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