blob: e69434b070da3f922909ece9417627e11234dcd6 [file] [log] [blame]
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001/*
2 * kernel/lockdep.c
3 *
4 * Runtime locking correctness validator
5 *
6 * Started by Ingo Molnar:
7 *
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{
Peter Zijlstra0119fee2011-09-02 01:30:29 +020099 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
100 /*
101 * The lockdep graph lock isn't locked while we expect it to
102 * be, we're confused now, bye!
103 */
Jarek Poplawski381a2292007-02-10 01:44:58 -0800104 return DEBUG_LOCKS_WARN_ON(1);
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200105 }
Jarek Poplawski381a2292007-02-10 01:44:58 -0800106
Steven Rostedtbb065af2008-05-12 21:21:00 +0200107 current->lockdep_recursion--;
Thomas Gleixner0199c4e2009-12-02 20:01:25 +0100108 arch_spin_unlock(&lockdep_lock);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800109 return 0;
110}
111
112/*
113 * Turn lock debugging off and return with 0 if it was off already,
114 * and also release the graph lock:
115 */
116static inline int debug_locks_off_graph_unlock(void)
117{
118 int ret = debug_locks_off();
119
Thomas Gleixner0199c4e2009-12-02 20:01:25 +0100120 arch_spin_unlock(&lockdep_lock);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800121
122 return ret;
123}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700124
125static int lockdep_initialized;
126
127unsigned long nr_list_entries;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200128static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700129
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700130/*
131 * All data structures here are protected by the global debug_lock.
132 *
133 * Mutex key structs only get allocated, once during bootup, and never
134 * get freed - this significantly simplifies the debugging code.
135 */
136unsigned long nr_lock_classes;
137static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
138
Dave Jonesf82b2172008-08-11 09:30:23 +0200139static inline struct lock_class *hlock_class(struct held_lock *hlock)
140{
141 if (!hlock->class_idx) {
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200142 /*
143 * Someone passed in garbage, we give up.
144 */
Dave Jonesf82b2172008-08-11 09:30:23 +0200145 DEBUG_LOCKS_WARN_ON(1);
146 return NULL;
147 }
148 return lock_classes + hlock->class_idx - 1;
149}
150
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700151#ifdef CONFIG_LOCK_STAT
Tejun Heo1871e522009-10-29 22:34:13 +0900152static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
153 cpu_lock_stats);
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700154
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200155static inline u64 lockstat_clock(void)
156{
Peter Zijlstrac6763292010-05-25 10:48:51 +0200157 return local_clock();
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200158}
159
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200160static int lock_point(unsigned long points[], unsigned long ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700161{
162 int i;
163
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200164 for (i = 0; i < LOCKSTAT_POINTS; i++) {
165 if (points[i] == 0) {
166 points[i] = ip;
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700167 break;
168 }
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200169 if (points[i] == ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700170 break;
171 }
172
173 return i;
174}
175
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200176static void lock_time_inc(struct lock_time *lt, u64 time)
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700177{
178 if (time > lt->max)
179 lt->max = time;
180
Frank Rowand109d71c2009-11-19 13:42:06 -0800181 if (time < lt->min || !lt->nr)
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700182 lt->min = time;
183
184 lt->total += time;
185 lt->nr++;
186}
187
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700188static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
189{
Frank Rowand109d71c2009-11-19 13:42:06 -0800190 if (!src->nr)
191 return;
192
193 if (src->max > dst->max)
194 dst->max = src->max;
195
196 if (src->min < dst->min || !dst->nr)
197 dst->min = src->min;
198
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700199 dst->total += src->total;
200 dst->nr += src->nr;
201}
202
203struct lock_class_stats lock_stats(struct lock_class *class)
204{
205 struct lock_class_stats stats;
206 int cpu, i;
207
208 memset(&stats, 0, sizeof(struct lock_class_stats));
209 for_each_possible_cpu(cpu) {
210 struct lock_class_stats *pcs =
Tejun Heo1871e522009-10-29 22:34:13 +0900211 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700212
213 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
214 stats.contention_point[i] += pcs->contention_point[i];
215
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200216 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
217 stats.contending_point[i] += pcs->contending_point[i];
218
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700219 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
220 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
221
222 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
223 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
Peter Zijlstra96645672007-07-19 01:49:00 -0700224
225 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
226 stats.bounces[i] += pcs->bounces[i];
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700227 }
228
229 return stats;
230}
231
232void clear_lock_stats(struct lock_class *class)
233{
234 int cpu;
235
236 for_each_possible_cpu(cpu) {
237 struct lock_class_stats *cpu_stats =
Tejun Heo1871e522009-10-29 22:34:13 +0900238 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700239
240 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
241 }
242 memset(class->contention_point, 0, sizeof(class->contention_point));
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200243 memset(class->contending_point, 0, sizeof(class->contending_point));
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700244}
245
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700246static struct lock_class_stats *get_lock_stats(struct lock_class *class)
247{
Tejun Heo1871e522009-10-29 22:34:13 +0900248 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700249}
250
251static void put_lock_stats(struct lock_class_stats *stats)
252{
Tejun Heo1871e522009-10-29 22:34:13 +0900253 put_cpu_var(cpu_lock_stats);
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700254}
255
256static void lock_release_holdtime(struct held_lock *hlock)
257{
258 struct lock_class_stats *stats;
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200259 u64 holdtime;
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700260
261 if (!lock_stat)
262 return;
263
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200264 holdtime = lockstat_clock() - hlock->holdtime_stamp;
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700265
Dave Jonesf82b2172008-08-11 09:30:23 +0200266 stats = get_lock_stats(hlock_class(hlock));
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700267 if (hlock->read)
268 lock_time_inc(&stats->read_holdtime, holdtime);
269 else
270 lock_time_inc(&stats->write_holdtime, holdtime);
271 put_lock_stats(stats);
272}
273#else
274static inline void lock_release_holdtime(struct held_lock *hlock)
275{
276}
277#endif
278
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700279/*
280 * We keep a global list of all lock classes. The list only grows,
281 * never shrinks. The list is only accessed with the lockdep
282 * spinlock lock held.
283 */
284LIST_HEAD(all_lock_classes);
285
286/*
287 * The lockdep classes are in a hash-table as well, for fast lookup:
288 */
289#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
290#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700291#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700292#define classhashentry(key) (classhash_table + __classhashfn((key)))
293
294static struct list_head classhash_table[CLASSHASH_SIZE];
295
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700296/*
297 * We put the lock dependency chains into a hash-table as well, to cache
298 * their existence:
299 */
300#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
301#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700302#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700303#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
304
305static struct list_head chainhash_table[CHAINHASH_SIZE];
306
307/*
308 * The hash key of the lock dependency chains is a hash itself too:
309 * it's a hash of all locks taken up to that lock, including that lock.
310 * It's a 64-bit hash, because it's important for the keys to be
311 * unique.
312 */
313#define iterate_chain_key(key1, key2) \
Ingo Molnar03cbc352006-09-29 02:01:46 -0700314 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
315 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700316 (key2))
317
Steven Rostedt1d09daa2008-05-12 21:20:55 +0200318void lockdep_off(void)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700319{
320 current->lockdep_recursion++;
321}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700322EXPORT_SYMBOL(lockdep_off);
323
Steven Rostedt1d09daa2008-05-12 21:20:55 +0200324void lockdep_on(void)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700325{
326 current->lockdep_recursion--;
327}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700328EXPORT_SYMBOL(lockdep_on);
329
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700330/*
331 * Debugging switches:
332 */
333
334#define VERBOSE 0
Ingo Molnar33e94e92006-12-13 00:34:41 -0800335#define VERY_VERBOSE 0
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700336
337#if VERBOSE
338# define HARDIRQ_VERBOSE 1
339# define SOFTIRQ_VERBOSE 1
Nick Piggincf40bd12009-01-21 08:12:39 +0100340# define RECLAIM_VERBOSE 1
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700341#else
342# define HARDIRQ_VERBOSE 0
343# define SOFTIRQ_VERBOSE 0
Nick Piggincf40bd12009-01-21 08:12:39 +0100344# define RECLAIM_VERBOSE 0
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700345#endif
346
Nick Piggincf40bd12009-01-21 08:12:39 +0100347#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700348/*
349 * Quick filtering for interesting events:
350 */
351static int class_filter(struct lock_class *class)
352{
Andi Kleenf9829cc2006-07-10 04:44:01 -0700353#if 0
354 /* Example */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700355 if (class->name_version == 1 &&
Andi Kleenf9829cc2006-07-10 04:44:01 -0700356 !strcmp(class->name, "lockname"))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700357 return 1;
358 if (class->name_version == 1 &&
Andi Kleenf9829cc2006-07-10 04:44:01 -0700359 !strcmp(class->name, "&struct->lockfield"))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700360 return 1;
Andi Kleenf9829cc2006-07-10 04:44:01 -0700361#endif
Ingo Molnara6640892006-12-13 00:34:39 -0800362 /* Filter everything else. 1 would be to allow everything else */
363 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700364}
365#endif
366
367static int verbose(struct lock_class *class)
368{
369#if VERBOSE
370 return class_filter(class);
371#endif
372 return 0;
373}
374
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700375/*
376 * Stack-trace: tightly packed array of stack backtrace
Ingo Molnar74c383f2006-12-13 00:34:43 -0800377 * addresses. Protected by the graph_lock.
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700378 */
379unsigned long nr_stack_trace_entries;
380static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
381
382static int save_trace(struct stack_trace *trace)
383{
384 trace->nr_entries = 0;
385 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
386 trace->entries = stack_trace + nr_stack_trace_entries;
387
Andi Kleen5a1b3992006-09-26 10:52:34 +0200388 trace->skip = 3;
Andi Kleen5a1b3992006-09-26 10:52:34 +0200389
Christoph Hellwigab1b6f02007-05-08 00:23:29 -0700390 save_stack_trace(trace);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700391
Peter Zijlstra4f84f432009-07-20 15:27:04 +0200392 /*
393 * Some daft arches put -1 at the end to indicate its a full trace.
394 *
395 * <rant> this is buggy anyway, since it takes a whole extra entry so a
396 * complete trace that maxes out the entries provided will be reported
397 * as incomplete, friggin useless </rant>
398 */
Luck, Tonyea5b41f2009-12-09 14:29:36 -0800399 if (trace->nr_entries != 0 &&
400 trace->entries[trace->nr_entries-1] == ULONG_MAX)
Peter Zijlstra4f84f432009-07-20 15:27:04 +0200401 trace->nr_entries--;
402
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700403 trace->max_entries = trace->nr_entries;
404
405 nr_stack_trace_entries += trace->nr_entries;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700406
Peter Zijlstra4f84f432009-07-20 15:27:04 +0200407 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
Ingo Molnar74c383f2006-12-13 00:34:43 -0800408 if (!debug_locks_off_graph_unlock())
409 return 0;
410
411 printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
412 printk("turning off the locking correctness validator.\n");
413 dump_stack();
414
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700415 return 0;
416 }
417
418 return 1;
419}
420
421unsigned int nr_hardirq_chains;
422unsigned int nr_softirq_chains;
423unsigned int nr_process_chains;
424unsigned int max_lockdep_depth;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700425
426#ifdef CONFIG_DEBUG_LOCKDEP
427/*
428 * We cannot printk in early bootup code. Not even early_printk()
429 * might work. So we mark any initialization errors and printk
430 * about it later on, in lockdep_info().
431 */
432static int lockdep_init_error;
Johannes Bergc71063c2007-07-19 01:49:02 -0700433static unsigned long lockdep_init_trace_data[20];
434static struct stack_trace lockdep_init_trace = {
435 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
436 .entries = lockdep_init_trace_data,
437};
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700438
439/*
440 * Various lockdep statistics:
441 */
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +0200442DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700443#endif
444
445/*
446 * Locking printouts:
447 */
448
Peter Zijlstrafabe9c42009-01-22 14:51:01 +0100449#define __USAGE(__STATE) \
Peter Zijlstrab4b136f2009-01-29 14:50:36 +0100450 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
451 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
452 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
453 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
Peter Zijlstrafabe9c42009-01-22 14:51:01 +0100454
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700455static const char *usage_str[] =
456{
Peter Zijlstrafabe9c42009-01-22 14:51:01 +0100457#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
458#include "lockdep_states.h"
459#undef LOCKDEP_STATE
460 [LOCK_USED] = "INITIAL USE",
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700461};
462
463const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
464{
Alexey Dobriyanffb45122007-05-08 00:28:41 -0700465 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700466}
467
Peter Zijlstra3ff176c2009-01-22 17:40:42 +0100468static inline unsigned long lock_flag(enum lock_usage_bit bit)
469{
470 return 1UL << bit;
471}
472
473static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
474{
475 char c = '.';
476
477 if (class->usage_mask & lock_flag(bit + 2))
478 c = '+';
479 if (class->usage_mask & lock_flag(bit)) {
480 c = '-';
481 if (class->usage_mask & lock_flag(bit + 2))
482 c = '?';
483 }
484
485 return c;
486}
487
Peter Zijlstraf510b232009-01-22 17:53:47 +0100488void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700489{
Peter Zijlstraf510b232009-01-22 17:53:47 +0100490 int i = 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700491
Peter Zijlstraf510b232009-01-22 17:53:47 +0100492#define LOCKDEP_STATE(__STATE) \
493 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
494 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
495#include "lockdep_states.h"
496#undef LOCKDEP_STATE
497
498 usage[i] = '\0';
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700499}
500
Steven Rostedt3003eba2011-04-20 21:41:54 -0400501static int __print_lock_name(struct lock_class *class)
502{
503 char str[KSYM_NAME_LEN];
504 const char *name;
505
506 name = class->name;
507 if (!name)
508 name = __get_key_name(class->key, str);
509
510 return printk("%s", name);
511}
512
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700513static void print_lock_name(struct lock_class *class)
514{
Peter Zijlstraf510b232009-01-22 17:53:47 +0100515 char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700516 const char *name;
517
Peter Zijlstraf510b232009-01-22 17:53:47 +0100518 get_usage_chars(class, usage);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700519
520 name = class->name;
521 if (!name) {
522 name = __get_key_name(class->key, str);
523 printk(" (%s", name);
524 } else {
525 printk(" (%s", name);
526 if (class->name_version > 1)
527 printk("#%d", class->name_version);
528 if (class->subclass)
529 printk("/%d", class->subclass);
530 }
Peter Zijlstraf510b232009-01-22 17:53:47 +0100531 printk("){%s}", usage);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700532}
533
534static void print_lockdep_cache(struct lockdep_map *lock)
535{
536 const char *name;
Tejun Heo9281ace2007-07-17 04:03:51 -0700537 char str[KSYM_NAME_LEN];
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700538
539 name = lock->name;
540 if (!name)
541 name = __get_key_name(lock->key->subkeys, str);
542
543 printk("%s", name);
544}
545
546static void print_lock(struct held_lock *hlock)
547{
Dave Jonesf82b2172008-08-11 09:30:23 +0200548 print_lock_name(hlock_class(hlock));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700549 printk(", at: ");
550 print_ip_sym(hlock->acquire_ip);
551}
552
553static void lockdep_print_held_locks(struct task_struct *curr)
554{
555 int i, depth = curr->lockdep_depth;
556
557 if (!depth) {
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700558 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700559 return;
560 }
561 printk("%d lock%s held by %s/%d:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700562 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700563
564 for (i = 0; i < depth; i++) {
565 printk(" #%d: ", i);
566 print_lock(curr->held_locks + i);
567 }
568}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700569
Dave Jones99de0552006-09-29 02:00:10 -0700570static void print_kernel_version(void)
571{
Serge E. Hallyn96b644b2006-10-02 02:18:13 -0700572 printk("%s %.*s\n", init_utsname()->release,
573 (int)strcspn(init_utsname()->version, " "),
574 init_utsname()->version);
Dave Jones99de0552006-09-29 02:00:10 -0700575}
576
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700577static int very_verbose(struct lock_class *class)
578{
579#if VERY_VERBOSE
580 return class_filter(class);
581#endif
582 return 0;
583}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700584
585/*
586 * Is this the address of a static object:
587 */
588static int static_obj(void *obj)
589{
590 unsigned long start = (unsigned long) &_stext,
591 end = (unsigned long) &_end,
592 addr = (unsigned long) obj;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700593
594 /*
595 * static variable?
596 */
597 if ((addr >= start) && (addr < end))
598 return 1;
599
Mike Frysinger2a9ad182009-09-22 16:44:16 -0700600 if (arch_is_kernel_data(addr))
601 return 1;
602
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700603 /*
Tejun Heo10fad5e2010-03-10 18:57:54 +0900604 * in-kernel percpu var?
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700605 */
Tejun Heo10fad5e2010-03-10 18:57:54 +0900606 if (is_kernel_percpu_address(addr))
607 return 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700608
609 /*
Tejun Heo10fad5e2010-03-10 18:57:54 +0900610 * module static or percpu var?
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700611 */
Tejun Heo10fad5e2010-03-10 18:57:54 +0900612 return is_module_address(addr) || is_module_percpu_address(addr);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700613}
614
615/*
616 * To make lock name printouts unique, we calculate a unique
617 * class->name_version generation counter:
618 */
619static int count_matching_names(struct lock_class *new_class)
620{
621 struct lock_class *class;
622 int count = 0;
623
624 if (!new_class->name)
625 return 0;
626
627 list_for_each_entry(class, &all_lock_classes, lock_entry) {
628 if (new_class->key - new_class->subclass == class->key)
629 return class->name_version;
630 if (class->name && !strcmp(class->name, new_class->name))
631 count = max(count, class->name_version);
632 }
633
634 return count + 1;
635}
636
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700637/*
638 * Register a lock's class in the hash-table, if the class is not present
639 * yet. Otherwise we look it up. We cache the result in the lock object
640 * itself, so actual lookup of the hash should be once per lock object.
641 */
642static inline struct lock_class *
Ingo Molnard6d897c2006-07-10 04:44:04 -0700643look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700644{
645 struct lockdep_subclass_key *key;
646 struct list_head *hash_head;
647 struct lock_class *class;
648
649#ifdef CONFIG_DEBUG_LOCKDEP
650 /*
651 * If the architecture calls into lockdep before initializing
652 * the hashes then we'll warn about it later. (we cannot printk
653 * right now)
654 */
655 if (unlikely(!lockdep_initialized)) {
656 lockdep_init();
657 lockdep_init_error = 1;
Johannes Bergc71063c2007-07-19 01:49:02 -0700658 save_stack_trace(&lockdep_init_trace);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700659 }
660#endif
661
Hitoshi Mitake4ba053c2010-10-13 17:30:26 +0900662 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
663 debug_locks_off();
664 printk(KERN_ERR
665 "BUG: looking up invalid subclass: %u\n", subclass);
666 printk(KERN_ERR
667 "turning off the locking correctness validator.\n");
668 dump_stack();
669 return NULL;
670 }
671
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700672 /*
673 * Static locks do not have their class-keys yet - for them the key
674 * is the lock object itself:
675 */
676 if (unlikely(!lock->key))
677 lock->key = (void *)lock;
678
679 /*
680 * NOTE: the class-key must be unique. For dynamic locks, a static
681 * lock_class_key variable is passed in through the mutex_init()
682 * (or spin_lock_init()) call - which acts as the key. For static
683 * locks we use the lock object itself as the key.
684 */
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700685 BUILD_BUG_ON(sizeof(struct lock_class_key) >
686 sizeof(struct lockdep_map));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700687
688 key = lock->key->subkeys + subclass;
689
690 hash_head = classhashentry(key);
691
692 /*
693 * We can walk the hash lockfree, because the hash only
694 * grows, and we are careful when adding entries to the end:
695 */
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700696 list_for_each_entry(class, hash_head, hash_entry) {
697 if (class->key == key) {
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200698 /*
699 * Huh! same key, different name? Did someone trample
700 * on some memory? We're most confused.
701 */
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700702 WARN_ON_ONCE(class->name != lock->name);
Ingo Molnard6d897c2006-07-10 04:44:04 -0700703 return class;
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700704 }
705 }
Ingo Molnard6d897c2006-07-10 04:44:04 -0700706
707 return NULL;
708}
709
710/*
711 * Register a lock's class in the hash-table, if the class is not present
712 * yet. Otherwise we look it up. We cache the result in the lock object
713 * itself, so actual lookup of the hash should be once per lock object.
714 */
715static inline struct lock_class *
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -0400716register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
Ingo Molnard6d897c2006-07-10 04:44:04 -0700717{
718 struct lockdep_subclass_key *key;
719 struct list_head *hash_head;
720 struct lock_class *class;
Ingo Molnar70e45062006-12-06 20:40:50 -0800721 unsigned long flags;
Ingo Molnard6d897c2006-07-10 04:44:04 -0700722
723 class = look_up_lock_class(lock, subclass);
724 if (likely(class))
725 return class;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700726
727 /*
728 * Debug-check: all keys must be persistent!
729 */
730 if (!static_obj(lock->key)) {
731 debug_locks_off();
732 printk("INFO: trying to register non-static key.\n");
733 printk("the code is fine but needs lockdep annotation.\n");
734 printk("turning off the locking correctness validator.\n");
735 dump_stack();
736
737 return NULL;
738 }
739
Ingo Molnard6d897c2006-07-10 04:44:04 -0700740 key = lock->key->subkeys + subclass;
741 hash_head = classhashentry(key);
742
Ingo Molnar70e45062006-12-06 20:40:50 -0800743 raw_local_irq_save(flags);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800744 if (!graph_lock()) {
745 raw_local_irq_restore(flags);
746 return NULL;
747 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700748 /*
749 * We have to do the hash-walk again, to avoid races
750 * with another CPU:
751 */
752 list_for_each_entry(class, hash_head, hash_entry)
753 if (class->key == key)
754 goto out_unlock_set;
755 /*
756 * Allocate a new key from the static array, and add it to
757 * the hash:
758 */
759 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
Ingo Molnar74c383f2006-12-13 00:34:43 -0800760 if (!debug_locks_off_graph_unlock()) {
761 raw_local_irq_restore(flags);
762 return NULL;
763 }
Ingo Molnar70e45062006-12-06 20:40:50 -0800764 raw_local_irq_restore(flags);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800765
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700766 printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
767 printk("turning off the locking correctness validator.\n");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +0100768 dump_stack();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700769 return NULL;
770 }
771 class = lock_classes + nr_lock_classes++;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +0200772 debug_atomic_inc(nr_unused_locks);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700773 class->key = key;
774 class->name = lock->name;
775 class->subclass = subclass;
776 INIT_LIST_HEAD(&class->lock_entry);
777 INIT_LIST_HEAD(&class->locks_before);
778 INIT_LIST_HEAD(&class->locks_after);
779 class->name_version = count_matching_names(class);
780 /*
781 * We use RCU's safe list-add method to make
782 * parallel walking of the hash-list safe:
783 */
784 list_add_tail_rcu(&class->hash_entry, hash_head);
Dale Farnsworth14811972008-02-25 23:03:02 +0100785 /*
786 * Add it to the global list of classes:
787 */
788 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700789
790 if (verbose(class)) {
Ingo Molnar74c383f2006-12-13 00:34:43 -0800791 graph_unlock();
Ingo Molnar70e45062006-12-06 20:40:50 -0800792 raw_local_irq_restore(flags);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800793
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700794 printk("\nnew class %p: %s", class->key, class->name);
795 if (class->name_version > 1)
796 printk("#%d", class->name_version);
797 printk("\n");
798 dump_stack();
Ingo Molnar74c383f2006-12-13 00:34:43 -0800799
Ingo Molnar70e45062006-12-06 20:40:50 -0800800 raw_local_irq_save(flags);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800801 if (!graph_lock()) {
802 raw_local_irq_restore(flags);
803 return NULL;
804 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700805 }
806out_unlock_set:
Ingo Molnar74c383f2006-12-13 00:34:43 -0800807 graph_unlock();
Ingo Molnar70e45062006-12-06 20:40:50 -0800808 raw_local_irq_restore(flags);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700809
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -0400810 if (!subclass || force)
Hitoshi Mitake62016252010-10-05 18:01:51 +0900811 lock->class_cache[0] = class;
812 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
813 lock->class_cache[subclass] = class;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700814
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200815 /*
816 * Hash collision, did we smoke some? We found a class with a matching
817 * hash but the subclass -- which is hashed in -- didn't match.
818 */
Jarek Poplawski381a2292007-02-10 01:44:58 -0800819 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
820 return NULL;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700821
822 return class;
823}
824
Peter Zijlstraca58abc2007-07-19 01:48:53 -0700825#ifdef CONFIG_PROVE_LOCKING
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700826/*
Peter Zijlstra8e182572007-07-19 01:48:54 -0700827 * Allocate a lockdep entry. (assumes the graph_lock held, returns
828 * with NULL on failure)
829 */
830static struct lock_list *alloc_list_entry(void)
831{
832 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
833 if (!debug_locks_off_graph_unlock())
834 return NULL;
835
836 printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
837 printk("turning off the locking correctness validator.\n");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +0100838 dump_stack();
Peter Zijlstra8e182572007-07-19 01:48:54 -0700839 return NULL;
840 }
841 return list_entries + nr_list_entries++;
842}
843
844/*
845 * Add a new dependency to the head of the list:
846 */
847static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
Yong Zhang4726f2a2010-05-04 14:16:48 +0800848 struct list_head *head, unsigned long ip,
849 int distance, struct stack_trace *trace)
Peter Zijlstra8e182572007-07-19 01:48:54 -0700850{
851 struct lock_list *entry;
852 /*
853 * Lock not present yet - get a new dependency struct and
854 * add it to the list:
855 */
856 entry = alloc_list_entry();
857 if (!entry)
858 return 0;
859
Zhu Yi74870172008-08-27 14:33:00 +0800860 entry->class = this;
861 entry->distance = distance;
Yong Zhang4726f2a2010-05-04 14:16:48 +0800862 entry->trace = *trace;
Peter Zijlstra8e182572007-07-19 01:48:54 -0700863 /*
864 * Since we never remove from the dependency list, the list can
865 * be walked lockless by other CPUs, it's only allocation
866 * that must be protected by the spinlock. But this also means
867 * we must make new entries visible only once writes to the
868 * entry become visible - hence the RCU op:
869 */
870 list_add_tail_rcu(&entry->entry, head);
871
872 return 1;
873}
874
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200875/*
876 * For good efficiency of modular, we use power of 2
877 */
Peter Zijlstraaf012962009-07-16 15:44:29 +0200878#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
879#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
880
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200881/*
882 * The circular_queue and helpers is used to implement the
Peter Zijlstraaf012962009-07-16 15:44:29 +0200883 * breadth-first search(BFS)algorithem, by which we can build
884 * the shortest path from the next lock to be acquired to the
885 * previous held lock if there is a circular between them.
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200886 */
Peter Zijlstraaf012962009-07-16 15:44:29 +0200887struct circular_queue {
888 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
889 unsigned int front, rear;
890};
891
892static struct circular_queue lock_cq;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200893
Ming Lei12f3dfd2009-07-16 15:44:29 +0200894unsigned int max_bfs_queue_depth;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200895
Ming Leie351b662009-07-22 22:48:09 +0800896static unsigned int lockdep_dependency_gen_id;
897
Peter Zijlstraaf012962009-07-16 15:44:29 +0200898static inline void __cq_init(struct circular_queue *cq)
899{
900 cq->front = cq->rear = 0;
Ming Leie351b662009-07-22 22:48:09 +0800901 lockdep_dependency_gen_id++;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200902}
903
904static inline int __cq_empty(struct circular_queue *cq)
905{
906 return (cq->front == cq->rear);
907}
908
909static inline int __cq_full(struct circular_queue *cq)
910{
911 return ((cq->rear + 1) & CQ_MASK) == cq->front;
912}
913
914static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
915{
916 if (__cq_full(cq))
917 return -1;
918
919 cq->element[cq->rear] = elem;
920 cq->rear = (cq->rear + 1) & CQ_MASK;
921 return 0;
922}
923
924static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
925{
926 if (__cq_empty(cq))
927 return -1;
928
929 *elem = cq->element[cq->front];
930 cq->front = (cq->front + 1) & CQ_MASK;
931 return 0;
932}
933
934static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
935{
936 return (cq->rear - cq->front) & CQ_MASK;
937}
938
939static inline void mark_lock_accessed(struct lock_list *lock,
940 struct lock_list *parent)
941{
942 unsigned long nr;
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200943
Peter Zijlstraaf012962009-07-16 15:44:29 +0200944 nr = lock - list_entries;
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200945 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
Peter Zijlstraaf012962009-07-16 15:44:29 +0200946 lock->parent = parent;
Ming Leie351b662009-07-22 22:48:09 +0800947 lock->class->dep_gen_id = lockdep_dependency_gen_id;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200948}
949
950static inline unsigned long lock_accessed(struct lock_list *lock)
951{
952 unsigned long nr;
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200953
Peter Zijlstraaf012962009-07-16 15:44:29 +0200954 nr = lock - list_entries;
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200955 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
Ming Leie351b662009-07-22 22:48:09 +0800956 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200957}
958
959static inline struct lock_list *get_lock_parent(struct lock_list *child)
960{
961 return child->parent;
962}
963
964static inline int get_lock_depth(struct lock_list *child)
965{
966 int depth = 0;
967 struct lock_list *parent;
968
969 while ((parent = get_lock_parent(child))) {
970 child = parent;
971 depth++;
972 }
973 return depth;
974}
975
Ming Lei9e2d5512009-07-16 15:44:29 +0200976static int __bfs(struct lock_list *source_entry,
Peter Zijlstraaf012962009-07-16 15:44:29 +0200977 void *data,
978 int (*match)(struct lock_list *entry, void *data),
979 struct lock_list **target_entry,
980 int forward)
Ming Leic94aa5c2009-07-16 15:44:29 +0200981{
982 struct lock_list *entry;
Ming Leid588e462009-07-16 15:44:29 +0200983 struct list_head *head;
Ming Leic94aa5c2009-07-16 15:44:29 +0200984 struct circular_queue *cq = &lock_cq;
985 int ret = 1;
986
Ming Lei9e2d5512009-07-16 15:44:29 +0200987 if (match(source_entry, data)) {
Ming Leic94aa5c2009-07-16 15:44:29 +0200988 *target_entry = source_entry;
989 ret = 0;
990 goto exit;
991 }
992
Ming Leid588e462009-07-16 15:44:29 +0200993 if (forward)
994 head = &source_entry->class->locks_after;
995 else
996 head = &source_entry->class->locks_before;
997
998 if (list_empty(head))
999 goto exit;
1000
1001 __cq_init(cq);
Ming Leic94aa5c2009-07-16 15:44:29 +02001002 __cq_enqueue(cq, (unsigned long)source_entry);
1003
1004 while (!__cq_empty(cq)) {
1005 struct lock_list *lock;
Ming Leic94aa5c2009-07-16 15:44:29 +02001006
1007 __cq_dequeue(cq, (unsigned long *)&lock);
1008
1009 if (!lock->class) {
1010 ret = -2;
1011 goto exit;
1012 }
1013
1014 if (forward)
1015 head = &lock->class->locks_after;
1016 else
1017 head = &lock->class->locks_before;
1018
1019 list_for_each_entry(entry, head, entry) {
1020 if (!lock_accessed(entry)) {
Ming Lei12f3dfd2009-07-16 15:44:29 +02001021 unsigned int cq_depth;
Ming Leic94aa5c2009-07-16 15:44:29 +02001022 mark_lock_accessed(entry, lock);
Ming Lei9e2d5512009-07-16 15:44:29 +02001023 if (match(entry, data)) {
Ming Leic94aa5c2009-07-16 15:44:29 +02001024 *target_entry = entry;
1025 ret = 0;
1026 goto exit;
1027 }
1028
1029 if (__cq_enqueue(cq, (unsigned long)entry)) {
1030 ret = -1;
1031 goto exit;
1032 }
Ming Lei12f3dfd2009-07-16 15:44:29 +02001033 cq_depth = __cq_get_elem_count(cq);
1034 if (max_bfs_queue_depth < cq_depth)
1035 max_bfs_queue_depth = cq_depth;
Ming Leic94aa5c2009-07-16 15:44:29 +02001036 }
1037 }
1038 }
1039exit:
1040 return ret;
1041}
1042
Ming Leid7aaba12009-07-16 15:44:29 +02001043static inline int __bfs_forwards(struct lock_list *src_entry,
Ming Lei9e2d5512009-07-16 15:44:29 +02001044 void *data,
1045 int (*match)(struct lock_list *entry, void *data),
1046 struct lock_list **target_entry)
Ming Leic94aa5c2009-07-16 15:44:29 +02001047{
Ming Lei9e2d5512009-07-16 15:44:29 +02001048 return __bfs(src_entry, data, match, target_entry, 1);
Ming Leic94aa5c2009-07-16 15:44:29 +02001049
1050}
1051
Ming Leid7aaba12009-07-16 15:44:29 +02001052static inline int __bfs_backwards(struct lock_list *src_entry,
Ming Lei9e2d5512009-07-16 15:44:29 +02001053 void *data,
1054 int (*match)(struct lock_list *entry, void *data),
1055 struct lock_list **target_entry)
Ming Leic94aa5c2009-07-16 15:44:29 +02001056{
Ming Lei9e2d5512009-07-16 15:44:29 +02001057 return __bfs(src_entry, data, match, target_entry, 0);
Ming Leic94aa5c2009-07-16 15:44:29 +02001058
1059}
1060
Peter Zijlstra8e182572007-07-19 01:48:54 -07001061/*
1062 * Recursive, forwards-direction lock-dependency checking, used for
1063 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1064 * checking.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001065 */
Peter Zijlstra8e182572007-07-19 01:48:54 -07001066
1067/*
1068 * Print a dependency chain entry (this is only done when a deadlock
1069 * has been detected):
1070 */
1071static noinline int
Ming Lei24208ca2009-07-16 15:44:29 +02001072print_circular_bug_entry(struct lock_list *target, int depth)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001073{
1074 if (debug_locks_silent)
1075 return 0;
1076 printk("\n-> #%u", depth);
1077 print_lock_name(target->class);
1078 printk(":\n");
1079 print_stack_trace(&target->trace, 6);
1080
1081 return 0;
1082}
1083
Steven Rostedtf4185812011-04-20 21:41:55 -04001084static void
1085print_circular_lock_scenario(struct held_lock *src,
1086 struct held_lock *tgt,
1087 struct lock_list *prt)
1088{
1089 struct lock_class *source = hlock_class(src);
1090 struct lock_class *target = hlock_class(tgt);
1091 struct lock_class *parent = prt->class;
1092
1093 /*
1094 * A direct locking problem where unsafe_class lock is taken
1095 * directly by safe_class lock, then all we need to show
1096 * is the deadlock scenario, as it is obvious that the
1097 * unsafe lock is taken under the safe lock.
1098 *
1099 * But if there is a chain instead, where the safe lock takes
1100 * an intermediate lock (middle_class) where this lock is
1101 * not the same as the safe lock, then the lock chain is
1102 * used to describe the problem. Otherwise we would need
1103 * to show a different CPU case for each link in the chain
1104 * from the safe_class lock to the unsafe_class lock.
1105 */
1106 if (parent != source) {
1107 printk("Chain exists of:\n ");
1108 __print_lock_name(source);
1109 printk(" --> ");
1110 __print_lock_name(parent);
1111 printk(" --> ");
1112 __print_lock_name(target);
1113 printk("\n\n");
1114 }
1115
1116 printk(" Possible unsafe locking scenario:\n\n");
1117 printk(" CPU0 CPU1\n");
1118 printk(" ---- ----\n");
1119 printk(" lock(");
1120 __print_lock_name(target);
1121 printk(");\n");
1122 printk(" lock(");
1123 __print_lock_name(parent);
1124 printk(");\n");
1125 printk(" lock(");
1126 __print_lock_name(target);
1127 printk(");\n");
1128 printk(" lock(");
1129 __print_lock_name(source);
1130 printk(");\n");
1131 printk("\n *** DEADLOCK ***\n\n");
1132}
1133
Peter Zijlstra8e182572007-07-19 01:48:54 -07001134/*
1135 * When a circular dependency is detected, print the
1136 * header first:
1137 */
1138static noinline int
Ming Leidb0002a2009-07-16 15:44:29 +02001139print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1140 struct held_lock *check_src,
1141 struct held_lock *check_tgt)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001142{
1143 struct task_struct *curr = current;
1144
Ming Leic94aa5c2009-07-16 15:44:29 +02001145 if (debug_locks_silent)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001146 return 0;
1147
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001148 printk("\n");
1149 printk("======================================================\n");
1150 printk("[ INFO: possible circular locking dependency detected ]\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001151 print_kernel_version();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001152 printk("-------------------------------------------------------\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001153 printk("%s/%d is trying to acquire lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07001154 curr->comm, task_pid_nr(curr));
Ming Leidb0002a2009-07-16 15:44:29 +02001155 print_lock(check_src);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001156 printk("\nbut task is already holding lock:\n");
Ming Leidb0002a2009-07-16 15:44:29 +02001157 print_lock(check_tgt);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001158 printk("\nwhich lock already depends on the new lock.\n\n");
1159 printk("\nthe existing dependency chain (in reverse order) is:\n");
1160
1161 print_circular_bug_entry(entry, depth);
1162
1163 return 0;
1164}
1165
Ming Lei9e2d5512009-07-16 15:44:29 +02001166static inline int class_equal(struct lock_list *entry, void *data)
1167{
1168 return entry->class == data;
1169}
1170
Ming Leidb0002a2009-07-16 15:44:29 +02001171static noinline int print_circular_bug(struct lock_list *this,
1172 struct lock_list *target,
1173 struct held_lock *check_src,
1174 struct held_lock *check_tgt)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001175{
1176 struct task_struct *curr = current;
Ming Leic94aa5c2009-07-16 15:44:29 +02001177 struct lock_list *parent;
Steven Rostedtf4185812011-04-20 21:41:55 -04001178 struct lock_list *first_parent;
Ming Lei24208ca2009-07-16 15:44:29 +02001179 int depth;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001180
Ming Leic94aa5c2009-07-16 15:44:29 +02001181 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001182 return 0;
1183
Ming Leidb0002a2009-07-16 15:44:29 +02001184 if (!save_trace(&this->trace))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001185 return 0;
1186
Ming Leic94aa5c2009-07-16 15:44:29 +02001187 depth = get_lock_depth(target);
1188
Ming Leidb0002a2009-07-16 15:44:29 +02001189 print_circular_bug_header(target, depth, check_src, check_tgt);
Ming Leic94aa5c2009-07-16 15:44:29 +02001190
1191 parent = get_lock_parent(target);
Steven Rostedtf4185812011-04-20 21:41:55 -04001192 first_parent = parent;
Ming Leic94aa5c2009-07-16 15:44:29 +02001193
1194 while (parent) {
1195 print_circular_bug_entry(parent, --depth);
1196 parent = get_lock_parent(parent);
1197 }
Peter Zijlstra8e182572007-07-19 01:48:54 -07001198
1199 printk("\nother info that might help us debug this:\n\n");
Steven Rostedtf4185812011-04-20 21:41:55 -04001200 print_circular_lock_scenario(check_src, check_tgt,
1201 first_parent);
1202
Peter Zijlstra8e182572007-07-19 01:48:54 -07001203 lockdep_print_held_locks(curr);
1204
1205 printk("\nstack backtrace:\n");
1206 dump_stack();
1207
1208 return 0;
1209}
1210
Ming Leidb0002a2009-07-16 15:44:29 +02001211static noinline int print_bfs_bug(int ret)
1212{
1213 if (!debug_locks_off_graph_unlock())
1214 return 0;
1215
Peter Zijlstra0119fee2011-09-02 01:30:29 +02001216 /*
1217 * Breadth-first-search failed, graph got corrupted?
1218 */
Ming Leidb0002a2009-07-16 15:44:29 +02001219 WARN(1, "lockdep bfs error:%d\n", ret);
1220
1221 return 0;
1222}
1223
Ming Leief681022009-07-16 15:44:29 +02001224static int noop_count(struct lock_list *entry, void *data)
David Miller419ca3f2008-07-29 21:45:03 -07001225{
Ming Leief681022009-07-16 15:44:29 +02001226 (*(unsigned long *)data)++;
1227 return 0;
David Miller419ca3f2008-07-29 21:45:03 -07001228}
1229
Ming Leief681022009-07-16 15:44:29 +02001230unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1231{
1232 unsigned long count = 0;
1233 struct lock_list *uninitialized_var(target_entry);
1234
1235 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1236
1237 return count;
1238}
David Miller419ca3f2008-07-29 21:45:03 -07001239unsigned long lockdep_count_forward_deps(struct lock_class *class)
1240{
1241 unsigned long ret, flags;
Ming Leief681022009-07-16 15:44:29 +02001242 struct lock_list this;
1243
1244 this.parent = NULL;
1245 this.class = class;
David Miller419ca3f2008-07-29 21:45:03 -07001246
1247 local_irq_save(flags);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001248 arch_spin_lock(&lockdep_lock);
Ming Leief681022009-07-16 15:44:29 +02001249 ret = __lockdep_count_forward_deps(&this);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001250 arch_spin_unlock(&lockdep_lock);
David Miller419ca3f2008-07-29 21:45:03 -07001251 local_irq_restore(flags);
1252
1253 return ret;
1254}
1255
Ming Leief681022009-07-16 15:44:29 +02001256unsigned long __lockdep_count_backward_deps(struct lock_list *this)
David Miller419ca3f2008-07-29 21:45:03 -07001257{
Ming Leief681022009-07-16 15:44:29 +02001258 unsigned long count = 0;
1259 struct lock_list *uninitialized_var(target_entry);
David Miller419ca3f2008-07-29 21:45:03 -07001260
Ming Leief681022009-07-16 15:44:29 +02001261 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
David Miller419ca3f2008-07-29 21:45:03 -07001262
Ming Leief681022009-07-16 15:44:29 +02001263 return count;
David Miller419ca3f2008-07-29 21:45:03 -07001264}
1265
1266unsigned long lockdep_count_backward_deps(struct lock_class *class)
1267{
1268 unsigned long ret, flags;
Ming Leief681022009-07-16 15:44:29 +02001269 struct lock_list this;
1270
1271 this.parent = NULL;
1272 this.class = class;
David Miller419ca3f2008-07-29 21:45:03 -07001273
1274 local_irq_save(flags);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001275 arch_spin_lock(&lockdep_lock);
Ming Leief681022009-07-16 15:44:29 +02001276 ret = __lockdep_count_backward_deps(&this);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001277 arch_spin_unlock(&lockdep_lock);
David Miller419ca3f2008-07-29 21:45:03 -07001278 local_irq_restore(flags);
1279
1280 return ret;
1281}
1282
Peter Zijlstra8e182572007-07-19 01:48:54 -07001283/*
1284 * Prove that the dependency graph starting at <entry> can not
1285 * lead to <target>. Print an error and return 0 if it does.
1286 */
1287static noinline int
Ming Leidb0002a2009-07-16 15:44:29 +02001288check_noncircular(struct lock_list *root, struct lock_class *target,
1289 struct lock_list **target_entry)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001290{
Ming Leidb0002a2009-07-16 15:44:29 +02001291 int result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001292
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001293 debug_atomic_inc(nr_cyclic_checks);
David Miller419ca3f2008-07-29 21:45:03 -07001294
Ming Leid7aaba12009-07-16 15:44:29 +02001295 result = __bfs_forwards(root, target, class_equal, target_entry);
Ming Leidb0002a2009-07-16 15:44:29 +02001296
1297 return result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001298}
1299
Steven Rostedt81d68a92008-05-12 21:20:42 +02001300#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001301/*
1302 * Forwards and backwards subgraph searching, for the purposes of
1303 * proving that two subgraphs can be connected by a new dependency
1304 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1305 */
Peter Zijlstra8e182572007-07-19 01:48:54 -07001306
Ming Leid7aaba12009-07-16 15:44:29 +02001307static inline int usage_match(struct lock_list *entry, void *bit)
1308{
1309 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1310}
1311
1312
1313
Peter Zijlstra8e182572007-07-19 01:48:54 -07001314/*
1315 * Find a node in the forwards-direction dependency sub-graph starting
Ming Leid7aaba12009-07-16 15:44:29 +02001316 * at @root->class that matches @bit.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001317 *
Ming Leid7aaba12009-07-16 15:44:29 +02001318 * Return 0 if such a node exists in the subgraph, and put that node
1319 * into *@target_entry.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001320 *
Ming Leid7aaba12009-07-16 15:44:29 +02001321 * Return 1 otherwise and keep *@target_entry unchanged.
1322 * Return <0 on error.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001323 */
Ming Leid7aaba12009-07-16 15:44:29 +02001324static int
1325find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1326 struct lock_list **target_entry)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001327{
Ming Leid7aaba12009-07-16 15:44:29 +02001328 int result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001329
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001330 debug_atomic_inc(nr_find_usage_forwards_checks);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001331
Ming Leid7aaba12009-07-16 15:44:29 +02001332 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1333
1334 return result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001335}
1336
1337/*
1338 * Find a node in the backwards-direction dependency sub-graph starting
Ming Leid7aaba12009-07-16 15:44:29 +02001339 * at @root->class that matches @bit.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001340 *
Ming Leid7aaba12009-07-16 15:44:29 +02001341 * Return 0 if such a node exists in the subgraph, and put that node
1342 * into *@target_entry.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001343 *
Ming Leid7aaba12009-07-16 15:44:29 +02001344 * Return 1 otherwise and keep *@target_entry unchanged.
1345 * Return <0 on error.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001346 */
Ming Leid7aaba12009-07-16 15:44:29 +02001347static int
1348find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1349 struct lock_list **target_entry)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001350{
Ming Leid7aaba12009-07-16 15:44:29 +02001351 int result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001352
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001353 debug_atomic_inc(nr_find_usage_backwards_checks);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001354
Ming Leid7aaba12009-07-16 15:44:29 +02001355 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
Dave Jonesf82b2172008-08-11 09:30:23 +02001356
Ming Leid7aaba12009-07-16 15:44:29 +02001357 return result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001358}
1359
Peter Zijlstraaf012962009-07-16 15:44:29 +02001360static void print_lock_class_header(struct lock_class *class, int depth)
1361{
1362 int bit;
1363
1364 printk("%*s->", depth, "");
1365 print_lock_name(class);
1366 printk(" ops: %lu", class->ops);
1367 printk(" {\n");
1368
1369 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1370 if (class->usage_mask & (1 << bit)) {
1371 int len = depth;
1372
1373 len += printk("%*s %s", depth, "", usage_str[bit]);
1374 len += printk(" at:\n");
1375 print_stack_trace(class->usage_traces + bit, len);
1376 }
1377 }
1378 printk("%*s }\n", depth, "");
1379
1380 printk("%*s ... key at: ",depth,"");
1381 print_ip_sym((unsigned long)class->key);
1382}
1383
1384/*
1385 * printk the shortest lock dependencies from @start to @end in reverse order:
1386 */
1387static void __used
1388print_shortest_lock_dependencies(struct lock_list *leaf,
1389 struct lock_list *root)
1390{
1391 struct lock_list *entry = leaf;
1392 int depth;
1393
1394 /*compute depth from generated tree by BFS*/
1395 depth = get_lock_depth(leaf);
1396
1397 do {
1398 print_lock_class_header(entry->class, depth);
1399 printk("%*s ... acquired at:\n", depth, "");
1400 print_stack_trace(&entry->trace, 2);
1401 printk("\n");
1402
1403 if (depth == 0 && (entry != root)) {
Steven Rostedt6be8c392011-04-20 21:41:58 -04001404 printk("lockdep:%s bad path found in chain graph\n", __func__);
Peter Zijlstraaf012962009-07-16 15:44:29 +02001405 break;
1406 }
1407
1408 entry = get_lock_parent(entry);
1409 depth--;
1410 } while (entry && (depth >= 0));
1411
1412 return;
1413}
Ming Leid7aaba12009-07-16 15:44:29 +02001414
Steven Rostedt3003eba2011-04-20 21:41:54 -04001415static void
1416print_irq_lock_scenario(struct lock_list *safe_entry,
1417 struct lock_list *unsafe_entry,
Steven Rostedtdad3d742011-04-20 21:41:57 -04001418 struct lock_class *prev_class,
1419 struct lock_class *next_class)
Steven Rostedt3003eba2011-04-20 21:41:54 -04001420{
1421 struct lock_class *safe_class = safe_entry->class;
1422 struct lock_class *unsafe_class = unsafe_entry->class;
Steven Rostedtdad3d742011-04-20 21:41:57 -04001423 struct lock_class *middle_class = prev_class;
Steven Rostedt3003eba2011-04-20 21:41:54 -04001424
1425 if (middle_class == safe_class)
Steven Rostedtdad3d742011-04-20 21:41:57 -04001426 middle_class = next_class;
Steven Rostedt3003eba2011-04-20 21:41:54 -04001427
1428 /*
1429 * A direct locking problem where unsafe_class lock is taken
1430 * directly by safe_class lock, then all we need to show
1431 * is the deadlock scenario, as it is obvious that the
1432 * unsafe lock is taken under the safe lock.
1433 *
1434 * But if there is a chain instead, where the safe lock takes
1435 * an intermediate lock (middle_class) where this lock is
1436 * not the same as the safe lock, then the lock chain is
1437 * used to describe the problem. Otherwise we would need
1438 * to show a different CPU case for each link in the chain
1439 * from the safe_class lock to the unsafe_class lock.
1440 */
1441 if (middle_class != unsafe_class) {
1442 printk("Chain exists of:\n ");
1443 __print_lock_name(safe_class);
1444 printk(" --> ");
1445 __print_lock_name(middle_class);
1446 printk(" --> ");
1447 __print_lock_name(unsafe_class);
1448 printk("\n\n");
1449 }
1450
1451 printk(" Possible interrupt unsafe locking scenario:\n\n");
1452 printk(" CPU0 CPU1\n");
1453 printk(" ---- ----\n");
1454 printk(" lock(");
1455 __print_lock_name(unsafe_class);
1456 printk(");\n");
1457 printk(" local_irq_disable();\n");
1458 printk(" lock(");
1459 __print_lock_name(safe_class);
1460 printk(");\n");
1461 printk(" lock(");
1462 __print_lock_name(middle_class);
1463 printk(");\n");
1464 printk(" <Interrupt>\n");
1465 printk(" lock(");
1466 __print_lock_name(safe_class);
1467 printk(");\n");
1468 printk("\n *** DEADLOCK ***\n\n");
1469}
1470
Peter Zijlstra8e182572007-07-19 01:48:54 -07001471static int
1472print_bad_irq_dependency(struct task_struct *curr,
Ming Lei24208ca2009-07-16 15:44:29 +02001473 struct lock_list *prev_root,
1474 struct lock_list *next_root,
1475 struct lock_list *backwards_entry,
1476 struct lock_list *forwards_entry,
Peter Zijlstra8e182572007-07-19 01:48:54 -07001477 struct held_lock *prev,
1478 struct held_lock *next,
1479 enum lock_usage_bit bit1,
1480 enum lock_usage_bit bit2,
1481 const char *irqclass)
1482{
1483 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1484 return 0;
1485
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001486 printk("\n");
1487 printk("======================================================\n");
1488 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
Peter Zijlstra8e182572007-07-19 01:48:54 -07001489 irqclass, irqclass);
1490 print_kernel_version();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001491 printk("------------------------------------------------------\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001492 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 -07001493 curr->comm, task_pid_nr(curr),
Peter Zijlstra8e182572007-07-19 01:48:54 -07001494 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1495 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1496 curr->hardirqs_enabled,
1497 curr->softirqs_enabled);
1498 print_lock(next);
1499
1500 printk("\nand this task is already holding:\n");
1501 print_lock(prev);
1502 printk("which would create a new lock dependency:\n");
Dave Jonesf82b2172008-08-11 09:30:23 +02001503 print_lock_name(hlock_class(prev));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001504 printk(" ->");
Dave Jonesf82b2172008-08-11 09:30:23 +02001505 print_lock_name(hlock_class(next));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001506 printk("\n");
1507
1508 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1509 irqclass);
Ming Lei24208ca2009-07-16 15:44:29 +02001510 print_lock_name(backwards_entry->class);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001511 printk("\n... which became %s-irq-safe at:\n", irqclass);
1512
Ming Lei24208ca2009-07-16 15:44:29 +02001513 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001514
1515 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
Ming Lei24208ca2009-07-16 15:44:29 +02001516 print_lock_name(forwards_entry->class);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001517 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1518 printk("...");
1519
Ming Lei24208ca2009-07-16 15:44:29 +02001520 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001521
1522 printk("\nother info that might help us debug this:\n\n");
Steven Rostedtdad3d742011-04-20 21:41:57 -04001523 print_irq_lock_scenario(backwards_entry, forwards_entry,
1524 hlock_class(prev), hlock_class(next));
Steven Rostedt3003eba2011-04-20 21:41:54 -04001525
Peter Zijlstra8e182572007-07-19 01:48:54 -07001526 lockdep_print_held_locks(curr);
1527
Ming Lei24208ca2009-07-16 15:44:29 +02001528 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1529 printk(" and the holding lock:\n");
1530 if (!save_trace(&prev_root->trace))
1531 return 0;
1532 print_shortest_lock_dependencies(backwards_entry, prev_root);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001533
Ming Lei24208ca2009-07-16 15:44:29 +02001534 printk("\nthe dependencies between the lock to be acquired");
1535 printk(" and %s-irq-unsafe lock:\n", irqclass);
1536 if (!save_trace(&next_root->trace))
1537 return 0;
1538 print_shortest_lock_dependencies(forwards_entry, next_root);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001539
1540 printk("\nstack backtrace:\n");
1541 dump_stack();
1542
1543 return 0;
1544}
1545
1546static int
1547check_usage(struct task_struct *curr, struct held_lock *prev,
1548 struct held_lock *next, enum lock_usage_bit bit_backwards,
1549 enum lock_usage_bit bit_forwards, const char *irqclass)
1550{
1551 int ret;
Ming Lei24208ca2009-07-16 15:44:29 +02001552 struct lock_list this, that;
Ming Leid7aaba12009-07-16 15:44:29 +02001553 struct lock_list *uninitialized_var(target_entry);
Ming Lei24208ca2009-07-16 15:44:29 +02001554 struct lock_list *uninitialized_var(target_entry1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001555
Ming Leid7aaba12009-07-16 15:44:29 +02001556 this.parent = NULL;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001557
Ming Leid7aaba12009-07-16 15:44:29 +02001558 this.class = hlock_class(prev);
1559 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
Peter Zijlstraaf012962009-07-16 15:44:29 +02001560 if (ret < 0)
1561 return print_bfs_bug(ret);
1562 if (ret == 1)
1563 return ret;
Ming Leid7aaba12009-07-16 15:44:29 +02001564
Ming Lei24208ca2009-07-16 15:44:29 +02001565 that.parent = NULL;
1566 that.class = hlock_class(next);
1567 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
Peter Zijlstraaf012962009-07-16 15:44:29 +02001568 if (ret < 0)
1569 return print_bfs_bug(ret);
1570 if (ret == 1)
1571 return ret;
Ming Leid7aaba12009-07-16 15:44:29 +02001572
Ming Lei24208ca2009-07-16 15:44:29 +02001573 return print_bad_irq_dependency(curr, &this, &that,
1574 target_entry, target_entry1,
1575 prev, next,
Peter Zijlstra8e182572007-07-19 01:48:54 -07001576 bit_backwards, bit_forwards, irqclass);
1577}
1578
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001579static const char *state_names[] = {
1580#define LOCKDEP_STATE(__STATE) \
Peter Zijlstrab4b136f2009-01-29 14:50:36 +01001581 __stringify(__STATE),
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001582#include "lockdep_states.h"
1583#undef LOCKDEP_STATE
1584};
1585
1586static const char *state_rnames[] = {
1587#define LOCKDEP_STATE(__STATE) \
Peter Zijlstrab4b136f2009-01-29 14:50:36 +01001588 __stringify(__STATE)"-READ",
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001589#include "lockdep_states.h"
1590#undef LOCKDEP_STATE
1591};
1592
1593static inline const char *state_name(enum lock_usage_bit bit)
1594{
1595 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1596}
1597
1598static int exclusive_bit(int new_bit)
1599{
1600 /*
1601 * USED_IN
1602 * USED_IN_READ
1603 * ENABLED
1604 * ENABLED_READ
1605 *
1606 * bit 0 - write/read
1607 * bit 1 - used_in/enabled
1608 * bit 2+ state
1609 */
1610
1611 int state = new_bit & ~3;
1612 int dir = new_bit & 2;
1613
1614 /*
1615 * keep state, bit flip the direction and strip read.
1616 */
1617 return state | (dir ^ 2);
1618}
1619
1620static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1621 struct held_lock *next, enum lock_usage_bit bit)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001622{
1623 /*
1624 * Prove that the new dependency does not connect a hardirq-safe
1625 * lock with a hardirq-unsafe lock - to achieve this we search
1626 * the backwards-subgraph starting at <prev>, and the
1627 * forwards-subgraph starting at <next>:
1628 */
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001629 if (!check_usage(curr, prev, next, bit,
1630 exclusive_bit(bit), state_name(bit)))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001631 return 0;
1632
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001633 bit++; /* _READ */
1634
Peter Zijlstra8e182572007-07-19 01:48:54 -07001635 /*
1636 * Prove that the new dependency does not connect a hardirq-safe-read
1637 * lock with a hardirq-unsafe lock - to achieve this we search
1638 * the backwards-subgraph starting at <prev>, and the
1639 * forwards-subgraph starting at <next>:
1640 */
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001641 if (!check_usage(curr, prev, next, bit,
1642 exclusive_bit(bit), state_name(bit)))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001643 return 0;
1644
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001645 return 1;
1646}
Peter Zijlstra8e182572007-07-19 01:48:54 -07001647
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001648static int
1649check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1650 struct held_lock *next)
1651{
1652#define LOCKDEP_STATE(__STATE) \
1653 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
Nick Piggincf40bd12009-01-21 08:12:39 +01001654 return 0;
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001655#include "lockdep_states.h"
1656#undef LOCKDEP_STATE
Nick Piggincf40bd12009-01-21 08:12:39 +01001657
Peter Zijlstra8e182572007-07-19 01:48:54 -07001658 return 1;
1659}
1660
1661static void inc_chains(void)
1662{
1663 if (current->hardirq_context)
1664 nr_hardirq_chains++;
1665 else {
1666 if (current->softirq_context)
1667 nr_softirq_chains++;
1668 else
1669 nr_process_chains++;
1670 }
1671}
1672
1673#else
1674
1675static inline int
1676check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1677 struct held_lock *next)
1678{
1679 return 1;
1680}
1681
1682static inline void inc_chains(void)
1683{
1684 nr_process_chains++;
1685}
1686
1687#endif
1688
Steven Rostedt48702ec2011-04-20 21:41:56 -04001689static void
1690print_deadlock_scenario(struct held_lock *nxt,
1691 struct held_lock *prv)
1692{
1693 struct lock_class *next = hlock_class(nxt);
1694 struct lock_class *prev = hlock_class(prv);
1695
1696 printk(" Possible unsafe locking scenario:\n\n");
1697 printk(" CPU0\n");
1698 printk(" ----\n");
1699 printk(" lock(");
1700 __print_lock_name(prev);
1701 printk(");\n");
1702 printk(" lock(");
1703 __print_lock_name(next);
1704 printk(");\n");
1705 printk("\n *** DEADLOCK ***\n\n");
1706 printk(" May be due to missing lock nesting notation\n\n");
1707}
1708
Peter Zijlstra8e182572007-07-19 01:48:54 -07001709static int
1710print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1711 struct held_lock *next)
1712{
1713 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1714 return 0;
1715
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001716 printk("\n");
1717 printk("=============================================\n");
1718 printk("[ INFO: possible recursive locking detected ]\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001719 print_kernel_version();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001720 printk("---------------------------------------------\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001721 printk("%s/%d is trying to acquire lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07001722 curr->comm, task_pid_nr(curr));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001723 print_lock(next);
1724 printk("\nbut task is already holding lock:\n");
1725 print_lock(prev);
1726
1727 printk("\nother info that might help us debug this:\n");
Steven Rostedt48702ec2011-04-20 21:41:56 -04001728 print_deadlock_scenario(next, prev);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001729 lockdep_print_held_locks(curr);
1730
1731 printk("\nstack backtrace:\n");
1732 dump_stack();
1733
1734 return 0;
1735}
1736
1737/*
1738 * Check whether we are holding such a class already.
1739 *
1740 * (Note that this has to be done separately, because the graph cannot
1741 * detect such classes of deadlocks.)
1742 *
1743 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1744 */
1745static int
1746check_deadlock(struct task_struct *curr, struct held_lock *next,
1747 struct lockdep_map *next_instance, int read)
1748{
1749 struct held_lock *prev;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001750 struct held_lock *nest = NULL;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001751 int i;
1752
1753 for (i = 0; i < curr->lockdep_depth; i++) {
1754 prev = curr->held_locks + i;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001755
1756 if (prev->instance == next->nest_lock)
1757 nest = prev;
1758
Dave Jonesf82b2172008-08-11 09:30:23 +02001759 if (hlock_class(prev) != hlock_class(next))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001760 continue;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001761
Peter Zijlstra8e182572007-07-19 01:48:54 -07001762 /*
1763 * Allow read-after-read recursion of the same
1764 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1765 */
1766 if ((read == 2) && prev->read)
1767 return 2;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001768
1769 /*
1770 * We're holding the nest_lock, which serializes this lock's
1771 * nesting behaviour.
1772 */
1773 if (nest)
1774 return 2;
1775
Peter Zijlstra8e182572007-07-19 01:48:54 -07001776 return print_deadlock_bug(curr, prev, next);
1777 }
1778 return 1;
1779}
1780
1781/*
1782 * There was a chain-cache miss, and we are about to add a new dependency
1783 * to a previous lock. We recursively validate the following rules:
1784 *
1785 * - would the adding of the <prev> -> <next> dependency create a
1786 * circular dependency in the graph? [== circular deadlock]
1787 *
1788 * - does the new prev->next dependency connect any hardirq-safe lock
1789 * (in the full backwards-subgraph starting at <prev>) with any
1790 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1791 * <next>)? [== illegal lock inversion with hardirq contexts]
1792 *
1793 * - does the new prev->next dependency connect any softirq-safe lock
1794 * (in the full backwards-subgraph starting at <prev>) with any
1795 * softirq-unsafe lock (in the full forwards-subgraph starting at
1796 * <next>)? [== illegal lock inversion with softirq contexts]
1797 *
1798 * any of these scenarios could lead to a deadlock.
1799 *
1800 * Then if all the validations pass, we add the forwards and backwards
1801 * dependency.
1802 */
1803static int
1804check_prev_add(struct task_struct *curr, struct held_lock *prev,
Yong Zhang4726f2a2010-05-04 14:16:48 +08001805 struct held_lock *next, int distance, int trylock_loop)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001806{
1807 struct lock_list *entry;
1808 int ret;
Ming Leidb0002a2009-07-16 15:44:29 +02001809 struct lock_list this;
1810 struct lock_list *uninitialized_var(target_entry);
Yong Zhang4726f2a2010-05-04 14:16:48 +08001811 /*
1812 * Static variable, serialized by the graph_lock().
1813 *
1814 * We use this static variable to save the stack trace in case
1815 * we call into this function multiple times due to encountering
1816 * trylocks in the held lock stack.
1817 */
1818 static struct stack_trace trace;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001819
1820 /*
1821 * Prove that the new <prev> -> <next> dependency would not
1822 * create a circular dependency in the graph. (We do this by
1823 * forward-recursing into the graph starting at <next>, and
1824 * checking whether we can reach <prev>.)
1825 *
1826 * We are using global variables to control the recursion, to
1827 * keep the stackframe size of the recursive functions low:
1828 */
Ming Leidb0002a2009-07-16 15:44:29 +02001829 this.class = hlock_class(next);
1830 this.parent = NULL;
1831 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1832 if (unlikely(!ret))
1833 return print_circular_bug(&this, target_entry, next, prev);
1834 else if (unlikely(ret < 0))
1835 return print_bfs_bug(ret);
Ming Leic94aa5c2009-07-16 15:44:29 +02001836
Peter Zijlstra8e182572007-07-19 01:48:54 -07001837 if (!check_prev_add_irq(curr, prev, next))
1838 return 0;
1839
1840 /*
1841 * For recursive read-locks we do all the dependency checks,
1842 * but we dont store read-triggered dependencies (only
1843 * write-triggered dependencies). This ensures that only the
1844 * write-side dependencies matter, and that if for example a
1845 * write-lock never takes any other locks, then the reads are
1846 * equivalent to a NOP.
1847 */
1848 if (next->read == 2 || prev->read == 2)
1849 return 1;
1850 /*
1851 * Is the <prev> -> <next> dependency already present?
1852 *
1853 * (this may occur even though this is a new chain: consider
1854 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1855 * chains - the second one will be new, but L1 already has
1856 * L2 added to its dependency list, due to the first chain.)
1857 */
Dave Jonesf82b2172008-08-11 09:30:23 +02001858 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1859 if (entry->class == hlock_class(next)) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07001860 if (distance == 1)
1861 entry->distance = 1;
1862 return 2;
1863 }
1864 }
1865
Yong Zhang4726f2a2010-05-04 14:16:48 +08001866 if (!trylock_loop && !save_trace(&trace))
1867 return 0;
1868
Peter Zijlstra8e182572007-07-19 01:48:54 -07001869 /*
1870 * Ok, all validations passed, add the new lock
1871 * to the previous lock's dependency list:
1872 */
Dave Jonesf82b2172008-08-11 09:30:23 +02001873 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1874 &hlock_class(prev)->locks_after,
Yong Zhang4726f2a2010-05-04 14:16:48 +08001875 next->acquire_ip, distance, &trace);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001876
1877 if (!ret)
1878 return 0;
1879
Dave Jonesf82b2172008-08-11 09:30:23 +02001880 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1881 &hlock_class(next)->locks_before,
Yong Zhang4726f2a2010-05-04 14:16:48 +08001882 next->acquire_ip, distance, &trace);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001883 if (!ret)
1884 return 0;
1885
1886 /*
1887 * Debugging printouts:
1888 */
Dave Jonesf82b2172008-08-11 09:30:23 +02001889 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07001890 graph_unlock();
1891 printk("\n new dependency: ");
Dave Jonesf82b2172008-08-11 09:30:23 +02001892 print_lock_name(hlock_class(prev));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001893 printk(" => ");
Dave Jonesf82b2172008-08-11 09:30:23 +02001894 print_lock_name(hlock_class(next));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001895 printk("\n");
1896 dump_stack();
1897 return graph_lock();
1898 }
1899 return 1;
1900}
1901
1902/*
1903 * Add the dependency to all directly-previous locks that are 'relevant'.
1904 * The ones that are relevant are (in increasing distance from curr):
1905 * all consecutive trylock entries and the final non-trylock entry - or
1906 * the end of this context's lock-chain - whichever comes first.
1907 */
1908static int
1909check_prevs_add(struct task_struct *curr, struct held_lock *next)
1910{
1911 int depth = curr->lockdep_depth;
Yong Zhang4726f2a2010-05-04 14:16:48 +08001912 int trylock_loop = 0;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001913 struct held_lock *hlock;
1914
1915 /*
1916 * Debugging checks.
1917 *
1918 * Depth must not be zero for a non-head lock:
1919 */
1920 if (!depth)
1921 goto out_bug;
1922 /*
1923 * At least two relevant locks must exist for this
1924 * to be a head:
1925 */
1926 if (curr->held_locks[depth].irq_context !=
1927 curr->held_locks[depth-1].irq_context)
1928 goto out_bug;
1929
1930 for (;;) {
1931 int distance = curr->lockdep_depth - depth + 1;
1932 hlock = curr->held_locks + depth-1;
1933 /*
1934 * Only non-recursive-read entries get new dependencies
1935 * added:
1936 */
1937 if (hlock->read != 2) {
Yong Zhang4726f2a2010-05-04 14:16:48 +08001938 if (!check_prev_add(curr, hlock, next,
1939 distance, trylock_loop))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001940 return 0;
1941 /*
1942 * Stop after the first non-trylock entry,
1943 * as non-trylock entries have added their
1944 * own direct dependencies already, so this
1945 * lock is connected to them indirectly:
1946 */
1947 if (!hlock->trylock)
1948 break;
1949 }
1950 depth--;
1951 /*
1952 * End of lock-stack?
1953 */
1954 if (!depth)
1955 break;
1956 /*
1957 * Stop the search if we cross into another context:
1958 */
1959 if (curr->held_locks[depth].irq_context !=
1960 curr->held_locks[depth-1].irq_context)
1961 break;
Yong Zhang4726f2a2010-05-04 14:16:48 +08001962 trylock_loop = 1;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001963 }
1964 return 1;
1965out_bug:
1966 if (!debug_locks_off_graph_unlock())
1967 return 0;
1968
Peter Zijlstra0119fee2011-09-02 01:30:29 +02001969 /*
1970 * Clearly we all shouldn't be here, but since we made it we
1971 * can reliable say we messed up our state. See the above two
1972 * gotos for reasons why we could possibly end up here.
1973 */
Peter Zijlstra8e182572007-07-19 01:48:54 -07001974 WARN_ON(1);
1975
1976 return 0;
1977}
1978
1979unsigned long nr_lock_chains;
Huang, Ying443cd502008-06-20 16:39:21 +08001980struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
Huang, Yingcd1a28e2008-06-23 11:20:54 +08001981int nr_chain_hlocks;
Huang, Ying443cd502008-06-20 16:39:21 +08001982static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1983
1984struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1985{
1986 return lock_classes + chain_hlocks[chain->base + i];
1987}
Peter Zijlstra8e182572007-07-19 01:48:54 -07001988
1989/*
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001990 * Look up a dependency chain. If the key is not present yet then
Jarek Poplawski9e860d02007-05-08 00:30:12 -07001991 * add it and return 1 - in this case the new dependency chain is
1992 * validated. If the key is already hashed, return 0.
1993 * (On return with 1 graph_lock is held.)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001994 */
Huang, Ying443cd502008-06-20 16:39:21 +08001995static inline int lookup_chain_cache(struct task_struct *curr,
1996 struct held_lock *hlock,
1997 u64 chain_key)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001998{
Dave Jonesf82b2172008-08-11 09:30:23 +02001999 struct lock_class *class = hlock_class(hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002000 struct list_head *hash_head = chainhashentry(chain_key);
2001 struct lock_chain *chain;
Huang, Ying443cd502008-06-20 16:39:21 +08002002 struct held_lock *hlock_curr, *hlock_next;
Steven Rostedte0944ee2011-04-20 21:42:00 -04002003 int i, j;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002004
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002005 /*
2006 * We might need to take the graph lock, ensure we've got IRQs
2007 * disabled to make this an IRQ-safe lock.. for recursion reasons
2008 * lockdep won't complain about its own locking errors.
2009 */
Jarek Poplawski381a2292007-02-10 01:44:58 -08002010 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2011 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002012 /*
2013 * We can walk it lock-free, because entries only get added
2014 * to the hash:
2015 */
2016 list_for_each_entry(chain, hash_head, entry) {
2017 if (chain->chain_key == chain_key) {
2018cache_hit:
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002019 debug_atomic_inc(chain_lookup_hits);
Ingo Molnar81fc6852006-12-13 00:34:40 -08002020 if (very_verbose(class))
Andrew Morton755cd902006-12-29 16:49:14 -08002021 printk("\nhash chain already cached, key: "
2022 "%016Lx tail class: [%p] %s\n",
2023 (unsigned long long)chain_key,
2024 class->key, class->name);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002025 return 0;
2026 }
2027 }
Ingo Molnar81fc6852006-12-13 00:34:40 -08002028 if (very_verbose(class))
Andrew Morton755cd902006-12-29 16:49:14 -08002029 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2030 (unsigned long long)chain_key, class->key, class->name);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002031 /*
2032 * Allocate a new chain entry from the static array, and add
2033 * it to the hash:
2034 */
Ingo Molnar74c383f2006-12-13 00:34:43 -08002035 if (!graph_lock())
2036 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002037 /*
2038 * We have to walk the chain again locked - to avoid duplicates:
2039 */
2040 list_for_each_entry(chain, hash_head, entry) {
2041 if (chain->chain_key == chain_key) {
Ingo Molnar74c383f2006-12-13 00:34:43 -08002042 graph_unlock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002043 goto cache_hit;
2044 }
2045 }
2046 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
Ingo Molnar74c383f2006-12-13 00:34:43 -08002047 if (!debug_locks_off_graph_unlock())
2048 return 0;
2049
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002050 printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
2051 printk("turning off the locking correctness validator.\n");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +01002052 dump_stack();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002053 return 0;
2054 }
2055 chain = lock_chains + nr_lock_chains++;
2056 chain->chain_key = chain_key;
Huang, Ying443cd502008-06-20 16:39:21 +08002057 chain->irq_context = hlock->irq_context;
2058 /* Find the first held_lock of current chain */
2059 hlock_next = hlock;
2060 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2061 hlock_curr = curr->held_locks + i;
2062 if (hlock_curr->irq_context != hlock_next->irq_context)
2063 break;
2064 hlock_next = hlock;
2065 }
2066 i++;
2067 chain->depth = curr->lockdep_depth + 1 - i;
Steven Rostedte0944ee2011-04-20 21:42:00 -04002068 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2069 chain->base = nr_chain_hlocks;
2070 nr_chain_hlocks += chain->depth;
Huang, Ying443cd502008-06-20 16:39:21 +08002071 for (j = 0; j < chain->depth - 1; j++, i++) {
Dave Jonesf82b2172008-08-11 09:30:23 +02002072 int lock_id = curr->held_locks[i].class_idx - 1;
Huang, Ying443cd502008-06-20 16:39:21 +08002073 chain_hlocks[chain->base + j] = lock_id;
2074 }
2075 chain_hlocks[chain->base + j] = class - lock_classes;
2076 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002077 list_add_tail_rcu(&chain->entry, hash_head);
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002078 debug_atomic_inc(chain_lookup_misses);
Peter Zijlstra8e182572007-07-19 01:48:54 -07002079 inc_chains();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002080
2081 return 1;
2082}
Peter Zijlstra8e182572007-07-19 01:48:54 -07002083
2084static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
Johannes Berg4e6045f2007-10-18 23:39:55 -07002085 struct held_lock *hlock, int chain_head, u64 chain_key)
Peter Zijlstra8e182572007-07-19 01:48:54 -07002086{
2087 /*
2088 * Trylock needs to maintain the stack of held locks, but it
2089 * does not add new dependencies, because trylock can be done
2090 * in any order.
2091 *
2092 * We look up the chain_key and do the O(N^2) check and update of
2093 * the dependencies only if this is a new dependency chain.
2094 * (If lookup_chain_cache() returns with 1 it acquires
2095 * graph_lock for us)
2096 */
2097 if (!hlock->trylock && (hlock->check == 2) &&
Huang, Ying443cd502008-06-20 16:39:21 +08002098 lookup_chain_cache(curr, hlock, chain_key)) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07002099 /*
2100 * Check whether last held lock:
2101 *
2102 * - is irq-safe, if this lock is irq-unsafe
2103 * - is softirq-safe, if this lock is hardirq-unsafe
2104 *
2105 * And check whether the new lock's dependency graph
2106 * could lead back to the previous lock.
2107 *
2108 * any of these scenarios could lead to a deadlock. If
2109 * All validations
2110 */
2111 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2112
2113 if (!ret)
2114 return 0;
2115 /*
2116 * Mark recursive read, as we jump over it when
2117 * building dependencies (just like we jump over
2118 * trylock entries):
2119 */
2120 if (ret == 2)
2121 hlock->read = 2;
2122 /*
2123 * Add dependency only if this lock is not the head
2124 * of the chain, and if it's not a secondary read-lock:
2125 */
2126 if (!chain_head && ret != 2)
2127 if (!check_prevs_add(curr, hlock))
2128 return 0;
2129 graph_unlock();
2130 } else
2131 /* after lookup_chain_cache(): */
2132 if (unlikely(!debug_locks))
2133 return 0;
2134
2135 return 1;
2136}
2137#else
2138static inline int validate_chain(struct task_struct *curr,
2139 struct lockdep_map *lock, struct held_lock *hlock,
Gregory Haskins3aa416b2007-10-11 22:11:11 +02002140 int chain_head, u64 chain_key)
Peter Zijlstra8e182572007-07-19 01:48:54 -07002141{
2142 return 1;
2143}
Peter Zijlstraca58abc2007-07-19 01:48:53 -07002144#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002145
2146/*
2147 * We are building curr_chain_key incrementally, so double-check
2148 * it from scratch, to make sure that it's done correctly:
2149 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002150static void check_chain_key(struct task_struct *curr)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002151{
2152#ifdef CONFIG_DEBUG_LOCKDEP
2153 struct held_lock *hlock, *prev_hlock = NULL;
2154 unsigned int i, id;
2155 u64 chain_key = 0;
2156
2157 for (i = 0; i < curr->lockdep_depth; i++) {
2158 hlock = curr->held_locks + i;
2159 if (chain_key != hlock->prev_chain_key) {
2160 debug_locks_off();
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002161 /*
2162 * We got mighty confused, our chain keys don't match
2163 * with what we expect, someone trample on our task state?
2164 */
Arjan van de Ven2df8b1d2008-07-30 12:43:11 -07002165 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002166 curr->lockdep_depth, i,
2167 (unsigned long long)chain_key,
2168 (unsigned long long)hlock->prev_chain_key);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002169 return;
2170 }
Dave Jonesf82b2172008-08-11 09:30:23 +02002171 id = hlock->class_idx - 1;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002172 /*
2173 * Whoops ran out of static storage again?
2174 */
Jarek Poplawski381a2292007-02-10 01:44:58 -08002175 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2176 return;
2177
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002178 if (prev_hlock && (prev_hlock->irq_context !=
2179 hlock->irq_context))
2180 chain_key = 0;
2181 chain_key = iterate_chain_key(chain_key, id);
2182 prev_hlock = hlock;
2183 }
2184 if (chain_key != curr->curr_chain_key) {
2185 debug_locks_off();
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002186 /*
2187 * More smoking hash instead of calculating it, damn see these
2188 * numbers float.. I bet that a pink elephant stepped on my memory.
2189 */
Arjan van de Ven2df8b1d2008-07-30 12:43:11 -07002190 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002191 curr->lockdep_depth, i,
2192 (unsigned long long)chain_key,
2193 (unsigned long long)curr->curr_chain_key);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002194 }
2195#endif
2196}
2197
Steven Rostedt282b5c22011-04-20 21:41:59 -04002198static void
2199print_usage_bug_scenario(struct held_lock *lock)
2200{
2201 struct lock_class *class = hlock_class(lock);
2202
2203 printk(" Possible unsafe locking scenario:\n\n");
2204 printk(" CPU0\n");
2205 printk(" ----\n");
2206 printk(" lock(");
2207 __print_lock_name(class);
2208 printk(");\n");
2209 printk(" <Interrupt>\n");
2210 printk(" lock(");
2211 __print_lock_name(class);
2212 printk(");\n");
2213 printk("\n *** DEADLOCK ***\n\n");
2214}
2215
Peter Zijlstra8e182572007-07-19 01:48:54 -07002216static int
2217print_usage_bug(struct task_struct *curr, struct held_lock *this,
2218 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2219{
2220 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2221 return 0;
2222
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07002223 printk("\n");
2224 printk("=================================\n");
2225 printk("[ INFO: inconsistent lock state ]\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07002226 print_kernel_version();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07002227 printk("---------------------------------\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07002228
2229 printk("inconsistent {%s} -> {%s} usage.\n",
2230 usage_str[prev_bit], usage_str[new_bit]);
2231
2232 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07002233 curr->comm, task_pid_nr(curr),
Peter Zijlstra8e182572007-07-19 01:48:54 -07002234 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2235 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2236 trace_hardirqs_enabled(curr),
2237 trace_softirqs_enabled(curr));
2238 print_lock(this);
2239
2240 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
Dave Jonesf82b2172008-08-11 09:30:23 +02002241 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07002242
2243 print_irqtrace_events(curr);
2244 printk("\nother info that might help us debug this:\n");
Steven Rostedt282b5c22011-04-20 21:41:59 -04002245 print_usage_bug_scenario(this);
2246
Peter Zijlstra8e182572007-07-19 01:48:54 -07002247 lockdep_print_held_locks(curr);
2248
2249 printk("\nstack backtrace:\n");
2250 dump_stack();
2251
2252 return 0;
2253}
2254
2255/*
2256 * Print out an error if an invalid bit is set:
2257 */
2258static inline int
2259valid_state(struct task_struct *curr, struct held_lock *this,
2260 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2261{
Dave Jonesf82b2172008-08-11 09:30:23 +02002262 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002263 return print_usage_bug(curr, this, bad_bit, new_bit);
2264 return 1;
2265}
2266
2267static int mark_lock(struct task_struct *curr, struct held_lock *this,
2268 enum lock_usage_bit new_bit);
2269
Steven Rostedt81d68a92008-05-12 21:20:42 +02002270#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002271
2272/*
2273 * print irq inversion bug:
2274 */
2275static int
Ming Lei24208ca2009-07-16 15:44:29 +02002276print_irq_inversion_bug(struct task_struct *curr,
2277 struct lock_list *root, struct lock_list *other,
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002278 struct held_lock *this, int forwards,
2279 const char *irqclass)
2280{
Steven Rostedtdad3d742011-04-20 21:41:57 -04002281 struct lock_list *entry = other;
2282 struct lock_list *middle = NULL;
2283 int depth;
2284
Ingo Molnar74c383f2006-12-13 00:34:43 -08002285 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002286 return 0;
2287
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07002288 printk("\n");
2289 printk("=========================================================\n");
2290 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
Dave Jones99de0552006-09-29 02:00:10 -07002291 print_kernel_version();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07002292 printk("---------------------------------------------------------\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002293 printk("%s/%d just changed the state of lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07002294 curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002295 print_lock(this);
2296 if (forwards)
Peter Zijlstra26575e22009-03-04 14:53:24 +01002297 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002298 else
Peter Zijlstra26575e22009-03-04 14:53:24 +01002299 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
Ming Lei24208ca2009-07-16 15:44:29 +02002300 print_lock_name(other->class);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002301 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2302
2303 printk("\nother info that might help us debug this:\n");
Steven Rostedtdad3d742011-04-20 21:41:57 -04002304
2305 /* Find a middle lock (if one exists) */
2306 depth = get_lock_depth(other);
2307 do {
2308 if (depth == 0 && (entry != root)) {
2309 printk("lockdep:%s bad path found in chain graph\n", __func__);
2310 break;
2311 }
2312 middle = entry;
2313 entry = get_lock_parent(entry);
2314 depth--;
2315 } while (entry && entry != root && (depth >= 0));
2316 if (forwards)
2317 print_irq_lock_scenario(root, other,
2318 middle ? middle->class : root->class, other->class);
2319 else
2320 print_irq_lock_scenario(other, root,
2321 middle ? middle->class : other->class, root->class);
2322
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002323 lockdep_print_held_locks(curr);
2324
Ming Lei24208ca2009-07-16 15:44:29 +02002325 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2326 if (!save_trace(&root->trace))
2327 return 0;
2328 print_shortest_lock_dependencies(other, root);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002329
2330 printk("\nstack backtrace:\n");
2331 dump_stack();
2332
2333 return 0;
2334}
2335
2336/*
2337 * Prove that in the forwards-direction subgraph starting at <this>
2338 * there is no lock matching <mask>:
2339 */
2340static int
2341check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2342 enum lock_usage_bit bit, const char *irqclass)
2343{
2344 int ret;
Ming Leid7aaba12009-07-16 15:44:29 +02002345 struct lock_list root;
2346 struct lock_list *uninitialized_var(target_entry);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002347
Ming Leid7aaba12009-07-16 15:44:29 +02002348 root.parent = NULL;
2349 root.class = hlock_class(this);
2350 ret = find_usage_forwards(&root, bit, &target_entry);
Peter Zijlstraaf012962009-07-16 15:44:29 +02002351 if (ret < 0)
2352 return print_bfs_bug(ret);
2353 if (ret == 1)
2354 return ret;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002355
Ming Lei24208ca2009-07-16 15:44:29 +02002356 return print_irq_inversion_bug(curr, &root, target_entry,
Ming Leid7aaba12009-07-16 15:44:29 +02002357 this, 1, irqclass);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002358}
2359
2360/*
2361 * Prove that in the backwards-direction subgraph starting at <this>
2362 * there is no lock matching <mask>:
2363 */
2364static int
2365check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2366 enum lock_usage_bit bit, const char *irqclass)
2367{
2368 int ret;
Ming Leid7aaba12009-07-16 15:44:29 +02002369 struct lock_list root;
2370 struct lock_list *uninitialized_var(target_entry);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002371
Ming Leid7aaba12009-07-16 15:44:29 +02002372 root.parent = NULL;
2373 root.class = hlock_class(this);
2374 ret = find_usage_backwards(&root, bit, &target_entry);
Peter Zijlstraaf012962009-07-16 15:44:29 +02002375 if (ret < 0)
2376 return print_bfs_bug(ret);
2377 if (ret == 1)
2378 return ret;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002379
Ming Lei24208ca2009-07-16 15:44:29 +02002380 return print_irq_inversion_bug(curr, &root, target_entry,
Oleg Nesterov48d50672010-01-26 19:16:41 +01002381 this, 0, irqclass);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002382}
2383
Ingo Molnar3117df02006-12-13 00:34:43 -08002384void print_irqtrace_events(struct task_struct *curr)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002385{
2386 printk("irq event stamp: %u\n", curr->irq_events);
2387 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2388 print_ip_sym(curr->hardirq_enable_ip);
2389 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2390 print_ip_sym(curr->hardirq_disable_ip);
2391 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2392 print_ip_sym(curr->softirq_enable_ip);
2393 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2394 print_ip_sym(curr->softirq_disable_ip);
2395}
2396
Peter Zijlstracd953022009-01-22 16:38:21 +01002397static int HARDIRQ_verbose(struct lock_class *class)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002398{
Peter Zijlstra8e182572007-07-19 01:48:54 -07002399#if HARDIRQ_VERBOSE
2400 return class_filter(class);
2401#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002402 return 0;
2403}
2404
Peter Zijlstracd953022009-01-22 16:38:21 +01002405static int SOFTIRQ_verbose(struct lock_class *class)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002406{
Peter Zijlstra8e182572007-07-19 01:48:54 -07002407#if SOFTIRQ_VERBOSE
2408 return class_filter(class);
2409#endif
2410 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002411}
2412
Peter Zijlstracd953022009-01-22 16:38:21 +01002413static int RECLAIM_FS_verbose(struct lock_class *class)
Nick Piggincf40bd12009-01-21 08:12:39 +01002414{
2415#if RECLAIM_VERBOSE
2416 return class_filter(class);
2417#endif
2418 return 0;
2419}
2420
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002421#define STRICT_READ_CHECKS 1
2422
Peter Zijlstracd953022009-01-22 16:38:21 +01002423static int (*state_verbose_f[])(struct lock_class *class) = {
2424#define LOCKDEP_STATE(__STATE) \
2425 __STATE##_verbose,
2426#include "lockdep_states.h"
2427#undef LOCKDEP_STATE
2428};
2429
2430static inline int state_verbose(enum lock_usage_bit bit,
2431 struct lock_class *class)
2432{
2433 return state_verbose_f[bit >> 2](class);
2434}
2435
Peter Zijlstra42c50d52009-01-22 16:58:16 +01002436typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2437 enum lock_usage_bit bit, const char *name);
2438
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002439static int
Peter Zijlstra1c21f142009-03-04 13:51:13 +01002440mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2441 enum lock_usage_bit new_bit)
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002442{
Peter Zijlstraf9892092009-01-22 16:09:59 +01002443 int excl_bit = exclusive_bit(new_bit);
Peter Zijlstra9d3651a2009-01-22 17:18:32 +01002444 int read = new_bit & 1;
Peter Zijlstra42c50d52009-01-22 16:58:16 +01002445 int dir = new_bit & 2;
2446
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002447 /*
2448 * mark USED_IN has to look forwards -- to ensure no dependency
2449 * has ENABLED state, which would allow recursion deadlocks.
2450 *
2451 * mark ENABLED has to look backwards -- to ensure no dependee
2452 * has USED_IN state, which, again, would allow recursion deadlocks.
2453 */
Peter Zijlstra42c50d52009-01-22 16:58:16 +01002454 check_usage_f usage = dir ?
2455 check_usage_backwards : check_usage_forwards;
Peter Zijlstraf9892092009-01-22 16:09:59 +01002456
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002457 /*
2458 * Validate that this particular lock does not have conflicting
2459 * usage states.
2460 */
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002461 if (!valid_state(curr, this, new_bit, excl_bit))
2462 return 0;
Peter Zijlstra9d3651a2009-01-22 17:18:32 +01002463
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002464 /*
2465 * Validate that the lock dependencies don't have conflicting usage
2466 * states.
2467 */
2468 if ((!read || !dir || STRICT_READ_CHECKS) &&
Peter Zijlstra1c21f142009-03-04 13:51:13 +01002469 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002470 return 0;
Peter Zijlstra780e8202009-01-22 16:51:29 +01002471
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002472 /*
2473 * Check for read in write conflicts
2474 */
2475 if (!read) {
2476 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2477 return 0;
2478
2479 if (STRICT_READ_CHECKS &&
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01002480 !usage(curr, this, excl_bit + 1,
2481 state_name(new_bit + 1)))
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002482 return 0;
2483 }
Peter Zijlstra780e8202009-01-22 16:51:29 +01002484
Peter Zijlstracd953022009-01-22 16:38:21 +01002485 if (state_verbose(new_bit, hlock_class(this)))
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002486 return 2;
2487
2488 return 1;
2489}
2490
Nick Piggincf40bd12009-01-21 08:12:39 +01002491enum mark_type {
Peter Zijlstra36bfb9b2009-01-22 14:12:41 +01002492#define LOCKDEP_STATE(__STATE) __STATE,
2493#include "lockdep_states.h"
2494#undef LOCKDEP_STATE
Nick Piggincf40bd12009-01-21 08:12:39 +01002495};
2496
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002497/*
2498 * Mark all held locks with a usage bit:
2499 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002500static int
Nick Piggincf40bd12009-01-21 08:12:39 +01002501mark_held_locks(struct task_struct *curr, enum mark_type mark)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002502{
2503 enum lock_usage_bit usage_bit;
2504 struct held_lock *hlock;
2505 int i;
2506
2507 for (i = 0; i < curr->lockdep_depth; i++) {
2508 hlock = curr->held_locks + i;
2509
Peter Zijlstracf2ad4d2009-01-27 13:58:08 +01002510 usage_bit = 2 + (mark << 2); /* ENABLED */
2511 if (hlock->read)
2512 usage_bit += 1; /* READ */
2513
2514 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
Nick Piggincf40bd12009-01-21 08:12:39 +01002515
Peter Zijlstra70a06862011-07-25 12:09:59 +02002516 if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
Peter Zijlstraefbe2ee2011-07-07 11:39:45 +02002517 continue;
2518
Jarek Poplawski4ff773bb2007-05-08 00:31:00 -07002519 if (!mark_lock(curr, hlock, usage_bit))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002520 return 0;
2521 }
2522
2523 return 1;
2524}
2525
2526/*
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002527 * Hardirqs will be enabled:
2528 */
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002529static void __trace_hardirqs_on_caller(unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002530{
2531 struct task_struct *curr = current;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002532
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002533 /* we'll do an OFF -> ON transition: */
2534 curr->hardirqs_enabled = 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002535
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002536 /*
2537 * We are going to turn hardirqs on, so set the
2538 * usage bit for all held locks:
2539 */
Nick Piggincf40bd12009-01-21 08:12:39 +01002540 if (!mark_held_locks(curr, HARDIRQ))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002541 return;
2542 /*
2543 * If we have softirqs enabled, then set the usage
2544 * bit for all held locks. (disabled hardirqs prevented
2545 * this bit from being set before)
2546 */
2547 if (curr->softirqs_enabled)
Nick Piggincf40bd12009-01-21 08:12:39 +01002548 if (!mark_held_locks(curr, SOFTIRQ))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002549 return;
2550
2551 curr->hardirq_enable_ip = ip;
2552 curr->hardirq_enable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002553 debug_atomic_inc(hardirqs_on_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002554}
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002555
2556void trace_hardirqs_on_caller(unsigned long ip)
2557{
2558 time_hardirqs_on(CALLER_ADDR0, ip);
2559
2560 if (unlikely(!debug_locks || current->lockdep_recursion))
2561 return;
2562
Peter Zijlstra7d36b262011-07-26 13:13:44 +02002563 if (unlikely(current->hardirqs_enabled)) {
2564 /*
2565 * Neither irq nor preemption are disabled here
2566 * so this is racy by nature but losing one hit
2567 * in a stat is not a big deal.
2568 */
2569 __debug_atomic_inc(redundant_hardirqs_on);
2570 return;
2571 }
2572
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002573 /*
2574 * We're enabling irqs and according to our state above irqs weren't
2575 * already enabled, yet we find the hardware thinks they are in fact
2576 * enabled.. someone messed up their IRQ state tracing.
2577 */
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002578 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2579 return;
2580
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002581 /*
2582 * See the fine text that goes along with this variable definition.
2583 */
Peter Zijlstra7d36b262011-07-26 13:13:44 +02002584 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2585 return;
2586
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002587 /*
2588 * Can't allow enabling interrupts while in an interrupt handler,
2589 * that's general bad form and such. Recursion, limited stack etc..
2590 */
Peter Zijlstra7d36b262011-07-26 13:13:44 +02002591 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2592 return;
2593
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002594 current->lockdep_recursion = 1;
2595 __trace_hardirqs_on_caller(ip);
2596 current->lockdep_recursion = 0;
2597}
Steven Rostedt81d68a92008-05-12 21:20:42 +02002598EXPORT_SYMBOL(trace_hardirqs_on_caller);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002599
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002600void trace_hardirqs_on(void)
Steven Rostedt81d68a92008-05-12 21:20:42 +02002601{
2602 trace_hardirqs_on_caller(CALLER_ADDR0);
2603}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002604EXPORT_SYMBOL(trace_hardirqs_on);
2605
2606/*
2607 * Hardirqs were disabled:
2608 */
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002609void trace_hardirqs_off_caller(unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002610{
2611 struct task_struct *curr = current;
2612
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002613 time_hardirqs_off(CALLER_ADDR0, ip);
Steven Rostedt81d68a92008-05-12 21:20:42 +02002614
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002615 if (unlikely(!debug_locks || current->lockdep_recursion))
2616 return;
2617
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002618 /*
2619 * So we're supposed to get called after you mask local IRQs, but for
2620 * some reason the hardware doesn't quite think you did a proper job.
2621 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002622 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2623 return;
2624
2625 if (curr->hardirqs_enabled) {
2626 /*
2627 * We have done an ON -> OFF transition:
2628 */
2629 curr->hardirqs_enabled = 0;
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002630 curr->hardirq_disable_ip = ip;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002631 curr->hardirq_disable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002632 debug_atomic_inc(hardirqs_off_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002633 } else
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002634 debug_atomic_inc(redundant_hardirqs_off);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002635}
Steven Rostedt81d68a92008-05-12 21:20:42 +02002636EXPORT_SYMBOL(trace_hardirqs_off_caller);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002637
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002638void trace_hardirqs_off(void)
Steven Rostedt81d68a92008-05-12 21:20:42 +02002639{
2640 trace_hardirqs_off_caller(CALLER_ADDR0);
2641}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002642EXPORT_SYMBOL(trace_hardirqs_off);
2643
2644/*
2645 * Softirqs will be enabled:
2646 */
2647void trace_softirqs_on(unsigned long ip)
2648{
2649 struct task_struct *curr = current;
2650
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002651 if (unlikely(!debug_locks || current->lockdep_recursion))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002652 return;
2653
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002654 /*
2655 * We fancy IRQs being disabled here, see softirq.c, avoids
2656 * funny state and nesting things.
2657 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002658 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2659 return;
2660
2661 if (curr->softirqs_enabled) {
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002662 debug_atomic_inc(redundant_softirqs_on);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002663 return;
2664 }
2665
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002666 current->lockdep_recursion = 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002667 /*
2668 * We'll do an OFF -> ON transition:
2669 */
2670 curr->softirqs_enabled = 1;
2671 curr->softirq_enable_ip = ip;
2672 curr->softirq_enable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002673 debug_atomic_inc(softirqs_on_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002674 /*
2675 * We are going to turn softirqs on, so set the
2676 * usage bit for all held locks, if hardirqs are
2677 * enabled too:
2678 */
2679 if (curr->hardirqs_enabled)
Nick Piggincf40bd12009-01-21 08:12:39 +01002680 mark_held_locks(curr, SOFTIRQ);
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002681 current->lockdep_recursion = 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002682}
2683
2684/*
2685 * Softirqs were disabled:
2686 */
2687void trace_softirqs_off(unsigned long ip)
2688{
2689 struct task_struct *curr = current;
2690
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002691 if (unlikely(!debug_locks || current->lockdep_recursion))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002692 return;
2693
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002694 /*
2695 * We fancy IRQs being disabled here, see softirq.c
2696 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002697 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2698 return;
2699
2700 if (curr->softirqs_enabled) {
2701 /*
2702 * We have done an ON -> OFF transition:
2703 */
2704 curr->softirqs_enabled = 0;
2705 curr->softirq_disable_ip = ip;
2706 curr->softirq_disable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002707 debug_atomic_inc(softirqs_off_events);
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002708 /*
2709 * Whoops, we wanted softirqs off, so why aren't they?
2710 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002711 DEBUG_LOCKS_WARN_ON(!softirq_count());
2712 } else
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002713 debug_atomic_inc(redundant_softirqs_off);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002714}
2715
Peter Zijlstra2f850182009-03-20 11:13:20 +01002716static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
Nick Piggincf40bd12009-01-21 08:12:39 +01002717{
2718 struct task_struct *curr = current;
2719
2720 if (unlikely(!debug_locks))
2721 return;
2722
2723 /* no reclaim without waiting on it */
2724 if (!(gfp_mask & __GFP_WAIT))
2725 return;
2726
2727 /* this guy won't enter reclaim */
2728 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2729 return;
2730
2731 /* We're only interested __GFP_FS allocations for now */
2732 if (!(gfp_mask & __GFP_FS))
2733 return;
2734
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002735 /*
2736 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2737 */
Peter Zijlstra2f850182009-03-20 11:13:20 +01002738 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
Nick Piggincf40bd12009-01-21 08:12:39 +01002739 return;
2740
2741 mark_held_locks(curr, RECLAIM_FS);
2742}
2743
Peter Zijlstra2f850182009-03-20 11:13:20 +01002744static void check_flags(unsigned long flags);
2745
2746void lockdep_trace_alloc(gfp_t gfp_mask)
2747{
2748 unsigned long flags;
2749
2750 if (unlikely(current->lockdep_recursion))
2751 return;
2752
2753 raw_local_irq_save(flags);
2754 check_flags(flags);
2755 current->lockdep_recursion = 1;
2756 __lockdep_trace_alloc(gfp_mask, flags);
2757 current->lockdep_recursion = 0;
2758 raw_local_irq_restore(flags);
2759}
2760
Peter Zijlstra8e182572007-07-19 01:48:54 -07002761static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2762{
2763 /*
2764 * If non-trylock use in a hardirq or softirq context, then
2765 * mark the lock as used in these contexts:
2766 */
2767 if (!hlock->trylock) {
2768 if (hlock->read) {
2769 if (curr->hardirq_context)
2770 if (!mark_lock(curr, hlock,
2771 LOCK_USED_IN_HARDIRQ_READ))
2772 return 0;
2773 if (curr->softirq_context)
2774 if (!mark_lock(curr, hlock,
2775 LOCK_USED_IN_SOFTIRQ_READ))
2776 return 0;
2777 } else {
2778 if (curr->hardirq_context)
2779 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2780 return 0;
2781 if (curr->softirq_context)
2782 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2783 return 0;
2784 }
2785 }
2786 if (!hlock->hardirqs_off) {
2787 if (hlock->read) {
2788 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002789 LOCK_ENABLED_HARDIRQ_READ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002790 return 0;
2791 if (curr->softirqs_enabled)
2792 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002793 LOCK_ENABLED_SOFTIRQ_READ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002794 return 0;
2795 } else {
2796 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002797 LOCK_ENABLED_HARDIRQ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002798 return 0;
2799 if (curr->softirqs_enabled)
2800 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002801 LOCK_ENABLED_SOFTIRQ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002802 return 0;
2803 }
2804 }
2805
Nick Piggincf40bd12009-01-21 08:12:39 +01002806 /*
2807 * We reuse the irq context infrastructure more broadly as a general
2808 * context checking code. This tests GFP_FS recursion (a lock taken
2809 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2810 * allocation).
2811 */
2812 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2813 if (hlock->read) {
2814 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2815 return 0;
2816 } else {
2817 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2818 return 0;
2819 }
2820 }
2821
Peter Zijlstra8e182572007-07-19 01:48:54 -07002822 return 1;
2823}
2824
2825static int separate_irq_context(struct task_struct *curr,
2826 struct held_lock *hlock)
2827{
2828 unsigned int depth = curr->lockdep_depth;
2829
2830 /*
2831 * Keep track of points where we cross into an interrupt context:
2832 */
2833 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2834 curr->softirq_context;
2835 if (depth) {
2836 struct held_lock *prev_hlock;
2837
2838 prev_hlock = curr->held_locks + depth-1;
2839 /*
2840 * If we cross into another context, reset the
2841 * hash key (this also prevents the checking and the
2842 * adding of the dependency to 'prev'):
2843 */
2844 if (prev_hlock->irq_context != hlock->irq_context)
2845 return 1;
2846 }
2847 return 0;
2848}
2849
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002850#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
Peter Zijlstra8e182572007-07-19 01:48:54 -07002851
2852static inline
2853int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2854 enum lock_usage_bit new_bit)
2855{
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002856 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
Peter Zijlstra8e182572007-07-19 01:48:54 -07002857 return 1;
2858}
2859
2860static inline int mark_irqflags(struct task_struct *curr,
2861 struct held_lock *hlock)
2862{
2863 return 1;
2864}
2865
2866static inline int separate_irq_context(struct task_struct *curr,
2867 struct held_lock *hlock)
2868{
2869 return 0;
2870}
2871
Peter Zijlstra868a23a2009-02-15 00:25:21 +01002872void lockdep_trace_alloc(gfp_t gfp_mask)
2873{
2874}
2875
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002876#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002877
2878/*
Peter Zijlstra8e182572007-07-19 01:48:54 -07002879 * Mark a lock with a usage bit, and validate the state transition:
2880 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002881static int mark_lock(struct task_struct *curr, struct held_lock *this,
Steven Rostedt0764d232008-05-12 21:20:44 +02002882 enum lock_usage_bit new_bit)
Peter Zijlstra8e182572007-07-19 01:48:54 -07002883{
2884 unsigned int new_mask = 1 << new_bit, ret = 1;
2885
2886 /*
2887 * If already set then do not dirty the cacheline,
2888 * nor do any checks:
2889 */
Dave Jonesf82b2172008-08-11 09:30:23 +02002890 if (likely(hlock_class(this)->usage_mask & new_mask))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002891 return 1;
2892
2893 if (!graph_lock())
2894 return 0;
2895 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03002896 * Make sure we didn't race:
Peter Zijlstra8e182572007-07-19 01:48:54 -07002897 */
Dave Jonesf82b2172008-08-11 09:30:23 +02002898 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07002899 graph_unlock();
2900 return 1;
2901 }
2902
Dave Jonesf82b2172008-08-11 09:30:23 +02002903 hlock_class(this)->usage_mask |= new_mask;
Peter Zijlstra8e182572007-07-19 01:48:54 -07002904
Dave Jonesf82b2172008-08-11 09:30:23 +02002905 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002906 return 0;
2907
2908 switch (new_bit) {
Peter Zijlstra53464172009-01-22 14:15:53 +01002909#define LOCKDEP_STATE(__STATE) \
2910 case LOCK_USED_IN_##__STATE: \
2911 case LOCK_USED_IN_##__STATE##_READ: \
2912 case LOCK_ENABLED_##__STATE: \
2913 case LOCK_ENABLED_##__STATE##_READ:
2914#include "lockdep_states.h"
2915#undef LOCKDEP_STATE
Peter Zijlstra8e182572007-07-19 01:48:54 -07002916 ret = mark_lock_irq(curr, this, new_bit);
2917 if (!ret)
2918 return 0;
2919 break;
2920 case LOCK_USED:
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002921 debug_atomic_dec(nr_unused_locks);
Peter Zijlstra8e182572007-07-19 01:48:54 -07002922 break;
2923 default:
2924 if (!debug_locks_off_graph_unlock())
2925 return 0;
2926 WARN_ON(1);
2927 return 0;
2928 }
2929
2930 graph_unlock();
2931
2932 /*
2933 * We must printk outside of the graph_lock:
2934 */
2935 if (ret == 2) {
2936 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2937 print_lock(this);
2938 print_irqtrace_events(curr);
2939 dump_stack();
2940 }
2941
2942 return ret;
2943}
2944
2945/*
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002946 * Initialize a lock instance's lock-class mapping info:
2947 */
2948void lockdep_init_map(struct lockdep_map *lock, const char *name,
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04002949 struct lock_class_key *key, int subclass)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002950{
Tejun Heof59de892011-07-14 15:19:09 +02002951 memset(lock, 0, sizeof(*lock));
Hitoshi Mitake62016252010-10-05 18:01:51 +09002952
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002953#ifdef CONFIG_LOCK_STAT
2954 lock->cpu = raw_smp_processor_id();
2955#endif
2956
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002957 /*
2958 * Can't be having no nameless bastards around this place!
2959 */
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002960 if (DEBUG_LOCKS_WARN_ON(!name)) {
2961 lock->name = "NULL";
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002962 return;
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002963 }
2964
2965 lock->name = name;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002966
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002967 /*
2968 * No key, no joy, we need to hash something.
2969 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002970 if (DEBUG_LOCKS_WARN_ON(!key))
2971 return;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002972 /*
2973 * Sanity check, the lock-class key must be persistent:
2974 */
2975 if (!static_obj(key)) {
2976 printk("BUG: key %p not in .data!\n", key);
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002977 /*
2978 * What it says above ^^^^^, I suggest you read it.
2979 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002980 DEBUG_LOCKS_WARN_ON(1);
2981 return;
2982 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002983 lock->key = key;
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002984
2985 if (unlikely(!debug_locks))
2986 return;
2987
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04002988 if (subclass)
2989 register_lock_class(lock, subclass, 1);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002990}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002991EXPORT_SYMBOL_GPL(lockdep_init_map);
2992
Peter Zijlstra1704f472010-03-19 01:37:42 +01002993struct lock_class_key __lockdep_no_validate__;
2994
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002995/*
2996 * This gets called for every mutex_lock*()/spin_lock*() operation.
2997 * We maintain the dependency maps and validate the locking attempt:
2998 */
2999static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3000 int trylock, int read, int check, int hardirqs_off,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003001 struct lockdep_map *nest_lock, unsigned long ip,
3002 int references)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003003{
3004 struct task_struct *curr = current;
Ingo Molnard6d897c2006-07-10 04:44:04 -07003005 struct lock_class *class = NULL;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003006 struct held_lock *hlock;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003007 unsigned int depth, id;
3008 int chain_head = 0;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003009 int class_idx;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003010 u64 chain_key;
3011
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003012 if (!prove_locking)
3013 check = 1;
3014
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003015 if (unlikely(!debug_locks))
3016 return 0;
3017
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003018 /*
3019 * Lockdep should run with IRQs disabled, otherwise we could
3020 * get an interrupt which would want to take locks, which would
3021 * end up in lockdep and have you got a head-ache already?
3022 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003023 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3024 return 0;
3025
Peter Zijlstra1704f472010-03-19 01:37:42 +01003026 if (lock->key == &__lockdep_no_validate__)
3027 check = 1;
3028
Hitoshi Mitake62016252010-10-05 18:01:51 +09003029 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3030 class = lock->class_cache[subclass];
Ingo Molnard6d897c2006-07-10 04:44:04 -07003031 /*
Hitoshi Mitake62016252010-10-05 18:01:51 +09003032 * Not cached?
Ingo Molnard6d897c2006-07-10 04:44:04 -07003033 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003034 if (unlikely(!class)) {
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04003035 class = register_lock_class(lock, subclass, 0);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003036 if (!class)
3037 return 0;
3038 }
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02003039 atomic_inc((atomic_t *)&class->ops);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003040 if (very_verbose(class)) {
3041 printk("\nacquire class [%p] %s", class->key, class->name);
3042 if (class->name_version > 1)
3043 printk("#%d", class->name_version);
3044 printk("\n");
3045 dump_stack();
3046 }
3047
3048 /*
3049 * Add the lock to the list of currently held locks.
3050 * (we dont increase the depth just yet, up until the
3051 * dependency checks are done)
3052 */
3053 depth = curr->lockdep_depth;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003054 /*
3055 * Ran out of static storage for our per-task lock stack again have we?
3056 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003057 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3058 return 0;
3059
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003060 class_idx = class - lock_classes + 1;
3061
3062 if (depth) {
3063 hlock = curr->held_locks + depth - 1;
3064 if (hlock->class_idx == class_idx && nest_lock) {
3065 if (hlock->references)
3066 hlock->references++;
3067 else
3068 hlock->references = 2;
3069
3070 return 1;
3071 }
3072 }
3073
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003074 hlock = curr->held_locks + depth;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003075 /*
3076 * Plain impossible, we just registered it and checked it weren't no
3077 * NULL like.. I bet this mushroom I ate was good!
3078 */
Dave Jonesf82b2172008-08-11 09:30:23 +02003079 if (DEBUG_LOCKS_WARN_ON(!class))
3080 return 0;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003081 hlock->class_idx = class_idx;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003082 hlock->acquire_ip = ip;
3083 hlock->instance = lock;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02003084 hlock->nest_lock = nest_lock;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003085 hlock->trylock = trylock;
3086 hlock->read = read;
3087 hlock->check = check;
Dmitry Baryshkov6951b122008-08-18 04:26:37 +04003088 hlock->hardirqs_off = !!hardirqs_off;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003089 hlock->references = references;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003090#ifdef CONFIG_LOCK_STAT
3091 hlock->waittime_stamp = 0;
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003092 hlock->holdtime_stamp = lockstat_clock();
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003093#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003094
Peter Zijlstra8e182572007-07-19 01:48:54 -07003095 if (check == 2 && !mark_irqflags(curr, hlock))
3096 return 0;
3097
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003098 /* mark it as used: */
Jarek Poplawski4ff773bb2007-05-08 00:31:00 -07003099 if (!mark_lock(curr, hlock, LOCK_USED))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003100 return 0;
Peter Zijlstra8e182572007-07-19 01:48:54 -07003101
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003102 /*
Gautham R Shenoy17aacfb2007-10-28 20:47:01 +01003103 * Calculate the chain hash: it's the combined hash of all the
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003104 * lock keys along the dependency chain. We save the hash value
3105 * at every step so that we can get the current hash easily
3106 * after unlock. The chain hash is then used to cache dependency
3107 * results.
3108 *
3109 * The 'key ID' is what is the most compact key value to drive
3110 * the hash, not class->key.
3111 */
3112 id = class - lock_classes;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003113 /*
3114 * Whoops, we did it again.. ran straight out of our static allocation.
3115 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003116 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3117 return 0;
3118
3119 chain_key = curr->curr_chain_key;
3120 if (!depth) {
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003121 /*
3122 * How can we have a chain hash when we ain't got no keys?!
3123 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003124 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3125 return 0;
3126 chain_head = 1;
3127 }
3128
3129 hlock->prev_chain_key = chain_key;
Peter Zijlstra8e182572007-07-19 01:48:54 -07003130 if (separate_irq_context(curr, hlock)) {
3131 chain_key = 0;
3132 chain_head = 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003133 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003134 chain_key = iterate_chain_key(chain_key, id);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003135
Gregory Haskins3aa416b2007-10-11 22:11:11 +02003136 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
Peter Zijlstra8e182572007-07-19 01:48:54 -07003137 return 0;
Jarek Poplawski381a2292007-02-10 01:44:58 -08003138
Gregory Haskins3aa416b2007-10-11 22:11:11 +02003139 curr->curr_chain_key = chain_key;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003140 curr->lockdep_depth++;
3141 check_chain_key(curr);
Jarek Poplawski60e114d2007-02-20 13:58:00 -08003142#ifdef CONFIG_DEBUG_LOCKDEP
3143 if (unlikely(!debug_locks))
3144 return 0;
3145#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003146 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3147 debug_locks_off();
3148 printk("BUG: MAX_LOCK_DEPTH too low!\n");
3149 printk("turning off the locking correctness validator.\n");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +01003150 dump_stack();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003151 return 0;
3152 }
Jarek Poplawski381a2292007-02-10 01:44:58 -08003153
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003154 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3155 max_lockdep_depth = curr->lockdep_depth;
3156
3157 return 1;
3158}
3159
3160static int
3161print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
3162 unsigned long ip)
3163{
3164 if (!debug_locks_off())
3165 return 0;
3166 if (debug_locks_silent)
3167 return 0;
3168
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07003169 printk("\n");
3170 printk("=====================================\n");
3171 printk("[ BUG: bad unlock balance detected! ]\n");
3172 printk("-------------------------------------\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003173 printk("%s/%d is trying to release lock (",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003174 curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003175 print_lockdep_cache(lock);
3176 printk(") at:\n");
3177 print_ip_sym(ip);
3178 printk("but there are no more locks to release!\n");
3179 printk("\nother info that might help us debug this:\n");
3180 lockdep_print_held_locks(curr);
3181
3182 printk("\nstack backtrace:\n");
3183 dump_stack();
3184
3185 return 0;
3186}
3187
3188/*
3189 * Common debugging checks for both nested and non-nested unlock:
3190 */
3191static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3192 unsigned long ip)
3193{
3194 if (unlikely(!debug_locks))
3195 return 0;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003196 /*
3197 * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
3198 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003199 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3200 return 0;
3201
3202 if (curr->lockdep_depth <= 0)
3203 return print_unlock_inbalance_bug(curr, lock, ip);
3204
3205 return 1;
3206}
3207
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003208static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3209{
3210 if (hlock->instance == lock)
3211 return 1;
3212
3213 if (hlock->references) {
Hitoshi Mitake62016252010-10-05 18:01:51 +09003214 struct lock_class *class = lock->class_cache[0];
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003215
3216 if (!class)
3217 class = look_up_lock_class(lock, 0);
3218
Peter Zijlstra80e04012011-08-05 14:26:17 +02003219 /*
3220 * If look_up_lock_class() failed to find a class, we're trying
3221 * to test if we hold a lock that has never yet been acquired.
3222 * Clearly if the lock hasn't been acquired _ever_, we're not
3223 * holding it either, so report failure.
3224 */
3225 if (!class)
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003226 return 0;
3227
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003228 /*
3229 * References, but not a lock we're actually ref-counting?
3230 * State got messed up, follow the sites that change ->references
3231 * and try to make sense of it.
3232 */
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003233 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3234 return 0;
3235
3236 if (hlock->class_idx == class - lock_classes + 1)
3237 return 1;
3238 }
3239
3240 return 0;
3241}
3242
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003243static int
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003244__lock_set_class(struct lockdep_map *lock, const char *name,
3245 struct lock_class_key *key, unsigned int subclass,
3246 unsigned long ip)
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003247{
3248 struct task_struct *curr = current;
3249 struct held_lock *hlock, *prev_hlock;
3250 struct lock_class *class;
3251 unsigned int depth;
3252 int i;
3253
3254 depth = curr->lockdep_depth;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003255 /*
3256 * This function is about (re)setting the class of a held lock,
3257 * yet we're not actually holding any locks. Naughty user!
3258 */
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003259 if (DEBUG_LOCKS_WARN_ON(!depth))
3260 return 0;
3261
3262 prev_hlock = NULL;
3263 for (i = depth-1; i >= 0; i--) {
3264 hlock = curr->held_locks + i;
3265 /*
3266 * We must not cross into another context:
3267 */
3268 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3269 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003270 if (match_held_lock(hlock, lock))
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003271 goto found_it;
3272 prev_hlock = hlock;
3273 }
3274 return print_unlock_inbalance_bug(curr, lock, ip);
3275
3276found_it:
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003277 lockdep_init_map(lock, name, key, 0);
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003278 class = register_lock_class(lock, subclass, 0);
Dave Jonesf82b2172008-08-11 09:30:23 +02003279 hlock->class_idx = class - lock_classes + 1;
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003280
3281 curr->lockdep_depth = i;
3282 curr->curr_chain_key = hlock->prev_chain_key;
3283
3284 for (; i < depth; i++) {
3285 hlock = curr->held_locks + i;
3286 if (!__lock_acquire(hlock->instance,
Dave Jonesf82b2172008-08-11 09:30:23 +02003287 hlock_class(hlock)->subclass, hlock->trylock,
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003288 hlock->read, hlock->check, hlock->hardirqs_off,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003289 hlock->nest_lock, hlock->acquire_ip,
3290 hlock->references))
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003291 return 0;
3292 }
3293
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003294 /*
3295 * I took it apart and put it back together again, except now I have
3296 * these 'spare' parts.. where shall I put them.
3297 */
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003298 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3299 return 0;
3300 return 1;
3301}
3302
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003303/*
3304 * Remove the lock to the list of currently held locks in a
3305 * potentially non-nested (out of order) manner. This is a
3306 * relatively rare operation, as all the unlock APIs default
3307 * to nested mode (which uses lock_release()):
3308 */
3309static int
3310lock_release_non_nested(struct task_struct *curr,
3311 struct lockdep_map *lock, unsigned long ip)
3312{
3313 struct held_lock *hlock, *prev_hlock;
3314 unsigned int depth;
3315 int i;
3316
3317 /*
3318 * Check whether the lock exists in the current stack
3319 * of held locks:
3320 */
3321 depth = curr->lockdep_depth;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003322 /*
3323 * So we're all set to release this lock.. wait what lock? We don't
3324 * own any locks, you've been drinking again?
3325 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003326 if (DEBUG_LOCKS_WARN_ON(!depth))
3327 return 0;
3328
3329 prev_hlock = NULL;
3330 for (i = depth-1; i >= 0; i--) {
3331 hlock = curr->held_locks + i;
3332 /*
3333 * We must not cross into another context:
3334 */
3335 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3336 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003337 if (match_held_lock(hlock, lock))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003338 goto found_it;
3339 prev_hlock = hlock;
3340 }
3341 return print_unlock_inbalance_bug(curr, lock, ip);
3342
3343found_it:
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003344 if (hlock->instance == lock)
3345 lock_release_holdtime(hlock);
3346
3347 if (hlock->references) {
3348 hlock->references--;
3349 if (hlock->references) {
3350 /*
3351 * We had, and after removing one, still have
3352 * references, the current lock stack is still
3353 * valid. We're done!
3354 */
3355 return 1;
3356 }
3357 }
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003358
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003359 /*
3360 * We have the right lock to unlock, 'hlock' points to it.
3361 * Now we remove it from the stack, and add back the other
3362 * entries (if any), recalculating the hash along the way:
3363 */
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003364
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003365 curr->lockdep_depth = i;
3366 curr->curr_chain_key = hlock->prev_chain_key;
3367
3368 for (i++; i < depth; i++) {
3369 hlock = curr->held_locks + i;
3370 if (!__lock_acquire(hlock->instance,
Dave Jonesf82b2172008-08-11 09:30:23 +02003371 hlock_class(hlock)->subclass, hlock->trylock,
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003372 hlock->read, hlock->check, hlock->hardirqs_off,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003373 hlock->nest_lock, hlock->acquire_ip,
3374 hlock->references))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003375 return 0;
3376 }
3377
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003378 /*
3379 * We had N bottles of beer on the wall, we drank one, but now
3380 * there's not N-1 bottles of beer left on the wall...
3381 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003382 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3383 return 0;
3384 return 1;
3385}
3386
3387/*
3388 * Remove the lock to the list of currently held locks - this gets
3389 * called on mutex_unlock()/spin_unlock*() (or on a failed
3390 * mutex_lock_interruptible()). This is done for unlocks that nest
3391 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3392 */
3393static int lock_release_nested(struct task_struct *curr,
3394 struct lockdep_map *lock, unsigned long ip)
3395{
3396 struct held_lock *hlock;
3397 unsigned int depth;
3398
3399 /*
3400 * Pop off the top of the lock stack:
3401 */
3402 depth = curr->lockdep_depth - 1;
3403 hlock = curr->held_locks + depth;
3404
3405 /*
3406 * Is the unlock non-nested:
3407 */
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003408 if (hlock->instance != lock || hlock->references)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003409 return lock_release_non_nested(curr, lock, ip);
3410 curr->lockdep_depth--;
3411
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003412 /*
3413 * No more locks, but somehow we've got hash left over, who left it?
3414 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003415 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3416 return 0;
3417
3418 curr->curr_chain_key = hlock->prev_chain_key;
3419
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003420 lock_release_holdtime(hlock);
3421
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003422#ifdef CONFIG_DEBUG_LOCKDEP
3423 hlock->prev_chain_key = 0;
Dave Jonesf82b2172008-08-11 09:30:23 +02003424 hlock->class_idx = 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003425 hlock->acquire_ip = 0;
3426 hlock->irq_context = 0;
3427#endif
3428 return 1;
3429}
3430
3431/*
3432 * Remove the lock to the list of currently held locks - this gets
3433 * called on mutex_unlock()/spin_unlock*() (or on a failed
3434 * mutex_lock_interruptible()). This is done for unlocks that nest
3435 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3436 */
3437static void
3438__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3439{
3440 struct task_struct *curr = current;
3441
3442 if (!check_unlock(curr, lock, ip))
3443 return;
3444
3445 if (nested) {
3446 if (!lock_release_nested(curr, lock, ip))
3447 return;
3448 } else {
3449 if (!lock_release_non_nested(curr, lock, ip))
3450 return;
3451 }
3452
3453 check_chain_key(curr);
3454}
3455
Peter Zijlstraf607c662009-07-20 19:16:29 +02003456static int __lock_is_held(struct lockdep_map *lock)
3457{
3458 struct task_struct *curr = current;
3459 int i;
3460
3461 for (i = 0; i < curr->lockdep_depth; i++) {
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003462 struct held_lock *hlock = curr->held_locks + i;
3463
3464 if (match_held_lock(hlock, lock))
Peter Zijlstraf607c662009-07-20 19:16:29 +02003465 return 1;
3466 }
3467
3468 return 0;
3469}
3470
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003471/*
3472 * Check whether we follow the irq-flags state precisely:
3473 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02003474static void check_flags(unsigned long flags)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003475{
Ingo Molnar992860e2008-07-14 10:28:38 +02003476#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3477 defined(CONFIG_TRACE_IRQFLAGS)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003478 if (!debug_locks)
3479 return;
3480
Ingo Molnar5f9fa8a2007-12-07 19:02:47 +01003481 if (irqs_disabled_flags(flags)) {
3482 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3483 printk("possible reason: unannotated irqs-off.\n");
3484 }
3485 } else {
3486 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3487 printk("possible reason: unannotated irqs-on.\n");
3488 }
3489 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003490
3491 /*
3492 * We dont accurately track softirq state in e.g.
3493 * hardirq contexts (such as on 4KSTACKS), so only
3494 * check if not in hardirq contexts:
3495 */
3496 if (!hardirq_count()) {
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003497 if (softirq_count()) {
3498 /* like the above, but with softirqs */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003499 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003500 } else {
3501 /* lick the above, does it taste good? */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003502 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003503 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003504 }
3505
3506 if (!debug_locks)
3507 print_irqtrace_events(current);
3508#endif
3509}
3510
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003511void lock_set_class(struct lockdep_map *lock, const char *name,
3512 struct lock_class_key *key, unsigned int subclass,
3513 unsigned long ip)
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003514{
3515 unsigned long flags;
3516
3517 if (unlikely(current->lockdep_recursion))
3518 return;
3519
3520 raw_local_irq_save(flags);
3521 current->lockdep_recursion = 1;
3522 check_flags(flags);
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003523 if (__lock_set_class(lock, name, key, subclass, ip))
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003524 check_chain_key(current);
3525 current->lockdep_recursion = 0;
3526 raw_local_irq_restore(flags);
3527}
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003528EXPORT_SYMBOL_GPL(lock_set_class);
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003529
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003530/*
3531 * We are not always called with irqs disabled - do that here,
3532 * and also avoid lockdep recursion:
3533 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02003534void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02003535 int trylock, int read, int check,
3536 struct lockdep_map *nest_lock, unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003537{
3538 unsigned long flags;
3539
3540 if (unlikely(current->lockdep_recursion))
3541 return;
3542
3543 raw_local_irq_save(flags);
3544 check_flags(flags);
3545
3546 current->lockdep_recursion = 1;
Frederic Weisbeckerdb2c4c72010-02-02 23:34:40 +01003547 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003548 __lock_acquire(lock, subclass, trylock, read, check,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003549 irqs_disabled_flags(flags), nest_lock, ip, 0);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003550 current->lockdep_recursion = 0;
3551 raw_local_irq_restore(flags);
3552}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003553EXPORT_SYMBOL_GPL(lock_acquire);
3554
Steven Rostedt1d09daa2008-05-12 21:20:55 +02003555void lock_release(struct lockdep_map *lock, int nested,
Steven Rostedt0764d232008-05-12 21:20:44 +02003556 unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003557{
3558 unsigned long flags;
3559
3560 if (unlikely(current->lockdep_recursion))
3561 return;
3562
3563 raw_local_irq_save(flags);
3564 check_flags(flags);
3565 current->lockdep_recursion = 1;
Frederic Weisbecker93135432010-05-08 06:24:25 +02003566 trace_lock_release(lock, ip);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003567 __lock_release(lock, nested, ip);
3568 current->lockdep_recursion = 0;
3569 raw_local_irq_restore(flags);
3570}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003571EXPORT_SYMBOL_GPL(lock_release);
3572
Peter Zijlstraf607c662009-07-20 19:16:29 +02003573int lock_is_held(struct lockdep_map *lock)
3574{
3575 unsigned long flags;
3576 int ret = 0;
3577
3578 if (unlikely(current->lockdep_recursion))
Peter Zijlstraf2513cd2011-06-06 12:32:43 +02003579 return 1; /* avoid false negative lockdep_assert_held() */
Peter Zijlstraf607c662009-07-20 19:16:29 +02003580
3581 raw_local_irq_save(flags);
3582 check_flags(flags);
3583
3584 current->lockdep_recursion = 1;
3585 ret = __lock_is_held(lock);
3586 current->lockdep_recursion = 0;
3587 raw_local_irq_restore(flags);
3588
3589 return ret;
3590}
3591EXPORT_SYMBOL_GPL(lock_is_held);
3592
Nick Piggincf40bd12009-01-21 08:12:39 +01003593void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3594{
3595 current->lockdep_reclaim_gfp = gfp_mask;
3596}
3597
3598void lockdep_clear_current_reclaim_state(void)
3599{
3600 current->lockdep_reclaim_gfp = 0;
3601}
3602
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003603#ifdef CONFIG_LOCK_STAT
3604static int
3605print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3606 unsigned long ip)
3607{
3608 if (!debug_locks_off())
3609 return 0;
3610 if (debug_locks_silent)
3611 return 0;
3612
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07003613 printk("\n");
3614 printk("=================================\n");
3615 printk("[ BUG: bad contention detected! ]\n");
3616 printk("---------------------------------\n");
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003617 printk("%s/%d is trying to contend lock (",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003618 curr->comm, task_pid_nr(curr));
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003619 print_lockdep_cache(lock);
3620 printk(") at:\n");
3621 print_ip_sym(ip);
3622 printk("but there are no locks held!\n");
3623 printk("\nother info that might help us debug this:\n");
3624 lockdep_print_held_locks(curr);
3625
3626 printk("\nstack backtrace:\n");
3627 dump_stack();
3628
3629 return 0;
3630}
3631
3632static void
3633__lock_contended(struct lockdep_map *lock, unsigned long ip)
3634{
3635 struct task_struct *curr = current;
3636 struct held_lock *hlock, *prev_hlock;
3637 struct lock_class_stats *stats;
3638 unsigned int depth;
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003639 int i, contention_point, contending_point;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003640
3641 depth = curr->lockdep_depth;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003642 /*
3643 * Whee, we contended on this lock, except it seems we're not
3644 * actually trying to acquire anything much at all..
3645 */
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003646 if (DEBUG_LOCKS_WARN_ON(!depth))
3647 return;
3648
3649 prev_hlock = NULL;
3650 for (i = depth-1; i >= 0; i--) {
3651 hlock = curr->held_locks + i;
3652 /*
3653 * We must not cross into another context:
3654 */
3655 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3656 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003657 if (match_held_lock(hlock, lock))
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003658 goto found_it;
3659 prev_hlock = hlock;
3660 }
3661 print_lock_contention_bug(curr, lock, ip);
3662 return;
3663
3664found_it:
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003665 if (hlock->instance != lock)
3666 return;
3667
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003668 hlock->waittime_stamp = lockstat_clock();
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003669
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003670 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3671 contending_point = lock_point(hlock_class(hlock)->contending_point,
3672 lock->ip);
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003673
Dave Jonesf82b2172008-08-11 09:30:23 +02003674 stats = get_lock_stats(hlock_class(hlock));
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003675 if (contention_point < LOCKSTAT_POINTS)
3676 stats->contention_point[contention_point]++;
3677 if (contending_point < LOCKSTAT_POINTS)
3678 stats->contending_point[contending_point]++;
Peter Zijlstra96645672007-07-19 01:49:00 -07003679 if (lock->cpu != smp_processor_id())
3680 stats->bounces[bounce_contended + !!hlock->read]++;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003681 put_lock_stats(stats);
3682}
3683
3684static void
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003685__lock_acquired(struct lockdep_map *lock, unsigned long ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003686{
3687 struct task_struct *curr = current;
3688 struct held_lock *hlock, *prev_hlock;
3689 struct lock_class_stats *stats;
3690 unsigned int depth;
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003691 u64 now, waittime = 0;
Peter Zijlstra96645672007-07-19 01:49:00 -07003692 int i, cpu;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003693
3694 depth = curr->lockdep_depth;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003695 /*
3696 * Yay, we acquired ownership of this lock we didn't try to
3697 * acquire, how the heck did that happen?
3698 */
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003699 if (DEBUG_LOCKS_WARN_ON(!depth))
3700 return;
3701
3702 prev_hlock = NULL;
3703 for (i = depth-1; i >= 0; i--) {
3704 hlock = curr->held_locks + i;
3705 /*
3706 * We must not cross into another context:
3707 */
3708 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3709 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003710 if (match_held_lock(hlock, lock))
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003711 goto found_it;
3712 prev_hlock = hlock;
3713 }
3714 print_lock_contention_bug(curr, lock, _RET_IP_);
3715 return;
3716
3717found_it:
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003718 if (hlock->instance != lock)
3719 return;
3720
Peter Zijlstra96645672007-07-19 01:49:00 -07003721 cpu = smp_processor_id();
3722 if (hlock->waittime_stamp) {
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003723 now = lockstat_clock();
Peter Zijlstra96645672007-07-19 01:49:00 -07003724 waittime = now - hlock->waittime_stamp;
3725 hlock->holdtime_stamp = now;
3726 }
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003727
Frederic Weisbecker883a2a32010-05-08 06:16:11 +02003728 trace_lock_acquired(lock, ip);
Frederic Weisbecker20625012009-04-06 01:49:33 +02003729
Dave Jonesf82b2172008-08-11 09:30:23 +02003730 stats = get_lock_stats(hlock_class(hlock));
Peter Zijlstra96645672007-07-19 01:49:00 -07003731 if (waittime) {
3732 if (hlock->read)
3733 lock_time_inc(&stats->read_waittime, waittime);
3734 else
3735 lock_time_inc(&stats->write_waittime, waittime);
3736 }
3737 if (lock->cpu != cpu)
3738 stats->bounces[bounce_acquired + !!hlock->read]++;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003739 put_lock_stats(stats);
Peter Zijlstra96645672007-07-19 01:49:00 -07003740
3741 lock->cpu = cpu;
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003742 lock->ip = ip;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003743}
3744
3745void lock_contended(struct lockdep_map *lock, unsigned long ip)
3746{
3747 unsigned long flags;
3748
3749 if (unlikely(!lock_stat))
3750 return;
3751
3752 if (unlikely(current->lockdep_recursion))
3753 return;
3754
3755 raw_local_irq_save(flags);
3756 check_flags(flags);
3757 current->lockdep_recursion = 1;
Frederic Weisbeckerdb2c4c72010-02-02 23:34:40 +01003758 trace_lock_contended(lock, ip);
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003759 __lock_contended(lock, ip);
3760 current->lockdep_recursion = 0;
3761 raw_local_irq_restore(flags);
3762}
3763EXPORT_SYMBOL_GPL(lock_contended);
3764
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003765void lock_acquired(struct lockdep_map *lock, unsigned long ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003766{
3767 unsigned long flags;
3768
3769 if (unlikely(!lock_stat))
3770 return;
3771
3772 if (unlikely(current->lockdep_recursion))
3773 return;
3774
3775 raw_local_irq_save(flags);
3776 check_flags(flags);
3777 current->lockdep_recursion = 1;
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003778 __lock_acquired(lock, ip);
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003779 current->lockdep_recursion = 0;
3780 raw_local_irq_restore(flags);
3781}
3782EXPORT_SYMBOL_GPL(lock_acquired);
3783#endif
3784
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003785/*
3786 * Used by the testsuite, sanitize the validator state
3787 * after a simulated failure:
3788 */
3789
3790void lockdep_reset(void)
3791{
3792 unsigned long flags;
Ingo Molnar23d95a02006-12-13 00:34:40 -08003793 int i;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003794
3795 raw_local_irq_save(flags);
3796 current->curr_chain_key = 0;
3797 current->lockdep_depth = 0;
3798 current->lockdep_recursion = 0;
3799 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3800 nr_hardirq_chains = 0;
3801 nr_softirq_chains = 0;
3802 nr_process_chains = 0;
3803 debug_locks = 1;
Ingo Molnar23d95a02006-12-13 00:34:40 -08003804 for (i = 0; i < CHAINHASH_SIZE; i++)
3805 INIT_LIST_HEAD(chainhash_table + i);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003806 raw_local_irq_restore(flags);
3807}
3808
3809static void zap_class(struct lock_class *class)
3810{
3811 int i;
3812
3813 /*
3814 * Remove all dependencies this lock is
3815 * involved in:
3816 */
3817 for (i = 0; i < nr_list_entries; i++) {
3818 if (list_entries[i].class == class)
3819 list_del_rcu(&list_entries[i].entry);
3820 }
3821 /*
3822 * Unhash the class and remove it from the all_lock_classes list:
3823 */
3824 list_del_rcu(&class->hash_entry);
3825 list_del_rcu(&class->lock_entry);
3826
Rabin Vincent8bfe0292008-08-11 09:30:26 +02003827 class->key = NULL;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003828}
3829
Arjan van de Venfabe8742008-01-24 07:00:45 +01003830static inline int within(const void *addr, void *start, unsigned long size)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003831{
3832 return addr >= start && addr < start + size;
3833}
3834
3835void lockdep_free_key_range(void *start, unsigned long size)
3836{
3837 struct lock_class *class, *next;
3838 struct list_head *head;
3839 unsigned long flags;
3840 int i;
Nick Piggin5a26db52008-01-16 09:51:58 +01003841 int locked;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003842
3843 raw_local_irq_save(flags);
Nick Piggin5a26db52008-01-16 09:51:58 +01003844 locked = graph_lock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003845
3846 /*
3847 * Unhash all classes that were created by this module:
3848 */
3849 for (i = 0; i < CLASSHASH_SIZE; i++) {
3850 head = classhash_table + i;
3851 if (list_empty(head))
3852 continue;
Arjan van de Venfabe8742008-01-24 07:00:45 +01003853 list_for_each_entry_safe(class, next, head, hash_entry) {
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003854 if (within(class->key, start, size))
3855 zap_class(class);
Arjan van de Venfabe8742008-01-24 07:00:45 +01003856 else if (within(class->name, start, size))
3857 zap_class(class);
3858 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003859 }
3860
Nick Piggin5a26db52008-01-16 09:51:58 +01003861 if (locked)
3862 graph_unlock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003863 raw_local_irq_restore(flags);
3864}
3865
3866void lockdep_reset_lock(struct lockdep_map *lock)
3867{
Ingo Molnard6d897c2006-07-10 04:44:04 -07003868 struct lock_class *class, *next;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003869 struct list_head *head;
3870 unsigned long flags;
3871 int i, j;
Nick Piggin5a26db52008-01-16 09:51:58 +01003872 int locked;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003873
3874 raw_local_irq_save(flags);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003875
3876 /*
Ingo Molnard6d897c2006-07-10 04:44:04 -07003877 * Remove all classes this lock might have:
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003878 */
Ingo Molnard6d897c2006-07-10 04:44:04 -07003879 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3880 /*
3881 * If the class exists we look it up and zap it:
3882 */
3883 class = look_up_lock_class(lock, j);
3884 if (class)
3885 zap_class(class);
3886 }
3887 /*
3888 * Debug check: in the end all mapped classes should
3889 * be gone.
3890 */
Nick Piggin5a26db52008-01-16 09:51:58 +01003891 locked = graph_lock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003892 for (i = 0; i < CLASSHASH_SIZE; i++) {
3893 head = classhash_table + i;
3894 if (list_empty(head))
3895 continue;
3896 list_for_each_entry_safe(class, next, head, hash_entry) {
Hitoshi Mitake62016252010-10-05 18:01:51 +09003897 int match = 0;
3898
3899 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3900 match |= class == lock->class_cache[j];
3901
3902 if (unlikely(match)) {
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003903 if (debug_locks_off_graph_unlock()) {
3904 /*
3905 * We all just reset everything, how did it match?
3906 */
Ingo Molnar74c383f2006-12-13 00:34:43 -08003907 WARN_ON(1);
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003908 }
Ingo Molnard6d897c2006-07-10 04:44:04 -07003909 goto out_restore;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003910 }
3911 }
3912 }
Nick Piggin5a26db52008-01-16 09:51:58 +01003913 if (locked)
3914 graph_unlock();
Ingo Molnard6d897c2006-07-10 04:44:04 -07003915
3916out_restore:
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003917 raw_local_irq_restore(flags);
3918}
3919
Sam Ravnborg14999932007-02-28 20:12:31 -08003920void lockdep_init(void)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003921{
3922 int i;
3923
3924 /*
3925 * Some architectures have their own start_kernel()
3926 * code which calls lockdep_init(), while we also
3927 * call lockdep_init() from the start_kernel() itself,
3928 * and we want to initialize the hashes only once:
3929 */
3930 if (lockdep_initialized)
3931 return;
3932
3933 for (i = 0; i < CLASSHASH_SIZE; i++)
3934 INIT_LIST_HEAD(classhash_table + i);
3935
3936 for (i = 0; i < CHAINHASH_SIZE; i++)
3937 INIT_LIST_HEAD(chainhash_table + i);
3938
3939 lockdep_initialized = 1;
3940}
3941
3942void __init lockdep_info(void)
3943{
3944 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3945
Li Zefanb0788ca2008-11-21 15:57:32 +08003946 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003947 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3948 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
Li Zefanb0788ca2008-11-21 15:57:32 +08003949 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003950 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3951 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3952 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3953
3954 printk(" memory used by lock dependency info: %lu kB\n",
3955 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3956 sizeof(struct list_head) * CLASSHASH_SIZE +
3957 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3958 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
Ming Lei90629202009-08-02 21:43:36 +08003959 sizeof(struct list_head) * CHAINHASH_SIZE
Ming Lei4dd861d2009-07-16 15:44:29 +02003960#ifdef CONFIG_PROVE_LOCKING
Ming Leie351b662009-07-22 22:48:09 +08003961 + sizeof(struct circular_queue)
Ming Lei4dd861d2009-07-16 15:44:29 +02003962#endif
Ming Lei90629202009-08-02 21:43:36 +08003963 ) / 1024
Ming Lei4dd861d2009-07-16 15:44:29 +02003964 );
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003965
3966 printk(" per task-struct memory footprint: %lu bytes\n",
3967 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3968
3969#ifdef CONFIG_DEBUG_LOCKDEP
Johannes Bergc71063c2007-07-19 01:49:02 -07003970 if (lockdep_init_error) {
3971 printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3972 printk("Call stack leading to lockdep invocation was:\n");
3973 print_stack_trace(&lockdep_init_trace, 0);
3974 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003975#endif
3976}
3977
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003978static void
3979print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
Arjan van de Ven55794a42006-07-10 04:44:03 -07003980 const void *mem_to, struct held_lock *hlock)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003981{
3982 if (!debug_locks_off())
3983 return;
3984 if (debug_locks_silent)
3985 return;
3986
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07003987 printk("\n");
3988 printk("=========================\n");
3989 printk("[ BUG: held lock freed! ]\n");
3990 printk("-------------------------\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003991 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003992 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
Arjan van de Ven55794a42006-07-10 04:44:03 -07003993 print_lock(hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003994 lockdep_print_held_locks(curr);
3995
3996 printk("\nstack backtrace:\n");
3997 dump_stack();
3998}
3999
Oleg Nesterov54561782007-12-05 15:46:09 +01004000static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4001 const void* lock_from, unsigned long lock_len)
4002{
4003 return lock_from + lock_len <= mem_from ||
4004 mem_from + mem_len <= lock_from;
4005}
4006
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004007/*
4008 * Called when kernel memory is freed (or unmapped), or if a lock
4009 * is destroyed or reinitialized - this code checks whether there is
4010 * any held lock in the memory range of <from> to <to>:
4011 */
4012void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4013{
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004014 struct task_struct *curr = current;
4015 struct held_lock *hlock;
4016 unsigned long flags;
4017 int i;
4018
4019 if (unlikely(!debug_locks))
4020 return;
4021
4022 local_irq_save(flags);
4023 for (i = 0; i < curr->lockdep_depth; i++) {
4024 hlock = curr->held_locks + i;
4025
Oleg Nesterov54561782007-12-05 15:46:09 +01004026 if (not_in_range(mem_from, mem_len, hlock->instance,
4027 sizeof(*hlock->instance)))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004028 continue;
4029
Oleg Nesterov54561782007-12-05 15:46:09 +01004030 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004031 break;
4032 }
4033 local_irq_restore(flags);
4034}
Peter Zijlstraed075362006-12-06 20:35:24 -08004035EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004036
4037static void print_held_locks_bug(struct task_struct *curr)
4038{
4039 if (!debug_locks_off())
4040 return;
4041 if (debug_locks_silent)
4042 return;
4043
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004044 printk("\n");
4045 printk("=====================================\n");
4046 printk("[ BUG: lock held at task exit time! ]\n");
4047 printk("-------------------------------------\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004048 printk("%s/%d is exiting with locks still held!\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07004049 curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004050 lockdep_print_held_locks(curr);
4051
4052 printk("\nstack backtrace:\n");
4053 dump_stack();
4054}
4055
4056void debug_check_no_locks_held(struct task_struct *task)
4057{
4058 if (unlikely(task->lockdep_depth > 0))
4059 print_held_locks_bug(task);
4060}
4061
4062void debug_show_all_locks(void)
4063{
4064 struct task_struct *g, *p;
4065 int count = 10;
4066 int unlock = 1;
4067
Jarek Poplawski9c35dd72007-03-22 00:11:28 -08004068 if (unlikely(!debug_locks)) {
4069 printk("INFO: lockdep is turned off.\n");
4070 return;
4071 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004072 printk("\nShowing all locks held in the system:\n");
4073
4074 /*
4075 * Here we try to get the tasklist_lock as hard as possible,
4076 * if not successful after 2 seconds we ignore it (but keep
4077 * trying). This is to enable a debug printout even if a
4078 * tasklist_lock-holding task deadlocks or crashes.
4079 */
4080retry:
4081 if (!read_trylock(&tasklist_lock)) {
4082 if (count == 10)
4083 printk("hm, tasklist_lock locked, retrying... ");
4084 if (count) {
4085 count--;
4086 printk(" #%d", 10-count);
4087 mdelay(200);
4088 goto retry;
4089 }
4090 printk(" ignoring it.\n");
4091 unlock = 0;
qinghuang feng46fec7a2008-10-28 17:24:28 +08004092 } else {
4093 if (count != 10)
4094 printk(KERN_CONT " locked it.\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004095 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004096
4097 do_each_thread(g, p) {
Ingo Molnar85684872007-12-05 15:46:09 +01004098 /*
4099 * It's not reliable to print a task's held locks
4100 * if it's not sleeping (or if it's not the current
4101 * task):
4102 */
4103 if (p->state == TASK_RUNNING && p != current)
4104 continue;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004105 if (p->lockdep_depth)
4106 lockdep_print_held_locks(p);
4107 if (!unlock)
4108 if (read_trylock(&tasklist_lock))
4109 unlock = 1;
4110 } while_each_thread(g, p);
4111
4112 printk("\n");
4113 printk("=============================================\n\n");
4114
4115 if (unlock)
4116 read_unlock(&tasklist_lock);
4117}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004118EXPORT_SYMBOL_GPL(debug_show_all_locks);
4119
Ingo Molnar82a1fcb2008-01-25 21:08:02 +01004120/*
4121 * Careful: only use this function if you are sure that
4122 * the task cannot run in parallel!
4123 */
John Kacurf1b499f2010-08-05 17:10:53 +02004124void debug_show_held_locks(struct task_struct *task)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004125{
Jarek Poplawski9c35dd72007-03-22 00:11:28 -08004126 if (unlikely(!debug_locks)) {
4127 printk("INFO: lockdep is turned off.\n");
4128 return;
4129 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004130 lockdep_print_held_locks(task);
4131}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004132EXPORT_SYMBOL_GPL(debug_show_held_locks);
Peter Zijlstrab351d162007-10-11 22:11:12 +02004133
4134void lockdep_sys_exit(void)
4135{
4136 struct task_struct *curr = current;
4137
4138 if (unlikely(curr->lockdep_depth)) {
4139 if (!debug_locks_off())
4140 return;
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004141 printk("\n");
4142 printk("================================================\n");
4143 printk("[ BUG: lock held when returning to user space! ]\n");
4144 printk("------------------------------------------------\n");
Peter Zijlstrab351d162007-10-11 22:11:12 +02004145 printk("%s/%d is leaving the kernel with locks still held!\n",
4146 curr->comm, curr->pid);
4147 lockdep_print_held_locks(curr);
4148 }
4149}
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004150
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004151void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004152{
4153 struct task_struct *curr = current;
4154
Lai Jiangshan2b3fc352010-04-20 16:23:07 +08004155#ifndef CONFIG_PROVE_RCU_REPEATEDLY
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004156 if (!debug_locks_off())
4157 return;
Lai Jiangshan2b3fc352010-04-20 16:23:07 +08004158#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4159 /* Note: the following can be executed concurrently, so be careful. */
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004160 printk("\n");
4161 printk("===============================\n");
4162 printk("[ INFO: suspicious RCU usage. ]\n");
4163 printk("-------------------------------\n");
4164 printk("%s:%d %s!\n", file, line, s);
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004165 printk("\nother info that might help us debug this:\n\n");
Paul E. McKenneycc5b83a2010-03-03 07:46:59 -08004166 printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004167 lockdep_print_held_locks(curr);
4168 printk("\nstack backtrace:\n");
4169 dump_stack();
4170}
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004171EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);