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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 *
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -07008 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070010 *
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 */
Steven Rostedta5e25882008-12-02 15:34:05 -050028#define DISABLE_BRANCH_PROFILING
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070029#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>
Dave Jones99de0552006-09-29 02:00:10 -070041#include <linux/utsname.h>
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -070042#include <linux/hash.h>
Steven Rostedt81d68a92008-05-12 21:20:42 +020043#include <linux/ftrace.h>
Peter Zijlstrab4b136f2009-01-29 14:50:36 +010044#include <linux/stringify.h>
Ming Leid588e462009-07-16 15:44:29 +020045#include <linux/bitops.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090046#include <linux/gfp.h>
Peter Zijlstraaf012962009-07-16 15:44:29 +020047
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070048#include <asm/sections.h>
49
50#include "lockdep_internals.h"
51
Steven Rostedta8d154b2009-04-10 09:36:00 -040052#define CREATE_TRACE_POINTS
Frederic Weisbecker67178762009-11-13 10:06:34 +010053#include <trace/events/lock.h>
Steven Rostedta8d154b2009-04-10 09:36:00 -040054
Peter Zijlstraf20786f2007-07-19 01:48:56 -070055#ifdef CONFIG_PROVE_LOCKING
56int prove_locking = 1;
57module_param(prove_locking, int, 0644);
58#else
59#define prove_locking 0
60#endif
61
62#ifdef CONFIG_LOCK_STAT
63int lock_stat = 1;
64module_param(lock_stat, int, 0644);
65#else
66#define lock_stat 0
67#endif
68
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070069/*
Ingo Molnar74c383f2006-12-13 00:34:43 -080070 * lockdep_lock: protects the lockdep graph, the hashes and the
71 * class/list/hash allocators.
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070072 *
73 * This is one of the rare exceptions where it's justified
74 * to use a raw spinlock - we really dont want the spinlock
Ingo Molnar74c383f2006-12-13 00:34:43 -080075 * code to recurse back into the lockdep code...
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070076 */
Thomas Gleixneredc35bd2009-12-03 12:38:57 +010077static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
Ingo Molnar74c383f2006-12-13 00:34:43 -080078
79static int graph_lock(void)
80{
Thomas Gleixner0199c4e2009-12-02 20:01:25 +010081 arch_spin_lock(&lockdep_lock);
Ingo Molnar74c383f2006-12-13 00:34:43 -080082 /*
83 * Make sure that if another CPU detected a bug while
84 * walking the graph we dont change it (while the other
85 * CPU is busy printing out stuff with the graph lock
86 * dropped already)
87 */
88 if (!debug_locks) {
Thomas Gleixner0199c4e2009-12-02 20:01:25 +010089 arch_spin_unlock(&lockdep_lock);
Ingo Molnar74c383f2006-12-13 00:34:43 -080090 return 0;
91 }
Steven Rostedtbb065af2008-05-12 21:21:00 +020092 /* prevent any recursions within lockdep from causing deadlocks */
93 current->lockdep_recursion++;
Ingo Molnar74c383f2006-12-13 00:34:43 -080094 return 1;
95}
96
97static inline int graph_unlock(void)
98{
Thomas Gleixner0199c4e2009-12-02 20:01:25 +010099 if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
Jarek Poplawski381a2292007-02-10 01:44:58 -0800100 return DEBUG_LOCKS_WARN_ON(1);
101
Steven Rostedtbb065af2008-05-12 21:21:00 +0200102 current->lockdep_recursion--;
Thomas Gleixner0199c4e2009-12-02 20:01:25 +0100103 arch_spin_unlock(&lockdep_lock);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800104 return 0;
105}
106
107/*
108 * Turn lock debugging off and return with 0 if it was off already,
109 * and also release the graph lock:
110 */
111static inline int debug_locks_off_graph_unlock(void)
112{
113 int ret = debug_locks_off();
114
Thomas Gleixner0199c4e2009-12-02 20:01:25 +0100115 arch_spin_unlock(&lockdep_lock);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800116
117 return ret;
118}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700119
120static int lockdep_initialized;
121
122unsigned long nr_list_entries;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200123static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700124
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700125/*
126 * All data structures here are protected by the global debug_lock.
127 *
128 * Mutex key structs only get allocated, once during bootup, and never
129 * get freed - this significantly simplifies the debugging code.
130 */
131unsigned long nr_lock_classes;
132static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
133
Dave Jonesf82b2172008-08-11 09:30:23 +0200134static inline struct lock_class *hlock_class(struct held_lock *hlock)
135{
136 if (!hlock->class_idx) {
137 DEBUG_LOCKS_WARN_ON(1);
138 return NULL;
139 }
140 return lock_classes + hlock->class_idx - 1;
141}
142
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700143#ifdef CONFIG_LOCK_STAT
Tejun Heo1871e522009-10-29 22:34:13 +0900144static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
145 cpu_lock_stats);
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700146
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200147static inline u64 lockstat_clock(void)
148{
Peter Zijlstrac6763292010-05-25 10:48:51 +0200149 return local_clock();
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200150}
151
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200152static int lock_point(unsigned long points[], unsigned long ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700153{
154 int i;
155
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200156 for (i = 0; i < LOCKSTAT_POINTS; i++) {
157 if (points[i] == 0) {
158 points[i] = ip;
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700159 break;
160 }
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200161 if (points[i] == ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700162 break;
163 }
164
165 return i;
166}
167
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200168static void lock_time_inc(struct lock_time *lt, u64 time)
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700169{
170 if (time > lt->max)
171 lt->max = time;
172
Frank Rowand109d71c2009-11-19 13:42:06 -0800173 if (time < lt->min || !lt->nr)
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700174 lt->min = time;
175
176 lt->total += time;
177 lt->nr++;
178}
179
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700180static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
181{
Frank Rowand109d71c2009-11-19 13:42:06 -0800182 if (!src->nr)
183 return;
184
185 if (src->max > dst->max)
186 dst->max = src->max;
187
188 if (src->min < dst->min || !dst->nr)
189 dst->min = src->min;
190
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700191 dst->total += src->total;
192 dst->nr += src->nr;
193}
194
195struct lock_class_stats lock_stats(struct lock_class *class)
196{
197 struct lock_class_stats stats;
198 int cpu, i;
199
200 memset(&stats, 0, sizeof(struct lock_class_stats));
201 for_each_possible_cpu(cpu) {
202 struct lock_class_stats *pcs =
Tejun Heo1871e522009-10-29 22:34:13 +0900203 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700204
205 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
206 stats.contention_point[i] += pcs->contention_point[i];
207
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200208 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
209 stats.contending_point[i] += pcs->contending_point[i];
210
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700211 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
212 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
213
214 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
215 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
Peter Zijlstra96645672007-07-19 01:49:00 -0700216
217 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
218 stats.bounces[i] += pcs->bounces[i];
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700219 }
220
221 return stats;
222}
223
224void clear_lock_stats(struct lock_class *class)
225{
226 int cpu;
227
228 for_each_possible_cpu(cpu) {
229 struct lock_class_stats *cpu_stats =
Tejun Heo1871e522009-10-29 22:34:13 +0900230 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700231
232 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
233 }
234 memset(class->contention_point, 0, sizeof(class->contention_point));
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200235 memset(class->contending_point, 0, sizeof(class->contending_point));
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700236}
237
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700238static struct lock_class_stats *get_lock_stats(struct lock_class *class)
239{
Tejun Heo1871e522009-10-29 22:34:13 +0900240 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700241}
242
243static void put_lock_stats(struct lock_class_stats *stats)
244{
Tejun Heo1871e522009-10-29 22:34:13 +0900245 put_cpu_var(cpu_lock_stats);
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700246}
247
248static void lock_release_holdtime(struct held_lock *hlock)
249{
250 struct lock_class_stats *stats;
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200251 u64 holdtime;
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700252
253 if (!lock_stat)
254 return;
255
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200256 holdtime = lockstat_clock() - hlock->holdtime_stamp;
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700257
Dave Jonesf82b2172008-08-11 09:30:23 +0200258 stats = get_lock_stats(hlock_class(hlock));
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700259 if (hlock->read)
260 lock_time_inc(&stats->read_holdtime, holdtime);
261 else
262 lock_time_inc(&stats->write_holdtime, holdtime);
263 put_lock_stats(stats);
264}
265#else
266static inline void lock_release_holdtime(struct held_lock *hlock)
267{
268}
269#endif
270
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700271/*
272 * We keep a global list of all lock classes. The list only grows,
273 * never shrinks. The list is only accessed with the lockdep
274 * spinlock lock held.
275 */
276LIST_HEAD(all_lock_classes);
277
278/*
279 * The lockdep classes are in a hash-table as well, for fast lookup:
280 */
281#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
282#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700283#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700284#define classhashentry(key) (classhash_table + __classhashfn((key)))
285
286static struct list_head classhash_table[CLASSHASH_SIZE];
287
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700288/*
289 * We put the lock dependency chains into a hash-table as well, to cache
290 * their existence:
291 */
292#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
293#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700294#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700295#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
296
297static struct list_head chainhash_table[CHAINHASH_SIZE];
298
299/*
300 * The hash key of the lock dependency chains is a hash itself too:
301 * it's a hash of all locks taken up to that lock, including that lock.
302 * It's a 64-bit hash, because it's important for the keys to be
303 * unique.
304 */
305#define iterate_chain_key(key1, key2) \
Ingo Molnar03cbc352006-09-29 02:01:46 -0700306 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
307 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700308 (key2))
309
Steven Rostedt1d09daa2008-05-12 21:20:55 +0200310void lockdep_off(void)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700311{
312 current->lockdep_recursion++;
313}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700314EXPORT_SYMBOL(lockdep_off);
315
Steven Rostedt1d09daa2008-05-12 21:20:55 +0200316void lockdep_on(void)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700317{
318 current->lockdep_recursion--;
319}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700320EXPORT_SYMBOL(lockdep_on);
321
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700322/*
323 * Debugging switches:
324 */
325
326#define VERBOSE 0
Ingo Molnar33e94e92006-12-13 00:34:41 -0800327#define VERY_VERBOSE 0
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700328
329#if VERBOSE
330# define HARDIRQ_VERBOSE 1
331# define SOFTIRQ_VERBOSE 1
Nick Piggincf40bd12009-01-21 08:12:39 +0100332# define RECLAIM_VERBOSE 1
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700333#else
334# define HARDIRQ_VERBOSE 0
335# define SOFTIRQ_VERBOSE 0
Nick Piggincf40bd12009-01-21 08:12:39 +0100336# define RECLAIM_VERBOSE 0
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700337#endif
338
Nick Piggincf40bd12009-01-21 08:12:39 +0100339#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700340/*
341 * Quick filtering for interesting events:
342 */
343static int class_filter(struct lock_class *class)
344{
Andi Kleenf9829cc2006-07-10 04:44:01 -0700345#if 0
346 /* Example */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700347 if (class->name_version == 1 &&
Andi Kleenf9829cc2006-07-10 04:44:01 -0700348 !strcmp(class->name, "lockname"))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700349 return 1;
350 if (class->name_version == 1 &&
Andi Kleenf9829cc2006-07-10 04:44:01 -0700351 !strcmp(class->name, "&struct->lockfield"))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700352 return 1;
Andi Kleenf9829cc2006-07-10 04:44:01 -0700353#endif
Ingo Molnara6640892006-12-13 00:34:39 -0800354 /* Filter everything else. 1 would be to allow everything else */
355 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700356}
357#endif
358
359static int verbose(struct lock_class *class)
360{
361#if VERBOSE
362 return class_filter(class);
363#endif
364 return 0;
365}
366
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700367/*
368 * Stack-trace: tightly packed array of stack backtrace
Ingo Molnar74c383f2006-12-13 00:34:43 -0800369 * addresses. Protected by the graph_lock.
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700370 */
371unsigned long nr_stack_trace_entries;
372static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
373
374static int save_trace(struct stack_trace *trace)
375{
376 trace->nr_entries = 0;
377 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
378 trace->entries = stack_trace + nr_stack_trace_entries;
379
Andi Kleen5a1b3992006-09-26 10:52:34 +0200380 trace->skip = 3;
Andi Kleen5a1b3992006-09-26 10:52:34 +0200381
Christoph Hellwigab1b6f02007-05-08 00:23:29 -0700382 save_stack_trace(trace);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700383
Peter Zijlstra4f84f432009-07-20 15:27:04 +0200384 /*
385 * Some daft arches put -1 at the end to indicate its a full trace.
386 *
387 * <rant> this is buggy anyway, since it takes a whole extra entry so a
388 * complete trace that maxes out the entries provided will be reported
389 * as incomplete, friggin useless </rant>
390 */
Luck, Tonyea5b41f2009-12-09 14:29:36 -0800391 if (trace->nr_entries != 0 &&
392 trace->entries[trace->nr_entries-1] == ULONG_MAX)
Peter Zijlstra4f84f432009-07-20 15:27:04 +0200393 trace->nr_entries--;
394
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700395 trace->max_entries = trace->nr_entries;
396
397 nr_stack_trace_entries += trace->nr_entries;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700398
Peter Zijlstra4f84f432009-07-20 15:27:04 +0200399 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
Ingo Molnar74c383f2006-12-13 00:34:43 -0800400 if (!debug_locks_off_graph_unlock())
401 return 0;
402
403 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
404 printk("turning off the locking correctness validator.\n");
405 dump_stack();
406
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700407 return 0;
408 }
409
410 return 1;
411}
412
413unsigned int nr_hardirq_chains;
414unsigned int nr_softirq_chains;
415unsigned int nr_process_chains;
416unsigned int max_lockdep_depth;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700417
418#ifdef CONFIG_DEBUG_LOCKDEP
419/*
420 * We cannot printk in early bootup code. Not even early_printk()
421 * might work. So we mark any initialization errors and printk
422 * about it later on, in lockdep_info().
423 */
424static int lockdep_init_error;
Johannes Bergc71063c2007-07-19 01:49:02 -0700425static unsigned long lockdep_init_trace_data[20];
426static struct stack_trace lockdep_init_trace = {
427 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
428 .entries = lockdep_init_trace_data,
429};
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700430
431/*
432 * Various lockdep statistics:
433 */
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +0200434DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700435#endif
436
437/*
438 * Locking printouts:
439 */
440
Peter Zijlstrafabe9c42009-01-22 14:51:01 +0100441#define __USAGE(__STATE) \
Peter Zijlstrab4b136f2009-01-29 14:50:36 +0100442 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
443 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
444 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
445 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
Peter Zijlstrafabe9c42009-01-22 14:51:01 +0100446
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700447static const char *usage_str[] =
448{
Peter Zijlstrafabe9c42009-01-22 14:51:01 +0100449#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
450#include "lockdep_states.h"
451#undef LOCKDEP_STATE
452 [LOCK_USED] = "INITIAL USE",
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700453};
454
455const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
456{
Alexey Dobriyanffb45122007-05-08 00:28:41 -0700457 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700458}
459
Peter Zijlstra3ff176c2009-01-22 17:40:42 +0100460static inline unsigned long lock_flag(enum lock_usage_bit bit)
461{
462 return 1UL << bit;
463}
464
465static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
466{
467 char c = '.';
468
469 if (class->usage_mask & lock_flag(bit + 2))
470 c = '+';
471 if (class->usage_mask & lock_flag(bit)) {
472 c = '-';
473 if (class->usage_mask & lock_flag(bit + 2))
474 c = '?';
475 }
476
477 return c;
478}
479
Peter Zijlstraf510b232009-01-22 17:53:47 +0100480void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700481{
Peter Zijlstraf510b232009-01-22 17:53:47 +0100482 int i = 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700483
Peter Zijlstraf510b232009-01-22 17:53:47 +0100484#define LOCKDEP_STATE(__STATE) \
485 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
486 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
487#include "lockdep_states.h"
488#undef LOCKDEP_STATE
489
490 usage[i] = '\0';
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700491}
492
Steven Rostedt3003eba2011-04-20 21:41:54 -0400493static int __print_lock_name(struct lock_class *class)
494{
495 char str[KSYM_NAME_LEN];
496 const char *name;
497
498 name = class->name;
499 if (!name)
500 name = __get_key_name(class->key, str);
501
502 return printk("%s", name);
503}
504
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700505static void print_lock_name(struct lock_class *class)
506{
Peter Zijlstraf510b232009-01-22 17:53:47 +0100507 char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700508 const char *name;
509
Peter Zijlstraf510b232009-01-22 17:53:47 +0100510 get_usage_chars(class, usage);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700511
512 name = class->name;
513 if (!name) {
514 name = __get_key_name(class->key, str);
515 printk(" (%s", name);
516 } else {
517 printk(" (%s", name);
518 if (class->name_version > 1)
519 printk("#%d", class->name_version);
520 if (class->subclass)
521 printk("/%d", class->subclass);
522 }
Peter Zijlstraf510b232009-01-22 17:53:47 +0100523 printk("){%s}", usage);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700524}
525
526static void print_lockdep_cache(struct lockdep_map *lock)
527{
528 const char *name;
Tejun Heo9281ace2007-07-17 04:03:51 -0700529 char str[KSYM_NAME_LEN];
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700530
531 name = lock->name;
532 if (!name)
533 name = __get_key_name(lock->key->subkeys, str);
534
535 printk("%s", name);
536}
537
538static void print_lock(struct held_lock *hlock)
539{
Dave Jonesf82b2172008-08-11 09:30:23 +0200540 print_lock_name(hlock_class(hlock));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700541 printk(", at: ");
542 print_ip_sym(hlock->acquire_ip);
543}
544
545static void lockdep_print_held_locks(struct task_struct *curr)
546{
547 int i, depth = curr->lockdep_depth;
548
549 if (!depth) {
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700550 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700551 return;
552 }
553 printk("%d lock%s held by %s/%d:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700554 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700555
556 for (i = 0; i < depth; i++) {
557 printk(" #%d: ", i);
558 print_lock(curr->held_locks + i);
559 }
560}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700561
Dave Jones99de0552006-09-29 02:00:10 -0700562static void print_kernel_version(void)
563{
Serge E. Hallyn96b644b2006-10-02 02:18:13 -0700564 printk("%s %.*s\n", init_utsname()->release,
565 (int)strcspn(init_utsname()->version, " "),
566 init_utsname()->version);
Dave Jones99de0552006-09-29 02:00:10 -0700567}
568
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700569static int very_verbose(struct lock_class *class)
570{
571#if VERY_VERBOSE
572 return class_filter(class);
573#endif
574 return 0;
575}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700576
577/*
578 * Is this the address of a static object:
579 */
580static int static_obj(void *obj)
581{
582 unsigned long start = (unsigned long) &_stext,
583 end = (unsigned long) &_end,
584 addr = (unsigned long) obj;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700585
586 /*
587 * static variable?
588 */
589 if ((addr >= start) && (addr < end))
590 return 1;
591
Mike Frysinger2a9ad182009-09-22 16:44:16 -0700592 if (arch_is_kernel_data(addr))
593 return 1;
594
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700595 /*
Tejun Heo10fad5e2010-03-10 18:57:54 +0900596 * in-kernel percpu var?
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700597 */
Tejun Heo10fad5e2010-03-10 18:57:54 +0900598 if (is_kernel_percpu_address(addr))
599 return 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700600
601 /*
Tejun Heo10fad5e2010-03-10 18:57:54 +0900602 * module static or percpu var?
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700603 */
Tejun Heo10fad5e2010-03-10 18:57:54 +0900604 return is_module_address(addr) || is_module_percpu_address(addr);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700605}
606
607/*
608 * To make lock name printouts unique, we calculate a unique
609 * class->name_version generation counter:
610 */
611static int count_matching_names(struct lock_class *new_class)
612{
613 struct lock_class *class;
614 int count = 0;
615
616 if (!new_class->name)
617 return 0;
618
619 list_for_each_entry(class, &all_lock_classes, lock_entry) {
620 if (new_class->key - new_class->subclass == class->key)
621 return class->name_version;
622 if (class->name && !strcmp(class->name, new_class->name))
623 count = max(count, class->name_version);
624 }
625
626 return count + 1;
627}
628
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700629/*
630 * Register a lock's class in the hash-table, if the class is not present
631 * yet. Otherwise we look it up. We cache the result in the lock object
632 * itself, so actual lookup of the hash should be once per lock object.
633 */
634static inline struct lock_class *
Ingo Molnard6d897c2006-07-10 04:44:04 -0700635look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700636{
637 struct lockdep_subclass_key *key;
638 struct list_head *hash_head;
639 struct lock_class *class;
640
641#ifdef CONFIG_DEBUG_LOCKDEP
642 /*
643 * If the architecture calls into lockdep before initializing
644 * the hashes then we'll warn about it later. (we cannot printk
645 * right now)
646 */
647 if (unlikely(!lockdep_initialized)) {
648 lockdep_init();
649 lockdep_init_error = 1;
Johannes Bergc71063c2007-07-19 01:49:02 -0700650 save_stack_trace(&lockdep_init_trace);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700651 }
652#endif
653
Hitoshi Mitake4ba053c2010-10-13 17:30:26 +0900654 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
655 debug_locks_off();
656 printk(KERN_ERR
657 "BUG: looking up invalid subclass: %u\n", subclass);
658 printk(KERN_ERR
659 "turning off the locking correctness validator.\n");
660 dump_stack();
661 return NULL;
662 }
663
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700664 /*
665 * Static locks do not have their class-keys yet - for them the key
666 * is the lock object itself:
667 */
668 if (unlikely(!lock->key))
669 lock->key = (void *)lock;
670
671 /*
672 * NOTE: the class-key must be unique. For dynamic locks, a static
673 * lock_class_key variable is passed in through the mutex_init()
674 * (or spin_lock_init()) call - which acts as the key. For static
675 * locks we use the lock object itself as the key.
676 */
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700677 BUILD_BUG_ON(sizeof(struct lock_class_key) >
678 sizeof(struct lockdep_map));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700679
680 key = lock->key->subkeys + subclass;
681
682 hash_head = classhashentry(key);
683
684 /*
685 * We can walk the hash lockfree, because the hash only
686 * grows, and we are careful when adding entries to the end:
687 */
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700688 list_for_each_entry(class, hash_head, hash_entry) {
689 if (class->key == key) {
690 WARN_ON_ONCE(class->name != lock->name);
Ingo Molnard6d897c2006-07-10 04:44:04 -0700691 return class;
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700692 }
693 }
Ingo Molnard6d897c2006-07-10 04:44:04 -0700694
695 return NULL;
696}
697
698/*
699 * Register a lock's class in the hash-table, if the class is not present
700 * yet. Otherwise we look it up. We cache the result in the lock object
701 * itself, so actual lookup of the hash should be once per lock object.
702 */
703static inline struct lock_class *
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -0400704register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
Ingo Molnard6d897c2006-07-10 04:44:04 -0700705{
706 struct lockdep_subclass_key *key;
707 struct list_head *hash_head;
708 struct lock_class *class;
Ingo Molnar70e45062006-12-06 20:40:50 -0800709 unsigned long flags;
Ingo Molnard6d897c2006-07-10 04:44:04 -0700710
711 class = look_up_lock_class(lock, subclass);
712 if (likely(class))
713 return class;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700714
715 /*
716 * Debug-check: all keys must be persistent!
717 */
718 if (!static_obj(lock->key)) {
719 debug_locks_off();
720 printk("INFO: trying to register non-static key.\n");
721 printk("the code is fine but needs lockdep annotation.\n");
722 printk("turning off the locking correctness validator.\n");
723 dump_stack();
724
725 return NULL;
726 }
727
Ingo Molnard6d897c2006-07-10 04:44:04 -0700728 key = lock->key->subkeys + subclass;
729 hash_head = classhashentry(key);
730
Ingo Molnar70e45062006-12-06 20:40:50 -0800731 raw_local_irq_save(flags);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800732 if (!graph_lock()) {
733 raw_local_irq_restore(flags);
734 return NULL;
735 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700736 /*
737 * We have to do the hash-walk again, to avoid races
738 * with another CPU:
739 */
740 list_for_each_entry(class, hash_head, hash_entry)
741 if (class->key == key)
742 goto out_unlock_set;
743 /*
744 * Allocate a new key from the static array, and add it to
745 * the hash:
746 */
747 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
Ingo Molnar74c383f2006-12-13 00:34:43 -0800748 if (!debug_locks_off_graph_unlock()) {
749 raw_local_irq_restore(flags);
750 return NULL;
751 }
Ingo Molnar70e45062006-12-06 20:40:50 -0800752 raw_local_irq_restore(flags);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800753
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700754 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
755 printk("turning off the locking correctness validator.\n");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +0100756 dump_stack();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700757 return NULL;
758 }
759 class = lock_classes + nr_lock_classes++;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +0200760 debug_atomic_inc(nr_unused_locks);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700761 class->key = key;
762 class->name = lock->name;
763 class->subclass = subclass;
764 INIT_LIST_HEAD(&class->lock_entry);
765 INIT_LIST_HEAD(&class->locks_before);
766 INIT_LIST_HEAD(&class->locks_after);
767 class->name_version = count_matching_names(class);
768 /*
769 * We use RCU's safe list-add method to make
770 * parallel walking of the hash-list safe:
771 */
772 list_add_tail_rcu(&class->hash_entry, hash_head);
Dale Farnsworth14811972008-02-25 23:03:02 +0100773 /*
774 * Add it to the global list of classes:
775 */
776 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700777
778 if (verbose(class)) {
Ingo Molnar74c383f2006-12-13 00:34:43 -0800779 graph_unlock();
Ingo Molnar70e45062006-12-06 20:40:50 -0800780 raw_local_irq_restore(flags);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800781
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700782 printk("\nnew class %p: %s", class->key, class->name);
783 if (class->name_version > 1)
784 printk("#%d", class->name_version);
785 printk("\n");
786 dump_stack();
Ingo Molnar74c383f2006-12-13 00:34:43 -0800787
Ingo Molnar70e45062006-12-06 20:40:50 -0800788 raw_local_irq_save(flags);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800789 if (!graph_lock()) {
790 raw_local_irq_restore(flags);
791 return NULL;
792 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700793 }
794out_unlock_set:
Ingo Molnar74c383f2006-12-13 00:34:43 -0800795 graph_unlock();
Ingo Molnar70e45062006-12-06 20:40:50 -0800796 raw_local_irq_restore(flags);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700797
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -0400798 if (!subclass || force)
Hitoshi Mitake62016252010-10-05 18:01:51 +0900799 lock->class_cache[0] = class;
800 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
801 lock->class_cache[subclass] = class;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700802
Jarek Poplawski381a2292007-02-10 01:44:58 -0800803 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
804 return NULL;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700805
806 return class;
807}
808
Peter Zijlstraca58abc2007-07-19 01:48:53 -0700809#ifdef CONFIG_PROVE_LOCKING
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700810/*
Peter Zijlstra8e182572007-07-19 01:48:54 -0700811 * Allocate a lockdep entry. (assumes the graph_lock held, returns
812 * with NULL on failure)
813 */
814static struct lock_list *alloc_list_entry(void)
815{
816 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
817 if (!debug_locks_off_graph_unlock())
818 return NULL;
819
820 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
821 printk("turning off the locking correctness validator.\n");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +0100822 dump_stack();
Peter Zijlstra8e182572007-07-19 01:48:54 -0700823 return NULL;
824 }
825 return list_entries + nr_list_entries++;
826}
827
828/*
829 * Add a new dependency to the head of the list:
830 */
831static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
Yong Zhang4726f2a2010-05-04 14:16:48 +0800832 struct list_head *head, unsigned long ip,
833 int distance, struct stack_trace *trace)
Peter Zijlstra8e182572007-07-19 01:48:54 -0700834{
835 struct lock_list *entry;
836 /*
837 * Lock not present yet - get a new dependency struct and
838 * add it to the list:
839 */
840 entry = alloc_list_entry();
841 if (!entry)
842 return 0;
843
Zhu Yi74870172008-08-27 14:33:00 +0800844 entry->class = this;
845 entry->distance = distance;
Yong Zhang4726f2a2010-05-04 14:16:48 +0800846 entry->trace = *trace;
Peter Zijlstra8e182572007-07-19 01:48:54 -0700847 /*
848 * Since we never remove from the dependency list, the list can
849 * be walked lockless by other CPUs, it's only allocation
850 * that must be protected by the spinlock. But this also means
851 * we must make new entries visible only once writes to the
852 * entry become visible - hence the RCU op:
853 */
854 list_add_tail_rcu(&entry->entry, head);
855
856 return 1;
857}
858
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200859/*
860 * For good efficiency of modular, we use power of 2
861 */
Peter Zijlstraaf012962009-07-16 15:44:29 +0200862#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
863#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
864
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200865/*
866 * The circular_queue and helpers is used to implement the
Peter Zijlstraaf012962009-07-16 15:44:29 +0200867 * breadth-first search(BFS)algorithem, by which we can build
868 * the shortest path from the next lock to be acquired to the
869 * previous held lock if there is a circular between them.
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200870 */
Peter Zijlstraaf012962009-07-16 15:44:29 +0200871struct circular_queue {
872 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
873 unsigned int front, rear;
874};
875
876static struct circular_queue lock_cq;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200877
Ming Lei12f3dfd2009-07-16 15:44:29 +0200878unsigned int max_bfs_queue_depth;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200879
Ming Leie351b662009-07-22 22:48:09 +0800880static unsigned int lockdep_dependency_gen_id;
881
Peter Zijlstraaf012962009-07-16 15:44:29 +0200882static inline void __cq_init(struct circular_queue *cq)
883{
884 cq->front = cq->rear = 0;
Ming Leie351b662009-07-22 22:48:09 +0800885 lockdep_dependency_gen_id++;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200886}
887
888static inline int __cq_empty(struct circular_queue *cq)
889{
890 return (cq->front == cq->rear);
891}
892
893static inline int __cq_full(struct circular_queue *cq)
894{
895 return ((cq->rear + 1) & CQ_MASK) == cq->front;
896}
897
898static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
899{
900 if (__cq_full(cq))
901 return -1;
902
903 cq->element[cq->rear] = elem;
904 cq->rear = (cq->rear + 1) & CQ_MASK;
905 return 0;
906}
907
908static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
909{
910 if (__cq_empty(cq))
911 return -1;
912
913 *elem = cq->element[cq->front];
914 cq->front = (cq->front + 1) & CQ_MASK;
915 return 0;
916}
917
918static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
919{
920 return (cq->rear - cq->front) & CQ_MASK;
921}
922
923static inline void mark_lock_accessed(struct lock_list *lock,
924 struct lock_list *parent)
925{
926 unsigned long nr;
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200927
Peter Zijlstraaf012962009-07-16 15:44:29 +0200928 nr = lock - list_entries;
929 WARN_ON(nr >= nr_list_entries);
930 lock->parent = parent;
Ming Leie351b662009-07-22 22:48:09 +0800931 lock->class->dep_gen_id = lockdep_dependency_gen_id;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200932}
933
934static inline unsigned long lock_accessed(struct lock_list *lock)
935{
936 unsigned long nr;
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200937
Peter Zijlstraaf012962009-07-16 15:44:29 +0200938 nr = lock - list_entries;
939 WARN_ON(nr >= nr_list_entries);
Ming Leie351b662009-07-22 22:48:09 +0800940 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200941}
942
943static inline struct lock_list *get_lock_parent(struct lock_list *child)
944{
945 return child->parent;
946}
947
948static inline int get_lock_depth(struct lock_list *child)
949{
950 int depth = 0;
951 struct lock_list *parent;
952
953 while ((parent = get_lock_parent(child))) {
954 child = parent;
955 depth++;
956 }
957 return depth;
958}
959
Ming Lei9e2d5512009-07-16 15:44:29 +0200960static int __bfs(struct lock_list *source_entry,
Peter Zijlstraaf012962009-07-16 15:44:29 +0200961 void *data,
962 int (*match)(struct lock_list *entry, void *data),
963 struct lock_list **target_entry,
964 int forward)
Ming Leic94aa5c2009-07-16 15:44:29 +0200965{
966 struct lock_list *entry;
Ming Leid588e462009-07-16 15:44:29 +0200967 struct list_head *head;
Ming Leic94aa5c2009-07-16 15:44:29 +0200968 struct circular_queue *cq = &lock_cq;
969 int ret = 1;
970
Ming Lei9e2d5512009-07-16 15:44:29 +0200971 if (match(source_entry, data)) {
Ming Leic94aa5c2009-07-16 15:44:29 +0200972 *target_entry = source_entry;
973 ret = 0;
974 goto exit;
975 }
976
Ming Leid588e462009-07-16 15:44:29 +0200977 if (forward)
978 head = &source_entry->class->locks_after;
979 else
980 head = &source_entry->class->locks_before;
981
982 if (list_empty(head))
983 goto exit;
984
985 __cq_init(cq);
Ming Leic94aa5c2009-07-16 15:44:29 +0200986 __cq_enqueue(cq, (unsigned long)source_entry);
987
988 while (!__cq_empty(cq)) {
989 struct lock_list *lock;
Ming Leic94aa5c2009-07-16 15:44:29 +0200990
991 __cq_dequeue(cq, (unsigned long *)&lock);
992
993 if (!lock->class) {
994 ret = -2;
995 goto exit;
996 }
997
998 if (forward)
999 head = &lock->class->locks_after;
1000 else
1001 head = &lock->class->locks_before;
1002
1003 list_for_each_entry(entry, head, entry) {
1004 if (!lock_accessed(entry)) {
Ming Lei12f3dfd2009-07-16 15:44:29 +02001005 unsigned int cq_depth;
Ming Leic94aa5c2009-07-16 15:44:29 +02001006 mark_lock_accessed(entry, lock);
Ming Lei9e2d5512009-07-16 15:44:29 +02001007 if (match(entry, data)) {
Ming Leic94aa5c2009-07-16 15:44:29 +02001008 *target_entry = entry;
1009 ret = 0;
1010 goto exit;
1011 }
1012
1013 if (__cq_enqueue(cq, (unsigned long)entry)) {
1014 ret = -1;
1015 goto exit;
1016 }
Ming Lei12f3dfd2009-07-16 15:44:29 +02001017 cq_depth = __cq_get_elem_count(cq);
1018 if (max_bfs_queue_depth < cq_depth)
1019 max_bfs_queue_depth = cq_depth;
Ming Leic94aa5c2009-07-16 15:44:29 +02001020 }
1021 }
1022 }
1023exit:
1024 return ret;
1025}
1026
Ming Leid7aaba12009-07-16 15:44:29 +02001027static inline int __bfs_forwards(struct lock_list *src_entry,
Ming Lei9e2d5512009-07-16 15:44:29 +02001028 void *data,
1029 int (*match)(struct lock_list *entry, void *data),
1030 struct lock_list **target_entry)
Ming Leic94aa5c2009-07-16 15:44:29 +02001031{
Ming Lei9e2d5512009-07-16 15:44:29 +02001032 return __bfs(src_entry, data, match, target_entry, 1);
Ming Leic94aa5c2009-07-16 15:44:29 +02001033
1034}
1035
Ming Leid7aaba12009-07-16 15:44:29 +02001036static inline int __bfs_backwards(struct lock_list *src_entry,
Ming Lei9e2d5512009-07-16 15:44:29 +02001037 void *data,
1038 int (*match)(struct lock_list *entry, void *data),
1039 struct lock_list **target_entry)
Ming Leic94aa5c2009-07-16 15:44:29 +02001040{
Ming Lei9e2d5512009-07-16 15:44:29 +02001041 return __bfs(src_entry, data, match, target_entry, 0);
Ming Leic94aa5c2009-07-16 15:44:29 +02001042
1043}
1044
Peter Zijlstra8e182572007-07-19 01:48:54 -07001045/*
1046 * Recursive, forwards-direction lock-dependency checking, used for
1047 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1048 * checking.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001049 */
Peter Zijlstra8e182572007-07-19 01:48:54 -07001050
1051/*
1052 * Print a dependency chain entry (this is only done when a deadlock
1053 * has been detected):
1054 */
1055static noinline int
Ming Lei24208ca2009-07-16 15:44:29 +02001056print_circular_bug_entry(struct lock_list *target, int depth)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001057{
1058 if (debug_locks_silent)
1059 return 0;
1060 printk("\n-> #%u", depth);
1061 print_lock_name(target->class);
1062 printk(":\n");
1063 print_stack_trace(&target->trace, 6);
1064
1065 return 0;
1066}
1067
Steven Rostedtf4185812011-04-20 21:41:55 -04001068static void
1069print_circular_lock_scenario(struct held_lock *src,
1070 struct held_lock *tgt,
1071 struct lock_list *prt)
1072{
1073 struct lock_class *source = hlock_class(src);
1074 struct lock_class *target = hlock_class(tgt);
1075 struct lock_class *parent = prt->class;
1076
1077 /*
1078 * A direct locking problem where unsafe_class lock is taken
1079 * directly by safe_class lock, then all we need to show
1080 * is the deadlock scenario, as it is obvious that the
1081 * unsafe lock is taken under the safe lock.
1082 *
1083 * But if there is a chain instead, where the safe lock takes
1084 * an intermediate lock (middle_class) where this lock is
1085 * not the same as the safe lock, then the lock chain is
1086 * used to describe the problem. Otherwise we would need
1087 * to show a different CPU case for each link in the chain
1088 * from the safe_class lock to the unsafe_class lock.
1089 */
1090 if (parent != source) {
1091 printk("Chain exists of:\n ");
1092 __print_lock_name(source);
1093 printk(" --> ");
1094 __print_lock_name(parent);
1095 printk(" --> ");
1096 __print_lock_name(target);
1097 printk("\n\n");
1098 }
1099
1100 printk(" Possible unsafe locking scenario:\n\n");
1101 printk(" CPU0 CPU1\n");
1102 printk(" ---- ----\n");
1103 printk(" lock(");
1104 __print_lock_name(target);
1105 printk(");\n");
1106 printk(" lock(");
1107 __print_lock_name(parent);
1108 printk(");\n");
1109 printk(" lock(");
1110 __print_lock_name(target);
1111 printk(");\n");
1112 printk(" lock(");
1113 __print_lock_name(source);
1114 printk(");\n");
1115 printk("\n *** DEADLOCK ***\n\n");
1116}
1117
Peter Zijlstra8e182572007-07-19 01:48:54 -07001118/*
1119 * When a circular dependency is detected, print the
1120 * header first:
1121 */
1122static noinline int
Ming Leidb0002a2009-07-16 15:44:29 +02001123print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1124 struct held_lock *check_src,
1125 struct held_lock *check_tgt)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001126{
1127 struct task_struct *curr = current;
1128
Ming Leic94aa5c2009-07-16 15:44:29 +02001129 if (debug_locks_silent)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001130 return 0;
1131
1132 printk("\n=======================================================\n");
1133 printk( "[ INFO: possible circular locking dependency detected ]\n");
1134 print_kernel_version();
1135 printk( "-------------------------------------------------------\n");
1136 printk("%s/%d is trying to acquire lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07001137 curr->comm, task_pid_nr(curr));
Ming Leidb0002a2009-07-16 15:44:29 +02001138 print_lock(check_src);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001139 printk("\nbut task is already holding lock:\n");
Ming Leidb0002a2009-07-16 15:44:29 +02001140 print_lock(check_tgt);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001141 printk("\nwhich lock already depends on the new lock.\n\n");
1142 printk("\nthe existing dependency chain (in reverse order) is:\n");
1143
1144 print_circular_bug_entry(entry, depth);
1145
1146 return 0;
1147}
1148
Ming Lei9e2d5512009-07-16 15:44:29 +02001149static inline int class_equal(struct lock_list *entry, void *data)
1150{
1151 return entry->class == data;
1152}
1153
Ming Leidb0002a2009-07-16 15:44:29 +02001154static noinline int print_circular_bug(struct lock_list *this,
1155 struct lock_list *target,
1156 struct held_lock *check_src,
1157 struct held_lock *check_tgt)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001158{
1159 struct task_struct *curr = current;
Ming Leic94aa5c2009-07-16 15:44:29 +02001160 struct lock_list *parent;
Steven Rostedtf4185812011-04-20 21:41:55 -04001161 struct lock_list *first_parent;
Ming Lei24208ca2009-07-16 15:44:29 +02001162 int depth;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001163
Ming Leic94aa5c2009-07-16 15:44:29 +02001164 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001165 return 0;
1166
Ming Leidb0002a2009-07-16 15:44:29 +02001167 if (!save_trace(&this->trace))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001168 return 0;
1169
Ming Leic94aa5c2009-07-16 15:44:29 +02001170 depth = get_lock_depth(target);
1171
Ming Leidb0002a2009-07-16 15:44:29 +02001172 print_circular_bug_header(target, depth, check_src, check_tgt);
Ming Leic94aa5c2009-07-16 15:44:29 +02001173
1174 parent = get_lock_parent(target);
Steven Rostedtf4185812011-04-20 21:41:55 -04001175 first_parent = parent;
Ming Leic94aa5c2009-07-16 15:44:29 +02001176
1177 while (parent) {
1178 print_circular_bug_entry(parent, --depth);
1179 parent = get_lock_parent(parent);
1180 }
Peter Zijlstra8e182572007-07-19 01:48:54 -07001181
1182 printk("\nother info that might help us debug this:\n\n");
Steven Rostedtf4185812011-04-20 21:41:55 -04001183 print_circular_lock_scenario(check_src, check_tgt,
1184 first_parent);
1185
Peter Zijlstra8e182572007-07-19 01:48:54 -07001186 lockdep_print_held_locks(curr);
1187
1188 printk("\nstack backtrace:\n");
1189 dump_stack();
1190
1191 return 0;
1192}
1193
Ming Leidb0002a2009-07-16 15:44:29 +02001194static noinline int print_bfs_bug(int ret)
1195{
1196 if (!debug_locks_off_graph_unlock())
1197 return 0;
1198
1199 WARN(1, "lockdep bfs error:%d\n", ret);
1200
1201 return 0;
1202}
1203
Ming Leief681022009-07-16 15:44:29 +02001204static int noop_count(struct lock_list *entry, void *data)
David Miller419ca3f2008-07-29 21:45:03 -07001205{
Ming Leief681022009-07-16 15:44:29 +02001206 (*(unsigned long *)data)++;
1207 return 0;
David Miller419ca3f2008-07-29 21:45:03 -07001208}
1209
Ming Leief681022009-07-16 15:44:29 +02001210unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1211{
1212 unsigned long count = 0;
1213 struct lock_list *uninitialized_var(target_entry);
1214
1215 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1216
1217 return count;
1218}
David Miller419ca3f2008-07-29 21:45:03 -07001219unsigned long lockdep_count_forward_deps(struct lock_class *class)
1220{
1221 unsigned long ret, flags;
Ming Leief681022009-07-16 15:44:29 +02001222 struct lock_list this;
1223
1224 this.parent = NULL;
1225 this.class = class;
David Miller419ca3f2008-07-29 21:45:03 -07001226
1227 local_irq_save(flags);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001228 arch_spin_lock(&lockdep_lock);
Ming Leief681022009-07-16 15:44:29 +02001229 ret = __lockdep_count_forward_deps(&this);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001230 arch_spin_unlock(&lockdep_lock);
David Miller419ca3f2008-07-29 21:45:03 -07001231 local_irq_restore(flags);
1232
1233 return ret;
1234}
1235
Ming Leief681022009-07-16 15:44:29 +02001236unsigned long __lockdep_count_backward_deps(struct lock_list *this)
David Miller419ca3f2008-07-29 21:45:03 -07001237{
Ming Leief681022009-07-16 15:44:29 +02001238 unsigned long count = 0;
1239 struct lock_list *uninitialized_var(target_entry);
David Miller419ca3f2008-07-29 21:45:03 -07001240
Ming Leief681022009-07-16 15:44:29 +02001241 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
David Miller419ca3f2008-07-29 21:45:03 -07001242
Ming Leief681022009-07-16 15:44:29 +02001243 return count;
David Miller419ca3f2008-07-29 21:45:03 -07001244}
1245
1246unsigned long lockdep_count_backward_deps(struct lock_class *class)
1247{
1248 unsigned long ret, flags;
Ming Leief681022009-07-16 15:44:29 +02001249 struct lock_list this;
1250
1251 this.parent = NULL;
1252 this.class = class;
David Miller419ca3f2008-07-29 21:45:03 -07001253
1254 local_irq_save(flags);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001255 arch_spin_lock(&lockdep_lock);
Ming Leief681022009-07-16 15:44:29 +02001256 ret = __lockdep_count_backward_deps(&this);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001257 arch_spin_unlock(&lockdep_lock);
David Miller419ca3f2008-07-29 21:45:03 -07001258 local_irq_restore(flags);
1259
1260 return ret;
1261}
1262
Peter Zijlstra8e182572007-07-19 01:48:54 -07001263/*
1264 * Prove that the dependency graph starting at <entry> can not
1265 * lead to <target>. Print an error and return 0 if it does.
1266 */
1267static noinline int
Ming Leidb0002a2009-07-16 15:44:29 +02001268check_noncircular(struct lock_list *root, struct lock_class *target,
1269 struct lock_list **target_entry)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001270{
Ming Leidb0002a2009-07-16 15:44:29 +02001271 int result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001272
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001273 debug_atomic_inc(nr_cyclic_checks);
David Miller419ca3f2008-07-29 21:45:03 -07001274
Ming Leid7aaba12009-07-16 15:44:29 +02001275 result = __bfs_forwards(root, target, class_equal, target_entry);
Ming Leidb0002a2009-07-16 15:44:29 +02001276
1277 return result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001278}
1279
Steven Rostedt81d68a92008-05-12 21:20:42 +02001280#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001281/*
1282 * Forwards and backwards subgraph searching, for the purposes of
1283 * proving that two subgraphs can be connected by a new dependency
1284 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1285 */
Peter Zijlstra8e182572007-07-19 01:48:54 -07001286
Ming Leid7aaba12009-07-16 15:44:29 +02001287static inline int usage_match(struct lock_list *entry, void *bit)
1288{
1289 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1290}
1291
1292
1293
Peter Zijlstra8e182572007-07-19 01:48:54 -07001294/*
1295 * Find a node in the forwards-direction dependency sub-graph starting
Ming Leid7aaba12009-07-16 15:44:29 +02001296 * at @root->class that matches @bit.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001297 *
Ming Leid7aaba12009-07-16 15:44:29 +02001298 * Return 0 if such a node exists in the subgraph, and put that node
1299 * into *@target_entry.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001300 *
Ming Leid7aaba12009-07-16 15:44:29 +02001301 * Return 1 otherwise and keep *@target_entry unchanged.
1302 * Return <0 on error.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001303 */
Ming Leid7aaba12009-07-16 15:44:29 +02001304static int
1305find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1306 struct lock_list **target_entry)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001307{
Ming Leid7aaba12009-07-16 15:44:29 +02001308 int result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001309
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001310 debug_atomic_inc(nr_find_usage_forwards_checks);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001311
Ming Leid7aaba12009-07-16 15:44:29 +02001312 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1313
1314 return result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001315}
1316
1317/*
1318 * Find a node in the backwards-direction dependency sub-graph starting
Ming Leid7aaba12009-07-16 15:44:29 +02001319 * at @root->class that matches @bit.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001320 *
Ming Leid7aaba12009-07-16 15:44:29 +02001321 * Return 0 if such a node exists in the subgraph, and put that node
1322 * into *@target_entry.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001323 *
Ming Leid7aaba12009-07-16 15:44:29 +02001324 * Return 1 otherwise and keep *@target_entry unchanged.
1325 * Return <0 on error.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001326 */
Ming Leid7aaba12009-07-16 15:44:29 +02001327static int
1328find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1329 struct lock_list **target_entry)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001330{
Ming Leid7aaba12009-07-16 15:44:29 +02001331 int result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001332
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001333 debug_atomic_inc(nr_find_usage_backwards_checks);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001334
Ming Leid7aaba12009-07-16 15:44:29 +02001335 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
Dave Jonesf82b2172008-08-11 09:30:23 +02001336
Ming Leid7aaba12009-07-16 15:44:29 +02001337 return result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001338}
1339
Peter Zijlstraaf012962009-07-16 15:44:29 +02001340static void print_lock_class_header(struct lock_class *class, int depth)
1341{
1342 int bit;
1343
1344 printk("%*s->", depth, "");
1345 print_lock_name(class);
1346 printk(" ops: %lu", class->ops);
1347 printk(" {\n");
1348
1349 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1350 if (class->usage_mask & (1 << bit)) {
1351 int len = depth;
1352
1353 len += printk("%*s %s", depth, "", usage_str[bit]);
1354 len += printk(" at:\n");
1355 print_stack_trace(class->usage_traces + bit, len);
1356 }
1357 }
1358 printk("%*s }\n", depth, "");
1359
1360 printk("%*s ... key at: ",depth,"");
1361 print_ip_sym((unsigned long)class->key);
1362}
1363
1364/*
1365 * printk the shortest lock dependencies from @start to @end in reverse order:
1366 */
1367static void __used
1368print_shortest_lock_dependencies(struct lock_list *leaf,
1369 struct lock_list *root)
1370{
1371 struct lock_list *entry = leaf;
1372 int depth;
1373
1374 /*compute depth from generated tree by BFS*/
1375 depth = get_lock_depth(leaf);
1376
1377 do {
1378 print_lock_class_header(entry->class, depth);
1379 printk("%*s ... acquired at:\n", depth, "");
1380 print_stack_trace(&entry->trace, 2);
1381 printk("\n");
1382
1383 if (depth == 0 && (entry != root)) {
1384 printk("lockdep:%s bad BFS generated tree\n", __func__);
1385 break;
1386 }
1387
1388 entry = get_lock_parent(entry);
1389 depth--;
1390 } while (entry && (depth >= 0));
1391
1392 return;
1393}
Ming Leid7aaba12009-07-16 15:44:29 +02001394
Steven Rostedt3003eba2011-04-20 21:41:54 -04001395static void
1396print_irq_lock_scenario(struct lock_list *safe_entry,
1397 struct lock_list *unsafe_entry,
1398 struct held_lock *prev,
1399 struct held_lock *next)
1400{
1401 struct lock_class *safe_class = safe_entry->class;
1402 struct lock_class *unsafe_class = unsafe_entry->class;
1403 struct lock_class *middle_class = hlock_class(prev);
1404
1405 if (middle_class == safe_class)
1406 middle_class = hlock_class(next);
1407
1408 /*
1409 * A direct locking problem where unsafe_class lock is taken
1410 * directly by safe_class lock, then all we need to show
1411 * is the deadlock scenario, as it is obvious that the
1412 * unsafe lock is taken under the safe lock.
1413 *
1414 * But if there is a chain instead, where the safe lock takes
1415 * an intermediate lock (middle_class) where this lock is
1416 * not the same as the safe lock, then the lock chain is
1417 * used to describe the problem. Otherwise we would need
1418 * to show a different CPU case for each link in the chain
1419 * from the safe_class lock to the unsafe_class lock.
1420 */
1421 if (middle_class != unsafe_class) {
1422 printk("Chain exists of:\n ");
1423 __print_lock_name(safe_class);
1424 printk(" --> ");
1425 __print_lock_name(middle_class);
1426 printk(" --> ");
1427 __print_lock_name(unsafe_class);
1428 printk("\n\n");
1429 }
1430
1431 printk(" Possible interrupt unsafe locking scenario:\n\n");
1432 printk(" CPU0 CPU1\n");
1433 printk(" ---- ----\n");
1434 printk(" lock(");
1435 __print_lock_name(unsafe_class);
1436 printk(");\n");
1437 printk(" local_irq_disable();\n");
1438 printk(" lock(");
1439 __print_lock_name(safe_class);
1440 printk(");\n");
1441 printk(" lock(");
1442 __print_lock_name(middle_class);
1443 printk(");\n");
1444 printk(" <Interrupt>\n");
1445 printk(" lock(");
1446 __print_lock_name(safe_class);
1447 printk(");\n");
1448 printk("\n *** DEADLOCK ***\n\n");
1449}
1450
Peter Zijlstra8e182572007-07-19 01:48:54 -07001451static int
1452print_bad_irq_dependency(struct task_struct *curr,
Ming Lei24208ca2009-07-16 15:44:29 +02001453 struct lock_list *prev_root,
1454 struct lock_list *next_root,
1455 struct lock_list *backwards_entry,
1456 struct lock_list *forwards_entry,
Peter Zijlstra8e182572007-07-19 01:48:54 -07001457 struct held_lock *prev,
1458 struct held_lock *next,
1459 enum lock_usage_bit bit1,
1460 enum lock_usage_bit bit2,
1461 const char *irqclass)
1462{
1463 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1464 return 0;
1465
1466 printk("\n======================================================\n");
1467 printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1468 irqclass, irqclass);
1469 print_kernel_version();
1470 printk( "------------------------------------------------------\n");
1471 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07001472 curr->comm, task_pid_nr(curr),
Peter Zijlstra8e182572007-07-19 01:48:54 -07001473 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1474 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1475 curr->hardirqs_enabled,
1476 curr->softirqs_enabled);
1477 print_lock(next);
1478
1479 printk("\nand this task is already holding:\n");
1480 print_lock(prev);
1481 printk("which would create a new lock dependency:\n");
Dave Jonesf82b2172008-08-11 09:30:23 +02001482 print_lock_name(hlock_class(prev));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001483 printk(" ->");
Dave Jonesf82b2172008-08-11 09:30:23 +02001484 print_lock_name(hlock_class(next));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001485 printk("\n");
1486
1487 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1488 irqclass);
Ming Lei24208ca2009-07-16 15:44:29 +02001489 print_lock_name(backwards_entry->class);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001490 printk("\n... which became %s-irq-safe at:\n", irqclass);
1491
Ming Lei24208ca2009-07-16 15:44:29 +02001492 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001493
1494 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
Ming Lei24208ca2009-07-16 15:44:29 +02001495 print_lock_name(forwards_entry->class);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001496 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1497 printk("...");
1498
Ming Lei24208ca2009-07-16 15:44:29 +02001499 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001500
1501 printk("\nother info that might help us debug this:\n\n");
Steven Rostedt3003eba2011-04-20 21:41:54 -04001502 print_irq_lock_scenario(backwards_entry, forwards_entry, prev, next);
1503
Peter Zijlstra8e182572007-07-19 01:48:54 -07001504 lockdep_print_held_locks(curr);
1505
Ming Lei24208ca2009-07-16 15:44:29 +02001506 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1507 printk(" and the holding lock:\n");
1508 if (!save_trace(&prev_root->trace))
1509 return 0;
1510 print_shortest_lock_dependencies(backwards_entry, prev_root);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001511
Ming Lei24208ca2009-07-16 15:44:29 +02001512 printk("\nthe dependencies between the lock to be acquired");
1513 printk(" and %s-irq-unsafe lock:\n", irqclass);
1514 if (!save_trace(&next_root->trace))
1515 return 0;
1516 print_shortest_lock_dependencies(forwards_entry, next_root);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001517
1518 printk("\nstack backtrace:\n");
1519 dump_stack();
1520
1521 return 0;
1522}
1523
1524static int
1525check_usage(struct task_struct *curr, struct held_lock *prev,
1526 struct held_lock *next, enum lock_usage_bit bit_backwards,
1527 enum lock_usage_bit bit_forwards, const char *irqclass)
1528{
1529 int ret;
Ming Lei24208ca2009-07-16 15:44:29 +02001530 struct lock_list this, that;
Ming Leid7aaba12009-07-16 15:44:29 +02001531 struct lock_list *uninitialized_var(target_entry);
Ming Lei24208ca2009-07-16 15:44:29 +02001532 struct lock_list *uninitialized_var(target_entry1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001533
Ming Leid7aaba12009-07-16 15:44:29 +02001534 this.parent = NULL;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001535
Ming Leid7aaba12009-07-16 15:44:29 +02001536 this.class = hlock_class(prev);
1537 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
Peter Zijlstraaf012962009-07-16 15:44:29 +02001538 if (ret < 0)
1539 return print_bfs_bug(ret);
1540 if (ret == 1)
1541 return ret;
Ming Leid7aaba12009-07-16 15:44:29 +02001542
Ming Lei24208ca2009-07-16 15:44:29 +02001543 that.parent = NULL;
1544 that.class = hlock_class(next);
1545 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
Peter Zijlstraaf012962009-07-16 15:44:29 +02001546 if (ret < 0)
1547 return print_bfs_bug(ret);
1548 if (ret == 1)
1549 return ret;
Ming Leid7aaba12009-07-16 15:44:29 +02001550
Ming Lei24208ca2009-07-16 15:44:29 +02001551 return print_bad_irq_dependency(curr, &this, &that,
1552 target_entry, target_entry1,
1553 prev, next,
Peter Zijlstra8e182572007-07-19 01:48:54 -07001554 bit_backwards, bit_forwards, irqclass);
1555}
1556
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001557static const char *state_names[] = {
1558#define LOCKDEP_STATE(__STATE) \
Peter Zijlstrab4b136f2009-01-29 14:50:36 +01001559 __stringify(__STATE),
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001560#include "lockdep_states.h"
1561#undef LOCKDEP_STATE
1562};
1563
1564static const char *state_rnames[] = {
1565#define LOCKDEP_STATE(__STATE) \
Peter Zijlstrab4b136f2009-01-29 14:50:36 +01001566 __stringify(__STATE)"-READ",
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001567#include "lockdep_states.h"
1568#undef LOCKDEP_STATE
1569};
1570
1571static inline const char *state_name(enum lock_usage_bit bit)
1572{
1573 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1574}
1575
1576static int exclusive_bit(int new_bit)
1577{
1578 /*
1579 * USED_IN
1580 * USED_IN_READ
1581 * ENABLED
1582 * ENABLED_READ
1583 *
1584 * bit 0 - write/read
1585 * bit 1 - used_in/enabled
1586 * bit 2+ state
1587 */
1588
1589 int state = new_bit & ~3;
1590 int dir = new_bit & 2;
1591
1592 /*
1593 * keep state, bit flip the direction and strip read.
1594 */
1595 return state | (dir ^ 2);
1596}
1597
1598static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1599 struct held_lock *next, enum lock_usage_bit bit)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001600{
1601 /*
1602 * Prove that the new dependency does not connect a hardirq-safe
1603 * lock with a hardirq-unsafe lock - to achieve this we search
1604 * the backwards-subgraph starting at <prev>, and the
1605 * forwards-subgraph starting at <next>:
1606 */
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001607 if (!check_usage(curr, prev, next, bit,
1608 exclusive_bit(bit), state_name(bit)))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001609 return 0;
1610
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001611 bit++; /* _READ */
1612
Peter Zijlstra8e182572007-07-19 01:48:54 -07001613 /*
1614 * Prove that the new dependency does not connect a hardirq-safe-read
1615 * lock with a hardirq-unsafe lock - to achieve this we search
1616 * the backwards-subgraph starting at <prev>, and the
1617 * forwards-subgraph starting at <next>:
1618 */
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001619 if (!check_usage(curr, prev, next, bit,
1620 exclusive_bit(bit), state_name(bit)))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001621 return 0;
1622
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001623 return 1;
1624}
Peter Zijlstra8e182572007-07-19 01:48:54 -07001625
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001626static int
1627check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1628 struct held_lock *next)
1629{
1630#define LOCKDEP_STATE(__STATE) \
1631 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
Nick Piggincf40bd12009-01-21 08:12:39 +01001632 return 0;
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001633#include "lockdep_states.h"
1634#undef LOCKDEP_STATE
Nick Piggincf40bd12009-01-21 08:12:39 +01001635
Peter Zijlstra8e182572007-07-19 01:48:54 -07001636 return 1;
1637}
1638
1639static void inc_chains(void)
1640{
1641 if (current->hardirq_context)
1642 nr_hardirq_chains++;
1643 else {
1644 if (current->softirq_context)
1645 nr_softirq_chains++;
1646 else
1647 nr_process_chains++;
1648 }
1649}
1650
1651#else
1652
1653static inline int
1654check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1655 struct held_lock *next)
1656{
1657 return 1;
1658}
1659
1660static inline void inc_chains(void)
1661{
1662 nr_process_chains++;
1663}
1664
1665#endif
1666
Steven Rostedt48702ec2011-04-20 21:41:56 -04001667static void
1668print_deadlock_scenario(struct held_lock *nxt,
1669 struct held_lock *prv)
1670{
1671 struct lock_class *next = hlock_class(nxt);
1672 struct lock_class *prev = hlock_class(prv);
1673
1674 printk(" Possible unsafe locking scenario:\n\n");
1675 printk(" CPU0\n");
1676 printk(" ----\n");
1677 printk(" lock(");
1678 __print_lock_name(prev);
1679 printk(");\n");
1680 printk(" lock(");
1681 __print_lock_name(next);
1682 printk(");\n");
1683 printk("\n *** DEADLOCK ***\n\n");
1684 printk(" May be due to missing lock nesting notation\n\n");
1685}
1686
Peter Zijlstra8e182572007-07-19 01:48:54 -07001687static int
1688print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1689 struct held_lock *next)
1690{
1691 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1692 return 0;
1693
1694 printk("\n=============================================\n");
1695 printk( "[ INFO: possible recursive locking detected ]\n");
1696 print_kernel_version();
1697 printk( "---------------------------------------------\n");
1698 printk("%s/%d is trying to acquire lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07001699 curr->comm, task_pid_nr(curr));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001700 print_lock(next);
1701 printk("\nbut task is already holding lock:\n");
1702 print_lock(prev);
1703
1704 printk("\nother info that might help us debug this:\n");
Steven Rostedt48702ec2011-04-20 21:41:56 -04001705 print_deadlock_scenario(next, prev);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001706 lockdep_print_held_locks(curr);
1707
1708 printk("\nstack backtrace:\n");
1709 dump_stack();
1710
1711 return 0;
1712}
1713
1714/*
1715 * Check whether we are holding such a class already.
1716 *
1717 * (Note that this has to be done separately, because the graph cannot
1718 * detect such classes of deadlocks.)
1719 *
1720 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1721 */
1722static int
1723check_deadlock(struct task_struct *curr, struct held_lock *next,
1724 struct lockdep_map *next_instance, int read)
1725{
1726 struct held_lock *prev;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001727 struct held_lock *nest = NULL;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001728 int i;
1729
1730 for (i = 0; i < curr->lockdep_depth; i++) {
1731 prev = curr->held_locks + i;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001732
1733 if (prev->instance == next->nest_lock)
1734 nest = prev;
1735
Dave Jonesf82b2172008-08-11 09:30:23 +02001736 if (hlock_class(prev) != hlock_class(next))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001737 continue;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001738
Peter Zijlstra8e182572007-07-19 01:48:54 -07001739 /*
1740 * Allow read-after-read recursion of the same
1741 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1742 */
1743 if ((read == 2) && prev->read)
1744 return 2;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001745
1746 /*
1747 * We're holding the nest_lock, which serializes this lock's
1748 * nesting behaviour.
1749 */
1750 if (nest)
1751 return 2;
1752
Peter Zijlstra8e182572007-07-19 01:48:54 -07001753 return print_deadlock_bug(curr, prev, next);
1754 }
1755 return 1;
1756}
1757
1758/*
1759 * There was a chain-cache miss, and we are about to add a new dependency
1760 * to a previous lock. We recursively validate the following rules:
1761 *
1762 * - would the adding of the <prev> -> <next> dependency create a
1763 * circular dependency in the graph? [== circular deadlock]
1764 *
1765 * - does the new prev->next dependency connect any hardirq-safe lock
1766 * (in the full backwards-subgraph starting at <prev>) with any
1767 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1768 * <next>)? [== illegal lock inversion with hardirq contexts]
1769 *
1770 * - does the new prev->next dependency connect any softirq-safe lock
1771 * (in the full backwards-subgraph starting at <prev>) with any
1772 * softirq-unsafe lock (in the full forwards-subgraph starting at
1773 * <next>)? [== illegal lock inversion with softirq contexts]
1774 *
1775 * any of these scenarios could lead to a deadlock.
1776 *
1777 * Then if all the validations pass, we add the forwards and backwards
1778 * dependency.
1779 */
1780static int
1781check_prev_add(struct task_struct *curr, struct held_lock *prev,
Yong Zhang4726f2a2010-05-04 14:16:48 +08001782 struct held_lock *next, int distance, int trylock_loop)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001783{
1784 struct lock_list *entry;
1785 int ret;
Ming Leidb0002a2009-07-16 15:44:29 +02001786 struct lock_list this;
1787 struct lock_list *uninitialized_var(target_entry);
Yong Zhang4726f2a2010-05-04 14:16:48 +08001788 /*
1789 * Static variable, serialized by the graph_lock().
1790 *
1791 * We use this static variable to save the stack trace in case
1792 * we call into this function multiple times due to encountering
1793 * trylocks in the held lock stack.
1794 */
1795 static struct stack_trace trace;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001796
1797 /*
1798 * Prove that the new <prev> -> <next> dependency would not
1799 * create a circular dependency in the graph. (We do this by
1800 * forward-recursing into the graph starting at <next>, and
1801 * checking whether we can reach <prev>.)
1802 *
1803 * We are using global variables to control the recursion, to
1804 * keep the stackframe size of the recursive functions low:
1805 */
Ming Leidb0002a2009-07-16 15:44:29 +02001806 this.class = hlock_class(next);
1807 this.parent = NULL;
1808 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1809 if (unlikely(!ret))
1810 return print_circular_bug(&this, target_entry, next, prev);
1811 else if (unlikely(ret < 0))
1812 return print_bfs_bug(ret);
Ming Leic94aa5c2009-07-16 15:44:29 +02001813
Peter Zijlstra8e182572007-07-19 01:48:54 -07001814 if (!check_prev_add_irq(curr, prev, next))
1815 return 0;
1816
1817 /*
1818 * For recursive read-locks we do all the dependency checks,
1819 * but we dont store read-triggered dependencies (only
1820 * write-triggered dependencies). This ensures that only the
1821 * write-side dependencies matter, and that if for example a
1822 * write-lock never takes any other locks, then the reads are
1823 * equivalent to a NOP.
1824 */
1825 if (next->read == 2 || prev->read == 2)
1826 return 1;
1827 /*
1828 * Is the <prev> -> <next> dependency already present?
1829 *
1830 * (this may occur even though this is a new chain: consider
1831 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1832 * chains - the second one will be new, but L1 already has
1833 * L2 added to its dependency list, due to the first chain.)
1834 */
Dave Jonesf82b2172008-08-11 09:30:23 +02001835 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1836 if (entry->class == hlock_class(next)) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07001837 if (distance == 1)
1838 entry->distance = 1;
1839 return 2;
1840 }
1841 }
1842
Yong Zhang4726f2a2010-05-04 14:16:48 +08001843 if (!trylock_loop && !save_trace(&trace))
1844 return 0;
1845
Peter Zijlstra8e182572007-07-19 01:48:54 -07001846 /*
1847 * Ok, all validations passed, add the new lock
1848 * to the previous lock's dependency list:
1849 */
Dave Jonesf82b2172008-08-11 09:30:23 +02001850 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1851 &hlock_class(prev)->locks_after,
Yong Zhang4726f2a2010-05-04 14:16:48 +08001852 next->acquire_ip, distance, &trace);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001853
1854 if (!ret)
1855 return 0;
1856
Dave Jonesf82b2172008-08-11 09:30:23 +02001857 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1858 &hlock_class(next)->locks_before,
Yong Zhang4726f2a2010-05-04 14:16:48 +08001859 next->acquire_ip, distance, &trace);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001860 if (!ret)
1861 return 0;
1862
1863 /*
1864 * Debugging printouts:
1865 */
Dave Jonesf82b2172008-08-11 09:30:23 +02001866 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07001867 graph_unlock();
1868 printk("\n new dependency: ");
Dave Jonesf82b2172008-08-11 09:30:23 +02001869 print_lock_name(hlock_class(prev));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001870 printk(" => ");
Dave Jonesf82b2172008-08-11 09:30:23 +02001871 print_lock_name(hlock_class(next));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001872 printk("\n");
1873 dump_stack();
1874 return graph_lock();
1875 }
1876 return 1;
1877}
1878
1879/*
1880 * Add the dependency to all directly-previous locks that are 'relevant'.
1881 * The ones that are relevant are (in increasing distance from curr):
1882 * all consecutive trylock entries and the final non-trylock entry - or
1883 * the end of this context's lock-chain - whichever comes first.
1884 */
1885static int
1886check_prevs_add(struct task_struct *curr, struct held_lock *next)
1887{
1888 int depth = curr->lockdep_depth;
Yong Zhang4726f2a2010-05-04 14:16:48 +08001889 int trylock_loop = 0;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001890 struct held_lock *hlock;
1891
1892 /*
1893 * Debugging checks.
1894 *
1895 * Depth must not be zero for a non-head lock:
1896 */
1897 if (!depth)
1898 goto out_bug;
1899 /*
1900 * At least two relevant locks must exist for this
1901 * to be a head:
1902 */
1903 if (curr->held_locks[depth].irq_context !=
1904 curr->held_locks[depth-1].irq_context)
1905 goto out_bug;
1906
1907 for (;;) {
1908 int distance = curr->lockdep_depth - depth + 1;
1909 hlock = curr->held_locks + depth-1;
1910 /*
1911 * Only non-recursive-read entries get new dependencies
1912 * added:
1913 */
1914 if (hlock->read != 2) {
Yong Zhang4726f2a2010-05-04 14:16:48 +08001915 if (!check_prev_add(curr, hlock, next,
1916 distance, trylock_loop))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001917 return 0;
1918 /*
1919 * Stop after the first non-trylock entry,
1920 * as non-trylock entries have added their
1921 * own direct dependencies already, so this
1922 * lock is connected to them indirectly:
1923 */
1924 if (!hlock->trylock)
1925 break;
1926 }
1927 depth--;
1928 /*
1929 * End of lock-stack?
1930 */
1931 if (!depth)
1932 break;
1933 /*
1934 * Stop the search if we cross into another context:
1935 */
1936 if (curr->held_locks[depth].irq_context !=
1937 curr->held_locks[depth-1].irq_context)
1938 break;
Yong Zhang4726f2a2010-05-04 14:16:48 +08001939 trylock_loop = 1;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001940 }
1941 return 1;
1942out_bug:
1943 if (!debug_locks_off_graph_unlock())
1944 return 0;
1945
1946 WARN_ON(1);
1947
1948 return 0;
1949}
1950
1951unsigned long nr_lock_chains;
Huang, Ying443cd502008-06-20 16:39:21 +08001952struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
Huang, Yingcd1a28e2008-06-23 11:20:54 +08001953int nr_chain_hlocks;
Huang, Ying443cd502008-06-20 16:39:21 +08001954static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1955
1956struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1957{
1958 return lock_classes + chain_hlocks[chain->base + i];
1959}
Peter Zijlstra8e182572007-07-19 01:48:54 -07001960
1961/*
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001962 * Look up a dependency chain. If the key is not present yet then
Jarek Poplawski9e860d02007-05-08 00:30:12 -07001963 * add it and return 1 - in this case the new dependency chain is
1964 * validated. If the key is already hashed, return 0.
1965 * (On return with 1 graph_lock is held.)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001966 */
Huang, Ying443cd502008-06-20 16:39:21 +08001967static inline int lookup_chain_cache(struct task_struct *curr,
1968 struct held_lock *hlock,
1969 u64 chain_key)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001970{
Dave Jonesf82b2172008-08-11 09:30:23 +02001971 struct lock_class *class = hlock_class(hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001972 struct list_head *hash_head = chainhashentry(chain_key);
1973 struct lock_chain *chain;
Huang, Ying443cd502008-06-20 16:39:21 +08001974 struct held_lock *hlock_curr, *hlock_next;
Huang, Yingcd1a28e2008-06-23 11:20:54 +08001975 int i, j, n, cn;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001976
Jarek Poplawski381a2292007-02-10 01:44:58 -08001977 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1978 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001979 /*
1980 * We can walk it lock-free, because entries only get added
1981 * to the hash:
1982 */
1983 list_for_each_entry(chain, hash_head, entry) {
1984 if (chain->chain_key == chain_key) {
1985cache_hit:
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001986 debug_atomic_inc(chain_lookup_hits);
Ingo Molnar81fc6852006-12-13 00:34:40 -08001987 if (very_verbose(class))
Andrew Morton755cd902006-12-29 16:49:14 -08001988 printk("\nhash chain already cached, key: "
1989 "%016Lx tail class: [%p] %s\n",
1990 (unsigned long long)chain_key,
1991 class->key, class->name);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001992 return 0;
1993 }
1994 }
Ingo Molnar81fc6852006-12-13 00:34:40 -08001995 if (very_verbose(class))
Andrew Morton755cd902006-12-29 16:49:14 -08001996 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1997 (unsigned long long)chain_key, class->key, class->name);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001998 /*
1999 * Allocate a new chain entry from the static array, and add
2000 * it to the hash:
2001 */
Ingo Molnar74c383f2006-12-13 00:34:43 -08002002 if (!graph_lock())
2003 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002004 /*
2005 * We have to walk the chain again locked - to avoid duplicates:
2006 */
2007 list_for_each_entry(chain, hash_head, entry) {
2008 if (chain->chain_key == chain_key) {
Ingo Molnar74c383f2006-12-13 00:34:43 -08002009 graph_unlock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002010 goto cache_hit;
2011 }
2012 }
2013 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
Ingo Molnar74c383f2006-12-13 00:34:43 -08002014 if (!debug_locks_off_graph_unlock())
2015 return 0;
2016
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002017 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2018 printk("turning off the locking correctness validator.\n");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +01002019 dump_stack();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002020 return 0;
2021 }
2022 chain = lock_chains + nr_lock_chains++;
2023 chain->chain_key = chain_key;
Huang, Ying443cd502008-06-20 16:39:21 +08002024 chain->irq_context = hlock->irq_context;
2025 /* Find the first held_lock of current chain */
2026 hlock_next = hlock;
2027 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2028 hlock_curr = curr->held_locks + i;
2029 if (hlock_curr->irq_context != hlock_next->irq_context)
2030 break;
2031 hlock_next = hlock;
2032 }
2033 i++;
2034 chain->depth = curr->lockdep_depth + 1 - i;
Huang, Yingcd1a28e2008-06-23 11:20:54 +08002035 cn = nr_chain_hlocks;
2036 while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
2037 n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
2038 if (n == cn)
2039 break;
2040 cn = n;
2041 }
2042 if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2043 chain->base = cn;
Huang, Ying443cd502008-06-20 16:39:21 +08002044 for (j = 0; j < chain->depth - 1; j++, i++) {
Dave Jonesf82b2172008-08-11 09:30:23 +02002045 int lock_id = curr->held_locks[i].class_idx - 1;
Huang, Ying443cd502008-06-20 16:39:21 +08002046 chain_hlocks[chain->base + j] = lock_id;
2047 }
2048 chain_hlocks[chain->base + j] = class - lock_classes;
2049 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002050 list_add_tail_rcu(&chain->entry, hash_head);
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002051 debug_atomic_inc(chain_lookup_misses);
Peter Zijlstra8e182572007-07-19 01:48:54 -07002052 inc_chains();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002053
2054 return 1;
2055}
Peter Zijlstra8e182572007-07-19 01:48:54 -07002056
2057static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
Johannes Berg4e6045f2007-10-18 23:39:55 -07002058 struct held_lock *hlock, int chain_head, u64 chain_key)
Peter Zijlstra8e182572007-07-19 01:48:54 -07002059{
2060 /*
2061 * Trylock needs to maintain the stack of held locks, but it
2062 * does not add new dependencies, because trylock can be done
2063 * in any order.
2064 *
2065 * We look up the chain_key and do the O(N^2) check and update of
2066 * the dependencies only if this is a new dependency chain.
2067 * (If lookup_chain_cache() returns with 1 it acquires
2068 * graph_lock for us)
2069 */
2070 if (!hlock->trylock && (hlock->check == 2) &&
Huang, Ying443cd502008-06-20 16:39:21 +08002071 lookup_chain_cache(curr, hlock, chain_key)) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07002072 /*
2073 * Check whether last held lock:
2074 *
2075 * - is irq-safe, if this lock is irq-unsafe
2076 * - is softirq-safe, if this lock is hardirq-unsafe
2077 *
2078 * And check whether the new lock's dependency graph
2079 * could lead back to the previous lock.
2080 *
2081 * any of these scenarios could lead to a deadlock. If
2082 * All validations
2083 */
2084 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2085
2086 if (!ret)
2087 return 0;
2088 /*
2089 * Mark recursive read, as we jump over it when
2090 * building dependencies (just like we jump over
2091 * trylock entries):
2092 */
2093 if (ret == 2)
2094 hlock->read = 2;
2095 /*
2096 * Add dependency only if this lock is not the head
2097 * of the chain, and if it's not a secondary read-lock:
2098 */
2099 if (!chain_head && ret != 2)
2100 if (!check_prevs_add(curr, hlock))
2101 return 0;
2102 graph_unlock();
2103 } else
2104 /* after lookup_chain_cache(): */
2105 if (unlikely(!debug_locks))
2106 return 0;
2107
2108 return 1;
2109}
2110#else
2111static inline int validate_chain(struct task_struct *curr,
2112 struct lockdep_map *lock, struct held_lock *hlock,
Gregory Haskins3aa416b2007-10-11 22:11:11 +02002113 int chain_head, u64 chain_key)
Peter Zijlstra8e182572007-07-19 01:48:54 -07002114{
2115 return 1;
2116}
Peter Zijlstraca58abc2007-07-19 01:48:53 -07002117#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002118
2119/*
2120 * We are building curr_chain_key incrementally, so double-check
2121 * it from scratch, to make sure that it's done correctly:
2122 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002123static void check_chain_key(struct task_struct *curr)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002124{
2125#ifdef CONFIG_DEBUG_LOCKDEP
2126 struct held_lock *hlock, *prev_hlock = NULL;
2127 unsigned int i, id;
2128 u64 chain_key = 0;
2129
2130 for (i = 0; i < curr->lockdep_depth; i++) {
2131 hlock = curr->held_locks + i;
2132 if (chain_key != hlock->prev_chain_key) {
2133 debug_locks_off();
Arjan van de Ven2df8b1d2008-07-30 12:43:11 -07002134 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002135 curr->lockdep_depth, i,
2136 (unsigned long long)chain_key,
2137 (unsigned long long)hlock->prev_chain_key);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002138 return;
2139 }
Dave Jonesf82b2172008-08-11 09:30:23 +02002140 id = hlock->class_idx - 1;
Jarek Poplawski381a2292007-02-10 01:44:58 -08002141 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2142 return;
2143
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002144 if (prev_hlock && (prev_hlock->irq_context !=
2145 hlock->irq_context))
2146 chain_key = 0;
2147 chain_key = iterate_chain_key(chain_key, id);
2148 prev_hlock = hlock;
2149 }
2150 if (chain_key != curr->curr_chain_key) {
2151 debug_locks_off();
Arjan van de Ven2df8b1d2008-07-30 12:43:11 -07002152 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002153 curr->lockdep_depth, i,
2154 (unsigned long long)chain_key,
2155 (unsigned long long)curr->curr_chain_key);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002156 }
2157#endif
2158}
2159
Peter Zijlstra8e182572007-07-19 01:48:54 -07002160static int
2161print_usage_bug(struct task_struct *curr, struct held_lock *this,
2162 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2163{
2164 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2165 return 0;
2166
2167 printk("\n=================================\n");
2168 printk( "[ INFO: inconsistent lock state ]\n");
2169 print_kernel_version();
2170 printk( "---------------------------------\n");
2171
2172 printk("inconsistent {%s} -> {%s} usage.\n",
2173 usage_str[prev_bit], usage_str[new_bit]);
2174
2175 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07002176 curr->comm, task_pid_nr(curr),
Peter Zijlstra8e182572007-07-19 01:48:54 -07002177 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2178 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2179 trace_hardirqs_enabled(curr),
2180 trace_softirqs_enabled(curr));
2181 print_lock(this);
2182
2183 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
Dave Jonesf82b2172008-08-11 09:30:23 +02002184 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07002185
2186 print_irqtrace_events(curr);
2187 printk("\nother info that might help us debug this:\n");
2188 lockdep_print_held_locks(curr);
2189
2190 printk("\nstack backtrace:\n");
2191 dump_stack();
2192
2193 return 0;
2194}
2195
2196/*
2197 * Print out an error if an invalid bit is set:
2198 */
2199static inline int
2200valid_state(struct task_struct *curr, struct held_lock *this,
2201 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2202{
Dave Jonesf82b2172008-08-11 09:30:23 +02002203 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002204 return print_usage_bug(curr, this, bad_bit, new_bit);
2205 return 1;
2206}
2207
2208static int mark_lock(struct task_struct *curr, struct held_lock *this,
2209 enum lock_usage_bit new_bit);
2210
Steven Rostedt81d68a92008-05-12 21:20:42 +02002211#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002212
2213/*
2214 * print irq inversion bug:
2215 */
2216static int
Ming Lei24208ca2009-07-16 15:44:29 +02002217print_irq_inversion_bug(struct task_struct *curr,
2218 struct lock_list *root, struct lock_list *other,
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002219 struct held_lock *this, int forwards,
2220 const char *irqclass)
2221{
Ingo Molnar74c383f2006-12-13 00:34:43 -08002222 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002223 return 0;
2224
2225 printk("\n=========================================================\n");
2226 printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
Dave Jones99de0552006-09-29 02:00:10 -07002227 print_kernel_version();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002228 printk( "---------------------------------------------------------\n");
2229 printk("%s/%d just changed the state of lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07002230 curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002231 print_lock(this);
2232 if (forwards)
Peter Zijlstra26575e22009-03-04 14:53:24 +01002233 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002234 else
Peter Zijlstra26575e22009-03-04 14:53:24 +01002235 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
Ming Lei24208ca2009-07-16 15:44:29 +02002236 print_lock_name(other->class);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002237 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2238
2239 printk("\nother info that might help us debug this:\n");
2240 lockdep_print_held_locks(curr);
2241
Ming Lei24208ca2009-07-16 15:44:29 +02002242 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2243 if (!save_trace(&root->trace))
2244 return 0;
2245 print_shortest_lock_dependencies(other, root);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002246
2247 printk("\nstack backtrace:\n");
2248 dump_stack();
2249
2250 return 0;
2251}
2252
2253/*
2254 * Prove that in the forwards-direction subgraph starting at <this>
2255 * there is no lock matching <mask>:
2256 */
2257static int
2258check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2259 enum lock_usage_bit bit, const char *irqclass)
2260{
2261 int ret;
Ming Leid7aaba12009-07-16 15:44:29 +02002262 struct lock_list root;
2263 struct lock_list *uninitialized_var(target_entry);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002264
Ming Leid7aaba12009-07-16 15:44:29 +02002265 root.parent = NULL;
2266 root.class = hlock_class(this);
2267 ret = find_usage_forwards(&root, bit, &target_entry);
Peter Zijlstraaf012962009-07-16 15:44:29 +02002268 if (ret < 0)
2269 return print_bfs_bug(ret);
2270 if (ret == 1)
2271 return ret;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002272
Ming Lei24208ca2009-07-16 15:44:29 +02002273 return print_irq_inversion_bug(curr, &root, target_entry,
Ming Leid7aaba12009-07-16 15:44:29 +02002274 this, 1, irqclass);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002275}
2276
2277/*
2278 * Prove that in the backwards-direction subgraph starting at <this>
2279 * there is no lock matching <mask>:
2280 */
2281static int
2282check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2283 enum lock_usage_bit bit, const char *irqclass)
2284{
2285 int ret;
Ming Leid7aaba12009-07-16 15:44:29 +02002286 struct lock_list root;
2287 struct lock_list *uninitialized_var(target_entry);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002288
Ming Leid7aaba12009-07-16 15:44:29 +02002289 root.parent = NULL;
2290 root.class = hlock_class(this);
2291 ret = find_usage_backwards(&root, bit, &target_entry);
Peter Zijlstraaf012962009-07-16 15:44:29 +02002292 if (ret < 0)
2293 return print_bfs_bug(ret);
2294 if (ret == 1)
2295 return ret;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002296
Ming Lei24208ca2009-07-16 15:44:29 +02002297 return print_irq_inversion_bug(curr, &root, target_entry,
Oleg Nesterov48d50672010-01-26 19:16:41 +01002298 this, 0, irqclass);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002299}
2300
Ingo Molnar3117df02006-12-13 00:34:43 -08002301void print_irqtrace_events(struct task_struct *curr)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002302{
2303 printk("irq event stamp: %u\n", curr->irq_events);
2304 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2305 print_ip_sym(curr->hardirq_enable_ip);
2306 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2307 print_ip_sym(curr->hardirq_disable_ip);
2308 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2309 print_ip_sym(curr->softirq_enable_ip);
2310 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2311 print_ip_sym(curr->softirq_disable_ip);
2312}
2313
Peter Zijlstracd953022009-01-22 16:38:21 +01002314static int HARDIRQ_verbose(struct lock_class *class)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002315{
Peter Zijlstra8e182572007-07-19 01:48:54 -07002316#if HARDIRQ_VERBOSE
2317 return class_filter(class);
2318#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002319 return 0;
2320}
2321
Peter Zijlstracd953022009-01-22 16:38:21 +01002322static int SOFTIRQ_verbose(struct lock_class *class)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002323{
Peter Zijlstra8e182572007-07-19 01:48:54 -07002324#if SOFTIRQ_VERBOSE
2325 return class_filter(class);
2326#endif
2327 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002328}
2329
Peter Zijlstracd953022009-01-22 16:38:21 +01002330static int RECLAIM_FS_verbose(struct lock_class *class)
Nick Piggincf40bd12009-01-21 08:12:39 +01002331{
2332#if RECLAIM_VERBOSE
2333 return class_filter(class);
2334#endif
2335 return 0;
2336}
2337
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002338#define STRICT_READ_CHECKS 1
2339
Peter Zijlstracd953022009-01-22 16:38:21 +01002340static int (*state_verbose_f[])(struct lock_class *class) = {
2341#define LOCKDEP_STATE(__STATE) \
2342 __STATE##_verbose,
2343#include "lockdep_states.h"
2344#undef LOCKDEP_STATE
2345};
2346
2347static inline int state_verbose(enum lock_usage_bit bit,
2348 struct lock_class *class)
2349{
2350 return state_verbose_f[bit >> 2](class);
2351}
2352
Peter Zijlstra42c50d52009-01-22 16:58:16 +01002353typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2354 enum lock_usage_bit bit, const char *name);
2355
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002356static int
Peter Zijlstra1c21f142009-03-04 13:51:13 +01002357mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2358 enum lock_usage_bit new_bit)
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002359{
Peter Zijlstraf9892092009-01-22 16:09:59 +01002360 int excl_bit = exclusive_bit(new_bit);
Peter Zijlstra9d3651a2009-01-22 17:18:32 +01002361 int read = new_bit & 1;
Peter Zijlstra42c50d52009-01-22 16:58:16 +01002362 int dir = new_bit & 2;
2363
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002364 /*
2365 * mark USED_IN has to look forwards -- to ensure no dependency
2366 * has ENABLED state, which would allow recursion deadlocks.
2367 *
2368 * mark ENABLED has to look backwards -- to ensure no dependee
2369 * has USED_IN state, which, again, would allow recursion deadlocks.
2370 */
Peter Zijlstra42c50d52009-01-22 16:58:16 +01002371 check_usage_f usage = dir ?
2372 check_usage_backwards : check_usage_forwards;
Peter Zijlstraf9892092009-01-22 16:09:59 +01002373
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002374 /*
2375 * Validate that this particular lock does not have conflicting
2376 * usage states.
2377 */
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002378 if (!valid_state(curr, this, new_bit, excl_bit))
2379 return 0;
Peter Zijlstra9d3651a2009-01-22 17:18:32 +01002380
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002381 /*
2382 * Validate that the lock dependencies don't have conflicting usage
2383 * states.
2384 */
2385 if ((!read || !dir || STRICT_READ_CHECKS) &&
Peter Zijlstra1c21f142009-03-04 13:51:13 +01002386 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002387 return 0;
Peter Zijlstra780e8202009-01-22 16:51:29 +01002388
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002389 /*
2390 * Check for read in write conflicts
2391 */
2392 if (!read) {
2393 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2394 return 0;
2395
2396 if (STRICT_READ_CHECKS &&
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01002397 !usage(curr, this, excl_bit + 1,
2398 state_name(new_bit + 1)))
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002399 return 0;
2400 }
Peter Zijlstra780e8202009-01-22 16:51:29 +01002401
Peter Zijlstracd953022009-01-22 16:38:21 +01002402 if (state_verbose(new_bit, hlock_class(this)))
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002403 return 2;
2404
2405 return 1;
2406}
2407
Nick Piggincf40bd12009-01-21 08:12:39 +01002408enum mark_type {
Peter Zijlstra36bfb9b2009-01-22 14:12:41 +01002409#define LOCKDEP_STATE(__STATE) __STATE,
2410#include "lockdep_states.h"
2411#undef LOCKDEP_STATE
Nick Piggincf40bd12009-01-21 08:12:39 +01002412};
2413
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002414/*
2415 * Mark all held locks with a usage bit:
2416 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002417static int
Nick Piggincf40bd12009-01-21 08:12:39 +01002418mark_held_locks(struct task_struct *curr, enum mark_type mark)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002419{
2420 enum lock_usage_bit usage_bit;
2421 struct held_lock *hlock;
2422 int i;
2423
2424 for (i = 0; i < curr->lockdep_depth; i++) {
2425 hlock = curr->held_locks + i;
2426
Peter Zijlstracf2ad4d2009-01-27 13:58:08 +01002427 usage_bit = 2 + (mark << 2); /* ENABLED */
2428 if (hlock->read)
2429 usage_bit += 1; /* READ */
2430
2431 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
Nick Piggincf40bd12009-01-21 08:12:39 +01002432
Jarek Poplawski4ff773bb2007-05-08 00:31:00 -07002433 if (!mark_lock(curr, hlock, usage_bit))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002434 return 0;
2435 }
2436
2437 return 1;
2438}
2439
2440/*
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002441 * Hardirqs will be enabled:
2442 */
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002443void trace_hardirqs_on_caller(unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002444{
2445 struct task_struct *curr = current;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002446
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002447 time_hardirqs_on(CALLER_ADDR0, ip);
Steven Rostedt81d68a92008-05-12 21:20:42 +02002448
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002449 if (unlikely(!debug_locks || current->lockdep_recursion))
2450 return;
2451
Tejun Heo2ce802f2011-01-20 12:06:35 +01002452 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002453 return;
2454
2455 if (unlikely(curr->hardirqs_enabled)) {
Frederic Weisbecker8795d772010-04-15 23:10:42 +02002456 /*
2457 * Neither irq nor preemption are disabled here
Lucas De Marchi25985ed2011-03-30 22:57:33 -03002458 * so this is racy by nature but losing one hit
Frederic Weisbecker8795d772010-04-15 23:10:42 +02002459 * in a stat is not a big deal.
2460 */
Frederic Weisbeckerba697f42010-05-04 04:47:25 +02002461 __debug_atomic_inc(redundant_hardirqs_on);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002462 return;
2463 }
2464 /* we'll do an OFF -> ON transition: */
2465 curr->hardirqs_enabled = 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002466
2467 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2468 return;
2469 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2470 return;
2471 /*
2472 * We are going to turn hardirqs on, so set the
2473 * usage bit for all held locks:
2474 */
Nick Piggincf40bd12009-01-21 08:12:39 +01002475 if (!mark_held_locks(curr, HARDIRQ))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002476 return;
2477 /*
2478 * If we have softirqs enabled, then set the usage
2479 * bit for all held locks. (disabled hardirqs prevented
2480 * this bit from being set before)
2481 */
2482 if (curr->softirqs_enabled)
Nick Piggincf40bd12009-01-21 08:12:39 +01002483 if (!mark_held_locks(curr, SOFTIRQ))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002484 return;
2485
2486 curr->hardirq_enable_ip = ip;
2487 curr->hardirq_enable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002488 debug_atomic_inc(hardirqs_on_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002489}
Steven Rostedt81d68a92008-05-12 21:20:42 +02002490EXPORT_SYMBOL(trace_hardirqs_on_caller);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002491
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002492void trace_hardirqs_on(void)
Steven Rostedt81d68a92008-05-12 21:20:42 +02002493{
2494 trace_hardirqs_on_caller(CALLER_ADDR0);
2495}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002496EXPORT_SYMBOL(trace_hardirqs_on);
2497
2498/*
2499 * Hardirqs were disabled:
2500 */
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002501void trace_hardirqs_off_caller(unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002502{
2503 struct task_struct *curr = current;
2504
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002505 time_hardirqs_off(CALLER_ADDR0, ip);
Steven Rostedt81d68a92008-05-12 21:20:42 +02002506
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002507 if (unlikely(!debug_locks || current->lockdep_recursion))
2508 return;
2509
2510 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2511 return;
2512
2513 if (curr->hardirqs_enabled) {
2514 /*
2515 * We have done an ON -> OFF transition:
2516 */
2517 curr->hardirqs_enabled = 0;
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002518 curr->hardirq_disable_ip = ip;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002519 curr->hardirq_disable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002520 debug_atomic_inc(hardirqs_off_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002521 } else
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002522 debug_atomic_inc(redundant_hardirqs_off);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002523}
Steven Rostedt81d68a92008-05-12 21:20:42 +02002524EXPORT_SYMBOL(trace_hardirqs_off_caller);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002525
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002526void trace_hardirqs_off(void)
Steven Rostedt81d68a92008-05-12 21:20:42 +02002527{
2528 trace_hardirqs_off_caller(CALLER_ADDR0);
2529}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002530EXPORT_SYMBOL(trace_hardirqs_off);
2531
2532/*
2533 * Softirqs will be enabled:
2534 */
2535void trace_softirqs_on(unsigned long ip)
2536{
2537 struct task_struct *curr = current;
2538
2539 if (unlikely(!debug_locks))
2540 return;
2541
2542 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2543 return;
2544
2545 if (curr->softirqs_enabled) {
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002546 debug_atomic_inc(redundant_softirqs_on);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002547 return;
2548 }
2549
2550 /*
2551 * We'll do an OFF -> ON transition:
2552 */
2553 curr->softirqs_enabled = 1;
2554 curr->softirq_enable_ip = ip;
2555 curr->softirq_enable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002556 debug_atomic_inc(softirqs_on_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002557 /*
2558 * We are going to turn softirqs on, so set the
2559 * usage bit for all held locks, if hardirqs are
2560 * enabled too:
2561 */
2562 if (curr->hardirqs_enabled)
Nick Piggincf40bd12009-01-21 08:12:39 +01002563 mark_held_locks(curr, SOFTIRQ);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002564}
2565
2566/*
2567 * Softirqs were disabled:
2568 */
2569void trace_softirqs_off(unsigned long ip)
2570{
2571 struct task_struct *curr = current;
2572
2573 if (unlikely(!debug_locks))
2574 return;
2575
2576 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2577 return;
2578
2579 if (curr->softirqs_enabled) {
2580 /*
2581 * We have done an ON -> OFF transition:
2582 */
2583 curr->softirqs_enabled = 0;
2584 curr->softirq_disable_ip = ip;
2585 curr->softirq_disable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002586 debug_atomic_inc(softirqs_off_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002587 DEBUG_LOCKS_WARN_ON(!softirq_count());
2588 } else
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002589 debug_atomic_inc(redundant_softirqs_off);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002590}
2591
Peter Zijlstra2f850182009-03-20 11:13:20 +01002592static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
Nick Piggincf40bd12009-01-21 08:12:39 +01002593{
2594 struct task_struct *curr = current;
2595
2596 if (unlikely(!debug_locks))
2597 return;
2598
2599 /* no reclaim without waiting on it */
2600 if (!(gfp_mask & __GFP_WAIT))
2601 return;
2602
2603 /* this guy won't enter reclaim */
2604 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2605 return;
2606
2607 /* We're only interested __GFP_FS allocations for now */
2608 if (!(gfp_mask & __GFP_FS))
2609 return;
2610
Peter Zijlstra2f850182009-03-20 11:13:20 +01002611 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
Nick Piggincf40bd12009-01-21 08:12:39 +01002612 return;
2613
2614 mark_held_locks(curr, RECLAIM_FS);
2615}
2616
Peter Zijlstra2f850182009-03-20 11:13:20 +01002617static void check_flags(unsigned long flags);
2618
2619void lockdep_trace_alloc(gfp_t gfp_mask)
2620{
2621 unsigned long flags;
2622
2623 if (unlikely(current->lockdep_recursion))
2624 return;
2625
2626 raw_local_irq_save(flags);
2627 check_flags(flags);
2628 current->lockdep_recursion = 1;
2629 __lockdep_trace_alloc(gfp_mask, flags);
2630 current->lockdep_recursion = 0;
2631 raw_local_irq_restore(flags);
2632}
2633
Peter Zijlstra8e182572007-07-19 01:48:54 -07002634static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2635{
2636 /*
2637 * If non-trylock use in a hardirq or softirq context, then
2638 * mark the lock as used in these contexts:
2639 */
2640 if (!hlock->trylock) {
2641 if (hlock->read) {
2642 if (curr->hardirq_context)
2643 if (!mark_lock(curr, hlock,
2644 LOCK_USED_IN_HARDIRQ_READ))
2645 return 0;
2646 if (curr->softirq_context)
2647 if (!mark_lock(curr, hlock,
2648 LOCK_USED_IN_SOFTIRQ_READ))
2649 return 0;
2650 } else {
2651 if (curr->hardirq_context)
2652 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2653 return 0;
2654 if (curr->softirq_context)
2655 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2656 return 0;
2657 }
2658 }
2659 if (!hlock->hardirqs_off) {
2660 if (hlock->read) {
2661 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002662 LOCK_ENABLED_HARDIRQ_READ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002663 return 0;
2664 if (curr->softirqs_enabled)
2665 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002666 LOCK_ENABLED_SOFTIRQ_READ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002667 return 0;
2668 } else {
2669 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002670 LOCK_ENABLED_HARDIRQ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002671 return 0;
2672 if (curr->softirqs_enabled)
2673 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002674 LOCK_ENABLED_SOFTIRQ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002675 return 0;
2676 }
2677 }
2678
Nick Piggincf40bd12009-01-21 08:12:39 +01002679 /*
2680 * We reuse the irq context infrastructure more broadly as a general
2681 * context checking code. This tests GFP_FS recursion (a lock taken
2682 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2683 * allocation).
2684 */
2685 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2686 if (hlock->read) {
2687 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2688 return 0;
2689 } else {
2690 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2691 return 0;
2692 }
2693 }
2694
Peter Zijlstra8e182572007-07-19 01:48:54 -07002695 return 1;
2696}
2697
2698static int separate_irq_context(struct task_struct *curr,
2699 struct held_lock *hlock)
2700{
2701 unsigned int depth = curr->lockdep_depth;
2702
2703 /*
2704 * Keep track of points where we cross into an interrupt context:
2705 */
2706 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2707 curr->softirq_context;
2708 if (depth) {
2709 struct held_lock *prev_hlock;
2710
2711 prev_hlock = curr->held_locks + depth-1;
2712 /*
2713 * If we cross into another context, reset the
2714 * hash key (this also prevents the checking and the
2715 * adding of the dependency to 'prev'):
2716 */
2717 if (prev_hlock->irq_context != hlock->irq_context)
2718 return 1;
2719 }
2720 return 0;
2721}
2722
2723#else
2724
2725static inline
2726int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2727 enum lock_usage_bit new_bit)
2728{
2729 WARN_ON(1);
2730 return 1;
2731}
2732
2733static inline int mark_irqflags(struct task_struct *curr,
2734 struct held_lock *hlock)
2735{
2736 return 1;
2737}
2738
2739static inline int separate_irq_context(struct task_struct *curr,
2740 struct held_lock *hlock)
2741{
2742 return 0;
2743}
2744
Peter Zijlstra868a23a2009-02-15 00:25:21 +01002745void lockdep_trace_alloc(gfp_t gfp_mask)
2746{
2747}
2748
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002749#endif
2750
2751/*
Peter Zijlstra8e182572007-07-19 01:48:54 -07002752 * Mark a lock with a usage bit, and validate the state transition:
2753 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002754static int mark_lock(struct task_struct *curr, struct held_lock *this,
Steven Rostedt0764d232008-05-12 21:20:44 +02002755 enum lock_usage_bit new_bit)
Peter Zijlstra8e182572007-07-19 01:48:54 -07002756{
2757 unsigned int new_mask = 1 << new_bit, ret = 1;
2758
2759 /*
2760 * If already set then do not dirty the cacheline,
2761 * nor do any checks:
2762 */
Dave Jonesf82b2172008-08-11 09:30:23 +02002763 if (likely(hlock_class(this)->usage_mask & new_mask))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002764 return 1;
2765
2766 if (!graph_lock())
2767 return 0;
2768 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03002769 * Make sure we didn't race:
Peter Zijlstra8e182572007-07-19 01:48:54 -07002770 */
Dave Jonesf82b2172008-08-11 09:30:23 +02002771 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07002772 graph_unlock();
2773 return 1;
2774 }
2775
Dave Jonesf82b2172008-08-11 09:30:23 +02002776 hlock_class(this)->usage_mask |= new_mask;
Peter Zijlstra8e182572007-07-19 01:48:54 -07002777
Dave Jonesf82b2172008-08-11 09:30:23 +02002778 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002779 return 0;
2780
2781 switch (new_bit) {
Peter Zijlstra53464172009-01-22 14:15:53 +01002782#define LOCKDEP_STATE(__STATE) \
2783 case LOCK_USED_IN_##__STATE: \
2784 case LOCK_USED_IN_##__STATE##_READ: \
2785 case LOCK_ENABLED_##__STATE: \
2786 case LOCK_ENABLED_##__STATE##_READ:
2787#include "lockdep_states.h"
2788#undef LOCKDEP_STATE
Peter Zijlstra8e182572007-07-19 01:48:54 -07002789 ret = mark_lock_irq(curr, this, new_bit);
2790 if (!ret)
2791 return 0;
2792 break;
2793 case LOCK_USED:
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002794 debug_atomic_dec(nr_unused_locks);
Peter Zijlstra8e182572007-07-19 01:48:54 -07002795 break;
2796 default:
2797 if (!debug_locks_off_graph_unlock())
2798 return 0;
2799 WARN_ON(1);
2800 return 0;
2801 }
2802
2803 graph_unlock();
2804
2805 /*
2806 * We must printk outside of the graph_lock:
2807 */
2808 if (ret == 2) {
2809 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2810 print_lock(this);
2811 print_irqtrace_events(curr);
2812 dump_stack();
2813 }
2814
2815 return ret;
2816}
2817
2818/*
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002819 * Initialize a lock instance's lock-class mapping info:
2820 */
2821void lockdep_init_map(struct lockdep_map *lock, const char *name,
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04002822 struct lock_class_key *key, int subclass)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002823{
Hitoshi Mitake62016252010-10-05 18:01:51 +09002824 int i;
2825
2826 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2827 lock->class_cache[i] = NULL;
2828
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002829#ifdef CONFIG_LOCK_STAT
2830 lock->cpu = raw_smp_processor_id();
2831#endif
2832
2833 if (DEBUG_LOCKS_WARN_ON(!name)) {
2834 lock->name = "NULL";
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002835 return;
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002836 }
2837
2838 lock->name = name;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002839
2840 if (DEBUG_LOCKS_WARN_ON(!key))
2841 return;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002842 /*
2843 * Sanity check, the lock-class key must be persistent:
2844 */
2845 if (!static_obj(key)) {
2846 printk("BUG: key %p not in .data!\n", key);
2847 DEBUG_LOCKS_WARN_ON(1);
2848 return;
2849 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002850 lock->key = key;
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002851
2852 if (unlikely(!debug_locks))
2853 return;
2854
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04002855 if (subclass)
2856 register_lock_class(lock, subclass, 1);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002857}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002858EXPORT_SYMBOL_GPL(lockdep_init_map);
2859
Peter Zijlstra1704f472010-03-19 01:37:42 +01002860struct lock_class_key __lockdep_no_validate__;
2861
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002862/*
2863 * This gets called for every mutex_lock*()/spin_lock*() operation.
2864 * We maintain the dependency maps and validate the locking attempt:
2865 */
2866static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2867 int trylock, int read, int check, int hardirqs_off,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02002868 struct lockdep_map *nest_lock, unsigned long ip,
2869 int references)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002870{
2871 struct task_struct *curr = current;
Ingo Molnard6d897c2006-07-10 04:44:04 -07002872 struct lock_class *class = NULL;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002873 struct held_lock *hlock;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002874 unsigned int depth, id;
2875 int chain_head = 0;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02002876 int class_idx;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002877 u64 chain_key;
2878
Peter Zijlstraf20786f2007-07-19 01:48:56 -07002879 if (!prove_locking)
2880 check = 1;
2881
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002882 if (unlikely(!debug_locks))
2883 return 0;
2884
2885 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2886 return 0;
2887
Peter Zijlstra1704f472010-03-19 01:37:42 +01002888 if (lock->key == &__lockdep_no_validate__)
2889 check = 1;
2890
Hitoshi Mitake62016252010-10-05 18:01:51 +09002891 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
2892 class = lock->class_cache[subclass];
Ingo Molnard6d897c2006-07-10 04:44:04 -07002893 /*
Hitoshi Mitake62016252010-10-05 18:01:51 +09002894 * Not cached?
Ingo Molnard6d897c2006-07-10 04:44:04 -07002895 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002896 if (unlikely(!class)) {
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04002897 class = register_lock_class(lock, subclass, 0);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002898 if (!class)
2899 return 0;
2900 }
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002901 atomic_inc((atomic_t *)&class->ops);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002902 if (very_verbose(class)) {
2903 printk("\nacquire class [%p] %s", class->key, class->name);
2904 if (class->name_version > 1)
2905 printk("#%d", class->name_version);
2906 printk("\n");
2907 dump_stack();
2908 }
2909
2910 /*
2911 * Add the lock to the list of currently held locks.
2912 * (we dont increase the depth just yet, up until the
2913 * dependency checks are done)
2914 */
2915 depth = curr->lockdep_depth;
2916 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2917 return 0;
2918
Peter Zijlstrabb97a912009-07-20 19:15:35 +02002919 class_idx = class - lock_classes + 1;
2920
2921 if (depth) {
2922 hlock = curr->held_locks + depth - 1;
2923 if (hlock->class_idx == class_idx && nest_lock) {
2924 if (hlock->references)
2925 hlock->references++;
2926 else
2927 hlock->references = 2;
2928
2929 return 1;
2930 }
2931 }
2932
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002933 hlock = curr->held_locks + depth;
Dave Jonesf82b2172008-08-11 09:30:23 +02002934 if (DEBUG_LOCKS_WARN_ON(!class))
2935 return 0;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02002936 hlock->class_idx = class_idx;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002937 hlock->acquire_ip = ip;
2938 hlock->instance = lock;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02002939 hlock->nest_lock = nest_lock;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002940 hlock->trylock = trylock;
2941 hlock->read = read;
2942 hlock->check = check;
Dmitry Baryshkov6951b122008-08-18 04:26:37 +04002943 hlock->hardirqs_off = !!hardirqs_off;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02002944 hlock->references = references;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07002945#ifdef CONFIG_LOCK_STAT
2946 hlock->waittime_stamp = 0;
Peter Zijlstra3365e7792009-10-09 10:12:41 +02002947 hlock->holdtime_stamp = lockstat_clock();
Peter Zijlstraf20786f2007-07-19 01:48:56 -07002948#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002949
Peter Zijlstra8e182572007-07-19 01:48:54 -07002950 if (check == 2 && !mark_irqflags(curr, hlock))
2951 return 0;
2952
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002953 /* mark it as used: */
Jarek Poplawski4ff773bb2007-05-08 00:31:00 -07002954 if (!mark_lock(curr, hlock, LOCK_USED))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002955 return 0;
Peter Zijlstra8e182572007-07-19 01:48:54 -07002956
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002957 /*
Gautham R Shenoy17aacfb2007-10-28 20:47:01 +01002958 * Calculate the chain hash: it's the combined hash of all the
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002959 * lock keys along the dependency chain. We save the hash value
2960 * at every step so that we can get the current hash easily
2961 * after unlock. The chain hash is then used to cache dependency
2962 * results.
2963 *
2964 * The 'key ID' is what is the most compact key value to drive
2965 * the hash, not class->key.
2966 */
2967 id = class - lock_classes;
2968 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2969 return 0;
2970
2971 chain_key = curr->curr_chain_key;
2972 if (!depth) {
2973 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2974 return 0;
2975 chain_head = 1;
2976 }
2977
2978 hlock->prev_chain_key = chain_key;
Peter Zijlstra8e182572007-07-19 01:48:54 -07002979 if (separate_irq_context(curr, hlock)) {
2980 chain_key = 0;
2981 chain_head = 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002982 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002983 chain_key = iterate_chain_key(chain_key, id);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002984
Gregory Haskins3aa416b2007-10-11 22:11:11 +02002985 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002986 return 0;
Jarek Poplawski381a2292007-02-10 01:44:58 -08002987
Gregory Haskins3aa416b2007-10-11 22:11:11 +02002988 curr->curr_chain_key = chain_key;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002989 curr->lockdep_depth++;
2990 check_chain_key(curr);
Jarek Poplawski60e114d2007-02-20 13:58:00 -08002991#ifdef CONFIG_DEBUG_LOCKDEP
2992 if (unlikely(!debug_locks))
2993 return 0;
2994#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002995 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2996 debug_locks_off();
2997 printk("BUG: MAX_LOCK_DEPTH too low!\n");
2998 printk("turning off the locking correctness validator.\n");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +01002999 dump_stack();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003000 return 0;
3001 }
Jarek Poplawski381a2292007-02-10 01:44:58 -08003002
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003003 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3004 max_lockdep_depth = curr->lockdep_depth;
3005
3006 return 1;
3007}
3008
3009static int
3010print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3011 unsigned long ip)
3012{
3013 if (!debug_locks_off())
3014 return 0;
3015 if (debug_locks_silent)
3016 return 0;
3017
3018 printk("\n=====================================\n");
3019 printk( "[ BUG: bad unlock balance detected! ]\n");
3020 printk( "-------------------------------------\n");
3021 printk("%s/%d is trying to release lock (",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003022 curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003023 print_lockdep_cache(lock);
3024 printk(") at:\n");
3025 print_ip_sym(ip);
3026 printk("but there are no more locks to release!\n");
3027 printk("\nother info that might help us debug this:\n");
3028 lockdep_print_held_locks(curr);
3029
3030 printk("\nstack backtrace:\n");
3031 dump_stack();
3032
3033 return 0;
3034}
3035
3036/*
3037 * Common debugging checks for both nested and non-nested unlock:
3038 */
3039static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3040 unsigned long ip)
3041{
3042 if (unlikely(!debug_locks))
3043 return 0;
3044 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3045 return 0;
3046
3047 if (curr->lockdep_depth <= 0)
3048 return print_unlock_inbalance_bug(curr, lock, ip);
3049
3050 return 1;
3051}
3052
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003053static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3054{
3055 if (hlock->instance == lock)
3056 return 1;
3057
3058 if (hlock->references) {
Hitoshi Mitake62016252010-10-05 18:01:51 +09003059 struct lock_class *class = lock->class_cache[0];
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003060
3061 if (!class)
3062 class = look_up_lock_class(lock, 0);
3063
3064 if (DEBUG_LOCKS_WARN_ON(!class))
3065 return 0;
3066
3067 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3068 return 0;
3069
3070 if (hlock->class_idx == class - lock_classes + 1)
3071 return 1;
3072 }
3073
3074 return 0;
3075}
3076
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003077static int
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003078__lock_set_class(struct lockdep_map *lock, const char *name,
3079 struct lock_class_key *key, unsigned int subclass,
3080 unsigned long ip)
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003081{
3082 struct task_struct *curr = current;
3083 struct held_lock *hlock, *prev_hlock;
3084 struct lock_class *class;
3085 unsigned int depth;
3086 int i;
3087
3088 depth = curr->lockdep_depth;
3089 if (DEBUG_LOCKS_WARN_ON(!depth))
3090 return 0;
3091
3092 prev_hlock = NULL;
3093 for (i = depth-1; i >= 0; i--) {
3094 hlock = curr->held_locks + i;
3095 /*
3096 * We must not cross into another context:
3097 */
3098 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3099 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003100 if (match_held_lock(hlock, lock))
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003101 goto found_it;
3102 prev_hlock = hlock;
3103 }
3104 return print_unlock_inbalance_bug(curr, lock, ip);
3105
3106found_it:
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003107 lockdep_init_map(lock, name, key, 0);
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003108 class = register_lock_class(lock, subclass, 0);
Dave Jonesf82b2172008-08-11 09:30:23 +02003109 hlock->class_idx = class - lock_classes + 1;
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003110
3111 curr->lockdep_depth = i;
3112 curr->curr_chain_key = hlock->prev_chain_key;
3113
3114 for (; i < depth; i++) {
3115 hlock = curr->held_locks + i;
3116 if (!__lock_acquire(hlock->instance,
Dave Jonesf82b2172008-08-11 09:30:23 +02003117 hlock_class(hlock)->subclass, hlock->trylock,
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003118 hlock->read, hlock->check, hlock->hardirqs_off,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003119 hlock->nest_lock, hlock->acquire_ip,
3120 hlock->references))
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003121 return 0;
3122 }
3123
3124 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3125 return 0;
3126 return 1;
3127}
3128
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003129/*
3130 * Remove the lock to the list of currently held locks in a
3131 * potentially non-nested (out of order) manner. This is a
3132 * relatively rare operation, as all the unlock APIs default
3133 * to nested mode (which uses lock_release()):
3134 */
3135static int
3136lock_release_non_nested(struct task_struct *curr,
3137 struct lockdep_map *lock, unsigned long ip)
3138{
3139 struct held_lock *hlock, *prev_hlock;
3140 unsigned int depth;
3141 int i;
3142
3143 /*
3144 * Check whether the lock exists in the current stack
3145 * of held locks:
3146 */
3147 depth = curr->lockdep_depth;
3148 if (DEBUG_LOCKS_WARN_ON(!depth))
3149 return 0;
3150
3151 prev_hlock = NULL;
3152 for (i = depth-1; i >= 0; i--) {
3153 hlock = curr->held_locks + i;
3154 /*
3155 * We must not cross into another context:
3156 */
3157 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3158 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003159 if (match_held_lock(hlock, lock))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003160 goto found_it;
3161 prev_hlock = hlock;
3162 }
3163 return print_unlock_inbalance_bug(curr, lock, ip);
3164
3165found_it:
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003166 if (hlock->instance == lock)
3167 lock_release_holdtime(hlock);
3168
3169 if (hlock->references) {
3170 hlock->references--;
3171 if (hlock->references) {
3172 /*
3173 * We had, and after removing one, still have
3174 * references, the current lock stack is still
3175 * valid. We're done!
3176 */
3177 return 1;
3178 }
3179 }
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003180
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003181 /*
3182 * We have the right lock to unlock, 'hlock' points to it.
3183 * Now we remove it from the stack, and add back the other
3184 * entries (if any), recalculating the hash along the way:
3185 */
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003186
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003187 curr->lockdep_depth = i;
3188 curr->curr_chain_key = hlock->prev_chain_key;
3189
3190 for (i++; i < depth; i++) {
3191 hlock = curr->held_locks + i;
3192 if (!__lock_acquire(hlock->instance,
Dave Jonesf82b2172008-08-11 09:30:23 +02003193 hlock_class(hlock)->subclass, hlock->trylock,
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003194 hlock->read, hlock->check, hlock->hardirqs_off,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003195 hlock->nest_lock, hlock->acquire_ip,
3196 hlock->references))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003197 return 0;
3198 }
3199
3200 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3201 return 0;
3202 return 1;
3203}
3204
3205/*
3206 * Remove the lock to the list of currently held locks - this gets
3207 * called on mutex_unlock()/spin_unlock*() (or on a failed
3208 * mutex_lock_interruptible()). This is done for unlocks that nest
3209 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3210 */
3211static int lock_release_nested(struct task_struct *curr,
3212 struct lockdep_map *lock, unsigned long ip)
3213{
3214 struct held_lock *hlock;
3215 unsigned int depth;
3216
3217 /*
3218 * Pop off the top of the lock stack:
3219 */
3220 depth = curr->lockdep_depth - 1;
3221 hlock = curr->held_locks + depth;
3222
3223 /*
3224 * Is the unlock non-nested:
3225 */
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003226 if (hlock->instance != lock || hlock->references)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003227 return lock_release_non_nested(curr, lock, ip);
3228 curr->lockdep_depth--;
3229
3230 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3231 return 0;
3232
3233 curr->curr_chain_key = hlock->prev_chain_key;
3234
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003235 lock_release_holdtime(hlock);
3236
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003237#ifdef CONFIG_DEBUG_LOCKDEP
3238 hlock->prev_chain_key = 0;
Dave Jonesf82b2172008-08-11 09:30:23 +02003239 hlock->class_idx = 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003240 hlock->acquire_ip = 0;
3241 hlock->irq_context = 0;
3242#endif
3243 return 1;
3244}
3245
3246/*
3247 * Remove the lock to the list of currently held locks - this gets
3248 * called on mutex_unlock()/spin_unlock*() (or on a failed
3249 * mutex_lock_interruptible()). This is done for unlocks that nest
3250 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3251 */
3252static void
3253__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3254{
3255 struct task_struct *curr = current;
3256
3257 if (!check_unlock(curr, lock, ip))
3258 return;
3259
3260 if (nested) {
3261 if (!lock_release_nested(curr, lock, ip))
3262 return;
3263 } else {
3264 if (!lock_release_non_nested(curr, lock, ip))
3265 return;
3266 }
3267
3268 check_chain_key(curr);
3269}
3270
Peter Zijlstraf607c662009-07-20 19:16:29 +02003271static int __lock_is_held(struct lockdep_map *lock)
3272{
3273 struct task_struct *curr = current;
3274 int i;
3275
3276 for (i = 0; i < curr->lockdep_depth; i++) {
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003277 struct held_lock *hlock = curr->held_locks + i;
3278
3279 if (match_held_lock(hlock, lock))
Peter Zijlstraf607c662009-07-20 19:16:29 +02003280 return 1;
3281 }
3282
3283 return 0;
3284}
3285
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003286/*
3287 * Check whether we follow the irq-flags state precisely:
3288 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02003289static void check_flags(unsigned long flags)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003290{
Ingo Molnar992860e2008-07-14 10:28:38 +02003291#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3292 defined(CONFIG_TRACE_IRQFLAGS)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003293 if (!debug_locks)
3294 return;
3295
Ingo Molnar5f9fa8a2007-12-07 19:02:47 +01003296 if (irqs_disabled_flags(flags)) {
3297 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3298 printk("possible reason: unannotated irqs-off.\n");
3299 }
3300 } else {
3301 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3302 printk("possible reason: unannotated irqs-on.\n");
3303 }
3304 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003305
3306 /*
3307 * We dont accurately track softirq state in e.g.
3308 * hardirq contexts (such as on 4KSTACKS), so only
3309 * check if not in hardirq contexts:
3310 */
3311 if (!hardirq_count()) {
3312 if (softirq_count())
3313 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3314 else
3315 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3316 }
3317
3318 if (!debug_locks)
3319 print_irqtrace_events(current);
3320#endif
3321}
3322
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003323void lock_set_class(struct lockdep_map *lock, const char *name,
3324 struct lock_class_key *key, unsigned int subclass,
3325 unsigned long ip)
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003326{
3327 unsigned long flags;
3328
3329 if (unlikely(current->lockdep_recursion))
3330 return;
3331
3332 raw_local_irq_save(flags);
3333 current->lockdep_recursion = 1;
3334 check_flags(flags);
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003335 if (__lock_set_class(lock, name, key, subclass, ip))
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003336 check_chain_key(current);
3337 current->lockdep_recursion = 0;
3338 raw_local_irq_restore(flags);
3339}
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003340EXPORT_SYMBOL_GPL(lock_set_class);
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003341
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003342/*
3343 * We are not always called with irqs disabled - do that here,
3344 * and also avoid lockdep recursion:
3345 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02003346void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02003347 int trylock, int read, int check,
3348 struct lockdep_map *nest_lock, unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003349{
3350 unsigned long flags;
3351
3352 if (unlikely(current->lockdep_recursion))
3353 return;
3354
3355 raw_local_irq_save(flags);
3356 check_flags(flags);
3357
3358 current->lockdep_recursion = 1;
Frederic Weisbeckerdb2c4c72010-02-02 23:34:40 +01003359 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003360 __lock_acquire(lock, subclass, trylock, read, check,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003361 irqs_disabled_flags(flags), nest_lock, ip, 0);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003362 current->lockdep_recursion = 0;
3363 raw_local_irq_restore(flags);
3364}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003365EXPORT_SYMBOL_GPL(lock_acquire);
3366
Steven Rostedt1d09daa2008-05-12 21:20:55 +02003367void lock_release(struct lockdep_map *lock, int nested,
Steven Rostedt0764d232008-05-12 21:20:44 +02003368 unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003369{
3370 unsigned long flags;
3371
3372 if (unlikely(current->lockdep_recursion))
3373 return;
3374
3375 raw_local_irq_save(flags);
3376 check_flags(flags);
3377 current->lockdep_recursion = 1;
Frederic Weisbecker93135432010-05-08 06:24:25 +02003378 trace_lock_release(lock, ip);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003379 __lock_release(lock, nested, ip);
3380 current->lockdep_recursion = 0;
3381 raw_local_irq_restore(flags);
3382}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003383EXPORT_SYMBOL_GPL(lock_release);
3384
Peter Zijlstraf607c662009-07-20 19:16:29 +02003385int lock_is_held(struct lockdep_map *lock)
3386{
3387 unsigned long flags;
3388 int ret = 0;
3389
3390 if (unlikely(current->lockdep_recursion))
3391 return ret;
3392
3393 raw_local_irq_save(flags);
3394 check_flags(flags);
3395
3396 current->lockdep_recursion = 1;
3397 ret = __lock_is_held(lock);
3398 current->lockdep_recursion = 0;
3399 raw_local_irq_restore(flags);
3400
3401 return ret;
3402}
3403EXPORT_SYMBOL_GPL(lock_is_held);
3404
Nick Piggincf40bd12009-01-21 08:12:39 +01003405void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3406{
3407 current->lockdep_reclaim_gfp = gfp_mask;
3408}
3409
3410void lockdep_clear_current_reclaim_state(void)
3411{
3412 current->lockdep_reclaim_gfp = 0;
3413}
3414
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003415#ifdef CONFIG_LOCK_STAT
3416static int
3417print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3418 unsigned long ip)
3419{
3420 if (!debug_locks_off())
3421 return 0;
3422 if (debug_locks_silent)
3423 return 0;
3424
3425 printk("\n=================================\n");
3426 printk( "[ BUG: bad contention detected! ]\n");
3427 printk( "---------------------------------\n");
3428 printk("%s/%d is trying to contend lock (",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003429 curr->comm, task_pid_nr(curr));
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003430 print_lockdep_cache(lock);
3431 printk(") at:\n");
3432 print_ip_sym(ip);
3433 printk("but there are no locks held!\n");
3434 printk("\nother info that might help us debug this:\n");
3435 lockdep_print_held_locks(curr);
3436
3437 printk("\nstack backtrace:\n");
3438 dump_stack();
3439
3440 return 0;
3441}
3442
3443static void
3444__lock_contended(struct lockdep_map *lock, unsigned long ip)
3445{
3446 struct task_struct *curr = current;
3447 struct held_lock *hlock, *prev_hlock;
3448 struct lock_class_stats *stats;
3449 unsigned int depth;
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003450 int i, contention_point, contending_point;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003451
3452 depth = curr->lockdep_depth;
3453 if (DEBUG_LOCKS_WARN_ON(!depth))
3454 return;
3455
3456 prev_hlock = NULL;
3457 for (i = depth-1; i >= 0; i--) {
3458 hlock = curr->held_locks + i;
3459 /*
3460 * We must not cross into another context:
3461 */
3462 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3463 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003464 if (match_held_lock(hlock, lock))
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003465 goto found_it;
3466 prev_hlock = hlock;
3467 }
3468 print_lock_contention_bug(curr, lock, ip);
3469 return;
3470
3471found_it:
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003472 if (hlock->instance != lock)
3473 return;
3474
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003475 hlock->waittime_stamp = lockstat_clock();
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003476
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003477 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3478 contending_point = lock_point(hlock_class(hlock)->contending_point,
3479 lock->ip);
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003480
Dave Jonesf82b2172008-08-11 09:30:23 +02003481 stats = get_lock_stats(hlock_class(hlock));
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003482 if (contention_point < LOCKSTAT_POINTS)
3483 stats->contention_point[contention_point]++;
3484 if (contending_point < LOCKSTAT_POINTS)
3485 stats->contending_point[contending_point]++;
Peter Zijlstra96645672007-07-19 01:49:00 -07003486 if (lock->cpu != smp_processor_id())
3487 stats->bounces[bounce_contended + !!hlock->read]++;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003488 put_lock_stats(stats);
3489}
3490
3491static void
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003492__lock_acquired(struct lockdep_map *lock, unsigned long ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003493{
3494 struct task_struct *curr = current;
3495 struct held_lock *hlock, *prev_hlock;
3496 struct lock_class_stats *stats;
3497 unsigned int depth;
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003498 u64 now, waittime = 0;
Peter Zijlstra96645672007-07-19 01:49:00 -07003499 int i, cpu;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003500
3501 depth = curr->lockdep_depth;
3502 if (DEBUG_LOCKS_WARN_ON(!depth))
3503 return;
3504
3505 prev_hlock = NULL;
3506 for (i = depth-1; i >= 0; i--) {
3507 hlock = curr->held_locks + i;
3508 /*
3509 * We must not cross into another context:
3510 */
3511 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3512 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003513 if (match_held_lock(hlock, lock))
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003514 goto found_it;
3515 prev_hlock = hlock;
3516 }
3517 print_lock_contention_bug(curr, lock, _RET_IP_);
3518 return;
3519
3520found_it:
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003521 if (hlock->instance != lock)
3522 return;
3523
Peter Zijlstra96645672007-07-19 01:49:00 -07003524 cpu = smp_processor_id();
3525 if (hlock->waittime_stamp) {
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003526 now = lockstat_clock();
Peter Zijlstra96645672007-07-19 01:49:00 -07003527 waittime = now - hlock->waittime_stamp;
3528 hlock->holdtime_stamp = now;
3529 }
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003530
Frederic Weisbecker883a2a32010-05-08 06:16:11 +02003531 trace_lock_acquired(lock, ip);
Frederic Weisbecker20625012009-04-06 01:49:33 +02003532
Dave Jonesf82b2172008-08-11 09:30:23 +02003533 stats = get_lock_stats(hlock_class(hlock));
Peter Zijlstra96645672007-07-19 01:49:00 -07003534 if (waittime) {
3535 if (hlock->read)
3536 lock_time_inc(&stats->read_waittime, waittime);
3537 else
3538 lock_time_inc(&stats->write_waittime, waittime);
3539 }
3540 if (lock->cpu != cpu)
3541 stats->bounces[bounce_acquired + !!hlock->read]++;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003542 put_lock_stats(stats);
Peter Zijlstra96645672007-07-19 01:49:00 -07003543
3544 lock->cpu = cpu;
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003545 lock->ip = ip;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003546}
3547
3548void lock_contended(struct lockdep_map *lock, unsigned long ip)
3549{
3550 unsigned long flags;
3551
3552 if (unlikely(!lock_stat))
3553 return;
3554
3555 if (unlikely(current->lockdep_recursion))
3556 return;
3557
3558 raw_local_irq_save(flags);
3559 check_flags(flags);
3560 current->lockdep_recursion = 1;
Frederic Weisbeckerdb2c4c72010-02-02 23:34:40 +01003561 trace_lock_contended(lock, ip);
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003562 __lock_contended(lock, ip);
3563 current->lockdep_recursion = 0;
3564 raw_local_irq_restore(flags);
3565}
3566EXPORT_SYMBOL_GPL(lock_contended);
3567
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003568void lock_acquired(struct lockdep_map *lock, unsigned long ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003569{
3570 unsigned long flags;
3571
3572 if (unlikely(!lock_stat))
3573 return;
3574
3575 if (unlikely(current->lockdep_recursion))
3576 return;
3577
3578 raw_local_irq_save(flags);
3579 check_flags(flags);
3580 current->lockdep_recursion = 1;
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003581 __lock_acquired(lock, ip);
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003582 current->lockdep_recursion = 0;
3583 raw_local_irq_restore(flags);
3584}
3585EXPORT_SYMBOL_GPL(lock_acquired);
3586#endif
3587
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003588/*
3589 * Used by the testsuite, sanitize the validator state
3590 * after a simulated failure:
3591 */
3592
3593void lockdep_reset(void)
3594{
3595 unsigned long flags;
Ingo Molnar23d95a02006-12-13 00:34:40 -08003596 int i;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003597
3598 raw_local_irq_save(flags);
3599 current->curr_chain_key = 0;
3600 current->lockdep_depth = 0;
3601 current->lockdep_recursion = 0;
3602 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3603 nr_hardirq_chains = 0;
3604 nr_softirq_chains = 0;
3605 nr_process_chains = 0;
3606 debug_locks = 1;
Ingo Molnar23d95a02006-12-13 00:34:40 -08003607 for (i = 0; i < CHAINHASH_SIZE; i++)
3608 INIT_LIST_HEAD(chainhash_table + i);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003609 raw_local_irq_restore(flags);
3610}
3611
3612static void zap_class(struct lock_class *class)
3613{
3614 int i;
3615
3616 /*
3617 * Remove all dependencies this lock is
3618 * involved in:
3619 */
3620 for (i = 0; i < nr_list_entries; i++) {
3621 if (list_entries[i].class == class)
3622 list_del_rcu(&list_entries[i].entry);
3623 }
3624 /*
3625 * Unhash the class and remove it from the all_lock_classes list:
3626 */
3627 list_del_rcu(&class->hash_entry);
3628 list_del_rcu(&class->lock_entry);
3629
Rabin Vincent8bfe0292008-08-11 09:30:26 +02003630 class->key = NULL;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003631}
3632
Arjan van de Venfabe8742008-01-24 07:00:45 +01003633static inline int within(const void *addr, void *start, unsigned long size)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003634{
3635 return addr >= start && addr < start + size;
3636}
3637
3638void lockdep_free_key_range(void *start, unsigned long size)
3639{
3640 struct lock_class *class, *next;
3641 struct list_head *head;
3642 unsigned long flags;
3643 int i;
Nick Piggin5a26db52008-01-16 09:51:58 +01003644 int locked;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003645
3646 raw_local_irq_save(flags);
Nick Piggin5a26db52008-01-16 09:51:58 +01003647 locked = graph_lock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003648
3649 /*
3650 * Unhash all classes that were created by this module:
3651 */
3652 for (i = 0; i < CLASSHASH_SIZE; i++) {
3653 head = classhash_table + i;
3654 if (list_empty(head))
3655 continue;
Arjan van de Venfabe8742008-01-24 07:00:45 +01003656 list_for_each_entry_safe(class, next, head, hash_entry) {
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003657 if (within(class->key, start, size))
3658 zap_class(class);
Arjan van de Venfabe8742008-01-24 07:00:45 +01003659 else if (within(class->name, start, size))
3660 zap_class(class);
3661 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003662 }
3663
Nick Piggin5a26db52008-01-16 09:51:58 +01003664 if (locked)
3665 graph_unlock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003666 raw_local_irq_restore(flags);
3667}
3668
3669void lockdep_reset_lock(struct lockdep_map *lock)
3670{
Ingo Molnard6d897c2006-07-10 04:44:04 -07003671 struct lock_class *class, *next;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003672 struct list_head *head;
3673 unsigned long flags;
3674 int i, j;
Nick Piggin5a26db52008-01-16 09:51:58 +01003675 int locked;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003676
3677 raw_local_irq_save(flags);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003678
3679 /*
Ingo Molnard6d897c2006-07-10 04:44:04 -07003680 * Remove all classes this lock might have:
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003681 */
Ingo Molnard6d897c2006-07-10 04:44:04 -07003682 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3683 /*
3684 * If the class exists we look it up and zap it:
3685 */
3686 class = look_up_lock_class(lock, j);
3687 if (class)
3688 zap_class(class);
3689 }
3690 /*
3691 * Debug check: in the end all mapped classes should
3692 * be gone.
3693 */
Nick Piggin5a26db52008-01-16 09:51:58 +01003694 locked = graph_lock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003695 for (i = 0; i < CLASSHASH_SIZE; i++) {
3696 head = classhash_table + i;
3697 if (list_empty(head))
3698 continue;
3699 list_for_each_entry_safe(class, next, head, hash_entry) {
Hitoshi Mitake62016252010-10-05 18:01:51 +09003700 int match = 0;
3701
3702 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3703 match |= class == lock->class_cache[j];
3704
3705 if (unlikely(match)) {
Ingo Molnar74c383f2006-12-13 00:34:43 -08003706 if (debug_locks_off_graph_unlock())
3707 WARN_ON(1);
Ingo Molnard6d897c2006-07-10 04:44:04 -07003708 goto out_restore;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003709 }
3710 }
3711 }
Nick Piggin5a26db52008-01-16 09:51:58 +01003712 if (locked)
3713 graph_unlock();
Ingo Molnard6d897c2006-07-10 04:44:04 -07003714
3715out_restore:
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003716 raw_local_irq_restore(flags);
3717}
3718
Sam Ravnborg14999932007-02-28 20:12:31 -08003719void lockdep_init(void)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003720{
3721 int i;
3722
3723 /*
3724 * Some architectures have their own start_kernel()
3725 * code which calls lockdep_init(), while we also
3726 * call lockdep_init() from the start_kernel() itself,
3727 * and we want to initialize the hashes only once:
3728 */
3729 if (lockdep_initialized)
3730 return;
3731
3732 for (i = 0; i < CLASSHASH_SIZE; i++)
3733 INIT_LIST_HEAD(classhash_table + i);
3734
3735 for (i = 0; i < CHAINHASH_SIZE; i++)
3736 INIT_LIST_HEAD(chainhash_table + i);
3737
3738 lockdep_initialized = 1;
3739}
3740
3741void __init lockdep_info(void)
3742{
3743 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3744
Li Zefanb0788ca2008-11-21 15:57:32 +08003745 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003746 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3747 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
Li Zefanb0788ca2008-11-21 15:57:32 +08003748 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003749 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3750 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3751 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3752
3753 printk(" memory used by lock dependency info: %lu kB\n",
3754 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3755 sizeof(struct list_head) * CLASSHASH_SIZE +
3756 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3757 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
Ming Lei90629202009-08-02 21:43:36 +08003758 sizeof(struct list_head) * CHAINHASH_SIZE
Ming Lei4dd861d2009-07-16 15:44:29 +02003759#ifdef CONFIG_PROVE_LOCKING
Ming Leie351b662009-07-22 22:48:09 +08003760 + sizeof(struct circular_queue)
Ming Lei4dd861d2009-07-16 15:44:29 +02003761#endif
Ming Lei90629202009-08-02 21:43:36 +08003762 ) / 1024
Ming Lei4dd861d2009-07-16 15:44:29 +02003763 );
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003764
3765 printk(" per task-struct memory footprint: %lu bytes\n",
3766 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3767
3768#ifdef CONFIG_DEBUG_LOCKDEP
Johannes Bergc71063c2007-07-19 01:49:02 -07003769 if (lockdep_init_error) {
3770 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3771 printk("Call stack leading to lockdep invocation was:\n");
3772 print_stack_trace(&lockdep_init_trace, 0);
3773 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003774#endif
3775}
3776
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003777static void
3778print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
Arjan van de Ven55794a42006-07-10 04:44:03 -07003779 const void *mem_to, struct held_lock *hlock)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003780{
3781 if (!debug_locks_off())
3782 return;
3783 if (debug_locks_silent)
3784 return;
3785
3786 printk("\n=========================\n");
3787 printk( "[ BUG: held lock freed! ]\n");
3788 printk( "-------------------------\n");
3789 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003790 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
Arjan van de Ven55794a42006-07-10 04:44:03 -07003791 print_lock(hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003792 lockdep_print_held_locks(curr);
3793
3794 printk("\nstack backtrace:\n");
3795 dump_stack();
3796}
3797
Oleg Nesterov54561782007-12-05 15:46:09 +01003798static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3799 const void* lock_from, unsigned long lock_len)
3800{
3801 return lock_from + lock_len <= mem_from ||
3802 mem_from + mem_len <= lock_from;
3803}
3804
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003805/*
3806 * Called when kernel memory is freed (or unmapped), or if a lock
3807 * is destroyed or reinitialized - this code checks whether there is
3808 * any held lock in the memory range of <from> to <to>:
3809 */
3810void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3811{
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003812 struct task_struct *curr = current;
3813 struct held_lock *hlock;
3814 unsigned long flags;
3815 int i;
3816
3817 if (unlikely(!debug_locks))
3818 return;
3819
3820 local_irq_save(flags);
3821 for (i = 0; i < curr->lockdep_depth; i++) {
3822 hlock = curr->held_locks + i;
3823
Oleg Nesterov54561782007-12-05 15:46:09 +01003824 if (not_in_range(mem_from, mem_len, hlock->instance,
3825 sizeof(*hlock->instance)))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003826 continue;
3827
Oleg Nesterov54561782007-12-05 15:46:09 +01003828 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003829 break;
3830 }
3831 local_irq_restore(flags);
3832}
Peter Zijlstraed075362006-12-06 20:35:24 -08003833EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003834
3835static void print_held_locks_bug(struct task_struct *curr)
3836{
3837 if (!debug_locks_off())
3838 return;
3839 if (debug_locks_silent)
3840 return;
3841
3842 printk("\n=====================================\n");
3843 printk( "[ BUG: lock held at task exit time! ]\n");
3844 printk( "-------------------------------------\n");
3845 printk("%s/%d is exiting with locks still held!\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003846 curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003847 lockdep_print_held_locks(curr);
3848
3849 printk("\nstack backtrace:\n");
3850 dump_stack();
3851}
3852
3853void debug_check_no_locks_held(struct task_struct *task)
3854{
3855 if (unlikely(task->lockdep_depth > 0))
3856 print_held_locks_bug(task);
3857}
3858
3859void debug_show_all_locks(void)
3860{
3861 struct task_struct *g, *p;
3862 int count = 10;
3863 int unlock = 1;
3864
Jarek Poplawski9c35dd72007-03-22 00:11:28 -08003865 if (unlikely(!debug_locks)) {
3866 printk("INFO: lockdep is turned off.\n");
3867 return;
3868 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003869 printk("\nShowing all locks held in the system:\n");
3870
3871 /*
3872 * Here we try to get the tasklist_lock as hard as possible,
3873 * if not successful after 2 seconds we ignore it (but keep
3874 * trying). This is to enable a debug printout even if a
3875 * tasklist_lock-holding task deadlocks or crashes.
3876 */
3877retry:
3878 if (!read_trylock(&tasklist_lock)) {
3879 if (count == 10)
3880 printk("hm, tasklist_lock locked, retrying... ");
3881 if (count) {
3882 count--;
3883 printk(" #%d", 10-count);
3884 mdelay(200);
3885 goto retry;
3886 }
3887 printk(" ignoring it.\n");
3888 unlock = 0;
qinghuang feng46fec7a2008-10-28 17:24:28 +08003889 } else {
3890 if (count != 10)
3891 printk(KERN_CONT " locked it.\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003892 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003893
3894 do_each_thread(g, p) {
Ingo Molnar85684872007-12-05 15:46:09 +01003895 /*
3896 * It's not reliable to print a task's held locks
3897 * if it's not sleeping (or if it's not the current
3898 * task):
3899 */
3900 if (p->state == TASK_RUNNING && p != current)
3901 continue;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003902 if (p->lockdep_depth)
3903 lockdep_print_held_locks(p);
3904 if (!unlock)
3905 if (read_trylock(&tasklist_lock))
3906 unlock = 1;
3907 } while_each_thread(g, p);
3908
3909 printk("\n");
3910 printk("=============================================\n\n");
3911
3912 if (unlock)
3913 read_unlock(&tasklist_lock);
3914}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003915EXPORT_SYMBOL_GPL(debug_show_all_locks);
3916
Ingo Molnar82a1fcb2008-01-25 21:08:02 +01003917/*
3918 * Careful: only use this function if you are sure that
3919 * the task cannot run in parallel!
3920 */
John Kacurf1b499f2010-08-05 17:10:53 +02003921void debug_show_held_locks(struct task_struct *task)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003922{
Jarek Poplawski9c35dd72007-03-22 00:11:28 -08003923 if (unlikely(!debug_locks)) {
3924 printk("INFO: lockdep is turned off.\n");
3925 return;
3926 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003927 lockdep_print_held_locks(task);
3928}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003929EXPORT_SYMBOL_GPL(debug_show_held_locks);
Peter Zijlstrab351d162007-10-11 22:11:12 +02003930
3931void lockdep_sys_exit(void)
3932{
3933 struct task_struct *curr = current;
3934
3935 if (unlikely(curr->lockdep_depth)) {
3936 if (!debug_locks_off())
3937 return;
3938 printk("\n================================================\n");
3939 printk( "[ BUG: lock held when returning to user space! ]\n");
3940 printk( "------------------------------------------------\n");
3941 printk("%s/%d is leaving the kernel with locks still held!\n",
3942 curr->comm, curr->pid);
3943 lockdep_print_held_locks(curr);
3944 }
3945}
Paul E. McKenney0632eb32010-02-22 17:04:47 -08003946
3947void lockdep_rcu_dereference(const char *file, const int line)
3948{
3949 struct task_struct *curr = current;
3950
Lai Jiangshan2b3fc352010-04-20 16:23:07 +08003951#ifndef CONFIG_PROVE_RCU_REPEATEDLY
Paul E. McKenney0632eb32010-02-22 17:04:47 -08003952 if (!debug_locks_off())
3953 return;
Lai Jiangshan2b3fc352010-04-20 16:23:07 +08003954#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
3955 /* Note: the following can be executed concurrently, so be careful. */
Paul E. McKenney056ba4a2010-02-25 14:06:46 -08003956 printk("\n===================================================\n");
3957 printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3958 printk( "---------------------------------------------------\n");
Paul E. McKenney0632eb32010-02-22 17:04:47 -08003959 printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3960 file, line);
3961 printk("\nother info that might help us debug this:\n\n");
Paul E. McKenneycc5b83a2010-03-03 07:46:59 -08003962 printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
Paul E. McKenney0632eb32010-02-22 17:04:47 -08003963 lockdep_print_held_locks(curr);
3964 printk("\nstack backtrace:\n");
3965 dump_stack();
3966}
3967EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);