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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
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001132 printk("\n");
1133 printk("======================================================\n");
1134 printk("[ INFO: possible circular locking dependency detected ]\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001135 print_kernel_version();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001136 printk("-------------------------------------------------------\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001137 printk("%s/%d is trying to acquire lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07001138 curr->comm, task_pid_nr(curr));
Ming Leidb0002a2009-07-16 15:44:29 +02001139 print_lock(check_src);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001140 printk("\nbut task is already holding lock:\n");
Ming Leidb0002a2009-07-16 15:44:29 +02001141 print_lock(check_tgt);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001142 printk("\nwhich lock already depends on the new lock.\n\n");
1143 printk("\nthe existing dependency chain (in reverse order) is:\n");
1144
1145 print_circular_bug_entry(entry, depth);
1146
1147 return 0;
1148}
1149
Ming Lei9e2d5512009-07-16 15:44:29 +02001150static inline int class_equal(struct lock_list *entry, void *data)
1151{
1152 return entry->class == data;
1153}
1154
Ming Leidb0002a2009-07-16 15:44:29 +02001155static noinline int print_circular_bug(struct lock_list *this,
1156 struct lock_list *target,
1157 struct held_lock *check_src,
1158 struct held_lock *check_tgt)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001159{
1160 struct task_struct *curr = current;
Ming Leic94aa5c2009-07-16 15:44:29 +02001161 struct lock_list *parent;
Steven Rostedtf4185812011-04-20 21:41:55 -04001162 struct lock_list *first_parent;
Ming Lei24208ca2009-07-16 15:44:29 +02001163 int depth;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001164
Ming Leic94aa5c2009-07-16 15:44:29 +02001165 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001166 return 0;
1167
Ming Leidb0002a2009-07-16 15:44:29 +02001168 if (!save_trace(&this->trace))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001169 return 0;
1170
Ming Leic94aa5c2009-07-16 15:44:29 +02001171 depth = get_lock_depth(target);
1172
Ming Leidb0002a2009-07-16 15:44:29 +02001173 print_circular_bug_header(target, depth, check_src, check_tgt);
Ming Leic94aa5c2009-07-16 15:44:29 +02001174
1175 parent = get_lock_parent(target);
Steven Rostedtf4185812011-04-20 21:41:55 -04001176 first_parent = parent;
Ming Leic94aa5c2009-07-16 15:44:29 +02001177
1178 while (parent) {
1179 print_circular_bug_entry(parent, --depth);
1180 parent = get_lock_parent(parent);
1181 }
Peter Zijlstra8e182572007-07-19 01:48:54 -07001182
1183 printk("\nother info that might help us debug this:\n\n");
Steven Rostedtf4185812011-04-20 21:41:55 -04001184 print_circular_lock_scenario(check_src, check_tgt,
1185 first_parent);
1186
Peter Zijlstra8e182572007-07-19 01:48:54 -07001187 lockdep_print_held_locks(curr);
1188
1189 printk("\nstack backtrace:\n");
1190 dump_stack();
1191
1192 return 0;
1193}
1194
Ming Leidb0002a2009-07-16 15:44:29 +02001195static noinline int print_bfs_bug(int ret)
1196{
1197 if (!debug_locks_off_graph_unlock())
1198 return 0;
1199
1200 WARN(1, "lockdep bfs error:%d\n", ret);
1201
1202 return 0;
1203}
1204
Ming Leief681022009-07-16 15:44:29 +02001205static int noop_count(struct lock_list *entry, void *data)
David Miller419ca3f2008-07-29 21:45:03 -07001206{
Ming Leief681022009-07-16 15:44:29 +02001207 (*(unsigned long *)data)++;
1208 return 0;
David Miller419ca3f2008-07-29 21:45:03 -07001209}
1210
Ming Leief681022009-07-16 15:44:29 +02001211unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1212{
1213 unsigned long count = 0;
1214 struct lock_list *uninitialized_var(target_entry);
1215
1216 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1217
1218 return count;
1219}
David Miller419ca3f2008-07-29 21:45:03 -07001220unsigned long lockdep_count_forward_deps(struct lock_class *class)
1221{
1222 unsigned long ret, flags;
Ming Leief681022009-07-16 15:44:29 +02001223 struct lock_list this;
1224
1225 this.parent = NULL;
1226 this.class = class;
David Miller419ca3f2008-07-29 21:45:03 -07001227
1228 local_irq_save(flags);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001229 arch_spin_lock(&lockdep_lock);
Ming Leief681022009-07-16 15:44:29 +02001230 ret = __lockdep_count_forward_deps(&this);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001231 arch_spin_unlock(&lockdep_lock);
David Miller419ca3f2008-07-29 21:45:03 -07001232 local_irq_restore(flags);
1233
1234 return ret;
1235}
1236
Ming Leief681022009-07-16 15:44:29 +02001237unsigned long __lockdep_count_backward_deps(struct lock_list *this)
David Miller419ca3f2008-07-29 21:45:03 -07001238{
Ming Leief681022009-07-16 15:44:29 +02001239 unsigned long count = 0;
1240 struct lock_list *uninitialized_var(target_entry);
David Miller419ca3f2008-07-29 21:45:03 -07001241
Ming Leief681022009-07-16 15:44:29 +02001242 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
David Miller419ca3f2008-07-29 21:45:03 -07001243
Ming Leief681022009-07-16 15:44:29 +02001244 return count;
David Miller419ca3f2008-07-29 21:45:03 -07001245}
1246
1247unsigned long lockdep_count_backward_deps(struct lock_class *class)
1248{
1249 unsigned long ret, flags;
Ming Leief681022009-07-16 15:44:29 +02001250 struct lock_list this;
1251
1252 this.parent = NULL;
1253 this.class = class;
David Miller419ca3f2008-07-29 21:45:03 -07001254
1255 local_irq_save(flags);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001256 arch_spin_lock(&lockdep_lock);
Ming Leief681022009-07-16 15:44:29 +02001257 ret = __lockdep_count_backward_deps(&this);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001258 arch_spin_unlock(&lockdep_lock);
David Miller419ca3f2008-07-29 21:45:03 -07001259 local_irq_restore(flags);
1260
1261 return ret;
1262}
1263
Peter Zijlstra8e182572007-07-19 01:48:54 -07001264/*
1265 * Prove that the dependency graph starting at <entry> can not
1266 * lead to <target>. Print an error and return 0 if it does.
1267 */
1268static noinline int
Ming Leidb0002a2009-07-16 15:44:29 +02001269check_noncircular(struct lock_list *root, struct lock_class *target,
1270 struct lock_list **target_entry)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001271{
Ming Leidb0002a2009-07-16 15:44:29 +02001272 int result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001273
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001274 debug_atomic_inc(nr_cyclic_checks);
David Miller419ca3f2008-07-29 21:45:03 -07001275
Ming Leid7aaba12009-07-16 15:44:29 +02001276 result = __bfs_forwards(root, target, class_equal, target_entry);
Ming Leidb0002a2009-07-16 15:44:29 +02001277
1278 return result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001279}
1280
Steven Rostedt81d68a92008-05-12 21:20:42 +02001281#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001282/*
1283 * Forwards and backwards subgraph searching, for the purposes of
1284 * proving that two subgraphs can be connected by a new dependency
1285 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1286 */
Peter Zijlstra8e182572007-07-19 01:48:54 -07001287
Ming Leid7aaba12009-07-16 15:44:29 +02001288static inline int usage_match(struct lock_list *entry, void *bit)
1289{
1290 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1291}
1292
1293
1294
Peter Zijlstra8e182572007-07-19 01:48:54 -07001295/*
1296 * Find a node in the forwards-direction dependency sub-graph starting
Ming Leid7aaba12009-07-16 15:44:29 +02001297 * at @root->class that matches @bit.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001298 *
Ming Leid7aaba12009-07-16 15:44:29 +02001299 * Return 0 if such a node exists in the subgraph, and put that node
1300 * into *@target_entry.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001301 *
Ming Leid7aaba12009-07-16 15:44:29 +02001302 * Return 1 otherwise and keep *@target_entry unchanged.
1303 * Return <0 on error.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001304 */
Ming Leid7aaba12009-07-16 15:44:29 +02001305static int
1306find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1307 struct lock_list **target_entry)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001308{
Ming Leid7aaba12009-07-16 15:44:29 +02001309 int result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001310
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001311 debug_atomic_inc(nr_find_usage_forwards_checks);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001312
Ming Leid7aaba12009-07-16 15:44:29 +02001313 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1314
1315 return result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001316}
1317
1318/*
1319 * Find a node in the backwards-direction dependency sub-graph starting
Ming Leid7aaba12009-07-16 15:44:29 +02001320 * at @root->class that matches @bit.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001321 *
Ming Leid7aaba12009-07-16 15:44:29 +02001322 * Return 0 if such a node exists in the subgraph, and put that node
1323 * into *@target_entry.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001324 *
Ming Leid7aaba12009-07-16 15:44:29 +02001325 * Return 1 otherwise and keep *@target_entry unchanged.
1326 * Return <0 on error.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001327 */
Ming Leid7aaba12009-07-16 15:44:29 +02001328static int
1329find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1330 struct lock_list **target_entry)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001331{
Ming Leid7aaba12009-07-16 15:44:29 +02001332 int result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001333
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001334 debug_atomic_inc(nr_find_usage_backwards_checks);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001335
Ming Leid7aaba12009-07-16 15:44:29 +02001336 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
Dave Jonesf82b2172008-08-11 09:30:23 +02001337
Ming Leid7aaba12009-07-16 15:44:29 +02001338 return result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001339}
1340
Peter Zijlstraaf012962009-07-16 15:44:29 +02001341static void print_lock_class_header(struct lock_class *class, int depth)
1342{
1343 int bit;
1344
1345 printk("%*s->", depth, "");
1346 print_lock_name(class);
1347 printk(" ops: %lu", class->ops);
1348 printk(" {\n");
1349
1350 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1351 if (class->usage_mask & (1 << bit)) {
1352 int len = depth;
1353
1354 len += printk("%*s %s", depth, "", usage_str[bit]);
1355 len += printk(" at:\n");
1356 print_stack_trace(class->usage_traces + bit, len);
1357 }
1358 }
1359 printk("%*s }\n", depth, "");
1360
1361 printk("%*s ... key at: ",depth,"");
1362 print_ip_sym((unsigned long)class->key);
1363}
1364
1365/*
1366 * printk the shortest lock dependencies from @start to @end in reverse order:
1367 */
1368static void __used
1369print_shortest_lock_dependencies(struct lock_list *leaf,
1370 struct lock_list *root)
1371{
1372 struct lock_list *entry = leaf;
1373 int depth;
1374
1375 /*compute depth from generated tree by BFS*/
1376 depth = get_lock_depth(leaf);
1377
1378 do {
1379 print_lock_class_header(entry->class, depth);
1380 printk("%*s ... acquired at:\n", depth, "");
1381 print_stack_trace(&entry->trace, 2);
1382 printk("\n");
1383
1384 if (depth == 0 && (entry != root)) {
Steven Rostedt6be8c392011-04-20 21:41:58 -04001385 printk("lockdep:%s bad path found in chain graph\n", __func__);
Peter Zijlstraaf012962009-07-16 15:44:29 +02001386 break;
1387 }
1388
1389 entry = get_lock_parent(entry);
1390 depth--;
1391 } while (entry && (depth >= 0));
1392
1393 return;
1394}
Ming Leid7aaba12009-07-16 15:44:29 +02001395
Steven Rostedt3003eba2011-04-20 21:41:54 -04001396static void
1397print_irq_lock_scenario(struct lock_list *safe_entry,
1398 struct lock_list *unsafe_entry,
Steven Rostedtdad3d742011-04-20 21:41:57 -04001399 struct lock_class *prev_class,
1400 struct lock_class *next_class)
Steven Rostedt3003eba2011-04-20 21:41:54 -04001401{
1402 struct lock_class *safe_class = safe_entry->class;
1403 struct lock_class *unsafe_class = unsafe_entry->class;
Steven Rostedtdad3d742011-04-20 21:41:57 -04001404 struct lock_class *middle_class = prev_class;
Steven Rostedt3003eba2011-04-20 21:41:54 -04001405
1406 if (middle_class == safe_class)
Steven Rostedtdad3d742011-04-20 21:41:57 -04001407 middle_class = next_class;
Steven Rostedt3003eba2011-04-20 21:41:54 -04001408
1409 /*
1410 * A direct locking problem where unsafe_class lock is taken
1411 * directly by safe_class lock, then all we need to show
1412 * is the deadlock scenario, as it is obvious that the
1413 * unsafe lock is taken under the safe lock.
1414 *
1415 * But if there is a chain instead, where the safe lock takes
1416 * an intermediate lock (middle_class) where this lock is
1417 * not the same as the safe lock, then the lock chain is
1418 * used to describe the problem. Otherwise we would need
1419 * to show a different CPU case for each link in the chain
1420 * from the safe_class lock to the unsafe_class lock.
1421 */
1422 if (middle_class != unsafe_class) {
1423 printk("Chain exists of:\n ");
1424 __print_lock_name(safe_class);
1425 printk(" --> ");
1426 __print_lock_name(middle_class);
1427 printk(" --> ");
1428 __print_lock_name(unsafe_class);
1429 printk("\n\n");
1430 }
1431
1432 printk(" Possible interrupt unsafe locking scenario:\n\n");
1433 printk(" CPU0 CPU1\n");
1434 printk(" ---- ----\n");
1435 printk(" lock(");
1436 __print_lock_name(unsafe_class);
1437 printk(");\n");
1438 printk(" local_irq_disable();\n");
1439 printk(" lock(");
1440 __print_lock_name(safe_class);
1441 printk(");\n");
1442 printk(" lock(");
1443 __print_lock_name(middle_class);
1444 printk(");\n");
1445 printk(" <Interrupt>\n");
1446 printk(" lock(");
1447 __print_lock_name(safe_class);
1448 printk(");\n");
1449 printk("\n *** DEADLOCK ***\n\n");
1450}
1451
Peter Zijlstra8e182572007-07-19 01:48:54 -07001452static int
1453print_bad_irq_dependency(struct task_struct *curr,
Ming Lei24208ca2009-07-16 15:44:29 +02001454 struct lock_list *prev_root,
1455 struct lock_list *next_root,
1456 struct lock_list *backwards_entry,
1457 struct lock_list *forwards_entry,
Peter Zijlstra8e182572007-07-19 01:48:54 -07001458 struct held_lock *prev,
1459 struct held_lock *next,
1460 enum lock_usage_bit bit1,
1461 enum lock_usage_bit bit2,
1462 const char *irqclass)
1463{
1464 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1465 return 0;
1466
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001467 printk("\n");
1468 printk("======================================================\n");
1469 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
Peter Zijlstra8e182572007-07-19 01:48:54 -07001470 irqclass, irqclass);
1471 print_kernel_version();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001472 printk("------------------------------------------------------\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001473 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 -07001474 curr->comm, task_pid_nr(curr),
Peter Zijlstra8e182572007-07-19 01:48:54 -07001475 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1476 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1477 curr->hardirqs_enabled,
1478 curr->softirqs_enabled);
1479 print_lock(next);
1480
1481 printk("\nand this task is already holding:\n");
1482 print_lock(prev);
1483 printk("which would create a new lock dependency:\n");
Dave Jonesf82b2172008-08-11 09:30:23 +02001484 print_lock_name(hlock_class(prev));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001485 printk(" ->");
Dave Jonesf82b2172008-08-11 09:30:23 +02001486 print_lock_name(hlock_class(next));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001487 printk("\n");
1488
1489 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1490 irqclass);
Ming Lei24208ca2009-07-16 15:44:29 +02001491 print_lock_name(backwards_entry->class);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001492 printk("\n... which became %s-irq-safe at:\n", irqclass);
1493
Ming Lei24208ca2009-07-16 15:44:29 +02001494 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001495
1496 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
Ming Lei24208ca2009-07-16 15:44:29 +02001497 print_lock_name(forwards_entry->class);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001498 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1499 printk("...");
1500
Ming Lei24208ca2009-07-16 15:44:29 +02001501 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001502
1503 printk("\nother info that might help us debug this:\n\n");
Steven Rostedtdad3d742011-04-20 21:41:57 -04001504 print_irq_lock_scenario(backwards_entry, forwards_entry,
1505 hlock_class(prev), hlock_class(next));
Steven Rostedt3003eba2011-04-20 21:41:54 -04001506
Peter Zijlstra8e182572007-07-19 01:48:54 -07001507 lockdep_print_held_locks(curr);
1508
Ming Lei24208ca2009-07-16 15:44:29 +02001509 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1510 printk(" and the holding lock:\n");
1511 if (!save_trace(&prev_root->trace))
1512 return 0;
1513 print_shortest_lock_dependencies(backwards_entry, prev_root);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001514
Ming Lei24208ca2009-07-16 15:44:29 +02001515 printk("\nthe dependencies between the lock to be acquired");
1516 printk(" and %s-irq-unsafe lock:\n", irqclass);
1517 if (!save_trace(&next_root->trace))
1518 return 0;
1519 print_shortest_lock_dependencies(forwards_entry, next_root);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001520
1521 printk("\nstack backtrace:\n");
1522 dump_stack();
1523
1524 return 0;
1525}
1526
1527static int
1528check_usage(struct task_struct *curr, struct held_lock *prev,
1529 struct held_lock *next, enum lock_usage_bit bit_backwards,
1530 enum lock_usage_bit bit_forwards, const char *irqclass)
1531{
1532 int ret;
Ming Lei24208ca2009-07-16 15:44:29 +02001533 struct lock_list this, that;
Ming Leid7aaba12009-07-16 15:44:29 +02001534 struct lock_list *uninitialized_var(target_entry);
Ming Lei24208ca2009-07-16 15:44:29 +02001535 struct lock_list *uninitialized_var(target_entry1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001536
Ming Leid7aaba12009-07-16 15:44:29 +02001537 this.parent = NULL;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001538
Ming Leid7aaba12009-07-16 15:44:29 +02001539 this.class = hlock_class(prev);
1540 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
Peter Zijlstraaf012962009-07-16 15:44:29 +02001541 if (ret < 0)
1542 return print_bfs_bug(ret);
1543 if (ret == 1)
1544 return ret;
Ming Leid7aaba12009-07-16 15:44:29 +02001545
Ming Lei24208ca2009-07-16 15:44:29 +02001546 that.parent = NULL;
1547 that.class = hlock_class(next);
1548 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
Peter Zijlstraaf012962009-07-16 15:44:29 +02001549 if (ret < 0)
1550 return print_bfs_bug(ret);
1551 if (ret == 1)
1552 return ret;
Ming Leid7aaba12009-07-16 15:44:29 +02001553
Ming Lei24208ca2009-07-16 15:44:29 +02001554 return print_bad_irq_dependency(curr, &this, &that,
1555 target_entry, target_entry1,
1556 prev, next,
Peter Zijlstra8e182572007-07-19 01:48:54 -07001557 bit_backwards, bit_forwards, irqclass);
1558}
1559
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001560static const char *state_names[] = {
1561#define LOCKDEP_STATE(__STATE) \
Peter Zijlstrab4b136f2009-01-29 14:50:36 +01001562 __stringify(__STATE),
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001563#include "lockdep_states.h"
1564#undef LOCKDEP_STATE
1565};
1566
1567static const char *state_rnames[] = {
1568#define LOCKDEP_STATE(__STATE) \
Peter Zijlstrab4b136f2009-01-29 14:50:36 +01001569 __stringify(__STATE)"-READ",
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001570#include "lockdep_states.h"
1571#undef LOCKDEP_STATE
1572};
1573
1574static inline const char *state_name(enum lock_usage_bit bit)
1575{
1576 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1577}
1578
1579static int exclusive_bit(int new_bit)
1580{
1581 /*
1582 * USED_IN
1583 * USED_IN_READ
1584 * ENABLED
1585 * ENABLED_READ
1586 *
1587 * bit 0 - write/read
1588 * bit 1 - used_in/enabled
1589 * bit 2+ state
1590 */
1591
1592 int state = new_bit & ~3;
1593 int dir = new_bit & 2;
1594
1595 /*
1596 * keep state, bit flip the direction and strip read.
1597 */
1598 return state | (dir ^ 2);
1599}
1600
1601static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1602 struct held_lock *next, enum lock_usage_bit bit)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001603{
1604 /*
1605 * Prove that the new dependency does not connect a hardirq-safe
1606 * lock with a hardirq-unsafe lock - to achieve this we search
1607 * the backwards-subgraph starting at <prev>, and the
1608 * forwards-subgraph starting at <next>:
1609 */
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001610 if (!check_usage(curr, prev, next, bit,
1611 exclusive_bit(bit), state_name(bit)))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001612 return 0;
1613
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001614 bit++; /* _READ */
1615
Peter Zijlstra8e182572007-07-19 01:48:54 -07001616 /*
1617 * Prove that the new dependency does not connect a hardirq-safe-read
1618 * lock with a hardirq-unsafe lock - to achieve this we search
1619 * the backwards-subgraph starting at <prev>, and the
1620 * forwards-subgraph starting at <next>:
1621 */
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001622 if (!check_usage(curr, prev, next, bit,
1623 exclusive_bit(bit), state_name(bit)))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001624 return 0;
1625
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001626 return 1;
1627}
Peter Zijlstra8e182572007-07-19 01:48:54 -07001628
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001629static int
1630check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1631 struct held_lock *next)
1632{
1633#define LOCKDEP_STATE(__STATE) \
1634 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
Nick Piggincf40bd12009-01-21 08:12:39 +01001635 return 0;
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001636#include "lockdep_states.h"
1637#undef LOCKDEP_STATE
Nick Piggincf40bd12009-01-21 08:12:39 +01001638
Peter Zijlstra8e182572007-07-19 01:48:54 -07001639 return 1;
1640}
1641
1642static void inc_chains(void)
1643{
1644 if (current->hardirq_context)
1645 nr_hardirq_chains++;
1646 else {
1647 if (current->softirq_context)
1648 nr_softirq_chains++;
1649 else
1650 nr_process_chains++;
1651 }
1652}
1653
1654#else
1655
1656static inline int
1657check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1658 struct held_lock *next)
1659{
1660 return 1;
1661}
1662
1663static inline void inc_chains(void)
1664{
1665 nr_process_chains++;
1666}
1667
1668#endif
1669
Steven Rostedt48702ec2011-04-20 21:41:56 -04001670static void
1671print_deadlock_scenario(struct held_lock *nxt,
1672 struct held_lock *prv)
1673{
1674 struct lock_class *next = hlock_class(nxt);
1675 struct lock_class *prev = hlock_class(prv);
1676
1677 printk(" Possible unsafe locking scenario:\n\n");
1678 printk(" CPU0\n");
1679 printk(" ----\n");
1680 printk(" lock(");
1681 __print_lock_name(prev);
1682 printk(");\n");
1683 printk(" lock(");
1684 __print_lock_name(next);
1685 printk(");\n");
1686 printk("\n *** DEADLOCK ***\n\n");
1687 printk(" May be due to missing lock nesting notation\n\n");
1688}
1689
Peter Zijlstra8e182572007-07-19 01:48:54 -07001690static int
1691print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1692 struct held_lock *next)
1693{
1694 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1695 return 0;
1696
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001697 printk("\n");
1698 printk("=============================================\n");
1699 printk("[ INFO: possible recursive locking detected ]\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001700 print_kernel_version();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001701 printk("---------------------------------------------\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001702 printk("%s/%d is trying to acquire lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07001703 curr->comm, task_pid_nr(curr));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001704 print_lock(next);
1705 printk("\nbut task is already holding lock:\n");
1706 print_lock(prev);
1707
1708 printk("\nother info that might help us debug this:\n");
Steven Rostedt48702ec2011-04-20 21:41:56 -04001709 print_deadlock_scenario(next, prev);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001710 lockdep_print_held_locks(curr);
1711
1712 printk("\nstack backtrace:\n");
1713 dump_stack();
1714
1715 return 0;
1716}
1717
1718/*
1719 * Check whether we are holding such a class already.
1720 *
1721 * (Note that this has to be done separately, because the graph cannot
1722 * detect such classes of deadlocks.)
1723 *
1724 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1725 */
1726static int
1727check_deadlock(struct task_struct *curr, struct held_lock *next,
1728 struct lockdep_map *next_instance, int read)
1729{
1730 struct held_lock *prev;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001731 struct held_lock *nest = NULL;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001732 int i;
1733
1734 for (i = 0; i < curr->lockdep_depth; i++) {
1735 prev = curr->held_locks + i;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001736
1737 if (prev->instance == next->nest_lock)
1738 nest = prev;
1739
Dave Jonesf82b2172008-08-11 09:30:23 +02001740 if (hlock_class(prev) != hlock_class(next))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001741 continue;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001742
Peter Zijlstra8e182572007-07-19 01:48:54 -07001743 /*
1744 * Allow read-after-read recursion of the same
1745 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1746 */
1747 if ((read == 2) && prev->read)
1748 return 2;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001749
1750 /*
1751 * We're holding the nest_lock, which serializes this lock's
1752 * nesting behaviour.
1753 */
1754 if (nest)
1755 return 2;
1756
Peter Zijlstra8e182572007-07-19 01:48:54 -07001757 return print_deadlock_bug(curr, prev, next);
1758 }
1759 return 1;
1760}
1761
1762/*
1763 * There was a chain-cache miss, and we are about to add a new dependency
1764 * to a previous lock. We recursively validate the following rules:
1765 *
1766 * - would the adding of the <prev> -> <next> dependency create a
1767 * circular dependency in the graph? [== circular deadlock]
1768 *
1769 * - does the new prev->next dependency connect any hardirq-safe lock
1770 * (in the full backwards-subgraph starting at <prev>) with any
1771 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1772 * <next>)? [== illegal lock inversion with hardirq contexts]
1773 *
1774 * - does the new prev->next dependency connect any softirq-safe lock
1775 * (in the full backwards-subgraph starting at <prev>) with any
1776 * softirq-unsafe lock (in the full forwards-subgraph starting at
1777 * <next>)? [== illegal lock inversion with softirq contexts]
1778 *
1779 * any of these scenarios could lead to a deadlock.
1780 *
1781 * Then if all the validations pass, we add the forwards and backwards
1782 * dependency.
1783 */
1784static int
1785check_prev_add(struct task_struct *curr, struct held_lock *prev,
Yong Zhang4726f2a2010-05-04 14:16:48 +08001786 struct held_lock *next, int distance, int trylock_loop)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001787{
1788 struct lock_list *entry;
1789 int ret;
Ming Leidb0002a2009-07-16 15:44:29 +02001790 struct lock_list this;
1791 struct lock_list *uninitialized_var(target_entry);
Yong Zhang4726f2a2010-05-04 14:16:48 +08001792 /*
1793 * Static variable, serialized by the graph_lock().
1794 *
1795 * We use this static variable to save the stack trace in case
1796 * we call into this function multiple times due to encountering
1797 * trylocks in the held lock stack.
1798 */
1799 static struct stack_trace trace;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001800
1801 /*
1802 * Prove that the new <prev> -> <next> dependency would not
1803 * create a circular dependency in the graph. (We do this by
1804 * forward-recursing into the graph starting at <next>, and
1805 * checking whether we can reach <prev>.)
1806 *
1807 * We are using global variables to control the recursion, to
1808 * keep the stackframe size of the recursive functions low:
1809 */
Ming Leidb0002a2009-07-16 15:44:29 +02001810 this.class = hlock_class(next);
1811 this.parent = NULL;
1812 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1813 if (unlikely(!ret))
1814 return print_circular_bug(&this, target_entry, next, prev);
1815 else if (unlikely(ret < 0))
1816 return print_bfs_bug(ret);
Ming Leic94aa5c2009-07-16 15:44:29 +02001817
Peter Zijlstra8e182572007-07-19 01:48:54 -07001818 if (!check_prev_add_irq(curr, prev, next))
1819 return 0;
1820
1821 /*
1822 * For recursive read-locks we do all the dependency checks,
1823 * but we dont store read-triggered dependencies (only
1824 * write-triggered dependencies). This ensures that only the
1825 * write-side dependencies matter, and that if for example a
1826 * write-lock never takes any other locks, then the reads are
1827 * equivalent to a NOP.
1828 */
1829 if (next->read == 2 || prev->read == 2)
1830 return 1;
1831 /*
1832 * Is the <prev> -> <next> dependency already present?
1833 *
1834 * (this may occur even though this is a new chain: consider
1835 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1836 * chains - the second one will be new, but L1 already has
1837 * L2 added to its dependency list, due to the first chain.)
1838 */
Dave Jonesf82b2172008-08-11 09:30:23 +02001839 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1840 if (entry->class == hlock_class(next)) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07001841 if (distance == 1)
1842 entry->distance = 1;
1843 return 2;
1844 }
1845 }
1846
Yong Zhang4726f2a2010-05-04 14:16:48 +08001847 if (!trylock_loop && !save_trace(&trace))
1848 return 0;
1849
Peter Zijlstra8e182572007-07-19 01:48:54 -07001850 /*
1851 * Ok, all validations passed, add the new lock
1852 * to the previous lock's dependency list:
1853 */
Dave Jonesf82b2172008-08-11 09:30:23 +02001854 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1855 &hlock_class(prev)->locks_after,
Yong Zhang4726f2a2010-05-04 14:16:48 +08001856 next->acquire_ip, distance, &trace);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001857
1858 if (!ret)
1859 return 0;
1860
Dave Jonesf82b2172008-08-11 09:30:23 +02001861 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1862 &hlock_class(next)->locks_before,
Yong Zhang4726f2a2010-05-04 14:16:48 +08001863 next->acquire_ip, distance, &trace);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001864 if (!ret)
1865 return 0;
1866
1867 /*
1868 * Debugging printouts:
1869 */
Dave Jonesf82b2172008-08-11 09:30:23 +02001870 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07001871 graph_unlock();
1872 printk("\n new dependency: ");
Dave Jonesf82b2172008-08-11 09:30:23 +02001873 print_lock_name(hlock_class(prev));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001874 printk(" => ");
Dave Jonesf82b2172008-08-11 09:30:23 +02001875 print_lock_name(hlock_class(next));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001876 printk("\n");
1877 dump_stack();
1878 return graph_lock();
1879 }
1880 return 1;
1881}
1882
1883/*
1884 * Add the dependency to all directly-previous locks that are 'relevant'.
1885 * The ones that are relevant are (in increasing distance from curr):
1886 * all consecutive trylock entries and the final non-trylock entry - or
1887 * the end of this context's lock-chain - whichever comes first.
1888 */
1889static int
1890check_prevs_add(struct task_struct *curr, struct held_lock *next)
1891{
1892 int depth = curr->lockdep_depth;
Yong Zhang4726f2a2010-05-04 14:16:48 +08001893 int trylock_loop = 0;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001894 struct held_lock *hlock;
1895
1896 /*
1897 * Debugging checks.
1898 *
1899 * Depth must not be zero for a non-head lock:
1900 */
1901 if (!depth)
1902 goto out_bug;
1903 /*
1904 * At least two relevant locks must exist for this
1905 * to be a head:
1906 */
1907 if (curr->held_locks[depth].irq_context !=
1908 curr->held_locks[depth-1].irq_context)
1909 goto out_bug;
1910
1911 for (;;) {
1912 int distance = curr->lockdep_depth - depth + 1;
1913 hlock = curr->held_locks + depth-1;
1914 /*
1915 * Only non-recursive-read entries get new dependencies
1916 * added:
1917 */
1918 if (hlock->read != 2) {
Yong Zhang4726f2a2010-05-04 14:16:48 +08001919 if (!check_prev_add(curr, hlock, next,
1920 distance, trylock_loop))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001921 return 0;
1922 /*
1923 * Stop after the first non-trylock entry,
1924 * as non-trylock entries have added their
1925 * own direct dependencies already, so this
1926 * lock is connected to them indirectly:
1927 */
1928 if (!hlock->trylock)
1929 break;
1930 }
1931 depth--;
1932 /*
1933 * End of lock-stack?
1934 */
1935 if (!depth)
1936 break;
1937 /*
1938 * Stop the search if we cross into another context:
1939 */
1940 if (curr->held_locks[depth].irq_context !=
1941 curr->held_locks[depth-1].irq_context)
1942 break;
Yong Zhang4726f2a2010-05-04 14:16:48 +08001943 trylock_loop = 1;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001944 }
1945 return 1;
1946out_bug:
1947 if (!debug_locks_off_graph_unlock())
1948 return 0;
1949
1950 WARN_ON(1);
1951
1952 return 0;
1953}
1954
1955unsigned long nr_lock_chains;
Huang, Ying443cd502008-06-20 16:39:21 +08001956struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
Huang, Yingcd1a28e2008-06-23 11:20:54 +08001957int nr_chain_hlocks;
Huang, Ying443cd502008-06-20 16:39:21 +08001958static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1959
1960struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1961{
1962 return lock_classes + chain_hlocks[chain->base + i];
1963}
Peter Zijlstra8e182572007-07-19 01:48:54 -07001964
1965/*
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001966 * Look up a dependency chain. If the key is not present yet then
Jarek Poplawski9e860d02007-05-08 00:30:12 -07001967 * add it and return 1 - in this case the new dependency chain is
1968 * validated. If the key is already hashed, return 0.
1969 * (On return with 1 graph_lock is held.)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001970 */
Huang, Ying443cd502008-06-20 16:39:21 +08001971static inline int lookup_chain_cache(struct task_struct *curr,
1972 struct held_lock *hlock,
1973 u64 chain_key)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001974{
Dave Jonesf82b2172008-08-11 09:30:23 +02001975 struct lock_class *class = hlock_class(hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001976 struct list_head *hash_head = chainhashentry(chain_key);
1977 struct lock_chain *chain;
Huang, Ying443cd502008-06-20 16:39:21 +08001978 struct held_lock *hlock_curr, *hlock_next;
Steven Rostedte0944ee2011-04-20 21:42:00 -04001979 int i, j;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001980
Jarek Poplawski381a2292007-02-10 01:44:58 -08001981 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1982 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001983 /*
1984 * We can walk it lock-free, because entries only get added
1985 * to the hash:
1986 */
1987 list_for_each_entry(chain, hash_head, entry) {
1988 if (chain->chain_key == chain_key) {
1989cache_hit:
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001990 debug_atomic_inc(chain_lookup_hits);
Ingo Molnar81fc6852006-12-13 00:34:40 -08001991 if (very_verbose(class))
Andrew Morton755cd902006-12-29 16:49:14 -08001992 printk("\nhash chain already cached, key: "
1993 "%016Lx tail class: [%p] %s\n",
1994 (unsigned long long)chain_key,
1995 class->key, class->name);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001996 return 0;
1997 }
1998 }
Ingo Molnar81fc6852006-12-13 00:34:40 -08001999 if (very_verbose(class))
Andrew Morton755cd902006-12-29 16:49:14 -08002000 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2001 (unsigned long long)chain_key, class->key, class->name);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002002 /*
2003 * Allocate a new chain entry from the static array, and add
2004 * it to the hash:
2005 */
Ingo Molnar74c383f2006-12-13 00:34:43 -08002006 if (!graph_lock())
2007 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002008 /*
2009 * We have to walk the chain again locked - to avoid duplicates:
2010 */
2011 list_for_each_entry(chain, hash_head, entry) {
2012 if (chain->chain_key == chain_key) {
Ingo Molnar74c383f2006-12-13 00:34:43 -08002013 graph_unlock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002014 goto cache_hit;
2015 }
2016 }
2017 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
Ingo Molnar74c383f2006-12-13 00:34:43 -08002018 if (!debug_locks_off_graph_unlock())
2019 return 0;
2020
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002021 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2022 printk("turning off the locking correctness validator.\n");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +01002023 dump_stack();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002024 return 0;
2025 }
2026 chain = lock_chains + nr_lock_chains++;
2027 chain->chain_key = chain_key;
Huang, Ying443cd502008-06-20 16:39:21 +08002028 chain->irq_context = hlock->irq_context;
2029 /* Find the first held_lock of current chain */
2030 hlock_next = hlock;
2031 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2032 hlock_curr = curr->held_locks + i;
2033 if (hlock_curr->irq_context != hlock_next->irq_context)
2034 break;
2035 hlock_next = hlock;
2036 }
2037 i++;
2038 chain->depth = curr->lockdep_depth + 1 - i;
Steven Rostedte0944ee2011-04-20 21:42:00 -04002039 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2040 chain->base = nr_chain_hlocks;
2041 nr_chain_hlocks += chain->depth;
Huang, Ying443cd502008-06-20 16:39:21 +08002042 for (j = 0; j < chain->depth - 1; j++, i++) {
Dave Jonesf82b2172008-08-11 09:30:23 +02002043 int lock_id = curr->held_locks[i].class_idx - 1;
Huang, Ying443cd502008-06-20 16:39:21 +08002044 chain_hlocks[chain->base + j] = lock_id;
2045 }
2046 chain_hlocks[chain->base + j] = class - lock_classes;
2047 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002048 list_add_tail_rcu(&chain->entry, hash_head);
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002049 debug_atomic_inc(chain_lookup_misses);
Peter Zijlstra8e182572007-07-19 01:48:54 -07002050 inc_chains();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002051
2052 return 1;
2053}
Peter Zijlstra8e182572007-07-19 01:48:54 -07002054
2055static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
Johannes Berg4e6045f2007-10-18 23:39:55 -07002056 struct held_lock *hlock, int chain_head, u64 chain_key)
Peter Zijlstra8e182572007-07-19 01:48:54 -07002057{
2058 /*
2059 * Trylock needs to maintain the stack of held locks, but it
2060 * does not add new dependencies, because trylock can be done
2061 * in any order.
2062 *
2063 * We look up the chain_key and do the O(N^2) check and update of
2064 * the dependencies only if this is a new dependency chain.
2065 * (If lookup_chain_cache() returns with 1 it acquires
2066 * graph_lock for us)
2067 */
2068 if (!hlock->trylock && (hlock->check == 2) &&
Huang, Ying443cd502008-06-20 16:39:21 +08002069 lookup_chain_cache(curr, hlock, chain_key)) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07002070 /*
2071 * Check whether last held lock:
2072 *
2073 * - is irq-safe, if this lock is irq-unsafe
2074 * - is softirq-safe, if this lock is hardirq-unsafe
2075 *
2076 * And check whether the new lock's dependency graph
2077 * could lead back to the previous lock.
2078 *
2079 * any of these scenarios could lead to a deadlock. If
2080 * All validations
2081 */
2082 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2083
2084 if (!ret)
2085 return 0;
2086 /*
2087 * Mark recursive read, as we jump over it when
2088 * building dependencies (just like we jump over
2089 * trylock entries):
2090 */
2091 if (ret == 2)
2092 hlock->read = 2;
2093 /*
2094 * Add dependency only if this lock is not the head
2095 * of the chain, and if it's not a secondary read-lock:
2096 */
2097 if (!chain_head && ret != 2)
2098 if (!check_prevs_add(curr, hlock))
2099 return 0;
2100 graph_unlock();
2101 } else
2102 /* after lookup_chain_cache(): */
2103 if (unlikely(!debug_locks))
2104 return 0;
2105
2106 return 1;
2107}
2108#else
2109static inline int validate_chain(struct task_struct *curr,
2110 struct lockdep_map *lock, struct held_lock *hlock,
Gregory Haskins3aa416b2007-10-11 22:11:11 +02002111 int chain_head, u64 chain_key)
Peter Zijlstra8e182572007-07-19 01:48:54 -07002112{
2113 return 1;
2114}
Peter Zijlstraca58abc2007-07-19 01:48:53 -07002115#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002116
2117/*
2118 * We are building curr_chain_key incrementally, so double-check
2119 * it from scratch, to make sure that it's done correctly:
2120 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002121static void check_chain_key(struct task_struct *curr)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002122{
2123#ifdef CONFIG_DEBUG_LOCKDEP
2124 struct held_lock *hlock, *prev_hlock = NULL;
2125 unsigned int i, id;
2126 u64 chain_key = 0;
2127
2128 for (i = 0; i < curr->lockdep_depth; i++) {
2129 hlock = curr->held_locks + i;
2130 if (chain_key != hlock->prev_chain_key) {
2131 debug_locks_off();
Arjan van de Ven2df8b1d2008-07-30 12:43:11 -07002132 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002133 curr->lockdep_depth, i,
2134 (unsigned long long)chain_key,
2135 (unsigned long long)hlock->prev_chain_key);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002136 return;
2137 }
Dave Jonesf82b2172008-08-11 09:30:23 +02002138 id = hlock->class_idx - 1;
Jarek Poplawski381a2292007-02-10 01:44:58 -08002139 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2140 return;
2141
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002142 if (prev_hlock && (prev_hlock->irq_context !=
2143 hlock->irq_context))
2144 chain_key = 0;
2145 chain_key = iterate_chain_key(chain_key, id);
2146 prev_hlock = hlock;
2147 }
2148 if (chain_key != curr->curr_chain_key) {
2149 debug_locks_off();
Arjan van de Ven2df8b1d2008-07-30 12:43:11 -07002150 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002151 curr->lockdep_depth, i,
2152 (unsigned long long)chain_key,
2153 (unsigned long long)curr->curr_chain_key);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002154 }
2155#endif
2156}
2157
Steven Rostedt282b5c22011-04-20 21:41:59 -04002158static void
2159print_usage_bug_scenario(struct held_lock *lock)
2160{
2161 struct lock_class *class = hlock_class(lock);
2162
2163 printk(" Possible unsafe locking scenario:\n\n");
2164 printk(" CPU0\n");
2165 printk(" ----\n");
2166 printk(" lock(");
2167 __print_lock_name(class);
2168 printk(");\n");
2169 printk(" <Interrupt>\n");
2170 printk(" lock(");
2171 __print_lock_name(class);
2172 printk(");\n");
2173 printk("\n *** DEADLOCK ***\n\n");
2174}
2175
Peter Zijlstra8e182572007-07-19 01:48:54 -07002176static int
2177print_usage_bug(struct task_struct *curr, struct held_lock *this,
2178 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2179{
2180 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2181 return 0;
2182
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07002183 printk("\n");
2184 printk("=================================\n");
2185 printk("[ INFO: inconsistent lock state ]\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07002186 print_kernel_version();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07002187 printk("---------------------------------\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07002188
2189 printk("inconsistent {%s} -> {%s} usage.\n",
2190 usage_str[prev_bit], usage_str[new_bit]);
2191
2192 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07002193 curr->comm, task_pid_nr(curr),
Peter Zijlstra8e182572007-07-19 01:48:54 -07002194 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2195 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2196 trace_hardirqs_enabled(curr),
2197 trace_softirqs_enabled(curr));
2198 print_lock(this);
2199
2200 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
Dave Jonesf82b2172008-08-11 09:30:23 +02002201 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07002202
2203 print_irqtrace_events(curr);
2204 printk("\nother info that might help us debug this:\n");
Steven Rostedt282b5c22011-04-20 21:41:59 -04002205 print_usage_bug_scenario(this);
2206
Peter Zijlstra8e182572007-07-19 01:48:54 -07002207 lockdep_print_held_locks(curr);
2208
2209 printk("\nstack backtrace:\n");
2210 dump_stack();
2211
2212 return 0;
2213}
2214
2215/*
2216 * Print out an error if an invalid bit is set:
2217 */
2218static inline int
2219valid_state(struct task_struct *curr, struct held_lock *this,
2220 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2221{
Dave Jonesf82b2172008-08-11 09:30:23 +02002222 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002223 return print_usage_bug(curr, this, bad_bit, new_bit);
2224 return 1;
2225}
2226
2227static int mark_lock(struct task_struct *curr, struct held_lock *this,
2228 enum lock_usage_bit new_bit);
2229
Steven Rostedt81d68a92008-05-12 21:20:42 +02002230#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002231
2232/*
2233 * print irq inversion bug:
2234 */
2235static int
Ming Lei24208ca2009-07-16 15:44:29 +02002236print_irq_inversion_bug(struct task_struct *curr,
2237 struct lock_list *root, struct lock_list *other,
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002238 struct held_lock *this, int forwards,
2239 const char *irqclass)
2240{
Steven Rostedtdad3d742011-04-20 21:41:57 -04002241 struct lock_list *entry = other;
2242 struct lock_list *middle = NULL;
2243 int depth;
2244
Ingo Molnar74c383f2006-12-13 00:34:43 -08002245 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002246 return 0;
2247
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07002248 printk("\n");
2249 printk("=========================================================\n");
2250 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
Dave Jones99de0552006-09-29 02:00:10 -07002251 print_kernel_version();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07002252 printk("---------------------------------------------------------\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002253 printk("%s/%d just changed the state of lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07002254 curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002255 print_lock(this);
2256 if (forwards)
Peter Zijlstra26575e22009-03-04 14:53:24 +01002257 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002258 else
Peter Zijlstra26575e22009-03-04 14:53:24 +01002259 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
Ming Lei24208ca2009-07-16 15:44:29 +02002260 print_lock_name(other->class);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002261 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2262
2263 printk("\nother info that might help us debug this:\n");
Steven Rostedtdad3d742011-04-20 21:41:57 -04002264
2265 /* Find a middle lock (if one exists) */
2266 depth = get_lock_depth(other);
2267 do {
2268 if (depth == 0 && (entry != root)) {
2269 printk("lockdep:%s bad path found in chain graph\n", __func__);
2270 break;
2271 }
2272 middle = entry;
2273 entry = get_lock_parent(entry);
2274 depth--;
2275 } while (entry && entry != root && (depth >= 0));
2276 if (forwards)
2277 print_irq_lock_scenario(root, other,
2278 middle ? middle->class : root->class, other->class);
2279 else
2280 print_irq_lock_scenario(other, root,
2281 middle ? middle->class : other->class, root->class);
2282
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002283 lockdep_print_held_locks(curr);
2284
Ming Lei24208ca2009-07-16 15:44:29 +02002285 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2286 if (!save_trace(&root->trace))
2287 return 0;
2288 print_shortest_lock_dependencies(other, root);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002289
2290 printk("\nstack backtrace:\n");
2291 dump_stack();
2292
2293 return 0;
2294}
2295
2296/*
2297 * Prove that in the forwards-direction subgraph starting at <this>
2298 * there is no lock matching <mask>:
2299 */
2300static int
2301check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2302 enum lock_usage_bit bit, const char *irqclass)
2303{
2304 int ret;
Ming Leid7aaba12009-07-16 15:44:29 +02002305 struct lock_list root;
2306 struct lock_list *uninitialized_var(target_entry);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002307
Ming Leid7aaba12009-07-16 15:44:29 +02002308 root.parent = NULL;
2309 root.class = hlock_class(this);
2310 ret = find_usage_forwards(&root, bit, &target_entry);
Peter Zijlstraaf012962009-07-16 15:44:29 +02002311 if (ret < 0)
2312 return print_bfs_bug(ret);
2313 if (ret == 1)
2314 return ret;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002315
Ming Lei24208ca2009-07-16 15:44:29 +02002316 return print_irq_inversion_bug(curr, &root, target_entry,
Ming Leid7aaba12009-07-16 15:44:29 +02002317 this, 1, irqclass);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002318}
2319
2320/*
2321 * Prove that in the backwards-direction subgraph starting at <this>
2322 * there is no lock matching <mask>:
2323 */
2324static int
2325check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2326 enum lock_usage_bit bit, const char *irqclass)
2327{
2328 int ret;
Ming Leid7aaba12009-07-16 15:44:29 +02002329 struct lock_list root;
2330 struct lock_list *uninitialized_var(target_entry);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002331
Ming Leid7aaba12009-07-16 15:44:29 +02002332 root.parent = NULL;
2333 root.class = hlock_class(this);
2334 ret = find_usage_backwards(&root, bit, &target_entry);
Peter Zijlstraaf012962009-07-16 15:44:29 +02002335 if (ret < 0)
2336 return print_bfs_bug(ret);
2337 if (ret == 1)
2338 return ret;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002339
Ming Lei24208ca2009-07-16 15:44:29 +02002340 return print_irq_inversion_bug(curr, &root, target_entry,
Oleg Nesterov48d50672010-01-26 19:16:41 +01002341 this, 0, irqclass);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002342}
2343
Ingo Molnar3117df02006-12-13 00:34:43 -08002344void print_irqtrace_events(struct task_struct *curr)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002345{
2346 printk("irq event stamp: %u\n", curr->irq_events);
2347 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2348 print_ip_sym(curr->hardirq_enable_ip);
2349 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2350 print_ip_sym(curr->hardirq_disable_ip);
2351 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2352 print_ip_sym(curr->softirq_enable_ip);
2353 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2354 print_ip_sym(curr->softirq_disable_ip);
2355}
2356
Peter Zijlstracd953022009-01-22 16:38:21 +01002357static int HARDIRQ_verbose(struct lock_class *class)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002358{
Peter Zijlstra8e182572007-07-19 01:48:54 -07002359#if HARDIRQ_VERBOSE
2360 return class_filter(class);
2361#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002362 return 0;
2363}
2364
Peter Zijlstracd953022009-01-22 16:38:21 +01002365static int SOFTIRQ_verbose(struct lock_class *class)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002366{
Peter Zijlstra8e182572007-07-19 01:48:54 -07002367#if SOFTIRQ_VERBOSE
2368 return class_filter(class);
2369#endif
2370 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002371}
2372
Peter Zijlstracd953022009-01-22 16:38:21 +01002373static int RECLAIM_FS_verbose(struct lock_class *class)
Nick Piggincf40bd12009-01-21 08:12:39 +01002374{
2375#if RECLAIM_VERBOSE
2376 return class_filter(class);
2377#endif
2378 return 0;
2379}
2380
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002381#define STRICT_READ_CHECKS 1
2382
Peter Zijlstracd953022009-01-22 16:38:21 +01002383static int (*state_verbose_f[])(struct lock_class *class) = {
2384#define LOCKDEP_STATE(__STATE) \
2385 __STATE##_verbose,
2386#include "lockdep_states.h"
2387#undef LOCKDEP_STATE
2388};
2389
2390static inline int state_verbose(enum lock_usage_bit bit,
2391 struct lock_class *class)
2392{
2393 return state_verbose_f[bit >> 2](class);
2394}
2395
Peter Zijlstra42c50d52009-01-22 16:58:16 +01002396typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2397 enum lock_usage_bit bit, const char *name);
2398
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002399static int
Peter Zijlstra1c21f142009-03-04 13:51:13 +01002400mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2401 enum lock_usage_bit new_bit)
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002402{
Peter Zijlstraf9892092009-01-22 16:09:59 +01002403 int excl_bit = exclusive_bit(new_bit);
Peter Zijlstra9d3651a2009-01-22 17:18:32 +01002404 int read = new_bit & 1;
Peter Zijlstra42c50d52009-01-22 16:58:16 +01002405 int dir = new_bit & 2;
2406
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002407 /*
2408 * mark USED_IN has to look forwards -- to ensure no dependency
2409 * has ENABLED state, which would allow recursion deadlocks.
2410 *
2411 * mark ENABLED has to look backwards -- to ensure no dependee
2412 * has USED_IN state, which, again, would allow recursion deadlocks.
2413 */
Peter Zijlstra42c50d52009-01-22 16:58:16 +01002414 check_usage_f usage = dir ?
2415 check_usage_backwards : check_usage_forwards;
Peter Zijlstraf9892092009-01-22 16:09:59 +01002416
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002417 /*
2418 * Validate that this particular lock does not have conflicting
2419 * usage states.
2420 */
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002421 if (!valid_state(curr, this, new_bit, excl_bit))
2422 return 0;
Peter Zijlstra9d3651a2009-01-22 17:18:32 +01002423
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002424 /*
2425 * Validate that the lock dependencies don't have conflicting usage
2426 * states.
2427 */
2428 if ((!read || !dir || STRICT_READ_CHECKS) &&
Peter Zijlstra1c21f142009-03-04 13:51:13 +01002429 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002430 return 0;
Peter Zijlstra780e8202009-01-22 16:51:29 +01002431
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002432 /*
2433 * Check for read in write conflicts
2434 */
2435 if (!read) {
2436 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2437 return 0;
2438
2439 if (STRICT_READ_CHECKS &&
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01002440 !usage(curr, this, excl_bit + 1,
2441 state_name(new_bit + 1)))
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002442 return 0;
2443 }
Peter Zijlstra780e8202009-01-22 16:51:29 +01002444
Peter Zijlstracd953022009-01-22 16:38:21 +01002445 if (state_verbose(new_bit, hlock_class(this)))
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002446 return 2;
2447
2448 return 1;
2449}
2450
Nick Piggincf40bd12009-01-21 08:12:39 +01002451enum mark_type {
Peter Zijlstra36bfb9b2009-01-22 14:12:41 +01002452#define LOCKDEP_STATE(__STATE) __STATE,
2453#include "lockdep_states.h"
2454#undef LOCKDEP_STATE
Nick Piggincf40bd12009-01-21 08:12:39 +01002455};
2456
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002457/*
2458 * Mark all held locks with a usage bit:
2459 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002460static int
Nick Piggincf40bd12009-01-21 08:12:39 +01002461mark_held_locks(struct task_struct *curr, enum mark_type mark)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002462{
2463 enum lock_usage_bit usage_bit;
2464 struct held_lock *hlock;
2465 int i;
2466
2467 for (i = 0; i < curr->lockdep_depth; i++) {
2468 hlock = curr->held_locks + i;
2469
Peter Zijlstracf2ad4d2009-01-27 13:58:08 +01002470 usage_bit = 2 + (mark << 2); /* ENABLED */
2471 if (hlock->read)
2472 usage_bit += 1; /* READ */
2473
2474 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
Nick Piggincf40bd12009-01-21 08:12:39 +01002475
Peter Zijlstra70a06862011-07-25 12:09:59 +02002476 if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
Peter Zijlstraefbe2ee2011-07-07 11:39:45 +02002477 continue;
2478
Jarek Poplawski4ff773bb2007-05-08 00:31:00 -07002479 if (!mark_lock(curr, hlock, usage_bit))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002480 return 0;
2481 }
2482
2483 return 1;
2484}
2485
2486/*
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002487 * Hardirqs will be enabled:
2488 */
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002489static void __trace_hardirqs_on_caller(unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002490{
2491 struct task_struct *curr = current;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002492
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002493 /* we'll do an OFF -> ON transition: */
2494 curr->hardirqs_enabled = 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002495
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002496 /*
2497 * We are going to turn hardirqs on, so set the
2498 * usage bit for all held locks:
2499 */
Nick Piggincf40bd12009-01-21 08:12:39 +01002500 if (!mark_held_locks(curr, HARDIRQ))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002501 return;
2502 /*
2503 * If we have softirqs enabled, then set the usage
2504 * bit for all held locks. (disabled hardirqs prevented
2505 * this bit from being set before)
2506 */
2507 if (curr->softirqs_enabled)
Nick Piggincf40bd12009-01-21 08:12:39 +01002508 if (!mark_held_locks(curr, SOFTIRQ))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002509 return;
2510
2511 curr->hardirq_enable_ip = ip;
2512 curr->hardirq_enable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002513 debug_atomic_inc(hardirqs_on_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002514}
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002515
2516void trace_hardirqs_on_caller(unsigned long ip)
2517{
2518 time_hardirqs_on(CALLER_ADDR0, ip);
2519
2520 if (unlikely(!debug_locks || current->lockdep_recursion))
2521 return;
2522
Peter Zijlstra7d36b262011-07-26 13:13:44 +02002523 if (unlikely(current->hardirqs_enabled)) {
2524 /*
2525 * Neither irq nor preemption are disabled here
2526 * so this is racy by nature but losing one hit
2527 * in a stat is not a big deal.
2528 */
2529 __debug_atomic_inc(redundant_hardirqs_on);
2530 return;
2531 }
2532
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002533 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2534 return;
2535
Peter Zijlstra7d36b262011-07-26 13:13:44 +02002536 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2537 return;
2538
2539 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2540 return;
2541
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002542 current->lockdep_recursion = 1;
2543 __trace_hardirqs_on_caller(ip);
2544 current->lockdep_recursion = 0;
2545}
Steven Rostedt81d68a92008-05-12 21:20:42 +02002546EXPORT_SYMBOL(trace_hardirqs_on_caller);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002547
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002548void trace_hardirqs_on(void)
Steven Rostedt81d68a92008-05-12 21:20:42 +02002549{
2550 trace_hardirqs_on_caller(CALLER_ADDR0);
2551}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002552EXPORT_SYMBOL(trace_hardirqs_on);
2553
2554/*
2555 * Hardirqs were disabled:
2556 */
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002557void trace_hardirqs_off_caller(unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002558{
2559 struct task_struct *curr = current;
2560
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002561 time_hardirqs_off(CALLER_ADDR0, ip);
Steven Rostedt81d68a92008-05-12 21:20:42 +02002562
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002563 if (unlikely(!debug_locks || current->lockdep_recursion))
2564 return;
2565
2566 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2567 return;
2568
2569 if (curr->hardirqs_enabled) {
2570 /*
2571 * We have done an ON -> OFF transition:
2572 */
2573 curr->hardirqs_enabled = 0;
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002574 curr->hardirq_disable_ip = ip;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002575 curr->hardirq_disable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002576 debug_atomic_inc(hardirqs_off_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002577 } else
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002578 debug_atomic_inc(redundant_hardirqs_off);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002579}
Steven Rostedt81d68a92008-05-12 21:20:42 +02002580EXPORT_SYMBOL(trace_hardirqs_off_caller);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002581
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002582void trace_hardirqs_off(void)
Steven Rostedt81d68a92008-05-12 21:20:42 +02002583{
2584 trace_hardirqs_off_caller(CALLER_ADDR0);
2585}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002586EXPORT_SYMBOL(trace_hardirqs_off);
2587
2588/*
2589 * Softirqs will be enabled:
2590 */
2591void trace_softirqs_on(unsigned long ip)
2592{
2593 struct task_struct *curr = current;
2594
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002595 if (unlikely(!debug_locks || current->lockdep_recursion))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002596 return;
2597
2598 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2599 return;
2600
2601 if (curr->softirqs_enabled) {
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002602 debug_atomic_inc(redundant_softirqs_on);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002603 return;
2604 }
2605
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002606 current->lockdep_recursion = 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002607 /*
2608 * We'll do an OFF -> ON transition:
2609 */
2610 curr->softirqs_enabled = 1;
2611 curr->softirq_enable_ip = ip;
2612 curr->softirq_enable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002613 debug_atomic_inc(softirqs_on_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002614 /*
2615 * We are going to turn softirqs on, so set the
2616 * usage bit for all held locks, if hardirqs are
2617 * enabled too:
2618 */
2619 if (curr->hardirqs_enabled)
Nick Piggincf40bd12009-01-21 08:12:39 +01002620 mark_held_locks(curr, SOFTIRQ);
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002621 current->lockdep_recursion = 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002622}
2623
2624/*
2625 * Softirqs were disabled:
2626 */
2627void trace_softirqs_off(unsigned long ip)
2628{
2629 struct task_struct *curr = current;
2630
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002631 if (unlikely(!debug_locks || current->lockdep_recursion))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002632 return;
2633
2634 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2635 return;
2636
2637 if (curr->softirqs_enabled) {
2638 /*
2639 * We have done an ON -> OFF transition:
2640 */
2641 curr->softirqs_enabled = 0;
2642 curr->softirq_disable_ip = ip;
2643 curr->softirq_disable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002644 debug_atomic_inc(softirqs_off_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002645 DEBUG_LOCKS_WARN_ON(!softirq_count());
2646 } else
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002647 debug_atomic_inc(redundant_softirqs_off);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002648}
2649
Peter Zijlstra2f850182009-03-20 11:13:20 +01002650static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
Nick Piggincf40bd12009-01-21 08:12:39 +01002651{
2652 struct task_struct *curr = current;
2653
2654 if (unlikely(!debug_locks))
2655 return;
2656
2657 /* no reclaim without waiting on it */
2658 if (!(gfp_mask & __GFP_WAIT))
2659 return;
2660
2661 /* this guy won't enter reclaim */
2662 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2663 return;
2664
2665 /* We're only interested __GFP_FS allocations for now */
2666 if (!(gfp_mask & __GFP_FS))
2667 return;
2668
Peter Zijlstra2f850182009-03-20 11:13:20 +01002669 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
Nick Piggincf40bd12009-01-21 08:12:39 +01002670 return;
2671
2672 mark_held_locks(curr, RECLAIM_FS);
2673}
2674
Peter Zijlstra2f850182009-03-20 11:13:20 +01002675static void check_flags(unsigned long flags);
2676
2677void lockdep_trace_alloc(gfp_t gfp_mask)
2678{
2679 unsigned long flags;
2680
2681 if (unlikely(current->lockdep_recursion))
2682 return;
2683
2684 raw_local_irq_save(flags);
2685 check_flags(flags);
2686 current->lockdep_recursion = 1;
2687 __lockdep_trace_alloc(gfp_mask, flags);
2688 current->lockdep_recursion = 0;
2689 raw_local_irq_restore(flags);
2690}
2691
Peter Zijlstra8e182572007-07-19 01:48:54 -07002692static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2693{
2694 /*
2695 * If non-trylock use in a hardirq or softirq context, then
2696 * mark the lock as used in these contexts:
2697 */
2698 if (!hlock->trylock) {
2699 if (hlock->read) {
2700 if (curr->hardirq_context)
2701 if (!mark_lock(curr, hlock,
2702 LOCK_USED_IN_HARDIRQ_READ))
2703 return 0;
2704 if (curr->softirq_context)
2705 if (!mark_lock(curr, hlock,
2706 LOCK_USED_IN_SOFTIRQ_READ))
2707 return 0;
2708 } else {
2709 if (curr->hardirq_context)
2710 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2711 return 0;
2712 if (curr->softirq_context)
2713 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2714 return 0;
2715 }
2716 }
2717 if (!hlock->hardirqs_off) {
2718 if (hlock->read) {
2719 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002720 LOCK_ENABLED_HARDIRQ_READ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002721 return 0;
2722 if (curr->softirqs_enabled)
2723 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002724 LOCK_ENABLED_SOFTIRQ_READ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002725 return 0;
2726 } else {
2727 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002728 LOCK_ENABLED_HARDIRQ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002729 return 0;
2730 if (curr->softirqs_enabled)
2731 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002732 LOCK_ENABLED_SOFTIRQ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002733 return 0;
2734 }
2735 }
2736
Nick Piggincf40bd12009-01-21 08:12:39 +01002737 /*
2738 * We reuse the irq context infrastructure more broadly as a general
2739 * context checking code. This tests GFP_FS recursion (a lock taken
2740 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2741 * allocation).
2742 */
2743 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2744 if (hlock->read) {
2745 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2746 return 0;
2747 } else {
2748 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2749 return 0;
2750 }
2751 }
2752
Peter Zijlstra8e182572007-07-19 01:48:54 -07002753 return 1;
2754}
2755
2756static int separate_irq_context(struct task_struct *curr,
2757 struct held_lock *hlock)
2758{
2759 unsigned int depth = curr->lockdep_depth;
2760
2761 /*
2762 * Keep track of points where we cross into an interrupt context:
2763 */
2764 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2765 curr->softirq_context;
2766 if (depth) {
2767 struct held_lock *prev_hlock;
2768
2769 prev_hlock = curr->held_locks + depth-1;
2770 /*
2771 * If we cross into another context, reset the
2772 * hash key (this also prevents the checking and the
2773 * adding of the dependency to 'prev'):
2774 */
2775 if (prev_hlock->irq_context != hlock->irq_context)
2776 return 1;
2777 }
2778 return 0;
2779}
2780
2781#else
2782
2783static inline
2784int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2785 enum lock_usage_bit new_bit)
2786{
2787 WARN_ON(1);
2788 return 1;
2789}
2790
2791static inline int mark_irqflags(struct task_struct *curr,
2792 struct held_lock *hlock)
2793{
2794 return 1;
2795}
2796
2797static inline int separate_irq_context(struct task_struct *curr,
2798 struct held_lock *hlock)
2799{
2800 return 0;
2801}
2802
Peter Zijlstra868a23a2009-02-15 00:25:21 +01002803void lockdep_trace_alloc(gfp_t gfp_mask)
2804{
2805}
2806
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002807#endif
2808
2809/*
Peter Zijlstra8e182572007-07-19 01:48:54 -07002810 * Mark a lock with a usage bit, and validate the state transition:
2811 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002812static int mark_lock(struct task_struct *curr, struct held_lock *this,
Steven Rostedt0764d232008-05-12 21:20:44 +02002813 enum lock_usage_bit new_bit)
Peter Zijlstra8e182572007-07-19 01:48:54 -07002814{
2815 unsigned int new_mask = 1 << new_bit, ret = 1;
2816
2817 /*
2818 * If already set then do not dirty the cacheline,
2819 * nor do any checks:
2820 */
Dave Jonesf82b2172008-08-11 09:30:23 +02002821 if (likely(hlock_class(this)->usage_mask & new_mask))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002822 return 1;
2823
2824 if (!graph_lock())
2825 return 0;
2826 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03002827 * Make sure we didn't race:
Peter Zijlstra8e182572007-07-19 01:48:54 -07002828 */
Dave Jonesf82b2172008-08-11 09:30:23 +02002829 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07002830 graph_unlock();
2831 return 1;
2832 }
2833
Dave Jonesf82b2172008-08-11 09:30:23 +02002834 hlock_class(this)->usage_mask |= new_mask;
Peter Zijlstra8e182572007-07-19 01:48:54 -07002835
Dave Jonesf82b2172008-08-11 09:30:23 +02002836 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002837 return 0;
2838
2839 switch (new_bit) {
Peter Zijlstra53464172009-01-22 14:15:53 +01002840#define LOCKDEP_STATE(__STATE) \
2841 case LOCK_USED_IN_##__STATE: \
2842 case LOCK_USED_IN_##__STATE##_READ: \
2843 case LOCK_ENABLED_##__STATE: \
2844 case LOCK_ENABLED_##__STATE##_READ:
2845#include "lockdep_states.h"
2846#undef LOCKDEP_STATE
Peter Zijlstra8e182572007-07-19 01:48:54 -07002847 ret = mark_lock_irq(curr, this, new_bit);
2848 if (!ret)
2849 return 0;
2850 break;
2851 case LOCK_USED:
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002852 debug_atomic_dec(nr_unused_locks);
Peter Zijlstra8e182572007-07-19 01:48:54 -07002853 break;
2854 default:
2855 if (!debug_locks_off_graph_unlock())
2856 return 0;
2857 WARN_ON(1);
2858 return 0;
2859 }
2860
2861 graph_unlock();
2862
2863 /*
2864 * We must printk outside of the graph_lock:
2865 */
2866 if (ret == 2) {
2867 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2868 print_lock(this);
2869 print_irqtrace_events(curr);
2870 dump_stack();
2871 }
2872
2873 return ret;
2874}
2875
2876/*
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002877 * Initialize a lock instance's lock-class mapping info:
2878 */
2879void lockdep_init_map(struct lockdep_map *lock, const char *name,
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04002880 struct lock_class_key *key, int subclass)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002881{
Tejun Heof59de892011-07-14 15:19:09 +02002882 memset(lock, 0, sizeof(*lock));
Hitoshi Mitake62016252010-10-05 18:01:51 +09002883
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002884#ifdef CONFIG_LOCK_STAT
2885 lock->cpu = raw_smp_processor_id();
2886#endif
2887
2888 if (DEBUG_LOCKS_WARN_ON(!name)) {
2889 lock->name = "NULL";
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002890 return;
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002891 }
2892
2893 lock->name = name;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002894
2895 if (DEBUG_LOCKS_WARN_ON(!key))
2896 return;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002897 /*
2898 * Sanity check, the lock-class key must be persistent:
2899 */
2900 if (!static_obj(key)) {
2901 printk("BUG: key %p not in .data!\n", key);
2902 DEBUG_LOCKS_WARN_ON(1);
2903 return;
2904 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002905 lock->key = key;
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002906
2907 if (unlikely(!debug_locks))
2908 return;
2909
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04002910 if (subclass)
2911 register_lock_class(lock, subclass, 1);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002912}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002913EXPORT_SYMBOL_GPL(lockdep_init_map);
2914
Peter Zijlstra1704f472010-03-19 01:37:42 +01002915struct lock_class_key __lockdep_no_validate__;
2916
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002917/*
2918 * This gets called for every mutex_lock*()/spin_lock*() operation.
2919 * We maintain the dependency maps and validate the locking attempt:
2920 */
2921static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2922 int trylock, int read, int check, int hardirqs_off,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02002923 struct lockdep_map *nest_lock, unsigned long ip,
2924 int references)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002925{
2926 struct task_struct *curr = current;
Ingo Molnard6d897c2006-07-10 04:44:04 -07002927 struct lock_class *class = NULL;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002928 struct held_lock *hlock;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002929 unsigned int depth, id;
2930 int chain_head = 0;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02002931 int class_idx;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002932 u64 chain_key;
2933
Peter Zijlstraf20786f2007-07-19 01:48:56 -07002934 if (!prove_locking)
2935 check = 1;
2936
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002937 if (unlikely(!debug_locks))
2938 return 0;
2939
2940 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2941 return 0;
2942
Peter Zijlstra1704f472010-03-19 01:37:42 +01002943 if (lock->key == &__lockdep_no_validate__)
2944 check = 1;
2945
Hitoshi Mitake62016252010-10-05 18:01:51 +09002946 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
2947 class = lock->class_cache[subclass];
Ingo Molnard6d897c2006-07-10 04:44:04 -07002948 /*
Hitoshi Mitake62016252010-10-05 18:01:51 +09002949 * Not cached?
Ingo Molnard6d897c2006-07-10 04:44:04 -07002950 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002951 if (unlikely(!class)) {
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04002952 class = register_lock_class(lock, subclass, 0);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002953 if (!class)
2954 return 0;
2955 }
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002956 atomic_inc((atomic_t *)&class->ops);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002957 if (very_verbose(class)) {
2958 printk("\nacquire class [%p] %s", class->key, class->name);
2959 if (class->name_version > 1)
2960 printk("#%d", class->name_version);
2961 printk("\n");
2962 dump_stack();
2963 }
2964
2965 /*
2966 * Add the lock to the list of currently held locks.
2967 * (we dont increase the depth just yet, up until the
2968 * dependency checks are done)
2969 */
2970 depth = curr->lockdep_depth;
2971 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2972 return 0;
2973
Peter Zijlstrabb97a912009-07-20 19:15:35 +02002974 class_idx = class - lock_classes + 1;
2975
2976 if (depth) {
2977 hlock = curr->held_locks + depth - 1;
2978 if (hlock->class_idx == class_idx && nest_lock) {
2979 if (hlock->references)
2980 hlock->references++;
2981 else
2982 hlock->references = 2;
2983
2984 return 1;
2985 }
2986 }
2987
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002988 hlock = curr->held_locks + depth;
Dave Jonesf82b2172008-08-11 09:30:23 +02002989 if (DEBUG_LOCKS_WARN_ON(!class))
2990 return 0;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02002991 hlock->class_idx = class_idx;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002992 hlock->acquire_ip = ip;
2993 hlock->instance = lock;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02002994 hlock->nest_lock = nest_lock;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002995 hlock->trylock = trylock;
2996 hlock->read = read;
2997 hlock->check = check;
Dmitry Baryshkov6951b122008-08-18 04:26:37 +04002998 hlock->hardirqs_off = !!hardirqs_off;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02002999 hlock->references = references;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003000#ifdef CONFIG_LOCK_STAT
3001 hlock->waittime_stamp = 0;
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003002 hlock->holdtime_stamp = lockstat_clock();
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003003#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003004
Peter Zijlstra8e182572007-07-19 01:48:54 -07003005 if (check == 2 && !mark_irqflags(curr, hlock))
3006 return 0;
3007
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003008 /* mark it as used: */
Jarek Poplawski4ff773bb2007-05-08 00:31:00 -07003009 if (!mark_lock(curr, hlock, LOCK_USED))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003010 return 0;
Peter Zijlstra8e182572007-07-19 01:48:54 -07003011
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003012 /*
Gautham R Shenoy17aacfb2007-10-28 20:47:01 +01003013 * Calculate the chain hash: it's the combined hash of all the
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003014 * lock keys along the dependency chain. We save the hash value
3015 * at every step so that we can get the current hash easily
3016 * after unlock. The chain hash is then used to cache dependency
3017 * results.
3018 *
3019 * The 'key ID' is what is the most compact key value to drive
3020 * the hash, not class->key.
3021 */
3022 id = class - lock_classes;
3023 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3024 return 0;
3025
3026 chain_key = curr->curr_chain_key;
3027 if (!depth) {
3028 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3029 return 0;
3030 chain_head = 1;
3031 }
3032
3033 hlock->prev_chain_key = chain_key;
Peter Zijlstra8e182572007-07-19 01:48:54 -07003034 if (separate_irq_context(curr, hlock)) {
3035 chain_key = 0;
3036 chain_head = 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003037 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003038 chain_key = iterate_chain_key(chain_key, id);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003039
Gregory Haskins3aa416b2007-10-11 22:11:11 +02003040 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
Peter Zijlstra8e182572007-07-19 01:48:54 -07003041 return 0;
Jarek Poplawski381a2292007-02-10 01:44:58 -08003042
Gregory Haskins3aa416b2007-10-11 22:11:11 +02003043 curr->curr_chain_key = chain_key;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003044 curr->lockdep_depth++;
3045 check_chain_key(curr);
Jarek Poplawski60e114d2007-02-20 13:58:00 -08003046#ifdef CONFIG_DEBUG_LOCKDEP
3047 if (unlikely(!debug_locks))
3048 return 0;
3049#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003050 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3051 debug_locks_off();
3052 printk("BUG: MAX_LOCK_DEPTH too low!\n");
3053 printk("turning off the locking correctness validator.\n");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +01003054 dump_stack();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003055 return 0;
3056 }
Jarek Poplawski381a2292007-02-10 01:44:58 -08003057
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003058 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3059 max_lockdep_depth = curr->lockdep_depth;
3060
3061 return 1;
3062}
3063
3064static int
3065print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3066 unsigned long ip)
3067{
3068 if (!debug_locks_off())
3069 return 0;
3070 if (debug_locks_silent)
3071 return 0;
3072
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07003073 printk("\n");
3074 printk("=====================================\n");
3075 printk("[ BUG: bad unlock balance detected! ]\n");
3076 printk("-------------------------------------\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003077 printk("%s/%d is trying to release lock (",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003078 curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003079 print_lockdep_cache(lock);
3080 printk(") at:\n");
3081 print_ip_sym(ip);
3082 printk("but there are no more locks to release!\n");
3083 printk("\nother info that might help us debug this:\n");
3084 lockdep_print_held_locks(curr);
3085
3086 printk("\nstack backtrace:\n");
3087 dump_stack();
3088
3089 return 0;
3090}
3091
3092/*
3093 * Common debugging checks for both nested and non-nested unlock:
3094 */
3095static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3096 unsigned long ip)
3097{
3098 if (unlikely(!debug_locks))
3099 return 0;
3100 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3101 return 0;
3102
3103 if (curr->lockdep_depth <= 0)
3104 return print_unlock_inbalance_bug(curr, lock, ip);
3105
3106 return 1;
3107}
3108
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003109static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3110{
3111 if (hlock->instance == lock)
3112 return 1;
3113
3114 if (hlock->references) {
Hitoshi Mitake62016252010-10-05 18:01:51 +09003115 struct lock_class *class = lock->class_cache[0];
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003116
3117 if (!class)
3118 class = look_up_lock_class(lock, 0);
3119
Peter Zijlstra80e04012011-08-05 14:26:17 +02003120 /*
3121 * If look_up_lock_class() failed to find a class, we're trying
3122 * to test if we hold a lock that has never yet been acquired.
3123 * Clearly if the lock hasn't been acquired _ever_, we're not
3124 * holding it either, so report failure.
3125 */
3126 if (!class)
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003127 return 0;
3128
3129 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3130 return 0;
3131
3132 if (hlock->class_idx == class - lock_classes + 1)
3133 return 1;
3134 }
3135
3136 return 0;
3137}
3138
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003139static int
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003140__lock_set_class(struct lockdep_map *lock, const char *name,
3141 struct lock_class_key *key, unsigned int subclass,
3142 unsigned long ip)
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003143{
3144 struct task_struct *curr = current;
3145 struct held_lock *hlock, *prev_hlock;
3146 struct lock_class *class;
3147 unsigned int depth;
3148 int i;
3149
3150 depth = curr->lockdep_depth;
3151 if (DEBUG_LOCKS_WARN_ON(!depth))
3152 return 0;
3153
3154 prev_hlock = NULL;
3155 for (i = depth-1; i >= 0; i--) {
3156 hlock = curr->held_locks + i;
3157 /*
3158 * We must not cross into another context:
3159 */
3160 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3161 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003162 if (match_held_lock(hlock, lock))
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003163 goto found_it;
3164 prev_hlock = hlock;
3165 }
3166 return print_unlock_inbalance_bug(curr, lock, ip);
3167
3168found_it:
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003169 lockdep_init_map(lock, name, key, 0);
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003170 class = register_lock_class(lock, subclass, 0);
Dave Jonesf82b2172008-08-11 09:30:23 +02003171 hlock->class_idx = class - lock_classes + 1;
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003172
3173 curr->lockdep_depth = i;
3174 curr->curr_chain_key = hlock->prev_chain_key;
3175
3176 for (; i < depth; i++) {
3177 hlock = curr->held_locks + i;
3178 if (!__lock_acquire(hlock->instance,
Dave Jonesf82b2172008-08-11 09:30:23 +02003179 hlock_class(hlock)->subclass, hlock->trylock,
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003180 hlock->read, hlock->check, hlock->hardirqs_off,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003181 hlock->nest_lock, hlock->acquire_ip,
3182 hlock->references))
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003183 return 0;
3184 }
3185
3186 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3187 return 0;
3188 return 1;
3189}
3190
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003191/*
3192 * Remove the lock to the list of currently held locks in a
3193 * potentially non-nested (out of order) manner. This is a
3194 * relatively rare operation, as all the unlock APIs default
3195 * to nested mode (which uses lock_release()):
3196 */
3197static int
3198lock_release_non_nested(struct task_struct *curr,
3199 struct lockdep_map *lock, unsigned long ip)
3200{
3201 struct held_lock *hlock, *prev_hlock;
3202 unsigned int depth;
3203 int i;
3204
3205 /*
3206 * Check whether the lock exists in the current stack
3207 * of held locks:
3208 */
3209 depth = curr->lockdep_depth;
3210 if (DEBUG_LOCKS_WARN_ON(!depth))
3211 return 0;
3212
3213 prev_hlock = NULL;
3214 for (i = depth-1; i >= 0; i--) {
3215 hlock = curr->held_locks + i;
3216 /*
3217 * We must not cross into another context:
3218 */
3219 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3220 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003221 if (match_held_lock(hlock, lock))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003222 goto found_it;
3223 prev_hlock = hlock;
3224 }
3225 return print_unlock_inbalance_bug(curr, lock, ip);
3226
3227found_it:
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003228 if (hlock->instance == lock)
3229 lock_release_holdtime(hlock);
3230
3231 if (hlock->references) {
3232 hlock->references--;
3233 if (hlock->references) {
3234 /*
3235 * We had, and after removing one, still have
3236 * references, the current lock stack is still
3237 * valid. We're done!
3238 */
3239 return 1;
3240 }
3241 }
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003242
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003243 /*
3244 * We have the right lock to unlock, 'hlock' points to it.
3245 * Now we remove it from the stack, and add back the other
3246 * entries (if any), recalculating the hash along the way:
3247 */
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003248
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003249 curr->lockdep_depth = i;
3250 curr->curr_chain_key = hlock->prev_chain_key;
3251
3252 for (i++; i < depth; i++) {
3253 hlock = curr->held_locks + i;
3254 if (!__lock_acquire(hlock->instance,
Dave Jonesf82b2172008-08-11 09:30:23 +02003255 hlock_class(hlock)->subclass, hlock->trylock,
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003256 hlock->read, hlock->check, hlock->hardirqs_off,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003257 hlock->nest_lock, hlock->acquire_ip,
3258 hlock->references))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003259 return 0;
3260 }
3261
3262 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3263 return 0;
3264 return 1;
3265}
3266
3267/*
3268 * Remove the lock to the list of currently held locks - this gets
3269 * called on mutex_unlock()/spin_unlock*() (or on a failed
3270 * mutex_lock_interruptible()). This is done for unlocks that nest
3271 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3272 */
3273static int lock_release_nested(struct task_struct *curr,
3274 struct lockdep_map *lock, unsigned long ip)
3275{
3276 struct held_lock *hlock;
3277 unsigned int depth;
3278
3279 /*
3280 * Pop off the top of the lock stack:
3281 */
3282 depth = curr->lockdep_depth - 1;
3283 hlock = curr->held_locks + depth;
3284
3285 /*
3286 * Is the unlock non-nested:
3287 */
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003288 if (hlock->instance != lock || hlock->references)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003289 return lock_release_non_nested(curr, lock, ip);
3290 curr->lockdep_depth--;
3291
3292 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3293 return 0;
3294
3295 curr->curr_chain_key = hlock->prev_chain_key;
3296
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003297 lock_release_holdtime(hlock);
3298
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003299#ifdef CONFIG_DEBUG_LOCKDEP
3300 hlock->prev_chain_key = 0;
Dave Jonesf82b2172008-08-11 09:30:23 +02003301 hlock->class_idx = 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003302 hlock->acquire_ip = 0;
3303 hlock->irq_context = 0;
3304#endif
3305 return 1;
3306}
3307
3308/*
3309 * Remove the lock to the list of currently held locks - this gets
3310 * called on mutex_unlock()/spin_unlock*() (or on a failed
3311 * mutex_lock_interruptible()). This is done for unlocks that nest
3312 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3313 */
3314static void
3315__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3316{
3317 struct task_struct *curr = current;
3318
3319 if (!check_unlock(curr, lock, ip))
3320 return;
3321
3322 if (nested) {
3323 if (!lock_release_nested(curr, lock, ip))
3324 return;
3325 } else {
3326 if (!lock_release_non_nested(curr, lock, ip))
3327 return;
3328 }
3329
3330 check_chain_key(curr);
3331}
3332
Peter Zijlstraf607c662009-07-20 19:16:29 +02003333static int __lock_is_held(struct lockdep_map *lock)
3334{
3335 struct task_struct *curr = current;
3336 int i;
3337
3338 for (i = 0; i < curr->lockdep_depth; i++) {
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003339 struct held_lock *hlock = curr->held_locks + i;
3340
3341 if (match_held_lock(hlock, lock))
Peter Zijlstraf607c662009-07-20 19:16:29 +02003342 return 1;
3343 }
3344
3345 return 0;
3346}
3347
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003348/*
3349 * Check whether we follow the irq-flags state precisely:
3350 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02003351static void check_flags(unsigned long flags)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003352{
Ingo Molnar992860e2008-07-14 10:28:38 +02003353#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3354 defined(CONFIG_TRACE_IRQFLAGS)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003355 if (!debug_locks)
3356 return;
3357
Ingo Molnar5f9fa8a2007-12-07 19:02:47 +01003358 if (irqs_disabled_flags(flags)) {
3359 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3360 printk("possible reason: unannotated irqs-off.\n");
3361 }
3362 } else {
3363 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3364 printk("possible reason: unannotated irqs-on.\n");
3365 }
3366 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003367
3368 /*
3369 * We dont accurately track softirq state in e.g.
3370 * hardirq contexts (such as on 4KSTACKS), so only
3371 * check if not in hardirq contexts:
3372 */
3373 if (!hardirq_count()) {
3374 if (softirq_count())
3375 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3376 else
3377 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3378 }
3379
3380 if (!debug_locks)
3381 print_irqtrace_events(current);
3382#endif
3383}
3384
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003385void lock_set_class(struct lockdep_map *lock, const char *name,
3386 struct lock_class_key *key, unsigned int subclass,
3387 unsigned long ip)
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003388{
3389 unsigned long flags;
3390
3391 if (unlikely(current->lockdep_recursion))
3392 return;
3393
3394 raw_local_irq_save(flags);
3395 current->lockdep_recursion = 1;
3396 check_flags(flags);
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003397 if (__lock_set_class(lock, name, key, subclass, ip))
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003398 check_chain_key(current);
3399 current->lockdep_recursion = 0;
3400 raw_local_irq_restore(flags);
3401}
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003402EXPORT_SYMBOL_GPL(lock_set_class);
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003403
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003404/*
3405 * We are not always called with irqs disabled - do that here,
3406 * and also avoid lockdep recursion:
3407 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02003408void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02003409 int trylock, int read, int check,
3410 struct lockdep_map *nest_lock, unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003411{
3412 unsigned long flags;
3413
3414 if (unlikely(current->lockdep_recursion))
3415 return;
3416
3417 raw_local_irq_save(flags);
3418 check_flags(flags);
3419
3420 current->lockdep_recursion = 1;
Frederic Weisbeckerdb2c4c72010-02-02 23:34:40 +01003421 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003422 __lock_acquire(lock, subclass, trylock, read, check,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003423 irqs_disabled_flags(flags), nest_lock, ip, 0);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003424 current->lockdep_recursion = 0;
3425 raw_local_irq_restore(flags);
3426}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003427EXPORT_SYMBOL_GPL(lock_acquire);
3428
Steven Rostedt1d09daa2008-05-12 21:20:55 +02003429void lock_release(struct lockdep_map *lock, int nested,
Steven Rostedt0764d232008-05-12 21:20:44 +02003430 unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003431{
3432 unsigned long flags;
3433
3434 if (unlikely(current->lockdep_recursion))
3435 return;
3436
3437 raw_local_irq_save(flags);
3438 check_flags(flags);
3439 current->lockdep_recursion = 1;
Frederic Weisbecker93135432010-05-08 06:24:25 +02003440 trace_lock_release(lock, ip);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003441 __lock_release(lock, nested, ip);
3442 current->lockdep_recursion = 0;
3443 raw_local_irq_restore(flags);
3444}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003445EXPORT_SYMBOL_GPL(lock_release);
3446
Peter Zijlstraf607c662009-07-20 19:16:29 +02003447int lock_is_held(struct lockdep_map *lock)
3448{
3449 unsigned long flags;
3450 int ret = 0;
3451
3452 if (unlikely(current->lockdep_recursion))
Peter Zijlstraf2513cd2011-06-06 12:32:43 +02003453 return 1; /* avoid false negative lockdep_assert_held() */
Peter Zijlstraf607c662009-07-20 19:16:29 +02003454
3455 raw_local_irq_save(flags);
3456 check_flags(flags);
3457
3458 current->lockdep_recursion = 1;
3459 ret = __lock_is_held(lock);
3460 current->lockdep_recursion = 0;
3461 raw_local_irq_restore(flags);
3462
3463 return ret;
3464}
3465EXPORT_SYMBOL_GPL(lock_is_held);
3466
Nick Piggincf40bd12009-01-21 08:12:39 +01003467void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3468{
3469 current->lockdep_reclaim_gfp = gfp_mask;
3470}
3471
3472void lockdep_clear_current_reclaim_state(void)
3473{
3474 current->lockdep_reclaim_gfp = 0;
3475}
3476
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003477#ifdef CONFIG_LOCK_STAT
3478static int
3479print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3480 unsigned long ip)
3481{
3482 if (!debug_locks_off())
3483 return 0;
3484 if (debug_locks_silent)
3485 return 0;
3486
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07003487 printk("\n");
3488 printk("=================================\n");
3489 printk("[ BUG: bad contention detected! ]\n");
3490 printk("---------------------------------\n");
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003491 printk("%s/%d is trying to contend lock (",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003492 curr->comm, task_pid_nr(curr));
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003493 print_lockdep_cache(lock);
3494 printk(") at:\n");
3495 print_ip_sym(ip);
3496 printk("but there are no locks held!\n");
3497 printk("\nother info that might help us debug this:\n");
3498 lockdep_print_held_locks(curr);
3499
3500 printk("\nstack backtrace:\n");
3501 dump_stack();
3502
3503 return 0;
3504}
3505
3506static void
3507__lock_contended(struct lockdep_map *lock, unsigned long ip)
3508{
3509 struct task_struct *curr = current;
3510 struct held_lock *hlock, *prev_hlock;
3511 struct lock_class_stats *stats;
3512 unsigned int depth;
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003513 int i, contention_point, contending_point;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003514
3515 depth = curr->lockdep_depth;
3516 if (DEBUG_LOCKS_WARN_ON(!depth))
3517 return;
3518
3519 prev_hlock = NULL;
3520 for (i = depth-1; i >= 0; i--) {
3521 hlock = curr->held_locks + i;
3522 /*
3523 * We must not cross into another context:
3524 */
3525 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3526 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003527 if (match_held_lock(hlock, lock))
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003528 goto found_it;
3529 prev_hlock = hlock;
3530 }
3531 print_lock_contention_bug(curr, lock, ip);
3532 return;
3533
3534found_it:
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003535 if (hlock->instance != lock)
3536 return;
3537
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003538 hlock->waittime_stamp = lockstat_clock();
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003539
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003540 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3541 contending_point = lock_point(hlock_class(hlock)->contending_point,
3542 lock->ip);
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003543
Dave Jonesf82b2172008-08-11 09:30:23 +02003544 stats = get_lock_stats(hlock_class(hlock));
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003545 if (contention_point < LOCKSTAT_POINTS)
3546 stats->contention_point[contention_point]++;
3547 if (contending_point < LOCKSTAT_POINTS)
3548 stats->contending_point[contending_point]++;
Peter Zijlstra96645672007-07-19 01:49:00 -07003549 if (lock->cpu != smp_processor_id())
3550 stats->bounces[bounce_contended + !!hlock->read]++;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003551 put_lock_stats(stats);
3552}
3553
3554static void
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003555__lock_acquired(struct lockdep_map *lock, unsigned long ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003556{
3557 struct task_struct *curr = current;
3558 struct held_lock *hlock, *prev_hlock;
3559 struct lock_class_stats *stats;
3560 unsigned int depth;
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003561 u64 now, waittime = 0;
Peter Zijlstra96645672007-07-19 01:49:00 -07003562 int i, cpu;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003563
3564 depth = curr->lockdep_depth;
3565 if (DEBUG_LOCKS_WARN_ON(!depth))
3566 return;
3567
3568 prev_hlock = NULL;
3569 for (i = depth-1; i >= 0; i--) {
3570 hlock = curr->held_locks + i;
3571 /*
3572 * We must not cross into another context:
3573 */
3574 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3575 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003576 if (match_held_lock(hlock, lock))
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003577 goto found_it;
3578 prev_hlock = hlock;
3579 }
3580 print_lock_contention_bug(curr, lock, _RET_IP_);
3581 return;
3582
3583found_it:
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003584 if (hlock->instance != lock)
3585 return;
3586
Peter Zijlstra96645672007-07-19 01:49:00 -07003587 cpu = smp_processor_id();
3588 if (hlock->waittime_stamp) {
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003589 now = lockstat_clock();
Peter Zijlstra96645672007-07-19 01:49:00 -07003590 waittime = now - hlock->waittime_stamp;
3591 hlock->holdtime_stamp = now;
3592 }
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003593
Frederic Weisbecker883a2a32010-05-08 06:16:11 +02003594 trace_lock_acquired(lock, ip);
Frederic Weisbecker20625012009-04-06 01:49:33 +02003595
Dave Jonesf82b2172008-08-11 09:30:23 +02003596 stats = get_lock_stats(hlock_class(hlock));
Peter Zijlstra96645672007-07-19 01:49:00 -07003597 if (waittime) {
3598 if (hlock->read)
3599 lock_time_inc(&stats->read_waittime, waittime);
3600 else
3601 lock_time_inc(&stats->write_waittime, waittime);
3602 }
3603 if (lock->cpu != cpu)
3604 stats->bounces[bounce_acquired + !!hlock->read]++;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003605 put_lock_stats(stats);
Peter Zijlstra96645672007-07-19 01:49:00 -07003606
3607 lock->cpu = cpu;
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003608 lock->ip = ip;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003609}
3610
3611void lock_contended(struct lockdep_map *lock, unsigned long ip)
3612{
3613 unsigned long flags;
3614
3615 if (unlikely(!lock_stat))
3616 return;
3617
3618 if (unlikely(current->lockdep_recursion))
3619 return;
3620
3621 raw_local_irq_save(flags);
3622 check_flags(flags);
3623 current->lockdep_recursion = 1;
Frederic Weisbeckerdb2c4c72010-02-02 23:34:40 +01003624 trace_lock_contended(lock, ip);
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003625 __lock_contended(lock, ip);
3626 current->lockdep_recursion = 0;
3627 raw_local_irq_restore(flags);
3628}
3629EXPORT_SYMBOL_GPL(lock_contended);
3630
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003631void lock_acquired(struct lockdep_map *lock, unsigned long ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003632{
3633 unsigned long flags;
3634
3635 if (unlikely(!lock_stat))
3636 return;
3637
3638 if (unlikely(current->lockdep_recursion))
3639 return;
3640
3641 raw_local_irq_save(flags);
3642 check_flags(flags);
3643 current->lockdep_recursion = 1;
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003644 __lock_acquired(lock, ip);
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003645 current->lockdep_recursion = 0;
3646 raw_local_irq_restore(flags);
3647}
3648EXPORT_SYMBOL_GPL(lock_acquired);
3649#endif
3650
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003651/*
3652 * Used by the testsuite, sanitize the validator state
3653 * after a simulated failure:
3654 */
3655
3656void lockdep_reset(void)
3657{
3658 unsigned long flags;
Ingo Molnar23d95a02006-12-13 00:34:40 -08003659 int i;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003660
3661 raw_local_irq_save(flags);
3662 current->curr_chain_key = 0;
3663 current->lockdep_depth = 0;
3664 current->lockdep_recursion = 0;
3665 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3666 nr_hardirq_chains = 0;
3667 nr_softirq_chains = 0;
3668 nr_process_chains = 0;
3669 debug_locks = 1;
Ingo Molnar23d95a02006-12-13 00:34:40 -08003670 for (i = 0; i < CHAINHASH_SIZE; i++)
3671 INIT_LIST_HEAD(chainhash_table + i);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003672 raw_local_irq_restore(flags);
3673}
3674
3675static void zap_class(struct lock_class *class)
3676{
3677 int i;
3678
3679 /*
3680 * Remove all dependencies this lock is
3681 * involved in:
3682 */
3683 for (i = 0; i < nr_list_entries; i++) {
3684 if (list_entries[i].class == class)
3685 list_del_rcu(&list_entries[i].entry);
3686 }
3687 /*
3688 * Unhash the class and remove it from the all_lock_classes list:
3689 */
3690 list_del_rcu(&class->hash_entry);
3691 list_del_rcu(&class->lock_entry);
3692
Rabin Vincent8bfe0292008-08-11 09:30:26 +02003693 class->key = NULL;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003694}
3695
Arjan van de Venfabe8742008-01-24 07:00:45 +01003696static inline int within(const void *addr, void *start, unsigned long size)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003697{
3698 return addr >= start && addr < start + size;
3699}
3700
3701void lockdep_free_key_range(void *start, unsigned long size)
3702{
3703 struct lock_class *class, *next;
3704 struct list_head *head;
3705 unsigned long flags;
3706 int i;
Nick Piggin5a26db52008-01-16 09:51:58 +01003707 int locked;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003708
3709 raw_local_irq_save(flags);
Nick Piggin5a26db52008-01-16 09:51:58 +01003710 locked = graph_lock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003711
3712 /*
3713 * Unhash all classes that were created by this module:
3714 */
3715 for (i = 0; i < CLASSHASH_SIZE; i++) {
3716 head = classhash_table + i;
3717 if (list_empty(head))
3718 continue;
Arjan van de Venfabe8742008-01-24 07:00:45 +01003719 list_for_each_entry_safe(class, next, head, hash_entry) {
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003720 if (within(class->key, start, size))
3721 zap_class(class);
Arjan van de Venfabe8742008-01-24 07:00:45 +01003722 else if (within(class->name, start, size))
3723 zap_class(class);
3724 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003725 }
3726
Nick Piggin5a26db52008-01-16 09:51:58 +01003727 if (locked)
3728 graph_unlock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003729 raw_local_irq_restore(flags);
3730}
3731
3732void lockdep_reset_lock(struct lockdep_map *lock)
3733{
Ingo Molnard6d897c2006-07-10 04:44:04 -07003734 struct lock_class *class, *next;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003735 struct list_head *head;
3736 unsigned long flags;
3737 int i, j;
Nick Piggin5a26db52008-01-16 09:51:58 +01003738 int locked;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003739
3740 raw_local_irq_save(flags);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003741
3742 /*
Ingo Molnard6d897c2006-07-10 04:44:04 -07003743 * Remove all classes this lock might have:
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003744 */
Ingo Molnard6d897c2006-07-10 04:44:04 -07003745 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3746 /*
3747 * If the class exists we look it up and zap it:
3748 */
3749 class = look_up_lock_class(lock, j);
3750 if (class)
3751 zap_class(class);
3752 }
3753 /*
3754 * Debug check: in the end all mapped classes should
3755 * be gone.
3756 */
Nick Piggin5a26db52008-01-16 09:51:58 +01003757 locked = graph_lock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003758 for (i = 0; i < CLASSHASH_SIZE; i++) {
3759 head = classhash_table + i;
3760 if (list_empty(head))
3761 continue;
3762 list_for_each_entry_safe(class, next, head, hash_entry) {
Hitoshi Mitake62016252010-10-05 18:01:51 +09003763 int match = 0;
3764
3765 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3766 match |= class == lock->class_cache[j];
3767
3768 if (unlikely(match)) {
Ingo Molnar74c383f2006-12-13 00:34:43 -08003769 if (debug_locks_off_graph_unlock())
3770 WARN_ON(1);
Ingo Molnard6d897c2006-07-10 04:44:04 -07003771 goto out_restore;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003772 }
3773 }
3774 }
Nick Piggin5a26db52008-01-16 09:51:58 +01003775 if (locked)
3776 graph_unlock();
Ingo Molnard6d897c2006-07-10 04:44:04 -07003777
3778out_restore:
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003779 raw_local_irq_restore(flags);
3780}
3781
Sam Ravnborg14999932007-02-28 20:12:31 -08003782void lockdep_init(void)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003783{
3784 int i;
3785
3786 /*
3787 * Some architectures have their own start_kernel()
3788 * code which calls lockdep_init(), while we also
3789 * call lockdep_init() from the start_kernel() itself,
3790 * and we want to initialize the hashes only once:
3791 */
3792 if (lockdep_initialized)
3793 return;
3794
3795 for (i = 0; i < CLASSHASH_SIZE; i++)
3796 INIT_LIST_HEAD(classhash_table + i);
3797
3798 for (i = 0; i < CHAINHASH_SIZE; i++)
3799 INIT_LIST_HEAD(chainhash_table + i);
3800
3801 lockdep_initialized = 1;
3802}
3803
3804void __init lockdep_info(void)
3805{
3806 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3807
Li Zefanb0788ca2008-11-21 15:57:32 +08003808 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003809 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3810 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
Li Zefanb0788ca2008-11-21 15:57:32 +08003811 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003812 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3813 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3814 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3815
3816 printk(" memory used by lock dependency info: %lu kB\n",
3817 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3818 sizeof(struct list_head) * CLASSHASH_SIZE +
3819 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3820 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
Ming Lei90629202009-08-02 21:43:36 +08003821 sizeof(struct list_head) * CHAINHASH_SIZE
Ming Lei4dd861d2009-07-16 15:44:29 +02003822#ifdef CONFIG_PROVE_LOCKING
Ming Leie351b662009-07-22 22:48:09 +08003823 + sizeof(struct circular_queue)
Ming Lei4dd861d2009-07-16 15:44:29 +02003824#endif
Ming Lei90629202009-08-02 21:43:36 +08003825 ) / 1024
Ming Lei4dd861d2009-07-16 15:44:29 +02003826 );
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003827
3828 printk(" per task-struct memory footprint: %lu bytes\n",
3829 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3830
3831#ifdef CONFIG_DEBUG_LOCKDEP
Johannes Bergc71063c2007-07-19 01:49:02 -07003832 if (lockdep_init_error) {
3833 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3834 printk("Call stack leading to lockdep invocation was:\n");
3835 print_stack_trace(&lockdep_init_trace, 0);
3836 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003837#endif
3838}
3839
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003840static void
3841print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
Arjan van de Ven55794a42006-07-10 04:44:03 -07003842 const void *mem_to, struct held_lock *hlock)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003843{
3844 if (!debug_locks_off())
3845 return;
3846 if (debug_locks_silent)
3847 return;
3848
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07003849 printk("\n");
3850 printk("=========================\n");
3851 printk("[ BUG: held lock freed! ]\n");
3852 printk("-------------------------\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003853 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003854 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
Arjan van de Ven55794a42006-07-10 04:44:03 -07003855 print_lock(hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003856 lockdep_print_held_locks(curr);
3857
3858 printk("\nstack backtrace:\n");
3859 dump_stack();
3860}
3861
Oleg Nesterov54561782007-12-05 15:46:09 +01003862static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3863 const void* lock_from, unsigned long lock_len)
3864{
3865 return lock_from + lock_len <= mem_from ||
3866 mem_from + mem_len <= lock_from;
3867}
3868
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003869/*
3870 * Called when kernel memory is freed (or unmapped), or if a lock
3871 * is destroyed or reinitialized - this code checks whether there is
3872 * any held lock in the memory range of <from> to <to>:
3873 */
3874void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3875{
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003876 struct task_struct *curr = current;
3877 struct held_lock *hlock;
3878 unsigned long flags;
3879 int i;
3880
3881 if (unlikely(!debug_locks))
3882 return;
3883
3884 local_irq_save(flags);
3885 for (i = 0; i < curr->lockdep_depth; i++) {
3886 hlock = curr->held_locks + i;
3887
Oleg Nesterov54561782007-12-05 15:46:09 +01003888 if (not_in_range(mem_from, mem_len, hlock->instance,
3889 sizeof(*hlock->instance)))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003890 continue;
3891
Oleg Nesterov54561782007-12-05 15:46:09 +01003892 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003893 break;
3894 }
3895 local_irq_restore(flags);
3896}
Peter Zijlstraed075362006-12-06 20:35:24 -08003897EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003898
3899static void print_held_locks_bug(struct task_struct *curr)
3900{
3901 if (!debug_locks_off())
3902 return;
3903 if (debug_locks_silent)
3904 return;
3905
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07003906 printk("\n");
3907 printk("=====================================\n");
3908 printk("[ BUG: lock held at task exit time! ]\n");
3909 printk("-------------------------------------\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003910 printk("%s/%d is exiting with locks still held!\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003911 curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003912 lockdep_print_held_locks(curr);
3913
3914 printk("\nstack backtrace:\n");
3915 dump_stack();
3916}
3917
3918void debug_check_no_locks_held(struct task_struct *task)
3919{
3920 if (unlikely(task->lockdep_depth > 0))
3921 print_held_locks_bug(task);
3922}
3923
3924void debug_show_all_locks(void)
3925{
3926 struct task_struct *g, *p;
3927 int count = 10;
3928 int unlock = 1;
3929
Jarek Poplawski9c35dd72007-03-22 00:11:28 -08003930 if (unlikely(!debug_locks)) {
3931 printk("INFO: lockdep is turned off.\n");
3932 return;
3933 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003934 printk("\nShowing all locks held in the system:\n");
3935
3936 /*
3937 * Here we try to get the tasklist_lock as hard as possible,
3938 * if not successful after 2 seconds we ignore it (but keep
3939 * trying). This is to enable a debug printout even if a
3940 * tasklist_lock-holding task deadlocks or crashes.
3941 */
3942retry:
3943 if (!read_trylock(&tasklist_lock)) {
3944 if (count == 10)
3945 printk("hm, tasklist_lock locked, retrying... ");
3946 if (count) {
3947 count--;
3948 printk(" #%d", 10-count);
3949 mdelay(200);
3950 goto retry;
3951 }
3952 printk(" ignoring it.\n");
3953 unlock = 0;
qinghuang feng46fec7a2008-10-28 17:24:28 +08003954 } else {
3955 if (count != 10)
3956 printk(KERN_CONT " locked it.\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003957 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003958
3959 do_each_thread(g, p) {
Ingo Molnar85684872007-12-05 15:46:09 +01003960 /*
3961 * It's not reliable to print a task's held locks
3962 * if it's not sleeping (or if it's not the current
3963 * task):
3964 */
3965 if (p->state == TASK_RUNNING && p != current)
3966 continue;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003967 if (p->lockdep_depth)
3968 lockdep_print_held_locks(p);
3969 if (!unlock)
3970 if (read_trylock(&tasklist_lock))
3971 unlock = 1;
3972 } while_each_thread(g, p);
3973
3974 printk("\n");
3975 printk("=============================================\n\n");
3976
3977 if (unlock)
3978 read_unlock(&tasklist_lock);
3979}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003980EXPORT_SYMBOL_GPL(debug_show_all_locks);
3981
Ingo Molnar82a1fcb2008-01-25 21:08:02 +01003982/*
3983 * Careful: only use this function if you are sure that
3984 * the task cannot run in parallel!
3985 */
John Kacurf1b499f2010-08-05 17:10:53 +02003986void debug_show_held_locks(struct task_struct *task)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003987{
Jarek Poplawski9c35dd72007-03-22 00:11:28 -08003988 if (unlikely(!debug_locks)) {
3989 printk("INFO: lockdep is turned off.\n");
3990 return;
3991 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003992 lockdep_print_held_locks(task);
3993}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003994EXPORT_SYMBOL_GPL(debug_show_held_locks);
Peter Zijlstrab351d162007-10-11 22:11:12 +02003995
3996void lockdep_sys_exit(void)
3997{
3998 struct task_struct *curr = current;
3999
4000 if (unlikely(curr->lockdep_depth)) {
4001 if (!debug_locks_off())
4002 return;
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004003 printk("\n");
4004 printk("================================================\n");
4005 printk("[ BUG: lock held when returning to user space! ]\n");
4006 printk("------------------------------------------------\n");
Peter Zijlstrab351d162007-10-11 22:11:12 +02004007 printk("%s/%d is leaving the kernel with locks still held!\n",
4008 curr->comm, curr->pid);
4009 lockdep_print_held_locks(curr);
4010 }
4011}
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004012
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004013void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004014{
4015 struct task_struct *curr = current;
4016
Lai Jiangshan2b3fc352010-04-20 16:23:07 +08004017#ifndef CONFIG_PROVE_RCU_REPEATEDLY
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004018 if (!debug_locks_off())
4019 return;
Lai Jiangshan2b3fc352010-04-20 16:23:07 +08004020#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4021 /* Note: the following can be executed concurrently, so be careful. */
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004022 printk("\n");
4023 printk("===============================\n");
4024 printk("[ INFO: suspicious RCU usage. ]\n");
4025 printk("-------------------------------\n");
4026 printk("%s:%d %s!\n", file, line, s);
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004027 printk("\nother info that might help us debug this:\n\n");
Paul E. McKenneycc5b83a2010-03-03 07:46:59 -08004028 printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004029 lockdep_print_held_locks(curr);
4030 printk("\nstack backtrace:\n");
4031 dump_stack();
4032}
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004033EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);