Merge branch 'linus' into x86/x2apic
[linux-2.6] / 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 #include <linux/mutex.h>
29 #include <linux/sched.h>
30 #include <linux/delay.h>
31 #include <linux/module.h>
32 #include <linux/proc_fs.h>
33 #include <linux/seq_file.h>
34 #include <linux/spinlock.h>
35 #include <linux/kallsyms.h>
36 #include <linux/interrupt.h>
37 #include <linux/stacktrace.h>
38 #include <linux/debug_locks.h>
39 #include <linux/irqflags.h>
40 #include <linux/utsname.h>
41 #include <linux/hash.h>
42 #include <linux/ftrace.h>
43
44 #include <asm/sections.h>
45
46 #include "lockdep_internals.h"
47
48 #ifdef CONFIG_PROVE_LOCKING
49 int prove_locking = 1;
50 module_param(prove_locking, int, 0644);
51 #else
52 #define prove_locking 0
53 #endif
54
55 #ifdef CONFIG_LOCK_STAT
56 int lock_stat = 1;
57 module_param(lock_stat, int, 0644);
58 #else
59 #define lock_stat 0
60 #endif
61
62 /*
63  * lockdep_lock: protects the lockdep graph, the hashes and the
64  *               class/list/hash allocators.
65  *
66  * This is one of the rare exceptions where it's justified
67  * to use a raw spinlock - we really dont want the spinlock
68  * code to recurse back into the lockdep code...
69  */
70 static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
71
72 static int graph_lock(void)
73 {
74         __raw_spin_lock(&lockdep_lock);
75         /*
76          * Make sure that if another CPU detected a bug while
77          * walking the graph we dont change it (while the other
78          * CPU is busy printing out stuff with the graph lock
79          * dropped already)
80          */
81         if (!debug_locks) {
82                 __raw_spin_unlock(&lockdep_lock);
83                 return 0;
84         }
85         /* prevent any recursions within lockdep from causing deadlocks */
86         current->lockdep_recursion++;
87         return 1;
88 }
89
90 static inline int graph_unlock(void)
91 {
92         if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
93                 return DEBUG_LOCKS_WARN_ON(1);
94
95         current->lockdep_recursion--;
96         __raw_spin_unlock(&lockdep_lock);
97         return 0;
98 }
99
100 /*
101  * Turn lock debugging off and return with 0 if it was off already,
102  * and also release the graph lock:
103  */
104 static inline int debug_locks_off_graph_unlock(void)
105 {
106         int ret = debug_locks_off();
107
108         __raw_spin_unlock(&lockdep_lock);
109
110         return ret;
111 }
112
113 static int lockdep_initialized;
114
115 unsigned long nr_list_entries;
116 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
117
118 /*
119  * All data structures here are protected by the global debug_lock.
120  *
121  * Mutex key structs only get allocated, once during bootup, and never
122  * get freed - this significantly simplifies the debugging code.
123  */
124 unsigned long nr_lock_classes;
125 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
126
127 #ifdef CONFIG_LOCK_STAT
128 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
129
130 static int lock_contention_point(struct lock_class *class, unsigned long ip)
131 {
132         int i;
133
134         for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {
135                 if (class->contention_point[i] == 0) {
136                         class->contention_point[i] = ip;
137                         break;
138                 }
139                 if (class->contention_point[i] == ip)
140                         break;
141         }
142
143         return i;
144 }
145
146 static void lock_time_inc(struct lock_time *lt, s64 time)
147 {
148         if (time > lt->max)
149                 lt->max = time;
150
151         if (time < lt->min || !lt->min)
152                 lt->min = time;
153
154         lt->total += time;
155         lt->nr++;
156 }
157
158 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
159 {
160         dst->min += src->min;
161         dst->max += src->max;
162         dst->total += src->total;
163         dst->nr += src->nr;
164 }
165
166 struct lock_class_stats lock_stats(struct lock_class *class)
167 {
168         struct lock_class_stats stats;
169         int cpu, i;
170
171         memset(&stats, 0, sizeof(struct lock_class_stats));
172         for_each_possible_cpu(cpu) {
173                 struct lock_class_stats *pcs =
174                         &per_cpu(lock_stats, cpu)[class - lock_classes];
175
176                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
177                         stats.contention_point[i] += pcs->contention_point[i];
178
179                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
180                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
181
182                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
183                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
184
185                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
186                         stats.bounces[i] += pcs->bounces[i];
187         }
188
189         return stats;
190 }
191
192 void clear_lock_stats(struct lock_class *class)
193 {
194         int cpu;
195
196         for_each_possible_cpu(cpu) {
197                 struct lock_class_stats *cpu_stats =
198                         &per_cpu(lock_stats, cpu)[class - lock_classes];
199
200                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
201         }
202         memset(class->contention_point, 0, sizeof(class->contention_point));
203 }
204
205 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
206 {
207         return &get_cpu_var(lock_stats)[class - lock_classes];
208 }
209
210 static void put_lock_stats(struct lock_class_stats *stats)
211 {
212         put_cpu_var(lock_stats);
213 }
214
215 static void lock_release_holdtime(struct held_lock *hlock)
216 {
217         struct lock_class_stats *stats;
218         s64 holdtime;
219
220         if (!lock_stat)
221                 return;
222
223         holdtime = sched_clock() - hlock->holdtime_stamp;
224
225         stats = get_lock_stats(hlock->class);
226         if (hlock->read)
227                 lock_time_inc(&stats->read_holdtime, holdtime);
228         else
229                 lock_time_inc(&stats->write_holdtime, holdtime);
230         put_lock_stats(stats);
231 }
232 #else
233 static inline void lock_release_holdtime(struct held_lock *hlock)
234 {
235 }
236 #endif
237
238 /*
239  * We keep a global list of all lock classes. The list only grows,
240  * never shrinks. The list is only accessed with the lockdep
241  * spinlock lock held.
242  */
243 LIST_HEAD(all_lock_classes);
244
245 /*
246  * The lockdep classes are in a hash-table as well, for fast lookup:
247  */
248 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
249 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
250 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
251 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
252
253 static struct list_head classhash_table[CLASSHASH_SIZE];
254
255 /*
256  * We put the lock dependency chains into a hash-table as well, to cache
257  * their existence:
258  */
259 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
260 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
261 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
262 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
263
264 static struct list_head chainhash_table[CHAINHASH_SIZE];
265
266 /*
267  * The hash key of the lock dependency chains is a hash itself too:
268  * it's a hash of all locks taken up to that lock, including that lock.
269  * It's a 64-bit hash, because it's important for the keys to be
270  * unique.
271  */
272 #define iterate_chain_key(key1, key2) \
273         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
274         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
275         (key2))
276
277 void lockdep_off(void)
278 {
279         current->lockdep_recursion++;
280 }
281
282 EXPORT_SYMBOL(lockdep_off);
283
284 void lockdep_on(void)
285 {
286         current->lockdep_recursion--;
287 }
288
289 EXPORT_SYMBOL(lockdep_on);
290
291 /*
292  * Debugging switches:
293  */
294
295 #define VERBOSE                 0
296 #define VERY_VERBOSE            0
297
298 #if VERBOSE
299 # define HARDIRQ_VERBOSE        1
300 # define SOFTIRQ_VERBOSE        1
301 #else
302 # define HARDIRQ_VERBOSE        0
303 # define SOFTIRQ_VERBOSE        0
304 #endif
305
306 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
307 /*
308  * Quick filtering for interesting events:
309  */
310 static int class_filter(struct lock_class *class)
311 {
312 #if 0
313         /* Example */
314         if (class->name_version == 1 &&
315                         !strcmp(class->name, "lockname"))
316                 return 1;
317         if (class->name_version == 1 &&
318                         !strcmp(class->name, "&struct->lockfield"))
319                 return 1;
320 #endif
321         /* Filter everything else. 1 would be to allow everything else */
322         return 0;
323 }
324 #endif
325
326 static int verbose(struct lock_class *class)
327 {
328 #if VERBOSE
329         return class_filter(class);
330 #endif
331         return 0;
332 }
333
334 /*
335  * Stack-trace: tightly packed array of stack backtrace
336  * addresses. Protected by the graph_lock.
337  */
338 unsigned long nr_stack_trace_entries;
339 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
340
341 static int save_trace(struct stack_trace *trace)
342 {
343         trace->nr_entries = 0;
344         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
345         trace->entries = stack_trace + nr_stack_trace_entries;
346
347         trace->skip = 3;
348
349         save_stack_trace(trace);
350
351         trace->max_entries = trace->nr_entries;
352
353         nr_stack_trace_entries += trace->nr_entries;
354
355         if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
356                 if (!debug_locks_off_graph_unlock())
357                         return 0;
358
359                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
360                 printk("turning off the locking correctness validator.\n");
361                 dump_stack();
362
363                 return 0;
364         }
365
366         return 1;
367 }
368
369 unsigned int nr_hardirq_chains;
370 unsigned int nr_softirq_chains;
371 unsigned int nr_process_chains;
372 unsigned int max_lockdep_depth;
373 unsigned int max_recursion_depth;
374
375 #ifdef CONFIG_DEBUG_LOCKDEP
376 /*
377  * We cannot printk in early bootup code. Not even early_printk()
378  * might work. So we mark any initialization errors and printk
379  * about it later on, in lockdep_info().
380  */
381 static int lockdep_init_error;
382 static unsigned long lockdep_init_trace_data[20];
383 static struct stack_trace lockdep_init_trace = {
384         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
385         .entries = lockdep_init_trace_data,
386 };
387
388 /*
389  * Various lockdep statistics:
390  */
391 atomic_t chain_lookup_hits;
392 atomic_t chain_lookup_misses;
393 atomic_t hardirqs_on_events;
394 atomic_t hardirqs_off_events;
395 atomic_t redundant_hardirqs_on;
396 atomic_t redundant_hardirqs_off;
397 atomic_t softirqs_on_events;
398 atomic_t softirqs_off_events;
399 atomic_t redundant_softirqs_on;
400 atomic_t redundant_softirqs_off;
401 atomic_t nr_unused_locks;
402 atomic_t nr_cyclic_checks;
403 atomic_t nr_cyclic_check_recursions;
404 atomic_t nr_find_usage_forwards_checks;
405 atomic_t nr_find_usage_forwards_recursions;
406 atomic_t nr_find_usage_backwards_checks;
407 atomic_t nr_find_usage_backwards_recursions;
408 # define debug_atomic_inc(ptr)          atomic_inc(ptr)
409 # define debug_atomic_dec(ptr)          atomic_dec(ptr)
410 # define debug_atomic_read(ptr)         atomic_read(ptr)
411 #else
412 # define debug_atomic_inc(ptr)          do { } while (0)
413 # define debug_atomic_dec(ptr)          do { } while (0)
414 # define debug_atomic_read(ptr)         0
415 #endif
416
417 /*
418  * Locking printouts:
419  */
420
421 static const char *usage_str[] =
422 {
423         [LOCK_USED] =                   "initial-use ",
424         [LOCK_USED_IN_HARDIRQ] =        "in-hardirq-W",
425         [LOCK_USED_IN_SOFTIRQ] =        "in-softirq-W",
426         [LOCK_ENABLED_SOFTIRQS] =       "softirq-on-W",
427         [LOCK_ENABLED_HARDIRQS] =       "hardirq-on-W",
428         [LOCK_USED_IN_HARDIRQ_READ] =   "in-hardirq-R",
429         [LOCK_USED_IN_SOFTIRQ_READ] =   "in-softirq-R",
430         [LOCK_ENABLED_SOFTIRQS_READ] =  "softirq-on-R",
431         [LOCK_ENABLED_HARDIRQS_READ] =  "hardirq-on-R",
432 };
433
434 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
435 {
436         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
437 }
438
439 void
440 get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
441 {
442         *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
443
444         if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
445                 *c1 = '+';
446         else
447                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
448                         *c1 = '-';
449
450         if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
451                 *c2 = '+';
452         else
453                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
454                         *c2 = '-';
455
456         if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
457                 *c3 = '-';
458         if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
459                 *c3 = '+';
460                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
461                         *c3 = '?';
462         }
463
464         if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
465                 *c4 = '-';
466         if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
467                 *c4 = '+';
468                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
469                         *c4 = '?';
470         }
471 }
472
473 static void print_lock_name(struct lock_class *class)
474 {
475         char str[KSYM_NAME_LEN], c1, c2, c3, c4;
476         const char *name;
477
478         get_usage_chars(class, &c1, &c2, &c3, &c4);
479
480         name = class->name;
481         if (!name) {
482                 name = __get_key_name(class->key, str);
483                 printk(" (%s", name);
484         } else {
485                 printk(" (%s", name);
486                 if (class->name_version > 1)
487                         printk("#%d", class->name_version);
488                 if (class->subclass)
489                         printk("/%d", class->subclass);
490         }
491         printk("){%c%c%c%c}", c1, c2, c3, c4);
492 }
493
494 static void print_lockdep_cache(struct lockdep_map *lock)
495 {
496         const char *name;
497         char str[KSYM_NAME_LEN];
498
499         name = lock->name;
500         if (!name)
501                 name = __get_key_name(lock->key->subkeys, str);
502
503         printk("%s", name);
504 }
505
506 static void print_lock(struct held_lock *hlock)
507 {
508         print_lock_name(hlock->class);
509         printk(", at: ");
510         print_ip_sym(hlock->acquire_ip);
511 }
512
513 static void lockdep_print_held_locks(struct task_struct *curr)
514 {
515         int i, depth = curr->lockdep_depth;
516
517         if (!depth) {
518                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
519                 return;
520         }
521         printk("%d lock%s held by %s/%d:\n",
522                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
523
524         for (i = 0; i < depth; i++) {
525                 printk(" #%d: ", i);
526                 print_lock(curr->held_locks + i);
527         }
528 }
529
530 static void print_lock_class_header(struct lock_class *class, int depth)
531 {
532         int bit;
533
534         printk("%*s->", depth, "");
535         print_lock_name(class);
536         printk(" ops: %lu", class->ops);
537         printk(" {\n");
538
539         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
540                 if (class->usage_mask & (1 << bit)) {
541                         int len = depth;
542
543                         len += printk("%*s   %s", depth, "", usage_str[bit]);
544                         len += printk(" at:\n");
545                         print_stack_trace(class->usage_traces + bit, len);
546                 }
547         }
548         printk("%*s }\n", depth, "");
549
550         printk("%*s ... key      at: ",depth,"");
551         print_ip_sym((unsigned long)class->key);
552 }
553
554 /*
555  * printk all lock dependencies starting at <entry>:
556  */
557 static void print_lock_dependencies(struct lock_class *class, int depth)
558 {
559         struct lock_list *entry;
560
561         if (DEBUG_LOCKS_WARN_ON(depth >= 20))
562                 return;
563
564         print_lock_class_header(class, depth);
565
566         list_for_each_entry(entry, &class->locks_after, entry) {
567                 if (DEBUG_LOCKS_WARN_ON(!entry->class))
568                         return;
569
570                 print_lock_dependencies(entry->class, depth + 1);
571
572                 printk("%*s ... acquired at:\n",depth,"");
573                 print_stack_trace(&entry->trace, 2);
574                 printk("\n");
575         }
576 }
577
578 static void print_kernel_version(void)
579 {
580         printk("%s %.*s\n", init_utsname()->release,
581                 (int)strcspn(init_utsname()->version, " "),
582                 init_utsname()->version);
583 }
584
585 static int very_verbose(struct lock_class *class)
586 {
587 #if VERY_VERBOSE
588         return class_filter(class);
589 #endif
590         return 0;
591 }
592
593 /*
594  * Is this the address of a static object:
595  */
596 static int static_obj(void *obj)
597 {
598         unsigned long start = (unsigned long) &_stext,
599                       end   = (unsigned long) &_end,
600                       addr  = (unsigned long) obj;
601 #ifdef CONFIG_SMP
602         int i;
603 #endif
604
605         /*
606          * static variable?
607          */
608         if ((addr >= start) && (addr < end))
609                 return 1;
610
611 #ifdef CONFIG_SMP
612         /*
613          * percpu var?
614          */
615         for_each_possible_cpu(i) {
616                 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
617                 end   = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
618                                         + per_cpu_offset(i);
619
620                 if ((addr >= start) && (addr < end))
621                         return 1;
622         }
623 #endif
624
625         /*
626          * module var?
627          */
628         return is_module_address(addr);
629 }
630
631 /*
632  * To make lock name printouts unique, we calculate a unique
633  * class->name_version generation counter:
634  */
635 static int count_matching_names(struct lock_class *new_class)
636 {
637         struct lock_class *class;
638         int count = 0;
639
640         if (!new_class->name)
641                 return 0;
642
643         list_for_each_entry(class, &all_lock_classes, lock_entry) {
644                 if (new_class->key - new_class->subclass == class->key)
645                         return class->name_version;
646                 if (class->name && !strcmp(class->name, new_class->name))
647                         count = max(count, class->name_version);
648         }
649
650         return count + 1;
651 }
652
653 /*
654  * Register a lock's class in the hash-table, if the class is not present
655  * yet. Otherwise we look it up. We cache the result in the lock object
656  * itself, so actual lookup of the hash should be once per lock object.
657  */
658 static inline struct lock_class *
659 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
660 {
661         struct lockdep_subclass_key *key;
662         struct list_head *hash_head;
663         struct lock_class *class;
664
665 #ifdef CONFIG_DEBUG_LOCKDEP
666         /*
667          * If the architecture calls into lockdep before initializing
668          * the hashes then we'll warn about it later. (we cannot printk
669          * right now)
670          */
671         if (unlikely(!lockdep_initialized)) {
672                 lockdep_init();
673                 lockdep_init_error = 1;
674                 save_stack_trace(&lockdep_init_trace);
675         }
676 #endif
677
678         /*
679          * Static locks do not have their class-keys yet - for them the key
680          * is the lock object itself:
681          */
682         if (unlikely(!lock->key))
683                 lock->key = (void *)lock;
684
685         /*
686          * NOTE: the class-key must be unique. For dynamic locks, a static
687          * lock_class_key variable is passed in through the mutex_init()
688          * (or spin_lock_init()) call - which acts as the key. For static
689          * locks we use the lock object itself as the key.
690          */
691         BUILD_BUG_ON(sizeof(struct lock_class_key) >
692                         sizeof(struct lockdep_map));
693
694         key = lock->key->subkeys + subclass;
695
696         hash_head = classhashentry(key);
697
698         /*
699          * We can walk the hash lockfree, because the hash only
700          * grows, and we are careful when adding entries to the end:
701          */
702         list_for_each_entry(class, hash_head, hash_entry) {
703                 if (class->key == key) {
704                         WARN_ON_ONCE(class->name != lock->name);
705                         return class;
706                 }
707         }
708
709         return NULL;
710 }
711
712 /*
713  * Register a lock's class in the hash-table, if the class is not present
714  * yet. Otherwise we look it up. We cache the result in the lock object
715  * itself, so actual lookup of the hash should be once per lock object.
716  */
717 static inline struct lock_class *
718 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
719 {
720         struct lockdep_subclass_key *key;
721         struct list_head *hash_head;
722         struct lock_class *class;
723         unsigned long flags;
724
725         class = look_up_lock_class(lock, subclass);
726         if (likely(class))
727                 return class;
728
729         /*
730          * Debug-check: all keys must be persistent!
731          */
732         if (!static_obj(lock->key)) {
733                 debug_locks_off();
734                 printk("INFO: trying to register non-static key.\n");
735                 printk("the code is fine but needs lockdep annotation.\n");
736                 printk("turning off the locking correctness validator.\n");
737                 dump_stack();
738
739                 return NULL;
740         }
741
742         key = lock->key->subkeys + subclass;
743         hash_head = classhashentry(key);
744
745         raw_local_irq_save(flags);
746         if (!graph_lock()) {
747                 raw_local_irq_restore(flags);
748                 return NULL;
749         }
750         /*
751          * We have to do the hash-walk again, to avoid races
752          * with another CPU:
753          */
754         list_for_each_entry(class, hash_head, hash_entry)
755                 if (class->key == key)
756                         goto out_unlock_set;
757         /*
758          * Allocate a new key from the static array, and add it to
759          * the hash:
760          */
761         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
762                 if (!debug_locks_off_graph_unlock()) {
763                         raw_local_irq_restore(flags);
764                         return NULL;
765                 }
766                 raw_local_irq_restore(flags);
767
768                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
769                 printk("turning off the locking correctness validator.\n");
770                 return NULL;
771         }
772         class = lock_classes + nr_lock_classes++;
773         debug_atomic_inc(&nr_unused_locks);
774         class->key = key;
775         class->name = lock->name;
776         class->subclass = subclass;
777         INIT_LIST_HEAD(&class->lock_entry);
778         INIT_LIST_HEAD(&class->locks_before);
779         INIT_LIST_HEAD(&class->locks_after);
780         class->name_version = count_matching_names(class);
781         /*
782          * We use RCU's safe list-add method to make
783          * parallel walking of the hash-list safe:
784          */
785         list_add_tail_rcu(&class->hash_entry, hash_head);
786         /*
787          * Add it to the global list of classes:
788          */
789         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
790
791         if (verbose(class)) {
792                 graph_unlock();
793                 raw_local_irq_restore(flags);
794
795                 printk("\nnew class %p: %s", class->key, class->name);
796                 if (class->name_version > 1)
797                         printk("#%d", class->name_version);
798                 printk("\n");
799                 dump_stack();
800
801                 raw_local_irq_save(flags);
802                 if (!graph_lock()) {
803                         raw_local_irq_restore(flags);
804                         return NULL;
805                 }
806         }
807 out_unlock_set:
808         graph_unlock();
809         raw_local_irq_restore(flags);
810
811         if (!subclass || force)
812                 lock->class_cache = class;
813
814         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
815                 return NULL;
816
817         return class;
818 }
819
820 #ifdef CONFIG_PROVE_LOCKING
821 /*
822  * Allocate a lockdep entry. (assumes the graph_lock held, returns
823  * with NULL on failure)
824  */
825 static struct lock_list *alloc_list_entry(void)
826 {
827         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
828                 if (!debug_locks_off_graph_unlock())
829                         return NULL;
830
831                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
832                 printk("turning off the locking correctness validator.\n");
833                 return NULL;
834         }
835         return list_entries + nr_list_entries++;
836 }
837
838 /*
839  * Add a new dependency to the head of the list:
840  */
841 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
842                             struct list_head *head, unsigned long ip, int distance)
843 {
844         struct lock_list *entry;
845         /*
846          * Lock not present yet - get a new dependency struct and
847          * add it to the list:
848          */
849         entry = alloc_list_entry();
850         if (!entry)
851                 return 0;
852
853         entry->class = this;
854         entry->distance = distance;
855         if (!save_trace(&entry->trace))
856                 return 0;
857
858         /*
859          * Since we never remove from the dependency list, the list can
860          * be walked lockless by other CPUs, it's only allocation
861          * that must be protected by the spinlock. But this also means
862          * we must make new entries visible only once writes to the
863          * entry become visible - hence the RCU op:
864          */
865         list_add_tail_rcu(&entry->entry, head);
866
867         return 1;
868 }
869
870 /*
871  * Recursive, forwards-direction lock-dependency checking, used for
872  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
873  * checking.
874  *
875  * (to keep the stackframe of the recursive functions small we
876  *  use these global variables, and we also mark various helper
877  *  functions as noinline.)
878  */
879 static struct held_lock *check_source, *check_target;
880
881 /*
882  * Print a dependency chain entry (this is only done when a deadlock
883  * has been detected):
884  */
885 static noinline int
886 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
887 {
888         if (debug_locks_silent)
889                 return 0;
890         printk("\n-> #%u", depth);
891         print_lock_name(target->class);
892         printk(":\n");
893         print_stack_trace(&target->trace, 6);
894
895         return 0;
896 }
897
898 /*
899  * When a circular dependency is detected, print the
900  * header first:
901  */
902 static noinline int
903 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
904 {
905         struct task_struct *curr = current;
906
907         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
908                 return 0;
909
910         printk("\n=======================================================\n");
911         printk(  "[ INFO: possible circular locking dependency detected ]\n");
912         print_kernel_version();
913         printk(  "-------------------------------------------------------\n");
914         printk("%s/%d is trying to acquire lock:\n",
915                 curr->comm, task_pid_nr(curr));
916         print_lock(check_source);
917         printk("\nbut task is already holding lock:\n");
918         print_lock(check_target);
919         printk("\nwhich lock already depends on the new lock.\n\n");
920         printk("\nthe existing dependency chain (in reverse order) is:\n");
921
922         print_circular_bug_entry(entry, depth);
923
924         return 0;
925 }
926
927 static noinline int print_circular_bug_tail(void)
928 {
929         struct task_struct *curr = current;
930         struct lock_list this;
931
932         if (debug_locks_silent)
933                 return 0;
934
935         this.class = check_source->class;
936         if (!save_trace(&this.trace))
937                 return 0;
938
939         print_circular_bug_entry(&this, 0);
940
941         printk("\nother info that might help us debug this:\n\n");
942         lockdep_print_held_locks(curr);
943
944         printk("\nstack backtrace:\n");
945         dump_stack();
946
947         return 0;
948 }
949
950 #define RECURSION_LIMIT 40
951
952 static int noinline print_infinite_recursion_bug(void)
953 {
954         if (!debug_locks_off_graph_unlock())
955                 return 0;
956
957         WARN_ON(1);
958
959         return 0;
960 }
961
962 /*
963  * Prove that the dependency graph starting at <entry> can not
964  * lead to <target>. Print an error and return 0 if it does.
965  */
966 static noinline int
967 check_noncircular(struct lock_class *source, unsigned int depth)
968 {
969         struct lock_list *entry;
970
971         debug_atomic_inc(&nr_cyclic_check_recursions);
972         if (depth > max_recursion_depth)
973                 max_recursion_depth = depth;
974         if (depth >= RECURSION_LIMIT)
975                 return print_infinite_recursion_bug();
976         /*
977          * Check this lock's dependency list:
978          */
979         list_for_each_entry(entry, &source->locks_after, entry) {
980                 if (entry->class == check_target->class)
981                         return print_circular_bug_header(entry, depth+1);
982                 debug_atomic_inc(&nr_cyclic_checks);
983                 if (!check_noncircular(entry->class, depth+1))
984                         return print_circular_bug_entry(entry, depth+1);
985         }
986         return 1;
987 }
988
989 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
990 /*
991  * Forwards and backwards subgraph searching, for the purposes of
992  * proving that two subgraphs can be connected by a new dependency
993  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
994  */
995 static enum lock_usage_bit find_usage_bit;
996 static struct lock_class *forwards_match, *backwards_match;
997
998 /*
999  * Find a node in the forwards-direction dependency sub-graph starting
1000  * at <source> that matches <find_usage_bit>.
1001  *
1002  * Return 2 if such a node exists in the subgraph, and put that node
1003  * into <forwards_match>.
1004  *
1005  * Return 1 otherwise and keep <forwards_match> unchanged.
1006  * Return 0 on error.
1007  */
1008 static noinline int
1009 find_usage_forwards(struct lock_class *source, unsigned int depth)
1010 {
1011         struct lock_list *entry;
1012         int ret;
1013
1014         if (depth > max_recursion_depth)
1015                 max_recursion_depth = depth;
1016         if (depth >= RECURSION_LIMIT)
1017                 return print_infinite_recursion_bug();
1018
1019         debug_atomic_inc(&nr_find_usage_forwards_checks);
1020         if (source->usage_mask & (1 << find_usage_bit)) {
1021                 forwards_match = source;
1022                 return 2;
1023         }
1024
1025         /*
1026          * Check this lock's dependency list:
1027          */
1028         list_for_each_entry(entry, &source->locks_after, entry) {
1029                 debug_atomic_inc(&nr_find_usage_forwards_recursions);
1030                 ret = find_usage_forwards(entry->class, depth+1);
1031                 if (ret == 2 || ret == 0)
1032                         return ret;
1033         }
1034         return 1;
1035 }
1036
1037 /*
1038  * Find a node in the backwards-direction dependency sub-graph starting
1039  * at <source> that matches <find_usage_bit>.
1040  *
1041  * Return 2 if such a node exists in the subgraph, and put that node
1042  * into <backwards_match>.
1043  *
1044  * Return 1 otherwise and keep <backwards_match> unchanged.
1045  * Return 0 on error.
1046  */
1047 static noinline int
1048 find_usage_backwards(struct lock_class *source, unsigned int depth)
1049 {
1050         struct lock_list *entry;
1051         int ret;
1052
1053         if (!__raw_spin_is_locked(&lockdep_lock))
1054                 return DEBUG_LOCKS_WARN_ON(1);
1055
1056         if (depth > max_recursion_depth)
1057                 max_recursion_depth = depth;
1058         if (depth >= RECURSION_LIMIT)
1059                 return print_infinite_recursion_bug();
1060
1061         debug_atomic_inc(&nr_find_usage_backwards_checks);
1062         if (source->usage_mask & (1 << find_usage_bit)) {
1063                 backwards_match = source;
1064                 return 2;
1065         }
1066
1067         /*
1068          * Check this lock's dependency list:
1069          */
1070         list_for_each_entry(entry, &source->locks_before, entry) {
1071                 debug_atomic_inc(&nr_find_usage_backwards_recursions);
1072                 ret = find_usage_backwards(entry->class, depth+1);
1073                 if (ret == 2 || ret == 0)
1074                         return ret;
1075         }
1076         return 1;
1077 }
1078
1079 static int
1080 print_bad_irq_dependency(struct task_struct *curr,
1081                          struct held_lock *prev,
1082                          struct held_lock *next,
1083                          enum lock_usage_bit bit1,
1084                          enum lock_usage_bit bit2,
1085                          const char *irqclass)
1086 {
1087         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1088                 return 0;
1089
1090         printk("\n======================================================\n");
1091         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1092                 irqclass, irqclass);
1093         print_kernel_version();
1094         printk(  "------------------------------------------------------\n");
1095         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1096                 curr->comm, task_pid_nr(curr),
1097                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1098                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1099                 curr->hardirqs_enabled,
1100                 curr->softirqs_enabled);
1101         print_lock(next);
1102
1103         printk("\nand this task is already holding:\n");
1104         print_lock(prev);
1105         printk("which would create a new lock dependency:\n");
1106         print_lock_name(prev->class);
1107         printk(" ->");
1108         print_lock_name(next->class);
1109         printk("\n");
1110
1111         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1112                 irqclass);
1113         print_lock_name(backwards_match);
1114         printk("\n... which became %s-irq-safe at:\n", irqclass);
1115
1116         print_stack_trace(backwards_match->usage_traces + bit1, 1);
1117
1118         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1119         print_lock_name(forwards_match);
1120         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1121         printk("...");
1122
1123         print_stack_trace(forwards_match->usage_traces + bit2, 1);
1124
1125         printk("\nother info that might help us debug this:\n\n");
1126         lockdep_print_held_locks(curr);
1127
1128         printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1129         print_lock_dependencies(backwards_match, 0);
1130
1131         printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1132         print_lock_dependencies(forwards_match, 0);
1133
1134         printk("\nstack backtrace:\n");
1135         dump_stack();
1136
1137         return 0;
1138 }
1139
1140 static int
1141 check_usage(struct task_struct *curr, struct held_lock *prev,
1142             struct held_lock *next, enum lock_usage_bit bit_backwards,
1143             enum lock_usage_bit bit_forwards, const char *irqclass)
1144 {
1145         int ret;
1146
1147         find_usage_bit = bit_backwards;
1148         /* fills in <backwards_match> */
1149         ret = find_usage_backwards(prev->class, 0);
1150         if (!ret || ret == 1)
1151                 return ret;
1152
1153         find_usage_bit = bit_forwards;
1154         ret = find_usage_forwards(next->class, 0);
1155         if (!ret || ret == 1)
1156                 return ret;
1157         /* ret == 2 */
1158         return print_bad_irq_dependency(curr, prev, next,
1159                         bit_backwards, bit_forwards, irqclass);
1160 }
1161
1162 static int
1163 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1164                 struct held_lock *next)
1165 {
1166         /*
1167          * Prove that the new dependency does not connect a hardirq-safe
1168          * lock with a hardirq-unsafe lock - to achieve this we search
1169          * the backwards-subgraph starting at <prev>, and the
1170          * forwards-subgraph starting at <next>:
1171          */
1172         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
1173                                         LOCK_ENABLED_HARDIRQS, "hard"))
1174                 return 0;
1175
1176         /*
1177          * Prove that the new dependency does not connect a hardirq-safe-read
1178          * lock with a hardirq-unsafe lock - to achieve this we search
1179          * the backwards-subgraph starting at <prev>, and the
1180          * forwards-subgraph starting at <next>:
1181          */
1182         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
1183                                         LOCK_ENABLED_HARDIRQS, "hard-read"))
1184                 return 0;
1185
1186         /*
1187          * Prove that the new dependency does not connect a softirq-safe
1188          * lock with a softirq-unsafe lock - to achieve this we search
1189          * the backwards-subgraph starting at <prev>, and the
1190          * forwards-subgraph starting at <next>:
1191          */
1192         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
1193                                         LOCK_ENABLED_SOFTIRQS, "soft"))
1194                 return 0;
1195         /*
1196          * Prove that the new dependency does not connect a softirq-safe-read
1197          * lock with a softirq-unsafe lock - to achieve this we search
1198          * the backwards-subgraph starting at <prev>, and the
1199          * forwards-subgraph starting at <next>:
1200          */
1201         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
1202                                         LOCK_ENABLED_SOFTIRQS, "soft"))
1203                 return 0;
1204
1205         return 1;
1206 }
1207
1208 static void inc_chains(void)
1209 {
1210         if (current->hardirq_context)
1211                 nr_hardirq_chains++;
1212         else {
1213                 if (current->softirq_context)
1214                         nr_softirq_chains++;
1215                 else
1216                         nr_process_chains++;
1217         }
1218 }
1219
1220 #else
1221
1222 static inline int
1223 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1224                 struct held_lock *next)
1225 {
1226         return 1;
1227 }
1228
1229 static inline void inc_chains(void)
1230 {
1231         nr_process_chains++;
1232 }
1233
1234 #endif
1235
1236 static int
1237 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1238                    struct held_lock *next)
1239 {
1240         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1241                 return 0;
1242
1243         printk("\n=============================================\n");
1244         printk(  "[ INFO: possible recursive locking detected ]\n");
1245         print_kernel_version();
1246         printk(  "---------------------------------------------\n");
1247         printk("%s/%d is trying to acquire lock:\n",
1248                 curr->comm, task_pid_nr(curr));
1249         print_lock(next);
1250         printk("\nbut task is already holding lock:\n");
1251         print_lock(prev);
1252
1253         printk("\nother info that might help us debug this:\n");
1254         lockdep_print_held_locks(curr);
1255
1256         printk("\nstack backtrace:\n");
1257         dump_stack();
1258
1259         return 0;
1260 }
1261
1262 /*
1263  * Check whether we are holding such a class already.
1264  *
1265  * (Note that this has to be done separately, because the graph cannot
1266  * detect such classes of deadlocks.)
1267  *
1268  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1269  */
1270 static int
1271 check_deadlock(struct task_struct *curr, struct held_lock *next,
1272                struct lockdep_map *next_instance, int read)
1273 {
1274         struct held_lock *prev;
1275         int i;
1276
1277         for (i = 0; i < curr->lockdep_depth; i++) {
1278                 prev = curr->held_locks + i;
1279                 if (prev->class != next->class)
1280                         continue;
1281                 /*
1282                  * Allow read-after-read recursion of the same
1283                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1284                  */
1285                 if ((read == 2) && prev->read)
1286                         return 2;
1287                 return print_deadlock_bug(curr, prev, next);
1288         }
1289         return 1;
1290 }
1291
1292 /*
1293  * There was a chain-cache miss, and we are about to add a new dependency
1294  * to a previous lock. We recursively validate the following rules:
1295  *
1296  *  - would the adding of the <prev> -> <next> dependency create a
1297  *    circular dependency in the graph? [== circular deadlock]
1298  *
1299  *  - does the new prev->next dependency connect any hardirq-safe lock
1300  *    (in the full backwards-subgraph starting at <prev>) with any
1301  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1302  *    <next>)? [== illegal lock inversion with hardirq contexts]
1303  *
1304  *  - does the new prev->next dependency connect any softirq-safe lock
1305  *    (in the full backwards-subgraph starting at <prev>) with any
1306  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1307  *    <next>)? [== illegal lock inversion with softirq contexts]
1308  *
1309  * any of these scenarios could lead to a deadlock.
1310  *
1311  * Then if all the validations pass, we add the forwards and backwards
1312  * dependency.
1313  */
1314 static int
1315 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1316                struct held_lock *next, int distance)
1317 {
1318         struct lock_list *entry;
1319         int ret;
1320
1321         /*
1322          * Prove that the new <prev> -> <next> dependency would not
1323          * create a circular dependency in the graph. (We do this by
1324          * forward-recursing into the graph starting at <next>, and
1325          * checking whether we can reach <prev>.)
1326          *
1327          * We are using global variables to control the recursion, to
1328          * keep the stackframe size of the recursive functions low:
1329          */
1330         check_source = next;
1331         check_target = prev;
1332         if (!(check_noncircular(next->class, 0)))
1333                 return print_circular_bug_tail();
1334
1335         if (!check_prev_add_irq(curr, prev, next))
1336                 return 0;
1337
1338         /*
1339          * For recursive read-locks we do all the dependency checks,
1340          * but we dont store read-triggered dependencies (only
1341          * write-triggered dependencies). This ensures that only the
1342          * write-side dependencies matter, and that if for example a
1343          * write-lock never takes any other locks, then the reads are
1344          * equivalent to a NOP.
1345          */
1346         if (next->read == 2 || prev->read == 2)
1347                 return 1;
1348         /*
1349          * Is the <prev> -> <next> dependency already present?
1350          *
1351          * (this may occur even though this is a new chain: consider
1352          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1353          *  chains - the second one will be new, but L1 already has
1354          *  L2 added to its dependency list, due to the first chain.)
1355          */
1356         list_for_each_entry(entry, &prev->class->locks_after, entry) {
1357                 if (entry->class == next->class) {
1358                         if (distance == 1)
1359                                 entry->distance = 1;
1360                         return 2;
1361                 }
1362         }
1363
1364         /*
1365          * Ok, all validations passed, add the new lock
1366          * to the previous lock's dependency list:
1367          */
1368         ret = add_lock_to_list(prev->class, next->class,
1369                                &prev->class->locks_after, next->acquire_ip, distance);
1370
1371         if (!ret)
1372                 return 0;
1373
1374         ret = add_lock_to_list(next->class, prev->class,
1375                                &next->class->locks_before, next->acquire_ip, distance);
1376         if (!ret)
1377                 return 0;
1378
1379         /*
1380          * Debugging printouts:
1381          */
1382         if (verbose(prev->class) || verbose(next->class)) {
1383                 graph_unlock();
1384                 printk("\n new dependency: ");
1385                 print_lock_name(prev->class);
1386                 printk(" => ");
1387                 print_lock_name(next->class);
1388                 printk("\n");
1389                 dump_stack();
1390                 return graph_lock();
1391         }
1392         return 1;
1393 }
1394
1395 /*
1396  * Add the dependency to all directly-previous locks that are 'relevant'.
1397  * The ones that are relevant are (in increasing distance from curr):
1398  * all consecutive trylock entries and the final non-trylock entry - or
1399  * the end of this context's lock-chain - whichever comes first.
1400  */
1401 static int
1402 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1403 {
1404         int depth = curr->lockdep_depth;
1405         struct held_lock *hlock;
1406
1407         /*
1408          * Debugging checks.
1409          *
1410          * Depth must not be zero for a non-head lock:
1411          */
1412         if (!depth)
1413                 goto out_bug;
1414         /*
1415          * At least two relevant locks must exist for this
1416          * to be a head:
1417          */
1418         if (curr->held_locks[depth].irq_context !=
1419                         curr->held_locks[depth-1].irq_context)
1420                 goto out_bug;
1421
1422         for (;;) {
1423                 int distance = curr->lockdep_depth - depth + 1;
1424                 hlock = curr->held_locks + depth-1;
1425                 /*
1426                  * Only non-recursive-read entries get new dependencies
1427                  * added:
1428                  */
1429                 if (hlock->read != 2) {
1430                         if (!check_prev_add(curr, hlock, next, distance))
1431                                 return 0;
1432                         /*
1433                          * Stop after the first non-trylock entry,
1434                          * as non-trylock entries have added their
1435                          * own direct dependencies already, so this
1436                          * lock is connected to them indirectly:
1437                          */
1438                         if (!hlock->trylock)
1439                                 break;
1440                 }
1441                 depth--;
1442                 /*
1443                  * End of lock-stack?
1444                  */
1445                 if (!depth)
1446                         break;
1447                 /*
1448                  * Stop the search if we cross into another context:
1449                  */
1450                 if (curr->held_locks[depth].irq_context !=
1451                                 curr->held_locks[depth-1].irq_context)
1452                         break;
1453         }
1454         return 1;
1455 out_bug:
1456         if (!debug_locks_off_graph_unlock())
1457                 return 0;
1458
1459         WARN_ON(1);
1460
1461         return 0;
1462 }
1463
1464 unsigned long nr_lock_chains;
1465 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1466 int nr_chain_hlocks;
1467 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1468
1469 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1470 {
1471         return lock_classes + chain_hlocks[chain->base + i];
1472 }
1473
1474 /*
1475  * Look up a dependency chain. If the key is not present yet then
1476  * add it and return 1 - in this case the new dependency chain is
1477  * validated. If the key is already hashed, return 0.
1478  * (On return with 1 graph_lock is held.)
1479  */
1480 static inline int lookup_chain_cache(struct task_struct *curr,
1481                                      struct held_lock *hlock,
1482                                      u64 chain_key)
1483 {
1484         struct lock_class *class = hlock->class;
1485         struct list_head *hash_head = chainhashentry(chain_key);
1486         struct lock_chain *chain;
1487         struct held_lock *hlock_curr, *hlock_next;
1488         int i, j, n, cn;
1489
1490         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1491                 return 0;
1492         /*
1493          * We can walk it lock-free, because entries only get added
1494          * to the hash:
1495          */
1496         list_for_each_entry(chain, hash_head, entry) {
1497                 if (chain->chain_key == chain_key) {
1498 cache_hit:
1499                         debug_atomic_inc(&chain_lookup_hits);
1500                         if (very_verbose(class))
1501                                 printk("\nhash chain already cached, key: "
1502                                         "%016Lx tail class: [%p] %s\n",
1503                                         (unsigned long long)chain_key,
1504                                         class->key, class->name);
1505                         return 0;
1506                 }
1507         }
1508         if (very_verbose(class))
1509                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1510                         (unsigned long long)chain_key, class->key, class->name);
1511         /*
1512          * Allocate a new chain entry from the static array, and add
1513          * it to the hash:
1514          */
1515         if (!graph_lock())
1516                 return 0;
1517         /*
1518          * We have to walk the chain again locked - to avoid duplicates:
1519          */
1520         list_for_each_entry(chain, hash_head, entry) {
1521                 if (chain->chain_key == chain_key) {
1522                         graph_unlock();
1523                         goto cache_hit;
1524                 }
1525         }
1526         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1527                 if (!debug_locks_off_graph_unlock())
1528                         return 0;
1529
1530                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1531                 printk("turning off the locking correctness validator.\n");
1532                 return 0;
1533         }
1534         chain = lock_chains + nr_lock_chains++;
1535         chain->chain_key = chain_key;
1536         chain->irq_context = hlock->irq_context;
1537         /* Find the first held_lock of current chain */
1538         hlock_next = hlock;
1539         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1540                 hlock_curr = curr->held_locks + i;
1541                 if (hlock_curr->irq_context != hlock_next->irq_context)
1542                         break;
1543                 hlock_next = hlock;
1544         }
1545         i++;
1546         chain->depth = curr->lockdep_depth + 1 - i;
1547         cn = nr_chain_hlocks;
1548         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1549                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1550                 if (n == cn)
1551                         break;
1552                 cn = n;
1553         }
1554         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1555                 chain->base = cn;
1556                 for (j = 0; j < chain->depth - 1; j++, i++) {
1557                         int lock_id = curr->held_locks[i].class - lock_classes;
1558                         chain_hlocks[chain->base + j] = lock_id;
1559                 }
1560                 chain_hlocks[chain->base + j] = class - lock_classes;
1561         }
1562         list_add_tail_rcu(&chain->entry, hash_head);
1563         debug_atomic_inc(&chain_lookup_misses);
1564         inc_chains();
1565
1566         return 1;
1567 }
1568
1569 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1570                 struct held_lock *hlock, int chain_head, u64 chain_key)
1571 {
1572         /*
1573          * Trylock needs to maintain the stack of held locks, but it
1574          * does not add new dependencies, because trylock can be done
1575          * in any order.
1576          *
1577          * We look up the chain_key and do the O(N^2) check and update of
1578          * the dependencies only if this is a new dependency chain.
1579          * (If lookup_chain_cache() returns with 1 it acquires
1580          * graph_lock for us)
1581          */
1582         if (!hlock->trylock && (hlock->check == 2) &&
1583             lookup_chain_cache(curr, hlock, chain_key)) {
1584                 /*
1585                  * Check whether last held lock:
1586                  *
1587                  * - is irq-safe, if this lock is irq-unsafe
1588                  * - is softirq-safe, if this lock is hardirq-unsafe
1589                  *
1590                  * And check whether the new lock's dependency graph
1591                  * could lead back to the previous lock.
1592                  *
1593                  * any of these scenarios could lead to a deadlock. If
1594                  * All validations
1595                  */
1596                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1597
1598                 if (!ret)
1599                         return 0;
1600                 /*
1601                  * Mark recursive read, as we jump over it when
1602                  * building dependencies (just like we jump over
1603                  * trylock entries):
1604                  */
1605                 if (ret == 2)
1606                         hlock->read = 2;
1607                 /*
1608                  * Add dependency only if this lock is not the head
1609                  * of the chain, and if it's not a secondary read-lock:
1610                  */
1611                 if (!chain_head && ret != 2)
1612                         if (!check_prevs_add(curr, hlock))
1613                                 return 0;
1614                 graph_unlock();
1615         } else
1616                 /* after lookup_chain_cache(): */
1617                 if (unlikely(!debug_locks))
1618                         return 0;
1619
1620         return 1;
1621 }
1622 #else
1623 static inline int validate_chain(struct task_struct *curr,
1624                 struct lockdep_map *lock, struct held_lock *hlock,
1625                 int chain_head, u64 chain_key)
1626 {
1627         return 1;
1628 }
1629 #endif
1630
1631 /*
1632  * We are building curr_chain_key incrementally, so double-check
1633  * it from scratch, to make sure that it's done correctly:
1634  */
1635 static void check_chain_key(struct task_struct *curr)
1636 {
1637 #ifdef CONFIG_DEBUG_LOCKDEP
1638         struct held_lock *hlock, *prev_hlock = NULL;
1639         unsigned int i, id;
1640         u64 chain_key = 0;
1641
1642         for (i = 0; i < curr->lockdep_depth; i++) {
1643                 hlock = curr->held_locks + i;
1644                 if (chain_key != hlock->prev_chain_key) {
1645                         debug_locks_off();
1646                         printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1647                                 curr->lockdep_depth, i,
1648                                 (unsigned long long)chain_key,
1649                                 (unsigned long long)hlock->prev_chain_key);
1650                         WARN_ON(1);
1651                         return;
1652                 }
1653                 id = hlock->class - lock_classes;
1654                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1655                         return;
1656
1657                 if (prev_hlock && (prev_hlock->irq_context !=
1658                                                         hlock->irq_context))
1659                         chain_key = 0;
1660                 chain_key = iterate_chain_key(chain_key, id);
1661                 prev_hlock = hlock;
1662         }
1663         if (chain_key != curr->curr_chain_key) {
1664                 debug_locks_off();
1665                 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1666                         curr->lockdep_depth, i,
1667                         (unsigned long long)chain_key,
1668                         (unsigned long long)curr->curr_chain_key);
1669                 WARN_ON(1);
1670         }
1671 #endif
1672 }
1673
1674 static int
1675 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1676                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1677 {
1678         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1679                 return 0;
1680
1681         printk("\n=================================\n");
1682         printk(  "[ INFO: inconsistent lock state ]\n");
1683         print_kernel_version();
1684         printk(  "---------------------------------\n");
1685
1686         printk("inconsistent {%s} -> {%s} usage.\n",
1687                 usage_str[prev_bit], usage_str[new_bit]);
1688
1689         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1690                 curr->comm, task_pid_nr(curr),
1691                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1692                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1693                 trace_hardirqs_enabled(curr),
1694                 trace_softirqs_enabled(curr));
1695         print_lock(this);
1696
1697         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1698         print_stack_trace(this->class->usage_traces + prev_bit, 1);
1699
1700         print_irqtrace_events(curr);
1701         printk("\nother info that might help us debug this:\n");
1702         lockdep_print_held_locks(curr);
1703
1704         printk("\nstack backtrace:\n");
1705         dump_stack();
1706
1707         return 0;
1708 }
1709
1710 /*
1711  * Print out an error if an invalid bit is set:
1712  */
1713 static inline int
1714 valid_state(struct task_struct *curr, struct held_lock *this,
1715             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1716 {
1717         if (unlikely(this->class->usage_mask & (1 << bad_bit)))
1718                 return print_usage_bug(curr, this, bad_bit, new_bit);
1719         return 1;
1720 }
1721
1722 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1723                      enum lock_usage_bit new_bit);
1724
1725 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1726
1727 /*
1728  * print irq inversion bug:
1729  */
1730 static int
1731 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1732                         struct held_lock *this, int forwards,
1733                         const char *irqclass)
1734 {
1735         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1736                 return 0;
1737
1738         printk("\n=========================================================\n");
1739         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
1740         print_kernel_version();
1741         printk(  "---------------------------------------------------------\n");
1742         printk("%s/%d just changed the state of lock:\n",
1743                 curr->comm, task_pid_nr(curr));
1744         print_lock(this);
1745         if (forwards)
1746                 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1747         else
1748                 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1749         print_lock_name(other);
1750         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1751
1752         printk("\nother info that might help us debug this:\n");
1753         lockdep_print_held_locks(curr);
1754
1755         printk("\nthe first lock's dependencies:\n");
1756         print_lock_dependencies(this->class, 0);
1757
1758         printk("\nthe second lock's dependencies:\n");
1759         print_lock_dependencies(other, 0);
1760
1761         printk("\nstack backtrace:\n");
1762         dump_stack();
1763
1764         return 0;
1765 }
1766
1767 /*
1768  * Prove that in the forwards-direction subgraph starting at <this>
1769  * there is no lock matching <mask>:
1770  */
1771 static int
1772 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1773                      enum lock_usage_bit bit, const char *irqclass)
1774 {
1775         int ret;
1776
1777         find_usage_bit = bit;
1778         /* fills in <forwards_match> */
1779         ret = find_usage_forwards(this->class, 0);
1780         if (!ret || ret == 1)
1781                 return ret;
1782
1783         return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1784 }
1785
1786 /*
1787  * Prove that in the backwards-direction subgraph starting at <this>
1788  * there is no lock matching <mask>:
1789  */
1790 static int
1791 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1792                       enum lock_usage_bit bit, const char *irqclass)
1793 {
1794         int ret;
1795
1796         find_usage_bit = bit;
1797         /* fills in <backwards_match> */
1798         ret = find_usage_backwards(this->class, 0);
1799         if (!ret || ret == 1)
1800                 return ret;
1801
1802         return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1803 }
1804
1805 void print_irqtrace_events(struct task_struct *curr)
1806 {
1807         printk("irq event stamp: %u\n", curr->irq_events);
1808         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
1809         print_ip_sym(curr->hardirq_enable_ip);
1810         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1811         print_ip_sym(curr->hardirq_disable_ip);
1812         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
1813         print_ip_sym(curr->softirq_enable_ip);
1814         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1815         print_ip_sym(curr->softirq_disable_ip);
1816 }
1817
1818 static int hardirq_verbose(struct lock_class *class)
1819 {
1820 #if HARDIRQ_VERBOSE
1821         return class_filter(class);
1822 #endif
1823         return 0;
1824 }
1825
1826 static int softirq_verbose(struct lock_class *class)
1827 {
1828 #if SOFTIRQ_VERBOSE
1829         return class_filter(class);
1830 #endif
1831         return 0;
1832 }
1833
1834 #define STRICT_READ_CHECKS      1
1835
1836 static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
1837                 enum lock_usage_bit new_bit)
1838 {
1839         int ret = 1;
1840
1841         switch(new_bit) {
1842         case LOCK_USED_IN_HARDIRQ:
1843                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1844                         return 0;
1845                 if (!valid_state(curr, this, new_bit,
1846                                  LOCK_ENABLED_HARDIRQS_READ))
1847                         return 0;
1848                 /*
1849                  * just marked it hardirq-safe, check that this lock
1850                  * took no hardirq-unsafe lock in the past:
1851                  */
1852                 if (!check_usage_forwards(curr, this,
1853                                           LOCK_ENABLED_HARDIRQS, "hard"))
1854                         return 0;
1855 #if STRICT_READ_CHECKS
1856                 /*
1857                  * just marked it hardirq-safe, check that this lock
1858                  * took no hardirq-unsafe-read lock in the past:
1859                  */
1860                 if (!check_usage_forwards(curr, this,
1861                                 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1862                         return 0;
1863 #endif
1864                 if (hardirq_verbose(this->class))
1865                         ret = 2;
1866                 break;
1867         case LOCK_USED_IN_SOFTIRQ:
1868                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1869                         return 0;
1870                 if (!valid_state(curr, this, new_bit,
1871                                  LOCK_ENABLED_SOFTIRQS_READ))
1872                         return 0;
1873                 /*
1874                  * just marked it softirq-safe, check that this lock
1875                  * took no softirq-unsafe lock in the past:
1876                  */
1877                 if (!check_usage_forwards(curr, this,
1878                                           LOCK_ENABLED_SOFTIRQS, "soft"))
1879                         return 0;
1880 #if STRICT_READ_CHECKS
1881                 /*
1882                  * just marked it softirq-safe, check that this lock
1883                  * took no softirq-unsafe-read lock in the past:
1884                  */
1885                 if (!check_usage_forwards(curr, this,
1886                                 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
1887                         return 0;
1888 #endif
1889                 if (softirq_verbose(this->class))
1890                         ret = 2;
1891                 break;
1892         case LOCK_USED_IN_HARDIRQ_READ:
1893                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1894                         return 0;
1895                 /*
1896                  * just marked it hardirq-read-safe, check that this lock
1897                  * took no hardirq-unsafe lock in the past:
1898                  */
1899                 if (!check_usage_forwards(curr, this,
1900                                           LOCK_ENABLED_HARDIRQS, "hard"))
1901                         return 0;
1902                 if (hardirq_verbose(this->class))
1903                         ret = 2;
1904                 break;
1905         case LOCK_USED_IN_SOFTIRQ_READ:
1906                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1907                         return 0;
1908                 /*
1909                  * just marked it softirq-read-safe, check that this lock
1910                  * took no softirq-unsafe lock in the past:
1911                  */
1912                 if (!check_usage_forwards(curr, this,
1913                                           LOCK_ENABLED_SOFTIRQS, "soft"))
1914                         return 0;
1915                 if (softirq_verbose(this->class))
1916                         ret = 2;
1917                 break;
1918         case LOCK_ENABLED_HARDIRQS:
1919                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1920                         return 0;
1921                 if (!valid_state(curr, this, new_bit,
1922                                  LOCK_USED_IN_HARDIRQ_READ))
1923                         return 0;
1924                 /*
1925                  * just marked it hardirq-unsafe, check that no hardirq-safe
1926                  * lock in the system ever took it in the past:
1927                  */
1928                 if (!check_usage_backwards(curr, this,
1929                                            LOCK_USED_IN_HARDIRQ, "hard"))
1930                         return 0;
1931 #if STRICT_READ_CHECKS
1932                 /*
1933                  * just marked it hardirq-unsafe, check that no
1934                  * hardirq-safe-read lock in the system ever took
1935                  * it in the past:
1936                  */
1937                 if (!check_usage_backwards(curr, this,
1938                                    LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
1939                         return 0;
1940 #endif
1941                 if (hardirq_verbose(this->class))
1942                         ret = 2;
1943                 break;
1944         case LOCK_ENABLED_SOFTIRQS:
1945                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1946                         return 0;
1947                 if (!valid_state(curr, this, new_bit,
1948                                  LOCK_USED_IN_SOFTIRQ_READ))
1949                         return 0;
1950                 /*
1951                  * just marked it softirq-unsafe, check that no softirq-safe
1952                  * lock in the system ever took it in the past:
1953                  */
1954                 if (!check_usage_backwards(curr, this,
1955                                            LOCK_USED_IN_SOFTIRQ, "soft"))
1956                         return 0;
1957 #if STRICT_READ_CHECKS
1958                 /*
1959                  * just marked it softirq-unsafe, check that no
1960                  * softirq-safe-read lock in the system ever took
1961                  * it in the past:
1962                  */
1963                 if (!check_usage_backwards(curr, this,
1964                                    LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
1965                         return 0;
1966 #endif
1967                 if (softirq_verbose(this->class))
1968                         ret = 2;
1969                 break;
1970         case LOCK_ENABLED_HARDIRQS_READ:
1971                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1972                         return 0;
1973 #if STRICT_READ_CHECKS
1974                 /*
1975                  * just marked it hardirq-read-unsafe, check that no
1976                  * hardirq-safe lock in the system ever took it in the past:
1977                  */
1978                 if (!check_usage_backwards(curr, this,
1979                                            LOCK_USED_IN_HARDIRQ, "hard"))
1980                         return 0;
1981 #endif
1982                 if (hardirq_verbose(this->class))
1983                         ret = 2;
1984                 break;
1985         case LOCK_ENABLED_SOFTIRQS_READ:
1986                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1987                         return 0;
1988 #if STRICT_READ_CHECKS
1989                 /*
1990                  * just marked it softirq-read-unsafe, check that no
1991                  * softirq-safe lock in the system ever took it in the past:
1992                  */
1993                 if (!check_usage_backwards(curr, this,
1994                                            LOCK_USED_IN_SOFTIRQ, "soft"))
1995                         return 0;
1996 #endif
1997                 if (softirq_verbose(this->class))
1998                         ret = 2;
1999                 break;
2000         default:
2001                 WARN_ON(1);
2002                 break;
2003         }
2004
2005         return ret;
2006 }
2007
2008 /*
2009  * Mark all held locks with a usage bit:
2010  */
2011 static int
2012 mark_held_locks(struct task_struct *curr, int hardirq)
2013 {
2014         enum lock_usage_bit usage_bit;
2015         struct held_lock *hlock;
2016         int i;
2017
2018         for (i = 0; i < curr->lockdep_depth; i++) {
2019                 hlock = curr->held_locks + i;
2020
2021                 if (hardirq) {
2022                         if (hlock->read)
2023                                 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
2024                         else
2025                                 usage_bit = LOCK_ENABLED_HARDIRQS;
2026                 } else {
2027                         if (hlock->read)
2028                                 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
2029                         else
2030                                 usage_bit = LOCK_ENABLED_SOFTIRQS;
2031                 }
2032                 if (!mark_lock(curr, hlock, usage_bit))
2033                         return 0;
2034         }
2035
2036         return 1;
2037 }
2038
2039 /*
2040  * Debugging helper: via this flag we know that we are in
2041  * 'early bootup code', and will warn about any invalid irqs-on event:
2042  */
2043 static int early_boot_irqs_enabled;
2044
2045 void early_boot_irqs_off(void)
2046 {
2047         early_boot_irqs_enabled = 0;
2048 }
2049
2050 void early_boot_irqs_on(void)
2051 {
2052         early_boot_irqs_enabled = 1;
2053 }
2054
2055 /*
2056  * Hardirqs will be enabled:
2057  */
2058 void trace_hardirqs_on_caller(unsigned long a0)
2059 {
2060         struct task_struct *curr = current;
2061         unsigned long ip;
2062
2063         time_hardirqs_on(CALLER_ADDR0, a0);
2064
2065         if (unlikely(!debug_locks || current->lockdep_recursion))
2066                 return;
2067
2068         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2069                 return;
2070
2071         if (unlikely(curr->hardirqs_enabled)) {
2072                 debug_atomic_inc(&redundant_hardirqs_on);
2073                 return;
2074         }
2075         /* we'll do an OFF -> ON transition: */
2076         curr->hardirqs_enabled = 1;
2077         ip = (unsigned long) __builtin_return_address(0);
2078
2079         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2080                 return;
2081         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2082                 return;
2083         /*
2084          * We are going to turn hardirqs on, so set the
2085          * usage bit for all held locks:
2086          */
2087         if (!mark_held_locks(curr, 1))
2088                 return;
2089         /*
2090          * If we have softirqs enabled, then set the usage
2091          * bit for all held locks. (disabled hardirqs prevented
2092          * this bit from being set before)
2093          */
2094         if (curr->softirqs_enabled)
2095                 if (!mark_held_locks(curr, 0))
2096                         return;
2097
2098         curr->hardirq_enable_ip = ip;
2099         curr->hardirq_enable_event = ++curr->irq_events;
2100         debug_atomic_inc(&hardirqs_on_events);
2101 }
2102 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2103
2104 void trace_hardirqs_on(void)
2105 {
2106         trace_hardirqs_on_caller(CALLER_ADDR0);
2107 }
2108 EXPORT_SYMBOL(trace_hardirqs_on);
2109
2110 /*
2111  * Hardirqs were disabled:
2112  */
2113 void trace_hardirqs_off_caller(unsigned long a0)
2114 {
2115         struct task_struct *curr = current;
2116
2117         time_hardirqs_off(CALLER_ADDR0, a0);
2118
2119         if (unlikely(!debug_locks || current->lockdep_recursion))
2120                 return;
2121
2122         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2123                 return;
2124
2125         if (curr->hardirqs_enabled) {
2126                 /*
2127                  * We have done an ON -> OFF transition:
2128                  */
2129                 curr->hardirqs_enabled = 0;
2130                 curr->hardirq_disable_ip = _RET_IP_;
2131                 curr->hardirq_disable_event = ++curr->irq_events;
2132                 debug_atomic_inc(&hardirqs_off_events);
2133         } else
2134                 debug_atomic_inc(&redundant_hardirqs_off);
2135 }
2136 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2137
2138 void trace_hardirqs_off(void)
2139 {
2140         trace_hardirqs_off_caller(CALLER_ADDR0);
2141 }
2142 EXPORT_SYMBOL(trace_hardirqs_off);
2143
2144 /*
2145  * Softirqs will be enabled:
2146  */
2147 void trace_softirqs_on(unsigned long ip)
2148 {
2149         struct task_struct *curr = current;
2150
2151         if (unlikely(!debug_locks))
2152                 return;
2153
2154         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2155                 return;
2156
2157         if (curr->softirqs_enabled) {
2158                 debug_atomic_inc(&redundant_softirqs_on);
2159                 return;
2160         }
2161
2162         /*
2163          * We'll do an OFF -> ON transition:
2164          */
2165         curr->softirqs_enabled = 1;
2166         curr->softirq_enable_ip = ip;
2167         curr->softirq_enable_event = ++curr->irq_events;
2168         debug_atomic_inc(&softirqs_on_events);
2169         /*
2170          * We are going to turn softirqs on, so set the
2171          * usage bit for all held locks, if hardirqs are
2172          * enabled too:
2173          */
2174         if (curr->hardirqs_enabled)
2175                 mark_held_locks(curr, 0);
2176 }
2177
2178 /*
2179  * Softirqs were disabled:
2180  */
2181 void trace_softirqs_off(unsigned long ip)
2182 {
2183         struct task_struct *curr = current;
2184
2185         if (unlikely(!debug_locks))
2186                 return;
2187
2188         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2189                 return;
2190
2191         if (curr->softirqs_enabled) {
2192                 /*
2193                  * We have done an ON -> OFF transition:
2194                  */
2195                 curr->softirqs_enabled = 0;
2196                 curr->softirq_disable_ip = ip;
2197                 curr->softirq_disable_event = ++curr->irq_events;
2198                 debug_atomic_inc(&softirqs_off_events);
2199                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2200         } else
2201                 debug_atomic_inc(&redundant_softirqs_off);
2202 }
2203
2204 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2205 {
2206         /*
2207          * If non-trylock use in a hardirq or softirq context, then
2208          * mark the lock as used in these contexts:
2209          */
2210         if (!hlock->trylock) {
2211                 if (hlock->read) {
2212                         if (curr->hardirq_context)
2213                                 if (!mark_lock(curr, hlock,
2214                                                 LOCK_USED_IN_HARDIRQ_READ))
2215                                         return 0;
2216                         if (curr->softirq_context)
2217                                 if (!mark_lock(curr, hlock,
2218                                                 LOCK_USED_IN_SOFTIRQ_READ))
2219                                         return 0;
2220                 } else {
2221                         if (curr->hardirq_context)
2222                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2223                                         return 0;
2224                         if (curr->softirq_context)
2225                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2226                                         return 0;
2227                 }
2228         }
2229         if (!hlock->hardirqs_off) {
2230                 if (hlock->read) {
2231                         if (!mark_lock(curr, hlock,
2232                                         LOCK_ENABLED_HARDIRQS_READ))
2233                                 return 0;
2234                         if (curr->softirqs_enabled)
2235                                 if (!mark_lock(curr, hlock,
2236                                                 LOCK_ENABLED_SOFTIRQS_READ))
2237                                         return 0;
2238                 } else {
2239                         if (!mark_lock(curr, hlock,
2240                                         LOCK_ENABLED_HARDIRQS))
2241                                 return 0;
2242                         if (curr->softirqs_enabled)
2243                                 if (!mark_lock(curr, hlock,
2244                                                 LOCK_ENABLED_SOFTIRQS))
2245                                         return 0;
2246                 }
2247         }
2248
2249         return 1;
2250 }
2251
2252 static int separate_irq_context(struct task_struct *curr,
2253                 struct held_lock *hlock)
2254 {
2255         unsigned int depth = curr->lockdep_depth;
2256
2257         /*
2258          * Keep track of points where we cross into an interrupt context:
2259          */
2260         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2261                                 curr->softirq_context;
2262         if (depth) {
2263                 struct held_lock *prev_hlock;
2264
2265                 prev_hlock = curr->held_locks + depth-1;
2266                 /*
2267                  * If we cross into another context, reset the
2268                  * hash key (this also prevents the checking and the
2269                  * adding of the dependency to 'prev'):
2270                  */
2271                 if (prev_hlock->irq_context != hlock->irq_context)
2272                         return 1;
2273         }
2274         return 0;
2275 }
2276
2277 #else
2278
2279 static inline
2280 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2281                 enum lock_usage_bit new_bit)
2282 {
2283         WARN_ON(1);
2284         return 1;
2285 }
2286
2287 static inline int mark_irqflags(struct task_struct *curr,
2288                 struct held_lock *hlock)
2289 {
2290         return 1;
2291 }
2292
2293 static inline int separate_irq_context(struct task_struct *curr,
2294                 struct held_lock *hlock)
2295 {
2296         return 0;
2297 }
2298
2299 #endif
2300
2301 /*
2302  * Mark a lock with a usage bit, and validate the state transition:
2303  */
2304 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2305                              enum lock_usage_bit new_bit)
2306 {
2307         unsigned int new_mask = 1 << new_bit, ret = 1;
2308
2309         /*
2310          * If already set then do not dirty the cacheline,
2311          * nor do any checks:
2312          */
2313         if (likely(this->class->usage_mask & new_mask))
2314                 return 1;
2315
2316         if (!graph_lock())
2317                 return 0;
2318         /*
2319          * Make sure we didnt race:
2320          */
2321         if (unlikely(this->class->usage_mask & new_mask)) {
2322                 graph_unlock();
2323                 return 1;
2324         }
2325
2326         this->class->usage_mask |= new_mask;
2327
2328         if (!save_trace(this->class->usage_traces + new_bit))
2329                 return 0;
2330
2331         switch (new_bit) {
2332         case LOCK_USED_IN_HARDIRQ:
2333         case LOCK_USED_IN_SOFTIRQ:
2334         case LOCK_USED_IN_HARDIRQ_READ:
2335         case LOCK_USED_IN_SOFTIRQ_READ:
2336         case LOCK_ENABLED_HARDIRQS:
2337         case LOCK_ENABLED_SOFTIRQS:
2338         case LOCK_ENABLED_HARDIRQS_READ:
2339         case LOCK_ENABLED_SOFTIRQS_READ:
2340                 ret = mark_lock_irq(curr, this, new_bit);
2341                 if (!ret)
2342                         return 0;
2343                 break;
2344         case LOCK_USED:
2345                 debug_atomic_dec(&nr_unused_locks);
2346                 break;
2347         default:
2348                 if (!debug_locks_off_graph_unlock())
2349                         return 0;
2350                 WARN_ON(1);
2351                 return 0;
2352         }
2353
2354         graph_unlock();
2355
2356         /*
2357          * We must printk outside of the graph_lock:
2358          */
2359         if (ret == 2) {
2360                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2361                 print_lock(this);
2362                 print_irqtrace_events(curr);
2363                 dump_stack();
2364         }
2365
2366         return ret;
2367 }
2368
2369 /*
2370  * Initialize a lock instance's lock-class mapping info:
2371  */
2372 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2373                       struct lock_class_key *key, int subclass)
2374 {
2375         if (unlikely(!debug_locks))
2376                 return;
2377
2378         if (DEBUG_LOCKS_WARN_ON(!key))
2379                 return;
2380         if (DEBUG_LOCKS_WARN_ON(!name))
2381                 return;
2382         /*
2383          * Sanity check, the lock-class key must be persistent:
2384          */
2385         if (!static_obj(key)) {
2386                 printk("BUG: key %p not in .data!\n", key);
2387                 DEBUG_LOCKS_WARN_ON(1);
2388                 return;
2389         }
2390         lock->name = name;
2391         lock->key = key;
2392         lock->class_cache = NULL;
2393 #ifdef CONFIG_LOCK_STAT
2394         lock->cpu = raw_smp_processor_id();
2395 #endif
2396         if (subclass)
2397                 register_lock_class(lock, subclass, 1);
2398 }
2399
2400 EXPORT_SYMBOL_GPL(lockdep_init_map);
2401
2402 /*
2403  * This gets called for every mutex_lock*()/spin_lock*() operation.
2404  * We maintain the dependency maps and validate the locking attempt:
2405  */
2406 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2407                           int trylock, int read, int check, int hardirqs_off,
2408                           unsigned long ip)
2409 {
2410         struct task_struct *curr = current;
2411         struct lock_class *class = NULL;
2412         struct held_lock *hlock;
2413         unsigned int depth, id;
2414         int chain_head = 0;
2415         u64 chain_key;
2416
2417         if (!prove_locking)
2418                 check = 1;
2419
2420         if (unlikely(!debug_locks))
2421                 return 0;
2422
2423         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2424                 return 0;
2425
2426         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2427                 debug_locks_off();
2428                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2429                 printk("turning off the locking correctness validator.\n");
2430                 return 0;
2431         }
2432
2433         if (!subclass)
2434                 class = lock->class_cache;
2435         /*
2436          * Not cached yet or subclass?
2437          */
2438         if (unlikely(!class)) {
2439                 class = register_lock_class(lock, subclass, 0);
2440                 if (!class)
2441                         return 0;
2442         }
2443         debug_atomic_inc((atomic_t *)&class->ops);
2444         if (very_verbose(class)) {
2445                 printk("\nacquire class [%p] %s", class->key, class->name);
2446                 if (class->name_version > 1)
2447                         printk("#%d", class->name_version);
2448                 printk("\n");
2449                 dump_stack();
2450         }
2451
2452         /*
2453          * Add the lock to the list of currently held locks.
2454          * (we dont increase the depth just yet, up until the
2455          * dependency checks are done)
2456          */
2457         depth = curr->lockdep_depth;
2458         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2459                 return 0;
2460
2461         hlock = curr->held_locks + depth;
2462
2463         hlock->class = class;
2464         hlock->acquire_ip = ip;
2465         hlock->instance = lock;
2466         hlock->trylock = trylock;
2467         hlock->read = read;
2468         hlock->check = check;
2469         hlock->hardirqs_off = hardirqs_off;
2470 #ifdef CONFIG_LOCK_STAT
2471         hlock->waittime_stamp = 0;
2472         hlock->holdtime_stamp = sched_clock();
2473 #endif
2474
2475         if (check == 2 && !mark_irqflags(curr, hlock))
2476                 return 0;
2477
2478         /* mark it as used: */
2479         if (!mark_lock(curr, hlock, LOCK_USED))
2480                 return 0;
2481
2482         /*
2483          * Calculate the chain hash: it's the combined hash of all the
2484          * lock keys along the dependency chain. We save the hash value
2485          * at every step so that we can get the current hash easily
2486          * after unlock. The chain hash is then used to cache dependency
2487          * results.
2488          *
2489          * The 'key ID' is what is the most compact key value to drive
2490          * the hash, not class->key.
2491          */
2492         id = class - lock_classes;
2493         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2494                 return 0;
2495
2496         chain_key = curr->curr_chain_key;
2497         if (!depth) {
2498                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2499                         return 0;
2500                 chain_head = 1;
2501         }
2502
2503         hlock->prev_chain_key = chain_key;
2504         if (separate_irq_context(curr, hlock)) {
2505                 chain_key = 0;
2506                 chain_head = 1;
2507         }
2508         chain_key = iterate_chain_key(chain_key, id);
2509
2510         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2511                 return 0;
2512
2513         curr->curr_chain_key = chain_key;
2514         curr->lockdep_depth++;
2515         check_chain_key(curr);
2516 #ifdef CONFIG_DEBUG_LOCKDEP
2517         if (unlikely(!debug_locks))
2518                 return 0;
2519 #endif
2520         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2521                 debug_locks_off();
2522                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2523                 printk("turning off the locking correctness validator.\n");
2524                 return 0;
2525         }
2526
2527         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2528                 max_lockdep_depth = curr->lockdep_depth;
2529
2530         return 1;
2531 }
2532
2533 static int
2534 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2535                            unsigned long ip)
2536 {
2537         if (!debug_locks_off())
2538                 return 0;
2539         if (debug_locks_silent)
2540                 return 0;
2541
2542         printk("\n=====================================\n");
2543         printk(  "[ BUG: bad unlock balance detected! ]\n");
2544         printk(  "-------------------------------------\n");
2545         printk("%s/%d is trying to release lock (",
2546                 curr->comm, task_pid_nr(curr));
2547         print_lockdep_cache(lock);
2548         printk(") at:\n");
2549         print_ip_sym(ip);
2550         printk("but there are no more locks to release!\n");
2551         printk("\nother info that might help us debug this:\n");
2552         lockdep_print_held_locks(curr);
2553
2554         printk("\nstack backtrace:\n");
2555         dump_stack();
2556
2557         return 0;
2558 }
2559
2560 /*
2561  * Common debugging checks for both nested and non-nested unlock:
2562  */
2563 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2564                         unsigned long ip)
2565 {
2566         if (unlikely(!debug_locks))
2567                 return 0;
2568         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2569                 return 0;
2570
2571         if (curr->lockdep_depth <= 0)
2572                 return print_unlock_inbalance_bug(curr, lock, ip);
2573
2574         return 1;
2575 }
2576
2577 /*
2578  * Remove the lock to the list of currently held locks in a
2579  * potentially non-nested (out of order) manner. This is a
2580  * relatively rare operation, as all the unlock APIs default
2581  * to nested mode (which uses lock_release()):
2582  */
2583 static int
2584 lock_release_non_nested(struct task_struct *curr,
2585                         struct lockdep_map *lock, unsigned long ip)
2586 {
2587         struct held_lock *hlock, *prev_hlock;
2588         unsigned int depth;
2589         int i;
2590
2591         /*
2592          * Check whether the lock exists in the current stack
2593          * of held locks:
2594          */
2595         depth = curr->lockdep_depth;
2596         if (DEBUG_LOCKS_WARN_ON(!depth))
2597                 return 0;
2598
2599         prev_hlock = NULL;
2600         for (i = depth-1; i >= 0; i--) {
2601                 hlock = curr->held_locks + i;
2602                 /*
2603                  * We must not cross into another context:
2604                  */
2605                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2606                         break;
2607                 if (hlock->instance == lock)
2608                         goto found_it;
2609                 prev_hlock = hlock;
2610         }
2611         return print_unlock_inbalance_bug(curr, lock, ip);
2612
2613 found_it:
2614         lock_release_holdtime(hlock);
2615
2616         /*
2617          * We have the right lock to unlock, 'hlock' points to it.
2618          * Now we remove it from the stack, and add back the other
2619          * entries (if any), recalculating the hash along the way:
2620          */
2621         curr->lockdep_depth = i;
2622         curr->curr_chain_key = hlock->prev_chain_key;
2623
2624         for (i++; i < depth; i++) {
2625                 hlock = curr->held_locks + i;
2626                 if (!__lock_acquire(hlock->instance,
2627                         hlock->class->subclass, hlock->trylock,
2628                                 hlock->read, hlock->check, hlock->hardirqs_off,
2629                                 hlock->acquire_ip))
2630                         return 0;
2631         }
2632
2633         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2634                 return 0;
2635         return 1;
2636 }
2637
2638 /*
2639  * Remove the lock to the list of currently held locks - this gets
2640  * called on mutex_unlock()/spin_unlock*() (or on a failed
2641  * mutex_lock_interruptible()). This is done for unlocks that nest
2642  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2643  */
2644 static int lock_release_nested(struct task_struct *curr,
2645                                struct lockdep_map *lock, unsigned long ip)
2646 {
2647         struct held_lock *hlock;
2648         unsigned int depth;
2649
2650         /*
2651          * Pop off the top of the lock stack:
2652          */
2653         depth = curr->lockdep_depth - 1;
2654         hlock = curr->held_locks + depth;
2655
2656         /*
2657          * Is the unlock non-nested:
2658          */
2659         if (hlock->instance != lock)
2660                 return lock_release_non_nested(curr, lock, ip);
2661         curr->lockdep_depth--;
2662
2663         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2664                 return 0;
2665
2666         curr->curr_chain_key = hlock->prev_chain_key;
2667
2668         lock_release_holdtime(hlock);
2669
2670 #ifdef CONFIG_DEBUG_LOCKDEP
2671         hlock->prev_chain_key = 0;
2672         hlock->class = NULL;
2673         hlock->acquire_ip = 0;
2674         hlock->irq_context = 0;
2675 #endif
2676         return 1;
2677 }
2678
2679 /*
2680  * Remove the lock to the list of currently held locks - this gets
2681  * called on mutex_unlock()/spin_unlock*() (or on a failed
2682  * mutex_lock_interruptible()). This is done for unlocks that nest
2683  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2684  */
2685 static void
2686 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2687 {
2688         struct task_struct *curr = current;
2689
2690         if (!check_unlock(curr, lock, ip))
2691                 return;
2692
2693         if (nested) {
2694                 if (!lock_release_nested(curr, lock, ip))
2695                         return;
2696         } else {
2697                 if (!lock_release_non_nested(curr, lock, ip))
2698                         return;
2699         }
2700
2701         check_chain_key(curr);
2702 }
2703
2704 /*
2705  * Check whether we follow the irq-flags state precisely:
2706  */
2707 static void check_flags(unsigned long flags)
2708 {
2709 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2710     defined(CONFIG_TRACE_IRQFLAGS)
2711         if (!debug_locks)
2712                 return;
2713
2714         if (irqs_disabled_flags(flags)) {
2715                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
2716                         printk("possible reason: unannotated irqs-off.\n");
2717                 }
2718         } else {
2719                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
2720                         printk("possible reason: unannotated irqs-on.\n");
2721                 }
2722         }
2723
2724         /*
2725          * We dont accurately track softirq state in e.g.
2726          * hardirq contexts (such as on 4KSTACKS), so only
2727          * check if not in hardirq contexts:
2728          */
2729         if (!hardirq_count()) {
2730                 if (softirq_count())
2731                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2732                 else
2733                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2734         }
2735
2736         if (!debug_locks)
2737                 print_irqtrace_events(current);
2738 #endif
2739 }
2740
2741 /*
2742  * We are not always called with irqs disabled - do that here,
2743  * and also avoid lockdep recursion:
2744  */
2745 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2746                           int trylock, int read, int check, unsigned long ip)
2747 {
2748         unsigned long flags;
2749
2750         if (unlikely(!lock_stat && !prove_locking))
2751                 return;
2752
2753         if (unlikely(current->lockdep_recursion))
2754                 return;
2755
2756         raw_local_irq_save(flags);
2757         check_flags(flags);
2758
2759         current->lockdep_recursion = 1;
2760         __lock_acquire(lock, subclass, trylock, read, check,
2761                        irqs_disabled_flags(flags), ip);
2762         current->lockdep_recursion = 0;
2763         raw_local_irq_restore(flags);
2764 }
2765
2766 EXPORT_SYMBOL_GPL(lock_acquire);
2767
2768 void lock_release(struct lockdep_map *lock, int nested,
2769                           unsigned long ip)
2770 {
2771         unsigned long flags;
2772
2773         if (unlikely(!lock_stat && !prove_locking))
2774                 return;
2775
2776         if (unlikely(current->lockdep_recursion))
2777                 return;
2778
2779         raw_local_irq_save(flags);
2780         check_flags(flags);
2781         current->lockdep_recursion = 1;
2782         __lock_release(lock, nested, ip);
2783         current->lockdep_recursion = 0;
2784         raw_local_irq_restore(flags);
2785 }
2786
2787 EXPORT_SYMBOL_GPL(lock_release);
2788
2789 #ifdef CONFIG_LOCK_STAT
2790 static int
2791 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
2792                            unsigned long ip)
2793 {
2794         if (!debug_locks_off())
2795                 return 0;
2796         if (debug_locks_silent)
2797                 return 0;
2798
2799         printk("\n=================================\n");
2800         printk(  "[ BUG: bad contention detected! ]\n");
2801         printk(  "---------------------------------\n");
2802         printk("%s/%d is trying to contend lock (",
2803                 curr->comm, task_pid_nr(curr));
2804         print_lockdep_cache(lock);
2805         printk(") at:\n");
2806         print_ip_sym(ip);
2807         printk("but there are no locks held!\n");
2808         printk("\nother info that might help us debug this:\n");
2809         lockdep_print_held_locks(curr);
2810
2811         printk("\nstack backtrace:\n");
2812         dump_stack();
2813
2814         return 0;
2815 }
2816
2817 static void
2818 __lock_contended(struct lockdep_map *lock, unsigned long ip)
2819 {
2820         struct task_struct *curr = current;
2821         struct held_lock *hlock, *prev_hlock;
2822         struct lock_class_stats *stats;
2823         unsigned int depth;
2824         int i, point;
2825
2826         depth = curr->lockdep_depth;
2827         if (DEBUG_LOCKS_WARN_ON(!depth))
2828                 return;
2829
2830         prev_hlock = NULL;
2831         for (i = depth-1; i >= 0; i--) {
2832                 hlock = curr->held_locks + i;
2833                 /*
2834                  * We must not cross into another context:
2835                  */
2836                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2837                         break;
2838                 if (hlock->instance == lock)
2839                         goto found_it;
2840                 prev_hlock = hlock;
2841         }
2842         print_lock_contention_bug(curr, lock, ip);
2843         return;
2844
2845 found_it:
2846         hlock->waittime_stamp = sched_clock();
2847
2848         point = lock_contention_point(hlock->class, ip);
2849
2850         stats = get_lock_stats(hlock->class);
2851         if (point < ARRAY_SIZE(stats->contention_point))
2852                 stats->contention_point[i]++;
2853         if (lock->cpu != smp_processor_id())
2854                 stats->bounces[bounce_contended + !!hlock->read]++;
2855         put_lock_stats(stats);
2856 }
2857
2858 static void
2859 __lock_acquired(struct lockdep_map *lock)
2860 {
2861         struct task_struct *curr = current;
2862         struct held_lock *hlock, *prev_hlock;
2863         struct lock_class_stats *stats;
2864         unsigned int depth;
2865         u64 now;
2866         s64 waittime = 0;
2867         int i, cpu;
2868
2869         depth = curr->lockdep_depth;
2870         if (DEBUG_LOCKS_WARN_ON(!depth))
2871                 return;
2872
2873         prev_hlock = NULL;
2874         for (i = depth-1; i >= 0; i--) {
2875                 hlock = curr->held_locks + i;
2876                 /*
2877                  * We must not cross into another context:
2878                  */
2879                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2880                         break;
2881                 if (hlock->instance == lock)
2882                         goto found_it;
2883                 prev_hlock = hlock;
2884         }
2885         print_lock_contention_bug(curr, lock, _RET_IP_);
2886         return;
2887
2888 found_it:
2889         cpu = smp_processor_id();
2890         if (hlock->waittime_stamp) {
2891                 now = sched_clock();
2892                 waittime = now - hlock->waittime_stamp;
2893                 hlock->holdtime_stamp = now;
2894         }
2895
2896         stats = get_lock_stats(hlock->class);
2897         if (waittime) {
2898                 if (hlock->read)
2899                         lock_time_inc(&stats->read_waittime, waittime);
2900                 else
2901                         lock_time_inc(&stats->write_waittime, waittime);
2902         }
2903         if (lock->cpu != cpu)
2904                 stats->bounces[bounce_acquired + !!hlock->read]++;
2905         put_lock_stats(stats);
2906
2907         lock->cpu = cpu;
2908 }
2909
2910 void lock_contended(struct lockdep_map *lock, unsigned long ip)
2911 {
2912         unsigned long flags;
2913
2914         if (unlikely(!lock_stat))
2915                 return;
2916
2917         if (unlikely(current->lockdep_recursion))
2918                 return;
2919
2920         raw_local_irq_save(flags);
2921         check_flags(flags);
2922         current->lockdep_recursion = 1;
2923         __lock_contended(lock, ip);
2924         current->lockdep_recursion = 0;
2925         raw_local_irq_restore(flags);
2926 }
2927 EXPORT_SYMBOL_GPL(lock_contended);
2928
2929 void lock_acquired(struct lockdep_map *lock)
2930 {
2931         unsigned long flags;
2932
2933         if (unlikely(!lock_stat))
2934                 return;
2935
2936         if (unlikely(current->lockdep_recursion))
2937                 return;
2938
2939         raw_local_irq_save(flags);
2940         check_flags(flags);
2941         current->lockdep_recursion = 1;
2942         __lock_acquired(lock);
2943         current->lockdep_recursion = 0;
2944         raw_local_irq_restore(flags);
2945 }
2946 EXPORT_SYMBOL_GPL(lock_acquired);
2947 #endif
2948
2949 /*
2950  * Used by the testsuite, sanitize the validator state
2951  * after a simulated failure:
2952  */
2953
2954 void lockdep_reset(void)
2955 {
2956         unsigned long flags;
2957         int i;
2958
2959         raw_local_irq_save(flags);
2960         current->curr_chain_key = 0;
2961         current->lockdep_depth = 0;
2962         current->lockdep_recursion = 0;
2963         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
2964         nr_hardirq_chains = 0;
2965         nr_softirq_chains = 0;
2966         nr_process_chains = 0;
2967         debug_locks = 1;
2968         for (i = 0; i < CHAINHASH_SIZE; i++)
2969                 INIT_LIST_HEAD(chainhash_table + i);
2970         raw_local_irq_restore(flags);
2971 }
2972
2973 static void zap_class(struct lock_class *class)
2974 {
2975         int i;
2976
2977         /*
2978          * Remove all dependencies this lock is
2979          * involved in:
2980          */
2981         for (i = 0; i < nr_list_entries; i++) {
2982                 if (list_entries[i].class == class)
2983                         list_del_rcu(&list_entries[i].entry);
2984         }
2985         /*
2986          * Unhash the class and remove it from the all_lock_classes list:
2987          */
2988         list_del_rcu(&class->hash_entry);
2989         list_del_rcu(&class->lock_entry);
2990
2991 }
2992
2993 static inline int within(const void *addr, void *start, unsigned long size)
2994 {
2995         return addr >= start && addr < start + size;
2996 }
2997
2998 void lockdep_free_key_range(void *start, unsigned long size)
2999 {
3000         struct lock_class *class, *next;
3001         struct list_head *head;
3002         unsigned long flags;
3003         int i;
3004         int locked;
3005
3006         raw_local_irq_save(flags);
3007         locked = graph_lock();
3008
3009         /*
3010          * Unhash all classes that were created by this module:
3011          */
3012         for (i = 0; i < CLASSHASH_SIZE; i++) {
3013                 head = classhash_table + i;
3014                 if (list_empty(head))
3015                         continue;
3016                 list_for_each_entry_safe(class, next, head, hash_entry) {
3017                         if (within(class->key, start, size))
3018                                 zap_class(class);
3019                         else if (within(class->name, start, size))
3020                                 zap_class(class);
3021                 }
3022         }
3023
3024         if (locked)
3025                 graph_unlock();
3026         raw_local_irq_restore(flags);
3027 }
3028
3029 void lockdep_reset_lock(struct lockdep_map *lock)
3030 {
3031         struct lock_class *class, *next;
3032         struct list_head *head;
3033         unsigned long flags;
3034         int i, j;
3035         int locked;
3036
3037         raw_local_irq_save(flags);
3038
3039         /*
3040          * Remove all classes this lock might have:
3041          */
3042         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3043                 /*
3044                  * If the class exists we look it up and zap it:
3045                  */
3046                 class = look_up_lock_class(lock, j);
3047                 if (class)
3048                         zap_class(class);
3049         }
3050         /*
3051          * Debug check: in the end all mapped classes should
3052          * be gone.
3053          */
3054         locked = graph_lock();
3055         for (i = 0; i < CLASSHASH_SIZE; i++) {
3056                 head = classhash_table + i;
3057                 if (list_empty(head))
3058                         continue;
3059                 list_for_each_entry_safe(class, next, head, hash_entry) {
3060                         if (unlikely(class == lock->class_cache)) {
3061                                 if (debug_locks_off_graph_unlock())
3062                                         WARN_ON(1);
3063                                 goto out_restore;
3064                         }
3065                 }
3066         }
3067         if (locked)
3068                 graph_unlock();
3069
3070 out_restore:
3071         raw_local_irq_restore(flags);
3072 }
3073
3074 void lockdep_init(void)
3075 {
3076         int i;
3077
3078         /*
3079          * Some architectures have their own start_kernel()
3080          * code which calls lockdep_init(), while we also
3081          * call lockdep_init() from the start_kernel() itself,
3082          * and we want to initialize the hashes only once:
3083          */
3084         if (lockdep_initialized)
3085                 return;
3086
3087         for (i = 0; i < CLASSHASH_SIZE; i++)
3088                 INIT_LIST_HEAD(classhash_table + i);
3089
3090         for (i = 0; i < CHAINHASH_SIZE; i++)
3091                 INIT_LIST_HEAD(chainhash_table + i);
3092
3093         lockdep_initialized = 1;
3094 }
3095
3096 void __init lockdep_info(void)
3097 {
3098         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3099
3100         printk("... MAX_LOCKDEP_SUBCLASSES:    %lu\n", MAX_LOCKDEP_SUBCLASSES);
3101         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3102         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3103         printk("... CLASSHASH_SIZE:           %lu\n", CLASSHASH_SIZE);
3104         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3105         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3106         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3107
3108         printk(" memory used by lock dependency info: %lu kB\n",
3109                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3110                 sizeof(struct list_head) * CLASSHASH_SIZE +
3111                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3112                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3113                 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
3114
3115         printk(" per task-struct memory footprint: %lu bytes\n",
3116                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3117
3118 #ifdef CONFIG_DEBUG_LOCKDEP
3119         if (lockdep_init_error) {
3120                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3121                 printk("Call stack leading to lockdep invocation was:\n");
3122                 print_stack_trace(&lockdep_init_trace, 0);
3123         }
3124 #endif
3125 }
3126
3127 static void
3128 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3129                      const void *mem_to, struct held_lock *hlock)
3130 {
3131         if (!debug_locks_off())
3132                 return;
3133         if (debug_locks_silent)
3134                 return;
3135
3136         printk("\n=========================\n");
3137         printk(  "[ BUG: held lock freed! ]\n");
3138         printk(  "-------------------------\n");
3139         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3140                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3141         print_lock(hlock);
3142         lockdep_print_held_locks(curr);
3143
3144         printk("\nstack backtrace:\n");
3145         dump_stack();
3146 }
3147
3148 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3149                                 const void* lock_from, unsigned long lock_len)
3150 {
3151         return lock_from + lock_len <= mem_from ||
3152                 mem_from + mem_len <= lock_from;
3153 }
3154
3155 /*
3156  * Called when kernel memory is freed (or unmapped), or if a lock
3157  * is destroyed or reinitialized - this code checks whether there is
3158  * any held lock in the memory range of <from> to <to>:
3159  */
3160 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3161 {
3162         struct task_struct *curr = current;
3163         struct held_lock *hlock;
3164         unsigned long flags;
3165         int i;
3166
3167         if (unlikely(!debug_locks))
3168                 return;
3169
3170         local_irq_save(flags);
3171         for (i = 0; i < curr->lockdep_depth; i++) {
3172                 hlock = curr->held_locks + i;
3173
3174                 if (not_in_range(mem_from, mem_len, hlock->instance,
3175                                         sizeof(*hlock->instance)))
3176                         continue;
3177
3178                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3179                 break;
3180         }
3181         local_irq_restore(flags);
3182 }
3183 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3184
3185 static void print_held_locks_bug(struct task_struct *curr)
3186 {
3187         if (!debug_locks_off())
3188                 return;
3189         if (debug_locks_silent)
3190                 return;
3191
3192         printk("\n=====================================\n");
3193         printk(  "[ BUG: lock held at task exit time! ]\n");
3194         printk(  "-------------------------------------\n");
3195         printk("%s/%d is exiting with locks still held!\n",
3196                 curr->comm, task_pid_nr(curr));
3197         lockdep_print_held_locks(curr);
3198
3199         printk("\nstack backtrace:\n");
3200         dump_stack();
3201 }
3202
3203 void debug_check_no_locks_held(struct task_struct *task)
3204 {
3205         if (unlikely(task->lockdep_depth > 0))
3206                 print_held_locks_bug(task);
3207 }
3208
3209 void debug_show_all_locks(void)
3210 {
3211         struct task_struct *g, *p;
3212         int count = 10;
3213         int unlock = 1;
3214
3215         if (unlikely(!debug_locks)) {
3216                 printk("INFO: lockdep is turned off.\n");
3217                 return;
3218         }
3219         printk("\nShowing all locks held in the system:\n");
3220
3221         /*
3222          * Here we try to get the tasklist_lock as hard as possible,
3223          * if not successful after 2 seconds we ignore it (but keep
3224          * trying). This is to enable a debug printout even if a
3225          * tasklist_lock-holding task deadlocks or crashes.
3226          */
3227 retry:
3228         if (!read_trylock(&tasklist_lock)) {
3229                 if (count == 10)
3230                         printk("hm, tasklist_lock locked, retrying... ");
3231                 if (count) {
3232                         count--;
3233                         printk(" #%d", 10-count);
3234                         mdelay(200);
3235                         goto retry;
3236                 }
3237                 printk(" ignoring it.\n");
3238                 unlock = 0;
3239         }
3240         if (count != 10)
3241                 printk(" locked it.\n");
3242
3243         do_each_thread(g, p) {
3244                 /*
3245                  * It's not reliable to print a task's held locks
3246                  * if it's not sleeping (or if it's not the current
3247                  * task):
3248                  */
3249                 if (p->state == TASK_RUNNING && p != current)
3250                         continue;
3251                 if (p->lockdep_depth)
3252                         lockdep_print_held_locks(p);
3253                 if (!unlock)
3254                         if (read_trylock(&tasklist_lock))
3255                                 unlock = 1;
3256         } while_each_thread(g, p);
3257
3258         printk("\n");
3259         printk("=============================================\n\n");
3260
3261         if (unlock)
3262                 read_unlock(&tasklist_lock);
3263 }
3264
3265 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3266
3267 /*
3268  * Careful: only use this function if you are sure that
3269  * the task cannot run in parallel!
3270  */
3271 void __debug_show_held_locks(struct task_struct *task)
3272 {
3273         if (unlikely(!debug_locks)) {
3274                 printk("INFO: lockdep is turned off.\n");
3275                 return;
3276         }
3277         lockdep_print_held_locks(task);
3278 }
3279 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3280
3281 void debug_show_held_locks(struct task_struct *task)
3282 {
3283                 __debug_show_held_locks(task);
3284 }
3285
3286 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3287
3288 void lockdep_sys_exit(void)
3289 {
3290         struct task_struct *curr = current;
3291
3292         if (unlikely(curr->lockdep_depth)) {
3293                 if (!debug_locks_off())
3294                         return;
3295                 printk("\n================================================\n");
3296                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3297                 printk(  "------------------------------------------------\n");
3298                 printk("%s/%d is leaving the kernel with locks still held!\n",
3299                                 curr->comm, curr->pid);
3300                 lockdep_print_held_locks(curr);
3301         }
3302 }