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