Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[sfrench/cifs-2.6.git] / kernel / locking / 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
10  *
11  * this code maps all the lock dependencies as they occur in a live kernel
12  * and will warn about the following classes of locking bugs:
13  *
14  * - lock inversion scenarios
15  * - circular lock dependencies
16  * - hardirq/softirq safe/unsafe locking bugs
17  *
18  * Bugs are reported even if the current locking scenario does not cause
19  * any deadlock at this point.
20  *
21  * I.e. if anytime in the past two locks were taken in a different order,
22  * even if it happened for another task, even if those were different
23  * locks (but of the same class as this lock), this code will detect it.
24  *
25  * Thanks to Arjan van de Ven for coming up with the initial idea of
26  * mapping lock dependencies runtime.
27  */
28 #define DISABLE_BRANCH_PROFILING
29 #include <linux/mutex.h>
30 #include <linux/sched.h>
31 #include <linux/sched/clock.h>
32 #include <linux/sched/task.h>
33 #include <linux/sched/mm.h>
34 #include <linux/delay.h>
35 #include <linux/module.h>
36 #include <linux/proc_fs.h>
37 #include <linux/seq_file.h>
38 #include <linux/spinlock.h>
39 #include <linux/kallsyms.h>
40 #include <linux/interrupt.h>
41 #include <linux/stacktrace.h>
42 #include <linux/debug_locks.h>
43 #include <linux/irqflags.h>
44 #include <linux/utsname.h>
45 #include <linux/hash.h>
46 #include <linux/ftrace.h>
47 #include <linux/stringify.h>
48 #include <linux/bitops.h>
49 #include <linux/gfp.h>
50 #include <linux/kmemcheck.h>
51 #include <linux/random.h>
52 #include <linux/jhash.h>
53
54 #include <asm/sections.h>
55
56 #include "lockdep_internals.h"
57
58 #define CREATE_TRACE_POINTS
59 #include <trace/events/lock.h>
60
61 #ifdef CONFIG_LOCKDEP_CROSSRELEASE
62 #include <linux/slab.h>
63 #endif
64
65 #ifdef CONFIG_PROVE_LOCKING
66 int prove_locking = 1;
67 module_param(prove_locking, int, 0644);
68 #else
69 #define prove_locking 0
70 #endif
71
72 #ifdef CONFIG_LOCK_STAT
73 int lock_stat = 1;
74 module_param(lock_stat, int, 0644);
75 #else
76 #define lock_stat 0
77 #endif
78
79 /*
80  * lockdep_lock: protects the lockdep graph, the hashes and the
81  *               class/list/hash allocators.
82  *
83  * This is one of the rare exceptions where it's justified
84  * to use a raw spinlock - we really dont want the spinlock
85  * code to recurse back into the lockdep code...
86  */
87 static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
88
89 static int graph_lock(void)
90 {
91         arch_spin_lock(&lockdep_lock);
92         /*
93          * Make sure that if another CPU detected a bug while
94          * walking the graph we dont change it (while the other
95          * CPU is busy printing out stuff with the graph lock
96          * dropped already)
97          */
98         if (!debug_locks) {
99                 arch_spin_unlock(&lockdep_lock);
100                 return 0;
101         }
102         /* prevent any recursions within lockdep from causing deadlocks */
103         current->lockdep_recursion++;
104         return 1;
105 }
106
107 static inline int graph_unlock(void)
108 {
109         if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
110                 /*
111                  * The lockdep graph lock isn't locked while we expect it to
112                  * be, we're confused now, bye!
113                  */
114                 return DEBUG_LOCKS_WARN_ON(1);
115         }
116
117         current->lockdep_recursion--;
118         arch_spin_unlock(&lockdep_lock);
119         return 0;
120 }
121
122 /*
123  * Turn lock debugging off and return with 0 if it was off already,
124  * and also release the graph lock:
125  */
126 static inline int debug_locks_off_graph_unlock(void)
127 {
128         int ret = debug_locks_off();
129
130         arch_spin_unlock(&lockdep_lock);
131
132         return ret;
133 }
134
135 unsigned long nr_list_entries;
136 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
137
138 /*
139  * All data structures here are protected by the global debug_lock.
140  *
141  * Mutex key structs only get allocated, once during bootup, and never
142  * get freed - this significantly simplifies the debugging code.
143  */
144 unsigned long nr_lock_classes;
145 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
146
147 static inline struct lock_class *hlock_class(struct held_lock *hlock)
148 {
149         if (!hlock->class_idx) {
150                 /*
151                  * Someone passed in garbage, we give up.
152                  */
153                 DEBUG_LOCKS_WARN_ON(1);
154                 return NULL;
155         }
156         return lock_classes + hlock->class_idx - 1;
157 }
158
159 #ifdef CONFIG_LOCK_STAT
160 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
161
162 static inline u64 lockstat_clock(void)
163 {
164         return local_clock();
165 }
166
167 static int lock_point(unsigned long points[], unsigned long ip)
168 {
169         int i;
170
171         for (i = 0; i < LOCKSTAT_POINTS; i++) {
172                 if (points[i] == 0) {
173                         points[i] = ip;
174                         break;
175                 }
176                 if (points[i] == ip)
177                         break;
178         }
179
180         return i;
181 }
182
183 static void lock_time_inc(struct lock_time *lt, u64 time)
184 {
185         if (time > lt->max)
186                 lt->max = time;
187
188         if (time < lt->min || !lt->nr)
189                 lt->min = time;
190
191         lt->total += time;
192         lt->nr++;
193 }
194
195 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
196 {
197         if (!src->nr)
198                 return;
199
200         if (src->max > dst->max)
201                 dst->max = src->max;
202
203         if (src->min < dst->min || !dst->nr)
204                 dst->min = src->min;
205
206         dst->total += src->total;
207         dst->nr += src->nr;
208 }
209
210 struct lock_class_stats lock_stats(struct lock_class *class)
211 {
212         struct lock_class_stats stats;
213         int cpu, i;
214
215         memset(&stats, 0, sizeof(struct lock_class_stats));
216         for_each_possible_cpu(cpu) {
217                 struct lock_class_stats *pcs =
218                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
219
220                 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
221                         stats.contention_point[i] += pcs->contention_point[i];
222
223                 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
224                         stats.contending_point[i] += pcs->contending_point[i];
225
226                 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
227                 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
228
229                 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
230                 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
231
232                 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
233                         stats.bounces[i] += pcs->bounces[i];
234         }
235
236         return stats;
237 }
238
239 void clear_lock_stats(struct lock_class *class)
240 {
241         int cpu;
242
243         for_each_possible_cpu(cpu) {
244                 struct lock_class_stats *cpu_stats =
245                         &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
246
247                 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
248         }
249         memset(class->contention_point, 0, sizeof(class->contention_point));
250         memset(class->contending_point, 0, sizeof(class->contending_point));
251 }
252
253 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
254 {
255         return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
256 }
257
258 static void put_lock_stats(struct lock_class_stats *stats)
259 {
260         put_cpu_var(cpu_lock_stats);
261 }
262
263 static void lock_release_holdtime(struct held_lock *hlock)
264 {
265         struct lock_class_stats *stats;
266         u64 holdtime;
267
268         if (!lock_stat)
269                 return;
270
271         holdtime = lockstat_clock() - hlock->holdtime_stamp;
272
273         stats = get_lock_stats(hlock_class(hlock));
274         if (hlock->read)
275                 lock_time_inc(&stats->read_holdtime, holdtime);
276         else
277                 lock_time_inc(&stats->write_holdtime, holdtime);
278         put_lock_stats(stats);
279 }
280 #else
281 static inline void lock_release_holdtime(struct held_lock *hlock)
282 {
283 }
284 #endif
285
286 /*
287  * We keep a global list of all lock classes. The list only grows,
288  * never shrinks. The list is only accessed with the lockdep
289  * spinlock lock held.
290  */
291 LIST_HEAD(all_lock_classes);
292
293 /*
294  * The lockdep classes are in a hash-table as well, for fast lookup:
295  */
296 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
297 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
298 #define __classhashfn(key)      hash_long((unsigned long)key, CLASSHASH_BITS)
299 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
300
301 static struct hlist_head classhash_table[CLASSHASH_SIZE];
302
303 /*
304  * We put the lock dependency chains into a hash-table as well, to cache
305  * their existence:
306  */
307 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
308 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
309 #define __chainhashfn(chain)    hash_long(chain, CHAINHASH_BITS)
310 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
311
312 static struct hlist_head chainhash_table[CHAINHASH_SIZE];
313
314 /*
315  * The hash key of the lock dependency chains is a hash itself too:
316  * it's a hash of all locks taken up to that lock, including that lock.
317  * It's a 64-bit hash, because it's important for the keys to be
318  * unique.
319  */
320 static inline u64 iterate_chain_key(u64 key, u32 idx)
321 {
322         u32 k0 = key, k1 = key >> 32;
323
324         __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
325
326         return k0 | (u64)k1 << 32;
327 }
328
329 void lockdep_off(void)
330 {
331         current->lockdep_recursion++;
332 }
333 EXPORT_SYMBOL(lockdep_off);
334
335 void lockdep_on(void)
336 {
337         current->lockdep_recursion--;
338 }
339 EXPORT_SYMBOL(lockdep_on);
340
341 /*
342  * Debugging switches:
343  */
344
345 #define VERBOSE                 0
346 #define VERY_VERBOSE            0
347
348 #if VERBOSE
349 # define HARDIRQ_VERBOSE        1
350 # define SOFTIRQ_VERBOSE        1
351 #else
352 # define HARDIRQ_VERBOSE        0
353 # define SOFTIRQ_VERBOSE        0
354 #endif
355
356 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
357 /*
358  * Quick filtering for interesting events:
359  */
360 static int class_filter(struct lock_class *class)
361 {
362 #if 0
363         /* Example */
364         if (class->name_version == 1 &&
365                         !strcmp(class->name, "lockname"))
366                 return 1;
367         if (class->name_version == 1 &&
368                         !strcmp(class->name, "&struct->lockfield"))
369                 return 1;
370 #endif
371         /* Filter everything else. 1 would be to allow everything else */
372         return 0;
373 }
374 #endif
375
376 static int verbose(struct lock_class *class)
377 {
378 #if VERBOSE
379         return class_filter(class);
380 #endif
381         return 0;
382 }
383
384 /*
385  * Stack-trace: tightly packed array of stack backtrace
386  * addresses. Protected by the graph_lock.
387  */
388 unsigned long nr_stack_trace_entries;
389 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
390
391 static void print_lockdep_off(const char *bug_msg)
392 {
393         printk(KERN_DEBUG "%s\n", bug_msg);
394         printk(KERN_DEBUG "turning off the locking correctness validator.\n");
395 #ifdef CONFIG_LOCK_STAT
396         printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
397 #endif
398 }
399
400 static int save_trace(struct stack_trace *trace)
401 {
402         trace->nr_entries = 0;
403         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
404         trace->entries = stack_trace + nr_stack_trace_entries;
405
406         trace->skip = 3;
407
408         save_stack_trace(trace);
409
410         /*
411          * Some daft arches put -1 at the end to indicate its a full trace.
412          *
413          * <rant> this is buggy anyway, since it takes a whole extra entry so a
414          * complete trace that maxes out the entries provided will be reported
415          * as incomplete, friggin useless </rant>
416          */
417         if (trace->nr_entries != 0 &&
418             trace->entries[trace->nr_entries-1] == ULONG_MAX)
419                 trace->nr_entries--;
420
421         trace->max_entries = trace->nr_entries;
422
423         nr_stack_trace_entries += trace->nr_entries;
424
425         if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
426                 if (!debug_locks_off_graph_unlock())
427                         return 0;
428
429                 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
430                 dump_stack();
431
432                 return 0;
433         }
434
435         return 1;
436 }
437
438 unsigned int nr_hardirq_chains;
439 unsigned int nr_softirq_chains;
440 unsigned int nr_process_chains;
441 unsigned int max_lockdep_depth;
442
443 #ifdef CONFIG_DEBUG_LOCKDEP
444 /*
445  * Various lockdep statistics:
446  */
447 DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
448 #endif
449
450 /*
451  * Locking printouts:
452  */
453
454 #define __USAGE(__STATE)                                                \
455         [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",       \
456         [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",         \
457         [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
458         [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
459
460 static const char *usage_str[] =
461 {
462 #define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
463 #include "lockdep_states.h"
464 #undef LOCKDEP_STATE
465         [LOCK_USED] = "INITIAL USE",
466 };
467
468 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
469 {
470         return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
471 }
472
473 static inline unsigned long lock_flag(enum lock_usage_bit bit)
474 {
475         return 1UL << bit;
476 }
477
478 static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
479 {
480         char c = '.';
481
482         if (class->usage_mask & lock_flag(bit + 2))
483                 c = '+';
484         if (class->usage_mask & lock_flag(bit)) {
485                 c = '-';
486                 if (class->usage_mask & lock_flag(bit + 2))
487                         c = '?';
488         }
489
490         return c;
491 }
492
493 void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
494 {
495         int i = 0;
496
497 #define LOCKDEP_STATE(__STATE)                                          \
498         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
499         usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
500 #include "lockdep_states.h"
501 #undef LOCKDEP_STATE
502
503         usage[i] = '\0';
504 }
505
506 static void __print_lock_name(struct lock_class *class)
507 {
508         char str[KSYM_NAME_LEN];
509         const char *name;
510
511         name = class->name;
512         if (!name) {
513                 name = __get_key_name(class->key, str);
514                 printk(KERN_CONT "%s", name);
515         } else {
516                 printk(KERN_CONT "%s", name);
517                 if (class->name_version > 1)
518                         printk(KERN_CONT "#%d", class->name_version);
519                 if (class->subclass)
520                         printk(KERN_CONT "/%d", class->subclass);
521         }
522 }
523
524 static void print_lock_name(struct lock_class *class)
525 {
526         char usage[LOCK_USAGE_CHARS];
527
528         get_usage_chars(class, usage);
529
530         printk(KERN_CONT " (");
531         __print_lock_name(class);
532         printk(KERN_CONT "){%s}", usage);
533 }
534
535 static void print_lockdep_cache(struct lockdep_map *lock)
536 {
537         const char *name;
538         char str[KSYM_NAME_LEN];
539
540         name = lock->name;
541         if (!name)
542                 name = __get_key_name(lock->key->subkeys, str);
543
544         printk(KERN_CONT "%s", name);
545 }
546
547 static void print_lock(struct held_lock *hlock)
548 {
549         /*
550          * We can be called locklessly through debug_show_all_locks() so be
551          * extra careful, the hlock might have been released and cleared.
552          */
553         unsigned int class_idx = hlock->class_idx;
554
555         /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
556         barrier();
557
558         if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
559                 printk(KERN_CONT "<RELEASED>\n");
560                 return;
561         }
562
563         print_lock_name(lock_classes + class_idx - 1);
564         printk(KERN_CONT ", at: [<%p>] %pS\n",
565                 (void *)hlock->acquire_ip, (void *)hlock->acquire_ip);
566 }
567
568 static void lockdep_print_held_locks(struct task_struct *curr)
569 {
570         int i, depth = curr->lockdep_depth;
571
572         if (!depth) {
573                 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
574                 return;
575         }
576         printk("%d lock%s held by %s/%d:\n",
577                 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
578
579         for (i = 0; i < depth; i++) {
580                 printk(" #%d: ", i);
581                 print_lock(curr->held_locks + i);
582         }
583 }
584
585 static void print_kernel_ident(void)
586 {
587         printk("%s %.*s %s\n", init_utsname()->release,
588                 (int)strcspn(init_utsname()->version, " "),
589                 init_utsname()->version,
590                 print_tainted());
591 }
592
593 static int very_verbose(struct lock_class *class)
594 {
595 #if VERY_VERBOSE
596         return class_filter(class);
597 #endif
598         return 0;
599 }
600
601 /*
602  * Is this the address of a static object:
603  */
604 #ifdef __KERNEL__
605 static int static_obj(void *obj)
606 {
607         unsigned long start = (unsigned long) &_stext,
608                       end   = (unsigned long) &_end,
609                       addr  = (unsigned long) obj;
610
611         /*
612          * static variable?
613          */
614         if ((addr >= start) && (addr < end))
615                 return 1;
616
617         if (arch_is_kernel_data(addr))
618                 return 1;
619
620         /*
621          * in-kernel percpu var?
622          */
623         if (is_kernel_percpu_address(addr))
624                 return 1;
625
626         /*
627          * module static or percpu var?
628          */
629         return is_module_address(addr) || is_module_percpu_address(addr);
630 }
631 #endif
632
633 /*
634  * To make lock name printouts unique, we calculate a unique
635  * class->name_version generation counter:
636  */
637 static int count_matching_names(struct lock_class *new_class)
638 {
639         struct lock_class *class;
640         int count = 0;
641
642         if (!new_class->name)
643                 return 0;
644
645         list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
646                 if (new_class->key - new_class->subclass == class->key)
647                         return class->name_version;
648                 if (class->name && !strcmp(class->name, new_class->name))
649                         count = max(count, class->name_version);
650         }
651
652         return count + 1;
653 }
654
655 /*
656  * Register a lock's class in the hash-table, if the class is not present
657  * yet. Otherwise we look it up. We cache the result in the lock object
658  * itself, so actual lookup of the hash should be once per lock object.
659  */
660 static inline struct lock_class *
661 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
662 {
663         struct lockdep_subclass_key *key;
664         struct hlist_head *hash_head;
665         struct lock_class *class;
666         bool is_static = false;
667
668         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
669                 debug_locks_off();
670                 printk(KERN_ERR
671                         "BUG: looking up invalid subclass: %u\n", subclass);
672                 printk(KERN_ERR
673                         "turning off the locking correctness validator.\n");
674                 dump_stack();
675                 return NULL;
676         }
677
678         /*
679          * Static locks do not have their class-keys yet - for them the key
680          * is the lock object itself. If the lock is in the per cpu area,
681          * the canonical address of the lock (per cpu offset removed) is
682          * used.
683          */
684         if (unlikely(!lock->key)) {
685                 unsigned long can_addr, addr = (unsigned long)lock;
686
687                 if (__is_kernel_percpu_address(addr, &can_addr))
688                         lock->key = (void *)can_addr;
689                 else if (__is_module_percpu_address(addr, &can_addr))
690                         lock->key = (void *)can_addr;
691                 else if (static_obj(lock))
692                         lock->key = (void *)lock;
693                 else
694                         return ERR_PTR(-EINVAL);
695                 is_static = true;
696         }
697
698         /*
699          * NOTE: the class-key must be unique. For dynamic locks, a static
700          * lock_class_key variable is passed in through the mutex_init()
701          * (or spin_lock_init()) call - which acts as the key. For static
702          * locks we use the lock object itself as the key.
703          */
704         BUILD_BUG_ON(sizeof(struct lock_class_key) >
705                         sizeof(struct lockdep_map));
706
707         key = lock->key->subkeys + subclass;
708
709         hash_head = classhashentry(key);
710
711         /*
712          * We do an RCU walk of the hash, see lockdep_free_key_range().
713          */
714         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
715                 return NULL;
716
717         hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
718                 if (class->key == key) {
719                         /*
720                          * Huh! same key, different name? Did someone trample
721                          * on some memory? We're most confused.
722                          */
723                         WARN_ON_ONCE(class->name != lock->name);
724                         return class;
725                 }
726         }
727
728         return is_static || static_obj(lock->key) ? NULL : ERR_PTR(-EINVAL);
729 }
730
731 #ifdef CONFIG_LOCKDEP_CROSSRELEASE
732 static void cross_init(struct lockdep_map *lock, int cross);
733 static int cross_lock(struct lockdep_map *lock);
734 static int lock_acquire_crosslock(struct held_lock *hlock);
735 static int lock_release_crosslock(struct lockdep_map *lock);
736 #else
737 static inline void cross_init(struct lockdep_map *lock, int cross) {}
738 static inline int cross_lock(struct lockdep_map *lock) { return 0; }
739 static inline int lock_acquire_crosslock(struct held_lock *hlock) { return 2; }
740 static inline int lock_release_crosslock(struct lockdep_map *lock) { return 2; }
741 #endif
742
743 /*
744  * Register a lock's class in the hash-table, if the class is not present
745  * yet. Otherwise we look it up. We cache the result in the lock object
746  * itself, so actual lookup of the hash should be once per lock object.
747  */
748 static struct lock_class *
749 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
750 {
751         struct lockdep_subclass_key *key;
752         struct hlist_head *hash_head;
753         struct lock_class *class;
754
755         DEBUG_LOCKS_WARN_ON(!irqs_disabled());
756
757         class = look_up_lock_class(lock, subclass);
758         if (likely(!IS_ERR_OR_NULL(class)))
759                 goto out_set_class_cache;
760
761         /*
762          * Debug-check: all keys must be persistent!
763          */
764         if (IS_ERR(class)) {
765                 debug_locks_off();
766                 printk("INFO: trying to register non-static key.\n");
767                 printk("the code is fine but needs lockdep annotation.\n");
768                 printk("turning off the locking correctness validator.\n");
769                 dump_stack();
770                 return NULL;
771         }
772
773         key = lock->key->subkeys + subclass;
774         hash_head = classhashentry(key);
775
776         if (!graph_lock()) {
777                 return NULL;
778         }
779         /*
780          * We have to do the hash-walk again, to avoid races
781          * with another CPU:
782          */
783         hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
784                 if (class->key == key)
785                         goto out_unlock_set;
786         }
787
788         /*
789          * Allocate a new key from the static array, and add it to
790          * the hash:
791          */
792         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
793                 if (!debug_locks_off_graph_unlock()) {
794                         return NULL;
795                 }
796
797                 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
798                 dump_stack();
799                 return NULL;
800         }
801         class = lock_classes + nr_lock_classes++;
802         debug_atomic_inc(nr_unused_locks);
803         class->key = key;
804         class->name = lock->name;
805         class->subclass = subclass;
806         INIT_LIST_HEAD(&class->lock_entry);
807         INIT_LIST_HEAD(&class->locks_before);
808         INIT_LIST_HEAD(&class->locks_after);
809         class->name_version = count_matching_names(class);
810         /*
811          * We use RCU's safe list-add method to make
812          * parallel walking of the hash-list safe:
813          */
814         hlist_add_head_rcu(&class->hash_entry, hash_head);
815         /*
816          * Add it to the global list of classes:
817          */
818         list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
819
820         if (verbose(class)) {
821                 graph_unlock();
822
823                 printk("\nnew class %p: %s", class->key, class->name);
824                 if (class->name_version > 1)
825                         printk(KERN_CONT "#%d", class->name_version);
826                 printk(KERN_CONT "\n");
827                 dump_stack();
828
829                 if (!graph_lock()) {
830                         return NULL;
831                 }
832         }
833 out_unlock_set:
834         graph_unlock();
835
836 out_set_class_cache:
837         if (!subclass || force)
838                 lock->class_cache[0] = class;
839         else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
840                 lock->class_cache[subclass] = class;
841
842         /*
843          * Hash collision, did we smoke some? We found a class with a matching
844          * hash but the subclass -- which is hashed in -- didn't match.
845          */
846         if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
847                 return NULL;
848
849         return class;
850 }
851
852 #ifdef CONFIG_PROVE_LOCKING
853 /*
854  * Allocate a lockdep entry. (assumes the graph_lock held, returns
855  * with NULL on failure)
856  */
857 static struct lock_list *alloc_list_entry(void)
858 {
859         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
860                 if (!debug_locks_off_graph_unlock())
861                         return NULL;
862
863                 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
864                 dump_stack();
865                 return NULL;
866         }
867         return list_entries + nr_list_entries++;
868 }
869
870 /*
871  * Add a new dependency to the head of the list:
872  */
873 static int add_lock_to_list(struct lock_class *this, struct list_head *head,
874                             unsigned long ip, int distance,
875                             struct stack_trace *trace)
876 {
877         struct lock_list *entry;
878         /*
879          * Lock not present yet - get a new dependency struct and
880          * add it to the list:
881          */
882         entry = alloc_list_entry();
883         if (!entry)
884                 return 0;
885
886         entry->class = this;
887         entry->distance = distance;
888         entry->trace = *trace;
889         /*
890          * Both allocation and removal are done under the graph lock; but
891          * iteration is under RCU-sched; see look_up_lock_class() and
892          * lockdep_free_key_range().
893          */
894         list_add_tail_rcu(&entry->entry, head);
895
896         return 1;
897 }
898
899 /*
900  * For good efficiency of modular, we use power of 2
901  */
902 #define MAX_CIRCULAR_QUEUE_SIZE         4096UL
903 #define CQ_MASK                         (MAX_CIRCULAR_QUEUE_SIZE-1)
904
905 /*
906  * The circular_queue and helpers is used to implement the
907  * breadth-first search(BFS)algorithem, by which we can build
908  * the shortest path from the next lock to be acquired to the
909  * previous held lock if there is a circular between them.
910  */
911 struct circular_queue {
912         unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
913         unsigned int  front, rear;
914 };
915
916 static struct circular_queue lock_cq;
917
918 unsigned int max_bfs_queue_depth;
919
920 static unsigned int lockdep_dependency_gen_id;
921
922 static inline void __cq_init(struct circular_queue *cq)
923 {
924         cq->front = cq->rear = 0;
925         lockdep_dependency_gen_id++;
926 }
927
928 static inline int __cq_empty(struct circular_queue *cq)
929 {
930         return (cq->front == cq->rear);
931 }
932
933 static inline int __cq_full(struct circular_queue *cq)
934 {
935         return ((cq->rear + 1) & CQ_MASK) == cq->front;
936 }
937
938 static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
939 {
940         if (__cq_full(cq))
941                 return -1;
942
943         cq->element[cq->rear] = elem;
944         cq->rear = (cq->rear + 1) & CQ_MASK;
945         return 0;
946 }
947
948 static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
949 {
950         if (__cq_empty(cq))
951                 return -1;
952
953         *elem = cq->element[cq->front];
954         cq->front = (cq->front + 1) & CQ_MASK;
955         return 0;
956 }
957
958 static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
959 {
960         return (cq->rear - cq->front) & CQ_MASK;
961 }
962
963 static inline void mark_lock_accessed(struct lock_list *lock,
964                                         struct lock_list *parent)
965 {
966         unsigned long nr;
967
968         nr = lock - list_entries;
969         WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
970         lock->parent = parent;
971         lock->class->dep_gen_id = lockdep_dependency_gen_id;
972 }
973
974 static inline unsigned long lock_accessed(struct lock_list *lock)
975 {
976         unsigned long nr;
977
978         nr = lock - list_entries;
979         WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
980         return lock->class->dep_gen_id == lockdep_dependency_gen_id;
981 }
982
983 static inline struct lock_list *get_lock_parent(struct lock_list *child)
984 {
985         return child->parent;
986 }
987
988 static inline int get_lock_depth(struct lock_list *child)
989 {
990         int depth = 0;
991         struct lock_list *parent;
992
993         while ((parent = get_lock_parent(child))) {
994                 child = parent;
995                 depth++;
996         }
997         return depth;
998 }
999
1000 static int __bfs(struct lock_list *source_entry,
1001                  void *data,
1002                  int (*match)(struct lock_list *entry, void *data),
1003                  struct lock_list **target_entry,
1004                  int forward)
1005 {
1006         struct lock_list *entry;
1007         struct list_head *head;
1008         struct circular_queue *cq = &lock_cq;
1009         int ret = 1;
1010
1011         if (match(source_entry, data)) {
1012                 *target_entry = source_entry;
1013                 ret = 0;
1014                 goto exit;
1015         }
1016
1017         if (forward)
1018                 head = &source_entry->class->locks_after;
1019         else
1020                 head = &source_entry->class->locks_before;
1021
1022         if (list_empty(head))
1023                 goto exit;
1024
1025         __cq_init(cq);
1026         __cq_enqueue(cq, (unsigned long)source_entry);
1027
1028         while (!__cq_empty(cq)) {
1029                 struct lock_list *lock;
1030
1031                 __cq_dequeue(cq, (unsigned long *)&lock);
1032
1033                 if (!lock->class) {
1034                         ret = -2;
1035                         goto exit;
1036                 }
1037
1038                 if (forward)
1039                         head = &lock->class->locks_after;
1040                 else
1041                         head = &lock->class->locks_before;
1042
1043                 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1044
1045                 list_for_each_entry_rcu(entry, head, entry) {
1046                         if (!lock_accessed(entry)) {
1047                                 unsigned int cq_depth;
1048                                 mark_lock_accessed(entry, lock);
1049                                 if (match(entry, data)) {
1050                                         *target_entry = entry;
1051                                         ret = 0;
1052                                         goto exit;
1053                                 }
1054
1055                                 if (__cq_enqueue(cq, (unsigned long)entry)) {
1056                                         ret = -1;
1057                                         goto exit;
1058                                 }
1059                                 cq_depth = __cq_get_elem_count(cq);
1060                                 if (max_bfs_queue_depth < cq_depth)
1061                                         max_bfs_queue_depth = cq_depth;
1062                         }
1063                 }
1064         }
1065 exit:
1066         return ret;
1067 }
1068
1069 static inline int __bfs_forwards(struct lock_list *src_entry,
1070                         void *data,
1071                         int (*match)(struct lock_list *entry, void *data),
1072                         struct lock_list **target_entry)
1073 {
1074         return __bfs(src_entry, data, match, target_entry, 1);
1075
1076 }
1077
1078 static inline int __bfs_backwards(struct lock_list *src_entry,
1079                         void *data,
1080                         int (*match)(struct lock_list *entry, void *data),
1081                         struct lock_list **target_entry)
1082 {
1083         return __bfs(src_entry, data, match, target_entry, 0);
1084
1085 }
1086
1087 /*
1088  * Recursive, forwards-direction lock-dependency checking, used for
1089  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1090  * checking.
1091  */
1092
1093 /*
1094  * Print a dependency chain entry (this is only done when a deadlock
1095  * has been detected):
1096  */
1097 static noinline int
1098 print_circular_bug_entry(struct lock_list *target, int depth)
1099 {
1100         if (debug_locks_silent)
1101                 return 0;
1102         printk("\n-> #%u", depth);
1103         print_lock_name(target->class);
1104         printk(KERN_CONT ":\n");
1105         print_stack_trace(&target->trace, 6);
1106
1107         return 0;
1108 }
1109
1110 static void
1111 print_circular_lock_scenario(struct held_lock *src,
1112                              struct held_lock *tgt,
1113                              struct lock_list *prt)
1114 {
1115         struct lock_class *source = hlock_class(src);
1116         struct lock_class *target = hlock_class(tgt);
1117         struct lock_class *parent = prt->class;
1118
1119         /*
1120          * A direct locking problem where unsafe_class lock is taken
1121          * directly by safe_class lock, then all we need to show
1122          * is the deadlock scenario, as it is obvious that the
1123          * unsafe lock is taken under the safe lock.
1124          *
1125          * But if there is a chain instead, where the safe lock takes
1126          * an intermediate lock (middle_class) where this lock is
1127          * not the same as the safe lock, then the lock chain is
1128          * used to describe the problem. Otherwise we would need
1129          * to show a different CPU case for each link in the chain
1130          * from the safe_class lock to the unsafe_class lock.
1131          */
1132         if (parent != source) {
1133                 printk("Chain exists of:\n  ");
1134                 __print_lock_name(source);
1135                 printk(KERN_CONT " --> ");
1136                 __print_lock_name(parent);
1137                 printk(KERN_CONT " --> ");
1138                 __print_lock_name(target);
1139                 printk(KERN_CONT "\n\n");
1140         }
1141
1142         if (cross_lock(tgt->instance)) {
1143                 printk(" Possible unsafe locking scenario by crosslock:\n\n");
1144                 printk("       CPU0                    CPU1\n");
1145                 printk("       ----                    ----\n");
1146                 printk("  lock(");
1147                 __print_lock_name(parent);
1148                 printk(KERN_CONT ");\n");
1149                 printk("  lock(");
1150                 __print_lock_name(target);
1151                 printk(KERN_CONT ");\n");
1152                 printk("                               lock(");
1153                 __print_lock_name(source);
1154                 printk(KERN_CONT ");\n");
1155                 printk("                               unlock(");
1156                 __print_lock_name(target);
1157                 printk(KERN_CONT ");\n");
1158                 printk("\n *** DEADLOCK ***\n\n");
1159         } else {
1160                 printk(" Possible unsafe locking scenario:\n\n");
1161                 printk("       CPU0                    CPU1\n");
1162                 printk("       ----                    ----\n");
1163                 printk("  lock(");
1164                 __print_lock_name(target);
1165                 printk(KERN_CONT ");\n");
1166                 printk("                               lock(");
1167                 __print_lock_name(parent);
1168                 printk(KERN_CONT ");\n");
1169                 printk("                               lock(");
1170                 __print_lock_name(target);
1171                 printk(KERN_CONT ");\n");
1172                 printk("  lock(");
1173                 __print_lock_name(source);
1174                 printk(KERN_CONT ");\n");
1175                 printk("\n *** DEADLOCK ***\n\n");
1176         }
1177 }
1178
1179 /*
1180  * When a circular dependency is detected, print the
1181  * header first:
1182  */
1183 static noinline int
1184 print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1185                         struct held_lock *check_src,
1186                         struct held_lock *check_tgt)
1187 {
1188         struct task_struct *curr = current;
1189
1190         if (debug_locks_silent)
1191                 return 0;
1192
1193         pr_warn("\n");
1194         pr_warn("======================================================\n");
1195         pr_warn("WARNING: possible circular locking dependency detected\n");
1196         print_kernel_ident();
1197         pr_warn("------------------------------------------------------\n");
1198         pr_warn("%s/%d is trying to acquire lock:\n",
1199                 curr->comm, task_pid_nr(curr));
1200         print_lock(check_src);
1201
1202         if (cross_lock(check_tgt->instance))
1203                 pr_warn("\nbut now in release context of a crosslock acquired at the following:\n");
1204         else
1205                 pr_warn("\nbut task is already holding lock:\n");
1206
1207         print_lock(check_tgt);
1208         pr_warn("\nwhich lock already depends on the new lock.\n\n");
1209         pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
1210
1211         print_circular_bug_entry(entry, depth);
1212
1213         return 0;
1214 }
1215
1216 static inline int class_equal(struct lock_list *entry, void *data)
1217 {
1218         return entry->class == data;
1219 }
1220
1221 static noinline int print_circular_bug(struct lock_list *this,
1222                                 struct lock_list *target,
1223                                 struct held_lock *check_src,
1224                                 struct held_lock *check_tgt,
1225                                 struct stack_trace *trace)
1226 {
1227         struct task_struct *curr = current;
1228         struct lock_list *parent;
1229         struct lock_list *first_parent;
1230         int depth;
1231
1232         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1233                 return 0;
1234
1235         if (cross_lock(check_tgt->instance))
1236                 this->trace = *trace;
1237         else if (!save_trace(&this->trace))
1238                 return 0;
1239
1240         depth = get_lock_depth(target);
1241
1242         print_circular_bug_header(target, depth, check_src, check_tgt);
1243
1244         parent = get_lock_parent(target);
1245         first_parent = parent;
1246
1247         while (parent) {
1248                 print_circular_bug_entry(parent, --depth);
1249                 parent = get_lock_parent(parent);
1250         }
1251
1252         printk("\nother info that might help us debug this:\n\n");
1253         print_circular_lock_scenario(check_src, check_tgt,
1254                                      first_parent);
1255
1256         lockdep_print_held_locks(curr);
1257
1258         printk("\nstack backtrace:\n");
1259         dump_stack();
1260
1261         return 0;
1262 }
1263
1264 static noinline int print_bfs_bug(int ret)
1265 {
1266         if (!debug_locks_off_graph_unlock())
1267                 return 0;
1268
1269         /*
1270          * Breadth-first-search failed, graph got corrupted?
1271          */
1272         WARN(1, "lockdep bfs error:%d\n", ret);
1273
1274         return 0;
1275 }
1276
1277 static int noop_count(struct lock_list *entry, void *data)
1278 {
1279         (*(unsigned long *)data)++;
1280         return 0;
1281 }
1282
1283 static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1284 {
1285         unsigned long  count = 0;
1286         struct lock_list *uninitialized_var(target_entry);
1287
1288         __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1289
1290         return count;
1291 }
1292 unsigned long lockdep_count_forward_deps(struct lock_class *class)
1293 {
1294         unsigned long ret, flags;
1295         struct lock_list this;
1296
1297         this.parent = NULL;
1298         this.class = class;
1299
1300         local_irq_save(flags);
1301         arch_spin_lock(&lockdep_lock);
1302         ret = __lockdep_count_forward_deps(&this);
1303         arch_spin_unlock(&lockdep_lock);
1304         local_irq_restore(flags);
1305
1306         return ret;
1307 }
1308
1309 static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1310 {
1311         unsigned long  count = 0;
1312         struct lock_list *uninitialized_var(target_entry);
1313
1314         __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1315
1316         return count;
1317 }
1318
1319 unsigned long lockdep_count_backward_deps(struct lock_class *class)
1320 {
1321         unsigned long ret, flags;
1322         struct lock_list this;
1323
1324         this.parent = NULL;
1325         this.class = class;
1326
1327         local_irq_save(flags);
1328         arch_spin_lock(&lockdep_lock);
1329         ret = __lockdep_count_backward_deps(&this);
1330         arch_spin_unlock(&lockdep_lock);
1331         local_irq_restore(flags);
1332
1333         return ret;
1334 }
1335
1336 /*
1337  * Prove that the dependency graph starting at <entry> can not
1338  * lead to <target>. Print an error and return 0 if it does.
1339  */
1340 static noinline int
1341 check_noncircular(struct lock_list *root, struct lock_class *target,
1342                 struct lock_list **target_entry)
1343 {
1344         int result;
1345
1346         debug_atomic_inc(nr_cyclic_checks);
1347
1348         result = __bfs_forwards(root, target, class_equal, target_entry);
1349
1350         return result;
1351 }
1352
1353 static noinline int
1354 check_redundant(struct lock_list *root, struct lock_class *target,
1355                 struct lock_list **target_entry)
1356 {
1357         int result;
1358
1359         debug_atomic_inc(nr_redundant_checks);
1360
1361         result = __bfs_forwards(root, target, class_equal, target_entry);
1362
1363         return result;
1364 }
1365
1366 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1367 /*
1368  * Forwards and backwards subgraph searching, for the purposes of
1369  * proving that two subgraphs can be connected by a new dependency
1370  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1371  */
1372
1373 static inline int usage_match(struct lock_list *entry, void *bit)
1374 {
1375         return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1376 }
1377
1378
1379
1380 /*
1381  * Find a node in the forwards-direction dependency sub-graph starting
1382  * at @root->class that matches @bit.
1383  *
1384  * Return 0 if such a node exists in the subgraph, and put that node
1385  * into *@target_entry.
1386  *
1387  * Return 1 otherwise and keep *@target_entry unchanged.
1388  * Return <0 on error.
1389  */
1390 static int
1391 find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1392                         struct lock_list **target_entry)
1393 {
1394         int result;
1395
1396         debug_atomic_inc(nr_find_usage_forwards_checks);
1397
1398         result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1399
1400         return result;
1401 }
1402
1403 /*
1404  * Find a node in the backwards-direction dependency sub-graph starting
1405  * at @root->class that matches @bit.
1406  *
1407  * Return 0 if such a node exists in the subgraph, and put that node
1408  * into *@target_entry.
1409  *
1410  * Return 1 otherwise and keep *@target_entry unchanged.
1411  * Return <0 on error.
1412  */
1413 static int
1414 find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1415                         struct lock_list **target_entry)
1416 {
1417         int result;
1418
1419         debug_atomic_inc(nr_find_usage_backwards_checks);
1420
1421         result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1422
1423         return result;
1424 }
1425
1426 static void print_lock_class_header(struct lock_class *class, int depth)
1427 {
1428         int bit;
1429
1430         printk("%*s->", depth, "");
1431         print_lock_name(class);
1432         printk(KERN_CONT " ops: %lu", class->ops);
1433         printk(KERN_CONT " {\n");
1434
1435         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1436                 if (class->usage_mask & (1 << bit)) {
1437                         int len = depth;
1438
1439                         len += printk("%*s   %s", depth, "", usage_str[bit]);
1440                         len += printk(KERN_CONT " at:\n");
1441                         print_stack_trace(class->usage_traces + bit, len);
1442                 }
1443         }
1444         printk("%*s }\n", depth, "");
1445
1446         printk("%*s ... key      at: [<%p>] %pS\n",
1447                 depth, "", class->key, class->key);
1448 }
1449
1450 /*
1451  * printk the shortest lock dependencies from @start to @end in reverse order:
1452  */
1453 static void __used
1454 print_shortest_lock_dependencies(struct lock_list *leaf,
1455                                 struct lock_list *root)
1456 {
1457         struct lock_list *entry = leaf;
1458         int depth;
1459
1460         /*compute depth from generated tree by BFS*/
1461         depth = get_lock_depth(leaf);
1462
1463         do {
1464                 print_lock_class_header(entry->class, depth);
1465                 printk("%*s ... acquired at:\n", depth, "");
1466                 print_stack_trace(&entry->trace, 2);
1467                 printk("\n");
1468
1469                 if (depth == 0 && (entry != root)) {
1470                         printk("lockdep:%s bad path found in chain graph\n", __func__);
1471                         break;
1472                 }
1473
1474                 entry = get_lock_parent(entry);
1475                 depth--;
1476         } while (entry && (depth >= 0));
1477
1478         return;
1479 }
1480
1481 static void
1482 print_irq_lock_scenario(struct lock_list *safe_entry,
1483                         struct lock_list *unsafe_entry,
1484                         struct lock_class *prev_class,
1485                         struct lock_class *next_class)
1486 {
1487         struct lock_class *safe_class = safe_entry->class;
1488         struct lock_class *unsafe_class = unsafe_entry->class;
1489         struct lock_class *middle_class = prev_class;
1490
1491         if (middle_class == safe_class)
1492                 middle_class = next_class;
1493
1494         /*
1495          * A direct locking problem where unsafe_class lock is taken
1496          * directly by safe_class lock, then all we need to show
1497          * is the deadlock scenario, as it is obvious that the
1498          * unsafe lock is taken under the safe lock.
1499          *
1500          * But if there is a chain instead, where the safe lock takes
1501          * an intermediate lock (middle_class) where this lock is
1502          * not the same as the safe lock, then the lock chain is
1503          * used to describe the problem. Otherwise we would need
1504          * to show a different CPU case for each link in the chain
1505          * from the safe_class lock to the unsafe_class lock.
1506          */
1507         if (middle_class != unsafe_class) {
1508                 printk("Chain exists of:\n  ");
1509                 __print_lock_name(safe_class);
1510                 printk(KERN_CONT " --> ");
1511                 __print_lock_name(middle_class);
1512                 printk(KERN_CONT " --> ");
1513                 __print_lock_name(unsafe_class);
1514                 printk(KERN_CONT "\n\n");
1515         }
1516
1517         printk(" Possible interrupt unsafe locking scenario:\n\n");
1518         printk("       CPU0                    CPU1\n");
1519         printk("       ----                    ----\n");
1520         printk("  lock(");
1521         __print_lock_name(unsafe_class);
1522         printk(KERN_CONT ");\n");
1523         printk("                               local_irq_disable();\n");
1524         printk("                               lock(");
1525         __print_lock_name(safe_class);
1526         printk(KERN_CONT ");\n");
1527         printk("                               lock(");
1528         __print_lock_name(middle_class);
1529         printk(KERN_CONT ");\n");
1530         printk("  <Interrupt>\n");
1531         printk("    lock(");
1532         __print_lock_name(safe_class);
1533         printk(KERN_CONT ");\n");
1534         printk("\n *** DEADLOCK ***\n\n");
1535 }
1536
1537 static int
1538 print_bad_irq_dependency(struct task_struct *curr,
1539                          struct lock_list *prev_root,
1540                          struct lock_list *next_root,
1541                          struct lock_list *backwards_entry,
1542                          struct lock_list *forwards_entry,
1543                          struct held_lock *prev,
1544                          struct held_lock *next,
1545                          enum lock_usage_bit bit1,
1546                          enum lock_usage_bit bit2,
1547                          const char *irqclass)
1548 {
1549         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1550                 return 0;
1551
1552         pr_warn("\n");
1553         pr_warn("=====================================================\n");
1554         pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
1555                 irqclass, irqclass);
1556         print_kernel_ident();
1557         pr_warn("-----------------------------------------------------\n");
1558         pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1559                 curr->comm, task_pid_nr(curr),
1560                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1561                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1562                 curr->hardirqs_enabled,
1563                 curr->softirqs_enabled);
1564         print_lock(next);
1565
1566         pr_warn("\nand this task is already holding:\n");
1567         print_lock(prev);
1568         pr_warn("which would create a new lock dependency:\n");
1569         print_lock_name(hlock_class(prev));
1570         pr_cont(" ->");
1571         print_lock_name(hlock_class(next));
1572         pr_cont("\n");
1573
1574         pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
1575                 irqclass);
1576         print_lock_name(backwards_entry->class);
1577         pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
1578
1579         print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1580
1581         pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
1582         print_lock_name(forwards_entry->class);
1583         pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
1584         pr_warn("...");
1585
1586         print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1587
1588         pr_warn("\nother info that might help us debug this:\n\n");
1589         print_irq_lock_scenario(backwards_entry, forwards_entry,
1590                                 hlock_class(prev), hlock_class(next));
1591
1592         lockdep_print_held_locks(curr);
1593
1594         pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
1595         if (!save_trace(&prev_root->trace))
1596                 return 0;
1597         print_shortest_lock_dependencies(backwards_entry, prev_root);
1598
1599         pr_warn("\nthe dependencies between the lock to be acquired");
1600         pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
1601         if (!save_trace(&next_root->trace))
1602                 return 0;
1603         print_shortest_lock_dependencies(forwards_entry, next_root);
1604
1605         pr_warn("\nstack backtrace:\n");
1606         dump_stack();
1607
1608         return 0;
1609 }
1610
1611 static int
1612 check_usage(struct task_struct *curr, struct held_lock *prev,
1613             struct held_lock *next, enum lock_usage_bit bit_backwards,
1614             enum lock_usage_bit bit_forwards, const char *irqclass)
1615 {
1616         int ret;
1617         struct lock_list this, that;
1618         struct lock_list *uninitialized_var(target_entry);
1619         struct lock_list *uninitialized_var(target_entry1);
1620
1621         this.parent = NULL;
1622
1623         this.class = hlock_class(prev);
1624         ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1625         if (ret < 0)
1626                 return print_bfs_bug(ret);
1627         if (ret == 1)
1628                 return ret;
1629
1630         that.parent = NULL;
1631         that.class = hlock_class(next);
1632         ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1633         if (ret < 0)
1634                 return print_bfs_bug(ret);
1635         if (ret == 1)
1636                 return ret;
1637
1638         return print_bad_irq_dependency(curr, &this, &that,
1639                         target_entry, target_entry1,
1640                         prev, next,
1641                         bit_backwards, bit_forwards, irqclass);
1642 }
1643
1644 static const char *state_names[] = {
1645 #define LOCKDEP_STATE(__STATE) \
1646         __stringify(__STATE),
1647 #include "lockdep_states.h"
1648 #undef LOCKDEP_STATE
1649 };
1650
1651 static const char *state_rnames[] = {
1652 #define LOCKDEP_STATE(__STATE) \
1653         __stringify(__STATE)"-READ",
1654 #include "lockdep_states.h"
1655 #undef LOCKDEP_STATE
1656 };
1657
1658 static inline const char *state_name(enum lock_usage_bit bit)
1659 {
1660         return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1661 }
1662
1663 static int exclusive_bit(int new_bit)
1664 {
1665         /*
1666          * USED_IN
1667          * USED_IN_READ
1668          * ENABLED
1669          * ENABLED_READ
1670          *
1671          * bit 0 - write/read
1672          * bit 1 - used_in/enabled
1673          * bit 2+  state
1674          */
1675
1676         int state = new_bit & ~3;
1677         int dir = new_bit & 2;
1678
1679         /*
1680          * keep state, bit flip the direction and strip read.
1681          */
1682         return state | (dir ^ 2);
1683 }
1684
1685 static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1686                            struct held_lock *next, enum lock_usage_bit bit)
1687 {
1688         /*
1689          * Prove that the new dependency does not connect a hardirq-safe
1690          * lock with a hardirq-unsafe lock - to achieve this we search
1691          * the backwards-subgraph starting at <prev>, and the
1692          * forwards-subgraph starting at <next>:
1693          */
1694         if (!check_usage(curr, prev, next, bit,
1695                            exclusive_bit(bit), state_name(bit)))
1696                 return 0;
1697
1698         bit++; /* _READ */
1699
1700         /*
1701          * Prove that the new dependency does not connect a hardirq-safe-read
1702          * lock with a hardirq-unsafe lock - to achieve this we search
1703          * the backwards-subgraph starting at <prev>, and the
1704          * forwards-subgraph starting at <next>:
1705          */
1706         if (!check_usage(curr, prev, next, bit,
1707                            exclusive_bit(bit), state_name(bit)))
1708                 return 0;
1709
1710         return 1;
1711 }
1712
1713 static int
1714 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1715                 struct held_lock *next)
1716 {
1717 #define LOCKDEP_STATE(__STATE)                                          \
1718         if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1719                 return 0;
1720 #include "lockdep_states.h"
1721 #undef LOCKDEP_STATE
1722
1723         return 1;
1724 }
1725
1726 static void inc_chains(void)
1727 {
1728         if (current->hardirq_context)
1729                 nr_hardirq_chains++;
1730         else {
1731                 if (current->softirq_context)
1732                         nr_softirq_chains++;
1733                 else
1734                         nr_process_chains++;
1735         }
1736 }
1737
1738 #else
1739
1740 static inline int
1741 check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1742                 struct held_lock *next)
1743 {
1744         return 1;
1745 }
1746
1747 static inline void inc_chains(void)
1748 {
1749         nr_process_chains++;
1750 }
1751
1752 #endif
1753
1754 static void
1755 print_deadlock_scenario(struct held_lock *nxt,
1756                              struct held_lock *prv)
1757 {
1758         struct lock_class *next = hlock_class(nxt);
1759         struct lock_class *prev = hlock_class(prv);
1760
1761         printk(" Possible unsafe locking scenario:\n\n");
1762         printk("       CPU0\n");
1763         printk("       ----\n");
1764         printk("  lock(");
1765         __print_lock_name(prev);
1766         printk(KERN_CONT ");\n");
1767         printk("  lock(");
1768         __print_lock_name(next);
1769         printk(KERN_CONT ");\n");
1770         printk("\n *** DEADLOCK ***\n\n");
1771         printk(" May be due to missing lock nesting notation\n\n");
1772 }
1773
1774 static int
1775 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1776                    struct held_lock *next)
1777 {
1778         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1779                 return 0;
1780
1781         pr_warn("\n");
1782         pr_warn("============================================\n");
1783         pr_warn("WARNING: possible recursive locking detected\n");
1784         print_kernel_ident();
1785         pr_warn("--------------------------------------------\n");
1786         pr_warn("%s/%d is trying to acquire lock:\n",
1787                 curr->comm, task_pid_nr(curr));
1788         print_lock(next);
1789         pr_warn("\nbut task is already holding lock:\n");
1790         print_lock(prev);
1791
1792         pr_warn("\nother info that might help us debug this:\n");
1793         print_deadlock_scenario(next, prev);
1794         lockdep_print_held_locks(curr);
1795
1796         pr_warn("\nstack backtrace:\n");
1797         dump_stack();
1798
1799         return 0;
1800 }
1801
1802 /*
1803  * Check whether we are holding such a class already.
1804  *
1805  * (Note that this has to be done separately, because the graph cannot
1806  * detect such classes of deadlocks.)
1807  *
1808  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1809  */
1810 static int
1811 check_deadlock(struct task_struct *curr, struct held_lock *next,
1812                struct lockdep_map *next_instance, int read)
1813 {
1814         struct held_lock *prev;
1815         struct held_lock *nest = NULL;
1816         int i;
1817
1818         for (i = 0; i < curr->lockdep_depth; i++) {
1819                 prev = curr->held_locks + i;
1820
1821                 if (prev->instance == next->nest_lock)
1822                         nest = prev;
1823
1824                 if (hlock_class(prev) != hlock_class(next))
1825                         continue;
1826
1827                 /*
1828                  * Allow read-after-read recursion of the same
1829                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
1830                  */
1831                 if ((read == 2) && prev->read)
1832                         return 2;
1833
1834                 /*
1835                  * We're holding the nest_lock, which serializes this lock's
1836                  * nesting behaviour.
1837                  */
1838                 if (nest)
1839                         return 2;
1840
1841                 if (cross_lock(prev->instance))
1842                         continue;
1843
1844                 return print_deadlock_bug(curr, prev, next);
1845         }
1846         return 1;
1847 }
1848
1849 /*
1850  * There was a chain-cache miss, and we are about to add a new dependency
1851  * to a previous lock. We recursively validate the following rules:
1852  *
1853  *  - would the adding of the <prev> -> <next> dependency create a
1854  *    circular dependency in the graph? [== circular deadlock]
1855  *
1856  *  - does the new prev->next dependency connect any hardirq-safe lock
1857  *    (in the full backwards-subgraph starting at <prev>) with any
1858  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
1859  *    <next>)? [== illegal lock inversion with hardirq contexts]
1860  *
1861  *  - does the new prev->next dependency connect any softirq-safe lock
1862  *    (in the full backwards-subgraph starting at <prev>) with any
1863  *    softirq-unsafe lock (in the full forwards-subgraph starting at
1864  *    <next>)? [== illegal lock inversion with softirq contexts]
1865  *
1866  * any of these scenarios could lead to a deadlock.
1867  *
1868  * Then if all the validations pass, we add the forwards and backwards
1869  * dependency.
1870  */
1871 static int
1872 check_prev_add(struct task_struct *curr, struct held_lock *prev,
1873                struct held_lock *next, int distance, struct stack_trace *trace,
1874                int (*save)(struct stack_trace *trace))
1875 {
1876         struct lock_list *uninitialized_var(target_entry);
1877         struct lock_list *entry;
1878         struct lock_list this;
1879         int ret;
1880
1881         /*
1882          * Prove that the new <prev> -> <next> dependency would not
1883          * create a circular dependency in the graph. (We do this by
1884          * forward-recursing into the graph starting at <next>, and
1885          * checking whether we can reach <prev>.)
1886          *
1887          * We are using global variables to control the recursion, to
1888          * keep the stackframe size of the recursive functions low:
1889          */
1890         this.class = hlock_class(next);
1891         this.parent = NULL;
1892         ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1893         if (unlikely(!ret)) {
1894                 if (!trace->entries) {
1895                         /*
1896                          * If @save fails here, the printing might trigger
1897                          * a WARN but because of the !nr_entries it should
1898                          * not do bad things.
1899                          */
1900                         save(trace);
1901                 }
1902                 return print_circular_bug(&this, target_entry, next, prev, trace);
1903         }
1904         else if (unlikely(ret < 0))
1905                 return print_bfs_bug(ret);
1906
1907         if (!check_prev_add_irq(curr, prev, next))
1908                 return 0;
1909
1910         /*
1911          * For recursive read-locks we do all the dependency checks,
1912          * but we dont store read-triggered dependencies (only
1913          * write-triggered dependencies). This ensures that only the
1914          * write-side dependencies matter, and that if for example a
1915          * write-lock never takes any other locks, then the reads are
1916          * equivalent to a NOP.
1917          */
1918         if (next->read == 2 || prev->read == 2)
1919                 return 1;
1920         /*
1921          * Is the <prev> -> <next> dependency already present?
1922          *
1923          * (this may occur even though this is a new chain: consider
1924          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1925          *  chains - the second one will be new, but L1 already has
1926          *  L2 added to its dependency list, due to the first chain.)
1927          */
1928         list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1929                 if (entry->class == hlock_class(next)) {
1930                         if (distance == 1)
1931                                 entry->distance = 1;
1932                         return 1;
1933                 }
1934         }
1935
1936         /*
1937          * Is the <prev> -> <next> link redundant?
1938          */
1939         this.class = hlock_class(prev);
1940         this.parent = NULL;
1941         ret = check_redundant(&this, hlock_class(next), &target_entry);
1942         if (!ret) {
1943                 debug_atomic_inc(nr_redundant);
1944                 return 2;
1945         }
1946         if (ret < 0)
1947                 return print_bfs_bug(ret);
1948
1949
1950         if (!trace->entries && !save(trace))
1951                 return 0;
1952
1953         /*
1954          * Ok, all validations passed, add the new lock
1955          * to the previous lock's dependency list:
1956          */
1957         ret = add_lock_to_list(hlock_class(next),
1958                                &hlock_class(prev)->locks_after,
1959                                next->acquire_ip, distance, trace);
1960
1961         if (!ret)
1962                 return 0;
1963
1964         ret = add_lock_to_list(hlock_class(prev),
1965                                &hlock_class(next)->locks_before,
1966                                next->acquire_ip, distance, trace);
1967         if (!ret)
1968                 return 0;
1969
1970         return 2;
1971 }
1972
1973 /*
1974  * Add the dependency to all directly-previous locks that are 'relevant'.
1975  * The ones that are relevant are (in increasing distance from curr):
1976  * all consecutive trylock entries and the final non-trylock entry - or
1977  * the end of this context's lock-chain - whichever comes first.
1978  */
1979 static int
1980 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1981 {
1982         int depth = curr->lockdep_depth;
1983         struct held_lock *hlock;
1984         struct stack_trace trace = {
1985                 .nr_entries = 0,
1986                 .max_entries = 0,
1987                 .entries = NULL,
1988                 .skip = 0,
1989         };
1990
1991         /*
1992          * Debugging checks.
1993          *
1994          * Depth must not be zero for a non-head lock:
1995          */
1996         if (!depth)
1997                 goto out_bug;
1998         /*
1999          * At least two relevant locks must exist for this
2000          * to be a head:
2001          */
2002         if (curr->held_locks[depth].irq_context !=
2003                         curr->held_locks[depth-1].irq_context)
2004                 goto out_bug;
2005
2006         for (;;) {
2007                 int distance = curr->lockdep_depth - depth + 1;
2008                 hlock = curr->held_locks + depth - 1;
2009                 /*
2010                  * Only non-crosslock entries get new dependencies added.
2011                  * Crosslock entries will be added by commit later:
2012                  */
2013                 if (!cross_lock(hlock->instance)) {
2014                         /*
2015                          * Only non-recursive-read entries get new dependencies
2016                          * added:
2017                          */
2018                         if (hlock->read != 2 && hlock->check) {
2019                                 int ret = check_prev_add(curr, hlock, next,
2020                                                          distance, &trace, save_trace);
2021                                 if (!ret)
2022                                         return 0;
2023
2024                                 /*
2025                                  * Stop after the first non-trylock entry,
2026                                  * as non-trylock entries have added their
2027                                  * own direct dependencies already, so this
2028                                  * lock is connected to them indirectly:
2029                                  */
2030                                 if (!hlock->trylock)
2031                                         break;
2032                         }
2033                 }
2034                 depth--;
2035                 /*
2036                  * End of lock-stack?
2037                  */
2038                 if (!depth)
2039                         break;
2040                 /*
2041                  * Stop the search if we cross into another context:
2042                  */
2043                 if (curr->held_locks[depth].irq_context !=
2044                                 curr->held_locks[depth-1].irq_context)
2045                         break;
2046         }
2047         return 1;
2048 out_bug:
2049         if (!debug_locks_off_graph_unlock())
2050                 return 0;
2051
2052         /*
2053          * Clearly we all shouldn't be here, but since we made it we
2054          * can reliable say we messed up our state. See the above two
2055          * gotos for reasons why we could possibly end up here.
2056          */
2057         WARN_ON(1);
2058
2059         return 0;
2060 }
2061
2062 unsigned long nr_lock_chains;
2063 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
2064 int nr_chain_hlocks;
2065 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
2066
2067 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
2068 {
2069         return lock_classes + chain_hlocks[chain->base + i];
2070 }
2071
2072 /*
2073  * Returns the index of the first held_lock of the current chain
2074  */
2075 static inline int get_first_held_lock(struct task_struct *curr,
2076                                         struct held_lock *hlock)
2077 {
2078         int i;
2079         struct held_lock *hlock_curr;
2080
2081         for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2082                 hlock_curr = curr->held_locks + i;
2083                 if (hlock_curr->irq_context != hlock->irq_context)
2084                         break;
2085
2086         }
2087
2088         return ++i;
2089 }
2090
2091 #ifdef CONFIG_DEBUG_LOCKDEP
2092 /*
2093  * Returns the next chain_key iteration
2094  */
2095 static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
2096 {
2097         u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
2098
2099         printk(" class_idx:%d -> chain_key:%016Lx",
2100                 class_idx,
2101                 (unsigned long long)new_chain_key);
2102         return new_chain_key;
2103 }
2104
2105 static void
2106 print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
2107 {
2108         struct held_lock *hlock;
2109         u64 chain_key = 0;
2110         int depth = curr->lockdep_depth;
2111         int i;
2112
2113         printk("depth: %u\n", depth + 1);
2114         for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
2115                 hlock = curr->held_locks + i;
2116                 chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
2117
2118                 print_lock(hlock);
2119         }
2120
2121         print_chain_key_iteration(hlock_next->class_idx, chain_key);
2122         print_lock(hlock_next);
2123 }
2124
2125 static void print_chain_keys_chain(struct lock_chain *chain)
2126 {
2127         int i;
2128         u64 chain_key = 0;
2129         int class_id;
2130
2131         printk("depth: %u\n", chain->depth);
2132         for (i = 0; i < chain->depth; i++) {
2133                 class_id = chain_hlocks[chain->base + i];
2134                 chain_key = print_chain_key_iteration(class_id + 1, chain_key);
2135
2136                 print_lock_name(lock_classes + class_id);
2137                 printk("\n");
2138         }
2139 }
2140
2141 static void print_collision(struct task_struct *curr,
2142                         struct held_lock *hlock_next,
2143                         struct lock_chain *chain)
2144 {
2145         pr_warn("\n");
2146         pr_warn("============================\n");
2147         pr_warn("WARNING: chain_key collision\n");
2148         print_kernel_ident();
2149         pr_warn("----------------------------\n");
2150         pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
2151         pr_warn("Hash chain already cached but the contents don't match!\n");
2152
2153         pr_warn("Held locks:");
2154         print_chain_keys_held_locks(curr, hlock_next);
2155
2156         pr_warn("Locks in cached chain:");
2157         print_chain_keys_chain(chain);
2158
2159         pr_warn("\nstack backtrace:\n");
2160         dump_stack();
2161 }
2162 #endif
2163
2164 /*
2165  * Checks whether the chain and the current held locks are consistent
2166  * in depth and also in content. If they are not it most likely means
2167  * that there was a collision during the calculation of the chain_key.
2168  * Returns: 0 not passed, 1 passed
2169  */
2170 static int check_no_collision(struct task_struct *curr,
2171                         struct held_lock *hlock,
2172                         struct lock_chain *chain)
2173 {
2174 #ifdef CONFIG_DEBUG_LOCKDEP
2175         int i, j, id;
2176
2177         i = get_first_held_lock(curr, hlock);
2178
2179         if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
2180                 print_collision(curr, hlock, chain);
2181                 return 0;
2182         }
2183
2184         for (j = 0; j < chain->depth - 1; j++, i++) {
2185                 id = curr->held_locks[i].class_idx - 1;
2186
2187                 if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
2188                         print_collision(curr, hlock, chain);
2189                         return 0;
2190                 }
2191         }
2192 #endif
2193         return 1;
2194 }
2195
2196 /*
2197  * This is for building a chain between just two different classes,
2198  * instead of adding a new hlock upon current, which is done by
2199  * add_chain_cache().
2200  *
2201  * This can be called in any context with two classes, while
2202  * add_chain_cache() must be done within the lock owener's context
2203  * since it uses hlock which might be racy in another context.
2204  */
2205 static inline int add_chain_cache_classes(unsigned int prev,
2206                                           unsigned int next,
2207                                           unsigned int irq_context,
2208                                           u64 chain_key)
2209 {
2210         struct hlist_head *hash_head = chainhashentry(chain_key);
2211         struct lock_chain *chain;
2212
2213         /*
2214          * Allocate a new chain entry from the static array, and add
2215          * it to the hash:
2216          */
2217
2218         /*
2219          * We might need to take the graph lock, ensure we've got IRQs
2220          * disabled to make this an IRQ-safe lock.. for recursion reasons
2221          * lockdep won't complain about its own locking errors.
2222          */
2223         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2224                 return 0;
2225
2226         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2227                 if (!debug_locks_off_graph_unlock())
2228                         return 0;
2229
2230                 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2231                 dump_stack();
2232                 return 0;
2233         }
2234
2235         chain = lock_chains + nr_lock_chains++;
2236         chain->chain_key = chain_key;
2237         chain->irq_context = irq_context;
2238         chain->depth = 2;
2239         if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2240                 chain->base = nr_chain_hlocks;
2241                 nr_chain_hlocks += chain->depth;
2242                 chain_hlocks[chain->base] = prev - 1;
2243                 chain_hlocks[chain->base + 1] = next -1;
2244         }
2245 #ifdef CONFIG_DEBUG_LOCKDEP
2246         /*
2247          * Important for check_no_collision().
2248          */
2249         else {
2250                 if (!debug_locks_off_graph_unlock())
2251                         return 0;
2252
2253                 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2254                 dump_stack();
2255                 return 0;
2256         }
2257 #endif
2258
2259         hlist_add_head_rcu(&chain->entry, hash_head);
2260         debug_atomic_inc(chain_lookup_misses);
2261         inc_chains();
2262
2263         return 1;
2264 }
2265
2266 /*
2267  * Adds a dependency chain into chain hashtable. And must be called with
2268  * graph_lock held.
2269  *
2270  * Return 0 if fail, and graph_lock is released.
2271  * Return 1 if succeed, with graph_lock held.
2272  */
2273 static inline int add_chain_cache(struct task_struct *curr,
2274                                   struct held_lock *hlock,
2275                                   u64 chain_key)
2276 {
2277         struct lock_class *class = hlock_class(hlock);
2278         struct hlist_head *hash_head = chainhashentry(chain_key);
2279         struct lock_chain *chain;
2280         int i, j;
2281
2282         /*
2283          * Allocate a new chain entry from the static array, and add
2284          * it to the hash:
2285          */
2286
2287         /*
2288          * We might need to take the graph lock, ensure we've got IRQs
2289          * disabled to make this an IRQ-safe lock.. for recursion reasons
2290          * lockdep won't complain about its own locking errors.
2291          */
2292         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2293                 return 0;
2294
2295         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2296                 if (!debug_locks_off_graph_unlock())
2297                         return 0;
2298
2299                 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2300                 dump_stack();
2301                 return 0;
2302         }
2303         chain = lock_chains + nr_lock_chains++;
2304         chain->chain_key = chain_key;
2305         chain->irq_context = hlock->irq_context;
2306         i = get_first_held_lock(curr, hlock);
2307         chain->depth = curr->lockdep_depth + 1 - i;
2308
2309         BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
2310         BUILD_BUG_ON((1UL << 6)  <= ARRAY_SIZE(curr->held_locks));
2311         BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
2312
2313         if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2314                 chain->base = nr_chain_hlocks;
2315                 for (j = 0; j < chain->depth - 1; j++, i++) {
2316                         int lock_id = curr->held_locks[i].class_idx - 1;
2317                         chain_hlocks[chain->base + j] = lock_id;
2318                 }
2319                 chain_hlocks[chain->base + j] = class - lock_classes;
2320         }
2321
2322         if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
2323                 nr_chain_hlocks += chain->depth;
2324
2325 #ifdef CONFIG_DEBUG_LOCKDEP
2326         /*
2327          * Important for check_no_collision().
2328          */
2329         if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
2330                 if (!debug_locks_off_graph_unlock())
2331                         return 0;
2332
2333                 print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
2334                 dump_stack();
2335                 return 0;
2336         }
2337 #endif
2338
2339         hlist_add_head_rcu(&chain->entry, hash_head);
2340         debug_atomic_inc(chain_lookup_misses);
2341         inc_chains();
2342
2343         return 1;
2344 }
2345
2346 /*
2347  * Look up a dependency chain.
2348  */
2349 static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
2350 {
2351         struct hlist_head *hash_head = chainhashentry(chain_key);
2352         struct lock_chain *chain;
2353
2354         /*
2355          * We can walk it lock-free, because entries only get added
2356          * to the hash:
2357          */
2358         hlist_for_each_entry_rcu(chain, hash_head, entry) {
2359                 if (chain->chain_key == chain_key) {
2360                         debug_atomic_inc(chain_lookup_hits);
2361                         return chain;
2362                 }
2363         }
2364         return NULL;
2365 }
2366
2367 /*
2368  * If the key is not present yet in dependency chain cache then
2369  * add it and return 1 - in this case the new dependency chain is
2370  * validated. If the key is already hashed, return 0.
2371  * (On return with 1 graph_lock is held.)
2372  */
2373 static inline int lookup_chain_cache_add(struct task_struct *curr,
2374                                          struct held_lock *hlock,
2375                                          u64 chain_key)
2376 {
2377         struct lock_class *class = hlock_class(hlock);
2378         struct lock_chain *chain = lookup_chain_cache(chain_key);
2379
2380         if (chain) {
2381 cache_hit:
2382                 if (!check_no_collision(curr, hlock, chain))
2383                         return 0;
2384
2385                 if (very_verbose(class)) {
2386                         printk("\nhash chain already cached, key: "
2387                                         "%016Lx tail class: [%p] %s\n",
2388                                         (unsigned long long)chain_key,
2389                                         class->key, class->name);
2390                 }
2391
2392                 return 0;
2393         }
2394
2395         if (very_verbose(class)) {
2396                 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2397                         (unsigned long long)chain_key, class->key, class->name);
2398         }
2399
2400         if (!graph_lock())
2401                 return 0;
2402
2403         /*
2404          * We have to walk the chain again locked - to avoid duplicates:
2405          */
2406         chain = lookup_chain_cache(chain_key);
2407         if (chain) {
2408                 graph_unlock();
2409                 goto cache_hit;
2410         }
2411
2412         if (!add_chain_cache(curr, hlock, chain_key))
2413                 return 0;
2414
2415         return 1;
2416 }
2417
2418 static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2419                 struct held_lock *hlock, int chain_head, u64 chain_key)
2420 {
2421         /*
2422          * Trylock needs to maintain the stack of held locks, but it
2423          * does not add new dependencies, because trylock can be done
2424          * in any order.
2425          *
2426          * We look up the chain_key and do the O(N^2) check and update of
2427          * the dependencies only if this is a new dependency chain.
2428          * (If lookup_chain_cache_add() return with 1 it acquires
2429          * graph_lock for us)
2430          */
2431         if (!hlock->trylock && hlock->check &&
2432             lookup_chain_cache_add(curr, hlock, chain_key)) {
2433                 /*
2434                  * Check whether last held lock:
2435                  *
2436                  * - is irq-safe, if this lock is irq-unsafe
2437                  * - is softirq-safe, if this lock is hardirq-unsafe
2438                  *
2439                  * And check whether the new lock's dependency graph
2440                  * could lead back to the previous lock.
2441                  *
2442                  * any of these scenarios could lead to a deadlock. If
2443                  * All validations
2444                  */
2445                 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2446
2447                 if (!ret)
2448                         return 0;
2449                 /*
2450                  * Mark recursive read, as we jump over it when
2451                  * building dependencies (just like we jump over
2452                  * trylock entries):
2453                  */
2454                 if (ret == 2)
2455                         hlock->read = 2;
2456                 /*
2457                  * Add dependency only if this lock is not the head
2458                  * of the chain, and if it's not a secondary read-lock:
2459                  */
2460                 if (!chain_head && ret != 2) {
2461                         if (!check_prevs_add(curr, hlock))
2462                                 return 0;
2463                 }
2464
2465                 graph_unlock();
2466         } else {
2467                 /* after lookup_chain_cache_add(): */
2468                 if (unlikely(!debug_locks))
2469                         return 0;
2470         }
2471
2472         return 1;
2473 }
2474 #else
2475 static inline int validate_chain(struct task_struct *curr,
2476                 struct lockdep_map *lock, struct held_lock *hlock,
2477                 int chain_head, u64 chain_key)
2478 {
2479         return 1;
2480 }
2481 #endif
2482
2483 /*
2484  * We are building curr_chain_key incrementally, so double-check
2485  * it from scratch, to make sure that it's done correctly:
2486  */
2487 static void check_chain_key(struct task_struct *curr)
2488 {
2489 #ifdef CONFIG_DEBUG_LOCKDEP
2490         struct held_lock *hlock, *prev_hlock = NULL;
2491         unsigned int i;
2492         u64 chain_key = 0;
2493
2494         for (i = 0; i < curr->lockdep_depth; i++) {
2495                 hlock = curr->held_locks + i;
2496                 if (chain_key != hlock->prev_chain_key) {
2497                         debug_locks_off();
2498                         /*
2499                          * We got mighty confused, our chain keys don't match
2500                          * with what we expect, someone trample on our task state?
2501                          */
2502                         WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2503                                 curr->lockdep_depth, i,
2504                                 (unsigned long long)chain_key,
2505                                 (unsigned long long)hlock->prev_chain_key);
2506                         return;
2507                 }
2508                 /*
2509                  * Whoops ran out of static storage again?
2510                  */
2511                 if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
2512                         return;
2513
2514                 if (prev_hlock && (prev_hlock->irq_context !=
2515                                                         hlock->irq_context))
2516                         chain_key = 0;
2517                 chain_key = iterate_chain_key(chain_key, hlock->class_idx);
2518                 prev_hlock = hlock;
2519         }
2520         if (chain_key != curr->curr_chain_key) {
2521                 debug_locks_off();
2522                 /*
2523                  * More smoking hash instead of calculating it, damn see these
2524                  * numbers float.. I bet that a pink elephant stepped on my memory.
2525                  */
2526                 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2527                         curr->lockdep_depth, i,
2528                         (unsigned long long)chain_key,
2529                         (unsigned long long)curr->curr_chain_key);
2530         }
2531 #endif
2532 }
2533
2534 static void
2535 print_usage_bug_scenario(struct held_lock *lock)
2536 {
2537         struct lock_class *class = hlock_class(lock);
2538
2539         printk(" Possible unsafe locking scenario:\n\n");
2540         printk("       CPU0\n");
2541         printk("       ----\n");
2542         printk("  lock(");
2543         __print_lock_name(class);
2544         printk(KERN_CONT ");\n");
2545         printk("  <Interrupt>\n");
2546         printk("    lock(");
2547         __print_lock_name(class);
2548         printk(KERN_CONT ");\n");
2549         printk("\n *** DEADLOCK ***\n\n");
2550 }
2551
2552 static int
2553 print_usage_bug(struct task_struct *curr, struct held_lock *this,
2554                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2555 {
2556         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2557                 return 0;
2558
2559         pr_warn("\n");
2560         pr_warn("================================\n");
2561         pr_warn("WARNING: inconsistent lock state\n");
2562         print_kernel_ident();
2563         pr_warn("--------------------------------\n");
2564
2565         pr_warn("inconsistent {%s} -> {%s} usage.\n",
2566                 usage_str[prev_bit], usage_str[new_bit]);
2567
2568         pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2569                 curr->comm, task_pid_nr(curr),
2570                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2571                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2572                 trace_hardirqs_enabled(curr),
2573                 trace_softirqs_enabled(curr));
2574         print_lock(this);
2575
2576         pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
2577         print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2578
2579         print_irqtrace_events(curr);
2580         pr_warn("\nother info that might help us debug this:\n");
2581         print_usage_bug_scenario(this);
2582
2583         lockdep_print_held_locks(curr);
2584
2585         pr_warn("\nstack backtrace:\n");
2586         dump_stack();
2587
2588         return 0;
2589 }
2590
2591 /*
2592  * Print out an error if an invalid bit is set:
2593  */
2594 static inline int
2595 valid_state(struct task_struct *curr, struct held_lock *this,
2596             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2597 {
2598         if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2599                 return print_usage_bug(curr, this, bad_bit, new_bit);
2600         return 1;
2601 }
2602
2603 static int mark_lock(struct task_struct *curr, struct held_lock *this,
2604                      enum lock_usage_bit new_bit);
2605
2606 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2607
2608 /*
2609  * print irq inversion bug:
2610  */
2611 static int
2612 print_irq_inversion_bug(struct task_struct *curr,
2613                         struct lock_list *root, struct lock_list *other,
2614                         struct held_lock *this, int forwards,
2615                         const char *irqclass)
2616 {
2617         struct lock_list *entry = other;
2618         struct lock_list *middle = NULL;
2619         int depth;
2620
2621         if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2622                 return 0;
2623
2624         pr_warn("\n");
2625         pr_warn("========================================================\n");
2626         pr_warn("WARNING: possible irq lock inversion dependency detected\n");
2627         print_kernel_ident();
2628         pr_warn("--------------------------------------------------------\n");
2629         pr_warn("%s/%d just changed the state of lock:\n",
2630                 curr->comm, task_pid_nr(curr));
2631         print_lock(this);
2632         if (forwards)
2633                 pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2634         else
2635                 pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2636         print_lock_name(other->class);
2637         pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2638
2639         pr_warn("\nother info that might help us debug this:\n");
2640
2641         /* Find a middle lock (if one exists) */
2642         depth = get_lock_depth(other);
2643         do {
2644                 if (depth == 0 && (entry != root)) {
2645                         pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
2646                         break;
2647                 }
2648                 middle = entry;
2649                 entry = get_lock_parent(entry);
2650                 depth--;
2651         } while (entry && entry != root && (depth >= 0));
2652         if (forwards)
2653                 print_irq_lock_scenario(root, other,
2654                         middle ? middle->class : root->class, other->class);
2655         else
2656                 print_irq_lock_scenario(other, root,
2657                         middle ? middle->class : other->class, root->class);
2658
2659         lockdep_print_held_locks(curr);
2660
2661         pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2662         if (!save_trace(&root->trace))
2663                 return 0;
2664         print_shortest_lock_dependencies(other, root);
2665
2666         pr_warn("\nstack backtrace:\n");
2667         dump_stack();
2668
2669         return 0;
2670 }
2671
2672 /*
2673  * Prove that in the forwards-direction subgraph starting at <this>
2674  * there is no lock matching <mask>:
2675  */
2676 static int
2677 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2678                      enum lock_usage_bit bit, const char *irqclass)
2679 {
2680         int ret;
2681         struct lock_list root;
2682         struct lock_list *uninitialized_var(target_entry);
2683
2684         root.parent = NULL;
2685         root.class = hlock_class(this);
2686         ret = find_usage_forwards(&root, bit, &target_entry);
2687         if (ret < 0)
2688                 return print_bfs_bug(ret);
2689         if (ret == 1)
2690                 return ret;
2691
2692         return print_irq_inversion_bug(curr, &root, target_entry,
2693                                         this, 1, irqclass);
2694 }
2695
2696 /*
2697  * Prove that in the backwards-direction subgraph starting at <this>
2698  * there is no lock matching <mask>:
2699  */
2700 static int
2701 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2702                       enum lock_usage_bit bit, const char *irqclass)
2703 {
2704         int ret;
2705         struct lock_list root;
2706         struct lock_list *uninitialized_var(target_entry);
2707
2708         root.parent = NULL;
2709         root.class = hlock_class(this);
2710         ret = find_usage_backwards(&root, bit, &target_entry);
2711         if (ret < 0)
2712                 return print_bfs_bug(ret);
2713         if (ret == 1)
2714                 return ret;
2715
2716         return print_irq_inversion_bug(curr, &root, target_entry,
2717                                         this, 0, irqclass);
2718 }
2719
2720 void print_irqtrace_events(struct task_struct *curr)
2721 {
2722         printk("irq event stamp: %u\n", curr->irq_events);
2723         printk("hardirqs last  enabled at (%u): [<%p>] %pS\n",
2724                 curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
2725                 (void *)curr->hardirq_enable_ip);
2726         printk("hardirqs last disabled at (%u): [<%p>] %pS\n",
2727                 curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
2728                 (void *)curr->hardirq_disable_ip);
2729         printk("softirqs last  enabled at (%u): [<%p>] %pS\n",
2730                 curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
2731                 (void *)curr->softirq_enable_ip);
2732         printk("softirqs last disabled at (%u): [<%p>] %pS\n",
2733                 curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
2734                 (void *)curr->softirq_disable_ip);
2735 }
2736
2737 static int HARDIRQ_verbose(struct lock_class *class)
2738 {
2739 #if HARDIRQ_VERBOSE
2740         return class_filter(class);
2741 #endif
2742         return 0;
2743 }
2744
2745 static int SOFTIRQ_verbose(struct lock_class *class)
2746 {
2747 #if SOFTIRQ_VERBOSE
2748         return class_filter(class);
2749 #endif
2750         return 0;
2751 }
2752
2753 #define STRICT_READ_CHECKS      1
2754
2755 static int (*state_verbose_f[])(struct lock_class *class) = {
2756 #define LOCKDEP_STATE(__STATE) \
2757         __STATE##_verbose,
2758 #include "lockdep_states.h"
2759 #undef LOCKDEP_STATE
2760 };
2761
2762 static inline int state_verbose(enum lock_usage_bit bit,
2763                                 struct lock_class *class)
2764 {
2765         return state_verbose_f[bit >> 2](class);
2766 }
2767
2768 typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2769                              enum lock_usage_bit bit, const char *name);
2770
2771 static int
2772 mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2773                 enum lock_usage_bit new_bit)
2774 {
2775         int excl_bit = exclusive_bit(new_bit);
2776         int read = new_bit & 1;
2777         int dir = new_bit & 2;
2778
2779         /*
2780          * mark USED_IN has to look forwards -- to ensure no dependency
2781          * has ENABLED state, which would allow recursion deadlocks.
2782          *
2783          * mark ENABLED has to look backwards -- to ensure no dependee
2784          * has USED_IN state, which, again, would allow  recursion deadlocks.
2785          */
2786         check_usage_f usage = dir ?
2787                 check_usage_backwards : check_usage_forwards;
2788
2789         /*
2790          * Validate that this particular lock does not have conflicting
2791          * usage states.
2792          */
2793         if (!valid_state(curr, this, new_bit, excl_bit))
2794                 return 0;
2795
2796         /*
2797          * Validate that the lock dependencies don't have conflicting usage
2798          * states.
2799          */
2800         if ((!read || !dir || STRICT_READ_CHECKS) &&
2801                         !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2802                 return 0;
2803
2804         /*
2805          * Check for read in write conflicts
2806          */
2807         if (!read) {
2808                 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2809                         return 0;
2810
2811                 if (STRICT_READ_CHECKS &&
2812                         !usage(curr, this, excl_bit + 1,
2813                                 state_name(new_bit + 1)))
2814                         return 0;
2815         }
2816
2817         if (state_verbose(new_bit, hlock_class(this)))
2818                 return 2;
2819
2820         return 1;
2821 }
2822
2823 enum mark_type {
2824 #define LOCKDEP_STATE(__STATE)  __STATE,
2825 #include "lockdep_states.h"
2826 #undef LOCKDEP_STATE
2827 };
2828
2829 /*
2830  * Mark all held locks with a usage bit:
2831  */
2832 static int
2833 mark_held_locks(struct task_struct *curr, enum mark_type mark)
2834 {
2835         enum lock_usage_bit usage_bit;
2836         struct held_lock *hlock;
2837         int i;
2838
2839         for (i = 0; i < curr->lockdep_depth; i++) {
2840                 hlock = curr->held_locks + i;
2841
2842                 usage_bit = 2 + (mark << 2); /* ENABLED */
2843                 if (hlock->read)
2844                         usage_bit += 1; /* READ */
2845
2846                 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2847
2848                 if (!hlock->check)
2849                         continue;
2850
2851                 if (!mark_lock(curr, hlock, usage_bit))
2852                         return 0;
2853         }
2854
2855         return 1;
2856 }
2857
2858 /*
2859  * Hardirqs will be enabled:
2860  */
2861 static void __trace_hardirqs_on_caller(unsigned long ip)
2862 {
2863         struct task_struct *curr = current;
2864
2865         /* we'll do an OFF -> ON transition: */
2866         curr->hardirqs_enabled = 1;
2867
2868         /*
2869          * We are going to turn hardirqs on, so set the
2870          * usage bit for all held locks:
2871          */
2872         if (!mark_held_locks(curr, HARDIRQ))
2873                 return;
2874         /*
2875          * If we have softirqs enabled, then set the usage
2876          * bit for all held locks. (disabled hardirqs prevented
2877          * this bit from being set before)
2878          */
2879         if (curr->softirqs_enabled)
2880                 if (!mark_held_locks(curr, SOFTIRQ))
2881                         return;
2882
2883         curr->hardirq_enable_ip = ip;
2884         curr->hardirq_enable_event = ++curr->irq_events;
2885         debug_atomic_inc(hardirqs_on_events);
2886 }
2887
2888 __visible void trace_hardirqs_on_caller(unsigned long ip)
2889 {
2890         time_hardirqs_on(CALLER_ADDR0, ip);
2891
2892         if (unlikely(!debug_locks || current->lockdep_recursion))
2893                 return;
2894
2895         if (unlikely(current->hardirqs_enabled)) {
2896                 /*
2897                  * Neither irq nor preemption are disabled here
2898                  * so this is racy by nature but losing one hit
2899                  * in a stat is not a big deal.
2900                  */
2901                 __debug_atomic_inc(redundant_hardirqs_on);
2902                 return;
2903         }
2904
2905         /*
2906          * We're enabling irqs and according to our state above irqs weren't
2907          * already enabled, yet we find the hardware thinks they are in fact
2908          * enabled.. someone messed up their IRQ state tracing.
2909          */
2910         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2911                 return;
2912
2913         /*
2914          * See the fine text that goes along with this variable definition.
2915          */
2916         if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2917                 return;
2918
2919         /*
2920          * Can't allow enabling interrupts while in an interrupt handler,
2921          * that's general bad form and such. Recursion, limited stack etc..
2922          */
2923         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2924                 return;
2925
2926         current->lockdep_recursion = 1;
2927         __trace_hardirqs_on_caller(ip);
2928         current->lockdep_recursion = 0;
2929 }
2930 EXPORT_SYMBOL(trace_hardirqs_on_caller);
2931
2932 void trace_hardirqs_on(void)
2933 {
2934         trace_hardirqs_on_caller(CALLER_ADDR0);
2935 }
2936 EXPORT_SYMBOL(trace_hardirqs_on);
2937
2938 /*
2939  * Hardirqs were disabled:
2940  */
2941 __visible void trace_hardirqs_off_caller(unsigned long ip)
2942 {
2943         struct task_struct *curr = current;
2944
2945         time_hardirqs_off(CALLER_ADDR0, ip);
2946
2947         if (unlikely(!debug_locks || current->lockdep_recursion))
2948                 return;
2949
2950         /*
2951          * So we're supposed to get called after you mask local IRQs, but for
2952          * some reason the hardware doesn't quite think you did a proper job.
2953          */
2954         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2955                 return;
2956
2957         if (curr->hardirqs_enabled) {
2958                 /*
2959                  * We have done an ON -> OFF transition:
2960                  */
2961                 curr->hardirqs_enabled = 0;
2962                 curr->hardirq_disable_ip = ip;
2963                 curr->hardirq_disable_event = ++curr->irq_events;
2964                 debug_atomic_inc(hardirqs_off_events);
2965         } else
2966                 debug_atomic_inc(redundant_hardirqs_off);
2967 }
2968 EXPORT_SYMBOL(trace_hardirqs_off_caller);
2969
2970 void trace_hardirqs_off(void)
2971 {
2972         trace_hardirqs_off_caller(CALLER_ADDR0);
2973 }
2974 EXPORT_SYMBOL(trace_hardirqs_off);
2975
2976 /*
2977  * Softirqs will be enabled:
2978  */
2979 void trace_softirqs_on(unsigned long ip)
2980 {
2981         struct task_struct *curr = current;
2982
2983         if (unlikely(!debug_locks || current->lockdep_recursion))
2984                 return;
2985
2986         /*
2987          * We fancy IRQs being disabled here, see softirq.c, avoids
2988          * funny state and nesting things.
2989          */
2990         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2991                 return;
2992
2993         if (curr->softirqs_enabled) {
2994                 debug_atomic_inc(redundant_softirqs_on);
2995                 return;
2996         }
2997
2998         current->lockdep_recursion = 1;
2999         /*
3000          * We'll do an OFF -> ON transition:
3001          */
3002         curr->softirqs_enabled = 1;
3003         curr->softirq_enable_ip = ip;
3004         curr->softirq_enable_event = ++curr->irq_events;
3005         debug_atomic_inc(softirqs_on_events);
3006         /*
3007          * We are going to turn softirqs on, so set the
3008          * usage bit for all held locks, if hardirqs are
3009          * enabled too:
3010          */
3011         if (curr->hardirqs_enabled)
3012                 mark_held_locks(curr, SOFTIRQ);
3013         current->lockdep_recursion = 0;
3014 }
3015
3016 /*
3017  * Softirqs were disabled:
3018  */
3019 void trace_softirqs_off(unsigned long ip)
3020 {
3021         struct task_struct *curr = current;
3022
3023         if (unlikely(!debug_locks || current->lockdep_recursion))
3024                 return;
3025
3026         /*
3027          * We fancy IRQs being disabled here, see softirq.c
3028          */
3029         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3030                 return;
3031
3032         if (curr->softirqs_enabled) {
3033                 /*
3034                  * We have done an ON -> OFF transition:
3035                  */
3036                 curr->softirqs_enabled = 0;
3037                 curr->softirq_disable_ip = ip;
3038                 curr->softirq_disable_event = ++curr->irq_events;
3039                 debug_atomic_inc(softirqs_off_events);
3040                 /*
3041                  * Whoops, we wanted softirqs off, so why aren't they?
3042                  */
3043                 DEBUG_LOCKS_WARN_ON(!softirq_count());
3044         } else
3045                 debug_atomic_inc(redundant_softirqs_off);
3046 }
3047
3048 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
3049 {
3050         /*
3051          * If non-trylock use in a hardirq or softirq context, then
3052          * mark the lock as used in these contexts:
3053          */
3054         if (!hlock->trylock) {
3055                 if (hlock->read) {
3056                         if (curr->hardirq_context)
3057                                 if (!mark_lock(curr, hlock,
3058                                                 LOCK_USED_IN_HARDIRQ_READ))
3059                                         return 0;
3060                         if (curr->softirq_context)
3061                                 if (!mark_lock(curr, hlock,
3062                                                 LOCK_USED_IN_SOFTIRQ_READ))
3063                                         return 0;
3064                 } else {
3065                         if (curr->hardirq_context)
3066                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
3067                                         return 0;
3068                         if (curr->softirq_context)
3069                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
3070                                         return 0;
3071                 }
3072         }
3073         if (!hlock->hardirqs_off) {
3074                 if (hlock->read) {
3075                         if (!mark_lock(curr, hlock,
3076                                         LOCK_ENABLED_HARDIRQ_READ))
3077                                 return 0;
3078                         if (curr->softirqs_enabled)
3079                                 if (!mark_lock(curr, hlock,
3080                                                 LOCK_ENABLED_SOFTIRQ_READ))
3081                                         return 0;
3082                 } else {
3083                         if (!mark_lock(curr, hlock,
3084                                         LOCK_ENABLED_HARDIRQ))
3085                                 return 0;
3086                         if (curr->softirqs_enabled)
3087                                 if (!mark_lock(curr, hlock,
3088                                                 LOCK_ENABLED_SOFTIRQ))
3089                                         return 0;
3090                 }
3091         }
3092
3093         return 1;
3094 }
3095
3096 static inline unsigned int task_irq_context(struct task_struct *task)
3097 {
3098         return 2 * !!task->hardirq_context + !!task->softirq_context;
3099 }
3100
3101 static int separate_irq_context(struct task_struct *curr,
3102                 struct held_lock *hlock)
3103 {
3104         unsigned int depth = curr->lockdep_depth;
3105
3106         /*
3107          * Keep track of points where we cross into an interrupt context:
3108          */
3109         if (depth) {
3110                 struct held_lock *prev_hlock;
3111
3112                 prev_hlock = curr->held_locks + depth-1;
3113                 /*
3114                  * If we cross into another context, reset the
3115                  * hash key (this also prevents the checking and the
3116                  * adding of the dependency to 'prev'):
3117                  */
3118                 if (prev_hlock->irq_context != hlock->irq_context)
3119                         return 1;
3120         }
3121         return 0;
3122 }
3123
3124 #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3125
3126 static inline
3127 int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
3128                 enum lock_usage_bit new_bit)
3129 {
3130         WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
3131         return 1;
3132 }
3133
3134 static inline int mark_irqflags(struct task_struct *curr,
3135                 struct held_lock *hlock)
3136 {
3137         return 1;
3138 }
3139
3140 static inline unsigned int task_irq_context(struct task_struct *task)
3141 {
3142         return 0;
3143 }
3144
3145 static inline int separate_irq_context(struct task_struct *curr,
3146                 struct held_lock *hlock)
3147 {
3148         return 0;
3149 }
3150
3151 #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
3152
3153 /*
3154  * Mark a lock with a usage bit, and validate the state transition:
3155  */
3156 static int mark_lock(struct task_struct *curr, struct held_lock *this,
3157                              enum lock_usage_bit new_bit)
3158 {
3159         unsigned int new_mask = 1 << new_bit, ret = 1;
3160
3161         /*
3162          * If already set then do not dirty the cacheline,
3163          * nor do any checks:
3164          */
3165         if (likely(hlock_class(this)->usage_mask & new_mask))
3166                 return 1;
3167
3168         if (!graph_lock())
3169                 return 0;
3170         /*
3171          * Make sure we didn't race:
3172          */
3173         if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
3174                 graph_unlock();
3175                 return 1;
3176         }
3177
3178         hlock_class(this)->usage_mask |= new_mask;
3179
3180         if (!save_trace(hlock_class(this)->usage_traces + new_bit))
3181                 return 0;
3182
3183         switch (new_bit) {
3184 #define LOCKDEP_STATE(__STATE)                  \
3185         case LOCK_USED_IN_##__STATE:            \
3186         case LOCK_USED_IN_##__STATE##_READ:     \
3187         case LOCK_ENABLED_##__STATE:            \
3188         case LOCK_ENABLED_##__STATE##_READ:
3189 #include "lockdep_states.h"
3190 #undef LOCKDEP_STATE
3191                 ret = mark_lock_irq(curr, this, new_bit);
3192                 if (!ret)
3193                         return 0;
3194                 break;
3195         case LOCK_USED:
3196                 debug_atomic_dec(nr_unused_locks);
3197                 break;
3198         default:
3199                 if (!debug_locks_off_graph_unlock())
3200                         return 0;
3201                 WARN_ON(1);
3202                 return 0;
3203         }
3204
3205         graph_unlock();
3206
3207         /*
3208          * We must printk outside of the graph_lock:
3209          */
3210         if (ret == 2) {
3211                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
3212                 print_lock(this);
3213                 print_irqtrace_events(curr);
3214                 dump_stack();
3215         }
3216
3217         return ret;
3218 }
3219
3220 /*
3221  * Initialize a lock instance's lock-class mapping info:
3222  */
3223 static void __lockdep_init_map(struct lockdep_map *lock, const char *name,
3224                       struct lock_class_key *key, int subclass)
3225 {
3226         int i;
3227
3228         kmemcheck_mark_initialized(lock, sizeof(*lock));
3229
3230         for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
3231                 lock->class_cache[i] = NULL;
3232
3233 #ifdef CONFIG_LOCK_STAT
3234         lock->cpu = raw_smp_processor_id();
3235 #endif
3236
3237         /*
3238          * Can't be having no nameless bastards around this place!
3239          */
3240         if (DEBUG_LOCKS_WARN_ON(!name)) {
3241                 lock->name = "NULL";
3242                 return;
3243         }
3244
3245         lock->name = name;
3246
3247         /*
3248          * No key, no joy, we need to hash something.
3249          */
3250         if (DEBUG_LOCKS_WARN_ON(!key))
3251                 return;
3252         /*
3253          * Sanity check, the lock-class key must be persistent:
3254          */
3255         if (!static_obj(key)) {
3256                 printk("BUG: key %p not in .data!\n", key);
3257                 /*
3258                  * What it says above ^^^^^, I suggest you read it.
3259                  */
3260                 DEBUG_LOCKS_WARN_ON(1);
3261                 return;
3262         }
3263         lock->key = key;
3264
3265         if (unlikely(!debug_locks))
3266                 return;
3267
3268         if (subclass) {
3269                 unsigned long flags;
3270
3271                 if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
3272                         return;
3273
3274                 raw_local_irq_save(flags);
3275                 current->lockdep_recursion = 1;
3276                 register_lock_class(lock, subclass, 1);
3277                 current->lockdep_recursion = 0;
3278                 raw_local_irq_restore(flags);
3279         }
3280 }
3281
3282 void lockdep_init_map(struct lockdep_map *lock, const char *name,
3283                       struct lock_class_key *key, int subclass)
3284 {
3285         cross_init(lock, 0);
3286         __lockdep_init_map(lock, name, key, subclass);
3287 }
3288 EXPORT_SYMBOL_GPL(lockdep_init_map);
3289
3290 #ifdef CONFIG_LOCKDEP_CROSSRELEASE
3291 void lockdep_init_map_crosslock(struct lockdep_map *lock, const char *name,
3292                       struct lock_class_key *key, int subclass)
3293 {
3294         cross_init(lock, 1);
3295         __lockdep_init_map(lock, name, key, subclass);
3296 }
3297 EXPORT_SYMBOL_GPL(lockdep_init_map_crosslock);
3298 #endif
3299
3300 struct lock_class_key __lockdep_no_validate__;
3301 EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3302
3303 static int
3304 print_lock_nested_lock_not_held(struct task_struct *curr,
3305                                 struct held_lock *hlock,
3306                                 unsigned long ip)
3307 {
3308         if (!debug_locks_off())
3309                 return 0;
3310         if (debug_locks_silent)
3311                 return 0;
3312
3313         pr_warn("\n");
3314         pr_warn("==================================\n");
3315         pr_warn("WARNING: Nested lock was not taken\n");
3316         print_kernel_ident();
3317         pr_warn("----------------------------------\n");
3318
3319         pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3320         print_lock(hlock);
3321
3322         pr_warn("\nbut this task is not holding:\n");
3323         pr_warn("%s\n", hlock->nest_lock->name);
3324
3325         pr_warn("\nstack backtrace:\n");
3326         dump_stack();
3327
3328         pr_warn("\nother info that might help us debug this:\n");
3329         lockdep_print_held_locks(curr);
3330
3331         pr_warn("\nstack backtrace:\n");
3332         dump_stack();
3333
3334         return 0;
3335 }
3336
3337 static int __lock_is_held(struct lockdep_map *lock, int read);
3338
3339 /*
3340  * This gets called for every mutex_lock*()/spin_lock*() operation.
3341  * We maintain the dependency maps and validate the locking attempt:
3342  */