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