[PATCH] IPC namespace - utils
[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 static int noinline print_infinite_recursion_bug(void)
579 {
580         __raw_spin_unlock(&hash_lock);
581         DEBUG_LOCKS_WARN_ON(1);
582
583         return 0;
584 }
585
586 /*
587  * Prove that the dependency graph starting at <entry> can not
588  * lead to <target>. Print an error and return 0 if it does.
589  */
590 static noinline int
591 check_noncircular(struct lock_class *source, unsigned int depth)
592 {
593         struct lock_list *entry;
594
595         debug_atomic_inc(&nr_cyclic_check_recursions);
596         if (depth > max_recursion_depth)
597                 max_recursion_depth = depth;
598         if (depth >= 20)
599                 return print_infinite_recursion_bug();
600         /*
601          * Check this lock's dependency list:
602          */
603         list_for_each_entry(entry, &source->locks_after, entry) {
604                 if (entry->class == check_target->class)
605                         return print_circular_bug_header(entry, depth+1);
606                 debug_atomic_inc(&nr_cyclic_checks);
607                 if (!check_noncircular(entry->class, depth+1))
608                         return print_circular_bug_entry(entry, depth+1);
609         }
610         return 1;
611 }
612
613 static int very_verbose(struct lock_class *class)
614 {
615 #if VERY_VERBOSE
616         return class_filter(class);
617 #endif
618         return 0;
619 }
620 #ifdef CONFIG_TRACE_IRQFLAGS
621
622 /*
623  * Forwards and backwards subgraph searching, for the purposes of
624  * proving that two subgraphs can be connected by a new dependency
625  * without creating any illegal irq-safe -> irq-unsafe lock dependency.
626  */
627 static enum lock_usage_bit find_usage_bit;
628 static struct lock_class *forwards_match, *backwards_match;
629
630 /*
631  * Find a node in the forwards-direction dependency sub-graph starting
632  * at <source> that matches <find_usage_bit>.
633  *
634  * Return 2 if such a node exists in the subgraph, and put that node
635  * into <forwards_match>.
636  *
637  * Return 1 otherwise and keep <forwards_match> unchanged.
638  * Return 0 on error.
639  */
640 static noinline int
641 find_usage_forwards(struct lock_class *source, unsigned int depth)
642 {
643         struct lock_list *entry;
644         int ret;
645
646         if (depth > max_recursion_depth)
647                 max_recursion_depth = depth;
648         if (depth >= 20)
649                 return print_infinite_recursion_bug();
650
651         debug_atomic_inc(&nr_find_usage_forwards_checks);
652         if (source->usage_mask & (1 << find_usage_bit)) {
653                 forwards_match = source;
654                 return 2;
655         }
656
657         /*
658          * Check this lock's dependency list:
659          */
660         list_for_each_entry(entry, &source->locks_after, entry) {
661                 debug_atomic_inc(&nr_find_usage_forwards_recursions);
662                 ret = find_usage_forwards(entry->class, depth+1);
663                 if (ret == 2 || ret == 0)
664                         return ret;
665         }
666         return 1;
667 }
668
669 /*
670  * Find a node in the backwards-direction dependency sub-graph starting
671  * at <source> that matches <find_usage_bit>.
672  *
673  * Return 2 if such a node exists in the subgraph, and put that node
674  * into <backwards_match>.
675  *
676  * Return 1 otherwise and keep <backwards_match> unchanged.
677  * Return 0 on error.
678  */
679 static noinline int
680 find_usage_backwards(struct lock_class *source, unsigned int depth)
681 {
682         struct lock_list *entry;
683         int ret;
684
685         if (depth > max_recursion_depth)
686                 max_recursion_depth = depth;
687         if (depth >= 20)
688                 return print_infinite_recursion_bug();
689
690         debug_atomic_inc(&nr_find_usage_backwards_checks);
691         if (source->usage_mask & (1 << find_usage_bit)) {
692                 backwards_match = source;
693                 return 2;
694         }
695
696         /*
697          * Check this lock's dependency list:
698          */
699         list_for_each_entry(entry, &source->locks_before, entry) {
700                 debug_atomic_inc(&nr_find_usage_backwards_recursions);
701                 ret = find_usage_backwards(entry->class, depth+1);
702                 if (ret == 2 || ret == 0)
703                         return ret;
704         }
705         return 1;
706 }
707
708 static int
709 print_bad_irq_dependency(struct task_struct *curr,
710                          struct held_lock *prev,
711                          struct held_lock *next,
712                          enum lock_usage_bit bit1,
713                          enum lock_usage_bit bit2,
714                          const char *irqclass)
715 {
716         __raw_spin_unlock(&hash_lock);
717         debug_locks_off();
718         if (debug_locks_silent)
719                 return 0;
720
721         printk("\n======================================================\n");
722         printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
723                 irqclass, irqclass);
724         print_kernel_version();
725         printk(  "------------------------------------------------------\n");
726         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
727                 curr->comm, curr->pid,
728                 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
729                 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
730                 curr->hardirqs_enabled,
731                 curr->softirqs_enabled);
732         print_lock(next);
733
734         printk("\nand this task is already holding:\n");
735         print_lock(prev);
736         printk("which would create a new lock dependency:\n");
737         print_lock_name(prev->class);
738         printk(" ->");
739         print_lock_name(next->class);
740         printk("\n");
741
742         printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
743                 irqclass);
744         print_lock_name(backwards_match);
745         printk("\n... which became %s-irq-safe at:\n", irqclass);
746
747         print_stack_trace(backwards_match->usage_traces + bit1, 1);
748
749         printk("\nto a %s-irq-unsafe lock:\n", irqclass);
750         print_lock_name(forwards_match);
751         printk("\n... which became %s-irq-unsafe at:\n", irqclass);
752         printk("...");
753
754         print_stack_trace(forwards_match->usage_traces + bit2, 1);
755
756         printk("\nother info that might help us debug this:\n\n");
757         lockdep_print_held_locks(curr);
758
759         printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
760         print_lock_dependencies(backwards_match, 0);
761
762         printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
763         print_lock_dependencies(forwards_match, 0);
764
765         printk("\nstack backtrace:\n");
766         dump_stack();
767
768         return 0;
769 }
770
771 static int
772 check_usage(struct task_struct *curr, struct held_lock *prev,
773             struct held_lock *next, enum lock_usage_bit bit_backwards,
774             enum lock_usage_bit bit_forwards, const char *irqclass)
775 {
776         int ret;
777
778         find_usage_bit = bit_backwards;
779         /* fills in <backwards_match> */
780         ret = find_usage_backwards(prev->class, 0);
781         if (!ret || ret == 1)
782                 return ret;
783
784         find_usage_bit = bit_forwards;
785         ret = find_usage_forwards(next->class, 0);
786         if (!ret || ret == 1)
787                 return ret;
788         /* ret == 2 */
789         return print_bad_irq_dependency(curr, prev, next,
790                         bit_backwards, bit_forwards, irqclass);
791 }
792
793 #endif
794
795 static int
796 print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
797                    struct held_lock *next)
798 {
799         debug_locks_off();
800         __raw_spin_unlock(&hash_lock);
801         if (debug_locks_silent)
802                 return 0;
803
804         printk("\n=============================================\n");
805         printk(  "[ INFO: possible recursive locking detected ]\n");
806         print_kernel_version();
807         printk(  "---------------------------------------------\n");
808         printk("%s/%d is trying to acquire lock:\n",
809                 curr->comm, curr->pid);
810         print_lock(next);
811         printk("\nbut task is already holding lock:\n");
812         print_lock(prev);
813
814         printk("\nother info that might help us debug this:\n");
815         lockdep_print_held_locks(curr);
816
817         printk("\nstack backtrace:\n");
818         dump_stack();
819
820         return 0;
821 }
822
823 /*
824  * Check whether we are holding such a class already.
825  *
826  * (Note that this has to be done separately, because the graph cannot
827  * detect such classes of deadlocks.)
828  *
829  * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
830  */
831 static int
832 check_deadlock(struct task_struct *curr, struct held_lock *next,
833                struct lockdep_map *next_instance, int read)
834 {
835         struct held_lock *prev;
836         int i;
837
838         for (i = 0; i < curr->lockdep_depth; i++) {
839                 prev = curr->held_locks + i;
840                 if (prev->class != next->class)
841                         continue;
842                 /*
843                  * Allow read-after-read recursion of the same
844                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
845                  */
846                 if ((read == 2) && prev->read)
847                         return 2;
848                 return print_deadlock_bug(curr, prev, next);
849         }
850         return 1;
851 }
852
853 /*
854  * There was a chain-cache miss, and we are about to add a new dependency
855  * to a previous lock. We recursively validate the following rules:
856  *
857  *  - would the adding of the <prev> -> <next> dependency create a
858  *    circular dependency in the graph? [== circular deadlock]
859  *
860  *  - does the new prev->next dependency connect any hardirq-safe lock
861  *    (in the full backwards-subgraph starting at <prev>) with any
862  *    hardirq-unsafe lock (in the full forwards-subgraph starting at
863  *    <next>)? [== illegal lock inversion with hardirq contexts]
864  *
865  *  - does the new prev->next dependency connect any softirq-safe lock
866  *    (in the full backwards-subgraph starting at <prev>) with any
867  *    softirq-unsafe lock (in the full forwards-subgraph starting at
868  *    <next>)? [== illegal lock inversion with softirq contexts]
869  *
870  * any of these scenarios could lead to a deadlock.
871  *
872  * Then if all the validations pass, we add the forwards and backwards
873  * dependency.
874  */
875 static int
876 check_prev_add(struct task_struct *curr, struct held_lock *prev,
877                struct held_lock *next)
878 {
879         struct lock_list *entry;
880         int ret;
881
882         /*
883          * Prove that the new <prev> -> <next> dependency would not
884          * create a circular dependency in the graph. (We do this by
885          * forward-recursing into the graph starting at <next>, and
886          * checking whether we can reach <prev>.)
887          *
888          * We are using global variables to control the recursion, to
889          * keep the stackframe size of the recursive functions low:
890          */
891         check_source = next;
892         check_target = prev;
893         if (!(check_noncircular(next->class, 0)))
894                 return print_circular_bug_tail();
895
896 #ifdef CONFIG_TRACE_IRQFLAGS
897         /*
898          * Prove that the new dependency does not connect a hardirq-safe
899          * lock with a hardirq-unsafe lock - to achieve this we search
900          * the backwards-subgraph starting at <prev>, and the
901          * forwards-subgraph starting at <next>:
902          */
903         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
904                                         LOCK_ENABLED_HARDIRQS, "hard"))
905                 return 0;
906
907         /*
908          * Prove that the new dependency does not connect a hardirq-safe-read
909          * lock with a hardirq-unsafe lock - to achieve this we search
910          * the backwards-subgraph starting at <prev>, and the
911          * forwards-subgraph starting at <next>:
912          */
913         if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
914                                         LOCK_ENABLED_HARDIRQS, "hard-read"))
915                 return 0;
916
917         /*
918          * Prove that the new dependency does not connect a softirq-safe
919          * lock with a softirq-unsafe lock - to achieve this we search
920          * the backwards-subgraph starting at <prev>, and the
921          * forwards-subgraph starting at <next>:
922          */
923         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
924                                         LOCK_ENABLED_SOFTIRQS, "soft"))
925                 return 0;
926         /*
927          * Prove that the new dependency does not connect a softirq-safe-read
928          * lock with a softirq-unsafe lock - to achieve this we search
929          * the backwards-subgraph starting at <prev>, and the
930          * forwards-subgraph starting at <next>:
931          */
932         if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
933                                         LOCK_ENABLED_SOFTIRQS, "soft"))
934                 return 0;
935 #endif
936         /*
937          * For recursive read-locks we do all the dependency checks,
938          * but we dont store read-triggered dependencies (only
939          * write-triggered dependencies). This ensures that only the
940          * write-side dependencies matter, and that if for example a
941          * write-lock never takes any other locks, then the reads are
942          * equivalent to a NOP.
943          */
944         if (next->read == 2 || prev->read == 2)
945                 return 1;
946         /*
947          * Is the <prev> -> <next> dependency already present?
948          *
949          * (this may occur even though this is a new chain: consider
950          *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
951          *  chains - the second one will be new, but L1 already has
952          *  L2 added to its dependency list, due to the first chain.)
953          */
954         list_for_each_entry(entry, &prev->class->locks_after, entry) {
955                 if (entry->class == next->class)
956                         return 2;
957         }
958
959         /*
960          * Ok, all validations passed, add the new lock
961          * to the previous lock's dependency list:
962          */
963         ret = add_lock_to_list(prev->class, next->class,
964                                &prev->class->locks_after, next->acquire_ip);
965         if (!ret)
966                 return 0;
967         /*
968          * Return value of 2 signals 'dependency already added',
969          * in that case we dont have to add the backlink either.
970          */
971         if (ret == 2)
972                 return 2;
973         ret = add_lock_to_list(next->class, prev->class,
974                                &next->class->locks_before, next->acquire_ip);
975
976         /*
977          * Debugging printouts:
978          */
979         if (verbose(prev->class) || verbose(next->class)) {
980                 __raw_spin_unlock(&hash_lock);
981                 printk("\n new dependency: ");
982                 print_lock_name(prev->class);
983                 printk(" => ");
984                 print_lock_name(next->class);
985                 printk("\n");
986                 dump_stack();
987                 __raw_spin_lock(&hash_lock);
988         }
989         return 1;
990 }
991
992 /*
993  * Add the dependency to all directly-previous locks that are 'relevant'.
994  * The ones that are relevant are (in increasing distance from curr):
995  * all consecutive trylock entries and the final non-trylock entry - or
996  * the end of this context's lock-chain - whichever comes first.
997  */
998 static int
999 check_prevs_add(struct task_struct *curr, struct held_lock *next)
1000 {
1001         int depth = curr->lockdep_depth;
1002         struct held_lock *hlock;
1003
1004         /*
1005          * Debugging checks.
1006          *
1007          * Depth must not be zero for a non-head lock:
1008          */
1009         if (!depth)
1010                 goto out_bug;
1011         /*
1012          * At least two relevant locks must exist for this
1013          * to be a head:
1014          */
1015         if (curr->held_locks[depth].irq_context !=
1016                         curr->held_locks[depth-1].irq_context)
1017                 goto out_bug;
1018
1019         for (;;) {
1020                 hlock = curr->held_locks + depth-1;
1021                 /*
1022                  * Only non-recursive-read entries get new dependencies
1023                  * added:
1024                  */
1025                 if (hlock->read != 2) {
1026                         check_prev_add(curr, hlock, next);
1027                         /*
1028                          * Stop after the first non-trylock entry,
1029                          * as non-trylock entries have added their
1030                          * own direct dependencies already, so this
1031                          * lock is connected to them indirectly:
1032                          */
1033                         if (!hlock->trylock)
1034                                 break;
1035                 }
1036                 depth--;
1037                 /*
1038                  * End of lock-stack?
1039                  */
1040                 if (!depth)
1041                         break;
1042                 /*
1043                  * Stop the search if we cross into another context:
1044                  */
1045                 if (curr->held_locks[depth].irq_context !=
1046                                 curr->held_locks[depth-1].irq_context)
1047                         break;
1048         }
1049         return 1;
1050 out_bug:
1051         __raw_spin_unlock(&hash_lock);
1052         DEBUG_LOCKS_WARN_ON(1);
1053
1054         return 0;
1055 }
1056
1057
1058 /*
1059  * Is this the address of a static object:
1060  */
1061 static int static_obj(void *obj)
1062 {
1063         unsigned long start = (unsigned long) &_stext,
1064                       end   = (unsigned long) &_end,
1065                       addr  = (unsigned long) obj;
1066 #ifdef CONFIG_SMP
1067         int i;
1068 #endif
1069
1070         /*
1071          * static variable?
1072          */
1073         if ((addr >= start) && (addr < end))
1074                 return 1;
1075
1076 #ifdef CONFIG_SMP
1077         /*
1078          * percpu var?
1079          */
1080         for_each_possible_cpu(i) {
1081                 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
1082                 end   = (unsigned long) &__per_cpu_end   + per_cpu_offset(i);
1083
1084                 if ((addr >= start) && (addr < end))
1085                         return 1;
1086         }
1087 #endif
1088
1089         /*
1090          * module var?
1091          */
1092         return is_module_address(addr);
1093 }
1094
1095 /*
1096  * To make lock name printouts unique, we calculate a unique
1097  * class->name_version generation counter:
1098  */
1099 static int count_matching_names(struct lock_class *new_class)
1100 {
1101         struct lock_class *class;
1102         int count = 0;
1103
1104         if (!new_class->name)
1105                 return 0;
1106
1107         list_for_each_entry(class, &all_lock_classes, lock_entry) {
1108                 if (new_class->key - new_class->subclass == class->key)
1109                         return class->name_version;
1110                 if (class->name && !strcmp(class->name, new_class->name))
1111                         count = max(count, class->name_version);
1112         }
1113
1114         return count + 1;
1115 }
1116
1117 extern void __error_too_big_MAX_LOCKDEP_SUBCLASSES(void);
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         if (sizeof(struct lock_class_key) > sizeof(struct lock_class))
1157                 __error_too_big_MAX_LOCKDEP_SUBCLASSES();
1158
1159         key = lock->key->subkeys + subclass;
1160
1161         hash_head = classhashentry(key);
1162
1163         /*
1164          * We can walk the hash lockfree, because the hash only
1165          * grows, and we are careful when adding entries to the end:
1166          */
1167         list_for_each_entry(class, hash_head, hash_entry)
1168                 if (class->key == key)
1169                         return class;
1170
1171         return NULL;
1172 }
1173
1174 /*
1175  * Register a lock's class in the hash-table, if the class is not present
1176  * yet. Otherwise we look it up. We cache the result in the lock object
1177  * itself, so actual lookup of the hash should be once per lock object.
1178  */
1179 static inline struct lock_class *
1180 register_lock_class(struct lockdep_map *lock, unsigned int subclass)
1181 {
1182         struct lockdep_subclass_key *key;
1183         struct list_head *hash_head;
1184         struct lock_class *class;
1185
1186         class = look_up_lock_class(lock, subclass);
1187         if (likely(class))
1188                 return class;
1189
1190         /*
1191          * Debug-check: all keys must be persistent!
1192          */
1193         if (!static_obj(lock->key)) {
1194                 debug_locks_off();
1195                 printk("INFO: trying to register non-static key.\n");
1196                 printk("the code is fine but needs lockdep annotation.\n");
1197                 printk("turning off the locking correctness validator.\n");
1198                 dump_stack();
1199
1200                 return NULL;
1201         }
1202
1203         key = lock->key->subkeys + subclass;
1204         hash_head = classhashentry(key);
1205
1206         __raw_spin_lock(&hash_lock);
1207         /*
1208          * We have to do the hash-walk again, to avoid races
1209          * with another CPU:
1210          */
1211         list_for_each_entry(class, hash_head, hash_entry)
1212                 if (class->key == key)
1213                         goto out_unlock_set;
1214         /*
1215          * Allocate a new key from the static array, and add it to
1216          * the hash:
1217          */
1218         if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
1219                 __raw_spin_unlock(&hash_lock);
1220                 debug_locks_off();
1221                 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
1222                 printk("turning off the locking correctness validator.\n");
1223                 return NULL;
1224         }
1225         class = lock_classes + nr_lock_classes++;
1226         debug_atomic_inc(&nr_unused_locks);
1227         class->key = key;
1228         class->name = lock->name;
1229         class->subclass = subclass;
1230         INIT_LIST_HEAD(&class->lock_entry);
1231         INIT_LIST_HEAD(&class->locks_before);
1232         INIT_LIST_HEAD(&class->locks_after);
1233         class->name_version = count_matching_names(class);
1234         /*
1235          * We use RCU's safe list-add method to make
1236          * parallel walking of the hash-list safe:
1237          */
1238         list_add_tail_rcu(&class->hash_entry, hash_head);
1239
1240         if (verbose(class)) {
1241                 __raw_spin_unlock(&hash_lock);
1242                 printk("\nnew class %p: %s", class->key, class->name);
1243                 if (class->name_version > 1)
1244                         printk("#%d", class->name_version);
1245                 printk("\n");
1246                 dump_stack();
1247                 __raw_spin_lock(&hash_lock);
1248         }
1249 out_unlock_set:
1250         __raw_spin_unlock(&hash_lock);
1251
1252         if (!subclass)
1253                 lock->class_cache = class;
1254
1255         DEBUG_LOCKS_WARN_ON(class->subclass != subclass);
1256
1257         return class;
1258 }
1259
1260 /*
1261  * Look up a dependency chain. If the key is not present yet then
1262  * add it and return 0 - in this case the new dependency chain is
1263  * validated. If the key is already hashed, return 1.
1264  */
1265 static inline int lookup_chain_cache(u64 chain_key)
1266 {
1267         struct list_head *hash_head = chainhashentry(chain_key);
1268         struct lock_chain *chain;
1269
1270         DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1271         /*
1272          * We can walk it lock-free, because entries only get added
1273          * to the hash:
1274          */
1275         list_for_each_entry(chain, hash_head, entry) {
1276                 if (chain->chain_key == chain_key) {
1277 cache_hit:
1278                         debug_atomic_inc(&chain_lookup_hits);
1279                         /*
1280                          * In the debugging case, force redundant checking
1281                          * by returning 1:
1282                          */
1283 #ifdef CONFIG_DEBUG_LOCKDEP
1284                         __raw_spin_lock(&hash_lock);
1285                         return 1;
1286 #endif
1287                         return 0;
1288                 }
1289         }
1290         /*
1291          * Allocate a new chain entry from the static array, and add
1292          * it to the hash:
1293          */
1294         __raw_spin_lock(&hash_lock);
1295         /*
1296          * We have to walk the chain again locked - to avoid duplicates:
1297          */
1298         list_for_each_entry(chain, hash_head, entry) {
1299                 if (chain->chain_key == chain_key) {
1300                         __raw_spin_unlock(&hash_lock);
1301                         goto cache_hit;
1302                 }
1303         }
1304         if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1305                 __raw_spin_unlock(&hash_lock);
1306                 debug_locks_off();
1307                 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1308                 printk("turning off the locking correctness validator.\n");
1309                 return 0;
1310         }
1311         chain = lock_chains + nr_lock_chains++;
1312         chain->chain_key = chain_key;
1313         list_add_tail_rcu(&chain->entry, hash_head);
1314         debug_atomic_inc(&chain_lookup_misses);
1315 #ifdef CONFIG_TRACE_IRQFLAGS
1316         if (current->hardirq_context)
1317                 nr_hardirq_chains++;
1318         else {
1319                 if (current->softirq_context)
1320                         nr_softirq_chains++;
1321                 else
1322                         nr_process_chains++;
1323         }
1324 #else
1325         nr_process_chains++;
1326 #endif
1327
1328         return 1;
1329 }
1330
1331 /*
1332  * We are building curr_chain_key incrementally, so double-check
1333  * it from scratch, to make sure that it's done correctly:
1334  */
1335 static void check_chain_key(struct task_struct *curr)
1336 {
1337 #ifdef CONFIG_DEBUG_LOCKDEP
1338         struct held_lock *hlock, *prev_hlock = NULL;
1339         unsigned int i, id;
1340         u64 chain_key = 0;
1341
1342         for (i = 0; i < curr->lockdep_depth; i++) {
1343                 hlock = curr->held_locks + i;
1344                 if (chain_key != hlock->prev_chain_key) {
1345                         debug_locks_off();
1346                         printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1347                                 curr->lockdep_depth, i,
1348                                 (unsigned long long)chain_key,
1349                                 (unsigned long long)hlock->prev_chain_key);
1350                         WARN_ON(1);
1351                         return;
1352                 }
1353                 id = hlock->class - lock_classes;
1354                 DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS);
1355                 if (prev_hlock && (prev_hlock->irq_context !=
1356                                                         hlock->irq_context))
1357                         chain_key = 0;
1358                 chain_key = iterate_chain_key(chain_key, id);
1359                 prev_hlock = hlock;
1360         }
1361         if (chain_key != curr->curr_chain_key) {
1362                 debug_locks_off();
1363                 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1364                         curr->lockdep_depth, i,
1365                         (unsigned long long)chain_key,
1366                         (unsigned long long)curr->curr_chain_key);
1367                 WARN_ON(1);
1368         }
1369 #endif
1370 }
1371
1372 #ifdef CONFIG_TRACE_IRQFLAGS
1373
1374 /*
1375  * print irq inversion bug:
1376  */
1377 static int
1378 print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1379                         struct held_lock *this, int forwards,
1380                         const char *irqclass)
1381 {
1382         __raw_spin_unlock(&hash_lock);
1383         debug_locks_off();
1384         if (debug_locks_silent)
1385                 return 0;
1386
1387         printk("\n=========================================================\n");
1388         printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
1389         print_kernel_version();
1390         printk(  "---------------------------------------------------------\n");
1391         printk("%s/%d just changed the state of lock:\n",
1392                 curr->comm, curr->pid);
1393         print_lock(this);
1394         if (forwards)
1395                 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1396         else
1397                 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1398         print_lock_name(other);
1399         printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1400
1401         printk("\nother info that might help us debug this:\n");
1402         lockdep_print_held_locks(curr);
1403
1404         printk("\nthe first lock's dependencies:\n");
1405         print_lock_dependencies(this->class, 0);
1406
1407         printk("\nthe second lock's dependencies:\n");
1408         print_lock_dependencies(other, 0);
1409
1410         printk("\nstack backtrace:\n");
1411         dump_stack();
1412
1413         return 0;
1414 }
1415
1416 /*
1417  * Prove that in the forwards-direction subgraph starting at <this>
1418  * there is no lock matching <mask>:
1419  */
1420 static int
1421 check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1422                      enum lock_usage_bit bit, const char *irqclass)
1423 {
1424         int ret;
1425
1426         find_usage_bit = bit;
1427         /* fills in <forwards_match> */
1428         ret = find_usage_forwards(this->class, 0);
1429         if (!ret || ret == 1)
1430                 return ret;
1431
1432         return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1433 }
1434
1435 /*
1436  * Prove that in the backwards-direction subgraph starting at <this>
1437  * there is no lock matching <mask>:
1438  */
1439 static int
1440 check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1441                       enum lock_usage_bit bit, const char *irqclass)
1442 {
1443         int ret;
1444
1445         find_usage_bit = bit;
1446         /* fills in <backwards_match> */
1447         ret = find_usage_backwards(this->class, 0);
1448         if (!ret || ret == 1)
1449                 return ret;
1450
1451         return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1452 }
1453
1454 static inline void print_irqtrace_events(struct task_struct *curr)
1455 {
1456         printk("irq event stamp: %u\n", curr->irq_events);
1457         printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
1458         print_ip_sym(curr->hardirq_enable_ip);
1459         printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1460         print_ip_sym(curr->hardirq_disable_ip);
1461         printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
1462         print_ip_sym(curr->softirq_enable_ip);
1463         printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1464         print_ip_sym(curr->softirq_disable_ip);
1465 }
1466
1467 #else
1468 static inline void print_irqtrace_events(struct task_struct *curr)
1469 {
1470 }
1471 #endif
1472
1473 static int
1474 print_usage_bug(struct task_struct *curr, struct held_lock *this,
1475                 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1476 {
1477         __raw_spin_unlock(&hash_lock);
1478         debug_locks_off();
1479         if (debug_locks_silent)
1480                 return 0;
1481
1482         printk("\n=================================\n");
1483         printk(  "[ INFO: inconsistent lock state ]\n");
1484         print_kernel_version();
1485         printk(  "---------------------------------\n");
1486
1487         printk("inconsistent {%s} -> {%s} usage.\n",
1488                 usage_str[prev_bit], usage_str[new_bit]);
1489
1490         printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1491                 curr->comm, curr->pid,
1492                 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1493                 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1494                 trace_hardirqs_enabled(curr),
1495                 trace_softirqs_enabled(curr));
1496         print_lock(this);
1497
1498         printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1499         print_stack_trace(this->class->usage_traces + prev_bit, 1);
1500
1501         print_irqtrace_events(curr);
1502         printk("\nother info that might help us debug this:\n");
1503         lockdep_print_held_locks(curr);
1504
1505         printk("\nstack backtrace:\n");
1506         dump_stack();
1507
1508         return 0;
1509 }
1510
1511 /*
1512  * Print out an error if an invalid bit is set:
1513  */
1514 static inline int
1515 valid_state(struct task_struct *curr, struct held_lock *this,
1516             enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1517 {
1518         if (unlikely(this->class->usage_mask & (1 << bad_bit)))
1519                 return print_usage_bug(curr, this, bad_bit, new_bit);
1520         return 1;
1521 }
1522
1523 #define STRICT_READ_CHECKS      1
1524
1525 /*
1526  * Mark a lock with a usage bit, and validate the state transition:
1527  */
1528 static int mark_lock(struct task_struct *curr, struct held_lock *this,
1529                      enum lock_usage_bit new_bit, unsigned long ip)
1530 {
1531         unsigned int new_mask = 1 << new_bit, ret = 1;
1532
1533         /*
1534          * If already set then do not dirty the cacheline,
1535          * nor do any checks:
1536          */
1537         if (likely(this->class->usage_mask & new_mask))
1538                 return 1;
1539
1540         __raw_spin_lock(&hash_lock);
1541         /*
1542          * Make sure we didnt race:
1543          */
1544         if (unlikely(this->class->usage_mask & new_mask)) {
1545                 __raw_spin_unlock(&hash_lock);
1546                 return 1;
1547         }
1548
1549         this->class->usage_mask |= new_mask;
1550
1551 #ifdef CONFIG_TRACE_IRQFLAGS
1552         if (new_bit == LOCK_ENABLED_HARDIRQS ||
1553                         new_bit == LOCK_ENABLED_HARDIRQS_READ)
1554                 ip = curr->hardirq_enable_ip;
1555         else if (new_bit == LOCK_ENABLED_SOFTIRQS ||
1556                         new_bit == LOCK_ENABLED_SOFTIRQS_READ)
1557                 ip = curr->softirq_enable_ip;
1558 #endif
1559         if (!save_trace(this->class->usage_traces + new_bit))
1560                 return 0;
1561
1562         switch (new_bit) {
1563 #ifdef CONFIG_TRACE_IRQFLAGS
1564         case LOCK_USED_IN_HARDIRQ:
1565                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1566                         return 0;
1567                 if (!valid_state(curr, this, new_bit,
1568                                  LOCK_ENABLED_HARDIRQS_READ))
1569                         return 0;
1570                 /*
1571                  * just marked it hardirq-safe, check that this lock
1572                  * took no hardirq-unsafe lock in the past:
1573                  */
1574                 if (!check_usage_forwards(curr, this,
1575                                           LOCK_ENABLED_HARDIRQS, "hard"))
1576                         return 0;
1577 #if STRICT_READ_CHECKS
1578                 /*
1579                  * just marked it hardirq-safe, check that this lock
1580                  * took no hardirq-unsafe-read lock in the past:
1581                  */
1582                 if (!check_usage_forwards(curr, this,
1583                                 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1584                         return 0;
1585 #endif
1586                 if (hardirq_verbose(this->class))
1587                         ret = 2;
1588                 break;
1589         case LOCK_USED_IN_SOFTIRQ:
1590                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1591                         return 0;
1592                 if (!valid_state(curr, this, new_bit,
1593                                  LOCK_ENABLED_SOFTIRQS_READ))
1594                         return 0;
1595                 /*
1596                  * just marked it softirq-safe, check that this lock
1597                  * took no softirq-unsafe lock in the past:
1598                  */
1599                 if (!check_usage_forwards(curr, this,
1600                                           LOCK_ENABLED_SOFTIRQS, "soft"))
1601                         return 0;
1602 #if STRICT_READ_CHECKS
1603                 /*
1604                  * just marked it softirq-safe, check that this lock
1605                  * took no softirq-unsafe-read lock in the past:
1606                  */
1607                 if (!check_usage_forwards(curr, this,
1608                                 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
1609                         return 0;
1610 #endif
1611                 if (softirq_verbose(this->class))
1612                         ret = 2;
1613                 break;
1614         case LOCK_USED_IN_HARDIRQ_READ:
1615                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1616                         return 0;
1617                 /*
1618                  * just marked it hardirq-read-safe, check that this lock
1619                  * took no hardirq-unsafe lock in the past:
1620                  */
1621                 if (!check_usage_forwards(curr, this,
1622                                           LOCK_ENABLED_HARDIRQS, "hard"))
1623                         return 0;
1624                 if (hardirq_verbose(this->class))
1625                         ret = 2;
1626                 break;
1627         case LOCK_USED_IN_SOFTIRQ_READ:
1628                 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1629                         return 0;
1630                 /*
1631                  * just marked it softirq-read-safe, check that this lock
1632                  * took no softirq-unsafe lock in the past:
1633                  */
1634                 if (!check_usage_forwards(curr, this,
1635                                           LOCK_ENABLED_SOFTIRQS, "soft"))
1636                         return 0;
1637                 if (softirq_verbose(this->class))
1638                         ret = 2;
1639                 break;
1640         case LOCK_ENABLED_HARDIRQS:
1641                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1642                         return 0;
1643                 if (!valid_state(curr, this, new_bit,
1644                                  LOCK_USED_IN_HARDIRQ_READ))
1645                         return 0;
1646                 /*
1647                  * just marked it hardirq-unsafe, check that no hardirq-safe
1648                  * lock in the system ever took it in the past:
1649                  */
1650                 if (!check_usage_backwards(curr, this,
1651                                            LOCK_USED_IN_HARDIRQ, "hard"))
1652                         return 0;
1653 #if STRICT_READ_CHECKS
1654                 /*
1655                  * just marked it hardirq-unsafe, check that no
1656                  * hardirq-safe-read lock in the system ever took
1657                  * it in the past:
1658                  */
1659                 if (!check_usage_backwards(curr, this,
1660                                    LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
1661                         return 0;
1662 #endif
1663                 if (hardirq_verbose(this->class))
1664                         ret = 2;
1665                 break;
1666         case LOCK_ENABLED_SOFTIRQS:
1667                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1668                         return 0;
1669                 if (!valid_state(curr, this, new_bit,
1670                                  LOCK_USED_IN_SOFTIRQ_READ))
1671                         return 0;
1672                 /*
1673                  * just marked it softirq-unsafe, check that no softirq-safe
1674                  * lock in the system ever took it in the past:
1675                  */
1676                 if (!check_usage_backwards(curr, this,
1677                                            LOCK_USED_IN_SOFTIRQ, "soft"))
1678                         return 0;
1679 #if STRICT_READ_CHECKS
1680                 /*
1681                  * just marked it softirq-unsafe, check that no
1682                  * softirq-safe-read lock in the system ever took
1683                  * it in the past:
1684                  */
1685                 if (!check_usage_backwards(curr, this,
1686                                    LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
1687                         return 0;
1688 #endif
1689                 if (softirq_verbose(this->class))
1690                         ret = 2;
1691                 break;
1692         case LOCK_ENABLED_HARDIRQS_READ:
1693                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1694                         return 0;
1695 #if STRICT_READ_CHECKS
1696                 /*
1697                  * just marked it hardirq-read-unsafe, check that no
1698                  * hardirq-safe lock in the system ever took it in the past:
1699                  */
1700                 if (!check_usage_backwards(curr, this,
1701                                            LOCK_USED_IN_HARDIRQ, "hard"))
1702                         return 0;
1703 #endif
1704                 if (hardirq_verbose(this->class))
1705                         ret = 2;
1706                 break;
1707         case LOCK_ENABLED_SOFTIRQS_READ:
1708                 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1709                         return 0;
1710 #if STRICT_READ_CHECKS
1711                 /*
1712                  * just marked it softirq-read-unsafe, check that no
1713                  * softirq-safe lock in the system ever took it in the past:
1714                  */
1715                 if (!check_usage_backwards(curr, this,
1716                                            LOCK_USED_IN_SOFTIRQ, "soft"))
1717                         return 0;
1718 #endif
1719                 if (softirq_verbose(this->class))
1720                         ret = 2;
1721                 break;
1722 #endif
1723         case LOCK_USED:
1724                 /*
1725                  * Add it to the global list of classes:
1726                  */
1727                 list_add_tail_rcu(&this->class->lock_entry, &all_lock_classes);
1728                 debug_atomic_dec(&nr_unused_locks);
1729                 break;
1730         default:
1731                 debug_locks_off();
1732                 WARN_ON(1);
1733                 return 0;
1734         }
1735
1736         __raw_spin_unlock(&hash_lock);
1737
1738         /*
1739          * We must printk outside of the hash_lock:
1740          */
1741         if (ret == 2) {
1742                 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
1743                 print_lock(this);
1744                 print_irqtrace_events(curr);
1745                 dump_stack();
1746         }
1747
1748         return ret;
1749 }
1750
1751 #ifdef CONFIG_TRACE_IRQFLAGS
1752 /*
1753  * Mark all held locks with a usage bit:
1754  */
1755 static int
1756 mark_held_locks(struct task_struct *curr, int hardirq, unsigned long ip)
1757 {
1758         enum lock_usage_bit usage_bit;
1759         struct held_lock *hlock;
1760         int i;
1761
1762         for (i = 0; i < curr->lockdep_depth; i++) {
1763                 hlock = curr->held_locks + i;
1764
1765                 if (hardirq) {
1766                         if (hlock->read)
1767                                 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
1768                         else
1769                                 usage_bit = LOCK_ENABLED_HARDIRQS;
1770                 } else {
1771                         if (hlock->read)
1772                                 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
1773                         else
1774                                 usage_bit = LOCK_ENABLED_SOFTIRQS;
1775                 }
1776                 if (!mark_lock(curr, hlock, usage_bit, ip))
1777                         return 0;
1778         }
1779
1780         return 1;
1781 }
1782
1783 /*
1784  * Debugging helper: via this flag we know that we are in
1785  * 'early bootup code', and will warn about any invalid irqs-on event:
1786  */
1787 static int early_boot_irqs_enabled;
1788
1789 void early_boot_irqs_off(void)
1790 {
1791         early_boot_irqs_enabled = 0;
1792 }
1793
1794 void early_boot_irqs_on(void)
1795 {
1796         early_boot_irqs_enabled = 1;
1797 }
1798
1799 /*
1800  * Hardirqs will be enabled:
1801  */
1802 void trace_hardirqs_on(void)
1803 {
1804         struct task_struct *curr = current;
1805         unsigned long ip;
1806
1807         if (unlikely(!debug_locks || current->lockdep_recursion))
1808                 return;
1809
1810         if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
1811                 return;
1812
1813         if (unlikely(curr->hardirqs_enabled)) {
1814                 debug_atomic_inc(&redundant_hardirqs_on);
1815                 return;
1816         }
1817         /* we'll do an OFF -> ON transition: */
1818         curr->hardirqs_enabled = 1;
1819         ip = (unsigned long) __builtin_return_address(0);
1820
1821         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1822                 return;
1823         if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
1824                 return;
1825         /*
1826          * We are going to turn hardirqs on, so set the
1827          * usage bit for all held locks:
1828          */
1829         if (!mark_held_locks(curr, 1, ip))
1830                 return;
1831         /*
1832          * If we have softirqs enabled, then set the usage
1833          * bit for all held locks. (disabled hardirqs prevented
1834          * this bit from being set before)
1835          */
1836         if (curr->softirqs_enabled)
1837                 if (!mark_held_locks(curr, 0, ip))
1838                         return;
1839
1840         curr->hardirq_enable_ip = ip;
1841         curr->hardirq_enable_event = ++curr->irq_events;
1842         debug_atomic_inc(&hardirqs_on_events);
1843 }
1844
1845 EXPORT_SYMBOL(trace_hardirqs_on);
1846
1847 /*
1848  * Hardirqs were disabled:
1849  */
1850 void trace_hardirqs_off(void)
1851 {
1852         struct task_struct *curr = current;
1853
1854         if (unlikely(!debug_locks || current->lockdep_recursion))
1855                 return;
1856
1857         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1858                 return;
1859
1860         if (curr->hardirqs_enabled) {
1861                 /*
1862                  * We have done an ON -> OFF transition:
1863                  */
1864                 curr->hardirqs_enabled = 0;
1865                 curr->hardirq_disable_ip = _RET_IP_;
1866                 curr->hardirq_disable_event = ++curr->irq_events;
1867                 debug_atomic_inc(&hardirqs_off_events);
1868         } else
1869                 debug_atomic_inc(&redundant_hardirqs_off);
1870 }
1871
1872 EXPORT_SYMBOL(trace_hardirqs_off);
1873
1874 /*
1875  * Softirqs will be enabled:
1876  */
1877 void trace_softirqs_on(unsigned long ip)
1878 {
1879         struct task_struct *curr = current;
1880
1881         if (unlikely(!debug_locks))
1882                 return;
1883
1884         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1885                 return;
1886
1887         if (curr->softirqs_enabled) {
1888                 debug_atomic_inc(&redundant_softirqs_on);
1889                 return;
1890         }
1891
1892         /*
1893          * We'll do an OFF -> ON transition:
1894          */
1895         curr->softirqs_enabled = 1;
1896         curr->softirq_enable_ip = ip;
1897         curr->softirq_enable_event = ++curr->irq_events;
1898         debug_atomic_inc(&softirqs_on_events);
1899         /*
1900          * We are going to turn softirqs on, so set the
1901          * usage bit for all held locks, if hardirqs are
1902          * enabled too:
1903          */
1904         if (curr->hardirqs_enabled)
1905                 mark_held_locks(curr, 0, ip);
1906 }
1907
1908 /*
1909  * Softirqs were disabled:
1910  */
1911 void trace_softirqs_off(unsigned long ip)
1912 {
1913         struct task_struct *curr = current;
1914
1915         if (unlikely(!debug_locks))
1916                 return;
1917
1918         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1919                 return;
1920
1921         if (curr->softirqs_enabled) {
1922                 /*
1923                  * We have done an ON -> OFF transition:
1924                  */
1925                 curr->softirqs_enabled = 0;
1926                 curr->softirq_disable_ip = ip;
1927                 curr->softirq_disable_event = ++curr->irq_events;
1928                 debug_atomic_inc(&softirqs_off_events);
1929                 DEBUG_LOCKS_WARN_ON(!softirq_count());
1930         } else
1931                 debug_atomic_inc(&redundant_softirqs_off);
1932 }
1933
1934 #endif
1935
1936 /*
1937  * Initialize a lock instance's lock-class mapping info:
1938  */
1939 void lockdep_init_map(struct lockdep_map *lock, const char *name,
1940                       struct lock_class_key *key)
1941 {
1942         if (unlikely(!debug_locks))
1943                 return;
1944
1945         if (DEBUG_LOCKS_WARN_ON(!key))
1946                 return;
1947         if (DEBUG_LOCKS_WARN_ON(!name))
1948                 return;
1949         /*
1950          * Sanity check, the lock-class key must be persistent:
1951          */
1952         if (!static_obj(key)) {
1953                 printk("BUG: key %p not in .data!\n", key);
1954                 DEBUG_LOCKS_WARN_ON(1);
1955                 return;
1956         }
1957         lock->name = name;
1958         lock->key = key;
1959         lock->class_cache = NULL;
1960 }
1961
1962 EXPORT_SYMBOL_GPL(lockdep_init_map);
1963
1964 /*
1965  * This gets called for every mutex_lock*()/spin_lock*() operation.
1966  * We maintain the dependency maps and validate the locking attempt:
1967  */
1968 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
1969                           int trylock, int read, int check, int hardirqs_off,
1970                           unsigned long ip)
1971 {
1972         struct task_struct *curr = current;
1973         struct lock_class *class = NULL;
1974         struct held_lock *hlock;
1975         unsigned int depth, id;
1976         int chain_head = 0;
1977         u64 chain_key;
1978
1979         if (unlikely(!debug_locks))
1980                 return 0;
1981
1982         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1983                 return 0;
1984
1985         if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
1986                 debug_locks_off();
1987                 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
1988                 printk("turning off the locking correctness validator.\n");
1989                 return 0;
1990         }
1991
1992         if (!subclass)
1993                 class = lock->class_cache;
1994         /*
1995          * Not cached yet or subclass?
1996          */
1997         if (unlikely(!class)) {
1998                 class = register_lock_class(lock, subclass);
1999                 if (!class)
2000                         return 0;
2001         }
2002         debug_atomic_inc((atomic_t *)&class->ops);
2003         if (very_verbose(class)) {
2004                 printk("\nacquire class [%p] %s", class->key, class->name);
2005                 if (class->name_version > 1)
2006                         printk("#%d", class->name_version);
2007                 printk("\n");
2008                 dump_stack();
2009         }
2010
2011         /*
2012          * Add the lock to the list of currently held locks.
2013          * (we dont increase the depth just yet, up until the
2014          * dependency checks are done)
2015          */
2016         depth = curr->lockdep_depth;
2017         if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2018                 return 0;
2019
2020         hlock = curr->held_locks + depth;
2021
2022         hlock->class = class;
2023         hlock->acquire_ip = ip;
2024         hlock->instance = lock;
2025         hlock->trylock = trylock;
2026         hlock->read = read;
2027         hlock->check = check;
2028         hlock->hardirqs_off = hardirqs_off;
2029
2030         if (check != 2)
2031                 goto out_calc_hash;
2032 #ifdef CONFIG_TRACE_IRQFLAGS
2033         /*
2034          * If non-trylock use in a hardirq or softirq context, then
2035          * mark the lock as used in these contexts:
2036          */
2037         if (!trylock) {
2038                 if (read) {
2039                         if (curr->hardirq_context)
2040                                 if (!mark_lock(curr, hlock,
2041                                                 LOCK_USED_IN_HARDIRQ_READ, ip))
2042                                         return 0;
2043                         if (curr->softirq_context)
2044                                 if (!mark_lock(curr, hlock,
2045                                                 LOCK_USED_IN_SOFTIRQ_READ, ip))
2046                                         return 0;
2047                 } else {
2048                         if (curr->hardirq_context)
2049                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ, ip))
2050                                         return 0;
2051                         if (curr->softirq_context)
2052                                 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ, ip))
2053                                         return 0;
2054                 }
2055         }
2056         if (!hardirqs_off) {
2057                 if (read) {
2058                         if (!mark_lock(curr, hlock,
2059                                         LOCK_ENABLED_HARDIRQS_READ, ip))
2060                                 return 0;
2061                         if (curr->softirqs_enabled)
2062                                 if (!mark_lock(curr, hlock,
2063                                                 LOCK_ENABLED_SOFTIRQS_READ, ip))
2064                                         return 0;
2065                 } else {
2066                         if (!mark_lock(curr, hlock,
2067                                         LOCK_ENABLED_HARDIRQS, ip))
2068                                 return 0;
2069                         if (curr->softirqs_enabled)
2070                                 if (!mark_lock(curr, hlock,
2071                                                 LOCK_ENABLED_SOFTIRQS, ip))
2072                                         return 0;
2073                 }
2074         }
2075 #endif
2076         /* mark it as used: */
2077         if (!mark_lock(curr, hlock, LOCK_USED, ip))
2078                 return 0;
2079 out_calc_hash:
2080         /*
2081          * Calculate the chain hash: it's the combined has of all the
2082          * lock keys along the dependency chain. We save the hash value
2083          * at every step so that we can get the current hash easily
2084          * after unlock. The chain hash is then used to cache dependency
2085          * results.
2086          *
2087          * The 'key ID' is what is the most compact key value to drive
2088          * the hash, not class->key.
2089          */
2090         id = class - lock_classes;
2091         if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2092                 return 0;
2093
2094         chain_key = curr->curr_chain_key;
2095         if (!depth) {
2096                 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2097                         return 0;
2098                 chain_head = 1;
2099         }
2100
2101         hlock->prev_chain_key = chain_key;
2102
2103 #ifdef CONFIG_TRACE_IRQFLAGS
2104         /*
2105          * Keep track of points where we cross into an interrupt context:
2106          */
2107         hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2108                                 curr->softirq_context;
2109         if (depth) {
2110                 struct held_lock *prev_hlock;
2111
2112                 prev_hlock = curr->held_locks + depth-1;
2113                 /*
2114                  * If we cross into another context, reset the
2115                  * hash key (this also prevents the checking and the
2116                  * adding of the dependency to 'prev'):
2117                  */
2118                 if (prev_hlock->irq_context != hlock->irq_context) {
2119                         chain_key = 0;
2120                         chain_head = 1;
2121                 }
2122         }
2123 #endif
2124         chain_key = iterate_chain_key(chain_key, id);
2125         curr->curr_chain_key = chain_key;
2126
2127         /*
2128          * Trylock needs to maintain the stack of held locks, but it
2129          * does not add new dependencies, because trylock can be done
2130          * in any order.
2131          *
2132          * We look up the chain_key and do the O(N^2) check and update of
2133          * the dependencies only if this is a new dependency chain.
2134          * (If lookup_chain_cache() returns with 1 it acquires
2135          * hash_lock for us)
2136          */
2137         if (!trylock && (check == 2) && lookup_chain_cache(chain_key)) {
2138                 /*
2139                  * Check whether last held lock:
2140                  *
2141                  * - is irq-safe, if this lock is irq-unsafe
2142                  * - is softirq-safe, if this lock is hardirq-unsafe
2143                  *
2144                  * And check whether the new lock's dependency graph
2145                  * could lead back to the previous lock.
2146                  *
2147                  * any of these scenarios could lead to a deadlock. If
2148                  * All validations
2149                  */
2150                 int ret = check_deadlock(curr, hlock, lock, read);
2151
2152                 if (!ret)
2153                         return 0;
2154                 /*
2155                  * Mark recursive read, as we jump over it when
2156                  * building dependencies (just like we jump over
2157                  * trylock entries):
2158                  */
2159                 if (ret == 2)
2160                         hlock->read = 2;
2161                 /*
2162                  * Add dependency only if this lock is not the head
2163                  * of the chain, and if it's not a secondary read-lock:
2164                  */
2165                 if (!chain_head && ret != 2)
2166                         if (!check_prevs_add(curr, hlock))
2167                                 return 0;
2168                 __raw_spin_unlock(&hash_lock);
2169         }
2170         curr->lockdep_depth++;
2171         check_chain_key(curr);
2172         if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2173                 debug_locks_off();
2174                 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2175                 printk("turning off the locking correctness validator.\n");
2176                 return 0;
2177         }
2178         if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2179                 max_lockdep_depth = curr->lockdep_depth;
2180
2181         return 1;
2182 }
2183
2184 static int
2185 print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2186                            unsigned long ip)
2187 {
2188         if (!debug_locks_off())
2189                 return 0;
2190         if (debug_locks_silent)
2191                 return 0;
2192
2193         printk("\n=====================================\n");
2194         printk(  "[ BUG: bad unlock balance detected! ]\n");
2195         printk(  "-------------------------------------\n");
2196         printk("%s/%d is trying to release lock (",
2197                 curr->comm, curr->pid);
2198         print_lockdep_cache(lock);
2199         printk(") at:\n");
2200         print_ip_sym(ip);
2201         printk("but there are no more locks to release!\n");
2202         printk("\nother info that might help us debug this:\n");
2203         lockdep_print_held_locks(curr);
2204
2205         printk("\nstack backtrace:\n");
2206         dump_stack();
2207
2208         return 0;
2209 }
2210
2211 /*
2212  * Common debugging checks for both nested and non-nested unlock:
2213  */
2214 static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2215                         unsigned long ip)
2216 {
2217         if (unlikely(!debug_locks))
2218                 return 0;
2219         if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2220                 return 0;
2221
2222         if (curr->lockdep_depth <= 0)
2223                 return print_unlock_inbalance_bug(curr, lock, ip);
2224
2225         return 1;
2226 }
2227
2228 /*
2229  * Remove the lock to the list of currently held locks in a
2230  * potentially non-nested (out of order) manner. This is a
2231  * relatively rare operation, as all the unlock APIs default
2232  * to nested mode (which uses lock_release()):
2233  */
2234 static int
2235 lock_release_non_nested(struct task_struct *curr,
2236                         struct lockdep_map *lock, unsigned long ip)
2237 {
2238         struct held_lock *hlock, *prev_hlock;
2239         unsigned int depth;
2240         int i;
2241
2242         /*
2243          * Check whether the lock exists in the current stack
2244          * of held locks:
2245          */
2246         depth = curr->lockdep_depth;
2247         if (DEBUG_LOCKS_WARN_ON(!depth))
2248                 return 0;
2249
2250         prev_hlock = NULL;
2251         for (i = depth-1; i >= 0; i--) {
2252                 hlock = curr->held_locks + i;
2253                 /*
2254                  * We must not cross into another context:
2255                  */
2256                 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2257                         break;
2258                 if (hlock->instance == lock)
2259                         goto found_it;
2260                 prev_hlock = hlock;
2261         }
2262         return print_unlock_inbalance_bug(curr, lock, ip);
2263
2264 found_it:
2265         /*
2266          * We have the right lock to unlock, 'hlock' points to it.
2267          * Now we remove it from the stack, and add back the other
2268          * entries (if any), recalculating the hash along the way:
2269          */
2270         curr->lockdep_depth = i;
2271         curr->curr_chain_key = hlock->prev_chain_key;
2272
2273         for (i++; i < depth; i++) {
2274                 hlock = curr->held_locks + i;
2275                 if (!__lock_acquire(hlock->instance,
2276                         hlock->class->subclass, hlock->trylock,
2277                                 hlock->read, hlock->check, hlock->hardirqs_off,
2278                                 hlock->acquire_ip))
2279                         return 0;
2280         }
2281
2282         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2283                 return 0;
2284         return 1;
2285 }
2286
2287 /*
2288  * Remove the lock to the list of currently held locks - this gets
2289  * called on mutex_unlock()/spin_unlock*() (or on a failed
2290  * mutex_lock_interruptible()). This is done for unlocks that nest
2291  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2292  */
2293 static int lock_release_nested(struct task_struct *curr,
2294                                struct lockdep_map *lock, unsigned long ip)
2295 {
2296         struct held_lock *hlock;
2297         unsigned int depth;
2298
2299         /*
2300          * Pop off the top of the lock stack:
2301          */
2302         depth = curr->lockdep_depth - 1;
2303         hlock = curr->held_locks + depth;
2304
2305         /*
2306          * Is the unlock non-nested:
2307          */
2308         if (hlock->instance != lock)
2309                 return lock_release_non_nested(curr, lock, ip);
2310         curr->lockdep_depth--;
2311
2312         if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2313                 return 0;
2314
2315         curr->curr_chain_key = hlock->prev_chain_key;
2316
2317 #ifdef CONFIG_DEBUG_LOCKDEP
2318         hlock->prev_chain_key = 0;
2319         hlock->class = NULL;
2320         hlock->acquire_ip = 0;
2321         hlock->irq_context = 0;
2322 #endif
2323         return 1;
2324 }
2325
2326 /*
2327  * Remove the lock to the list of currently held locks - this gets
2328  * called on mutex_unlock()/spin_unlock*() (or on a failed
2329  * mutex_lock_interruptible()). This is done for unlocks that nest
2330  * perfectly. (i.e. the current top of the lock-stack is unlocked)
2331  */
2332 static void
2333 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2334 {
2335         struct task_struct *curr = current;
2336
2337         if (!check_unlock(curr, lock, ip))
2338                 return;
2339
2340         if (nested) {
2341                 if (!lock_release_nested(curr, lock, ip))
2342                         return;
2343         } else {
2344                 if (!lock_release_non_nested(curr, lock, ip))
2345                         return;
2346         }
2347
2348         check_chain_key(curr);
2349 }
2350
2351 /*
2352  * Check whether we follow the irq-flags state precisely:
2353  */
2354 static void check_flags(unsigned long flags)
2355 {
2356 #if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2357         if (!debug_locks)
2358                 return;
2359
2360         if (irqs_disabled_flags(flags))
2361                 DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled);
2362         else
2363                 DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled);
2364
2365         /*
2366          * We dont accurately track softirq state in e.g.
2367          * hardirq contexts (such as on 4KSTACKS), so only
2368          * check if not in hardirq contexts:
2369          */
2370         if (!hardirq_count()) {
2371                 if (softirq_count())
2372                         DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2373                 else
2374                         DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2375         }
2376
2377         if (!debug_locks)
2378                 print_irqtrace_events(current);
2379 #endif
2380 }
2381
2382 /*
2383  * We are not always called with irqs disabled - do that here,
2384  * and also avoid lockdep recursion:
2385  */
2386 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2387                   int trylock, int read, int check, unsigned long ip)
2388 {
2389         unsigned long flags;
2390
2391         if (unlikely(current->lockdep_recursion))
2392                 return;
2393
2394         raw_local_irq_save(flags);
2395         check_flags(flags);
2396
2397         current->lockdep_recursion = 1;
2398         __lock_acquire(lock, subclass, trylock, read, check,
2399                        irqs_disabled_flags(flags), ip);
2400         current->lockdep_recursion = 0;
2401         raw_local_irq_restore(flags);
2402 }
2403
2404 EXPORT_SYMBOL_GPL(lock_acquire);
2405
2406 void lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2407 {
2408         unsigned long flags;
2409
2410         if (unlikely(current->lockdep_recursion))
2411                 return;
2412
2413         raw_local_irq_save(flags);
2414         check_flags(flags);
2415         current->lockdep_recursion = 1;
2416         __lock_release(lock, nested, ip);
2417         current->lockdep_recursion = 0;
2418         raw_local_irq_restore(flags);
2419 }
2420
2421 EXPORT_SYMBOL_GPL(lock_release);
2422
2423 /*
2424  * Used by the testsuite, sanitize the validator state
2425  * after a simulated failure:
2426  */
2427
2428 void lockdep_reset(void)
2429 {
2430         unsigned long flags;
2431
2432         raw_local_irq_save(flags);
2433         current->curr_chain_key = 0;
2434         current->lockdep_depth = 0;
2435         current->lockdep_recursion = 0;
2436         memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
2437         nr_hardirq_chains = 0;
2438         nr_softirq_chains = 0;
2439         nr_process_chains = 0;
2440         debug_locks = 1;
2441         raw_local_irq_restore(flags);
2442 }
2443
2444 static void zap_class(struct lock_class *class)
2445 {
2446         int i;
2447
2448         /*
2449          * Remove all dependencies this lock is
2450          * involved in:
2451          */
2452         for (i = 0; i < nr_list_entries; i++) {
2453                 if (list_entries[i].class == class)
2454                         list_del_rcu(&list_entries[i].entry);
2455         }
2456         /*
2457          * Unhash the class and remove it from the all_lock_classes list:
2458          */
2459         list_del_rcu(&class->hash_entry);
2460         list_del_rcu(&class->lock_entry);
2461
2462 }
2463
2464 static inline int within(void *addr, void *start, unsigned long size)
2465 {
2466         return addr >= start && addr < start + size;
2467 }
2468
2469 void lockdep_free_key_range(void *start, unsigned long size)
2470 {
2471         struct lock_class *class, *next;
2472         struct list_head *head;
2473         unsigned long flags;
2474         int i;
2475
2476         raw_local_irq_save(flags);
2477         __raw_spin_lock(&hash_lock);
2478
2479         /*
2480          * Unhash all classes that were created by this module:
2481          */
2482         for (i = 0; i < CLASSHASH_SIZE; i++) {
2483                 head = classhash_table + i;
2484                 if (list_empty(head))
2485                         continue;
2486                 list_for_each_entry_safe(class, next, head, hash_entry)
2487                         if (within(class->key, start, size))
2488                                 zap_class(class);
2489         }
2490
2491         __raw_spin_unlock(&hash_lock);
2492         raw_local_irq_restore(flags);
2493 }
2494
2495 void lockdep_reset_lock(struct lockdep_map *lock)
2496 {
2497         struct lock_class *class, *next;
2498         struct list_head *head;
2499         unsigned long flags;
2500         int i, j;
2501
2502         raw_local_irq_save(flags);
2503
2504         /*
2505          * Remove all classes this lock might have:
2506          */
2507         for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
2508                 /*
2509                  * If the class exists we look it up and zap it:
2510                  */
2511                 class = look_up_lock_class(lock, j);
2512                 if (class)
2513                         zap_class(class);
2514         }
2515         /*
2516          * Debug check: in the end all mapped classes should
2517          * be gone.
2518          */
2519         __raw_spin_lock(&hash_lock);
2520         for (i = 0; i < CLASSHASH_SIZE; i++) {
2521                 head = classhash_table + i;
2522                 if (list_empty(head))
2523                         continue;
2524                 list_for_each_entry_safe(class, next, head, hash_entry) {
2525                         if (unlikely(class == lock->class_cache)) {
2526                                 __raw_spin_unlock(&hash_lock);
2527                                 DEBUG_LOCKS_WARN_ON(1);
2528                                 goto out_restore;
2529                         }
2530                 }
2531         }
2532         __raw_spin_unlock(&hash_lock);
2533
2534 out_restore:
2535         raw_local_irq_restore(flags);
2536 }
2537
2538 void __init lockdep_init(void)
2539 {
2540         int i;
2541
2542         /*
2543          * Some architectures have their own start_kernel()
2544          * code which calls lockdep_init(), while we also
2545          * call lockdep_init() from the start_kernel() itself,
2546          * and we want to initialize the hashes only once:
2547          */
2548         if (lockdep_initialized)
2549                 return;
2550
2551         for (i = 0; i < CLASSHASH_SIZE; i++)
2552                 INIT_LIST_HEAD(classhash_table + i);
2553
2554         for (i = 0; i < CHAINHASH_SIZE; i++)
2555                 INIT_LIST_HEAD(chainhash_table + i);
2556
2557         lockdep_initialized = 1;
2558 }
2559
2560 void __init lockdep_info(void)
2561 {
2562         printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
2563
2564         printk("... MAX_LOCKDEP_SUBCLASSES:    %lu\n", MAX_LOCKDEP_SUBCLASSES);
2565         printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
2566         printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
2567         printk("... CLASSHASH_SIZE:           %lu\n", CLASSHASH_SIZE);
2568         printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
2569         printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
2570         printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
2571
2572         printk(" memory used by lock dependency info: %lu kB\n",
2573                 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
2574                 sizeof(struct list_head) * CLASSHASH_SIZE +
2575                 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
2576                 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
2577                 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
2578
2579         printk(" per task-struct memory footprint: %lu bytes\n",
2580                 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
2581
2582 #ifdef CONFIG_DEBUG_LOCKDEP
2583         if (lockdep_init_error)
2584                 printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n");
2585 #endif
2586 }
2587
2588 static inline int in_range(const void *start, const void *addr, const void *end)
2589 {
2590         return addr >= start && addr <= end;
2591 }
2592
2593 static void
2594 print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
2595                      const void *mem_to, struct held_lock *hlock)
2596 {
2597         if (!debug_locks_off())
2598                 return;
2599         if (debug_locks_silent)
2600                 return;
2601
2602         printk("\n=========================\n");
2603         printk(  "[ BUG: held lock freed! ]\n");
2604         printk(  "-------------------------\n");
2605         printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
2606                 curr->comm, curr->pid, mem_from, mem_to-1);
2607         print_lock(hlock);
2608         lockdep_print_held_locks(curr);
2609
2610         printk("\nstack backtrace:\n");
2611         dump_stack();
2612 }
2613
2614 /*
2615  * Called when kernel memory is freed (or unmapped), or if a lock
2616  * is destroyed or reinitialized - this code checks whether there is
2617  * any held lock in the memory range of <from> to <to>:
2618  */
2619 void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
2620 {
2621         const void *mem_to = mem_from + mem_len, *lock_from, *lock_to;
2622         struct task_struct *curr = current;
2623         struct held_lock *hlock;
2624         unsigned long flags;
2625         int i;
2626
2627         if (unlikely(!debug_locks))
2628                 return;
2629
2630         local_irq_save(flags);
2631         for (i = 0; i < curr->lockdep_depth; i++) {
2632                 hlock = curr->held_locks + i;
2633
2634                 lock_from = (void *)hlock->instance;
2635                 lock_to = (void *)(hlock->instance + 1);
2636
2637                 if (!in_range(mem_from, lock_from, mem_to) &&
2638                                         !in_range(mem_from, lock_to, mem_to))
2639                         continue;
2640
2641                 print_freed_lock_bug(curr, mem_from, mem_to, hlock);
2642                 break;
2643         }
2644         local_irq_restore(flags);
2645 }
2646
2647 static void print_held_locks_bug(struct task_struct *curr)
2648 {
2649         if (!debug_locks_off())
2650                 return;
2651         if (debug_locks_silent)
2652                 return;
2653
2654         printk("\n=====================================\n");
2655         printk(  "[ BUG: lock held at task exit time! ]\n");
2656         printk(  "-------------------------------------\n");
2657         printk("%s/%d is exiting with locks still held!\n",
2658                 curr->comm, curr->pid);
2659         lockdep_print_held_locks(curr);
2660
2661         printk("\nstack backtrace:\n");
2662         dump_stack();
2663 }
2664
2665 void debug_check_no_locks_held(struct task_struct *task)
2666 {
2667         if (unlikely(task->lockdep_depth > 0))
2668                 print_held_locks_bug(task);
2669 }
2670
2671 void debug_show_all_locks(void)
2672 {
2673         struct task_struct *g, *p;
2674         int count = 10;
2675         int unlock = 1;
2676
2677         printk("\nShowing all locks held in the system:\n");
2678
2679         /*
2680          * Here we try to get the tasklist_lock as hard as possible,
2681          * if not successful after 2 seconds we ignore it (but keep
2682          * trying). This is to enable a debug printout even if a
2683          * tasklist_lock-holding task deadlocks or crashes.
2684          */
2685 retry:
2686         if (!read_trylock(&tasklist_lock)) {
2687                 if (count == 10)
2688                         printk("hm, tasklist_lock locked, retrying... ");
2689                 if (count) {
2690                         count--;
2691                         printk(" #%d", 10-count);
2692                         mdelay(200);
2693                         goto retry;
2694                 }
2695                 printk(" ignoring it.\n");
2696                 unlock = 0;
2697         }
2698         if (count != 10)
2699                 printk(" locked it.\n");
2700
2701         do_each_thread(g, p) {
2702                 if (p->lockdep_depth)
2703                         lockdep_print_held_locks(p);
2704                 if (!unlock)
2705                         if (read_trylock(&tasklist_lock))
2706                                 unlock = 1;
2707         } while_each_thread(g, p);
2708
2709         printk("\n");
2710         printk("=============================================\n\n");
2711
2712         if (unlock)
2713                 read_unlock(&tasklist_lock);
2714 }
2715
2716 EXPORT_SYMBOL_GPL(debug_show_all_locks);
2717
2718 void debug_show_held_locks(struct task_struct *task)
2719 {
2720         lockdep_print_held_locks(task);
2721 }
2722
2723 EXPORT_SYMBOL_GPL(debug_show_held_locks);
2724