[PATCH] slab: remove kmem_cache_t
[linux-2.6.git] / kernel / lockdep.c
1 /*
2  * kernel/lockdep.c
3  *
4  * Runtime locking correctness validator
5  *
6  * Started by Ingo Molnar:
7  *
8  *  Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9  *
10  * this code maps all the lock dependencies as they occur in a live kernel
11  * and will warn about the following classes of locking bugs:
12  *
13  * - lock inversion scenarios
14  * - circular lock dependencies
15  * - hardirq/softirq safe/unsafe locking bugs
16  *
17  * Bugs are reported even if the current locking scenario does not cause
18  * any deadlock at this point.
19  *
20  * I.e. if anytime in the past two locks were taken in a different order,
21  * even if it happened for another task, even if those were different
22  * locks (but of the same class as this lock), this code will detect it.
23  *
24  * Thanks to Arjan van de Ven for coming up with the initial idea of
25  * mapping lock dependencies runtime.
26  */
27 #include <linux/mutex.h>
28 #include <linux/sched.h>
29 #include <linux/delay.h>
30 #include <linux/module.h>
31 #include <linux/proc_fs.h>
32 #include <linux/seq_file.h>
33 #include <linux/spinlock.h>
34 #include <linux/kallsyms.h>
35 #include <linux/interrupt.h>
36 #include <linux/stacktrace.h>
37 #include <linux/debug_locks.h>
38 #include <linux/irqflags.h>
39 #include <linux/utsname.h>
40
41 #include <asm/sections.h>
42
43 #include "lockdep_internals.h"
44
45 /*
46  * hash_lock: protects the lockdep hashes and class/list/hash allocators.
47  *
48  * This is one of the rare exceptions where it's justified
49  * to use a raw spinlock - we really dont want the spinlock
50  * code to recurse back into the lockdep code.
51  */
52 static raw_spinlock_t hash_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
53
54 static int lockdep_initialized;
55
56 unsigned long nr_list_entries;
57 static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
58
59 /*
60  * Allocate a lockdep entry. (assumes hash_lock held, returns
61  * with NULL on failure)
62  */
63 static struct lock_list *alloc_list_entry(void)
64 {
65         if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
66                 __raw_spin_unlock(&hash_lock);
67                 debug_locks_off();
68                 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
69                 printk("turning off the locking correctness validator.\n");
70                 return NULL;
71         }
72         return list_entries + nr_list_entries++;
73 }
74
75 /*
76  * All data structures here are protected by the global debug_lock.
77  *
78  * Mutex key structs only get allocated, once during bootup, and never
79  * get freed - this significantly simplifies the debugging code.
80  */
81 unsigned long nr_lock_classes;
82 static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
83
84 /*
85  * We keep a global list of all lock classes. The list only grows,
86  * never shrinks. The list is only accessed with the lockdep
87  * spinlock lock held.
88  */
89 LIST_HEAD(all_lock_classes);
90
91 /*
92  * The lockdep classes are in a hash-table as well, for fast lookup:
93  */
94 #define CLASSHASH_BITS          (MAX_LOCKDEP_KEYS_BITS - 1)
95 #define CLASSHASH_SIZE          (1UL << CLASSHASH_BITS)
96 #define CLASSHASH_MASK          (CLASSHASH_SIZE - 1)
97 #define __classhashfn(key)      ((((unsigned long)key >> CLASSHASH_BITS) + (unsigned long)key) & CLASSHASH_MASK)
98 #define classhashentry(key)     (classhash_table + __classhashfn((key)))
99
100 static struct list_head classhash_table[CLASSHASH_SIZE];
101
102 unsigned long nr_lock_chains;
103 static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
104
105 /*
106  * We put the lock dependency chains into a hash-table as well, to cache
107  * their existence:
108  */
109 #define CHAINHASH_BITS          (MAX_LOCKDEP_CHAINS_BITS-1)
110 #define CHAINHASH_SIZE          (1UL << CHAINHASH_BITS)
111 #define CHAINHASH_MASK          (CHAINHASH_SIZE - 1)
112 #define __chainhashfn(chain) \
113                 (((chain >> CHAINHASH_BITS) + chain) & CHAINHASH_MASK)
114 #define chainhashentry(chain)   (chainhash_table + __chainhashfn((chain)))
115
116 static struct list_head chainhash_table[CHAINHASH_SIZE];
117
118 /*
119  * The hash key of the lock dependency chains is a hash itself too:
120  * it's a hash of all locks taken up to that lock, including that lock.
121  * It's a 64-bit hash, because it's important for the keys to be
122  * unique.
123  */
124 #define iterate_chain_key(key1, key2) \
125         (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
126         ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
127         (key2))
128
129 void lockdep_off(void)
130 {
131         current->lockdep_recursion++;
132 }
133
134 EXPORT_SYMBOL(lockdep_off);
135
136 void lockdep_on(void)
137 {
138         current->lockdep_recursion--;
139 }
140
141 EXPORT_SYMBOL(lockdep_on);
142
143 int lockdep_internal(void)
144 {
145         return current->lockdep_recursion != 0;
146 }
147
148 EXPORT_SYMBOL(lockdep_internal);
149
150 /*
151  * Debugging switches:
152  */
153
154 #define VERBOSE                 0
155 #ifdef VERBOSE
156 # define VERY_VERBOSE           0
157 #endif
158
159 #if VERBOSE
160 # define HARDIRQ_VERBOSE        1
161 # define SOFTIRQ_VERBOSE        1
162 #else
163 # define HARDIRQ_VERBOSE        0
164 # define SOFTIRQ_VERBOSE        0
165 #endif
166
167 #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
168 /*
169  * Quick filtering for interesting events:
170  */
171 static int class_filter(struct lock_class *class)
172 {
173 #if 0
174         /* Example */
175         if (class->name_version == 1 &&
176                         !strcmp(class->name, "lockname"))
177                 return 1;
178         if (class->name_version == 1 &&
179                         !strcmp(class->name, "&struct->lockfield"))
180                 return 1;
181 #endif
182         /* Allow everything else. 0 would be filter everything else */
183         return 1;
184 }
185 #endif
186
187 static int verbose(struct lock_class *class)
188 {
189 #if VERBOSE
190         return class_filter(class);
191 #endif
192         return 0;
193 }
194
195 #ifdef CONFIG_TRACE_IRQFLAGS
196
197 static int hardirq_verbose(struct lock_class *class)
198 {
199 #if HARDIRQ_VERBOSE
200         return class_filter(class);
201 #endif
202         return 0;
203 }
204
205 static int softirq_verbose(struct lock_class *class)
206 {
207 #if SOFTIRQ_VERBOSE
208         return class_filter(class);
209 #endif
210         return 0;
211 }
212
213 #endif
214
215 /*
216  * Stack-trace: tightly packed array of stack backtrace
217  * addresses. Protected by the hash_lock.
218  */
219 unsigned long nr_stack_trace_entries;
220 static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
221
222 static int save_trace(struct stack_trace *trace)
223 {
224         trace->nr_entries = 0;
225         trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
226         trace->entries = stack_trace + nr_stack_trace_entries;
227
228         trace->skip = 3;
229         trace->all_contexts = 0;
230
231         /* Make sure to not recurse in case the the unwinder needs to tak
232 e          locks. */
233         lockdep_off();
234         save_stack_trace(trace, NULL);
235         lockdep_on();
236
237         trace->max_entries = trace->nr_entries;
238
239         nr_stack_trace_entries += trace->nr_entries;
240         if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES))
241                 return 0;
242
243         if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
244                 __raw_spin_unlock(&hash_lock);
245                 if (debug_locks_off()) {
246                         printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
247                         printk("turning off the locking correctness validator.\n");
248                         dump_stack();
249                 }
250                 return 0;
251         }
252
253         return 1;
254 }
255
256 unsigned int nr_hardirq_chains;
257 unsigned int nr_softirq_chains;
258 unsigned int nr_process_chains;
259 unsigned int max_lockdep_depth;
260 unsigned int max_recursion_depth;
261
262 #ifdef CONFIG_DEBUG_LOCKDEP
263 /*
264  * We cannot printk in early bootup code. Not even early_printk()
265  * might work. So we mark any initialization errors and printk
266  * about it later on, in lockdep_info().
267  */
268 static int lockdep_init_error;
269
270 /*
271  * Various lockdep statistics:
272  */
273 atomic_t chain_lookup_hits;
274 atomic_t chain_lookup_misses;
275 atomic_t hardirqs_on_events;
276 atomic_t hardirqs_off_events;
277 atomic_t redundant_hardirqs_on;
278 atomic_t redundant_hardirqs_off;
279 atomic_t softirqs_on_events;
280 atomic_t softirqs_off_events;
281 atomic_t redundant_softirqs_on;
282 atomic_t redundant_softirqs_off;
283 atomic_t nr_unused_locks;
284 atomic_t nr_cyclic_checks;
285 atomic_t nr_cyclic_check_recursions;
286 atomic_t nr_find_usage_forwards_checks;
287 atomic_t nr_find_usage_forwards_recursions;
288 atomic_t nr_find_usage_backwards_checks;
289 atomic_t nr_find_usage_backwards_recursions;
290 # define debug_atomic_inc(ptr)          atomic_inc(ptr)
291 # define debug_atomic_dec(ptr)          atomic_dec(ptr)
292 # define debug_atomic_read(ptr)         atomic_read(ptr)
293 #else
294 # define debug_atomic_inc(ptr)          do { } while (0)
295 # define debug_atomic_dec(ptr)          do { } while (0)
296 # define debug_atomic_read(ptr)         0
297 #endif
298
299 /*
300  * Locking printouts:
301  */
302
303 static const char *usage_str[] =
304 {
305         [LOCK_USED] =                   "initial-use ",
306         [LOCK_USED_IN_HARDIRQ] =        "in-hardirq-W",
307         [LOCK_USED_IN_SOFTIRQ] =        "in-softirq-W",
308         [LOCK_ENABLED_SOFTIRQS] =       "softirq-on-W",
309         [LOCK_ENABLED_HARDIRQS] =       "hardirq-on-W",
310         [LOCK_USED_IN_HARDIRQ_READ] =   "in-hardirq-R",
311         [LOCK_USED_IN_SOFTIRQ_READ] =   "in-softirq-R",
312         [LOCK_ENABLED_SOFTIRQS_READ] =  "softirq-on-R",
313         [LOCK_ENABLED_HARDIRQS_READ] =  "hardirq-on-R",
314 };
315
316 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
317 {
318         unsigned long offs, size;
319         char *modname;
320
321         return kallsyms_lookup((unsigned long)key, &size, &offs, &modname, str);
322 }
323
324 void
325 get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
326 {
327         *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
328
329         if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
330                 *c1 = '+';
331         else
332                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
333                         *c1 = '-';
334
335         if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
336                 *c2 = '+';
337         else
338                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
339                         *c2 = '-';
340
341         if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
342                 *c3 = '-';
343         if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
344                 *c3 = '+';
345                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
346                         *c3 = '?';
347         }
348
349         if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
350                 *c4 = '-';
351         if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
352                 *c4 = '+';
353                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
354                         *c4 = '?';
355         }
356 }
357
358 static void print_lock_name(struct lock_class *class)
359 {
360         char str[128], c1, c2, c3, c4;
361         const char *name;
362
363         get_usage_chars(class, &c1, &c2, &c3, &c4);
364
365         name = class->name;
366         if (!name) {
367                 name = __get_key_name(class->key, str);
368                 printk(" (%s", name);
369         } else {
370                 printk(" (%s", name);
371                 if (class->name_version > 1)
372                         printk("#%d", class->name_version);
373                 if (class->subclass)
374                         printk("/%d", class->subclass);
375         }
376         printk("){%c%c%c%c}", c1, c2, c3, c4);
377 }
378
379 static void print_lockdep_cache(struct lockdep_map *lock)
380 {
381         const char *name;
382         char str[128];
383
384         name = lock->name;
385         if (!name)
386                 name = __get_key_name(lock->key->subkeys, str);
387
388         printk("%s", name);
389 }
390
391 static void print_lock(struct held_lock *hlock)
392 {
393         print_lock_name(hlock->class);
394         printk(", at: ");
395         print_ip_sym(hlock->acquire_ip);
396 }
397
398 static void lockdep_print_held_locks(struct task_struct *curr)
399 {
400         int i, depth = curr->lockdep_depth;
401
402         if (!depth) {
403                 printk("no locks held by %s/%d.\n", curr->comm, curr->pid);
404                 return;
405         }
406         printk("%d lock%s held by %s/%d:\n",
407                 depth, depth > 1 ? "s" : "", curr->comm, curr->pid);
408
409         for (i = 0; i < depth; i++) {
410                 printk(" #%d: ", i);
411                 print_lock(curr->held_locks + i);
412         }
413 }
414
415 static void print_lock_class_header(struct lock_class *class, int depth)
416 {
417         int bit;
418
419         printk("%*s->", depth, "");
420         print_lock_name(class);
421         printk(" ops: %lu", class->ops);
422         printk(" {\n");
423
424         for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
425                 if (class->usage_mask & (1 << bit)) {
426                         int len = depth;
427
428                         len += printk("%*s   %s", depth, "", usage_str[bit]);
429                         len += printk(" at:\n");
430                         print_stack_trace(class->usage_traces + bit, len);
431                 }
432         }
433         printk("%*s }\n", depth, "");
434
435         printk("%*s ... key      at: ",depth,"");
436         print_ip_sym((unsigned long)class->key);
437 }
438
439 /*
440  * printk all lock dependencies starting at <entry>:
441  */
442 static void print_lock_dependencies(struct lock_class *class, int depth)
443 {
444         struct lock_list *entry;
445
446         if (DEBUG_LOCKS_WARN_ON(depth >= 20))
447                 return;
448
449         print_lock_class_header(class, depth);
450
451         list_for_each_entry(entry, &class->locks_after, entry) {
452                 DEBUG_LOCKS_WARN_ON(!entry->class);
453                 print_lock_dependencies(entry->class, depth + 1);
454
455                 printk("%*s ... acquired at:\n",depth,"");
456                 print_stack_trace(&entry->trace, 2);
457                 printk("\n");
458         }
459 }
460
461 /*
462  * Add a new dependency to the head of the list:
463  */
464 static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
465                             struct list_head *head, unsigned long ip)
466 {
467         struct lock_list *entry;
468         /*
469          * Lock not present yet - get a new dependency struct and
470          * add it to the list:
471          */
472         entry = alloc_list_entry();
473         if (!entry)
474                 return 0;
475
476         entry->class = this;
477         save_trace(&entry->trace);
478
479         /*
480          * Since we never remove from the dependency list, the list can
481          * be walked lockless by other CPUs, it's only allocation
482          * that must be protected by the spinlock. But this also means
483          * we must make new entries visible only once writes to the
484          * entry become visible - hence the RCU op:
485          */
486         list_add_tail_rcu(&entry->entry, head);
487
488         return 1;
489 }
490
491 /*
492  * Recursive, forwards-direction lock-dependency checking, used for
493  * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
494  * checking.
495  *
496  * (to keep the stackframe of the recursive functions small we
497  *  use these global variables, and we also mark various helper
498  *  functions as noinline.)
499  */
500 static struct held_lock *check_source, *check_target;
501
502 /*
503  * Print a dependency chain entry (this is only done when a deadlock
504  * has been detected):
505  */
506 static noinline int
507 print_circular_bug_entry(struct lock_list *target, unsigned int depth)
508 {
509         if (debug_locks_silent)
510                 return 0;
511         printk("\n-> #%u", depth);
512         print_lock_name(target->class);
513         printk(":\n");
514         print_stack_trace(&target->trace, 6);
515
516         return 0;
517 }
518
519 static void print_kernel_version(void)
520 {
521         printk("%s %.*s\n", init_utsname()->release,
522                 (int)strcspn(init_utsname()->version, " "),
523                 init_utsname()->version);
524 }
525
526 /*
527  * When a circular dependency is detected, print the
528  * header first:
529  */
530 static noinline int
531 print_circular_bug_header(struct lock_list *entry, unsigned int depth)
532 {
533         struct task_struct *curr = current;
534
535         __raw_spin_unlock(&hash_lock);
536         debug_locks_off();
537         if (debug_locks_silent)
538                 return 0;
539
540         printk("\n=======================================================\n");
541         printk(  "[ INFO: possible circular locking dependency detected ]\n");
542         print_kernel_version();
543         printk(  "-------------------------------------------------------\n");
544         printk("%s/%d is trying to acquire lock:\n",
545                 curr->comm, curr->pid);
546         print_lock(check_source);
547         printk("\nbut task is already holding lock:\n");
548         print_lock(check_target);
549         printk("\nwhich lock already depends on the new lock.\n\n");
550         printk("\nthe existing dependency chain (in reverse order) is:\n");
551
552         print_circular_bug_entry(entry, depth);
553
554         return 0;
555 }
556
557 static noinline int print_circular_bug_tail(void)
558 {
559         struct task_struct *curr = current;
560         struct lock_list this;
561
562         if (debug_locks_silent)
563                 return 0;
564
565         this.class = check_source->class;
566         save_trace(&this.trace);
567         print_circular_bug_entry(&this, 0);
568
569         printk("\nother info that might help us debug this:\n\n");
570         lockdep_print_held_locks(curr);
571
572         printk("\nstack backtrace:\n");
573         dump_stack();
574
575         return 0;
576 }
577
578 #define RECURSION_LIMIT 40
579
580 static int noinline print_infinite_recursion_bug(void)
581 {
582         __raw_spin_unlock(&hash_lock);
583         DEBUG_LOCKS_WARN_ON(1);
584
585         return 0;
586 }
587
588 /*
589  * Prove that the dependency graph starting at <entry> can not
590  * lead to <target>. Print an error and return 0 if it does.
591  */
592 static noinline int
593 check_noncircular(struct lock_class *source, unsigned int depth)
594 {
595         struct lock_list *entry;
596
597         debug_atomic_inc(&nr_cyclic_check_recursions);
598         if (depth > max_recursion_depth)
599                 max_recursion_depth = depth;
600         if (depth >= RECURSION_LIMIT)
601                 return print_infinite_recursion_bug();
602         /*
603          * Check this lock's dependency list:
604          */
605         list_for_each_entry(entry, &source->locks_after, entry) {
606                 if (entry->class == check_target->class)
607                         return print_circular_bug_header(entry, depth+1);
608                 debug_atomic_inc(&nr_cyclic_checks);
609                 if (!check_noncircular(entry->class, depth+1))
610                         return print_circular_bug_entry(entry, depth+1);
611         }
612         return 1;
613 }
614
615 static int very_verbose(struct lock_class *class)
616 {
617 #if VERY_VERBOSE
618         return class_filter(class);
619 #endif
620         return 0;
621 }
622 #ifdef CONFIG_TRACE_IRQFLAGS
623
624 /*
625  * Forwards and backwards subgraph searching, for the purposes of
626  * proving that two subgraphs can be connected by a new dependency
627  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
628  */
629 static enum lock_usage_bit find_usage_bit;
630 static struct lock_class *forwards_match, *backwards_match;
631
632 /*
633  * Find a node in the forwards-direction dependency sub-graph starting
634  * at <source> that matches <find_usage_bit>.
635  *
636  * Return 2 if such a node exists in the subgraph, and put that node
637  * into <forwards_match>.
638  *
639  * Return 1 otherwise and keep <forwards_match> unchanged.
640  * Return 0 on error.
641  */
642 static noinline int
643 find_usage_forwards(struct lock_class *source, unsigned int depth)
644 {
645         struct lock_list *entry;
646         int ret;
647
648         if (depth > max_recursion_depth)
649                 max_recursion_depth = depth;
650         if (depth >= RECURSION_LIMIT)
651                 return print_infinite_recursion_bug();
652
653         debug_atomic_inc(&nr_find_usage_forwards_checks);
654         if (source->usage_mask & (1 << find_usage_bit)) {
655                 forwards_match = source;
656                 return 2;
657         }
658
659         /*
660          * Check this lock's dependency list:
661          */
662         list_for_each_entry(entry, &source->locks_after, entry) {
663                 debug_atomic_inc(&nr_find_usage_forwards_recursions);
664                 ret = find_usage_forwards(entry->class, depth+1);
665                 if (ret == 2 || ret == 0)
666                         return ret;
667         }
668         return 1;
669 }
670
671 /*
672  * Find a node in the backwards-direction dependency sub-graph starting
673  * at <source> that matches <find_usage_bit>.
674  *
675  * Return 2 if such a node exists in the subgraph, and put that node
676  * into <backwards_match>.
677  *
678  * Return 1 otherwise and keep <backwards_match> unchanged.
679  * Return 0 on error.
680  */
681 static noinline int
682 find_usage_backwards(struct lock_class *source, unsigned int depth)
683 {
684         struct lock_list *entry;
685         int ret;
686
687         if (depth > max_recursion_depth)
688                 max_recursion_depth = depth;
689         if (depth >= RECURSION_LIMIT)
690                 return print_infinite_recursion_bug();
691
692         debug_atomic_inc(&nr_find_usage_backwards_checks);
693         if (source->usage_mask & (1 << find_usage_bit)) {
694                 backwards_match = source;
695                 return 2;
696         }
697
698         /*
699          * Check this lock's dependency list:
700          */
701         list_for_each_entry(entry, &source->locks_before, entry) {
702                 debug_atomic_inc(&nr_find_usage_backwards_recursions);
703                 ret = find_usage_backwards(entry->class, depth+1);
704                 if (ret == 2 || ret == 0)
705                         return ret;
706         }
707         return 1;
708 }
709
710 static int
711 print_bad_irq_dependency(struct task_struct *curr,
712                          struct held_lock *prev,
713                          struct held_lock *next,
714                          enum lock_usage_bit bit1,
715                          enum lock_usage_bit bit2,
716                          const char *irqclass)
717 {
718         __raw_spin_unlock(&hash_lock);
719         debug_locks_off();
720         if (debug_locks_silent)
721                 return 0;
722
723         printk("\n======================================================\n");
724         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
725                 irqclass, irqclass);
726         print_kernel_version();
727         printk(  "------------------------------------------------------\n");
728         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
729                 curr->comm, curr->pid,
730                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
731                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
732                 curr->hardirqs_enabled,
733                 curr->softirqs_enabled);
734         print_lock(next);
735
736         printk("\nand this task is already holding:\n");
737         print_lock(prev);
738         printk("which would create a new lock dependency:\n");
739         print_lock_name(prev->class);
740         printk(" ->");
741         print_lock_name(next->class);
742         printk("\n");
743
744         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
745                 irqclass);
746         print_lock_name(backwards_match);
747         printk("\n... which became %s-irq-safe at:\n", irqclass);
748
749         print_stack_trace(backwards_match->usage_traces + bit1, 1);
750
751         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
752         print_lock_name(forwards_match);
753         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
754         printk("...");
755
756         print_stack_trace(forwards_match->usage_traces + bit2, 1);
757
758         printk("\nother info that might help us debug this:\n\n");
759         lockdep_print_held_locks(curr);
760
761         printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
762         print_lock_dependencies(backwards_match, 0);
763
764         printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
765         print_lock_dependencies(forwards_match, 0);
766
767         printk("\nstack backtrace:\n");
768         dump_stack();
769
770         return 0;
771 }
772
773 static int
774 check_usage(struct task_struct *curr, struct held_lock *prev,
775             struct held_lock *next, enum lock_usage_bit bit_backwards,
776             enum lock_usage_bit bit_forwards, const char *irqclass)
777 {
778         int ret;
779
780         find_usage_bit = bit_backwards;
781         /* fills in <backwards_match> */
782         ret = find_usage_backwards(prev->class, 0);
783         if (!ret || ret == 1)
784                 return ret;
785
786         find_usage_bit = bit_forwards;
787         ret = find_usage_forwards(next->class, 0);
788         if (!ret || ret == 1)
789                 return ret;
790         /* ret == 2 */
791         return print_bad_irq_dependency(curr, prev, next,
792                         bit_backwards, bit_forwards, irqclass);
793 }
794
795 #endif
796
797 static int
798 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
799                    struct held_lock *next)
800 {
801         debug_locks_off();
802         __raw_spin_unlock(&hash_lock);
803         if (debug_locks_silent)
804                 return 0;
805
806         printk("\n=============================================\n");
807         printk(  "[ INFO: possible recursive locking detected ]\n");
808         print_kernel_version();
809         printk(  "---------------------------------------------\n");
810         printk("%s/%d is trying to acquire lock:\n",
811                 curr->comm, curr->pid);
812         print_lock(next);
813         printk("\nbut task is already holding lock:\n");
814         print_lock(prev);
815
816         printk("\nother info that might help us debug this:\n");
817         lockdep_print_held_locks(curr);
818
819         printk("\nstack backtrace:\n");
820         dump_stack();
821
822         return 0;
823 }
824
825 /*
826  * Check whether we are holding such a class already.
827  *
828  * (Note that this has to be done separately, because the graph cannot
829  * detect such classes of deadlocks.)
830  *
831  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
832  */
833 static int
834 check_deadlock(struct task_struct *curr, struct held_lock *next,
835                struct lockdep_map *next_instance, int read)
836 {
837         struct held_lock *prev;
838         int i;
839
840         for (i = 0; i < curr->lockdep_depth; i++) {
841                 prev = curr->held_locks + i;
842                 if (prev->class != next->class)
843                         continue;
844                 /*
845                  * Allow read-after-read recursion of the same
846                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
847                  */
848                 if ((read == 2) && prev->read)
849                         return 2;
850                 return print_deadlock_bug(curr, prev, next);
851         }
852         return 1;
853 }
854
855 /*
856  * There was a chain-cache miss, and we are about to add a new dependency
857  * to a previous lock. We recursively validate the following rules:
858  *
859  *  - would the adding of the <prev> -> <next> dependency create a
860  *    circular dependency in the graph? [== circular deadlock]
861  *
862  *  - does the new prev->next dependency connect any hardirq-safe lock
863  *    (in the full backwards-subgraph starting at <prev>) with any
864  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
865  *    <next>)? [== illegal lock inversion with hardirq contexts]
866  *
867  *  - does the new prev->next dependency connect any softirq-safe lock
868  *    (in the full backwards-subgraph starting at <prev>) with any
869  *    softirq-unsafe lock (in the full forwards-subgraph starting at
870  *    <next>)? [== illegal lock inversion with softirq contexts]
871  *
872  * any of these scenarios could lead to a deadlock.
873  *
874  * Then if all the validations pass, we add the forwards and backwards
875  * dependency.
876  */
877 static int
878 check_prev_add(struct task_struct *curr, struct held_lock *prev,
879                struct held_lock *next)
880 {
881         struct lock_list *entry;
882         int ret;
883
884         /*
885          * Prove that the new <prev> -> <next> dependency would not
886          * create a circular dependency in the graph. (We do this by
887          * forward-recursing into the graph starting at <next>, and
888          * checking whether we can reach <prev>.)
889          *
890          * We are using global variables to control the recursion, to
891          * keep the stackframe size of the recursive functions low:
892          */
893         check_source = next;
894         check_target = prev;
895         if (!(check_noncircular(next->class, 0)))
896                 return print_circular_bug_tail();
897
898 #ifdef CONFIG_TRACE_IRQFLAGS
899         /*
900          * Prove that the new dependency does not connect a hardirq-safe
901          * lock with a hardirq-unsafe lock - to achieve this we search
902          * the backwards-subgraph starting at <prev>, and the
903          * forwards-subgraph starting at <next>:
904          */
905         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
906                                         LOCK_ENABLED_HARDIRQS, "hard"))
907                 return 0;
908
909         /*
910          * Prove that the new dependency does not connect a hardirq-safe-read
911          * lock with a hardirq-unsafe lock - to achieve this we search
912          * the backwards-subgraph starting at <prev>, and the
913          * forwards-subgraph starting at <next>:
914          */
915         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
916                                         LOCK_ENABLED_HARDIRQS, "hard-read"))
917                 return 0;
918
919         /*
920          * Prove that the new dependency does not connect a softirq-safe
921          * lock with a softirq-unsafe lock - to achieve this we search
922          * the backwards-subgraph starting at <prev>, and the
923          * forwards-subgraph starting at <next>:
924          */
925         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
926                                         LOCK_ENABLED_SOFTIRQS, "soft"))
927                 return 0;
928         /*
929          * Prove that the new dependency does not connect a softirq-safe-read
930          * lock with a softirq-unsafe lock - to achieve this we search
931          * the backwards-subgraph starting at <prev>, and the
932          * forwards-subgraph starting at <next>:
933          */
934         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
935                                         LOCK_ENABLED_SOFTIRQS, "soft"))
936                 return 0;
937 #endif
938         /*
939          * For recursive read-locks we do all the dependency checks,
940          * but we dont store read-triggered dependencies (only
941          * write-triggered dependencies). This ensures that only the
942          * write-side dependencies matter, and that if for example a
943          * write-lock never takes any other locks, then the reads are
944          * equivalent to a NOP.
945          */
946         if (next->read == 2 || prev->read == 2)
947                 return 1;
948         /*
949          * Is the <prev> -> <next> dependency already present?
950          *
951          * (this may occur even though this is a new chain: consider
952          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
953          *  chains - the second one will be new, but L1 already has
954          *  L2 added to its dependency list, due to the first chain.)
955          */
956         list_for_each_entry(entry, &prev->class->locks_after, entry) {
957                 if (entry->class == next->class)
958                         return 2;
959         }
960
961         /*
962          * Ok, all validations passed, add the new lock
963          * to the previous lock's dependency list:
964          */
965         ret = add_lock_to_list(prev->class, next->class,
966                                &prev->class->locks_after, next->acquire_ip);
967         if (!ret)
968                 return 0;
969         /*
970          * Return value of 2 signals 'dependency already added',
971          * in that case we dont have to add the backlink either.
972          */
973         if (ret == 2)
974                 return 2;
975         ret = add_lock_to_list(next->class, prev->class,
976                                &next->class->locks_before, next->acquire_ip);
977
978         /*
979          * Debugging printouts:
980          */
981         if (verbose(prev->class) || verbose(next->class)) {
982                 __raw_spin_unlock(&hash_lock);
983                 printk("\n new dependency: ");
984                 print_lock_name(prev->class);
985                 printk(" => ");
986                 print_lock_name(next->class);
987                 printk("\n");
988                 dump_stack();
989                 __raw_spin_lock(&hash_lock);
990         }
991         return 1;
992 }
993
994 /*
995  * Add the dependency to all directly-previous locks that are 'relevant'.
996  * The ones that are relevant are (in increasing distance from curr):
997  * all consecutive trylock entries and the final non-trylock entry - or
998  * the end of this context's lock-chain - whichever comes first.
999  */
1000 static int
1001 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1002 {
1003         int depth = curr->lockdep_depth;
1004         struct held_lock *hlock;
1005
1006         /*
1007          * Debugging checks.
1008          *
1009          * Depth must not be zero for a non-head lock:
1010          */
1011         if (!depth)
1012                 goto out_bug;
1013         /*
1014          * At least two relevant locks must exist for this
1015          * to be a head:
1016          */
1017         if (curr->held_locks[depth].irq_context !=
1018                         curr->held_locks[depth-1].irq_context)
1019                 goto out_bug;
1020
1021         for (;;) {
1022                 hlock = curr->held_locks + depth-1;
1023                 /*
1024                  * Only non-recursive-read entries get new dependencies
1025                  * added:
1026                  */
1027                 if (hlock->read != 2) {
1028                         check_prev_add(curr, hlock, next);
1029                         /*
1030                          * Stop after the first non-trylock entry,
1031                          * as non-trylock entries have added their
1032                          * own direct dependencies already, so this
1033                          * lock is connected to them indirectly:
1034                          */
1035                         if (!hlock->trylock)
1036                                 break;
1037                 }
1038                 depth--;
1039                 /*
1040                  * End of lock-stack?
1041                  */
1042                 if (!depth)
1043                         break;
1044                 /*
1045                  * Stop the search if we cross into another context:
1046                  */
1047                 if (curr->held_locks[depth].irq_context !=
1048                                 curr->held_locks[depth-1].irq_context)
1049                         break;
1050         }
1051         return 1;
1052 out_bug:
1053         __raw_spin_unlock(&hash_lock);
1054         DEBUG_LOCKS_WARN_ON(1);
1055
1056         return 0;
1057 }
1058
1059
1060 /*
1061  * Is this the address of a static object:
1062  */
1063 static int static_obj(void *obj)
1064 {
1065         unsigned long start = (unsigned long) &_stext,
1066                       end   = (unsigned long) &_end,
1067                       addr  = (unsigned long) obj;
1068 #ifdef CONFIG_SMP
1069         int i;
1070 #endif
1071
1072         /*
1073          * static variable?
1074          */
1075         if ((addr >= start) && (addr < end))
1076                 return 1;
1077
1078 #ifdef CONFIG_SMP
1079         /*
1080          * percpu var?
1081          */
1082         for_each_possible_cpu(i) {
1083                 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
1084                 end   = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
1085                                         + per_cpu_offset(i);
1086
1087                 if ((addr >= start) && (addr < end))
1088                         return 1;
1089         }
1090 #endif
1091
1092         /*
1093          * module var?
1094          */
1095         return is_module_address(addr);
1096 }
1097
1098 /*
1099  * To make lock name printouts unique, we calculate a unique
1100  * class->name_version generation counter:
1101  */
1102 static int count_matching_names(struct lock_class *new_class)
1103 {
1104         struct lock_class *class;
1105         int count = 0;
1106
1107         if (!new_class->name)
1108                 return 0;
1109
1110         list_for_each_entry(class, &all_lock_classes, lock_entry) {
1111                 if (new_class->key - new_class->subclass == class->key)
1112                         return class->name_version;
1113                 if (class->name && !strcmp(class->name, new_class->name))
1114                         count = max(count, class->name_version);
1115         }
1116
1117         return count + 1;
1118 }
1119
1120 /*
1121  * Register a lock's class in the hash-table, if the class is not present
1122  * yet. Otherwise we look it up. We cache the result in the lock object
1123  * itself, so actual lookup of the hash should be once per lock object.
1124  */
1125 static inline struct lock_class *
1126 look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
1127 {
1128         struct lockdep_subclass_key *key;
1129         struct list_head *hash_head;
1130         struct lock_class *class;
1131
1132 #ifdef CONFIG_DEBUG_LOCKDEP
1133         /*
1134          * If the architecture calls into lockdep before initializing
1135          * the hashes then we'll warn about it later. (we cannot printk
1136          * right now)
1137          */
1138         if (unlikely(!lockdep_initialized)) {
1139                 lockdep_init();
1140                 lockdep_init_error = 1;
1141         }
1142 #endif
1143
1144         /*
1145          * Static locks do not have their class-keys yet - for them the key
1146          * is the lock object itself:
1147          */
1148         if (unlikely(!lock->key))
1149                 lock->key = (void *)lock;
1150
1151         /*
1152          * NOTE: the class-key must be unique. For dynamic locks, a static
1153          * lock_class_key variable is passed in through the mutex_init()
1154          * (or spin_lock_init()) call - which acts as the key. For static
1155          * locks we use the lock object itself as the key.
1156          */
1157         BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(struct lock_class));
1158
1159         key = lock->key->subkeys + subclass;
1160
1161         hash_head = classhashentry(key);
1162
1163         /*
1164          * We can walk the hash lockfree, because the hash only
1165          * grows, and we are careful when adding entries to the end:
1166          */
1167         list_for_each_entry(class, hash_head, hash_entry)
1168                 if (class->key == key)
1169                         return class;
1170
1171         return NULL;
1172 }
1173
1174 /*
1175  * Register a lock's class in the hash-table, if the class is not present
1176  * yet. Otherwise we look it up. We cache the result in the lock object
1177  * itself, so actual lookup of the hash should be once per lock object.
1178  */
1179 static inline struct lock_class *
1180 register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
1181 {
1182         struct lockdep_subclass_key *key;
1183         struct list_head *hash_head;
1184         struct lock_class *class;
1185
1186         class = look_up_lock_class(lock, subclass);
1187         if (likely(class))
1188                 return class;
1189
1190         /*
1191          * Debug-check: all keys must be persistent!
1192          */
1193         if (!static_obj(lock->key)) {
1194                 debug_locks_off();
1195                 printk("INFO: trying to register non-static key.\n");
1196                 printk("the code is fine but needs lockdep annotation.\n");
1197                 printk("turning off the locking correctness validator.\n");
1198                 dump_stack();
1199
1200                 return NULL;
1201         }
1202
1203         key = lock->key->subkeys + subclass;
1204         hash_head = classhashentry(key);
1205
1206         __raw_spin_lock(&hash_lock);
1207         /*
1208          * We have to do the hash-walk again, to avoid races
1209          * with another CPU:
1210          */
1211         list_for_each_entry(class, hash_head, hash_entry)
1212                 if (class->key == key)
1213                         goto out_unlock_set;
1214         /*
1215          * Allocate a new key from the static array, and add it to
1216          * the hash:
1217          */
1218         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
1219                 __raw_spin_unlock(&hash_lock);
1220                 debug_locks_off();
1221                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
1222                 printk("turning off the locking correctness validator.\n");
1223                 return NULL;
1224         }
1225         class = lock_classes + nr_lock_classes++;
1226         debug_atomic_inc(&nr_unused_locks);
1227         class->key = key;
1228         class->name = lock->name;
1229         class->subclass = subclass;
1230         INIT_LIST_HEAD(&class->lock_entry);
1231         INIT_LIST_HEAD(&class->locks_before);
1232         INIT_LIST_HEAD(&class->locks_after);
1233         class->name_version = count_matching_names(class);
1234         /*
1235          * We use RCU's safe list-add method to make
1236          * parallel walking of the hash-list safe:
1237          */
1238         list_add_tail_rcu(&class->hash_entry, hash_head);
1239
1240         if (verbose(class)) {
1241                 __raw_spin_unlock(&hash_lock);
1242                 printk("\nnew class %p: %s", class->key, class->name);
1243                 if (class->name_version > 1)
1244                         printk("#%d", class->name_version);
1245                 printk("\n");
1246                 dump_stack();
1247                 __raw_spin_lock(&hash_lock);
1248         }
1249 out_unlock_set:
1250         __raw_spin_unlock(&hash_lock);
1251
1252         if (!subclass || force)
1253                 lock->class_cache = class;
1254
1255         DEBUG_LOCKS_WARN_ON(class->subclass != subclass);
1256
1257         return class;
1258 }
1259
1260 /*
1261  * Look up a dependency chain. If the key is not present yet then
1262  * add it and return 0 - in this case the new dependency chain is
1263  * validated. If the key is already hashed, return 1.
1264  */
1265 static inline int lookup_chain_cache(u64 chain_key)
1266 {
1267         struct list_head *hash_head = chainhashentry(chain_key);
1268         struct lock_chain *chain;
1269
1270         DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1271         /*
1272          * We can walk it lock-free, because entries only get added
1273          * to the hash:
1274          */
1275         list_for_each_entry(chain, hash_head, entry) {
1276                 if (chain->chain_key == chain_key) {
1277 cache_hit:
1278                         debug_atomic_inc(&chain_lookup_hits);
1279                         /*
1280                          * In the debugging case, force redundant checking
1281                          * by returning 1:
1282                          */
1283 #ifdef CONFIG_DEBUG_LOCKDEP
1284                         __raw_spin_lock(&hash_lock);
1285                         return 1;
1286 #endif
1287                         return 0;
1288                 }
1289         }
1290         /*
1291          * Allocate a new chain entry from the static array, and add
1292          * it to the hash:
1293          */
1294         __raw_spin_lock(&hash_lock);
1295         /*
1296          * We have to walk the chain again locked - to avoid duplicates:
1297          */
1298         list_for_each_entry(chain, hash_head, entry) {
1299                 if (chain->chain_key == chain_key) {
1300                         __raw_spin_unlock(&hash_lock);
1301                         goto cache_hit;
1302                 }
1303         }
1304         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1305                 __raw_spin_unlock(&hash_lock);
1306                 debug_locks_off();
1307                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1308                 printk("turning off the locking correctness validator.\n");
1309                 return 0;
1310         }
1311         chain = lock_chains + nr_lock_chains++;
1312         chain->chain_key = chain_key;
1313         list_add_tail_rcu(&chain->entry, hash_head);
1314         debug_atomic_inc(&chain_lookup_misses);
1315 #ifdef CONFIG_TRACE_IRQFLAGS
1316         if (current->hardirq_context)
1317                 nr_hardirq_chains++;
1318         else {
1319                 if (current->softirq_context)
1320                         nr_softirq_chains++;
1321                 else
1322                         nr_process_chains++;
1323         }
1324 #else
1325         nr_process_chains++;
1326 #endif
1327
1328         return 1;
1329 }
1330
1331 /*
1332  * We are building curr_chain_key incrementally, so double-check
1333  * it from scratch, to make sure that it's done correctly:
1334  */
1335 static void check_chain_key(struct task_struct *curr)
1336 {
1337 #ifdef CONFIG_DEBUG_LOCKDEP
1338         struct held_lock *hlock, *prev_hlock = NULL;
1339         unsigned int i, id;
1340         u64 chain_key = 0;
1341
1342         for (i = 0; i < curr->lockdep_depth; i++) {
1343                 hlock = curr->held_locks + i;
1344                 if (chain_key != hlock->prev_chain_key) {
1345                         debug_locks_off();
1346                         printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1347                                 curr->lockdep_depth, i,
1348                                 (unsigned long long)chain_key,
1349                                 (unsigned long long)hlock->prev_chain_key);
1350                         WARN_ON(1);
1351                         return;
1352                 }
1353                 id = hlock->class - lock_classes;
1354                 DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS);
1355                 if (prev_hlock && (prev_hlock->irq_context !=
1356                                                         hlock->irq_context))
1357                         chain_key = 0;
1358                 chain_key = iterate_chain_key(chain_key, id);
1359                 prev_hlock = hlock;
1360         }
1361         if (chain_key != curr->curr_chain_key) {
1362                 debug_locks_off();
1363                 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1364                         curr->lockdep_depth, i,
1365                         (unsigned long long)chain_key,
1366                         (unsigned long long)curr->curr_chain_key);
1367                 WARN_ON(1);
1368         }
1369 #endif
1370 }
1371
1372 #ifdef CONFIG_TRACE_IRQFLAGS
1373
1374 /*
1375  * print irq inversion bug:
1376  */
1377 static int
1378 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1379                         struct held_lock *this, int forwards,
1380                         const char *irqclass)
1381 {
1382         __raw_spin_unlock(&hash_lock);
1383         debug_locks_off();
1384         if (debug_locks_silent)
1385                 return 0;
1386
1387         printk("\n=========================================================\n");
1388         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
1389         print_kernel_version();
1390         printk(  "---------------------------------------------------------\n");
1391         printk("%s/%d just changed the state of lock:\n",
1392                 curr->comm, curr->pid);
1393         print_lock(this);
1394         if (forwards)
1395                 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1396         else
1397                 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1398         print_lock_name(other);
1399         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1400
1401         printk("\nother info that might help us debug this:\n");
1402         lockdep_print_held_locks(curr);
1403
1404         printk("\nthe first lock's dependencies:\n");
1405         print_lock_dependencies(this->class, 0);
1406
1407         printk("\nthe second lock's dependencies:\n");
1408         print_lock_dependencies(other, 0);
1409
1410         printk("\nstack backtrace:\n");
1411         dump_stack();
1412
1413         return 0;
1414 }
1415
1416 /*
1417  * Prove that in the forwards-direction subgraph starting at <this>
1418  * there is no lock matching <mask>:
1419  */
1420 static int
1421 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1422                      enum lock_usage_bit bit, const char *irqclass)
1423 {
1424         int ret;
1425
1426         find_usage_bit = bit;
1427         /* fills in <forwards_match> */
1428         ret = find_usage_forwards(this->class, 0);
1429         if (!ret || ret == 1)
1430                 return ret;
1431
1432         return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1433 }
1434
1435 /*
1436  * Prove that in the backwards-direction subgraph starting at <this>
1437  * there is no lock matching <mask>:
1438  */
1439 static int
1440 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1441                       enum lock_usage_bit bit, const char *irqclass)
1442 {
1443         int ret;
1444
1445         find_usage_bit = bit;
1446         /* fills in <backwards_match> */
1447         ret = find_usage_backwards(this->class, 0);
1448         if (!ret || ret == 1)
1449                 return ret;
1450
1451         return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1452 }
1453
1454 static inline void print_irqtrace_events(struct task_struct *curr)
1455 {
1456         printk("irq event stamp: %u\n", curr->irq_events);
1457         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
1458         print_ip_sym(curr->hardirq_enable_ip);
1459         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1460         print_ip_sym(curr->hardirq_disable_ip);
1461         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
1462         print_ip_sym(curr->softirq_enable_ip);
1463         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1464         print_ip_sym(curr->softirq_disable_ip);
1465 }
1466
1467 #else
1468 static inline void print_irqtrace_events(struct task_struct *curr)
1469 {
1470 }
1471 #endif
1472
1473 static int
1474 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1475                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1476 {
1477         __raw_spin_unlock(&hash_lock);
1478         debug_locks_off();
1479         if (debug_locks_silent)
1480                 return 0;
1481
1482         printk("\n=================================\n");
1483         printk(  "[ INFO: inconsistent lock state ]\n");
1484         print_kernel_version();
1485         printk(  "---------------------------------\n");
1486
1487         printk("inconsistent {%s} -> {%s} usage.\n",
1488                 usage_str[prev_bit], usage_str[new_bit]);
1489
1490         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1491                 curr->comm, curr->pid,
1492                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1493                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1494                 trace_hardirqs_enabled(curr),
1495                 trace_softirqs_enabled(curr));
1496         print_lock(this);
1497
1498         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1499         print_stack_trace(this->class->usage_traces + prev_bit, 1);
1500
1501         print_irqtrace_events(curr);
1502         printk("\nother info that might help us debug this:\n");
1503         lockdep_print_held_locks(curr);
1504
1505         printk("\nstack backtrace:\n");
1506         dump_stack();
1507
1508         return 0;
1509 }
1510
1511 /*
1512  * Print out an error if an invalid bit is set:
1513  */
1514 static inline int
1515 valid_state(struct task_struct *curr, struct held_lock *this,
1516             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1517 {
1518         if (unlikely(this->class->usage_mask & (1 << bad_bit)))
1519                 return print_usage_bug(curr, this, bad_bit, new_bit);
1520         return 1;
1521 }
1522
1523 #define STRICT_READ_CHECKS      1
1524
1525 /*
1526  * Mark a lock with a usage bit, and validate the state transition:
1527  */
1528 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1529                      enum lock_usage_bit new_bit, unsigned long ip)
1530 {
1531         unsigned int new_mask = 1 << new_bit, ret = 1;
1532
1533         /*
1534          * If already set then do not dirty the cacheline,
1535          * nor do any checks:
1536          */
1537         if (likely(this->class->usage_mask & new_mask))
1538                 return 1;
1539
1540         __raw_spin_lock(&hash_lock);
1541         /*
1542          * Make sure we didnt race:
1543          */
1544         if (unlikely(this->class->usage_mask & new_mask)) {
1545                 __raw_spin_unlock(&hash_lock);
1546                 return 1;
1547         }
1548
1549         this->class->usage_mask |= new_mask;
1550
1551 #ifdef CONFIG_TRACE_IRQFLAGS
1552         if (new_bit == LOCK_ENABLED_HARDIRQS ||
1553                         new_bit == LOCK_ENABLED_HARDIRQS_READ)
1554                 ip = curr->hardirq_enable_ip;
1555         else if (new_bit == LOCK_ENABLED_SOFTIRQS ||
1556                         new_bit == LOCK_ENABLED_SOFTIRQS_READ)
1557                 ip = curr->softirq_enable_ip;
1558 #endif
1559         if (!save_trace(this->class->usage_traces + new_bit))
1560                 return 0;
1561
1562         switch (new_bit) {
1563 #ifdef CONFIG_TRACE_IRQFLAGS
1564         case LOCK_USED_IN_HARDIRQ:
1565                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1566                         return 0;
1567                 if (!valid_state(curr, this, new_bit,
1568                                  LOCK_ENABLED_HARDIRQS_READ))
1569                         return 0;
1570                 /*
1571                  * just marked it hardirq-safe, check that this lock
1572                  * took no hardirq-unsafe lock in the past:
1573                  */
1574                 if (!check_usage_forwards(curr, this,
1575                                           LOCK_ENABLED_HARDIRQS, "hard"))
1576                         return 0;
1577 #if STRICT_READ_CHECKS
1578                 /*
1579                  * just marked it hardirq-safe, check that this lock
1580                  * took no hardirq-unsafe-read lock in the past:
1581                  */
1582                 if (!check_usage_forwards(curr, this,
1583                                 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1584                         return 0;
1585 #endif
1586                 if (hardirq_verbose(this->class))
1587                         ret = 2;
1588                 break;
1589         case LOCK_USED_IN_SOFTIRQ:
1590                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1591                         return 0;
1592                 if (!valid_state(curr, this, new_bit,
1593                                  LOCK_ENABLED_SOFTIRQS_READ))
1594                         return 0;
1595                 /*
1596                  * just marked it softirq-safe, check that this lock
1597                  * took no softirq-unsafe lock in the past:
1598                  */
1599                 if (!check_usage_forwards(curr, this,
1600                                           LOCK_ENABLED_SOFTIRQS, "soft"))
1601                         return 0;
1602 #if STRICT_READ_CHECKS
1603                 /*
1604                  * just marked it softirq-safe, check that this lock
1605                  * took no softirq-unsafe-read lock in the past:
1606                  */
1607                 if (!check_usage_forwards(curr, this,
1608                                 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
1609                         return 0;
1610 #endif
1611                 if (softirq_verbose(this->class))
1612                         ret = 2;
1613                 break;
1614         case LOCK_USED_IN_HARDIRQ_READ:
1615                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1616                         return 0;
1617                 /*
1618                  * just marked it hardirq-read-safe, check that this lock
1619                  * took no hardirq-unsafe lock in the past:
1620                  */
1621                 if (!check_usage_forwards(curr, this,
1622                                           LOCK_ENABLED_HARDIRQS, "hard"))
1623                         return 0;
1624                 if (hardirq_verbose(this->class))
1625                         ret = 2;
1626                 break;
1627         case LOCK_USED_IN_SOFTIRQ_READ:
1628                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1629                         return 0;
1630                 /*
1631                  * just marked it softirq-read-safe, check that this lock
1632                  * took no softirq-unsafe lock in the past:
1633                  */
1634                 if (!check_usage_forwards(curr, this,
1635                                           LOCK_ENABLED_SOFTIRQS, "soft"))
1636                         return 0;
1637                 if (softirq_verbose(this->class))
1638                         ret = 2;
1639                 break;
1640         case LOCK_ENABLED_HARDIRQS:
1641                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1642                         return 0;
1643                 if (!valid_state(curr, this, new_bit,
1644                                  LOCK_USED_IN_HARDIRQ_READ))
1645                         return 0;
1646                 /*
1647                  * just marked it hardirq-unsafe, check that no hardirq-safe
1648                  * lock in the system ever took it in the past:
1649                  */
1650                 if (!check_usage_backwards(curr, this,
1651                                            LOCK_USED_IN_HARDIRQ, "hard"))
1652                         return 0;
1653 #if STRICT_READ_CHECKS
1654                 /*
1655                  * just marked it hardirq-unsafe, check that no
1656                  * hardirq-safe-read lock in the system ever took
1657                  * it in the past:
1658                  */
1659                 if (!check_usage_backwards(curr, this,
1660                                    LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
1661                         return 0;
1662 #endif
1663                 if (hardirq_verbose(this->class))
1664                         ret = 2;
1665                 break;
1666         case LOCK_ENABLED_SOFTIRQS:
1667                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1668                         return 0;
1669                 if (!valid_state(curr, this, new_bit,
1670                                  LOCK_USED_IN_SOFTIRQ_READ))
1671                         return 0;
1672                 /*
1673                  * just marked it softirq-unsafe, check that no softirq-safe
1674                  * lock in the system ever took it in the past:
1675                  */
1676                 if (!check_usage_backwards(curr, this,
1677                                            LOCK_USED_IN_SOFTIRQ, "soft"))
1678                         return 0;
1679 #if STRICT_READ_CHECKS
1680                 /*
1681                  * just marked it softirq-unsafe, check that no
1682                  * softirq-safe-read lock in the system ever took
1683                  * it in the past:
1684                  */
1685                 if (!check_usage_backwards(curr, this,
1686                                    LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
1687                         return 0;
1688 #endif
1689                 if (softirq_verbose(this->class))
1690                         ret = 2;
1691                 break;
1692         case LOCK_ENABLED_HARDIRQS_READ:
1693                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1694                         return 0;
1695 #if STRICT_READ_CHECKS
1696                 /*
1697                  * just marked it hardirq-read-unsafe, check that no
1698                  * hardirq-safe lock in the system ever took it in the past:
1699                  */
1700                 if (!check_usage_backwards(curr, this,
1701                                            LOCK_USED_IN_HARDIRQ, "hard"))
1702                         return 0;
1703 #endif
1704                 if (hardirq_verbose(this->class))
1705                         ret = 2;
1706                 break;
1707         case LOCK_ENABLED_SOFTIRQS_READ:
1708                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1709                         return 0;
1710 #if STRICT_READ_CHECKS
1711                 /*
1712                  * just marked it softirq-read-unsafe, check that no
1713                  * softirq-safe lock in the system ever took it in the past:
1714                  */
1715                 if (!check_usage_backwards(curr, this,
1716                                            LOCK_USED_IN_SOFTIRQ, "soft"))
1717                         return 0;
1718 #endif
1719                 if (softirq_verbose(this->class))
1720                         ret = 2;
1721                 break;
1722 #endif
1723         case LOCK_USED:
1724                 /*
1725                  * Add it to the global list of classes:
1726                  */
1727                 list_add_tail_rcu(&this->class->lock_entry, &all_lock_classes);
1728                 debug_atomic_dec(&nr_unused_locks);
1729                 break;
1730         default:
1731                 debug_locks_off();
1732                 WARN_ON(1);
1733                 return 0;
1734         }
1735
1736         __raw_spin_unlock(&hash_lock);
1737
1738         /*
1739          * We must printk outside of the hash_lock:
1740          */
1741         if (ret == 2) {
1742                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
1743                 print_lock(this);
1744                 print_irqtrace_events(curr);
1745                 dump_stack();
1746         }
1747
1748         return ret;
1749 }
1750
1751 #ifdef CONFIG_TRACE_IRQFLAGS
1752 /*
1753  * Mark all held locks with a usage bit:
1754  */
1755 static int
1756 mark_held_locks(struct task_struct *curr, int hardirq, unsigned long ip)
1757 {
1758         enum lock_usage_bit usage_bit;
1759         struct held_lock *hlock;
1760         int i;
1761
1762         for (i = 0; i < curr->lockdep_depth; i++) {
1763                 hlock = curr->held_locks + i;
1764
1765                 if (hardirq) {
1766                         if (hlock->read)
1767                                 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
1768                         else
1769                                 usage_bit = LOCK_ENABLED_HARDIRQS;
1770                 } else {
1771                         if (hlock->read)
1772                                 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
1773                         else
1774                                 usage_bit = LOCK_ENABLED_SOFTIRQS;
1775                 }
1776                 if (!mark_lock(curr, hlock, usage_bit, ip))
1777                         return 0;
1778         }
1779
1780         return 1;
1781 }
1782
1783 /*
1784  * Debugging helper: via this flag we know that we are in
1785  * 'early bootup code', and will warn about any invalid irqs-on event:
1786  */
1787 static int early_boot_irqs_enabled;
1788
1789 void early_boot_irqs_off(void)
1790 {
1791         early_boot_irqs_enabled = 0;
1792 }
1793
1794 void early_boot_irqs_on(void)
1795 {
1796         early_boot_irqs_enabled = 1;
1797 }
1798
1799 /*
1800  * Hardirqs will be enabled:
1801  */
1802 void trace_hardirqs_on(void)
1803 {
1804         struct task_struct *curr = current;
1805         unsigned long ip;
1806
1807         if (unlikely(!debug_locks || current->lockdep_recursion))
1808                 return;
1809
1810         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
1811                 return;
1812
1813         if (unlikely(curr->hardirqs_enabled)) {
1814                 debug_atomic_inc(&redundant_hardirqs_on);
1815                 return;
1816         }
1817         /* we'll do an OFF -> ON transition: */
1818         curr->hardirqs_enabled = 1;
1819         ip = (unsigned long) __builtin_return_address(0);
1820
1821         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1822                 return;
1823         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
1824                 return;
1825         /*
1826          * We are going to turn hardirqs on, so set the
1827          * usage bit for all held locks:
1828          */
1829         if (!mark_held_locks(curr, 1, ip))
1830                 return;
1831         /*
1832          * If we have softirqs enabled, then set the usage
1833          * bit for all held locks. (disabled hardirqs prevented
1834          * this bit from being set before)
1835          */
1836         if (curr->softirqs_enabled)
1837                 if (!mark_held_locks(curr, 0, ip))
1838                         return;
1839
1840         curr->hardirq_enable_ip = ip;
1841         curr->hardirq_enable_event = ++curr->irq_events;
1842         debug_atomic_inc(&hardirqs_on_events);
1843 }
1844
1845 EXPORT_SYMBOL(trace_hardirqs_on);
1846
1847 /*
1848  * Hardirqs were disabled:
1849  */
1850 void trace_hardirqs_off(void)
1851 {
1852         struct task_struct *curr = current;
1853
1854         if (unlikely(!debug_locks || current->lockdep_recursion))
1855                 return;
1856
1857         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1858                 return;
1859
1860         if (curr->hardirqs_enabled) {
1861                 /*
1862                  * We have done an ON -> OFF transition:
1863                  */
1864                 curr->hardirqs_enabled = 0;
1865                 curr->hardirq_disable_ip = _RET_IP_;
1866                 curr->hardirq_disable_event = ++curr->irq_events;
1867                 debug_atomic_inc(&hardirqs_off_events);
1868         } else
1869                 debug_atomic_inc(&redundant_hardirqs_off);
1870 }
1871
1872 EXPORT_SYMBOL(trace_hardirqs_off);
1873
1874 /*
1875  * Softirqs will be enabled:
1876  */
1877 void trace_softirqs_on(unsigned long ip)
1878 {
1879         struct task_struct *curr = current;
1880
1881         if (unlikely(!debug_locks))
1882                 return;
1883
1884         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1885                 return;
1886
1887         if (curr->softirqs_enabled) {
1888                 debug_atomic_inc(&redundant_softirqs_on);
1889                 return;
1890         }
1891
1892         /*
1893          * We'll do an OFF -> ON transition:
1894          */
1895         curr->softirqs_enabled = 1;
1896         curr->softirq_enable_ip = ip;
1897         curr->softirq_enable_event = ++curr->irq_events;
1898         debug_atomic_inc(&softirqs_on_events);
1899         /*
1900          * We are going to turn softirqs on, so set the
1901          * usage bit for all held locks, if hardirqs are
1902          * enabled too:
1903          */
1904         if (curr->hardirqs_enabled)
1905                 mark_held_locks(curr, 0, ip);
1906 }
1907
1908 /*
1909  * Softirqs were disabled:
1910  */
1911 void trace_softirqs_off(unsigned long ip)
1912 {
1913         struct task_struct *curr = current;
1914
1915         if (unlikely(!debug_locks))
1916                 return;
1917
1918         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1919                 return;
1920
1921         if (curr->softirqs_enabled) {
1922                 /*
1923                  * We have done an ON -> OFF transition:
1924                  */
1925                 curr->softirqs_enabled = 0;
1926                 curr->softirq_disable_ip = ip;
1927                 curr->softirq_disable_event = ++curr->irq_events;
1928                 debug_atomic_inc(&softirqs_off_events);
1929                 DEBUG_LOCKS_WARN_ON(!softirq_count());
1930         } else
1931                 debug_atomic_inc(&redundant_softirqs_off);
1932 }
1933
1934 #endif
1935
1936 /*
1937  * Initialize a lock instance's lock-class mapping info:
1938  */
1939 void lockdep_init_map(struct lockdep_map *lock, const char *name,
1940                       struct lock_class_key *key, int subclass)
1941 {
1942         if (unlikely(!debug_locks))
1943                 return;
1944
1945         if (DEBUG_LOCKS_WARN_ON(!key))
1946                 return;
1947         if (DEBUG_LOCKS_WARN_ON(!name))
1948                 return;
1949         /*
1950          * Sanity check, the lock-class key must be persistent:
1951          */
1952         if (!static_obj(key)) {
1953                 printk("BUG: key %p not in .data!\n", key);
1954                 DEBUG_LOCKS_WARN_ON(1);
1955                 return;
1956         }
1957         lock->name = name;
1958         lock->key = key;
1959         lock->class_cache = NULL;
1960         if (subclass)
1961                 register_lock_class(lock, subclass, 1);
1962 }
1963
1964 EXPORT_SYMBOL_GPL(lockdep_init_map);
1965
1966 /*
1967  * This gets called for every mutex_lock*()/spin_lock*() operation.
1968  * We maintain the dependency maps and validate the locking attempt:
1969  */
1970 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
1971                           int trylock, int read, int check, int hardirqs_off,
1972                           unsigned long ip)
1973 {
1974         struct task_struct *curr = current;
1975         struct lock_class *class = NULL;
1976         struct held_lock *hlock;
1977         unsigned int depth, id;
1978         int chain_head = 0;
1979         u64 chain_key;
1980
1981         if (unlikely(!debug_locks))
1982                 return 0;
1983
1984         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1985                 return 0;
1986
1987         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
1988                 debug_locks_off();
1989                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
1990                 printk("turning off the locking correctness validator.\n");
1991                 return 0;
1992         }
1993
1994         if (!subclass)
1995                 class = lock->class_cache;
1996         /*
1997          * Not cached yet or subclass?
1998          */
1999         if (unlikely(!class)) {
2000                 class = register_lock_class(lock, subclass, 0);
2001                 if (!class)
2002                         return 0;
2003         }
2004         debug_atomic_inc((atomic_t *)&class->ops);
2005         if (very_verbose(class)) {
2006                 printk("\nacquire class [%p] %s", class->key, class->name);
2007                 if (class->name_version > 1)
2008                         printk("#%d", class->name_version);
2009                 printk("\n");
2010                 dump_stack();
2011         }
2012
2013         /*
2014          * Add the lock to the list of currently held locks.
2015          * (we dont increase the depth just yet, up until the
2016          * dependency checks are done)
2017          */
2018         depth = curr->lockdep_depth;
2019         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2020                 return 0;
2021
2022         hlock = curr->held_locks + depth;
2023
2024         hlock->class = class;
2025         hlock->acquire_ip = ip;
2026         hlock->instance = lock;
2027         hlock->trylock = trylock;
2028         hlock->read = read;
2029         hlock->check = check;
2030         hlock->hardirqs_off = hardirqs_off;
2031
2032         if (check != 2)
2033                 goto out_calc_hash;
2034 #ifdef CONFIG_TRACE_IRQFLAGS
2035         /*
2036          * If non-trylock use in a hardirq or softirq context, then
2037          * mark the lock as used in these contexts:
2038          */
2039         if (!trylock) {
2040                 if (read) {
2041                         if (curr->hardirq_context)
2042                                 if (!mark_lock(curr, hlock,
2043                                                 LOCK_USED_IN_HARDIRQ_READ, ip))
2044                                         return 0;
2045                         if (curr->softirq_context)
2046                                 if (!mark_lock(curr, hlock,
2047                                                 LOCK_USED_IN_SOFTIRQ_READ, ip))
2048                                         return 0;
2049                 } else {
2050                         if (curr->hardirq_context)
2051                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ, ip))
2052                                         return 0;
2053                         if (curr->softirq_context)
2054                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ, ip))
2055                                         return 0;
2056                 }
2057         }
2058         if (!hardirqs_off) {
2059                 if (read) {
2060                         if (!mark_lock(curr, hlock,
2061                                         LOCK_ENABLED_HARDIRQS_READ, ip))
2062                                 return 0;
2063                         if (curr->softirqs_enabled)
2064                                 if (!mark_lock(curr, hlock,
2065                                                 LOCK_ENABLED_SOFTIRQS_READ, ip))
2066                                         return 0;
2067                 } else {
2068                         if (!mark_lock(curr, hlock,
2069                                         LOCK_ENABLED_HARDIRQS, ip))
2070                                 return 0;
2071                         if (curr->softirqs_enabled)
2072                                 if (!mark_lock(curr, hlock,
2073                                                 LOCK_ENABLED_SOFTIRQS, ip))
2074                                         return 0;
2075                 }
2076         }
2077 #endif
2078         /* mark it as used: */
2079         if (!mark_lock(curr, hlock, LOCK_USED, ip))
2080                 return 0;
2081 out_calc_hash:
2082         /*
2083          * Calculate the chain hash: it's the combined has of all the
2084          * lock keys along the dependency chain. We save the hash value
2085          * at every step so that we can get the current hash easily
2086          * after unlock. The chain hash is then used to cache dependency
2087          * results.
2088          *
2089          * The 'key ID' is what is the most compact key value to drive
2090          * the hash, not class->key.
2091          */
2092         id = class - lock_classes;
2093         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2094                 return 0;
2095
2096         chain_key = curr->curr_chain_key;
2097         if (!depth) {
2098                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2099                         return 0;
2100                 chain_head = 1;
2101         }
2102
2103         hlock->prev_chain_key = chain_key;
2104
2105 #ifdef CONFIG_TRACE_IRQFLAGS
2106         /*
2107          * Keep track of points where we cross into an interrupt context:
2108          */
2109         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2110                                 curr->softirq_context;
2111         if (depth) {
2112                 struct held_lock *prev_hlock;
2113
2114                 prev_hlock = curr->held_locks + depth-1;
2115                 /*
2116                  * If we cross into another context, reset the
2117                  * hash key (this also prevents the checking and the
2118                  * adding of the dependency to 'prev'):
2119                  */
2120                 if (prev_hlock->irq_context != hlock->irq_context) {
2121                         chain_key = 0;
2122                         chain_head = 1;
2123                 }
2124         }
2125 #endif
2126         chain_key = iterate_chain_key(chain_key, id);
2127         curr->curr_chain_key = chain_key;
2128
2129         /*
2130          * Trylock needs to maintain the stack of held locks, but it
2131          * does not add new dependencies, because trylock can be done
2132          * in any order.
2133          *
2134          * We look up the chain_key and do the O(N^2) check and update of
2135          * the dependencies only if this is a new dependency chain.
2136          * (If lookup_chain_cache() returns with 1 it acquires
2137          * hash_lock for us)
2138          */
2139         if (!trylock && (check == 2) && lookup_chain_cache(chain_key)) {
2140                 /*
2141                  * Check whether last held lock:
2142                  *
2143                  * - is irq-safe, if this lock is irq-unsafe
2144                  * - is softirq-safe, if this lock is hardirq-unsafe
2145                  *
2146                  * And check whether the new lock's dependency graph
2147                  * could lead back to the previous lock.
2148                  *
2149                  * any of these scenarios could lead to a deadlock. If
2150                  * All validations
2151                  */
2152                 int ret = check_deadlock(curr, hlock, lock, read);
2153
2154                 if (!ret)
2155                         return 0;
2156                 /*
2157                  * Mark recursive read, as we jump over it when
2158                  * building dependencies (just like we jump over
2159                  * trylock entries):
2160                  */
2161                 if (ret == 2)
2162                         hlock->read = 2;
2163                 /*
2164                  * Add dependency only if this lock is not the head
2165                  * of the chain, and if it's not a secondary read-lock:
2166                  */
2167                 if (!chain_head && ret != 2)
2168                         if (!check_prevs_add(curr, hlock))
2169                                 return 0;
2170                 __raw_spin_unlock(&hash_lock);
2171         }
2172         curr->lockdep_depth++;
2173         check_chain_key(curr);
2174         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2175                 debug_locks_off();
2176                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2177                 printk("turning off the locking correctness validator.\n");
2178                 return 0;
2179         }
2180         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2181                 max_lockdep_depth = curr->lockdep_depth;
2182
2183         return 1;
2184 }
2185
2186 static int
2187 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2188                            unsigned long ip)
2189 {
2190         if (!debug_locks_off())
2191                 return 0;
2192         if (debug_locks_silent)
2193                 return 0;
2194
2195         printk("\n=====================================\n");
2196         printk(  "[ BUG: bad unlock balance detected! ]\n");
2197         printk(  "-------------------------------------\n");
2198         printk("%s/%d is trying to release lock (",
2199                 curr->comm, curr->pid);
2200         print_lockdep_cache(lock);
2201         printk(") at:\n");
2202         print_ip_sym(ip);
2203         printk("but there are no more locks to release!\n");
2204         printk("\nother info that might help us debug this:\n");
2205         lockdep_print_held_locks(curr);
2206
2207         printk("\nstack backtrace:\n");
2208         dump_stack();
2209
2210         return 0;
2211 }
2212
2213 /*
2214  * Common debugging checks for both nested and non-nested unlock:
2215  */
2216 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2217                         unsigned long ip)
2218 {
2219         if (unlikely(!debug_locks))
2220                 return 0;
2221         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2222                 return 0;
2223
2224         if (curr->lockdep_depth <= 0)
2225                 return print_unlock_inbalance_bug(curr, lock, ip);
2226
2227         return 1;
2228 }
2229
2230 /*
2231  * Remove the lock to the list of currently held locks in a
2232  * potentially non-nested (out of order) manner. This is a
2233  * relatively rare operation, as all the unlock APIs default
2234  * to nested mode (which uses lock_release()):
2235  */
2236 static int
2237 lock_release_non_nested(struct task_struct *curr,
2238                         struct lockdep_map *lock, unsigned long ip)
2239 {
2240         struct held_lock *hlock, *prev_hlock;
2241         unsigned int depth;
2242         int i;
2243
2244         /*
2245          * Check whether the lock exists in the current stack
2246          * of held locks:
2247          */
2248         depth = curr->lockdep_depth;
2249         if (DEBUG_LOCKS_WARN_ON(!depth))
2250                 return 0;
2251
2252         prev_hlock = NULL;
2253         for (i = depth-1; i >= 0; i--) {
2254                 hlock = curr->held_locks + i;
2255                 /*
2256                  * We must not cross into another context:
2257                  */
2258                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2259                         break;
2260                 if (hlock->instance == lock)
2261                         goto found_it;
2262                 prev_hlock = hlock;
2263         }
2264         return print_unlock_inbalance_bug(curr, lock, ip);
2265
2266 found_it:
2267         /*
2268          * We have the right lock to unlock, 'hlock' points to it.
2269          * Now we remove it from the stack, and add back the other
2270          * entries (if any), recalculating the hash along the way:
2271          */
2272         curr->lockdep_depth = i;
2273         curr->curr_chain_key = hlock->prev_chain_key;
2274
2275         for (i++; i < depth; i++) {
2276                 hlock = curr->held_locks + i;
2277                 if (!__lock_acquire(hlock->instance,
2278                         hlock->class->subclass, hlock->trylock,
2279                                 hlock->read, hlock->check, hlock->hardirqs_off,
2280                                 hlock->acquire_ip))
2281                         return 0;
2282         }
2283
2284         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2285                 return 0;
2286         return 1;
2287 }
2288
2289 /*
2290  * Remove the lock to the list of currently held locks - this gets
2291  * called on mutex_unlock()/spin_unlock*() (or on a failed
2292  * mutex_lock_interruptible()). This is done for unlocks that nest
2293  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2294  */
2295 static int lock_release_nested(struct task_struct *curr,
2296                                struct lockdep_map *lock, unsigned long ip)
2297 {
2298         struct held_lock *hlock;
2299         unsigned int depth;
2300
2301         /*
2302          * Pop off the top of the lock stack:
2303          */
2304         depth = curr->lockdep_depth - 1;
2305         hlock = curr->held_locks + depth;
2306
2307         /*
2308          * Is the unlock non-nested:
2309          */
2310         if (hlock->instance != lock)
2311                 return lock_release_non_nested(curr, lock, ip);
2312         curr->lockdep_depth--;
2313
2314         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2315                 return 0;
2316
2317         curr->curr_chain_key = hlock->prev_chain_key;
2318
2319 #ifdef CONFIG_DEBUG_LOCKDEP
2320         hlock->prev_chain_key = 0;
2321         hlock->class = NULL;
2322         hlock->acquire_ip = 0;
2323         hlock->irq_context = 0;
2324 #endif
2325         return 1;
2326 }
2327
2328 /*
2329  * Remove the lock to the list of currently held locks - this gets
2330  * called on mutex_unlock()/spin_unlock*() (or on a failed
2331  * mutex_lock_interruptible()). This is done for unlocks that nest
2332  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2333  */
2334 static void
2335 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2336 {
2337         struct task_struct *curr = current;
2338
2339         if (!check_unlock(curr, lock, ip))
2340                 return;
2341
2342         if (nested) {
2343                 if (!lock_release_nested(curr, lock, ip))
2344                         return;
2345         } else {
2346                 if (!lock_release_non_nested(curr, lock, ip))
2347                         return;
2348         }
2349
2350         check_chain_key(curr);
2351 }
2352
2353 /*
2354  * Check whether we follow the irq-flags state precisely:
2355  */
2356 static void check_flags(unsigned long flags)
2357 {
2358 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2359         if (!debug_locks)
2360                 return;
2361
2362         if (irqs_disabled_flags(flags))
2363                 DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled);
2364         else
2365                 DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled);
2366
2367         /*
2368          * We dont accurately track softirq state in e.g.
2369          * hardirq contexts (such as on 4KSTACKS), so only
2370          * check if not in hardirq contexts:
2371          */
2372         if (!hardirq_count()) {
2373                 if (softirq_count())
2374                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2375                 else
2376                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2377         }
2378
2379         if (!debug_locks)
2380                 print_irqtrace_events(current);
2381 #endif
2382 }
2383
2384 /*
2385  * We are not always called with irqs disabled - do that here,
2386  * and also avoid lockdep recursion:
2387  */
2388 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2389                   int trylock, int read, int check, unsigned long ip)
2390 {
2391         unsigned long flags;
2392
2393         if (unlikely(current->lockdep_recursion))
2394                 return;
2395
2396         raw_local_irq_save(flags);
2397         check_flags(flags);
2398
2399         current->lockdep_recursion = 1;
2400         __lock_acquire(lock, subclass, trylock, read, check,
2401                        irqs_disabled_flags(flags), ip);
2402         current->lockdep_recursion = 0;
2403         raw_local_irq_restore(flags);
2404 }
2405
2406 EXPORT_SYMBOL_GPL(lock_acquire);
2407
2408 void lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2409 {
2410         unsigned long flags;
2411
2412         if (unlikely(current->lockdep_recursion))
2413                 return;
2414
2415         raw_local_irq_save(flags);
2416         check_flags(flags);
2417         current->lockdep_recursion = 1;
2418         __lock_release(lock, nested, ip);
2419         current->lockdep_recursion = 0;
2420         raw_local_irq_restore(flags);
2421 }
2422
2423 EXPORT_SYMBOL_GPL(lock_release);
2424
2425 /*
2426  * Used by the testsuite, sanitize the validator state
2427  * after a simulated failure:
2428  */
2429
2430 void lockdep_reset(void)
2431 {
2432         unsigned long flags;
2433
2434         raw_local_irq_save(flags);
2435         current->curr_chain_key = 0;
2436         current->lockdep_depth = 0;
2437         current->lockdep_recursion = 0;
2438         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
2439         nr_hardirq_chains = 0;
2440         nr_softirq_chains = 0;
2441         nr_process_chains = 0;
2442         debug_locks = 1;
2443         raw_local_irq_restore(flags);
2444 }
2445
2446 static void zap_class(struct lock_class *class)
2447 {
2448         int i;
2449
2450         /*
2451          * Remove all dependencies this lock is
2452          * involved in:
2453          */
2454         for (i = 0; i < nr_list_entries; i++) {
2455                 if (list_entries[i].class == class)
2456                         list_del_rcu(&list_entries[i].entry);
2457         }
2458         /*
2459          * Unhash the class and remove it from the all_lock_classes list:
2460          */
2461         list_del_rcu(&class->hash_entry);
2462         list_del_rcu(&class->lock_entry);
2463
2464 }
2465
2466 static inline int within(void *addr, void *start, unsigned long size)
2467 {
2468         return addr >= start && addr < start + size;
2469 }
2470
2471 void lockdep_free_key_range(void *start, unsigned long size)
2472 {
2473         struct lock_class *class, *next;
2474         struct list_head *head;
2475         unsigned long flags;
2476         int i;
2477
2478         raw_local_irq_save(flags);
2479         __raw_spin_lock(&hash_lock);
2480
2481         /*
2482          * Unhash all classes that were created by this module:
2483          */
2484         for (i = 0; i < CLASSHASH_SIZE; i++) {
2485                 head = classhash_table + i;
2486                 if (list_empty(head))
2487                         continue;
2488                 list_for_each_entry_safe(class, next, head, hash_entry)
2489                         if (within(class->key, start, size))
2490                                 zap_class(class);
2491         }
2492
2493         __raw_spin_unlock(&hash_lock);
2494         raw_local_irq_restore(flags);
2495 }
2496
2497 void lockdep_reset_lock(struct lockdep_map *lock)
2498 {
2499         struct lock_class *class, *next;
2500         struct list_head *head;
2501         unsigned long flags;
2502         int i, j;
2503
2504         raw_local_irq_save(flags);
2505
2506         /*
2507          * Remove all classes this lock might have:
2508          */
2509         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
2510                 /*
2511                  * If the class exists we look it up and zap it:
2512                  */
2513                 class = look_up_lock_class(lock, j);
2514                 if (class)
2515                         zap_class(class);
2516         }
2517         /*
2518          * Debug check: in the end all mapped classes should
2519          * be gone.
2520          */
2521         __raw_spin_lock(&hash_lock);
2522         for (i = 0; i < CLASSHASH_SIZE; i++) {
2523                 head = classhash_table + i;
2524                 if (list_empty(head))
2525                         continue;
2526                 list_for_each_entry_safe(class, next, head, hash_entry) {
2527                         if (unlikely(class == lock->class_cache)) {
2528                                 __raw_spin_unlock(&hash_lock);
2529                                 DEBUG_LOCKS_WARN_ON(1);
2530                                 goto out_restore;
2531                         }
2532                 }
2533         }
2534         __raw_spin_unlock(&hash_lock);
2535
2536 out_restore:
2537         raw_local_irq_restore(flags);
2538 }
2539
2540 void __init lockdep_init(void)
2541 {
2542         int i;
2543
2544         /*
2545          * Some architectures have their own start_kernel()
2546          * code which calls lockdep_init(), while we also
2547          * call lockdep_init() from the start_kernel() itself,
2548          * and we want to initialize the hashes only once:
2549          */
2550         if (lockdep_initialized)
2551                 return;
2552
2553         for (i = 0; i < CLASSHASH_SIZE; i++)
2554                 INIT_LIST_HEAD(classhash_table + i);
2555
2556         for (i = 0; i < CHAINHASH_SIZE; i++)
2557                 INIT_LIST_HEAD(chainhash_table + i);
2558
2559         lockdep_initialized = 1;
2560 }
2561
2562 void __init lockdep_info(void)
2563 {
2564         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
2565
2566         printk("... MAX_LOCKDEP_SUBCLASSES:    %lu\n", MAX_LOCKDEP_SUBCLASSES);
2567         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
2568         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
2569         printk("... CLASSHASH_SIZE:           %lu\n", CLASSHASH_SIZE);
2570         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
2571         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
2572         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
2573
2574         printk(" memory used by lock dependency info: %lu kB\n",
2575                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
2576                 sizeof(struct list_head) * CLASSHASH_SIZE +
2577                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
2578                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
2579                 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
2580
2581         printk(" per task-struct memory footprint: %lu bytes\n",
2582                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
2583
2584 #ifdef CONFIG_DEBUG_LOCKDEP
2585         if (lockdep_init_error)
2586                 printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n");
2587 #endif
2588 }
2589
2590 static inline int in_range(const void *start, const void *addr, const void *end)
2591 {
2592         return addr >= start && addr <= end;
2593 }
2594
2595 static void
2596 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
2597                      const void *mem_to, struct held_lock *hlock)
2598 {
2599         if (!debug_locks_off())
2600                 return;
2601         if (debug_locks_silent)
2602                 return;
2603
2604         printk("\n=========================\n");
2605         printk(  "[ BUG: held lock freed! ]\n");
2606         printk(  "-------------------------\n");
2607         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
2608                 curr->comm, curr->pid, mem_from, mem_to-1);
2609         print_lock(hlock);
2610         lockdep_print_held_locks(curr);
2611
2612         printk("\nstack backtrace:\n");
2613         dump_stack();
2614 }
2615
2616 /*
2617  * Called when kernel memory is freed (or unmapped), or if a lock
2618  * is destroyed or reinitialized - this code checks whether there is
2619  * any held lock in the memory range of <from> to <to>:
2620  */
2621 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
2622 {
2623         const void *mem_to = mem_from + mem_len, *lock_from, *lock_to;
2624         struct task_struct *curr = current;
2625         struct held_lock *hlock;
2626         unsigned long flags;
2627         int i;
2628
2629         if (unlikely(!debug_locks))
2630                 return;
2631
2632         local_irq_save(flags);
2633         for (i = 0; i < curr->lockdep_depth; i++) {
2634                 hlock = curr->held_locks + i;
2635
2636                 lock_from = (void *)hlock->instance;
2637                 lock_to = (void *)(hlock->instance + 1);
2638
2639                 if (!in_range(mem_from, lock_from, mem_to) &&
2640                                         !in_range(mem_from, lock_to, mem_to))
2641                         continue;
2642
2643                 print_freed_lock_bug(curr, mem_from, mem_to, hlock);
2644                 break;
2645         }
2646         local_irq_restore(flags);
2647 }
2648
2649 static void print_held_locks_bug(struct task_struct *curr)
2650 {
2651         if (!debug_locks_off())
2652                 return;
2653         if (debug_locks_silent)
2654                 return;
2655
2656         printk("\n=====================================\n");
2657         printk(  "[ BUG: lock held at task exit time! ]\n");
2658         printk(  "-------------------------------------\n");
2659         printk("%s/%d is exiting with locks still held!\n",
2660                 curr->comm, curr->pid);
2661         lockdep_print_held_locks(curr);
2662
2663         printk("\nstack backtrace:\n");
2664         dump_stack();
2665 }
2666
2667 void debug_check_no_locks_held(struct task_struct *task)
2668 {
2669         if (unlikely(task->lockdep_depth > 0))
2670                 print_held_locks_bug(task);
2671 }
2672
2673 void debug_show_all_locks(void)
2674 {
2675         struct task_struct *g, *p;
2676         int count = 10;
2677         int unlock = 1;
2678
2679         printk("\nShowing all locks held in the system:\n");
2680
2681         /*
2682          * Here we try to get the tasklist_lock as hard as possible,
2683          * if not successful after 2 seconds we ignore it (but keep
2684          * trying). This is to enable a debug printout even if a
2685          * tasklist_lock-holding task deadlocks or crashes.
2686          */
2687 retry:
2688         if (!read_trylock(&tasklist_lock)) {
2689                 if (count == 10)
2690                         printk("hm, tasklist_lock locked, retrying... ");
2691                 if (count) {
2692                         count--;
2693                         printk(" #%d", 10-count);
2694                         mdelay(200);
2695                         goto retry;
2696                 }
2697                 printk(" ignoring it.\n");
2698                 unlock = 0;
2699         }
2700         if (count != 10)
2701                 printk(" locked it.\n");
2702
2703         do_each_thread(g, p) {
2704                 if (p->lockdep_depth)
2705                         lockdep_print_held_locks(p);
2706                 if (!unlock)
2707                         if (read_trylock(&tasklist_lock))
2708                                 unlock = 1;
2709         } while_each_thread(g, p);
2710
2711         printk("\n");
2712         printk("=============================================\n\n");
2713
2714         if (unlock)
2715                 read_unlock(&tasklist_lock);
2716 }
2717
2718 EXPORT_SYMBOL_GPL(debug_show_all_locks);
2719
2720 void debug_show_held_locks(struct task_struct *task)
2721 {
2722         lockdep_print_held_locks(task);
2723 }
2724
2725 EXPORT_SYMBOL_GPL(debug_show_held_locks);
2726