lockdep, kmemcheck: Annotate ->lock in lockdep_init_map()
[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 #include <linux/kmemcheck.h>
48
49 #include <asm/sections.h>
50
51 #include "lockdep_internals.h"
52
53 #define CREATE_TRACE_POINTS
54 #include <trace/events/lock.h>
55
56 #ifdef CONFIG_PROVE_LOCKING
57 int prove_locking = 1;
58 module_param(prove_locking, int, 0644);
59 #else
60 #define prove_locking 0
61 #endif
62
63 #ifdef CONFIG_LOCK_STAT
64 int lock_stat = 1;
65 module_param(lock_stat, int, 0644);
66 #else
67 #define lock_stat 0
68 #endif
69
70 /*
71  * lockdep_lock: protects the lockdep graph, the hashes and the
72  *               class/list/hash allocators.
73  *
74  * This is one of the rare exceptions where it's justified
75  * to use a raw spinlock - we really dont want the spinlock
76  * code to recurse back into the lockdep code...
77  */
78 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
79
80 static int graph_lock(void)
81 {
82         arch_spin_lock(&lockdep_lock);
83         /*
84          * Make sure that if another CPU detected a bug while
85          * walking the graph we dont change it (while the other
86          * CPU is busy printing out stuff with the graph lock
87          * dropped already)
88          */
89         if (!debug_locks) {
90                 arch_spin_unlock(&lockdep_lock);
91                 return 0;
92         }
93         /* prevent any recursions within lockdep from causing deadlocks */
94         current->lockdep_recursion++;
95         return 1;
96 }
97
98 static inline int graph_unlock(void)
99 {
100         if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
101                 /*
102                  * The lockdep graph lock isn't locked while we expect it to
103                  * be, we're confused now, bye!
104                  */
105                 return DEBUG_LOCKS_WARN_ON(1);
106         }
107
108         current->lockdep_recursion--;
109         arch_spin_unlock(&lockdep_lock);
110         return 0;
111 }
112
113 /*
114  * Turn lock debugging off and return with 0 if it was off already,
115  * and also release the graph lock:
116  */
117 static inline int debug_locks_off_graph_unlock(void)
118 {
119         int ret = debug_locks_off();
120
121         arch_spin_unlock(&lockdep_lock);
122
123         return ret;
124 }
125
126 static int lockdep_initialized;
127
128 unsigned long nr_list_entries;
129 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
130
131 /*
132  * All data structures here are protected by the global debug_lock.
133  *
134  * Mutex key structs only get allocated, once during bootup, and never
135  * get freed - this significantly simplifies the debugging code.
136  */
137 unsigned long nr_lock_classes;
138 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
139
140 static inline struct lock_class *hlock_class(struct held_lock *hlock)
141 {
142         if (!hlock->class_idx) {
143                 /*
144                  * Someone passed in garbage, we give up.
145                  */
146                 DEBUG_LOCKS_WARN_ON(1);
147                 return NULL;
148         }
149         return lock_classes + hlock->class_idx - 1;
150 }
151
152 #ifdef CONFIG_LOCK_STAT
153 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
154                       cpu_lock_stats);
155
156 static inline u64 lockstat_clock(void)
157 {
158         return local_clock();
159 }
160
161 static int lock_point(unsigned long points[], unsigned long ip)
162 {
163         int i;
164
165         for (i = 0; i < LOCKSTAT_POINTS; i++) {
166                 if (points[i] == 0) {
167                         points[i] = ip;
168                         break;
169                 }
170                 if (points[i] == ip)
171                         break;
172         }
173
174         return i;
175 }
176
177 static void lock_time_inc(struct lock_time *lt, u64 time)
178 {
179         if (time > lt->max)
180                 lt->max = time;
181
182         if (time < lt->min || !lt->nr)
183                 lt->min = time;
184
185         lt->total += time;
186         lt->nr++;
187 }
188
189 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
190 {
191         if (!src->nr)
192                 return;
193
194         if (src->max > dst->max)
195                 dst->max = src->max;
196
197         if (src->min < dst->min || !dst->nr)
198                 dst->min = src->min;
199
200         dst->total += src->total;
201         dst->nr += src->nr;
202 }
203
204 struct lock_class_stats lock_stats(struct lock_class *class)
205 {
206         struct lock_class_stats stats;
207         int cpu, i;
208
209         memset(&stats, 0, sizeof(struct lock_class_stats));
210         for_each_possible_cpu(cpu) {
211                 struct lock_class_stats *pcs =
212                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
213
214                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
215                         stats.contention_point[i] += pcs->contention_point[i];
216
217                 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
218                         stats.contending_point[i] += pcs->contending_point[i];
219
220                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
221                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
222
223                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
224                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
225
226                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
227                         stats.bounces[i] += pcs->bounces[i];
228         }
229
230         return stats;
231 }
232
233 void clear_lock_stats(struct lock_class *class)
234 {
235         int cpu;
236
237         for_each_possible_cpu(cpu) {
238                 struct lock_class_stats *cpu_stats =
239                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
240
241                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
242         }
243         memset(class->contention_point, 0, sizeof(class->contention_point));
244         memset(class->contending_point, 0, sizeof(class->contending_point));
245 }
246
247 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
248 {
249         return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
250 }
251
252 static void put_lock_stats(struct lock_class_stats *stats)
253 {
254         put_cpu_var(cpu_lock_stats);
255 }
256
257 static void lock_release_holdtime(struct held_lock *hlock)
258 {
259         struct lock_class_stats *stats;
260         u64 holdtime;
261
262         if (!lock_stat)
263                 return;
264
265         holdtime = lockstat_clock() - hlock->holdtime_stamp;
266
267         stats = get_lock_stats(hlock_class(hlock));
268         if (hlock->read)
269                 lock_time_inc(&stats->read_holdtime, holdtime);
270         else
271                 lock_time_inc(&stats->write_holdtime, holdtime);
272         put_lock_stats(stats);
273 }
274 #else
275 static inline void lock_release_holdtime(struct held_lock *hlock)
276 {
277 }
278 #endif
279
280 /*
281  * We keep a global list of all lock classes. The list only grows,
282  * never shrinks. The list is only accessed with the lockdep
283  * spinlock lock held.
284  */
285 LIST_HEAD(all_lock_classes);
286
287 /*
288  * The lockdep classes are in a hash-table as well, for fast lookup:
289  */
290 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
291 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
292 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
293 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
294
295 static struct list_head classhash_table[CLASSHASH_SIZE];
296
297 /*
298  * We put the lock dependency chains into a hash-table as well, to cache
299  * their existence:
300  */
301 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
302 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
303 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
304 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
305
306 static struct list_head chainhash_table[CHAINHASH_SIZE];
307
308 /*
309  * The hash key of the lock dependency chains is a hash itself too:
310  * it's a hash of all locks taken up to that lock, including that lock.
311  * It's a 64-bit hash, because it's important for the keys to be
312  * unique.
313  */
314 #define iterate_chain_key(key1, key2) \
315         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
316         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
317         (key2))
318
319 void lockdep_off(void)
320 {
321         current->lockdep_recursion++;
322 }
323 EXPORT_SYMBOL(lockdep_off);
324
325 void lockdep_on(void)
326 {
327         current->lockdep_recursion--;
328 }
329 EXPORT_SYMBOL(lockdep_on);
330
331 /*
332  * Debugging switches:
333  */
334
335 #define VERBOSE                 0
336 #define VERY_VERBOSE            0
337
338 #if VERBOSE
339 # define HARDIRQ_VERBOSE        1
340 # define SOFTIRQ_VERBOSE        1
341 # define RECLAIM_VERBOSE        1
342 #else
343 # define HARDIRQ_VERBOSE        0
344 # define SOFTIRQ_VERBOSE        0
345 # define RECLAIM_VERBOSE        0
346 #endif
347
348 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
349 /*
350  * Quick filtering for interesting events:
351  */
352 static int class_filter(struct lock_class *class)
353 {
354 #if 0
355         /* Example */
356         if (class->name_version == 1 &&
357                         !strcmp(class->name, "lockname"))
358                 return 1;
359         if (class->name_version == 1 &&
360                         !strcmp(class->name, "&struct->lockfield"))
361                 return 1;
362 #endif
363         /* Filter everything else. 1 would be to allow everything else */
364         return 0;
365 }
366 #endif
367
368 static int verbose(struct lock_class *class)
369 {
370 #if VERBOSE
371         return class_filter(class);
372 #endif
373         return 0;
374 }
375
376 /*
377  * Stack-trace: tightly packed array of stack backtrace
378  * addresses. Protected by the graph_lock.
379  */
380 unsigned long nr_stack_trace_entries;
381 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
382
383 static int save_trace(struct stack_trace *trace)
384 {
385         trace->nr_entries = 0;
386         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
387         trace->entries = stack_trace + nr_stack_trace_entries;
388
389         trace->skip = 3;
390
391         save_stack_trace(trace);
392
393         /*
394          * Some daft arches put -1 at the end to indicate its a full trace.
395          *
396          * <rant> this is buggy anyway, since it takes a whole extra entry so a
397          * complete trace that maxes out the entries provided will be reported
398          * as incomplete, friggin useless </rant>
399          */
400         if (trace->nr_entries != 0 &&
401             trace->entries[trace->nr_entries-1] == ULONG_MAX)
402                 trace->nr_entries--;
403
404         trace->max_entries = trace->nr_entries;
405
406         nr_stack_trace_entries += trace->nr_entries;
407
408         if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
409                 if (!debug_locks_off_graph_unlock())
410                         return 0;
411
412                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
413                 printk("turning off the locking correctness validator.\n");
414                 dump_stack();
415
416                 return 0;
417         }
418
419         return 1;
420 }
421
422 unsigned int nr_hardirq_chains;
423 unsigned int nr_softirq_chains;
424 unsigned int nr_process_chains;
425 unsigned int max_lockdep_depth;
426
427 #ifdef CONFIG_DEBUG_LOCKDEP
428 /*
429  * We cannot printk in early bootup code. Not even early_printk()
430  * might work. So we mark any initialization errors and printk
431  * about it later on, in lockdep_info().
432  */
433 static int lockdep_init_error;
434 static unsigned long lockdep_init_trace_data[20];
435 static struct stack_trace lockdep_init_trace = {
436         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
437         .entries = lockdep_init_trace_data,
438 };
439
440 /*
441  * Various lockdep statistics:
442  */
443 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
444 #endif
445
446 /*
447  * Locking printouts:
448  */
449
450 #define __USAGE(__STATE)                                                \
451         [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
452         [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
453         [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
454         [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
455
456 static const char *usage_str[] =
457 {
458 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
459 #include "lockdep_states.h"
460 #undef LOCKDEP_STATE
461         [LOCK_USED] = "INITIAL USE",
462 };
463
464 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
465 {
466         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
467 }
468
469 static inline unsigned long lock_flag(enum lock_usage_bit bit)
470 {
471         return 1UL << bit;
472 }
473
474 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
475 {
476         char c = '.';
477
478         if (class->usage_mask & lock_flag(bit + 2))
479                 c = '+';
480         if (class->usage_mask & lock_flag(bit)) {
481                 c = '-';
482                 if (class->usage_mask & lock_flag(bit + 2))
483                         c = '?';
484         }
485
486         return c;
487 }
488
489 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
490 {
491         int i = 0;
492
493 #define LOCKDEP_STATE(__STATE)                                          \
494         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
495         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
496 #include "lockdep_states.h"
497 #undef LOCKDEP_STATE
498
499         usage[i] = '\0';
500 }
501
502 static int __print_lock_name(struct lock_class *class)
503 {
504         char str[KSYM_NAME_LEN];
505         const char *name;
506
507         name = class->name;
508         if (!name)
509                 name = __get_key_name(class->key, str);
510
511         return printk("%s", name);
512 }
513
514 static void print_lock_name(struct lock_class *class)
515 {
516         char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
517         const char *name;
518
519         get_usage_chars(class, usage);
520
521         name = class->name;
522         if (!name) {
523                 name = __get_key_name(class->key, str);
524                 printk(" (%s", name);
525         } else {
526                 printk(" (%s", name);
527                 if (class->name_version > 1)
528                         printk("#%d", class->name_version);
529                 if (class->subclass)
530                         printk("/%d", class->subclass);
531         }
532         printk("){%s}", usage);
533 }
534
535 static void print_lockdep_cache(struct lockdep_map *lock)
536 {
537         const char *name;
538         char str[KSYM_NAME_LEN];
539
540         name = lock->name;
541         if (!name)
542                 name = __get_key_name(lock->key->subkeys, str);
543
544         printk("%s", name);
545 }
546
547 static void print_lock(struct held_lock *hlock)
548 {
549         print_lock_name(hlock_class(hlock));
550         printk(", at: ");
551         print_ip_sym(hlock->acquire_ip);
552 }
553
554 static void lockdep_print_held_locks(struct task_struct *curr)
555 {
556         int i, depth = curr->lockdep_depth;
557
558         if (!depth) {
559                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
560                 return;
561         }
562         printk("%d lock%s held by %s/%d:\n",
563                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
564
565         for (i = 0; i < depth; i++) {
566                 printk(" #%d: ", i);
567                 print_lock(curr->held_locks + i);
568         }
569 }
570
571 static void print_kernel_version(void)
572 {
573         printk("%s %.*s\n", init_utsname()->release,
574                 (int)strcspn(init_utsname()->version, " "),
575                 init_utsname()->version);
576 }
577
578 static int very_verbose(struct lock_class *class)
579 {
580 #if VERY_VERBOSE
581         return class_filter(class);
582 #endif
583         return 0;
584 }
585
586 /*
587  * Is this the address of a static object:
588  */
589 static int static_obj(void *obj)
590 {
591         unsigned long start = (unsigned long) &_stext,
592                       end   = (unsigned long) &_end,
593                       addr  = (unsigned long) obj;
594
595         /*
596          * static variable?
597          */
598         if ((addr >= start) && (addr < end))
599                 return 1;
600
601         if (arch_is_kernel_data(addr))
602                 return 1;
603
604         /*
605          * in-kernel percpu var?
606          */
607         if (is_kernel_percpu_address(addr))
608                 return 1;
609
610         /*
611          * module static or percpu var?
612          */
613         return is_module_address(addr) || is_module_percpu_address(addr);
614 }
615
616 /*
617  * To make lock name printouts unique, we calculate a unique
618  * class->name_version generation counter:
619  */
620 static int count_matching_names(struct lock_class *new_class)
621 {
622         struct lock_class *class;
623         int count = 0;
624
625         if (!new_class->name)
626                 return 0;
627
628         list_for_each_entry(class, &all_lock_classes, lock_entry) {
629                 if (new_class->key - new_class->subclass == class->key)
630                         return class->name_version;
631                 if (class->name && !strcmp(class->name, new_class->name))
632                         count = max(count, class->name_version);
633         }
634
635         return count + 1;
636 }
637
638 /*
639  * Register a lock's class in the hash-table, if the class is not present
640  * yet. Otherwise we look it up. We cache the result in the lock object
641  * itself, so actual lookup of the hash should be once per lock object.
642  */
643 static inline struct lock_class *
644 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
645 {
646         struct lockdep_subclass_key *key;
647         struct list_head *hash_head;
648         struct lock_class *class;
649
650 #ifdef CONFIG_DEBUG_LOCKDEP
651         /*
652          * If the architecture calls into lockdep before initializing
653          * the hashes then we'll warn about it later. (we cannot printk
654          * right now)
655          */
656         if (unlikely(!lockdep_initialized)) {
657                 lockdep_init();
658                 lockdep_init_error = 1;
659                 save_stack_trace(&lockdep_init_trace);
660         }
661 #endif
662
663         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
664                 debug_locks_off();
665                 printk(KERN_ERR
666                         "BUG: looking up invalid subclass: %u\n", subclass);
667                 printk(KERN_ERR
668                         "turning off the locking correctness validator.\n");
669                 dump_stack();
670                 return NULL;
671         }
672
673         /*
674          * Static locks do not have their class-keys yet - for them the key
675          * is the lock object itself:
676          */
677         if (unlikely(!lock->key))
678                 lock->key = (void *)lock;
679
680         /*
681          * NOTE: the class-key must be unique. For dynamic locks, a static
682          * lock_class_key variable is passed in through the mutex_init()
683          * (or spin_lock_init()) call - which acts as the key. For static
684          * locks we use the lock object itself as the key.
685          */
686         BUILD_BUG_ON(sizeof(struct lock_class_key) >
687                         sizeof(struct lockdep_map));
688
689         key = lock->key->subkeys + subclass;
690
691         hash_head = classhashentry(key);
692
693         /*
694          * We can walk the hash lockfree, because the hash only
695          * grows, and we are careful when adding entries to the end:
696          */
697         list_for_each_entry(class, hash_head, hash_entry) {
698                 if (class->key == key) {
699                         /*
700                          * Huh! same key, different name? Did someone trample
701                          * on some memory? We're most confused.
702                          */
703                         WARN_ON_ONCE(class->name != lock->name);
704                         return class;
705                 }
706         }
707
708         return NULL;
709 }
710
711 /*
712  * Register a lock's class in the hash-table, if the class is not present
713  * yet. Otherwise we look it up. We cache the result in the lock object
714  * itself, so actual lookup of the hash should be once per lock object.
715  */
716 static inline struct lock_class *
717 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
718 {
719         struct lockdep_subclass_key *key;
720         struct list_head *hash_head;
721         struct lock_class *class;
722         unsigned long flags;
723
724         class = look_up_lock_class(lock, subclass);
725         if (likely(class))
726                 return class;
727
728         /*
729          * Debug-check: all keys must be persistent!
730          */
731         if (!static_obj(lock->key)) {
732                 debug_locks_off();
733                 printk("INFO: trying to register non-static key.\n");
734                 printk("the code is fine but needs lockdep annotation.\n");
735                 printk("turning off the locking correctness validator.\n");
736                 dump_stack();
737
738                 return NULL;
739         }
740
741         key = lock->key->subkeys + subclass;
742         hash_head = classhashentry(key);
743
744         raw_local_irq_save(flags);
745         if (!graph_lock()) {
746                 raw_local_irq_restore(flags);
747                 return NULL;
748         }
749         /*
750          * We have to do the hash-walk again, to avoid races
751          * with another CPU:
752          */
753         list_for_each_entry(class, hash_head, hash_entry)
754                 if (class->key == key)
755                         goto out_unlock_set;
756         /*
757          * Allocate a new key from the static array, and add it to
758          * the hash:
759          */
760         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
761                 if (!debug_locks_off_graph_unlock()) {
762                         raw_local_irq_restore(flags);
763                         return NULL;
764                 }
765                 raw_local_irq_restore(flags);
766
767                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
768                 printk("turning off the locking correctness validator.\n");
769                 dump_stack();
770                 return NULL;
771         }
772         class = lock_classes + nr_lock_classes++;
773         debug_atomic_inc(nr_unused_locks);
774         class->key = key;
775         class->name = lock->name;
776         class->subclass = subclass;
777         INIT_LIST_HEAD(&class->lock_entry);
778         INIT_LIST_HEAD(&class->locks_before);
779         INIT_LIST_HEAD(&class->locks_after);
780         class->name_version = count_matching_names(class);
781         /*
782          * We use RCU's safe list-add method to make
783          * parallel walking of the hash-list safe:
784          */
785         list_add_tail_rcu(&class->hash_entry, hash_head);
786         /*
787          * Add it to the global list of classes:
788          */
789         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
790
791         if (verbose(class)) {
792                 graph_unlock();
793                 raw_local_irq_restore(flags);
794
795                 printk("\nnew class %p: %s", class->key, class->name);
796                 if (class->name_version > 1)
797                         printk("#%d", class->name_version);
798                 printk("\n");
799                 dump_stack();
800
801                 raw_local_irq_save(flags);
802                 if (!graph_lock()) {
803                         raw_local_irq_restore(flags);
804                         return NULL;
805                 }
806         }
807 out_unlock_set:
808         graph_unlock();
809         raw_local_irq_restore(flags);
810
811         if (!subclass || force)
812                 lock->class_cache[0] = class;
813         else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
814                 lock->class_cache[subclass] = class;
815
816         /*
817          * Hash collision, did we smoke some? We found a class with a matching
818          * hash but the subclass -- which is hashed in -- didn't match.
819          */
820         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
821                 return NULL;
822
823         return class;
824 }
825
826 #ifdef CONFIG_PROVE_LOCKING
827 /*
828  * Allocate a lockdep entry. (assumes the graph_lock held, returns
829  * with NULL on failure)
830  */
831 static struct lock_list *alloc_list_entry(void)
832 {
833         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
834                 if (!debug_locks_off_graph_unlock())
835                         return NULL;
836
837                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
838                 printk("turning off the locking correctness validator.\n");
839                 dump_stack();
840                 return NULL;
841         }
842         return list_entries + nr_list_entries++;
843 }
844
845 /*
846  * Add a new dependency to the head of the list:
847  */
848 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
849                             struct list_head *head, unsigned long ip,
850                             int distance, struct stack_trace *trace)
851 {
852         struct lock_list *entry;
853         /*
854          * Lock not present yet - get a new dependency struct and
855          * add it to the list:
856          */
857         entry = alloc_list_entry();
858         if (!entry)
859                 return 0;
860
861         entry->class = this;
862         entry->distance = distance;
863         entry->trace = *trace;
864         /*
865          * Since we never remove from the dependency list, the list can
866          * be walked lockless by other CPUs, it's only allocation
867          * that must be protected by the spinlock. But this also means
868          * we must make new entries visible only once writes to the
869          * entry become visible - hence the RCU op:
870          */
871         list_add_tail_rcu(&entry->entry, head);
872
873         return 1;
874 }
875
876 /*
877  * For good efficiency of modular, we use power of 2
878  */
879 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
880 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
881
882 /*
883  * The circular_queue and helpers is used to implement the
884  * breadth-first search(BFS)algorithem, by which we can build
885  * the shortest path from the next lock to be acquired to the
886  * previous held lock if there is a circular between them.
887  */
888 struct circular_queue {
889         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
890         unsigned int  front, rear;
891 };
892
893 static struct circular_queue lock_cq;
894
895 unsigned int max_bfs_queue_depth;
896
897 static unsigned int lockdep_dependency_gen_id;
898
899 static inline void __cq_init(struct circular_queue *cq)
900 {
901         cq->front = cq->rear = 0;
902         lockdep_dependency_gen_id++;
903 }
904
905 static inline int __cq_empty(struct circular_queue *cq)
906 {
907         return (cq->front == cq->rear);
908 }
909
910 static inline int __cq_full(struct circular_queue *cq)
911 {
912         return ((cq->rear + 1) & CQ_MASK) == cq->front;
913 }
914
915 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
916 {
917         if (__cq_full(cq))
918                 return -1;
919
920         cq->element[cq->rear] = elem;
921         cq->rear = (cq->rear + 1) & CQ_MASK;
922         return 0;
923 }
924
925 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
926 {
927         if (__cq_empty(cq))
928                 return -1;
929
930         *elem = cq->element[cq->front];
931         cq->front = (cq->front + 1) & CQ_MASK;
932         return 0;
933 }
934
935 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
936 {
937         return (cq->rear - cq->front) & CQ_MASK;
938 }
939
940 static inline void mark_lock_accessed(struct lock_list *lock,
941                                         struct lock_list *parent)
942 {
943         unsigned long nr;
944
945         nr = lock - list_entries;
946         WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
947         lock->parent = parent;
948         lock->class->dep_gen_id = lockdep_dependency_gen_id;
949 }
950
951 static inline unsigned long lock_accessed(struct lock_list *lock)
952 {
953         unsigned long nr;
954
955         nr = lock - list_entries;
956         WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
957         return lock->class->dep_gen_id == lockdep_dependency_gen_id;
958 }
959
960 static inline struct lock_list *get_lock_parent(struct lock_list *child)
961 {
962         return child->parent;
963 }
964
965 static inline int get_lock_depth(struct lock_list *child)
966 {
967         int depth = 0;
968         struct lock_list *parent;
969
970         while ((parent = get_lock_parent(child))) {
971                 child = parent;
972                 depth++;
973         }
974         return depth;
975 }
976
977 static int __bfs(struct lock_list *source_entry,
978                  void *data,
979                  int (*match)(struct lock_list *entry, void *data),
980                  struct lock_list **target_entry,
981                  int forward)
982 {
983         struct lock_list *entry;
984         struct list_head *head;
985         struct circular_queue *cq = &lock_cq;
986         int ret = 1;
987
988         if (match(source_entry, data)) {
989                 *target_entry = source_entry;
990                 ret = 0;
991                 goto exit;
992         }
993
994         if (forward)
995                 head = &source_entry->class->locks_after;
996         else
997                 head = &source_entry->class->locks_before;
998
999         if (list_empty(head))
1000                 goto exit;
1001
1002         __cq_init(cq);
1003         __cq_enqueue(cq, (unsigned long)source_entry);
1004
1005         while (!__cq_empty(cq)) {
1006                 struct lock_list *lock;
1007
1008                 __cq_dequeue(cq, (unsigned long *)&lock);
1009
1010                 if (!lock->class) {
1011                         ret = -2;
1012                         goto exit;
1013                 }
1014
1015                 if (forward)
1016                         head = &lock->class->locks_after;
1017                 else
1018                         head = &lock->class->locks_before;
1019
1020                 list_for_each_entry(entry, head, entry) {
1021                         if (!lock_accessed(entry)) {
1022                                 unsigned int cq_depth;
1023                                 mark_lock_accessed(entry, lock);
1024                                 if (match(entry, data)) {
1025                                         *target_entry = entry;
1026                                         ret = 0;
1027                                         goto exit;
1028                                 }
1029
1030                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
1031                                         ret = -1;
1032                                         goto exit;
1033                                 }
1034                                 cq_depth = __cq_get_elem_count(cq);
1035                                 if (max_bfs_queue_depth < cq_depth)
1036                                         max_bfs_queue_depth = cq_depth;
1037                         }
1038                 }
1039         }
1040 exit:
1041         return ret;
1042 }
1043
1044 static inline int __bfs_forwards(struct lock_list *src_entry,
1045                         void *data,
1046                         int (*match)(struct lock_list *entry, void *data),
1047                         struct lock_list **target_entry)
1048 {
1049         return __bfs(src_entry, data, match, target_entry, 1);
1050
1051 }
1052
1053 static inline int __bfs_backwards(struct lock_list *src_entry,
1054                         void *data,
1055                         int (*match)(struct lock_list *entry, void *data),
1056                         struct lock_list **target_entry)
1057 {
1058         return __bfs(src_entry, data, match, target_entry, 0);
1059
1060 }
1061
1062 /*
1063  * Recursive, forwards-direction lock-dependency checking, used for
1064  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1065  * checking.
1066  */
1067
1068 /*
1069  * Print a dependency chain entry (this is only done when a deadlock
1070  * has been detected):
1071  */
1072 static noinline int
1073 print_circular_bug_entry(struct lock_list *target, int depth)
1074 {
1075         if (debug_locks_silent)
1076                 return 0;
1077         printk("\n-> #%u", depth);
1078         print_lock_name(target->class);
1079         printk(":\n");
1080         print_stack_trace(&target->trace, 6);
1081
1082         return 0;
1083 }
1084
1085 static void
1086 print_circular_lock_scenario(struct held_lock *src,
1087                              struct held_lock *tgt,
1088                              struct lock_list *prt)
1089 {
1090         struct lock_class *source = hlock_class(src);
1091         struct lock_class *target = hlock_class(tgt);
1092         struct lock_class *parent = prt->class;
1093
1094         /*
1095          * A direct locking problem where unsafe_class lock is taken
1096          * directly by safe_class lock, then all we need to show
1097          * is the deadlock scenario, as it is obvious that the
1098          * unsafe lock is taken under the safe lock.
1099          *
1100          * But if there is a chain instead, where the safe lock takes
1101          * an intermediate lock (middle_class) where this lock is
1102          * not the same as the safe lock, then the lock chain is
1103          * used to describe the problem. Otherwise we would need
1104          * to show a different CPU case for each link in the chain
1105          * from the safe_class lock to the unsafe_class lock.
1106          */
1107         if (parent != source) {
1108                 printk("Chain exists of:\n  ");
1109                 __print_lock_name(source);
1110                 printk(" --> ");
1111                 __print_lock_name(parent);
1112                 printk(" --> ");
1113                 __print_lock_name(target);
1114                 printk("\n\n");
1115         }
1116
1117         printk(" Possible unsafe locking scenario:\n\n");
1118         printk("       CPU0                    CPU1\n");
1119         printk("       ----                    ----\n");
1120         printk("  lock(");
1121         __print_lock_name(target);
1122         printk(");\n");
1123         printk("                               lock(");
1124         __print_lock_name(parent);
1125         printk(");\n");
1126         printk("                               lock(");
1127         __print_lock_name(target);
1128         printk(");\n");
1129         printk("  lock(");
1130         __print_lock_name(source);
1131         printk(");\n");
1132         printk("\n *** DEADLOCK ***\n\n");
1133 }
1134
1135 /*
1136  * When a circular dependency is detected, print the
1137  * header first:
1138  */
1139 static noinline int
1140 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1141                         struct held_lock *check_src,
1142                         struct held_lock *check_tgt)
1143 {
1144         struct task_struct *curr = current;
1145
1146         if (debug_locks_silent)
1147                 return 0;
1148
1149         printk("\n");
1150         printk("======================================================\n");
1151         printk("[ INFO: possible circular locking dependency detected ]\n");
1152         print_kernel_version();
1153         printk("-------------------------------------------------------\n");
1154         printk("%s/%d is trying to acquire lock:\n",
1155                 curr->comm, task_pid_nr(curr));
1156         print_lock(check_src);
1157         printk("\nbut task is already holding lock:\n");
1158         print_lock(check_tgt);
1159         printk("\nwhich lock already depends on the new lock.\n\n");
1160         printk("\nthe existing dependency chain (in reverse order) is:\n");
1161
1162         print_circular_bug_entry(entry, depth);
1163
1164         return 0;
1165 }
1166
1167 static inline int class_equal(struct lock_list *entry, void *data)
1168 {
1169         return entry->class == data;
1170 }
1171
1172 static noinline int print_circular_bug(struct lock_list *this,
1173                                 struct lock_list *target,
1174                                 struct held_lock *check_src,
1175                                 struct held_lock *check_tgt)
1176 {
1177         struct task_struct *curr = current;
1178         struct lock_list *parent;
1179         struct lock_list *first_parent;
1180         int depth;
1181
1182         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1183                 return 0;
1184
1185         if (!save_trace(&this->trace))
1186                 return 0;
1187
1188         depth = get_lock_depth(target);
1189
1190         print_circular_bug_header(target, depth, check_src, check_tgt);
1191
1192         parent = get_lock_parent(target);
1193         first_parent = parent;
1194
1195         while (parent) {
1196                 print_circular_bug_entry(parent, --depth);
1197                 parent = get_lock_parent(parent);
1198         }
1199
1200         printk("\nother info that might help us debug this:\n\n");
1201         print_circular_lock_scenario(check_src, check_tgt,
1202                                      first_parent);
1203
1204         lockdep_print_held_locks(curr);
1205
1206         printk("\nstack backtrace:\n");
1207         dump_stack();
1208
1209         return 0;
1210 }
1211
1212 static noinline int print_bfs_bug(int ret)
1213 {
1214         if (!debug_locks_off_graph_unlock())
1215                 return 0;
1216
1217         /*
1218          * Breadth-first-search failed, graph got corrupted?
1219          */
1220         WARN(1, "lockdep bfs error:%d\n", ret);
1221
1222         return 0;
1223 }
1224
1225 static int noop_count(struct lock_list *entry, void *data)
1226 {
1227         (*(unsigned long *)data)++;
1228         return 0;
1229 }
1230
1231 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1232 {
1233         unsigned long  count = 0;
1234         struct lock_list *uninitialized_var(target_entry);
1235
1236         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1237
1238         return count;
1239 }
1240 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1241 {
1242         unsigned long ret, flags;
1243         struct lock_list this;
1244
1245         this.parent = NULL;
1246         this.class = class;
1247
1248         local_irq_save(flags);
1249         arch_spin_lock(&lockdep_lock);
1250         ret = __lockdep_count_forward_deps(&this);
1251         arch_spin_unlock(&lockdep_lock);
1252         local_irq_restore(flags);
1253
1254         return ret;
1255 }
1256
1257 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1258 {
1259         unsigned long  count = 0;
1260         struct lock_list *uninitialized_var(target_entry);
1261
1262         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1263
1264         return count;
1265 }
1266
1267 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1268 {
1269         unsigned long ret, flags;
1270         struct lock_list this;
1271
1272         this.parent = NULL;
1273         this.class = class;
1274
1275         local_irq_save(flags);
1276         arch_spin_lock(&lockdep_lock);
1277         ret = __lockdep_count_backward_deps(&this);
1278         arch_spin_unlock(&lockdep_lock);
1279         local_irq_restore(flags);
1280
1281         return ret;
1282 }
1283
1284 /*
1285  * Prove that the dependency graph starting at <entry> can not
1286  * lead to <target>. Print an error and return 0 if it does.
1287  */
1288 static noinline int
1289 check_noncircular(struct lock_list *root, struct lock_class *target,
1290                 struct lock_list **target_entry)
1291 {
1292         int result;
1293
1294         debug_atomic_inc(nr_cyclic_checks);
1295
1296         result = __bfs_forwards(root, target, class_equal, target_entry);
1297
1298         return result;
1299 }
1300
1301 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1302 /*
1303  * Forwards and backwards subgraph searching, for the purposes of
1304  * proving that two subgraphs can be connected by a new dependency
1305  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1306  */
1307
1308 static inline int usage_match(struct lock_list *entry, void *bit)
1309 {
1310         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1311 }
1312
1313
1314
1315 /*
1316  * Find a node in the forwards-direction dependency sub-graph starting
1317  * at @root->class that matches @bit.
1318  *
1319  * Return 0 if such a node exists in the subgraph, and put that node
1320  * into *@target_entry.
1321  *
1322  * Return 1 otherwise and keep *@target_entry unchanged.
1323  * Return <0 on error.
1324  */
1325 static int
1326 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1327                         struct lock_list **target_entry)
1328 {
1329         int result;
1330
1331         debug_atomic_inc(nr_find_usage_forwards_checks);
1332
1333         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1334
1335         return result;
1336 }
1337
1338 /*
1339  * Find a node in the backwards-direction dependency sub-graph starting
1340  * at @root->class that matches @bit.
1341  *
1342  * Return 0 if such a node exists in the subgraph, and put that node
1343  * into *@target_entry.
1344  *
1345  * Return 1 otherwise and keep *@target_entry unchanged.
1346  * Return <0 on error.
1347  */
1348 static int
1349 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1350                         struct lock_list **target_entry)
1351 {
1352         int result;
1353
1354         debug_atomic_inc(nr_find_usage_backwards_checks);
1355
1356         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1357
1358         return result;
1359 }
1360
1361 static void print_lock_class_header(struct lock_class *class, int depth)
1362 {
1363         int bit;
1364
1365         printk("%*s->", depth, "");
1366         print_lock_name(class);
1367         printk(" ops: %lu", class->ops);
1368         printk(" {\n");
1369
1370         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1371                 if (class->usage_mask & (1 << bit)) {
1372                         int len = depth;
1373
1374                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1375                         len += printk(" at:\n");
1376                         print_stack_trace(class->usage_traces + bit, len);
1377                 }
1378         }
1379         printk("%*s }\n", depth, "");
1380
1381         printk("%*s ... key      at: ",depth,"");
1382         print_ip_sym((unsigned long)class->key);
1383 }
1384
1385 /*
1386  * printk the shortest lock dependencies from @start to @end in reverse order:
1387  */
1388 static void __used
1389 print_shortest_lock_dependencies(struct lock_list *leaf,
1390                                 struct lock_list *root)
1391 {
1392         struct lock_list *entry = leaf;
1393         int depth;
1394
1395         /*compute depth from generated tree by BFS*/
1396         depth = get_lock_depth(leaf);
1397
1398         do {
1399                 print_lock_class_header(entry->class, depth);
1400                 printk("%*s ... acquired at:\n", depth, "");
1401                 print_stack_trace(&entry->trace, 2);
1402                 printk("\n");
1403
1404                 if (depth == 0 && (entry != root)) {
1405                         printk("lockdep:%s bad path found in chain graph\n", __func__);
1406                         break;
1407                 }
1408
1409                 entry = get_lock_parent(entry);
1410                 depth--;
1411         } while (entry && (depth >= 0));
1412
1413         return;
1414 }
1415
1416 static void
1417 print_irq_lock_scenario(struct lock_list *safe_entry,
1418                         struct lock_list *unsafe_entry,
1419                         struct lock_class *prev_class,
1420                         struct lock_class *next_class)
1421 {
1422         struct lock_class *safe_class = safe_entry->class;
1423         struct lock_class *unsafe_class = unsafe_entry->class;
1424         struct lock_class *middle_class = prev_class;
1425
1426         if (middle_class == safe_class)
1427                 middle_class = next_class;
1428
1429         /*
1430          * A direct locking problem where unsafe_class lock is taken
1431          * directly by safe_class lock, then all we need to show
1432          * is the deadlock scenario, as it is obvious that the
1433          * unsafe lock is taken under the safe lock.
1434          *
1435          * But if there is a chain instead, where the safe lock takes
1436          * an intermediate lock (middle_class) where this lock is
1437          * not the same as the safe lock, then the lock chain is
1438          * used to describe the problem. Otherwise we would need
1439          * to show a different CPU case for each link in the chain
1440          * from the safe_class lock to the unsafe_class lock.
1441          */
1442         if (middle_class != unsafe_class) {
1443                 printk("Chain exists of:\n  ");
1444                 __print_lock_name(safe_class);
1445                 printk(" --> ");
1446                 __print_lock_name(middle_class);
1447                 printk(" --> ");
1448                 __print_lock_name(unsafe_class);
1449                 printk("\n\n");
1450         }
1451
1452         printk(" Possible interrupt unsafe locking scenario:\n\n");
1453         printk("       CPU0                    CPU1\n");
1454         printk("       ----                    ----\n");
1455         printk("  lock(");
1456         __print_lock_name(unsafe_class);
1457         printk(");\n");
1458         printk("                               local_irq_disable();\n");
1459         printk("                               lock(");
1460         __print_lock_name(safe_class);
1461         printk(");\n");
1462         printk("                               lock(");
1463         __print_lock_name(middle_class);
1464         printk(");\n");
1465         printk("  <Interrupt>\n");
1466         printk("    lock(");
1467         __print_lock_name(safe_class);
1468         printk(");\n");
1469         printk("\n *** DEADLOCK ***\n\n");
1470 }
1471
1472 static int
1473 print_bad_irq_dependency(struct task_struct *curr,
1474                          struct lock_list *prev_root,
1475                          struct lock_list *next_root,
1476                          struct lock_list *backwards_entry,
1477                          struct lock_list *forwards_entry,
1478                          struct held_lock *prev,
1479                          struct held_lock *next,
1480                          enum lock_usage_bit bit1,
1481                          enum lock_usage_bit bit2,
1482                          const char *irqclass)
1483 {
1484         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1485                 return 0;
1486
1487         printk("\n");
1488         printk("======================================================\n");
1489         printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1490                 irqclass, irqclass);
1491         print_kernel_version();
1492         printk("------------------------------------------------------\n");
1493         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1494                 curr->comm, task_pid_nr(curr),
1495                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1496                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1497                 curr->hardirqs_enabled,
1498                 curr->softirqs_enabled);
1499         print_lock(next);
1500
1501         printk("\nand this task is already holding:\n");
1502         print_lock(prev);
1503         printk("which would create a new lock dependency:\n");
1504         print_lock_name(hlock_class(prev));
1505         printk(" ->");
1506         print_lock_name(hlock_class(next));
1507         printk("\n");
1508
1509         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1510                 irqclass);
1511         print_lock_name(backwards_entry->class);
1512         printk("\n... which became %s-irq-safe at:\n", irqclass);
1513
1514         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1515
1516         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1517         print_lock_name(forwards_entry->class);
1518         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1519         printk("...");
1520
1521         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1522
1523         printk("\nother info that might help us debug this:\n\n");
1524         print_irq_lock_scenario(backwards_entry, forwards_entry,
1525                                 hlock_class(prev), hlock_class(next));
1526
1527         lockdep_print_held_locks(curr);
1528
1529         printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1530         printk(" and the holding lock:\n");
1531         if (!save_trace(&prev_root->trace))
1532                 return 0;
1533         print_shortest_lock_dependencies(backwards_entry, prev_root);
1534
1535         printk("\nthe dependencies between the lock to be acquired");
1536         printk(" and %s-irq-unsafe lock:\n", irqclass);
1537         if (!save_trace(&next_root->trace))
1538                 return 0;
1539         print_shortest_lock_dependencies(forwards_entry, next_root);
1540
1541         printk("\nstack backtrace:\n");
1542         dump_stack();
1543
1544         return 0;
1545 }
1546
1547 static int
1548 check_usage(struct task_struct *curr, struct held_lock *prev,
1549             struct held_lock *next, enum lock_usage_bit bit_backwards,
1550             enum lock_usage_bit bit_forwards, const char *irqclass)
1551 {
1552         int ret;
1553         struct lock_list this, that;
1554         struct lock_list *uninitialized_var(target_entry);
1555         struct lock_list *uninitialized_var(target_entry1);
1556
1557         this.parent = NULL;
1558
1559         this.class = hlock_class(prev);
1560         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1561         if (ret < 0)
1562                 return print_bfs_bug(ret);
1563         if (ret == 1)
1564                 return ret;
1565
1566         that.parent = NULL;
1567         that.class = hlock_class(next);
1568         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1569         if (ret < 0)
1570                 return print_bfs_bug(ret);
1571         if (ret == 1)
1572                 return ret;
1573
1574         return print_bad_irq_dependency(curr, &this, &that,
1575                         target_entry, target_entry1,
1576                         prev, next,
1577                         bit_backwards, bit_forwards, irqclass);
1578 }
1579
1580 static const char *state_names[] = {
1581 #define LOCKDEP_STATE(__STATE) \
1582         __stringify(__STATE),
1583 #include "lockdep_states.h"
1584 #undef LOCKDEP_STATE
1585 };
1586
1587 static const char *state_rnames[] = {
1588 #define LOCKDEP_STATE(__STATE) \
1589         __stringify(__STATE)"-READ",
1590 #include "lockdep_states.h"
1591 #undef LOCKDEP_STATE
1592 };
1593
1594 static inline const char *state_name(enum lock_usage_bit bit)
1595 {
1596         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1597 }
1598
1599 static int exclusive_bit(int new_bit)
1600 {
1601         /*
1602          * USED_IN
1603          * USED_IN_READ
1604          * ENABLED
1605          * ENABLED_READ
1606          *
1607          * bit 0 - write/read
1608          * bit 1 - used_in/enabled
1609          * bit 2+  state
1610          */
1611
1612         int state = new_bit & ~3;
1613         int dir = new_bit & 2;
1614
1615         /*
1616          * keep state, bit flip the direction and strip read.
1617          */
1618         return state | (dir ^ 2);
1619 }
1620
1621 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1622                            struct held_lock *next, enum lock_usage_bit bit)
1623 {
1624         /*
1625          * Prove that the new dependency does not connect a hardirq-safe
1626          * lock with a hardirq-unsafe lock - to achieve this we search
1627          * the backwards-subgraph starting at <prev>, and the
1628          * forwards-subgraph starting at <next>:
1629          */
1630         if (!check_usage(curr, prev, next, bit,
1631                            exclusive_bit(bit), state_name(bit)))
1632                 return 0;
1633
1634         bit++; /* _READ */
1635
1636         /*
1637          * Prove that the new dependency does not connect a hardirq-safe-read
1638          * lock with a hardirq-unsafe lock - to achieve this we search
1639          * the backwards-subgraph starting at <prev>, and the
1640          * forwards-subgraph starting at <next>:
1641          */
1642         if (!check_usage(curr, prev, next, bit,
1643                            exclusive_bit(bit), state_name(bit)))
1644                 return 0;
1645
1646         return 1;
1647 }
1648
1649 static int
1650 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1651                 struct held_lock *next)
1652 {
1653 #define LOCKDEP_STATE(__STATE)                                          \
1654         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1655                 return 0;
1656 #include "lockdep_states.h"
1657 #undef LOCKDEP_STATE
1658
1659         return 1;
1660 }
1661
1662 static void inc_chains(void)
1663 {
1664         if (current->hardirq_context)
1665                 nr_hardirq_chains++;
1666         else {
1667                 if (current->softirq_context)
1668                         nr_softirq_chains++;
1669                 else
1670                         nr_process_chains++;
1671         }
1672 }
1673
1674 #else
1675
1676 static inline int
1677 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1678                 struct held_lock *next)
1679 {
1680         return 1;
1681 }
1682
1683 static inline void inc_chains(void)
1684 {
1685         nr_process_chains++;
1686 }
1687
1688 #endif
1689
1690 static void
1691 print_deadlock_scenario(struct held_lock *nxt,
1692                              struct held_lock *prv)
1693 {
1694         struct lock_class *next = hlock_class(nxt);
1695         struct lock_class *prev = hlock_class(prv);
1696
1697         printk(" Possible unsafe locking scenario:\n\n");
1698         printk("       CPU0\n");
1699         printk("       ----\n");
1700         printk("  lock(");
1701         __print_lock_name(prev);
1702         printk(");\n");
1703         printk("  lock(");
1704         __print_lock_name(next);
1705         printk(");\n");
1706         printk("\n *** DEADLOCK ***\n\n");
1707         printk(" May be due to missing lock nesting notation\n\n");
1708 }
1709
1710 static int
1711 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1712                    struct held_lock *next)
1713 {
1714         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1715                 return 0;
1716
1717         printk("\n");
1718         printk("=============================================\n");
1719         printk("[ INFO: possible recursive locking detected ]\n");
1720         print_kernel_version();
1721         printk("---------------------------------------------\n");
1722         printk("%s/%d is trying to acquire lock:\n",
1723                 curr->comm, task_pid_nr(curr));
1724         print_lock(next);
1725         printk("\nbut task is already holding lock:\n");
1726         print_lock(prev);
1727
1728         printk("\nother info that might help us debug this:\n");
1729         print_deadlock_scenario(next, prev);
1730         lockdep_print_held_locks(curr);
1731
1732         printk("\nstack backtrace:\n");
1733         dump_stack();
1734
1735         return 0;
1736 }
1737
1738 /*
1739  * Check whether we are holding such a class already.
1740  *
1741  * (Note that this has to be done separately, because the graph cannot
1742  * detect such classes of deadlocks.)
1743  *
1744  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1745  */
1746 static int
1747 check_deadlock(struct task_struct *curr, struct held_lock *next,
1748                struct lockdep_map *next_instance, int read)
1749 {
1750         struct held_lock *prev;
1751         struct held_lock *nest = NULL;
1752         int i;
1753
1754         for (i = 0; i < curr->lockdep_depth; i++) {
1755                 prev = curr->held_locks + i;
1756
1757                 if (prev->instance == next->nest_lock)
1758                         nest = prev;
1759
1760                 if (hlock_class(prev) != hlock_class(next))
1761                         continue;
1762
1763                 /*
1764                  * Allow read-after-read recursion of the same
1765                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1766                  */
1767                 if ((read == 2) && prev->read)
1768                         return 2;
1769
1770                 /*
1771                  * We're holding the nest_lock, which serializes this lock's
1772                  * nesting behaviour.
1773                  */
1774                 if (nest)
1775                         return 2;
1776
1777                 return print_deadlock_bug(curr, prev, next);
1778         }
1779         return 1;
1780 }
1781
1782 /*
1783  * There was a chain-cache miss, and we are about to add a new dependency
1784  * to a previous lock. We recursively validate the following rules:
1785  *
1786  *  - would the adding of the <prev> -> <next> dependency create a
1787  *    circular dependency in the graph? [== circular deadlock]
1788  *
1789  *  - does the new prev->next dependency connect any hardirq-safe lock
1790  *    (in the full backwards-subgraph starting at <prev>) with any
1791  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1792  *    <next>)? [== illegal lock inversion with hardirq contexts]
1793  *
1794  *  - does the new prev->next dependency connect any softirq-safe lock
1795  *    (in the full backwards-subgraph starting at <prev>) with any
1796  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1797  *    <next>)? [== illegal lock inversion with softirq contexts]
1798  *
1799  * any of these scenarios could lead to a deadlock.
1800  *
1801  * Then if all the validations pass, we add the forwards and backwards
1802  * dependency.
1803  */
1804 static int
1805 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1806                struct held_lock *next, int distance, int trylock_loop)
1807 {
1808         struct lock_list *entry;
1809         int ret;
1810         struct lock_list this;
1811         struct lock_list *uninitialized_var(target_entry);
1812         /*
1813          * Static variable, serialized by the graph_lock().
1814          *
1815          * We use this static variable to save the stack trace in case
1816          * we call into this function multiple times due to encountering
1817          * trylocks in the held lock stack.
1818          */
1819         static struct stack_trace trace;
1820
1821         /*
1822          * Prove that the new <prev> -> <next> dependency would not
1823          * create a circular dependency in the graph. (We do this by
1824          * forward-recursing into the graph starting at <next>, and
1825          * checking whether we can reach <prev>.)
1826          *
1827          * We are using global variables to control the recursion, to
1828          * keep the stackframe size of the recursive functions low:
1829          */
1830         this.class = hlock_class(next);
1831         this.parent = NULL;
1832         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1833         if (unlikely(!ret))
1834                 return print_circular_bug(&this, target_entry, next, prev);
1835         else if (unlikely(ret < 0))
1836                 return print_bfs_bug(ret);
1837
1838         if (!check_prev_add_irq(curr, prev, next))
1839                 return 0;
1840
1841         /*
1842          * For recursive read-locks we do all the dependency checks,
1843          * but we dont store read-triggered dependencies (only
1844          * write-triggered dependencies). This ensures that only the
1845          * write-side dependencies matter, and that if for example a
1846          * write-lock never takes any other locks, then the reads are
1847          * equivalent to a NOP.
1848          */
1849         if (next->read == 2 || prev->read == 2)
1850                 return 1;
1851         /*
1852          * Is the <prev> -> <next> dependency already present?
1853          *
1854          * (this may occur even though this is a new chain: consider
1855          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1856          *  chains - the second one will be new, but L1 already has
1857          *  L2 added to its dependency list, due to the first chain.)
1858          */
1859         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1860                 if (entry->class == hlock_class(next)) {
1861                         if (distance == 1)
1862                                 entry->distance = 1;
1863                         return 2;
1864                 }
1865         }
1866
1867         if (!trylock_loop && !save_trace(&trace))
1868                 return 0;
1869
1870         /*
1871          * Ok, all validations passed, add the new lock
1872          * to the previous lock's dependency list:
1873          */
1874         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1875                                &hlock_class(prev)->locks_after,
1876                                next->acquire_ip, distance, &trace);
1877
1878         if (!ret)
1879                 return 0;
1880
1881         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1882                                &hlock_class(next)->locks_before,
1883                                next->acquire_ip, distance, &trace);
1884         if (!ret)
1885                 return 0;
1886
1887         /*
1888          * Debugging printouts:
1889          */
1890         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1891                 graph_unlock();
1892                 printk("\n new dependency: ");
1893                 print_lock_name(hlock_class(prev));
1894                 printk(" => ");
1895                 print_lock_name(hlock_class(next));
1896                 printk("\n");
1897                 dump_stack();
1898                 return graph_lock();
1899         }
1900         return 1;
1901 }
1902
1903 /*
1904  * Add the dependency to all directly-previous locks that are 'relevant'.
1905  * The ones that are relevant are (in increasing distance from curr):
1906  * all consecutive trylock entries and the final non-trylock entry - or
1907  * the end of this context's lock-chain - whichever comes first.
1908  */
1909 static int
1910 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1911 {
1912         int depth = curr->lockdep_depth;
1913         int trylock_loop = 0;
1914         struct held_lock *hlock;
1915
1916         /*
1917          * Debugging checks.
1918          *
1919          * Depth must not be zero for a non-head lock:
1920          */
1921         if (!depth)
1922                 goto out_bug;
1923         /*
1924          * At least two relevant locks must exist for this
1925          * to be a head:
1926          */
1927         if (curr->held_locks[depth].irq_context !=
1928                         curr->held_locks[depth-1].irq_context)
1929                 goto out_bug;
1930
1931         for (;;) {
1932                 int distance = curr->lockdep_depth - depth + 1;
1933                 hlock = curr->held_locks + depth-1;
1934                 /*
1935                  * Only non-recursive-read entries get new dependencies
1936                  * added:
1937                  */
1938                 if (hlock->read != 2) {
1939                         if (!check_prev_add(curr, hlock, next,
1940                                                 distance, trylock_loop))
1941                                 return 0;
1942                         /*
1943                          * Stop after the first non-trylock entry,
1944                          * as non-trylock entries have added their
1945                          * own direct dependencies already, so this
1946                          * lock is connected to them indirectly:
1947                          */
1948                         if (!hlock->trylock)
1949                                 break;
1950                 }
1951                 depth--;
1952                 /*
1953                  * End of lock-stack?
1954                  */
1955                 if (!depth)
1956                         break;
1957                 /*
1958                  * Stop the search if we cross into another context:
1959                  */
1960                 if (curr->held_locks[depth].irq_context !=
1961                                 curr->held_locks[depth-1].irq_context)
1962                         break;
1963                 trylock_loop = 1;
1964         }
1965         return 1;
1966 out_bug:
1967         if (!debug_locks_off_graph_unlock())
1968                 return 0;
1969
1970         /*
1971          * Clearly we all shouldn't be here, but since we made it we
1972          * can reliable say we messed up our state. See the above two
1973          * gotos for reasons why we could possibly end up here.
1974          */
1975         WARN_ON(1);
1976
1977         return 0;
1978 }
1979
1980 unsigned long nr_lock_chains;
1981 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1982 int nr_chain_hlocks;
1983 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1984
1985 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1986 {
1987         return lock_classes + chain_hlocks[chain->base + i];
1988 }
1989
1990 /*
1991  * Look up a dependency chain. If the key is not present yet then
1992  * add it and return 1 - in this case the new dependency chain is
1993  * validated. If the key is already hashed, return 0.
1994  * (On return with 1 graph_lock is held.)
1995  */
1996 static inline int lookup_chain_cache(struct task_struct *curr,
1997                                      struct held_lock *hlock,
1998                                      u64 chain_key)
1999 {
2000         struct lock_class *class = hlock_class(hlock);
2001         struct list_head *hash_head = chainhashentry(chain_key);
2002         struct lock_chain *chain;
2003         struct held_lock *hlock_curr, *hlock_next;
2004         int i, j;
2005
2006         /*
2007          * We might need to take the graph lock, ensure we've got IRQs
2008          * disabled to make this an IRQ-safe lock.. for recursion reasons
2009          * lockdep won't complain about its own locking errors.
2010          */
2011         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2012                 return 0;
2013         /*
2014          * We can walk it lock-free, because entries only get added
2015          * to the hash:
2016          */
2017         list_for_each_entry(chain, hash_head, entry) {
2018                 if (chain->chain_key == chain_key) {
2019 cache_hit:
2020                         debug_atomic_inc(chain_lookup_hits);
2021                         if (very_verbose(class))
2022                                 printk("\nhash chain already cached, key: "
2023                                         "%016Lx tail class: [%p] %s\n",
2024                                         (unsigned long long)chain_key,
2025                                         class->key, class->name);
2026                         return 0;
2027                 }
2028         }
2029         if (very_verbose(class))
2030                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2031                         (unsigned long long)chain_key, class->key, class->name);
2032         /*
2033          * Allocate a new chain entry from the static array, and add
2034          * it to the hash:
2035          */
2036         if (!graph_lock())
2037                 return 0;
2038         /*
2039          * We have to walk the chain again locked - to avoid duplicates:
2040          */
2041         list_for_each_entry(chain, hash_head, entry) {
2042                 if (chain->chain_key == chain_key) {
2043                         graph_unlock();
2044                         goto cache_hit;
2045                 }
2046         }
2047         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2048                 if (!debug_locks_off_graph_unlock())
2049                         return 0;
2050
2051                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2052                 printk("turning off the locking correctness validator.\n");
2053                 dump_stack();
2054                 return 0;
2055         }
2056         chain = lock_chains + nr_lock_chains++;
2057         chain->chain_key = chain_key;
2058         chain->irq_context = hlock->irq_context;
2059         /* Find the first held_lock of current chain */
2060         hlock_next = hlock;
2061         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2062                 hlock_curr = curr->held_locks + i;
2063                 if (hlock_curr->irq_context != hlock_next->irq_context)
2064                         break;
2065                 hlock_next = hlock;
2066         }
2067         i++;
2068         chain->depth = curr->lockdep_depth + 1 - i;
2069         if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2070                 chain->base = nr_chain_hlocks;
2071                 nr_chain_hlocks += chain->depth;
2072                 for (j = 0; j < chain->depth - 1; j++, i++) {
2073                         int lock_id = curr->held_locks[i].class_idx - 1;
2074                         chain_hlocks[chain->base + j] = lock_id;
2075                 }
2076                 chain_hlocks[chain->base + j] = class - lock_classes;
2077         }
2078         list_add_tail_rcu(&chain->entry, hash_head);
2079         debug_atomic_inc(chain_lookup_misses);
2080         inc_chains();
2081
2082         return 1;
2083 }
2084
2085 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2086                 struct held_lock *hlock, int chain_head, u64 chain_key)
2087 {
2088         /*
2089          * Trylock needs to maintain the stack of held locks, but it
2090          * does not add new dependencies, because trylock can be done
2091          * in any order.
2092          *
2093          * We look up the chain_key and do the O(N^2) check and update of
2094          * the dependencies only if this is a new dependency chain.
2095          * (If lookup_chain_cache() returns with 1 it acquires
2096          * graph_lock for us)
2097          */
2098         if (!hlock->trylock && (hlock->check == 2) &&
2099             lookup_chain_cache(curr, hlock, chain_key)) {
2100                 /*
2101                  * Check whether last held lock:
2102                  *
2103                  * - is irq-safe, if this lock is irq-unsafe
2104                  * - is softirq-safe, if this lock is hardirq-unsafe
2105                  *
2106                  * And check whether the new lock's dependency graph
2107                  * could lead back to the previous lock.
2108                  *
2109                  * any of these scenarios could lead to a deadlock. If
2110                  * All validations
2111                  */
2112                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2113
2114                 if (!ret)
2115                         return 0;
2116                 /*
2117                  * Mark recursive read, as we jump over it when
2118                  * building dependencies (just like we jump over
2119                  * trylock entries):
2120                  */
2121                 if (ret == 2)
2122                         hlock->read = 2;
2123                 /*
2124                  * Add dependency only if this lock is not the head
2125                  * of the chain, and if it's not a secondary read-lock:
2126                  */
2127                 if (!chain_head && ret != 2)
2128                         if (!check_prevs_add(curr, hlock))
2129                                 return 0;
2130                 graph_unlock();
2131         } else
2132                 /* after lookup_chain_cache(): */
2133                 if (unlikely(!debug_locks))
2134                         return 0;
2135
2136         return 1;
2137 }
2138 #else
2139 static inline int validate_chain(struct task_struct *curr,
2140                 struct lockdep_map *lock, struct held_lock *hlock,
2141                 int chain_head, u64 chain_key)
2142 {
2143         return 1;
2144 }
2145 #endif
2146
2147 /*
2148  * We are building curr_chain_key incrementally, so double-check
2149  * it from scratch, to make sure that it's done correctly:
2150  */
2151 static void check_chain_key(struct task_struct *curr)
2152 {
2153 #ifdef CONFIG_DEBUG_LOCKDEP
2154         struct held_lock *hlock, *prev_hlock = NULL;
2155         unsigned int i, id;
2156         u64 chain_key = 0;
2157
2158         for (i = 0; i < curr->lockdep_depth; i++) {
2159                 hlock = curr->held_locks + i;
2160                 if (chain_key != hlock->prev_chain_key) {
2161                         debug_locks_off();
2162                         /*
2163                          * We got mighty confused, our chain keys don't match
2164                          * with what we expect, someone trample on our task state?
2165                          */
2166                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2167                                 curr->lockdep_depth, i,
2168                                 (unsigned long long)chain_key,
2169                                 (unsigned long long)hlock->prev_chain_key);
2170                         return;
2171                 }
2172                 id = hlock->class_idx - 1;
2173                 /*
2174                  * Whoops ran out of static storage again?
2175                  */
2176                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2177                         return;
2178
2179                 if (prev_hlock && (prev_hlock->irq_context !=
2180                                                         hlock->irq_context))
2181                         chain_key = 0;
2182                 chain_key = iterate_chain_key(chain_key, id);
2183                 prev_hlock = hlock;
2184         }
2185         if (chain_key != curr->curr_chain_key) {
2186                 debug_locks_off();
2187                 /*
2188                  * More smoking hash instead of calculating it, damn see these
2189                  * numbers float.. I bet that a pink elephant stepped on my memory.
2190                  */
2191                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2192                         curr->lockdep_depth, i,
2193                         (unsigned long long)chain_key,
2194                         (unsigned long long)curr->curr_chain_key);
2195         }
2196 #endif
2197 }
2198
2199 static void
2200 print_usage_bug_scenario(struct held_lock *lock)
2201 {
2202         struct lock_class *class = hlock_class(lock);
2203
2204         printk(" Possible unsafe locking scenario:\n\n");
2205         printk("       CPU0\n");
2206         printk("       ----\n");
2207         printk("  lock(");
2208         __print_lock_name(class);
2209         printk(");\n");
2210         printk("  <Interrupt>\n");
2211         printk("    lock(");
2212         __print_lock_name(class);
2213         printk(");\n");
2214         printk("\n *** DEADLOCK ***\n\n");
2215 }
2216
2217 static int
2218 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2219                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2220 {
2221         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2222                 return 0;
2223
2224         printk("\n");
2225         printk("=================================\n");
2226         printk("[ INFO: inconsistent lock state ]\n");
2227         print_kernel_version();
2228         printk("---------------------------------\n");
2229
2230         printk("inconsistent {%s} -> {%s} usage.\n",
2231                 usage_str[prev_bit], usage_str[new_bit]);
2232
2233         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2234                 curr->comm, task_pid_nr(curr),
2235                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2236                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2237                 trace_hardirqs_enabled(curr),
2238                 trace_softirqs_enabled(curr));
2239         print_lock(this);
2240
2241         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2242         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2243
2244         print_irqtrace_events(curr);
2245         printk("\nother info that might help us debug this:\n");
2246         print_usage_bug_scenario(this);
2247
2248         lockdep_print_held_locks(curr);
2249
2250         printk("\nstack backtrace:\n");
2251         dump_stack();
2252
2253         return 0;
2254 }
2255
2256 /*
2257  * Print out an error if an invalid bit is set:
2258  */
2259 static inline int
2260 valid_state(struct task_struct *curr, struct held_lock *this,
2261             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2262 {
2263         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2264                 return print_usage_bug(curr, this, bad_bit, new_bit);
2265         return 1;
2266 }
2267
2268 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2269                      enum lock_usage_bit new_bit);
2270
2271 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2272
2273 /*
2274  * print irq inversion bug:
2275  */
2276 static int
2277 print_irq_inversion_bug(struct task_struct *curr,
2278                         struct lock_list *root, struct lock_list *other,
2279                         struct held_lock *this, int forwards,
2280                         const char *irqclass)
2281 {
2282         struct lock_list *entry = other;
2283         struct lock_list *middle = NULL;
2284         int depth;
2285
2286         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2287                 return 0;
2288
2289         printk("\n");
2290         printk("=========================================================\n");
2291         printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2292         print_kernel_version();
2293         printk("---------------------------------------------------------\n");
2294         printk("%s/%d just changed the state of lock:\n",
2295                 curr->comm, task_pid_nr(curr));
2296         print_lock(this);
2297         if (forwards)
2298                 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2299         else
2300                 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2301         print_lock_name(other->class);
2302         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2303
2304         printk("\nother info that might help us debug this:\n");
2305
2306         /* Find a middle lock (if one exists) */
2307         depth = get_lock_depth(other);
2308         do {
2309                 if (depth == 0 && (entry != root)) {
2310                         printk("lockdep:%s bad path found in chain graph\n", __func__);
2311                         break;
2312                 }
2313                 middle = entry;
2314                 entry = get_lock_parent(entry);
2315                 depth--;
2316         } while (entry && entry != root && (depth >= 0));
2317         if (forwards)
2318                 print_irq_lock_scenario(root, other,
2319                         middle ? middle->class : root->class, other->class);
2320         else
2321                 print_irq_lock_scenario(other, root,
2322                         middle ? middle->class : other->class, root->class);
2323
2324         lockdep_print_held_locks(curr);
2325
2326         printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2327         if (!save_trace(&root->trace))
2328                 return 0;
2329         print_shortest_lock_dependencies(other, root);
2330
2331         printk("\nstack backtrace:\n");
2332         dump_stack();
2333
2334         return 0;
2335 }
2336
2337 /*
2338  * Prove that in the forwards-direction subgraph starting at <this>
2339  * there is no lock matching <mask>:
2340  */
2341 static int
2342 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2343                      enum lock_usage_bit bit, const char *irqclass)
2344 {
2345         int ret;
2346         struct lock_list root;
2347         struct lock_list *uninitialized_var(target_entry);
2348
2349         root.parent = NULL;
2350         root.class = hlock_class(this);
2351         ret = find_usage_forwards(&root, bit, &target_entry);
2352         if (ret < 0)
2353                 return print_bfs_bug(ret);
2354         if (ret == 1)
2355                 return ret;
2356
2357         return print_irq_inversion_bug(curr, &root, target_entry,
2358                                         this, 1, irqclass);
2359 }
2360
2361 /*
2362  * Prove that in the backwards-direction subgraph starting at <this>
2363  * there is no lock matching <mask>:
2364  */
2365 static int
2366 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2367                       enum lock_usage_bit bit, const char *irqclass)
2368 {
2369         int ret;
2370         struct lock_list root;
2371         struct lock_list *uninitialized_var(target_entry);
2372
2373         root.parent = NULL;
2374         root.class = hlock_class(this);
2375         ret = find_usage_backwards(&root, bit, &target_entry);
2376         if (ret < 0)
2377                 return print_bfs_bug(ret);
2378         if (ret == 1)
2379                 return ret;
2380
2381         return print_irq_inversion_bug(curr, &root, target_entry,
2382                                         this, 0, irqclass);
2383 }
2384
2385 void print_irqtrace_events(struct task_struct *curr)
2386 {
2387         printk("irq event stamp: %u\n", curr->irq_events);
2388         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2389         print_ip_sym(curr->hardirq_enable_ip);
2390         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2391         print_ip_sym(curr->hardirq_disable_ip);
2392         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2393         print_ip_sym(curr->softirq_enable_ip);
2394         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2395         print_ip_sym(curr->softirq_disable_ip);
2396 }
2397
2398 static int HARDIRQ_verbose(struct lock_class *class)
2399 {
2400 #if HARDIRQ_VERBOSE
2401         return class_filter(class);
2402 #endif
2403         return 0;
2404 }
2405
2406 static int SOFTIRQ_verbose(struct lock_class *class)
2407 {
2408 #if SOFTIRQ_VERBOSE
2409         return class_filter(class);
2410 #endif
2411         return 0;
2412 }
2413
2414 static int RECLAIM_FS_verbose(struct lock_class *class)
2415 {
2416 #if RECLAIM_VERBOSE
2417         return class_filter(class);
2418 #endif
2419         return 0;
2420 }
2421
2422 #define STRICT_READ_CHECKS      1
2423
2424 static int (*state_verbose_f[])(struct lock_class *class) = {
2425 #define LOCKDEP_STATE(__STATE) \
2426         __STATE##_verbose,
2427 #include "lockdep_states.h"
2428 #undef LOCKDEP_STATE
2429 };
2430
2431 static inline int state_verbose(enum lock_usage_bit bit,
2432                                 struct lock_class *class)
2433 {
2434         return state_verbose_f[bit >> 2](class);
2435 }
2436
2437 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2438                              enum lock_usage_bit bit, const char *name);
2439
2440 static int
2441 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2442                 enum lock_usage_bit new_bit)
2443 {
2444         int excl_bit = exclusive_bit(new_bit);
2445         int read = new_bit & 1;
2446         int dir = new_bit & 2;
2447
2448         /*
2449          * mark USED_IN has to look forwards -- to ensure no dependency
2450          * has ENABLED state, which would allow recursion deadlocks.
2451          *
2452          * mark ENABLED has to look backwards -- to ensure no dependee
2453          * has USED_IN state, which, again, would allow  recursion deadlocks.
2454          */
2455         check_usage_f usage = dir ?
2456                 check_usage_backwards : check_usage_forwards;
2457
2458         /*
2459          * Validate that this particular lock does not have conflicting
2460          * usage states.
2461          */
2462         if (!valid_state(curr, this, new_bit, excl_bit))
2463                 return 0;
2464
2465         /*
2466          * Validate that the lock dependencies don't have conflicting usage
2467          * states.
2468          */
2469         if ((!read || !dir || STRICT_READ_CHECKS) &&
2470                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2471                 return 0;
2472
2473         /*
2474          * Check for read in write conflicts
2475          */
2476         if (!read) {
2477                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2478                         return 0;
2479
2480                 if (STRICT_READ_CHECKS &&
2481                         !usage(curr, this, excl_bit + 1,
2482                                 state_name(new_bit + 1)))
2483                         return 0;
2484         }
2485
2486         if (state_verbose(new_bit, hlock_class(this)))
2487                 return 2;
2488
2489         return 1;
2490 }
2491
2492 enum mark_type {
2493 #define LOCKDEP_STATE(__STATE)  __STATE,
2494 #include "lockdep_states.h"
2495 #undef LOCKDEP_STATE
2496 };
2497
2498 /*
2499  * Mark all held locks with a usage bit:
2500  */
2501 static int
2502 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2503 {
2504         enum lock_usage_bit usage_bit;
2505         struct held_lock *hlock;
2506         int i;
2507
2508         for (i = 0; i < curr->lockdep_depth; i++) {
2509                 hlock = curr->held_locks + i;
2510
2511                 usage_bit = 2 + (mark << 2); /* ENABLED */
2512                 if (hlock->read)
2513                         usage_bit += 1; /* READ */
2514
2515                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2516
2517                 if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
2518                         continue;
2519
2520                 if (!mark_lock(curr, hlock, usage_bit))
2521                         return 0;
2522         }
2523
2524         return 1;
2525 }
2526
2527 /*
2528  * Hardirqs will be enabled:
2529  */
2530 static void __trace_hardirqs_on_caller(unsigned long ip)
2531 {
2532         struct task_struct *curr = current;
2533
2534         /* we'll do an OFF -> ON transition: */
2535         curr->hardirqs_enabled = 1;
2536
2537         /*
2538          * We are going to turn hardirqs on, so set the
2539          * usage bit for all held locks:
2540          */
2541         if (!mark_held_locks(curr, HARDIRQ))
2542                 return;
2543         /*
2544          * If we have softirqs enabled, then set the usage
2545          * bit for all held locks. (disabled hardirqs prevented
2546          * this bit from being set before)
2547          */
2548         if (curr->softirqs_enabled)
2549                 if (!mark_held_locks(curr, SOFTIRQ))
2550                         return;
2551
2552         curr->hardirq_enable_ip = ip;
2553         curr->hardirq_enable_event = ++curr->irq_events;
2554         debug_atomic_inc(hardirqs_on_events);
2555 }
2556
2557 void trace_hardirqs_on_caller(unsigned long ip)
2558 {
2559         time_hardirqs_on(CALLER_ADDR0, ip);
2560
2561         if (unlikely(!debug_locks || current->lockdep_recursion))
2562                 return;
2563
2564         if (unlikely(current->hardirqs_enabled)) {
2565                 /*
2566                  * Neither irq nor preemption are disabled here
2567                  * so this is racy by nature but losing one hit
2568                  * in a stat is not a big deal.
2569                  */
2570                 __debug_atomic_inc(redundant_hardirqs_on);
2571                 return;
2572         }
2573
2574         /*
2575          * We're enabling irqs and according to our state above irqs weren't
2576          * already enabled, yet we find the hardware thinks they are in fact
2577          * enabled.. someone messed up their IRQ state tracing.
2578          */
2579         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2580                 return;
2581
2582         /*
2583          * See the fine text that goes along with this variable definition.
2584          */
2585         if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2586                 return;
2587
2588         /*
2589          * Can't allow enabling interrupts while in an interrupt handler,
2590          * that's general bad form and such. Recursion, limited stack etc..
2591          */
2592         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2593                 return;
2594
2595         current->lockdep_recursion = 1;
2596         __trace_hardirqs_on_caller(ip);
2597         current->lockdep_recursion = 0;
2598 }
2599 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2600
2601 void trace_hardirqs_on(void)
2602 {
2603         trace_hardirqs_on_caller(CALLER_ADDR0);
2604 }
2605 EXPORT_SYMBOL(trace_hardirqs_on);
2606
2607 /*
2608  * Hardirqs were disabled:
2609  */
2610 void trace_hardirqs_off_caller(unsigned long ip)
2611 {
2612         struct task_struct *curr = current;
2613
2614         time_hardirqs_off(CALLER_ADDR0, ip);
2615
2616         if (unlikely(!debug_locks || current->lockdep_recursion))
2617                 return;
2618
2619         /*
2620          * So we're supposed to get called after you mask local IRQs, but for
2621          * some reason the hardware doesn't quite think you did a proper job.
2622          */
2623         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2624                 return;
2625
2626         if (curr->hardirqs_enabled) {
2627                 /*
2628                  * We have done an ON -> OFF transition:
2629                  */
2630                 curr->hardirqs_enabled = 0;
2631                 curr->hardirq_disable_ip = ip;
2632                 curr->hardirq_disable_event = ++curr->irq_events;
2633                 debug_atomic_inc(hardirqs_off_events);
2634         } else
2635                 debug_atomic_inc(redundant_hardirqs_off);
2636 }
2637 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2638
2639 void trace_hardirqs_off(void)
2640 {
2641         trace_hardirqs_off_caller(CALLER_ADDR0);
2642 }
2643 EXPORT_SYMBOL(trace_hardirqs_off);
2644
2645 /*
2646  * Softirqs will be enabled:
2647  */
2648 void trace_softirqs_on(unsigned long ip)
2649 {
2650         struct task_struct *curr = current;
2651
2652         if (unlikely(!debug_locks || current->lockdep_recursion))
2653                 return;
2654
2655         /*
2656          * We fancy IRQs being disabled here, see softirq.c, avoids
2657          * funny state and nesting things.
2658          */
2659         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2660                 return;
2661
2662         if (curr->softirqs_enabled) {
2663                 debug_atomic_inc(redundant_softirqs_on);
2664                 return;
2665         }
2666
2667         current->lockdep_recursion = 1;
2668         /*
2669          * We'll do an OFF -> ON transition:
2670          */
2671         curr->softirqs_enabled = 1;
2672         curr->softirq_enable_ip = ip;
2673         curr->softirq_enable_event = ++curr->irq_events;
2674         debug_atomic_inc(softirqs_on_events);
2675         /*
2676          * We are going to turn softirqs on, so set the
2677          * usage bit for all held locks, if hardirqs are
2678          * enabled too:
2679          */
2680         if (curr->hardirqs_enabled)
2681                 mark_held_locks(curr, SOFTIRQ);
2682         current->lockdep_recursion = 0;
2683 }
2684
2685 /*
2686  * Softirqs were disabled:
2687  */
2688 void trace_softirqs_off(unsigned long ip)
2689 {
2690         struct task_struct *curr = current;
2691
2692         if (unlikely(!debug_locks || current->lockdep_recursion))
2693                 return;
2694
2695         /*
2696          * We fancy IRQs being disabled here, see softirq.c
2697          */
2698         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2699                 return;
2700
2701         if (curr->softirqs_enabled) {
2702                 /*
2703                  * We have done an ON -> OFF transition:
2704                  */
2705                 curr->softirqs_enabled = 0;
2706                 curr->softirq_disable_ip = ip;
2707                 curr->softirq_disable_event = ++curr->irq_events;
2708                 debug_atomic_inc(softirqs_off_events);
2709                 /*
2710                  * Whoops, we wanted softirqs off, so why aren't they?
2711                  */
2712                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2713         } else
2714                 debug_atomic_inc(redundant_softirqs_off);
2715 }
2716
2717 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2718 {
2719         struct task_struct *curr = current;
2720
2721         if (unlikely(!debug_locks))
2722                 return;
2723
2724         /* no reclaim without waiting on it */
2725         if (!(gfp_mask & __GFP_WAIT))
2726                 return;
2727
2728         /* this guy won't enter reclaim */
2729         if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2730                 return;
2731
2732         /* We're only interested __GFP_FS allocations for now */
2733         if (!(gfp_mask & __GFP_FS))
2734                 return;
2735
2736         /*
2737          * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2738          */
2739         if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2740                 return;
2741
2742         mark_held_locks(curr, RECLAIM_FS);
2743 }
2744
2745 static void check_flags(unsigned long flags);
2746
2747 void lockdep_trace_alloc(gfp_t gfp_mask)
2748 {
2749         unsigned long flags;
2750
2751         if (unlikely(current->lockdep_recursion))
2752                 return;
2753
2754         raw_local_irq_save(flags);
2755         check_flags(flags);
2756         current->lockdep_recursion = 1;
2757         __lockdep_trace_alloc(gfp_mask, flags);
2758         current->lockdep_recursion = 0;
2759         raw_local_irq_restore(flags);
2760 }
2761
2762 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2763 {
2764         /*
2765          * If non-trylock use in a hardirq or softirq context, then
2766          * mark the lock as used in these contexts:
2767          */
2768         if (!hlock->trylock) {
2769                 if (hlock->read) {
2770                         if (curr->hardirq_context)
2771                                 if (!mark_lock(curr, hlock,
2772                                                 LOCK_USED_IN_HARDIRQ_READ))
2773                                         return 0;
2774                         if (curr->softirq_context)
2775                                 if (!mark_lock(curr, hlock,
2776                                                 LOCK_USED_IN_SOFTIRQ_READ))
2777                                         return 0;
2778                 } else {
2779                         if (curr->hardirq_context)
2780                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2781                                         return 0;
2782                         if (curr->softirq_context)
2783                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2784                                         return 0;
2785                 }
2786         }
2787         if (!hlock->hardirqs_off) {
2788                 if (hlock->read) {
2789                         if (!mark_lock(curr, hlock,
2790                                         LOCK_ENABLED_HARDIRQ_READ))
2791                                 return 0;
2792                         if (curr->softirqs_enabled)
2793                                 if (!mark_lock(curr, hlock,
2794                                                 LOCK_ENABLED_SOFTIRQ_READ))
2795                                         return 0;
2796                 } else {
2797                         if (!mark_lock(curr, hlock,
2798                                         LOCK_ENABLED_HARDIRQ))
2799                                 return 0;
2800                         if (curr->softirqs_enabled)
2801                                 if (!mark_lock(curr, hlock,
2802                                                 LOCK_ENABLED_SOFTIRQ))
2803                                         return 0;
2804                 }
2805         }
2806
2807         /*
2808          * We reuse the irq context infrastructure more broadly as a general
2809          * context checking code. This tests GFP_FS recursion (a lock taken
2810          * during reclaim for a GFP_FS allocation is held over a GFP_FS
2811          * allocation).
2812          */
2813         if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2814                 if (hlock->read) {
2815                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2816                                         return 0;
2817                 } else {
2818                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2819                                         return 0;
2820                 }
2821         }
2822
2823         return 1;
2824 }
2825
2826 static int separate_irq_context(struct task_struct *curr,
2827                 struct held_lock *hlock)
2828 {
2829         unsigned int depth = curr->lockdep_depth;
2830
2831         /*
2832          * Keep track of points where we cross into an interrupt context:
2833          */
2834         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2835                                 curr->softirq_context;
2836         if (depth) {
2837                 struct held_lock *prev_hlock;
2838
2839                 prev_hlock = curr->held_locks + depth-1;
2840                 /*
2841                  * If we cross into another context, reset the
2842                  * hash key (this also prevents the checking and the
2843                  * adding of the dependency to 'prev'):
2844                  */
2845                 if (prev_hlock->irq_context != hlock->irq_context)
2846                         return 1;
2847         }
2848         return 0;
2849 }
2850
2851 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2852
2853 static inline
2854 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2855                 enum lock_usage_bit new_bit)
2856 {
2857         WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2858         return 1;
2859 }
2860
2861 static inline int mark_irqflags(struct task_struct *curr,
2862                 struct held_lock *hlock)
2863 {
2864         return 1;
2865 }
2866
2867 static inline int separate_irq_context(struct task_struct *curr,
2868                 struct held_lock *hlock)
2869 {
2870         return 0;
2871 }
2872
2873 void lockdep_trace_alloc(gfp_t gfp_mask)
2874 {
2875 }
2876
2877 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2878
2879 /*
2880  * Mark a lock with a usage bit, and validate the state transition:
2881  */
2882 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2883                              enum lock_usage_bit new_bit)
2884 {
2885         unsigned int new_mask = 1 << new_bit, ret = 1;
2886
2887         /*
2888          * If already set then do not dirty the cacheline,
2889          * nor do any checks:
2890          */
2891         if (likely(hlock_class(this)->usage_mask & new_mask))
2892                 return 1;
2893
2894         if (!graph_lock())
2895                 return 0;
2896         /*
2897          * Make sure we didn't race:
2898          */
2899         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2900                 graph_unlock();
2901                 return 1;
2902         }
2903
2904         hlock_class(this)->usage_mask |= new_mask;
2905
2906         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2907                 return 0;
2908
2909         switch (new_bit) {
2910 #define LOCKDEP_STATE(__STATE)                  \
2911         case LOCK_USED_IN_##__STATE:            \
2912         case LOCK_USED_IN_##__STATE##_READ:     \
2913         case LOCK_ENABLED_##__STATE:            \
2914         case LOCK_ENABLED_##__STATE##_READ:
2915 #include "lockdep_states.h"
2916 #undef LOCKDEP_STATE
2917                 ret = mark_lock_irq(curr, this, new_bit);
2918                 if (!ret)
2919                         return 0;
2920                 break;
2921         case LOCK_USED:
2922                 debug_atomic_dec(nr_unused_locks);
2923                 break;
2924         default:
2925                 if (!debug_locks_off_graph_unlock())
2926                         return 0;
2927                 WARN_ON(1);
2928                 return 0;
2929         }
2930
2931         graph_unlock();
2932
2933         /*
2934          * We must printk outside of the graph_lock:
2935          */
2936         if (ret == 2) {
2937                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2938                 print_lock(this);
2939                 print_irqtrace_events(curr);
2940                 dump_stack();
2941         }
2942
2943         return ret;
2944 }
2945
2946 /*
2947  * Initialize a lock instance's lock-class mapping info:
2948  */
2949 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2950                       struct lock_class_key *key, int subclass)
2951 {
2952         int i;
2953
2954         kmemcheck_mark_initialized(lock, sizeof(*lock));
2955
2956         for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2957                 lock->class_cache[i] = NULL;
2958
2959 #ifdef CONFIG_LOCK_STAT
2960         lock->cpu = raw_smp_processor_id();
2961 #endif
2962
2963         /*
2964          * Can't be having no nameless bastards around this place!
2965          */
2966         if (DEBUG_LOCKS_WARN_ON(!name)) {
2967                 lock->name = "NULL";
2968                 return;
2969         }
2970
2971         lock->name = name;
2972
2973         /*
2974          * No key, no joy, we need to hash something.
2975          */
2976         if (DEBUG_LOCKS_WARN_ON(!key))
2977                 return;
2978         /*
2979          * Sanity check, the lock-class key must be persistent:
2980          */
2981         if (!static_obj(key)) {
2982                 printk("BUG: key %p not in .data!\n", key);
2983                 /*
2984                  * What it says above ^^^^^, I suggest you read it.
2985                  */
2986                 DEBUG_LOCKS_WARN_ON(1);
2987                 return;
2988         }
2989         lock->key = key;
2990
2991         if (unlikely(!debug_locks))
2992                 return;
2993
2994         if (subclass)
2995                 register_lock_class(lock, subclass, 1);
2996 }
2997 EXPORT_SYMBOL_GPL(lockdep_init_map);
2998
2999 struct lock_class_key __lockdep_no_validate__;
3000
3001 /*
3002  * This gets called for every mutex_lock*()/spin_lock*() operation.
3003  * We maintain the dependency maps and validate the locking attempt:
3004  */
3005 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3006                           int trylock, int read, int check, int hardirqs_off,
3007                           struct lockdep_map *nest_lock, unsigned long ip,
3008                           int references)
3009 {
3010         struct task_struct *curr = current;
3011         struct lock_class *class = NULL;
3012         struct held_lock *hlock;
3013         unsigned int depth, id;
3014         int chain_head = 0;
3015         int class_idx;
3016         u64 chain_key;
3017
3018         if (!prove_locking)
3019                 check = 1;
3020
3021         if (unlikely(!debug_locks))
3022                 return 0;
3023
3024         /*
3025          * Lockdep should run with IRQs disabled, otherwise we could
3026          * get an interrupt which would want to take locks, which would
3027          * end up in lockdep and have you got a head-ache already?
3028          */
3029         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3030                 return 0;
3031
3032         if (lock->key == &__lockdep_no_validate__)
3033                 check = 1;
3034
3035         if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3036                 class = lock->class_cache[subclass];
3037         /*
3038          * Not cached?
3039          */
3040         if (unlikely(!class)) {
3041                 class = register_lock_class(lock, subclass, 0);
3042                 if (!class)
3043                         return 0;
3044         }
3045         atomic_inc((atomic_t *)&class->ops);
3046         if (very_verbose(class)) {
3047                 printk("\nacquire class [%p] %s", class->key, class->name);
3048                 if (class->name_version > 1)
3049                         printk("#%d", class->name_version);
3050                 printk("\n");
3051                 dump_stack();
3052         }
3053
3054         /*
3055          * Add the lock to the list of currently held locks.
3056          * (we dont increase the depth just yet, up until the
3057          * dependency checks are done)
3058          */
3059         depth = curr->lockdep_depth;
3060         /*
3061          * Ran out of static storage for our per-task lock stack again have we?
3062          */
3063         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3064                 return 0;
3065
3066         class_idx = class - lock_classes + 1;
3067
3068         if (depth) {
3069                 hlock = curr->held_locks + depth - 1;
3070                 if (hlock->class_idx == class_idx && nest_lock) {
3071                         if (hlock->references)
3072                                 hlock->references++;
3073                         else
3074                                 hlock->references = 2;
3075
3076                         return 1;
3077                 }
3078         }
3079
3080         hlock = curr->held_locks + depth;
3081         /*
3082          * Plain impossible, we just registered it and checked it weren't no
3083          * NULL like.. I bet this mushroom I ate was good!
3084          */
3085         if (DEBUG_LOCKS_WARN_ON(!class))
3086                 return 0;
3087         hlock->class_idx = class_idx;
3088         hlock->acquire_ip = ip;
3089         hlock->instance = lock;
3090         hlock->nest_lock = nest_lock;
3091         hlock->trylock = trylock;
3092         hlock->read = read;
3093         hlock->check = check;
3094         hlock->hardirqs_off = !!hardirqs_off;
3095         hlock->references = references;
3096 #ifdef CONFIG_LOCK_STAT
3097         hlock->waittime_stamp = 0;
3098         hlock->holdtime_stamp = lockstat_clock();
3099 #endif
3100
3101         if (check == 2 && !mark_irqflags(curr, hlock))
3102                 return 0;
3103
3104         /* mark it as used: */
3105         if (!mark_lock(curr, hlock, LOCK_USED))
3106                 return 0;
3107
3108         /*
3109          * Calculate the chain hash: it's the combined hash of all the
3110          * lock keys along the dependency chain. We save the hash value
3111          * at every step so that we can get the current hash easily
3112          * after unlock. The chain hash is then used to cache dependency
3113          * results.
3114          *
3115          * The 'key ID' is what is the most compact key value to drive
3116          * the hash, not class->key.
3117          */
3118         id = class - lock_classes;
3119         /*
3120          * Whoops, we did it again.. ran straight out of our static allocation.
3121          */
3122         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3123                 return 0;
3124
3125         chain_key = curr->curr_chain_key;
3126         if (!depth) {
3127                 /*
3128                  * How can we have a chain hash when we ain't got no keys?!
3129                  */
3130                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3131                         return 0;
3132                 chain_head = 1;
3133         }
3134
3135         hlock->prev_chain_key = chain_key;
3136         if (separate_irq_context(curr, hlock)) {
3137                 chain_key = 0;
3138                 chain_head = 1;
3139         }
3140         chain_key = iterate_chain_key(chain_key, id);
3141
3142         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3143                 return 0;
3144
3145         curr->curr_chain_key = chain_key;
3146         curr->lockdep_depth++;
3147         check_chain_key(curr);
3148 #ifdef CONFIG_DEBUG_LOCKDEP
3149         if (unlikely(!debug_locks))
3150                 return 0;
3151 #endif
3152         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3153                 debug_locks_off();
3154                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
3155                 printk("turning off the locking correctness validator.\n");
3156                 dump_stack();
3157                 return 0;
3158         }
3159
3160         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3161                 max_lockdep_depth = curr->lockdep_depth;
3162
3163         return 1;
3164 }
3165
3166 static int
3167 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3168                            unsigned long ip)
3169 {
3170         if (!debug_locks_off())
3171                 return 0;
3172         if (debug_locks_silent)
3173                 return 0;
3174
3175         printk("\n");
3176         printk("=====================================\n");
3177         printk("[ BUG: bad unlock balance detected! ]\n");
3178         printk("-------------------------------------\n");
3179         printk("%s/%d is trying to release lock (",
3180                 curr->comm, task_pid_nr(curr));
3181         print_lockdep_cache(lock);
3182         printk(") at:\n");
3183         print_ip_sym(ip);
3184         printk("but there are no more locks to release!\n");
3185         printk("\nother info that might help us debug this:\n");
3186         lockdep_print_held_locks(curr);
3187
3188         printk("\nstack backtrace:\n");
3189         dump_stack();
3190
3191         return 0;
3192 }
3193
3194 /*
3195  * Common debugging checks for both nested and non-nested unlock:
3196  */
3197 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3198                         unsigned long ip)
3199 {
3200         if (unlikely(!debug_locks))
3201                 return 0;
3202         /*
3203          * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
3204          */
3205         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3206                 return 0;
3207
3208         if (curr->lockdep_depth <= 0)
3209                 return print_unlock_inbalance_bug(curr, lock, ip);
3210
3211         return 1;
3212 }
3213
3214 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3215 {
3216         if (hlock->instance == lock)
3217                 return 1;
3218
3219         if (hlock->references) {
3220                 struct lock_class *class = lock->class_cache[0];
3221
3222                 if (!class)
3223                         class = look_up_lock_class(lock, 0);
3224
3225                 /*
3226                  * If look_up_lock_class() failed to find a class, we're trying
3227                  * to test if we hold a lock that has never yet been acquired.
3228                  * Clearly if the lock hasn't been acquired _ever_, we're not
3229                  * holding it either, so report failure.
3230                  */
3231                 if (!class)
3232                         return 0;
3233
3234                 /*
3235                  * References, but not a lock we're actually ref-counting?
3236                  * State got messed up, follow the sites that change ->references
3237                  * and try to make sense of it.
3238                  */
3239                 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3240                         return 0;
3241
3242                 if (hlock->class_idx == class - lock_classes + 1)
3243                         return 1;
3244         }
3245
3246         return 0;
3247 }
3248
3249 static int
3250 __lock_set_class(struct lockdep_map *lock, const char *name,
3251                  struct lock_class_key *key, unsigned int subclass,
3252                  unsigned long ip)
3253 {
3254         struct task_struct *curr = current;
3255         struct held_lock *hlock, *prev_hlock;
3256         struct lock_class *class;
3257         unsigned int depth;
3258         int i;
3259
3260         depth = curr->lockdep_depth;
3261         /*
3262          * This function is about (re)setting the class of a held lock,
3263          * yet we're not actually holding any locks. Naughty user!
3264          */
3265         if (DEBUG_LOCKS_WARN_ON(!depth))
3266                 return 0;
3267
3268         prev_hlock = NULL;
3269         for (i = depth-1; i >= 0; i--) {
3270                 hlock = curr->held_locks + i;
3271                 /*
3272                  * We must not cross into another context:
3273                  */
3274                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3275                         break;
3276                 if (match_held_lock(hlock, lock))
3277                         goto found_it;
3278                 prev_hlock = hlock;
3279         }
3280         return print_unlock_inbalance_bug(curr, lock, ip);
3281
3282 found_it:
3283         lockdep_init_map(lock, name, key, 0);
3284         class = register_lock_class(lock, subclass, 0);
3285         hlock->class_idx = class - lock_classes + 1;
3286
3287         curr->lockdep_depth = i;
3288         curr->curr_chain_key = hlock->prev_chain_key;
3289
3290         for (; i < depth; i++) {
3291                 hlock = curr->held_locks + i;
3292                 if (!__lock_acquire(hlock->instance,
3293                         hlock_class(hlock)->subclass, hlock->trylock,
3294                                 hlock->read, hlock->check, hlock->hardirqs_off,
3295                                 hlock->nest_lock, hlock->acquire_ip,
3296                                 hlock->references))
3297                         return 0;
3298         }
3299
3300         /*
3301          * I took it apart and put it back together again, except now I have
3302          * these 'spare' parts.. where shall I put them.
3303          */
3304         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3305                 return 0;
3306         return 1;
3307 }
3308
3309 /*
3310  * Remove the lock to the list of currently held locks in a
3311  * potentially non-nested (out of order) manner. This is a
3312  * relatively rare operation, as all the unlock APIs default
3313  * to nested mode (which uses lock_release()):
3314  */
3315 static int
3316 lock_release_non_nested(struct task_struct *curr,
3317                         struct lockdep_map *lock, unsigned long ip)
3318 {
3319         struct held_lock *hlock, *prev_hlock;
3320         unsigned int depth;
3321         int i;
3322
3323         /*
3324          * Check whether the lock exists in the current stack
3325          * of held locks:
3326          */
3327         depth = curr->lockdep_depth;
3328         /*
3329          * So we're all set to release this lock.. wait what lock? We don't
3330          * own any locks, you've been drinking again?
3331          */
3332         if (DEBUG_LOCKS_WARN_ON(!depth))
3333                 return 0;
3334
3335         prev_hlock = NULL;
3336         for (i = depth-1; i >= 0; i--) {
3337                 hlock = curr->held_locks + i;
3338                 /*
3339                  * We must not cross into another context:
3340                  */
3341                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3342                         break;
3343                 if (match_held_lock(hlock, lock))
3344                         goto found_it;
3345                 prev_hlock = hlock;
3346         }
3347         return print_unlock_inbalance_bug(curr, lock, ip);
3348
3349 found_it:
3350         if (hlock->instance == lock)
3351                 lock_release_holdtime(hlock);
3352
3353         if (hlock->references) {
3354                 hlock->references--;
3355                 if (hlock->references) {
3356                         /*
3357                          * We had, and after removing one, still have
3358                          * references, the current lock stack is still
3359                          * valid. We're done!
3360                          */
3361                         return 1;
3362                 }
3363         }
3364
3365         /*
3366          * We have the right lock to unlock, 'hlock' points to it.
3367          * Now we remove it from the stack, and add back the other
3368          * entries (if any), recalculating the hash along the way:
3369          */
3370
3371         curr->lockdep_depth = i;
3372         curr->curr_chain_key = hlock->prev_chain_key;
3373
3374         for (i++; i < depth; i++) {
3375                 hlock = curr->held_locks + i;
3376                 if (!__lock_acquire(hlock->instance,
3377                         hlock_class(hlock)->subclass, hlock->trylock,
3378                                 hlock->read, hlock->check, hlock->hardirqs_off,
3379                                 hlock->nest_lock, hlock->acquire_ip,
3380                                 hlock->references))
3381                         return 0;
3382         }
3383
3384         /*
3385          * We had N bottles of beer on the wall, we drank one, but now
3386          * there's not N-1 bottles of beer left on the wall...
3387          */
3388         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3389                 return 0;
3390         return 1;
3391 }
3392
3393 /*
3394  * Remove the lock to the list of currently held locks - this gets
3395  * called on mutex_unlock()/spin_unlock*() (or on a failed
3396  * mutex_lock_interruptible()). This is done for unlocks that nest
3397  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3398  */
3399 static int lock_release_nested(struct task_struct *curr,
3400                                struct lockdep_map *lock, unsigned long ip)
3401 {
3402         struct held_lock *hlock;
3403         unsigned int depth;
3404
3405         /*
3406          * Pop off the top of the lock stack:
3407          */
3408         depth = curr->lockdep_depth - 1;
3409         hlock = curr->held_locks + depth;
3410
3411         /*
3412          * Is the unlock non-nested:
3413          */
3414         if (hlock->instance != lock || hlock->references)
3415                 return lock_release_non_nested(curr, lock, ip);
3416         curr->lockdep_depth--;
3417
3418         /*
3419          * No more locks, but somehow we've got hash left over, who left it?
3420          */
3421         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3422                 return 0;
3423
3424         curr->curr_chain_key = hlock->prev_chain_key;
3425
3426         lock_release_holdtime(hlock);
3427
3428 #ifdef CONFIG_DEBUG_LOCKDEP
3429         hlock->prev_chain_key = 0;
3430         hlock->class_idx = 0;
3431         hlock->acquire_ip = 0;
3432         hlock->irq_context = 0;
3433 #endif
3434         return 1;
3435 }
3436
3437 /*
3438  * Remove the lock to the list of currently held locks - this gets
3439  * called on mutex_unlock()/spin_unlock*() (or on a failed
3440  * mutex_lock_interruptible()). This is done for unlocks that nest
3441  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3442  */
3443 static void
3444 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3445 {
3446         struct task_struct *curr = current;
3447
3448         if (!check_unlock(curr, lock, ip))
3449                 return;
3450
3451         if (nested) {
3452                 if (!lock_release_nested(curr, lock, ip))
3453                         return;
3454         } else {
3455                 if (!lock_release_non_nested(curr, lock, ip))
3456                         return;
3457         }
3458
3459         check_chain_key(curr);
3460 }
3461
3462 static int __lock_is_held(struct lockdep_map *lock)
3463 {
3464         struct task_struct *curr = current;
3465         int i;
3466
3467         for (i = 0; i < curr->lockdep_depth; i++) {
3468                 struct held_lock *hlock = curr->held_locks + i;
3469
3470                 if (match_held_lock(hlock, lock))
3471                         return 1;
3472         }
3473
3474         return 0;
3475 }
3476
3477 /*
3478  * Check whether we follow the irq-flags state precisely:
3479  */
3480 static void check_flags(unsigned long flags)
3481 {
3482 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3483     defined(CONFIG_TRACE_IRQFLAGS)
3484         if (!debug_locks)
3485                 return;
3486
3487         if (irqs_disabled_flags(flags)) {
3488                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3489                         printk("possible reason: unannotated irqs-off.\n");
3490                 }
3491         } else {
3492                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3493                         printk("possible reason: unannotated irqs-on.\n");
3494                 }
3495         }
3496
3497         /*
3498          * We dont accurately track softirq state in e.g.
3499          * hardirq contexts (such as on 4KSTACKS), so only
3500          * check if not in hardirq contexts:
3501          */
3502         if (!hardirq_count()) {
3503                 if (softirq_count()) {
3504                         /* like the above, but with softirqs */
3505                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3506                 } else {
3507                         /* lick the above, does it taste good? */
3508                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3509                 }
3510         }
3511
3512         if (!debug_locks)
3513                 print_irqtrace_events(current);
3514 #endif
3515 }
3516
3517 void lock_set_class(struct lockdep_map *lock, const char *name,
3518                     struct lock_class_key *key, unsigned int subclass,
3519                     unsigned long ip)
3520 {
3521         unsigned long flags;
3522
3523         if (unlikely(current->lockdep_recursion))
3524                 return;
3525
3526         raw_local_irq_save(flags);
3527         current->lockdep_recursion = 1;
3528         check_flags(flags);
3529         if (__lock_set_class(lock, name, key, subclass, ip))
3530                 check_chain_key(current);
3531         current->lockdep_recursion = 0;
3532         raw_local_irq_restore(flags);
3533 }
3534 EXPORT_SYMBOL_GPL(lock_set_class);
3535
3536 /*
3537  * We are not always called with irqs disabled - do that here,
3538  * and also avoid lockdep recursion:
3539  */
3540 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3541                           int trylock, int read, int check,
3542                           struct lockdep_map *nest_lock, unsigned long ip)
3543 {
3544         unsigned long flags;
3545
3546         if (unlikely(current->lockdep_recursion))
3547                 return;
3548
3549         raw_local_irq_save(flags);
3550         check_flags(flags);
3551
3552         current->lockdep_recursion = 1;
3553         trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3554         __lock_acquire(lock, subclass, trylock, read, check,
3555                        irqs_disabled_flags(flags), nest_lock, ip, 0);
3556         current->lockdep_recursion = 0;
3557         raw_local_irq_restore(flags);
3558 }
3559 EXPORT_SYMBOL_GPL(lock_acquire);
3560
3561 void lock_release(struct lockdep_map *lock, int nested,
3562                           unsigned long ip)
3563 {
3564         unsigned long flags;
3565
3566         if (unlikely(current->lockdep_recursion))
3567                 return;
3568
3569         raw_local_irq_save(flags);
3570         check_flags(flags);
3571         current->lockdep_recursion = 1;
3572         trace_lock_release(lock, ip);
3573         __lock_release(lock, nested, ip);
3574         current->lockdep_recursion = 0;
3575         raw_local_irq_restore(flags);
3576 }
3577 EXPORT_SYMBOL_GPL(lock_release);
3578
3579 int lock_is_held(struct lockdep_map *lock)
3580 {
3581         unsigned long flags;
3582         int ret = 0;
3583
3584         if (unlikely(current->lockdep_recursion))
3585                 return 1; /* avoid false negative lockdep_assert_held() */
3586
3587         raw_local_irq_save(flags);
3588         check_flags(flags);
3589
3590         current->lockdep_recursion = 1;
3591         ret = __lock_is_held(lock);
3592         current->lockdep_recursion = 0;
3593         raw_local_irq_restore(flags);
3594
3595         return ret;
3596 }
3597 EXPORT_SYMBOL_GPL(lock_is_held);
3598
3599 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3600 {
3601         current->lockdep_reclaim_gfp = gfp_mask;
3602 }
3603
3604 void lockdep_clear_current_reclaim_state(void)
3605 {
3606         current->lockdep_reclaim_gfp = 0;
3607 }
3608
3609 #ifdef CONFIG_LOCK_STAT
3610 static int
3611 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3612                            unsigned long ip)
3613 {
3614         if (!debug_locks_off())
3615                 return 0;
3616         if (debug_locks_silent)
3617                 return 0;
3618
3619         printk("\n");
3620         printk("=================================\n");
3621         printk("[ BUG: bad contention detected! ]\n");
3622         printk("---------------------------------\n");
3623         printk("%s/%d is trying to contend lock (",
3624                 curr->comm, task_pid_nr(curr));
3625         print_lockdep_cache(lock);
3626         printk(") at:\n");
3627         print_ip_sym(ip);
3628         printk("but there are no locks held!\n");
3629         printk("\nother info that might help us debug this:\n");
3630         lockdep_print_held_locks(curr);
3631
3632         printk("\nstack backtrace:\n");
3633         dump_stack();
3634
3635         return 0;
3636 }
3637
3638 static void
3639 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3640 {
3641         struct task_struct *curr = current;
3642         struct held_lock *hlock, *prev_hlock;
3643         struct lock_class_stats *stats;
3644         unsigned int depth;
3645         int i, contention_point, contending_point;
3646
3647         depth = curr->lockdep_depth;
3648         /*
3649          * Whee, we contended on this lock, except it seems we're not
3650          * actually trying to acquire anything much at all..
3651          */
3652         if (DEBUG_LOCKS_WARN_ON(!depth))
3653                 return;
3654
3655         prev_hlock = NULL;
3656         for (i = depth-1; i >= 0; i--) {
3657                 hlock = curr->held_locks + i;
3658                 /*
3659                  * We must not cross into another context:
3660                  */
3661                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3662                         break;
3663                 if (match_held_lock(hlock, lock))
3664                         goto found_it;
3665                 prev_hlock = hlock;
3666         }
3667         print_lock_contention_bug(curr, lock, ip);
3668         return;
3669
3670 found_it:
3671         if (hlock->instance != lock)
3672                 return;
3673
3674         hlock->waittime_stamp = lockstat_clock();
3675
3676         contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3677         contending_point = lock_point(hlock_class(hlock)->contending_point,
3678                                       lock->ip);
3679
3680         stats = get_lock_stats(hlock_class(hlock));
3681         if (contention_point < LOCKSTAT_POINTS)
3682                 stats->contention_point[contention_point]++;
3683         if (contending_point < LOCKSTAT_POINTS)
3684                 stats->contending_point[contending_point]++;
3685         if (lock->cpu != smp_processor_id())
3686                 stats->bounces[bounce_contended + !!hlock->read]++;
3687         put_lock_stats(stats);
3688 }
3689
3690 static void
3691 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3692 {
3693         struct task_struct *curr = current;
3694         struct held_lock *hlock, *prev_hlock;
3695         struct lock_class_stats *stats;
3696         unsigned int depth;
3697         u64 now, waittime = 0;
3698         int i, cpu;
3699
3700         depth = curr->lockdep_depth;
3701         /*
3702          * Yay, we acquired ownership of this lock we didn't try to
3703          * acquire, how the heck did that happen?
3704          */
3705         if (DEBUG_LOCKS_WARN_ON(!depth))
3706                 return;
3707
3708         prev_hlock = NULL;
3709         for (i = depth-1; i >= 0; i--) {
3710                 hlock = curr->held_locks + i;
3711                 /*
3712                  * We must not cross into another context:
3713                  */
3714                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3715                         break;
3716                 if (match_held_lock(hlock, lock))
3717                         goto found_it;
3718                 prev_hlock = hlock;
3719         }
3720         print_lock_contention_bug(curr, lock, _RET_IP_);
3721         return;
3722
3723 found_it:
3724         if (hlock->instance != lock)
3725                 return;
3726
3727         cpu = smp_processor_id();
3728         if (hlock->waittime_stamp) {
3729                 now = lockstat_clock();
3730                 waittime = now - hlock->waittime_stamp;
3731                 hlock->holdtime_stamp = now;
3732         }
3733
3734         trace_lock_acquired(lock, ip);
3735
3736         stats = get_lock_stats(hlock_class(hlock));
3737         if (waittime) {
3738                 if (hlock->read)
3739                         lock_time_inc(&stats->read_waittime, waittime);
3740                 else
3741                         lock_time_inc(&stats->write_waittime, waittime);
3742         }
3743         if (lock->cpu != cpu)
3744                 stats->bounces[bounce_acquired + !!hlock->read]++;
3745         put_lock_stats(stats);
3746
3747         lock->cpu = cpu;
3748         lock->ip = ip;
3749 }
3750
3751 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3752 {
3753         unsigned long flags;
3754
3755         if (unlikely(!lock_stat))
3756                 return;
3757
3758         if (unlikely(current->lockdep_recursion))
3759                 return;
3760
3761         raw_local_irq_save(flags);
3762         check_flags(flags);
3763         current->lockdep_recursion = 1;
3764         trace_lock_contended(lock, ip);
3765         __lock_contended(lock, ip);
3766         current->lockdep_recursion = 0;
3767         raw_local_irq_restore(flags);
3768 }
3769 EXPORT_SYMBOL_GPL(lock_contended);
3770
3771 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3772 {
3773         unsigned long flags;
3774
3775         if (unlikely(!lock_stat))
3776                 return;
3777
3778         if (unlikely(current->lockdep_recursion))
3779                 return;
3780
3781         raw_local_irq_save(flags);
3782         check_flags(flags);
3783         current->lockdep_recursion = 1;
3784         __lock_acquired(lock, ip);
3785         current->lockdep_recursion = 0;
3786         raw_local_irq_restore(flags);
3787 }
3788 EXPORT_SYMBOL_GPL(lock_acquired);
3789 #endif
3790
3791 /*
3792  * Used by the testsuite, sanitize the validator state
3793  * after a simulated failure:
3794  */
3795
3796 void lockdep_reset(void)
3797 {
3798         unsigned long flags;
3799         int i;
3800
3801         raw_local_irq_save(flags);
3802         current->curr_chain_key = 0;
3803         current->lockdep_depth = 0;
3804         current->lockdep_recursion = 0;
3805         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3806         nr_hardirq_chains = 0;
3807         nr_softirq_chains = 0;
3808         nr_process_chains = 0;
3809         debug_locks = 1;
3810         for (i = 0; i < CHAINHASH_SIZE; i++)
3811                 INIT_LIST_HEAD(chainhash_table + i);
3812         raw_local_irq_restore(flags);
3813 }
3814
3815 static void zap_class(struct lock_class *class)
3816 {
3817         int i;
3818
3819         /*
3820          * Remove all dependencies this lock is
3821          * involved in:
3822          */
3823         for (i = 0; i < nr_list_entries; i++) {
3824                 if (list_entries[i].class == class)
3825                         list_del_rcu(&list_entries[i].entry);
3826         }
3827         /*
3828          * Unhash the class and remove it from the all_lock_classes list:
3829          */
3830         list_del_rcu(&class->hash_entry);
3831         list_del_rcu(&class->lock_entry);
3832
3833         class->key = NULL;
3834 }
3835
3836 static inline int within(const void *addr, void *start, unsigned long size)
3837 {
3838         return addr >= start && addr < start + size;
3839 }
3840
3841 void lockdep_free_key_range(void *start, unsigned long size)
3842 {
3843         struct lock_class *class, *next;
3844         struct list_head *head;
3845         unsigned long flags;
3846         int i;
3847         int locked;
3848
3849         raw_local_irq_save(flags);
3850         locked = graph_lock();
3851
3852         /*
3853          * Unhash all classes that were created by this module:
3854          */
3855         for (i = 0; i < CLASSHASH_SIZE; i++) {
3856                 head = classhash_table + i;
3857                 if (list_empty(head))
3858                         continue;
3859                 list_for_each_entry_safe(class, next, head, hash_entry) {
3860                         if (within(class->key, start, size))
3861                                 zap_class(class);
3862                         else if (within(class->name, start, size))
3863                                 zap_class(class);
3864                 }
3865         }
3866
3867         if (locked)
3868                 graph_unlock();
3869         raw_local_irq_restore(flags);
3870 }
3871
3872 void lockdep_reset_lock(struct lockdep_map *lock)
3873 {
3874         struct lock_class *class, *next;
3875         struct list_head *head;
3876         unsigned long flags;
3877         int i, j;
3878         int locked;
3879
3880         raw_local_irq_save(flags);
3881
3882         /*
3883          * Remove all classes this lock might have:
3884          */
3885         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3886                 /*
3887                  * If the class exists we look it up and zap it:
3888                  */
3889                 class = look_up_lock_class(lock, j);
3890                 if (class)
3891                         zap_class(class);
3892         }
3893         /*
3894          * Debug check: in the end all mapped classes should
3895          * be gone.
3896          */
3897         locked = graph_lock();
3898         for (i = 0; i < CLASSHASH_SIZE; i++) {
3899                 head = classhash_table + i;
3900                 if (list_empty(head))
3901                         continue;
3902                 list_for_each_entry_safe(class, next, head, hash_entry) {
3903                         int match = 0;
3904
3905                         for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3906                                 match |= class == lock->class_cache[j];
3907
3908                         if (unlikely(match)) {
3909                                 if (debug_locks_off_graph_unlock()) {
3910                                         /*
3911                                          * We all just reset everything, how did it match?
3912                                          */
3913                                         WARN_ON(1);
3914                                 }
3915                                 goto out_restore;
3916                         }
3917                 }
3918         }
3919         if (locked)
3920                 graph_unlock();
3921
3922 out_restore:
3923         raw_local_irq_restore(flags);
3924 }
3925
3926 void lockdep_init(void)
3927 {
3928         int i;
3929
3930         /*
3931          * Some architectures have their own start_kernel()
3932          * code which calls lockdep_init(), while we also
3933          * call lockdep_init() from the start_kernel() itself,
3934          * and we want to initialize the hashes only once:
3935          */
3936         if (lockdep_initialized)
3937                 return;
3938
3939         for (i = 0; i < CLASSHASH_SIZE; i++)
3940                 INIT_LIST_HEAD(classhash_table + i);
3941
3942         for (i = 0; i < CHAINHASH_SIZE; i++)
3943                 INIT_LIST_HEAD(chainhash_table + i);
3944
3945         lockdep_initialized = 1;
3946 }
3947
3948 void __init lockdep_info(void)
3949 {
3950         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3951
3952         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3953         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3954         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3955         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3956         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3957         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3958         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3959
3960         printk(" memory used by lock dependency info: %lu kB\n",
3961                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3962                 sizeof(struct list_head) * CLASSHASH_SIZE +
3963                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3964                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3965                 sizeof(struct list_head) * CHAINHASH_SIZE
3966 #ifdef CONFIG_PROVE_LOCKING
3967                 + sizeof(struct circular_queue)
3968 #endif
3969                 ) / 1024
3970                 );
3971
3972         printk(" per task-struct memory footprint: %lu bytes\n",
3973                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3974
3975 #ifdef CONFIG_DEBUG_LOCKDEP
3976         if (lockdep_init_error) {
3977                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3978                 printk("Call stack leading to lockdep invocation was:\n");
3979                 print_stack_trace(&lockdep_init_trace, 0);
3980         }
3981 #endif
3982 }
3983
3984 static void
3985 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3986                      const void *mem_to, struct held_lock *hlock)
3987 {
3988         if (!debug_locks_off())
3989                 return;
3990         if (debug_locks_silent)
3991                 return;
3992
3993         printk("\n");
3994         printk("=========================\n");
3995         printk("[ BUG: held lock freed! ]\n");
3996         printk("-------------------------\n");
3997         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3998                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3999         print_lock(hlock);
4000         lockdep_print_held_locks(curr);
4001
4002         printk("\nstack backtrace:\n");
4003         dump_stack();
4004 }
4005
4006 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4007                                 const void* lock_from, unsigned long lock_len)
4008 {
4009         return lock_from + lock_len <= mem_from ||
4010                 mem_from + mem_len <= lock_from;
4011 }
4012
4013 /*
4014  * Called when kernel memory is freed (or unmapped), or if a lock
4015  * is destroyed or reinitialized - this code checks whether there is
4016  * any held lock in the memory range of <from> to <to>:
4017  */
4018 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4019 {
4020         struct task_struct *curr = current;
4021         struct held_lock *hlock;
4022         unsigned long flags;
4023         int i;
4024
4025         if (unlikely(!debug_locks))
4026                 return;
4027
4028         local_irq_save(flags);
4029         for (i = 0; i < curr->lockdep_depth; i++) {
4030                 hlock = curr->held_locks + i;
4031
4032                 if (not_in_range(mem_from, mem_len, hlock->instance,
4033                                         sizeof(*hlock->instance)))
4034                         continue;
4035
4036                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4037                 break;
4038         }
4039         local_irq_restore(flags);
4040 }
4041 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4042
4043 static void print_held_locks_bug(struct task_struct *curr)
4044 {
4045         if (!debug_locks_off())
4046                 return;
4047         if (debug_locks_silent)
4048                 return;
4049
4050         printk("\n");
4051         printk("=====================================\n");
4052         printk("[ BUG: lock held at task exit time! ]\n");
4053         printk("-------------------------------------\n");
4054         printk("%s/%d is exiting with locks still held!\n",
4055                 curr->comm, task_pid_nr(curr));
4056         lockdep_print_held_locks(curr);
4057
4058         printk("\nstack backtrace:\n");
4059         dump_stack();
4060 }
4061
4062 void debug_check_no_locks_held(struct task_struct *task)
4063 {
4064         if (unlikely(task->lockdep_depth > 0))
4065                 print_held_locks_bug(task);
4066 }
4067
4068 void debug_show_all_locks(void)
4069 {
4070         struct task_struct *g, *p;
4071         int count = 10;
4072         int unlock = 1;
4073
4074         if (unlikely(!debug_locks)) {
4075                 printk("INFO: lockdep is turned off.\n");
4076                 return;
4077         }
4078         printk("\nShowing all locks held in the system:\n");
4079
4080         /*
4081          * Here we try to get the tasklist_lock as hard as possible,
4082          * if not successful after 2 seconds we ignore it (but keep
4083          * trying). This is to enable a debug printout even if a
4084          * tasklist_lock-holding task deadlocks or crashes.
4085          */
4086 retry:
4087         if (!read_trylock(&tasklist_lock)) {
4088                 if (count == 10)
4089                         printk("hm, tasklist_lock locked, retrying... ");
4090                 if (count) {
4091                         count--;
4092                         printk(" #%d", 10-count);
4093                         mdelay(200);
4094                         goto retry;
4095                 }
4096                 printk(" ignoring it.\n");
4097                 unlock = 0;
4098         } else {
4099                 if (count != 10)
4100                         printk(KERN_CONT " locked it.\n");
4101         }
4102
4103         do_each_thread(g, p) {
4104                 /*
4105                  * It's not reliable to print a task's held locks
4106                  * if it's not sleeping (or if it's not the current
4107                  * task):
4108                  */
4109                 if (p->state == TASK_RUNNING && p != current)
4110                         continue;
4111                 if (p->lockdep_depth)
4112                         lockdep_print_held_locks(p);
4113                 if (!unlock)
4114                         if (read_trylock(&tasklist_lock))
4115                                 unlock = 1;
4116         } while_each_thread(g, p);
4117
4118         printk("\n");
4119         printk("=============================================\n\n");
4120
4121         if (unlock)
4122                 read_unlock(&tasklist_lock);
4123 }
4124 EXPORT_SYMBOL_GPL(debug_show_all_locks);
4125
4126 /*
4127  * Careful: only use this function if you are sure that
4128  * the task cannot run in parallel!
4129  */
4130 void debug_show_held_locks(struct task_struct *task)
4131 {
4132         if (unlikely(!debug_locks)) {
4133                 printk("INFO: lockdep is turned off.\n");
4134                 return;
4135         }
4136         lockdep_print_held_locks(task);
4137 }
4138 EXPORT_SYMBOL_GPL(debug_show_held_locks);
4139
4140 void lockdep_sys_exit(void)
4141 {
4142         struct task_struct *curr = current;
4143
4144         if (unlikely(curr->lockdep_depth)) {
4145                 if (!debug_locks_off())
4146                         return;
4147                 printk("\n");
4148                 printk("================================================\n");
4149                 printk("[ BUG: lock held when returning to user space! ]\n");
4150                 printk("------------------------------------------------\n");
4151                 printk("%s/%d is leaving the kernel with locks still held!\n",
4152                                 curr->comm, curr->pid);
4153                 lockdep_print_held_locks(curr);
4154         }
4155 }
4156
4157 void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4158 {
4159         struct task_struct *curr = current;
4160
4161 #ifndef CONFIG_PROVE_RCU_REPEATEDLY
4162         if (!debug_locks_off())
4163                 return;
4164 #endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4165         /* Note: the following can be executed concurrently, so be careful. */
4166         printk("\n");
4167         printk("===============================\n");
4168         printk("[ INFO: suspicious RCU usage. ]\n");
4169         printk("-------------------------------\n");
4170         printk("%s:%d %s!\n", file, line, s);
4171         printk("\nother info that might help us debug this:\n\n");
4172         printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
4173         lockdep_print_held_locks(curr);
4174         printk("\nstack backtrace:\n");
4175         dump_stack();
4176 }
4177 EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);