */
2429         if ((!read || !dir || STRICT_READ_CHECKS) &&
2430                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2431                 return 0;
2432
2433         /*
2434          * Check for read in write conflicts
2435          */
2436         if (!read) {
2437                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2438                         return 0;
2439
2440                 if (STRICT_READ_CHECKS &&
2441                         !usage(curr, this, excl_bit + 1,
2442                                 state_name(new_bit + 1)))
2443                         return 0;
2444         }
2445
2446         if (state_verbose(new_bit, hlock_class(this)))
2447                 return 2;
2448
2449         return 1;
2450 }
2451
2452 enum mark_type {
2453 #define LOCKDEP_STATE(__STATE)  __STATE,
2454 #include "lockdep_states.h"
2455 #undef LOCKDEP_STATE
2456 };
2457
2458 /*
2459  * Mark all held locks with a usage bit:
2460  */
2461 static int
2462 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2463 {
2464         enum lock_usage_bit usage_bit;
2465         struct held_lock *hlock;
2466         int i;
2467
2468         for (i = 0; i < curr->lockdep_depth; i++) {
2469                 hlock = curr->held_locks + i;
2470
2471                 usage_bit = 2 + (mark << 2); /* ENABLED */
2472                 if (hlock->read)
2473                         usage_bit += 1; /* READ */
2474
2475                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2476
2477                 if (!mark_lock(curr, hlock, usage_bit))
2478                         return 0;
2479         }
2480
2481         return 1;
2482 }
2483
2484 /*
2485  * Hardirqs will be enabled:
2486  */
2487 void trace_hardirqs_on_caller(unsigned long ip)
2488 {
2489         struct task_struct *curr = current;
2490
2491         time_hardirqs_on(CALLER_ADDR0, ip);
2492
2493         if (unlikely(!debug_locks || current->lockdep_recursion))
2494                 return;
2495
2496         if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2497                 return;
2498
2499         if (unlikely(curr->hardirqs_enabled)) {
2500                 /*
2501                  * Neither irq nor preemption are disabled here
2502                  * so this is racy by nature but losing one hit
2503                  * in a stat is not a big deal.
2504                  */
2505                 __debug_atomic_inc(redundant_hardirqs_on);
2506                 return;
2507         }
2508         /* we'll do an OFF -> ON transition: */
2509         curr->hardirqs_enabled = 1;
2510
2511         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2512                 return;
2513         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2514                 return;
2515         /*
2516          * We are going to turn hardirqs on, so set the
2517          * usage bit for all held locks:
2518          */
2519         if (!mark_held_locks(curr, HARDIRQ))
2520                 return;
2521         /*
2522          * If we have softirqs enabled, then set the usage
2523          * bit for all held locks. (disabled hardirqs prevented
2524          * this bit from being set before)
2525          */
2526         if (curr->softirqs_enabled)
2527                 if (!mark_held_locks(curr, SOFTIRQ))
2528                         return;
2529
2530         curr->hardirq_enable_ip = ip;
2531         curr->hardirq_enable_event = ++curr->irq_events;
2532         debug_atomic_inc(hardirqs_on_events);
2533 }
2534 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2535
2536 void trace_hardirqs_on(void)
2537 {
2538         trace_hardirqs_on_caller(CALLER_ADDR0);
2539 }
2540 EXPORT_SYMBOL(trace_hardirqs_on);
2541
2542 /*
2543  * Hardirqs were disabled:
2544  */
2545 void trace_hardirqs_off_caller(unsigned long ip)
2546 {
2547         struct task_struct *curr = current;
2548
2549         time_hardirqs_off(CALLER_ADDR0, ip);
2550
2551         if (unlikely(!debug_locks || current->lockdep_recursion))
2552                 return;
2553
2554         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2555                 return;
2556
2557         if (curr->hardirqs_enabled) {
2558                 /*
2559                  * We have done an ON -> OFF transition:
2560                  */
2561                 curr->hardirqs_enabled = 0;
2562                 curr->hardirq_disable_ip = ip;
2563                 curr->hardirq_disable_event = ++curr->irq_events;
2564                 debug_atomic_inc(hardirqs_off_events);
2565         } else
2566                 debug_atomic_inc(redundant_hardirqs_off);
2567 }
2568 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2569
2570 void trace_hardirqs_off(void)
2571 {
2572         trace_hardirqs_off_caller(CALLER_ADDR0);
2573 }
2574 EXPORT_SYMBOL(trace_hardirqs_off);
2575
2576 /*
2577  * Softirqs will be enabled:
2578  */
2579 void trace_softirqs_on(unsigned long ip)
2580 {
2581         struct task_struct *curr = current;
2582
2583         if (unlikely(!debug_locks))
2584                 return;
2585
2586         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2587                 return;
2588
2589         if (curr->softirqs_enabled) {
2590                 debug_atomic_inc(redundant_softirqs_on);
2591                 return;
2592         }
2593
2594         /*
2595          * We'll do an OFF -> ON transition:
2596          */
2597         curr->softirqs_enabled = 1;
2598         curr->softirq_enable_ip = ip;
2599         curr->softirq_enable_event = ++curr->irq_events;
2600         debug_atomic_inc(softirqs_on_events);
2601         /*
2602          * We are going to turn softirqs on, so set the
2603          * usage bit for all held locks, if hardirqs are
2604          * enabled too:
2605          */
2606         if (curr->hardirqs_enabled)
2607                 mark_held_locks(curr, SOFTIRQ);
2608 }
2609
2610 /*
2611  * Softirqs were disabled:
2612  */
2613 void trace_softirqs_off(unsigned long ip)
2614 {
2615         struct task_struct *curr = current;
2616
2617         if (unlikely(!debug_locks))
2618                 return;
2619
2620         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2621                 return;
2622
2623         if (curr->softirqs_enabled) {
2624                 /*
2625                  * We have done an ON -> OFF transition:
2626                  */
2627                 curr->softirqs_enabled = 0;
2628                 curr->softirq_disable_ip = ip;
2629                 curr->softirq_disable_event = ++curr->irq_events;
2630                 debug_atomic_inc(softirqs_off_events);
2631                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2632         } else
2633                 debug_atomic_inc(redundant_softirqs_off);
2634 }
2635
2636 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2637 {
2638         struct task_struct *curr = current;
2639
2640         if (unlikely(!debug_locks))
2641                 return;
2642
2643         /* no reclaim without waiting on it */
2644         if (!(gfp_mask & __GFP_WAIT))
2645                 return;
2646
2647         /* this guy won't enter reclaim */
2648         if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2649                 return;
2650
2651         /* We're only interested __GFP_FS allocations for now */
2652         if (!(gfp_mask & __GFP_FS))
2653                 return;
2654
2655         if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2656                 return;
2657
2658         mark_held_locks(curr, RECLAIM_FS);
2659 }
2660
2661 static void check_flags(unsigned long flags);
2662
2663 void lockdep_trace_alloc(gfp_t gfp_mask)
2664 {
2665         unsigned long flags;
2666
2667         if (unlikely(current->lockdep_recursion))
2668                 return;
2669
2670         raw_local_irq_save(flags);
2671         check_flags(flags);
2672         current->lockdep_recursion = 1;
2673         __lockdep_trace_alloc(gfp_mask, flags);
2674         current->lockdep_recursion = 0;
2675         raw_local_irq_restore(flags);
2676 }
2677
2678 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2679 {
2680         /*
2681          * If non-trylock use in a hardirq or softirq context, then
2682          * mark the lock as used in these contexts:
2683          */
2684         if (!hlock->trylock) {
2685                 if (hlock->read) {
2686                         if (curr->hardirq_context)
2687                                 if (!mark_lock(curr, hlock,
2688                                                 LOCK_USED_IN_HARDIRQ_READ))
2689                                         return 0;
2690                         if (curr->softirq_context)
2691                                 if (!mark_lock(curr, hlock,
2692                                                 LOCK_USED_IN_SOFTIRQ_READ))
2693                                         return 0;
2694                 } else {
2695                         if (curr->hardirq_context)
2696                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2697                                         return 0;
2698                         if (curr->softirq_context)
2699                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2700                                         return 0;
2701                 }
2702         }
2703         if (!hlock->hardirqs_off) {
2704                 if (hlock->read) {
2705                         if (!mark_lock(curr, hlock,
2706                                         LOCK_ENABLED_HARDIRQ_READ))
2707                                 return 0;
2708                         if (curr->softirqs_enabled)
2709                                 if (!mark_lock(curr, hlock,
2710                                                 LOCK_ENABLED_SOFTIRQ_READ))
2711                                         return 0;
2712                 } else {
2713                         if (!mark_lock(curr, hlock,
2714                                         LOCK_ENABLED_HARDIRQ))
2715                                 return 0;
2716                         if (curr->softirqs_enabled)
2717                                 if (!mark_lock(curr, hlock,
2718                                                 LOCK_ENABLED_SOFTIRQ))
2719                                         return 0;
2720                 }
2721         }
2722
2723         /*
2724          * We reuse the irq context infrastructure more broadly as a general
2725          * context checking code. This tests GFP_FS recursion (a lock taken
2726          * during reclaim for a GFP_FS allocation is held over a GFP_FS
2727          * allocation).
2728          */
2729         if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2730                 if (hlock->read) {
2731                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2732                                         return 0;
2733                 } else {
2734                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2735                                         return 0;
2736                 }
2737         }
2738
2739         return 1;
2740 }
2741
2742 static int separate_irq_context(struct task_struct *curr,
2743                 struct held_lock *hlock)
2744 {
2745         unsigned int depth = curr->lockdep_depth;
2746
2747         /*
2748          * Keep track of points where we cross into an interrupt context:
2749          */
2750         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2751                                 curr->softirq_context;
2752         if (depth) {
2753                 struct held_lock *prev_hlock;
2754
2755                 prev_hlock = curr->held_locks + depth-1;
2756                 /*
2757                  * If we cross into another context, reset the
2758                  * hash key (this also prevents the checking and the
2759                  * adding of the dependency to 'prev'):
2760                  */
2761                 if (prev_hlock->irq_context != hlock->irq_context)
2762                         return 1;
2763         }
2764         return 0;
2765 }
2766
2767 #else
2768
2769 static inline
2770 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2771                 enum lock_usage_bit new_bit)
2772 {
2773         WARN_ON(1);
2774         return 1;
2775 }
2776
2777 static inline int mark_irqflags(struct task_struct *curr,
2778                 struct held_lock *hlock)
2779 {
2780         return 1;
2781 }
2782
2783 static inline int separate_irq_context(struct task_struct *curr,
2784                 struct held_lock *hlock)
2785 {
2786         return 0;
2787 }
2788
2789 void lockdep_trace_alloc(gfp_t gfp_mask)
2790 {
2791 }
2792
2793 #endif
2794
2795 /*
2796  * Mark a lock with a usage bit, and validate the state transition:
2797  */
2798 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2799                              enum lock_usage_bit new_bit)
2800 {
2801         unsigned int new_mask = 1 << new_bit, ret = 1;
2802
2803         /*
2804          * If already set then do not dirty the cacheline,
2805          * nor do any checks:
2806          */
2807         if (likely(hlock_class(this)->usage_mask & new_mask))
2808                 return 1;
2809
2810         if (!graph_lock())
2811                 return 0;
2812         /*
2813          * Make sure we didn't race:
2814          */
2815         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2816                 graph_unlock();
2817                 return 1;
2818         }
2819
2820         hlock_class(this)->usage_mask |= new_mask;
2821
2822         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2823                 return 0;
2824
2825         switch (new_bit) {
2826 #define LOCKDEP_STATE(__STATE)                  \
2827         case LOCK_USED_IN_##__STATE:            \
2828         case LOCK_USED_IN_##__STATE##_READ:     \
2829         case LOCK_ENABLED_##__STATE:            \
2830         case LOCK_ENABLED_##__STATE##_READ:
2831 #include "lockdep_states.h"
2832 #undef LOCKDEP_STATE
2833                 ret = mark_lock_irq(curr, this, new_bit);
2834                 if (!ret)
2835                         return 0;
2836                 break;
2837         case LOCK_USED:
2838                 debug_atomic_dec(nr_unused_locks);
2839                 break;
2840         default:
2841                 if (!debug_locks_off_graph_unlock())
2842                         return 0;
2843                 WARN_ON(1);
2844                 return 0;
2845         }
2846
2847         graph_unlock();
2848
2849         /*
2850          * We must printk outside of the graph_lock:
2851          */
2852         if (ret == 2) {
2853                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2854                 print_lock(this);
2855                 print_irqtrace_events(curr);
2856                 dump_stack();
2857         }
2858
2859         return ret;
2860 }
2861
2862 /*
2863  * Initialize a lock instance's lock-class mapping info:
2864  */
2865 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2866                       struct lock_class_key *key, int subclass)
2867 {
2868         int i;
2869
2870         for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2871                 lock->class_cache[i] = NULL;
2872
2873 #ifdef CONFIG_LOCK_STAT
2874         lock->cpu = raw_smp_processor_id();
2875 #endif
2876
2877         if (DEBUG_LOCKS_WARN_ON(!name)) {
2878                 lock->name = "NULL";
2879                 return;
2880         }
2881
2882         lock->name = name;
2883
2884         if (DEBUG_LOCKS_WARN_ON(!key))
2885                 return;
2886         /*
2887          * Sanity check, the lock-class key must be persistent:
2888          */
2889         if (!static_obj(key)) {
2890                 printk("BUG: key %p not in .data!\n", key);
2891                 DEBUG_LOCKS_WARN_ON(1);
2892                 return;
2893         }
2894         lock->key = key;
2895
2896         if (unlikely(!debug_locks))
2897                 return;
2898
2899         if (subclass)
2900                 register_lock_class(lock, subclass, 1);
2901 }
2902 EXPORT_SYMBOL_GPL(lockdep_init_map);
2903
2904 struct lock_class_key __lockdep_no_validate__;
2905
2906 /*
2907  * This gets called for every mutex_lock*()/spin_lock*() operation.
2908  * We maintain the dependency maps and validate the locking attempt:
2909  */
2910 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2911                           int trylock, int read, int check, int hardirqs_off,
2912                           struct lockdep_map *nest_lock, unsigned long ip,
2913                           int references)
2914 {
2915         struct task_struct *curr = current;
2916         struct lock_class *class = NULL;
2917         struct held_lock *hlock;
2918         unsigned int depth, id;
2919         int chain_head = 0;
2920         int class_idx;
2921         u64 chain_key;
2922
2923         if (!prove_locking)
2924                 check = 1;
2925
2926         if (unlikely(!debug_locks))
2927                 return 0;
2928
2929         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2930                 return 0;
2931
2932         if (lock->key == &__lockdep_no_validate__)
2933                 check = 1;
2934
2935         if (subclass < NR_LOCKDEP_CACHING_CLASSES)
2936                 class = lock->class_cache[subclass];
2937         /*
2938          * Not cached?
2939          */
2940         if (unlikely(!class)) {
2941                 class = register_lock_class(lock, subclass, 0);
2942                 if (!class)
2943                         return 0;
2944         }
2945         atomic_inc((atomic_t *)&class->ops);
2946         if (very_verbose(class)) {
2947                 printk("\nacquire class [%p] %s", class->key, class->name);
2948                 if (class->name_version > 1)
2949                         printk("#%d", class->name_version);
2950                 printk("\n");
2951                 dump_stack();
2952         }
2953
2954         /*
2955          * Add the lock to the list of currently held locks.
2956          * (we dont increase the depth just yet, up until the
2957          * dependency checks are done)
2958          */
2959         depth = curr->lockdep_depth;
2960         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2961                 return 0;
2962
2963         class_idx = class - lock_classes + 1;
2964
2965         if (depth) {
2966                 hlock = curr->held_locks + depth - 1;
2967                 if (hlock->class_idx == class_idx && nest_lock) {
2968                         if (hlock->references)
2969                                 hlock->references++;
2970                         else
2971                                 hlock->references = 2;
2972
2973                         return 1;
2974                 }
2975         }
2976
2977         hlock = curr->held_locks + depth;
2978         if (DEBUG_LOCKS_WARN_ON(!class))
2979                 return 0;
2980         hlock->class_idx = class_idx;
2981         hlock->acquire_ip = ip;
2982         hlock->instance = lock;
2983         hlock->nest_lock = nest_lock;
2984         hlock->trylock = trylock;
2985         hlock->read = read;
2986         hlock->check = check;
2987         hlock->hardirqs_off = !!hardirqs_off;
2988         hlock->references = references;
2989 #ifdef CONFIG_LOCK_STAT
2990         hlock->waittime_stamp = 0;
2991         hlock->holdtime_stamp = lockstat_clock();
2992 #endif
2993
2994         if (check == 2 && !mark_irqflags(curr, hlock))
2995                 return 0;
2996
2997         /* mark it as used: */
2998         if (!mark_lock(curr, hlock, LOCK_USED))
2999                 return 0;
3000
3001         /*
3002          * Calculate the chain hash: it's the combined hash of all the
3003          * lock keys along the dependency chain. We save the hash value
3004          * at every step so that we can get the current hash easily
3005          * after unlock. The chain hash is then used to cache dependency
3006          * results.
3007          *
3008          * The 'key ID' is what is the most compact key value to drive
3009          * the hash, not class->key.
3010          */
3011         id = class - lock_classes;
3012         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3013                 return 0;
3014
3015         chain_key = curr->curr_chain_key;
3016         if (!depth) {
3017                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3018                         return 0;
3019                 chain_head = 1;
3020         }
3021
3022         hlock->prev_chain_key = chain_key;
3023         if (separate_irq_context(curr, hlock)) {
3024                 chain_key = 0;
3025                 chain_head = 1;
3026         }
3027         chain_key = iterate_chain_key(chain_key, id);
3028
3029         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3030                 return 0;
3031
3032         curr->curr_chain_key = chain_key;
3033         curr->lockdep_depth++;
3034         check_chain_key(curr);
3035 #ifdef CONFIG_DEBUG_LOCKDEP
3036         if (unlikely(!debug_locks))
3037                 return 0;
3038 #endif
3039         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3040                 debug_locks_off();
3041                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
3042                 printk("turning off the locking correctness validator.\n");
3043                 dump_stack();
3044                 return 0;
3045         }
3046
3047         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3048                 max_lockdep_depth = curr->lockdep_depth;
3049
3050         return 1;
3051 }
3052
3053 static int
3054 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3055                            unsigned long ip)
3056 {
3057         if (!debug_locks_off())
3058                 return 0;
3059         if (debug_locks_silent)
3060                 return 0;
3061
3062         printk("\n=====================================\n");
3063         printk(  "[ BUG: bad unlock balance detected! ]\n");
3064         printk(  "-------------------------------------\n");
3065         printk("%s/%d is trying to release lock (",
3066                 curr->comm, task_pid_nr(curr));
3067         print_lockdep_cache(lock);
3068         printk(") at:\n");
3069         print_ip_sym(ip);
3070         printk("but there are no more locks to release!\n");
3071         printk("\nother info that might help us debug this:\n");
3072         lockdep_print_held_locks(curr);
3073
3074         printk("\nstack backtrace:\n");
3075         dump_stack();
3076
3077         return 0;
3078 }
3079
3080 /*
3081  * Common debugging checks for both nested and non-nested unlock:
3082  */
3083 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3084                         unsigned long ip)
3085 {
3086         if (unlikely(!debug_locks))
3087                 return 0;
3088         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3089                 return 0;
3090
3091         if (curr->lockdep_depth <= 0)
3092                 return print_unlock_inbalance_bug(curr, lock, ip);
3093
3094         return 1;
3095 }
3096
3097 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3098 {
3099         if (hlock->instance == lock)
3100                 return 1;
3101
3102         if (hlock->references) {
3103                 struct lock_class *class = lock->class_cache[0];
3104
3105                 if (!class)
3106                         class = look_up_lock_class(lock, 0);
3107
3108                 if (DEBUG_LOCKS_WARN_ON(!class))
3109                         return 0;
3110
3111                 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3112                         return 0;
3113
3114                 if (hlock->class_idx == class - lock_classes + 1)
3115                         return 1;
3116         }
3117
3118         return 0;
3119 }
3120
3121 static int
3122 __lock_set_class(struct lockdep_map *lock, const char *name,
3123                  struct lock_class_key *key, unsigned int subclass,
3124                  unsigned long ip)
3125 {
3126         struct task_struct *curr = current;
3127         struct held_lock *hlock, *prev_hlock;
3128         struct lock_class *class;
3129         unsigned int depth;
3130         int i;
3131
3132         depth = curr->lockdep_depth;
3133         if (DEBUG_LOCKS_WARN_ON(!depth))
3134                 return 0;
3135
3136         prev_hlock = NULL;
3137         for (i = depth-1; i >= 0; i--) {
3138                 hlock = curr->held_locks + i;
3139                 /*
3140                  * We must not cross into another context:
3141                  */
3142                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3143                         break;
3144                 if (match_held_lock(hlock, lock))
3145                         goto found_it;
3146                 prev_hlock = hlock;
3147         }
3148         return print_unlock_inbalance_bug(curr, lock, ip);
3149
3150 found_it:
3151         lockdep_init_map(lock, name, key, 0);
3152         class = register_lock_class(lock, subclass, 0);
3153         hlock->class_idx = class - lock_classes + 1;
3154
3155         curr->lockdep_depth = i;
3156         curr->curr_chain_key = hlock->prev_chain_key;
3157
3158         for (; i < depth; i++) {
3159                 hlock = curr->held_locks + i;
3160                 if (!__lock_acquire(hlock->instance,
3161                         hlock_class(hlock)->subclass, hlock->trylock,
3162                                 hlock->read, hlock->check, hlock->hardirqs_off,
3163                                 hlock->nest_lock, hlock->acquire_ip,
3164                                 hlock->references))
3165                         return 0;
3166         }
3167
3168         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3169                 return 0;
3170         return 1;
3171 }
3172
3173 /*
3174  * Remove the lock to the list of currently held locks in a
3175  * potentially non-nested (out of order) manner. This is a
3176  * relatively rare operation, as all the unlock APIs default
3177  * to nested mode (which uses lock_release()):
3178  */
3179 static int
3180 lock_release_non_nested(struct task_struct *curr,
3181                         struct lockdep_map *lock, unsigned long ip)
3182 {
3183         struct held_lock *hlock, *prev_hlock;
3184         unsigned int depth;
3185         int i;
3186
3187         /*
3188          * Check whether the lock exists in the current stack
3189          * of held locks:
3190          */
3191         depth = curr->lockdep_depth;
3192         if (DEBUG_LOCKS_WARN_ON(!depth))
3193                 return 0;
3194
3195         prev_hlock = NULL;
3196         for (i = depth-1; i >= 0; i--) {
3197                 hlock = curr->held_locks + i;
3198                 /*
3199                  * We must not cross into another context:
3200                  */
3201                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3202                         break;
3203                 if (match_held_lock(hlock, lock))
3204                         goto found_it;
3205                 prev_hlock = hlock;
3206         }
3207         return print_unlock_inbalance_bug(curr, lock, ip);
3208
3209 found_it:
3210         if (hlock->instance == lock)
3211                 lock_release_holdtime(hlock);
3212
3213         if (hlock->references) {
3214                 hlock->references--;
3215                 if (hlock->references) {
3216                         /*
3217                          * We had, and after removing one, still have
3218                          * references, the current lock stack is still
3219                          * valid. We're done!
3220                          */
3221                         return 1;
3222                 }
3223         }
3224
3225         /*
3226          * We have the right lock to unlock, 'hlock' points to it.
3227          * Now we remove it from the stack, and add back the other
3228          * entries (if any), recalculating the hash along the way:
3229          */
3230
3231         curr->lockdep_depth = i;
3232         curr->curr_chain_key = hlock->prev_chain_key;
3233
3234         for (i++; i < depth; i++) {
3235                 hlock = curr->held_locks + i;
3236                 if (!__lock_acquire(hlock->instance,
3237                         hlock_class(hlock)->subclass, hlock->trylock,
3238                                 hlock->read, hlock->check, hlock->hardirqs_off,
3239                                 hlock->nest_lock, hlock->acquire_ip,
3240                                 hlock->references))
3241                         return 0;
3242         }
3243
3244         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3245                 return 0;
3246         return 1;
3247 }
3248
3249 /*
3250  * Remove the lock to the list of currently held locks - this gets
3251  * called on mutex_unlock()/spin_unlock*() (or on a failed
3252  * mutex_lock_interruptible()). This is done for unlocks that nest
3253  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3254  */
3255 static int lock_release_nested(struct task_struct *curr,
3256                                struct lockdep_map *lock, unsigned long ip)
3257 {
3258         struct held_lock *hlock;
3259         unsigned int depth;
3260
3261         /*
3262          * Pop off the top of the lock stack:
3263          */
3264         depth = curr->lockdep_depth - 1;
3265         hlock = curr->held_locks + depth;
3266
3267         /*
3268          * Is the unlock non-nested:
3269          */
3270         if (hlock->instance != lock || hlock->references)
3271                 return lock_release_non_nested(curr, lock, ip);
3272         curr->lockdep_depth--;
3273
3274         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3275                 return 0;
3276
3277         curr->curr_chain_key = hlock->prev_chain_key;
3278
3279         lock_release_holdtime(hlock);
3280
3281 #ifdef CONFIG_DEBUG_LOCKDEP
3282         hlock->prev_chain_key = 0;
3283         hlock->class_idx = 0;
3284         hlock->acquire_ip = 0;
3285         hlock->irq_context = 0;
3286 #endif
3287         return 1;
3288 }
3289
3290 /*
3291  * Remove the lock to the list of currently held locks - this gets
3292  * called on mutex_unlock()/spin_unlock*() (or on a failed
3293  * mutex_lock_interruptible()). This is done for unlocks that nest
3294  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3295  */
3296 static void
3297 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3298 {
3299         struct task_struct *curr = current;
3300
3301         if (!check_unlock(curr, lock, ip))
3302                 return;
3303
3304         if (nested) {
3305                 if (!lock_release_nested(curr, lock, ip))
3306                         return;
3307         } else {
3308                 if (!lock_release_non_nested(curr, lock, ip))
3309                         return;
3310         }
3311
3312         check_chain_key(curr);
3313 }
3314
3315 static int __lock_is_held(struct lockdep_map *lock)
3316 {
3317         struct task_struct *curr = current;
3318         int i;
3319
3320         for (i = 0; i < curr->lockdep_depth; i++) {
3321                 struct held_lock *hlock = curr->held_locks + i;
3322
3323                 if (match_held_lock(hlock, lock))
3324                         return 1;
3325         }
3326
3327         return 0;
3328 }
3329
3330 /*
3331  * Check whether we follow the irq-flags state precisely:
3332  */
3333 static void check_flags(unsigned long flags)
3334 {
3335 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3336     defined(CONFIG_TRACE_IRQFLAGS)
3337         if (!debug_locks)
3338                 return;
3339
3340         if (irqs_disabled_flags(flags)) {
3341                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3342                         printk("possible reason: unannotated irqs-off.\n");
3343                 }
3344         } else {
3345                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3346                         printk("possible reason: unannotated irqs-on.\n");
3347                 }
3348         }
3349
3350         /*
3351          * We dont accurately track softirq state in e.g.
3352          * hardirq contexts (such as on 4KSTACKS), so only
3353          * check if not in hardirq contexts:
3354          */
3355         if (!hardirq_count()) {
3356                 if (softirq_count())
3357                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3358                 else
3359                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3360         }
3361
3362         if (!debug_locks)
3363                 print_irqtrace_events(current);
3364 #endif
3365 }
3366
3367 void lock_set_class(struct lockdep_map *lock, const char *name,
3368                     struct lock_class_key *key, unsigned int subclass,
3369                     unsigned long ip)
3370 {
3371         unsigned long flags;
3372
3373         if (unlikely(current->lockdep_recursion))
3374                 return;
3375
3376         raw_local_irq_save(flags);
3377         current->lockdep_recursion = 1;
3378         check_flags(flags);
3379         if (__lock_set_class(lock, name, key, subclass, ip))
3380                 check_chain_key(current);
3381         current->lockdep_recursion = 0;
3382         raw_local_irq_restore(flags);
3383 }
3384 EXPORT_SYMBOL_GPL(lock_set_class);
3385
3386 /*
3387  * We are not always called with irqs disabled - do that here,
3388  * and also avoid lockdep recursion:
3389  */
3390 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3391                           int trylock, int read, int check,
3392                           struct lockdep_map *nest_lock, unsigned long ip)
3393 {
3394         unsigned long flags;
3395
3396         if (unlikely(current->lockdep_recursion))
3397                 return;
3398
3399         raw_local_irq_save(flags);
3400         check_flags(flags);
3401
3402         current->lockdep_recursion = 1;
3403         trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3404         __lock_acquire(lock, subclass, trylock, read, check,
3405                        irqs_disabled_flags(flags), nest_lock, ip, 0);
3406         current->lockdep_recursion = 0;
3407         raw_local_irq_restore(flags);
3408 }
3409 EXPORT_SYMBOL_GPL(lock_acquire);
3410
3411 void lock_release(struct lockdep_map *lock, int nested,
3412                           unsigned long ip)
3413 {
3414         unsigned long flags;
3415
3416         if (unlikely(current->lockdep_recursion))
3417                 return;
3418
3419         raw_local_irq_save(flags);
3420         check_flags(flags);
3421         current->lockdep_recursion = 1;
3422         trace_lock_release(lock, ip);
3423         __lock_release(lock, nested, ip);
3424         current->lockdep_recursion = 0;
3425         raw_local_irq_restore(flags);
3426 }
3427 EXPORT_SYMBOL_GPL(lock_release);
3428
3429 int lock_is_held(struct lockdep_map *lock)
3430 {
3431         unsigned long flags;
3432         int ret = 0;
3433
3434         if (unlikely(current->lockdep_recursion))
3435                 return ret;
3436
3437         raw_local_irq_save(flags);
3438         check_flags(flags);
3439
3440         current->lockdep_recursion = 1;
3441         ret = __lock_is_held(lock);
3442         current->lockdep_recursion = 0;
3443         raw_local_irq_restore(flags);
3444
3445         return ret;
3446 }
3447 EXPORT_SYMBOL_GPL(lock_is_held);
3448
3449 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3450 {
3451         current->lockdep_reclaim_gfp = gfp_mask;
3452 }
3453
3454 void lockdep_clear_current_reclaim_state(void)
3455 {
3456         current->lockdep_reclaim_gfp = 0;
3457 }
3458
3459 #ifdef CONFIG_LOCK_STAT
3460 static int
3461 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3462                            unsigned long ip)
3463 {
3464         if (!debug_locks_off())
3465                 return 0;
3466         if (debug_locks_silent)
3467                 return 0;
3468
3469         printk("\n=================================\n");
3470         printk(  "[ BUG: bad contention detected! ]\n");
3471         printk(  "---------------------------------\n");
3472         printk("%s/%d is trying to contend lock (",
3473                 curr->comm, task_pid_nr(curr));
3474         print_lockdep_cache(lock);
3475         printk(") at:\n");
3476         print_ip_sym(ip);
3477         printk("but there are no locks held!\n");
3478         printk("\nother info that might help us debug this:\n");
3479         lockdep_print_held_locks(curr);
3480
3481         printk("\nstack backtrace:\n");
3482         dump_stack();
3483
3484         return 0;
3485 }
3486
3487 static void
3488 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3489 {
3490         struct task_struct *curr = current;
3491         struct held_lock *hlock, *prev_hlock;
3492         struct lock_class_stats *stats;
3493         unsigned int depth;
3494         int i, contention_point, contending_point;
3495
3496         depth = curr->lockdep_depth;
3497         if (DEBUG_LOCKS_WARN_ON(!depth))
3498                 return;
3499
3500         prev_hlock = NULL;
3501         for (i = depth-1; i >= 0; i--) {
3502                 hlock = curr->held_locks + i;
3503                 /*
3504                  * We must not cross into another context:
3505                  */
3506                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3507                         break;
3508                 if (match_held_lock(hlock, lock))
3509                         goto found_it;
3510                 prev_hlock = hlock;
3511         }
3512         print_lock_contention_bug(curr, lock, ip);
3513         return;
3514
3515 found_it:
3516         if (hlock->instance != lock)
3517                 return;
3518
3519         hlock->waittime_stamp = lockstat_clock();
3520
3521         contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3522         contending_point = lock_point(hlock_class(hlock)->contending_point,
3523                                       lock->ip);
3524
3525         stats = get_lock_stats(hlock_class(hlock));
3526         if (contention_point < LOCKSTAT_POINTS)
3527                 stats->contention_point[contention_point]++;
3528         if (contending_point < LOCKSTAT_POINTS)
3529                 stats->contending_point[contending_point]++;
3530         if (lock->cpu != smp_processor_id())
3531                 stats->bounces[bounce_contended + !!hlock->read]++;
3532         put_lock_stats(stats);
3533 }
3534
3535 static void
3536 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3537 {
3538         struct task_struct *curr = current;
3539         struct held_lock *hlock, *prev_hlock;
3540         struct lock_class_stats *stats;
3541         unsigned int depth;
3542         u64 now, waittime = 0;
3543         int i, cpu;
3544
3545         depth = curr->lockdep_depth;
3546         if (DEBUG_LOCKS_WARN_ON(!depth))
3547                 return;
3548
3549         prev_hlock = NULL;
3550         for (i = depth-1; i >= 0; i--) {
3551                 hlock = curr->held_locks + i;
3552                 /*
3553                  * We must not cross into another context:
3554                  */
3555                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3556                         break;
3557                 if (match_held_lock(hlock, lock))
3558                         goto found_it;
3559                 prev_hlock = hlock;
3560         }
3561         print_lock_contention_bug(curr, lock, _RET_IP_);
3562         return;
3563
3564 found_it:
3565         if (hlock->instance != lock)
3566                 return;
3567
3568         cpu = smp_processor_id();
3569         if (hlock->waittime_stamp) {
3570                 now = lockstat_clock();
3571                 waittime = now - hlock->waittime_stamp;
3572                 hlock->holdtime_stamp = now;
3573         }
3574
3575         trace_lock_acquired(lock, ip);
3576
3577         stats = get_lock_stats(hlock_class(hlock));
3578         if (waittime) {
3579                 if (hlock->read)
3580                         lock_time_inc(&stats->read_waittime, waittime);
3581                 else
3582                         lock_time_inc(&stats->write_waittime, waittime);
3583         }
3584         if (lock->cpu != cpu)
3585                 stats->bounces[bounce_acquired + !!hlock->read]++;
3586         put_lock_stats(stats);
3587
3588         lock->cpu = cpu;
3589         lock->ip = ip;
3590 }
3591
3592 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3593 {
3594         unsigned long flags;
3595
3596         if (unlikely(!lock_stat))
3597                 return;
3598
3599         if (unlikely(current->lockdep_recursion))
3600                 return;
3601
3602         raw_local_irq_save(flags);
3603         check_flags(flags);
3604         current->lockdep_recursion = 1;
3605         trace_lock_contended(lock, ip);
3606         __lock_contended(lock, ip);
3607         current->lockdep_recursion = 0;
3608         raw_local_irq_restore(flags);
3609 }
3610 EXPORT_SYMBOL_GPL(lock_contended);
3611
3612 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3613 {
3614         unsigned long flags;
3615
3616         if (unlikely(!lock_stat))
3617                 return;
3618
3619         if (unlikely(current->lockdep_recursion))
3620                 return;
3621
3622         raw_local_irq_save(flags);
3623         check_flags(flags);
3624         current->lockdep_recursion = 1;
3625         __lock_acquired(lock, ip);
3626         current->lockdep_recursion = 0;
3627         raw_local_irq_restore(flags);
3628 }
3629 EXPORT_SYMBOL_GPL(lock_acquired);
3630 #endif
3631
3632 /*
3633  * Used by the testsuite, sanitize the validator state
3634  * after a simulated failure:
3635  */
3636
3637 void lockdep_reset(void)
3638 {
3639         unsigned long flags;
3640         int i;
3641
3642         raw_local_irq_save(flags);
3643         current->curr_chain_key = 0;
3644         current->lockdep_depth = 0;
3645         current->lockdep_recursion = 0;
3646         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3647         nr_hardirq_chains = 0;
3648         nr_softirq_chains = 0;
3649         nr_process_chains = 0;
3650         debug_locks = 1;
3651         for (i = 0; i < CHAINHASH_SIZE; i++)
3652                 INIT_LIST_HEAD(chainhash_table + i);
3653         raw_local_irq_restore(flags);
3654 }
3655
3656 static void zap_class(struct lock_class *class)
3657 {
3658         int i;
3659
3660         /*
3661          * Remove all dependencies this lock is
3662          * involved in:
3663          */
3664         for (i = 0; i < nr_list_entries; i++) {
3665                 if (list_entries[i].class == class)
3666                         list_del_rcu(&list_entries[i].entry);
3667         }
3668         /*
3669          * Unhash the class and remove it from the all_lock_classes list:
3670          */
3671         list_del_rcu(&class->hash_entry);
3672         list_del_rcu(&class->lock_entry);
3673
3674         class->key = NULL;
3675 }
3676
3677 static inline int within(const void *addr, void *start, unsigned long size)
3678 {
3679         return addr >= start && addr < start + size;
3680 }
3681
3682 void lockdep_free_key_range(void *start, unsigned long size)
3683 {
3684         struct lock_class *class, *next;
3685         struct list_head *head;
3686         unsigned long flags;
3687         int i;
3688         int locked;
3689
3690         raw_local_irq_save(flags);
3691         locked = graph_lock();
3692
3693         /*
3694          * Unhash all classes that were created by this module:
3695          */
3696         for (i = 0; i < CLASSHASH_SIZE; i++) {
3697                 head = classhash_table + i;
3698                 if (list_empty(head))
3699                         continue;
3700                 list_for_each_entry_safe(class, next, head, hash_entry) {
3701                         if (within(class->key, start, size))
3702                                 zap_class(class);
3703                         else if (within(class->name, start, size))
3704                                 zap_class(class);
3705                 }
3706         }
3707
3708         if (locked)
3709                 graph_unlock();
3710         raw_local_irq_restore(flags);
3711 }
3712
3713 void lockdep_reset_lock(struct lockdep_map *lock)
3714 {
3715         struct lock_class *class, *next;
3716         struct list_head *head;
3717         unsigned long flags;
3718         int i, j;
3719         int locked;
3720
3721         raw_local_irq_save(flags);
3722
3723         /*
3724          * Remove all classes this lock might have:
3725          */
3726         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3727                 /*
3728                  * If the class exists we look it up and zap it:
3729                  */
3730                 class = look_up_lock_class(lock, j);
3731                 if (class)
3732                         zap_class(class);
3733         }
3734         /*
3735          * Debug check: in the end all mapped classes should
3736          * be gone.
3737          */
3738         locked = graph_lock();
3739         for (i = 0; i < CLASSHASH_SIZE; i++) {
3740                 head = classhash_table + i;
3741                 if (list_empty(head))
3742                         continue;
3743                 list_for_each_entry_safe(class, next, head, hash_entry) {
3744                         int match = 0;
3745
3746                         for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3747                                 match |= class == lock->class_cache[j];
3748
3749                         if (unlikely(match)) {
3750                                 if (debug_locks_off_graph_unlock())
3751                                         WARN_ON(1);
3752                                 goto out_restore;
3753                         }
3754                 }
3755         }
3756         if (locked)
3757                 graph_unlock();
3758
3759 out_restore:
3760         raw_local_irq_restore(flags);
3761 }
3762
3763 void lockdep_init(void)
3764 {
3765         int i;
3766
3767         /*
3768          * Some architectures have their own start_kernel()
3769          * code which calls lockdep_init(), while we also
3770          * call lockdep_init() from the start_kernel() itself,
3771          * and we want to initialize the hashes only once:
3772          */
3773         if (lockdep_initialized)
3774                 return;
3775
3776         for (i = 0; i < CLASSHASH_SIZE; i++)
3777                 INIT_LIST_HEAD(classhash_table + i);
3778
3779         for (i = 0; i < CHAINHASH_SIZE; i++)
3780                 INIT_LIST_HEAD(chainhash_table + i);
3781
3782         lockdep_initialized = 1;
3783 }
3784
3785 void __init lockdep_info(void)
3786 {
3787         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3788
3789         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3790         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3791         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3792         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3793         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3794         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3795         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3796
3797         printk(" memory used by lock dependency info: %lu kB\n",
3798                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3799                 sizeof(struct list_head) * CLASSHASH_SIZE +
3800                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3801                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3802                 sizeof(struct list_head) * CHAINHASH_SIZE
3803 #ifdef CONFIG_PROVE_LOCKING
3804                 + sizeof(struct circular_queue)
3805 #endif
3806                 ) / 1024
3807                 );
3808
3809         printk(" per task-struct memory footprint: %lu bytes\n",
3810                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3811
3812 #ifdef CONFIG_DEBUG_LOCKDEP
3813         if (lockdep_init_error) {
3814                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3815                 printk("Call stack leading to lockdep invocation was:\n");
3816                 print_stack_trace(&lockdep_init_trace, 0);
3817         }
3818 #endif
3819 }
3820
3821 static void
3822 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3823                      const void *mem_to, struct held_lock *hlock)
3824 {
3825         if (!debug_locks_off())
3826                 return;
3827         if (debug_locks_silent)
3828                 return;
3829
3830         printk("\n=========================\n");
3831         printk(  "[ BUG: held lock freed! ]\n");
3832         printk(  "-------------------------\n");
3833         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3834                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3835         print_lock(hlock);
3836         lockdep_print_held_locks(curr);
3837
3838         printk("\nstack backtrace:\n");
3839         dump_stack();
3840 }
3841
3842 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3843                                 const void* lock_from, unsigned long lock_len)
3844 {
3845         return lock_from + lock_len <= mem_from ||
3846                 mem_from + mem_len <= lock_from;
3847 }
3848
3849 /*
3850  * Called when kernel memory is freed (or unmapped), or if a lock
3851  * is destroyed or reinitialized - this code checks whether there is
3852  * any held lock in the memory range of <from> to <to>:
3853  */
3854 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3855 {
3856         struct task_struct *curr = current;
3857         struct held_lock *hlock;
3858         unsigned long flags;
3859         int i;
3860
3861         if (unlikely(!debug_locks))
3862                 return;
3863
3864         local_irq_save(flags);
3865         for (i = 0; i < curr->lockdep_depth; i++) {
3866                 hlock = curr->held_locks + i;
3867
3868                 if (not_in_range(mem_from, mem_len, hlock->instance,
3869                                         sizeof(*hlock->instance)))
3870                         continue;
3871
3872                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3873                 break;
3874         }
3875         local_irq_restore(flags);
3876 }
3877 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3878
3879 static void print_held_locks_bug(struct task_struct *curr)
3880 {
3881         if (!debug_locks_off())
3882                 return;
3883         if (debug_locks_silent)
3884                 return;
3885
3886         printk("\n=====================================\n");
3887         printk(  "[ BUG: lock held at task exit time! ]\n");
3888         printk(  "-------------------------------------\n");
3889         printk("%s/%d is exiting with locks still held!\n",
3890                 curr->comm, task_pid_nr(curr));
3891         lockdep_print_held_locks(curr);
3892
3893         printk("\nstack backtrace:\n");
3894         dump_stack();
3895 }
3896
3897 void debug_check_no_locks_held(struct task_struct *task)
3898 {
3899         if (unlikely(task->lockdep_depth > 0))
3900                 print_held_locks_bug(task);
3901 }
3902
3903 void debug_show_all_locks(void)
3904 {
3905         struct task_struct *g, *p;
3906         int count = 10;
3907         int unlock = 1;
3908
3909         if (unlikely(!debug_locks)) {
3910                 printk("INFO: lockdep is turned off.\n");
3911                 return;
3912         }
3913         printk("\nShowing all locks held in the system:\n");
3914
3915         /*
3916          * Here we try to get the tasklist_lock as hard as possible,
3917          * if not successful after 2 seconds we ignore it (but keep
3918          * trying). This is to enable a debug printout even if a
3919          * tasklist_lock-holding task deadlocks or crashes.
3920          */
3921 retry:
3922         if (!read_trylock(&tasklist_lock)) {
3923                 if (count == 10)
3924                         printk("hm, tasklist_lock locked, retrying... ");
3925                 if (count) {
3926                         count--;
3927                         printk(" #%d", 10-count);
3928                         mdelay(200);
3929                         goto retry;
3930                 }
3931                 printk(" ignoring it.\n");
3932                 unlock = 0;
3933         } else {
3934                 if (count != 10)
3935                         printk(KERN_CONT " locked it.\n");
3936         }
3937
3938         do_each_thread(g, p) {
3939                 /*
3940                  * It's not reliable to print a task's held locks
3941                  * if it's not sleeping (or if it's not the current
3942                  * task):
3943                  */
3944                 if (p->state == TASK_RUNNING && p != current)
3945                         continue;
3946                 if (p->lockdep_depth)
3947                         lockdep_print_held_locks(p);
3948                 if (!unlock)
3949                         if (read_trylock(&tasklist_lock))
3950                                 unlock = 1;
3951         } while_each_thread(g, p);
3952
3953         printk("\n");
3954         printk("=============================================\n\n");
3955
3956         if (unlock)
3957                 read_unlock(&tasklist_lock);
3958 }
3959 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3960
3961 /*
3962  * Careful: only use this function if you are sure that
3963  * the task cannot run in parallel!
3964  */
3965 void debug_show_held_locks(struct task_struct *task)
3966 {
3967         if (unlikely(!debug_locks)) {
3968                 printk("INFO: lockdep is turned off.\n");
3969                 return;
3970         }
3971         lockdep_print_held_locks(task);
3972 }
3973 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3974
3975 void lockdep_sys_exit(void)
3976 {
3977         struct task_struct *curr = current;
3978
3979         if (unlikely(curr->lockdep_depth)) {
3980                 if (!debug_locks_off())
3981                         return;
3982                 printk("\n================================================\n");
3983                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3984                 printk(  "------------------------------------------------\n");
3985                 printk("%s/%d is leaving the kernel with locks still held!\n",
3986                                 curr->comm, curr->pid);
3987                 lockdep_print_held_locks(curr);
3988         }
3989 }
3990
3991 void lockdep_rcu_dereference(const char *file, const int line)
3992 {
3993         struct task_struct *curr = current;
3994
3995 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
3996         if (!debug_locks_off())
3997                 return;
3998 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
3999         /* Note: the following can be executed concurrently, so be careful. */
4000         printk("\n===================================================\n");
4001         printk(  "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
4002         printk(  "---------------------------------------------------\n");
4003         printk("%s:%d invoked rcu_dereference_check() without protection!\n",
4004                         file, line);
4005         printk("\nother info that might help us debug this:\n\n");
4006         printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
4007         lockdep_print_held_locks(curr);
4008         printk("\nstack backtrace:\n");
4009         dump_stack();
4010 }
4011 EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);