blob: c9fefdb1a7db45df9658dd32d963e7f28bbdfdf4 [file] [log] [blame]
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001/*
2 * kernel/lockdep.c
3 *
4 * Runtime locking correctness validator
5 *
6 * Started by Ingo Molnar:
7 *
8 * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 *
10 * this code maps all the lock dependencies as they occur in a live kernel
11 * and will warn about the following classes of locking bugs:
12 *
13 * - lock inversion scenarios
14 * - circular lock dependencies
15 * - hardirq/softirq safe/unsafe locking bugs
16 *
17 * Bugs are reported even if the current locking scenario does not cause
18 * any deadlock at this point.
19 *
20 * I.e. if anytime in the past two locks were taken in a different order,
21 * even if it happened for another task, even if those were different
22 * locks (but of the same class as this lock), this code will detect it.
23 *
24 * Thanks to Arjan van de Ven for coming up with the initial idea of
25 * mapping lock dependencies runtime.
26 */
27#include <linux/mutex.h>
28#include <linux/sched.h>
29#include <linux/delay.h>
30#include <linux/module.h>
31#include <linux/proc_fs.h>
32#include <linux/seq_file.h>
33#include <linux/spinlock.h>
34#include <linux/kallsyms.h>
35#include <linux/interrupt.h>
36#include <linux/stacktrace.h>
37#include <linux/debug_locks.h>
38#include <linux/irqflags.h>
Dave Jones99de0552006-09-29 02:00:10 -070039#include <linux/utsname.h>
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070040
41#include <asm/sections.h>
42
43#include "lockdep_internals.h"
44
45/*
46 * hash_lock: protects the lockdep hashes and class/list/hash allocators.
47 *
48 * This is one of the rare exceptions where it's justified
49 * to use a raw spinlock - we really dont want the spinlock
50 * code to recurse back into the lockdep code.
51 */
52static raw_spinlock_t hash_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
53
54static int lockdep_initialized;
55
56unsigned long nr_list_entries;
57static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
58
59/*
60 * Allocate a lockdep entry. (assumes hash_lock held, returns
61 * with NULL on failure)
62 */
63static struct lock_list *alloc_list_entry(void)
64{
65 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
66 __raw_spin_unlock(&hash_lock);
67 debug_locks_off();
68 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
69 printk("turning off the locking correctness validator.\n");
70 return NULL;
71 }
72 return list_entries + nr_list_entries++;
73}
74
75/*
76 * All data structures here are protected by the global debug_lock.
77 *
78 * Mutex key structs only get allocated, once during bootup, and never
79 * get freed - this significantly simplifies the debugging code.
80 */
81unsigned long nr_lock_classes;
82static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
83
84/*
85 * We keep a global list of all lock classes. The list only grows,
86 * never shrinks. The list is only accessed with the lockdep
87 * spinlock lock held.
88 */
89LIST_HEAD(all_lock_classes);
90
91/*
92 * The lockdep classes are in a hash-table as well, for fast lookup:
93 */
94#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
95#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
96#define CLASSHASH_MASK (CLASSHASH_SIZE - 1)
97#define __classhashfn(key) ((((unsigned long)key >> CLASSHASH_BITS) + (unsigned long)key) & CLASSHASH_MASK)
98#define classhashentry(key) (classhash_table + __classhashfn((key)))
99
100static struct list_head classhash_table[CLASSHASH_SIZE];
101
102unsigned long nr_lock_chains;
103static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
104
105/*
106 * We put the lock dependency chains into a hash-table as well, to cache
107 * their existence:
108 */
109#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
110#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
111#define CHAINHASH_MASK (CHAINHASH_SIZE - 1)
112#define __chainhashfn(chain) \
113 (((chain >> CHAINHASH_BITS) + chain) & CHAINHASH_MASK)
114#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
115
116static struct list_head chainhash_table[CHAINHASH_SIZE];
117
118/*
119 * The hash key of the lock dependency chains is a hash itself too:
120 * it's a hash of all locks taken up to that lock, including that lock.
121 * It's a 64-bit hash, because it's important for the keys to be
122 * unique.
123 */
124#define iterate_chain_key(key1, key2) \
Ingo Molnar03cbc352006-09-29 02:01:46 -0700125 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
126 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700127 (key2))
128
129void lockdep_off(void)
130{
131 current->lockdep_recursion++;
132}
133
134EXPORT_SYMBOL(lockdep_off);
135
136void lockdep_on(void)
137{
138 current->lockdep_recursion--;
139}
140
141EXPORT_SYMBOL(lockdep_on);
142
143int lockdep_internal(void)
144{
145 return current->lockdep_recursion != 0;
146}
147
148EXPORT_SYMBOL(lockdep_internal);
149
150/*
151 * Debugging switches:
152 */
153
154#define VERBOSE 0
155#ifdef VERBOSE
156# define VERY_VERBOSE 0
157#endif
158
159#if VERBOSE
160# define HARDIRQ_VERBOSE 1
161# define SOFTIRQ_VERBOSE 1
162#else
163# define HARDIRQ_VERBOSE 0
164# define SOFTIRQ_VERBOSE 0
165#endif
166
167#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
168/*
169 * Quick filtering for interesting events:
170 */
171static int class_filter(struct lock_class *class)
172{
Andi Kleenf9829cc2006-07-10 04:44:01 -0700173#if 0
174 /* Example */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700175 if (class->name_version == 1 &&
Andi Kleenf9829cc2006-07-10 04:44:01 -0700176 !strcmp(class->name, "lockname"))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700177 return 1;
178 if (class->name_version == 1 &&
Andi Kleenf9829cc2006-07-10 04:44:01 -0700179 !strcmp(class->name, "&struct->lockfield"))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700180 return 1;
Andi Kleenf9829cc2006-07-10 04:44:01 -0700181#endif
182 /* Allow everything else. 0 would be filter everything else */
183 return 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700184}
185#endif
186
187static int verbose(struct lock_class *class)
188{
189#if VERBOSE
190 return class_filter(class);
191#endif
192 return 0;
193}
194
195#ifdef CONFIG_TRACE_IRQFLAGS
196
197static int hardirq_verbose(struct lock_class *class)
198{
199#if HARDIRQ_VERBOSE
200 return class_filter(class);
201#endif
202 return 0;
203}
204
205static int softirq_verbose(struct lock_class *class)
206{
207#if SOFTIRQ_VERBOSE
208 return class_filter(class);
209#endif
210 return 0;
211}
212
213#endif
214
215/*
216 * Stack-trace: tightly packed array of stack backtrace
217 * addresses. Protected by the hash_lock.
218 */
219unsigned long nr_stack_trace_entries;
220static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
221
222static int save_trace(struct stack_trace *trace)
223{
224 trace->nr_entries = 0;
225 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
226 trace->entries = stack_trace + nr_stack_trace_entries;
227
Andi Kleen5a1b3992006-09-26 10:52:34 +0200228 trace->skip = 3;
229 trace->all_contexts = 0;
230
Andi Kleen3fa7c792006-09-26 10:52:34 +0200231 /* Make sure to not recurse in case the the unwinder needs to tak
232e locks. */
233 lockdep_off();
Andi Kleen5a1b3992006-09-26 10:52:34 +0200234 save_stack_trace(trace, NULL);
Andi Kleen3fa7c792006-09-26 10:52:34 +0200235 lockdep_on();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700236
237 trace->max_entries = trace->nr_entries;
238
239 nr_stack_trace_entries += trace->nr_entries;
240 if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES))
241 return 0;
242
243 if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
244 __raw_spin_unlock(&hash_lock);
245 if (debug_locks_off()) {
246 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
247 printk("turning off the locking correctness validator.\n");
248 dump_stack();
249 }
250 return 0;
251 }
252
253 return 1;
254}
255
256unsigned int nr_hardirq_chains;
257unsigned int nr_softirq_chains;
258unsigned int nr_process_chains;
259unsigned int max_lockdep_depth;
260unsigned int max_recursion_depth;
261
262#ifdef CONFIG_DEBUG_LOCKDEP
263/*
264 * We cannot printk in early bootup code. Not even early_printk()
265 * might work. So we mark any initialization errors and printk
266 * about it later on, in lockdep_info().
267 */
268static int lockdep_init_error;
269
270/*
271 * Various lockdep statistics:
272 */
273atomic_t chain_lookup_hits;
274atomic_t chain_lookup_misses;
275atomic_t hardirqs_on_events;
276atomic_t hardirqs_off_events;
277atomic_t redundant_hardirqs_on;
278atomic_t redundant_hardirqs_off;
279atomic_t softirqs_on_events;
280atomic_t softirqs_off_events;
281atomic_t redundant_softirqs_on;
282atomic_t redundant_softirqs_off;
283atomic_t nr_unused_locks;
284atomic_t nr_cyclic_checks;
285atomic_t nr_cyclic_check_recursions;
286atomic_t nr_find_usage_forwards_checks;
287atomic_t nr_find_usage_forwards_recursions;
288atomic_t nr_find_usage_backwards_checks;
289atomic_t nr_find_usage_backwards_recursions;
290# define debug_atomic_inc(ptr) atomic_inc(ptr)
291# define debug_atomic_dec(ptr) atomic_dec(ptr)
292# define debug_atomic_read(ptr) atomic_read(ptr)
293#else
294# define debug_atomic_inc(ptr) do { } while (0)
295# define debug_atomic_dec(ptr) do { } while (0)
296# define debug_atomic_read(ptr) 0
297#endif
298
299/*
300 * Locking printouts:
301 */
302
303static const char *usage_str[] =
304{
305 [LOCK_USED] = "initial-use ",
306 [LOCK_USED_IN_HARDIRQ] = "in-hardirq-W",
307 [LOCK_USED_IN_SOFTIRQ] = "in-softirq-W",
308 [LOCK_ENABLED_SOFTIRQS] = "softirq-on-W",
309 [LOCK_ENABLED_HARDIRQS] = "hardirq-on-W",
310 [LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R",
311 [LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R",
312 [LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R",
313 [LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R",
314};
315
316const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
317{
318 unsigned long offs, size;
319 char *modname;
320
321 return kallsyms_lookup((unsigned long)key, &size, &offs, &modname, str);
322}
323
324void
325get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
326{
327 *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
328
329 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
330 *c1 = '+';
331 else
332 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
333 *c1 = '-';
334
335 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
336 *c2 = '+';
337 else
338 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
339 *c2 = '-';
340
341 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
342 *c3 = '-';
343 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
344 *c3 = '+';
345 if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
346 *c3 = '?';
347 }
348
349 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
350 *c4 = '-';
351 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
352 *c4 = '+';
353 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
354 *c4 = '?';
355 }
356}
357
358static void print_lock_name(struct lock_class *class)
359{
360 char str[128], c1, c2, c3, c4;
361 const char *name;
362
363 get_usage_chars(class, &c1, &c2, &c3, &c4);
364
365 name = class->name;
366 if (!name) {
367 name = __get_key_name(class->key, str);
368 printk(" (%s", name);
369 } else {
370 printk(" (%s", name);
371 if (class->name_version > 1)
372 printk("#%d", class->name_version);
373 if (class->subclass)
374 printk("/%d", class->subclass);
375 }
376 printk("){%c%c%c%c}", c1, c2, c3, c4);
377}
378
379static void print_lockdep_cache(struct lockdep_map *lock)
380{
381 const char *name;
382 char str[128];
383
384 name = lock->name;
385 if (!name)
386 name = __get_key_name(lock->key->subkeys, str);
387
388 printk("%s", name);
389}
390
391static void print_lock(struct held_lock *hlock)
392{
393 print_lock_name(hlock->class);
394 printk(", at: ");
395 print_ip_sym(hlock->acquire_ip);
396}
397
398static void lockdep_print_held_locks(struct task_struct *curr)
399{
400 int i, depth = curr->lockdep_depth;
401
402 if (!depth) {
403 printk("no locks held by %s/%d.\n", curr->comm, curr->pid);
404 return;
405 }
406 printk("%d lock%s held by %s/%d:\n",
407 depth, depth > 1 ? "s" : "", curr->comm, curr->pid);
408
409 for (i = 0; i < depth; i++) {
410 printk(" #%d: ", i);
411 print_lock(curr->held_locks + i);
412 }
413}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700414
415static void print_lock_class_header(struct lock_class *class, int depth)
416{
417 int bit;
418
Andi Kleenf9829cc2006-07-10 04:44:01 -0700419 printk("%*s->", depth, "");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700420 print_lock_name(class);
421 printk(" ops: %lu", class->ops);
422 printk(" {\n");
423
424 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
425 if (class->usage_mask & (1 << bit)) {
426 int len = depth;
427
Andi Kleenf9829cc2006-07-10 04:44:01 -0700428 len += printk("%*s %s", depth, "", usage_str[bit]);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700429 len += printk(" at:\n");
430 print_stack_trace(class->usage_traces + bit, len);
431 }
432 }
Andi Kleenf9829cc2006-07-10 04:44:01 -0700433 printk("%*s }\n", depth, "");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700434
Andi Kleenf9829cc2006-07-10 04:44:01 -0700435 printk("%*s ... key at: ",depth,"");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700436 print_ip_sym((unsigned long)class->key);
437}
438
439/*
440 * printk all lock dependencies starting at <entry>:
441 */
442static void print_lock_dependencies(struct lock_class *class, int depth)
443{
444 struct lock_list *entry;
445
446 if (DEBUG_LOCKS_WARN_ON(depth >= 20))
447 return;
448
449 print_lock_class_header(class, depth);
450
451 list_for_each_entry(entry, &class->locks_after, entry) {
452 DEBUG_LOCKS_WARN_ON(!entry->class);
453 print_lock_dependencies(entry->class, depth + 1);
454
Andi Kleenf9829cc2006-07-10 04:44:01 -0700455 printk("%*s ... acquired at:\n",depth,"");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700456 print_stack_trace(&entry->trace, 2);
457 printk("\n");
458 }
459}
460
461/*
462 * Add a new dependency to the head of the list:
463 */
464static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
465 struct list_head *head, unsigned long ip)
466{
467 struct lock_list *entry;
468 /*
469 * Lock not present yet - get a new dependency struct and
470 * add it to the list:
471 */
472 entry = alloc_list_entry();
473 if (!entry)
474 return 0;
475
476 entry->class = this;
477 save_trace(&entry->trace);
478
479 /*
480 * Since we never remove from the dependency list, the list can
481 * be walked lockless by other CPUs, it's only allocation
482 * that must be protected by the spinlock. But this also means
483 * we must make new entries visible only once writes to the
484 * entry become visible - hence the RCU op:
485 */
486 list_add_tail_rcu(&entry->entry, head);
487
488 return 1;
489}
490
491/*
492 * Recursive, forwards-direction lock-dependency checking, used for
493 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
494 * checking.
495 *
496 * (to keep the stackframe of the recursive functions small we
497 * use these global variables, and we also mark various helper
498 * functions as noinline.)
499 */
500static struct held_lock *check_source, *check_target;
501
502/*
503 * Print a dependency chain entry (this is only done when a deadlock
504 * has been detected):
505 */
506static noinline int
507print_circular_bug_entry(struct lock_list *target, unsigned int depth)
508{
509 if (debug_locks_silent)
510 return 0;
511 printk("\n-> #%u", depth);
512 print_lock_name(target->class);
513 printk(":\n");
514 print_stack_trace(&target->trace, 6);
515
516 return 0;
517}
518
Dave Jones99de0552006-09-29 02:00:10 -0700519static void print_kernel_version(void)
520{
Serge E. Hallyn96b644b2006-10-02 02:18:13 -0700521 printk("%s %.*s\n", init_utsname()->release,
522 (int)strcspn(init_utsname()->version, " "),
523 init_utsname()->version);
Dave Jones99de0552006-09-29 02:00:10 -0700524}
525
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700526/*
527 * When a circular dependency is detected, print the
528 * header first:
529 */
530static noinline int
531print_circular_bug_header(struct lock_list *entry, unsigned int depth)
532{
533 struct task_struct *curr = current;
534
535 __raw_spin_unlock(&hash_lock);
536 debug_locks_off();
537 if (debug_locks_silent)
538 return 0;
539
540 printk("\n=======================================================\n");
541 printk( "[ INFO: possible circular locking dependency detected ]\n");
Dave Jones99de0552006-09-29 02:00:10 -0700542 print_kernel_version();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700543 printk( "-------------------------------------------------------\n");
544 printk("%s/%d is trying to acquire lock:\n",
545 curr->comm, curr->pid);
546 print_lock(check_source);
547 printk("\nbut task is already holding lock:\n");
548 print_lock(check_target);
549 printk("\nwhich lock already depends on the new lock.\n\n");
550 printk("\nthe existing dependency chain (in reverse order) is:\n");
551
552 print_circular_bug_entry(entry, depth);
553
554 return 0;
555}
556
557static noinline int print_circular_bug_tail(void)
558{
559 struct task_struct *curr = current;
560 struct lock_list this;
561
562 if (debug_locks_silent)
563 return 0;
564
565 this.class = check_source->class;
566 save_trace(&this.trace);
567 print_circular_bug_entry(&this, 0);
568
569 printk("\nother info that might help us debug this:\n\n");
570 lockdep_print_held_locks(curr);
571
572 printk("\nstack backtrace:\n");
573 dump_stack();
574
575 return 0;
576}
577
Ingo Molnarca268c62006-10-17 00:09:28 -0700578#define RECURSION_LIMIT 40
579
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700580static int noinline print_infinite_recursion_bug(void)
581{
582 __raw_spin_unlock(&hash_lock);
583 DEBUG_LOCKS_WARN_ON(1);
584
585 return 0;
586}
587
588/*
589 * Prove that the dependency graph starting at <entry> can not
590 * lead to <target>. Print an error and return 0 if it does.
591 */
592static noinline int
593check_noncircular(struct lock_class *source, unsigned int depth)
594{
595 struct lock_list *entry;
596
597 debug_atomic_inc(&nr_cyclic_check_recursions);
598 if (depth > max_recursion_depth)
599 max_recursion_depth = depth;
Ingo Molnarca268c62006-10-17 00:09:28 -0700600 if (depth >= RECURSION_LIMIT)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700601 return print_infinite_recursion_bug();
602 /*
603 * Check this lock's dependency list:
604 */
605 list_for_each_entry(entry, &source->locks_after, entry) {
606 if (entry->class == check_target->class)
607 return print_circular_bug_header(entry, depth+1);
608 debug_atomic_inc(&nr_cyclic_checks);
609 if (!check_noncircular(entry->class, depth+1))
610 return print_circular_bug_entry(entry, depth+1);
611 }
612 return 1;
613}
614
615static int very_verbose(struct lock_class *class)
616{
617#if VERY_VERBOSE
618 return class_filter(class);
619#endif
620 return 0;
621}
622#ifdef CONFIG_TRACE_IRQFLAGS
623
624/*
625 * Forwards and backwards subgraph searching, for the purposes of
626 * proving that two subgraphs can be connected by a new dependency
627 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
628 */
629static enum lock_usage_bit find_usage_bit;
630static struct lock_class *forwards_match, *backwards_match;
631
632/*
633 * Find a node in the forwards-direction dependency sub-graph starting
634 * at <source> that matches <find_usage_bit>.
635 *
636 * Return 2 if such a node exists in the subgraph, and put that node
637 * into <forwards_match>.
638 *
639 * Return 1 otherwise and keep <forwards_match> unchanged.
640 * Return 0 on error.
641 */
642static noinline int
643find_usage_forwards(struct lock_class *source, unsigned int depth)
644{
645 struct lock_list *entry;
646 int ret;
647
648 if (depth > max_recursion_depth)
649 max_recursion_depth = depth;
Ingo Molnarca268c62006-10-17 00:09:28 -0700650 if (depth >= RECURSION_LIMIT)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700651 return print_infinite_recursion_bug();
652
653 debug_atomic_inc(&nr_find_usage_forwards_checks);
654 if (source->usage_mask & (1 << find_usage_bit)) {
655 forwards_match = source;
656 return 2;
657 }
658
659 /*
660 * Check this lock's dependency list:
661 */
662 list_for_each_entry(entry, &source->locks_after, entry) {
663 debug_atomic_inc(&nr_find_usage_forwards_recursions);
664 ret = find_usage_forwards(entry->class, depth+1);
665 if (ret == 2 || ret == 0)
666 return ret;
667 }
668 return 1;
669}
670
671/*
672 * Find a node in the backwards-direction dependency sub-graph starting
673 * at <source> that matches <find_usage_bit>.
674 *
675 * Return 2 if such a node exists in the subgraph, and put that node
676 * into <backwards_match>.
677 *
678 * Return 1 otherwise and keep <backwards_match> unchanged.
679 * Return 0 on error.
680 */
681static noinline int
682find_usage_backwards(struct lock_class *source, unsigned int depth)
683{
684 struct lock_list *entry;
685 int ret;
686
687 if (depth > max_recursion_depth)
688 max_recursion_depth = depth;
Ingo Molnarca268c62006-10-17 00:09:28 -0700689 if (depth >= RECURSION_LIMIT)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700690 return print_infinite_recursion_bug();
691
692 debug_atomic_inc(&nr_find_usage_backwards_checks);
693 if (source->usage_mask & (1 << find_usage_bit)) {
694 backwards_match = source;
695 return 2;
696 }
697
698 /*
699 * Check this lock's dependency list:
700 */
701 list_for_each_entry(entry, &source->locks_before, entry) {
702 debug_atomic_inc(&nr_find_usage_backwards_recursions);
703 ret = find_usage_backwards(entry->class, depth+1);
704 if (ret == 2 || ret == 0)
705 return ret;
706 }
707 return 1;
708}
709
710static int
711print_bad_irq_dependency(struct task_struct *curr,
712 struct held_lock *prev,
713 struct held_lock *next,
714 enum lock_usage_bit bit1,
715 enum lock_usage_bit bit2,
716 const char *irqclass)
717{
718 __raw_spin_unlock(&hash_lock);
719 debug_locks_off();
720 if (debug_locks_silent)
721 return 0;
722
723 printk("\n======================================================\n");
724 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
725 irqclass, irqclass);
Dave Jones99de0552006-09-29 02:00:10 -0700726 print_kernel_version();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700727 printk( "------------------------------------------------------\n");
728 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
729 curr->comm, curr->pid,
730 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
731 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
732 curr->hardirqs_enabled,
733 curr->softirqs_enabled);
734 print_lock(next);
735
736 printk("\nand this task is already holding:\n");
737 print_lock(prev);
738 printk("which would create a new lock dependency:\n");
739 print_lock_name(prev->class);
740 printk(" ->");
741 print_lock_name(next->class);
742 printk("\n");
743
744 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
745 irqclass);
746 print_lock_name(backwards_match);
747 printk("\n... which became %s-irq-safe at:\n", irqclass);
748
749 print_stack_trace(backwards_match->usage_traces + bit1, 1);
750
751 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
752 print_lock_name(forwards_match);
753 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
754 printk("...");
755
756 print_stack_trace(forwards_match->usage_traces + bit2, 1);
757
758 printk("\nother info that might help us debug this:\n\n");
759 lockdep_print_held_locks(curr);
760
761 printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
762 print_lock_dependencies(backwards_match, 0);
763
764 printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
765 print_lock_dependencies(forwards_match, 0);
766
767 printk("\nstack backtrace:\n");
768 dump_stack();
769
770 return 0;
771}
772
773static int
774check_usage(struct task_struct *curr, struct held_lock *prev,
775 struct held_lock *next, enum lock_usage_bit bit_backwards,
776 enum lock_usage_bit bit_forwards, const char *irqclass)
777{
778 int ret;
779
780 find_usage_bit = bit_backwards;
781 /* fills in <backwards_match> */
782 ret = find_usage_backwards(prev->class, 0);
783 if (!ret || ret == 1)
784 return ret;
785
786 find_usage_bit = bit_forwards;
787 ret = find_usage_forwards(next->class, 0);
788 if (!ret || ret == 1)
789 return ret;
790 /* ret == 2 */
791 return print_bad_irq_dependency(curr, prev, next,
792 bit_backwards, bit_forwards, irqclass);
793}
794
795#endif
796
797static int
798print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
799 struct held_lock *next)
800{
801 debug_locks_off();
802 __raw_spin_unlock(&hash_lock);
803 if (debug_locks_silent)
804 return 0;
805
806 printk("\n=============================================\n");
807 printk( "[ INFO: possible recursive locking detected ]\n");
Dave Jones99de0552006-09-29 02:00:10 -0700808 print_kernel_version();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700809 printk( "---------------------------------------------\n");
810 printk("%s/%d is trying to acquire lock:\n",
811 curr->comm, curr->pid);
812 print_lock(next);
813 printk("\nbut task is already holding lock:\n");
814 print_lock(prev);
815
816 printk("\nother info that might help us debug this:\n");
817 lockdep_print_held_locks(curr);
818
819 printk("\nstack backtrace:\n");
820 dump_stack();
821
822 return 0;
823}
824
825/*
826 * Check whether we are holding such a class already.
827 *
828 * (Note that this has to be done separately, because the graph cannot
829 * detect such classes of deadlocks.)
830 *
831 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
832 */
833static int
834check_deadlock(struct task_struct *curr, struct held_lock *next,
835 struct lockdep_map *next_instance, int read)
836{
837 struct held_lock *prev;
838 int i;
839
840 for (i = 0; i < curr->lockdep_depth; i++) {
841 prev = curr->held_locks + i;
842 if (prev->class != next->class)
843 continue;
844 /*
845 * Allow read-after-read recursion of the same
Ingo Molnar6c9076e2006-07-03 00:24:51 -0700846 * lock class (i.e. read_lock(lock)+read_lock(lock)):
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700847 */
Ingo Molnar6c9076e2006-07-03 00:24:51 -0700848 if ((read == 2) && prev->read)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700849 return 2;
850 return print_deadlock_bug(curr, prev, next);
851 }
852 return 1;
853}
854
855/*
856 * There was a chain-cache miss, and we are about to add a new dependency
857 * to a previous lock. We recursively validate the following rules:
858 *
859 * - would the adding of the <prev> -> <next> dependency create a
860 * circular dependency in the graph? [== circular deadlock]
861 *
862 * - does the new prev->next dependency connect any hardirq-safe lock
863 * (in the full backwards-subgraph starting at <prev>) with any
864 * hardirq-unsafe lock (in the full forwards-subgraph starting at
865 * <next>)? [== illegal lock inversion with hardirq contexts]
866 *
867 * - does the new prev->next dependency connect any softirq-safe lock
868 * (in the full backwards-subgraph starting at <prev>) with any
869 * softirq-unsafe lock (in the full forwards-subgraph starting at
870 * <next>)? [== illegal lock inversion with softirq contexts]
871 *
872 * any of these scenarios could lead to a deadlock.
873 *
874 * Then if all the validations pass, we add the forwards and backwards
875 * dependency.
876 */
877static int
878check_prev_add(struct task_struct *curr, struct held_lock *prev,
879 struct held_lock *next)
880{
881 struct lock_list *entry;
882 int ret;
883
884 /*
885 * Prove that the new <prev> -> <next> dependency would not
886 * create a circular dependency in the graph. (We do this by
887 * forward-recursing into the graph starting at <next>, and
888 * checking whether we can reach <prev>.)
889 *
890 * We are using global variables to control the recursion, to
891 * keep the stackframe size of the recursive functions low:
892 */
893 check_source = next;
894 check_target = prev;
895 if (!(check_noncircular(next->class, 0)))
896 return print_circular_bug_tail();
897
898#ifdef CONFIG_TRACE_IRQFLAGS
899 /*
900 * Prove that the new dependency does not connect a hardirq-safe
901 * lock with a hardirq-unsafe lock - to achieve this we search
902 * the backwards-subgraph starting at <prev>, and the
903 * forwards-subgraph starting at <next>:
904 */
905 if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
906 LOCK_ENABLED_HARDIRQS, "hard"))
907 return 0;
908
909 /*
910 * Prove that the new dependency does not connect a hardirq-safe-read
911 * lock with a hardirq-unsafe lock - to achieve this we search
912 * the backwards-subgraph starting at <prev>, and the
913 * forwards-subgraph starting at <next>:
914 */
915 if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
916 LOCK_ENABLED_HARDIRQS, "hard-read"))
917 return 0;
918
919 /*
920 * Prove that the new dependency does not connect a softirq-safe
921 * lock with a softirq-unsafe lock - to achieve this we search
922 * the backwards-subgraph starting at <prev>, and the
923 * forwards-subgraph starting at <next>:
924 */
925 if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
926 LOCK_ENABLED_SOFTIRQS, "soft"))
927 return 0;
928 /*
929 * Prove that the new dependency does not connect a softirq-safe-read
930 * lock with a softirq-unsafe lock - to achieve this we search
931 * the backwards-subgraph starting at <prev>, and the
932 * forwards-subgraph starting at <next>:
933 */
934 if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
935 LOCK_ENABLED_SOFTIRQS, "soft"))
936 return 0;
937#endif
938 /*
939 * For recursive read-locks we do all the dependency checks,
940 * but we dont store read-triggered dependencies (only
941 * write-triggered dependencies). This ensures that only the
942 * write-side dependencies matter, and that if for example a
943 * write-lock never takes any other locks, then the reads are
944 * equivalent to a NOP.
945 */
946 if (next->read == 2 || prev->read == 2)
947 return 1;
948 /*
949 * Is the <prev> -> <next> dependency already present?
950 *
951 * (this may occur even though this is a new chain: consider
952 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
953 * chains - the second one will be new, but L1 already has
954 * L2 added to its dependency list, due to the first chain.)
955 */
956 list_for_each_entry(entry, &prev->class->locks_after, entry) {
957 if (entry->class == next->class)
958 return 2;
959 }
960
961 /*
962 * Ok, all validations passed, add the new lock
963 * to the previous lock's dependency list:
964 */
965 ret = add_lock_to_list(prev->class, next->class,
966 &prev->class->locks_after, next->acquire_ip);
967 if (!ret)
968 return 0;
969 /*
970 * Return value of 2 signals 'dependency already added',
971 * in that case we dont have to add the backlink either.
972 */
973 if (ret == 2)
974 return 2;
975 ret = add_lock_to_list(next->class, prev->class,
976 &next->class->locks_before, next->acquire_ip);
977
978 /*
979 * Debugging printouts:
980 */
981 if (verbose(prev->class) || verbose(next->class)) {
982 __raw_spin_unlock(&hash_lock);
983 printk("\n new dependency: ");
984 print_lock_name(prev->class);
985 printk(" => ");
986 print_lock_name(next->class);
987 printk("\n");
988 dump_stack();
989 __raw_spin_lock(&hash_lock);
990 }
991 return 1;
992}
993
994/*
995 * Add the dependency to all directly-previous locks that are 'relevant'.
996 * The ones that are relevant are (in increasing distance from curr):
997 * all consecutive trylock entries and the final non-trylock entry - or
998 * the end of this context's lock-chain - whichever comes first.
999 */
1000static int
1001check_prevs_add(struct task_struct *curr, struct held_lock *next)
1002{
1003 int depth = curr->lockdep_depth;
1004 struct held_lock *hlock;
1005
1006 /*
1007 * Debugging checks.
1008 *
1009 * Depth must not be zero for a non-head lock:
1010 */
1011 if (!depth)
1012 goto out_bug;
1013 /*
1014 * At least two relevant locks must exist for this
1015 * to be a head:
1016 */
1017 if (curr->held_locks[depth].irq_context !=
1018 curr->held_locks[depth-1].irq_context)
1019 goto out_bug;
1020
1021 for (;;) {
1022 hlock = curr->held_locks + depth-1;
1023 /*
1024 * Only non-recursive-read entries get new dependencies
1025 * added:
1026 */
1027 if (hlock->read != 2) {
1028 check_prev_add(curr, hlock, next);
1029 /*
1030 * Stop after the first non-trylock entry,
1031 * as non-trylock entries have added their
1032 * own direct dependencies already, so this
1033 * lock is connected to them indirectly:
1034 */
1035 if (!hlock->trylock)
1036 break;
1037 }
1038 depth--;
1039 /*
1040 * End of lock-stack?
1041 */
1042 if (!depth)
1043 break;
1044 /*
1045 * Stop the search if we cross into another context:
1046 */
1047 if (curr->held_locks[depth].irq_context !=
1048 curr->held_locks[depth-1].irq_context)
1049 break;
1050 }
1051 return 1;
1052out_bug:
1053 __raw_spin_unlock(&hash_lock);
1054 DEBUG_LOCKS_WARN_ON(1);
1055
1056 return 0;
1057}
1058
1059
1060/*
1061 * Is this the address of a static object:
1062 */
1063static int static_obj(void *obj)
1064{
1065 unsigned long start = (unsigned long) &_stext,
1066 end = (unsigned long) &_end,
1067 addr = (unsigned long) obj;
1068#ifdef CONFIG_SMP
1069 int i;
1070#endif
1071
1072 /*
1073 * static variable?
1074 */
1075 if ((addr >= start) && (addr < end))
1076 return 1;
1077
1078#ifdef CONFIG_SMP
1079 /*
1080 * percpu var?
1081 */
1082 for_each_possible_cpu(i) {
1083 start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
Ingo Molnar1ff56832006-11-17 19:57:22 +01001084 end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
1085 + per_cpu_offset(i);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001086
1087 if ((addr >= start) && (addr < end))
1088 return 1;
1089 }
1090#endif
1091
1092 /*
1093 * module var?
1094 */
1095 return is_module_address(addr);
1096}
1097
1098/*
1099 * To make lock name printouts unique, we calculate a unique
1100 * class->name_version generation counter:
1101 */
1102static int count_matching_names(struct lock_class *new_class)
1103{
1104 struct lock_class *class;
1105 int count = 0;
1106
1107 if (!new_class->name)
1108 return 0;
1109
1110 list_for_each_entry(class, &all_lock_classes, lock_entry) {
1111 if (new_class->key - new_class->subclass == class->key)
1112 return class->name_version;
1113 if (class->name && !strcmp(class->name, new_class->name))
1114 count = max(count, class->name_version);
1115 }
1116
1117 return count + 1;
1118}
1119
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001120/*
1121 * Register a lock's class in the hash-table, if the class is not present
1122 * yet. Otherwise we look it up. We cache the result in the lock object
1123 * itself, so actual lookup of the hash should be once per lock object.
1124 */
1125static inline struct lock_class *
Ingo Molnard6d897c2006-07-10 04:44:04 -07001126look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001127{
1128 struct lockdep_subclass_key *key;
1129 struct list_head *hash_head;
1130 struct lock_class *class;
1131
1132#ifdef CONFIG_DEBUG_LOCKDEP
1133 /*
1134 * If the architecture calls into lockdep before initializing
1135 * the hashes then we'll warn about it later. (we cannot printk
1136 * right now)
1137 */
1138 if (unlikely(!lockdep_initialized)) {
1139 lockdep_init();
1140 lockdep_init_error = 1;
1141 }
1142#endif
1143
1144 /*
1145 * Static locks do not have their class-keys yet - for them the key
1146 * is the lock object itself:
1147 */
1148 if (unlikely(!lock->key))
1149 lock->key = (void *)lock;
1150
1151 /*
1152 * NOTE: the class-key must be unique. For dynamic locks, a static
1153 * lock_class_key variable is passed in through the mutex_init()
1154 * (or spin_lock_init()) call - which acts as the key. For static
1155 * locks we use the lock object itself as the key.
1156 */
Alexey Dobriyan3dc30992006-10-11 01:22:06 -07001157 BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(struct lock_class));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001158
1159 key = lock->key->subkeys + subclass;
1160
1161 hash_head = classhashentry(key);
1162
1163 /*
1164 * We can walk the hash lockfree, because the hash only
1165 * grows, and we are careful when adding entries to the end:
1166 */
1167 list_for_each_entry(class, hash_head, hash_entry)
1168 if (class->key == key)
Ingo Molnard6d897c2006-07-10 04:44:04 -07001169 return class;
1170
1171 return NULL;
1172}
1173
1174/*
1175 * Register a lock's class in the hash-table, if the class is not present
1176 * yet. Otherwise we look it up. We cache the result in the lock object
1177 * itself, so actual lookup of the hash should be once per lock object.
1178 */
1179static inline struct lock_class *
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04001180register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
Ingo Molnard6d897c2006-07-10 04:44:04 -07001181{
1182 struct lockdep_subclass_key *key;
1183 struct list_head *hash_head;
1184 struct lock_class *class;
1185
1186 class = look_up_lock_class(lock, subclass);
1187 if (likely(class))
1188 return class;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001189
1190 /*
1191 * Debug-check: all keys must be persistent!
1192 */
1193 if (!static_obj(lock->key)) {
1194 debug_locks_off();
1195 printk("INFO: trying to register non-static key.\n");
1196 printk("the code is fine but needs lockdep annotation.\n");
1197 printk("turning off the locking correctness validator.\n");
1198 dump_stack();
1199
1200 return NULL;
1201 }
1202
Ingo Molnard6d897c2006-07-10 04:44:04 -07001203 key = lock->key->subkeys + subclass;
1204 hash_head = classhashentry(key);
1205
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001206 __raw_spin_lock(&hash_lock);
1207 /*
1208 * We have to do the hash-walk again, to avoid races
1209 * with another CPU:
1210 */
1211 list_for_each_entry(class, hash_head, hash_entry)
1212 if (class->key == key)
1213 goto out_unlock_set;
1214 /*
1215 * Allocate a new key from the static array, and add it to
1216 * the hash:
1217 */
1218 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
1219 __raw_spin_unlock(&hash_lock);
1220 debug_locks_off();
1221 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
1222 printk("turning off the locking correctness validator.\n");
1223 return NULL;
1224 }
1225 class = lock_classes + nr_lock_classes++;
1226 debug_atomic_inc(&nr_unused_locks);
1227 class->key = key;
1228 class->name = lock->name;
1229 class->subclass = subclass;
1230 INIT_LIST_HEAD(&class->lock_entry);
1231 INIT_LIST_HEAD(&class->locks_before);
1232 INIT_LIST_HEAD(&class->locks_after);
1233 class->name_version = count_matching_names(class);
1234 /*
1235 * We use RCU's safe list-add method to make
1236 * parallel walking of the hash-list safe:
1237 */
1238 list_add_tail_rcu(&class->hash_entry, hash_head);
1239
1240 if (verbose(class)) {
1241 __raw_spin_unlock(&hash_lock);
1242 printk("\nnew class %p: %s", class->key, class->name);
1243 if (class->name_version > 1)
1244 printk("#%d", class->name_version);
1245 printk("\n");
1246 dump_stack();
1247 __raw_spin_lock(&hash_lock);
1248 }
1249out_unlock_set:
1250 __raw_spin_unlock(&hash_lock);
1251
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04001252 if (!subclass || force)
Ingo Molnard6d897c2006-07-10 04:44:04 -07001253 lock->class_cache = class;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001254
1255 DEBUG_LOCKS_WARN_ON(class->subclass != subclass);
1256
1257 return class;
1258}
1259
1260/*
1261 * Look up a dependency chain. If the key is not present yet then
1262 * add it and return 0 - in this case the new dependency chain is
1263 * validated. If the key is already hashed, return 1.
1264 */
1265static inline int lookup_chain_cache(u64 chain_key)
1266{
1267 struct list_head *hash_head = chainhashentry(chain_key);
1268 struct lock_chain *chain;
1269
1270 DEBUG_LOCKS_WARN_ON(!irqs_disabled());
1271 /*
1272 * We can walk it lock-free, because entries only get added
1273 * to the hash:
1274 */
1275 list_for_each_entry(chain, hash_head, entry) {
1276 if (chain->chain_key == chain_key) {
1277cache_hit:
1278 debug_atomic_inc(&chain_lookup_hits);
1279 /*
1280 * In the debugging case, force redundant checking
1281 * by returning 1:
1282 */
1283#ifdef CONFIG_DEBUG_LOCKDEP
1284 __raw_spin_lock(&hash_lock);
1285 return 1;
1286#endif
1287 return 0;
1288 }
1289 }
1290 /*
1291 * Allocate a new chain entry from the static array, and add
1292 * it to the hash:
1293 */
1294 __raw_spin_lock(&hash_lock);
1295 /*
1296 * We have to walk the chain again locked - to avoid duplicates:
1297 */
1298 list_for_each_entry(chain, hash_head, entry) {
1299 if (chain->chain_key == chain_key) {
1300 __raw_spin_unlock(&hash_lock);
1301 goto cache_hit;
1302 }
1303 }
1304 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1305 __raw_spin_unlock(&hash_lock);
1306 debug_locks_off();
1307 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1308 printk("turning off the locking correctness validator.\n");
1309 return 0;
1310 }
1311 chain = lock_chains + nr_lock_chains++;
1312 chain->chain_key = chain_key;
1313 list_add_tail_rcu(&chain->entry, hash_head);
1314 debug_atomic_inc(&chain_lookup_misses);
1315#ifdef CONFIG_TRACE_IRQFLAGS
1316 if (current->hardirq_context)
1317 nr_hardirq_chains++;
1318 else {
1319 if (current->softirq_context)
1320 nr_softirq_chains++;
1321 else
1322 nr_process_chains++;
1323 }
1324#else
1325 nr_process_chains++;
1326#endif
1327
1328 return 1;
1329}
1330
1331/*
1332 * We are building curr_chain_key incrementally, so double-check
1333 * it from scratch, to make sure that it's done correctly:
1334 */
1335static void check_chain_key(struct task_struct *curr)
1336{
1337#ifdef CONFIG_DEBUG_LOCKDEP
1338 struct held_lock *hlock, *prev_hlock = NULL;
1339 unsigned int i, id;
1340 u64 chain_key = 0;
1341
1342 for (i = 0; i < curr->lockdep_depth; i++) {
1343 hlock = curr->held_locks + i;
1344 if (chain_key != hlock->prev_chain_key) {
1345 debug_locks_off();
1346 printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1347 curr->lockdep_depth, i,
1348 (unsigned long long)chain_key,
1349 (unsigned long long)hlock->prev_chain_key);
1350 WARN_ON(1);
1351 return;
1352 }
1353 id = hlock->class - lock_classes;
1354 DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS);
1355 if (prev_hlock && (prev_hlock->irq_context !=
1356 hlock->irq_context))
1357 chain_key = 0;
1358 chain_key = iterate_chain_key(chain_key, id);
1359 prev_hlock = hlock;
1360 }
1361 if (chain_key != curr->curr_chain_key) {
1362 debug_locks_off();
1363 printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1364 curr->lockdep_depth, i,
1365 (unsigned long long)chain_key,
1366 (unsigned long long)curr->curr_chain_key);
1367 WARN_ON(1);
1368 }
1369#endif
1370}
1371
1372#ifdef CONFIG_TRACE_IRQFLAGS
1373
1374/*
1375 * print irq inversion bug:
1376 */
1377static int
1378print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
1379 struct held_lock *this, int forwards,
1380 const char *irqclass)
1381{
1382 __raw_spin_unlock(&hash_lock);
1383 debug_locks_off();
1384 if (debug_locks_silent)
1385 return 0;
1386
1387 printk("\n=========================================================\n");
1388 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
Dave Jones99de0552006-09-29 02:00:10 -07001389 print_kernel_version();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001390 printk( "---------------------------------------------------------\n");
1391 printk("%s/%d just changed the state of lock:\n",
1392 curr->comm, curr->pid);
1393 print_lock(this);
1394 if (forwards)
1395 printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
1396 else
1397 printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
1398 print_lock_name(other);
1399 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
1400
1401 printk("\nother info that might help us debug this:\n");
1402 lockdep_print_held_locks(curr);
1403
1404 printk("\nthe first lock's dependencies:\n");
1405 print_lock_dependencies(this->class, 0);
1406
1407 printk("\nthe second lock's dependencies:\n");
1408 print_lock_dependencies(other, 0);
1409
1410 printk("\nstack backtrace:\n");
1411 dump_stack();
1412
1413 return 0;
1414}
1415
1416/*
1417 * Prove that in the forwards-direction subgraph starting at <this>
1418 * there is no lock matching <mask>:
1419 */
1420static int
1421check_usage_forwards(struct task_struct *curr, struct held_lock *this,
1422 enum lock_usage_bit bit, const char *irqclass)
1423{
1424 int ret;
1425
1426 find_usage_bit = bit;
1427 /* fills in <forwards_match> */
1428 ret = find_usage_forwards(this->class, 0);
1429 if (!ret || ret == 1)
1430 return ret;
1431
1432 return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
1433}
1434
1435/*
1436 * Prove that in the backwards-direction subgraph starting at <this>
1437 * there is no lock matching <mask>:
1438 */
1439static int
1440check_usage_backwards(struct task_struct *curr, struct held_lock *this,
1441 enum lock_usage_bit bit, const char *irqclass)
1442{
1443 int ret;
1444
1445 find_usage_bit = bit;
1446 /* fills in <backwards_match> */
1447 ret = find_usage_backwards(this->class, 0);
1448 if (!ret || ret == 1)
1449 return ret;
1450
1451 return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
1452}
1453
1454static inline void print_irqtrace_events(struct task_struct *curr)
1455{
1456 printk("irq event stamp: %u\n", curr->irq_events);
1457 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
1458 print_ip_sym(curr->hardirq_enable_ip);
1459 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
1460 print_ip_sym(curr->hardirq_disable_ip);
1461 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
1462 print_ip_sym(curr->softirq_enable_ip);
1463 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
1464 print_ip_sym(curr->softirq_disable_ip);
1465}
1466
1467#else
1468static inline void print_irqtrace_events(struct task_struct *curr)
1469{
1470}
1471#endif
1472
1473static int
1474print_usage_bug(struct task_struct *curr, struct held_lock *this,
1475 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
1476{
1477 __raw_spin_unlock(&hash_lock);
1478 debug_locks_off();
1479 if (debug_locks_silent)
1480 return 0;
1481
1482 printk("\n=================================\n");
1483 printk( "[ INFO: inconsistent lock state ]\n");
Dave Jones99de0552006-09-29 02:00:10 -07001484 print_kernel_version();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001485 printk( "---------------------------------\n");
1486
1487 printk("inconsistent {%s} -> {%s} usage.\n",
1488 usage_str[prev_bit], usage_str[new_bit]);
1489
1490 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
1491 curr->comm, curr->pid,
1492 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
1493 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
1494 trace_hardirqs_enabled(curr),
1495 trace_softirqs_enabled(curr));
1496 print_lock(this);
1497
1498 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
1499 print_stack_trace(this->class->usage_traces + prev_bit, 1);
1500
1501 print_irqtrace_events(curr);
1502 printk("\nother info that might help us debug this:\n");
1503 lockdep_print_held_locks(curr);
1504
1505 printk("\nstack backtrace:\n");
1506 dump_stack();
1507
1508 return 0;
1509}
1510
1511/*
1512 * Print out an error if an invalid bit is set:
1513 */
1514static inline int
1515valid_state(struct task_struct *curr, struct held_lock *this,
1516 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
1517{
1518 if (unlikely(this->class->usage_mask & (1 << bad_bit)))
1519 return print_usage_bug(curr, this, bad_bit, new_bit);
1520 return 1;
1521}
1522
1523#define STRICT_READ_CHECKS 1
1524
1525/*
1526 * Mark a lock with a usage bit, and validate the state transition:
1527 */
1528static int mark_lock(struct task_struct *curr, struct held_lock *this,
1529 enum lock_usage_bit new_bit, unsigned long ip)
1530{
1531 unsigned int new_mask = 1 << new_bit, ret = 1;
1532
1533 /*
1534 * If already set then do not dirty the cacheline,
1535 * nor do any checks:
1536 */
1537 if (likely(this->class->usage_mask & new_mask))
1538 return 1;
1539
1540 __raw_spin_lock(&hash_lock);
1541 /*
1542 * Make sure we didnt race:
1543 */
1544 if (unlikely(this->class->usage_mask & new_mask)) {
1545 __raw_spin_unlock(&hash_lock);
1546 return 1;
1547 }
1548
1549 this->class->usage_mask |= new_mask;
1550
1551#ifdef CONFIG_TRACE_IRQFLAGS
1552 if (new_bit == LOCK_ENABLED_HARDIRQS ||
1553 new_bit == LOCK_ENABLED_HARDIRQS_READ)
1554 ip = curr->hardirq_enable_ip;
1555 else if (new_bit == LOCK_ENABLED_SOFTIRQS ||
1556 new_bit == LOCK_ENABLED_SOFTIRQS_READ)
1557 ip = curr->softirq_enable_ip;
1558#endif
1559 if (!save_trace(this->class->usage_traces + new_bit))
1560 return 0;
1561
1562 switch (new_bit) {
1563#ifdef CONFIG_TRACE_IRQFLAGS
1564 case LOCK_USED_IN_HARDIRQ:
1565 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1566 return 0;
1567 if (!valid_state(curr, this, new_bit,
1568 LOCK_ENABLED_HARDIRQS_READ))
1569 return 0;
1570 /*
1571 * just marked it hardirq-safe, check that this lock
1572 * took no hardirq-unsafe lock in the past:
1573 */
1574 if (!check_usage_forwards(curr, this,
1575 LOCK_ENABLED_HARDIRQS, "hard"))
1576 return 0;
1577#if STRICT_READ_CHECKS
1578 /*
1579 * just marked it hardirq-safe, check that this lock
1580 * took no hardirq-unsafe-read lock in the past:
1581 */
1582 if (!check_usage_forwards(curr, this,
1583 LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
1584 return 0;
1585#endif
1586 if (hardirq_verbose(this->class))
1587 ret = 2;
1588 break;
1589 case LOCK_USED_IN_SOFTIRQ:
1590 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1591 return 0;
1592 if (!valid_state(curr, this, new_bit,
1593 LOCK_ENABLED_SOFTIRQS_READ))
1594 return 0;
1595 /*
1596 * just marked it softirq-safe, check that this lock
1597 * took no softirq-unsafe lock in the past:
1598 */
1599 if (!check_usage_forwards(curr, this,
1600 LOCK_ENABLED_SOFTIRQS, "soft"))
1601 return 0;
1602#if STRICT_READ_CHECKS
1603 /*
1604 * just marked it softirq-safe, check that this lock
1605 * took no softirq-unsafe-read lock in the past:
1606 */
1607 if (!check_usage_forwards(curr, this,
1608 LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
1609 return 0;
1610#endif
1611 if (softirq_verbose(this->class))
1612 ret = 2;
1613 break;
1614 case LOCK_USED_IN_HARDIRQ_READ:
1615 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
1616 return 0;
1617 /*
1618 * just marked it hardirq-read-safe, check that this lock
1619 * took no hardirq-unsafe lock in the past:
1620 */
1621 if (!check_usage_forwards(curr, this,
1622 LOCK_ENABLED_HARDIRQS, "hard"))
1623 return 0;
1624 if (hardirq_verbose(this->class))
1625 ret = 2;
1626 break;
1627 case LOCK_USED_IN_SOFTIRQ_READ:
1628 if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
1629 return 0;
1630 /*
1631 * just marked it softirq-read-safe, check that this lock
1632 * took no softirq-unsafe lock in the past:
1633 */
1634 if (!check_usage_forwards(curr, this,
1635 LOCK_ENABLED_SOFTIRQS, "soft"))
1636 return 0;
1637 if (softirq_verbose(this->class))
1638 ret = 2;
1639 break;
1640 case LOCK_ENABLED_HARDIRQS:
1641 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1642 return 0;
1643 if (!valid_state(curr, this, new_bit,
1644 LOCK_USED_IN_HARDIRQ_READ))
1645 return 0;
1646 /*
1647 * just marked it hardirq-unsafe, check that no hardirq-safe
1648 * lock in the system ever took it in the past:
1649 */
1650 if (!check_usage_backwards(curr, this,
1651 LOCK_USED_IN_HARDIRQ, "hard"))
1652 return 0;
1653#if STRICT_READ_CHECKS
1654 /*
1655 * just marked it hardirq-unsafe, check that no
1656 * hardirq-safe-read lock in the system ever took
1657 * it in the past:
1658 */
1659 if (!check_usage_backwards(curr, this,
1660 LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
1661 return 0;
1662#endif
1663 if (hardirq_verbose(this->class))
1664 ret = 2;
1665 break;
1666 case LOCK_ENABLED_SOFTIRQS:
1667 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1668 return 0;
1669 if (!valid_state(curr, this, new_bit,
1670 LOCK_USED_IN_SOFTIRQ_READ))
1671 return 0;
1672 /*
1673 * just marked it softirq-unsafe, check that no softirq-safe
1674 * lock in the system ever took it in the past:
1675 */
1676 if (!check_usage_backwards(curr, this,
1677 LOCK_USED_IN_SOFTIRQ, "soft"))
1678 return 0;
1679#if STRICT_READ_CHECKS
1680 /*
1681 * just marked it softirq-unsafe, check that no
1682 * softirq-safe-read lock in the system ever took
1683 * it in the past:
1684 */
1685 if (!check_usage_backwards(curr, this,
1686 LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
1687 return 0;
1688#endif
1689 if (softirq_verbose(this->class))
1690 ret = 2;
1691 break;
1692 case LOCK_ENABLED_HARDIRQS_READ:
1693 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
1694 return 0;
1695#if STRICT_READ_CHECKS
1696 /*
1697 * just marked it hardirq-read-unsafe, check that no
1698 * hardirq-safe lock in the system ever took it in the past:
1699 */
1700 if (!check_usage_backwards(curr, this,
1701 LOCK_USED_IN_HARDIRQ, "hard"))
1702 return 0;
1703#endif
1704 if (hardirq_verbose(this->class))
1705 ret = 2;
1706 break;
1707 case LOCK_ENABLED_SOFTIRQS_READ:
1708 if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
1709 return 0;
1710#if STRICT_READ_CHECKS
1711 /*
1712 * just marked it softirq-read-unsafe, check that no
1713 * softirq-safe lock in the system ever took it in the past:
1714 */
1715 if (!check_usage_backwards(curr, this,
1716 LOCK_USED_IN_SOFTIRQ, "soft"))
1717 return 0;
1718#endif
1719 if (softirq_verbose(this->class))
1720 ret = 2;
1721 break;
1722#endif
1723 case LOCK_USED:
1724 /*
1725 * Add it to the global list of classes:
1726 */
1727 list_add_tail_rcu(&this->class->lock_entry, &all_lock_classes);
1728 debug_atomic_dec(&nr_unused_locks);
1729 break;
1730 default:
1731 debug_locks_off();
1732 WARN_ON(1);
1733 return 0;
1734 }
1735
1736 __raw_spin_unlock(&hash_lock);
1737
1738 /*
1739 * We must printk outside of the hash_lock:
1740 */
1741 if (ret == 2) {
1742 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
1743 print_lock(this);
1744 print_irqtrace_events(curr);
1745 dump_stack();
1746 }
1747
1748 return ret;
1749}
1750
1751#ifdef CONFIG_TRACE_IRQFLAGS
1752/*
1753 * Mark all held locks with a usage bit:
1754 */
1755static int
1756mark_held_locks(struct task_struct *curr, int hardirq, unsigned long ip)
1757{
1758 enum lock_usage_bit usage_bit;
1759 struct held_lock *hlock;
1760 int i;
1761
1762 for (i = 0; i < curr->lockdep_depth; i++) {
1763 hlock = curr->held_locks + i;
1764
1765 if (hardirq) {
1766 if (hlock->read)
1767 usage_bit = LOCK_ENABLED_HARDIRQS_READ;
1768 else
1769 usage_bit = LOCK_ENABLED_HARDIRQS;
1770 } else {
1771 if (hlock->read)
1772 usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
1773 else
1774 usage_bit = LOCK_ENABLED_SOFTIRQS;
1775 }
1776 if (!mark_lock(curr, hlock, usage_bit, ip))
1777 return 0;
1778 }
1779
1780 return 1;
1781}
1782
1783/*
1784 * Debugging helper: via this flag we know that we are in
1785 * 'early bootup code', and will warn about any invalid irqs-on event:
1786 */
1787static int early_boot_irqs_enabled;
1788
1789void early_boot_irqs_off(void)
1790{
1791 early_boot_irqs_enabled = 0;
1792}
1793
1794void early_boot_irqs_on(void)
1795{
1796 early_boot_irqs_enabled = 1;
1797}
1798
1799/*
1800 * Hardirqs will be enabled:
1801 */
1802void trace_hardirqs_on(void)
1803{
1804 struct task_struct *curr = current;
1805 unsigned long ip;
1806
1807 if (unlikely(!debug_locks || current->lockdep_recursion))
1808 return;
1809
1810 if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
1811 return;
1812
1813 if (unlikely(curr->hardirqs_enabled)) {
1814 debug_atomic_inc(&redundant_hardirqs_on);
1815 return;
1816 }
1817 /* we'll do an OFF -> ON transition: */
1818 curr->hardirqs_enabled = 1;
1819 ip = (unsigned long) __builtin_return_address(0);
1820
1821 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1822 return;
1823 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
1824 return;
1825 /*
1826 * We are going to turn hardirqs on, so set the
1827 * usage bit for all held locks:
1828 */
1829 if (!mark_held_locks(curr, 1, ip))
1830 return;
1831 /*
1832 * If we have softirqs enabled, then set the usage
1833 * bit for all held locks. (disabled hardirqs prevented
1834 * this bit from being set before)
1835 */
1836 if (curr->softirqs_enabled)
1837 if (!mark_held_locks(curr, 0, ip))
1838 return;
1839
1840 curr->hardirq_enable_ip = ip;
1841 curr->hardirq_enable_event = ++curr->irq_events;
1842 debug_atomic_inc(&hardirqs_on_events);
1843}
1844
1845EXPORT_SYMBOL(trace_hardirqs_on);
1846
1847/*
1848 * Hardirqs were disabled:
1849 */
1850void trace_hardirqs_off(void)
1851{
1852 struct task_struct *curr = current;
1853
1854 if (unlikely(!debug_locks || current->lockdep_recursion))
1855 return;
1856
1857 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1858 return;
1859
1860 if (curr->hardirqs_enabled) {
1861 /*
1862 * We have done an ON -> OFF transition:
1863 */
1864 curr->hardirqs_enabled = 0;
1865 curr->hardirq_disable_ip = _RET_IP_;
1866 curr->hardirq_disable_event = ++curr->irq_events;
1867 debug_atomic_inc(&hardirqs_off_events);
1868 } else
1869 debug_atomic_inc(&redundant_hardirqs_off);
1870}
1871
1872EXPORT_SYMBOL(trace_hardirqs_off);
1873
1874/*
1875 * Softirqs will be enabled:
1876 */
1877void trace_softirqs_on(unsigned long ip)
1878{
1879 struct task_struct *curr = current;
1880
1881 if (unlikely(!debug_locks))
1882 return;
1883
1884 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1885 return;
1886
1887 if (curr->softirqs_enabled) {
1888 debug_atomic_inc(&redundant_softirqs_on);
1889 return;
1890 }
1891
1892 /*
1893 * We'll do an OFF -> ON transition:
1894 */
1895 curr->softirqs_enabled = 1;
1896 curr->softirq_enable_ip = ip;
1897 curr->softirq_enable_event = ++curr->irq_events;
1898 debug_atomic_inc(&softirqs_on_events);
1899 /*
1900 * We are going to turn softirqs on, so set the
1901 * usage bit for all held locks, if hardirqs are
1902 * enabled too:
1903 */
1904 if (curr->hardirqs_enabled)
1905 mark_held_locks(curr, 0, ip);
1906}
1907
1908/*
1909 * Softirqs were disabled:
1910 */
1911void trace_softirqs_off(unsigned long ip)
1912{
1913 struct task_struct *curr = current;
1914
1915 if (unlikely(!debug_locks))
1916 return;
1917
1918 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1919 return;
1920
1921 if (curr->softirqs_enabled) {
1922 /*
1923 * We have done an ON -> OFF transition:
1924 */
1925 curr->softirqs_enabled = 0;
1926 curr->softirq_disable_ip = ip;
1927 curr->softirq_disable_event = ++curr->irq_events;
1928 debug_atomic_inc(&softirqs_off_events);
1929 DEBUG_LOCKS_WARN_ON(!softirq_count());
1930 } else
1931 debug_atomic_inc(&redundant_softirqs_off);
1932}
1933
1934#endif
1935
1936/*
1937 * Initialize a lock instance's lock-class mapping info:
1938 */
1939void lockdep_init_map(struct lockdep_map *lock, const char *name,
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04001940 struct lock_class_key *key, int subclass)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001941{
1942 if (unlikely(!debug_locks))
1943 return;
1944
1945 if (DEBUG_LOCKS_WARN_ON(!key))
1946 return;
1947 if (DEBUG_LOCKS_WARN_ON(!name))
1948 return;
1949 /*
1950 * Sanity check, the lock-class key must be persistent:
1951 */
1952 if (!static_obj(key)) {
1953 printk("BUG: key %p not in .data!\n", key);
1954 DEBUG_LOCKS_WARN_ON(1);
1955 return;
1956 }
1957 lock->name = name;
1958 lock->key = key;
Ingo Molnard6d897c2006-07-10 04:44:04 -07001959 lock->class_cache = NULL;
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04001960 if (subclass)
1961 register_lock_class(lock, subclass, 1);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001962}
1963
1964EXPORT_SYMBOL_GPL(lockdep_init_map);
1965
1966/*
1967 * This gets called for every mutex_lock*()/spin_lock*() operation.
1968 * We maintain the dependency maps and validate the locking attempt:
1969 */
1970static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
1971 int trylock, int read, int check, int hardirqs_off,
1972 unsigned long ip)
1973{
1974 struct task_struct *curr = current;
Ingo Molnard6d897c2006-07-10 04:44:04 -07001975 struct lock_class *class = NULL;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001976 struct held_lock *hlock;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001977 unsigned int depth, id;
1978 int chain_head = 0;
1979 u64 chain_key;
1980
1981 if (unlikely(!debug_locks))
1982 return 0;
1983
1984 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1985 return 0;
1986
1987 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
1988 debug_locks_off();
1989 printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
1990 printk("turning off the locking correctness validator.\n");
1991 return 0;
1992 }
1993
Ingo Molnard6d897c2006-07-10 04:44:04 -07001994 if (!subclass)
1995 class = lock->class_cache;
1996 /*
1997 * Not cached yet or subclass?
1998 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001999 if (unlikely(!class)) {
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04002000 class = register_lock_class(lock, subclass, 0);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002001 if (!class)
2002 return 0;
2003 }
2004 debug_atomic_inc((atomic_t *)&class->ops);
2005 if (very_verbose(class)) {
2006 printk("\nacquire class [%p] %s", class->key, class->name);
2007 if (class->name_version > 1)
2008 printk("#%d", class->name_version);
2009 printk("\n");
2010 dump_stack();
2011 }
2012
2013 /*
2014 * Add the lock to the list of currently held locks.
2015 * (we dont increase the depth just yet, up until the
2016 * dependency checks are done)
2017 */
2018 depth = curr->lockdep_depth;
2019 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2020 return 0;
2021
2022 hlock = curr->held_locks + depth;
2023
2024 hlock->class = class;
2025 hlock->acquire_ip = ip;
2026 hlock->instance = lock;
2027 hlock->trylock = trylock;
2028 hlock->read = read;
2029 hlock->check = check;
2030 hlock->hardirqs_off = hardirqs_off;
2031
2032 if (check != 2)
2033 goto out_calc_hash;
2034#ifdef CONFIG_TRACE_IRQFLAGS
2035 /*
2036 * If non-trylock use in a hardirq or softirq context, then
2037 * mark the lock as used in these contexts:
2038 */
2039 if (!trylock) {
2040 if (read) {
2041 if (curr->hardirq_context)
2042 if (!mark_lock(curr, hlock,
2043 LOCK_USED_IN_HARDIRQ_READ, ip))
2044 return 0;
2045 if (curr->softirq_context)
2046 if (!mark_lock(curr, hlock,
2047 LOCK_USED_IN_SOFTIRQ_READ, ip))
2048 return 0;
2049 } else {
2050 if (curr->hardirq_context)
2051 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ, ip))
2052 return 0;
2053 if (curr->softirq_context)
2054 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ, ip))
2055 return 0;
2056 }
2057 }
2058 if (!hardirqs_off) {
2059 if (read) {
2060 if (!mark_lock(curr, hlock,
2061 LOCK_ENABLED_HARDIRQS_READ, ip))
2062 return 0;
2063 if (curr->softirqs_enabled)
2064 if (!mark_lock(curr, hlock,
2065 LOCK_ENABLED_SOFTIRQS_READ, ip))
2066 return 0;
2067 } else {
2068 if (!mark_lock(curr, hlock,
2069 LOCK_ENABLED_HARDIRQS, ip))
2070 return 0;
2071 if (curr->softirqs_enabled)
2072 if (!mark_lock(curr, hlock,
2073 LOCK_ENABLED_SOFTIRQS, ip))
2074 return 0;
2075 }
2076 }
2077#endif
2078 /* mark it as used: */
2079 if (!mark_lock(curr, hlock, LOCK_USED, ip))
2080 return 0;
2081out_calc_hash:
2082 /*
2083 * Calculate the chain hash: it's the combined has of all the
2084 * lock keys along the dependency chain. We save the hash value
2085 * at every step so that we can get the current hash easily
2086 * after unlock. The chain hash is then used to cache dependency
2087 * results.
2088 *
2089 * The 'key ID' is what is the most compact key value to drive
2090 * the hash, not class->key.
2091 */
2092 id = class - lock_classes;
2093 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2094 return 0;
2095
2096 chain_key = curr->curr_chain_key;
2097 if (!depth) {
2098 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2099 return 0;
2100 chain_head = 1;
2101 }
2102
2103 hlock->prev_chain_key = chain_key;
2104
2105#ifdef CONFIG_TRACE_IRQFLAGS
2106 /*
2107 * Keep track of points where we cross into an interrupt context:
2108 */
2109 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2110 curr->softirq_context;
2111 if (depth) {
2112 struct held_lock *prev_hlock;
2113
2114 prev_hlock = curr->held_locks + depth-1;
2115 /*
2116 * If we cross into another context, reset the
2117 * hash key (this also prevents the checking and the
2118 * adding of the dependency to 'prev'):
2119 */
2120 if (prev_hlock->irq_context != hlock->irq_context) {
2121 chain_key = 0;
2122 chain_head = 1;
2123 }
2124 }
2125#endif
2126 chain_key = iterate_chain_key(chain_key, id);
2127 curr->curr_chain_key = chain_key;
2128
2129 /*
2130 * Trylock needs to maintain the stack of held locks, but it
2131 * does not add new dependencies, because trylock can be done
2132 * in any order.
2133 *
2134 * We look up the chain_key and do the O(N^2) check and update of
2135 * the dependencies only if this is a new dependency chain.
2136 * (If lookup_chain_cache() returns with 1 it acquires
2137 * hash_lock for us)
2138 */
2139 if (!trylock && (check == 2) && lookup_chain_cache(chain_key)) {
2140 /*
2141 * Check whether last held lock:
2142 *
2143 * - is irq-safe, if this lock is irq-unsafe
2144 * - is softirq-safe, if this lock is hardirq-unsafe
2145 *
2146 * And check whether the new lock's dependency graph
2147 * could lead back to the previous lock.
2148 *
2149 * any of these scenarios could lead to a deadlock. If
2150 * All validations
2151 */
2152 int ret = check_deadlock(curr, hlock, lock, read);
2153
2154 if (!ret)
2155 return 0;
2156 /*
2157 * Mark recursive read, as we jump over it when
2158 * building dependencies (just like we jump over
2159 * trylock entries):
2160 */
2161 if (ret == 2)
2162 hlock->read = 2;
2163 /*
2164 * Add dependency only if this lock is not the head
2165 * of the chain, and if it's not a secondary read-lock:
2166 */
2167 if (!chain_head && ret != 2)
2168 if (!check_prevs_add(curr, hlock))
2169 return 0;
2170 __raw_spin_unlock(&hash_lock);
2171 }
2172 curr->lockdep_depth++;
2173 check_chain_key(curr);
2174 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2175 debug_locks_off();
2176 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2177 printk("turning off the locking correctness validator.\n");
2178 return 0;
2179 }
2180 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2181 max_lockdep_depth = curr->lockdep_depth;
2182
2183 return 1;
2184}
2185
2186static int
2187print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
2188 unsigned long ip)
2189{
2190 if (!debug_locks_off())
2191 return 0;
2192 if (debug_locks_silent)
2193 return 0;
2194
2195 printk("\n=====================================\n");
2196 printk( "[ BUG: bad unlock balance detected! ]\n");
2197 printk( "-------------------------------------\n");
2198 printk("%s/%d is trying to release lock (",
2199 curr->comm, curr->pid);
2200 print_lockdep_cache(lock);
2201 printk(") at:\n");
2202 print_ip_sym(ip);
2203 printk("but there are no more locks to release!\n");
2204 printk("\nother info that might help us debug this:\n");
2205 lockdep_print_held_locks(curr);
2206
2207 printk("\nstack backtrace:\n");
2208 dump_stack();
2209
2210 return 0;
2211}
2212
2213/*
2214 * Common debugging checks for both nested and non-nested unlock:
2215 */
2216static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
2217 unsigned long ip)
2218{
2219 if (unlikely(!debug_locks))
2220 return 0;
2221 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2222 return 0;
2223
2224 if (curr->lockdep_depth <= 0)
2225 return print_unlock_inbalance_bug(curr, lock, ip);
2226
2227 return 1;
2228}
2229
2230/*
2231 * Remove the lock to the list of currently held locks in a
2232 * potentially non-nested (out of order) manner. This is a
2233 * relatively rare operation, as all the unlock APIs default
2234 * to nested mode (which uses lock_release()):
2235 */
2236static int
2237lock_release_non_nested(struct task_struct *curr,
2238 struct lockdep_map *lock, unsigned long ip)
2239{
2240 struct held_lock *hlock, *prev_hlock;
2241 unsigned int depth;
2242 int i;
2243
2244 /*
2245 * Check whether the lock exists in the current stack
2246 * of held locks:
2247 */
2248 depth = curr->lockdep_depth;
2249 if (DEBUG_LOCKS_WARN_ON(!depth))
2250 return 0;
2251
2252 prev_hlock = NULL;
2253 for (i = depth-1; i >= 0; i--) {
2254 hlock = curr->held_locks + i;
2255 /*
2256 * We must not cross into another context:
2257 */
2258 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2259 break;
2260 if (hlock->instance == lock)
2261 goto found_it;
2262 prev_hlock = hlock;
2263 }
2264 return print_unlock_inbalance_bug(curr, lock, ip);
2265
2266found_it:
2267 /*
2268 * We have the right lock to unlock, 'hlock' points to it.
2269 * Now we remove it from the stack, and add back the other
2270 * entries (if any), recalculating the hash along the way:
2271 */
2272 curr->lockdep_depth = i;
2273 curr->curr_chain_key = hlock->prev_chain_key;
2274
2275 for (i++; i < depth; i++) {
2276 hlock = curr->held_locks + i;
2277 if (!__lock_acquire(hlock->instance,
2278 hlock->class->subclass, hlock->trylock,
2279 hlock->read, hlock->check, hlock->hardirqs_off,
2280 hlock->acquire_ip))
2281 return 0;
2282 }
2283
2284 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
2285 return 0;
2286 return 1;
2287}
2288
2289/*
2290 * Remove the lock to the list of currently held locks - this gets
2291 * called on mutex_unlock()/spin_unlock*() (or on a failed
2292 * mutex_lock_interruptible()). This is done for unlocks that nest
2293 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2294 */
2295static int lock_release_nested(struct task_struct *curr,
2296 struct lockdep_map *lock, unsigned long ip)
2297{
2298 struct held_lock *hlock;
2299 unsigned int depth;
2300
2301 /*
2302 * Pop off the top of the lock stack:
2303 */
2304 depth = curr->lockdep_depth - 1;
2305 hlock = curr->held_locks + depth;
2306
2307 /*
2308 * Is the unlock non-nested:
2309 */
2310 if (hlock->instance != lock)
2311 return lock_release_non_nested(curr, lock, ip);
2312 curr->lockdep_depth--;
2313
2314 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
2315 return 0;
2316
2317 curr->curr_chain_key = hlock->prev_chain_key;
2318
2319#ifdef CONFIG_DEBUG_LOCKDEP
2320 hlock->prev_chain_key = 0;
2321 hlock->class = NULL;
2322 hlock->acquire_ip = 0;
2323 hlock->irq_context = 0;
2324#endif
2325 return 1;
2326}
2327
2328/*
2329 * Remove the lock to the list of currently held locks - this gets
2330 * called on mutex_unlock()/spin_unlock*() (or on a failed
2331 * mutex_lock_interruptible()). This is done for unlocks that nest
2332 * perfectly. (i.e. the current top of the lock-stack is unlocked)
2333 */
2334static void
2335__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2336{
2337 struct task_struct *curr = current;
2338
2339 if (!check_unlock(curr, lock, ip))
2340 return;
2341
2342 if (nested) {
2343 if (!lock_release_nested(curr, lock, ip))
2344 return;
2345 } else {
2346 if (!lock_release_non_nested(curr, lock, ip))
2347 return;
2348 }
2349
2350 check_chain_key(curr);
2351}
2352
2353/*
2354 * Check whether we follow the irq-flags state precisely:
2355 */
2356static void check_flags(unsigned long flags)
2357{
2358#if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
2359 if (!debug_locks)
2360 return;
2361
2362 if (irqs_disabled_flags(flags))
2363 DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled);
2364 else
2365 DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled);
2366
2367 /*
2368 * We dont accurately track softirq state in e.g.
2369 * hardirq contexts (such as on 4KSTACKS), so only
2370 * check if not in hardirq contexts:
2371 */
2372 if (!hardirq_count()) {
2373 if (softirq_count())
2374 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
2375 else
2376 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
2377 }
2378
2379 if (!debug_locks)
2380 print_irqtrace_events(current);
2381#endif
2382}
2383
2384/*
2385 * We are not always called with irqs disabled - do that here,
2386 * and also avoid lockdep recursion:
2387 */
2388void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2389 int trylock, int read, int check, unsigned long ip)
2390{
2391 unsigned long flags;
2392
2393 if (unlikely(current->lockdep_recursion))
2394 return;
2395
2396 raw_local_irq_save(flags);
2397 check_flags(flags);
2398
2399 current->lockdep_recursion = 1;
2400 __lock_acquire(lock, subclass, trylock, read, check,
2401 irqs_disabled_flags(flags), ip);
2402 current->lockdep_recursion = 0;
2403 raw_local_irq_restore(flags);
2404}
2405
2406EXPORT_SYMBOL_GPL(lock_acquire);
2407
2408void lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
2409{
2410 unsigned long flags;
2411
2412 if (unlikely(current->lockdep_recursion))
2413 return;
2414
2415 raw_local_irq_save(flags);
2416 check_flags(flags);
2417 current->lockdep_recursion = 1;
2418 __lock_release(lock, nested, ip);
2419 current->lockdep_recursion = 0;
2420 raw_local_irq_restore(flags);
2421}
2422
2423EXPORT_SYMBOL_GPL(lock_release);
2424
2425/*
2426 * Used by the testsuite, sanitize the validator state
2427 * after a simulated failure:
2428 */
2429
2430void lockdep_reset(void)
2431{
2432 unsigned long flags;
2433
2434 raw_local_irq_save(flags);
2435 current->curr_chain_key = 0;
2436 current->lockdep_depth = 0;
2437 current->lockdep_recursion = 0;
2438 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
2439 nr_hardirq_chains = 0;
2440 nr_softirq_chains = 0;
2441 nr_process_chains = 0;
2442 debug_locks = 1;
2443 raw_local_irq_restore(flags);
2444}
2445
2446static void zap_class(struct lock_class *class)
2447{
2448 int i;
2449
2450 /*
2451 * Remove all dependencies this lock is
2452 * involved in:
2453 */
2454 for (i = 0; i < nr_list_entries; i++) {
2455 if (list_entries[i].class == class)
2456 list_del_rcu(&list_entries[i].entry);
2457 }
2458 /*
2459 * Unhash the class and remove it from the all_lock_classes list:
2460 */
2461 list_del_rcu(&class->hash_entry);
2462 list_del_rcu(&class->lock_entry);
2463
2464}
2465
2466static inline int within(void *addr, void *start, unsigned long size)
2467{
2468 return addr >= start && addr < start + size;
2469}
2470
2471void lockdep_free_key_range(void *start, unsigned long size)
2472{
2473 struct lock_class *class, *next;
2474 struct list_head *head;
2475 unsigned long flags;
2476 int i;
2477
2478 raw_local_irq_save(flags);
2479 __raw_spin_lock(&hash_lock);
2480
2481 /*
2482 * Unhash all classes that were created by this module:
2483 */
2484 for (i = 0; i < CLASSHASH_SIZE; i++) {
2485 head = classhash_table + i;
2486 if (list_empty(head))
2487 continue;
2488 list_for_each_entry_safe(class, next, head, hash_entry)
2489 if (within(class->key, start, size))
2490 zap_class(class);
2491 }
2492
2493 __raw_spin_unlock(&hash_lock);
2494 raw_local_irq_restore(flags);
2495}
2496
2497void lockdep_reset_lock(struct lockdep_map *lock)
2498{
Ingo Molnard6d897c2006-07-10 04:44:04 -07002499 struct lock_class *class, *next;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002500 struct list_head *head;
2501 unsigned long flags;
2502 int i, j;
2503
2504 raw_local_irq_save(flags);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002505
2506 /*
Ingo Molnard6d897c2006-07-10 04:44:04 -07002507 * Remove all classes this lock might have:
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002508 */
Ingo Molnard6d897c2006-07-10 04:44:04 -07002509 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
2510 /*
2511 * If the class exists we look it up and zap it:
2512 */
2513 class = look_up_lock_class(lock, j);
2514 if (class)
2515 zap_class(class);
2516 }
2517 /*
2518 * Debug check: in the end all mapped classes should
2519 * be gone.
2520 */
2521 __raw_spin_lock(&hash_lock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002522 for (i = 0; i < CLASSHASH_SIZE; i++) {
2523 head = classhash_table + i;
2524 if (list_empty(head))
2525 continue;
2526 list_for_each_entry_safe(class, next, head, hash_entry) {
Ingo Molnard6d897c2006-07-10 04:44:04 -07002527 if (unlikely(class == lock->class_cache)) {
2528 __raw_spin_unlock(&hash_lock);
2529 DEBUG_LOCKS_WARN_ON(1);
2530 goto out_restore;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002531 }
2532 }
2533 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002534 __raw_spin_unlock(&hash_lock);
Ingo Molnard6d897c2006-07-10 04:44:04 -07002535
2536out_restore:
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002537 raw_local_irq_restore(flags);
2538}
2539
2540void __init lockdep_init(void)
2541{
2542 int i;
2543
2544 /*
2545 * Some architectures have their own start_kernel()
2546 * code which calls lockdep_init(), while we also
2547 * call lockdep_init() from the start_kernel() itself,
2548 * and we want to initialize the hashes only once:
2549 */
2550 if (lockdep_initialized)
2551 return;
2552
2553 for (i = 0; i < CLASSHASH_SIZE; i++)
2554 INIT_LIST_HEAD(classhash_table + i);
2555
2556 for (i = 0; i < CHAINHASH_SIZE; i++)
2557 INIT_LIST_HEAD(chainhash_table + i);
2558
2559 lockdep_initialized = 1;
2560}
2561
2562void __init lockdep_info(void)
2563{
2564 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
2565
2566 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
2567 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
2568 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
2569 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
2570 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
2571 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
2572 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
2573
2574 printk(" memory used by lock dependency info: %lu kB\n",
2575 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
2576 sizeof(struct list_head) * CLASSHASH_SIZE +
2577 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
2578 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
2579 sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
2580
2581 printk(" per task-struct memory footprint: %lu bytes\n",
2582 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
2583
2584#ifdef CONFIG_DEBUG_LOCKDEP
2585 if (lockdep_init_error)
2586 printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n");
2587#endif
2588}
2589
2590static inline int in_range(const void *start, const void *addr, const void *end)
2591{
2592 return addr >= start && addr <= end;
2593}
2594
2595static void
2596print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
Arjan van de Ven55794a42006-07-10 04:44:03 -07002597 const void *mem_to, struct held_lock *hlock)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002598{
2599 if (!debug_locks_off())
2600 return;
2601 if (debug_locks_silent)
2602 return;
2603
2604 printk("\n=========================\n");
2605 printk( "[ BUG: held lock freed! ]\n");
2606 printk( "-------------------------\n");
2607 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
2608 curr->comm, curr->pid, mem_from, mem_to-1);
Arjan van de Ven55794a42006-07-10 04:44:03 -07002609 print_lock(hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002610 lockdep_print_held_locks(curr);
2611
2612 printk("\nstack backtrace:\n");
2613 dump_stack();
2614}
2615
2616/*
2617 * Called when kernel memory is freed (or unmapped), or if a lock
2618 * is destroyed or reinitialized - this code checks whether there is
2619 * any held lock in the memory range of <from> to <to>:
2620 */
2621void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
2622{
2623 const void *mem_to = mem_from + mem_len, *lock_from, *lock_to;
2624 struct task_struct *curr = current;
2625 struct held_lock *hlock;
2626 unsigned long flags;
2627 int i;
2628
2629 if (unlikely(!debug_locks))
2630 return;
2631
2632 local_irq_save(flags);
2633 for (i = 0; i < curr->lockdep_depth; i++) {
2634 hlock = curr->held_locks + i;
2635
2636 lock_from = (void *)hlock->instance;
2637 lock_to = (void *)(hlock->instance + 1);
2638
2639 if (!in_range(mem_from, lock_from, mem_to) &&
2640 !in_range(mem_from, lock_to, mem_to))
2641 continue;
2642
Arjan van de Ven55794a42006-07-10 04:44:03 -07002643 print_freed_lock_bug(curr, mem_from, mem_to, hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002644 break;
2645 }
2646 local_irq_restore(flags);
2647}
2648
2649static void print_held_locks_bug(struct task_struct *curr)
2650{
2651 if (!debug_locks_off())
2652 return;
2653 if (debug_locks_silent)
2654 return;
2655
2656 printk("\n=====================================\n");
2657 printk( "[ BUG: lock held at task exit time! ]\n");
2658 printk( "-------------------------------------\n");
2659 printk("%s/%d is exiting with locks still held!\n",
2660 curr->comm, curr->pid);
2661 lockdep_print_held_locks(curr);
2662
2663 printk("\nstack backtrace:\n");
2664 dump_stack();
2665}
2666
2667void debug_check_no_locks_held(struct task_struct *task)
2668{
2669 if (unlikely(task->lockdep_depth > 0))
2670 print_held_locks_bug(task);
2671}
2672
2673void debug_show_all_locks(void)
2674{
2675 struct task_struct *g, *p;
2676 int count = 10;
2677 int unlock = 1;
2678
2679 printk("\nShowing all locks held in the system:\n");
2680
2681 /*
2682 * Here we try to get the tasklist_lock as hard as possible,
2683 * if not successful after 2 seconds we ignore it (but keep
2684 * trying). This is to enable a debug printout even if a
2685 * tasklist_lock-holding task deadlocks or crashes.
2686 */
2687retry:
2688 if (!read_trylock(&tasklist_lock)) {
2689 if (count == 10)
2690 printk("hm, tasklist_lock locked, retrying... ");
2691 if (count) {
2692 count--;
2693 printk(" #%d", 10-count);
2694 mdelay(200);
2695 goto retry;
2696 }
2697 printk(" ignoring it.\n");
2698 unlock = 0;
2699 }
2700 if (count != 10)
2701 printk(" locked it.\n");
2702
2703 do_each_thread(g, p) {
2704 if (p->lockdep_depth)
2705 lockdep_print_held_locks(p);
2706 if (!unlock)
2707 if (read_trylock(&tasklist_lock))
2708 unlock = 1;
2709 } while_each_thread(g, p);
2710
2711 printk("\n");
2712 printk("=============================================\n\n");
2713
2714 if (unlock)
2715 read_unlock(&tasklist_lock);
2716}
2717
2718EXPORT_SYMBOL_GPL(debug_show_all_locks);
2719
2720void debug_show_held_locks(struct task_struct *task)
2721{
2722 lockdep_print_held_locks(task);
2723}
2724
2725EXPORT_SYMBOL_GPL(debug_show_held_locks);
2726