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