lockdep: Fix style nits
[linux-2.6.git] / kernel / lockdep.c
1 /*
2  * kernel/lockdep.c
3  *
4  * Runtime locking correctness validator
5  *
6  * Started by Ingo Molnar:
7  *
8  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
10  *
11  * this code maps all the lock dependencies as they occur in a live kernel
12  * and will warn about the following classes of locking bugs:
13  *
14  * - lock inversion scenarios
15  * - circular lock dependencies
16  * - hardirq/softirq safe/unsafe locking bugs
17  *
18  * Bugs are reported even if the current locking scenario does not cause
19  * any deadlock at this point.
20  *
21  * I.e. if anytime in the past two locks were taken in a different order,
22  * even if it happened for another task, even if those were different
23  * locks (but of the same class as this lock), this code will detect it.
24  *
25  * Thanks to Arjan van de Ven for coming up with the initial idea of
26  * mapping lock dependencies runtime.
27  */
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 #include <linux/spinlock.h>
36 #include <linux/kallsyms.h>
37 #include <linux/interrupt.h>
38 #include <linux/stacktrace.h>
39 #include <linux/debug_locks.h>
40 #include <linux/irqflags.h>
41 #include <linux/utsname.h>
42 #include <linux/hash.h>
43 #include <linux/ftrace.h>
44 #include <linux/stringify.h>
45 #include <linux/bitops.h>
46
47 #include <asm/sections.h>
48
49 #include "lockdep_internals.h"
50
51 #define CREATE_TRACE_POINTS
52 #include <trace/events/lockdep.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 int lock_point(unsigned long points[], unsigned long ip)
146 {
147         int i;
148
149         for (i = 0; i < LOCKSTAT_POINTS; i++) {
150                 if (points[i] == 0) {
151                         points[i] = ip;
152                         break;
153                 }
154                 if (points[i] == ip)
155                         break;
156         }
157
158         return i;
159 }
160
161 static void lock_time_inc(struct lock_time *lt, s64 time)
162 {
163         if (time > lt->max)
164                 lt->max = time;
165
166         if (time < lt->min || !lt->min)
167                 lt->min = time;
168
169         lt->total += time;
170         lt->nr++;
171 }
172
173 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
174 {
175         dst->min += src->min;
176         dst->max += src->max;
177         dst->total += src->total;
178         dst->nr += src->nr;
179 }
180
181 struct lock_class_stats lock_stats(struct lock_class *class)
182 {
183         struct lock_class_stats stats;
184         int cpu, i;
185
186         memset(&stats, 0, sizeof(struct lock_class_stats));
187         for_each_possible_cpu(cpu) {
188                 struct lock_class_stats *pcs =
189                         &per_cpu(lock_stats, cpu)[class - lock_classes];
190
191                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
192                         stats.contention_point[i] += pcs->contention_point[i];
193
194                 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
195                         stats.contending_point[i] += pcs->contending_point[i];
196
197                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
198                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
199
200                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
201                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
202
203                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
204                         stats.bounces[i] += pcs->bounces[i];
205         }
206
207         return stats;
208 }
209
210 void clear_lock_stats(struct lock_class *class)
211 {
212         int cpu;
213
214         for_each_possible_cpu(cpu) {
215                 struct lock_class_stats *cpu_stats =
216                         &per_cpu(lock_stats, cpu)[class - lock_classes];
217
218                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
219         }
220         memset(class->contention_point, 0, sizeof(class->contention_point));
221         memset(class->contending_point, 0, sizeof(class->contending_point));
222 }
223
224 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
225 {
226         return &get_cpu_var(lock_stats)[class - lock_classes];
227 }
228
229 static void put_lock_stats(struct lock_class_stats *stats)
230 {
231         put_cpu_var(lock_stats);
232 }
233
234 static void lock_release_holdtime(struct held_lock *hlock)
235 {
236         struct lock_class_stats *stats;
237         s64 holdtime;
238
239         if (!lock_stat)
240                 return;
241
242         holdtime = sched_clock() - hlock->holdtime_stamp;
243
244         stats = get_lock_stats(hlock_class(hlock));
245         if (hlock->read)
246                 lock_time_inc(&stats->read_holdtime, holdtime);
247         else
248                 lock_time_inc(&stats->write_holdtime, holdtime);
249         put_lock_stats(stats);
250 }
251 #else
252 static inline void lock_release_holdtime(struct held_lock *hlock)
253 {
254 }
255 #endif
256
257 /*
258  * We keep a global list of all lock classes. The list only grows,
259  * never shrinks. The list is only accessed with the lockdep
260  * spinlock lock held.
261  */
262 LIST_HEAD(all_lock_classes);
263
264 /*
265  * The lockdep classes are in a hash-table as well, for fast lookup:
266  */
267 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
268 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
269 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
270 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
271
272 static struct list_head classhash_table[CLASSHASH_SIZE];
273
274 /*
275  * We put the lock dependency chains into a hash-table as well, to cache
276  * their existence:
277  */
278 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
279 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
280 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
281 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
282
283 static struct list_head chainhash_table[CHAINHASH_SIZE];
284
285 /*
286  * The hash key of the lock dependency chains is a hash itself too:
287  * it's a hash of all locks taken up to that lock, including that lock.
288  * It's a 64-bit hash, because it's important for the keys to be
289  * unique.
290  */
291 #define iterate_chain_key(key1, key2) \
292         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
293         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
294         (key2))
295
296 void lockdep_off(void)
297 {
298         current->lockdep_recursion++;
299 }
300 EXPORT_SYMBOL(lockdep_off);
301
302 void lockdep_on(void)
303 {
304         current->lockdep_recursion--;
305 }
306 EXPORT_SYMBOL(lockdep_on);
307
308 /*
309  * Debugging switches:
310  */
311
312 #define VERBOSE                 0
313 #define VERY_VERBOSE            0
314
315 #if VERBOSE
316 # define HARDIRQ_VERBOSE        1
317 # define SOFTIRQ_VERBOSE        1
318 # define RECLAIM_VERBOSE        1
319 #else
320 # define HARDIRQ_VERBOSE        0
321 # define SOFTIRQ_VERBOSE        0
322 # define RECLAIM_VERBOSE        0
323 #endif
324
325 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
326 /*
327  * Quick filtering for interesting events:
328  */
329 static int class_filter(struct lock_class *class)
330 {
331 #if 0
332         /* Example */
333         if (class->name_version == 1 &&
334                         !strcmp(class->name, "lockname"))
335                 return 1;
336         if (class->name_version == 1 &&
337                         !strcmp(class->name, "&struct->lockfield"))
338                 return 1;
339 #endif
340         /* Filter everything else. 1 would be to allow everything else */
341         return 0;
342 }
343 #endif
344
345 static int verbose(struct lock_class *class)
346 {
347 #if VERBOSE
348         return class_filter(class);
349 #endif
350         return 0;
351 }
352
353 /*
354  * Stack-trace: tightly packed array of stack backtrace
355  * addresses. Protected by the graph_lock.
356  */
357 unsigned long nr_stack_trace_entries;
358 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
359
360 static int save_trace(struct stack_trace *trace)
361 {
362         trace->nr_entries = 0;
363         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
364         trace->entries = stack_trace + nr_stack_trace_entries;
365
366         trace->skip = 3;
367
368         save_stack_trace(trace);
369
370         /*
371          * Some daft arches put -1 at the end to indicate its a full trace.
372          *
373          * <rant> this is buggy anyway, since it takes a whole extra entry so a
374          * complete trace that maxes out the entries provided will be reported
375          * as incomplete, friggin useless </rant>
376          */
377         if (trace->entries[trace->nr_entries-1] == ULONG_MAX)
378                 trace->nr_entries--;
379
380         trace->max_entries = trace->nr_entries;
381
382         nr_stack_trace_entries += trace->nr_entries;
383
384         if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
385                 if (!debug_locks_off_graph_unlock())
386                         return 0;
387
388                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
389                 printk("turning off the locking correctness validator.\n");
390                 dump_stack();
391
392                 return 0;
393         }
394
395         return 1;
396 }
397
398 unsigned int nr_hardirq_chains;
399 unsigned int nr_softirq_chains;
400 unsigned int nr_process_chains;
401 unsigned int max_lockdep_depth;
402 unsigned int max_recursion_depth;
403
404 #ifdef CONFIG_DEBUG_LOCKDEP
405 /*
406  * We cannot printk in early bootup code. Not even early_printk()
407  * might work. So we mark any initialization errors and printk
408  * about it later on, in lockdep_info().
409  */
410 static int lockdep_init_error;
411 static unsigned long lockdep_init_trace_data[20];
412 static struct stack_trace lockdep_init_trace = {
413         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
414         .entries = lockdep_init_trace_data,
415 };
416
417 /*
418  * Various lockdep statistics:
419  */
420 atomic_t chain_lookup_hits;
421 atomic_t chain_lookup_misses;
422 atomic_t hardirqs_on_events;
423 atomic_t hardirqs_off_events;
424 atomic_t redundant_hardirqs_on;
425 atomic_t redundant_hardirqs_off;
426 atomic_t softirqs_on_events;
427 atomic_t softirqs_off_events;
428 atomic_t redundant_softirqs_on;
429 atomic_t redundant_softirqs_off;
430 atomic_t nr_unused_locks;
431 atomic_t nr_cyclic_checks;
432 atomic_t nr_cyclic_check_recursions;
433 atomic_t nr_find_usage_forwards_checks;
434 atomic_t nr_find_usage_forwards_recursions;
435 atomic_t nr_find_usage_backwards_checks;
436 atomic_t nr_find_usage_backwards_recursions;
437 #endif
438
439 /*
440  * Locking printouts:
441  */
442
443 #define __USAGE(__STATE)                                                \
444         [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
445         [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
446         [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
447         [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
448
449 static const char *usage_str[] =
450 {
451 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
452 #include "lockdep_states.h"
453 #undef LOCKDEP_STATE
454         [LOCK_USED] = "INITIAL USE",
455 };
456
457 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
458 {
459         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
460 }
461
462 static inline unsigned long lock_flag(enum lock_usage_bit bit)
463 {
464         return 1UL << bit;
465 }
466
467 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
468 {
469         char c = '.';
470
471         if (class->usage_mask & lock_flag(bit + 2))
472                 c = '+';
473         if (class->usage_mask & lock_flag(bit)) {
474                 c = '-';
475                 if (class->usage_mask & lock_flag(bit + 2))
476                         c = '?';
477         }
478
479         return c;
480 }
481
482 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
483 {
484         int i = 0;
485
486 #define LOCKDEP_STATE(__STATE)                                          \
487         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
488         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
489 #include "lockdep_states.h"
490 #undef LOCKDEP_STATE
491
492         usage[i] = '\0';
493 }
494
495 static void print_lock_name(struct lock_class *class)
496 {
497         char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
498         const char *name;
499
500         get_usage_chars(class, usage);
501
502         name = class->name;
503         if (!name) {
504                 name = __get_key_name(class->key, str);
505                 printk(" (%s", name);
506         } else {
507                 printk(" (%s", name);
508                 if (class->name_version > 1)
509                         printk("#%d", class->name_version);
510                 if (class->subclass)
511                         printk("/%d", class->subclass);
512         }
513         printk("){%s}", usage);
514 }
515
516 static void print_lockdep_cache(struct lockdep_map *lock)
517 {
518         const char *name;
519         char str[KSYM_NAME_LEN];
520
521         name = lock->name;
522         if (!name)
523                 name = __get_key_name(lock->key->subkeys, str);
524
525         printk("%s", name);
526 }
527
528 static void print_lock(struct held_lock *hlock)
529 {
530         print_lock_name(hlock_class(hlock));
531         printk(", at: ");
532         print_ip_sym(hlock->acquire_ip);
533 }
534
535 static void lockdep_print_held_locks(struct task_struct *curr)
536 {
537         int i, depth = curr->lockdep_depth;
538
539         if (!depth) {
540                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
541                 return;
542         }
543         printk("%d lock%s held by %s/%d:\n",
544                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
545
546         for (i = 0; i < depth; i++) {
547                 printk(" #%d: ", i);
548                 print_lock(curr->held_locks + i);
549         }
550 }
551
552 static void print_kernel_version(void)
553 {
554         printk("%s %.*s\n", init_utsname()->release,
555                 (int)strcspn(init_utsname()->version, " "),
556                 init_utsname()->version);
557 }
558
559 static int very_verbose(struct lock_class *class)
560 {
561 #if VERY_VERBOSE
562         return class_filter(class);
563 #endif
564         return 0;
565 }
566
567 /*
568  * Is this the address of a static object:
569  */
570 static int static_obj(void *obj)
571 {
572         unsigned long start = (unsigned long) &_stext,
573                       end   = (unsigned long) &_end,
574                       addr  = (unsigned long) obj;
575 #ifdef CONFIG_SMP
576         int i;
577 #endif
578
579         /*
580          * static variable?
581          */
582         if ((addr >= start) && (addr < end))
583                 return 1;
584
585 #ifdef CONFIG_SMP
586         /*
587          * percpu var?
588          */
589         for_each_possible_cpu(i) {
590                 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
591                 end   = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
592                                         + per_cpu_offset(i);
593
594                 if ((addr >= start) && (addr < end))
595                         return 1;
596         }
597 #endif
598
599         /*
600          * module var?
601          */
602         return is_module_address(addr);
603 }
604
605 /*
606  * To make lock name printouts unique, we calculate a unique
607  * class->name_version generation counter:
608  */
609 static int count_matching_names(struct lock_class *new_class)
610 {
611         struct lock_class *class;
612         int count = 0;
613
614         if (!new_class->name)
615                 return 0;
616
617         list_for_each_entry(class, &all_lock_classes, lock_entry) {
618                 if (new_class->key - new_class->subclass == class->key)
619                         return class->name_version;
620                 if (class->name && !strcmp(class->name, new_class->name))
621                         count = max(count, class->name_version);
622         }
623
624         return count + 1;
625 }
626
627 /*
628  * Register a lock's class in the hash-table, if the class is not present
629  * yet. Otherwise we look it up. We cache the result in the lock object
630  * itself, so actual lookup of the hash should be once per lock object.
631  */
632 static inline struct lock_class *
633 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
634 {
635         struct lockdep_subclass_key *key;
636         struct list_head *hash_head;
637         struct lock_class *class;
638
639 #ifdef CONFIG_DEBUG_LOCKDEP
640         /*
641          * If the architecture calls into lockdep before initializing
642          * the hashes then we'll warn about it later. (we cannot printk
643          * right now)
644          */
645         if (unlikely(!lockdep_initialized)) {
646                 lockdep_init();
647                 lockdep_init_error = 1;
648                 save_stack_trace(&lockdep_init_trace);
649         }
650 #endif
651
652         /*
653          * Static locks do not have their class-keys yet - for them the key
654          * is the lock object itself:
655          */
656         if (unlikely(!lock->key))
657                 lock->key = (void *)lock;
658
659         /*
660          * NOTE: the class-key must be unique. For dynamic locks, a static
661          * lock_class_key variable is passed in through the mutex_init()
662          * (or spin_lock_init()) call - which acts as the key. For static
663          * locks we use the lock object itself as the key.
664          */
665         BUILD_BUG_ON(sizeof(struct lock_class_key) >
666                         sizeof(struct lockdep_map));
667
668         key = lock->key->subkeys + subclass;
669
670         hash_head = classhashentry(key);
671
672         /*
673          * We can walk the hash lockfree, because the hash only
674          * grows, and we are careful when adding entries to the end:
675          */
676         list_for_each_entry(class, hash_head, hash_entry) {
677                 if (class->key == key) {
678                         WARN_ON_ONCE(class->name != lock->name);
679                         return class;
680                 }
681         }
682
683         return NULL;
684 }
685
686 /*
687  * Register a lock's class in the hash-table, if the class is not present
688  * yet. Otherwise we look it up. We cache the result in the lock object
689  * itself, so actual lookup of the hash should be once per lock object.
690  */
691 static inline struct lock_class *
692 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
693 {
694         struct lockdep_subclass_key *key;
695         struct list_head *hash_head;
696         struct lock_class *class;
697         unsigned long flags;
698
699         class = look_up_lock_class(lock, subclass);
700         if (likely(class))
701                 return class;
702
703         /*
704          * Debug-check: all keys must be persistent!
705          */
706         if (!static_obj(lock->key)) {
707                 debug_locks_off();
708                 printk("INFO: trying to register non-static key.\n");
709                 printk("the code is fine but needs lockdep annotation.\n");
710                 printk("turning off the locking correctness validator.\n");
711                 dump_stack();
712
713                 return NULL;
714         }
715
716         key = lock->key->subkeys + subclass;
717         hash_head = classhashentry(key);
718
719         raw_local_irq_save(flags);
720         if (!graph_lock()) {
721                 raw_local_irq_restore(flags);
722                 return NULL;
723         }
724         /*
725          * We have to do the hash-walk again, to avoid races
726          * with another CPU:
727          */
728         list_for_each_entry(class, hash_head, hash_entry)
729                 if (class->key == key)
730                         goto out_unlock_set;
731         /*
732          * Allocate a new key from the static array, and add it to
733          * the hash:
734          */
735         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
736                 if (!debug_locks_off_graph_unlock()) {
737                         raw_local_irq_restore(flags);
738                         return NULL;
739                 }
740                 raw_local_irq_restore(flags);
741
742                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
743                 printk("turning off the locking correctness validator.\n");
744                 dump_stack();
745                 return NULL;
746         }
747         class = lock_classes + nr_lock_classes++;
748         debug_atomic_inc(&nr_unused_locks);
749         class->key = key;
750         class->name = lock->name;
751         class->subclass = subclass;
752         INIT_LIST_HEAD(&class->lock_entry);
753         INIT_LIST_HEAD(&class->locks_before);
754         INIT_LIST_HEAD(&class->locks_after);
755         class->name_version = count_matching_names(class);
756         /*
757          * We use RCU's safe list-add method to make
758          * parallel walking of the hash-list safe:
759          */
760         list_add_tail_rcu(&class->hash_entry, hash_head);
761         /*
762          * Add it to the global list of classes:
763          */
764         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
765
766         if (verbose(class)) {
767                 graph_unlock();
768                 raw_local_irq_restore(flags);
769
770                 printk("\nnew class %p: %s", class->key, class->name);
771                 if (class->name_version > 1)
772                         printk("#%d", class->name_version);
773                 printk("\n");
774                 dump_stack();
775
776                 raw_local_irq_save(flags);
777                 if (!graph_lock()) {
778                         raw_local_irq_restore(flags);
779                         return NULL;
780                 }
781         }
782 out_unlock_set:
783         graph_unlock();
784         raw_local_irq_restore(flags);
785
786         if (!subclass || force)
787                 lock->class_cache = class;
788
789         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
790                 return NULL;
791
792         return class;
793 }
794
795 #ifdef CONFIG_PROVE_LOCKING
796 /*
797  * Allocate a lockdep entry. (assumes the graph_lock held, returns
798  * with NULL on failure)
799  */
800 static struct lock_list *alloc_list_entry(void)
801 {
802         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
803                 if (!debug_locks_off_graph_unlock())
804                         return NULL;
805
806                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
807                 printk("turning off the locking correctness validator.\n");
808                 dump_stack();
809                 return NULL;
810         }
811         return list_entries + nr_list_entries++;
812 }
813
814 /*
815  * Add a new dependency to the head of the list:
816  */
817 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
818                             struct list_head *head, unsigned long ip, int distance)
819 {
820         struct lock_list *entry;
821         /*
822          * Lock not present yet - get a new dependency struct and
823          * add it to the list:
824          */
825         entry = alloc_list_entry();
826         if (!entry)
827                 return 0;
828
829         if (!save_trace(&entry->trace))
830                 return 0;
831
832         entry->class = this;
833         entry->distance = distance;
834         /*
835          * Since we never remove from the dependency list, the list can
836          * be walked lockless by other CPUs, it's only allocation
837          * that must be protected by the spinlock. But this also means
838          * we must make new entries visible only once writes to the
839          * entry become visible - hence the RCU op:
840          */
841         list_add_tail_rcu(&entry->entry, head);
842
843         return 1;
844 }
845
846 /*
847  * For good efficiency of modular, we use power of 2
848  */
849 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
850 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
851
852 /*
853  * The circular_queue and helpers is used to implement the
854  * breadth-first search(BFS)algorithem, by which we can build
855  * the shortest path from the next lock to be acquired to the
856  * previous held lock if there is a circular between them.
857  */
858 struct circular_queue {
859         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
860         unsigned int  front, rear;
861 };
862
863 static struct circular_queue lock_cq;
864 static unsigned long bfs_accessed[BITS_TO_LONGS(MAX_LOCKDEP_ENTRIES)];
865
866 unsigned int max_bfs_queue_depth;
867
868 static inline void __cq_init(struct circular_queue *cq)
869 {
870         cq->front = cq->rear = 0;
871         bitmap_zero(bfs_accessed, MAX_LOCKDEP_ENTRIES);
872 }
873
874 static inline int __cq_empty(struct circular_queue *cq)
875 {
876         return (cq->front == cq->rear);
877 }
878
879 static inline int __cq_full(struct circular_queue *cq)
880 {
881         return ((cq->rear + 1) & CQ_MASK) == cq->front;
882 }
883
884 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
885 {
886         if (__cq_full(cq))
887                 return -1;
888
889         cq->element[cq->rear] = elem;
890         cq->rear = (cq->rear + 1) & CQ_MASK;
891         return 0;
892 }
893
894 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
895 {
896         if (__cq_empty(cq))
897                 return -1;
898
899         *elem = cq->element[cq->front];
900         cq->front = (cq->front + 1) & CQ_MASK;
901         return 0;
902 }
903
904 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
905 {
906         return (cq->rear - cq->front) & CQ_MASK;
907 }
908
909 static inline void mark_lock_accessed(struct lock_list *lock,
910                                         struct lock_list *parent)
911 {
912         unsigned long nr;
913
914         nr = lock - list_entries;
915         WARN_ON(nr >= nr_list_entries);
916         lock->parent = parent;
917         set_bit(nr, bfs_accessed);
918 }
919
920 static inline unsigned long lock_accessed(struct lock_list *lock)
921 {
922         unsigned long nr;
923
924         nr = lock - list_entries;
925         WARN_ON(nr >= nr_list_entries);
926         return test_bit(nr, bfs_accessed);
927 }
928
929 static inline struct lock_list *get_lock_parent(struct lock_list *child)
930 {
931         return child->parent;
932 }
933
934 static inline int get_lock_depth(struct lock_list *child)
935 {
936         int depth = 0;
937         struct lock_list *parent;
938
939         while ((parent = get_lock_parent(child))) {
940                 child = parent;
941                 depth++;
942         }
943         return depth;
944 }
945
946 static int __bfs(struct lock_list *source_entry,
947                  void *data,
948                  int (*match)(struct lock_list *entry, void *data),
949                  struct lock_list **target_entry,
950                  int forward)
951 {
952         struct lock_list *entry;
953         struct list_head *head;
954         struct circular_queue *cq = &lock_cq;
955         int ret = 1;
956
957         if (match(source_entry, data)) {
958                 *target_entry = source_entry;
959                 ret = 0;
960                 goto exit;
961         }
962
963         if (forward)
964                 head = &source_entry->class->locks_after;
965         else
966                 head = &source_entry->class->locks_before;
967
968         if (list_empty(head))
969                 goto exit;
970
971         __cq_init(cq);
972         __cq_enqueue(cq, (unsigned long)source_entry);
973
974         while (!__cq_empty(cq)) {
975                 struct lock_list *lock;
976
977                 __cq_dequeue(cq, (unsigned long *)&lock);
978
979                 if (!lock->class) {
980                         ret = -2;
981                         goto exit;
982                 }
983
984                 if (forward)
985                         head = &lock->class->locks_after;
986                 else
987                         head = &lock->class->locks_before;
988
989                 list_for_each_entry(entry, head, entry) {
990                         if (!lock_accessed(entry)) {
991                                 unsigned int cq_depth;
992                                 mark_lock_accessed(entry, lock);
993                                 if (match(entry, data)) {
994                                         *target_entry = entry;
995                                         ret = 0;
996                                         goto exit;
997                                 }
998
999                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
1000                                         ret = -1;
1001                                         goto exit;
1002                                 }
1003                                 cq_depth = __cq_get_elem_count(cq);
1004                                 if (max_bfs_queue_depth < cq_depth)
1005                                         max_bfs_queue_depth = cq_depth;
1006                         }
1007                 }
1008         }
1009 exit:
1010         return ret;
1011 }
1012
1013 static inline int __bfs_forwards(struct lock_list *src_entry,
1014                         void *data,
1015                         int (*match)(struct lock_list *entry, void *data),
1016                         struct lock_list **target_entry)
1017 {
1018         return __bfs(src_entry, data, match, target_entry, 1);
1019
1020 }
1021
1022 static inline int __bfs_backwards(struct lock_list *src_entry,
1023                         void *data,
1024                         int (*match)(struct lock_list *entry, void *data),
1025                         struct lock_list **target_entry)
1026 {
1027         return __bfs(src_entry, data, match, target_entry, 0);
1028
1029 }
1030
1031 /*
1032  * Recursive, forwards-direction lock-dependency checking, used for
1033  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1034  * checking.
1035  */
1036
1037 /*
1038  * Print a dependency chain entry (this is only done when a deadlock
1039  * has been detected):
1040  */
1041 static noinline int
1042 print_circular_bug_entry(struct lock_list *target, int depth)
1043 {
1044         if (debug_locks_silent)
1045                 return 0;
1046         printk("\n-> #%u", depth);
1047         print_lock_name(target->class);
1048         printk(":\n");
1049         print_stack_trace(&target->trace, 6);
1050
1051         return 0;
1052 }
1053
1054 /*
1055  * When a circular dependency is detected, print the
1056  * header first:
1057  */
1058 static noinline int
1059 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1060                         struct held_lock *check_src,
1061                         struct held_lock *check_tgt)
1062 {
1063         struct task_struct *curr = current;
1064
1065         if (debug_locks_silent)
1066                 return 0;
1067
1068         printk("\n=======================================================\n");
1069         printk(  "[ INFO: possible circular locking dependency detected ]\n");
1070         print_kernel_version();
1071         printk(  "-------------------------------------------------------\n");
1072         printk("%s/%d is trying to acquire lock:\n",
1073                 curr->comm, task_pid_nr(curr));
1074         print_lock(check_src);
1075         printk("\nbut task is already holding lock:\n");
1076         print_lock(check_tgt);
1077         printk("\nwhich lock already depends on the new lock.\n\n");
1078         printk("\nthe existing dependency chain (in reverse order) is:\n");
1079
1080         print_circular_bug_entry(entry, depth);
1081
1082         return 0;
1083 }
1084
1085 static inline int class_equal(struct lock_list *entry, void *data)
1086 {
1087         return entry->class == data;
1088 }
1089
1090 static noinline int print_circular_bug(struct lock_list *this,
1091                                 struct lock_list *target,
1092                                 struct held_lock *check_src,
1093                                 struct held_lock *check_tgt)
1094 {
1095         struct task_struct *curr = current;
1096         struct lock_list *parent;
1097         int depth;
1098
1099         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1100                 return 0;
1101
1102         if (!save_trace(&this->trace))
1103                 return 0;
1104
1105         depth = get_lock_depth(target);
1106
1107         print_circular_bug_header(target, depth, check_src, check_tgt);
1108
1109         parent = get_lock_parent(target);
1110
1111         while (parent) {
1112                 print_circular_bug_entry(parent, --depth);
1113                 parent = get_lock_parent(parent);
1114         }
1115
1116         printk("\nother info that might help us debug this:\n\n");
1117         lockdep_print_held_locks(curr);
1118
1119         printk("\nstack backtrace:\n");
1120         dump_stack();
1121
1122         return 0;
1123 }
1124
1125 static noinline int print_bfs_bug(int ret)
1126 {
1127         if (!debug_locks_off_graph_unlock())
1128                 return 0;
1129
1130         WARN(1, "lockdep bfs error:%d\n", ret);
1131
1132         return 0;
1133 }
1134
1135 static int noop_count(struct lock_list *entry, void *data)
1136 {
1137         (*(unsigned long *)data)++;
1138         return 0;
1139 }
1140
1141 unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1142 {
1143         unsigned long  count = 0;
1144         struct lock_list *uninitialized_var(target_entry);
1145
1146         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1147
1148         return count;
1149 }
1150 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1151 {
1152         unsigned long ret, flags;
1153         struct lock_list this;
1154
1155         this.parent = NULL;
1156         this.class = class;
1157
1158         local_irq_save(flags);
1159         __raw_spin_lock(&lockdep_lock);
1160         ret = __lockdep_count_forward_deps(&this);
1161         __raw_spin_unlock(&lockdep_lock);
1162         local_irq_restore(flags);
1163
1164         return ret;
1165 }
1166
1167 unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1168 {
1169         unsigned long  count = 0;
1170         struct lock_list *uninitialized_var(target_entry);
1171
1172         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1173
1174         return count;
1175 }
1176
1177 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1178 {
1179         unsigned long ret, flags;
1180         struct lock_list this;
1181
1182         this.parent = NULL;
1183         this.class = class;
1184
1185         local_irq_save(flags);
1186         __raw_spin_lock(&lockdep_lock);
1187         ret = __lockdep_count_backward_deps(&this);
1188         __raw_spin_unlock(&lockdep_lock);
1189         local_irq_restore(flags);
1190
1191         return ret;
1192 }
1193
1194 /*
1195  * Prove that the dependency graph starting at <entry> can not
1196  * lead to <target>. Print an error and return 0 if it does.
1197  */
1198 static noinline int
1199 check_noncircular(struct lock_list *root, struct lock_class *target,
1200                 struct lock_list **target_entry)
1201 {
1202         int result;
1203
1204         debug_atomic_inc(&nr_cyclic_checks);
1205
1206         result = __bfs_forwards(root, target, class_equal, target_entry);
1207
1208         return result;
1209 }
1210
1211 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1212 /*
1213  * Forwards and backwards subgraph searching, for the purposes of
1214  * proving that two subgraphs can be connected by a new dependency
1215  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1216  */
1217
1218 static inline int usage_match(struct lock_list *entry, void *bit)
1219 {
1220         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1221 }
1222
1223
1224
1225 /*
1226  * Find a node in the forwards-direction dependency sub-graph starting
1227  * at @root->class that matches @bit.
1228  *
1229  * Return 0 if such a node exists in the subgraph, and put that node
1230  * into *@target_entry.
1231  *
1232  * Return 1 otherwise and keep *@target_entry unchanged.
1233  * Return <0 on error.
1234  */
1235 static int
1236 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1237                         struct lock_list **target_entry)
1238 {
1239         int result;
1240
1241         debug_atomic_inc(&nr_find_usage_forwards_checks);
1242
1243         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1244
1245         return result;
1246 }
1247
1248 /*
1249  * Find a node in the backwards-direction dependency sub-graph starting
1250  * at @root->class that matches @bit.
1251  *
1252  * Return 0 if such a node exists in the subgraph, and put that node
1253  * into *@target_entry.
1254  *
1255  * Return 1 otherwise and keep *@target_entry unchanged.
1256  * Return <0 on error.
1257  */
1258 static int
1259 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1260                         struct lock_list **target_entry)
1261 {
1262         int result;
1263
1264         debug_atomic_inc(&nr_find_usage_backwards_checks);
1265
1266         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1267
1268         return result;
1269 }
1270
1271 static void print_lock_class_header(struct lock_class *class, int depth)
1272 {
1273         int bit;
1274
1275         printk("%*s->", depth, "");
1276         print_lock_name(class);
1277         printk(" ops: %lu", class->ops);
1278         printk(" {\n");
1279
1280         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1281                 if (class->usage_mask & (1 << bit)) {
1282                         int len = depth;
1283
1284                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1285                         len += printk(" at:\n");
1286                         print_stack_trace(class->usage_traces + bit, len);
1287                 }
1288         }
1289         printk("%*s }\n", depth, "");
1290
1291         printk("%*s ... key      at: ",depth,"");
1292         print_ip_sym((unsigned long)class->key);
1293 }
1294
1295 /*
1296  * printk the shortest lock dependencies from @start to @end in reverse order:
1297  */
1298 static void __used
1299 print_shortest_lock_dependencies(struct lock_list *leaf,
1300                                 struct lock_list *root)
1301 {
1302         struct lock_list *entry = leaf;
1303         int depth;
1304
1305         /*compute depth from generated tree by BFS*/
1306         depth = get_lock_depth(leaf);
1307
1308         do {
1309                 print_lock_class_header(entry->class, depth);
1310                 printk("%*s ... acquired at:\n", depth, "");
1311                 print_stack_trace(&entry->trace, 2);
1312                 printk("\n");
1313
1314                 if (depth == 0 && (entry != root)) {
1315                         printk("lockdep:%s bad BFS generated tree\n", __func__);
1316                         break;
1317                 }
1318
1319                 entry = get_lock_parent(entry);
1320                 depth--;
1321         } while (entry && (depth >= 0));
1322
1323         return;
1324 }
1325
1326 static int
1327 print_bad_irq_dependency(struct task_struct *curr,
1328                          struct lock_list *prev_root,
1329                          struct lock_list *next_root,
1330                          struct lock_list *backwards_entry,
1331                          struct lock_list *forwards_entry,
1332                          struct held_lock *prev,
1333                          struct held_lock *next,
1334                          enum lock_usage_bit bit1,
1335                          enum lock_usage_bit bit2,
1336                          const char *irqclass)
1337 {
1338         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1339                 return 0;
1340
1341         printk("\n======================================================\n");
1342         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1343                 irqclass, irqclass);
1344         print_kernel_version();
1345         printk(  "------------------------------------------------------\n");
1346         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1347                 curr->comm, task_pid_nr(curr),
1348                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1349                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1350                 curr->hardirqs_enabled,
1351                 curr->softirqs_enabled);
1352         print_lock(next);
1353
1354         printk("\nand this task is already holding:\n");
1355         print_lock(prev);
1356         printk("which would create a new lock dependency:\n");
1357         print_lock_name(hlock_class(prev));
1358         printk(" ->");
1359         print_lock_name(hlock_class(next));
1360         printk("\n");
1361
1362         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1363                 irqclass);
1364         print_lock_name(backwards_entry->class);
1365         printk("\n... which became %s-irq-safe at:\n", irqclass);
1366
1367         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1368
1369         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1370         print_lock_name(forwards_entry->class);
1371         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1372         printk("...");
1373
1374         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1375
1376         printk("\nother info that might help us debug this:\n\n");
1377         lockdep_print_held_locks(curr);
1378
1379         printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1380         printk(" and the holding lock:\n");
1381         if (!save_trace(&prev_root->trace))
1382                 return 0;
1383         print_shortest_lock_dependencies(backwards_entry, prev_root);
1384
1385         printk("\nthe dependencies between the lock to be acquired");
1386         printk(" and %s-irq-unsafe lock:\n", irqclass);
1387         if (!save_trace(&next_root->trace))
1388                 return 0;
1389         print_shortest_lock_dependencies(forwards_entry, next_root);
1390
1391         printk("\nstack backtrace:\n");
1392         dump_stack();
1393
1394         return 0;
1395 }
1396
1397 static int
1398 check_usage(struct task_struct *curr, struct held_lock *prev,
1399             struct held_lock *next, enum lock_usage_bit bit_backwards,
1400             enum lock_usage_bit bit_forwards, const char *irqclass)
1401 {
1402         int ret;
1403         struct lock_list this, that;
1404         struct lock_list *uninitialized_var(target_entry);
1405         struct lock_list *uninitialized_var(target_entry1);
1406
1407         this.parent = NULL;
1408
1409         this.class = hlock_class(prev);
1410         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1411         if (ret < 0)
1412                 return print_bfs_bug(ret);
1413         if (ret == 1)
1414                 return ret;
1415
1416         that.parent = NULL;
1417         that.class = hlock_class(next);
1418         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1419         if (ret < 0)
1420                 return print_bfs_bug(ret);
1421         if (ret == 1)
1422                 return ret;
1423
1424         return print_bad_irq_dependency(curr, &this, &that,
1425                         target_entry, target_entry1,
1426                         prev, next,
1427                         bit_backwards, bit_forwards, irqclass);
1428 }
1429
1430 static const char *state_names[] = {
1431 #define LOCKDEP_STATE(__STATE) \
1432         __stringify(__STATE),
1433 #include "lockdep_states.h"
1434 #undef LOCKDEP_STATE
1435 };
1436
1437 static const char *state_rnames[] = {
1438 #define LOCKDEP_STATE(__STATE) \
1439         __stringify(__STATE)"-READ",
1440 #include "lockdep_states.h"
1441 #undef LOCKDEP_STATE
1442 };
1443
1444 static inline const char *state_name(enum lock_usage_bit bit)
1445 {
1446         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1447 }
1448
1449 static int exclusive_bit(int new_bit)
1450 {
1451         /*
1452          * USED_IN
1453          * USED_IN_READ
1454          * ENABLED
1455          * ENABLED_READ
1456          *
1457          * bit 0 - write/read
1458          * bit 1 - used_in/enabled
1459          * bit 2+  state
1460          */
1461
1462         int state = new_bit & ~3;
1463         int dir = new_bit & 2;
1464
1465         /*
1466          * keep state, bit flip the direction and strip read.
1467          */
1468         return state | (dir ^ 2);
1469 }
1470
1471 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1472                            struct held_lock *next, enum lock_usage_bit bit)
1473 {
1474         /*
1475          * Prove that the new dependency does not connect a hardirq-safe
1476          * lock with a hardirq-unsafe lock - to achieve this we search
1477          * the backwards-subgraph starting at <prev>, and the
1478          * forwards-subgraph starting at <next>:
1479          */
1480         if (!check_usage(curr, prev, next, bit,
1481                            exclusive_bit(bit), state_name(bit)))
1482                 return 0;
1483
1484         bit++; /* _READ */
1485
1486         /*
1487          * Prove that the new dependency does not connect a hardirq-safe-read
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         return 1;
1497 }
1498
1499 static int
1500 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1501                 struct held_lock *next)
1502 {
1503 #define LOCKDEP_STATE(__STATE)                                          \
1504         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1505                 return 0;
1506 #include "lockdep_states.h"
1507 #undef LOCKDEP_STATE
1508
1509         return 1;
1510 }
1511
1512 static void inc_chains(void)
1513 {
1514         if (current->hardirq_context)
1515                 nr_hardirq_chains++;
1516         else {
1517                 if (current->softirq_context)
1518                         nr_softirq_chains++;
1519                 else
1520                         nr_process_chains++;
1521         }
1522 }
1523
1524 #else
1525
1526 static inline int
1527 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1528                 struct held_lock *next)
1529 {
1530         return 1;
1531 }
1532
1533 static inline void inc_chains(void)
1534 {
1535         nr_process_chains++;
1536 }
1537
1538 #endif
1539
1540 static int
1541 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1542                    struct held_lock *next)
1543 {
1544         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1545                 return 0;
1546
1547         printk("\n=============================================\n");
1548         printk(  "[ INFO: possible recursive locking detected ]\n");
1549         print_kernel_version();
1550         printk(  "---------------------------------------------\n");
1551         printk("%s/%d is trying to acquire lock:\n",
1552                 curr->comm, task_pid_nr(curr));
1553         print_lock(next);
1554         printk("\nbut task is already holding lock:\n");
1555         print_lock(prev);
1556
1557         printk("\nother info that might help us debug this:\n");
1558         lockdep_print_held_locks(curr);
1559
1560         printk("\nstack backtrace:\n");
1561         dump_stack();
1562
1563         return 0;
1564 }
1565
1566 /*
1567  * Check whether we are holding such a class already.
1568  *
1569  * (Note that this has to be done separately, because the graph cannot
1570  * detect such classes of deadlocks.)
1571  *
1572  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1573  */
1574 static int
1575 check_deadlock(struct task_struct *curr, struct held_lock *next,
1576                struct lockdep_map *next_instance, int read)
1577 {
1578         struct held_lock *prev;
1579         struct held_lock *nest = NULL;
1580         int i;
1581
1582         for (i = 0; i < curr->lockdep_depth; i++) {
1583                 prev = curr->held_locks + i;
1584
1585                 if (prev->instance == next->nest_lock)
1586                         nest = prev;
1587
1588                 if (hlock_class(prev) != hlock_class(next))
1589                         continue;
1590
1591                 /*
1592                  * Allow read-after-read recursion of the same
1593                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1594                  */
1595                 if ((read == 2) && prev->read)
1596                         return 2;
1597
1598                 /*
1599                  * We're holding the nest_lock, which serializes this lock's
1600                  * nesting behaviour.
1601                  */
1602                 if (nest)
1603                         return 2;
1604
1605                 return print_deadlock_bug(curr, prev, next);
1606         }
1607         return 1;
1608 }
1609
1610 /*
1611  * There was a chain-cache miss, and we are about to add a new dependency
1612  * to a previous lock. We recursively validate the following rules:
1613  *
1614  *  - would the adding of the <prev> -> <next> dependency create a
1615  *    circular dependency in the graph? [== circular deadlock]
1616  *
1617  *  - does the new prev->next dependency connect any hardirq-safe lock
1618  *    (in the full backwards-subgraph starting at <prev>) with any
1619  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1620  *    <next>)? [== illegal lock inversion with hardirq contexts]
1621  *
1622  *  - does the new prev->next dependency connect any softirq-safe lock
1623  *    (in the full backwards-subgraph starting at <prev>) with any
1624  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1625  *    <next>)? [== illegal lock inversion with softirq contexts]
1626  *
1627  * any of these scenarios could lead to a deadlock.
1628  *
1629  * Then if all the validations pass, we add the forwards and backwards
1630  * dependency.
1631  */
1632 static int
1633 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1634                struct held_lock *next, int distance)
1635 {
1636         struct lock_list *entry;
1637         int ret;
1638         struct lock_list this;
1639         struct lock_list *uninitialized_var(target_entry);
1640
1641         /*
1642          * Prove that the new <prev> -> <next> dependency would not
1643          * create a circular dependency in the graph. (We do this by
1644          * forward-recursing into the graph starting at <next>, and
1645          * checking whether we can reach <prev>.)
1646          *
1647          * We are using global variables to control the recursion, to
1648          * keep the stackframe size of the recursive functions low:
1649          */
1650         this.class = hlock_class(next);
1651         this.parent = NULL;
1652         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1653         if (unlikely(!ret))
1654                 return print_circular_bug(&this, target_entry, next, prev);
1655         else if (unlikely(ret < 0))
1656                 return print_bfs_bug(ret);
1657
1658         if (!check_prev_add_irq(curr, prev, next))
1659                 return 0;
1660
1661         /*
1662          * For recursive read-locks we do all the dependency checks,
1663          * but we dont store read-triggered dependencies (only
1664          * write-triggered dependencies). This ensures that only the
1665          * write-side dependencies matter, and that if for example a
1666          * write-lock never takes any other locks, then the reads are
1667          * equivalent to a NOP.
1668          */
1669         if (next->read == 2 || prev->read == 2)
1670                 return 1;
1671         /*
1672          * Is the <prev> -> <next> dependency already present?
1673          *
1674          * (this may occur even though this is a new chain: consider
1675          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1676          *  chains - the second one will be new, but L1 already has
1677          *  L2 added to its dependency list, due to the first chain.)
1678          */
1679         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1680                 if (entry->class == hlock_class(next)) {
1681                         if (distance == 1)
1682                                 entry->distance = 1;
1683                         return 2;
1684                 }
1685         }
1686
1687         /*
1688          * Ok, all validations passed, add the new lock
1689          * to the previous lock's dependency list:
1690          */
1691         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1692                                &hlock_class(prev)->locks_after,
1693                                next->acquire_ip, distance);
1694
1695         if (!ret)
1696                 return 0;
1697
1698         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1699                                &hlock_class(next)->locks_before,
1700                                next->acquire_ip, distance);
1701         if (!ret)
1702                 return 0;
1703
1704         /*
1705          * Debugging printouts:
1706          */
1707         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1708                 graph_unlock();
1709                 printk("\n new dependency: ");
1710                 print_lock_name(hlock_class(prev));
1711                 printk(" => ");
1712                 print_lock_name(hlock_class(next));
1713                 printk("\n");
1714                 dump_stack();
1715                 return graph_lock();
1716         }
1717         return 1;
1718 }
1719
1720 /*
1721  * Add the dependency to all directly-previous locks that are 'relevant'.
1722  * The ones that are relevant are (in increasing distance from curr):
1723  * all consecutive trylock entries and the final non-trylock entry - or
1724  * the end of this context's lock-chain - whichever comes first.
1725  */
1726 static int
1727 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1728 {
1729         int depth = curr->lockdep_depth;
1730         struct held_lock *hlock;
1731
1732         /*
1733          * Debugging checks.
1734          *
1735          * Depth must not be zero for a non-head lock:
1736          */
1737         if (!depth)
1738                 goto out_bug;
1739         /*
1740          * At least two relevant locks must exist for this
1741          * to be a head:
1742          */
1743         if (curr->held_locks[depth].irq_context !=
1744                         curr->held_locks[depth-1].irq_context)
1745                 goto out_bug;
1746
1747         for (;;) {
1748                 int distance = curr->lockdep_depth - depth + 1;
1749                 hlock = curr->held_locks + depth-1;
1750                 /*
1751                  * Only non-recursive-read entries get new dependencies
1752                  * added:
1753                  */
1754                 if (hlock->read != 2) {
1755                         if (!check_prev_add(curr, hlock, next, distance))
1756                                 return 0;
1757                         /*
1758                          * Stop after the first non-trylock entry,
1759                          * as non-trylock entries have added their
1760                          * own direct dependencies already, so this
1761                          * lock is connected to them indirectly:
1762                          */
1763                         if (!hlock->trylock)
1764                                 break;
1765                 }
1766                 depth--;
1767                 /*
1768                  * End of lock-stack?
1769                  */
1770                 if (!depth)
1771                         break;
1772                 /*
1773                  * Stop the search if we cross into another context:
1774                  */
1775                 if (curr->held_locks[depth].irq_context !=
1776                                 curr->held_locks[depth-1].irq_context)
1777                         break;
1778         }
1779         return 1;
1780 out_bug:
1781         if (!debug_locks_off_graph_unlock())
1782                 return 0;
1783
1784         WARN_ON(1);
1785
1786         return 0;
1787 }
1788
1789 unsigned long nr_lock_chains;
1790 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1791 int nr_chain_hlocks;
1792 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1793
1794 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1795 {
1796         return lock_classes + chain_hlocks[chain->base + i];
1797 }
1798
1799 /*
1800  * Look up a dependency chain. If the key is not present yet then
1801  * add it and return 1 - in this case the new dependency chain is
1802  * validated. If the key is already hashed, return 0.
1803  * (On return with 1 graph_lock is held.)
1804  */
1805 static inline int lookup_chain_cache(struct task_struct *curr,
1806                                      struct held_lock *hlock,
1807                                      u64 chain_key)
1808 {
1809         struct lock_class *class = hlock_class(hlock);
1810         struct list_head *hash_head = chainhashentry(chain_key);
1811         struct lock_chain *chain;
1812         struct held_lock *hlock_curr, *hlock_next;
1813         int i, j, n, cn;
1814
1815         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1816                 return 0;
1817         /*
1818          * We can walk it lock-free, because entries only get added
1819          * to the hash:
1820          */
1821         list_for_each_entry(chain, hash_head, entry) {
1822                 if (chain->chain_key == chain_key) {
1823 cache_hit:
1824                         debug_atomic_inc(&chain_lookup_hits);
1825                         if (very_verbose(class))
1826                                 printk("\nhash chain already cached, key: "
1827                                         "%016Lx tail class: [%p] %s\n",
1828                                         (unsigned long long)chain_key,
1829                                         class->key, class->name);
1830                         return 0;
1831                 }
1832         }
1833         if (very_verbose(class))
1834                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1835                         (unsigned long long)chain_key, class->key, class->name);
1836         /*
1837          * Allocate a new chain entry from the static array, and add
1838          * it to the hash:
1839          */
1840         if (!graph_lock())
1841                 return 0;
1842         /*
1843          * We have to walk the chain again locked - to avoid duplicates:
1844          */
1845         list_for_each_entry(chain, hash_head, entry) {
1846                 if (chain->chain_key == chain_key) {
1847                         graph_unlock();
1848                         goto cache_hit;
1849                 }
1850         }
1851         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1852                 if (!debug_locks_off_graph_unlock())
1853                         return 0;
1854
1855                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1856                 printk("turning off the locking correctness validator.\n");
1857                 dump_stack();
1858                 return 0;
1859         }
1860         chain = lock_chains + nr_lock_chains++;
1861         chain->chain_key = chain_key;
1862         chain->irq_context = hlock->irq_context;
1863         /* Find the first held_lock of current chain */
1864         hlock_next = hlock;
1865         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1866                 hlock_curr = curr->held_locks + i;
1867                 if (hlock_curr->irq_context != hlock_next->irq_context)
1868                         break;
1869                 hlock_next = hlock;
1870         }
1871         i++;
1872         chain->depth = curr->lockdep_depth + 1 - i;
1873         cn = nr_chain_hlocks;
1874         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1875                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1876                 if (n == cn)
1877                         break;
1878                 cn = n;
1879         }
1880         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1881                 chain->base = cn;
1882                 for (j = 0; j < chain->depth - 1; j++, i++) {
1883                         int lock_id = curr->held_locks[i].class_idx - 1;
1884                         chain_hlocks[chain->base + j] = lock_id;
1885                 }
1886                 chain_hlocks[chain->base + j] = class - lock_classes;
1887         }
1888         list_add_tail_rcu(&chain->entry, hash_head);
1889         debug_atomic_inc(&chain_lookup_misses);
1890         inc_chains();
1891
1892         return 1;
1893 }
1894
1895 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1896                 struct held_lock *hlock, int chain_head, u64 chain_key)
1897 {
1898         /*
1899          * Trylock needs to maintain the stack of held locks, but it
1900          * does not add new dependencies, because trylock can be done
1901          * in any order.
1902          *
1903          * We look up the chain_key and do the O(N^2) check and update of
1904          * the dependencies only if this is a new dependency chain.
1905          * (If lookup_chain_cache() returns with 1 it acquires
1906          * graph_lock for us)
1907          */
1908         if (!hlock->trylock && (hlock->check == 2) &&
1909             lookup_chain_cache(curr, hlock, chain_key)) {
1910                 /*
1911                  * Check whether last held lock:
1912                  *
1913                  * - is irq-safe, if this lock is irq-unsafe
1914                  * - is softirq-safe, if this lock is hardirq-unsafe
1915                  *
1916                  * And check whether the new lock's dependency graph
1917                  * could lead back to the previous lock.
1918                  *
1919                  * any of these scenarios could lead to a deadlock. If
1920                  * All validations
1921                  */
1922                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1923
1924                 if (!ret)
1925                         return 0;
1926                 /*
1927                  * Mark recursive read, as we jump over it when
1928                  * building dependencies (just like we jump over
1929                  * trylock entries):
1930                  */
1931                 if (ret == 2)
1932                         hlock->read = 2;
1933                 /*
1934                  * Add dependency only if this lock is not the head
1935                  * of the chain, and if it's not a secondary read-lock:
1936                  */
1937                 if (!chain_head && ret != 2)
1938                         if (!check_prevs_add(curr, hlock))
1939                                 return 0;
1940                 graph_unlock();
1941         } else
1942                 /* after lookup_chain_cache(): */
1943                 if (unlikely(!debug_locks))
1944                         return 0;
1945
1946         return 1;
1947 }
1948 #else
1949 static inline int validate_chain(struct task_struct *curr,
1950                 struct lockdep_map *lock, struct held_lock *hlock,
1951                 int chain_head, u64 chain_key)
1952 {
1953         return 1;
1954 }
1955 #endif
1956
1957 /*
1958  * We are building curr_chain_key incrementally, so double-check
1959  * it from scratch, to make sure that it's done correctly:
1960  */
1961 static void check_chain_key(struct task_struct *curr)
1962 {
1963 #ifdef CONFIG_DEBUG_LOCKDEP
1964         struct held_lock *hlock, *prev_hlock = NULL;
1965         unsigned int i, id;
1966         u64 chain_key = 0;
1967
1968         for (i = 0; i < curr->lockdep_depth; i++) {
1969                 hlock = curr->held_locks + i;
1970                 if (chain_key != hlock->prev_chain_key) {
1971                         debug_locks_off();
1972                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1973                                 curr->lockdep_depth, i,
1974                                 (unsigned long long)chain_key,
1975                                 (unsigned long long)hlock->prev_chain_key);
1976                         return;
1977                 }
1978                 id = hlock->class_idx - 1;
1979                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1980                         return;
1981
1982                 if (prev_hlock && (prev_hlock->irq_context !=
1983                                                         hlock->irq_context))
1984                         chain_key = 0;
1985                 chain_key = iterate_chain_key(chain_key, id);
1986                 prev_hlock = hlock;
1987         }
1988         if (chain_key != curr->curr_chain_key) {
1989                 debug_locks_off();
1990                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1991                         curr->lockdep_depth, i,
1992                         (unsigned long long)chain_key,
1993                         (unsigned long long)curr->curr_chain_key);
1994         }
1995 #endif
1996 }
1997
1998 static int
1999 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2000                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2001 {
2002         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2003                 return 0;
2004
2005         printk("\n=================================\n");
2006         printk(  "[ INFO: inconsistent lock state ]\n");
2007         print_kernel_version();
2008         printk(  "---------------------------------\n");
2009
2010         printk("inconsistent {%s} -> {%s} usage.\n",
2011                 usage_str[prev_bit], usage_str[new_bit]);
2012
2013         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2014                 curr->comm, task_pid_nr(curr),
2015                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2016                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2017                 trace_hardirqs_enabled(curr),
2018                 trace_softirqs_enabled(curr));
2019         print_lock(this);
2020
2021         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2022         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2023
2024         print_irqtrace_events(curr);
2025         printk("\nother info that might help us debug this:\n");
2026         lockdep_print_held_locks(curr);
2027
2028         printk("\nstack backtrace:\n");
2029         dump_stack();
2030
2031         return 0;
2032 }
2033
2034 /*
2035  * Print out an error if an invalid bit is set:
2036  */
2037 static inline int
2038 valid_state(struct task_struct *curr, struct held_lock *this,
2039             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2040 {
2041         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2042                 return print_usage_bug(curr, this, bad_bit, new_bit);
2043         return 1;
2044 }
2045
2046 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2047                      enum lock_usage_bit new_bit);
2048
2049 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2050
2051 /*
2052  * print irq inversion bug:
2053  */
2054 static int
2055 print_irq_inversion_bug(struct task_struct *curr,
2056                         struct lock_list *root, struct lock_list *other,
2057                         struct held_lock *this, int forwards,
2058                         const char *irqclass)
2059 {
2060         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2061                 return 0;
2062
2063         printk("\n=========================================================\n");
2064         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2065         print_kernel_version();
2066         printk(  "---------------------------------------------------------\n");
2067         printk("%s/%d just changed the state of lock:\n",
2068                 curr->comm, task_pid_nr(curr));
2069         print_lock(this);
2070         if (forwards)
2071                 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2072         else
2073                 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2074         print_lock_name(other->class);
2075         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2076
2077         printk("\nother info that might help us debug this:\n");
2078         lockdep_print_held_locks(curr);
2079
2080         printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2081         if (!save_trace(&root->trace))
2082                 return 0;
2083         print_shortest_lock_dependencies(other, root);
2084
2085         printk("\nstack backtrace:\n");
2086         dump_stack();
2087
2088         return 0;
2089 }
2090
2091 /*
2092  * Prove that in the forwards-direction subgraph starting at <this>
2093  * there is no lock matching <mask>:
2094  */
2095 static int
2096 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2097                      enum lock_usage_bit bit, const char *irqclass)
2098 {
2099         int ret;
2100         struct lock_list root;
2101         struct lock_list *uninitialized_var(target_entry);
2102
2103         root.parent = NULL;
2104         root.class = hlock_class(this);
2105         ret = find_usage_forwards(&root, bit, &target_entry);
2106         if (ret < 0)
2107                 return print_bfs_bug(ret);
2108         if (ret == 1)
2109                 return ret;
2110
2111         return print_irq_inversion_bug(curr, &root, target_entry,
2112                                         this, 1, irqclass);
2113 }
2114
2115 /*
2116  * Prove that in the backwards-direction subgraph starting at <this>
2117  * there is no lock matching <mask>:
2118  */
2119 static int
2120 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2121                       enum lock_usage_bit bit, const char *irqclass)
2122 {
2123         int ret;
2124         struct lock_list root;
2125         struct lock_list *uninitialized_var(target_entry);
2126
2127         root.parent = NULL;
2128         root.class = hlock_class(this);
2129         ret = find_usage_backwards(&root, bit, &target_entry);
2130         if (ret < 0)
2131                 return print_bfs_bug(ret);
2132         if (ret == 1)
2133                 return ret;
2134
2135         return print_irq_inversion_bug(curr, &root, target_entry,
2136                                         this, 1, irqclass);
2137 }
2138
2139 void print_irqtrace_events(struct task_struct *curr)
2140 {
2141         printk("irq event stamp: %u\n", curr->irq_events);
2142         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
2143         print_ip_sym(curr->hardirq_enable_ip);
2144         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2145         print_ip_sym(curr->hardirq_disable_ip);
2146         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
2147         print_ip_sym(curr->softirq_enable_ip);
2148         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2149         print_ip_sym(curr->softirq_disable_ip);
2150 }
2151
2152 static int HARDIRQ_verbose(struct lock_class *class)
2153 {
2154 #if HARDIRQ_VERBOSE
2155         return class_filter(class);
2156 #endif
2157         return 0;
2158 }
2159
2160 static int SOFTIRQ_verbose(struct lock_class *class)
2161 {
2162 #if SOFTIRQ_VERBOSE
2163         return class_filter(class);
2164 #endif
2165         return 0;
2166 }
2167
2168 static int RECLAIM_FS_verbose(struct lock_class *class)
2169 {
2170 #if RECLAIM_VERBOSE
2171         return class_filter(class);
2172 #endif
2173         return 0;
2174 }
2175
2176 #define STRICT_READ_CHECKS      1
2177
2178 static int (*state_verbose_f[])(struct lock_class *class) = {
2179 #define LOCKDEP_STATE(__STATE) \
2180         __STATE##_verbose,
2181 #include "lockdep_states.h"
2182 #undef LOCKDEP_STATE
2183 };
2184
2185 static inline int state_verbose(enum lock_usage_bit bit,
2186                                 struct lock_class *class)
2187 {
2188         return state_verbose_f[bit >> 2](class);
2189 }
2190
2191 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2192                              enum lock_usage_bit bit, const char *name);
2193
2194 static int
2195 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2196                 enum lock_usage_bit new_bit)
2197 {
2198         int excl_bit = exclusive_bit(new_bit);
2199         int read = new_bit & 1;
2200         int dir = new_bit & 2;
2201
2202         /*
2203          * mark USED_IN has to look forwards -- to ensure no dependency
2204          * has ENABLED state, which would allow recursion deadlocks.
2205          *
2206          * mark ENABLED has to look backwards -- to ensure no dependee
2207          * has USED_IN state, which, again, would allow  recursion deadlocks.
2208          */
2209         check_usage_f usage = dir ?
2210                 check_usage_backwards : check_usage_forwards;
2211
2212         /*
2213          * Validate that this particular lock does not have conflicting
2214          * usage states.
2215          */
2216         if (!valid_state(curr, this, new_bit, excl_bit))
2217                 return 0;
2218
2219         /*
2220          * Validate that the lock dependencies don't have conflicting usage
2221          * states.
2222          */
2223         if ((!read || !dir || STRICT_READ_CHECKS) &&
2224                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2225                 return 0;
2226
2227         /*
2228          * Check for read in write conflicts
2229          */
2230         if (!read) {
2231                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2232                         return 0;
2233
2234                 if (STRICT_READ_CHECKS &&
2235                         !usage(curr, this, excl_bit + 1,
2236                                 state_name(new_bit + 1)))
2237                         return 0;
2238         }
2239
2240         if (state_verbose(new_bit, hlock_class(this)))
2241                 return 2;
2242
2243         return 1;
2244 }
2245
2246 enum mark_type {
2247 #define LOCKDEP_STATE(__STATE)  __STATE,
2248 #include "lockdep_states.h"
2249 #undef LOCKDEP_STATE
2250 };
2251
2252 /*
2253  * Mark all held locks with a usage bit:
2254  */
2255 static int
2256 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2257 {
2258         enum lock_usage_bit usage_bit;
2259         struct held_lock *hlock;
2260         int i;
2261
2262         for (i = 0; i < curr->lockdep_depth; i++) {
2263                 hlock = curr->held_locks + i;
2264
2265                 usage_bit = 2 + (mark << 2); /* ENABLED */
2266                 if (hlock->read)
2267                         usage_bit += 1; /* READ */
2268
2269                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2270
2271                 if (!mark_lock(curr, hlock, usage_bit))
2272                         return 0;
2273         }
2274
2275         return 1;
2276 }
2277
2278 /*
2279  * Debugging helper: via this flag we know that we are in
2280  * 'early bootup code', and will warn about any invalid irqs-on event:
2281  */
2282 static int early_boot_irqs_enabled;
2283
2284 void early_boot_irqs_off(void)
2285 {
2286         early_boot_irqs_enabled = 0;
2287 }
2288
2289 void early_boot_irqs_on(void)
2290 {
2291         early_boot_irqs_enabled = 1;
2292 }
2293
2294 /*
2295  * Hardirqs will be enabled:
2296  */
2297 void trace_hardirqs_on_caller(unsigned long ip)
2298 {
2299         struct task_struct *curr = current;
2300
2301         time_hardirqs_on(CALLER_ADDR0, ip);
2302
2303         if (unlikely(!debug_locks || current->lockdep_recursion))
2304                 return;
2305
2306         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2307                 return;
2308
2309         if (unlikely(curr->hardirqs_enabled)) {
2310                 debug_atomic_inc(&redundant_hardirqs_on);
2311                 return;
2312         }
2313         /* we'll do an OFF -> ON transition: */
2314         curr->hardirqs_enabled = 1;
2315
2316         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2317                 return;
2318         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2319                 return;
2320         /*
2321          * We are going to turn hardirqs on, so set the
2322          * usage bit for all held locks:
2323          */
2324         if (!mark_held_locks(curr, HARDIRQ))
2325                 return;
2326         /*
2327          * If we have softirqs enabled, then set the usage
2328          * bit for all held locks. (disabled hardirqs prevented
2329          * this bit from being set before)
2330          */
2331         if (curr->softirqs_enabled)
2332                 if (!mark_held_locks(curr, SOFTIRQ))
2333                         return;
2334
2335         curr->hardirq_enable_ip = ip;
2336         curr->hardirq_enable_event = ++curr->irq_events;
2337         debug_atomic_inc(&hardirqs_on_events);
2338 }
2339 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2340
2341 void trace_hardirqs_on(void)
2342 {
2343         trace_hardirqs_on_caller(CALLER_ADDR0);
2344 }
2345 EXPORT_SYMBOL(trace_hardirqs_on);
2346
2347 /*
2348  * Hardirqs were disabled:
2349  */
2350 void trace_hardirqs_off_caller(unsigned long ip)
2351 {
2352         struct task_struct *curr = current;
2353
2354         time_hardirqs_off(CALLER_ADDR0, ip);
2355
2356         if (unlikely(!debug_locks || current->lockdep_recursion))
2357                 return;
2358
2359         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2360                 return;
2361
2362         if (curr->hardirqs_enabled) {
2363                 /*
2364                  * We have done an ON -> OFF transition:
2365                  */
2366                 curr->hardirqs_enabled = 0;
2367                 curr->hardirq_disable_ip = ip;
2368                 curr->hardirq_disable_event = ++curr->irq_events;
2369                 debug_atomic_inc(&hardirqs_off_events);
2370         } else
2371                 debug_atomic_inc(&redundant_hardirqs_off);
2372 }
2373 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2374
2375 void trace_hardirqs_off(void)
2376 {
2377         trace_hardirqs_off_caller(CALLER_ADDR0);
2378 }
2379 EXPORT_SYMBOL(trace_hardirqs_off);
2380
2381 /*
2382  * Softirqs will be enabled:
2383  */
2384 void trace_softirqs_on(unsigned long ip)
2385 {
2386         struct task_struct *curr = current;
2387
2388         if (unlikely(!debug_locks))
2389                 return;
2390
2391         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2392                 return;
2393
2394         if (curr->softirqs_enabled) {
2395                 debug_atomic_inc(&redundant_softirqs_on);
2396                 return;
2397         }
2398
2399         /*
2400          * We'll do an OFF -> ON transition:
2401          */
2402         curr->softirqs_enabled = 1;
2403         curr->softirq_enable_ip = ip;
2404         curr->softirq_enable_event = ++curr->irq_events;
2405         debug_atomic_inc(&softirqs_on_events);
2406         /*
2407          * We are going to turn softirqs on, so set the
2408          * usage bit for all held locks, if hardirqs are
2409          * enabled too:
2410          */
2411         if (curr->hardirqs_enabled)
2412                 mark_held_locks(curr, SOFTIRQ);
2413 }
2414
2415 /*
2416  * Softirqs were disabled:
2417  */
2418 void trace_softirqs_off(unsigned long ip)
2419 {
2420         struct task_struct *curr = current;
2421
2422         if (unlikely(!debug_locks))
2423                 return;
2424
2425         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2426                 return;
2427
2428         if (curr->softirqs_enabled) {
2429                 /*
2430                  * We have done an ON -> OFF transition:
2431                  */
2432                 curr->softirqs_enabled = 0;
2433                 curr->softirq_disable_ip = ip;
2434                 curr->softirq_disable_event = ++curr->irq_events;
2435                 debug_atomic_inc(&softirqs_off_events);
2436                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2437         } else
2438                 debug_atomic_inc(&redundant_softirqs_off);
2439 }
2440
2441 static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2442 {
2443         struct task_struct *curr = current;
2444
2445         if (unlikely(!debug_locks))
2446                 return;
2447
2448         /* no reclaim without waiting on it */
2449         if (!(gfp_mask & __GFP_WAIT))
2450                 return;
2451
2452         /* this guy won't enter reclaim */
2453         if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2454                 return;
2455
2456         /* We're only interested __GFP_FS allocations for now */
2457         if (!(gfp_mask & __GFP_FS))
2458                 return;
2459
2460         if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2461                 return;
2462
2463         mark_held_locks(curr, RECLAIM_FS);
2464 }
2465
2466 static void check_flags(unsigned long flags);
2467
2468 void lockdep_trace_alloc(gfp_t gfp_mask)
2469 {
2470         unsigned long flags;
2471
2472         if (unlikely(current->lockdep_recursion))
2473                 return;
2474
2475         raw_local_irq_save(flags);
2476         check_flags(flags);
2477         current->lockdep_recursion = 1;
2478         __lockdep_trace_alloc(gfp_mask, flags);
2479         current->lockdep_recursion = 0;
2480         raw_local_irq_restore(flags);
2481 }
2482
2483 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2484 {
2485         /*
2486          * If non-trylock use in a hardirq or softirq context, then
2487          * mark the lock as used in these contexts:
2488          */
2489         if (!hlock->trylock) {
2490                 if (hlock->read) {
2491                         if (curr->hardirq_context)
2492                                 if (!mark_lock(curr, hlock,
2493                                                 LOCK_USED_IN_HARDIRQ_READ))
2494                                         return 0;
2495                         if (curr->softirq_context)
2496                                 if (!mark_lock(curr, hlock,
2497                                                 LOCK_USED_IN_SOFTIRQ_READ))
2498                                         return 0;
2499                 } else {
2500                         if (curr->hardirq_context)
2501                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2502                                         return 0;
2503                         if (curr->softirq_context)
2504                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2505                                         return 0;
2506                 }
2507         }
2508         if (!hlock->hardirqs_off) {
2509                 if (hlock->read) {
2510                         if (!mark_lock(curr, hlock,
2511                                         LOCK_ENABLED_HARDIRQ_READ))
2512                                 return 0;
2513                         if (curr->softirqs_enabled)
2514                                 if (!mark_lock(curr, hlock,
2515                                                 LOCK_ENABLED_SOFTIRQ_READ))
2516                                         return 0;
2517                 } else {
2518                         if (!mark_lock(curr, hlock,
2519                                         LOCK_ENABLED_HARDIRQ))
2520                                 return 0;
2521                         if (curr->softirqs_enabled)
2522                                 if (!mark_lock(curr, hlock,
2523                                                 LOCK_ENABLED_SOFTIRQ))
2524                                         return 0;
2525                 }
2526         }
2527
2528         /*
2529          * We reuse the irq context infrastructure more broadly as a general
2530          * context checking code. This tests GFP_FS recursion (a lock taken
2531          * during reclaim for a GFP_FS allocation is held over a GFP_FS
2532          * allocation).
2533          */
2534         if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2535                 if (hlock->read) {
2536                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2537                                         return 0;
2538                 } else {
2539                         if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2540                                         return 0;
2541                 }
2542         }
2543
2544         return 1;
2545 }
2546
2547 static int separate_irq_context(struct task_struct *curr,
2548                 struct held_lock *hlock)
2549 {
2550         unsigned int depth = curr->lockdep_depth;
2551
2552         /*
2553          * Keep track of points where we cross into an interrupt context:
2554          */
2555         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2556                                 curr->softirq_context;
2557         if (depth) {
2558                 struct held_lock *prev_hlock;
2559
2560                 prev_hlock = curr->held_locks + depth-1;
2561                 /*
2562                  * If we cross into another context, reset the
2563                  * hash key (this also prevents the checking and the
2564                  * adding of the dependency to 'prev'):
2565                  */
2566                 if (prev_hlock->irq_context != hlock->irq_context)
2567                         return 1;
2568         }
2569         return 0;
2570 }
2571
2572 #else
2573
2574 static inline
2575 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2576                 enum lock_usage_bit new_bit)
2577 {
2578         WARN_ON(1);
2579         return 1;
2580 }
2581
2582 static inline int mark_irqflags(struct task_struct *curr,
2583                 struct held_lock *hlock)
2584 {
2585         return 1;
2586 }
2587
2588 static inline int separate_irq_context(struct task_struct *curr,
2589                 struct held_lock *hlock)
2590 {
2591         return 0;
2592 }
2593
2594 void lockdep_trace_alloc(gfp_t gfp_mask)
2595 {
2596 }
2597
2598 #endif
2599
2600 /*
2601  * Mark a lock with a usage bit, and validate the state transition:
2602  */
2603 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2604                              enum lock_usage_bit new_bit)
2605 {
2606         unsigned int new_mask = 1 << new_bit, ret = 1;
2607
2608         /*
2609          * If already set then do not dirty the cacheline,
2610          * nor do any checks:
2611          */
2612         if (likely(hlock_class(this)->usage_mask & new_mask))
2613                 return 1;
2614
2615         if (!graph_lock())
2616                 return 0;
2617         /*
2618          * Make sure we didnt race:
2619          */
2620         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2621                 graph_unlock();
2622                 return 1;
2623         }
2624
2625         hlock_class(this)->usage_mask |= new_mask;
2626
2627         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2628                 return 0;
2629
2630         switch (new_bit) {
2631 #define LOCKDEP_STATE(__STATE)                  \
2632         case LOCK_USED_IN_##__STATE:            \
2633         case LOCK_USED_IN_##__STATE##_READ:     \
2634         case LOCK_ENABLED_##__STATE:            \
2635         case LOCK_ENABLED_##__STATE##_READ:
2636 #include "lockdep_states.h"
2637 #undef LOCKDEP_STATE
2638                 ret = mark_lock_irq(curr, this, new_bit);
2639                 if (!ret)
2640                         return 0;
2641                 break;
2642         case LOCK_USED:
2643                 debug_atomic_dec(&nr_unused_locks);
2644                 break;
2645         default:
2646                 if (!debug_locks_off_graph_unlock())
2647                         return 0;
2648                 WARN_ON(1);
2649                 return 0;
2650         }
2651
2652         graph_unlock();
2653
2654         /*
2655          * We must printk outside of the graph_lock:
2656          */
2657         if (ret == 2) {
2658                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2659                 print_lock(this);
2660                 print_irqtrace_events(curr);
2661                 dump_stack();
2662         }
2663
2664         return ret;
2665 }
2666
2667 /*
2668  * Initialize a lock instance's lock-class mapping info:
2669  */
2670 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2671                       struct lock_class_key *key, int subclass)
2672 {
2673         lock->class_cache = NULL;
2674 #ifdef CONFIG_LOCK_STAT
2675         lock->cpu = raw_smp_processor_id();
2676 #endif
2677
2678         if (DEBUG_LOCKS_WARN_ON(!name)) {
2679                 lock->name = "NULL";
2680                 return;
2681         }
2682
2683         lock->name = name;
2684
2685         if (DEBUG_LOCKS_WARN_ON(!key))
2686                 return;
2687         /*
2688          * Sanity check, the lock-class key must be persistent:
2689          */
2690         if (!static_obj(key)) {
2691                 printk("BUG: key %p not in .data!\n", key);
2692                 DEBUG_LOCKS_WARN_ON(1);
2693                 return;
2694         }
2695         lock->key = key;
2696
2697         if (unlikely(!debug_locks))
2698                 return;
2699
2700         if (subclass)
2701                 register_lock_class(lock, subclass, 1);
2702 }
2703 EXPORT_SYMBOL_GPL(lockdep_init_map);
2704
2705 /*
2706  * This gets called for every mutex_lock*()/spin_lock*() operation.
2707  * We maintain the dependency maps and validate the locking attempt:
2708  */
2709 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2710                           int trylock, int read, int check, int hardirqs_off,
2711                           struct lockdep_map *nest_lock, unsigned long ip)
2712 {
2713         struct task_struct *curr = current;
2714         struct lock_class *class = NULL;
2715         struct held_lock *hlock;
2716         unsigned int depth, id;
2717         int chain_head = 0;
2718         u64 chain_key;
2719
2720         if (!prove_locking)
2721                 check = 1;
2722
2723         if (unlikely(!debug_locks))
2724                 return 0;
2725
2726         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2727                 return 0;
2728
2729         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2730                 debug_locks_off();
2731                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2732                 printk("turning off the locking correctness validator.\n");
2733                 dump_stack();
2734                 return 0;
2735         }
2736
2737         if (!subclass)
2738                 class = lock->class_cache;
2739         /*
2740          * Not cached yet or subclass?
2741          */
2742         if (unlikely(!class)) {
2743                 class = register_lock_class(lock, subclass, 0);
2744                 if (!class)
2745                         return 0;
2746         }
2747         debug_atomic_inc((atomic_t *)&class->ops);
2748         if (very_verbose(class)) {
2749                 printk("\nacquire class [%p] %s", class->key, class->name);
2750                 if (class->name_version > 1)
2751                         printk("#%d", class->name_version);
2752                 printk("\n");
2753                 dump_stack();
2754         }
2755
2756         /*
2757          * Add the lock to the list of currently held locks.
2758          * (we dont increase the depth just yet, up until the
2759          * dependency checks are done)
2760          */
2761         depth = curr->lockdep_depth;
2762         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2763                 return 0;
2764
2765         hlock = curr->held_locks + depth;
2766         if (DEBUG_LOCKS_WARN_ON(!class))
2767                 return 0;
2768         hlock->class_idx = class - lock_classes + 1;
2769         hlock->acquire_ip = ip;
2770         hlock->instance = lock;
2771         hlock->nest_lock = nest_lock;
2772         hlock->trylock = trylock;
2773         hlock->read = read;
2774         hlock->check = check;
2775         hlock->hardirqs_off = !!hardirqs_off;
2776 #ifdef CONFIG_LOCK_STAT
2777         hlock->waittime_stamp = 0;
2778         hlock->holdtime_stamp = sched_clock();
2779 #endif
2780
2781         if (check == 2 && !mark_irqflags(curr, hlock))
2782                 return 0;
2783
2784         /* mark it as used: */
2785         if (!mark_lock(curr, hlock, LOCK_USED))
2786                 return 0;
2787
2788         /*
2789          * Calculate the chain hash: it's the combined hash of all the
2790          * lock keys along the dependency chain. We save the hash value
2791          * at every step so that we can get the current hash easily
2792          * after unlock. The chain hash is then used to cache dependency
2793          * results.
2794          *
2795          * The 'key ID' is what is the most compact key value to drive
2796          * the hash, not class->key.
2797          */
2798         id = class - lock_classes;
2799         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2800                 return 0;
2801
2802         chain_key = curr->curr_chain_key;
2803         if (!depth) {
2804                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2805                         return 0;
2806                 chain_head = 1;
2807         }
2808
2809         hlock->prev_chain_key = chain_key;
2810         if (separate_irq_context(curr, hlock)) {
2811                 chain_key = 0;
2812                 chain_head = 1;
2813         }
2814         chain_key = iterate_chain_key(chain_key, id);
2815
2816         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2817                 return 0;
2818
2819         curr->curr_chain_key = chain_key;
2820         curr->lockdep_depth++;
2821         check_chain_key(curr);
2822 #ifdef CONFIG_DEBUG_LOCKDEP
2823         if (unlikely(!debug_locks))
2824                 return 0;
2825 #endif
2826         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2827                 debug_locks_off();
2828                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2829                 printk("turning off the locking correctness validator.\n");
2830                 dump_stack();
2831                 return 0;
2832         }
2833
2834         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2835                 max_lockdep_depth = curr->lockdep_depth;
2836
2837         return 1;
2838 }
2839
2840 static int
2841 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2842                            unsigned long ip)
2843 {
2844         if (!debug_locks_off())
2845                 return 0;
2846         if (debug_locks_silent)
2847                 return 0;
2848
2849         printk("\n=====================================\n");
2850         printk(  "[ BUG: bad unlock balance detected! ]\n");
2851         printk(  "-------------------------------------\n");
2852         printk("%s/%d is trying to release lock (",
2853                 curr->comm, task_pid_nr(curr));
2854         print_lockdep_cache(lock);
2855         printk(") at:\n");
2856         print_ip_sym(ip);
2857         printk("but there are no more locks to release!\n");
2858         printk("\nother info that might help us debug this:\n");
2859         lockdep_print_held_locks(curr);
2860
2861         printk("\nstack backtrace:\n");
2862         dump_stack();
2863
2864         return 0;
2865 }
2866
2867 /*
2868  * Common debugging checks for both nested and non-nested unlock:
2869  */
2870 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2871                         unsigned long ip)
2872 {
2873         if (unlikely(!debug_locks))
2874                 return 0;
2875         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2876                 return 0;
2877
2878         if (curr->lockdep_depth <= 0)
2879                 return print_unlock_inbalance_bug(curr, lock, ip);
2880
2881         return 1;
2882 }
2883
2884 static int
2885 __lock_set_class(struct lockdep_map *lock, const char *name,
2886                  struct lock_class_key *key, unsigned int subclass,
2887                  unsigned long ip)
2888 {
2889         struct task_struct *curr = current;
2890         struct held_lock *hlock, *prev_hlock;
2891         struct lock_class *class;
2892         unsigned int depth;
2893         int i;
2894
2895         depth = curr->lockdep_depth;
2896         if (DEBUG_LOCKS_WARN_ON(!depth))
2897                 return 0;
2898
2899         prev_hlock = NULL;
2900         for (i = depth-1; i >= 0; i--) {
2901                 hlock = curr->held_locks + i;
2902                 /*
2903                  * We must not cross into another context:
2904                  */
2905                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2906                         break;
2907                 if (hlock->instance == lock)
2908                         goto found_it;
2909                 prev_hlock = hlock;
2910         }
2911         return print_unlock_inbalance_bug(curr, lock, ip);
2912
2913 found_it:
2914         lockdep_init_map(lock, name, key, 0);
2915         class = register_lock_class(lock, subclass, 0);
2916         hlock->class_idx = class - lock_classes + 1;
2917
2918         curr->lockdep_depth = i;
2919         curr->curr_chain_key = hlock->prev_chain_key;
2920
2921         for (; i < depth; i++) {
2922                 hlock = curr->held_locks + i;
2923                 if (!__lock_acquire(hlock->instance,
2924                         hlock_class(hlock)->subclass, hlock->trylock,
2925                                 hlock->read, hlock->check, hlock->hardirqs_off,
2926                                 hlock->nest_lock, hlock->acquire_ip))
2927                         return 0;
2928         }
2929
2930         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2931                 return 0;
2932         return 1;
2933 }
2934
2935 /*
2936  * Remove the lock to the list of currently held locks in a
2937  * potentially non-nested (out of order) manner. This is a
2938  * relatively rare operation, as all the unlock APIs default
2939  * to nested mode (which uses lock_release()):
2940  */
2941 static int
2942 lock_release_non_nested(struct task_struct *curr,
2943                         struct lockdep_map *lock, unsigned long ip)
2944 {
2945         struct held_lock *hlock, *prev_hlock;
2946         unsigned int depth;
2947         int i;
2948
2949         /*
2950          * Check whether the lock exists in the current stack
2951          * of held locks:
2952          */
2953         depth = curr->lockdep_depth;
2954         if (DEBUG_LOCKS_WARN_ON(!depth))
2955                 return 0;
2956
2957         prev_hlock = NULL;
2958         for (i = depth-1; i >= 0; i--) {
2959                 hlock = curr->held_locks + i;
2960                 /*
2961                  * We must not cross into another context:
2962                  */
2963                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2964                         break;
2965                 if (hlock->instance == lock)
2966                         goto found_it;
2967                 prev_hlock = hlock;
2968         }
2969         return print_unlock_inbalance_bug(curr, lock, ip);
2970
2971 found_it:
2972         lock_release_holdtime(hlock);
2973
2974         /*
2975          * We have the right lock to unlock, 'hlock' points to it.
2976          * Now we remove it from the stack, and add back the other
2977          * entries (if any), recalculating the hash along the way:
2978          */
2979         curr->lockdep_depth = i;
2980         curr->curr_chain_key = hlock->prev_chain_key;
2981
2982         for (i++; i < depth; i++) {
2983                 hlock = curr->held_locks + i;
2984                 if (!__lock_acquire(hlock->instance,
2985                         hlock_class(hlock)->subclass, hlock->trylock,
2986                                 hlock->read, hlock->check, hlock->hardirqs_off,
2987                                 hlock->nest_lock, hlock->acquire_ip))
2988                         return 0;
2989         }
2990
2991         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2992                 return 0;
2993         return 1;
2994 }
2995
2996 /*
2997  * Remove the lock to the list of currently held locks - this gets
2998  * called on mutex_unlock()/spin_unlock*() (or on a failed
2999  * mutex_lock_interruptible()). This is done for unlocks that nest
3000  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3001  */
3002 static int lock_release_nested(struct task_struct *curr,
3003                                struct lockdep_map *lock, unsigned long ip)
3004 {
3005         struct held_lock *hlock;
3006         unsigned int depth;
3007
3008         /*
3009          * Pop off the top of the lock stack:
3010          */
3011         depth = curr->lockdep_depth - 1;
3012         hlock = curr->held_locks + depth;
3013
3014         /*
3015          * Is the unlock non-nested:
3016          */
3017         if (hlock->instance != lock)
3018                 return lock_release_non_nested(curr, lock, ip);
3019         curr->lockdep_depth--;
3020
3021         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3022                 return 0;
3023
3024         curr->curr_chain_key = hlock->prev_chain_key;
3025
3026         lock_release_holdtime(hlock);
3027
3028 #ifdef CONFIG_DEBUG_LOCKDEP
3029         hlock->prev_chain_key = 0;
3030         hlock->class_idx = 0;
3031         hlock->acquire_ip = 0;
3032         hlock->irq_context = 0;
3033 #endif
3034         return 1;
3035 }
3036
3037 /*
3038  * Remove the lock to the list of currently held locks - this gets
3039  * called on mutex_unlock()/spin_unlock*() (or on a failed
3040  * mutex_lock_interruptible()). This is done for unlocks that nest
3041  * perfectly. (i.e. the current top of the lock-stack is unlocked)
3042  */
3043 static void
3044 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3045 {
3046         struct task_struct *curr = current;
3047
3048         if (!check_unlock(curr, lock, ip))
3049                 return;
3050
3051         if (nested) {
3052                 if (!lock_release_nested(curr, lock, ip))
3053                         return;
3054         } else {
3055                 if (!lock_release_non_nested(curr, lock, ip))
3056                         return;
3057         }
3058
3059         check_chain_key(curr);
3060 }
3061
3062 /*
3063  * Check whether we follow the irq-flags state precisely:
3064  */
3065 static void check_flags(unsigned long flags)
3066 {
3067 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3068     defined(CONFIG_TRACE_IRQFLAGS)
3069         if (!debug_locks)
3070                 return;
3071
3072         if (irqs_disabled_flags(flags)) {
3073                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3074                         printk("possible reason: unannotated irqs-off.\n");
3075                 }
3076         } else {
3077                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3078                         printk("possible reason: unannotated irqs-on.\n");
3079                 }
3080         }
3081
3082         /*
3083          * We dont accurately track softirq state in e.g.
3084          * hardirq contexts (such as on 4KSTACKS), so only
3085          * check if not in hardirq contexts:
3086          */
3087         if (!hardirq_count()) {
3088                 if (softirq_count())
3089                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3090                 else
3091                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3092         }
3093
3094         if (!debug_locks)
3095                 print_irqtrace_events(current);
3096 #endif
3097 }
3098
3099 void lock_set_class(struct lockdep_map *lock, const char *name,
3100                     struct lock_class_key *key, unsigned int subclass,
3101                     unsigned long ip)
3102 {
3103         unsigned long flags;
3104
3105         if (unlikely(current->lockdep_recursion))
3106                 return;
3107
3108         raw_local_irq_save(flags);
3109         current->lockdep_recursion = 1;
3110         check_flags(flags);
3111         if (__lock_set_class(lock, name, key, subclass, ip))
3112                 check_chain_key(current);
3113         current->lockdep_recursion = 0;
3114         raw_local_irq_restore(flags);
3115 }
3116 EXPORT_SYMBOL_GPL(lock_set_class);
3117
3118 /*
3119  * We are not always called with irqs disabled - do that here,
3120  * and also avoid lockdep recursion:
3121  */
3122 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3123                           int trylock, int read, int check,
3124                           struct lockdep_map *nest_lock, unsigned long ip)
3125 {
3126         unsigned long flags;
3127
3128         trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3129
3130         if (unlikely(current->lockdep_recursion))
3131                 return;
3132
3133         raw_local_irq_save(flags);
3134         check_flags(flags);
3135
3136         current->lockdep_recursion = 1;
3137         __lock_acquire(lock, subclass, trylock, read, check,
3138                        irqs_disabled_flags(flags), nest_lock, ip);
3139         current->lockdep_recursion = 0;
3140         raw_local_irq_restore(flags);
3141 }
3142 EXPORT_SYMBOL_GPL(lock_acquire);
3143
3144 void lock_release(struct lockdep_map *lock, int nested,
3145                           unsigned long ip)
3146 {
3147         unsigned long flags;
3148
3149         trace_lock_release(lock, nested, ip);
3150
3151         if (unlikely(current->lockdep_recursion))
3152                 return;
3153
3154         raw_local_irq_save(flags);
3155         check_flags(flags);
3156         current->lockdep_recursion = 1;
3157         __lock_release(lock, nested, ip);
3158         current->lockdep_recursion = 0;
3159         raw_local_irq_restore(flags);
3160 }
3161 EXPORT_SYMBOL_GPL(lock_release);
3162
3163 void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3164 {
3165         current->lockdep_reclaim_gfp = gfp_mask;
3166 }
3167
3168 void lockdep_clear_current_reclaim_state(void)
3169 {
3170         current->lockdep_reclaim_gfp = 0;
3171 }
3172
3173 #ifdef CONFIG_LOCK_STAT
3174 static int
3175 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3176                            unsigned long ip)
3177 {
3178         if (!debug_locks_off())
3179                 return 0;
3180         if (debug_locks_silent)
3181                 return 0;
3182
3183         printk("\n=================================\n");
3184         printk(  "[ BUG: bad contention detected! ]\n");
3185         printk(  "---------------------------------\n");
3186         printk("%s/%d is trying to contend lock (",
3187                 curr->comm, task_pid_nr(curr));
3188         print_lockdep_cache(lock);
3189         printk(") at:\n");
3190         print_ip_sym(ip);
3191         printk("but there are no locks held!\n");
3192         printk("\nother info that might help us debug this:\n");
3193         lockdep_print_held_locks(curr);
3194
3195         printk("\nstack backtrace:\n");
3196         dump_stack();
3197
3198         return 0;
3199 }
3200
3201 static void
3202 __lock_contended(struct lockdep_map *lock, unsigned long ip)
3203 {
3204         struct task_struct *curr = current;
3205         struct held_lock *hlock, *prev_hlock;
3206         struct lock_class_stats *stats;
3207         unsigned int depth;
3208         int i, contention_point, contending_point;
3209
3210         depth = curr->lockdep_depth;
3211         if (DEBUG_LOCKS_WARN_ON(!depth))
3212                 return;
3213
3214         prev_hlock = NULL;
3215         for (i = depth-1; i >= 0; i--) {
3216                 hlock = curr->held_locks + i;
3217                 /*
3218                  * We must not cross into another context:
3219                  */
3220                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3221                         break;
3222                 if (hlock->instance == lock)
3223                         goto found_it;
3224                 prev_hlock = hlock;
3225         }
3226         print_lock_contention_bug(curr, lock, ip);
3227         return;
3228
3229 found_it:
3230         hlock->waittime_stamp = sched_clock();
3231
3232         contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3233         contending_point = lock_point(hlock_class(hlock)->contending_point,
3234                                       lock->ip);
3235
3236         stats = get_lock_stats(hlock_class(hlock));
3237         if (contention_point < LOCKSTAT_POINTS)
3238                 stats->contention_point[contention_point]++;
3239         if (contending_point < LOCKSTAT_POINTS)
3240                 stats->contending_point[contending_point]++;
3241         if (lock->cpu != smp_processor_id())
3242                 stats->bounces[bounce_contended + !!hlock->read]++;
3243         put_lock_stats(stats);
3244 }
3245
3246 static void
3247 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
3248 {
3249         struct task_struct *curr = current;
3250         struct held_lock *hlock, *prev_hlock;
3251         struct lock_class_stats *stats;
3252         unsigned int depth;
3253         u64 now;
3254         s64 waittime = 0;
3255         int i, cpu;
3256
3257         depth = curr->lockdep_depth;
3258         if (DEBUG_LOCKS_WARN_ON(!depth))
3259                 return;
3260
3261         prev_hlock = NULL;
3262         for (i = depth-1; i >= 0; i--) {
3263                 hlock = curr->held_locks + i;
3264                 /*
3265                  * We must not cross into another context:
3266                  */
3267                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3268                         break;
3269                 if (hlock->instance == lock)
3270                         goto found_it;
3271                 prev_hlock = hlock;
3272         }
3273         print_lock_contention_bug(curr, lock, _RET_IP_);
3274         return;
3275
3276 found_it:
3277         cpu = smp_processor_id();
3278         if (hlock->waittime_stamp) {
3279                 now = sched_clock();
3280                 waittime = now - hlock->waittime_stamp;
3281                 hlock->holdtime_stamp = now;
3282         }
3283
3284         trace_lock_acquired(lock, ip, waittime);
3285
3286         stats = get_lock_stats(hlock_class(hlock));
3287         if (waittime) {
3288                 if (hlock->read)
3289                         lock_time_inc(&stats->read_waittime, waittime);
3290                 else
3291                         lock_time_inc(&stats->write_waittime, waittime);
3292         }
3293         if (lock->cpu != cpu)
3294                 stats->bounces[bounce_acquired + !!hlock->read]++;
3295         put_lock_stats(stats);
3296
3297         lock->cpu = cpu;
3298         lock->ip = ip;
3299 }
3300
3301 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3302 {
3303         unsigned long flags;
3304
3305         trace_lock_contended(lock, ip);
3306
3307         if (unlikely(!lock_stat))
3308                 return;
3309
3310         if (unlikely(current->lockdep_recursion))
3311                 return;
3312
3313         raw_local_irq_save(flags);
3314         check_flags(flags);
3315         current->lockdep_recursion = 1;
3316         __lock_contended(lock, ip);
3317         current->lockdep_recursion = 0;
3318         raw_local_irq_restore(flags);
3319 }
3320 EXPORT_SYMBOL_GPL(lock_contended);
3321
3322 void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3323 {
3324         unsigned long flags;
3325
3326         if (unlikely(!lock_stat))
3327                 return;
3328
3329         if (unlikely(current->lockdep_recursion))
3330                 return;
3331
3332         raw_local_irq_save(flags);
3333         check_flags(flags);
3334         current->lockdep_recursion = 1;
3335         __lock_acquired(lock, ip);
3336         current->lockdep_recursion = 0;
3337         raw_local_irq_restore(flags);
3338 }
3339 EXPORT_SYMBOL_GPL(lock_acquired);
3340 #endif
3341
3342 /*
3343  * Used by the testsuite, sanitize the validator state
3344  * after a simulated failure:
3345  */
3346
3347 void lockdep_reset(void)
3348 {
3349         unsigned long flags;
3350         int i;
3351
3352         raw_local_irq_save(flags);
3353         current->curr_chain_key = 0;
3354         current->lockdep_depth = 0;
3355         current->lockdep_recursion = 0;
3356         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3357         nr_hardirq_chains = 0;
3358         nr_softirq_chains = 0;
3359         nr_process_chains = 0;
3360         debug_locks = 1;
3361         for (i = 0; i < CHAINHASH_SIZE; i++)
3362                 INIT_LIST_HEAD(chainhash_table + i);
3363         raw_local_irq_restore(flags);
3364 }
3365
3366 static void zap_class(struct lock_class *class)
3367 {
3368         int i;
3369
3370         /*
3371          * Remove all dependencies this lock is
3372          * involved in:
3373          */
3374         for (i = 0; i < nr_list_entries; i++) {
3375                 if (list_entries[i].class == class)
3376                         list_del_rcu(&list_entries[i].entry);
3377         }
3378         /*
3379          * Unhash the class and remove it from the all_lock_classes list:
3380          */
3381         list_del_rcu(&class->hash_entry);
3382         list_del_rcu(&class->lock_entry);
3383
3384         class->key = NULL;
3385 }
3386
3387 static inline int within(const void *addr, void *start, unsigned long size)
3388 {
3389         return addr >= start && addr < start + size;
3390 }
3391
3392 void lockdep_free_key_range(void *start, unsigned long size)
3393 {
3394         struct lock_class *class, *next;
3395         struct list_head *head;
3396         unsigned long flags;
3397         int i;
3398         int locked;
3399
3400         raw_local_irq_save(flags);
3401         locked = graph_lock();
3402
3403         /*
3404          * Unhash all classes that were created by this module:
3405          */
3406         for (i = 0; i < CLASSHASH_SIZE; i++) {
3407                 head = classhash_table + i;
3408                 if (list_empty(head))
3409                         continue;
3410                 list_for_each_entry_safe(class, next, head, hash_entry) {
3411                         if (within(class->key, start, size))
3412                                 zap_class(class);
3413                         else if (within(class->name, start, size))
3414                                 zap_class(class);
3415                 }
3416         }
3417
3418         if (locked)
3419                 graph_unlock();
3420         raw_local_irq_restore(flags);
3421 }
3422
3423 void lockdep_reset_lock(struct lockdep_map *lock)
3424 {
3425         struct lock_class *class, *next;
3426         struct list_head *head;
3427         unsigned long flags;
3428         int i, j;
3429         int locked;
3430
3431         raw_local_irq_save(flags);
3432
3433         /*
3434          * Remove all classes this lock might have:
3435          */
3436         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3437                 /*
3438                  * If the class exists we look it up and zap it:
3439                  */
3440                 class = look_up_lock_class(lock, j);
3441                 if (class)
3442                         zap_class(class);
3443         }
3444         /*
3445          * Debug check: in the end all mapped classes should
3446          * be gone.
3447          */
3448         locked = graph_lock();
3449         for (i = 0; i < CLASSHASH_SIZE; i++) {
3450                 head = classhash_table + i;
3451                 if (list_empty(head))
3452                         continue;
3453                 list_for_each_entry_safe(class, next, head, hash_entry) {
3454                         if (unlikely(class == lock->class_cache)) {
3455                                 if (debug_locks_off_graph_unlock())
3456                                         WARN_ON(1);
3457                                 goto out_restore;
3458                         }
3459                 }
3460         }
3461         if (locked)
3462                 graph_unlock();
3463
3464 out_restore:
3465         raw_local_irq_restore(flags);
3466 }
3467
3468 void lockdep_init(void)
3469 {
3470         int i;
3471
3472         /*
3473          * Some architectures have their own start_kernel()
3474          * code which calls lockdep_init(), while we also
3475          * call lockdep_init() from the start_kernel() itself,
3476          * and we want to initialize the hashes only once:
3477          */
3478         if (lockdep_initialized)
3479                 return;
3480
3481         for (i = 0; i < CLASSHASH_SIZE; i++)
3482                 INIT_LIST_HEAD(classhash_table + i);
3483
3484         for (i = 0; i < CHAINHASH_SIZE; i++)
3485                 INIT_LIST_HEAD(chainhash_table + i);
3486
3487         lockdep_initialized = 1;
3488 }
3489
3490 void __init lockdep_info(void)
3491 {
3492         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3493
3494         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3495         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3496         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3497         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3498         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3499         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3500         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3501
3502         printk(" memory used by lock dependency info: %lu kB\n",
3503                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3504                 sizeof(struct list_head) * CLASSHASH_SIZE +
3505                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3506                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3507                 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024
3508 #ifdef CONFIG_PROVE_LOCKING
3509                 + sizeof(struct circular_queue) + sizeof(bfs_accessed)
3510 #endif
3511                 );
3512
3513         printk(" per task-struct memory footprint: %lu bytes\n",
3514                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3515
3516 #ifdef CONFIG_DEBUG_LOCKDEP
3517         if (lockdep_init_error) {
3518                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3519                 printk("Call stack leading to lockdep invocation was:\n");
3520                 print_stack_trace(&lockdep_init_trace, 0);
3521         }
3522 #endif
3523 }
3524
3525 static void
3526 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3527                      const void *mem_to, struct held_lock *hlock)
3528 {
3529         if (!debug_locks_off())
3530                 return;
3531         if (debug_locks_silent)
3532                 return;
3533
3534         printk("\n=========================\n");
3535         printk(  "[ BUG: held lock freed! ]\n");
3536         printk(  "-------------------------\n");
3537         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3538                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3539         print_lock(hlock);
3540         lockdep_print_held_locks(curr);
3541
3542         printk("\nstack backtrace:\n");
3543         dump_stack();
3544 }
3545
3546 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3547                                 const void* lock_from, unsigned long lock_len)
3548 {
3549         return lock_from + lock_len <= mem_from ||
3550                 mem_from + mem_len <= lock_from;
3551 }
3552
3553 /*
3554  * Called when kernel memory is freed (or unmapped), or if a lock
3555  * is destroyed or reinitialized - this code checks whether there is
3556  * any held lock in the memory range of <from> to <to>:
3557  */
3558 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3559 {
3560         struct task_struct *curr = current;
3561         struct held_lock *hlock;
3562         unsigned long flags;
3563         int i;
3564
3565         if (unlikely(!debug_locks))
3566                 return;
3567
3568         local_irq_save(flags);
3569         for (i = 0; i < curr->lockdep_depth; i++) {
3570                 hlock = curr->held_locks + i;
3571
3572                 if (not_in_range(mem_from, mem_len, hlock->instance,
3573                                         sizeof(*hlock->instance)))
3574                         continue;
3575
3576                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3577                 break;
3578         }
3579         local_irq_restore(flags);
3580 }
3581 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3582
3583 static void print_held_locks_bug(struct task_struct *curr)
3584 {
3585         if (!debug_locks_off())
3586                 return;
3587         if (debug_locks_silent)
3588                 return;
3589
3590         printk("\n=====================================\n");
3591         printk(  "[ BUG: lock held at task exit time! ]\n");
3592         printk(  "-------------------------------------\n");
3593         printk("%s/%d is exiting with locks still held!\n",
3594                 curr->comm, task_pid_nr(curr));
3595         lockdep_print_held_locks(curr);
3596
3597         printk("\nstack backtrace:\n");
3598         dump_stack();
3599 }
3600
3601 void debug_check_no_locks_held(struct task_struct *task)
3602 {
3603         if (unlikely(task->lockdep_depth > 0))
3604                 print_held_locks_bug(task);
3605 }
3606
3607 void debug_show_all_locks(void)
3608 {
3609         struct task_struct *g, *p;
3610         int count = 10;
3611         int unlock = 1;
3612
3613         if (unlikely(!debug_locks)) {
3614                 printk("INFO: lockdep is turned off.\n");
3615                 return;
3616         }
3617         printk("\nShowing all locks held in the system:\n");
3618
3619         /*
3620          * Here we try to get the tasklist_lock as hard as possible,
3621          * if not successful after 2 seconds we ignore it (but keep
3622          * trying). This is to enable a debug printout even if a
3623          * tasklist_lock-holding task deadlocks or crashes.
3624          */
3625 retry:
3626         if (!read_trylock(&tasklist_lock)) {
3627                 if (count == 10)
3628                         printk("hm, tasklist_lock locked, retrying... ");
3629                 if (count) {
3630                         count--;
3631                         printk(" #%d", 10-count);
3632                         mdelay(200);
3633                         goto retry;
3634                 }
3635                 printk(" ignoring it.\n");
3636                 unlock = 0;
3637         } else {
3638                 if (count != 10)
3639                         printk(KERN_CONT " locked it.\n");
3640         }
3641
3642         do_each_thread(g, p) {
3643                 /*
3644                  * It's not reliable to print a task's held locks
3645                  * if it's not sleeping (or if it's not the current
3646                  * task):
3647                  */
3648                 if (p->state == TASK_RUNNING && p != current)
3649                         continue;
3650                 if (p->lockdep_depth)
3651                         lockdep_print_held_locks(p);
3652                 if (!unlock)
3653                         if (read_trylock(&tasklist_lock))
3654                                 unlock = 1;
3655         } while_each_thread(g, p);
3656
3657         printk("\n");
3658         printk("=============================================\n\n");
3659
3660         if (unlock)
3661                 read_unlock(&tasklist_lock);
3662 }
3663 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3664
3665 /*
3666  * Careful: only use this function if you are sure that
3667  * the task cannot run in parallel!
3668  */
3669 void __debug_show_held_locks(struct task_struct *task)
3670 {
3671         if (unlikely(!debug_locks)) {
3672                 printk("INFO: lockdep is turned off.\n");
3673                 return;
3674         }
3675         lockdep_print_held_locks(task);
3676 }
3677 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3678
3679 void debug_show_held_locks(struct task_struct *task)
3680 {
3681                 __debug_show_held_locks(task);
3682 }
3683 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3684
3685 void lockdep_sys_exit(void)
3686 {
3687         struct task_struct *curr = current;
3688
3689         if (unlikely(curr->lockdep_depth)) {
3690                 if (!debug_locks_off())
3691                         return;
3692                 printk("\n================================================\n");
3693                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3694                 printk(  "------------------------------------------------\n");
3695                 printk("%s/%d is leaving the kernel with locks still held!\n",
3696                                 curr->comm, curr->pid);
3697                 lockdep_print_held_locks(curr);
3698         }
3699 }