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