ftrace: replace raw_local_irq_save with local_irq_save
[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
45 #include <asm/sections.h>
46
47 #include "lockdep_internals.h"
48
49 #ifdef CONFIG_PROVE_LOCKING
50 int prove_locking = 1;
51 module_param(prove_locking, int, 0644);
52 #else
53 #define prove_locking 0
54 #endif
55
56 #ifdef CONFIG_LOCK_STAT
57 int lock_stat = 1;
58 module_param(lock_stat, int, 0644);
59 #else
60 #define lock_stat 0
61 #endif
62
63 /*
64  * lockdep_lock: protects the lockdep graph, the hashes and the
65  *               class/list/hash allocators.
66  *
67  * This is one of the rare exceptions where it's justified
68  * to use a raw spinlock - we really dont want the spinlock
69  * code to recurse back into the lockdep code...
70  */
71 static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
72
73 static int graph_lock(void)
74 {
75         __raw_spin_lock(&lockdep_lock);
76         /*
77          * Make sure that if another CPU detected a bug while
78          * walking the graph we dont change it (while the other
79          * CPU is busy printing out stuff with the graph lock
80          * dropped already)
81          */
82         if (!debug_locks) {
83                 __raw_spin_unlock(&lockdep_lock);
84                 return 0;
85         }
86         /* prevent any recursions within lockdep from causing deadlocks */
87         current->lockdep_recursion++;
88         return 1;
89 }
90
91 static inline int graph_unlock(void)
92 {
93         if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
94                 return DEBUG_LOCKS_WARN_ON(1);
95
96         current->lockdep_recursion--;
97         __raw_spin_unlock(&lockdep_lock);
98         return 0;
99 }
100
101 /*
102  * Turn lock debugging off and return with 0 if it was off already,
103  * and also release the graph lock:
104  */
105 static inline int debug_locks_off_graph_unlock(void)
106 {
107         int ret = debug_locks_off();
108
109         __raw_spin_unlock(&lockdep_lock);
110
111         return ret;
112 }
113
114 static int lockdep_initialized;
115
116 unsigned long nr_list_entries;
117 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
118
119 /*
120  * All data structures here are protected by the global debug_lock.
121  *
122  * Mutex key structs only get allocated, once during bootup, and never
123  * get freed - this significantly simplifies the debugging code.
124  */
125 unsigned long nr_lock_classes;
126 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
127
128 static inline struct lock_class *hlock_class(struct held_lock *hlock)
129 {
130         if (!hlock->class_idx) {
131                 DEBUG_LOCKS_WARN_ON(1);
132                 return NULL;
133         }
134         return lock_classes + hlock->class_idx - 1;
135 }
136
137 #ifdef CONFIG_LOCK_STAT
138 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
139
140 static int lock_contention_point(struct lock_class *class, unsigned long ip)
141 {
142         int i;
143
144         for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {
145                 if (class->contention_point[i] == 0) {
146                         class->contention_point[i] = ip;
147                         break;
148                 }
149                 if (class->contention_point[i] == ip)
150                         break;
151         }
152
153         return i;
154 }
155
156 static void lock_time_inc(struct lock_time *lt, s64 time)
157 {
158         if (time > lt->max)
159                 lt->max = time;
160
161         if (time < lt->min || !lt->min)
162                 lt->min = time;
163
164         lt->total += time;
165         lt->nr++;
166 }
167
168 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
169 {
170         dst->min += src->min;
171         dst->max += src->max;
172         dst->total += src->total;
173         dst->nr += src->nr;
174 }
175
176 struct lock_class_stats lock_stats(struct lock_class *class)
177 {
178         struct lock_class_stats stats;
179         int cpu, i;
180
181         memset(&stats, 0, sizeof(struct lock_class_stats));
182         for_each_possible_cpu(cpu) {
183                 struct lock_class_stats *pcs =
184                         &per_cpu(lock_stats, cpu)[class - lock_classes];
185
186                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
187                         stats.contention_point[i] += pcs->contention_point[i];
188
189                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
190                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
191
192                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
193                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
194
195                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
196                         stats.bounces[i] += pcs->bounces[i];
197         }
198
199         return stats;
200 }
201
202 void clear_lock_stats(struct lock_class *class)
203 {
204         int cpu;
205
206         for_each_possible_cpu(cpu) {
207                 struct lock_class_stats *cpu_stats =
208                         &per_cpu(lock_stats, cpu)[class - lock_classes];
209
210                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
211         }
212         memset(class->contention_point, 0, sizeof(class->contention_point));
213 }
214
215 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
216 {
217         return &get_cpu_var(lock_stats)[class - lock_classes];
218 }
219
220 static void put_lock_stats(struct lock_class_stats *stats)
221 {
222         put_cpu_var(lock_stats);
223 }
224
225 static void lock_release_holdtime(struct held_lock *hlock)
226 {
227         struct lock_class_stats *stats;
228         s64 holdtime;
229
230         if (!lock_stat)
231                 return;
232
233         holdtime = sched_clock() - hlock->holdtime_stamp;
234
235         stats = get_lock_stats(hlock_class(hlock));
236         if (hlock->read)
237                 lock_time_inc(&stats->read_holdtime, holdtime);
238         else
239                 lock_time_inc(&stats->write_holdtime, holdtime);
240         put_lock_stats(stats);
241 }
242 #else
243 static inline void lock_release_holdtime(struct held_lock *hlock)
244 {
245 }
246 #endif
247
248 /*
249  * We keep a global list of all lock classes. The list only grows,
250  * never shrinks. The list is only accessed with the lockdep
251  * spinlock lock held.
252  */
253 LIST_HEAD(all_lock_classes);
254
255 /*
256  * The lockdep classes are in a hash-table as well, for fast lookup:
257  */
258 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
259 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
260 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
261 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
262
263 static struct list_head classhash_table[CLASSHASH_SIZE];
264
265 /*
266  * We put the lock dependency chains into a hash-table as well, to cache
267  * their existence:
268  */
269 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
270 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
271 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
272 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
273
274 static struct list_head chainhash_table[CHAINHASH_SIZE];
275
276 /*
277  * The hash key of the lock dependency chains is a hash itself too:
278  * it's a hash of all locks taken up to that lock, including that lock.
279  * It's a 64-bit hash, because it's important for the keys to be
280  * unique.
281  */
282 #define iterate_chain_key(key1, key2) \
283         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
284         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
285         (key2))
286
287 void lockdep_off(void)
288 {
289         current->lockdep_recursion++;
290 }
291
292 EXPORT_SYMBOL(lockdep_off);
293
294 void lockdep_on(void)
295 {
296         current->lockdep_recursion--;
297 }
298
299 EXPORT_SYMBOL(lockdep_on);
300
301 /*
302  * Debugging switches:
303  */
304
305 #define VERBOSE                 0
306 #define VERY_VERBOSE            0
307
308 #if VERBOSE
309 # define HARDIRQ_VERBOSE        1
310 # define SOFTIRQ_VERBOSE        1
311 #else
312 # define HARDIRQ_VERBOSE        0
313 # define SOFTIRQ_VERBOSE        0
314 #endif
315
316 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
317 /*
318  * Quick filtering for interesting events:
319  */
320 static int class_filter(struct lock_class *class)
321 {
322 #if 0
323         /* Example */
324         if (class->name_version == 1 &&
325                         !strcmp(class->name, "lockname"))
326                 return 1;
327         if (class->name_version == 1 &&
328                         !strcmp(class->name, "&struct->lockfield"))
329                 return 1;
330 #endif
331         /* Filter everything else. 1 would be to allow everything else */
332         return 0;
333 }
334 #endif
335
336 static int verbose(struct lock_class *class)
337 {
338 #if VERBOSE
339         return class_filter(class);
340 #endif
341         return 0;
342 }
343
344 /*
345  * Stack-trace: tightly packed array of stack backtrace
346  * addresses. Protected by the graph_lock.
347  */
348 unsigned long nr_stack_trace_entries;
349 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
350
351 static int save_trace(struct stack_trace *trace)
352 {
353         trace->nr_entries = 0;
354         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
355         trace->entries = stack_trace + nr_stack_trace_entries;
356
357         trace->skip = 3;
358
359         save_stack_trace(trace);
360
361         trace->max_entries = trace->nr_entries;
362
363         nr_stack_trace_entries += trace->nr_entries;
364
365         if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
366                 if (!debug_locks_off_graph_unlock())
367                         return 0;
368
369                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
370                 printk("turning off the locking correctness validator.\n");
371                 dump_stack();
372
373                 return 0;
374         }
375
376         return 1;
377 }
378
379 unsigned int nr_hardirq_chains;
380 unsigned int nr_softirq_chains;
381 unsigned int nr_process_chains;
382 unsigned int max_lockdep_depth;
383 unsigned int max_recursion_depth;
384
385 static unsigned int lockdep_dependency_gen_id;
386
387 static bool lockdep_dependency_visit(struct lock_class *source,
388                                      unsigned int depth)
389 {
390         if (!depth)
391                 lockdep_dependency_gen_id++;
392         if (source->dep_gen_id == lockdep_dependency_gen_id)
393                 return true;
394         source->dep_gen_id = lockdep_dependency_gen_id;
395         return false;
396 }
397
398 #ifdef CONFIG_DEBUG_LOCKDEP
399 /*
400  * We cannot printk in early bootup code. Not even early_printk()
401  * might work. So we mark any initialization errors and printk
402  * about it later on, in lockdep_info().
403  */
404 static int lockdep_init_error;
405 static unsigned long lockdep_init_trace_data[20];
406 static struct stack_trace lockdep_init_trace = {
407         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
408         .entries = lockdep_init_trace_data,
409 };
410
411 /*
412  * Various lockdep statistics:
413  */
414 atomic_t chain_lookup_hits;
415 atomic_t chain_lookup_misses;
416 atomic_t hardirqs_on_events;
417 atomic_t hardirqs_off_events;
418 atomic_t redundant_hardirqs_on;
419 atomic_t redundant_hardirqs_off;
420 atomic_t softirqs_on_events;
421 atomic_t softirqs_off_events;
422 atomic_t redundant_softirqs_on;
423 atomic_t redundant_softirqs_off;
424 atomic_t nr_unused_locks;
425 atomic_t nr_cyclic_checks;
426 atomic_t nr_cyclic_check_recursions;
427 atomic_t nr_find_usage_forwards_checks;
428 atomic_t nr_find_usage_forwards_recursions;
429 atomic_t nr_find_usage_backwards_checks;
430 atomic_t nr_find_usage_backwards_recursions;
431 # define debug_atomic_inc(ptr)          atomic_inc(ptr)
432 # define debug_atomic_dec(ptr)          atomic_dec(ptr)
433 # define debug_atomic_read(ptr)         atomic_read(ptr)
434 #else
435 # define debug_atomic_inc(ptr)          do { } while (0)
436 # define debug_atomic_dec(ptr)          do { } while (0)
437 # define debug_atomic_read(ptr)         0
438 #endif
439
440 /*
441  * Locking printouts:
442  */
443
444 static const char *usage_str[] =
445 {
446         [LOCK_USED] =                   "initial-use ",
447         [LOCK_USED_IN_HARDIRQ] =        "in-hardirq-W",
448         [LOCK_USED_IN_SOFTIRQ] =        "in-softirq-W",
449         [LOCK_ENABLED_SOFTIRQS] =       "softirq-on-W",
450         [LOCK_ENABLED_HARDIRQS] =       "hardirq-on-W",
451         [LOCK_USED_IN_HARDIRQ_READ] =   "in-hardirq-R",
452         [LOCK_USED_IN_SOFTIRQ_READ] =   "in-softirq-R",
453         [LOCK_ENABLED_SOFTIRQS_READ] =  "softirq-on-R",
454         [LOCK_ENABLED_HARDIRQS_READ] =  "hardirq-on-R",
455 };
456
457 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
458 {
459         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
460 }
461
462 void
463 get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
464 {
465         *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
466
467         if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
468                 *c1 = '+';
469         else
470                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
471                         *c1 = '-';
472
473         if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
474                 *c2 = '+';
475         else
476                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
477                         *c2 = '-';
478
479         if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
480                 *c3 = '-';
481         if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
482                 *c3 = '+';
483                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
484                         *c3 = '?';
485         }
486
487         if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
488                 *c4 = '-';
489         if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
490                 *c4 = '+';
491                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
492                         *c4 = '?';
493         }
494 }
495
496 static void print_lock_name(struct lock_class *class)
497 {
498         char str[KSYM_NAME_LEN], c1, c2, c3, c4;
499         const char *name;
500
501         get_usage_chars(class, &c1, &c2, &c3, &c4);
502
503         name = class->name;
504         if (!name) {
505                 name = __get_key_name(class->key, str);
506                 printk(" (%s", name);
507         } else {
508                 printk(" (%s", name);
509                 if (class->name_version > 1)
510                         printk("#%d", class->name_version);
511                 if (class->subclass)
512                         printk("/%d", class->subclass);
513         }
514         printk("){%c%c%c%c}", c1, c2, c3, c4);
515 }
516
517 static void print_lockdep_cache(struct lockdep_map *lock)
518 {
519         const char *name;
520         char str[KSYM_NAME_LEN];
521
522         name = lock->name;
523         if (!name)
524                 name = __get_key_name(lock->key->subkeys, str);
525
526         printk("%s", name);
527 }
528
529 static void print_lock(struct held_lock *hlock)
530 {
531         print_lock_name(hlock_class(hlock));
532         printk(", at: ");
533         print_ip_sym(hlock->acquire_ip);
534 }
535
536 static void lockdep_print_held_locks(struct task_struct *curr)
537 {
538         int i, depth = curr->lockdep_depth;
539
540         if (!depth) {
541                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
542                 return;
543         }
544         printk("%d lock%s held by %s/%d:\n",
545                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
546
547         for (i = 0; i < depth; i++) {
548                 printk(" #%d: ", i);
549                 print_lock(curr->held_locks + i);
550         }
551 }
552
553 static void print_lock_class_header(struct lock_class *class, int depth)
554 {
555         int bit;
556
557         printk("%*s->", depth, "");
558         print_lock_name(class);
559         printk(" ops: %lu", class->ops);
560         printk(" {\n");
561
562         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
563                 if (class->usage_mask & (1 << bit)) {
564                         int len = depth;
565
566                         len += printk("%*s   %s", depth, "", usage_str[bit]);
567                         len += printk(" at:\n");
568                         print_stack_trace(class->usage_traces + bit, len);
569                 }
570         }
571         printk("%*s }\n", depth, "");
572
573         printk("%*s ... key      at: ",depth,"");
574         print_ip_sym((unsigned long)class->key);
575 }
576
577 /*
578  * printk all lock dependencies starting at <entry>:
579  */
580 static void print_lock_dependencies(struct lock_class *class, int depth)
581 {
582         struct lock_list *entry;
583
584         if (lockdep_dependency_visit(class, depth))
585                 return;
586
587         if (DEBUG_LOCKS_WARN_ON(depth >= 20))
588                 return;
589
590         print_lock_class_header(class, depth);
591
592         list_for_each_entry(entry, &class->locks_after, entry) {
593                 if (DEBUG_LOCKS_WARN_ON(!entry->class))
594                         return;
595
596                 print_lock_dependencies(entry->class, depth + 1);
597
598                 printk("%*s ... acquired at:\n",depth,"");
599                 print_stack_trace(&entry->trace, 2);
600                 printk("\n");
601         }
602 }
603
604 static void print_kernel_version(void)
605 {
606         printk("%s %.*s\n", init_utsname()->release,
607                 (int)strcspn(init_utsname()->version, " "),
608                 init_utsname()->version);
609 }
610
611 static int very_verbose(struct lock_class *class)
612 {
613 #if VERY_VERBOSE
614         return class_filter(class);
615 #endif
616         return 0;
617 }
618
619 /*
620  * Is this the address of a static object:
621  */
622 static int static_obj(void *obj)
623 {
624         unsigned long start = (unsigned long) &_stext,
625                       end   = (unsigned long) &_end,
626                       addr  = (unsigned long) obj;
627 #ifdef CONFIG_SMP
628         int i;
629 #endif
630
631         /*
632          * static variable?
633          */
634         if ((addr >= start) && (addr < end))
635                 return 1;
636
637 #ifdef CONFIG_SMP
638         /*
639          * percpu var?
640          */
641         for_each_possible_cpu(i) {
642                 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
643                 end   = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
644                                         + per_cpu_offset(i);
645
646                 if ((addr >= start) && (addr < end))
647                         return 1;
648         }
649 #endif
650
651         /*
652          * module var?
653          */
654         return is_module_address(addr);
655 }
656
657 /*
658  * To make lock name printouts unique, we calculate a unique
659  * class->name_version generation counter:
660  */
661 static int count_matching_names(struct lock_class *new_class)
662 {
663         struct lock_class *class;
664         int count = 0;
665
666         if (!new_class->name)
667                 return 0;
668
669         list_for_each_entry(class, &all_lock_classes, lock_entry) {
670                 if (new_class->key - new_class->subclass == class->key)
671                         return class->name_version;
672                 if (class->name && !strcmp(class->name, new_class->name))
673                         count = max(count, class->name_version);
674         }
675
676         return count + 1;
677 }
678
679 /*
680  * Register a lock's class in the hash-table, if the class is not present
681  * yet. Otherwise we look it up. We cache the result in the lock object
682  * itself, so actual lookup of the hash should be once per lock object.
683  */
684 static inline struct lock_class *
685 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
686 {
687         struct lockdep_subclass_key *key;
688         struct list_head *hash_head;
689         struct lock_class *class;
690
691 #ifdef CONFIG_DEBUG_LOCKDEP
692         /*
693          * If the architecture calls into lockdep before initializing
694          * the hashes then we'll warn about it later. (we cannot printk
695          * right now)
696          */
697         if (unlikely(!lockdep_initialized)) {
698                 lockdep_init();
699                 lockdep_init_error = 1;
700                 save_stack_trace(&lockdep_init_trace);
701         }
702 #endif
703
704         /*
705          * Static locks do not have their class-keys yet - for them the key
706          * is the lock object itself:
707          */
708         if (unlikely(!lock->key))
709                 lock->key = (void *)lock;
710
711         /*
712          * NOTE: the class-key must be unique. For dynamic locks, a static
713          * lock_class_key variable is passed in through the mutex_init()
714          * (or spin_lock_init()) call - which acts as the key. For static
715          * locks we use the lock object itself as the key.
716          */
717         BUILD_BUG_ON(sizeof(struct lock_class_key) >
718                         sizeof(struct lockdep_map));
719
720         key = lock->key->subkeys + subclass;
721
722         hash_head = classhashentry(key);
723
724         /*
725          * We can walk the hash lockfree, because the hash only
726          * grows, and we are careful when adding entries to the end:
727          */
728         list_for_each_entry(class, hash_head, hash_entry) {
729                 if (class->key == key) {
730                         WARN_ON_ONCE(class->name != lock->name);
731                         return class;
732                 }
733         }
734
735         return NULL;
736 }
737
738 /*
739  * Register a lock's class in the hash-table, if the class is not present
740  * yet. Otherwise we look it up. We cache the result in the lock object
741  * itself, so actual lookup of the hash should be once per lock object.
742  */
743 static inline struct lock_class *
744 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
745 {
746         struct lockdep_subclass_key *key;
747         struct list_head *hash_head;
748         struct lock_class *class;
749         unsigned long flags;
750
751         class = look_up_lock_class(lock, subclass);
752         if (likely(class))
753                 return class;
754
755         /*
756          * Debug-check: all keys must be persistent!
757          */
758         if (!static_obj(lock->key)) {
759                 debug_locks_off();
760                 printk("INFO: trying to register non-static key.\n");
761                 printk("the code is fine but needs lockdep annotation.\n");
762                 printk("turning off the locking correctness validator.\n");
763                 dump_stack();
764
765                 return NULL;
766         }
767
768         key = lock->key->subkeys + subclass;
769         hash_head = classhashentry(key);
770
771         raw_local_irq_save(flags);
772         if (!graph_lock()) {
773                 raw_local_irq_restore(flags);
774                 return NULL;
775         }
776         /*
777          * We have to do the hash-walk again, to avoid races
778          * with another CPU:
779          */
780         list_for_each_entry(class, hash_head, hash_entry)
781                 if (class->key == key)
782                         goto out_unlock_set;
783         /*
784          * Allocate a new key from the static array, and add it to
785          * the hash:
786          */
787         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
788                 if (!debug_locks_off_graph_unlock()) {
789                         raw_local_irq_restore(flags);
790                         return NULL;
791                 }
792                 raw_local_irq_restore(flags);
793
794                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
795                 printk("turning off the locking correctness validator.\n");
796                 return NULL;
797         }
798         class = lock_classes + nr_lock_classes++;
799         debug_atomic_inc(&nr_unused_locks);
800         class->key = key;
801         class->name = lock->name;
802         class->subclass = subclass;
803         INIT_LIST_HEAD(&class->lock_entry);
804         INIT_LIST_HEAD(&class->locks_before);
805         INIT_LIST_HEAD(&class->locks_after);
806         class->name_version = count_matching_names(class);
807         /*
808          * We use RCU's safe list-add method to make
809          * parallel walking of the hash-list safe:
810          */
811         list_add_tail_rcu(&class->hash_entry, hash_head);
812         /*
813          * Add it to the global list of classes:
814          */
815         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
816
817         if (verbose(class)) {
818                 graph_unlock();
819                 raw_local_irq_restore(flags);
820
821                 printk("\nnew class %p: %s", class->key, class->name);
822                 if (class->name_version > 1)
823                         printk("#%d", class->name_version);
824                 printk("\n");
825                 dump_stack();
826
827                 raw_local_irq_save(flags);
828                 if (!graph_lock()) {
829                         raw_local_irq_restore(flags);
830                         return NULL;
831                 }
832         }
833 out_unlock_set:
834         graph_unlock();
835         raw_local_irq_restore(flags);
836
837         if (!subclass || force)
838                 lock->class_cache = class;
839
840         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
841                 return NULL;
842
843         return class;
844 }
845
846 #ifdef CONFIG_PROVE_LOCKING
847 /*
848  * Allocate a lockdep entry. (assumes the graph_lock held, returns
849  * with NULL on failure)
850  */
851 static struct lock_list *alloc_list_entry(void)
852 {
853         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
854                 if (!debug_locks_off_graph_unlock())
855                         return NULL;
856
857                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
858                 printk("turning off the locking correctness validator.\n");
859                 return NULL;
860         }
861         return list_entries + nr_list_entries++;
862 }
863
864 /*
865  * Add a new dependency to the head of the list:
866  */
867 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
868                             struct list_head *head, unsigned long ip, int distance)
869 {
870         struct lock_list *entry;
871         /*
872          * Lock not present yet - get a new dependency struct and
873          * add it to the list:
874          */
875         entry = alloc_list_entry();
876         if (!entry)
877                 return 0;
878
879         if (!save_trace(&entry->trace))
880                 return 0;
881
882         entry->class = this;
883         entry->distance = distance;
884         /*
885          * Since we never remove from the dependency list, the list can
886          * be walked lockless by other CPUs, it's only allocation
887          * that must be protected by the spinlock. But this also means
888          * we must make new entries visible only once writes to the
889          * entry become visible - hence the RCU op:
890          */
891         list_add_tail_rcu(&entry->entry, head);
892
893         return 1;
894 }
895
896 /*
897  * Recursive, forwards-direction lock-dependency checking, used for
898  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
899  * checking.
900  *
901  * (to keep the stackframe of the recursive functions small we
902  *  use these global variables, and we also mark various helper
903  *  functions as noinline.)
904  */
905 static struct held_lock *check_source, *check_target;
906
907 /*
908  * Print a dependency chain entry (this is only done when a deadlock
909  * has been detected):
910  */
911 static noinline int
912 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
913 {
914         if (debug_locks_silent)
915                 return 0;
916         printk("\n-> #%u", depth);
917         print_lock_name(target->class);
918         printk(":\n");
919         print_stack_trace(&target->trace, 6);
920
921         return 0;
922 }
923
924 /*
925  * When a circular dependency is detected, print the
926  * header first:
927  */
928 static noinline int
929 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
930 {
931         struct task_struct *curr = current;
932
933         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
934                 return 0;
935
936         printk("\n=======================================================\n");
937         printk(  "[ INFO: possible circular locking dependency detected ]\n");
938         print_kernel_version();
939         printk(  "-------------------------------------------------------\n");
940         printk("%s/%d is trying to acquire lock:\n",
941                 curr->comm, task_pid_nr(curr));
942         print_lock(check_source);
943         printk("\nbut task is already holding lock:\n");
944         print_lock(check_target);
945         printk("\nwhich lock already depends on the new lock.\n\n");
946         printk("\nthe existing dependency chain (in reverse order) is:\n");
947
948         print_circular_bug_entry(entry, depth);
949
950         return 0;
951 }
952
953 static noinline int print_circular_bug_tail(void)
954 {
955         struct task_struct *curr = current;
956         struct lock_list this;
957
958         if (debug_locks_silent)
959                 return 0;
960
961         this.class = hlock_class(check_source);
962         if (!save_trace(&this.trace))
963                 return 0;
964
965         print_circular_bug_entry(&this, 0);
966
967         printk("\nother info that might help us debug this:\n\n");
968         lockdep_print_held_locks(curr);
969
970         printk("\nstack backtrace:\n");
971         dump_stack();
972
973         return 0;
974 }
975
976 #define RECURSION_LIMIT 40
977
978 static int noinline print_infinite_recursion_bug(void)
979 {
980         if (!debug_locks_off_graph_unlock())
981                 return 0;
982
983         WARN_ON(1);
984
985         return 0;
986 }
987
988 unsigned long __lockdep_count_forward_deps(struct lock_class *class,
989                                            unsigned int depth)
990 {
991         struct lock_list *entry;
992         unsigned long ret = 1;
993
994         if (lockdep_dependency_visit(class, depth))
995                 return 0;
996
997         /*
998          * Recurse this class's dependency list:
999          */
1000         list_for_each_entry(entry, &class->locks_after, entry)
1001                 ret += __lockdep_count_forward_deps(entry->class, depth + 1);
1002
1003         return ret;
1004 }
1005
1006 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1007 {
1008         unsigned long ret, flags;
1009
1010         local_irq_save(flags);
1011         __raw_spin_lock(&lockdep_lock);
1012         ret = __lockdep_count_forward_deps(class, 0);
1013         __raw_spin_unlock(&lockdep_lock);
1014         local_irq_restore(flags);
1015
1016         return ret;
1017 }
1018
1019 unsigned long __lockdep_count_backward_deps(struct lock_class *class,
1020                                             unsigned int depth)
1021 {
1022         struct lock_list *entry;
1023         unsigned long ret = 1;
1024
1025         if (lockdep_dependency_visit(class, depth))
1026                 return 0;
1027         /*
1028          * Recurse this class's dependency list:
1029          */
1030         list_for_each_entry(entry, &class->locks_before, entry)
1031                 ret += __lockdep_count_backward_deps(entry->class, depth + 1);
1032
1033         return ret;
1034 }
1035
1036 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1037 {
1038         unsigned long ret, flags;
1039
1040         local_irq_save(flags);
1041         __raw_spin_lock(&lockdep_lock);
1042         ret = __lockdep_count_backward_deps(class, 0);
1043         __raw_spin_unlock(&lockdep_lock);
1044         local_irq_restore(flags);
1045
1046         return ret;
1047 }
1048
1049 /*
1050  * Prove that the dependency graph starting at <entry> can not
1051  * lead to <target>. Print an error and return 0 if it does.
1052  */
1053 static noinline int
1054 check_noncircular(struct lock_class *source, unsigned int depth)
1055 {
1056         struct lock_list *entry;
1057
1058         if (lockdep_dependency_visit(source, depth))
1059                 return 1;
1060
1061         debug_atomic_inc(&nr_cyclic_check_recursions);
1062         if (depth > max_recursion_depth)
1063                 max_recursion_depth = depth;
1064         if (depth >= RECURSION_LIMIT)
1065                 return print_infinite_recursion_bug();
1066         /*
1067          * Check this lock's dependency list:
1068          */
1069         list_for_each_entry(entry, &source->locks_after, entry) {
1070                 if (entry->class == hlock_class(check_target))
1071                         return print_circular_bug_header(entry, depth+1);
1072                 debug_atomic_inc(&nr_cyclic_checks);
1073                 if (!check_noncircular(entry->class, depth+1))
1074                         return print_circular_bug_entry(entry, depth+1);
1075         }
1076         return 1;
1077 }
1078
1079 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1080 /*
1081  * Forwards and backwards subgraph searching, for the purposes of
1082  * proving that two subgraphs can be connected by a new dependency
1083  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1084  */
1085 static enum lock_usage_bit find_usage_bit;
1086 static struct lock_class *forwards_match, *backwards_match;
1087
1088 /*
1089  * Find a node in the forwards-direction dependency sub-graph starting
1090  * at <source> that matches <find_usage_bit>.
1091  *
1092  * Return 2 if such a node exists in the subgraph, and put that node
1093  * into <forwards_match>.
1094  *
1095  * Return 1 otherwise and keep <forwards_match> unchanged.
1096  * Return 0 on error.
1097  */
1098 static noinline int
1099 find_usage_forwards(struct lock_class *source, unsigned int depth)
1100 {
1101         struct lock_list *entry;
1102         int ret;
1103
1104         if (lockdep_dependency_visit(source, depth))
1105                 return 1;
1106
1107         if (depth > max_recursion_depth)
1108                 max_recursion_depth = depth;
1109         if (depth >= RECURSION_LIMIT)
1110                 return print_infinite_recursion_bug();
1111
1112         debug_atomic_inc(&nr_find_usage_forwards_checks);
1113         if (source->usage_mask & (1 << find_usage_bit)) {
1114                 forwards_match = source;
1115                 return 2;
1116         }
1117
1118         /*
1119          * Check this lock's dependency list:
1120          */
1121         list_for_each_entry(entry, &source->locks_after, entry) {
1122                 debug_atomic_inc(&nr_find_usage_forwards_recursions);
1123                 ret = find_usage_forwards(entry->class, depth+1);
1124                 if (ret == 2 || ret == 0)
1125                         return ret;
1126         }
1127         return 1;
1128 }
1129
1130 /*
1131  * Find a node in the backwards-direction dependency sub-graph starting
1132  * at <source> that matches <find_usage_bit>.
1133  *
1134  * Return 2 if such a node exists in the subgraph, and put that node
1135  * into <backwards_match>.
1136  *
1137  * Return 1 otherwise and keep <backwards_match> unchanged.
1138  * Return 0 on error.
1139  */
1140 static noinline int
1141 find_usage_backwards(struct lock_class *source, unsigned int depth)
1142 {
1143         struct lock_list *entry;
1144         int ret;
1145
1146         if (lockdep_dependency_visit(source, depth))
1147                 return 1;
1148
1149         if (!__raw_spin_is_locked(&lockdep_lock))
1150                 return DEBUG_LOCKS_WARN_ON(1);
1151
1152         if (depth > max_recursion_depth)
1153                 max_recursion_depth = depth;
1154         if (depth >= RECURSION_LIMIT)
1155                 return print_infinite_recursion_bug();
1156
1157         debug_atomic_inc(&nr_find_usage_backwards_checks);
1158         if (source->usage_mask & (1 << find_usage_bit)) {
1159                 backwards_match = source;
1160                 return 2;
1161         }
1162
1163         if (!source && debug_locks_off_graph_unlock()) {
1164                 WARN_ON(1);
1165                 return 0;
1166         }
1167
1168         /*
1169          * Check this lock's dependency list:
1170          */
1171         list_for_each_entry(entry, &source->locks_before, entry) {
1172                 debug_atomic_inc(&nr_find_usage_backwards_recursions);
1173                 ret = find_usage_backwards(entry->class, depth+1);
1174                 if (ret == 2 || ret == 0)
1175                         return ret;
1176         }
1177         return 1;
1178 }
1179
1180 static int
1181 print_bad_irq_dependency(struct task_struct *curr,
1182                          struct held_lock *prev,
1183                          struct held_lock *next,
1184                          enum lock_usage_bit bit1,
1185                          enum lock_usage_bit bit2,
1186                          const char *irqclass)
1187 {
1188         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1189                 return 0;
1190
1191         printk("\n======================================================\n");
1192         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1193                 irqclass, irqclass);
1194         print_kernel_version();
1195         printk(  "------------------------------------------------------\n");
1196         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1197                 curr->comm, task_pid_nr(curr),
1198                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1199                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1200                 curr->hardirqs_enabled,
1201                 curr->softirqs_enabled);
1202         print_lock(next);
1203
1204         printk("\nand this task is already holding:\n");
1205         print_lock(prev);
1206         printk("which would create a new lock dependency:\n");
1207         print_lock_name(hlock_class(prev));
1208         printk(" ->");
1209         print_lock_name(hlock_class(next));
1210         printk("\n");
1211
1212         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1213                 irqclass);
1214         print_lock_name(backwards_match);
1215         printk("\n... which became %s-irq-safe at:\n", irqclass);
1216
1217         print_stack_trace(backwards_match->usage_traces + bit1, 1);
1218
1219         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1220         print_lock_name(forwards_match);
1221         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1222         printk("...");
1223
1224         print_stack_trace(forwards_match->usage_traces + bit2, 1);
1225
1226         printk("\nother info that might help us debug this:\n\n");
1227         lockdep_print_held_locks(curr);
1228
1229         printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1230         print_lock_dependencies(backwards_match, 0);
1231
1232         printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1233         print_lock_dependencies(forwards_match, 0);
1234
1235         printk("\nstack backtrace:\n");
1236         dump_stack();
1237
1238         return 0;
1239 }
1240
1241 static int
1242 check_usage(struct task_struct *curr, struct held_lock *prev,
1243             struct held_lock *next, enum lock_usage_bit bit_backwards,
1244             enum lock_usage_bit bit_forwards, const char *irqclass)
1245 {
1246         int ret;
1247
1248         find_usage_bit = bit_backwards;
1249         /* fills in <backwards_match> */
1250         ret = find_usage_backwards(hlock_class(prev), 0);
1251         if (!ret || ret == 1)
1252                 return ret;
1253
1254         find_usage_bit = bit_forwards;
1255         ret = find_usage_forwards(hlock_class(next), 0);
1256         if (!ret || ret == 1)
1257                 return ret;
1258         /* ret == 2 */
1259         return print_bad_irq_dependency(curr, prev, next,
1260                         bit_backwards, bit_forwards, irqclass);
1261 }
1262
1263 static int
1264 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1265                 struct held_lock *next)
1266 {
1267         /*
1268          * Prove that the new dependency does not connect a hardirq-safe
1269          * lock with a hardirq-unsafe lock - to achieve this we search
1270          * the backwards-subgraph starting at <prev>, and the
1271          * forwards-subgraph starting at <next>:
1272          */
1273         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
1274                                         LOCK_ENABLED_HARDIRQS, "hard"))
1275                 return 0;
1276
1277         /*
1278          * Prove that the new dependency does not connect a hardirq-safe-read
1279          * lock with a hardirq-unsafe lock - to achieve this we search
1280          * the backwards-subgraph starting at <prev>, and the
1281          * forwards-subgraph starting at <next>:
1282          */
1283         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
1284                                         LOCK_ENABLED_HARDIRQS, "hard-read"))
1285                 return 0;
1286
1287         /*
1288          * Prove that the new dependency does not connect a softirq-safe
1289          * lock with a softirq-unsafe lock - to achieve this we search
1290          * the backwards-subgraph starting at <prev>, and the
1291          * forwards-subgraph starting at <next>:
1292          */
1293         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
1294                                         LOCK_ENABLED_SOFTIRQS, "soft"))
1295                 return 0;
1296         /*
1297          * Prove that the new dependency does not connect a softirq-safe-read
1298          * lock with a softirq-unsafe lock - to achieve this we search
1299          * the backwards-subgraph starting at <prev>, and the
1300          * forwards-subgraph starting at <next>:
1301          */
1302         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
1303                                         LOCK_ENABLED_SOFTIRQS, "soft"))
1304                 return 0;
1305
1306         return 1;
1307 }
1308
1309 static void inc_chains(void)
1310 {
1311         if (current->hardirq_context)
1312                 nr_hardirq_chains++;
1313         else {
1314                 if (current->softirq_context)
1315                         nr_softirq_chains++;
1316                 else
1317                         nr_process_chains++;
1318         }
1319 }
1320
1321 #else
1322
1323 static inline int
1324 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1325                 struct held_lock *next)
1326 {
1327         return 1;
1328 }
1329
1330 static inline void inc_chains(void)
1331 {
1332         nr_process_chains++;
1333 }
1334
1335 #endif
1336
1337 static int
1338 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1339                    struct held_lock *next)
1340 {
1341         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1342                 return 0;
1343
1344         printk("\n=============================================\n");
1345         printk(  "[ INFO: possible recursive locking detected ]\n");
1346         print_kernel_version();
1347         printk(  "---------------------------------------------\n");
1348         printk("%s/%d is trying to acquire lock:\n",
1349                 curr->comm, task_pid_nr(curr));
1350         print_lock(next);
1351         printk("\nbut task is already holding lock:\n");
1352         print_lock(prev);
1353
1354         printk("\nother info that might help us debug this:\n");
1355         lockdep_print_held_locks(curr);
1356
1357         printk("\nstack backtrace:\n");
1358         dump_stack();
1359
1360         return 0;
1361 }
1362
1363 /*
1364  * Check whether we are holding such a class already.
1365  *
1366  * (Note that this has to be done separately, because the graph cannot
1367  * detect such classes of deadlocks.)
1368  *
1369  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1370  */
1371 static int
1372 check_deadlock(struct task_struct *curr, struct held_lock *next,
1373                struct lockdep_map *next_instance, int read)
1374 {
1375         struct held_lock *prev;
1376         struct held_lock *nest = NULL;
1377         int i;
1378
1379         for (i = 0; i < curr->lockdep_depth; i++) {
1380                 prev = curr->held_locks + i;
1381
1382                 if (prev->instance == next->nest_lock)
1383                         nest = prev;
1384
1385                 if (hlock_class(prev) != hlock_class(next))
1386                         continue;
1387
1388                 /*
1389                  * Allow read-after-read recursion of the same
1390                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1391                  */
1392                 if ((read == 2) && prev->read)
1393                         return 2;
1394
1395                 /*
1396                  * We're holding the nest_lock, which serializes this lock's
1397                  * nesting behaviour.
1398                  */
1399                 if (nest)
1400                         return 2;
1401
1402                 return print_deadlock_bug(curr, prev, next);
1403         }
1404         return 1;
1405 }
1406
1407 /*
1408  * There was a chain-cache miss, and we are about to add a new dependency
1409  * to a previous lock. We recursively validate the following rules:
1410  *
1411  *  - would the adding of the <prev> -> <next> dependency create a
1412  *    circular dependency in the graph? [== circular deadlock]
1413  *
1414  *  - does the new prev->next dependency connect any hardirq-safe lock
1415  *    (in the full backwards-subgraph starting at <prev>) with any
1416  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1417  *    <next>)? [== illegal lock inversion with hardirq contexts]
1418  *
1419  *  - does the new prev->next dependency connect any softirq-safe lock
1420  *    (in the full backwards-subgraph starting at <prev>) with any
1421  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1422  *    <next>)? [== illegal lock inversion with softirq contexts]
1423  *
1424  * any of these scenarios could lead to a deadlock.
1425  *
1426  * Then if all the validations pass, we add the forwards and backwards
1427  * dependency.
1428  */
1429 static int
1430 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1431                struct held_lock *next, int distance)
1432 {
1433         struct lock_list *entry;
1434         int ret;
1435
1436         /*
1437          * Prove that the new <prev> -> <next> dependency would not
1438          * create a circular dependency in the graph. (We do this by
1439          * forward-recursing into the graph starting at <next>, and
1440          * checking whether we can reach <prev>.)
1441          *
1442          * We are using global variables to control the recursion, to
1443          * keep the stackframe size of the recursive functions low:
1444          */
1445         check_source = next;
1446         check_target = prev;
1447         if (!(check_noncircular(hlock_class(next), 0)))
1448                 return print_circular_bug_tail();
1449
1450         if (!check_prev_add_irq(curr, prev, next))
1451                 return 0;
1452
1453         /*
1454          * For recursive read-locks we do all the dependency checks,
1455          * but we dont store read-triggered dependencies (only
1456          * write-triggered dependencies). This ensures that only the
1457          * write-side dependencies matter, and that if for example a
1458          * write-lock never takes any other locks, then the reads are
1459          * equivalent to a NOP.
1460          */
1461         if (next->read == 2 || prev->read == 2)
1462                 return 1;
1463         /*
1464          * Is the <prev> -> <next> dependency already present?
1465          *
1466          * (this may occur even though this is a new chain: consider
1467          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1468          *  chains - the second one will be new, but L1 already has
1469          *  L2 added to its dependency list, due to the first chain.)
1470          */
1471         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1472                 if (entry->class == hlock_class(next)) {
1473                         if (distance == 1)
1474                                 entry->distance = 1;
1475                         return 2;
1476                 }
1477         }
1478
1479         /*
1480          * Ok, all validations passed, add the new lock
1481          * to the previous lock's dependency list:
1482          */
1483         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1484                                &hlock_class(prev)->locks_after,
1485                                next->acquire_ip, distance);
1486
1487         if (!ret)
1488                 return 0;
1489
1490         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1491                                &hlock_class(next)->locks_before,
1492                                next->acquire_ip, distance);
1493         if (!ret)
1494                 return 0;
1495
1496         /*
1497          * Debugging printouts:
1498          */
1499         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1500                 graph_unlock();
1501                 printk("\n new dependency: ");
1502                 print_lock_name(hlock_class(prev));
1503                 printk(" => ");
1504                 print_lock_name(hlock_class(next));
1505                 printk("\n");
1506                 dump_stack();
1507                 return graph_lock();
1508         }
1509         return 1;
1510 }
1511
1512 /*
1513  * Add the dependency to all directly-previous locks that are 'relevant'.
1514  * The ones that are relevant are (in increasing distance from curr):
1515  * all consecutive trylock entries and the final non-trylock entry - or
1516  * the end of this context's lock-chain - whichever comes first.
1517  */
1518 static int
1519 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1520 {
1521         int depth = curr->lockdep_depth;
1522         struct held_lock *hlock;
1523
1524         /*
1525          * Debugging checks.
1526          *
1527          * Depth must not be zero for a non-head lock:
1528          */
1529         if (!depth)
1530                 goto out_bug;
1531         /*
1532          * At least two relevant locks must exist for this
1533          * to be a head:
1534          */
1535         if (curr->held_locks[depth].irq_context !=
1536                         curr->held_locks[depth-1].irq_context)
1537                 goto out_bug;
1538
1539         for (;;) {
1540                 int distance = curr->lockdep_depth - depth + 1;
1541                 hlock = curr->held_locks + depth-1;
1542                 /*
1543                  * Only non-recursive-read entries get new dependencies
1544                  * added:
1545                  */
1546                 if (hlock->read != 2) {
1547                         if (!check_prev_add(curr, hlock, next, distance))
1548                                 return 0;
1549                         /*
1550                          * Stop after the first non-trylock entry,
1551                          * as non-trylock entries have added their
1552                          * own direct dependencies already, so this
1553                          * lock is connected to them indirectly:
1554                          */
1555                         if (!hlock->trylock)
1556                                 break;
1557                 }
1558                 depth--;
1559                 /*
1560                  * End of lock-stack?
1561                  */
1562                 if (!depth)
1563                         break;
1564                 /*
1565                  * Stop the search if we cross into another context:
1566                  */
1567                 if (curr->held_locks[depth].irq_context !=
1568                                 curr->held_locks[depth-1].irq_context)
1569                         break;
1570         }
1571         return 1;
1572 out_bug:
1573         if (!debug_locks_off_graph_unlock())
1574                 return 0;
1575
1576         WARN_ON(1);
1577
1578         return 0;
1579 }
1580
1581 unsigned long nr_lock_chains;
1582 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1583 int nr_chain_hlocks;
1584 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1585
1586 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1587 {
1588         return lock_classes + chain_hlocks[chain->base + i];
1589 }
1590
1591 /*
1592  * Look up a dependency chain. If the key is not present yet then
1593  * add it and return 1 - in this case the new dependency chain is
1594  * validated. If the key is already hashed, return 0.
1595  * (On return with 1 graph_lock is held.)
1596  */
1597 static inline int lookup_chain_cache(struct task_struct *curr,
1598                                      struct held_lock *hlock,
1599                                      u64 chain_key)
1600 {
1601         struct lock_class *class = hlock_class(hlock);
1602         struct list_head *hash_head = chainhashentry(chain_key);
1603         struct lock_chain *chain;
1604         struct held_lock *hlock_curr, *hlock_next;
1605         int i, j, n, cn;
1606
1607         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1608                 return 0;
1609         /*
1610          * We can walk it lock-free, because entries only get added
1611          * to the hash:
1612          */
1613         list_for_each_entry(chain, hash_head, entry) {
1614                 if (chain->chain_key == chain_key) {
1615 cache_hit:
1616                         debug_atomic_inc(&chain_lookup_hits);
1617                         if (very_verbose(class))
1618                                 printk("\nhash chain already cached, key: "
1619                                         "%016Lx tail class: [%p] %s\n",
1620                                         (unsigned long long)chain_key,
1621                                         class->key, class->name);
1622                         return 0;
1623                 }
1624         }
1625         if (very_verbose(class))
1626                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1627                         (unsigned long long)chain_key, class->key, class->name);
1628         /*
1629          * Allocate a new chain entry from the static array, and add
1630          * it to the hash:
1631          */
1632         if (!graph_lock())
1633                 return 0;
1634         /*
1635          * We have to walk the chain again locked - to avoid duplicates:
1636          */
1637         list_for_each_entry(chain, hash_head, entry) {
1638                 if (chain->chain_key == chain_key) {
1639                         graph_unlock();
1640                         goto cache_hit;
1641                 }
1642         }
1643         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1644                 if (!debug_locks_off_graph_unlock())
1645                         return 0;
1646
1647                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1648                 printk("turning off the locking correctness validator.\n");
1649                 return 0;
1650         }
1651         chain = lock_chains + nr_lock_chains++;
1652         chain->chain_key = chain_key;
1653         chain->irq_context = hlock->irq_context;
1654         /* Find the first held_lock of current chain */
1655         hlock_next = hlock;
1656         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1657                 hlock_curr = curr->held_locks + i;
1658                 if (hlock_curr->irq_context != hlock_next->irq_context)
1659                         break;
1660                 hlock_next = hlock;
1661         }
1662         i++;
1663         chain->depth = curr->lockdep_depth + 1 - i;
1664         cn = nr_chain_hlocks;
1665         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1666                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1667                 if (n == cn)
1668                         break;
1669                 cn = n;
1670         }
1671         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1672                 chain->base = cn;
1673                 for (j = 0; j < chain->depth - 1; j++, i++) {
1674                         int lock_id = curr->held_locks[i].class_idx - 1;
1675                         chain_hlocks[chain->base + j] = lock_id;
1676                 }
1677                 chain_hlocks[chain->base + j] = class - lock_classes;
1678         }
1679         list_add_tail_rcu(&chain->entry, hash_head);
1680         debug_atomic_inc(&chain_lookup_misses);
1681         inc_chains();
1682
1683         return 1;
1684 }
1685
1686 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1687                 struct held_lock *hlock, int chain_head, u64 chain_key)
1688 {
1689         /*
1690          * Trylock needs to maintain the stack of held locks, but it
1691          * does not add new dependencies, because trylock can be done
1692          * in any order.
1693          *
1694          * We look up the chain_key and do the O(N^2) check and update of
1695          * the dependencies only if this is a new dependency chain.
1696          * (If lookup_chain_cache() returns with 1 it acquires
1697          * graph_lock for us)
1698          */
1699         if (!hlock->trylock && (hlock->check == 2) &&
1700             lookup_chain_cache(curr, hlock, chain_key)) {
1701                 /*
1702                  * Check whether last held lock:
1703                  *
1704                  * - is irq-safe, if this lock is irq-unsafe
1705                  * - is softirq-safe, if this lock is hardirq-unsafe
1706                  *
1707                  * And check whether the new lock's dependency graph
1708                  * could lead back to the previous lock.
1709                  *
1710                  * any of these scenarios could lead to a deadlock. If
1711                  * All validations
1712                  */
1713                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1714
1715                 if (!ret)
1716                         return 0;
1717                 /*
1718                  * Mark recursive read, as we jump over it when
1719                  * building dependencies (just like we jump over
1720                  * trylock entries):
1721                  */
1722                 if (ret == 2)
1723                         hlock->read = 2;
1724                 /*
1725                  * Add dependency only if this lock is not the head
1726                  * of the chain, and if it's not a secondary read-lock:
1727                  */
1728                 if (!chain_head && ret != 2)
1729                         if (!check_prevs_add(curr, hlock))
1730                                 return 0;
1731                 graph_unlock();
1732         } else
1733                 /* after lookup_chain_cache(): */
1734                 if (unlikely(!debug_locks))
1735                         return 0;
1736
1737         return 1;
1738 }
1739 #else
1740 static inline int validate_chain(struct task_struct *curr,
1741                 struct lockdep_map *lock, struct held_lock *hlock,
1742                 int chain_head, u64 chain_key)
1743 {
1744         return 1;
1745 }
1746 #endif
1747
1748 /*
1749  * We are building curr_chain_key incrementally, so double-check
1750  * it from scratch, to make sure that it's done correctly:
1751  */
1752 static void check_chain_key(struct task_struct *curr)
1753 {
1754 #ifdef CONFIG_DEBUG_LOCKDEP
1755         struct held_lock *hlock, *prev_hlock = NULL;
1756         unsigned int i, id;
1757         u64 chain_key = 0;
1758
1759         for (i = 0; i < curr->lockdep_depth; i++) {
1760                 hlock = curr->held_locks + i;
1761                 if (chain_key != hlock->prev_chain_key) {
1762                         debug_locks_off();
1763                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1764                                 curr->lockdep_depth, i,
1765                                 (unsigned long long)chain_key,
1766                                 (unsigned long long)hlock->prev_chain_key);
1767                         return;
1768                 }
1769                 id = hlock->class_idx - 1;
1770                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1771                         return;
1772
1773                 if (prev_hlock && (prev_hlock->irq_context !=
1774                                                         hlock->irq_context))
1775                         chain_key = 0;
1776                 chain_key = iterate_chain_key(chain_key, id);
1777                 prev_hlock = hlock;
1778         }
1779         if (chain_key != curr->curr_chain_key) {
1780                 debug_locks_off();
1781                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1782                         curr->lockdep_depth, i,
1783                         (unsigned long long)chain_key,
1784                         (unsigned long long)curr->curr_chain_key);
1785         }
1786 #endif
1787 }
1788
1789 static int
1790 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1791                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1792 {
1793         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1794                 return 0;
1795
1796         printk("\n=================================\n");
1797         printk(  "[ INFO: inconsistent lock state ]\n");
1798         print_kernel_version();
1799         printk(  "---------------------------------\n");
1800
1801         printk("inconsistent {%s} -> {%s} usage.\n",
1802                 usage_str[prev_bit], usage_str[new_bit]);
1803
1804         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1805                 curr->comm, task_pid_nr(curr),
1806                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1807                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1808                 trace_hardirqs_enabled(curr),
1809                 trace_softirqs_enabled(curr));
1810         print_lock(this);
1811
1812         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1813         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
1814
1815         print_irqtrace_events(curr);
1816         printk("\nother info that might help us debug this:\n");
1817         lockdep_print_held_locks(curr);
1818
1819         printk("\nstack backtrace:\n");
1820         dump_stack();
1821
1822         return 0;
1823 }
1824
1825 /*
1826  * Print out an error if an invalid bit is set:
1827  */
1828 static inline int
1829 valid_state(struct task_struct *curr, struct held_lock *this,
1830             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1831 {
1832         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
1833                 return print_usage_bug(curr, this, bad_bit, new_bit);
1834         return 1;
1835 }
1836
1837 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1838                      enum lock_usage_bit new_bit);
1839
1840 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1841
1842 /*
1843  * print irq inversion bug:
1844  */
1845 static int
1846 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1847                         struct held_lock *this, int forwards,
1848                         const char *irqclass)
1849 {
1850         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1851                 return 0;
1852
1853         printk("\n=========================================================\n");
1854         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
1855         print_kernel_version();
1856         printk(  "---------------------------------------------------------\n");
1857         printk("%s/%d just changed the state of lock:\n",
1858                 curr->comm, task_pid_nr(curr));
1859         print_lock(this);
1860         if (forwards)
1861                 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1862         else
1863                 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1864         print_lock_name(other);
1865         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1866
1867         printk("\nother info that might help us debug this:\n");
1868         lockdep_print_held_locks(curr);
1869
1870         printk("\nthe first lock's dependencies:\n");
1871         print_lock_dependencies(hlock_class(this), 0);
1872
1873         printk("\nthe second lock's dependencies:\n");
1874         print_lock_dependencies(other, 0);
1875
1876         printk("\nstack backtrace:\n");
1877         dump_stack();
1878
1879         return 0;
1880 }
1881
1882 /*
1883  * Prove that in the forwards-direction subgraph starting at <this>
1884  * there is no lock matching <mask>:
1885  */
1886 static int
1887 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1888                      enum lock_usage_bit bit, const char *irqclass)
1889 {
1890         int ret;
1891
1892         find_usage_bit = bit;
1893         /* fills in <forwards_match> */
1894         ret = find_usage_forwards(hlock_class(this), 0);
1895         if (!ret || ret == 1)
1896                 return ret;
1897
1898         return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1899 }
1900
1901 /*
1902  * Prove that in the backwards-direction subgraph starting at <this>
1903  * there is no lock matching <mask>:
1904  */
1905 static int
1906 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1907                       enum lock_usage_bit bit, const char *irqclass)
1908 {
1909         int ret;
1910
1911         find_usage_bit = bit;
1912         /* fills in <backwards_match> */
1913         ret = find_usage_backwards(hlock_class(this), 0);
1914         if (!ret || ret == 1)
1915                 return ret;
1916
1917         return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1918 }
1919
1920 void print_irqtrace_events(struct task_struct *curr)
1921 {
1922         printk("irq event stamp: %u\n", curr->irq_events);
1923         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
1924         print_ip_sym(curr->hardirq_enable_ip);
1925         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1926         print_ip_sym(curr->hardirq_disable_ip);
1927         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
1928         print_ip_sym(curr->softirq_enable_ip);
1929         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1930         print_ip_sym(curr->softirq_disable_ip);
1931 }
1932
1933 static int hardirq_verbose(struct lock_class *class)
1934 {
1935 #if HARDIRQ_VERBOSE
1936         return class_filter(class);
1937 #endif
1938         return 0;
1939 }
1940
1941 static int softirq_verbose(struct lock_class *class)
1942 {
1943 #if SOFTIRQ_VERBOSE
1944         return class_filter(class);
1945 #endif
1946         return 0;
1947 }
1948
1949 #define STRICT_READ_CHECKS      1
1950
1951 static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
1952                 enum lock_usage_bit new_bit)
1953 {
1954         int ret = 1;
1955
1956         switch(new_bit) {
1957         case LOCK_USED_IN_HARDIRQ:
1958                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1959                         return 0;
1960                 if (!valid_state(curr, this, new_bit,
1961                                  LOCK_ENABLED_HARDIRQS_READ))
1962                         return 0;
1963                 /*
1964                  * just marked it hardirq-safe, check that this lock
1965                  * took no hardirq-unsafe lock in the past:
1966                  */
1967                 if (!check_usage_forwards(curr, this,
1968                                           LOCK_ENABLED_HARDIRQS, "hard"))
1969                         return 0;
1970 #if STRICT_READ_CHECKS
1971                 /*
1972                  * just marked it hardirq-safe, check that this lock
1973                  * took no hardirq-unsafe-read lock in the past:
1974                  */
1975                 if (!check_usage_forwards(curr, this,
1976                                 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1977                         return 0;
1978 #endif
1979                 if (hardirq_verbose(hlock_class(this)))
1980                         ret = 2;
1981                 break;
1982         case LOCK_USED_IN_SOFTIRQ:
1983                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1984                         return 0;
1985                 if (!valid_state(curr, this, new_bit,
1986                                  LOCK_ENABLED_SOFTIRQS_READ))
1987                         return 0;
1988                 /*
1989                  * just marked it softirq-safe, check that this lock
1990                  * took no softirq-unsafe lock in the past:
1991                  */
1992                 if (!check_usage_forwards(curr, this,
1993                                           LOCK_ENABLED_SOFTIRQS, "soft"))
1994                         return 0;
1995 #if STRICT_READ_CHECKS
1996                 /*
1997                  * just marked it softirq-safe, check that this lock
1998                  * took no softirq-unsafe-read lock in the past:
1999                  */
2000                 if (!check_usage_forwards(curr, this,
2001                                 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
2002                         return 0;
2003 #endif
2004                 if (softirq_verbose(hlock_class(this)))
2005                         ret = 2;
2006                 break;
2007         case LOCK_USED_IN_HARDIRQ_READ:
2008                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
2009                         return 0;
2010                 /*
2011                  * just marked it hardirq-read-safe, check that this lock
2012                  * took no hardirq-unsafe lock in the past:
2013                  */
2014                 if (!check_usage_forwards(curr, this,
2015                                           LOCK_ENABLED_HARDIRQS, "hard"))
2016                         return 0;
2017                 if (hardirq_verbose(hlock_class(this)))
2018                         ret = 2;
2019                 break;
2020         case LOCK_USED_IN_SOFTIRQ_READ:
2021                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
2022                         return 0;
2023                 /*
2024                  * just marked it softirq-read-safe, check that this lock
2025                  * took no softirq-unsafe lock in the past:
2026                  */
2027                 if (!check_usage_forwards(curr, this,
2028                                           LOCK_ENABLED_SOFTIRQS, "soft"))
2029                         return 0;
2030                 if (softirq_verbose(hlock_class(this)))
2031                         ret = 2;
2032                 break;
2033         case LOCK_ENABLED_HARDIRQS:
2034                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
2035                         return 0;
2036                 if (!valid_state(curr, this, new_bit,
2037                                  LOCK_USED_IN_HARDIRQ_READ))
2038                         return 0;
2039                 /*
2040                  * just marked it hardirq-unsafe, check that no hardirq-safe
2041                  * lock in the system ever took it in the past:
2042                  */
2043                 if (!check_usage_backwards(curr, this,
2044                                            LOCK_USED_IN_HARDIRQ, "hard"))
2045                         return 0;
2046 #if STRICT_READ_CHECKS
2047                 /*
2048                  * just marked it hardirq-unsafe, check that no
2049                  * hardirq-safe-read lock in the system ever took
2050                  * it in the past:
2051                  */
2052                 if (!check_usage_backwards(curr, this,
2053                                    LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
2054                         return 0;
2055 #endif
2056                 if (hardirq_verbose(hlock_class(this)))
2057                         ret = 2;
2058                 break;
2059         case LOCK_ENABLED_SOFTIRQS:
2060                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
2061                         return 0;
2062                 if (!valid_state(curr, this, new_bit,
2063                                  LOCK_USED_IN_SOFTIRQ_READ))
2064                         return 0;
2065                 /*
2066                  * just marked it softirq-unsafe, check that no softirq-safe
2067                  * lock in the system ever took it in the past:
2068                  */
2069                 if (!check_usage_backwards(curr, this,
2070                                            LOCK_USED_IN_SOFTIRQ, "soft"))
2071                         return 0;
2072 #if STRICT_READ_CHECKS
2073                 /*
2074                  * just marked it softirq-unsafe, check that no
2075                  * softirq-safe-read lock in the system ever took
2076                  * it in the past:
2077                  */
2078                 if (!check_usage_backwards(curr, this,
2079                                    LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
2080                         return 0;
2081 #endif
2082                 if (softirq_verbose(hlock_class(this)))
2083                         ret = 2;
2084                 break;
2085         case LOCK_ENABLED_HARDIRQS_READ:
2086                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
2087                         return 0;
2088 #if STRICT_READ_CHECKS
2089                 /*
2090                  * just marked it hardirq-read-unsafe, check that no
2091                  * hardirq-safe lock in the system ever took it in the past:
2092                  */
2093                 if (!check_usage_backwards(curr, this,
2094                                            LOCK_USED_IN_HARDIRQ, "hard"))
2095                         return 0;
2096 #endif
2097                 if (hardirq_verbose(hlock_class(this)))
2098                         ret = 2;
2099                 break;
2100         case LOCK_ENABLED_SOFTIRQS_READ:
2101                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
2102                         return 0;
2103 #if STRICT_READ_CHECKS
2104                 /*
2105                  * just marked it softirq-read-unsafe, check that no
2106                  * softirq-safe lock in the system ever took it in the past:
2107                  */
2108                 if (!check_usage_backwards(curr, this,
2109                                            LOCK_USED_IN_SOFTIRQ, "soft"))
2110                         return 0;
2111 #endif
2112                 if (softirq_verbose(hlock_class(this)))
2113                         ret = 2;
2114                 break;
2115         default:
2116                 WARN_ON(1);
2117                 break;
2118         }
2119
2120         return ret;
2121 }
2122
2123 /*
2124  * Mark all held locks with a usage bit:
2125  */
2126 static int
2127 mark_held_locks(struct task_struct *curr, int hardirq)
2128 {
2129         enum lock_usage_bit usage_bit;
2130         struct held_lock *hlock;
2131         int i;
2132
2133         for (i = 0; i < curr->lockdep_depth; i++) {
2134                 hlock = curr->held_locks + i;
2135
2136                 if (hardirq) {
2137                         if (hlock->read)
2138                                 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
2139                         else
2140                                 usage_bit = LOCK_ENABLED_HARDIRQS;
2141                 } else {
2142                         if (hlock->read)
2143                                 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
2144                         else
2145                                 usage_bit = LOCK_ENABLED_SOFTIRQS;
2146                 }
2147                 if (!mark_lock(curr, hlock, usage_bit))
2148                         return 0;
2149         }
2150
2151         return 1;
2152 }
2153
2154 /*
2155  * Debugging helper: via this flag we know that we are in
2156  * 'early bootup code', and will warn about any invalid irqs-on event:
2157  */
2158 static int early_boot_irqs_enabled;
2159
2160 void early_boot_irqs_off(void)
2161 {
2162         early_boot_irqs_enabled = 0;
2163 }
2164
2165 void early_boot_irqs_on(void)
2166 {
2167         early_boot_irqs_enabled = 1;
2168 }
2169
2170 /*
2171  * Hardirqs will be enabled:
2172  */
2173 void trace_hardirqs_on_caller(unsigned long ip)
2174 {
2175         struct task_struct *curr = current;
2176
2177         time_hardirqs_on(CALLER_ADDR0, ip);
2178
2179         if (unlikely(!debug_locks || current->lockdep_recursion))
2180                 return;
2181
2182         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2183                 return;
2184
2185         if (unlikely(curr->hardirqs_enabled)) {
2186                 debug_atomic_inc(&redundant_hardirqs_on);
2187                 return;
2188         }
2189         /* we'll do an OFF -> ON transition: */
2190         curr->hardirqs_enabled = 1;
2191
2192         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2193                 return;
2194         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2195                 return;
2196         /*
2197          * We are going to turn hardirqs on, so set the
2198          * usage bit for all held locks:
2199          */
2200         if (!mark_held_locks(curr, 1))
2201                 return;
2202         /*
2203          * If we have softirqs enabled, then set the usage
2204          * bit for all held locks. (disabled hardirqs prevented
2205          * this bit from being set before)
2206          */
2207         if (curr->softirqs_enabled)
2208                 if (!mark_held_locks(curr, 0))
2209                         return;
2210
2211         curr->hardirq_enable_ip = ip;
2212         curr->hardirq_enable_event = ++curr->irq_events;
2213         debug_atomic_inc(&hardirqs_on_events);
2214 }
2215 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2216
2217 void trace_hardirqs_on(void)
2218 {
2219         trace_hardirqs_on_caller(CALLER_ADDR0);
2220 }
2221 EXPORT_SYMBOL(trace_hardirqs_on);
2222
2223 /*
2224  * Hardirqs were disabled:
2225  */
2226 void trace_hardirqs_off_caller(unsigned long ip)
2227 {
2228         struct task_struct *curr = current;
2229
2230         time_hardirqs_off(CALLER_ADDR0, ip);
2231
2232         if (unlikely(!debug_locks || current->lockdep_recursion))
2233                 return;
2234
2235         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2236                 return;
2237
2238         if (curr->hardirqs_enabled) {
2239                 /*
2240                  * We have done an ON -> OFF transition:
2241                  */
2242                 curr->hardirqs_enabled = 0;
2243                 curr->hardirq_disable_ip = ip;
2244                 curr->hardirq_disable_event = ++curr->irq_events;
2245                 debug_atomic_inc(&hardirqs_off_events);
2246         } else
2247                 debug_atomic_inc(&redundant_hardirqs_off);
2248 }
2249 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2250
2251 void trace_hardirqs_off(void)
2252 {
2253         trace_hardirqs_off_caller(CALLER_ADDR0);
2254 }
2255 EXPORT_SYMBOL(trace_hardirqs_off);
2256
2257 /*
2258  * Softirqs will be enabled:
2259  */
2260 void trace_softirqs_on(unsigned long ip)
2261 {
2262         struct task_struct *curr = current;
2263
2264         if (unlikely(!debug_locks))
2265                 return;
2266
2267         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2268                 return;
2269
2270         if (curr->softirqs_enabled) {
2271                 debug_atomic_inc(&redundant_softirqs_on);
2272                 return;
2273         }
2274
2275         /*
2276          * We'll do an OFF -> ON transition:
2277          */
2278         curr->softirqs_enabled = 1;
2279         curr->softirq_enable_ip = ip;
2280         curr->softirq_enable_event = ++curr->irq_events;
2281         debug_atomic_inc(&softirqs_on_events);
2282         /*
2283          * We are going to turn softirqs on, so set the
2284          * usage bit for all held locks, if hardirqs are
2285          * enabled too:
2286          */
2287         if (curr->hardirqs_enabled)
2288                 mark_held_locks(curr, 0);
2289 }
2290
2291 /*
2292  * Softirqs were disabled:
2293  */
2294 void trace_softirqs_off(unsigned long ip)
2295 {
2296         struct task_struct *curr = current;
2297
2298         if (unlikely(!debug_locks))
2299                 return;
2300
2301         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2302                 return;
2303
2304         if (curr->softirqs_enabled) {
2305                 /*
2306                  * We have done an ON -> OFF transition:
2307                  */
2308                 curr->softirqs_enabled = 0;
2309                 curr->softirq_disable_ip = ip;
2310                 curr->softirq_disable_event = ++curr->irq_events;
2311                 debug_atomic_inc(&softirqs_off_events);
2312                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2313         } else
2314                 debug_atomic_inc(&redundant_softirqs_off);
2315 }
2316
2317 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2318 {
2319         /*
2320          * If non-trylock use in a hardirq or softirq context, then
2321          * mark the lock as used in these contexts:
2322          */
2323         if (!hlock->trylock) {
2324                 if (hlock->read) {
2325                         if (curr->hardirq_context)
2326                                 if (!mark_lock(curr, hlock,
2327                                                 LOCK_USED_IN_HARDIRQ_READ))
2328                                         return 0;
2329                         if (curr->softirq_context)
2330                                 if (!mark_lock(curr, hlock,
2331                                                 LOCK_USED_IN_SOFTIRQ_READ))
2332                                         return 0;
2333                 } else {
2334                         if (curr->hardirq_context)
2335                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2336                                         return 0;
2337                         if (curr->softirq_context)
2338                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2339                                         return 0;
2340                 }
2341         }
2342         if (!hlock->hardirqs_off) {
2343                 if (hlock->read) {
2344                         if (!mark_lock(curr, hlock,
2345                                         LOCK_ENABLED_HARDIRQS_READ))
2346                                 return 0;
2347                         if (curr->softirqs_enabled)
2348                                 if (!mark_lock(curr, hlock,
2349                                                 LOCK_ENABLED_SOFTIRQS_READ))
2350                                         return 0;
2351                 } else {
2352                         if (!mark_lock(curr, hlock,
2353                                         LOCK_ENABLED_HARDIRQS))
2354                                 return 0;
2355                         if (curr->softirqs_enabled)
2356                                 if (!mark_lock(curr, hlock,
2357                                                 LOCK_ENABLED_SOFTIRQS))
2358                                         return 0;
2359                 }
2360         }
2361
2362         return 1;
2363 }
2364
2365 static int separate_irq_context(struct task_struct *curr,
2366                 struct held_lock *hlock)
2367 {
2368         unsigned int depth = curr->lockdep_depth;
2369
2370         /*
2371          * Keep track of points where we cross into an interrupt context:
2372          */
2373         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2374                                 curr->softirq_context;
2375         if (depth) {
2376                 struct held_lock *prev_hlock;
2377
2378                 prev_hlock = curr->held_locks + depth-1;
2379                 /*
2380                  * If we cross into another context, reset the
2381                  * hash key (this also prevents the checking and the
2382                  * adding of the dependency to 'prev'):
2383                  */
2384                 if (prev_hlock->irq_context != hlock->irq_context)
2385                         return 1;
2386         }
2387         return 0;
2388 }
2389
2390 #else
2391
2392 static inline
2393 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2394                 enum lock_usage_bit new_bit)
2395 {
2396         WARN_ON(1);
2397         return 1;
2398 }
2399
2400 static inline int mark_irqflags(struct task_struct *curr,
2401                 struct held_lock *hlock)
2402 {
2403         return 1;
2404 }
2405
2406 static inline int separate_irq_context(struct task_struct *curr,
2407                 struct held_lock *hlock)
2408 {
2409         return 0;
2410 }
2411
2412 #endif
2413
2414 /*
2415  * Mark a lock with a usage bit, and validate the state transition:
2416  */
2417 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2418                              enum lock_usage_bit new_bit)
2419 {
2420         unsigned int new_mask = 1 << new_bit, ret = 1;
2421
2422         /*
2423          * If already set then do not dirty the cacheline,
2424          * nor do any checks:
2425          */
2426         if (likely(hlock_class(this)->usage_mask & new_mask))
2427                 return 1;
2428
2429         if (!graph_lock())
2430                 return 0;
2431         /*
2432          * Make sure we didnt race:
2433          */
2434         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2435                 graph_unlock();
2436                 return 1;
2437         }
2438
2439         hlock_class(this)->usage_mask |= new_mask;
2440
2441         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2442                 return 0;
2443
2444         switch (new_bit) {
2445         case LOCK_USED_IN_HARDIRQ:
2446         case LOCK_USED_IN_SOFTIRQ:
2447         case LOCK_USED_IN_HARDIRQ_READ:
2448         case LOCK_USED_IN_SOFTIRQ_READ:
2449         case LOCK_ENABLED_HARDIRQS:
2450         case LOCK_ENABLED_SOFTIRQS:
2451         case LOCK_ENABLED_HARDIRQS_READ:
2452         case LOCK_ENABLED_SOFTIRQS_READ:
2453                 ret = mark_lock_irq(curr, this, new_bit);
2454                 if (!ret)
2455                         return 0;
2456                 break;
2457         case LOCK_USED:
2458                 debug_atomic_dec(&nr_unused_locks);
2459                 break;
2460         default:
2461                 if (!debug_locks_off_graph_unlock())
2462                         return 0;
2463                 WARN_ON(1);
2464                 return 0;
2465         }
2466
2467         graph_unlock();
2468
2469         /*
2470          * We must printk outside of the graph_lock:
2471          */
2472         if (ret == 2) {
2473                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2474                 print_lock(this);
2475                 print_irqtrace_events(curr);
2476                 dump_stack();
2477         }
2478
2479         return ret;
2480 }
2481
2482 /*
2483  * Initialize a lock instance's lock-class mapping info:
2484  */
2485 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2486                       struct lock_class_key *key, int subclass)
2487 {
2488         if (unlikely(!debug_locks))
2489                 return;
2490
2491         if (DEBUG_LOCKS_WARN_ON(!key))
2492                 return;
2493         if (DEBUG_LOCKS_WARN_ON(!name))
2494                 return;
2495         /*
2496          * Sanity check, the lock-class key must be persistent:
2497          */
2498         if (!static_obj(key)) {
2499                 printk("BUG: key %p not in .data!\n", key);
2500                 DEBUG_LOCKS_WARN_ON(1);
2501                 return;
2502         }
2503         lock->name = name;
2504         lock->key = key;
2505         lock->class_cache = NULL;
2506 #ifdef CONFIG_LOCK_STAT
2507         lock->cpu = raw_smp_processor_id();
2508 #endif
2509         if (subclass)
2510                 register_lock_class(lock, subclass, 1);
2511 }
2512
2513 EXPORT_SYMBOL_GPL(lockdep_init_map);
2514
2515 /*
2516  * This gets called for every mutex_lock*()/spin_lock*() operation.
2517  * We maintain the dependency maps and validate the locking attempt:
2518  */
2519 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2520                           int trylock, int read, int check, int hardirqs_off,
2521                           struct lockdep_map *nest_lock, unsigned long ip)
2522 {
2523         struct task_struct *curr = current;
2524         struct lock_class *class = NULL;
2525         struct held_lock *hlock;
2526         unsigned int depth, id;
2527         int chain_head = 0;
2528         u64 chain_key;
2529
2530         if (!prove_locking)
2531                 check = 1;
2532
2533         if (unlikely(!debug_locks))
2534                 return 0;
2535
2536         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2537                 return 0;
2538
2539         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2540                 debug_locks_off();
2541                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2542                 printk("turning off the locking correctness validator.\n");
2543                 return 0;
2544         }
2545
2546         if (!subclass)
2547                 class = lock->class_cache;
2548         /*
2549          * Not cached yet or subclass?
2550          */
2551         if (unlikely(!class)) {
2552                 class = register_lock_class(lock, subclass, 0);
2553                 if (!class)
2554                         return 0;
2555         }
2556         debug_atomic_inc((atomic_t *)&class->ops);
2557         if (very_verbose(class)) {
2558                 printk("\nacquire class [%p] %s", class->key, class->name);
2559                 if (class->name_version > 1)
2560                         printk("#%d", class->name_version);
2561                 printk("\n");
2562                 dump_stack();
2563         }
2564
2565         /*
2566          * Add the lock to the list of currently held locks.
2567          * (we dont increase the depth just yet, up until the
2568          * dependency checks are done)
2569          */
2570         depth = curr->lockdep_depth;
2571         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2572                 return 0;
2573
2574         hlock = curr->held_locks + depth;
2575         if (DEBUG_LOCKS_WARN_ON(!class))
2576                 return 0;
2577         hlock->class_idx = class - lock_classes + 1;
2578         hlock->acquire_ip = ip;
2579         hlock->instance = lock;
2580         hlock->nest_lock = nest_lock;
2581         hlock->trylock = trylock;
2582         hlock->read = read;
2583         hlock->check = check;
2584         hlock->hardirqs_off = !!hardirqs_off;
2585 #ifdef CONFIG_LOCK_STAT
2586         hlock->waittime_stamp = 0;
2587         hlock->holdtime_stamp = sched_clock();
2588 #endif
2589
2590         if (check == 2 && !mark_irqflags(curr, hlock))
2591                 return 0;
2592
2593         /* mark it as used: */
2594         if (!mark_lock(curr, hlock, LOCK_USED))
2595                 return 0;
2596
2597         /*
2598          * Calculate the chain hash: it's the combined hash of all the
2599          * lock keys along the dependency chain. We save the hash value
2600          * at every step so that we can get the current hash easily
2601          * after unlock. The chain hash is then used to cache dependency
2602          * results.
2603          *
2604          * The 'key ID' is what is the most compact key value to drive
2605          * the hash, not class->key.
2606          */
2607         id = class - lock_classes;
2608         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2609                 return 0;
2610
2611         chain_key = curr->curr_chain_key;
2612         if (!depth) {
2613                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2614                         return 0;
2615                 chain_head = 1;
2616         }
2617
2618         hlock->prev_chain_key = chain_key;
2619         if (separate_irq_context(curr, hlock)) {
2620                 chain_key = 0;
2621                 chain_head = 1;
2622         }
2623         chain_key = iterate_chain_key(chain_key, id);
2624
2625         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2626                 return 0;
2627
2628         curr->curr_chain_key = chain_key;
2629         curr->lockdep_depth++;
2630         check_chain_key(curr);
2631 #ifdef CONFIG_DEBUG_LOCKDEP
2632         if (unlikely(!debug_locks))
2633                 return 0;
2634 #endif
2635         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2636                 debug_locks_off();
2637                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2638                 printk("turning off the locking correctness validator.\n");
2639                 return 0;
2640         }
2641
2642         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2643                 max_lockdep_depth = curr->lockdep_depth;
2644
2645         return 1;
2646 }
2647
2648 static int
2649 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2650                            unsigned long ip)
2651 {
2652         if (!debug_locks_off())
2653                 return 0;
2654         if (debug_locks_silent)
2655                 return 0;
2656
2657         printk("\n=====================================\n");
2658         printk(  "[ BUG: bad unlock balance detected! ]\n");
2659         printk(  "-------------------------------------\n");
2660         printk("%s/%d is trying to release lock (",
2661                 curr->comm, task_pid_nr(curr));
2662         print_lockdep_cache(lock);
2663         printk(") at:\n");
2664         print_ip_sym(ip);
2665         printk("but there are no more locks to release!\n");
2666         printk("\nother info that might help us debug this:\n");
2667         lockdep_print_held_locks(curr);
2668
2669         printk("\nstack backtrace:\n");
2670         dump_stack();
2671
2672         return 0;
2673 }
2674
2675 /*
2676  * Common debugging checks for both nested and non-nested unlock:
2677  */
2678 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2679                         unsigned long ip)
2680 {
2681         if (unlikely(!debug_locks))
2682                 return 0;
2683         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2684                 return 0;
2685
2686         if (curr->lockdep_depth <= 0)
2687                 return print_unlock_inbalance_bug(curr, lock, ip);
2688
2689         return 1;
2690 }
2691
2692 static int
2693 __lock_set_subclass(struct lockdep_map *lock,
2694                     unsigned int subclass, unsigned long ip)
2695 {
2696         struct task_struct *curr = current;
2697         struct held_lock *hlock, *prev_hlock;
2698         struct lock_class *class;
2699         unsigned int depth;
2700         int i;
2701
2702         depth = curr->lockdep_depth;
2703         if (DEBUG_LOCKS_WARN_ON(!depth))
2704                 return 0;
2705
2706         prev_hlock = NULL;
2707         for (i = depth-1; i >= 0; i--) {
2708                 hlock = curr->held_locks + i;
2709                 /*
2710                  * We must not cross into another context:
2711                  */
2712                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2713                         break;
2714                 if (hlock->instance == lock)
2715                         goto found_it;
2716                 prev_hlock = hlock;
2717         }
2718         return print_unlock_inbalance_bug(curr, lock, ip);
2719
2720 found_it:
2721         class = register_lock_class(lock, subclass, 0);
2722         hlock->class_idx = class - lock_classes + 1;
2723
2724         curr->lockdep_depth = i;
2725         curr->curr_chain_key = hlock->prev_chain_key;
2726
2727         for (; i < depth; i++) {
2728                 hlock = curr->held_locks + i;
2729                 if (!__lock_acquire(hlock->instance,
2730                         hlock_class(hlock)->subclass, hlock->trylock,
2731                                 hlock->read, hlock->check, hlock->hardirqs_off,
2732                                 hlock->nest_lock, hlock->acquire_ip))
2733                         return 0;
2734         }
2735
2736         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2737                 return 0;
2738         return 1;
2739 }
2740
2741 /*
2742  * Remove the lock to the list of currently held locks in a
2743  * potentially non-nested (out of order) manner. This is a
2744  * relatively rare operation, as all the unlock APIs default
2745  * to nested mode (which uses lock_release()):
2746  */
2747 static int
2748 lock_release_non_nested(struct task_struct *curr,
2749                         struct lockdep_map *lock, unsigned long ip)
2750 {
2751         struct held_lock *hlock, *prev_hlock;
2752         unsigned int depth;
2753         int i;
2754
2755         /*
2756          * Check whether the lock exists in the current stack
2757          * of held locks:
2758          */
2759         depth = curr->lockdep_depth;
2760         if (DEBUG_LOCKS_WARN_ON(!depth))
2761                 return 0;
2762
2763         prev_hlock = NULL;
2764         for (i = depth-1; i >= 0; i--) {
2765                 hlock = curr->held_locks + i;
2766                 /*
2767                  * We must not cross into another context:
2768                  */
2769                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2770                         break;
2771                 if (hlock->instance == lock)
2772                         goto found_it;
2773                 prev_hlock = hlock;
2774         }
2775         return print_unlock_inbalance_bug(curr, lock, ip);
2776
2777 found_it:
2778         lock_release_holdtime(hlock);
2779
2780         /*
2781          * We have the right lock to unlock, 'hlock' points to it.
2782          * Now we remove it from the stack, and add back the other
2783          * entries (if any), recalculating the hash along the way:
2784          */
2785         curr->lockdep_depth = i;
2786         curr->curr_chain_key = hlock->prev_chain_key;
2787
2788         for (i++; i < depth; i++) {
2789                 hlock = curr->held_locks + i;
2790                 if (!__lock_acquire(hlock->instance,
2791                         hlock_class(hlock)->subclass, hlock->trylock,
2792                                 hlock->read, hlock->check, hlock->hardirqs_off,
2793                                 hlock->nest_lock, hlock->acquire_ip))
2794                         return 0;
2795         }
2796
2797         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2798                 return 0;
2799         return 1;
2800 }
2801
2802 /*
2803  * Remove the lock to the list of currently held locks - this gets
2804  * called on mutex_unlock()/spin_unlock*() (or on a failed
2805  * mutex_lock_interruptible()). This is done for unlocks that nest
2806  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2807  */
2808 static int lock_release_nested(struct task_struct *curr,
2809                                struct lockdep_map *lock, unsigned long ip)
2810 {
2811         struct held_lock *hlock;
2812         unsigned int depth;
2813
2814         /*
2815          * Pop off the top of the lock stack:
2816          */
2817         depth = curr->lockdep_depth - 1;
2818         hlock = curr->held_locks + depth;
2819
2820         /*
2821          * Is the unlock non-nested:
2822          */
2823         if (hlock->instance != lock)
2824                 return lock_release_non_nested(curr, lock, ip);
2825         curr->lockdep_depth--;
2826
2827         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2828                 return 0;
2829
2830         curr->curr_chain_key = hlock->prev_chain_key;
2831
2832         lock_release_holdtime(hlock);
2833
2834 #ifdef CONFIG_DEBUG_LOCKDEP
2835         hlock->prev_chain_key = 0;
2836         hlock->class_idx = 0;
2837         hlock->acquire_ip = 0;
2838         hlock->irq_context = 0;
2839 #endif
2840         return 1;
2841 }
2842
2843 /*
2844  * Remove the lock to the list of currently held locks - this gets
2845  * called on mutex_unlock()/spin_unlock*() (or on a failed
2846  * mutex_lock_interruptible()). This is done for unlocks that nest
2847  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2848  */
2849 static void
2850 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2851 {
2852         struct task_struct *curr = current;
2853
2854         if (!check_unlock(curr, lock, ip))
2855                 return;
2856
2857         if (nested) {
2858                 if (!lock_release_nested(curr, lock, ip))
2859                         return;
2860         } else {
2861                 if (!lock_release_non_nested(curr, lock, ip))
2862                         return;
2863         }
2864
2865         check_chain_key(curr);
2866 }
2867
2868 /*
2869  * Check whether we follow the irq-flags state precisely:
2870  */
2871 static void check_flags(unsigned long flags)
2872 {
2873 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2874     defined(CONFIG_TRACE_IRQFLAGS)
2875         if (!debug_locks)
2876                 return;
2877
2878         if (irqs_disabled_flags(flags)) {
2879                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
2880                         printk("possible reason: unannotated irqs-off.\n");
2881                 }
2882         } else {
2883                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
2884                         printk("possible reason: unannotated irqs-on.\n");
2885                 }
2886         }
2887
2888         /*
2889          * We dont accurately track softirq state in e.g.
2890          * hardirq contexts (such as on 4KSTACKS), so only
2891          * check if not in hardirq contexts:
2892          */
2893         if (!hardirq_count()) {
2894                 if (softirq_count())
2895                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2896                 else
2897                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2898         }
2899
2900         if (!debug_locks)
2901                 print_irqtrace_events(current);
2902 #endif
2903 }
2904
2905 void
2906 lock_set_subclass(struct lockdep_map *lock,
2907                   unsigned int subclass, unsigned long ip)
2908 {
2909         unsigned long flags;
2910
2911         if (unlikely(current->lockdep_recursion))
2912                 return;
2913
2914         raw_local_irq_save(flags);
2915         current->lockdep_recursion = 1;
2916         check_flags(flags);
2917         if (__lock_set_subclass(lock, subclass, ip))
2918                 check_chain_key(current);
2919         current->lockdep_recursion = 0;
2920         raw_local_irq_restore(flags);
2921 }
2922
2923 EXPORT_SYMBOL_GPL(lock_set_subclass);
2924
2925 /*
2926  * We are not always called with irqs disabled - do that here,
2927  * and also avoid lockdep recursion:
2928  */
2929 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2930                           int trylock, int read, int check,
2931                           struct lockdep_map *nest_lock, unsigned long ip)
2932 {
2933         unsigned long flags;
2934
2935         if (unlikely(current->lockdep_recursion))
2936                 return;
2937
2938         raw_local_irq_save(flags);
2939         check_flags(flags);
2940
2941         current->lockdep_recursion = 1;
2942         __lock_acquire(lock, subclass, trylock, read, check,
2943                        irqs_disabled_flags(flags), nest_lock, ip);
2944         current->lockdep_recursion = 0;
2945         raw_local_irq_restore(flags);
2946 }
2947
2948 EXPORT_SYMBOL_GPL(lock_acquire);
2949
2950 void lock_release(struct lockdep_map *lock, int nested,
2951                           unsigned long ip)
2952 {
2953         unsigned long flags;
2954
2955         if (unlikely(current->lockdep_recursion))
2956                 return;
2957
2958         raw_local_irq_save(flags);
2959         check_flags(flags);
2960         current->lockdep_recursion = 1;
2961         __lock_release(lock, nested, ip);
2962         current->lockdep_recursion = 0;
2963         raw_local_irq_restore(flags);
2964 }
2965
2966 EXPORT_SYMBOL_GPL(lock_release);
2967
2968 #ifdef CONFIG_LOCK_STAT
2969 static int
2970 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
2971                            unsigned long ip)
2972 {
2973         if (!debug_locks_off())
2974                 return 0;
2975         if (debug_locks_silent)
2976                 return 0;
2977
2978         printk("\n=================================\n");
2979         printk(  "[ BUG: bad contention detected! ]\n");
2980         printk(  "---------------------------------\n");
2981         printk("%s/%d is trying to contend lock (",
2982                 curr->comm, task_pid_nr(curr));
2983         print_lockdep_cache(lock);
2984         printk(") at:\n");
2985         print_ip_sym(ip);
2986         printk("but there are no locks held!\n");
2987         printk("\nother info that might help us debug this:\n");
2988         lockdep_print_held_locks(curr);
2989
2990         printk("\nstack backtrace:\n");
2991         dump_stack();
2992
2993         return 0;
2994 }
2995
2996 static void
2997 __lock_contended(struct lockdep_map *lock, unsigned long ip)
2998 {
2999         struct task_struct *curr = current;
3000         struct held_lock *hlock, *prev_hlock;
3001         struct lock_class_stats *stats;
3002         unsigned int depth;
3003         int i, point;
3004
3005         depth = curr->lockdep_depth;
3006         if (DEBUG_LOCKS_WARN_ON(!depth))
3007                 return;
3008
3009         prev_hlock = NULL;
3010         for (i = depth-1; i >= 0; i--) {
3011                 hlock = curr->held_locks + i;
3012                 /*
3013                  * We must not cross into another context:
3014                  */
3015                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3016                         break;
3017                 if (hlock->instance == lock)
3018                         goto found_it;
3019                 prev_hlock = hlock;
3020         }
3021         print_lock_contention_bug(curr, lock, ip);
3022         return;
3023
3024 found_it:
3025         hlock->waittime_stamp = sched_clock();
3026
3027         point = lock_contention_point(hlock_class(hlock), ip);
3028
3029         stats = get_lock_stats(hlock_class(hlock));
3030         if (point < ARRAY_SIZE(stats->contention_point))
3031                 stats->contention_point[point]++;
3032         if (lock->cpu != smp_processor_id())
3033                 stats->bounces[bounce_contended + !!hlock->read]++;
3034         put_lock_stats(stats);
3035 }
3036
3037 static void
3038 __lock_acquired(struct lockdep_map *lock)
3039 {
3040         struct task_struct *curr = current;
3041         struct held_lock *hlock, *prev_hlock;
3042         struct lock_class_stats *stats;
3043         unsigned int depth;
3044         u64 now;
3045         s64 waittime = 0;
3046         int i, cpu;
3047
3048         depth = curr->lockdep_depth;
3049         if (DEBUG_LOCKS_WARN_ON(!depth))
3050                 return;
3051
3052         prev_hlock = NULL;
3053         for (i = depth-1; i >= 0; i--) {
3054                 hlock = curr->held_locks + i;
3055                 /*
3056                  * We must not cross into another context:
3057                  */
3058                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3059                         break;
3060                 if (hlock->instance == lock)
3061                         goto found_it;
3062                 prev_hlock = hlock;
3063         }
3064         print_lock_contention_bug(curr, lock, _RET_IP_);
3065         return;
3066
3067 found_it:
3068         cpu = smp_processor_id();
3069         if (hlock->waittime_stamp) {
3070                 now = sched_clock();
3071                 waittime = now - hlock->waittime_stamp;
3072                 hlock->holdtime_stamp = now;
3073         }
3074
3075         stats = get_lock_stats(hlock_class(hlock));
3076         if (waittime) {
3077                 if (hlock->read)
3078                         lock_time_inc(&stats->read_waittime, waittime);
3079                 else
3080                         lock_time_inc(&stats->write_waittime, waittime);
3081         }
3082         if (lock->cpu != cpu)
3083                 stats->bounces[bounce_acquired + !!hlock->read]++;
3084         put_lock_stats(stats);
3085
3086         lock->cpu = cpu;
3087 }
3088
3089 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3090 {
3091         unsigned long flags;
3092
3093         if (unlikely(!lock_stat))
3094                 return;
3095
3096         if (unlikely(current->lockdep_recursion))
3097                 return;
3098
3099         raw_local_irq_save(flags);
3100         check_flags(flags);
3101         current->lockdep_recursion = 1;
3102         __lock_contended(lock, ip);
3103         current->lockdep_recursion = 0;
3104         raw_local_irq_restore(flags);
3105 }
3106 EXPORT_SYMBOL_GPL(lock_contended);
3107
3108 void lock_acquired(struct lockdep_map *lock)
3109 {
3110         unsigned long flags;
3111
3112         if (unlikely(!lock_stat))
3113                 return;
3114
3115         if (unlikely(current->lockdep_recursion))
3116                 return;
3117
3118         raw_local_irq_save(flags);
3119         check_flags(flags);
3120         current->lockdep_recursion = 1;
3121         __lock_acquired(lock);
3122         current->lockdep_recursion = 0;
3123         raw_local_irq_restore(flags);
3124 }
3125 EXPORT_SYMBOL_GPL(lock_acquired);
3126 #endif
3127
3128 /*
3129  * Used by the testsuite, sanitize the validator state
3130  * after a simulated failure:
3131  */
3132
3133 void lockdep_reset(void)
3134 {
3135         unsigned long flags;
3136         int i;
3137
3138         raw_local_irq_save(flags);
3139         current->curr_chain_key = 0;
3140         current->lockdep_depth = 0;
3141         current->lockdep_recursion = 0;
3142         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3143         nr_hardirq_chains = 0;
3144         nr_softirq_chains = 0;
3145         nr_process_chains = 0;
3146         debug_locks = 1;
3147         for (i = 0; i < CHAINHASH_SIZE; i++)
3148                 INIT_LIST_HEAD(chainhash_table + i);
3149         raw_local_irq_restore(flags);
3150 }
3151
3152 static void zap_class(struct lock_class *class)
3153 {
3154         int i;
3155
3156         /*
3157          * Remove all dependencies this lock is
3158          * involved in:
3159          */
3160         for (i = 0; i < nr_list_entries; i++) {
3161                 if (list_entries[i].class == class)
3162                         list_del_rcu(&list_entries[i].entry);
3163         }
3164         /*
3165          * Unhash the class and remove it from the all_lock_classes list:
3166          */
3167         list_del_rcu(&class->hash_entry);
3168         list_del_rcu(&class->lock_entry);
3169
3170         class->key = NULL;
3171 }
3172
3173 static inline int within(const void *addr, void *start, unsigned long size)
3174 {
3175         return addr >= start && addr < start + size;
3176 }
3177
3178 void lockdep_free_key_range(void *start, unsigned long size)
3179 {
3180         struct lock_class *class, *next;
3181         struct list_head *head;
3182         unsigned long flags;
3183         int i;
3184         int locked;
3185
3186         raw_local_irq_save(flags);
3187         locked = graph_lock();
3188
3189         /*
3190          * Unhash all classes that were created by this module:
3191          */
3192         for (i = 0; i < CLASSHASH_SIZE; i++) {
3193                 head = classhash_table + i;
3194                 if (list_empty(head))
3195                         continue;
3196                 list_for_each_entry_safe(class, next, head, hash_entry) {
3197                         if (within(class->key, start, size))
3198                                 zap_class(class);
3199                         else if (within(class->name, start, size))
3200                                 zap_class(class);
3201                 }
3202         }
3203
3204         if (locked)
3205                 graph_unlock();
3206         raw_local_irq_restore(flags);
3207 }
3208
3209 void lockdep_reset_lock(struct lockdep_map *lock)
3210 {
3211         struct lock_class *class, *next;
3212         struct list_head *head;
3213         unsigned long flags;
3214         int i, j;
3215         int locked;
3216
3217         raw_local_irq_save(flags);
3218
3219         /*
3220          * Remove all classes this lock might have:
3221          */
3222         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3223                 /*
3224                  * If the class exists we look it up and zap it:
3225                  */
3226                 class = look_up_lock_class(lock, j);
3227                 if (class)
3228                         zap_class(class);
3229         }
3230         /*
3231          * Debug check: in the end all mapped classes should
3232          * be gone.
3233          */
3234         locked = graph_lock();
3235         for (i = 0; i < CLASSHASH_SIZE; i++) {
3236                 head = classhash_table + i;
3237                 if (list_empty(head))
3238                         continue;
3239                 list_for_each_entry_safe(class, next, head, hash_entry) {
3240                         if (unlikely(class == lock->class_cache)) {
3241                                 if (debug_locks_off_graph_unlock())
3242                                         WARN_ON(1);
3243                                 goto out_restore;
3244                         }
3245                 }
3246         }
3247         if (locked)
3248                 graph_unlock();
3249
3250 out_restore:
3251         raw_local_irq_restore(flags);
3252 }
3253
3254 void lockdep_init(void)
3255 {
3256         int i;
3257
3258         /*
3259          * Some architectures have their own start_kernel()
3260          * code which calls lockdep_init(), while we also
3261          * call lockdep_init() from the start_kernel() itself,
3262          * and we want to initialize the hashes only once:
3263          */
3264         if (lockdep_initialized)
3265                 return;
3266
3267         for (i = 0; i < CLASSHASH_SIZE; i++)
3268                 INIT_LIST_HEAD(classhash_table + i);
3269
3270         for (i = 0; i < CHAINHASH_SIZE; i++)
3271                 INIT_LIST_HEAD(chainhash_table + i);
3272
3273         lockdep_initialized = 1;
3274 }
3275
3276 void __init lockdep_info(void)
3277 {
3278         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3279
3280         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3281         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3282         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3283         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3284         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3285         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3286         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3287
3288         printk(" memory used by lock dependency info: %lu kB\n",
3289                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3290                 sizeof(struct list_head) * CLASSHASH_SIZE +
3291                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3292                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3293                 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
3294
3295         printk(" per task-struct memory footprint: %lu bytes\n",
3296                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3297
3298 #ifdef CONFIG_DEBUG_LOCKDEP
3299         if (lockdep_init_error) {
3300                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3301                 printk("Call stack leading to lockdep invocation was:\n");
3302                 print_stack_trace(&lockdep_init_trace, 0);
3303         }
3304 #endif
3305 }
3306
3307 static void
3308 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3309                      const void *mem_to, struct held_lock *hlock)
3310 {
3311         if (!debug_locks_off())
3312                 return;
3313         if (debug_locks_silent)
3314                 return;
3315
3316         printk("\n=========================\n");
3317         printk(  "[ BUG: held lock freed! ]\n");
3318         printk(  "-------------------------\n");
3319         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3320                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3321         print_lock(hlock);
3322         lockdep_print_held_locks(curr);
3323
3324         printk("\nstack backtrace:\n");
3325         dump_stack();
3326 }
3327
3328 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3329                                 const void* lock_from, unsigned long lock_len)
3330 {
3331         return lock_from + lock_len <= mem_from ||
3332                 mem_from + mem_len <= lock_from;
3333 }
3334
3335 /*
3336  * Called when kernel memory is freed (or unmapped), or if a lock
3337  * is destroyed or reinitialized - this code checks whether there is
3338  * any held lock in the memory range of <from> to <to>:
3339  */
3340 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3341 {
3342         struct task_struct *curr = current;
3343         struct held_lock *hlock;
3344         unsigned long flags;
3345         int i;
3346
3347         if (unlikely(!debug_locks))
3348                 return;
3349
3350         local_irq_save(flags);
3351         for (i = 0; i < curr->lockdep_depth; i++) {
3352                 hlock = curr->held_locks + i;
3353
3354                 if (not_in_range(mem_from, mem_len, hlock->instance,
3355                                         sizeof(*hlock->instance)))
3356                         continue;
3357
3358                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3359                 break;
3360         }
3361         local_irq_restore(flags);
3362 }
3363 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3364
3365 static void print_held_locks_bug(struct task_struct *curr)
3366 {
3367         if (!debug_locks_off())
3368                 return;
3369         if (debug_locks_silent)
3370                 return;
3371
3372         printk("\n=====================================\n");
3373         printk(  "[ BUG: lock held at task exit time! ]\n");
3374         printk(  "-------------------------------------\n");
3375         printk("%s/%d is exiting with locks still held!\n",
3376                 curr->comm, task_pid_nr(curr));
3377         lockdep_print_held_locks(curr);
3378
3379         printk("\nstack backtrace:\n");
3380         dump_stack();
3381 }
3382
3383 void debug_check_no_locks_held(struct task_struct *task)
3384 {
3385         if (unlikely(task->lockdep_depth > 0))
3386                 print_held_locks_bug(task);
3387 }
3388
3389 void debug_show_all_locks(void)
3390 {
3391         struct task_struct *g, *p;
3392         int count = 10;
3393         int unlock = 1;
3394
3395         if (unlikely(!debug_locks)) {
3396                 printk("INFO: lockdep is turned off.\n");
3397                 return;
3398         }
3399         printk("\nShowing all locks held in the system:\n");
3400
3401         /*
3402          * Here we try to get the tasklist_lock as hard as possible,
3403          * if not successful after 2 seconds we ignore it (but keep
3404          * trying). This is to enable a debug printout even if a
3405          * tasklist_lock-holding task deadlocks or crashes.
3406          */
3407 retry:
3408         if (!read_trylock(&tasklist_lock)) {
3409                 if (count == 10)
3410                         printk("hm, tasklist_lock locked, retrying... ");
3411                 if (count) {
3412                         count--;
3413                         printk(" #%d", 10-count);
3414                         mdelay(200);
3415                         goto retry;
3416                 }
3417                 printk(" ignoring it.\n");
3418                 unlock = 0;
3419         } else {
3420                 if (count != 10)
3421                         printk(KERN_CONT " locked it.\n");
3422         }
3423
3424         do_each_thread(g, p) {
3425                 /*
3426                  * It's not reliable to print a task's held locks
3427                  * if it's not sleeping (or if it's not the current
3428                  * task):
3429                  */
3430                 if (p->state == TASK_RUNNING && p != current)
3431                         continue;
3432                 if (p->lockdep_depth)
3433                         lockdep_print_held_locks(p);
3434                 if (!unlock)
3435                         if (read_trylock(&tasklist_lock))
3436                                 unlock = 1;
3437         } while_each_thread(g, p);
3438
3439         printk("\n");
3440         printk("=============================================\n\n");
3441
3442         if (unlock)
3443                 read_unlock(&tasklist_lock);
3444 }
3445
3446 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3447
3448 /*
3449  * Careful: only use this function if you are sure that
3450  * the task cannot run in parallel!
3451  */
3452 void __debug_show_held_locks(struct task_struct *task)
3453 {
3454         if (unlikely(!debug_locks)) {
3455                 printk("INFO: lockdep is turned off.\n");
3456                 return;
3457         }
3458         lockdep_print_held_locks(task);
3459 }
3460 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3461
3462 void debug_show_held_locks(struct task_struct *task)
3463 {
3464                 __debug_show_held_locks(task);
3465 }
3466
3467 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3468
3469 void lockdep_sys_exit(void)
3470 {
3471         struct task_struct *curr = current;
3472
3473         if (unlikely(curr->lockdep_depth)) {
3474                 if (!debug_locks_off())
3475                         return;
3476                 printk("\n================================================\n");
3477                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3478                 printk(  "------------------------------------------------\n");
3479                 printk("%s/%d is leaving the kernel with locks still held!\n",
3480                                 curr->comm, curr->pid);
3481                 lockdep_print_held_locks(curr);
3482         }
3483 }