lockdep: consistent alignement for lockdep info
[linux-2.6.git] / kernel / lockdep.c
1 /*
2  * kernel/lockdep.c
3  *
4  * Runtime locking correctness validator
5  *
6  * Started by Ingo Molnar:
7  *
8  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
10  *
11  * this code maps all the lock dependencies as they occur in a live kernel
12  * and will warn about the following classes of locking bugs:
13  *
14  * - lock inversion scenarios
15  * - circular lock dependencies
16  * - hardirq/softirq safe/unsafe locking bugs
17  *
18  * Bugs are reported even if the current locking scenario does not cause
19  * any deadlock at this point.
20  *
21  * I.e. if anytime in the past two locks were taken in a different order,
22  * even if it happened for another task, even if those were different
23  * locks (but of the same class as this lock), this code will detect it.
24  *
25  * Thanks to Arjan van de Ven for coming up with the initial idea of
26  * mapping lock dependencies runtime.
27  */
28 #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 static inline struct lock_class *hlock_class(struct held_lock *hlock)
128 {
129         if (!hlock->class_idx) {
130                 DEBUG_LOCKS_WARN_ON(1);
131                 return NULL;
132         }
133         return lock_classes + hlock->class_idx - 1;
134 }
135
136 #ifdef CONFIG_LOCK_STAT
137 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
138
139 static int lock_contention_point(struct lock_class *class, unsigned long ip)
140 {
141         int i;
142
143         for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {
144                 if (class->contention_point[i] == 0) {
145                         class->contention_point[i] = ip;
146                         break;
147                 }
148                 if (class->contention_point[i] == ip)
149                         break;
150         }
151
152         return i;
153 }
154
155 static void lock_time_inc(struct lock_time *lt, s64 time)
156 {
157         if (time > lt->max)
158                 lt->max = time;
159
160         if (time < lt->min || !lt->min)
161                 lt->min = time;
162
163         lt->total += time;
164         lt->nr++;
165 }
166
167 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
168 {
169         dst->min += src->min;
170         dst->max += src->max;
171         dst->total += src->total;
172         dst->nr += src->nr;
173 }
174
175 struct lock_class_stats lock_stats(struct lock_class *class)
176 {
177         struct lock_class_stats stats;
178         int cpu, i;
179
180         memset(&stats, 0, sizeof(struct lock_class_stats));
181         for_each_possible_cpu(cpu) {
182                 struct lock_class_stats *pcs =
183                         &per_cpu(lock_stats, cpu)[class - lock_classes];
184
185                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
186                         stats.contention_point[i] += pcs->contention_point[i];
187
188                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
189                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
190
191                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
192                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
193
194                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
195                         stats.bounces[i] += pcs->bounces[i];
196         }
197
198         return stats;
199 }
200
201 void clear_lock_stats(struct lock_class *class)
202 {
203         int cpu;
204
205         for_each_possible_cpu(cpu) {
206                 struct lock_class_stats *cpu_stats =
207                         &per_cpu(lock_stats, cpu)[class - lock_classes];
208
209                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
210         }
211         memset(class->contention_point, 0, sizeof(class->contention_point));
212 }
213
214 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
215 {
216         return &get_cpu_var(lock_stats)[class - lock_classes];
217 }
218
219 static void put_lock_stats(struct lock_class_stats *stats)
220 {
221         put_cpu_var(lock_stats);
222 }
223
224 static void lock_release_holdtime(struct held_lock *hlock)
225 {
226         struct lock_class_stats *stats;
227         s64 holdtime;
228
229         if (!lock_stat)
230                 return;
231
232         holdtime = sched_clock() - hlock->holdtime_stamp;
233
234         stats = get_lock_stats(hlock_class(hlock));
235         if (hlock->read)
236                 lock_time_inc(&stats->read_holdtime, holdtime);
237         else
238                 lock_time_inc(&stats->write_holdtime, holdtime);
239         put_lock_stats(stats);
240 }
241 #else
242 static inline void lock_release_holdtime(struct held_lock *hlock)
243 {
244 }
245 #endif
246
247 /*
248  * We keep a global list of all lock classes. The list only grows,
249  * never shrinks. The list is only accessed with the lockdep
250  * spinlock lock held.
251  */
252 LIST_HEAD(all_lock_classes);
253
254 /*
255  * The lockdep classes are in a hash-table as well, for fast lookup:
256  */
257 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
258 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
259 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
260 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
261
262 static struct list_head classhash_table[CLASSHASH_SIZE];
263
264 /*
265  * We put the lock dependency chains into a hash-table as well, to cache
266  * their existence:
267  */
268 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
269 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
270 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
271 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
272
273 static struct list_head chainhash_table[CHAINHASH_SIZE];
274
275 /*
276  * The hash key of the lock dependency chains is a hash itself too:
277  * it's a hash of all locks taken up to that lock, including that lock.
278  * It's a 64-bit hash, because it's important for the keys to be
279  * unique.
280  */
281 #define iterate_chain_key(key1, key2) \
282         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
283         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
284         (key2))
285
286 void lockdep_off(void)
287 {
288         current->lockdep_recursion++;
289 }
290
291 EXPORT_SYMBOL(lockdep_off);
292
293 void lockdep_on(void)
294 {
295         current->lockdep_recursion--;
296 }
297
298 EXPORT_SYMBOL(lockdep_on);
299
300 /*
301  * Debugging switches:
302  */
303
304 #define VERBOSE                 0
305 #define VERY_VERBOSE            0
306
307 #if VERBOSE
308 # define HARDIRQ_VERBOSE        1
309 # define SOFTIRQ_VERBOSE        1
310 #else
311 # define HARDIRQ_VERBOSE        0
312 # define SOFTIRQ_VERBOSE        0
313 #endif
314
315 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
316 /*
317  * Quick filtering for interesting events:
318  */
319 static int class_filter(struct lock_class *class)
320 {
321 #if 0
322         /* Example */
323         if (class->name_version == 1 &&
324                         !strcmp(class->name, "lockname"))
325                 return 1;
326         if (class->name_version == 1 &&
327                         !strcmp(class->name, "&struct->lockfield"))
328                 return 1;
329 #endif
330         /* Filter everything else. 1 would be to allow everything else */
331         return 0;
332 }
333 #endif
334
335 static int verbose(struct lock_class *class)
336 {
337 #if VERBOSE
338         return class_filter(class);
339 #endif
340         return 0;
341 }
342
343 /*
344  * Stack-trace: tightly packed array of stack backtrace
345  * addresses. Protected by the graph_lock.
346  */
347 unsigned long nr_stack_trace_entries;
348 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
349
350 static int save_trace(struct stack_trace *trace)
351 {
352         trace->nr_entries = 0;
353         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
354         trace->entries = stack_trace + nr_stack_trace_entries;
355
356         trace->skip = 3;
357
358         save_stack_trace(trace);
359
360         trace->max_entries = trace->nr_entries;
361
362         nr_stack_trace_entries += trace->nr_entries;
363
364         if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
365                 if (!debug_locks_off_graph_unlock())
366                         return 0;
367
368                 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
369                 printk("turning off the locking correctness validator.\n");
370                 dump_stack();
371
372                 return 0;
373         }
374
375         return 1;
376 }
377
378 unsigned int nr_hardirq_chains;
379 unsigned int nr_softirq_chains;
380 unsigned int nr_process_chains;
381 unsigned int max_lockdep_depth;
382 unsigned int max_recursion_depth;
383
384 static unsigned int lockdep_dependency_gen_id;
385
386 static bool lockdep_dependency_visit(struct lock_class *source,
387                                      unsigned int depth)
388 {
389         if (!depth)
390                 lockdep_dependency_gen_id++;
391         if (source->dep_gen_id == lockdep_dependency_gen_id)
392                 return true;
393         source->dep_gen_id = lockdep_dependency_gen_id;
394         return false;
395 }
396
397 #ifdef CONFIG_DEBUG_LOCKDEP
398 /*
399  * We cannot printk in early bootup code. Not even early_printk()
400  * might work. So we mark any initialization errors and printk
401  * about it later on, in lockdep_info().
402  */
403 static int lockdep_init_error;
404 static unsigned long lockdep_init_trace_data[20];
405 static struct stack_trace lockdep_init_trace = {
406         .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
407         .entries = lockdep_init_trace_data,
408 };
409
410 /*
411  * Various lockdep statistics:
412  */
413 atomic_t chain_lookup_hits;
414 atomic_t chain_lookup_misses;
415 atomic_t hardirqs_on_events;
416 atomic_t hardirqs_off_events;
417 atomic_t redundant_hardirqs_on;
418 atomic_t redundant_hardirqs_off;
419 atomic_t softirqs_on_events;
420 atomic_t softirqs_off_events;
421 atomic_t redundant_softirqs_on;
422 atomic_t redundant_softirqs_off;
423 atomic_t nr_unused_locks;
424 atomic_t nr_cyclic_checks;
425 atomic_t nr_cyclic_check_recursions;
426 atomic_t nr_find_usage_forwards_checks;
427 atomic_t nr_find_usage_forwards_recursions;
428 atomic_t nr_find_usage_backwards_checks;
429 atomic_t nr_find_usage_backwards_recursions;
430 # define debug_atomic_inc(ptr)          atomic_inc(ptr)
431 # define debug_atomic_dec(ptr)          atomic_dec(ptr)
432 # define debug_atomic_read(ptr)         atomic_read(ptr)
433 #else
434 # define debug_atomic_inc(ptr)          do { } while (0)
435 # define debug_atomic_dec(ptr)          do { } while (0)
436 # define debug_atomic_read(ptr)         0
437 #endif
438
439 /*
440  * Locking printouts:
441  */
442
443 static const char *usage_str[] =
444 {
445         [LOCK_USED] =                   "initial-use ",
446         [LOCK_USED_IN_HARDIRQ] =        "in-hardirq-W",
447         [LOCK_USED_IN_SOFTIRQ] =        "in-softirq-W",
448         [LOCK_ENABLED_SOFTIRQS] =       "softirq-on-W",
449         [LOCK_ENABLED_HARDIRQS] =       "hardirq-on-W",
450         [LOCK_USED_IN_HARDIRQ_READ] =   "in-hardirq-R",
451         [LOCK_USED_IN_SOFTIRQ_READ] =   "in-softirq-R",
452         [LOCK_ENABLED_SOFTIRQS_READ] =  "softirq-on-R",
453         [LOCK_ENABLED_HARDIRQS_READ] =  "hardirq-on-R",
454 };
455
456 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
457 {
458         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
459 }
460
461 void
462 get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
463 {
464         *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
465
466         if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
467                 *c1 = '+';
468         else
469                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
470                         *c1 = '-';
471
472         if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
473                 *c2 = '+';
474         else
475                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
476                         *c2 = '-';
477
478         if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
479                 *c3 = '-';
480         if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
481                 *c3 = '+';
482                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
483                         *c3 = '?';
484         }
485
486         if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
487                 *c4 = '-';
488         if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
489                 *c4 = '+';
490                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
491                         *c4 = '?';
492         }
493 }
494
495 static void print_lock_name(struct lock_class *class)
496 {
497         char str[KSYM_NAME_LEN], c1, c2, c3, c4;
498         const char *name;
499
500         get_usage_chars(class, &c1, &c2, &c3, &c4);
501
502         name = class->name;
503         if (!name) {
504                 name = __get_key_name(class->key, str);
505                 printk(" (%s", name);
506         } else {
507                 printk(" (%s", name);
508                 if (class->name_version > 1)
509                         printk("#%d", class->name_version);
510                 if (class->subclass)
511                         printk("/%d", class->subclass);
512         }
513         printk("){%c%c%c%c}", c1, c2, c3, c4);
514 }
515
516 static void print_lockdep_cache(struct lockdep_map *lock)
517 {
518         const char *name;
519         char str[KSYM_NAME_LEN];
520
521         name = lock->name;
522         if (!name)
523                 name = __get_key_name(lock->key->subkeys, str);
524
525         printk("%s", name);
526 }
527
528 static void print_lock(struct held_lock *hlock)
529 {
530         print_lock_name(hlock_class(hlock));
531         printk(", at: ");
532         print_ip_sym(hlock->acquire_ip);
533 }
534
535 static void lockdep_print_held_locks(struct task_struct *curr)
536 {
537         int i, depth = curr->lockdep_depth;
538
539         if (!depth) {
540                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
541                 return;
542         }
543         printk("%d lock%s held by %s/%d:\n",
544                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
545
546         for (i = 0; i < depth; i++) {
547                 printk(" #%d: ", i);
548                 print_lock(curr->held_locks + i);
549         }
550 }
551
552 static void print_lock_class_header(struct lock_class *class, int depth)
553 {
554         int bit;
555
556         printk("%*s->", depth, "");
557         print_lock_name(class);
558         printk(" ops: %lu", class->ops);
559         printk(" {\n");
560
561         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
562                 if (class->usage_mask & (1 << bit)) {
563                         int len = depth;
564
565                         len += printk("%*s   %s", depth, "", usage_str[bit]);
566                         len += printk(" at:\n");
567                         print_stack_trace(class->usage_traces + bit, len);
568                 }
569         }
570         printk("%*s }\n", depth, "");
571
572         printk("%*s ... key      at: ",depth,"");
573         print_ip_sym((unsigned long)class->key);
574 }
575
576 /*
577  * printk all lock dependencies starting at <entry>:
578  */
579 static void print_lock_dependencies(struct lock_class *class, int depth)
580 {
581         struct lock_list *entry;
582
583         if (lockdep_dependency_visit(class, depth))
584                 return;
585
586         if (DEBUG_LOCKS_WARN_ON(depth >= 20))
587                 return;
588
589         print_lock_class_header(class, depth);
590
591         list_for_each_entry(entry, &class->locks_after, entry) {
592                 if (DEBUG_LOCKS_WARN_ON(!entry->class))
593                         return;
594
595                 print_lock_dependencies(entry->class, depth + 1);
596
597                 printk("%*s ... acquired at:\n",depth,"");
598                 print_stack_trace(&entry->trace, 2);
599                 printk("\n");
600         }
601 }
602
603 static void print_kernel_version(void)
604 {
605         printk("%s %.*s\n", init_utsname()->release,
606                 (int)strcspn(init_utsname()->version, " "),
607                 init_utsname()->version);
608 }
609
610 static int very_verbose(struct lock_class *class)
611 {
612 #if VERY_VERBOSE
613         return class_filter(class);
614 #endif
615         return 0;
616 }
617
618 /*
619  * Is this the address of a static object:
620  */
621 static int static_obj(void *obj)
622 {
623         unsigned long start = (unsigned long) &_stext,
624                       end   = (unsigned long) &_end,
625                       addr  = (unsigned long) obj;
626 #ifdef CONFIG_SMP
627         int i;
628 #endif
629
630         /*
631          * static variable?
632          */
633         if ((addr >= start) && (addr < end))
634                 return 1;
635
636 #ifdef CONFIG_SMP
637         /*
638          * percpu var?
639          */
640         for_each_possible_cpu(i) {
641                 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
642                 end   = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
643                                         + per_cpu_offset(i);
644
645                 if ((addr >= start) && (addr < end))
646                         return 1;
647         }
648 #endif
649
650         /*
651          * module var?
652          */
653         return is_module_address(addr);
654 }
655
656 /*
657  * To make lock name printouts unique, we calculate a unique
658  * class->name_version generation counter:
659  */
660 static int count_matching_names(struct lock_class *new_class)
661 {
662         struct lock_class *class;
663         int count = 0;
664
665         if (!new_class->name)
666                 return 0;
667
668         list_for_each_entry(class, &all_lock_classes, lock_entry) {
669                 if (new_class->key - new_class->subclass == class->key)
670                         return class->name_version;
671                 if (class->name && !strcmp(class->name, new_class->name))
672                         count = max(count, class->name_version);
673         }
674
675         return count + 1;
676 }
677
678 /*
679  * Register a lock's class in the hash-table, if the class is not present
680  * yet. Otherwise we look it up. We cache the result in the lock object
681  * itself, so actual lookup of the hash should be once per lock object.
682  */
683 static inline struct lock_class *
684 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
685 {
686         struct lockdep_subclass_key *key;
687         struct list_head *hash_head;
688         struct lock_class *class;
689
690 #ifdef CONFIG_DEBUG_LOCKDEP
691         /*
692          * If the architecture calls into lockdep before initializing
693          * the hashes then we'll warn about it later. (we cannot printk
694          * right now)
695          */
696         if (unlikely(!lockdep_initialized)) {
697                 lockdep_init();
698                 lockdep_init_error = 1;
699                 save_stack_trace(&lockdep_init_trace);
700         }
701 #endif
702
703         /*
704          * Static locks do not have their class-keys yet - for them the key
705          * is the lock object itself:
706          */
707         if (unlikely(!lock->key))
708                 lock->key = (void *)lock;
709
710         /*
711          * NOTE: the class-key must be unique. For dynamic locks, a static
712          * lock_class_key variable is passed in through the mutex_init()
713          * (or spin_lock_init()) call - which acts as the key. For static
714          * locks we use the lock object itself as the key.
715          */
716         BUILD_BUG_ON(sizeof(struct lock_class_key) >
717                         sizeof(struct lockdep_map));
718
719         key = lock->key->subkeys + subclass;
720
721         hash_head = classhashentry(key);
722
723         /*
724          * We can walk the hash lockfree, because the hash only
725          * grows, and we are careful when adding entries to the end:
726          */
727         list_for_each_entry(class, hash_head, hash_entry) {
728                 if (class->key == key) {
729                         WARN_ON_ONCE(class->name != lock->name);
730                         return class;
731                 }
732         }
733
734         return NULL;
735 }
736
737 /*
738  * Register a lock's class in the hash-table, if the class is not present
739  * yet. Otherwise we look it up. We cache the result in the lock object
740  * itself, so actual lookup of the hash should be once per lock object.
741  */
742 static inline struct lock_class *
743 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
744 {
745         struct lockdep_subclass_key *key;
746         struct list_head *hash_head;
747         struct lock_class *class;
748         unsigned long flags;
749
750         class = look_up_lock_class(lock, subclass);
751         if (likely(class))
752                 return class;
753
754         /*
755          * Debug-check: all keys must be persistent!
756          */
757         if (!static_obj(lock->key)) {
758                 debug_locks_off();
759                 printk("INFO: trying to register non-static key.\n");
760                 printk("the code is fine but needs lockdep annotation.\n");
761                 printk("turning off the locking correctness validator.\n");
762                 dump_stack();
763
764                 return NULL;
765         }
766
767         key = lock->key->subkeys + subclass;
768         hash_head = classhashentry(key);
769
770         raw_local_irq_save(flags);
771         if (!graph_lock()) {
772                 raw_local_irq_restore(flags);
773                 return NULL;
774         }
775         /*
776          * We have to do the hash-walk again, to avoid races
777          * with another CPU:
778          */
779         list_for_each_entry(class, hash_head, hash_entry)
780                 if (class->key == key)
781                         goto out_unlock_set;
782         /*
783          * Allocate a new key from the static array, and add it to
784          * the hash:
785          */
786         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
787                 if (!debug_locks_off_graph_unlock()) {
788                         raw_local_irq_restore(flags);
789                         return NULL;
790                 }
791                 raw_local_irq_restore(flags);
792
793                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
794                 printk("turning off the locking correctness validator.\n");
795                 return NULL;
796         }
797         class = lock_classes + nr_lock_classes++;
798         debug_atomic_inc(&nr_unused_locks);
799         class->key = key;
800         class->name = lock->name;
801         class->subclass = subclass;
802         INIT_LIST_HEAD(&class->lock_entry);
803         INIT_LIST_HEAD(&class->locks_before);
804         INIT_LIST_HEAD(&class->locks_after);
805         class->name_version = count_matching_names(class);
806         /*
807          * We use RCU's safe list-add method to make
808          * parallel walking of the hash-list safe:
809          */
810         list_add_tail_rcu(&class->hash_entry, hash_head);
811         /*
812          * Add it to the global list of classes:
813          */
814         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
815
816         if (verbose(class)) {
817                 graph_unlock();
818                 raw_local_irq_restore(flags);
819
820                 printk("\nnew class %p: %s", class->key, class->name);
821                 if (class->name_version > 1)
822                         printk("#%d", class->name_version);
823                 printk("\n");
824                 dump_stack();
825
826                 raw_local_irq_save(flags);
827                 if (!graph_lock()) {
828                         raw_local_irq_restore(flags);
829                         return NULL;
830                 }
831         }
832 out_unlock_set:
833         graph_unlock();
834         raw_local_irq_restore(flags);
835
836         if (!subclass || force)
837                 lock->class_cache = class;
838
839         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
840                 return NULL;
841
842         return class;
843 }
844
845 #ifdef CONFIG_PROVE_LOCKING
846 /*
847  * Allocate a lockdep entry. (assumes the graph_lock held, returns
848  * with NULL on failure)
849  */
850 static struct lock_list *alloc_list_entry(void)
851 {
852         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
853                 if (!debug_locks_off_graph_unlock())
854                         return NULL;
855
856                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
857                 printk("turning off the locking correctness validator.\n");
858                 return NULL;
859         }
860         return list_entries + nr_list_entries++;
861 }
862
863 /*
864  * Add a new dependency to the head of the list:
865  */
866 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
867                             struct list_head *head, unsigned long ip, int distance)
868 {
869         struct lock_list *entry;
870         /*
871          * Lock not present yet - get a new dependency struct and
872          * add it to the list:
873          */
874         entry = alloc_list_entry();
875         if (!entry)
876                 return 0;
877
878         if (!save_trace(&entry->trace))
879                 return 0;
880
881         entry->class = this;
882         entry->distance = distance;
883         /*
884          * Since we never remove from the dependency list, the list can
885          * be walked lockless by other CPUs, it's only allocation
886          * that must be protected by the spinlock. But this also means
887          * we must make new entries visible only once writes to the
888          * entry become visible - hence the RCU op:
889          */
890         list_add_tail_rcu(&entry->entry, head);
891
892         return 1;
893 }
894
895 /*
896  * Recursive, forwards-direction lock-dependency checking, used for
897  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
898  * checking.
899  *
900  * (to keep the stackframe of the recursive functions small we
901  *  use these global variables, and we also mark various helper
902  *  functions as noinline.)
903  */
904 static struct held_lock *check_source, *check_target;
905
906 /*
907  * Print a dependency chain entry (this is only done when a deadlock
908  * has been detected):
909  */
910 static noinline int
911 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
912 {
913         if (debug_locks_silent)
914                 return 0;
915         printk("\n-> #%u", depth);
916         print_lock_name(target->class);
917         printk(":\n");
918         print_stack_trace(&target->trace, 6);
919
920         return 0;
921 }
922
923 /*
924  * When a circular dependency is detected, print the
925  * header first:
926  */
927 static noinline int
928 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
929 {
930         struct task_struct *curr = current;
931
932         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
933                 return 0;
934
935         printk("\n=======================================================\n");
936         printk(  "[ INFO: possible circular locking dependency detected ]\n");
937         print_kernel_version();
938         printk(  "-------------------------------------------------------\n");
939         printk("%s/%d is trying to acquire lock:\n",
940                 curr->comm, task_pid_nr(curr));
941         print_lock(check_source);
942         printk("\nbut task is already holding lock:\n");
943         print_lock(check_target);
944         printk("\nwhich lock already depends on the new lock.\n\n");
945         printk("\nthe existing dependency chain (in reverse order) is:\n");
946
947         print_circular_bug_entry(entry, depth);
948
949         return 0;
950 }
951
952 static noinline int print_circular_bug_tail(void)
953 {
954         struct task_struct *curr = current;
955         struct lock_list this;
956
957         if (debug_locks_silent)
958                 return 0;
959
960         this.class = hlock_class(check_source);
961         if (!save_trace(&this.trace))
962                 return 0;
963
964         print_circular_bug_entry(&this, 0);
965
966         printk("\nother info that might help us debug this:\n\n");
967         lockdep_print_held_locks(curr);
968
969         printk("\nstack backtrace:\n");
970         dump_stack();
971
972         return 0;
973 }
974
975 #define RECURSION_LIMIT 40
976
977 static int noinline print_infinite_recursion_bug(void)
978 {
979         if (!debug_locks_off_graph_unlock())
980                 return 0;
981
982         WARN_ON(1);
983
984         return 0;
985 }
986
987 unsigned long __lockdep_count_forward_deps(struct lock_class *class,
988                                            unsigned int depth)
989 {
990         struct lock_list *entry;
991         unsigned long ret = 1;
992
993         if (lockdep_dependency_visit(class, depth))
994                 return 0;
995
996         /*
997          * Recurse this class's dependency list:
998          */
999         list_for_each_entry(entry, &class->locks_after, entry)
1000                 ret += __lockdep_count_forward_deps(entry->class, depth + 1);
1001
1002         return ret;
1003 }
1004
1005 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1006 {
1007         unsigned long ret, flags;
1008
1009         local_irq_save(flags);
1010         __raw_spin_lock(&lockdep_lock);
1011         ret = __lockdep_count_forward_deps(class, 0);
1012         __raw_spin_unlock(&lockdep_lock);
1013         local_irq_restore(flags);
1014
1015         return ret;
1016 }
1017
1018 unsigned long __lockdep_count_backward_deps(struct lock_class *class,
1019                                             unsigned int depth)
1020 {
1021         struct lock_list *entry;
1022         unsigned long ret = 1;
1023
1024         if (lockdep_dependency_visit(class, depth))
1025                 return 0;
1026         /*
1027          * Recurse this class's dependency list:
1028          */
1029         list_for_each_entry(entry, &class->locks_before, entry)
1030                 ret += __lockdep_count_backward_deps(entry->class, depth + 1);
1031
1032         return ret;
1033 }
1034
1035 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1036 {
1037         unsigned long ret, flags;
1038
1039         local_irq_save(flags);
1040         __raw_spin_lock(&lockdep_lock);
1041         ret = __lockdep_count_backward_deps(class, 0);
1042         __raw_spin_unlock(&lockdep_lock);
1043         local_irq_restore(flags);
1044
1045         return ret;
1046 }
1047
1048 /*
1049  * Prove that the dependency graph starting at <entry> can not
1050  * lead to <target>. Print an error and return 0 if it does.
1051  */
1052 static noinline int
1053 check_noncircular(struct lock_class *source, unsigned int depth)
1054 {
1055         struct lock_list *entry;
1056
1057         if (lockdep_dependency_visit(source, depth))
1058                 return 1;
1059
1060         debug_atomic_inc(&nr_cyclic_check_recursions);
1061         if (depth > max_recursion_depth)
1062                 max_recursion_depth = depth;
1063         if (depth >= RECURSION_LIMIT)
1064                 return print_infinite_recursion_bug();
1065         /*
1066          * Check this lock's dependency list:
1067          */
1068         list_for_each_entry(entry, &source->locks_after, entry) {
1069                 if (entry->class == hlock_class(check_target))
1070                         return print_circular_bug_header(entry, depth+1);
1071                 debug_atomic_inc(&nr_cyclic_checks);
1072                 if (!check_noncircular(entry->class, depth+1))
1073                         return print_circular_bug_entry(entry, depth+1);
1074         }
1075         return 1;
1076 }
1077
1078 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1079 /*
1080  * Forwards and backwards subgraph searching, for the purposes of
1081  * proving that two subgraphs can be connected by a new dependency
1082  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1083  */
1084 static enum lock_usage_bit find_usage_bit;
1085 static struct lock_class *forwards_match, *backwards_match;
1086
1087 /*
1088  * Find a node in the forwards-direction dependency sub-graph starting
1089  * at <source> that matches <find_usage_bit>.
1090  *
1091  * Return 2 if such a node exists in the subgraph, and put that node
1092  * into <forwards_match>.
1093  *
1094  * Return 1 otherwise and keep <forwards_match> unchanged.
1095  * Return 0 on error.
1096  */
1097 static noinline int
1098 find_usage_forwards(struct lock_class *source, unsigned int depth)
1099 {
1100         struct lock_list *entry;
1101         int ret;
1102
1103         if (lockdep_dependency_visit(source, depth))
1104                 return 1;
1105
1106         if (depth > max_recursion_depth)
1107                 max_recursion_depth = depth;
1108         if (depth >= RECURSION_LIMIT)
1109                 return print_infinite_recursion_bug();
1110
1111         debug_atomic_inc(&nr_find_usage_forwards_checks);
1112         if (source->usage_mask & (1 << find_usage_bit)) {
1113                 forwards_match = source;
1114                 return 2;
1115         }
1116
1117         /*
1118          * Check this lock's dependency list:
1119          */
1120         list_for_each_entry(entry, &source->locks_after, entry) {
1121                 debug_atomic_inc(&nr_find_usage_forwards_recursions);
1122                 ret = find_usage_forwards(entry->class, depth+1);
1123                 if (ret == 2 || ret == 0)
1124                         return ret;
1125         }
1126         return 1;
1127 }
1128
1129 /*
1130  * Find a node in the backwards-direction dependency sub-graph starting
1131  * at <source> that matches <find_usage_bit>.
1132  *
1133  * Return 2 if such a node exists in the subgraph, and put that node
1134  * into <backwards_match>.
1135  *
1136  * Return 1 otherwise and keep <backwards_match> unchanged.
1137  * Return 0 on error.
1138  */
1139 static noinline int
1140 find_usage_backwards(struct lock_class *source, unsigned int depth)
1141 {
1142         struct lock_list *entry;
1143         int ret;
1144
1145         if (lockdep_dependency_visit(source, depth))
1146                 return 1;
1147
1148         if (!__raw_spin_is_locked(&lockdep_lock))
1149                 return DEBUG_LOCKS_WARN_ON(1);
1150
1151         if (depth > max_recursion_depth)
1152                 max_recursion_depth = depth;
1153         if (depth >= RECURSION_LIMIT)
1154                 return print_infinite_recursion_bug();
1155
1156         debug_atomic_inc(&nr_find_usage_backwards_checks);
1157         if (source->usage_mask & (1 << find_usage_bit)) {
1158                 backwards_match = source;
1159                 return 2;
1160         }
1161
1162         if (!source && debug_locks_off_graph_unlock()) {
1163                 WARN_ON(1);
1164                 return 0;
1165         }
1166
1167         /*
1168          * Check this lock's dependency list:
1169          */
1170         list_for_each_entry(entry, &source->locks_before, entry) {
1171                 debug_atomic_inc(&nr_find_usage_backwards_recursions);
1172                 ret = find_usage_backwards(entry->class, depth+1);
1173                 if (ret == 2 || ret == 0)
1174                         return ret;
1175         }
1176         return 1;
1177 }
1178
1179 static int
1180 print_bad_irq_dependency(struct task_struct *curr,
1181                          struct held_lock *prev,
1182                          struct held_lock *next,
1183                          enum lock_usage_bit bit1,
1184                          enum lock_usage_bit bit2,
1185                          const char *irqclass)
1186 {
1187         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1188                 return 0;
1189
1190         printk("\n======================================================\n");
1191         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1192                 irqclass, irqclass);
1193         print_kernel_version();
1194         printk(  "------------------------------------------------------\n");
1195         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1196                 curr->comm, task_pid_nr(curr),
1197                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1198                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1199                 curr->hardirqs_enabled,
1200                 curr->softirqs_enabled);
1201         print_lock(next);
1202
1203         printk("\nand this task is already holding:\n");
1204         print_lock(prev);
1205         printk("which would create a new lock dependency:\n");
1206         print_lock_name(hlock_class(prev));
1207         printk(" ->");
1208         print_lock_name(hlock_class(next));
1209         printk("\n");
1210
1211         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1212                 irqclass);
1213         print_lock_name(backwards_match);
1214         printk("\n... which became %s-irq-safe at:\n", irqclass);
1215
1216         print_stack_trace(backwards_match->usage_traces + bit1, 1);
1217
1218         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1219         print_lock_name(forwards_match);
1220         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1221         printk("...");
1222
1223         print_stack_trace(forwards_match->usage_traces + bit2, 1);
1224
1225         printk("\nother info that might help us debug this:\n\n");
1226         lockdep_print_held_locks(curr);
1227
1228         printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
1229         print_lock_dependencies(backwards_match, 0);
1230
1231         printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
1232         print_lock_dependencies(forwards_match, 0);
1233
1234         printk("\nstack backtrace:\n");
1235         dump_stack();
1236
1237         return 0;
1238 }
1239
1240 static int
1241 check_usage(struct task_struct *curr, struct held_lock *prev,
1242             struct held_lock *next, enum lock_usage_bit bit_backwards,
1243             enum lock_usage_bit bit_forwards, const char *irqclass)
1244 {
1245         int ret;
1246
1247         find_usage_bit = bit_backwards;
1248         /* fills in <backwards_match> */
1249         ret = find_usage_backwards(hlock_class(prev), 0);
1250         if (!ret || ret == 1)
1251                 return ret;
1252
1253         find_usage_bit = bit_forwards;
1254         ret = find_usage_forwards(hlock_class(next), 0);
1255         if (!ret || ret == 1)
1256                 return ret;
1257         /* ret == 2 */
1258         return print_bad_irq_dependency(curr, prev, next,
1259                         bit_backwards, bit_forwards, irqclass);
1260 }
1261
1262 static int
1263 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1264                 struct held_lock *next)
1265 {
1266         /*
1267          * Prove that the new dependency does not connect a hardirq-safe
1268          * lock with a hardirq-unsafe lock - to achieve this we search
1269          * the backwards-subgraph starting at <prev>, and the
1270          * forwards-subgraph starting at <next>:
1271          */
1272         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
1273                                         LOCK_ENABLED_HARDIRQS, "hard"))
1274                 return 0;
1275
1276         /*
1277          * Prove that the new dependency does not connect a hardirq-safe-read
1278          * lock with a hardirq-unsafe lock - to achieve this we search
1279          * the backwards-subgraph starting at <prev>, and the
1280          * forwards-subgraph starting at <next>:
1281          */
1282         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
1283                                         LOCK_ENABLED_HARDIRQS, "hard-read"))
1284                 return 0;
1285
1286         /*
1287          * Prove that the new dependency does not connect a softirq-safe
1288          * lock with a softirq-unsafe lock - to achieve this we search
1289          * the backwards-subgraph starting at <prev>, and the
1290          * forwards-subgraph starting at <next>:
1291          */
1292         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
1293                                         LOCK_ENABLED_SOFTIRQS, "soft"))
1294                 return 0;
1295         /*
1296          * Prove that the new dependency does not connect a softirq-safe-read
1297          * lock with a softirq-unsafe lock - to achieve this we search
1298          * the backwards-subgraph starting at <prev>, and the
1299          * forwards-subgraph starting at <next>:
1300          */
1301         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
1302                                         LOCK_ENABLED_SOFTIRQS, "soft"))
1303                 return 0;
1304
1305         return 1;
1306 }
1307
1308 static void inc_chains(void)
1309 {
1310         if (current->hardirq_context)
1311                 nr_hardirq_chains++;
1312         else {
1313                 if (current->softirq_context)
1314                         nr_softirq_chains++;
1315                 else
1316                         nr_process_chains++;
1317         }
1318 }
1319
1320 #else
1321
1322 static inline int
1323 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1324                 struct held_lock *next)
1325 {
1326         return 1;
1327 }
1328
1329 static inline void inc_chains(void)
1330 {
1331         nr_process_chains++;
1332 }
1333
1334 #endif
1335
1336 static int
1337 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1338                    struct held_lock *next)
1339 {
1340         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1341                 return 0;
1342
1343         printk("\n=============================================\n");
1344         printk(  "[ INFO: possible recursive locking detected ]\n");
1345         print_kernel_version();
1346         printk(  "---------------------------------------------\n");
1347         printk("%s/%d is trying to acquire lock:\n",
1348                 curr->comm, task_pid_nr(curr));
1349         print_lock(next);
1350         printk("\nbut task is already holding lock:\n");
1351         print_lock(prev);
1352
1353         printk("\nother info that might help us debug this:\n");
1354         lockdep_print_held_locks(curr);
1355
1356         printk("\nstack backtrace:\n");
1357         dump_stack();
1358
1359         return 0;
1360 }
1361
1362 /*
1363  * Check whether we are holding such a class already.
1364  *
1365  * (Note that this has to be done separately, because the graph cannot
1366  * detect such classes of deadlocks.)
1367  *
1368  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1369  */
1370 static int
1371 check_deadlock(struct task_struct *curr, struct held_lock *next,
1372                struct lockdep_map *next_instance, int read)
1373 {
1374         struct held_lock *prev;
1375         struct held_lock *nest = NULL;
1376         int i;
1377
1378         for (i = 0; i < curr->lockdep_depth; i++) {
1379                 prev = curr->held_locks + i;
1380
1381                 if (prev->instance == next->nest_lock)
1382                         nest = prev;
1383
1384                 if (hlock_class(prev) != hlock_class(next))
1385                         continue;
1386
1387                 /*
1388                  * Allow read-after-read recursion of the same
1389                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1390                  */
1391                 if ((read == 2) && prev->read)
1392                         return 2;
1393
1394                 /*
1395                  * We're holding the nest_lock, which serializes this lock's
1396                  * nesting behaviour.
1397                  */
1398                 if (nest)
1399                         return 2;
1400
1401                 return print_deadlock_bug(curr, prev, next);
1402         }
1403         return 1;
1404 }
1405
1406 /*
1407  * There was a chain-cache miss, and we are about to add a new dependency
1408  * to a previous lock. We recursively validate the following rules:
1409  *
1410  *  - would the adding of the <prev> -> <next> dependency create a
1411  *    circular dependency in the graph? [== circular deadlock]
1412  *
1413  *  - does the new prev->next dependency connect any hardirq-safe lock
1414  *    (in the full backwards-subgraph starting at <prev>) with any
1415  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1416  *    <next>)? [== illegal lock inversion with hardirq contexts]
1417  *
1418  *  - does the new prev->next dependency connect any softirq-safe lock
1419  *    (in the full backwards-subgraph starting at <prev>) with any
1420  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1421  *    <next>)? [== illegal lock inversion with softirq contexts]
1422  *
1423  * any of these scenarios could lead to a deadlock.
1424  *
1425  * Then if all the validations pass, we add the forwards and backwards
1426  * dependency.
1427  */
1428 static int
1429 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1430                struct held_lock *next, int distance)
1431 {
1432         struct lock_list *entry;
1433         int ret;
1434
1435         /*
1436          * Prove that the new <prev> -> <next> dependency would not
1437          * create a circular dependency in the graph. (We do this by
1438          * forward-recursing into the graph starting at <next>, and
1439          * checking whether we can reach <prev>.)
1440          *
1441          * We are using global variables to control the recursion, to
1442          * keep the stackframe size of the recursive functions low:
1443          */
1444         check_source = next;
1445         check_target = prev;
1446         if (!(check_noncircular(hlock_class(next), 0)))
1447                 return print_circular_bug_tail();
1448
1449         if (!check_prev_add_irq(curr, prev, next))
1450                 return 0;
1451
1452         /*
1453          * For recursive read-locks we do all the dependency checks,
1454          * but we dont store read-triggered dependencies (only
1455          * write-triggered dependencies). This ensures that only the
1456          * write-side dependencies matter, and that if for example a
1457          * write-lock never takes any other locks, then the reads are
1458          * equivalent to a NOP.
1459          */
1460         if (next->read == 2 || prev->read == 2)
1461                 return 1;
1462         /*
1463          * Is the <prev> -> <next> dependency already present?
1464          *
1465          * (this may occur even though this is a new chain: consider
1466          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1467          *  chains - the second one will be new, but L1 already has
1468          *  L2 added to its dependency list, due to the first chain.)
1469          */
1470         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1471                 if (entry->class == hlock_class(next)) {
1472                         if (distance == 1)
1473                                 entry->distance = 1;
1474                         return 2;
1475                 }
1476         }
1477
1478         /*
1479          * Ok, all validations passed, add the new lock
1480          * to the previous lock's dependency list:
1481          */
1482         ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1483                                &hlock_class(prev)->locks_after,
1484                                next->acquire_ip, distance);
1485
1486         if (!ret)
1487                 return 0;
1488
1489         ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1490                                &hlock_class(next)->locks_before,
1491                                next->acquire_ip, distance);
1492         if (!ret)
1493                 return 0;
1494
1495         /*
1496          * Debugging printouts:
1497          */
1498         if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1499                 graph_unlock();
1500                 printk("\n new dependency: ");
1501                 print_lock_name(hlock_class(prev));
1502                 printk(" => ");
1503                 print_lock_name(hlock_class(next));
1504                 printk("\n");
1505                 dump_stack();
1506                 return graph_lock();
1507         }
1508         return 1;
1509 }
1510
1511 /*
1512  * Add the dependency to all directly-previous locks that are 'relevant'.
1513  * The ones that are relevant are (in increasing distance from curr):
1514  * all consecutive trylock entries and the final non-trylock entry - or
1515  * the end of this context's lock-chain - whichever comes first.
1516  */
1517 static int
1518 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1519 {
1520         int depth = curr->lockdep_depth;
1521         struct held_lock *hlock;
1522
1523         /*
1524          * Debugging checks.
1525          *
1526          * Depth must not be zero for a non-head lock:
1527          */
1528         if (!depth)
1529                 goto out_bug;
1530         /*
1531          * At least two relevant locks must exist for this
1532          * to be a head:
1533          */
1534         if (curr->held_locks[depth].irq_context !=
1535                         curr->held_locks[depth-1].irq_context)
1536                 goto out_bug;
1537
1538         for (;;) {
1539                 int distance = curr->lockdep_depth - depth + 1;
1540                 hlock = curr->held_locks + depth-1;
1541                 /*
1542                  * Only non-recursive-read entries get new dependencies
1543                  * added:
1544                  */
1545                 if (hlock->read != 2) {
1546                         if (!check_prev_add(curr, hlock, next, distance))
1547                                 return 0;
1548                         /*
1549                          * Stop after the first non-trylock entry,
1550                          * as non-trylock entries have added their
1551                          * own direct dependencies already, so this
1552                          * lock is connected to them indirectly:
1553                          */
1554                         if (!hlock->trylock)
1555                                 break;
1556                 }
1557                 depth--;
1558                 /*
1559                  * End of lock-stack?
1560                  */
1561                 if (!depth)
1562                         break;
1563                 /*
1564                  * Stop the search if we cross into another context:
1565                  */
1566                 if (curr->held_locks[depth].irq_context !=
1567                                 curr->held_locks[depth-1].irq_context)
1568                         break;
1569         }
1570         return 1;
1571 out_bug:
1572         if (!debug_locks_off_graph_unlock())
1573                 return 0;
1574
1575         WARN_ON(1);
1576
1577         return 0;
1578 }
1579
1580 unsigned long nr_lock_chains;
1581 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1582 int nr_chain_hlocks;
1583 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1584
1585 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1586 {
1587         return lock_classes + chain_hlocks[chain->base + i];
1588 }
1589
1590 /*
1591  * Look up a dependency chain. If the key is not present yet then
1592  * add it and return 1 - in this case the new dependency chain is
1593  * validated. If the key is already hashed, return 0.
1594  * (On return with 1 graph_lock is held.)
1595  */
1596 static inline int lookup_chain_cache(struct task_struct *curr,
1597                                      struct held_lock *hlock,
1598                                      u64 chain_key)
1599 {
1600         struct lock_class *class = hlock_class(hlock);
1601         struct list_head *hash_head = chainhashentry(chain_key);
1602         struct lock_chain *chain;
1603         struct held_lock *hlock_curr, *hlock_next;
1604         int i, j, n, cn;
1605
1606         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1607                 return 0;
1608         /*
1609          * We can walk it lock-free, because entries only get added
1610          * to the hash:
1611          */
1612         list_for_each_entry(chain, hash_head, entry) {
1613                 if (chain->chain_key == chain_key) {
1614 cache_hit:
1615                         debug_atomic_inc(&chain_lookup_hits);
1616                         if (very_verbose(class))
1617                                 printk("\nhash chain already cached, key: "
1618                                         "%016Lx tail class: [%p] %s\n",
1619                                         (unsigned long long)chain_key,
1620                                         class->key, class->name);
1621                         return 0;
1622                 }
1623         }
1624         if (very_verbose(class))
1625                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1626                         (unsigned long long)chain_key, class->key, class->name);
1627         /*
1628          * Allocate a new chain entry from the static array, and add
1629          * it to the hash:
1630          */
1631         if (!graph_lock())
1632                 return 0;
1633         /*
1634          * We have to walk the chain again locked - to avoid duplicates:
1635          */
1636         list_for_each_entry(chain, hash_head, entry) {
1637                 if (chain->chain_key == chain_key) {
1638                         graph_unlock();
1639                         goto cache_hit;
1640                 }
1641         }
1642         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1643                 if (!debug_locks_off_graph_unlock())
1644                         return 0;
1645
1646                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1647                 printk("turning off the locking correctness validator.\n");
1648                 return 0;
1649         }
1650         chain = lock_chains + nr_lock_chains++;
1651         chain->chain_key = chain_key;
1652         chain->irq_context = hlock->irq_context;
1653         /* Find the first held_lock of current chain */
1654         hlock_next = hlock;
1655         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1656                 hlock_curr = curr->held_locks + i;
1657                 if (hlock_curr->irq_context != hlock_next->irq_context)
1658                         break;
1659                 hlock_next = hlock;
1660         }
1661         i++;
1662         chain->depth = curr->lockdep_depth + 1 - i;
1663         cn = nr_chain_hlocks;
1664         while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1665                 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1666                 if (n == cn)
1667                         break;
1668                 cn = n;
1669         }
1670         if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1671                 chain->base = cn;
1672                 for (j = 0; j < chain->depth - 1; j++, i++) {
1673                         int lock_id = curr->held_locks[i].class_idx - 1;
1674                         chain_hlocks[chain->base + j] = lock_id;
1675                 }
1676                 chain_hlocks[chain->base + j] = class - lock_classes;
1677         }
1678         list_add_tail_rcu(&chain->entry, hash_head);
1679         debug_atomic_inc(&chain_lookup_misses);
1680         inc_chains();
1681
1682         return 1;
1683 }
1684
1685 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1686                 struct held_lock *hlock, int chain_head, u64 chain_key)
1687 {
1688         /*
1689          * Trylock needs to maintain the stack of held locks, but it
1690          * does not add new dependencies, because trylock can be done
1691          * in any order.
1692          *
1693          * We look up the chain_key and do the O(N^2) check and update of
1694          * the dependencies only if this is a new dependency chain.
1695          * (If lookup_chain_cache() returns with 1 it acquires
1696          * graph_lock for us)
1697          */
1698         if (!hlock->trylock && (hlock->check == 2) &&
1699             lookup_chain_cache(curr, hlock, chain_key)) {
1700                 /*
1701                  * Check whether last held lock:
1702                  *
1703                  * - is irq-safe, if this lock is irq-unsafe
1704                  * - is softirq-safe, if this lock is hardirq-unsafe
1705                  *
1706                  * And check whether the new lock's dependency graph
1707                  * could lead back to the previous lock.
1708                  *
1709                  * any of these scenarios could lead to a deadlock. If
1710                  * All validations
1711                  */
1712                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
1713
1714                 if (!ret)
1715                         return 0;
1716                 /*
1717                  * Mark recursive read, as we jump over it when
1718                  * building dependencies (just like we jump over
1719                  * trylock entries):
1720                  */
1721                 if (ret == 2)
1722                         hlock->read = 2;
1723                 /*
1724                  * Add dependency only if this lock is not the head
1725                  * of the chain, and if it's not a secondary read-lock:
1726                  */
1727                 if (!chain_head && ret != 2)
1728                         if (!check_prevs_add(curr, hlock))
1729                                 return 0;
1730                 graph_unlock();
1731         } else
1732                 /* after lookup_chain_cache(): */
1733                 if (unlikely(!debug_locks))
1734                         return 0;
1735
1736         return 1;
1737 }
1738 #else
1739 static inline int validate_chain(struct task_struct *curr,
1740                 struct lockdep_map *lock, struct held_lock *hlock,
1741                 int chain_head, u64 chain_key)
1742 {
1743         return 1;
1744 }
1745 #endif
1746
1747 /*
1748  * We are building curr_chain_key incrementally, so double-check
1749  * it from scratch, to make sure that it's done correctly:
1750  */
1751 static void check_chain_key(struct task_struct *curr)
1752 {
1753 #ifdef CONFIG_DEBUG_LOCKDEP
1754         struct held_lock *hlock, *prev_hlock = NULL;
1755         unsigned int i, id;
1756         u64 chain_key = 0;
1757
1758         for (i = 0; i < curr->lockdep_depth; i++) {
1759                 hlock = curr->held_locks + i;
1760                 if (chain_key != hlock->prev_chain_key) {
1761                         debug_locks_off();
1762                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1763                                 curr->lockdep_depth, i,
1764                                 (unsigned long long)chain_key,
1765                                 (unsigned long long)hlock->prev_chain_key);
1766                         return;
1767                 }
1768                 id = hlock->class_idx - 1;
1769                 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1770                         return;
1771
1772                 if (prev_hlock && (prev_hlock->irq_context !=
1773                                                         hlock->irq_context))
1774                         chain_key = 0;
1775                 chain_key = iterate_chain_key(chain_key, id);
1776                 prev_hlock = hlock;
1777         }
1778         if (chain_key != curr->curr_chain_key) {
1779                 debug_locks_off();
1780                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1781                         curr->lockdep_depth, i,
1782                         (unsigned long long)chain_key,
1783                         (unsigned long long)curr->curr_chain_key);
1784         }
1785 #endif
1786 }
1787
1788 static int
1789 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1790                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1791 {
1792         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1793                 return 0;
1794
1795         printk("\n=================================\n");
1796         printk(  "[ INFO: inconsistent lock state ]\n");
1797         print_kernel_version();
1798         printk(  "---------------------------------\n");
1799
1800         printk("inconsistent {%s} -> {%s} usage.\n",
1801                 usage_str[prev_bit], usage_str[new_bit]);
1802
1803         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1804                 curr->comm, task_pid_nr(curr),
1805                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1806                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1807                 trace_hardirqs_enabled(curr),
1808                 trace_softirqs_enabled(curr));
1809         print_lock(this);
1810
1811         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1812         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
1813
1814         print_irqtrace_events(curr);
1815         printk("\nother info that might help us debug this:\n");
1816         lockdep_print_held_locks(curr);
1817
1818         printk("\nstack backtrace:\n");
1819         dump_stack();
1820
1821         return 0;
1822 }
1823
1824 /*
1825  * Print out an error if an invalid bit is set:
1826  */
1827 static inline int
1828 valid_state(struct task_struct *curr, struct held_lock *this,
1829             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1830 {
1831         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
1832                 return print_usage_bug(curr, this, bad_bit, new_bit);
1833         return 1;
1834 }
1835
1836 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1837                      enum lock_usage_bit new_bit);
1838
1839 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1840
1841 /*
1842  * print irq inversion bug:
1843  */
1844 static int
1845 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1846                         struct held_lock *this, int forwards,
1847                         const char *irqclass)
1848 {
1849         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1850                 return 0;
1851
1852         printk("\n=========================================================\n");
1853         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
1854         print_kernel_version();
1855         printk(  "---------------------------------------------------------\n");
1856         printk("%s/%d just changed the state of lock:\n",
1857                 curr->comm, task_pid_nr(curr));
1858         print_lock(this);
1859         if (forwards)
1860                 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1861         else
1862                 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1863         print_lock_name(other);
1864         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1865
1866         printk("\nother info that might help us debug this:\n");
1867         lockdep_print_held_locks(curr);
1868
1869         printk("\nthe first lock's dependencies:\n");
1870         print_lock_dependencies(hlock_class(this), 0);
1871
1872         printk("\nthe second lock's dependencies:\n");
1873         print_lock_dependencies(other, 0);
1874
1875         printk("\nstack backtrace:\n");
1876         dump_stack();
1877
1878         return 0;
1879 }
1880
1881 /*
1882  * Prove that in the forwards-direction subgraph starting at <this>
1883  * there is no lock matching <mask>:
1884  */
1885 static int
1886 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1887                      enum lock_usage_bit bit, const char *irqclass)
1888 {
1889         int ret;
1890
1891         find_usage_bit = bit;
1892         /* fills in <forwards_match> */
1893         ret = find_usage_forwards(hlock_class(this), 0);
1894         if (!ret || ret == 1)
1895                 return ret;
1896
1897         return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1898 }
1899
1900 /*
1901  * Prove that in the backwards-direction subgraph starting at <this>
1902  * there is no lock matching <mask>:
1903  */
1904 static int
1905 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1906                       enum lock_usage_bit bit, const char *irqclass)
1907 {
1908         int ret;
1909
1910         find_usage_bit = bit;
1911         /* fills in <backwards_match> */
1912         ret = find_usage_backwards(hlock_class(this), 0);
1913         if (!ret || ret == 1)
1914                 return ret;
1915
1916         return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1917 }
1918
1919 void print_irqtrace_events(struct task_struct *curr)
1920 {
1921         printk("irq event stamp: %u\n", curr->irq_events);
1922         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
1923         print_ip_sym(curr->hardirq_enable_ip);
1924         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1925         print_ip_sym(curr->hardirq_disable_ip);
1926         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
1927         print_ip_sym(curr->softirq_enable_ip);
1928         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1929         print_ip_sym(curr->softirq_disable_ip);
1930 }
1931
1932 static int hardirq_verbose(struct lock_class *class)
1933 {
1934 #if HARDIRQ_VERBOSE
1935         return class_filter(class);
1936 #endif
1937         return 0;
1938 }
1939
1940 static int softirq_verbose(struct lock_class *class)
1941 {
1942 #if SOFTIRQ_VERBOSE
1943         return class_filter(class);
1944 #endif
1945         return 0;
1946 }
1947
1948 #define STRICT_READ_CHECKS      1
1949
1950 static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
1951                 enum lock_usage_bit new_bit)
1952 {
1953         int ret = 1;
1954
1955         switch(new_bit) {
1956         case LOCK_USED_IN_HARDIRQ:
1957                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1958                         return 0;
1959                 if (!valid_state(curr, this, new_bit,
1960                                  LOCK_ENABLED_HARDIRQS_READ))
1961                         return 0;
1962                 /*
1963                  * just marked it hardirq-safe, check that this lock
1964                  * took no hardirq-unsafe lock in the past:
1965                  */
1966                 if (!check_usage_forwards(curr, this,
1967                                           LOCK_ENABLED_HARDIRQS, "hard"))
1968                         return 0;
1969 #if STRICT_READ_CHECKS
1970                 /*
1971                  * just marked it hardirq-safe, check that this lock
1972                  * took no hardirq-unsafe-read lock in the past:
1973                  */
1974                 if (!check_usage_forwards(curr, this,
1975                                 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1976                         return 0;
1977 #endif
1978                 if (hardirq_verbose(hlock_class(this)))
1979                         ret = 2;
1980                 break;
1981         case LOCK_USED_IN_SOFTIRQ:
1982                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1983                         return 0;
1984                 if (!valid_state(curr, this, new_bit,
1985                                  LOCK_ENABLED_SOFTIRQS_READ))
1986                         return 0;
1987                 /*
1988                  * just marked it softirq-safe, check that this lock
1989                  * took no softirq-unsafe lock in the past:
1990                  */
1991                 if (!check_usage_forwards(curr, this,
1992                                           LOCK_ENABLED_SOFTIRQS, "soft"))
1993                         return 0;
1994 #if STRICT_READ_CHECKS
1995                 /*
1996                  * just marked it softirq-safe, check that this lock
1997                  * took no softirq-unsafe-read lock in the past:
1998                  */
1999                 if (!check_usage_forwards(curr, this,
2000                                 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
2001                         return 0;
2002 #endif
2003                 if (softirq_verbose(hlock_class(this)))
2004                         ret = 2;
2005                 break;
2006         case LOCK_USED_IN_HARDIRQ_READ:
2007                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
2008                         return 0;
2009                 /*
2010                  * just marked it hardirq-read-safe, check that this lock
2011                  * took no hardirq-unsafe lock in the past:
2012                  */
2013                 if (!check_usage_forwards(curr, this,
2014                                           LOCK_ENABLED_HARDIRQS, "hard"))
2015                         return 0;
2016                 if (hardirq_verbose(hlock_class(this)))
2017                         ret = 2;
2018                 break;
2019         case LOCK_USED_IN_SOFTIRQ_READ:
2020                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
2021                         return 0;
2022                 /*
2023                  * just marked it softirq-read-safe, check that this lock
2024                  * took no softirq-unsafe lock in the past:
2025                  */
2026                 if (!check_usage_forwards(curr, this,
2027                                           LOCK_ENABLED_SOFTIRQS, "soft"))
2028                         return 0;
2029                 if (softirq_verbose(hlock_class(this)))
2030                         ret = 2;
2031                 break;
2032         case LOCK_ENABLED_HARDIRQS:
2033                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
2034                         return 0;
2035                 if (!valid_state(curr, this, new_bit,
2036                                  LOCK_USED_IN_HARDIRQ_READ))
2037                         return 0;
2038                 /*
2039                  * just marked it hardirq-unsafe, check that no hardirq-safe
2040                  * lock in the system ever took it in the past:
2041                  */
2042                 if (!check_usage_backwards(curr, this,
2043                                            LOCK_USED_IN_HARDIRQ, "hard"))
2044                         return 0;
2045 #if STRICT_READ_CHECKS
2046                 /*
2047                  * just marked it hardirq-unsafe, check that no
2048                  * hardirq-safe-read lock in the system ever took
2049                  * it in the past:
2050                  */
2051                 if (!check_usage_backwards(curr, this,
2052                                    LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
2053                         return 0;
2054 #endif
2055                 if (hardirq_verbose(hlock_class(this)))
2056                         ret = 2;
2057                 break;
2058         case LOCK_ENABLED_SOFTIRQS:
2059                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
2060                         return 0;
2061                 if (!valid_state(curr, this, new_bit,
2062                                  LOCK_USED_IN_SOFTIRQ_READ))
2063                         return 0;
2064                 /*
2065                  * just marked it softirq-unsafe, check that no softirq-safe
2066                  * lock in the system ever took it in the past:
2067                  */
2068                 if (!check_usage_backwards(curr, this,
2069                                            LOCK_USED_IN_SOFTIRQ, "soft"))
2070                         return 0;
2071 #if STRICT_READ_CHECKS
2072                 /*
2073                  * just marked it softirq-unsafe, check that no
2074                  * softirq-safe-read lock in the system ever took
2075                  * it in the past:
2076                  */
2077                 if (!check_usage_backwards(curr, this,
2078                                    LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
2079                         return 0;
2080 #endif
2081                 if (softirq_verbose(hlock_class(this)))
2082                         ret = 2;
2083                 break;
2084         case LOCK_ENABLED_HARDIRQS_READ:
2085                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
2086                         return 0;
2087 #if STRICT_READ_CHECKS
2088                 /*
2089                  * just marked it hardirq-read-unsafe, check that no
2090                  * hardirq-safe lock in the system ever took it in the past:
2091                  */
2092                 if (!check_usage_backwards(curr, this,
2093                                            LOCK_USED_IN_HARDIRQ, "hard"))
2094                         return 0;
2095 #endif
2096                 if (hardirq_verbose(hlock_class(this)))
2097                         ret = 2;
2098                 break;
2099         case LOCK_ENABLED_SOFTIRQS_READ:
2100                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
2101                         return 0;
2102 #if STRICT_READ_CHECKS
2103                 /*
2104                  * just marked it softirq-read-unsafe, check that no
2105                  * softirq-safe lock in the system ever took it in the past:
2106                  */
2107                 if (!check_usage_backwards(curr, this,
2108                                            LOCK_USED_IN_SOFTIRQ, "soft"))
2109                         return 0;
2110 #endif
2111                 if (softirq_verbose(hlock_class(this)))
2112                         ret = 2;
2113                 break;
2114         default:
2115                 WARN_ON(1);
2116                 break;
2117         }
2118
2119         return ret;
2120 }
2121
2122 /*
2123  * Mark all held locks with a usage bit:
2124  */
2125 static int
2126 mark_held_locks(struct task_struct *curr, int hardirq)
2127 {
2128         enum lock_usage_bit usage_bit;
2129         struct held_lock *hlock;
2130         int i;
2131
2132         for (i = 0; i < curr->lockdep_depth; i++) {
2133                 hlock = curr->held_locks + i;
2134
2135                 if (hardirq) {
2136                         if (hlock->read)
2137                                 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
2138                         else
2139                                 usage_bit = LOCK_ENABLED_HARDIRQS;
2140                 } else {
2141                         if (hlock->read)
2142                                 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
2143                         else
2144                                 usage_bit = LOCK_ENABLED_SOFTIRQS;
2145                 }
2146                 if (!mark_lock(curr, hlock, usage_bit))
2147                         return 0;
2148         }
2149
2150         return 1;
2151 }
2152
2153 /*
2154  * Debugging helper: via this flag we know that we are in
2155  * 'early bootup code', and will warn about any invalid irqs-on event:
2156  */
2157 static int early_boot_irqs_enabled;
2158
2159 void early_boot_irqs_off(void)
2160 {
2161         early_boot_irqs_enabled = 0;
2162 }
2163
2164 void early_boot_irqs_on(void)
2165 {
2166         early_boot_irqs_enabled = 1;
2167 }
2168
2169 /*
2170  * Hardirqs will be enabled:
2171  */
2172 void trace_hardirqs_on_caller(unsigned long ip)
2173 {
2174         struct task_struct *curr = current;
2175
2176         time_hardirqs_on(CALLER_ADDR0, ip);
2177
2178         if (unlikely(!debug_locks || current->lockdep_recursion))
2179                 return;
2180
2181         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2182                 return;
2183
2184         if (unlikely(curr->hardirqs_enabled)) {
2185                 debug_atomic_inc(&redundant_hardirqs_on);
2186                 return;
2187         }
2188         /* we'll do an OFF -> ON transition: */
2189         curr->hardirqs_enabled = 1;
2190
2191         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2192                 return;
2193         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2194                 return;
2195         /*
2196          * We are going to turn hardirqs on, so set the
2197          * usage bit for all held locks:
2198          */
2199         if (!mark_held_locks(curr, 1))
2200                 return;
2201         /*
2202          * If we have softirqs enabled, then set the usage
2203          * bit for all held locks. (disabled hardirqs prevented
2204          * this bit from being set before)
2205          */
2206         if (curr->softirqs_enabled)
2207                 if (!mark_held_locks(curr, 0))
2208                         return;
2209
2210         curr->hardirq_enable_ip = ip;
2211         curr->hardirq_enable_event = ++curr->irq_events;
2212         debug_atomic_inc(&hardirqs_on_events);
2213 }
2214 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2215
2216 void trace_hardirqs_on(void)
2217 {
2218         trace_hardirqs_on_caller(CALLER_ADDR0);
2219 }
2220 EXPORT_SYMBOL(trace_hardirqs_on);
2221
2222 /*
2223  * Hardirqs were disabled:
2224  */
2225 void trace_hardirqs_off_caller(unsigned long ip)
2226 {
2227         struct task_struct *curr = current;
2228
2229         time_hardirqs_off(CALLER_ADDR0, ip);
2230
2231         if (unlikely(!debug_locks || current->lockdep_recursion))
2232                 return;
2233
2234         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2235                 return;
2236
2237         if (curr->hardirqs_enabled) {
2238                 /*
2239                  * We have done an ON -> OFF transition:
2240                  */
2241                 curr->hardirqs_enabled = 0;
2242                 curr->hardirq_disable_ip = ip;
2243                 curr->hardirq_disable_event = ++curr->irq_events;
2244                 debug_atomic_inc(&hardirqs_off_events);
2245         } else
2246                 debug_atomic_inc(&redundant_hardirqs_off);
2247 }
2248 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2249
2250 void trace_hardirqs_off(void)
2251 {
2252         trace_hardirqs_off_caller(CALLER_ADDR0);
2253 }
2254 EXPORT_SYMBOL(trace_hardirqs_off);
2255
2256 /*
2257  * Softirqs will be enabled:
2258  */
2259 void trace_softirqs_on(unsigned long ip)
2260 {
2261         struct task_struct *curr = current;
2262
2263         if (unlikely(!debug_locks))
2264                 return;
2265
2266         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2267                 return;
2268
2269         if (curr->softirqs_enabled) {
2270                 debug_atomic_inc(&redundant_softirqs_on);
2271                 return;
2272         }
2273
2274         /*
2275          * We'll do an OFF -> ON transition:
2276          */
2277         curr->softirqs_enabled = 1;
2278         curr->softirq_enable_ip = ip;
2279         curr->softirq_enable_event = ++curr->irq_events;
2280         debug_atomic_inc(&softirqs_on_events);
2281         /*
2282          * We are going to turn softirqs on, so set the
2283          * usage bit for all held locks, if hardirqs are
2284          * enabled too:
2285          */
2286         if (curr->hardirqs_enabled)
2287                 mark_held_locks(curr, 0);
2288 }
2289
2290 /*
2291  * Softirqs were disabled:
2292  */
2293 void trace_softirqs_off(unsigned long ip)
2294 {
2295         struct task_struct *curr = current;
2296
2297         if (unlikely(!debug_locks))
2298                 return;
2299
2300         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2301                 return;
2302
2303         if (curr->softirqs_enabled) {
2304                 /*
2305                  * We have done an ON -> OFF transition:
2306                  */
2307                 curr->softirqs_enabled = 0;
2308                 curr->softirq_disable_ip = ip;
2309                 curr->softirq_disable_event = ++curr->irq_events;
2310                 debug_atomic_inc(&softirqs_off_events);
2311                 DEBUG_LOCKS_WARN_ON(!softirq_count());
2312         } else
2313                 debug_atomic_inc(&redundant_softirqs_off);
2314 }
2315
2316 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2317 {
2318         /*
2319          * If non-trylock use in a hardirq or softirq context, then
2320          * mark the lock as used in these contexts:
2321          */
2322         if (!hlock->trylock) {
2323                 if (hlock->read) {
2324                         if (curr->hardirq_context)
2325                                 if (!mark_lock(curr, hlock,
2326                                                 LOCK_USED_IN_HARDIRQ_READ))
2327                                         return 0;
2328                         if (curr->softirq_context)
2329                                 if (!mark_lock(curr, hlock,
2330                                                 LOCK_USED_IN_SOFTIRQ_READ))
2331                                         return 0;
2332                 } else {
2333                         if (curr->hardirq_context)
2334                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2335                                         return 0;
2336                         if (curr->softirq_context)
2337                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2338                                         return 0;
2339                 }
2340         }
2341         if (!hlock->hardirqs_off) {
2342                 if (hlock->read) {
2343                         if (!mark_lock(curr, hlock,
2344                                         LOCK_ENABLED_HARDIRQS_READ))
2345                                 return 0;
2346                         if (curr->softirqs_enabled)
2347                                 if (!mark_lock(curr, hlock,
2348                                                 LOCK_ENABLED_SOFTIRQS_READ))
2349                                         return 0;
2350                 } else {
2351                         if (!mark_lock(curr, hlock,
2352                                         LOCK_ENABLED_HARDIRQS))
2353                                 return 0;
2354                         if (curr->softirqs_enabled)
2355                                 if (!mark_lock(curr, hlock,
2356                                                 LOCK_ENABLED_SOFTIRQS))
2357                                         return 0;
2358                 }
2359         }
2360
2361         return 1;
2362 }
2363
2364 static int separate_irq_context(struct task_struct *curr,
2365                 struct held_lock *hlock)
2366 {
2367         unsigned int depth = curr->lockdep_depth;
2368
2369         /*
2370          * Keep track of points where we cross into an interrupt context:
2371          */
2372         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2373                                 curr->softirq_context;
2374         if (depth) {
2375                 struct held_lock *prev_hlock;
2376
2377                 prev_hlock = curr->held_locks + depth-1;
2378                 /*
2379                  * If we cross into another context, reset the
2380                  * hash key (this also prevents the checking and the
2381                  * adding of the dependency to 'prev'):
2382                  */
2383                 if (prev_hlock->irq_context != hlock->irq_context)
2384                         return 1;
2385         }
2386         return 0;
2387 }
2388
2389 #else
2390
2391 static inline
2392 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2393                 enum lock_usage_bit new_bit)
2394 {
2395         WARN_ON(1);
2396         return 1;
2397 }
2398
2399 static inline int mark_irqflags(struct task_struct *curr,
2400                 struct held_lock *hlock)
2401 {
2402         return 1;
2403 }
2404
2405 static inline int separate_irq_context(struct task_struct *curr,
2406                 struct held_lock *hlock)
2407 {
2408         return 0;
2409 }
2410
2411 #endif
2412
2413 /*
2414  * Mark a lock with a usage bit, and validate the state transition:
2415  */
2416 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2417                              enum lock_usage_bit new_bit)
2418 {
2419         unsigned int new_mask = 1 << new_bit, ret = 1;
2420
2421         /*
2422          * If already set then do not dirty the cacheline,
2423          * nor do any checks:
2424          */
2425         if (likely(hlock_class(this)->usage_mask & new_mask))
2426                 return 1;
2427
2428         if (!graph_lock())
2429                 return 0;
2430         /*
2431          * Make sure we didnt race:
2432          */
2433         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2434                 graph_unlock();
2435                 return 1;
2436         }
2437
2438         hlock_class(this)->usage_mask |= new_mask;
2439
2440         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2441                 return 0;
2442
2443         switch (new_bit) {
2444         case LOCK_USED_IN_HARDIRQ:
2445         case LOCK_USED_IN_SOFTIRQ:
2446         case LOCK_USED_IN_HARDIRQ_READ:
2447         case LOCK_USED_IN_SOFTIRQ_READ:
2448         case LOCK_ENABLED_HARDIRQS:
2449         case LOCK_ENABLED_SOFTIRQS:
2450         case LOCK_ENABLED_HARDIRQS_READ:
2451         case LOCK_ENABLED_SOFTIRQS_READ:
2452                 ret = mark_lock_irq(curr, this, new_bit);
2453                 if (!ret)
2454                         return 0;
2455                 break;
2456         case LOCK_USED:
2457                 debug_atomic_dec(&nr_unused_locks);
2458                 break;
2459         default:
2460                 if (!debug_locks_off_graph_unlock())
2461                         return 0;
2462                 WARN_ON(1);
2463                 return 0;
2464         }
2465
2466         graph_unlock();
2467
2468         /*
2469          * We must printk outside of the graph_lock:
2470          */
2471         if (ret == 2) {
2472                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2473                 print_lock(this);
2474                 print_irqtrace_events(curr);
2475                 dump_stack();
2476         }
2477
2478         return ret;
2479 }
2480
2481 /*
2482  * Initialize a lock instance's lock-class mapping info:
2483  */
2484 void lockdep_init_map(struct lockdep_map *lock, const char *name,
2485                       struct lock_class_key *key, int subclass)
2486 {
2487         if (unlikely(!debug_locks))
2488                 return;
2489
2490         if (DEBUG_LOCKS_WARN_ON(!key))
2491                 return;
2492         if (DEBUG_LOCKS_WARN_ON(!name))
2493                 return;
2494         /*
2495          * Sanity check, the lock-class key must be persistent:
2496          */
2497         if (!static_obj(key)) {
2498                 printk("BUG: key %p not in .data!\n", key);
2499                 DEBUG_LOCKS_WARN_ON(1);
2500                 return;
2501         }
2502         lock->name = name;
2503         lock->key = key;
2504         lock->class_cache = NULL;
2505 #ifdef CONFIG_LOCK_STAT
2506         lock->cpu = raw_smp_processor_id();
2507 #endif
2508         if (subclass)
2509                 register_lock_class(lock, subclass, 1);
2510 }
2511
2512 EXPORT_SYMBOL_GPL(lockdep_init_map);
2513
2514 /*
2515  * This gets called for every mutex_lock*()/spin_lock*() operation.
2516  * We maintain the dependency maps and validate the locking attempt:
2517  */
2518 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2519                           int trylock, int read, int check, int hardirqs_off,
2520                           struct lockdep_map *nest_lock, unsigned long ip)
2521 {
2522         struct task_struct *curr = current;
2523         struct lock_class *class = NULL;
2524         struct held_lock *hlock;
2525         unsigned int depth, id;
2526         int chain_head = 0;
2527         u64 chain_key;
2528
2529         if (!prove_locking)
2530                 check = 1;
2531
2532         if (unlikely(!debug_locks))
2533                 return 0;
2534
2535         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2536                 return 0;
2537
2538         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2539                 debug_locks_off();
2540                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2541                 printk("turning off the locking correctness validator.\n");
2542                 return 0;
2543         }
2544
2545         if (!subclass)
2546                 class = lock->class_cache;
2547         /*
2548          * Not cached yet or subclass?
2549          */
2550         if (unlikely(!class)) {
2551                 class = register_lock_class(lock, subclass, 0);
2552                 if (!class)
2553                         return 0;
2554         }
2555         debug_atomic_inc((atomic_t *)&class->ops);
2556         if (very_verbose(class)) {
2557                 printk("\nacquire class [%p] %s", class->key, class->name);
2558                 if (class->name_version > 1)
2559                         printk("#%d", class->name_version);
2560                 printk("\n");
2561                 dump_stack();
2562         }
2563
2564         /*
2565          * Add the lock to the list of currently held locks.
2566          * (we dont increase the depth just yet, up until the
2567          * dependency checks are done)
2568          */
2569         depth = curr->lockdep_depth;
2570         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2571                 return 0;
2572
2573         hlock = curr->held_locks + depth;
2574         if (DEBUG_LOCKS_WARN_ON(!class))
2575                 return 0;
2576         hlock->class_idx = class - lock_classes + 1;
2577         hlock->acquire_ip = ip;
2578         hlock->instance = lock;
2579         hlock->nest_lock = nest_lock;
2580         hlock->trylock = trylock;
2581         hlock->read = read;
2582         hlock->check = check;
2583         hlock->hardirqs_off = !!hardirqs_off;
2584 #ifdef CONFIG_LOCK_STAT
2585         hlock->waittime_stamp = 0;
2586         hlock->holdtime_stamp = sched_clock();
2587 #endif
2588
2589         if (check == 2 && !mark_irqflags(curr, hlock))
2590                 return 0;
2591
2592         /* mark it as used: */
2593         if (!mark_lock(curr, hlock, LOCK_USED))
2594                 return 0;
2595
2596         /*
2597          * Calculate the chain hash: it's the combined hash of all the
2598          * lock keys along the dependency chain. We save the hash value
2599          * at every step so that we can get the current hash easily
2600          * after unlock. The chain hash is then used to cache dependency
2601          * results.
2602          *
2603          * The 'key ID' is what is the most compact key value to drive
2604          * the hash, not class->key.
2605          */
2606         id = class - lock_classes;
2607         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2608                 return 0;
2609
2610         chain_key = curr->curr_chain_key;
2611         if (!depth) {
2612                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2613                         return 0;
2614                 chain_head = 1;
2615         }
2616
2617         hlock->prev_chain_key = chain_key;
2618         if (separate_irq_context(curr, hlock)) {
2619                 chain_key = 0;
2620                 chain_head = 1;
2621         }
2622         chain_key = iterate_chain_key(chain_key, id);
2623
2624         if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2625                 return 0;
2626
2627         curr->curr_chain_key = chain_key;
2628         curr->lockdep_depth++;
2629         check_chain_key(curr);
2630 #ifdef CONFIG_DEBUG_LOCKDEP
2631         if (unlikely(!debug_locks))
2632                 return 0;
2633 #endif
2634         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2635                 debug_locks_off();
2636                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2637                 printk("turning off the locking correctness validator.\n");
2638                 return 0;
2639         }
2640
2641         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2642                 max_lockdep_depth = curr->lockdep_depth;
2643
2644         return 1;
2645 }
2646
2647 static int
2648 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2649                            unsigned long ip)
2650 {
2651         if (!debug_locks_off())
2652                 return 0;
2653         if (debug_locks_silent)
2654                 return 0;
2655
2656         printk("\n=====================================\n");
2657         printk(  "[ BUG: bad unlock balance detected! ]\n");
2658         printk(  "-------------------------------------\n");
2659         printk("%s/%d is trying to release lock (",
2660                 curr->comm, task_pid_nr(curr));
2661         print_lockdep_cache(lock);
2662         printk(") at:\n");
2663         print_ip_sym(ip);
2664         printk("but there are no more locks to release!\n");
2665         printk("\nother info that might help us debug this:\n");
2666         lockdep_print_held_locks(curr);
2667
2668         printk("\nstack backtrace:\n");
2669         dump_stack();
2670
2671         return 0;
2672 }
2673
2674 /*
2675  * Common debugging checks for both nested and non-nested unlock:
2676  */
2677 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2678                         unsigned long ip)
2679 {
2680         if (unlikely(!debug_locks))
2681                 return 0;
2682         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2683                 return 0;
2684
2685         if (curr->lockdep_depth <= 0)
2686                 return print_unlock_inbalance_bug(curr, lock, ip);
2687
2688         return 1;
2689 }
2690
2691 static int
2692 __lock_set_subclass(struct lockdep_map *lock,
2693                     unsigned int subclass, unsigned long ip)
2694 {
2695         struct task_struct *curr = current;
2696         struct held_lock *hlock, *prev_hlock;
2697         struct lock_class *class;
2698         unsigned int depth;
2699         int i;
2700
2701         depth = curr->lockdep_depth;
2702         if (DEBUG_LOCKS_WARN_ON(!depth))
2703                 return 0;
2704
2705         prev_hlock = NULL;
2706         for (i = depth-1; i >= 0; i--) {
2707                 hlock = curr->held_locks + i;
2708                 /*
2709                  * We must not cross into another context:
2710                  */
2711                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2712                         break;
2713                 if (hlock->instance == lock)
2714                         goto found_it;
2715                 prev_hlock = hlock;
2716         }
2717         return print_unlock_inbalance_bug(curr, lock, ip);
2718
2719 found_it:
2720         class = register_lock_class(lock, subclass, 0);
2721         hlock->class_idx = class - lock_classes + 1;
2722
2723         curr->lockdep_depth = i;
2724         curr->curr_chain_key = hlock->prev_chain_key;
2725
2726         for (; i < depth; i++) {
2727                 hlock = curr->held_locks + i;
2728                 if (!__lock_acquire(hlock->instance,
2729                         hlock_class(hlock)->subclass, hlock->trylock,
2730                                 hlock->read, hlock->check, hlock->hardirqs_off,
2731                                 hlock->nest_lock, hlock->acquire_ip))
2732                         return 0;
2733         }
2734
2735         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2736                 return 0;
2737         return 1;
2738 }
2739
2740 /*
2741  * Remove the lock to the list of currently held locks in a
2742  * potentially non-nested (out of order) manner. This is a
2743  * relatively rare operation, as all the unlock APIs default
2744  * to nested mode (which uses lock_release()):
2745  */
2746 static int
2747 lock_release_non_nested(struct task_struct *curr,
2748                         struct lockdep_map *lock, unsigned long ip)
2749 {
2750         struct held_lock *hlock, *prev_hlock;
2751         unsigned int depth;
2752         int i;
2753
2754         /*
2755          * Check whether the lock exists in the current stack
2756          * of held locks:
2757          */
2758         depth = curr->lockdep_depth;
2759         if (DEBUG_LOCKS_WARN_ON(!depth))
2760                 return 0;
2761
2762         prev_hlock = NULL;
2763         for (i = depth-1; i >= 0; i--) {
2764                 hlock = curr->held_locks + i;
2765                 /*
2766                  * We must not cross into another context:
2767                  */
2768                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2769                         break;
2770                 if (hlock->instance == lock)
2771                         goto found_it;
2772                 prev_hlock = hlock;
2773         }
2774         return print_unlock_inbalance_bug(curr, lock, ip);
2775
2776 found_it:
2777         lock_release_holdtime(hlock);
2778
2779         /*
2780          * We have the right lock to unlock, 'hlock' points to it.
2781          * Now we remove it from the stack, and add back the other
2782          * entries (if any), recalculating the hash along the way:
2783          */
2784         curr->lockdep_depth = i;
2785         curr->curr_chain_key = hlock->prev_chain_key;
2786
2787         for (i++; i < depth; i++) {
2788                 hlock = curr->held_locks + i;
2789                 if (!__lock_acquire(hlock->instance,
2790                         hlock_class(hlock)->subclass, hlock->trylock,
2791                                 hlock->read, hlock->check, hlock->hardirqs_off,
2792                                 hlock->nest_lock, hlock->acquire_ip))
2793                         return 0;
2794         }
2795
2796         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2797                 return 0;
2798         return 1;
2799 }
2800
2801 /*
2802  * Remove the lock to the list of currently held locks - this gets
2803  * called on mutex_unlock()/spin_unlock*() (or on a failed
2804  * mutex_lock_interruptible()). This is done for unlocks that nest
2805  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2806  */
2807 static int lock_release_nested(struct task_struct *curr,
2808                                struct lockdep_map *lock, unsigned long ip)
2809 {
2810         struct held_lock *hlock;
2811         unsigned int depth;
2812
2813         /*
2814          * Pop off the top of the lock stack:
2815          */
2816         depth = curr->lockdep_depth - 1;
2817         hlock = curr->held_locks + depth;
2818
2819         /*
2820          * Is the unlock non-nested:
2821          */
2822         if (hlock->instance != lock)
2823                 return lock_release_non_nested(curr, lock, ip);
2824         curr->lockdep_depth--;
2825
2826         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2827                 return 0;
2828
2829         curr->curr_chain_key = hlock->prev_chain_key;
2830
2831         lock_release_holdtime(hlock);
2832
2833 #ifdef CONFIG_DEBUG_LOCKDEP
2834         hlock->prev_chain_key = 0;
2835         hlock->class_idx = 0;
2836         hlock->acquire_ip = 0;
2837         hlock->irq_context = 0;
2838 #endif
2839         return 1;
2840 }
2841
2842 /*
2843  * Remove the lock to the list of currently held locks - this gets
2844  * called on mutex_unlock()/spin_unlock*() (or on a failed
2845  * mutex_lock_interruptible()). This is done for unlocks that nest
2846  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2847  */
2848 static void
2849 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2850 {
2851         struct task_struct *curr = current;
2852
2853         if (!check_unlock(curr, lock, ip))
2854                 return;
2855
2856         if (nested) {
2857                 if (!lock_release_nested(curr, lock, ip))
2858                         return;
2859         } else {
2860                 if (!lock_release_non_nested(curr, lock, ip))
2861                         return;
2862         }
2863
2864         check_chain_key(curr);
2865 }
2866
2867 /*
2868  * Check whether we follow the irq-flags state precisely:
2869  */
2870 static void check_flags(unsigned long flags)
2871 {
2872 #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
2873     defined(CONFIG_TRACE_IRQFLAGS)
2874         if (!debug_locks)
2875                 return;
2876
2877         if (irqs_disabled_flags(flags)) {
2878                 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
2879                         printk("possible reason: unannotated irqs-off.\n");
2880                 }
2881         } else {
2882                 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
2883                         printk("possible reason: unannotated irqs-on.\n");
2884                 }
2885         }
2886
2887         /*
2888          * We dont accurately track softirq state in e.g.
2889          * hardirq contexts (such as on 4KSTACKS), so only
2890          * check if not in hardirq contexts:
2891          */
2892         if (!hardirq_count()) {
2893                 if (softirq_count())
2894                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2895                 else
2896                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2897         }
2898
2899         if (!debug_locks)
2900                 print_irqtrace_events(current);
2901 #endif
2902 }
2903
2904 void
2905 lock_set_subclass(struct lockdep_map *lock,
2906                   unsigned int subclass, unsigned long ip)
2907 {
2908         unsigned long flags;
2909
2910         if (unlikely(current->lockdep_recursion))
2911                 return;
2912
2913         raw_local_irq_save(flags);
2914         current->lockdep_recursion = 1;
2915         check_flags(flags);
2916         if (__lock_set_subclass(lock, subclass, ip))
2917                 check_chain_key(current);
2918         current->lockdep_recursion = 0;
2919         raw_local_irq_restore(flags);
2920 }
2921
2922 EXPORT_SYMBOL_GPL(lock_set_subclass);
2923
2924 /*
2925  * We are not always called with irqs disabled - do that here,
2926  * and also avoid lockdep recursion:
2927  */
2928 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2929                           int trylock, int read, int check,
2930                           struct lockdep_map *nest_lock, unsigned long ip)
2931 {
2932         unsigned long flags;
2933
2934         if (unlikely(current->lockdep_recursion))
2935                 return;
2936
2937         raw_local_irq_save(flags);
2938         check_flags(flags);
2939
2940         current->lockdep_recursion = 1;
2941         __lock_acquire(lock, subclass, trylock, read, check,
2942                        irqs_disabled_flags(flags), nest_lock, ip);
2943         current->lockdep_recursion = 0;
2944         raw_local_irq_restore(flags);
2945 }
2946
2947 EXPORT_SYMBOL_GPL(lock_acquire);
2948
2949 void lock_release(struct lockdep_map *lock, int nested,
2950                           unsigned long ip)
2951 {
2952         unsigned long flags;
2953
2954         if (unlikely(current->lockdep_recursion))
2955                 return;
2956
2957         raw_local_irq_save(flags);
2958         check_flags(flags);
2959         current->lockdep_recursion = 1;
2960         __lock_release(lock, nested, ip);
2961         current->lockdep_recursion = 0;
2962         raw_local_irq_restore(flags);
2963 }
2964
2965 EXPORT_SYMBOL_GPL(lock_release);
2966
2967 #ifdef CONFIG_LOCK_STAT
2968 static int
2969 print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
2970                            unsigned long ip)
2971 {
2972         if (!debug_locks_off())
2973                 return 0;
2974         if (debug_locks_silent)
2975                 return 0;
2976
2977         printk("\n=================================\n");
2978         printk(  "[ BUG: bad contention detected! ]\n");
2979         printk(  "---------------------------------\n");
2980         printk("%s/%d is trying to contend lock (",
2981                 curr->comm, task_pid_nr(curr));
2982         print_lockdep_cache(lock);
2983         printk(") at:\n");
2984         print_ip_sym(ip);
2985         printk("but there are no locks held!\n");
2986         printk("\nother info that might help us debug this:\n");
2987         lockdep_print_held_locks(curr);
2988
2989         printk("\nstack backtrace:\n");
2990         dump_stack();
2991
2992         return 0;
2993 }
2994
2995 static void
2996 __lock_contended(struct lockdep_map *lock, unsigned long ip)
2997 {
2998         struct task_struct *curr = current;
2999         struct held_lock *hlock, *prev_hlock;
3000         struct lock_class_stats *stats;
3001         unsigned int depth;
3002         int i, point;
3003
3004         depth = curr->lockdep_depth;
3005         if (DEBUG_LOCKS_WARN_ON(!depth))
3006                 return;
3007
3008         prev_hlock = NULL;
3009         for (i = depth-1; i >= 0; i--) {
3010                 hlock = curr->held_locks + i;
3011                 /*
3012                  * We must not cross into another context:
3013                  */
3014                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3015                         break;
3016                 if (hlock->instance == lock)
3017                         goto found_it;
3018                 prev_hlock = hlock;
3019         }
3020         print_lock_contention_bug(curr, lock, ip);
3021         return;
3022
3023 found_it:
3024         hlock->waittime_stamp = sched_clock();
3025
3026         point = lock_contention_point(hlock_class(hlock), ip);
3027
3028         stats = get_lock_stats(hlock_class(hlock));
3029         if (point < ARRAY_SIZE(stats->contention_point))
3030                 stats->contention_point[point]++;
3031         if (lock->cpu != smp_processor_id())
3032                 stats->bounces[bounce_contended + !!hlock->read]++;
3033         put_lock_stats(stats);
3034 }
3035
3036 static void
3037 __lock_acquired(struct lockdep_map *lock)
3038 {
3039         struct task_struct *curr = current;
3040         struct held_lock *hlock, *prev_hlock;
3041         struct lock_class_stats *stats;
3042         unsigned int depth;
3043         u64 now;
3044         s64 waittime = 0;
3045         int i, cpu;
3046
3047         depth = curr->lockdep_depth;
3048         if (DEBUG_LOCKS_WARN_ON(!depth))
3049                 return;
3050
3051         prev_hlock = NULL;
3052         for (i = depth-1; i >= 0; i--) {
3053                 hlock = curr->held_locks + i;
3054                 /*
3055                  * We must not cross into another context:
3056                  */
3057                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3058                         break;
3059                 if (hlock->instance == lock)
3060                         goto found_it;
3061                 prev_hlock = hlock;
3062         }
3063         print_lock_contention_bug(curr, lock, _RET_IP_);
3064         return;
3065
3066 found_it:
3067         cpu = smp_processor_id();
3068         if (hlock->waittime_stamp) {
3069                 now = sched_clock();
3070                 waittime = now - hlock->waittime_stamp;
3071                 hlock->holdtime_stamp = now;
3072         }
3073
3074         stats = get_lock_stats(hlock_class(hlock));
3075         if (waittime) {
3076                 if (hlock->read)
3077                         lock_time_inc(&stats->read_waittime, waittime);
3078                 else
3079                         lock_time_inc(&stats->write_waittime, waittime);
3080         }
3081         if (lock->cpu != cpu)
3082                 stats->bounces[bounce_acquired + !!hlock->read]++;
3083         put_lock_stats(stats);
3084
3085         lock->cpu = cpu;
3086 }
3087
3088 void lock_contended(struct lockdep_map *lock, unsigned long ip)
3089 {
3090         unsigned long flags;
3091
3092         if (unlikely(!lock_stat))
3093                 return;
3094
3095         if (unlikely(current->lockdep_recursion))
3096                 return;
3097
3098         raw_local_irq_save(flags);
3099         check_flags(flags);
3100         current->lockdep_recursion = 1;
3101         __lock_contended(lock, ip);
3102         current->lockdep_recursion = 0;
3103         raw_local_irq_restore(flags);
3104 }
3105 EXPORT_SYMBOL_GPL(lock_contended);
3106
3107 void lock_acquired(struct lockdep_map *lock)
3108 {
3109         unsigned long flags;
3110
3111         if (unlikely(!lock_stat))
3112                 return;
3113
3114         if (unlikely(current->lockdep_recursion))
3115                 return;
3116
3117         raw_local_irq_save(flags);
3118         check_flags(flags);
3119         current->lockdep_recursion = 1;
3120         __lock_acquired(lock);
3121         current->lockdep_recursion = 0;
3122         raw_local_irq_restore(flags);
3123 }
3124 EXPORT_SYMBOL_GPL(lock_acquired);
3125 #endif
3126
3127 /*
3128  * Used by the testsuite, sanitize the validator state
3129  * after a simulated failure:
3130  */
3131
3132 void lockdep_reset(void)
3133 {
3134         unsigned long flags;
3135         int i;
3136
3137         raw_local_irq_save(flags);
3138         current->curr_chain_key = 0;
3139         current->lockdep_depth = 0;
3140         current->lockdep_recursion = 0;
3141         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3142         nr_hardirq_chains = 0;
3143         nr_softirq_chains = 0;
3144         nr_process_chains = 0;
3145         debug_locks = 1;
3146         for (i = 0; i < CHAINHASH_SIZE; i++)
3147                 INIT_LIST_HEAD(chainhash_table + i);
3148         raw_local_irq_restore(flags);
3149 }
3150
3151 static void zap_class(struct lock_class *class)
3152 {
3153         int i;
3154
3155         /*
3156          * Remove all dependencies this lock is
3157          * involved in:
3158          */
3159         for (i = 0; i < nr_list_entries; i++) {
3160                 if (list_entries[i].class == class)
3161                         list_del_rcu(&list_entries[i].entry);
3162         }
3163         /*
3164          * Unhash the class and remove it from the all_lock_classes list:
3165          */
3166         list_del_rcu(&class->hash_entry);
3167         list_del_rcu(&class->lock_entry);
3168
3169         class->key = NULL;
3170 }
3171
3172 static inline int within(const void *addr, void *start, unsigned long size)
3173 {
3174         return addr >= start && addr < start + size;
3175 }
3176
3177 void lockdep_free_key_range(void *start, unsigned long size)
3178 {
3179         struct lock_class *class, *next;
3180         struct list_head *head;
3181         unsigned long flags;
3182         int i;
3183         int locked;
3184
3185         raw_local_irq_save(flags);
3186         locked = graph_lock();
3187
3188         /*
3189          * Unhash all classes that were created by this module:
3190          */
3191         for (i = 0; i < CLASSHASH_SIZE; i++) {
3192                 head = classhash_table + i;
3193                 if (list_empty(head))
3194                         continue;
3195                 list_for_each_entry_safe(class, next, head, hash_entry) {
3196                         if (within(class->key, start, size))
3197                                 zap_class(class);
3198                         else if (within(class->name, start, size))
3199                                 zap_class(class);
3200                 }
3201         }
3202
3203         if (locked)
3204                 graph_unlock();
3205         raw_local_irq_restore(flags);
3206 }
3207
3208 void lockdep_reset_lock(struct lockdep_map *lock)
3209 {
3210         struct lock_class *class, *next;
3211         struct list_head *head;
3212         unsigned long flags;
3213         int i, j;
3214         int locked;
3215
3216         raw_local_irq_save(flags);
3217
3218         /*
3219          * Remove all classes this lock might have:
3220          */
3221         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3222                 /*
3223                  * If the class exists we look it up and zap it:
3224                  */
3225                 class = look_up_lock_class(lock, j);
3226                 if (class)
3227                         zap_class(class);
3228         }
3229         /*
3230          * Debug check: in the end all mapped classes should
3231          * be gone.
3232          */
3233         locked = graph_lock();
3234         for (i = 0; i < CLASSHASH_SIZE; i++) {
3235                 head = classhash_table + i;
3236                 if (list_empty(head))
3237                         continue;
3238                 list_for_each_entry_safe(class, next, head, hash_entry) {
3239                         if (unlikely(class == lock->class_cache)) {
3240                                 if (debug_locks_off_graph_unlock())
3241                                         WARN_ON(1);
3242                                 goto out_restore;
3243                         }
3244                 }
3245         }
3246         if (locked)
3247                 graph_unlock();
3248
3249 out_restore:
3250         raw_local_irq_restore(flags);
3251 }
3252
3253 void lockdep_init(void)
3254 {
3255         int i;
3256
3257         /*
3258          * Some architectures have their own start_kernel()
3259          * code which calls lockdep_init(), while we also
3260          * call lockdep_init() from the start_kernel() itself,
3261          * and we want to initialize the hashes only once:
3262          */
3263         if (lockdep_initialized)
3264                 return;
3265
3266         for (i = 0; i < CLASSHASH_SIZE; i++)
3267                 INIT_LIST_HEAD(classhash_table + i);
3268
3269         for (i = 0; i < CHAINHASH_SIZE; i++)
3270                 INIT_LIST_HEAD(chainhash_table + i);
3271
3272         lockdep_initialized = 1;
3273 }
3274
3275 void __init lockdep_info(void)
3276 {
3277         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3278
3279         printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
3280         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
3281         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3282         printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
3283         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
3284         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
3285         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
3286
3287         printk(" memory used by lock dependency info: %lu kB\n",
3288                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3289                 sizeof(struct list_head) * CLASSHASH_SIZE +
3290                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3291                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3292                 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
3293
3294         printk(" per task-struct memory footprint: %lu bytes\n",
3295                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3296
3297 #ifdef CONFIG_DEBUG_LOCKDEP
3298         if (lockdep_init_error) {
3299                 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3300                 printk("Call stack leading to lockdep invocation was:\n");
3301                 print_stack_trace(&lockdep_init_trace, 0);
3302         }
3303 #endif
3304 }
3305
3306 static void
3307 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3308                      const void *mem_to, struct held_lock *hlock)
3309 {
3310         if (!debug_locks_off())
3311                 return;
3312         if (debug_locks_silent)
3313                 return;
3314
3315         printk("\n=========================\n");
3316         printk(  "[ BUG: held lock freed! ]\n");
3317         printk(  "-------------------------\n");
3318         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3319                 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3320         print_lock(hlock);
3321         lockdep_print_held_locks(curr);
3322
3323         printk("\nstack backtrace:\n");
3324         dump_stack();
3325 }
3326
3327 static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3328                                 const void* lock_from, unsigned long lock_len)
3329 {
3330         return lock_from + lock_len <= mem_from ||
3331                 mem_from + mem_len <= lock_from;
3332 }
3333
3334 /*
3335  * Called when kernel memory is freed (or unmapped), or if a lock
3336  * is destroyed or reinitialized - this code checks whether there is
3337  * any held lock in the memory range of <from> to <to>:
3338  */
3339 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3340 {
3341         struct task_struct *curr = current;
3342         struct held_lock *hlock;
3343         unsigned long flags;
3344         int i;
3345
3346         if (unlikely(!debug_locks))
3347                 return;
3348
3349         local_irq_save(flags);
3350         for (i = 0; i < curr->lockdep_depth; i++) {
3351                 hlock = curr->held_locks + i;
3352
3353                 if (not_in_range(mem_from, mem_len, hlock->instance,
3354                                         sizeof(*hlock->instance)))
3355                         continue;
3356
3357                 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3358                 break;
3359         }
3360         local_irq_restore(flags);
3361 }
3362 EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3363
3364 static void print_held_locks_bug(struct task_struct *curr)
3365 {
3366         if (!debug_locks_off())
3367                 return;
3368         if (debug_locks_silent)
3369                 return;
3370
3371         printk("\n=====================================\n");
3372         printk(  "[ BUG: lock held at task exit time! ]\n");
3373         printk(  "-------------------------------------\n");
3374         printk("%s/%d is exiting with locks still held!\n",
3375                 curr->comm, task_pid_nr(curr));
3376         lockdep_print_held_locks(curr);
3377
3378         printk("\nstack backtrace:\n");
3379         dump_stack();
3380 }
3381
3382 void debug_check_no_locks_held(struct task_struct *task)
3383 {
3384         if (unlikely(task->lockdep_depth > 0))
3385                 print_held_locks_bug(task);
3386 }
3387
3388 void debug_show_all_locks(void)
3389 {
3390         struct task_struct *g, *p;
3391         int count = 10;
3392         int unlock = 1;
3393
3394         if (unlikely(!debug_locks)) {
3395                 printk("INFO: lockdep is turned off.\n");
3396                 return;
3397         }
3398         printk("\nShowing all locks held in the system:\n");
3399
3400         /*
3401          * Here we try to get the tasklist_lock as hard as possible,
3402          * if not successful after 2 seconds we ignore it (but keep
3403          * trying). This is to enable a debug printout even if a
3404          * tasklist_lock-holding task deadlocks or crashes.
3405          */
3406 retry:
3407         if (!read_trylock(&tasklist_lock)) {
3408                 if (count == 10)
3409                         printk("hm, tasklist_lock locked, retrying... ");
3410                 if (count) {
3411                         count--;
3412                         printk(" #%d", 10-count);
3413                         mdelay(200);
3414                         goto retry;
3415                 }
3416                 printk(" ignoring it.\n");
3417                 unlock = 0;
3418         } else {
3419                 if (count != 10)
3420                         printk(KERN_CONT " locked it.\n");
3421         }
3422
3423         do_each_thread(g, p) {
3424                 /*
3425                  * It's not reliable to print a task's held locks
3426                  * if it's not sleeping (or if it's not the current
3427                  * task):
3428                  */
3429                 if (p->state == TASK_RUNNING && p != current)
3430                         continue;
3431                 if (p->lockdep_depth)
3432                         lockdep_print_held_locks(p);
3433                 if (!unlock)
3434                         if (read_trylock(&tasklist_lock))
3435                                 unlock = 1;
3436         } while_each_thread(g, p);
3437
3438         printk("\n");
3439         printk("=============================================\n\n");
3440
3441         if (unlock)
3442                 read_unlock(&tasklist_lock);
3443 }
3444
3445 EXPORT_SYMBOL_GPL(debug_show_all_locks);
3446
3447 /*
3448  * Careful: only use this function if you are sure that
3449  * the task cannot run in parallel!
3450  */
3451 void __debug_show_held_locks(struct task_struct *task)
3452 {
3453         if (unlikely(!debug_locks)) {
3454                 printk("INFO: lockdep is turned off.\n");
3455                 return;
3456         }
3457         lockdep_print_held_locks(task);
3458 }
3459 EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3460
3461 void debug_show_held_locks(struct task_struct *task)
3462 {
3463                 __debug_show_held_locks(task);
3464 }
3465
3466 EXPORT_SYMBOL_GPL(debug_show_held_locks);
3467
3468 void lockdep_sys_exit(void)
3469 {
3470         struct task_struct *curr = current;
3471
3472         if (unlikely(curr->lockdep_depth)) {
3473                 if (!debug_locks_off())
3474                         return;
3475                 printk("\n================================================\n");
3476                 printk(  "[ BUG: lock held when returning to user space! ]\n");
3477                 printk(  "------------------------------------------------\n");
3478                 printk("%s/%d is leaving the kernel with locks still held!\n",
3479                                 curr->comm, curr->pid);
3480                 lockdep_print_held_locks(curr);
3481         }
3482 }