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1/*
2 * kernel/lockdep.c
3 *
4 * Runtime locking correctness validator
5 *
6 * Started by Ingo Molnar:
7 *
8 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
10 *
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
13 *
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
17 *
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
20 *
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
24 *
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
27 */
28#define DISABLE_BRANCH_PROFILING
29#include <linux/mutex.h>
30#include <linux/sched.h>
31#include <linux/delay.h>
32#include <linux/module.h>
33#include <linux/proc_fs.h>
34#include <linux/seq_file.h>
35#include <linux/spinlock.h>
36#include <linux/kallsyms.h>
37#include <linux/interrupt.h>
38#include <linux/stacktrace.h>
39#include <linux/debug_locks.h>
40#include <linux/irqflags.h>
41#include <linux/utsname.h>
42#include <linux/hash.h>
43#include <linux/ftrace.h>
44#include <linux/stringify.h>
45#include <linux/bitops.h>
46#include <linux/gfp.h>
47#include <linux/kmemcheck.h>
48
49#include <asm/sections.h>
50
51#include "lockdep_internals.h"
52
53#define CREATE_TRACE_POINTS
54#include <trace/events/lock.h>
55
56#ifdef CONFIG_PROVE_LOCKING
57int prove_locking = 1;
58module_param(prove_locking, int, 0644);
59#else
60#define prove_locking 0
61#endif
62
63#ifdef CONFIG_LOCK_STAT
64int lock_stat = 1;
65module_param(lock_stat, int, 0644);
66#else
67#define lock_stat 0
68#endif
69
70/*
71 * lockdep_lock: protects the lockdep graph, the hashes and the
72 * class/list/hash allocators.
73 *
74 * This is one of the rare exceptions where it's justified
75 * to use a raw spinlock - we really dont want the spinlock
76 * code to recurse back into the lockdep code...
77 */
78static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
79
80static int graph_lock(void)
81{
82 arch_spin_lock(&lockdep_lock);
83 /*
84 * Make sure that if another CPU detected a bug while
85 * walking the graph we dont change it (while the other
86 * CPU is busy printing out stuff with the graph lock
87 * dropped already)
88 */
89 if (!debug_locks) {
90 arch_spin_unlock(&lockdep_lock);
91 return 0;
92 }
93 /* prevent any recursions within lockdep from causing deadlocks */
94 current->lockdep_recursion++;
95 return 1;
96}
97
98static inline int graph_unlock(void)
99{
100 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
101 /*
102 * The lockdep graph lock isn't locked while we expect it to
103 * be, we're confused now, bye!
104 */
105 return DEBUG_LOCKS_WARN_ON(1);
106 }
107
108 current->lockdep_recursion--;
109 arch_spin_unlock(&lockdep_lock);
110 return 0;
111}
112
113/*
114 * Turn lock debugging off and return with 0 if it was off already,
115 * and also release the graph lock:
116 */
117static inline int debug_locks_off_graph_unlock(void)
118{
119 int ret = debug_locks_off();
120
121 arch_spin_unlock(&lockdep_lock);
122
123 return ret;
124}
125
126static int lockdep_initialized;
127
128unsigned long nr_list_entries;
129static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
130
131/*
132 * All data structures here are protected by the global debug_lock.
133 *
134 * Mutex key structs only get allocated, once during bootup, and never
135 * get freed - this significantly simplifies the debugging code.
136 */
137unsigned long nr_lock_classes;
138static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
139
140static inline struct lock_class *hlock_class(struct held_lock *hlock)
141{
142 if (!hlock->class_idx) {
143 /*
144 * Someone passed in garbage, we give up.
145 */
146 DEBUG_LOCKS_WARN_ON(1);
147 return NULL;
148 }
149 return lock_classes + hlock->class_idx - 1;
150}
151
152#ifdef CONFIG_LOCK_STAT
153static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
154 cpu_lock_stats);
155
156static inline u64 lockstat_clock(void)
157{
158 return local_clock();
159}
160
161static int lock_point(unsigned long points[], unsigned long ip)
162{
163 int i;
164
165 for (i = 0; i < LOCKSTAT_POINTS; i++) {
166 if (points[i] == 0) {
167 points[i] = ip;
168 break;
169 }
170 if (points[i] == ip)
171 break;
172 }
173
174 return i;
175}
176
177static void lock_time_inc(struct lock_time *lt, u64 time)
178{
179 if (time > lt->max)
180 lt->max = time;
181
182 if (time < lt->min || !lt->nr)
183 lt->min = time;
184
185 lt->total += time;
186 lt->nr++;
187}
188
189static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
190{
191 if (!src->nr)
192 return;
193
194 if (src->max > dst->max)
195 dst->max = src->max;
196
197 if (src->min < dst->min || !dst->nr)
198 dst->min = src->min;
199
200 dst->total += src->total;
201 dst->nr += src->nr;
202}
203
204struct lock_class_stats lock_stats(struct lock_class *class)
205{
206 struct lock_class_stats stats;
207 int cpu, i;
208
209 memset(&stats, 0, sizeof(struct lock_class_stats));
210 for_each_possible_cpu(cpu) {
211 struct lock_class_stats *pcs =
212 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
213
214 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
215 stats.contention_point[i] += pcs->contention_point[i];
216
217 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
218 stats.contending_point[i] += pcs->contending_point[i];
219
220 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
221 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
222
223 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
224 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
225
226 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
227 stats.bounces[i] += pcs->bounces[i];
228 }
229
230 return stats;
231}
232
233void clear_lock_stats(struct lock_class *class)
234{
235 int cpu;
236
237 for_each_possible_cpu(cpu) {
238 struct lock_class_stats *cpu_stats =
239 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
240
241 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
242 }
243 memset(class->contention_point, 0, sizeof(class->contention_point));
244 memset(class->contending_point, 0, sizeof(class->contending_point));
245}
246
247static struct lock_class_stats *get_lock_stats(struct lock_class *class)
248{
249 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
250}
251
252static void put_lock_stats(struct lock_class_stats *stats)
253{
254 put_cpu_var(cpu_lock_stats);
255}
256
257static void lock_release_holdtime(struct held_lock *hlock)
258{
259 struct lock_class_stats *stats;
260 u64 holdtime;
261
262 if (!lock_stat)
263 return;
264
265 holdtime = lockstat_clock() - hlock->holdtime_stamp;
266
267 stats = get_lock_stats(hlock_class(hlock));
268 if (hlock->read)
269 lock_time_inc(&stats->read_holdtime, holdtime);
270 else
271 lock_time_inc(&stats->write_holdtime, holdtime);
272 put_lock_stats(stats);
273}
274#else
275static inline void lock_release_holdtime(struct held_lock *hlock)
276{
277}
278#endif
279
280/*
281 * We keep a global list of all lock classes. The list only grows,
282 * never shrinks. The list is only accessed with the lockdep
283 * spinlock lock held.
284 */
285LIST_HEAD(all_lock_classes);
286
287/*
288 * The lockdep classes are in a hash-table as well, for fast lookup:
289 */
290#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
291#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
292#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
293#define classhashentry(key) (classhash_table + __classhashfn((key)))
294
295static struct list_head classhash_table[CLASSHASH_SIZE];
296
297/*
298 * We put the lock dependency chains into a hash-table as well, to cache
299 * their existence:
300 */
301#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
302#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
303#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
304#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
305
306static struct list_head chainhash_table[CHAINHASH_SIZE];
307
308/*
309 * The hash key of the lock dependency chains is a hash itself too:
310 * it's a hash of all locks taken up to that lock, including that lock.
311 * It's a 64-bit hash, because it's important for the keys to be
312 * unique.
313 */
314#define iterate_chain_key(key1, key2) \
315 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
316 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
317 (key2))
318
319void lockdep_off(void)
320{
321 current->lockdep_recursion++;
322}
323EXPORT_SYMBOL(lockdep_off);
324
325void lockdep_on(void)
326{
327 current->lockdep_recursion--;
328}
329EXPORT_SYMBOL(lockdep_on);
330
331/*
332 * Debugging switches:
333 */
334
335#define VERBOSE 0
336#define VERY_VERBOSE 0
337
338#if VERBOSE
339# define HARDIRQ_VERBOSE 1
340# define SOFTIRQ_VERBOSE 1
341# define RECLAIM_VERBOSE 1
342#else
343# define HARDIRQ_VERBOSE 0
344# define SOFTIRQ_VERBOSE 0
345# define RECLAIM_VERBOSE 0
346#endif
347
348#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
349/*
350 * Quick filtering for interesting events:
351 */
352static int class_filter(struct lock_class *class)
353{
354#if 0
355 /* Example */
356 if (class->name_version == 1 &&
357 !strcmp(class->name, "lockname"))
358 return 1;
359 if (class->name_version == 1 &&
360 !strcmp(class->name, "&struct->lockfield"))
361 return 1;
362#endif
363 /* Filter everything else. 1 would be to allow everything else */
364 return 0;
365}
366#endif
367
368static int verbose(struct lock_class *class)
369{
370#if VERBOSE
371 return class_filter(class);
372#endif
373 return 0;
374}
375
376/*
377 * Stack-trace: tightly packed array of stack backtrace
378 * addresses. Protected by the graph_lock.
379 */
380unsigned long nr_stack_trace_entries;
381static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
382
383static int save_trace(struct stack_trace *trace)
384{
385 trace->nr_entries = 0;
386 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
387 trace->entries = stack_trace + nr_stack_trace_entries;
388
389 trace->skip = 3;
390
391 save_stack_trace(trace);
392
393 /*
394 * Some daft arches put -1 at the end to indicate its a full trace.
395 *
396 * <rant> this is buggy anyway, since it takes a whole extra entry so a
397 * complete trace that maxes out the entries provided will be reported
398 * as incomplete, friggin useless </rant>
399 */
400 if (trace->nr_entries != 0 &&
401 trace->entries[trace->nr_entries-1] == ULONG_MAX)
402 trace->nr_entries--;
403
404 trace->max_entries = trace->nr_entries;
405
406 nr_stack_trace_entries += trace->nr_entries;
407
408 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
409 if (!debug_locks_off_graph_unlock())
410 return 0;
411
412 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
413 printk("turning off the locking correctness validator.\n");
414 dump_stack();
415
416 return 0;
417 }
418
419 return 1;
420}
421
422unsigned int nr_hardirq_chains;
423unsigned int nr_softirq_chains;
424unsigned int nr_process_chains;
425unsigned int max_lockdep_depth;
426
427#ifdef CONFIG_DEBUG_LOCKDEP
428/*
429 * We cannot printk in early bootup code. Not even early_printk()
430 * might work. So we mark any initialization errors and printk
431 * about it later on, in lockdep_info().
432 */
433static int lockdep_init_error;
434static const char *lock_init_error;
435static unsigned long lockdep_init_trace_data[20];
436static struct stack_trace lockdep_init_trace = {
437 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
438 .entries = lockdep_init_trace_data,
439};
440
441/*
442 * Various lockdep statistics:
443 */
444DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
445#endif
446
447/*
448 * Locking printouts:
449 */
450
451#define __USAGE(__STATE) \
452 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
453 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
454 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
455 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
456
457static const char *usage_str[] =
458{
459#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
460#include "lockdep_states.h"
461#undef LOCKDEP_STATE
462 [LOCK_USED] = "INITIAL USE",
463};
464
465const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
466{
467 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
468}
469
470static inline unsigned long lock_flag(enum lock_usage_bit bit)
471{
472 return 1UL << bit;
473}
474
475static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
476{
477 char c = '.';
478
479 if (class->usage_mask & lock_flag(bit + 2))
480 c = '+';
481 if (class->usage_mask & lock_flag(bit)) {
482 c = '-';
483 if (class->usage_mask & lock_flag(bit + 2))
484 c = '?';
485 }
486
487 return c;
488}
489
490void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
491{
492 int i = 0;
493
494#define LOCKDEP_STATE(__STATE) \
495 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
496 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
497#include "lockdep_states.h"
498#undef LOCKDEP_STATE
499
500 usage[i] = '\0';
501}
502
503static void __print_lock_name(struct lock_class *class)
504{
505 char str[KSYM_NAME_LEN];
506 const char *name;
507
508 name = class->name;
509 if (!name) {
510 name = __get_key_name(class->key, str);
511 printk("%s", name);
512 } else {
513 printk("%s", name);
514 if (class->name_version > 1)
515 printk("#%d", class->name_version);
516 if (class->subclass)
517 printk("/%d", class->subclass);
518 }
519}
520
521static void print_lock_name(struct lock_class *class)
522{
523 char usage[LOCK_USAGE_CHARS];
524
525 get_usage_chars(class, usage);
526
527 printk(" (");
528 __print_lock_name(class);
529 printk("){%s}", usage);
530}
531
532static void print_lockdep_cache(struct lockdep_map *lock)
533{
534 const char *name;
535 char str[KSYM_NAME_LEN];
536
537 name = lock->name;
538 if (!name)
539 name = __get_key_name(lock->key->subkeys, str);
540
541 printk("%s", name);
542}
543
544static void print_lock(struct held_lock *hlock)
545{
546 print_lock_name(hlock_class(hlock));
547 printk(", at: ");
548 print_ip_sym(hlock->acquire_ip);
549}
550
551static void lockdep_print_held_locks(struct task_struct *curr)
552{
553 int i, depth = curr->lockdep_depth;
554
555 if (!depth) {
556 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
557 return;
558 }
559 printk("%d lock%s held by %s/%d:\n",
560 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
561
562 for (i = 0; i < depth; i++) {
563 printk(" #%d: ", i);
564 print_lock(curr->held_locks + i);
565 }
566}
567
568static void print_kernel_ident(void)
569{
570 printk("%s %.*s %s\n", init_utsname()->release,
571 (int)strcspn(init_utsname()->version, " "),
572 init_utsname()->version,
573 print_tainted());
574}
575
576static int very_verbose(struct lock_class *class)
577{
578#if VERY_VERBOSE
579 return class_filter(class);
580#endif
581 return 0;
582}
583
584/*
585 * Is this the address of a static object:
586 */
587static int static_obj(void *obj)
588{
589 unsigned long start = (unsigned long) &_stext,
590 end = (unsigned long) &_end,
591 addr = (unsigned long) obj;
592
593 /*
594 * static variable?
595 */
596 if ((addr >= start) && (addr < end))
597 return 1;
598
599 if (arch_is_kernel_data(addr))
600 return 1;
601
602 /*
603 * in-kernel percpu var?
604 */
605 if (is_kernel_percpu_address(addr))
606 return 1;
607
608 /*
609 * module static or percpu var?
610 */
611 return is_module_address(addr) || is_module_percpu_address(addr);
612}
613
614/*
615 * To make lock name printouts unique, we calculate a unique
616 * class->name_version generation counter:
617 */
618static int count_matching_names(struct lock_class *new_class)
619{
620 struct lock_class *class;
621 int count = 0;
622
623 if (!new_class->name)
624 return 0;
625
626 list_for_each_entry(class, &all_lock_classes, lock_entry) {
627 if (new_class->key - new_class->subclass == class->key)
628 return class->name_version;
629 if (class->name && !strcmp(class->name, new_class->name))
630 count = max(count, class->name_version);
631 }
632
633 return count + 1;
634}
635
636/*
637 * Register a lock's class in the hash-table, if the class is not present
638 * yet. Otherwise we look it up. We cache the result in the lock object
639 * itself, so actual lookup of the hash should be once per lock object.
640 */
641static inline struct lock_class *
642look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
643{
644 struct lockdep_subclass_key *key;
645 struct list_head *hash_head;
646 struct lock_class *class;
647
648#ifdef CONFIG_DEBUG_LOCKDEP
649 /*
650 * If the architecture calls into lockdep before initializing
651 * the hashes then we'll warn about it later. (we cannot printk
652 * right now)
653 */
654 if (unlikely(!lockdep_initialized)) {
655 lockdep_init();
656 lockdep_init_error = 1;
657 lock_init_error = lock->name;
658 save_stack_trace(&lockdep_init_trace);
659 }
660#endif
661
662 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
663 debug_locks_off();
664 printk(KERN_ERR
665 "BUG: looking up invalid subclass: %u\n", subclass);
666 printk(KERN_ERR
667 "turning off the locking correctness validator.\n");
668 dump_stack();
669 return NULL;
670 }
671
672 /*
673 * Static locks do not have their class-keys yet - for them the key
674 * is the lock object itself:
675 */
676 if (unlikely(!lock->key))
677 lock->key = (void *)lock;
678
679 /*
680 * NOTE: the class-key must be unique. For dynamic locks, a static
681 * lock_class_key variable is passed in through the mutex_init()
682 * (or spin_lock_init()) call - which acts as the key. For static
683 * locks we use the lock object itself as the key.
684 */
685 BUILD_BUG_ON(sizeof(struct lock_class_key) >
686 sizeof(struct lockdep_map));
687
688 key = lock->key->subkeys + subclass;
689
690 hash_head = classhashentry(key);
691
692 /*
693 * We can walk the hash lockfree, because the hash only
694 * grows, and we are careful when adding entries to the end:
695 */
696 list_for_each_entry(class, hash_head, hash_entry) {
697 if (class->key == key) {
698 /*
699 * Huh! same key, different name? Did someone trample
700 * on some memory? We're most confused.
701 */
702 WARN_ON_ONCE(class->name != lock->name);
703 return class;
704 }
705 }
706
707 return NULL;
708}
709
710/*
711 * Register a lock's class in the hash-table, if the class is not present
712 * yet. Otherwise we look it up. We cache the result in the lock object
713 * itself, so actual lookup of the hash should be once per lock object.
714 */
715static inline struct lock_class *
716register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
717{
718 struct lockdep_subclass_key *key;
719 struct list_head *hash_head;
720 struct lock_class *class;
721 unsigned long flags;
722
723 class = look_up_lock_class(lock, subclass);
724 if (likely(class))
725 goto out_set_class_cache;
726
727 /*
728 * Debug-check: all keys must be persistent!
729 */
730 if (!static_obj(lock->key)) {
731 debug_locks_off();
732 printk("INFO: trying to register non-static key.\n");
733 printk("the code is fine but needs lockdep annotation.\n");
734 printk("turning off the locking correctness validator.\n");
735 dump_stack();
736
737 return NULL;
738 }
739
740 key = lock->key->subkeys + subclass;
741 hash_head = classhashentry(key);
742
743 raw_local_irq_save(flags);
744 if (!graph_lock()) {
745 raw_local_irq_restore(flags);
746 return NULL;
747 }
748 /*
749 * We have to do the hash-walk again, to avoid races
750 * with another CPU:
751 */
752 list_for_each_entry(class, hash_head, hash_entry)
753 if (class->key == key)
754 goto out_unlock_set;
755 /*
756 * Allocate a new key from the static array, and add it to
757 * the hash:
758 */
759 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
760 if (!debug_locks_off_graph_unlock()) {
761 raw_local_irq_restore(flags);
762 return NULL;
763 }
764 raw_local_irq_restore(flags);
765
766 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
767 printk("turning off the locking correctness validator.\n");
768 dump_stack();
769 return NULL;
770 }
771 class = lock_classes + nr_lock_classes++;
772 debug_atomic_inc(nr_unused_locks);
773 class->key = key;
774 class->name = lock->name;
775 class->subclass = subclass;
776 INIT_LIST_HEAD(&class->lock_entry);
777 INIT_LIST_HEAD(&class->locks_before);
778 INIT_LIST_HEAD(&class->locks_after);
779 class->name_version = count_matching_names(class);
780 /*
781 * We use RCU's safe list-add method to make
782 * parallel walking of the hash-list safe:
783 */
784 list_add_tail_rcu(&class->hash_entry, hash_head);
785 /*
786 * Add it to the global list of classes:
787 */
788 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
789
790 if (verbose(class)) {
791 graph_unlock();
792 raw_local_irq_restore(flags);
793
794 printk("\nnew class %p: %s", class->key, class->name);
795 if (class->name_version > 1)
796 printk("#%d", class->name_version);
797 printk("\n");
798 dump_stack();
799
800 raw_local_irq_save(flags);
801 if (!graph_lock()) {
802 raw_local_irq_restore(flags);
803 return NULL;
804 }
805 }
806out_unlock_set:
807 graph_unlock();
808 raw_local_irq_restore(flags);
809
810out_set_class_cache:
811 if (!subclass || force)
812 lock->class_cache[0] = class;
813 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
814 lock->class_cache[subclass] = class;
815
816 /*
817 * Hash collision, did we smoke some? We found a class with a matching
818 * hash but the subclass -- which is hashed in -- didn't match.
819 */
820 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
821 return NULL;
822
823 return class;
824}
825
826#ifdef CONFIG_PROVE_LOCKING
827/*
828 * Allocate a lockdep entry. (assumes the graph_lock held, returns
829 * with NULL on failure)
830 */
831static struct lock_list *alloc_list_entry(void)
832{
833 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
834 if (!debug_locks_off_graph_unlock())
835 return NULL;
836
837 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
838 printk("turning off the locking correctness validator.\n");
839 dump_stack();
840 return NULL;
841 }
842 return list_entries + nr_list_entries++;
843}
844
845/*
846 * Add a new dependency to the head of the list:
847 */
848static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
849 struct list_head *head, unsigned long ip,
850 int distance, struct stack_trace *trace)
851{
852 struct lock_list *entry;
853 /*
854 * Lock not present yet - get a new dependency struct and
855 * add it to the list:
856 */
857 entry = alloc_list_entry();
858 if (!entry)
859 return 0;
860
861 entry->class = this;
862 entry->distance = distance;
863 entry->trace = *trace;
864 /*
865 * Since we never remove from the dependency list, the list can
866 * be walked lockless by other CPUs, it's only allocation
867 * that must be protected by the spinlock. But this also means
868 * we must make new entries visible only once writes to the
869 * entry become visible - hence the RCU op:
870 */
871 list_add_tail_rcu(&entry->entry, head);
872
873 return 1;
874}
875
876/*
877 * For good efficiency of modular, we use power of 2
878 */
879#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
880#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
881
882/*
883 * The circular_queue and helpers is used to implement the
884 * breadth-first search(BFS)algorithem, by which we can build
885 * the shortest path from the next lock to be acquired to the
886 * previous held lock if there is a circular between them.
887 */
888struct circular_queue {
889 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
890 unsigned int front, rear;
891};
892
893static struct circular_queue lock_cq;
894
895unsigned int max_bfs_queue_depth;
896
897static unsigned int lockdep_dependency_gen_id;
898
899static inline void __cq_init(struct circular_queue *cq)
900{
901 cq->front = cq->rear = 0;
902 lockdep_dependency_gen_id++;
903}
904
905static inline int __cq_empty(struct circular_queue *cq)
906{
907 return (cq->front == cq->rear);
908}
909
910static inline int __cq_full(struct circular_queue *cq)
911{
912 return ((cq->rear + 1) & CQ_MASK) == cq->front;
913}
914
915static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
916{
917 if (__cq_full(cq))
918 return -1;
919
920 cq->element[cq->rear] = elem;
921 cq->rear = (cq->rear + 1) & CQ_MASK;
922 return 0;
923}
924
925static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
926{
927 if (__cq_empty(cq))
928 return -1;
929
930 *elem = cq->element[cq->front];
931 cq->front = (cq->front + 1) & CQ_MASK;
932 return 0;
933}
934
935static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
936{
937 return (cq->rear - cq->front) & CQ_MASK;
938}
939
940static inline void mark_lock_accessed(struct lock_list *lock,
941 struct lock_list *parent)
942{
943 unsigned long nr;
944
945 nr = lock - list_entries;
946 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
947 lock->parent = parent;
948 lock->class->dep_gen_id = lockdep_dependency_gen_id;
949}
950
951static inline unsigned long lock_accessed(struct lock_list *lock)
952{
953 unsigned long nr;
954
955 nr = lock - list_entries;
956 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
957 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
958}
959
960static inline struct lock_list *get_lock_parent(struct lock_list *child)
961{
962 return child->parent;
963}
964
965static inline int get_lock_depth(struct lock_list *child)
966{
967 int depth = 0;
968 struct lock_list *parent;
969
970 while ((parent = get_lock_parent(child))) {
971 child = parent;
972 depth++;
973 }
974 return depth;
975}
976
977static int __bfs(struct lock_list *source_entry,
978 void *data,
979 int (*match)(struct lock_list *entry, void *data),
980 struct lock_list **target_entry,
981 int forward)
982{
983 struct lock_list *entry;
984 struct list_head *head;
985 struct circular_queue *cq = &lock_cq;
986 int ret = 1;
987
988 if (match(source_entry, data)) {
989 *target_entry = source_entry;
990 ret = 0;
991 goto exit;
992 }
993
994 if (forward)
995 head = &source_entry->class->locks_after;
996 else
997 head = &source_entry->class->locks_before;
998
999 if (list_empty(head))
1000 goto exit;
1001
1002 __cq_init(cq);
1003 __cq_enqueue(cq, (unsigned long)source_entry);
1004
1005 while (!__cq_empty(cq)) {
1006 struct lock_list *lock;
1007
1008 __cq_dequeue(cq, (unsigned long *)&lock);
1009
1010 if (!lock->class) {
1011 ret = -2;
1012 goto exit;
1013 }
1014
1015 if (forward)
1016 head = &lock->class->locks_after;
1017 else
1018 head = &lock->class->locks_before;
1019
1020 list_for_each_entry(entry, head, entry) {
1021 if (!lock_accessed(entry)) {
1022 unsigned int cq_depth;
1023 mark_lock_accessed(entry, lock);
1024 if (match(entry, data)) {
1025 *target_entry = entry;
1026 ret = 0;
1027 goto exit;
1028 }
1029
1030 if (__cq_enqueue(cq, (unsigned long)entry)) {
1031 ret = -1;
1032 goto exit;
1033 }
1034 cq_depth = __cq_get_elem_count(cq);
1035 if (max_bfs_queue_depth < cq_depth)
1036 max_bfs_queue_depth = cq_depth;
1037 }
1038 }
1039 }
1040exit:
1041 return ret;
1042}
1043
1044static inline int __bfs_forwards(struct lock_list *src_entry,
1045 void *data,
1046 int (*match)(struct lock_list *entry, void *data),
1047 struct lock_list **target_entry)
1048{
1049 return __bfs(src_entry, data, match, target_entry, 1);
1050
1051}
1052
1053static inline int __bfs_backwards(struct lock_list *src_entry,
1054 void *data,
1055 int (*match)(struct lock_list *entry, void *data),
1056 struct lock_list **target_entry)
1057{
1058 return __bfs(src_entry, data, match, target_entry, 0);
1059
1060}
1061
1062/*
1063 * Recursive, forwards-direction lock-dependency checking, used for
1064 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1065 * checking.
1066 */
1067
1068/*
1069 * Print a dependency chain entry (this is only done when a deadlock
1070 * has been detected):
1071 */
1072static noinline int
1073print_circular_bug_entry(struct lock_list *target, int depth)
1074{
1075 if (debug_locks_silent)
1076 return 0;
1077 printk("\n-> #%u", depth);
1078 print_lock_name(target->class);
1079 printk(":\n");
1080 print_stack_trace(&target->trace, 6);
1081
1082 return 0;
1083}
1084
1085static void
1086print_circular_lock_scenario(struct held_lock *src,
1087 struct held_lock *tgt,
1088 struct lock_list *prt)
1089{
1090 struct lock_class *source = hlock_class(src);
1091 struct lock_class *target = hlock_class(tgt);
1092 struct lock_class *parent = prt->class;
1093
1094 /*
1095 * A direct locking problem where unsafe_class lock is taken
1096 * directly by safe_class lock, then all we need to show
1097 * is the deadlock scenario, as it is obvious that the
1098 * unsafe lock is taken under the safe lock.
1099 *
1100 * But if there is a chain instead, where the safe lock takes
1101 * an intermediate lock (middle_class) where this lock is
1102 * not the same as the safe lock, then the lock chain is
1103 * used to describe the problem. Otherwise we would need
1104 * to show a different CPU case for each link in the chain
1105 * from the safe_class lock to the unsafe_class lock.
1106 */
1107 if (parent != source) {
1108 printk("Chain exists of:\n ");
1109 __print_lock_name(source);
1110 printk(" --> ");
1111 __print_lock_name(parent);
1112 printk(" --> ");
1113 __print_lock_name(target);
1114 printk("\n\n");
1115 }
1116
1117 printk(" Possible unsafe locking scenario:\n\n");
1118 printk(" CPU0 CPU1\n");
1119 printk(" ---- ----\n");
1120 printk(" lock(");
1121 __print_lock_name(target);
1122 printk(");\n");
1123 printk(" lock(");
1124 __print_lock_name(parent);
1125 printk(");\n");
1126 printk(" lock(");
1127 __print_lock_name(target);
1128 printk(");\n");
1129 printk(" lock(");
1130 __print_lock_name(source);
1131 printk(");\n");
1132 printk("\n *** DEADLOCK ***\n\n");
1133}
1134
1135/*
1136 * When a circular dependency is detected, print the
1137 * header first:
1138 */
1139static noinline int
1140print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1141 struct held_lock *check_src,
1142 struct held_lock *check_tgt)
1143{
1144 struct task_struct *curr = current;
1145
1146 if (debug_locks_silent)
1147 return 0;
1148
1149 printk("\n");
1150 printk("======================================================\n");
1151 printk("[ INFO: possible circular locking dependency detected ]\n");
1152 print_kernel_ident();
1153 printk("-------------------------------------------------------\n");
1154 printk("%s/%d is trying to acquire lock:\n",
1155 curr->comm, task_pid_nr(curr));
1156 print_lock(check_src);
1157 printk("\nbut task is already holding lock:\n");
1158 print_lock(check_tgt);
1159 printk("\nwhich lock already depends on the new lock.\n\n");
1160 printk("\nthe existing dependency chain (in reverse order) is:\n");
1161
1162 print_circular_bug_entry(entry, depth);
1163
1164 return 0;
1165}
1166
1167static inline int class_equal(struct lock_list *entry, void *data)
1168{
1169 return entry->class == data;
1170}
1171
1172static noinline int print_circular_bug(struct lock_list *this,
1173 struct lock_list *target,
1174 struct held_lock *check_src,
1175 struct held_lock *check_tgt)
1176{
1177 struct task_struct *curr = current;
1178 struct lock_list *parent;
1179 struct lock_list *first_parent;
1180 int depth;
1181
1182 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1183 return 0;
1184
1185 if (!save_trace(&this->trace))
1186 return 0;
1187
1188 depth = get_lock_depth(target);
1189
1190 print_circular_bug_header(target, depth, check_src, check_tgt);
1191
1192 parent = get_lock_parent(target);
1193 first_parent = parent;
1194
1195 while (parent) {
1196 print_circular_bug_entry(parent, --depth);
1197 parent = get_lock_parent(parent);
1198 }
1199
1200 printk("\nother info that might help us debug this:\n\n");
1201 print_circular_lock_scenario(check_src, check_tgt,
1202 first_parent);
1203
1204 lockdep_print_held_locks(curr);
1205
1206 printk("\nstack backtrace:\n");
1207 dump_stack();
1208
1209 return 0;
1210}
1211
1212static noinline int print_bfs_bug(int ret)
1213{
1214 if (!debug_locks_off_graph_unlock())
1215 return 0;
1216
1217 /*
1218 * Breadth-first-search failed, graph got corrupted?
1219 */
1220 WARN(1, "lockdep bfs error:%d\n", ret);
1221
1222 return 0;
1223}
1224
1225static int noop_count(struct lock_list *entry, void *data)
1226{
1227 (*(unsigned long *)data)++;
1228 return 0;
1229}
1230
1231unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1232{
1233 unsigned long count = 0;
1234 struct lock_list *uninitialized_var(target_entry);
1235
1236 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1237
1238 return count;
1239}
1240unsigned long lockdep_count_forward_deps(struct lock_class *class)
1241{
1242 unsigned long ret, flags;
1243 struct lock_list this;
1244
1245 this.parent = NULL;
1246 this.class = class;
1247
1248 local_irq_save(flags);
1249 arch_spin_lock(&lockdep_lock);
1250 ret = __lockdep_count_forward_deps(&this);
1251 arch_spin_unlock(&lockdep_lock);
1252 local_irq_restore(flags);
1253
1254 return ret;
1255}
1256
1257unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1258{
1259 unsigned long count = 0;
1260 struct lock_list *uninitialized_var(target_entry);
1261
1262 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1263
1264 return count;
1265}
1266
1267unsigned long lockdep_count_backward_deps(struct lock_class *class)
1268{
1269 unsigned long ret, flags;
1270 struct lock_list this;
1271
1272 this.parent = NULL;
1273 this.class = class;
1274
1275 local_irq_save(flags);
1276 arch_spin_lock(&lockdep_lock);
1277 ret = __lockdep_count_backward_deps(&this);
1278 arch_spin_unlock(&lockdep_lock);
1279 local_irq_restore(flags);
1280
1281 return ret;
1282}
1283
1284/*
1285 * Prove that the dependency graph starting at <entry> can not
1286 * lead to <target>. Print an error and return 0 if it does.
1287 */
1288static noinline int
1289check_noncircular(struct lock_list *root, struct lock_class *target,
1290 struct lock_list **target_entry)
1291{
1292 int result;
1293
1294 debug_atomic_inc(nr_cyclic_checks);
1295
1296 result = __bfs_forwards(root, target, class_equal, target_entry);
1297
1298 return result;
1299}
1300
1301#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1302/*
1303 * Forwards and backwards subgraph searching, for the purposes of
1304 * proving that two subgraphs can be connected by a new dependency
1305 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1306 */
1307
1308static inline int usage_match(struct lock_list *entry, void *bit)
1309{
1310 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1311}
1312
1313
1314
1315/*
1316 * Find a node in the forwards-direction dependency sub-graph starting
1317 * at @root->class that matches @bit.
1318 *
1319 * Return 0 if such a node exists in the subgraph, and put that node
1320 * into *@target_entry.
1321 *
1322 * Return 1 otherwise and keep *@target_entry unchanged.
1323 * Return <0 on error.
1324 */
1325static int
1326find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1327 struct lock_list **target_entry)
1328{
1329 int result;
1330
1331 debug_atomic_inc(nr_find_usage_forwards_checks);
1332
1333 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1334
1335 return result;
1336}
1337
1338/*
1339 * Find a node in the backwards-direction dependency sub-graph starting
1340 * at @root->class that matches @bit.
1341 *
1342 * Return 0 if such a node exists in the subgraph, and put that node
1343 * into *@target_entry.
1344 *
1345 * Return 1 otherwise and keep *@target_entry unchanged.
1346 * Return <0 on error.
1347 */
1348static int
1349find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1350 struct lock_list **target_entry)
1351{
1352 int result;
1353
1354 debug_atomic_inc(nr_find_usage_backwards_checks);
1355
1356 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1357
1358 return result;
1359}
1360
1361static void print_lock_class_header(struct lock_class *class, int depth)
1362{
1363 int bit;
1364
1365 printk("%*s->", depth, "");
1366 print_lock_name(class);
1367 printk(" ops: %lu", class->ops);
1368 printk(" {\n");
1369
1370 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1371 if (class->usage_mask & (1 << bit)) {
1372 int len = depth;
1373
1374 len += printk("%*s %s", depth, "", usage_str[bit]);
1375 len += printk(" at:\n");
1376 print_stack_trace(class->usage_traces + bit, len);
1377 }
1378 }
1379 printk("%*s }\n", depth, "");
1380
1381 printk("%*s ... key at: ",depth,"");
1382 print_ip_sym((unsigned long)class->key);
1383}
1384
1385/*
1386 * printk the shortest lock dependencies from @start to @end in reverse order:
1387 */
1388static void __used
1389print_shortest_lock_dependencies(struct lock_list *leaf,
1390 struct lock_list *root)
1391{
1392 struct lock_list *entry = leaf;
1393 int depth;
1394
1395 /*compute depth from generated tree by BFS*/
1396 depth = get_lock_depth(leaf);
1397
1398 do {
1399 print_lock_class_header(entry->class, depth);
1400 printk("%*s ... acquired at:\n", depth, "");
1401 print_stack_trace(&entry->trace, 2);
1402 printk("\n");
1403
1404 if (depth == 0 && (entry != root)) {
1405 printk("lockdep:%s bad path found in chain graph\n", __func__);
1406 break;
1407 }
1408
1409 entry = get_lock_parent(entry);
1410 depth--;
1411 } while (entry && (depth >= 0));
1412
1413 return;
1414}
1415
1416static void
1417print_irq_lock_scenario(struct lock_list *safe_entry,
1418 struct lock_list *unsafe_entry,
1419 struct lock_class *prev_class,
1420 struct lock_class *next_class)
1421{
1422 struct lock_class *safe_class = safe_entry->class;
1423 struct lock_class *unsafe_class = unsafe_entry->class;
1424 struct lock_class *middle_class = prev_class;
1425
1426 if (middle_class == safe_class)
1427 middle_class = next_class;
1428
1429 /*
1430 * A direct locking problem where unsafe_class lock is taken
1431 * directly by safe_class lock, then all we need to show
1432 * is the deadlock scenario, as it is obvious that the
1433 * unsafe lock is taken under the safe lock.
1434 *
1435 * But if there is a chain instead, where the safe lock takes
1436 * an intermediate lock (middle_class) where this lock is
1437 * not the same as the safe lock, then the lock chain is
1438 * used to describe the problem. Otherwise we would need
1439 * to show a different CPU case for each link in the chain
1440 * from the safe_class lock to the unsafe_class lock.
1441 */
1442 if (middle_class != unsafe_class) {
1443 printk("Chain exists of:\n ");
1444 __print_lock_name(safe_class);
1445 printk(" --> ");
1446 __print_lock_name(middle_class);
1447 printk(" --> ");
1448 __print_lock_name(unsafe_class);
1449 printk("\n\n");
1450 }
1451
1452 printk(" Possible interrupt unsafe locking scenario:\n\n");
1453 printk(" CPU0 CPU1\n");
1454 printk(" ---- ----\n");
1455 printk(" lock(");
1456 __print_lock_name(unsafe_class);
1457 printk(");\n");
1458 printk(" local_irq_disable();\n");
1459 printk(" lock(");
1460 __print_lock_name(safe_class);
1461 printk(");\n");
1462 printk(" lock(");
1463 __print_lock_name(middle_class);
1464 printk(");\n");
1465 printk(" <Interrupt>\n");
1466 printk(" lock(");
1467 __print_lock_name(safe_class);
1468 printk(");\n");
1469 printk("\n *** DEADLOCK ***\n\n");
1470}
1471
1472static int
1473print_bad_irq_dependency(struct task_struct *curr,
1474 struct lock_list *prev_root,
1475 struct lock_list *next_root,
1476 struct lock_list *backwards_entry,
1477 struct lock_list *forwards_entry,
1478 struct held_lock *prev,
1479 struct held_lock *next,
1480 enum lock_usage_bit bit1,
1481 enum lock_usage_bit bit2,
1482 const char *irqclass)
1483{
1484 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1485 return 0;
1486
1487 printk("\n");
1488 printk("======================================================\n");
1489 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1490 irqclass, irqclass);
1491 print_kernel_ident();
1492 printk("------------------------------------------------------\n");
1493 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1494 curr->comm, task_pid_nr(curr),
1495 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1496 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1497 curr->hardirqs_enabled,
1498 curr->softirqs_enabled);
1499 print_lock(next);
1500
1501 printk("\nand this task is already holding:\n");
1502 print_lock(prev);
1503 printk("which would create a new lock dependency:\n");
1504 print_lock_name(hlock_class(prev));
1505 printk(" ->");
1506 print_lock_name(hlock_class(next));
1507 printk("\n");
1508
1509 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1510 irqclass);
1511 print_lock_name(backwards_entry->class);
1512 printk("\n... which became %s-irq-safe at:\n", irqclass);
1513
1514 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1515
1516 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1517 print_lock_name(forwards_entry->class);
1518 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1519 printk("...");
1520
1521 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1522
1523 printk("\nother info that might help us debug this:\n\n");
1524 print_irq_lock_scenario(backwards_entry, forwards_entry,
1525 hlock_class(prev), hlock_class(next));
1526
1527 lockdep_print_held_locks(curr);
1528
1529 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1530 printk(" and the holding lock:\n");
1531 if (!save_trace(&prev_root->trace))
1532 return 0;
1533 print_shortest_lock_dependencies(backwards_entry, prev_root);
1534
1535 printk("\nthe dependencies between the lock to be acquired");
1536 printk(" and %s-irq-unsafe lock:\n", irqclass);
1537 if (!save_trace(&next_root->trace))
1538 return 0;
1539 print_shortest_lock_dependencies(forwards_entry, next_root);
1540
1541 printk("\nstack backtrace:\n");
1542 dump_stack();
1543
1544 return 0;
1545}
1546
1547static int
1548check_usage(struct task_struct *curr, struct held_lock *prev,
1549 struct held_lock *next, enum lock_usage_bit bit_backwards,
1550 enum lock_usage_bit bit_forwards, const char *irqclass)
1551{
1552 int ret;
1553 struct lock_list this, that;
1554 struct lock_list *uninitialized_var(target_entry);
1555 struct lock_list *uninitialized_var(target_entry1);
1556
1557 this.parent = NULL;
1558
1559 this.class = hlock_class(prev);
1560 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1561 if (ret < 0)
1562 return print_bfs_bug(ret);
1563 if (ret == 1)
1564 return ret;
1565
1566 that.parent = NULL;
1567 that.class = hlock_class(next);
1568 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1569 if (ret < 0)
1570 return print_bfs_bug(ret);
1571 if (ret == 1)
1572 return ret;
1573
1574 return print_bad_irq_dependency(curr, &this, &that,
1575 target_entry, target_entry1,
1576 prev, next,
1577 bit_backwards, bit_forwards, irqclass);
1578}
1579
1580static const char *state_names[] = {
1581#define LOCKDEP_STATE(__STATE) \
1582 __stringify(__STATE),
1583#include "lockdep_states.h"
1584#undef LOCKDEP_STATE
1585};
1586
1587static const char *state_rnames[] = {
1588#define LOCKDEP_STATE(__STATE) \
1589 __stringify(__STATE)"-READ",
1590#include "lockdep_states.h"
1591#undef LOCKDEP_STATE
1592};
1593
1594static inline const char *state_name(enum lock_usage_bit bit)
1595{
1596 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1597}
1598
1599static int exclusive_bit(int new_bit)
1600{
1601 /*
1602 * USED_IN
1603 * USED_IN_READ
1604 * ENABLED
1605 * ENABLED_READ
1606 *
1607 * bit 0 - write/read
1608 * bit 1 - used_in/enabled
1609 * bit 2+ state
1610 */
1611
1612 int state = new_bit & ~3;
1613 int dir = new_bit & 2;
1614
1615 /*
1616 * keep state, bit flip the direction and strip read.
1617 */
1618 return state | (dir ^ 2);
1619}
1620
1621static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1622 struct held_lock *next, enum lock_usage_bit bit)
1623{
1624 /*
1625 * Prove that the new dependency does not connect a hardirq-safe
1626 * lock with a hardirq-unsafe lock - to achieve this we search
1627 * the backwards-subgraph starting at <prev>, and the
1628 * forwards-subgraph starting at <next>:
1629 */
1630 if (!check_usage(curr, prev, next, bit,
1631 exclusive_bit(bit), state_name(bit)))
1632 return 0;
1633
1634 bit++; /* _READ */
1635
1636 /*
1637 * Prove that the new dependency does not connect a hardirq-safe-read
1638 * lock with a hardirq-unsafe lock - to achieve this we search
1639 * the backwards-subgraph starting at <prev>, and the
1640 * forwards-subgraph starting at <next>:
1641 */
1642 if (!check_usage(curr, prev, next, bit,
1643 exclusive_bit(bit), state_name(bit)))
1644 return 0;
1645
1646 return 1;
1647}
1648
1649static int
1650check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1651 struct held_lock *next)
1652{
1653#define LOCKDEP_STATE(__STATE) \
1654 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1655 return 0;
1656#include "lockdep_states.h"
1657#undef LOCKDEP_STATE
1658
1659 return 1;
1660}
1661
1662static void inc_chains(void)
1663{
1664 if (current->hardirq_context)
1665 nr_hardirq_chains++;
1666 else {
1667 if (current->softirq_context)
1668 nr_softirq_chains++;
1669 else
1670 nr_process_chains++;
1671 }
1672}
1673
1674#else
1675
1676static inline int
1677check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1678 struct held_lock *next)
1679{
1680 return 1;
1681}
1682
1683static inline void inc_chains(void)
1684{
1685 nr_process_chains++;
1686}
1687
1688#endif
1689
1690static void
1691print_deadlock_scenario(struct held_lock *nxt,
1692 struct held_lock *prv)
1693{
1694 struct lock_class *next = hlock_class(nxt);
1695 struct lock_class *prev = hlock_class(prv);
1696
1697 printk(" Possible unsafe locking scenario:\n\n");
1698 printk(" CPU0\n");
1699 printk(" ----\n");
1700 printk(" lock(");
1701 __print_lock_name(prev);
1702 printk(");\n");
1703 printk(" lock(");
1704 __print_lock_name(next);
1705 printk(");\n");
1706 printk("\n *** DEADLOCK ***\n\n");
1707 printk(" May be due to missing lock nesting notation\n\n");
1708}
1709
1710static int
1711print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1712 struct held_lock *next)
1713{
1714 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1715 return 0;
1716
1717 printk("\n");
1718 printk("=============================================\n");
1719 printk("[ INFO: possible recursive locking detected ]\n");
1720 print_kernel_ident();
1721 printk("---------------------------------------------\n");
1722 printk("%s/%d is trying to acquire lock:\n",
1723 curr->comm, task_pid_nr(curr));
1724 print_lock(next);
1725 printk("\nbut task is already holding lock:\n");
1726 print_lock(prev);
1727
1728 printk("\nother info that might help us debug this:\n");
1729 print_deadlock_scenario(next, prev);
1730 lockdep_print_held_locks(curr);
1731
1732 printk("\nstack backtrace:\n");
1733 dump_stack();
1734
1735 return 0;
1736}
1737
1738/*
1739 * Check whether we are holding such a class already.
1740 *
1741 * (Note that this has to be done separately, because the graph cannot
1742 * detect such classes of deadlocks.)
1743 *
1744 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1745 */
1746static int
1747check_deadlock(struct task_struct *curr, struct held_lock *next,
1748 struct lockdep_map *next_instance, int read)
1749{
1750 struct held_lock *prev;
1751 struct held_lock *nest = NULL;
1752 int i;
1753
1754 for (i = 0; i < curr->lockdep_depth; i++) {
1755 prev = curr->held_locks + i;
1756
1757 if (prev->instance == next->nest_lock)
1758 nest = prev;
1759
1760 if (hlock_class(prev) != hlock_class(next))
1761 continue;
1762
1763 /*
1764 * Allow read-after-read recursion of the same
1765 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1766 */
1767 if ((read == 2) && prev->read)
1768 return 2;
1769
1770 /*
1771 * We're holding the nest_lock, which serializes this lock's
1772 * nesting behaviour.
1773 */
1774 if (nest)
1775 return 2;
1776
1777 return print_deadlock_bug(curr, prev, next);
1778 }
1779 return 1;
1780}
1781
1782/*
1783 * There was a chain-cache miss, and we are about to add a new dependency
1784 * to a previous lock. We recursively validate the following rules:
1785 *
1786 * - would the adding of the <prev> -> <next> dependency create a
1787 * circular dependency in the graph? [== circular deadlock]
1788 *
1789 * - does the new prev->next dependency connect any hardirq-safe lock
1790 * (in the full backwards-subgraph starting at <prev>) with any
1791 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1792 * <next>)? [== illegal lock inversion with hardirq contexts]
1793 *
1794 * - does the new prev->next dependency connect any softirq-safe lock
1795 * (in the full backwards-subgraph starting at <prev>) with any
1796 * softirq-unsafe lock (in the full forwards-subgraph starting at
1797 * <next>)? [== illegal lock inversion with softirq contexts]
1798 *
1799 * any of these scenarios could lead to a deadlock.
1800 *
1801 * Then if all the validations pass, we add the forwards and backwards
1802 * dependency.
1803 */
1804static int
1805check_prev_add(struct task_struct *curr, struct held_lock *prev,
1806 struct held_lock *next, int distance, int trylock_loop)
1807{
1808 struct lock_list *entry;
1809 int ret;
1810 struct lock_list this;
1811 struct lock_list *uninitialized_var(target_entry);
1812 /*
1813 * Static variable, serialized by the graph_lock().
1814 *
1815 * We use this static variable to save the stack trace in case
1816 * we call into this function multiple times due to encountering
1817 * trylocks in the held lock stack.
1818 */
1819 static struct stack_trace trace;
1820
1821 /*
1822 * Prove that the new <prev> -> <next> dependency would not
1823 * create a circular dependency in the graph. (We do this by
1824 * forward-recursing into the graph starting at <next>, and
1825 * checking whether we can reach <prev>.)
1826 *
1827 * We are using global variables to control the recursion, to
1828 * keep the stackframe size of the recursive functions low:
1829 */
1830 this.class = hlock_class(next);
1831 this.parent = NULL;
1832 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1833 if (unlikely(!ret))
1834 return print_circular_bug(&this, target_entry, next, prev);
1835 else if (unlikely(ret < 0))
1836 return print_bfs_bug(ret);
1837
1838 if (!check_prev_add_irq(curr, prev, next))
1839 return 0;
1840
1841 /*
1842 * For recursive read-locks we do all the dependency checks,
1843 * but we dont store read-triggered dependencies (only
1844 * write-triggered dependencies). This ensures that only the
1845 * write-side dependencies matter, and that if for example a
1846 * write-lock never takes any other locks, then the reads are
1847 * equivalent to a NOP.
1848 */
1849 if (next->read == 2 || prev->read == 2)
1850 return 1;
1851 /*
1852 * Is the <prev> -> <next> dependency already present?
1853 *
1854 * (this may occur even though this is a new chain: consider
1855 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1856 * chains - the second one will be new, but L1 already has
1857 * L2 added to its dependency list, due to the first chain.)
1858 */
1859 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1860 if (entry->class == hlock_class(next)) {
1861 if (distance == 1)
1862 entry->distance = 1;
1863 return 2;
1864 }
1865 }
1866
1867 if (!trylock_loop && !save_trace(&trace))
1868 return 0;
1869
1870 /*
1871 * Ok, all validations passed, add the new lock
1872 * to the previous lock's dependency list:
1873 */
1874 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1875 &hlock_class(prev)->locks_after,
1876 next->acquire_ip, distance, &trace);
1877
1878 if (!ret)
1879 return 0;
1880
1881 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1882 &hlock_class(next)->locks_before,
1883 next->acquire_ip, distance, &trace);
1884 if (!ret)
1885 return 0;
1886
1887 /*
1888 * Debugging printouts:
1889 */
1890 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1891 graph_unlock();
1892 printk("\n new dependency: ");
1893 print_lock_name(hlock_class(prev));
1894 printk(" => ");
1895 print_lock_name(hlock_class(next));
1896 printk("\n");
1897 dump_stack();
1898 return graph_lock();
1899 }
1900 return 1;
1901}
1902
1903/*
1904 * Add the dependency to all directly-previous locks that are 'relevant'.
1905 * The ones that are relevant are (in increasing distance from curr):
1906 * all consecutive trylock entries and the final non-trylock entry - or
1907 * the end of this context's lock-chain - whichever comes first.
1908 */
1909static int
1910check_prevs_add(struct task_struct *curr, struct held_lock *next)
1911{
1912 int depth = curr->lockdep_depth;
1913 int trylock_loop = 0;
1914 struct held_lock *hlock;
1915
1916 /*
1917 * Debugging checks.
1918 *
1919 * Depth must not be zero for a non-head lock:
1920 */
1921 if (!depth)
1922 goto out_bug;
1923 /*
1924 * At least two relevant locks must exist for this
1925 * to be a head:
1926 */
1927 if (curr->held_locks[depth].irq_context !=
1928 curr->held_locks[depth-1].irq_context)
1929 goto out_bug;
1930
1931 for (;;) {
1932 int distance = curr->lockdep_depth - depth + 1;
1933 hlock = curr->held_locks + depth-1;
1934 /*
1935 * Only non-recursive-read entries get new dependencies
1936 * added:
1937 */
1938 if (hlock->read != 2) {
1939 if (!check_prev_add(curr, hlock, next,
1940 distance, trylock_loop))
1941 return 0;
1942 /*
1943 * Stop after the first non-trylock entry,
1944 * as non-trylock entries have added their
1945 * own direct dependencies already, so this
1946 * lock is connected to them indirectly:
1947 */
1948 if (!hlock->trylock)
1949 break;
1950 }
1951 depth--;
1952 /*
1953 * End of lock-stack?
1954 */
1955 if (!depth)
1956 break;
1957 /*
1958 * Stop the search if we cross into another context:
1959 */
1960 if (curr->held_locks[depth].irq_context !=
1961 curr->held_locks[depth-1].irq_context)
1962 break;
1963 trylock_loop = 1;
1964 }
1965 return 1;
1966out_bug:
1967 if (!debug_locks_off_graph_unlock())
1968 return 0;
1969
1970 /*
1971 * Clearly we all shouldn't be here, but since we made it we
1972 * can reliable say we messed up our state. See the above two
1973 * gotos for reasons why we could possibly end up here.
1974 */
1975 WARN_ON(1);
1976
1977 return 0;
1978}
1979
1980unsigned long nr_lock_chains;
1981struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1982int nr_chain_hlocks;
1983static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1984
1985struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1986{
1987 return lock_classes + chain_hlocks[chain->base + i];
1988}
1989
1990/*
1991 * Look up a dependency chain. If the key is not present yet then
1992 * add it and return 1 - in this case the new dependency chain is
1993 * validated. If the key is already hashed, return 0.
1994 * (On return with 1 graph_lock is held.)
1995 */
1996static inline int lookup_chain_cache(struct task_struct *curr,
1997 struct held_lock *hlock,
1998 u64 chain_key)
1999{
2000 struct lock_class *class = hlock_class(hlock);
2001 struct list_head *hash_head = chainhashentry(chain_key);
2002 struct lock_chain *chain;
2003 struct held_lock *hlock_curr, *hlock_next;
2004 int i, j;
2005
2006 /*
2007 * We might need to take the graph lock, ensure we've got IRQs
2008 * disabled to make this an IRQ-safe lock.. for recursion reasons
2009 * lockdep won't complain about its own locking errors.
2010 */
2011 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2012 return 0;
2013 /*
2014 * We can walk it lock-free, because entries only get added
2015 * to the hash:
2016 */
2017 list_for_each_entry(chain, hash_head, entry) {
2018 if (chain->chain_key == chain_key) {
2019cache_hit:
2020 debug_atomic_inc(chain_lookup_hits);
2021 if (very_verbose(class))
2022 printk("\nhash chain already cached, key: "
2023 "%016Lx tail class: [%p] %s\n",
2024 (unsigned long long)chain_key,
2025 class->key, class->name);
2026 return 0;
2027 }
2028 }
2029 if (very_verbose(class))
2030 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2031 (unsigned long long)chain_key, class->key, class->name);
2032 /*
2033 * Allocate a new chain entry from the static array, and add
2034 * it to the hash:
2035 */
2036 if (!graph_lock())
2037 return 0;
2038 /*
2039 * We have to walk the chain again locked - to avoid duplicates:
2040 */
2041 list_for_each_entry(chain, hash_head, entry) {
2042 if (chain->chain_key == chain_key) {
2043 graph_unlock();
2044 goto cache_hit;
2045 }
2046 }
2047 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2048 if (!debug_locks_off_graph_unlock())
2049 return 0;
2050
2051 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2052 printk("turning off the locking correctness validator.\n");
2053 dump_stack();
2054 return 0;
2055 }
2056 chain = lock_chains + nr_lock_chains++;
2057 chain->chain_key = chain_key;
2058 chain->irq_context = hlock->irq_context;
2059 /* Find the first held_lock of current chain */
2060 hlock_next = hlock;
2061 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2062 hlock_curr = curr->held_locks + i;
2063 if (hlock_curr->irq_context != hlock_next->irq_context)
2064 break;
2065 hlock_next = hlock;
2066 }
2067 i++;
2068 chain->depth = curr->lockdep_depth + 1 - i;
2069 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2070 chain->base = nr_chain_hlocks;
2071 nr_chain_hlocks += chain->depth;
2072 for (j = 0; j < chain->depth - 1; j++, i++) {
2073 int lock_id = curr->held_locks[i].class_idx - 1;
2074 chain_hlocks[chain->base + j] = lock_id;
2075 }
2076 chain_hlocks[chain->base + j] = class - lock_classes;
2077 }
2078 list_add_tail_rcu(&chain->entry, hash_head);
2079 debug_atomic_inc(chain_lookup_misses);
2080 inc_chains();
2081
2082 return 1;
2083}
2084
2085static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2086 struct held_lock *hlock, int chain_head, u64 chain_key)
2087{
2088 /*
2089 * Trylock needs to maintain the stack of held locks, but it
2090 * does not add new dependencies, because trylock can be done
2091 * in any order.
2092 *
2093 * We look up the chain_key and do the O(N^2) check and update of
2094 * the dependencies only if this is a new dependency chain.
2095 * (If lookup_chain_cache() returns with 1 it acquires
2096 * graph_lock for us)
2097 */
2098 if (!hlock->trylock && (hlock->check == 2) &&
2099 lookup_chain_cache(curr, hlock, chain_key)) {
2100 /*
2101 * Check whether last held lock:
2102 *
2103 * - is irq-safe, if this lock is irq-unsafe
2104 * - is softirq-safe, if this lock is hardirq-unsafe
2105 *
2106 * And check whether the new lock's dependency graph
2107 * could lead back to the previous lock.
2108 *
2109 * any of these scenarios could lead to a deadlock. If
2110 * All validations
2111 */
2112 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2113
2114 if (!ret)
2115 return 0;
2116 /*
2117 * Mark recursive read, as we jump over it when
2118 * building dependencies (just like we jump over
2119 * trylock entries):
2120 */
2121 if (ret == 2)
2122 hlock->read = 2;
2123 /*
2124 * Add dependency only if this lock is not the head
2125 * of the chain, and if it's not a secondary read-lock:
2126 */
2127 if (!chain_head && ret != 2)
2128 if (!check_prevs_add(curr, hlock))
2129 return 0;
2130 graph_unlock();
2131 } else
2132 /* after lookup_chain_cache(): */
2133 if (unlikely(!debug_locks))
2134 return 0;
2135
2136 return 1;
2137}
2138#else
2139static inline int validate_chain(struct task_struct *curr,
2140 struct lockdep_map *lock, struct held_lock *hlock,
2141 int chain_head, u64 chain_key)
2142{
2143 return 1;
2144}
2145#endif
2146
2147/*
2148 * We are building curr_chain_key incrementally, so double-check
2149 * it from scratch, to make sure that it's done correctly:
2150 */
2151static void check_chain_key(struct task_struct *curr)
2152{
2153#ifdef CONFIG_DEBUG_LOCKDEP
2154 struct held_lock *hlock, *prev_hlock = NULL;
2155 unsigned int i, id;
2156 u64 chain_key = 0;
2157
2158 for (i = 0; i < curr->lockdep_depth; i++) {
2159 hlock = curr->held_locks + i;
2160 if (chain_key != hlock->prev_chain_key) {
2161 debug_locks_off();
2162 /*
2163 * We got mighty confused, our chain keys don't match
2164 * with what we expect, someone trample on our task state?
2165 */
2166 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
2167 curr->lockdep_depth, i,
2168 (unsigned long long)chain_key,
2169 (unsigned long long)hlock->prev_chain_key);
2170 return;
2171 }
2172 id = hlock->class_idx - 1;
2173 /*
2174 * Whoops ran out of static storage again?
2175 */
2176 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2177 return;
2178
2179 if (prev_hlock && (prev_hlock->irq_context !=
2180 hlock->irq_context))
2181 chain_key = 0;
2182 chain_key = iterate_chain_key(chain_key, id);
2183 prev_hlock = hlock;
2184 }
2185 if (chain_key != curr->curr_chain_key) {
2186 debug_locks_off();
2187 /*
2188 * More smoking hash instead of calculating it, damn see these
2189 * numbers float.. I bet that a pink elephant stepped on my memory.
2190 */
2191 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
2192 curr->lockdep_depth, i,
2193 (unsigned long long)chain_key,
2194 (unsigned long long)curr->curr_chain_key);
2195 }
2196#endif
2197}
2198
2199static void
2200print_usage_bug_scenario(struct held_lock *lock)
2201{
2202 struct lock_class *class = hlock_class(lock);
2203
2204 printk(" Possible unsafe locking scenario:\n\n");
2205 printk(" CPU0\n");
2206 printk(" ----\n");
2207 printk(" lock(");
2208 __print_lock_name(class);
2209 printk(");\n");
2210 printk(" <Interrupt>\n");
2211 printk(" lock(");
2212 __print_lock_name(class);
2213 printk(");\n");
2214 printk("\n *** DEADLOCK ***\n\n");
2215}
2216
2217static int
2218print_usage_bug(struct task_struct *curr, struct held_lock *this,
2219 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2220{
2221 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2222 return 0;
2223
2224 printk("\n");
2225 printk("=================================\n");
2226 printk("[ INFO: inconsistent lock state ]\n");
2227 print_kernel_ident();
2228 printk("---------------------------------\n");
2229
2230 printk("inconsistent {%s} -> {%s} usage.\n",
2231 usage_str[prev_bit], usage_str[new_bit]);
2232
2233 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2234 curr->comm, task_pid_nr(curr),
2235 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2236 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2237 trace_hardirqs_enabled(curr),
2238 trace_softirqs_enabled(curr));
2239 print_lock(this);
2240
2241 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2242 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2243
2244 print_irqtrace_events(curr);
2245 printk("\nother info that might help us debug this:\n");
2246 print_usage_bug_scenario(this);
2247
2248 lockdep_print_held_locks(curr);
2249
2250 printk("\nstack backtrace:\n");
2251 dump_stack();
2252
2253 return 0;
2254}
2255
2256/*
2257 * Print out an error if an invalid bit is set:
2258 */
2259static inline int
2260valid_state(struct task_struct *curr, struct held_lock *this,
2261 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2262{
2263 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2264 return print_usage_bug(curr, this, bad_bit, new_bit);
2265 return 1;
2266}
2267
2268static int mark_lock(struct task_struct *curr, struct held_lock *this,
2269 enum lock_usage_bit new_bit);
2270
2271#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2272
2273/*
2274 * print irq inversion bug:
2275 */
2276static int
2277print_irq_inversion_bug(struct task_struct *curr,
2278 struct lock_list *root, struct lock_list *other,
2279 struct held_lock *this, int forwards,
2280 const char *irqclass)
2281{
2282 struct lock_list *entry = other;
2283 struct lock_list *middle = NULL;
2284 int depth;
2285
2286 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2287 return 0;
2288
2289 printk("\n");
2290 printk("=========================================================\n");
2291 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2292 print_kernel_ident();
2293 printk("---------------------------------------------------------\n");
2294 printk("%s/%d just changed the state of lock:\n",
2295 curr->comm, task_pid_nr(curr));
2296 print_lock(this);
2297 if (forwards)
2298 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2299 else
2300 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2301 print_lock_name(other->class);
2302 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2303
2304 printk("\nother info that might help us debug this:\n");
2305
2306 /* Find a middle lock (if one exists) */
2307 depth = get_lock_depth(other);
2308 do {
2309 if (depth == 0 && (entry != root)) {
2310 printk("lockdep:%s bad path found in chain graph\n", __func__);
2311 break;
2312 }
2313 middle = entry;
2314 entry = get_lock_parent(entry);
2315 depth--;
2316 } while (entry && entry != root && (depth >= 0));
2317 if (forwards)
2318 print_irq_lock_scenario(root, other,
2319 middle ? middle->class : root->class, other->class);
2320 else
2321 print_irq_lock_scenario(other, root,
2322 middle ? middle->class : other->class, root->class);
2323
2324 lockdep_print_held_locks(curr);
2325
2326 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2327 if (!save_trace(&root->trace))
2328 return 0;
2329 print_shortest_lock_dependencies(other, root);
2330
2331 printk("\nstack backtrace:\n");
2332 dump_stack();
2333
2334 return 0;
2335}
2336
2337/*
2338 * Prove that in the forwards-direction subgraph starting at <this>
2339 * there is no lock matching <mask>:
2340 */
2341static int
2342check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2343 enum lock_usage_bit bit, const char *irqclass)
2344{
2345 int ret;
2346 struct lock_list root;
2347 struct lock_list *uninitialized_var(target_entry);
2348
2349 root.parent = NULL;
2350 root.class = hlock_class(this);
2351 ret = find_usage_forwards(&root, bit, &target_entry);
2352 if (ret < 0)
2353 return print_bfs_bug(ret);
2354 if (ret == 1)
2355 return ret;
2356
2357 return print_irq_inversion_bug(curr, &root, target_entry,
2358 this, 1, irqclass);
2359}
2360
2361/*
2362 * Prove that in the backwards-direction subgraph starting at <this>
2363 * there is no lock matching <mask>:
2364 */
2365static int
2366check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2367 enum lock_usage_bit bit, const char *irqclass)
2368{
2369 int ret;
2370 struct lock_list root;
2371 struct lock_list *uninitialized_var(target_entry);
2372
2373 root.parent = NULL;
2374 root.class = hlock_class(this);
2375 ret = find_usage_backwards(&root, bit, &target_entry);
2376 if (ret < 0)
2377 return print_bfs_bug(ret);
2378 if (ret == 1)
2379 return ret;
2380
2381 return print_irq_inversion_bug(curr, &root, target_entry,
2382 this, 0, irqclass);
2383}
2384
2385void print_irqtrace_events(struct task_struct *curr)
2386{
2387 printk("irq event stamp: %u\n", curr->irq_events);
2388 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2389 print_ip_sym(curr->hardirq_enable_ip);
2390 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2391 print_ip_sym(curr->hardirq_disable_ip);
2392 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2393 print_ip_sym(curr->softirq_enable_ip);
2394 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2395 print_ip_sym(curr->softirq_disable_ip);
2396}
2397
2398static int HARDIRQ_verbose(struct lock_class *class)
2399{
2400#if HARDIRQ_VERBOSE
2401 return class_filter(class);
2402#endif
2403 return 0;
2404}
2405
2406static int SOFTIRQ_verbose(struct lock_class *class)
2407{
2408#if SOFTIRQ_VERBOSE
2409 return class_filter(class);
2410#endif
2411 return 0;
2412}
2413
2414static int RECLAIM_FS_verbose(struct lock_class *class)
2415{
2416#if RECLAIM_VERBOSE
2417 return class_filter(class);
2418#endif
2419 return 0;
2420}
2421
2422#define STRICT_READ_CHECKS 1
2423
2424static int (*state_verbose_f[])(struct lock_class *class) = {
2425#define LOCKDEP_STATE(__STATE) \
2426 __STATE##_verbose,
2427#include "lockdep_states.h"
2428#undef LOCKDEP_STATE
2429};
2430
2431static inline int state_verbose(enum lock_usage_bit bit,
2432 struct lock_class *class)
2433{
2434 return state_verbose_f[bit >> 2](class);
2435}
2436
2437typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2438 enum lock_usage_bit bit, const char *name);
2439
2440static int
2441mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2442 enum lock_usage_bit new_bit)
2443{
2444 int excl_bit = exclusive_bit(new_bit);
2445 int read = new_bit & 1;
2446 int dir = new_bit & 2;
2447
2448 /*
2449 * mark USED_IN has to look forwards -- to ensure no dependency
2450 * has ENABLED state, which would allow recursion deadlocks.
2451 *
2452 * mark ENABLED has to look backwards -- to ensure no dependee
2453 * has USED_IN state, which, again, would allow recursion deadlocks.
2454 */
2455 check_usage_f usage = dir ?
2456 check_usage_backwards : check_usage_forwards;
2457
2458 /*
2459 * Validate that this particular lock does not have conflicting
2460 * usage states.
2461 */
2462 if (!valid_state(curr, this, new_bit, excl_bit))
2463 return 0;
2464
2465 /*
2466 * Validate that the lock dependencies don't have conflicting usage
2467 * states.
2468 */
2469 if ((!read || !dir || STRICT_READ_CHECKS) &&
2470 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2471 return 0;
2472
2473 /*
2474 * Check for read in write conflicts
2475 */
2476 if (!read) {
2477 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2478 return 0;
2479
2480 if (STRICT_READ_CHECKS &&
2481 !usage(curr, this, excl_bit + 1,
2482 state_name(new_bit + 1)))
2483 return 0;
2484 }
2485
2486 if (state_verbose(new_bit, hlock_class(this)))
2487 return 2;
2488
2489 return 1;
2490}
2491
2492enum mark_type {
2493#define LOCKDEP_STATE(__STATE) __STATE,
2494#include "lockdep_states.h"
2495#undef LOCKDEP_STATE
2496};
2497
2498/*
2499 * Mark all held locks with a usage bit:
2500 */
2501static int
2502mark_held_locks(struct task_struct *curr, enum mark_type mark)
2503{
2504 enum lock_usage_bit usage_bit;
2505 struct held_lock *hlock;
2506 int i;
2507
2508 for (i = 0; i < curr->lockdep_depth; i++) {
2509 hlock = curr->held_locks + i;
2510
2511 usage_bit = 2 + (mark << 2); /* ENABLED */
2512 if (hlock->read)
2513 usage_bit += 1; /* READ */
2514
2515 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2516
2517 if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
2518 continue;
2519
2520 if (!mark_lock(curr, hlock, usage_bit))
2521 return 0;
2522 }
2523
2524 return 1;
2525}
2526
2527/*
2528 * Hardirqs will be enabled:
2529 */
2530static void __trace_hardirqs_on_caller(unsigned long ip)
2531{
2532 struct task_struct *curr = current;
2533
2534 /* we'll do an OFF -> ON transition: */
2535 curr->hardirqs_enabled = 1;
2536
2537 /*
2538 * We are going to turn hardirqs on, so set the
2539 * usage bit for all held locks:
2540 */
2541 if (!mark_held_locks(curr, HARDIRQ))
2542 return;
2543 /*
2544 * If we have softirqs enabled, then set the usage
2545 * bit for all held locks. (disabled hardirqs prevented
2546 * this bit from being set before)
2547 */
2548 if (curr->softirqs_enabled)
2549 if (!mark_held_locks(curr, SOFTIRQ))
2550 return;
2551
2552 curr->hardirq_enable_ip = ip;
2553 curr->hardirq_enable_event = ++curr->irq_events;
2554 debug_atomic_inc(hardirqs_on_events);
2555}
2556
2557void trace_hardirqs_on_caller(unsigned long ip)
2558{
2559 time_hardirqs_on(CALLER_ADDR0, ip);
2560
2561 if (unlikely(!debug_locks || current->lockdep_recursion))
2562 return;
2563
2564 if (unlikely(current->hardirqs_enabled)) {
2565 /*
2566 * Neither irq nor preemption are disabled here
2567 * so this is racy by nature but losing one hit
2568 * in a stat is not a big deal.
2569 */
2570 __debug_atomic_inc(redundant_hardirqs_on);
2571 return;
2572 }
2573
2574 /*
2575 * We're enabling irqs and according to our state above irqs weren't
2576 * already enabled, yet we find the hardware thinks they are in fact
2577 * enabled.. someone messed up their IRQ state tracing.
2578 */
2579 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2580 return;
2581
2582 /*
2583 * See the fine text that goes along with this variable definition.
2584 */
2585 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2586 return;
2587
2588 /*
2589 * Can't allow enabling interrupts while in an interrupt handler,
2590 * that's general bad form and such. Recursion, limited stack etc..
2591 */
2592 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2593 return;
2594
2595 current->lockdep_recursion = 1;
2596 __trace_hardirqs_on_caller(ip);
2597 current->lockdep_recursion = 0;
2598}
2599EXPORT_SYMBOL(trace_hardirqs_on_caller);
2600
2601void trace_hardirqs_on(void)
2602{
2603 trace_hardirqs_on_caller(CALLER_ADDR0);
2604}
2605EXPORT_SYMBOL(trace_hardirqs_on);
2606
2607/*
2608 * Hardirqs were disabled:
2609 */
2610void trace_hardirqs_off_caller(unsigned long ip)
2611{
2612 struct task_struct *curr = current;
2613
2614 time_hardirqs_off(CALLER_ADDR0, ip);
2615
2616 if (unlikely(!debug_locks || current->lockdep_recursion))
2617 return;
2618
2619 /*
2620 * So we're supposed to get called after you mask local IRQs, but for
2621 * some reason the hardware doesn't quite think you did a proper job.
2622 */
2623 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2624 return;
2625
2626 if (curr->hardirqs_enabled) {
2627 /*
2628 * We have done an ON -> OFF transition:
2629 */
2630 curr->hardirqs_enabled = 0;
2631 curr->hardirq_disable_ip = ip;
2632 curr->hardirq_disable_event = ++curr->irq_events;
2633 debug_atomic_inc(hardirqs_off_events);
2634 } else
2635 debug_atomic_inc(redundant_hardirqs_off);
2636}
2637EXPORT_SYMBOL(trace_hardirqs_off_caller);
2638
2639void trace_hardirqs_off(void)
2640{
2641 trace_hardirqs_off_caller(CALLER_ADDR0);
2642}
2643EXPORT_SYMBOL(trace_hardirqs_off);
2644
2645/*
2646 * Softirqs will be enabled:
2647 */
2648void trace_softirqs_on(unsigned long ip)
2649{
2650 struct task_struct *curr = current;
2651
2652 if (unlikely(!debug_locks || current->lockdep_recursion))
2653 return;
2654
2655 /*
2656 * We fancy IRQs being disabled here, see softirq.c, avoids
2657 * funny state and nesting things.
2658 */
2659 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2660 return;
2661
2662 if (curr->softirqs_enabled) {
2663 debug_atomic_inc(redundant_softirqs_on);
2664 return;
2665 }
2666
2667 current->lockdep_recursion = 1;
2668 /*
2669 * We'll do an OFF -> ON transition:
2670 */
2671 curr->softirqs_enabled = 1;
2672 curr->softirq_enable_ip = ip;
2673 curr->softirq_enable_event = ++curr->irq_events;
2674 debug_atomic_inc(softirqs_on_events);
2675 /*
2676 * We are going to turn softirqs on, so set the
2677 * usage bit for all held locks, if hardirqs are
2678 * enabled too:
2679 */
2680 if (curr->hardirqs_enabled)
2681 mark_held_locks(curr, SOFTIRQ);
2682 current->lockdep_recursion = 0;
2683}
2684
2685/*
2686 * Softirqs were disabled:
2687 */
2688void trace_softirqs_off(unsigned long ip)
2689{
2690 struct task_struct *curr = current;
2691
2692 if (unlikely(!debug_locks || current->lockdep_recursion))
2693 return;
2694
2695 /*
2696 * We fancy IRQs being disabled here, see softirq.c
2697 */
2698 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2699 return;
2700
2701 if (curr->softirqs_enabled) {
2702 /*
2703 * We have done an ON -> OFF transition:
2704 */
2705 curr->softirqs_enabled = 0;
2706 curr->softirq_disable_ip = ip;
2707 curr->softirq_disable_event = ++curr->irq_events;
2708 debug_atomic_inc(softirqs_off_events);
2709 /*
2710 * Whoops, we wanted softirqs off, so why aren't they?
2711 */
2712 DEBUG_LOCKS_WARN_ON(!softirq_count());
2713 } else
2714 debug_atomic_inc(redundant_softirqs_off);
2715}
2716
2717static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2718{
2719 struct task_struct *curr = current;
2720
2721 if (unlikely(!debug_locks))
2722 return;
2723
2724 /* no reclaim without waiting on it */
2725 if (!(gfp_mask & __GFP_WAIT))
2726 return;
2727
2728 /* this guy won't enter reclaim */
2729 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2730 return;
2731
2732 /* We're only interested __GFP_FS allocations for now */
2733 if (!(gfp_mask & __GFP_FS))
2734 return;
2735
2736 /*
2737 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2738 */
2739 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2740 return;
2741
2742 mark_held_locks(curr, RECLAIM_FS);
2743}
2744
2745static void check_flags(unsigned long flags);
2746
2747void lockdep_trace_alloc(gfp_t gfp_mask)
2748{
2749 unsigned long flags;
2750
2751 if (unlikely(current->lockdep_recursion))
2752 return;
2753
2754 raw_local_irq_save(flags);
2755 check_flags(flags);
2756 current->lockdep_recursion = 1;
2757 __lockdep_trace_alloc(gfp_mask, flags);
2758 current->lockdep_recursion = 0;
2759 raw_local_irq_restore(flags);
2760}
2761
2762static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2763{
2764 /*
2765 * If non-trylock use in a hardirq or softirq context, then
2766 * mark the lock as used in these contexts:
2767 */
2768 if (!hlock->trylock) {
2769 if (hlock->read) {
2770 if (curr->hardirq_context)
2771 if (!mark_lock(curr, hlock,
2772 LOCK_USED_IN_HARDIRQ_READ))
2773 return 0;
2774 if (curr->softirq_context)
2775 if (!mark_lock(curr, hlock,
2776 LOCK_USED_IN_SOFTIRQ_READ))
2777 return 0;
2778 } else {
2779 if (curr->hardirq_context)
2780 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2781 return 0;
2782 if (curr->softirq_context)
2783 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2784 return 0;
2785 }
2786 }
2787 if (!hlock->hardirqs_off) {
2788 if (hlock->read) {
2789 if (!mark_lock(curr, hlock,
2790 LOCK_ENABLED_HARDIRQ_READ))
2791 return 0;
2792 if (curr->softirqs_enabled)
2793 if (!mark_lock(curr, hlock,
2794 LOCK_ENABLED_SOFTIRQ_READ))
2795 return 0;
2796 } else {
2797 if (!mark_lock(curr, hlock,
2798 LOCK_ENABLED_HARDIRQ))
2799 return 0;
2800 if (curr->softirqs_enabled)
2801 if (!mark_lock(curr, hlock,
2802 LOCK_ENABLED_SOFTIRQ))
2803 return 0;
2804 }
2805 }
2806
2807 /*
2808 * We reuse the irq context infrastructure more broadly as a general
2809 * context checking code. This tests GFP_FS recursion (a lock taken
2810 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2811 * allocation).
2812 */
2813 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2814 if (hlock->read) {
2815 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2816 return 0;
2817 } else {
2818 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2819 return 0;
2820 }
2821 }
2822
2823 return 1;
2824}
2825
2826static int separate_irq_context(struct task_struct *curr,
2827 struct held_lock *hlock)
2828{
2829 unsigned int depth = curr->lockdep_depth;
2830
2831 /*
2832 * Keep track of points where we cross into an interrupt context:
2833 */
2834 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2835 curr->softirq_context;
2836 if (depth) {
2837 struct held_lock *prev_hlock;
2838
2839 prev_hlock = curr->held_locks + depth-1;
2840 /*
2841 * If we cross into another context, reset the
2842 * hash key (this also prevents the checking and the
2843 * adding of the dependency to 'prev'):
2844 */
2845 if (prev_hlock->irq_context != hlock->irq_context)
2846 return 1;
2847 }
2848 return 0;
2849}
2850
2851#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2852
2853static inline
2854int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2855 enum lock_usage_bit new_bit)
2856{
2857 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
2858 return 1;
2859}
2860
2861static inline int mark_irqflags(struct task_struct *curr,
2862 struct held_lock *hlock)
2863{
2864 return 1;
2865}
2866
2867static inline int separate_irq_context(struct task_struct *curr,
2868 struct held_lock *hlock)
2869{
2870 return 0;
2871}
2872
2873void lockdep_trace_alloc(gfp_t gfp_mask)
2874{
2875}
2876
2877#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
2878
2879/*
2880 * Mark a lock with a usage bit, and validate the state transition:
2881 */
2882static int mark_lock(struct task_struct *curr, struct held_lock *this,
2883 enum lock_usage_bit new_bit)
2884{
2885 unsigned int new_mask = 1 << new_bit, ret = 1;
2886
2887 /*
2888 * If already set then do not dirty the cacheline,
2889 * nor do any checks:
2890 */
2891 if (likely(hlock_class(this)->usage_mask & new_mask))
2892 return 1;
2893
2894 if (!graph_lock())
2895 return 0;
2896 /*
2897 * Make sure we didn't race:
2898 */
2899 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2900 graph_unlock();
2901 return 1;
2902 }
2903
2904 hlock_class(this)->usage_mask |= new_mask;
2905
2906 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2907 return 0;
2908
2909 switch (new_bit) {
2910#define LOCKDEP_STATE(__STATE) \
2911 case LOCK_USED_IN_##__STATE: \
2912 case LOCK_USED_IN_##__STATE##_READ: \
2913 case LOCK_ENABLED_##__STATE: \
2914 case LOCK_ENABLED_##__STATE##_READ:
2915#include "lockdep_states.h"
2916#undef LOCKDEP_STATE
2917 ret = mark_lock_irq(curr, this, new_bit);
2918 if (!ret)
2919 return 0;
2920 break;
2921 case LOCK_USED:
2922 debug_atomic_dec(nr_unused_locks);
2923 break;
2924 default:
2925 if (!debug_locks_off_graph_unlock())
2926 return 0;
2927 WARN_ON(1);
2928 return 0;
2929 }
2930
2931 graph_unlock();
2932
2933 /*
2934 * We must printk outside of the graph_lock:
2935 */
2936 if (ret == 2) {
2937 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2938 print_lock(this);
2939 print_irqtrace_events(curr);
2940 dump_stack();
2941 }
2942
2943 return ret;
2944}
2945
2946/*
2947 * Initialize a lock instance's lock-class mapping info:
2948 */
2949void lockdep_init_map(struct lockdep_map *lock, const char *name,
2950 struct lock_class_key *key, int subclass)
2951{
2952 int i;
2953
2954 kmemcheck_mark_initialized(lock, sizeof(*lock));
2955
2956 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2957 lock->class_cache[i] = NULL;
2958
2959#ifdef CONFIG_LOCK_STAT
2960 lock->cpu = raw_smp_processor_id();
2961#endif
2962
2963 /*
2964 * Can't be having no nameless bastards around this place!
2965 */
2966 if (DEBUG_LOCKS_WARN_ON(!name)) {
2967 lock->name = "NULL";
2968 return;
2969 }
2970
2971 lock->name = name;
2972
2973 /*
2974 * No key, no joy, we need to hash something.
2975 */
2976 if (DEBUG_LOCKS_WARN_ON(!key))
2977 return;
2978 /*
2979 * Sanity check, the lock-class key must be persistent:
2980 */
2981 if (!static_obj(key)) {
2982 printk("BUG: key %p not in .data!\n", key);
2983 /*
2984 * What it says above ^^^^^, I suggest you read it.
2985 */
2986 DEBUG_LOCKS_WARN_ON(1);
2987 return;
2988 }
2989 lock->key = key;
2990
2991 if (unlikely(!debug_locks))
2992 return;
2993
2994 if (subclass)
2995 register_lock_class(lock, subclass, 1);
2996}
2997EXPORT_SYMBOL_GPL(lockdep_init_map);
2998
2999struct lock_class_key __lockdep_no_validate__;
3000
3001/*
3002 * This gets called for every mutex_lock*()/spin_lock*() operation.
3003 * We maintain the dependency maps and validate the locking attempt:
3004 */
3005static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3006 int trylock, int read, int check, int hardirqs_off,
3007 struct lockdep_map *nest_lock, unsigned long ip,
3008 int references)
3009{
3010 struct task_struct *curr = current;
3011 struct lock_class *class = NULL;
3012 struct held_lock *hlock;
3013 unsigned int depth, id;
3014 int chain_head = 0;
3015 int class_idx;
3016 u64 chain_key;
3017
3018 if (!prove_locking)
3019 check = 1;
3020
3021 if (unlikely(!debug_locks))
3022 return 0;
3023
3024 /*
3025 * Lockdep should run with IRQs disabled, otherwise we could
3026 * get an interrupt which would want to take locks, which would
3027 * end up in lockdep and have you got a head-ache already?
3028 */
3029 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3030 return 0;
3031
3032 if (lock->key == &__lockdep_no_validate__)
3033 check = 1;
3034
3035 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3036 class = lock->class_cache[subclass];
3037 /*
3038 * Not cached?
3039 */
3040 if (unlikely(!class)) {
3041 class = register_lock_class(lock, subclass, 0);
3042 if (!class)
3043 return 0;
3044 }
3045 atomic_inc((atomic_t *)&class->ops);
3046 if (very_verbose(class)) {
3047 printk("\nacquire class [%p] %s", class->key, class->name);
3048 if (class->name_version > 1)
3049 printk("#%d", class->name_version);
3050 printk("\n");
3051 dump_stack();
3052 }
3053
3054 /*
3055 * Add the lock to the list of currently held locks.
3056 * (we dont increase the depth just yet, up until the
3057 * dependency checks are done)
3058 */
3059 depth = curr->lockdep_depth;
3060 /*
3061 * Ran out of static storage for our per-task lock stack again have we?
3062 */
3063 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3064 return 0;
3065
3066 class_idx = class - lock_classes + 1;
3067
3068 if (depth) {
3069 hlock = curr->held_locks + depth - 1;
3070 if (hlock->class_idx == class_idx && nest_lock) {
3071 if (hlock->references)
3072 hlock->references++;
3073 else
3074 hlock->references = 2;
3075
3076 return 1;
3077 }
3078 }
3079
3080 hlock = curr->held_locks + depth;
3081 /*
3082 * Plain impossible, we just registered it and checked it weren't no
3083 * NULL like.. I bet this mushroom I ate was good!
3084 */
3085 if (DEBUG_LOCKS_WARN_ON(!class))
3086 return 0;
3087 hlock->class_idx = class_idx;
3088 hlock->acquire_ip = ip;
3089 hlock->instance = lock;
3090 hlock->nest_lock = nest_lock;
3091 hlock->trylock = trylock;
3092 hlock->read = read;
3093 hlock->check = check;
3094 hlock->hardirqs_off = !!hardirqs_off;
3095 hlock->references = references;
3096#ifdef CONFIG_LOCK_STAT
3097 hlock->waittime_stamp = 0;
3098 hlock->holdtime_stamp = lockstat_clock();
3099#endif
3100
3101 if (check == 2 && !mark_irqflags(curr, hlock))
3102 return 0;
3103
3104 /* mark it as used: */
3105 if (!mark_lock(curr, hlock, LOCK_USED))
3106 return 0;
3107
3108 /*
3109 * Calculate the chain hash: it's the combined hash of all the
3110 * lock keys along the dependency chain. We save the hash value
3111 * at every step so that we can get the current hash easily
3112 * after unlock. The chain hash is then used to cache dependency
3113 * results.
3114 *
3115 * The 'key ID' is what is the most compact key value to drive
3116 * the hash, not class->key.
3117 */
3118 id = class - lock_classes;
3119 /*
3120 * Whoops, we did it again.. ran straight out of our static allocation.
3121 */
3122 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3123 return 0;
3124
3125 chain_key = curr->curr_chain_key;
3126 if (!depth) {
3127 /*
3128 * How can we have a chain hash when we ain't got no keys?!
3129 */
3130 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3131 return 0;
3132 chain_head = 1;
3133 }
3134
3135 hlock->prev_chain_key = chain_key;
3136 if (separate_irq_context(curr, hlock)) {
3137 chain_key = 0;
3138 chain_head = 1;
3139 }
3140 chain_key = iterate_chain_key(chain_key, id);
3141
3142 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
3143 return 0;
3144
3145 curr->curr_chain_key = chain_key;
3146 curr->lockdep_depth++;
3147 check_chain_key(curr);
3148#ifdef CONFIG_DEBUG_LOCKDEP
3149 if (unlikely(!debug_locks))
3150 return 0;
3151#endif
3152 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3153 debug_locks_off();
3154 printk("BUG: MAX_LOCK_DEPTH too low!\n");
3155 printk("turning off the locking correctness validator.\n");
3156 dump_stack();
3157 return 0;
3158 }
3159
3160 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3161 max_lockdep_depth = curr->lockdep_depth;
3162
3163 return 1;
3164}
3165
3166static int
3167print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3168 unsigned long ip)
3169{
3170 if (!debug_locks_off())
3171 return 0;
3172 if (debug_locks_silent)
3173 return 0;
3174
3175 printk("\n");
3176 printk("=====================================\n");
3177 printk("[ BUG: bad unlock balance detected! ]\n");
3178 print_kernel_ident();
3179 printk("-------------------------------------\n");
3180 printk("%s/%d is trying to release lock (",
3181 curr->comm, task_pid_nr(curr));
3182 print_lockdep_cache(lock);
3183 printk(") at:\n");
3184 print_ip_sym(ip);
3185 printk("but there are no more locks to release!\n");
3186 printk("\nother info that might help us debug this:\n");
3187 lockdep_print_held_locks(curr);
3188
3189 printk("\nstack backtrace:\n");
3190 dump_stack();
3191
3192 return 0;
3193}
3194
3195/*
3196 * Common debugging checks for both nested and non-nested unlock:
3197 */
3198static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3199 unsigned long ip)
3200{
3201 if (unlikely(!debug_locks))
3202 return 0;
3203 /*
3204 * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
3205 */
3206 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3207 return 0;
3208
3209 if (curr->lockdep_depth <= 0)
3210 return print_unlock_inbalance_bug(curr, lock, ip);
3211
3212 return 1;
3213}
3214
3215static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3216{
3217 if (hlock->instance == lock)
3218 return 1;
3219
3220 if (hlock->references) {
3221 struct lock_class *class = lock->class_cache[0];
3222
3223 if (!class)
3224 class = look_up_lock_class(lock, 0);
3225
3226 /*
3227 * If look_up_lock_class() failed to find a class, we're trying
3228 * to test if we hold a lock that has never yet been acquired.
3229 * Clearly if the lock hasn't been acquired _ever_, we're not
3230 * holding it either, so report failure.
3231 */
3232 if (!class)
3233 return 0;
3234
3235 /*
3236 * References, but not a lock we're actually ref-counting?
3237 * State got messed up, follow the sites that change ->references
3238 * and try to make sense of it.
3239 */
3240 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3241 return 0;
3242
3243 if (hlock->class_idx == class - lock_classes + 1)
3244 return 1;
3245 }
3246
3247 return 0;
3248}
3249
3250static int
3251__lock_set_class(struct lockdep_map *lock, const char *name,
3252 struct lock_class_key *key, unsigned int subclass,
3253 unsigned long ip)
3254{
3255 struct task_struct *curr = current;
3256 struct held_lock *hlock, *prev_hlock;
3257 struct lock_class *class;
3258 unsigned int depth;
3259 int i;
3260
3261 depth = curr->lockdep_depth;
3262 /*
3263 * This function is about (re)setting the class of a held lock,
3264 * yet we're not actually holding any locks. Naughty user!
3265 */
3266 if (DEBUG_LOCKS_WARN_ON(!depth))
3267 return 0;
3268
3269 prev_hlock = NULL;
3270 for (i = depth-1; i >= 0; i--) {
3271 hlock = curr->held_locks + i;
3272 /*
3273 * We must not cross into another context:
3274 */
3275 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3276 break;
3277 if (match_held_lock(hlock, lock))
3278 goto found_it;
3279 prev_hlock = hlock;
3280 }
3281 return print_unlock_inbalance_bug(curr, lock, ip);
3282
3283found_it:
3284 lockdep_init_map(lock, name, key, 0);
3285 class = register_lock_class(lock, subclass, 0);
3286 hlock->class_idx = class - lock_classes + 1;
3287
3288 curr->lockdep_depth = i;
3289 curr->curr_chain_key = hlock->prev_chain_key;
3290
3291 for (; i < depth; i++) {
3292 hlock = curr->held_locks + i;
3293 if (!__lock_acquire(hlock->instance,
3294 hlock_class(hlock)->subclass, hlock->trylock,
3295 hlock->read, hlock->check, hlock->hardirqs_off,
3296 hlock->nest_lock, hlock->acquire_ip,
3297 hlock->references))
3298 return 0;
3299 }
3300
3301 /*
3302 * I took it apart and put it back together again, except now I have
3303 * these 'spare' parts.. where shall I put them.
3304 */
3305 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3306 return 0;
3307 return 1;
3308}
3309
3310/*
3311 * Remove the lock to the list of currently held locks in a
3312 * potentially non-nested (out of order) manner. This is a
3313 * relatively rare operation, as all the unlock APIs default
3314 * to nested mode (which uses lock_release()):
3315 */
3316static int
3317lock_release_non_nested(struct task_struct *curr,
3318 struct lockdep_map *lock, unsigned long ip)
3319{
3320 struct held_lock *hlock, *prev_hlock;
3321 unsigned int depth;
3322 int i;
3323
3324 /*
3325 * Check whether the lock exists in the current stack
3326 * of held locks:
3327 */
3328 depth = curr->lockdep_depth;
3329 /*
3330 * So we're all set to release this lock.. wait what lock? We don't
3331 * own any locks, you've been drinking again?
3332 */
3333 if (DEBUG_LOCKS_WARN_ON(!depth))
3334 return 0;
3335
3336 prev_hlock = NULL;
3337 for (i = depth-1; i >= 0; i--) {
3338 hlock = curr->held_locks + i;
3339 /*
3340 * We must not cross into another context:
3341 */
3342 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3343 break;
3344 if (match_held_lock(hlock, lock))
3345 goto found_it;
3346 prev_hlock = hlock;
3347 }
3348 return print_unlock_inbalance_bug(curr, lock, ip);
3349
3350found_it:
3351 if (hlock->instance == lock)
3352 lock_release_holdtime(hlock);
3353
3354 if (hlock->references) {
3355 hlock->references--;
3356 if (hlock->references) {
3357 /*
3358 * We had, and after removing one, still have
3359 * references, the current lock stack is still
3360 * valid. We're done!
3361 */
3362 return 1;
3363 }
3364 }
3365
3366 /*
3367 * We have the right lock to unlock, 'hlock' points to it.
3368 * Now we remove it from the stack, and add back the other
3369 * entries (if any), recalculating the hash along the way:
3370 */
3371
3372 curr->lockdep_depth = i;
3373 curr->curr_chain_key = hlock->prev_chain_key;
3374
3375 for (i++; i < depth; i++) {
3376 hlock = curr->held_locks + i;
3377 if (!__lock_acquire(hlock->instance,
3378 hlock_class(hlock)->subclass, hlock->trylock,
3379 hlock->read, hlock->check, hlock->hardirqs_off,
3380 hlock->nest_lock, hlock->acquire_ip,
3381 hlock->references))
3382 return 0;
3383 }
3384
3385 /*
3386 * We had N bottles of beer on the wall, we drank one, but now
3387 * there's not N-1 bottles of beer left on the wall...
3388 */
3389 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3390 return 0;
3391 return 1;
3392}
3393
3394/*
3395 * Remove the lock to the list of currently held locks - this gets
3396 * called on mutex_unlock()/spin_unlock*() (or on a failed
3397 * mutex_lock_interruptible()). This is done for unlocks that nest
3398 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3399 */
3400static int lock_release_nested(struct task_struct *curr,
3401 struct lockdep_map *lock, unsigned long ip)
3402{
3403 struct held_lock *hlock;
3404 unsigned int depth;
3405
3406 /*
3407 * Pop off the top of the lock stack:
3408 */
3409 depth = curr->lockdep_depth - 1;
3410 hlock = curr->held_locks + depth;
3411
3412 /*
3413 * Is the unlock non-nested:
3414 */
3415 if (hlock->instance != lock || hlock->references)
3416 return lock_release_non_nested(curr, lock, ip);
3417 curr->lockdep_depth--;
3418
3419 /*
3420 * No more locks, but somehow we've got hash left over, who left it?
3421 */
3422 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3423 return 0;
3424
3425 curr->curr_chain_key = hlock->prev_chain_key;
3426
3427 lock_release_holdtime(hlock);
3428
3429#ifdef CONFIG_DEBUG_LOCKDEP
3430 hlock->prev_chain_key = 0;
3431 hlock->class_idx = 0;
3432 hlock->acquire_ip = 0;
3433 hlock->irq_context = 0;
3434#endif
3435 return 1;
3436}
3437
3438/*
3439 * Remove the lock to the list of currently held locks - this gets
3440 * called on mutex_unlock()/spin_unlock*() (or on a failed
3441 * mutex_lock_interruptible()). This is done for unlocks that nest
3442 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3443 */
3444static void
3445__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3446{
3447 struct task_struct *curr = current;
3448
3449 if (!check_unlock(curr, lock, ip))
3450 return;
3451
3452 if (nested) {
3453 if (!lock_release_nested(curr, lock, ip))
3454 return;
3455 } else {
3456 if (!lock_release_non_nested(curr, lock, ip))
3457 return;
3458 }
3459
3460 check_chain_key(curr);
3461}
3462
3463static int __lock_is_held(struct lockdep_map *lock)
3464{
3465 struct task_struct *curr = current;
3466 int i;
3467
3468 for (i = 0; i < curr->lockdep_depth; i++) {
3469 struct held_lock *hlock = curr->held_locks + i;
3470
3471 if (match_held_lock(hlock, lock))
3472 return 1;
3473 }
3474
3475 return 0;
3476}
3477
3478/*
3479 * Check whether we follow the irq-flags state precisely:
3480 */
3481static void check_flags(unsigned long flags)
3482{
3483#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3484 defined(CONFIG_TRACE_IRQFLAGS)
3485 if (!debug_locks)
3486 return;
3487
3488 if (irqs_disabled_flags(flags)) {
3489 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3490 printk("possible reason: unannotated irqs-off.\n");
3491 }
3492 } else {
3493 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3494 printk("possible reason: unannotated irqs-on.\n");
3495 }
3496 }
3497
3498 /*
3499 * We dont accurately track softirq state in e.g.
3500 * hardirq contexts (such as on 4KSTACKS), so only
3501 * check if not in hardirq contexts:
3502 */
3503 if (!hardirq_count()) {
3504 if (softirq_count()) {
3505 /* like the above, but with softirqs */
3506 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3507 } else {
3508 /* lick the above, does it taste good? */
3509 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3510 }
3511 }
3512
3513 if (!debug_locks)
3514 print_irqtrace_events(current);
3515#endif
3516}
3517
3518void lock_set_class(struct lockdep_map *lock, const char *name,
3519 struct lock_class_key *key, unsigned int subclass,
3520 unsigned long ip)
3521{
3522 unsigned long flags;
3523
3524 if (unlikely(current->lockdep_recursion))
3525 return;
3526
3527 raw_local_irq_save(flags);
3528 current->lockdep_recursion = 1;
3529 check_flags(flags);
3530 if (__lock_set_class(lock, name, key, subclass, ip))
3531 check_chain_key(current);
3532 current->lockdep_recursion = 0;
3533 raw_local_irq_restore(flags);
3534}
3535EXPORT_SYMBOL_GPL(lock_set_class);
3536
3537/*
3538 * We are not always called with irqs disabled - do that here,
3539 * and also avoid lockdep recursion:
3540 */
3541void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3542 int trylock, int read, int check,
3543 struct lockdep_map *nest_lock, unsigned long ip)
3544{
3545 unsigned long flags;
3546
3547 if (unlikely(current->lockdep_recursion))
3548 return;
3549
3550 raw_local_irq_save(flags);
3551 check_flags(flags);
3552
3553 current->lockdep_recursion = 1;
3554 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3555 __lock_acquire(lock, subclass, trylock, read, check,
3556 irqs_disabled_flags(flags), nest_lock, ip, 0);
3557 current->lockdep_recursion = 0;
3558 raw_local_irq_restore(flags);
3559}
3560EXPORT_SYMBOL_GPL(lock_acquire);
3561
3562void lock_release(struct lockdep_map *lock, int nested,
3563 unsigned long ip)
3564{
3565 unsigned long flags;
3566
3567 if (unlikely(current->lockdep_recursion))
3568 return;
3569
3570 raw_local_irq_save(flags);
3571 check_flags(flags);
3572 current->lockdep_recursion = 1;
3573 trace_lock_release(lock, ip);
3574 __lock_release(lock, nested, ip);
3575 current->lockdep_recursion = 0;
3576 raw_local_irq_restore(flags);
3577}
3578EXPORT_SYMBOL_GPL(lock_release);
3579
3580int lock_is_held(struct lockdep_map *lock)
3581{
3582 unsigned long flags;
3583 int ret = 0;
3584
3585 if (unlikely(current->lockdep_recursion))
3586 return 1; /* avoid false negative lockdep_assert_held() */
3587
3588 raw_local_irq_save(flags);
3589 check_flags(flags);
3590
3591 current->lockdep_recursion = 1;
3592 ret = __lock_is_held(lock);
3593 current->lockdep_recursion = 0;
3594 raw_local_irq_restore(flags);
3595
3596 return ret;
3597}
3598EXPORT_SYMBOL_GPL(lock_is_held);
3599
3600void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3601{
3602 current->lockdep_reclaim_gfp = gfp_mask;
3603}
3604
3605void lockdep_clear_current_reclaim_state(void)
3606{
3607 current->lockdep_reclaim_gfp = 0;
3608}
3609
3610#ifdef CONFIG_LOCK_STAT
3611static int
3612print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3613 unsigned long ip)
3614{
3615 if (!debug_locks_off())
3616 return 0;
3617 if (debug_locks_silent)
3618 return 0;
3619
3620 printk("\n");
3621 printk("=================================\n");
3622 printk("[ BUG: bad contention detected! ]\n");
3623 print_kernel_ident();
3624 printk("---------------------------------\n");
3625 printk("%s/%d is trying to contend lock (",
3626 curr->comm, task_pid_nr(curr));
3627 print_lockdep_cache(lock);
3628 printk(") at:\n");
3629 print_ip_sym(ip);
3630 printk("but there are no locks held!\n");
3631 printk("\nother info that might help us debug this:\n");
3632 lockdep_print_held_locks(curr);
3633
3634 printk("\nstack backtrace:\n");
3635 dump_stack();
3636
3637 return 0;
3638}
3639
3640static void
3641__lock_contended(struct lockdep_map *lock, unsigned long ip)
3642{
3643 struct task_struct *curr = current;
3644 struct held_lock *hlock, *prev_hlock;
3645 struct lock_class_stats *stats;
3646 unsigned int depth;
3647 int i, contention_point, contending_point;
3648
3649 depth = curr->lockdep_depth;
3650 /*
3651 * Whee, we contended on this lock, except it seems we're not
3652 * actually trying to acquire anything much at all..
3653 */
3654 if (DEBUG_LOCKS_WARN_ON(!depth))
3655 return;
3656
3657 prev_hlock = NULL;
3658 for (i = depth-1; i >= 0; i--) {
3659 hlock = curr->held_locks + i;
3660 /*
3661 * We must not cross into another context:
3662 */
3663 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3664 break;
3665 if (match_held_lock(hlock, lock))
3666 goto found_it;
3667 prev_hlock = hlock;
3668 }
3669 print_lock_contention_bug(curr, lock, ip);
3670 return;
3671
3672found_it:
3673 if (hlock->instance != lock)
3674 return;
3675
3676 hlock->waittime_stamp = lockstat_clock();
3677
3678 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3679 contending_point = lock_point(hlock_class(hlock)->contending_point,
3680 lock->ip);
3681
3682 stats = get_lock_stats(hlock_class(hlock));
3683 if (contention_point < LOCKSTAT_POINTS)
3684 stats->contention_point[contention_point]++;
3685 if (contending_point < LOCKSTAT_POINTS)
3686 stats->contending_point[contending_point]++;
3687 if (lock->cpu != smp_processor_id())
3688 stats->bounces[bounce_contended + !!hlock->read]++;
3689 put_lock_stats(stats);
3690}
3691
3692static void
3693__lock_acquired(struct lockdep_map *lock, unsigned long ip)
3694{
3695 struct task_struct *curr = current;
3696 struct held_lock *hlock, *prev_hlock;
3697 struct lock_class_stats *stats;
3698 unsigned int depth;
3699 u64 now, waittime = 0;
3700 int i, cpu;
3701
3702 depth = curr->lockdep_depth;
3703 /*
3704 * Yay, we acquired ownership of this lock we didn't try to
3705 * acquire, how the heck did that happen?
3706 */
3707 if (DEBUG_LOCKS_WARN_ON(!depth))
3708 return;
3709
3710 prev_hlock = NULL;
3711 for (i = depth-1; i >= 0; i--) {
3712 hlock = curr->held_locks + i;
3713 /*
3714 * We must not cross into another context:
3715 */
3716 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3717 break;
3718 if (match_held_lock(hlock, lock))
3719 goto found_it;
3720 prev_hlock = hlock;
3721 }
3722 print_lock_contention_bug(curr, lock, _RET_IP_);
3723 return;
3724
3725found_it:
3726 if (hlock->instance != lock)
3727 return;
3728
3729 cpu = smp_processor_id();
3730 if (hlock->waittime_stamp) {
3731 now = lockstat_clock();
3732 waittime = now - hlock->waittime_stamp;
3733 hlock->holdtime_stamp = now;
3734 }
3735
3736 trace_lock_acquired(lock, ip);
3737
3738 stats = get_lock_stats(hlock_class(hlock));
3739 if (waittime) {
3740 if (hlock->read)
3741 lock_time_inc(&stats->read_waittime, waittime);
3742 else
3743 lock_time_inc(&stats->write_waittime, waittime);
3744 }
3745 if (lock->cpu != cpu)
3746 stats->bounces[bounce_acquired + !!hlock->read]++;
3747 put_lock_stats(stats);
3748
3749 lock->cpu = cpu;
3750 lock->ip = ip;
3751}
3752
3753void lock_contended(struct lockdep_map *lock, unsigned long ip)
3754{
3755 unsigned long flags;
3756
3757 if (unlikely(!lock_stat))
3758 return;
3759
3760 if (unlikely(current->lockdep_recursion))
3761 return;
3762
3763 raw_local_irq_save(flags);
3764 check_flags(flags);
3765 current->lockdep_recursion = 1;
3766 trace_lock_contended(lock, ip);
3767 __lock_contended(lock, ip);
3768 current->lockdep_recursion = 0;
3769 raw_local_irq_restore(flags);
3770}
3771EXPORT_SYMBOL_GPL(lock_contended);
3772
3773void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3774{
3775 unsigned long flags;
3776
3777 if (unlikely(!lock_stat))
3778 return;
3779
3780 if (unlikely(current->lockdep_recursion))
3781 return;
3782
3783 raw_local_irq_save(flags);
3784 check_flags(flags);
3785 current->lockdep_recursion = 1;
3786 __lock_acquired(lock, ip);
3787 current->lockdep_recursion = 0;
3788 raw_local_irq_restore(flags);
3789}
3790EXPORT_SYMBOL_GPL(lock_acquired);
3791#endif
3792
3793/*
3794 * Used by the testsuite, sanitize the validator state
3795 * after a simulated failure:
3796 */
3797
3798void lockdep_reset(void)
3799{
3800 unsigned long flags;
3801 int i;
3802
3803 raw_local_irq_save(flags);
3804 current->curr_chain_key = 0;
3805 current->lockdep_depth = 0;
3806 current->lockdep_recursion = 0;
3807 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3808 nr_hardirq_chains = 0;
3809 nr_softirq_chains = 0;
3810 nr_process_chains = 0;
3811 debug_locks = 1;
3812 for (i = 0; i < CHAINHASH_SIZE; i++)
3813 INIT_LIST_HEAD(chainhash_table + i);
3814 raw_local_irq_restore(flags);
3815}
3816
3817static void zap_class(struct lock_class *class)
3818{
3819 int i;
3820
3821 /*
3822 * Remove all dependencies this lock is
3823 * involved in:
3824 */
3825 for (i = 0; i < nr_list_entries; i++) {
3826 if (list_entries[i].class == class)
3827 list_del_rcu(&list_entries[i].entry);
3828 }
3829 /*
3830 * Unhash the class and remove it from the all_lock_classes list:
3831 */
3832 list_del_rcu(&class->hash_entry);
3833 list_del_rcu(&class->lock_entry);
3834
3835 class->key = NULL;
3836}
3837
3838static inline int within(const void *addr, void *start, unsigned long size)
3839{
3840 return addr >= start && addr < start + size;
3841}
3842
3843void lockdep_free_key_range(void *start, unsigned long size)
3844{
3845 struct lock_class *class, *next;
3846 struct list_head *head;
3847 unsigned long flags;
3848 int i;
3849 int locked;
3850
3851 raw_local_irq_save(flags);
3852 locked = graph_lock();
3853
3854 /*
3855 * Unhash all classes that were created by this module:
3856 */
3857 for (i = 0; i < CLASSHASH_SIZE; i++) {
3858 head = classhash_table + i;
3859 if (list_empty(head))
3860 continue;
3861 list_for_each_entry_safe(class, next, head, hash_entry) {
3862 if (within(class->key, start, size))
3863 zap_class(class);
3864 else if (within(class->name, start, size))
3865 zap_class(class);
3866 }
3867 }
3868
3869 if (locked)
3870 graph_unlock();
3871 raw_local_irq_restore(flags);
3872}
3873
3874void lockdep_reset_lock(struct lockdep_map *lock)
3875{
3876 struct lock_class *class, *next;
3877 struct list_head *head;
3878 unsigned long flags;
3879 int i, j;
3880 int locked;
3881
3882 raw_local_irq_save(flags);
3883
3884 /*
3885 * Remove all classes this lock might have:
3886 */
3887 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3888 /*
3889 * If the class exists we look it up and zap it:
3890 */
3891 class = look_up_lock_class(lock, j);
3892 if (class)
3893 zap_class(class);
3894 }
3895 /*
3896 * Debug check: in the end all mapped classes should
3897 * be gone.
3898 */
3899 locked = graph_lock();
3900 for (i = 0; i < CLASSHASH_SIZE; i++) {
3901 head = classhash_table + i;
3902 if (list_empty(head))
3903 continue;
3904 list_for_each_entry_safe(class, next, head, hash_entry) {
3905 int match = 0;
3906
3907 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3908 match |= class == lock->class_cache[j];
3909
3910 if (unlikely(match)) {
3911 if (debug_locks_off_graph_unlock()) {
3912 /*
3913 * We all just reset everything, how did it match?
3914 */
3915 WARN_ON(1);
3916 }
3917 goto out_restore;
3918 }
3919 }
3920 }
3921 if (locked)
3922 graph_unlock();
3923
3924out_restore:
3925 raw_local_irq_restore(flags);
3926}
3927
3928void lockdep_init(void)
3929{
3930 int i;
3931
3932 /*
3933 * Some architectures have their own start_kernel()
3934 * code which calls lockdep_init(), while we also
3935 * call lockdep_init() from the start_kernel() itself,
3936 * and we want to initialize the hashes only once:
3937 */
3938 if (lockdep_initialized)
3939 return;
3940
3941 for (i = 0; i < CLASSHASH_SIZE; i++)
3942 INIT_LIST_HEAD(classhash_table + i);
3943
3944 for (i = 0; i < CHAINHASH_SIZE; i++)
3945 INIT_LIST_HEAD(chainhash_table + i);
3946
3947 lockdep_initialized = 1;
3948}
3949
3950void __init lockdep_info(void)
3951{
3952 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3953
3954 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3955 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3956 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3957 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3958 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3959 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3960 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3961
3962 printk(" memory used by lock dependency info: %lu kB\n",
3963 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3964 sizeof(struct list_head) * CLASSHASH_SIZE +
3965 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3966 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3967 sizeof(struct list_head) * CHAINHASH_SIZE
3968#ifdef CONFIG_PROVE_LOCKING
3969 + sizeof(struct circular_queue)
3970#endif
3971 ) / 1024
3972 );
3973
3974 printk(" per task-struct memory footprint: %lu bytes\n",
3975 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3976
3977#ifdef CONFIG_DEBUG_LOCKDEP
3978 if (lockdep_init_error) {
3979 printk("WARNING: lockdep init error! lock-%s was acquired"
3980 "before lockdep_init\n", lock_init_error);
3981 printk("Call stack leading to lockdep invocation was:\n");
3982 print_stack_trace(&lockdep_init_trace, 0);
3983 }
3984#endif
3985}
3986
3987static void
3988print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3989 const void *mem_to, struct held_lock *hlock)
3990{
3991 if (!debug_locks_off())
3992 return;
3993 if (debug_locks_silent)
3994 return;
3995
3996 printk("\n");
3997 printk("=========================\n");
3998 printk("[ BUG: held lock freed! ]\n");
3999 print_kernel_ident();
4000 printk("-------------------------\n");
4001 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4002 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4003 print_lock(hlock);
4004 lockdep_print_held_locks(curr);
4005
4006 printk("\nstack backtrace:\n");
4007 dump_stack();
4008}
4009
4010static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4011 const void* lock_from, unsigned long lock_len)
4012{
4013 return lock_from + lock_len <= mem_from ||
4014 mem_from + mem_len <= lock_from;
4015}
4016
4017/*
4018 * Called when kernel memory is freed (or unmapped), or if a lock
4019 * is destroyed or reinitialized - this code checks whether there is
4020 * any held lock in the memory range of <from> to <to>:
4021 */
4022void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4023{
4024 struct task_struct *curr = current;
4025 struct held_lock *hlock;
4026 unsigned long flags;
4027 int i;
4028
4029 if (unlikely(!debug_locks))
4030 return;
4031
4032 local_irq_save(flags);
4033 for (i = 0; i < curr->lockdep_depth; i++) {
4034 hlock = curr->held_locks + i;
4035
4036 if (not_in_range(mem_from, mem_len, hlock->instance,
4037 sizeof(*hlock->instance)))
4038 continue;
4039
4040 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
4041 break;
4042 }
4043 local_irq_restore(flags);
4044}
4045EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
4046
4047static void print_held_locks_bug(struct task_struct *curr)
4048{
4049 if (!debug_locks_off())
4050 return;
4051 if (debug_locks_silent)
4052 return;
4053
4054 printk("\n");
4055 printk("=====================================\n");
4056 printk("[ BUG: lock held at task exit time! ]\n");
4057 print_kernel_ident();
4058 printk("-------------------------------------\n");
4059 printk("%s/%d is exiting with locks still held!\n",
4060 curr->comm, task_pid_nr(curr));
4061 lockdep_print_held_locks(curr);
4062
4063 printk("\nstack backtrace:\n");
4064 dump_stack();
4065}
4066
4067void debug_check_no_locks_held(struct task_struct *task)
4068{
4069 if (unlikely(task->lockdep_depth > 0))
4070 print_held_locks_bug(task);
4071}
4072
4073void debug_show_all_locks(void)
4074{
4075 struct task_struct *g, *p;
4076 int count = 10;
4077 int unlock = 1;
4078
4079 if (unlikely(!debug_locks)) {
4080 printk("INFO: lockdep is turned off.\n");
4081 return;
4082 }
4083 printk("\nShowing all locks held in the system:\n");
4084
4085 /*
4086 * Here we try to get the tasklist_lock as hard as possible,
4087 * if not successful after 2 seconds we ignore it (but keep
4088 * trying). This is to enable a debug printout even if a
4089 * tasklist_lock-holding task deadlocks or crashes.
4090 */
4091retry:
4092 if (!read_trylock(&tasklist_lock)) {
4093 if (count == 10)
4094 printk("hm, tasklist_lock locked, retrying... ");
4095 if (count) {
4096 count--;
4097 printk(" #%d", 10-count);
4098 mdelay(200);
4099 goto retry;
4100 }
4101 printk(" ignoring it.\n");
4102 unlock = 0;
4103 } else {
4104 if (count != 10)
4105 printk(KERN_CONT " locked it.\n");
4106 }
4107
4108 do_each_thread(g, p) {
4109 /*
4110 * It's not reliable to print a task's held locks
4111 * if it's not sleeping (or if it's not the current
4112 * task):
4113 */
4114 if (p->state == TASK_RUNNING && p != current)
4115 continue;
4116 if (p->lockdep_depth)
4117 lockdep_print_held_locks(p);
4118 if (!unlock)
4119 if (read_trylock(&tasklist_lock))
4120 unlock = 1;
4121 } while_each_thread(g, p);
4122
4123 printk("\n");
4124 printk("=============================================\n\n");
4125
4126 if (unlock)
4127 read_unlock(&tasklist_lock);
4128}
4129EXPORT_SYMBOL_GPL(debug_show_all_locks);
4130
4131/*
4132 * Careful: only use this function if you are sure that
4133 * the task cannot run in parallel!
4134 */
4135void debug_show_held_locks(struct task_struct *task)
4136{
4137 if (unlikely(!debug_locks)) {
4138 printk("INFO: lockdep is turned off.\n");
4139 return;
4140 }
4141 lockdep_print_held_locks(task);
4142}
4143EXPORT_SYMBOL_GPL(debug_show_held_locks);
4144
4145void lockdep_sys_exit(void)
4146{
4147 struct task_struct *curr = current;
4148
4149 if (unlikely(curr->lockdep_depth)) {
4150 if (!debug_locks_off())
4151 return;
4152 printk("\n");
4153 printk("================================================\n");
4154 printk("[ BUG: lock held when returning to user space! ]\n");
4155 print_kernel_ident();
4156 printk("------------------------------------------------\n");
4157 printk("%s/%d is leaving the kernel with locks still held!\n",
4158 curr->comm, curr->pid);
4159 lockdep_print_held_locks(curr);
4160 }
4161}
4162
4163void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4164{
4165 struct task_struct *curr = current;
4166
4167#ifndef CONFIG_PROVE_RCU_REPEATEDLY
4168 if (!debug_locks_off())
4169 return;
4170#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4171 /* Note: the following can be executed concurrently, so be careful. */
4172 printk("\n");
4173 printk("===============================\n");
4174 printk("[ INFO: suspicious RCU usage. ]\n");
4175 print_kernel_ident();
4176 printk("-------------------------------\n");
4177 printk("%s:%d %s!\n", file, line, s);
4178 printk("\nother info that might help us debug this:\n\n");
4179 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4180 !rcu_lockdep_current_cpu_online()
4181 ? "RCU used illegally from offline CPU!\n"
4182 : rcu_is_cpu_idle()
4183 ? "RCU used illegally from idle CPU!\n"
4184 : "",
4185 rcu_scheduler_active, debug_locks);
4186
4187 /*
4188 * If a CPU is in the RCU-free window in idle (ie: in the section
4189 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4190 * considers that CPU to be in an "extended quiescent state",
4191 * which means that RCU will be completely ignoring that CPU.
4192 * Therefore, rcu_read_lock() and friends have absolutely no
4193 * effect on a CPU running in that state. In other words, even if
4194 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4195 * delete data structures out from under it. RCU really has no
4196 * choice here: we need to keep an RCU-free window in idle where
4197 * the CPU may possibly enter into low power mode. This way we can
4198 * notice an extended quiescent state to other CPUs that started a grace
4199 * period. Otherwise we would delay any grace period as long as we run
4200 * in the idle task.
4201 *
4202 * So complain bitterly if someone does call rcu_read_lock(),
4203 * rcu_read_lock_bh() and so on from extended quiescent states.
4204 */
4205 if (rcu_is_cpu_idle())
4206 printk("RCU used illegally from extended quiescent state!\n");
4207
4208 lockdep_print_held_locks(curr);
4209 printk("\nstack backtrace:\n");
4210 dump_stack();
4211}
4212EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);