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Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001/*
2 * kernel/lockdep.c
3 *
4 * Runtime locking correctness validator
5 *
6 * Started by Ingo Molnar:
7 *
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -07008 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070010 *
11 * this code maps all the lock dependencies as they occur in a live kernel
12 * and will warn about the following classes of locking bugs:
13 *
14 * - lock inversion scenarios
15 * - circular lock dependencies
16 * - hardirq/softirq safe/unsafe locking bugs
17 *
18 * Bugs are reported even if the current locking scenario does not cause
19 * any deadlock at this point.
20 *
21 * I.e. if anytime in the past two locks were taken in a different order,
22 * even if it happened for another task, even if those were different
23 * locks (but of the same class as this lock), this code will detect it.
24 *
25 * Thanks to Arjan van de Ven for coming up with the initial idea of
26 * mapping lock dependencies runtime.
27 */
Steven Rostedta5e25882008-12-02 15:34:05 -050028#define DISABLE_BRANCH_PROFILING
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070029#include <linux/mutex.h>
30#include <linux/sched.h>
31#include <linux/delay.h>
32#include <linux/module.h>
33#include <linux/proc_fs.h>
34#include <linux/seq_file.h>
35#include <linux/spinlock.h>
36#include <linux/kallsyms.h>
37#include <linux/interrupt.h>
38#include <linux/stacktrace.h>
39#include <linux/debug_locks.h>
40#include <linux/irqflags.h>
Dave Jones99de0552006-09-29 02:00:10 -070041#include <linux/utsname.h>
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -070042#include <linux/hash.h>
Steven Rostedt81d68a92008-05-12 21:20:42 +020043#include <linux/ftrace.h>
Peter Zijlstrab4b136f2009-01-29 14:50:36 +010044#include <linux/stringify.h>
Ming Leid588e462009-07-16 15:44:29 +020045#include <linux/bitops.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090046#include <linux/gfp.h>
Yong Zhangd3d03d42011-11-09 16:04:51 +080047#include <linux/kmemcheck.h>
Peter Zijlstraaf012962009-07-16 15:44:29 +020048
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070049#include <asm/sections.h>
50
51#include "lockdep_internals.h"
52
Steven Rostedta8d154b2009-04-10 09:36:00 -040053#define CREATE_TRACE_POINTS
Frederic Weisbecker67178762009-11-13 10:06:34 +010054#include <trace/events/lock.h>
Steven Rostedta8d154b2009-04-10 09:36:00 -040055
Peter Zijlstraf20786f2007-07-19 01:48:56 -070056#ifdef CONFIG_PROVE_LOCKING
57int prove_locking = 1;
58module_param(prove_locking, int, 0644);
59#else
60#define prove_locking 0
61#endif
62
63#ifdef CONFIG_LOCK_STAT
64int lock_stat = 1;
65module_param(lock_stat, int, 0644);
66#else
67#define lock_stat 0
68#endif
69
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070070/*
Ingo Molnar74c383f2006-12-13 00:34:43 -080071 * lockdep_lock: protects the lockdep graph, the hashes and the
72 * class/list/hash allocators.
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070073 *
74 * This is one of the rare exceptions where it's justified
75 * to use a raw spinlock - we really dont want the spinlock
Ingo Molnar74c383f2006-12-13 00:34:43 -080076 * code to recurse back into the lockdep code...
Ingo Molnarfbb9ce952006-07-03 00:24:50 -070077 */
Thomas Gleixneredc35bd2009-12-03 12:38:57 +010078static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
Ingo Molnar74c383f2006-12-13 00:34:43 -080079
80static int graph_lock(void)
81{
Thomas Gleixner0199c4e2009-12-02 20:01:25 +010082 arch_spin_lock(&lockdep_lock);
Ingo Molnar74c383f2006-12-13 00:34:43 -080083 /*
84 * Make sure that if another CPU detected a bug while
85 * walking the graph we dont change it (while the other
86 * CPU is busy printing out stuff with the graph lock
87 * dropped already)
88 */
89 if (!debug_locks) {
Thomas Gleixner0199c4e2009-12-02 20:01:25 +010090 arch_spin_unlock(&lockdep_lock);
Ingo Molnar74c383f2006-12-13 00:34:43 -080091 return 0;
92 }
Steven Rostedtbb065af2008-05-12 21:21:00 +020093 /* prevent any recursions within lockdep from causing deadlocks */
94 current->lockdep_recursion++;
Ingo Molnar74c383f2006-12-13 00:34:43 -080095 return 1;
96}
97
98static inline int graph_unlock(void)
99{
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200100 if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
101 /*
102 * The lockdep graph lock isn't locked while we expect it to
103 * be, we're confused now, bye!
104 */
Jarek Poplawski381a2292007-02-10 01:44:58 -0800105 return DEBUG_LOCKS_WARN_ON(1);
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200106 }
Jarek Poplawski381a2292007-02-10 01:44:58 -0800107
Steven Rostedtbb065af2008-05-12 21:21:00 +0200108 current->lockdep_recursion--;
Thomas Gleixner0199c4e2009-12-02 20:01:25 +0100109 arch_spin_unlock(&lockdep_lock);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800110 return 0;
111}
112
113/*
114 * Turn lock debugging off and return with 0 if it was off already,
115 * and also release the graph lock:
116 */
117static inline int debug_locks_off_graph_unlock(void)
118{
119 int ret = debug_locks_off();
120
Thomas Gleixner0199c4e2009-12-02 20:01:25 +0100121 arch_spin_unlock(&lockdep_lock);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800122
123 return ret;
124}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700125
126static int lockdep_initialized;
127
128unsigned long nr_list_entries;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200129static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700130
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700131/*
132 * All data structures here are protected by the global debug_lock.
133 *
134 * Mutex key structs only get allocated, once during bootup, and never
135 * get freed - this significantly simplifies the debugging code.
136 */
137unsigned long nr_lock_classes;
138static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
139
Dave Jonesf82b2172008-08-11 09:30:23 +0200140static inline struct lock_class *hlock_class(struct held_lock *hlock)
141{
142 if (!hlock->class_idx) {
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200143 /*
144 * Someone passed in garbage, we give up.
145 */
Dave Jonesf82b2172008-08-11 09:30:23 +0200146 DEBUG_LOCKS_WARN_ON(1);
147 return NULL;
148 }
149 return lock_classes + hlock->class_idx - 1;
150}
151
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700152#ifdef CONFIG_LOCK_STAT
Tejun Heo1871e522009-10-29 22:34:13 +0900153static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
154 cpu_lock_stats);
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700155
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200156static inline u64 lockstat_clock(void)
157{
Peter Zijlstrac6763292010-05-25 10:48:51 +0200158 return local_clock();
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200159}
160
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200161static int lock_point(unsigned long points[], unsigned long ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700162{
163 int i;
164
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200165 for (i = 0; i < LOCKSTAT_POINTS; i++) {
166 if (points[i] == 0) {
167 points[i] = ip;
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700168 break;
169 }
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200170 if (points[i] == ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700171 break;
172 }
173
174 return i;
175}
176
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200177static void lock_time_inc(struct lock_time *lt, u64 time)
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700178{
179 if (time > lt->max)
180 lt->max = time;
181
Frank Rowand109d71c2009-11-19 13:42:06 -0800182 if (time < lt->min || !lt->nr)
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700183 lt->min = time;
184
185 lt->total += time;
186 lt->nr++;
187}
188
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700189static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
190{
Frank Rowand109d71c2009-11-19 13:42:06 -0800191 if (!src->nr)
192 return;
193
194 if (src->max > dst->max)
195 dst->max = src->max;
196
197 if (src->min < dst->min || !dst->nr)
198 dst->min = src->min;
199
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700200 dst->total += src->total;
201 dst->nr += src->nr;
202}
203
204struct lock_class_stats lock_stats(struct lock_class *class)
205{
206 struct lock_class_stats stats;
207 int cpu, i;
208
209 memset(&stats, 0, sizeof(struct lock_class_stats));
210 for_each_possible_cpu(cpu) {
211 struct lock_class_stats *pcs =
Tejun Heo1871e522009-10-29 22:34:13 +0900212 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700213
214 for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
215 stats.contention_point[i] += pcs->contention_point[i];
216
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200217 for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
218 stats.contending_point[i] += pcs->contending_point[i];
219
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700220 lock_time_add(&pcs->read_waittime, &stats.read_waittime);
221 lock_time_add(&pcs->write_waittime, &stats.write_waittime);
222
223 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
224 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
Peter Zijlstra96645672007-07-19 01:49:00 -0700225
226 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
227 stats.bounces[i] += pcs->bounces[i];
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700228 }
229
230 return stats;
231}
232
233void clear_lock_stats(struct lock_class *class)
234{
235 int cpu;
236
237 for_each_possible_cpu(cpu) {
238 struct lock_class_stats *cpu_stats =
Tejun Heo1871e522009-10-29 22:34:13 +0900239 &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700240
241 memset(cpu_stats, 0, sizeof(struct lock_class_stats));
242 }
243 memset(class->contention_point, 0, sizeof(class->contention_point));
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +0200244 memset(class->contending_point, 0, sizeof(class->contending_point));
Peter Zijlstrac46261d2007-07-19 01:48:57 -0700245}
246
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700247static struct lock_class_stats *get_lock_stats(struct lock_class *class)
248{
Tejun Heo1871e522009-10-29 22:34:13 +0900249 return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700250}
251
252static void put_lock_stats(struct lock_class_stats *stats)
253{
Tejun Heo1871e522009-10-29 22:34:13 +0900254 put_cpu_var(cpu_lock_stats);
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700255}
256
257static void lock_release_holdtime(struct held_lock *hlock)
258{
259 struct lock_class_stats *stats;
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200260 u64 holdtime;
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700261
262 if (!lock_stat)
263 return;
264
Peter Zijlstra3365e7792009-10-09 10:12:41 +0200265 holdtime = lockstat_clock() - hlock->holdtime_stamp;
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700266
Dave Jonesf82b2172008-08-11 09:30:23 +0200267 stats = get_lock_stats(hlock_class(hlock));
Peter Zijlstraf20786f2007-07-19 01:48:56 -0700268 if (hlock->read)
269 lock_time_inc(&stats->read_holdtime, holdtime);
270 else
271 lock_time_inc(&stats->write_holdtime, holdtime);
272 put_lock_stats(stats);
273}
274#else
275static inline void lock_release_holdtime(struct held_lock *hlock)
276{
277}
278#endif
279
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700280/*
281 * We keep a global list of all lock classes. The list only grows,
282 * never shrinks. The list is only accessed with the lockdep
283 * spinlock lock held.
284 */
285LIST_HEAD(all_lock_classes);
286
287/*
288 * The lockdep classes are in a hash-table as well, for fast lookup:
289 */
290#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
291#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700292#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700293#define classhashentry(key) (classhash_table + __classhashfn((key)))
294
295static struct list_head classhash_table[CLASSHASH_SIZE];
296
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700297/*
298 * We put the lock dependency chains into a hash-table as well, to cache
299 * their existence:
300 */
301#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
302#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700303#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700304#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
305
306static struct list_head chainhash_table[CHAINHASH_SIZE];
307
308/*
309 * The hash key of the lock dependency chains is a hash itself too:
310 * it's a hash of all locks taken up to that lock, including that lock.
311 * It's a 64-bit hash, because it's important for the keys to be
312 * unique.
313 */
314#define iterate_chain_key(key1, key2) \
Ingo Molnar03cbc352006-09-29 02:01:46 -0700315 (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
316 ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700317 (key2))
318
Steven Rostedt1d09daa2008-05-12 21:20:55 +0200319void lockdep_off(void)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700320{
321 current->lockdep_recursion++;
322}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700323EXPORT_SYMBOL(lockdep_off);
324
Steven Rostedt1d09daa2008-05-12 21:20:55 +0200325void lockdep_on(void)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700326{
327 current->lockdep_recursion--;
328}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700329EXPORT_SYMBOL(lockdep_on);
330
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700331/*
332 * Debugging switches:
333 */
334
335#define VERBOSE 0
Ingo Molnar33e94e92006-12-13 00:34:41 -0800336#define VERY_VERBOSE 0
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700337
338#if VERBOSE
339# define HARDIRQ_VERBOSE 1
340# define SOFTIRQ_VERBOSE 1
Nick Piggincf40bd12009-01-21 08:12:39 +0100341# define RECLAIM_VERBOSE 1
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700342#else
343# define HARDIRQ_VERBOSE 0
344# define SOFTIRQ_VERBOSE 0
Nick Piggincf40bd12009-01-21 08:12:39 +0100345# define RECLAIM_VERBOSE 0
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700346#endif
347
Nick Piggincf40bd12009-01-21 08:12:39 +0100348#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700349/*
350 * Quick filtering for interesting events:
351 */
352static int class_filter(struct lock_class *class)
353{
Andi Kleenf9829cc2006-07-10 04:44:01 -0700354#if 0
355 /* Example */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700356 if (class->name_version == 1 &&
Andi Kleenf9829cc2006-07-10 04:44:01 -0700357 !strcmp(class->name, "lockname"))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700358 return 1;
359 if (class->name_version == 1 &&
Andi Kleenf9829cc2006-07-10 04:44:01 -0700360 !strcmp(class->name, "&struct->lockfield"))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700361 return 1;
Andi Kleenf9829cc2006-07-10 04:44:01 -0700362#endif
Ingo Molnara6640892006-12-13 00:34:39 -0800363 /* Filter everything else. 1 would be to allow everything else */
364 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700365}
366#endif
367
368static int verbose(struct lock_class *class)
369{
370#if VERBOSE
371 return class_filter(class);
372#endif
373 return 0;
374}
375
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700376/*
377 * Stack-trace: tightly packed array of stack backtrace
Ingo Molnar74c383f2006-12-13 00:34:43 -0800378 * addresses. Protected by the graph_lock.
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700379 */
380unsigned long nr_stack_trace_entries;
381static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
382
Dave Jones2c522832013-04-25 13:40:02 -0400383static void print_lockdep_off(const char *bug_msg)
384{
385 printk(KERN_DEBUG "%s\n", bug_msg);
386 printk(KERN_DEBUG "turning off the locking correctness validator.\n");
387 printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
388}
389
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700390static int save_trace(struct stack_trace *trace)
391{
392 trace->nr_entries = 0;
393 trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
394 trace->entries = stack_trace + nr_stack_trace_entries;
395
Andi Kleen5a1b3992006-09-26 10:52:34 +0200396 trace->skip = 3;
Andi Kleen5a1b3992006-09-26 10:52:34 +0200397
Christoph Hellwigab1b6f02007-05-08 00:23:29 -0700398 save_stack_trace(trace);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700399
Peter Zijlstra4f84f432009-07-20 15:27:04 +0200400 /*
401 * Some daft arches put -1 at the end to indicate its a full trace.
402 *
403 * <rant> this is buggy anyway, since it takes a whole extra entry so a
404 * complete trace that maxes out the entries provided will be reported
405 * as incomplete, friggin useless </rant>
406 */
Luck, Tonyea5b41f2009-12-09 14:29:36 -0800407 if (trace->nr_entries != 0 &&
408 trace->entries[trace->nr_entries-1] == ULONG_MAX)
Peter Zijlstra4f84f432009-07-20 15:27:04 +0200409 trace->nr_entries--;
410
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700411 trace->max_entries = trace->nr_entries;
412
413 nr_stack_trace_entries += trace->nr_entries;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700414
Peter Zijlstra4f84f432009-07-20 15:27:04 +0200415 if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
Ingo Molnar74c383f2006-12-13 00:34:43 -0800416 if (!debug_locks_off_graph_unlock())
417 return 0;
418
Dave Jones2c522832013-04-25 13:40:02 -0400419 print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
Ingo Molnar74c383f2006-12-13 00:34:43 -0800420 dump_stack();
421
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700422 return 0;
423 }
424
425 return 1;
426}
427
428unsigned int nr_hardirq_chains;
429unsigned int nr_softirq_chains;
430unsigned int nr_process_chains;
431unsigned int max_lockdep_depth;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700432
433#ifdef CONFIG_DEBUG_LOCKDEP
434/*
435 * We cannot printk in early bootup code. Not even early_printk()
436 * might work. So we mark any initialization errors and printk
437 * about it later on, in lockdep_info().
438 */
439static int lockdep_init_error;
Ming Lei81140ac2011-11-17 13:34:32 +0800440static const char *lock_init_error;
Johannes Bergc71063c2007-07-19 01:49:02 -0700441static unsigned long lockdep_init_trace_data[20];
442static struct stack_trace lockdep_init_trace = {
443 .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
444 .entries = lockdep_init_trace_data,
445};
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700446
447/*
448 * Various lockdep statistics:
449 */
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +0200450DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700451#endif
452
453/*
454 * Locking printouts:
455 */
456
Peter Zijlstrafabe9c42009-01-22 14:51:01 +0100457#define __USAGE(__STATE) \
Peter Zijlstrab4b136f2009-01-29 14:50:36 +0100458 [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
459 [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
460 [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
461 [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
Peter Zijlstrafabe9c42009-01-22 14:51:01 +0100462
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700463static const char *usage_str[] =
464{
Peter Zijlstrafabe9c42009-01-22 14:51:01 +0100465#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
466#include "lockdep_states.h"
467#undef LOCKDEP_STATE
468 [LOCK_USED] = "INITIAL USE",
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700469};
470
471const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
472{
Alexey Dobriyanffb45122007-05-08 00:28:41 -0700473 return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700474}
475
Peter Zijlstra3ff176c2009-01-22 17:40:42 +0100476static inline unsigned long lock_flag(enum lock_usage_bit bit)
477{
478 return 1UL << bit;
479}
480
481static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
482{
483 char c = '.';
484
485 if (class->usage_mask & lock_flag(bit + 2))
486 c = '+';
487 if (class->usage_mask & lock_flag(bit)) {
488 c = '-';
489 if (class->usage_mask & lock_flag(bit + 2))
490 c = '?';
491 }
492
493 return c;
494}
495
Peter Zijlstraf510b232009-01-22 17:53:47 +0100496void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700497{
Peter Zijlstraf510b232009-01-22 17:53:47 +0100498 int i = 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700499
Peter Zijlstraf510b232009-01-22 17:53:47 +0100500#define LOCKDEP_STATE(__STATE) \
501 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
502 usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
503#include "lockdep_states.h"
504#undef LOCKDEP_STATE
505
506 usage[i] = '\0';
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700507}
508
Steven Rostedte5e78d02011-11-02 20:24:16 -0400509static void __print_lock_name(struct lock_class *class)
Steven Rostedt3003eba2011-04-20 21:41:54 -0400510{
511 char str[KSYM_NAME_LEN];
512 const char *name;
513
514 name = class->name;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700515 if (!name) {
516 name = __get_key_name(class->key, str);
Steven Rostedte5e78d02011-11-02 20:24:16 -0400517 printk("%s", name);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700518 } else {
Steven Rostedte5e78d02011-11-02 20:24:16 -0400519 printk("%s", name);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700520 if (class->name_version > 1)
521 printk("#%d", class->name_version);
522 if (class->subclass)
523 printk("/%d", class->subclass);
524 }
Steven Rostedte5e78d02011-11-02 20:24:16 -0400525}
526
527static void print_lock_name(struct lock_class *class)
528{
529 char usage[LOCK_USAGE_CHARS];
530
531 get_usage_chars(class, usage);
532
533 printk(" (");
534 __print_lock_name(class);
Peter Zijlstraf510b232009-01-22 17:53:47 +0100535 printk("){%s}", usage);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700536}
537
538static void print_lockdep_cache(struct lockdep_map *lock)
539{
540 const char *name;
Tejun Heo9281ace2007-07-17 04:03:51 -0700541 char str[KSYM_NAME_LEN];
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700542
543 name = lock->name;
544 if (!name)
545 name = __get_key_name(lock->key->subkeys, str);
546
547 printk("%s", name);
548}
549
550static void print_lock(struct held_lock *hlock)
551{
Dave Jonesf82b2172008-08-11 09:30:23 +0200552 print_lock_name(hlock_class(hlock));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700553 printk(", at: ");
554 print_ip_sym(hlock->acquire_ip);
555}
556
557static void lockdep_print_held_locks(struct task_struct *curr)
558{
559 int i, depth = curr->lockdep_depth;
560
561 if (!depth) {
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700562 printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700563 return;
564 }
565 printk("%d lock%s held by %s/%d:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700566 depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700567
568 for (i = 0; i < depth; i++) {
569 printk(" #%d: ", i);
570 print_lock(curr->held_locks + i);
571 }
572}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700573
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +0100574static void print_kernel_ident(void)
Dave Jones99de0552006-09-29 02:00:10 -0700575{
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +0100576 printk("%s %.*s %s\n", init_utsname()->release,
Serge E. Hallyn96b644b2006-10-02 02:18:13 -0700577 (int)strcspn(init_utsname()->version, " "),
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +0100578 init_utsname()->version,
579 print_tainted());
Dave Jones99de0552006-09-29 02:00:10 -0700580}
581
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700582static int very_verbose(struct lock_class *class)
583{
584#if VERY_VERBOSE
585 return class_filter(class);
586#endif
587 return 0;
588}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700589
590/*
591 * Is this the address of a static object:
592 */
593static int static_obj(void *obj)
594{
595 unsigned long start = (unsigned long) &_stext,
596 end = (unsigned long) &_end,
597 addr = (unsigned long) obj;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700598
599 /*
600 * static variable?
601 */
602 if ((addr >= start) && (addr < end))
603 return 1;
604
Mike Frysinger2a9ad182009-09-22 16:44:16 -0700605 if (arch_is_kernel_data(addr))
606 return 1;
607
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700608 /*
Tejun Heo10fad5e2010-03-10 18:57:54 +0900609 * in-kernel percpu var?
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700610 */
Tejun Heo10fad5e2010-03-10 18:57:54 +0900611 if (is_kernel_percpu_address(addr))
612 return 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700613
614 /*
Tejun Heo10fad5e2010-03-10 18:57:54 +0900615 * module static or percpu var?
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700616 */
Tejun Heo10fad5e2010-03-10 18:57:54 +0900617 return is_module_address(addr) || is_module_percpu_address(addr);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700618}
619
620/*
621 * To make lock name printouts unique, we calculate a unique
622 * class->name_version generation counter:
623 */
624static int count_matching_names(struct lock_class *new_class)
625{
626 struct lock_class *class;
627 int count = 0;
628
629 if (!new_class->name)
630 return 0;
631
632 list_for_each_entry(class, &all_lock_classes, lock_entry) {
633 if (new_class->key - new_class->subclass == class->key)
634 return class->name_version;
635 if (class->name && !strcmp(class->name, new_class->name))
636 count = max(count, class->name_version);
637 }
638
639 return count + 1;
640}
641
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700642/*
643 * Register a lock's class in the hash-table, if the class is not present
644 * yet. Otherwise we look it up. We cache the result in the lock object
645 * itself, so actual lookup of the hash should be once per lock object.
646 */
647static inline struct lock_class *
Ingo Molnard6d897c2006-07-10 04:44:04 -0700648look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700649{
650 struct lockdep_subclass_key *key;
651 struct list_head *hash_head;
652 struct lock_class *class;
653
654#ifdef CONFIG_DEBUG_LOCKDEP
655 /*
656 * If the architecture calls into lockdep before initializing
657 * the hashes then we'll warn about it later. (we cannot printk
658 * right now)
659 */
660 if (unlikely(!lockdep_initialized)) {
661 lockdep_init();
662 lockdep_init_error = 1;
Ming Lei81140ac2011-11-17 13:34:32 +0800663 lock_init_error = lock->name;
Johannes Bergc71063c2007-07-19 01:49:02 -0700664 save_stack_trace(&lockdep_init_trace);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700665 }
666#endif
667
Hitoshi Mitake4ba053c2010-10-13 17:30:26 +0900668 if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
669 debug_locks_off();
670 printk(KERN_ERR
671 "BUG: looking up invalid subclass: %u\n", subclass);
672 printk(KERN_ERR
673 "turning off the locking correctness validator.\n");
674 dump_stack();
675 return NULL;
676 }
677
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700678 /*
679 * Static locks do not have their class-keys yet - for them the key
680 * is the lock object itself:
681 */
682 if (unlikely(!lock->key))
683 lock->key = (void *)lock;
684
685 /*
686 * NOTE: the class-key must be unique. For dynamic locks, a static
687 * lock_class_key variable is passed in through the mutex_init()
688 * (or spin_lock_init()) call - which acts as the key. For static
689 * locks we use the lock object itself as the key.
690 */
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700691 BUILD_BUG_ON(sizeof(struct lock_class_key) >
692 sizeof(struct lockdep_map));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700693
694 key = lock->key->subkeys + subclass;
695
696 hash_head = classhashentry(key);
697
698 /*
699 * We can walk the hash lockfree, because the hash only
700 * grows, and we are careful when adding entries to the end:
701 */
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700702 list_for_each_entry(class, hash_head, hash_entry) {
703 if (class->key == key) {
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200704 /*
705 * Huh! same key, different name? Did someone trample
706 * on some memory? We're most confused.
707 */
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700708 WARN_ON_ONCE(class->name != lock->name);
Ingo Molnard6d897c2006-07-10 04:44:04 -0700709 return class;
Peter Zijlstra4b32d0a2007-07-19 01:48:59 -0700710 }
711 }
Ingo Molnard6d897c2006-07-10 04:44:04 -0700712
713 return NULL;
714}
715
716/*
717 * Register a lock's class in the hash-table, if the class is not present
718 * yet. Otherwise we look it up. We cache the result in the lock object
719 * itself, so actual lookup of the hash should be once per lock object.
720 */
721static inline struct lock_class *
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -0400722register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
Ingo Molnard6d897c2006-07-10 04:44:04 -0700723{
724 struct lockdep_subclass_key *key;
725 struct list_head *hash_head;
726 struct lock_class *class;
Ingo Molnar70e45062006-12-06 20:40:50 -0800727 unsigned long flags;
Ingo Molnard6d897c2006-07-10 04:44:04 -0700728
729 class = look_up_lock_class(lock, subclass);
730 if (likely(class))
Yong Zhang87cdee72011-11-09 16:07:14 +0800731 goto out_set_class_cache;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700732
733 /*
734 * Debug-check: all keys must be persistent!
735 */
736 if (!static_obj(lock->key)) {
737 debug_locks_off();
738 printk("INFO: trying to register non-static key.\n");
739 printk("the code is fine but needs lockdep annotation.\n");
740 printk("turning off the locking correctness validator.\n");
741 dump_stack();
742
743 return NULL;
744 }
745
Ingo Molnard6d897c2006-07-10 04:44:04 -0700746 key = lock->key->subkeys + subclass;
747 hash_head = classhashentry(key);
748
Ingo Molnar70e45062006-12-06 20:40:50 -0800749 raw_local_irq_save(flags);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800750 if (!graph_lock()) {
751 raw_local_irq_restore(flags);
752 return NULL;
753 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700754 /*
755 * We have to do the hash-walk again, to avoid races
756 * with another CPU:
757 */
758 list_for_each_entry(class, hash_head, hash_entry)
759 if (class->key == key)
760 goto out_unlock_set;
761 /*
762 * Allocate a new key from the static array, and add it to
763 * the hash:
764 */
765 if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
Ingo Molnar74c383f2006-12-13 00:34:43 -0800766 if (!debug_locks_off_graph_unlock()) {
767 raw_local_irq_restore(flags);
768 return NULL;
769 }
Ingo Molnar70e45062006-12-06 20:40:50 -0800770 raw_local_irq_restore(flags);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800771
Dave Jones2c522832013-04-25 13:40:02 -0400772 print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +0100773 dump_stack();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700774 return NULL;
775 }
776 class = lock_classes + nr_lock_classes++;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +0200777 debug_atomic_inc(nr_unused_locks);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700778 class->key = key;
779 class->name = lock->name;
780 class->subclass = subclass;
781 INIT_LIST_HEAD(&class->lock_entry);
782 INIT_LIST_HEAD(&class->locks_before);
783 INIT_LIST_HEAD(&class->locks_after);
784 class->name_version = count_matching_names(class);
785 /*
786 * We use RCU's safe list-add method to make
787 * parallel walking of the hash-list safe:
788 */
789 list_add_tail_rcu(&class->hash_entry, hash_head);
Dale Farnsworth14811972008-02-25 23:03:02 +0100790 /*
791 * Add it to the global list of classes:
792 */
793 list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700794
795 if (verbose(class)) {
Ingo Molnar74c383f2006-12-13 00:34:43 -0800796 graph_unlock();
Ingo Molnar70e45062006-12-06 20:40:50 -0800797 raw_local_irq_restore(flags);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800798
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700799 printk("\nnew class %p: %s", class->key, class->name);
800 if (class->name_version > 1)
801 printk("#%d", class->name_version);
802 printk("\n");
803 dump_stack();
Ingo Molnar74c383f2006-12-13 00:34:43 -0800804
Ingo Molnar70e45062006-12-06 20:40:50 -0800805 raw_local_irq_save(flags);
Ingo Molnar74c383f2006-12-13 00:34:43 -0800806 if (!graph_lock()) {
807 raw_local_irq_restore(flags);
808 return NULL;
809 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700810 }
811out_unlock_set:
Ingo Molnar74c383f2006-12-13 00:34:43 -0800812 graph_unlock();
Ingo Molnar70e45062006-12-06 20:40:50 -0800813 raw_local_irq_restore(flags);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700814
Yong Zhang87cdee72011-11-09 16:07:14 +0800815out_set_class_cache:
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -0400816 if (!subclass || force)
Hitoshi Mitake62016252010-10-05 18:01:51 +0900817 lock->class_cache[0] = class;
818 else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
819 lock->class_cache[subclass] = class;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700820
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200821 /*
822 * Hash collision, did we smoke some? We found a class with a matching
823 * hash but the subclass -- which is hashed in -- didn't match.
824 */
Jarek Poplawski381a2292007-02-10 01:44:58 -0800825 if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
826 return NULL;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700827
828 return class;
829}
830
Peter Zijlstraca58abc2007-07-19 01:48:53 -0700831#ifdef CONFIG_PROVE_LOCKING
Ingo Molnarfbb9ce952006-07-03 00:24:50 -0700832/*
Peter Zijlstra8e182572007-07-19 01:48:54 -0700833 * Allocate a lockdep entry. (assumes the graph_lock held, returns
834 * with NULL on failure)
835 */
836static struct lock_list *alloc_list_entry(void)
837{
838 if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
839 if (!debug_locks_off_graph_unlock())
840 return NULL;
841
Dave Jones2c522832013-04-25 13:40:02 -0400842 print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +0100843 dump_stack();
Peter Zijlstra8e182572007-07-19 01:48:54 -0700844 return NULL;
845 }
846 return list_entries + nr_list_entries++;
847}
848
849/*
850 * Add a new dependency to the head of the list:
851 */
852static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
Yong Zhang4726f2a2010-05-04 14:16:48 +0800853 struct list_head *head, unsigned long ip,
854 int distance, struct stack_trace *trace)
Peter Zijlstra8e182572007-07-19 01:48:54 -0700855{
856 struct lock_list *entry;
857 /*
858 * Lock not present yet - get a new dependency struct and
859 * add it to the list:
860 */
861 entry = alloc_list_entry();
862 if (!entry)
863 return 0;
864
Zhu Yi74870172008-08-27 14:33:00 +0800865 entry->class = this;
866 entry->distance = distance;
Yong Zhang4726f2a2010-05-04 14:16:48 +0800867 entry->trace = *trace;
Peter Zijlstra8e182572007-07-19 01:48:54 -0700868 /*
869 * Since we never remove from the dependency list, the list can
870 * be walked lockless by other CPUs, it's only allocation
871 * that must be protected by the spinlock. But this also means
872 * we must make new entries visible only once writes to the
873 * entry become visible - hence the RCU op:
874 */
875 list_add_tail_rcu(&entry->entry, head);
876
877 return 1;
878}
879
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200880/*
881 * For good efficiency of modular, we use power of 2
882 */
Peter Zijlstraaf012962009-07-16 15:44:29 +0200883#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
884#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
885
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200886/*
887 * The circular_queue and helpers is used to implement the
Peter Zijlstraaf012962009-07-16 15:44:29 +0200888 * breadth-first search(BFS)algorithem, by which we can build
889 * the shortest path from the next lock to be acquired to the
890 * previous held lock if there is a circular between them.
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200891 */
Peter Zijlstraaf012962009-07-16 15:44:29 +0200892struct circular_queue {
893 unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
894 unsigned int front, rear;
895};
896
897static struct circular_queue lock_cq;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200898
Ming Lei12f3dfd2009-07-16 15:44:29 +0200899unsigned int max_bfs_queue_depth;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200900
Ming Leie351b662009-07-22 22:48:09 +0800901static unsigned int lockdep_dependency_gen_id;
902
Peter Zijlstraaf012962009-07-16 15:44:29 +0200903static inline void __cq_init(struct circular_queue *cq)
904{
905 cq->front = cq->rear = 0;
Ming Leie351b662009-07-22 22:48:09 +0800906 lockdep_dependency_gen_id++;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200907}
908
909static inline int __cq_empty(struct circular_queue *cq)
910{
911 return (cq->front == cq->rear);
912}
913
914static inline int __cq_full(struct circular_queue *cq)
915{
916 return ((cq->rear + 1) & CQ_MASK) == cq->front;
917}
918
919static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
920{
921 if (__cq_full(cq))
922 return -1;
923
924 cq->element[cq->rear] = elem;
925 cq->rear = (cq->rear + 1) & CQ_MASK;
926 return 0;
927}
928
929static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
930{
931 if (__cq_empty(cq))
932 return -1;
933
934 *elem = cq->element[cq->front];
935 cq->front = (cq->front + 1) & CQ_MASK;
936 return 0;
937}
938
939static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
940{
941 return (cq->rear - cq->front) & CQ_MASK;
942}
943
944static inline void mark_lock_accessed(struct lock_list *lock,
945 struct lock_list *parent)
946{
947 unsigned long nr;
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200948
Peter Zijlstraaf012962009-07-16 15:44:29 +0200949 nr = lock - list_entries;
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200950 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
Peter Zijlstraaf012962009-07-16 15:44:29 +0200951 lock->parent = parent;
Ming Leie351b662009-07-22 22:48:09 +0800952 lock->class->dep_gen_id = lockdep_dependency_gen_id;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200953}
954
955static inline unsigned long lock_accessed(struct lock_list *lock)
956{
957 unsigned long nr;
Peter Zijlstra98c33ed2009-07-21 13:19:07 +0200958
Peter Zijlstraaf012962009-07-16 15:44:29 +0200959 nr = lock - list_entries;
Peter Zijlstra0119fee2011-09-02 01:30:29 +0200960 WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
Ming Leie351b662009-07-22 22:48:09 +0800961 return lock->class->dep_gen_id == lockdep_dependency_gen_id;
Peter Zijlstraaf012962009-07-16 15:44:29 +0200962}
963
964static inline struct lock_list *get_lock_parent(struct lock_list *child)
965{
966 return child->parent;
967}
968
969static inline int get_lock_depth(struct lock_list *child)
970{
971 int depth = 0;
972 struct lock_list *parent;
973
974 while ((parent = get_lock_parent(child))) {
975 child = parent;
976 depth++;
977 }
978 return depth;
979}
980
Ming Lei9e2d5512009-07-16 15:44:29 +0200981static int __bfs(struct lock_list *source_entry,
Peter Zijlstraaf012962009-07-16 15:44:29 +0200982 void *data,
983 int (*match)(struct lock_list *entry, void *data),
984 struct lock_list **target_entry,
985 int forward)
Ming Leic94aa5c2009-07-16 15:44:29 +0200986{
987 struct lock_list *entry;
Ming Leid588e462009-07-16 15:44:29 +0200988 struct list_head *head;
Ming Leic94aa5c2009-07-16 15:44:29 +0200989 struct circular_queue *cq = &lock_cq;
990 int ret = 1;
991
Ming Lei9e2d5512009-07-16 15:44:29 +0200992 if (match(source_entry, data)) {
Ming Leic94aa5c2009-07-16 15:44:29 +0200993 *target_entry = source_entry;
994 ret = 0;
995 goto exit;
996 }
997
Ming Leid588e462009-07-16 15:44:29 +0200998 if (forward)
999 head = &source_entry->class->locks_after;
1000 else
1001 head = &source_entry->class->locks_before;
1002
1003 if (list_empty(head))
1004 goto exit;
1005
1006 __cq_init(cq);
Ming Leic94aa5c2009-07-16 15:44:29 +02001007 __cq_enqueue(cq, (unsigned long)source_entry);
1008
1009 while (!__cq_empty(cq)) {
1010 struct lock_list *lock;
Ming Leic94aa5c2009-07-16 15:44:29 +02001011
1012 __cq_dequeue(cq, (unsigned long *)&lock);
1013
1014 if (!lock->class) {
1015 ret = -2;
1016 goto exit;
1017 }
1018
1019 if (forward)
1020 head = &lock->class->locks_after;
1021 else
1022 head = &lock->class->locks_before;
1023
1024 list_for_each_entry(entry, head, entry) {
1025 if (!lock_accessed(entry)) {
Ming Lei12f3dfd2009-07-16 15:44:29 +02001026 unsigned int cq_depth;
Ming Leic94aa5c2009-07-16 15:44:29 +02001027 mark_lock_accessed(entry, lock);
Ming Lei9e2d5512009-07-16 15:44:29 +02001028 if (match(entry, data)) {
Ming Leic94aa5c2009-07-16 15:44:29 +02001029 *target_entry = entry;
1030 ret = 0;
1031 goto exit;
1032 }
1033
1034 if (__cq_enqueue(cq, (unsigned long)entry)) {
1035 ret = -1;
1036 goto exit;
1037 }
Ming Lei12f3dfd2009-07-16 15:44:29 +02001038 cq_depth = __cq_get_elem_count(cq);
1039 if (max_bfs_queue_depth < cq_depth)
1040 max_bfs_queue_depth = cq_depth;
Ming Leic94aa5c2009-07-16 15:44:29 +02001041 }
1042 }
1043 }
1044exit:
1045 return ret;
1046}
1047
Ming Leid7aaba12009-07-16 15:44:29 +02001048static inline int __bfs_forwards(struct lock_list *src_entry,
Ming Lei9e2d5512009-07-16 15:44:29 +02001049 void *data,
1050 int (*match)(struct lock_list *entry, void *data),
1051 struct lock_list **target_entry)
Ming Leic94aa5c2009-07-16 15:44:29 +02001052{
Ming Lei9e2d5512009-07-16 15:44:29 +02001053 return __bfs(src_entry, data, match, target_entry, 1);
Ming Leic94aa5c2009-07-16 15:44:29 +02001054
1055}
1056
Ming Leid7aaba12009-07-16 15:44:29 +02001057static inline int __bfs_backwards(struct lock_list *src_entry,
Ming Lei9e2d5512009-07-16 15:44:29 +02001058 void *data,
1059 int (*match)(struct lock_list *entry, void *data),
1060 struct lock_list **target_entry)
Ming Leic94aa5c2009-07-16 15:44:29 +02001061{
Ming Lei9e2d5512009-07-16 15:44:29 +02001062 return __bfs(src_entry, data, match, target_entry, 0);
Ming Leic94aa5c2009-07-16 15:44:29 +02001063
1064}
1065
Peter Zijlstra8e182572007-07-19 01:48:54 -07001066/*
1067 * Recursive, forwards-direction lock-dependency checking, used for
1068 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1069 * checking.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001070 */
Peter Zijlstra8e182572007-07-19 01:48:54 -07001071
1072/*
1073 * Print a dependency chain entry (this is only done when a deadlock
1074 * has been detected):
1075 */
1076static noinline int
Ming Lei24208ca2009-07-16 15:44:29 +02001077print_circular_bug_entry(struct lock_list *target, int depth)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001078{
1079 if (debug_locks_silent)
1080 return 0;
1081 printk("\n-> #%u", depth);
1082 print_lock_name(target->class);
1083 printk(":\n");
1084 print_stack_trace(&target->trace, 6);
1085
1086 return 0;
1087}
1088
Steven Rostedtf4185812011-04-20 21:41:55 -04001089static void
1090print_circular_lock_scenario(struct held_lock *src,
1091 struct held_lock *tgt,
1092 struct lock_list *prt)
1093{
1094 struct lock_class *source = hlock_class(src);
1095 struct lock_class *target = hlock_class(tgt);
1096 struct lock_class *parent = prt->class;
1097
1098 /*
1099 * A direct locking problem where unsafe_class lock is taken
1100 * directly by safe_class lock, then all we need to show
1101 * is the deadlock scenario, as it is obvious that the
1102 * unsafe lock is taken under the safe lock.
1103 *
1104 * But if there is a chain instead, where the safe lock takes
1105 * an intermediate lock (middle_class) where this lock is
1106 * not the same as the safe lock, then the lock chain is
1107 * used to describe the problem. Otherwise we would need
1108 * to show a different CPU case for each link in the chain
1109 * from the safe_class lock to the unsafe_class lock.
1110 */
1111 if (parent != source) {
1112 printk("Chain exists of:\n ");
1113 __print_lock_name(source);
1114 printk(" --> ");
1115 __print_lock_name(parent);
1116 printk(" --> ");
1117 __print_lock_name(target);
1118 printk("\n\n");
1119 }
1120
1121 printk(" Possible unsafe locking scenario:\n\n");
1122 printk(" CPU0 CPU1\n");
1123 printk(" ---- ----\n");
1124 printk(" lock(");
1125 __print_lock_name(target);
1126 printk(");\n");
1127 printk(" lock(");
1128 __print_lock_name(parent);
1129 printk(");\n");
1130 printk(" lock(");
1131 __print_lock_name(target);
1132 printk(");\n");
1133 printk(" lock(");
1134 __print_lock_name(source);
1135 printk(");\n");
1136 printk("\n *** DEADLOCK ***\n\n");
1137}
1138
Peter Zijlstra8e182572007-07-19 01:48:54 -07001139/*
1140 * When a circular dependency is detected, print the
1141 * header first:
1142 */
1143static noinline int
Ming Leidb0002a2009-07-16 15:44:29 +02001144print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1145 struct held_lock *check_src,
1146 struct held_lock *check_tgt)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001147{
1148 struct task_struct *curr = current;
1149
Ming Leic94aa5c2009-07-16 15:44:29 +02001150 if (debug_locks_silent)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001151 return 0;
1152
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001153 printk("\n");
1154 printk("======================================================\n");
1155 printk("[ INFO: possible circular locking dependency detected ]\n");
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +01001156 print_kernel_ident();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001157 printk("-------------------------------------------------------\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001158 printk("%s/%d is trying to acquire lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07001159 curr->comm, task_pid_nr(curr));
Ming Leidb0002a2009-07-16 15:44:29 +02001160 print_lock(check_src);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001161 printk("\nbut task is already holding lock:\n");
Ming Leidb0002a2009-07-16 15:44:29 +02001162 print_lock(check_tgt);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001163 printk("\nwhich lock already depends on the new lock.\n\n");
1164 printk("\nthe existing dependency chain (in reverse order) is:\n");
1165
1166 print_circular_bug_entry(entry, depth);
1167
1168 return 0;
1169}
1170
Ming Lei9e2d5512009-07-16 15:44:29 +02001171static inline int class_equal(struct lock_list *entry, void *data)
1172{
1173 return entry->class == data;
1174}
1175
Ming Leidb0002a2009-07-16 15:44:29 +02001176static noinline int print_circular_bug(struct lock_list *this,
1177 struct lock_list *target,
1178 struct held_lock *check_src,
1179 struct held_lock *check_tgt)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001180{
1181 struct task_struct *curr = current;
Ming Leic94aa5c2009-07-16 15:44:29 +02001182 struct lock_list *parent;
Steven Rostedtf4185812011-04-20 21:41:55 -04001183 struct lock_list *first_parent;
Ming Lei24208ca2009-07-16 15:44:29 +02001184 int depth;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001185
Ming Leic94aa5c2009-07-16 15:44:29 +02001186 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001187 return 0;
1188
Ming Leidb0002a2009-07-16 15:44:29 +02001189 if (!save_trace(&this->trace))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001190 return 0;
1191
Ming Leic94aa5c2009-07-16 15:44:29 +02001192 depth = get_lock_depth(target);
1193
Ming Leidb0002a2009-07-16 15:44:29 +02001194 print_circular_bug_header(target, depth, check_src, check_tgt);
Ming Leic94aa5c2009-07-16 15:44:29 +02001195
1196 parent = get_lock_parent(target);
Steven Rostedtf4185812011-04-20 21:41:55 -04001197 first_parent = parent;
Ming Leic94aa5c2009-07-16 15:44:29 +02001198
1199 while (parent) {
1200 print_circular_bug_entry(parent, --depth);
1201 parent = get_lock_parent(parent);
1202 }
Peter Zijlstra8e182572007-07-19 01:48:54 -07001203
1204 printk("\nother info that might help us debug this:\n\n");
Steven Rostedtf4185812011-04-20 21:41:55 -04001205 print_circular_lock_scenario(check_src, check_tgt,
1206 first_parent);
1207
Peter Zijlstra8e182572007-07-19 01:48:54 -07001208 lockdep_print_held_locks(curr);
1209
1210 printk("\nstack backtrace:\n");
1211 dump_stack();
1212
1213 return 0;
1214}
1215
Ming Leidb0002a2009-07-16 15:44:29 +02001216static noinline int print_bfs_bug(int ret)
1217{
1218 if (!debug_locks_off_graph_unlock())
1219 return 0;
1220
Peter Zijlstra0119fee2011-09-02 01:30:29 +02001221 /*
1222 * Breadth-first-search failed, graph got corrupted?
1223 */
Ming Leidb0002a2009-07-16 15:44:29 +02001224 WARN(1, "lockdep bfs error:%d\n", ret);
1225
1226 return 0;
1227}
1228
Ming Leief681022009-07-16 15:44:29 +02001229static int noop_count(struct lock_list *entry, void *data)
David Miller419ca3f2008-07-29 21:45:03 -07001230{
Ming Leief681022009-07-16 15:44:29 +02001231 (*(unsigned long *)data)++;
1232 return 0;
David Miller419ca3f2008-07-29 21:45:03 -07001233}
1234
Ming Leief681022009-07-16 15:44:29 +02001235unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1236{
1237 unsigned long count = 0;
1238 struct lock_list *uninitialized_var(target_entry);
1239
1240 __bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1241
1242 return count;
1243}
David Miller419ca3f2008-07-29 21:45:03 -07001244unsigned long lockdep_count_forward_deps(struct lock_class *class)
1245{
1246 unsigned long ret, flags;
Ming Leief681022009-07-16 15:44:29 +02001247 struct lock_list this;
1248
1249 this.parent = NULL;
1250 this.class = class;
David Miller419ca3f2008-07-29 21:45:03 -07001251
1252 local_irq_save(flags);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001253 arch_spin_lock(&lockdep_lock);
Ming Leief681022009-07-16 15:44:29 +02001254 ret = __lockdep_count_forward_deps(&this);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001255 arch_spin_unlock(&lockdep_lock);
David Miller419ca3f2008-07-29 21:45:03 -07001256 local_irq_restore(flags);
1257
1258 return ret;
1259}
1260
Ming Leief681022009-07-16 15:44:29 +02001261unsigned long __lockdep_count_backward_deps(struct lock_list *this)
David Miller419ca3f2008-07-29 21:45:03 -07001262{
Ming Leief681022009-07-16 15:44:29 +02001263 unsigned long count = 0;
1264 struct lock_list *uninitialized_var(target_entry);
David Miller419ca3f2008-07-29 21:45:03 -07001265
Ming Leief681022009-07-16 15:44:29 +02001266 __bfs_backwards(this, (void *)&count, noop_count, &target_entry);
David Miller419ca3f2008-07-29 21:45:03 -07001267
Ming Leief681022009-07-16 15:44:29 +02001268 return count;
David Miller419ca3f2008-07-29 21:45:03 -07001269}
1270
1271unsigned long lockdep_count_backward_deps(struct lock_class *class)
1272{
1273 unsigned long ret, flags;
Ming Leief681022009-07-16 15:44:29 +02001274 struct lock_list this;
1275
1276 this.parent = NULL;
1277 this.class = class;
David Miller419ca3f2008-07-29 21:45:03 -07001278
1279 local_irq_save(flags);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001280 arch_spin_lock(&lockdep_lock);
Ming Leief681022009-07-16 15:44:29 +02001281 ret = __lockdep_count_backward_deps(&this);
Thomas Gleixner0199c4e2009-12-02 20:01:25 +01001282 arch_spin_unlock(&lockdep_lock);
David Miller419ca3f2008-07-29 21:45:03 -07001283 local_irq_restore(flags);
1284
1285 return ret;
1286}
1287
Peter Zijlstra8e182572007-07-19 01:48:54 -07001288/*
1289 * Prove that the dependency graph starting at <entry> can not
1290 * lead to <target>. Print an error and return 0 if it does.
1291 */
1292static noinline int
Ming Leidb0002a2009-07-16 15:44:29 +02001293check_noncircular(struct lock_list *root, struct lock_class *target,
1294 struct lock_list **target_entry)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001295{
Ming Leidb0002a2009-07-16 15:44:29 +02001296 int result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001297
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001298 debug_atomic_inc(nr_cyclic_checks);
David Miller419ca3f2008-07-29 21:45:03 -07001299
Ming Leid7aaba12009-07-16 15:44:29 +02001300 result = __bfs_forwards(root, target, class_equal, target_entry);
Ming Leidb0002a2009-07-16 15:44:29 +02001301
1302 return result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001303}
1304
Steven Rostedt81d68a92008-05-12 21:20:42 +02001305#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001306/*
1307 * Forwards and backwards subgraph searching, for the purposes of
1308 * proving that two subgraphs can be connected by a new dependency
1309 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
1310 */
Peter Zijlstra8e182572007-07-19 01:48:54 -07001311
Ming Leid7aaba12009-07-16 15:44:29 +02001312static inline int usage_match(struct lock_list *entry, void *bit)
1313{
1314 return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1315}
1316
1317
1318
Peter Zijlstra8e182572007-07-19 01:48:54 -07001319/*
1320 * Find a node in the forwards-direction dependency sub-graph starting
Ming Leid7aaba12009-07-16 15:44:29 +02001321 * at @root->class that matches @bit.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001322 *
Ming Leid7aaba12009-07-16 15:44:29 +02001323 * Return 0 if such a node exists in the subgraph, and put that node
1324 * into *@target_entry.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001325 *
Ming Leid7aaba12009-07-16 15:44:29 +02001326 * Return 1 otherwise and keep *@target_entry unchanged.
1327 * Return <0 on error.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001328 */
Ming Leid7aaba12009-07-16 15:44:29 +02001329static int
1330find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1331 struct lock_list **target_entry)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001332{
Ming Leid7aaba12009-07-16 15:44:29 +02001333 int result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001334
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001335 debug_atomic_inc(nr_find_usage_forwards_checks);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001336
Ming Leid7aaba12009-07-16 15:44:29 +02001337 result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1338
1339 return result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001340}
1341
1342/*
1343 * Find a node in the backwards-direction dependency sub-graph starting
Ming Leid7aaba12009-07-16 15:44:29 +02001344 * at @root->class that matches @bit.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001345 *
Ming Leid7aaba12009-07-16 15:44:29 +02001346 * Return 0 if such a node exists in the subgraph, and put that node
1347 * into *@target_entry.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001348 *
Ming Leid7aaba12009-07-16 15:44:29 +02001349 * Return 1 otherwise and keep *@target_entry unchanged.
1350 * Return <0 on error.
Peter Zijlstra8e182572007-07-19 01:48:54 -07001351 */
Ming Leid7aaba12009-07-16 15:44:29 +02001352static int
1353find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1354 struct lock_list **target_entry)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001355{
Ming Leid7aaba12009-07-16 15:44:29 +02001356 int result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001357
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02001358 debug_atomic_inc(nr_find_usage_backwards_checks);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001359
Ming Leid7aaba12009-07-16 15:44:29 +02001360 result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
Dave Jonesf82b2172008-08-11 09:30:23 +02001361
Ming Leid7aaba12009-07-16 15:44:29 +02001362 return result;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001363}
1364
Peter Zijlstraaf012962009-07-16 15:44:29 +02001365static void print_lock_class_header(struct lock_class *class, int depth)
1366{
1367 int bit;
1368
1369 printk("%*s->", depth, "");
1370 print_lock_name(class);
1371 printk(" ops: %lu", class->ops);
1372 printk(" {\n");
1373
1374 for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1375 if (class->usage_mask & (1 << bit)) {
1376 int len = depth;
1377
1378 len += printk("%*s %s", depth, "", usage_str[bit]);
1379 len += printk(" at:\n");
1380 print_stack_trace(class->usage_traces + bit, len);
1381 }
1382 }
1383 printk("%*s }\n", depth, "");
1384
1385 printk("%*s ... key at: ",depth,"");
1386 print_ip_sym((unsigned long)class->key);
1387}
1388
1389/*
1390 * printk the shortest lock dependencies from @start to @end in reverse order:
1391 */
1392static void __used
1393print_shortest_lock_dependencies(struct lock_list *leaf,
1394 struct lock_list *root)
1395{
1396 struct lock_list *entry = leaf;
1397 int depth;
1398
1399 /*compute depth from generated tree by BFS*/
1400 depth = get_lock_depth(leaf);
1401
1402 do {
1403 print_lock_class_header(entry->class, depth);
1404 printk("%*s ... acquired at:\n", depth, "");
1405 print_stack_trace(&entry->trace, 2);
1406 printk("\n");
1407
1408 if (depth == 0 && (entry != root)) {
Steven Rostedt6be8c392011-04-20 21:41:58 -04001409 printk("lockdep:%s bad path found in chain graph\n", __func__);
Peter Zijlstraaf012962009-07-16 15:44:29 +02001410 break;
1411 }
1412
1413 entry = get_lock_parent(entry);
1414 depth--;
1415 } while (entry && (depth >= 0));
1416
1417 return;
1418}
Ming Leid7aaba12009-07-16 15:44:29 +02001419
Steven Rostedt3003eba2011-04-20 21:41:54 -04001420static void
1421print_irq_lock_scenario(struct lock_list *safe_entry,
1422 struct lock_list *unsafe_entry,
Steven Rostedtdad3d742011-04-20 21:41:57 -04001423 struct lock_class *prev_class,
1424 struct lock_class *next_class)
Steven Rostedt3003eba2011-04-20 21:41:54 -04001425{
1426 struct lock_class *safe_class = safe_entry->class;
1427 struct lock_class *unsafe_class = unsafe_entry->class;
Steven Rostedtdad3d742011-04-20 21:41:57 -04001428 struct lock_class *middle_class = prev_class;
Steven Rostedt3003eba2011-04-20 21:41:54 -04001429
1430 if (middle_class == safe_class)
Steven Rostedtdad3d742011-04-20 21:41:57 -04001431 middle_class = next_class;
Steven Rostedt3003eba2011-04-20 21:41:54 -04001432
1433 /*
1434 * A direct locking problem where unsafe_class lock is taken
1435 * directly by safe_class lock, then all we need to show
1436 * is the deadlock scenario, as it is obvious that the
1437 * unsafe lock is taken under the safe lock.
1438 *
1439 * But if there is a chain instead, where the safe lock takes
1440 * an intermediate lock (middle_class) where this lock is
1441 * not the same as the safe lock, then the lock chain is
1442 * used to describe the problem. Otherwise we would need
1443 * to show a different CPU case for each link in the chain
1444 * from the safe_class lock to the unsafe_class lock.
1445 */
1446 if (middle_class != unsafe_class) {
1447 printk("Chain exists of:\n ");
1448 __print_lock_name(safe_class);
1449 printk(" --> ");
1450 __print_lock_name(middle_class);
1451 printk(" --> ");
1452 __print_lock_name(unsafe_class);
1453 printk("\n\n");
1454 }
1455
1456 printk(" Possible interrupt unsafe locking scenario:\n\n");
1457 printk(" CPU0 CPU1\n");
1458 printk(" ---- ----\n");
1459 printk(" lock(");
1460 __print_lock_name(unsafe_class);
1461 printk(");\n");
1462 printk(" local_irq_disable();\n");
1463 printk(" lock(");
1464 __print_lock_name(safe_class);
1465 printk(");\n");
1466 printk(" lock(");
1467 __print_lock_name(middle_class);
1468 printk(");\n");
1469 printk(" <Interrupt>\n");
1470 printk(" lock(");
1471 __print_lock_name(safe_class);
1472 printk(");\n");
1473 printk("\n *** DEADLOCK ***\n\n");
1474}
1475
Peter Zijlstra8e182572007-07-19 01:48:54 -07001476static int
1477print_bad_irq_dependency(struct task_struct *curr,
Ming Lei24208ca2009-07-16 15:44:29 +02001478 struct lock_list *prev_root,
1479 struct lock_list *next_root,
1480 struct lock_list *backwards_entry,
1481 struct lock_list *forwards_entry,
Peter Zijlstra8e182572007-07-19 01:48:54 -07001482 struct held_lock *prev,
1483 struct held_lock *next,
1484 enum lock_usage_bit bit1,
1485 enum lock_usage_bit bit2,
1486 const char *irqclass)
1487{
1488 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1489 return 0;
1490
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001491 printk("\n");
1492 printk("======================================================\n");
1493 printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
Peter Zijlstra8e182572007-07-19 01:48:54 -07001494 irqclass, irqclass);
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +01001495 print_kernel_ident();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001496 printk("------------------------------------------------------\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001497 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 -07001498 curr->comm, task_pid_nr(curr),
Peter Zijlstra8e182572007-07-19 01:48:54 -07001499 curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1500 curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1501 curr->hardirqs_enabled,
1502 curr->softirqs_enabled);
1503 print_lock(next);
1504
1505 printk("\nand this task is already holding:\n");
1506 print_lock(prev);
1507 printk("which would create a new lock dependency:\n");
Dave Jonesf82b2172008-08-11 09:30:23 +02001508 print_lock_name(hlock_class(prev));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001509 printk(" ->");
Dave Jonesf82b2172008-08-11 09:30:23 +02001510 print_lock_name(hlock_class(next));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001511 printk("\n");
1512
1513 printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1514 irqclass);
Ming Lei24208ca2009-07-16 15:44:29 +02001515 print_lock_name(backwards_entry->class);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001516 printk("\n... which became %s-irq-safe at:\n", irqclass);
1517
Ming Lei24208ca2009-07-16 15:44:29 +02001518 print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001519
1520 printk("\nto a %s-irq-unsafe lock:\n", irqclass);
Ming Lei24208ca2009-07-16 15:44:29 +02001521 print_lock_name(forwards_entry->class);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001522 printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1523 printk("...");
1524
Ming Lei24208ca2009-07-16 15:44:29 +02001525 print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001526
1527 printk("\nother info that might help us debug this:\n\n");
Steven Rostedtdad3d742011-04-20 21:41:57 -04001528 print_irq_lock_scenario(backwards_entry, forwards_entry,
1529 hlock_class(prev), hlock_class(next));
Steven Rostedt3003eba2011-04-20 21:41:54 -04001530
Peter Zijlstra8e182572007-07-19 01:48:54 -07001531 lockdep_print_held_locks(curr);
1532
Ming Lei24208ca2009-07-16 15:44:29 +02001533 printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1534 printk(" and the holding lock:\n");
1535 if (!save_trace(&prev_root->trace))
1536 return 0;
1537 print_shortest_lock_dependencies(backwards_entry, prev_root);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001538
Ming Lei24208ca2009-07-16 15:44:29 +02001539 printk("\nthe dependencies between the lock to be acquired");
1540 printk(" and %s-irq-unsafe lock:\n", irqclass);
1541 if (!save_trace(&next_root->trace))
1542 return 0;
1543 print_shortest_lock_dependencies(forwards_entry, next_root);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001544
1545 printk("\nstack backtrace:\n");
1546 dump_stack();
1547
1548 return 0;
1549}
1550
1551static int
1552check_usage(struct task_struct *curr, struct held_lock *prev,
1553 struct held_lock *next, enum lock_usage_bit bit_backwards,
1554 enum lock_usage_bit bit_forwards, const char *irqclass)
1555{
1556 int ret;
Ming Lei24208ca2009-07-16 15:44:29 +02001557 struct lock_list this, that;
Ming Leid7aaba12009-07-16 15:44:29 +02001558 struct lock_list *uninitialized_var(target_entry);
Ming Lei24208ca2009-07-16 15:44:29 +02001559 struct lock_list *uninitialized_var(target_entry1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001560
Ming Leid7aaba12009-07-16 15:44:29 +02001561 this.parent = NULL;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001562
Ming Leid7aaba12009-07-16 15:44:29 +02001563 this.class = hlock_class(prev);
1564 ret = find_usage_backwards(&this, bit_backwards, &target_entry);
Peter Zijlstraaf012962009-07-16 15:44:29 +02001565 if (ret < 0)
1566 return print_bfs_bug(ret);
1567 if (ret == 1)
1568 return ret;
Ming Leid7aaba12009-07-16 15:44:29 +02001569
Ming Lei24208ca2009-07-16 15:44:29 +02001570 that.parent = NULL;
1571 that.class = hlock_class(next);
1572 ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
Peter Zijlstraaf012962009-07-16 15:44:29 +02001573 if (ret < 0)
1574 return print_bfs_bug(ret);
1575 if (ret == 1)
1576 return ret;
Ming Leid7aaba12009-07-16 15:44:29 +02001577
Ming Lei24208ca2009-07-16 15:44:29 +02001578 return print_bad_irq_dependency(curr, &this, &that,
1579 target_entry, target_entry1,
1580 prev, next,
Peter Zijlstra8e182572007-07-19 01:48:54 -07001581 bit_backwards, bit_forwards, irqclass);
1582}
1583
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001584static const char *state_names[] = {
1585#define LOCKDEP_STATE(__STATE) \
Peter Zijlstrab4b136f2009-01-29 14:50:36 +01001586 __stringify(__STATE),
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001587#include "lockdep_states.h"
1588#undef LOCKDEP_STATE
1589};
1590
1591static const char *state_rnames[] = {
1592#define LOCKDEP_STATE(__STATE) \
Peter Zijlstrab4b136f2009-01-29 14:50:36 +01001593 __stringify(__STATE)"-READ",
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001594#include "lockdep_states.h"
1595#undef LOCKDEP_STATE
1596};
1597
1598static inline const char *state_name(enum lock_usage_bit bit)
1599{
1600 return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1601}
1602
1603static int exclusive_bit(int new_bit)
1604{
1605 /*
1606 * USED_IN
1607 * USED_IN_READ
1608 * ENABLED
1609 * ENABLED_READ
1610 *
1611 * bit 0 - write/read
1612 * bit 1 - used_in/enabled
1613 * bit 2+ state
1614 */
1615
1616 int state = new_bit & ~3;
1617 int dir = new_bit & 2;
1618
1619 /*
1620 * keep state, bit flip the direction and strip read.
1621 */
1622 return state | (dir ^ 2);
1623}
1624
1625static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
1626 struct held_lock *next, enum lock_usage_bit bit)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001627{
1628 /*
1629 * Prove that the new dependency does not connect a hardirq-safe
1630 * lock with a hardirq-unsafe lock - to achieve this we search
1631 * the backwards-subgraph starting at <prev>, and the
1632 * forwards-subgraph starting at <next>:
1633 */
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001634 if (!check_usage(curr, prev, next, bit,
1635 exclusive_bit(bit), state_name(bit)))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001636 return 0;
1637
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001638 bit++; /* _READ */
1639
Peter Zijlstra8e182572007-07-19 01:48:54 -07001640 /*
1641 * Prove that the new dependency does not connect a hardirq-safe-read
1642 * lock with a hardirq-unsafe lock - to achieve this we search
1643 * the backwards-subgraph starting at <prev>, and the
1644 * forwards-subgraph starting at <next>:
1645 */
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001646 if (!check_usage(curr, prev, next, bit,
1647 exclusive_bit(bit), state_name(bit)))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001648 return 0;
1649
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001650 return 1;
1651}
Peter Zijlstra8e182572007-07-19 01:48:54 -07001652
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001653static int
1654check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1655 struct held_lock *next)
1656{
1657#define LOCKDEP_STATE(__STATE) \
1658 if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
Nick Piggincf40bd12009-01-21 08:12:39 +01001659 return 0;
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01001660#include "lockdep_states.h"
1661#undef LOCKDEP_STATE
Nick Piggincf40bd12009-01-21 08:12:39 +01001662
Peter Zijlstra8e182572007-07-19 01:48:54 -07001663 return 1;
1664}
1665
1666static void inc_chains(void)
1667{
1668 if (current->hardirq_context)
1669 nr_hardirq_chains++;
1670 else {
1671 if (current->softirq_context)
1672 nr_softirq_chains++;
1673 else
1674 nr_process_chains++;
1675 }
1676}
1677
1678#else
1679
1680static inline int
1681check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
1682 struct held_lock *next)
1683{
1684 return 1;
1685}
1686
1687static inline void inc_chains(void)
1688{
1689 nr_process_chains++;
1690}
1691
1692#endif
1693
Steven Rostedt48702ec2011-04-20 21:41:56 -04001694static void
1695print_deadlock_scenario(struct held_lock *nxt,
1696 struct held_lock *prv)
1697{
1698 struct lock_class *next = hlock_class(nxt);
1699 struct lock_class *prev = hlock_class(prv);
1700
1701 printk(" Possible unsafe locking scenario:\n\n");
1702 printk(" CPU0\n");
1703 printk(" ----\n");
1704 printk(" lock(");
1705 __print_lock_name(prev);
1706 printk(");\n");
1707 printk(" lock(");
1708 __print_lock_name(next);
1709 printk(");\n");
1710 printk("\n *** DEADLOCK ***\n\n");
1711 printk(" May be due to missing lock nesting notation\n\n");
1712}
1713
Peter Zijlstra8e182572007-07-19 01:48:54 -07001714static int
1715print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
1716 struct held_lock *next)
1717{
1718 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
1719 return 0;
1720
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001721 printk("\n");
1722 printk("=============================================\n");
1723 printk("[ INFO: possible recursive locking detected ]\n");
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +01001724 print_kernel_ident();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07001725 printk("---------------------------------------------\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07001726 printk("%s/%d is trying to acquire lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07001727 curr->comm, task_pid_nr(curr));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001728 print_lock(next);
1729 printk("\nbut task is already holding lock:\n");
1730 print_lock(prev);
1731
1732 printk("\nother info that might help us debug this:\n");
Steven Rostedt48702ec2011-04-20 21:41:56 -04001733 print_deadlock_scenario(next, prev);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001734 lockdep_print_held_locks(curr);
1735
1736 printk("\nstack backtrace:\n");
1737 dump_stack();
1738
1739 return 0;
1740}
1741
1742/*
1743 * Check whether we are holding such a class already.
1744 *
1745 * (Note that this has to be done separately, because the graph cannot
1746 * detect such classes of deadlocks.)
1747 *
1748 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1749 */
1750static int
1751check_deadlock(struct task_struct *curr, struct held_lock *next,
1752 struct lockdep_map *next_instance, int read)
1753{
1754 struct held_lock *prev;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001755 struct held_lock *nest = NULL;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001756 int i;
1757
1758 for (i = 0; i < curr->lockdep_depth; i++) {
1759 prev = curr->held_locks + i;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001760
1761 if (prev->instance == next->nest_lock)
1762 nest = prev;
1763
Dave Jonesf82b2172008-08-11 09:30:23 +02001764 if (hlock_class(prev) != hlock_class(next))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001765 continue;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001766
Peter Zijlstra8e182572007-07-19 01:48:54 -07001767 /*
1768 * Allow read-after-read recursion of the same
1769 * lock class (i.e. read_lock(lock)+read_lock(lock)):
1770 */
1771 if ((read == 2) && prev->read)
1772 return 2;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02001773
1774 /*
1775 * We're holding the nest_lock, which serializes this lock's
1776 * nesting behaviour.
1777 */
1778 if (nest)
1779 return 2;
1780
Peter Zijlstra8e182572007-07-19 01:48:54 -07001781 return print_deadlock_bug(curr, prev, next);
1782 }
1783 return 1;
1784}
1785
1786/*
1787 * There was a chain-cache miss, and we are about to add a new dependency
1788 * to a previous lock. We recursively validate the following rules:
1789 *
1790 * - would the adding of the <prev> -> <next> dependency create a
1791 * circular dependency in the graph? [== circular deadlock]
1792 *
1793 * - does the new prev->next dependency connect any hardirq-safe lock
1794 * (in the full backwards-subgraph starting at <prev>) with any
1795 * hardirq-unsafe lock (in the full forwards-subgraph starting at
1796 * <next>)? [== illegal lock inversion with hardirq contexts]
1797 *
1798 * - does the new prev->next dependency connect any softirq-safe lock
1799 * (in the full backwards-subgraph starting at <prev>) with any
1800 * softirq-unsafe lock (in the full forwards-subgraph starting at
1801 * <next>)? [== illegal lock inversion with softirq contexts]
1802 *
1803 * any of these scenarios could lead to a deadlock.
1804 *
1805 * Then if all the validations pass, we add the forwards and backwards
1806 * dependency.
1807 */
1808static int
1809check_prev_add(struct task_struct *curr, struct held_lock *prev,
Yong Zhang4726f2a2010-05-04 14:16:48 +08001810 struct held_lock *next, int distance, int trylock_loop)
Peter Zijlstra8e182572007-07-19 01:48:54 -07001811{
1812 struct lock_list *entry;
1813 int ret;
Ming Leidb0002a2009-07-16 15:44:29 +02001814 struct lock_list this;
1815 struct lock_list *uninitialized_var(target_entry);
Yong Zhang4726f2a2010-05-04 14:16:48 +08001816 /*
1817 * Static variable, serialized by the graph_lock().
1818 *
1819 * We use this static variable to save the stack trace in case
1820 * we call into this function multiple times due to encountering
1821 * trylocks in the held lock stack.
1822 */
1823 static struct stack_trace trace;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001824
1825 /*
1826 * Prove that the new <prev> -> <next> dependency would not
1827 * create a circular dependency in the graph. (We do this by
1828 * forward-recursing into the graph starting at <next>, and
1829 * checking whether we can reach <prev>.)
1830 *
1831 * We are using global variables to control the recursion, to
1832 * keep the stackframe size of the recursive functions low:
1833 */
Ming Leidb0002a2009-07-16 15:44:29 +02001834 this.class = hlock_class(next);
1835 this.parent = NULL;
1836 ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1837 if (unlikely(!ret))
1838 return print_circular_bug(&this, target_entry, next, prev);
1839 else if (unlikely(ret < 0))
1840 return print_bfs_bug(ret);
Ming Leic94aa5c2009-07-16 15:44:29 +02001841
Peter Zijlstra8e182572007-07-19 01:48:54 -07001842 if (!check_prev_add_irq(curr, prev, next))
1843 return 0;
1844
1845 /*
1846 * For recursive read-locks we do all the dependency checks,
1847 * but we dont store read-triggered dependencies (only
1848 * write-triggered dependencies). This ensures that only the
1849 * write-side dependencies matter, and that if for example a
1850 * write-lock never takes any other locks, then the reads are
1851 * equivalent to a NOP.
1852 */
1853 if (next->read == 2 || prev->read == 2)
1854 return 1;
1855 /*
1856 * Is the <prev> -> <next> dependency already present?
1857 *
1858 * (this may occur even though this is a new chain: consider
1859 * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1860 * chains - the second one will be new, but L1 already has
1861 * L2 added to its dependency list, due to the first chain.)
1862 */
Dave Jonesf82b2172008-08-11 09:30:23 +02001863 list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1864 if (entry->class == hlock_class(next)) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07001865 if (distance == 1)
1866 entry->distance = 1;
1867 return 2;
1868 }
1869 }
1870
Yong Zhang4726f2a2010-05-04 14:16:48 +08001871 if (!trylock_loop && !save_trace(&trace))
1872 return 0;
1873
Peter Zijlstra8e182572007-07-19 01:48:54 -07001874 /*
1875 * Ok, all validations passed, add the new lock
1876 * to the previous lock's dependency list:
1877 */
Dave Jonesf82b2172008-08-11 09:30:23 +02001878 ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1879 &hlock_class(prev)->locks_after,
Yong Zhang4726f2a2010-05-04 14:16:48 +08001880 next->acquire_ip, distance, &trace);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001881
1882 if (!ret)
1883 return 0;
1884
Dave Jonesf82b2172008-08-11 09:30:23 +02001885 ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1886 &hlock_class(next)->locks_before,
Yong Zhang4726f2a2010-05-04 14:16:48 +08001887 next->acquire_ip, distance, &trace);
Peter Zijlstra8e182572007-07-19 01:48:54 -07001888 if (!ret)
1889 return 0;
1890
1891 /*
1892 * Debugging printouts:
1893 */
Dave Jonesf82b2172008-08-11 09:30:23 +02001894 if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07001895 graph_unlock();
1896 printk("\n new dependency: ");
Dave Jonesf82b2172008-08-11 09:30:23 +02001897 print_lock_name(hlock_class(prev));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001898 printk(" => ");
Dave Jonesf82b2172008-08-11 09:30:23 +02001899 print_lock_name(hlock_class(next));
Peter Zijlstra8e182572007-07-19 01:48:54 -07001900 printk("\n");
1901 dump_stack();
1902 return graph_lock();
1903 }
1904 return 1;
1905}
1906
1907/*
1908 * Add the dependency to all directly-previous locks that are 'relevant'.
1909 * The ones that are relevant are (in increasing distance from curr):
1910 * all consecutive trylock entries and the final non-trylock entry - or
1911 * the end of this context's lock-chain - whichever comes first.
1912 */
1913static int
1914check_prevs_add(struct task_struct *curr, struct held_lock *next)
1915{
1916 int depth = curr->lockdep_depth;
Yong Zhang4726f2a2010-05-04 14:16:48 +08001917 int trylock_loop = 0;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001918 struct held_lock *hlock;
1919
1920 /*
1921 * Debugging checks.
1922 *
1923 * Depth must not be zero for a non-head lock:
1924 */
1925 if (!depth)
1926 goto out_bug;
1927 /*
1928 * At least two relevant locks must exist for this
1929 * to be a head:
1930 */
1931 if (curr->held_locks[depth].irq_context !=
1932 curr->held_locks[depth-1].irq_context)
1933 goto out_bug;
1934
1935 for (;;) {
1936 int distance = curr->lockdep_depth - depth + 1;
1937 hlock = curr->held_locks + depth-1;
1938 /*
1939 * Only non-recursive-read entries get new dependencies
1940 * added:
1941 */
1942 if (hlock->read != 2) {
Yong Zhang4726f2a2010-05-04 14:16:48 +08001943 if (!check_prev_add(curr, hlock, next,
1944 distance, trylock_loop))
Peter Zijlstra8e182572007-07-19 01:48:54 -07001945 return 0;
1946 /*
1947 * Stop after the first non-trylock entry,
1948 * as non-trylock entries have added their
1949 * own direct dependencies already, so this
1950 * lock is connected to them indirectly:
1951 */
1952 if (!hlock->trylock)
1953 break;
1954 }
1955 depth--;
1956 /*
1957 * End of lock-stack?
1958 */
1959 if (!depth)
1960 break;
1961 /*
1962 * Stop the search if we cross into another context:
1963 */
1964 if (curr->held_locks[depth].irq_context !=
1965 curr->held_locks[depth-1].irq_context)
1966 break;
Yong Zhang4726f2a2010-05-04 14:16:48 +08001967 trylock_loop = 1;
Peter Zijlstra8e182572007-07-19 01:48:54 -07001968 }
1969 return 1;
1970out_bug:
1971 if (!debug_locks_off_graph_unlock())
1972 return 0;
1973
Peter Zijlstra0119fee2011-09-02 01:30:29 +02001974 /*
1975 * Clearly we all shouldn't be here, but since we made it we
1976 * can reliable say we messed up our state. See the above two
1977 * gotos for reasons why we could possibly end up here.
1978 */
Peter Zijlstra8e182572007-07-19 01:48:54 -07001979 WARN_ON(1);
1980
1981 return 0;
1982}
1983
1984unsigned long nr_lock_chains;
Huang, Ying443cd502008-06-20 16:39:21 +08001985struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
Huang, Yingcd1a28e2008-06-23 11:20:54 +08001986int nr_chain_hlocks;
Huang, Ying443cd502008-06-20 16:39:21 +08001987static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1988
1989struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
1990{
1991 return lock_classes + chain_hlocks[chain->base + i];
1992}
Peter Zijlstra8e182572007-07-19 01:48:54 -07001993
1994/*
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001995 * Look up a dependency chain. If the key is not present yet then
Jarek Poplawski9e860d02007-05-08 00:30:12 -07001996 * add it and return 1 - in this case the new dependency chain is
1997 * validated. If the key is already hashed, return 0.
1998 * (On return with 1 graph_lock is held.)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07001999 */
Huang, Ying443cd502008-06-20 16:39:21 +08002000static inline int lookup_chain_cache(struct task_struct *curr,
2001 struct held_lock *hlock,
2002 u64 chain_key)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002003{
Dave Jonesf82b2172008-08-11 09:30:23 +02002004 struct lock_class *class = hlock_class(hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002005 struct list_head *hash_head = chainhashentry(chain_key);
2006 struct lock_chain *chain;
Hong Zhiguobfaf4af2013-04-04 15:01:21 +08002007 struct held_lock *hlock_curr;
Steven Rostedte0944ee2011-04-20 21:42:00 -04002008 int i, j;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002009
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002010 /*
2011 * We might need to take the graph lock, ensure we've got IRQs
2012 * disabled to make this an IRQ-safe lock.. for recursion reasons
2013 * lockdep won't complain about its own locking errors.
2014 */
Jarek Poplawski381a2292007-02-10 01:44:58 -08002015 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2016 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002017 /*
2018 * We can walk it lock-free, because entries only get added
2019 * to the hash:
2020 */
2021 list_for_each_entry(chain, hash_head, entry) {
2022 if (chain->chain_key == chain_key) {
2023cache_hit:
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002024 debug_atomic_inc(chain_lookup_hits);
Ingo Molnar81fc6852006-12-13 00:34:40 -08002025 if (very_verbose(class))
Andrew Morton755cd902006-12-29 16:49:14 -08002026 printk("\nhash chain already cached, key: "
2027 "%016Lx tail class: [%p] %s\n",
2028 (unsigned long long)chain_key,
2029 class->key, class->name);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002030 return 0;
2031 }
2032 }
Ingo Molnar81fc6852006-12-13 00:34:40 -08002033 if (very_verbose(class))
Andrew Morton755cd902006-12-29 16:49:14 -08002034 printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
2035 (unsigned long long)chain_key, class->key, class->name);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002036 /*
2037 * Allocate a new chain entry from the static array, and add
2038 * it to the hash:
2039 */
Ingo Molnar74c383f2006-12-13 00:34:43 -08002040 if (!graph_lock())
2041 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002042 /*
2043 * We have to walk the chain again locked - to avoid duplicates:
2044 */
2045 list_for_each_entry(chain, hash_head, entry) {
2046 if (chain->chain_key == chain_key) {
Ingo Molnar74c383f2006-12-13 00:34:43 -08002047 graph_unlock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002048 goto cache_hit;
2049 }
2050 }
2051 if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
Ingo Molnar74c383f2006-12-13 00:34:43 -08002052 if (!debug_locks_off_graph_unlock())
2053 return 0;
2054
Dave Jones2c522832013-04-25 13:40:02 -04002055 print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
Peter Zijlstraeedeeab2009-03-18 12:38:47 +01002056 dump_stack();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002057 return 0;
2058 }
2059 chain = lock_chains + nr_lock_chains++;
2060 chain->chain_key = chain_key;
Huang, Ying443cd502008-06-20 16:39:21 +08002061 chain->irq_context = hlock->irq_context;
2062 /* Find the first held_lock of current chain */
Huang, Ying443cd502008-06-20 16:39:21 +08002063 for (i = curr->lockdep_depth - 1; i >= 0; i--) {
2064 hlock_curr = curr->held_locks + i;
Hong Zhiguobfaf4af2013-04-04 15:01:21 +08002065 if (hlock_curr->irq_context != hlock->irq_context)
Huang, Ying443cd502008-06-20 16:39:21 +08002066 break;
Huang, Ying443cd502008-06-20 16:39:21 +08002067 }
2068 i++;
2069 chain->depth = curr->lockdep_depth + 1 - i;
Steven Rostedte0944ee2011-04-20 21:42:00 -04002070 if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
2071 chain->base = nr_chain_hlocks;
2072 nr_chain_hlocks += chain->depth;
Huang, Ying443cd502008-06-20 16:39:21 +08002073 for (j = 0; j < chain->depth - 1; j++, i++) {
Dave Jonesf82b2172008-08-11 09:30:23 +02002074 int lock_id = curr->held_locks[i].class_idx - 1;
Huang, Ying443cd502008-06-20 16:39:21 +08002075 chain_hlocks[chain->base + j] = lock_id;
2076 }
2077 chain_hlocks[chain->base + j] = class - lock_classes;
2078 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002079 list_add_tail_rcu(&chain->entry, hash_head);
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002080 debug_atomic_inc(chain_lookup_misses);
Peter Zijlstra8e182572007-07-19 01:48:54 -07002081 inc_chains();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002082
2083 return 1;
2084}
Peter Zijlstra8e182572007-07-19 01:48:54 -07002085
2086static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
Johannes Berg4e6045f2007-10-18 23:39:55 -07002087 struct held_lock *hlock, int chain_head, u64 chain_key)
Peter Zijlstra8e182572007-07-19 01:48:54 -07002088{
2089 /*
2090 * Trylock needs to maintain the stack of held locks, but it
2091 * does not add new dependencies, because trylock can be done
2092 * in any order.
2093 *
2094 * We look up the chain_key and do the O(N^2) check and update of
2095 * the dependencies only if this is a new dependency chain.
2096 * (If lookup_chain_cache() returns with 1 it acquires
2097 * graph_lock for us)
2098 */
2099 if (!hlock->trylock && (hlock->check == 2) &&
Huang, Ying443cd502008-06-20 16:39:21 +08002100 lookup_chain_cache(curr, hlock, chain_key)) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07002101 /*
2102 * Check whether last held lock:
2103 *
2104 * - is irq-safe, if this lock is irq-unsafe
2105 * - is softirq-safe, if this lock is hardirq-unsafe
2106 *
2107 * And check whether the new lock's dependency graph
2108 * could lead back to the previous lock.
2109 *
2110 * any of these scenarios could lead to a deadlock. If
2111 * All validations
2112 */
2113 int ret = check_deadlock(curr, hlock, lock, hlock->read);
2114
2115 if (!ret)
2116 return 0;
2117 /*
2118 * Mark recursive read, as we jump over it when
2119 * building dependencies (just like we jump over
2120 * trylock entries):
2121 */
2122 if (ret == 2)
2123 hlock->read = 2;
2124 /*
2125 * Add dependency only if this lock is not the head
2126 * of the chain, and if it's not a secondary read-lock:
2127 */
2128 if (!chain_head && ret != 2)
2129 if (!check_prevs_add(curr, hlock))
2130 return 0;
2131 graph_unlock();
2132 } else
2133 /* after lookup_chain_cache(): */
2134 if (unlikely(!debug_locks))
2135 return 0;
2136
2137 return 1;
2138}
2139#else
2140static inline int validate_chain(struct task_struct *curr,
2141 struct lockdep_map *lock, struct held_lock *hlock,
Gregory Haskins3aa416b2007-10-11 22:11:11 +02002142 int chain_head, u64 chain_key)
Peter Zijlstra8e182572007-07-19 01:48:54 -07002143{
2144 return 1;
2145}
Peter Zijlstraca58abc2007-07-19 01:48:53 -07002146#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002147
2148/*
2149 * We are building curr_chain_key incrementally, so double-check
2150 * it from scratch, to make sure that it's done correctly:
2151 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002152static void check_chain_key(struct task_struct *curr)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002153{
2154#ifdef CONFIG_DEBUG_LOCKDEP
2155 struct held_lock *hlock, *prev_hlock = NULL;
2156 unsigned int i, id;
2157 u64 chain_key = 0;
2158
2159 for (i = 0; i < curr->lockdep_depth; i++) {
2160 hlock = curr->held_locks + i;
2161 if (chain_key != hlock->prev_chain_key) {
2162 debug_locks_off();
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002163 /*
2164 * We got mighty confused, our chain keys don't match
2165 * with what we expect, someone trample on our task state?
2166 */
Arjan van de Ven2df8b1d2008-07-30 12:43:11 -07002167 WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002168 curr->lockdep_depth, i,
2169 (unsigned long long)chain_key,
2170 (unsigned long long)hlock->prev_chain_key);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002171 return;
2172 }
Dave Jonesf82b2172008-08-11 09:30:23 +02002173 id = hlock->class_idx - 1;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002174 /*
2175 * Whoops ran out of static storage again?
2176 */
Jarek Poplawski381a2292007-02-10 01:44:58 -08002177 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2178 return;
2179
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002180 if (prev_hlock && (prev_hlock->irq_context !=
2181 hlock->irq_context))
2182 chain_key = 0;
2183 chain_key = iterate_chain_key(chain_key, id);
2184 prev_hlock = hlock;
2185 }
2186 if (chain_key != curr->curr_chain_key) {
2187 debug_locks_off();
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002188 /*
2189 * More smoking hash instead of calculating it, damn see these
2190 * numbers float.. I bet that a pink elephant stepped on my memory.
2191 */
Arjan van de Ven2df8b1d2008-07-30 12:43:11 -07002192 WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002193 curr->lockdep_depth, i,
2194 (unsigned long long)chain_key,
2195 (unsigned long long)curr->curr_chain_key);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002196 }
2197#endif
2198}
2199
Steven Rostedt282b5c22011-04-20 21:41:59 -04002200static void
2201print_usage_bug_scenario(struct held_lock *lock)
2202{
2203 struct lock_class *class = hlock_class(lock);
2204
2205 printk(" Possible unsafe locking scenario:\n\n");
2206 printk(" CPU0\n");
2207 printk(" ----\n");
2208 printk(" lock(");
2209 __print_lock_name(class);
2210 printk(");\n");
2211 printk(" <Interrupt>\n");
2212 printk(" lock(");
2213 __print_lock_name(class);
2214 printk(");\n");
2215 printk("\n *** DEADLOCK ***\n\n");
2216}
2217
Peter Zijlstra8e182572007-07-19 01:48:54 -07002218static int
2219print_usage_bug(struct task_struct *curr, struct held_lock *this,
2220 enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2221{
2222 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
2223 return 0;
2224
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07002225 printk("\n");
2226 printk("=================================\n");
2227 printk("[ INFO: inconsistent lock state ]\n");
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +01002228 print_kernel_ident();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07002229 printk("---------------------------------\n");
Peter Zijlstra8e182572007-07-19 01:48:54 -07002230
2231 printk("inconsistent {%s} -> {%s} usage.\n",
2232 usage_str[prev_bit], usage_str[new_bit]);
2233
2234 printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07002235 curr->comm, task_pid_nr(curr),
Peter Zijlstra8e182572007-07-19 01:48:54 -07002236 trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2237 trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2238 trace_hardirqs_enabled(curr),
2239 trace_softirqs_enabled(curr));
2240 print_lock(this);
2241
2242 printk("{%s} state was registered at:\n", usage_str[prev_bit]);
Dave Jonesf82b2172008-08-11 09:30:23 +02002243 print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
Peter Zijlstra8e182572007-07-19 01:48:54 -07002244
2245 print_irqtrace_events(curr);
2246 printk("\nother info that might help us debug this:\n");
Steven Rostedt282b5c22011-04-20 21:41:59 -04002247 print_usage_bug_scenario(this);
2248
Peter Zijlstra8e182572007-07-19 01:48:54 -07002249 lockdep_print_held_locks(curr);
2250
2251 printk("\nstack backtrace:\n");
2252 dump_stack();
2253
2254 return 0;
2255}
2256
2257/*
2258 * Print out an error if an invalid bit is set:
2259 */
2260static inline int
2261valid_state(struct task_struct *curr, struct held_lock *this,
2262 enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2263{
Dave Jonesf82b2172008-08-11 09:30:23 +02002264 if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002265 return print_usage_bug(curr, this, bad_bit, new_bit);
2266 return 1;
2267}
2268
2269static int mark_lock(struct task_struct *curr, struct held_lock *this,
2270 enum lock_usage_bit new_bit);
2271
Steven Rostedt81d68a92008-05-12 21:20:42 +02002272#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002273
2274/*
2275 * print irq inversion bug:
2276 */
2277static int
Ming Lei24208ca2009-07-16 15:44:29 +02002278print_irq_inversion_bug(struct task_struct *curr,
2279 struct lock_list *root, struct lock_list *other,
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002280 struct held_lock *this, int forwards,
2281 const char *irqclass)
2282{
Steven Rostedtdad3d742011-04-20 21:41:57 -04002283 struct lock_list *entry = other;
2284 struct lock_list *middle = NULL;
2285 int depth;
2286
Ingo Molnar74c383f2006-12-13 00:34:43 -08002287 if (!debug_locks_off_graph_unlock() || debug_locks_silent)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002288 return 0;
2289
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07002290 printk("\n");
2291 printk("=========================================================\n");
2292 printk("[ INFO: possible irq lock inversion dependency detected ]\n");
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +01002293 print_kernel_ident();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07002294 printk("---------------------------------------------------------\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002295 printk("%s/%d just changed the state of lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07002296 curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002297 print_lock(this);
2298 if (forwards)
Peter Zijlstra26575e22009-03-04 14:53:24 +01002299 printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002300 else
Peter Zijlstra26575e22009-03-04 14:53:24 +01002301 printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
Ming Lei24208ca2009-07-16 15:44:29 +02002302 print_lock_name(other->class);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002303 printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2304
2305 printk("\nother info that might help us debug this:\n");
Steven Rostedtdad3d742011-04-20 21:41:57 -04002306
2307 /* Find a middle lock (if one exists) */
2308 depth = get_lock_depth(other);
2309 do {
2310 if (depth == 0 && (entry != root)) {
2311 printk("lockdep:%s bad path found in chain graph\n", __func__);
2312 break;
2313 }
2314 middle = entry;
2315 entry = get_lock_parent(entry);
2316 depth--;
2317 } while (entry && entry != root && (depth >= 0));
2318 if (forwards)
2319 print_irq_lock_scenario(root, other,
2320 middle ? middle->class : root->class, other->class);
2321 else
2322 print_irq_lock_scenario(other, root,
2323 middle ? middle->class : other->class, root->class);
2324
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002325 lockdep_print_held_locks(curr);
2326
Ming Lei24208ca2009-07-16 15:44:29 +02002327 printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2328 if (!save_trace(&root->trace))
2329 return 0;
2330 print_shortest_lock_dependencies(other, root);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002331
2332 printk("\nstack backtrace:\n");
2333 dump_stack();
2334
2335 return 0;
2336}
2337
2338/*
2339 * Prove that in the forwards-direction subgraph starting at <this>
2340 * there is no lock matching <mask>:
2341 */
2342static int
2343check_usage_forwards(struct task_struct *curr, struct held_lock *this,
2344 enum lock_usage_bit bit, const char *irqclass)
2345{
2346 int ret;
Ming Leid7aaba12009-07-16 15:44:29 +02002347 struct lock_list root;
2348 struct lock_list *uninitialized_var(target_entry);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002349
Ming Leid7aaba12009-07-16 15:44:29 +02002350 root.parent = NULL;
2351 root.class = hlock_class(this);
2352 ret = find_usage_forwards(&root, bit, &target_entry);
Peter Zijlstraaf012962009-07-16 15:44:29 +02002353 if (ret < 0)
2354 return print_bfs_bug(ret);
2355 if (ret == 1)
2356 return ret;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002357
Ming Lei24208ca2009-07-16 15:44:29 +02002358 return print_irq_inversion_bug(curr, &root, target_entry,
Ming Leid7aaba12009-07-16 15:44:29 +02002359 this, 1, irqclass);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002360}
2361
2362/*
2363 * Prove that in the backwards-direction subgraph starting at <this>
2364 * there is no lock matching <mask>:
2365 */
2366static int
2367check_usage_backwards(struct task_struct *curr, struct held_lock *this,
2368 enum lock_usage_bit bit, const char *irqclass)
2369{
2370 int ret;
Ming Leid7aaba12009-07-16 15:44:29 +02002371 struct lock_list root;
2372 struct lock_list *uninitialized_var(target_entry);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002373
Ming Leid7aaba12009-07-16 15:44:29 +02002374 root.parent = NULL;
2375 root.class = hlock_class(this);
2376 ret = find_usage_backwards(&root, bit, &target_entry);
Peter Zijlstraaf012962009-07-16 15:44:29 +02002377 if (ret < 0)
2378 return print_bfs_bug(ret);
2379 if (ret == 1)
2380 return ret;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002381
Ming Lei24208ca2009-07-16 15:44:29 +02002382 return print_irq_inversion_bug(curr, &root, target_entry,
Oleg Nesterov48d50672010-01-26 19:16:41 +01002383 this, 0, irqclass);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002384}
2385
Ingo Molnar3117df02006-12-13 00:34:43 -08002386void print_irqtrace_events(struct task_struct *curr)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002387{
2388 printk("irq event stamp: %u\n", curr->irq_events);
2389 printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2390 print_ip_sym(curr->hardirq_enable_ip);
2391 printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2392 print_ip_sym(curr->hardirq_disable_ip);
2393 printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2394 print_ip_sym(curr->softirq_enable_ip);
2395 printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2396 print_ip_sym(curr->softirq_disable_ip);
2397}
2398
Peter Zijlstracd953022009-01-22 16:38:21 +01002399static int HARDIRQ_verbose(struct lock_class *class)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002400{
Peter Zijlstra8e182572007-07-19 01:48:54 -07002401#if HARDIRQ_VERBOSE
2402 return class_filter(class);
2403#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002404 return 0;
2405}
2406
Peter Zijlstracd953022009-01-22 16:38:21 +01002407static int SOFTIRQ_verbose(struct lock_class *class)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002408{
Peter Zijlstra8e182572007-07-19 01:48:54 -07002409#if SOFTIRQ_VERBOSE
2410 return class_filter(class);
2411#endif
2412 return 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002413}
2414
Peter Zijlstracd953022009-01-22 16:38:21 +01002415static int RECLAIM_FS_verbose(struct lock_class *class)
Nick Piggincf40bd12009-01-21 08:12:39 +01002416{
2417#if RECLAIM_VERBOSE
2418 return class_filter(class);
2419#endif
2420 return 0;
2421}
2422
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002423#define STRICT_READ_CHECKS 1
2424
Peter Zijlstracd953022009-01-22 16:38:21 +01002425static int (*state_verbose_f[])(struct lock_class *class) = {
2426#define LOCKDEP_STATE(__STATE) \
2427 __STATE##_verbose,
2428#include "lockdep_states.h"
2429#undef LOCKDEP_STATE
2430};
2431
2432static inline int state_verbose(enum lock_usage_bit bit,
2433 struct lock_class *class)
2434{
2435 return state_verbose_f[bit >> 2](class);
2436}
2437
Peter Zijlstra42c50d52009-01-22 16:58:16 +01002438typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
2439 enum lock_usage_bit bit, const char *name);
2440
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002441static int
Peter Zijlstra1c21f142009-03-04 13:51:13 +01002442mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2443 enum lock_usage_bit new_bit)
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002444{
Peter Zijlstraf9892092009-01-22 16:09:59 +01002445 int excl_bit = exclusive_bit(new_bit);
Peter Zijlstra9d3651a2009-01-22 17:18:32 +01002446 int read = new_bit & 1;
Peter Zijlstra42c50d52009-01-22 16:58:16 +01002447 int dir = new_bit & 2;
2448
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002449 /*
2450 * mark USED_IN has to look forwards -- to ensure no dependency
2451 * has ENABLED state, which would allow recursion deadlocks.
2452 *
2453 * mark ENABLED has to look backwards -- to ensure no dependee
2454 * has USED_IN state, which, again, would allow recursion deadlocks.
2455 */
Peter Zijlstra42c50d52009-01-22 16:58:16 +01002456 check_usage_f usage = dir ?
2457 check_usage_backwards : check_usage_forwards;
Peter Zijlstraf9892092009-01-22 16:09:59 +01002458
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002459 /*
2460 * Validate that this particular lock does not have conflicting
2461 * usage states.
2462 */
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002463 if (!valid_state(curr, this, new_bit, excl_bit))
2464 return 0;
Peter Zijlstra9d3651a2009-01-22 17:18:32 +01002465
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002466 /*
2467 * Validate that the lock dependencies don't have conflicting usage
2468 * states.
2469 */
2470 if ((!read || !dir || STRICT_READ_CHECKS) &&
Peter Zijlstra1c21f142009-03-04 13:51:13 +01002471 !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002472 return 0;
Peter Zijlstra780e8202009-01-22 16:51:29 +01002473
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002474 /*
2475 * Check for read in write conflicts
2476 */
2477 if (!read) {
2478 if (!valid_state(curr, this, new_bit, excl_bit + 1))
2479 return 0;
2480
2481 if (STRICT_READ_CHECKS &&
Peter Zijlstra4f367d8a2009-01-22 18:10:42 +01002482 !usage(curr, this, excl_bit + 1,
2483 state_name(new_bit + 1)))
Peter Zijlstra38aa2712009-01-27 14:53:50 +01002484 return 0;
2485 }
Peter Zijlstra780e8202009-01-22 16:51:29 +01002486
Peter Zijlstracd953022009-01-22 16:38:21 +01002487 if (state_verbose(new_bit, hlock_class(this)))
Peter Zijlstra6a6904d2009-01-22 16:07:44 +01002488 return 2;
2489
2490 return 1;
2491}
2492
Nick Piggincf40bd12009-01-21 08:12:39 +01002493enum mark_type {
Peter Zijlstra36bfb9b2009-01-22 14:12:41 +01002494#define LOCKDEP_STATE(__STATE) __STATE,
2495#include "lockdep_states.h"
2496#undef LOCKDEP_STATE
Nick Piggincf40bd12009-01-21 08:12:39 +01002497};
2498
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002499/*
2500 * Mark all held locks with a usage bit:
2501 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002502static int
Nick Piggincf40bd12009-01-21 08:12:39 +01002503mark_held_locks(struct task_struct *curr, enum mark_type mark)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002504{
2505 enum lock_usage_bit usage_bit;
2506 struct held_lock *hlock;
2507 int i;
2508
2509 for (i = 0; i < curr->lockdep_depth; i++) {
2510 hlock = curr->held_locks + i;
2511
Peter Zijlstracf2ad4d2009-01-27 13:58:08 +01002512 usage_bit = 2 + (mark << 2); /* ENABLED */
2513 if (hlock->read)
2514 usage_bit += 1; /* READ */
2515
2516 BUG_ON(usage_bit >= LOCK_USAGE_STATES);
Nick Piggincf40bd12009-01-21 08:12:39 +01002517
Peter Zijlstra70a06862011-07-25 12:09:59 +02002518 if (hlock_class(hlock)->key == __lockdep_no_validate__.subkeys)
Peter Zijlstraefbe2ee2011-07-07 11:39:45 +02002519 continue;
2520
Jarek Poplawski4ff773bb2007-05-08 00:31:00 -07002521 if (!mark_lock(curr, hlock, usage_bit))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002522 return 0;
2523 }
2524
2525 return 1;
2526}
2527
2528/*
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002529 * Hardirqs will be enabled:
2530 */
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002531static void __trace_hardirqs_on_caller(unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002532{
2533 struct task_struct *curr = current;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002534
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002535 /* we'll do an OFF -> ON transition: */
2536 curr->hardirqs_enabled = 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002537
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002538 /*
2539 * We are going to turn hardirqs on, so set the
2540 * usage bit for all held locks:
2541 */
Nick Piggincf40bd12009-01-21 08:12:39 +01002542 if (!mark_held_locks(curr, HARDIRQ))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002543 return;
2544 /*
2545 * If we have softirqs enabled, then set the usage
2546 * bit for all held locks. (disabled hardirqs prevented
2547 * this bit from being set before)
2548 */
2549 if (curr->softirqs_enabled)
Nick Piggincf40bd12009-01-21 08:12:39 +01002550 if (!mark_held_locks(curr, SOFTIRQ))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002551 return;
2552
2553 curr->hardirq_enable_ip = ip;
2554 curr->hardirq_enable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002555 debug_atomic_inc(hardirqs_on_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002556}
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002557
2558void trace_hardirqs_on_caller(unsigned long ip)
2559{
2560 time_hardirqs_on(CALLER_ADDR0, ip);
2561
2562 if (unlikely(!debug_locks || current->lockdep_recursion))
2563 return;
2564
Peter Zijlstra7d36b262011-07-26 13:13:44 +02002565 if (unlikely(current->hardirqs_enabled)) {
2566 /*
2567 * Neither irq nor preemption are disabled here
2568 * so this is racy by nature but losing one hit
2569 * in a stat is not a big deal.
2570 */
2571 __debug_atomic_inc(redundant_hardirqs_on);
2572 return;
2573 }
2574
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002575 /*
2576 * We're enabling irqs and according to our state above irqs weren't
2577 * already enabled, yet we find the hardware thinks they are in fact
2578 * enabled.. someone messed up their IRQ state tracing.
2579 */
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002580 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2581 return;
2582
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002583 /*
2584 * See the fine text that goes along with this variable definition.
2585 */
Peter Zijlstra7d36b262011-07-26 13:13:44 +02002586 if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
2587 return;
2588
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002589 /*
2590 * Can't allow enabling interrupts while in an interrupt handler,
2591 * that's general bad form and such. Recursion, limited stack etc..
2592 */
Peter Zijlstra7d36b262011-07-26 13:13:44 +02002593 if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2594 return;
2595
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002596 current->lockdep_recursion = 1;
2597 __trace_hardirqs_on_caller(ip);
2598 current->lockdep_recursion = 0;
2599}
Steven Rostedt81d68a92008-05-12 21:20:42 +02002600EXPORT_SYMBOL(trace_hardirqs_on_caller);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002601
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002602void trace_hardirqs_on(void)
Steven Rostedt81d68a92008-05-12 21:20:42 +02002603{
2604 trace_hardirqs_on_caller(CALLER_ADDR0);
2605}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002606EXPORT_SYMBOL(trace_hardirqs_on);
2607
2608/*
2609 * Hardirqs were disabled:
2610 */
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002611void trace_hardirqs_off_caller(unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002612{
2613 struct task_struct *curr = current;
2614
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002615 time_hardirqs_off(CALLER_ADDR0, ip);
Steven Rostedt81d68a92008-05-12 21:20:42 +02002616
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002617 if (unlikely(!debug_locks || current->lockdep_recursion))
2618 return;
2619
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002620 /*
2621 * So we're supposed to get called after you mask local IRQs, but for
2622 * some reason the hardware doesn't quite think you did a proper job.
2623 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002624 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2625 return;
2626
2627 if (curr->hardirqs_enabled) {
2628 /*
2629 * We have done an ON -> OFF transition:
2630 */
2631 curr->hardirqs_enabled = 0;
Heiko Carstens6afe40b2008-10-28 11:14:58 +01002632 curr->hardirq_disable_ip = ip;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002633 curr->hardirq_disable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002634 debug_atomic_inc(hardirqs_off_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002635 } else
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002636 debug_atomic_inc(redundant_hardirqs_off);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002637}
Steven Rostedt81d68a92008-05-12 21:20:42 +02002638EXPORT_SYMBOL(trace_hardirqs_off_caller);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002639
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002640void trace_hardirqs_off(void)
Steven Rostedt81d68a92008-05-12 21:20:42 +02002641{
2642 trace_hardirqs_off_caller(CALLER_ADDR0);
2643}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002644EXPORT_SYMBOL(trace_hardirqs_off);
2645
2646/*
2647 * Softirqs will be enabled:
2648 */
2649void trace_softirqs_on(unsigned long ip)
2650{
2651 struct task_struct *curr = current;
2652
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002653 if (unlikely(!debug_locks || current->lockdep_recursion))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002654 return;
2655
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002656 /*
2657 * We fancy IRQs being disabled here, see softirq.c, avoids
2658 * funny state and nesting things.
2659 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002660 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2661 return;
2662
2663 if (curr->softirqs_enabled) {
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002664 debug_atomic_inc(redundant_softirqs_on);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002665 return;
2666 }
2667
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002668 current->lockdep_recursion = 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002669 /*
2670 * We'll do an OFF -> ON transition:
2671 */
2672 curr->softirqs_enabled = 1;
2673 curr->softirq_enable_ip = ip;
2674 curr->softirq_enable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002675 debug_atomic_inc(softirqs_on_events);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002676 /*
2677 * We are going to turn softirqs on, so set the
2678 * usage bit for all held locks, if hardirqs are
2679 * enabled too:
2680 */
2681 if (curr->hardirqs_enabled)
Nick Piggincf40bd12009-01-21 08:12:39 +01002682 mark_held_locks(curr, SOFTIRQ);
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002683 current->lockdep_recursion = 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002684}
2685
2686/*
2687 * Softirqs were disabled:
2688 */
2689void trace_softirqs_off(unsigned long ip)
2690{
2691 struct task_struct *curr = current;
2692
Peter Zijlstradd4e5d32011-06-21 17:17:27 +02002693 if (unlikely(!debug_locks || current->lockdep_recursion))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002694 return;
2695
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002696 /*
2697 * We fancy IRQs being disabled here, see softirq.c
2698 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002699 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2700 return;
2701
2702 if (curr->softirqs_enabled) {
2703 /*
2704 * We have done an ON -> OFF transition:
2705 */
2706 curr->softirqs_enabled = 0;
2707 curr->softirq_disable_ip = ip;
2708 curr->softirq_disable_event = ++curr->irq_events;
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002709 debug_atomic_inc(softirqs_off_events);
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002710 /*
2711 * Whoops, we wanted softirqs off, so why aren't they?
2712 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002713 DEBUG_LOCKS_WARN_ON(!softirq_count());
2714 } else
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002715 debug_atomic_inc(redundant_softirqs_off);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002716}
2717
Peter Zijlstra2f850182009-03-20 11:13:20 +01002718static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
Nick Piggincf40bd12009-01-21 08:12:39 +01002719{
2720 struct task_struct *curr = current;
2721
2722 if (unlikely(!debug_locks))
2723 return;
2724
2725 /* no reclaim without waiting on it */
2726 if (!(gfp_mask & __GFP_WAIT))
2727 return;
2728
2729 /* this guy won't enter reclaim */
2730 if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2731 return;
2732
2733 /* We're only interested __GFP_FS allocations for now */
2734 if (!(gfp_mask & __GFP_FS))
2735 return;
2736
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002737 /*
2738 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
2739 */
Peter Zijlstra2f850182009-03-20 11:13:20 +01002740 if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
Nick Piggincf40bd12009-01-21 08:12:39 +01002741 return;
2742
2743 mark_held_locks(curr, RECLAIM_FS);
2744}
2745
Peter Zijlstra2f850182009-03-20 11:13:20 +01002746static void check_flags(unsigned long flags);
2747
2748void lockdep_trace_alloc(gfp_t gfp_mask)
2749{
2750 unsigned long flags;
2751
2752 if (unlikely(current->lockdep_recursion))
2753 return;
2754
2755 raw_local_irq_save(flags);
2756 check_flags(flags);
2757 current->lockdep_recursion = 1;
2758 __lockdep_trace_alloc(gfp_mask, flags);
2759 current->lockdep_recursion = 0;
2760 raw_local_irq_restore(flags);
2761}
2762
Peter Zijlstra8e182572007-07-19 01:48:54 -07002763static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
2764{
2765 /*
2766 * If non-trylock use in a hardirq or softirq context, then
2767 * mark the lock as used in these contexts:
2768 */
2769 if (!hlock->trylock) {
2770 if (hlock->read) {
2771 if (curr->hardirq_context)
2772 if (!mark_lock(curr, hlock,
2773 LOCK_USED_IN_HARDIRQ_READ))
2774 return 0;
2775 if (curr->softirq_context)
2776 if (!mark_lock(curr, hlock,
2777 LOCK_USED_IN_SOFTIRQ_READ))
2778 return 0;
2779 } else {
2780 if (curr->hardirq_context)
2781 if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2782 return 0;
2783 if (curr->softirq_context)
2784 if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2785 return 0;
2786 }
2787 }
2788 if (!hlock->hardirqs_off) {
2789 if (hlock->read) {
2790 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002791 LOCK_ENABLED_HARDIRQ_READ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002792 return 0;
2793 if (curr->softirqs_enabled)
2794 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002795 LOCK_ENABLED_SOFTIRQ_READ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002796 return 0;
2797 } else {
2798 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002799 LOCK_ENABLED_HARDIRQ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002800 return 0;
2801 if (curr->softirqs_enabled)
2802 if (!mark_lock(curr, hlock,
Peter Zijlstra4fc95e82009-01-22 13:10:52 +01002803 LOCK_ENABLED_SOFTIRQ))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002804 return 0;
2805 }
2806 }
2807
Nick Piggincf40bd12009-01-21 08:12:39 +01002808 /*
2809 * We reuse the irq context infrastructure more broadly as a general
2810 * context checking code. This tests GFP_FS recursion (a lock taken
2811 * during reclaim for a GFP_FS allocation is held over a GFP_FS
2812 * allocation).
2813 */
2814 if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2815 if (hlock->read) {
2816 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2817 return 0;
2818 } else {
2819 if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2820 return 0;
2821 }
2822 }
2823
Peter Zijlstra8e182572007-07-19 01:48:54 -07002824 return 1;
2825}
2826
2827static int separate_irq_context(struct task_struct *curr,
2828 struct held_lock *hlock)
2829{
2830 unsigned int depth = curr->lockdep_depth;
2831
2832 /*
2833 * Keep track of points where we cross into an interrupt context:
2834 */
2835 hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2836 curr->softirq_context;
2837 if (depth) {
2838 struct held_lock *prev_hlock;
2839
2840 prev_hlock = curr->held_locks + depth-1;
2841 /*
2842 * If we cross into another context, reset the
2843 * hash key (this also prevents the checking and the
2844 * adding of the dependency to 'prev'):
2845 */
2846 if (prev_hlock->irq_context != hlock->irq_context)
2847 return 1;
2848 }
2849 return 0;
2850}
2851
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002852#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
Peter Zijlstra8e182572007-07-19 01:48:54 -07002853
2854static inline
2855int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
2856 enum lock_usage_bit new_bit)
2857{
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002858 WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
Peter Zijlstra8e182572007-07-19 01:48:54 -07002859 return 1;
2860}
2861
2862static inline int mark_irqflags(struct task_struct *curr,
2863 struct held_lock *hlock)
2864{
2865 return 1;
2866}
2867
2868static inline int separate_irq_context(struct task_struct *curr,
2869 struct held_lock *hlock)
2870{
2871 return 0;
2872}
2873
Peter Zijlstra868a23a2009-02-15 00:25:21 +01002874void lockdep_trace_alloc(gfp_t gfp_mask)
2875{
2876}
2877
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002878#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002879
2880/*
Peter Zijlstra8e182572007-07-19 01:48:54 -07002881 * Mark a lock with a usage bit, and validate the state transition:
2882 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02002883static int mark_lock(struct task_struct *curr, struct held_lock *this,
Steven Rostedt0764d232008-05-12 21:20:44 +02002884 enum lock_usage_bit new_bit)
Peter Zijlstra8e182572007-07-19 01:48:54 -07002885{
2886 unsigned int new_mask = 1 << new_bit, ret = 1;
2887
2888 /*
2889 * If already set then do not dirty the cacheline,
2890 * nor do any checks:
2891 */
Dave Jonesf82b2172008-08-11 09:30:23 +02002892 if (likely(hlock_class(this)->usage_mask & new_mask))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002893 return 1;
2894
2895 if (!graph_lock())
2896 return 0;
2897 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03002898 * Make sure we didn't race:
Peter Zijlstra8e182572007-07-19 01:48:54 -07002899 */
Dave Jonesf82b2172008-08-11 09:30:23 +02002900 if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
Peter Zijlstra8e182572007-07-19 01:48:54 -07002901 graph_unlock();
2902 return 1;
2903 }
2904
Dave Jonesf82b2172008-08-11 09:30:23 +02002905 hlock_class(this)->usage_mask |= new_mask;
Peter Zijlstra8e182572007-07-19 01:48:54 -07002906
Dave Jonesf82b2172008-08-11 09:30:23 +02002907 if (!save_trace(hlock_class(this)->usage_traces + new_bit))
Peter Zijlstra8e182572007-07-19 01:48:54 -07002908 return 0;
2909
2910 switch (new_bit) {
Peter Zijlstra53464172009-01-22 14:15:53 +01002911#define LOCKDEP_STATE(__STATE) \
2912 case LOCK_USED_IN_##__STATE: \
2913 case LOCK_USED_IN_##__STATE##_READ: \
2914 case LOCK_ENABLED_##__STATE: \
2915 case LOCK_ENABLED_##__STATE##_READ:
2916#include "lockdep_states.h"
2917#undef LOCKDEP_STATE
Peter Zijlstra8e182572007-07-19 01:48:54 -07002918 ret = mark_lock_irq(curr, this, new_bit);
2919 if (!ret)
2920 return 0;
2921 break;
2922 case LOCK_USED:
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02002923 debug_atomic_dec(nr_unused_locks);
Peter Zijlstra8e182572007-07-19 01:48:54 -07002924 break;
2925 default:
2926 if (!debug_locks_off_graph_unlock())
2927 return 0;
2928 WARN_ON(1);
2929 return 0;
2930 }
2931
2932 graph_unlock();
2933
2934 /*
2935 * We must printk outside of the graph_lock:
2936 */
2937 if (ret == 2) {
2938 printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2939 print_lock(this);
2940 print_irqtrace_events(curr);
2941 dump_stack();
2942 }
2943
2944 return ret;
2945}
2946
2947/*
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002948 * Initialize a lock instance's lock-class mapping info:
2949 */
2950void lockdep_init_map(struct lockdep_map *lock, const char *name,
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04002951 struct lock_class_key *key, int subclass)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002952{
Yong Zhangd3d03d42011-11-09 16:04:51 +08002953 int i;
2954
2955 kmemcheck_mark_initialized(lock, sizeof(*lock));
2956
2957 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
2958 lock->class_cache[i] = NULL;
Hitoshi Mitake62016252010-10-05 18:01:51 +09002959
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002960#ifdef CONFIG_LOCK_STAT
2961 lock->cpu = raw_smp_processor_id();
2962#endif
2963
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002964 /*
2965 * Can't be having no nameless bastards around this place!
2966 */
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002967 if (DEBUG_LOCKS_WARN_ON(!name)) {
2968 lock->name = "NULL";
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002969 return;
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002970 }
2971
2972 lock->name = name;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002973
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002974 /*
2975 * No key, no joy, we need to hash something.
2976 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002977 if (DEBUG_LOCKS_WARN_ON(!key))
2978 return;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002979 /*
2980 * Sanity check, the lock-class key must be persistent:
2981 */
2982 if (!static_obj(key)) {
2983 printk("BUG: key %p not in .data!\n", key);
Peter Zijlstra0119fee2011-09-02 01:30:29 +02002984 /*
2985 * What it says above ^^^^^, I suggest you read it.
2986 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002987 DEBUG_LOCKS_WARN_ON(1);
2988 return;
2989 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002990 lock->key = key;
Peter Zijlstrac8a25002009-04-17 09:40:49 +02002991
2992 if (unlikely(!debug_locks))
2993 return;
2994
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04002995 if (subclass)
2996 register_lock_class(lock, subclass, 1);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002997}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07002998EXPORT_SYMBOL_GPL(lockdep_init_map);
2999
Peter Zijlstra1704f472010-03-19 01:37:42 +01003000struct lock_class_key __lockdep_no_validate__;
Kent Overstreetea6749c2012-12-27 22:21:58 -08003001EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
Peter Zijlstra1704f472010-03-19 01:37:42 +01003002
Maarten Lankhorstd0945952012-09-13 11:39:51 +02003003static int
3004print_lock_nested_lock_not_held(struct task_struct *curr,
3005 struct held_lock *hlock,
3006 unsigned long ip)
3007{
3008 if (!debug_locks_off())
3009 return 0;
3010 if (debug_locks_silent)
3011 return 0;
3012
3013 printk("\n");
3014 printk("==================================\n");
3015 printk("[ BUG: Nested lock was not taken ]\n");
3016 print_kernel_ident();
3017 printk("----------------------------------\n");
3018
3019 printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
3020 print_lock(hlock);
3021
3022 printk("\nbut this task is not holding:\n");
3023 printk("%s\n", hlock->nest_lock->name);
3024
3025 printk("\nstack backtrace:\n");
3026 dump_stack();
3027
3028 printk("\nother info that might help us debug this:\n");
3029 lockdep_print_held_locks(curr);
3030
3031 printk("\nstack backtrace:\n");
3032 dump_stack();
3033
3034 return 0;
3035}
3036
3037static int __lock_is_held(struct lockdep_map *lock);
3038
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003039/*
3040 * This gets called for every mutex_lock*()/spin_lock*() operation.
3041 * We maintain the dependency maps and validate the locking attempt:
3042 */
3043static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3044 int trylock, int read, int check, int hardirqs_off,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003045 struct lockdep_map *nest_lock, unsigned long ip,
3046 int references)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003047{
3048 struct task_struct *curr = current;
Ingo Molnard6d897c2006-07-10 04:44:04 -07003049 struct lock_class *class = NULL;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003050 struct held_lock *hlock;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003051 unsigned int depth, id;
3052 int chain_head = 0;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003053 int class_idx;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003054 u64 chain_key;
3055
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003056 if (!prove_locking)
3057 check = 1;
3058
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003059 if (unlikely(!debug_locks))
3060 return 0;
3061
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003062 /*
3063 * Lockdep should run with IRQs disabled, otherwise we could
3064 * get an interrupt which would want to take locks, which would
3065 * end up in lockdep and have you got a head-ache already?
3066 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003067 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3068 return 0;
3069
Peter Zijlstra1704f472010-03-19 01:37:42 +01003070 if (lock->key == &__lockdep_no_validate__)
3071 check = 1;
3072
Hitoshi Mitake62016252010-10-05 18:01:51 +09003073 if (subclass < NR_LOCKDEP_CACHING_CLASSES)
3074 class = lock->class_cache[subclass];
Ingo Molnard6d897c2006-07-10 04:44:04 -07003075 /*
Hitoshi Mitake62016252010-10-05 18:01:51 +09003076 * Not cached?
Ingo Molnard6d897c2006-07-10 04:44:04 -07003077 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003078 if (unlikely(!class)) {
Peter Zijlstra4dfbb9d2006-10-11 01:45:14 -04003079 class = register_lock_class(lock, subclass, 0);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003080 if (!class)
3081 return 0;
3082 }
Frederic Weisbeckerbd6d29c2010-04-06 00:10:17 +02003083 atomic_inc((atomic_t *)&class->ops);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003084 if (very_verbose(class)) {
3085 printk("\nacquire class [%p] %s", class->key, class->name);
3086 if (class->name_version > 1)
3087 printk("#%d", class->name_version);
3088 printk("\n");
3089 dump_stack();
3090 }
3091
3092 /*
3093 * Add the lock to the list of currently held locks.
3094 * (we dont increase the depth just yet, up until the
3095 * dependency checks are done)
3096 */
3097 depth = curr->lockdep_depth;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003098 /*
3099 * Ran out of static storage for our per-task lock stack again have we?
3100 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003101 if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
3102 return 0;
3103
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003104 class_idx = class - lock_classes + 1;
3105
3106 if (depth) {
3107 hlock = curr->held_locks + depth - 1;
3108 if (hlock->class_idx == class_idx && nest_lock) {
3109 if (hlock->references)
3110 hlock->references++;
3111 else
3112 hlock->references = 2;
3113
3114 return 1;
3115 }
3116 }
3117
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003118 hlock = curr->held_locks + depth;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003119 /*
3120 * Plain impossible, we just registered it and checked it weren't no
3121 * NULL like.. I bet this mushroom I ate was good!
3122 */
Dave Jonesf82b2172008-08-11 09:30:23 +02003123 if (DEBUG_LOCKS_WARN_ON(!class))
3124 return 0;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003125 hlock->class_idx = class_idx;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003126 hlock->acquire_ip = ip;
3127 hlock->instance = lock;
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02003128 hlock->nest_lock = nest_lock;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003129 hlock->trylock = trylock;
3130 hlock->read = read;
3131 hlock->check = check;
Dmitry Baryshkov6951b122008-08-18 04:26:37 +04003132 hlock->hardirqs_off = !!hardirqs_off;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003133 hlock->references = references;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003134#ifdef CONFIG_LOCK_STAT
3135 hlock->waittime_stamp = 0;
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003136 hlock->holdtime_stamp = lockstat_clock();
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003137#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003138
Peter Zijlstra8e182572007-07-19 01:48:54 -07003139 if (check == 2 && !mark_irqflags(curr, hlock))
3140 return 0;
3141
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003142 /* mark it as used: */
Jarek Poplawski4ff773bb2007-05-08 00:31:00 -07003143 if (!mark_lock(curr, hlock, LOCK_USED))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003144 return 0;
Peter Zijlstra8e182572007-07-19 01:48:54 -07003145
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003146 /*
Gautham R Shenoy17aacfb2007-10-28 20:47:01 +01003147 * Calculate the chain hash: it's the combined hash of all the
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003148 * lock keys along the dependency chain. We save the hash value
3149 * at every step so that we can get the current hash easily
3150 * after unlock. The chain hash is then used to cache dependency
3151 * results.
3152 *
3153 * The 'key ID' is what is the most compact key value to drive
3154 * the hash, not class->key.
3155 */
3156 id = class - lock_classes;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003157 /*
3158 * Whoops, we did it again.. ran straight out of our static allocation.
3159 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003160 if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
3161 return 0;
3162
3163 chain_key = curr->curr_chain_key;
3164 if (!depth) {
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003165 /*
3166 * How can we have a chain hash when we ain't got no keys?!
3167 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003168 if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
3169 return 0;
3170 chain_head = 1;
3171 }
3172
3173 hlock->prev_chain_key = chain_key;
Peter Zijlstra8e182572007-07-19 01:48:54 -07003174 if (separate_irq_context(curr, hlock)) {
3175 chain_key = 0;
3176 chain_head = 1;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003177 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003178 chain_key = iterate_chain_key(chain_key, id);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003179
Maarten Lankhorstd0945952012-09-13 11:39:51 +02003180 if (nest_lock && !__lock_is_held(nest_lock))
3181 return print_lock_nested_lock_not_held(curr, hlock, ip);
3182
Gregory Haskins3aa416b2007-10-11 22:11:11 +02003183 if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
Peter Zijlstra8e182572007-07-19 01:48:54 -07003184 return 0;
Jarek Poplawski381a2292007-02-10 01:44:58 -08003185
Gregory Haskins3aa416b2007-10-11 22:11:11 +02003186 curr->curr_chain_key = chain_key;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003187 curr->lockdep_depth++;
3188 check_chain_key(curr);
Jarek Poplawski60e114d2007-02-20 13:58:00 -08003189#ifdef CONFIG_DEBUG_LOCKDEP
3190 if (unlikely(!debug_locks))
3191 return 0;
3192#endif
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003193 if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
3194 debug_locks_off();
Dave Jones2c522832013-04-25 13:40:02 -04003195 print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
3196 printk(KERN_DEBUG "depth: %i max: %lu!\n",
Ben Greearc0540602013-02-06 10:56:19 -08003197 curr->lockdep_depth, MAX_LOCK_DEPTH);
Ben Greearc0540602013-02-06 10:56:19 -08003198
3199 lockdep_print_held_locks(current);
3200 debug_show_all_locks();
Peter Zijlstraeedeeab2009-03-18 12:38:47 +01003201 dump_stack();
Ben Greearc0540602013-02-06 10:56:19 -08003202
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003203 return 0;
3204 }
Jarek Poplawski381a2292007-02-10 01:44:58 -08003205
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003206 if (unlikely(curr->lockdep_depth > max_lockdep_depth))
3207 max_lockdep_depth = curr->lockdep_depth;
3208
3209 return 1;
3210}
3211
3212static int
Srivatsa S. Bhatf86f7552013-01-08 18:35:58 +05303213print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003214 unsigned long ip)
3215{
3216 if (!debug_locks_off())
3217 return 0;
3218 if (debug_locks_silent)
3219 return 0;
3220
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07003221 printk("\n");
3222 printk("=====================================\n");
3223 printk("[ BUG: bad unlock balance detected! ]\n");
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +01003224 print_kernel_ident();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07003225 printk("-------------------------------------\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003226 printk("%s/%d is trying to release lock (",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003227 curr->comm, task_pid_nr(curr));
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003228 print_lockdep_cache(lock);
3229 printk(") at:\n");
3230 print_ip_sym(ip);
3231 printk("but there are no more locks to release!\n");
3232 printk("\nother info that might help us debug this:\n");
3233 lockdep_print_held_locks(curr);
3234
3235 printk("\nstack backtrace:\n");
3236 dump_stack();
3237
3238 return 0;
3239}
3240
3241/*
3242 * Common debugging checks for both nested and non-nested unlock:
3243 */
3244static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
3245 unsigned long ip)
3246{
3247 if (unlikely(!debug_locks))
3248 return 0;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003249 /*
3250 * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
3251 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003252 if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
3253 return 0;
3254
3255 if (curr->lockdep_depth <= 0)
Srivatsa S. Bhatf86f7552013-01-08 18:35:58 +05303256 return print_unlock_imbalance_bug(curr, lock, ip);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003257
3258 return 1;
3259}
3260
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003261static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
3262{
3263 if (hlock->instance == lock)
3264 return 1;
3265
3266 if (hlock->references) {
Hitoshi Mitake62016252010-10-05 18:01:51 +09003267 struct lock_class *class = lock->class_cache[0];
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003268
3269 if (!class)
3270 class = look_up_lock_class(lock, 0);
3271
Peter Zijlstra80e04012011-08-05 14:26:17 +02003272 /*
3273 * If look_up_lock_class() failed to find a class, we're trying
3274 * to test if we hold a lock that has never yet been acquired.
3275 * Clearly if the lock hasn't been acquired _ever_, we're not
3276 * holding it either, so report failure.
3277 */
3278 if (!class)
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003279 return 0;
3280
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003281 /*
3282 * References, but not a lock we're actually ref-counting?
3283 * State got messed up, follow the sites that change ->references
3284 * and try to make sense of it.
3285 */
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003286 if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
3287 return 0;
3288
3289 if (hlock->class_idx == class - lock_classes + 1)
3290 return 1;
3291 }
3292
3293 return 0;
3294}
3295
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003296static int
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003297__lock_set_class(struct lockdep_map *lock, const char *name,
3298 struct lock_class_key *key, unsigned int subclass,
3299 unsigned long ip)
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003300{
3301 struct task_struct *curr = current;
3302 struct held_lock *hlock, *prev_hlock;
3303 struct lock_class *class;
3304 unsigned int depth;
3305 int i;
3306
3307 depth = curr->lockdep_depth;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003308 /*
3309 * This function is about (re)setting the class of a held lock,
3310 * yet we're not actually holding any locks. Naughty user!
3311 */
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003312 if (DEBUG_LOCKS_WARN_ON(!depth))
3313 return 0;
3314
3315 prev_hlock = NULL;
3316 for (i = depth-1; i >= 0; i--) {
3317 hlock = curr->held_locks + i;
3318 /*
3319 * We must not cross into another context:
3320 */
3321 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3322 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003323 if (match_held_lock(hlock, lock))
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003324 goto found_it;
3325 prev_hlock = hlock;
3326 }
Srivatsa S. Bhatf86f7552013-01-08 18:35:58 +05303327 return print_unlock_imbalance_bug(curr, lock, ip);
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003328
3329found_it:
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003330 lockdep_init_map(lock, name, key, 0);
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003331 class = register_lock_class(lock, subclass, 0);
Dave Jonesf82b2172008-08-11 09:30:23 +02003332 hlock->class_idx = class - lock_classes + 1;
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003333
3334 curr->lockdep_depth = i;
3335 curr->curr_chain_key = hlock->prev_chain_key;
3336
3337 for (; i < depth; i++) {
3338 hlock = curr->held_locks + i;
3339 if (!__lock_acquire(hlock->instance,
Dave Jonesf82b2172008-08-11 09:30:23 +02003340 hlock_class(hlock)->subclass, hlock->trylock,
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003341 hlock->read, hlock->check, hlock->hardirqs_off,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003342 hlock->nest_lock, hlock->acquire_ip,
3343 hlock->references))
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003344 return 0;
3345 }
3346
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003347 /*
3348 * I took it apart and put it back together again, except now I have
3349 * these 'spare' parts.. where shall I put them.
3350 */
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003351 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
3352 return 0;
3353 return 1;
3354}
3355
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003356/*
3357 * Remove the lock to the list of currently held locks in a
3358 * potentially non-nested (out of order) manner. This is a
3359 * relatively rare operation, as all the unlock APIs default
3360 * to nested mode (which uses lock_release()):
3361 */
3362static int
3363lock_release_non_nested(struct task_struct *curr,
3364 struct lockdep_map *lock, unsigned long ip)
3365{
3366 struct held_lock *hlock, *prev_hlock;
3367 unsigned int depth;
3368 int i;
3369
3370 /*
3371 * Check whether the lock exists in the current stack
3372 * of held locks:
3373 */
3374 depth = curr->lockdep_depth;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003375 /*
3376 * So we're all set to release this lock.. wait what lock? We don't
3377 * own any locks, you've been drinking again?
3378 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003379 if (DEBUG_LOCKS_WARN_ON(!depth))
3380 return 0;
3381
3382 prev_hlock = NULL;
3383 for (i = depth-1; i >= 0; i--) {
3384 hlock = curr->held_locks + i;
3385 /*
3386 * We must not cross into another context:
3387 */
3388 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3389 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003390 if (match_held_lock(hlock, lock))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003391 goto found_it;
3392 prev_hlock = hlock;
3393 }
Srivatsa S. Bhatf86f7552013-01-08 18:35:58 +05303394 return print_unlock_imbalance_bug(curr, lock, ip);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003395
3396found_it:
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003397 if (hlock->instance == lock)
3398 lock_release_holdtime(hlock);
3399
3400 if (hlock->references) {
3401 hlock->references--;
3402 if (hlock->references) {
3403 /*
3404 * We had, and after removing one, still have
3405 * references, the current lock stack is still
3406 * valid. We're done!
3407 */
3408 return 1;
3409 }
3410 }
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003411
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003412 /*
3413 * We have the right lock to unlock, 'hlock' points to it.
3414 * Now we remove it from the stack, and add back the other
3415 * entries (if any), recalculating the hash along the way:
3416 */
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003417
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003418 curr->lockdep_depth = i;
3419 curr->curr_chain_key = hlock->prev_chain_key;
3420
3421 for (i++; i < depth; i++) {
3422 hlock = curr->held_locks + i;
3423 if (!__lock_acquire(hlock->instance,
Dave Jonesf82b2172008-08-11 09:30:23 +02003424 hlock_class(hlock)->subclass, hlock->trylock,
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003425 hlock->read, hlock->check, hlock->hardirqs_off,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003426 hlock->nest_lock, hlock->acquire_ip,
3427 hlock->references))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003428 return 0;
3429 }
3430
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003431 /*
3432 * We had N bottles of beer on the wall, we drank one, but now
3433 * there's not N-1 bottles of beer left on the wall...
3434 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003435 if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3436 return 0;
3437 return 1;
3438}
3439
3440/*
3441 * Remove the lock to the list of currently held locks - this gets
3442 * called on mutex_unlock()/spin_unlock*() (or on a failed
3443 * mutex_lock_interruptible()). This is done for unlocks that nest
3444 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3445 */
3446static int lock_release_nested(struct task_struct *curr,
3447 struct lockdep_map *lock, unsigned long ip)
3448{
3449 struct held_lock *hlock;
3450 unsigned int depth;
3451
3452 /*
3453 * Pop off the top of the lock stack:
3454 */
3455 depth = curr->lockdep_depth - 1;
3456 hlock = curr->held_locks + depth;
3457
3458 /*
3459 * Is the unlock non-nested:
3460 */
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003461 if (hlock->instance != lock || hlock->references)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003462 return lock_release_non_nested(curr, lock, ip);
3463 curr->lockdep_depth--;
3464
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003465 /*
3466 * No more locks, but somehow we've got hash left over, who left it?
3467 */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003468 if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3469 return 0;
3470
3471 curr->curr_chain_key = hlock->prev_chain_key;
3472
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003473 lock_release_holdtime(hlock);
3474
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003475#ifdef CONFIG_DEBUG_LOCKDEP
3476 hlock->prev_chain_key = 0;
Dave Jonesf82b2172008-08-11 09:30:23 +02003477 hlock->class_idx = 0;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003478 hlock->acquire_ip = 0;
3479 hlock->irq_context = 0;
3480#endif
3481 return 1;
3482}
3483
3484/*
3485 * Remove the lock to the list of currently held locks - this gets
3486 * called on mutex_unlock()/spin_unlock*() (or on a failed
3487 * mutex_lock_interruptible()). This is done for unlocks that nest
3488 * perfectly. (i.e. the current top of the lock-stack is unlocked)
3489 */
3490static void
3491__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3492{
3493 struct task_struct *curr = current;
3494
3495 if (!check_unlock(curr, lock, ip))
3496 return;
3497
3498 if (nested) {
3499 if (!lock_release_nested(curr, lock, ip))
3500 return;
3501 } else {
3502 if (!lock_release_non_nested(curr, lock, ip))
3503 return;
3504 }
3505
3506 check_chain_key(curr);
3507}
3508
Peter Zijlstraf607c662009-07-20 19:16:29 +02003509static int __lock_is_held(struct lockdep_map *lock)
3510{
3511 struct task_struct *curr = current;
3512 int i;
3513
3514 for (i = 0; i < curr->lockdep_depth; i++) {
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003515 struct held_lock *hlock = curr->held_locks + i;
3516
3517 if (match_held_lock(hlock, lock))
Peter Zijlstraf607c662009-07-20 19:16:29 +02003518 return 1;
3519 }
3520
3521 return 0;
3522}
3523
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003524/*
3525 * Check whether we follow the irq-flags state precisely:
3526 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02003527static void check_flags(unsigned long flags)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003528{
Ingo Molnar992860e2008-07-14 10:28:38 +02003529#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3530 defined(CONFIG_TRACE_IRQFLAGS)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003531 if (!debug_locks)
3532 return;
3533
Ingo Molnar5f9fa8a2007-12-07 19:02:47 +01003534 if (irqs_disabled_flags(flags)) {
3535 if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3536 printk("possible reason: unannotated irqs-off.\n");
3537 }
3538 } else {
3539 if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3540 printk("possible reason: unannotated irqs-on.\n");
3541 }
3542 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003543
3544 /*
3545 * We dont accurately track softirq state in e.g.
3546 * hardirq contexts (such as on 4KSTACKS), so only
3547 * check if not in hardirq contexts:
3548 */
3549 if (!hardirq_count()) {
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003550 if (softirq_count()) {
3551 /* like the above, but with softirqs */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003552 DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003553 } else {
3554 /* lick the above, does it taste good? */
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003555 DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003556 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003557 }
3558
3559 if (!debug_locks)
3560 print_irqtrace_events(current);
3561#endif
3562}
3563
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003564void lock_set_class(struct lockdep_map *lock, const char *name,
3565 struct lock_class_key *key, unsigned int subclass,
3566 unsigned long ip)
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003567{
3568 unsigned long flags;
3569
3570 if (unlikely(current->lockdep_recursion))
3571 return;
3572
3573 raw_local_irq_save(flags);
3574 current->lockdep_recursion = 1;
3575 check_flags(flags);
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003576 if (__lock_set_class(lock, name, key, subclass, ip))
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003577 check_chain_key(current);
3578 current->lockdep_recursion = 0;
3579 raw_local_irq_restore(flags);
3580}
Peter Zijlstra00ef9f72008-12-04 09:00:17 +01003581EXPORT_SYMBOL_GPL(lock_set_class);
Peter Zijlstra64aa3482008-08-11 09:30:21 +02003582
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003583/*
3584 * We are not always called with irqs disabled - do that here,
3585 * and also avoid lockdep recursion:
3586 */
Steven Rostedt1d09daa2008-05-12 21:20:55 +02003587void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
Peter Zijlstra7531e2f2008-08-11 09:30:24 +02003588 int trylock, int read, int check,
3589 struct lockdep_map *nest_lock, unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003590{
3591 unsigned long flags;
3592
3593 if (unlikely(current->lockdep_recursion))
3594 return;
3595
3596 raw_local_irq_save(flags);
3597 check_flags(flags);
3598
3599 current->lockdep_recursion = 1;
Frederic Weisbeckerdb2c4c72010-02-02 23:34:40 +01003600 trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003601 __lock_acquire(lock, subclass, trylock, read, check,
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003602 irqs_disabled_flags(flags), nest_lock, ip, 0);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003603 current->lockdep_recursion = 0;
3604 raw_local_irq_restore(flags);
3605}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003606EXPORT_SYMBOL_GPL(lock_acquire);
3607
Steven Rostedt1d09daa2008-05-12 21:20:55 +02003608void lock_release(struct lockdep_map *lock, int nested,
Steven Rostedt0764d232008-05-12 21:20:44 +02003609 unsigned long ip)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003610{
3611 unsigned long flags;
3612
3613 if (unlikely(current->lockdep_recursion))
3614 return;
3615
3616 raw_local_irq_save(flags);
3617 check_flags(flags);
3618 current->lockdep_recursion = 1;
Frederic Weisbecker93135432010-05-08 06:24:25 +02003619 trace_lock_release(lock, ip);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003620 __lock_release(lock, nested, ip);
3621 current->lockdep_recursion = 0;
3622 raw_local_irq_restore(flags);
3623}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003624EXPORT_SYMBOL_GPL(lock_release);
3625
Peter Zijlstraf607c662009-07-20 19:16:29 +02003626int lock_is_held(struct lockdep_map *lock)
3627{
3628 unsigned long flags;
3629 int ret = 0;
3630
3631 if (unlikely(current->lockdep_recursion))
Peter Zijlstraf2513cd2011-06-06 12:32:43 +02003632 return 1; /* avoid false negative lockdep_assert_held() */
Peter Zijlstraf607c662009-07-20 19:16:29 +02003633
3634 raw_local_irq_save(flags);
3635 check_flags(flags);
3636
3637 current->lockdep_recursion = 1;
3638 ret = __lock_is_held(lock);
3639 current->lockdep_recursion = 0;
3640 raw_local_irq_restore(flags);
3641
3642 return ret;
3643}
3644EXPORT_SYMBOL_GPL(lock_is_held);
3645
Nick Piggincf40bd12009-01-21 08:12:39 +01003646void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3647{
3648 current->lockdep_reclaim_gfp = gfp_mask;
3649}
3650
3651void lockdep_clear_current_reclaim_state(void)
3652{
3653 current->lockdep_reclaim_gfp = 0;
3654}
3655
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003656#ifdef CONFIG_LOCK_STAT
3657static int
3658print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
3659 unsigned long ip)
3660{
3661 if (!debug_locks_off())
3662 return 0;
3663 if (debug_locks_silent)
3664 return 0;
3665
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07003666 printk("\n");
3667 printk("=================================\n");
3668 printk("[ BUG: bad contention detected! ]\n");
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +01003669 print_kernel_ident();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07003670 printk("---------------------------------\n");
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003671 printk("%s/%d is trying to contend lock (",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07003672 curr->comm, task_pid_nr(curr));
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003673 print_lockdep_cache(lock);
3674 printk(") at:\n");
3675 print_ip_sym(ip);
3676 printk("but there are no locks held!\n");
3677 printk("\nother info that might help us debug this:\n");
3678 lockdep_print_held_locks(curr);
3679
3680 printk("\nstack backtrace:\n");
3681 dump_stack();
3682
3683 return 0;
3684}
3685
3686static void
3687__lock_contended(struct lockdep_map *lock, unsigned long ip)
3688{
3689 struct task_struct *curr = current;
3690 struct held_lock *hlock, *prev_hlock;
3691 struct lock_class_stats *stats;
3692 unsigned int depth;
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003693 int i, contention_point, contending_point;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003694
3695 depth = curr->lockdep_depth;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003696 /*
3697 * Whee, we contended on this lock, except it seems we're not
3698 * actually trying to acquire anything much at all..
3699 */
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003700 if (DEBUG_LOCKS_WARN_ON(!depth))
3701 return;
3702
3703 prev_hlock = NULL;
3704 for (i = depth-1; i >= 0; i--) {
3705 hlock = curr->held_locks + i;
3706 /*
3707 * We must not cross into another context:
3708 */
3709 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3710 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003711 if (match_held_lock(hlock, lock))
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003712 goto found_it;
3713 prev_hlock = hlock;
3714 }
3715 print_lock_contention_bug(curr, lock, ip);
3716 return;
3717
3718found_it:
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003719 if (hlock->instance != lock)
3720 return;
3721
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003722 hlock->waittime_stamp = lockstat_clock();
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003723
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003724 contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3725 contending_point = lock_point(hlock_class(hlock)->contending_point,
3726 lock->ip);
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003727
Dave Jonesf82b2172008-08-11 09:30:23 +02003728 stats = get_lock_stats(hlock_class(hlock));
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003729 if (contention_point < LOCKSTAT_POINTS)
3730 stats->contention_point[contention_point]++;
3731 if (contending_point < LOCKSTAT_POINTS)
3732 stats->contending_point[contending_point]++;
Peter Zijlstra96645672007-07-19 01:49:00 -07003733 if (lock->cpu != smp_processor_id())
3734 stats->bounces[bounce_contended + !!hlock->read]++;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003735 put_lock_stats(stats);
3736}
3737
3738static void
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003739__lock_acquired(struct lockdep_map *lock, unsigned long ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003740{
3741 struct task_struct *curr = current;
3742 struct held_lock *hlock, *prev_hlock;
3743 struct lock_class_stats *stats;
3744 unsigned int depth;
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003745 u64 now, waittime = 0;
Peter Zijlstra96645672007-07-19 01:49:00 -07003746 int i, cpu;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003747
3748 depth = curr->lockdep_depth;
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003749 /*
3750 * Yay, we acquired ownership of this lock we didn't try to
3751 * acquire, how the heck did that happen?
3752 */
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003753 if (DEBUG_LOCKS_WARN_ON(!depth))
3754 return;
3755
3756 prev_hlock = NULL;
3757 for (i = depth-1; i >= 0; i--) {
3758 hlock = curr->held_locks + i;
3759 /*
3760 * We must not cross into another context:
3761 */
3762 if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3763 break;
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003764 if (match_held_lock(hlock, lock))
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003765 goto found_it;
3766 prev_hlock = hlock;
3767 }
3768 print_lock_contention_bug(curr, lock, _RET_IP_);
3769 return;
3770
3771found_it:
Peter Zijlstrabb97a912009-07-20 19:15:35 +02003772 if (hlock->instance != lock)
3773 return;
3774
Peter Zijlstra96645672007-07-19 01:49:00 -07003775 cpu = smp_processor_id();
3776 if (hlock->waittime_stamp) {
Peter Zijlstra3365e7792009-10-09 10:12:41 +02003777 now = lockstat_clock();
Peter Zijlstra96645672007-07-19 01:49:00 -07003778 waittime = now - hlock->waittime_stamp;
3779 hlock->holdtime_stamp = now;
3780 }
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003781
Frederic Weisbecker883a2a32010-05-08 06:16:11 +02003782 trace_lock_acquired(lock, ip);
Frederic Weisbecker20625012009-04-06 01:49:33 +02003783
Dave Jonesf82b2172008-08-11 09:30:23 +02003784 stats = get_lock_stats(hlock_class(hlock));
Peter Zijlstra96645672007-07-19 01:49:00 -07003785 if (waittime) {
3786 if (hlock->read)
3787 lock_time_inc(&stats->read_waittime, waittime);
3788 else
3789 lock_time_inc(&stats->write_waittime, waittime);
3790 }
3791 if (lock->cpu != cpu)
3792 stats->bounces[bounce_acquired + !!hlock->read]++;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003793 put_lock_stats(stats);
Peter Zijlstra96645672007-07-19 01:49:00 -07003794
3795 lock->cpu = cpu;
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003796 lock->ip = ip;
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003797}
3798
3799void lock_contended(struct lockdep_map *lock, unsigned long ip)
3800{
3801 unsigned long flags;
3802
3803 if (unlikely(!lock_stat))
3804 return;
3805
3806 if (unlikely(current->lockdep_recursion))
3807 return;
3808
3809 raw_local_irq_save(flags);
3810 check_flags(flags);
3811 current->lockdep_recursion = 1;
Frederic Weisbeckerdb2c4c72010-02-02 23:34:40 +01003812 trace_lock_contended(lock, ip);
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003813 __lock_contended(lock, ip);
3814 current->lockdep_recursion = 0;
3815 raw_local_irq_restore(flags);
3816}
3817EXPORT_SYMBOL_GPL(lock_contended);
3818
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003819void lock_acquired(struct lockdep_map *lock, unsigned long ip)
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003820{
3821 unsigned long flags;
3822
3823 if (unlikely(!lock_stat))
3824 return;
3825
3826 if (unlikely(current->lockdep_recursion))
3827 return;
3828
3829 raw_local_irq_save(flags);
3830 check_flags(flags);
3831 current->lockdep_recursion = 1;
Peter Zijlstrac7e78cf2008-10-16 23:17:09 +02003832 __lock_acquired(lock, ip);
Peter Zijlstraf20786f2007-07-19 01:48:56 -07003833 current->lockdep_recursion = 0;
3834 raw_local_irq_restore(flags);
3835}
3836EXPORT_SYMBOL_GPL(lock_acquired);
3837#endif
3838
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003839/*
3840 * Used by the testsuite, sanitize the validator state
3841 * after a simulated failure:
3842 */
3843
3844void lockdep_reset(void)
3845{
3846 unsigned long flags;
Ingo Molnar23d95a02006-12-13 00:34:40 -08003847 int i;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003848
3849 raw_local_irq_save(flags);
3850 current->curr_chain_key = 0;
3851 current->lockdep_depth = 0;
3852 current->lockdep_recursion = 0;
3853 memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3854 nr_hardirq_chains = 0;
3855 nr_softirq_chains = 0;
3856 nr_process_chains = 0;
3857 debug_locks = 1;
Ingo Molnar23d95a02006-12-13 00:34:40 -08003858 for (i = 0; i < CHAINHASH_SIZE; i++)
3859 INIT_LIST_HEAD(chainhash_table + i);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003860 raw_local_irq_restore(flags);
3861}
3862
3863static void zap_class(struct lock_class *class)
3864{
3865 int i;
3866
3867 /*
3868 * Remove all dependencies this lock is
3869 * involved in:
3870 */
3871 for (i = 0; i < nr_list_entries; i++) {
3872 if (list_entries[i].class == class)
3873 list_del_rcu(&list_entries[i].entry);
3874 }
3875 /*
3876 * Unhash the class and remove it from the all_lock_classes list:
3877 */
3878 list_del_rcu(&class->hash_entry);
3879 list_del_rcu(&class->lock_entry);
3880
Rabin Vincent8bfe0292008-08-11 09:30:26 +02003881 class->key = NULL;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003882}
3883
Arjan van de Venfabe8742008-01-24 07:00:45 +01003884static inline int within(const void *addr, void *start, unsigned long size)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003885{
3886 return addr >= start && addr < start + size;
3887}
3888
3889void lockdep_free_key_range(void *start, unsigned long size)
3890{
3891 struct lock_class *class, *next;
3892 struct list_head *head;
3893 unsigned long flags;
3894 int i;
Nick Piggin5a26db52008-01-16 09:51:58 +01003895 int locked;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003896
3897 raw_local_irq_save(flags);
Nick Piggin5a26db52008-01-16 09:51:58 +01003898 locked = graph_lock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003899
3900 /*
3901 * Unhash all classes that were created by this module:
3902 */
3903 for (i = 0; i < CLASSHASH_SIZE; i++) {
3904 head = classhash_table + i;
3905 if (list_empty(head))
3906 continue;
Arjan van de Venfabe8742008-01-24 07:00:45 +01003907 list_for_each_entry_safe(class, next, head, hash_entry) {
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003908 if (within(class->key, start, size))
3909 zap_class(class);
Arjan van de Venfabe8742008-01-24 07:00:45 +01003910 else if (within(class->name, start, size))
3911 zap_class(class);
3912 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003913 }
3914
Nick Piggin5a26db52008-01-16 09:51:58 +01003915 if (locked)
3916 graph_unlock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003917 raw_local_irq_restore(flags);
3918}
3919
3920void lockdep_reset_lock(struct lockdep_map *lock)
3921{
Ingo Molnard6d897c2006-07-10 04:44:04 -07003922 struct lock_class *class, *next;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003923 struct list_head *head;
3924 unsigned long flags;
3925 int i, j;
Nick Piggin5a26db52008-01-16 09:51:58 +01003926 int locked;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003927
3928 raw_local_irq_save(flags);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003929
3930 /*
Ingo Molnard6d897c2006-07-10 04:44:04 -07003931 * Remove all classes this lock might have:
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003932 */
Ingo Molnard6d897c2006-07-10 04:44:04 -07003933 for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3934 /*
3935 * If the class exists we look it up and zap it:
3936 */
3937 class = look_up_lock_class(lock, j);
3938 if (class)
3939 zap_class(class);
3940 }
3941 /*
3942 * Debug check: in the end all mapped classes should
3943 * be gone.
3944 */
Nick Piggin5a26db52008-01-16 09:51:58 +01003945 locked = graph_lock();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003946 for (i = 0; i < CLASSHASH_SIZE; i++) {
3947 head = classhash_table + i;
3948 if (list_empty(head))
3949 continue;
3950 list_for_each_entry_safe(class, next, head, hash_entry) {
Hitoshi Mitake62016252010-10-05 18:01:51 +09003951 int match = 0;
3952
3953 for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
3954 match |= class == lock->class_cache[j];
3955
3956 if (unlikely(match)) {
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003957 if (debug_locks_off_graph_unlock()) {
3958 /*
3959 * We all just reset everything, how did it match?
3960 */
Ingo Molnar74c383f2006-12-13 00:34:43 -08003961 WARN_ON(1);
Peter Zijlstra0119fee2011-09-02 01:30:29 +02003962 }
Ingo Molnard6d897c2006-07-10 04:44:04 -07003963 goto out_restore;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003964 }
3965 }
3966 }
Nick Piggin5a26db52008-01-16 09:51:58 +01003967 if (locked)
3968 graph_unlock();
Ingo Molnard6d897c2006-07-10 04:44:04 -07003969
3970out_restore:
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003971 raw_local_irq_restore(flags);
3972}
3973
Sam Ravnborg14999932007-02-28 20:12:31 -08003974void lockdep_init(void)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07003975{
3976 int i;
3977
3978 /*
3979 * Some architectures have their own start_kernel()
3980 * code which calls lockdep_init(), while we also
3981 * call lockdep_init() from the start_kernel() itself,
3982 * and we want to initialize the hashes only once:
3983 */
3984 if (lockdep_initialized)
3985 return;
3986
3987 for (i = 0; i < CLASSHASH_SIZE; i++)
3988 INIT_LIST_HEAD(classhash_table + i);
3989
3990 for (i = 0; i < CHAINHASH_SIZE; i++)
3991 INIT_LIST_HEAD(chainhash_table + i);
3992
3993 lockdep_initialized = 1;
3994}
3995
3996void __init lockdep_info(void)
3997{
3998 printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3999
Li Zefanb0788ca2008-11-21 15:57:32 +08004000 printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004001 printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
4002 printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
Li Zefanb0788ca2008-11-21 15:57:32 +08004003 printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004004 printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
4005 printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
4006 printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
4007
4008 printk(" memory used by lock dependency info: %lu kB\n",
4009 (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
4010 sizeof(struct list_head) * CLASSHASH_SIZE +
4011 sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
4012 sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
Ming Lei90629202009-08-02 21:43:36 +08004013 sizeof(struct list_head) * CHAINHASH_SIZE
Ming Lei4dd861d2009-07-16 15:44:29 +02004014#ifdef CONFIG_PROVE_LOCKING
Ming Leie351b662009-07-22 22:48:09 +08004015 + sizeof(struct circular_queue)
Ming Lei4dd861d2009-07-16 15:44:29 +02004016#endif
Ming Lei90629202009-08-02 21:43:36 +08004017 ) / 1024
Ming Lei4dd861d2009-07-16 15:44:29 +02004018 );
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004019
4020 printk(" per task-struct memory footprint: %lu bytes\n",
4021 sizeof(struct held_lock) * MAX_LOCK_DEPTH);
4022
4023#ifdef CONFIG_DEBUG_LOCKDEP
Johannes Bergc71063c2007-07-19 01:49:02 -07004024 if (lockdep_init_error) {
Ming Lei81140ac2011-11-17 13:34:32 +08004025 printk("WARNING: lockdep init error! lock-%s was acquired"
4026 "before lockdep_init\n", lock_init_error);
Johannes Bergc71063c2007-07-19 01:49:02 -07004027 printk("Call stack leading to lockdep invocation was:\n");
4028 print_stack_trace(&lockdep_init_trace, 0);
4029 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004030#endif
4031}
4032
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004033static void
4034print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
Arjan van de Ven55794a42006-07-10 04:44:03 -07004035 const void *mem_to, struct held_lock *hlock)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004036{
4037 if (!debug_locks_off())
4038 return;
4039 if (debug_locks_silent)
4040 return;
4041
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004042 printk("\n");
4043 printk("=========================\n");
4044 printk("[ BUG: held lock freed! ]\n");
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +01004045 print_kernel_ident();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004046 printk("-------------------------\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004047 printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07004048 curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
Arjan van de Ven55794a42006-07-10 04:44:03 -07004049 print_lock(hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004050 lockdep_print_held_locks(curr);
4051
4052 printk("\nstack backtrace:\n");
4053 dump_stack();
4054}
4055
Oleg Nesterov54561782007-12-05 15:46:09 +01004056static inline int not_in_range(const void* mem_from, unsigned long mem_len,
4057 const void* lock_from, unsigned long lock_len)
4058{
4059 return lock_from + lock_len <= mem_from ||
4060 mem_from + mem_len <= lock_from;
4061}
4062
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004063/*
4064 * Called when kernel memory is freed (or unmapped), or if a lock
4065 * is destroyed or reinitialized - this code checks whether there is
4066 * any held lock in the memory range of <from> to <to>:
4067 */
4068void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
4069{
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004070 struct task_struct *curr = current;
4071 struct held_lock *hlock;
4072 unsigned long flags;
4073 int i;
4074
4075 if (unlikely(!debug_locks))
4076 return;
4077
4078 local_irq_save(flags);
4079 for (i = 0; i < curr->lockdep_depth; i++) {
4080 hlock = curr->held_locks + i;
4081
Oleg Nesterov54561782007-12-05 15:46:09 +01004082 if (not_in_range(mem_from, mem_len, hlock->instance,
4083 sizeof(*hlock->instance)))
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004084 continue;
4085
Oleg Nesterov54561782007-12-05 15:46:09 +01004086 print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004087 break;
4088 }
4089 local_irq_restore(flags);
4090}
Peter Zijlstraed075362006-12-06 20:35:24 -08004091EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004092
Colin Cross1b1d2fb2013-05-06 23:50:08 +00004093static void print_held_locks_bug(void)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004094{
4095 if (!debug_locks_off())
4096 return;
4097 if (debug_locks_silent)
4098 return;
4099
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004100 printk("\n");
4101 printk("=====================================\n");
Colin Cross1b1d2fb2013-05-06 23:50:08 +00004102 printk("[ BUG: %s/%d still has locks held! ]\n",
4103 current->comm, task_pid_nr(current));
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +01004104 print_kernel_ident();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004105 printk("-------------------------------------\n");
Colin Cross1b1d2fb2013-05-06 23:50:08 +00004106 lockdep_print_held_locks(current);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004107 printk("\nstack backtrace:\n");
4108 dump_stack();
4109}
4110
Colin Cross1b1d2fb2013-05-06 23:50:08 +00004111void debug_check_no_locks_held(void)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004112{
Colin Cross1b1d2fb2013-05-06 23:50:08 +00004113 if (unlikely(current->lockdep_depth > 0))
4114 print_held_locks_bug();
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004115}
Colin Cross1b1d2fb2013-05-06 23:50:08 +00004116EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004117
4118void debug_show_all_locks(void)
4119{
4120 struct task_struct *g, *p;
4121 int count = 10;
4122 int unlock = 1;
4123
Jarek Poplawski9c35dd72007-03-22 00:11:28 -08004124 if (unlikely(!debug_locks)) {
4125 printk("INFO: lockdep is turned off.\n");
4126 return;
4127 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004128 printk("\nShowing all locks held in the system:\n");
4129
4130 /*
4131 * Here we try to get the tasklist_lock as hard as possible,
4132 * if not successful after 2 seconds we ignore it (but keep
4133 * trying). This is to enable a debug printout even if a
4134 * tasklist_lock-holding task deadlocks or crashes.
4135 */
4136retry:
4137 if (!read_trylock(&tasklist_lock)) {
4138 if (count == 10)
4139 printk("hm, tasklist_lock locked, retrying... ");
4140 if (count) {
4141 count--;
4142 printk(" #%d", 10-count);
4143 mdelay(200);
4144 goto retry;
4145 }
4146 printk(" ignoring it.\n");
4147 unlock = 0;
qinghuang feng46fec7a2008-10-28 17:24:28 +08004148 } else {
4149 if (count != 10)
4150 printk(KERN_CONT " locked it.\n");
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004151 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004152
4153 do_each_thread(g, p) {
Ingo Molnar85684872007-12-05 15:46:09 +01004154 /*
4155 * It's not reliable to print a task's held locks
4156 * if it's not sleeping (or if it's not the current
4157 * task):
4158 */
4159 if (p->state == TASK_RUNNING && p != current)
4160 continue;
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004161 if (p->lockdep_depth)
4162 lockdep_print_held_locks(p);
4163 if (!unlock)
4164 if (read_trylock(&tasklist_lock))
4165 unlock = 1;
4166 } while_each_thread(g, p);
4167
4168 printk("\n");
4169 printk("=============================================\n\n");
4170
4171 if (unlock)
4172 read_unlock(&tasklist_lock);
4173}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004174EXPORT_SYMBOL_GPL(debug_show_all_locks);
4175
Ingo Molnar82a1fcb2008-01-25 21:08:02 +01004176/*
4177 * Careful: only use this function if you are sure that
4178 * the task cannot run in parallel!
4179 */
John Kacurf1b499f2010-08-05 17:10:53 +02004180void debug_show_held_locks(struct task_struct *task)
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004181{
Jarek Poplawski9c35dd72007-03-22 00:11:28 -08004182 if (unlikely(!debug_locks)) {
4183 printk("INFO: lockdep is turned off.\n");
4184 return;
4185 }
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004186 lockdep_print_held_locks(task);
4187}
Ingo Molnarfbb9ce952006-07-03 00:24:50 -07004188EXPORT_SYMBOL_GPL(debug_show_held_locks);
Peter Zijlstrab351d162007-10-11 22:11:12 +02004189
4190void lockdep_sys_exit(void)
4191{
4192 struct task_struct *curr = current;
4193
4194 if (unlikely(curr->lockdep_depth)) {
4195 if (!debug_locks_off())
4196 return;
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004197 printk("\n");
4198 printk("================================================\n");
4199 printk("[ BUG: lock held when returning to user space! ]\n");
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +01004200 print_kernel_ident();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004201 printk("------------------------------------------------\n");
Peter Zijlstrab351d162007-10-11 22:11:12 +02004202 printk("%s/%d is leaving the kernel with locks still held!\n",
4203 curr->comm, curr->pid);
4204 lockdep_print_held_locks(curr);
4205 }
4206}
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004207
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004208void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004209{
4210 struct task_struct *curr = current;
4211
Lai Jiangshan2b3fc352010-04-20 16:23:07 +08004212#ifndef CONFIG_PROVE_RCU_REPEATEDLY
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004213 if (!debug_locks_off())
4214 return;
Lai Jiangshan2b3fc352010-04-20 16:23:07 +08004215#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
4216 /* Note: the following can be executed concurrently, so be careful. */
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004217 printk("\n");
4218 printk("===============================\n");
4219 printk("[ INFO: suspicious RCU usage. ]\n");
Ben Hutchingsfbdc4b92011-10-28 04:36:55 +01004220 print_kernel_ident();
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004221 printk("-------------------------------\n");
4222 printk("%s:%d %s!\n", file, line, s);
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004223 printk("\nother info that might help us debug this:\n\n");
Paul E. McKenneyc5fdcec2012-01-30 08:46:32 -08004224 printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
4225 !rcu_lockdep_current_cpu_online()
4226 ? "RCU used illegally from offline CPU!\n"
Paul E. McKenney5c173eb2013-09-13 17:20:11 -07004227 : !rcu_is_watching()
Paul E. McKenneyc5fdcec2012-01-30 08:46:32 -08004228 ? "RCU used illegally from idle CPU!\n"
4229 : "",
4230 rcu_scheduler_active, debug_locks);
Frederic Weisbecker0464e932011-10-07 18:22:01 +02004231
4232 /*
4233 * If a CPU is in the RCU-free window in idle (ie: in the section
4234 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
4235 * considers that CPU to be in an "extended quiescent state",
4236 * which means that RCU will be completely ignoring that CPU.
4237 * Therefore, rcu_read_lock() and friends have absolutely no
4238 * effect on a CPU running in that state. In other words, even if
4239 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
4240 * delete data structures out from under it. RCU really has no
4241 * choice here: we need to keep an RCU-free window in idle where
4242 * the CPU may possibly enter into low power mode. This way we can
4243 * notice an extended quiescent state to other CPUs that started a grace
4244 * period. Otherwise we would delay any grace period as long as we run
4245 * in the idle task.
4246 *
4247 * So complain bitterly if someone does call rcu_read_lock(),
4248 * rcu_read_lock_bh() and so on from extended quiescent states.
4249 */
Paul E. McKenney5c173eb2013-09-13 17:20:11 -07004250 if (!rcu_is_watching())
Frederic Weisbecker0464e932011-10-07 18:22:01 +02004251 printk("RCU used illegally from extended quiescent state!\n");
4252
Paul E. McKenney0632eb32010-02-22 17:04:47 -08004253 lockdep_print_held_locks(curr);
4254 printk("\nstack backtrace:\n");
4255 dump_stack();
4256}
Paul E. McKenneyb3fbab02011-05-24 08:31:09 -07004257EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);