Kernel

Kernel Git Source Tree

Root/kernel/lockdep.c

1	/*
2	* kernel/lockdep.c
3	*
4	* Runtime locking correctness validator
5	*
6	* Started by Ingo Molnar:
7	*
8	* Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
9	* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
10	*
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	*/
28	#define DISABLE_BRANCH_PROFILING
29	#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>
41	#include <linux/utsname.h>
42	#include <linux/hash.h>
43	#include <linux/ftrace.h>
44	#include <linux/stringify.h>
45	#include <linux/bitops.h>
46	#include <linux/gfp.h>
47
48	#include <asm/sections.h>
49
50	#include "lockdep_internals.h"
51
52	#define CREATE_TRACE_POINTS
53	#include <trace/events/lock.h>
54
55	#ifdef CONFIG_PROVE_LOCKING
56	int prove_locking = 1;
57	module_param(prove_locking, int, 0644);
58	#else
59	#define prove_locking 0
60	#endif
61
62	#ifdef CONFIG_LOCK_STAT
63	int lock_stat = 1;
64	module_param(lock_stat, int, 0644);
65	#else
66	#define lock_stat 0
67	#endif
68
69	/*
70	* lockdep_lock: protects the lockdep graph, the hashes and the
71	* class/list/hash allocators.
72	*
73	* This is one of the rare exceptions where it's justified
74	* to use a raw spinlock - we really dont want the spinlock
75	* code to recurse back into the lockdep code...
76	*/
77	static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
78
79	static int graph_lock(void)
80	{
81	arch_spin_lock(&lockdep_lock);
82	/*
83	* Make sure that if another CPU detected a bug while
84	* walking the graph we dont change it (while the other
85	* CPU is busy printing out stuff with the graph lock
86	* dropped already)
87	*/
88	if (!debug_locks) {
89	arch_spin_unlock(&lockdep_lock);
90	return 0;
91	}
92	/* prevent any recursions within lockdep from causing deadlocks */
93	current->lockdep_recursion++;
94	return 1;
95	}
96
97	static inline int graph_unlock(void)
98	{
99	if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
100	return DEBUG_LOCKS_WARN_ON(1);
101
102	current->lockdep_recursion--;
103	arch_spin_unlock(&lockdep_lock);
104	return 0;
105	}
106
107	/*
108	* Turn lock debugging off and return with 0 if it was off already,
109	* and also release the graph lock:
110	*/
111	static inline int debug_locks_off_graph_unlock(void)
112	{
113	int ret = debug_locks_off();
114
115	arch_spin_unlock(&lockdep_lock);
116
117	return ret;
118	}
119
120	static int lockdep_initialized;
121
122	unsigned long nr_list_entries;
123	static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
124
125	/*
126	* All data structures here are protected by the global debug_lock.
127	*
128	* Mutex key structs only get allocated, once during bootup, and never
129	* get freed - this significantly simplifies the debugging code.
130	*/
131	unsigned long nr_lock_classes;
132	static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
133
134	static inline struct lock_class hlock_class(struct held_lock hlock)
135	{
136	if (!hlock->class_idx) {
137	DEBUG_LOCKS_WARN_ON(1);
138	return NULL;
139	}
140	return lock_classes + hlock->class_idx - 1;
141	}
142
143	#ifdef CONFIG_LOCK_STAT
144	static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
145	cpu_lock_stats);
146
147	static inline u64 lockstat_clock(void)
148	{
149	return cpu_clock(smp_processor_id());
150	}
151
152	static int lock_point(unsigned long points[], unsigned long ip)
153	{
154	int i;
155
156	for (i = 0; i < LOCKSTAT_POINTS; i++) {
157	if (points[i] == 0) {
158	points[i] = ip;
159	break;
160	}
161	if (points[i] == ip)
162	break;
163	}
164
165	return i;
166	}
167
168	static void lock_time_inc(struct lock_time *lt, u64 time)
169	{
170	if (time > lt->max)
171	lt->max = time;
172
173	if (time < lt->min \|\| !lt->nr)
174	lt->min = time;
175
176	lt->total += time;
177	lt->nr++;
178	}
179
180	static inline void lock_time_add(struct lock_time src, struct lock_time dst)
181	{
182	if (!src->nr)
183	return;
184
185	if (src->max > dst->max)
186	dst->max = src->max;
187
188	if (src->min < dst->min \|\| !dst->nr)
189	dst->min = src->min;
190
191	dst->total += src->total;
192	dst->nr += src->nr;
193	}
194
195	struct lock_class_stats lock_stats(struct lock_class *class)
196	{
197	struct lock_class_stats stats;
198	int cpu, i;
199
200	memset(&stats, 0, sizeof(struct lock_class_stats));
201	for_each_possible_cpu(cpu) {
202	struct lock_class_stats *pcs =
203	&per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
204
205	for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
206	stats.contention_point[i] += pcs->contention_point[i];
207
208	for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
209	stats.contending_point[i] += pcs->contending_point[i];
210
211	lock_time_add(&pcs->read_waittime, &stats.read_waittime);
212	lock_time_add(&pcs->write_waittime, &stats.write_waittime);
213
214	lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
215	lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
216
217	for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
218	stats.bounces[i] += pcs->bounces[i];
219	}
220
221	return stats;
222	}
223
224	void clear_lock_stats(struct lock_class *class)
225	{
226	int cpu;
227
228	for_each_possible_cpu(cpu) {
229	struct lock_class_stats *cpu_stats =
230	&per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
231
232	memset(cpu_stats, 0, sizeof(struct lock_class_stats));
233	}
234	memset(class->contention_point, 0, sizeof(class->contention_point));
235	memset(class->contending_point, 0, sizeof(class->contending_point));
236	}
237
238	static struct lock_class_stats get_lock_stats(struct lock_class class)
239	{
240	return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
241	}
242
243	static void put_lock_stats(struct lock_class_stats *stats)
244	{
245	put_cpu_var(cpu_lock_stats);
246	}
247
248	static void lock_release_holdtime(struct held_lock *hlock)
249	{
250	struct lock_class_stats *stats;
251	u64 holdtime;
252
253	if (!lock_stat)
254	return;
255
256	holdtime = lockstat_clock() - hlock->holdtime_stamp;
257
258	stats = get_lock_stats(hlock_class(hlock));
259	if (hlock->read)
260	lock_time_inc(&stats->read_holdtime, holdtime);
261	else
262	lock_time_inc(&stats->write_holdtime, holdtime);
263	put_lock_stats(stats);
264	}
265	#else
266	static inline void lock_release_holdtime(struct held_lock *hlock)
267	{
268	}
269	#endif
270
271	/*
272	* We keep a global list of all lock classes. The list only grows,
273	* never shrinks. The list is only accessed with the lockdep
274	* spinlock lock held.
275	*/
276	LIST_HEAD(all_lock_classes);
277
278	/*
279	* The lockdep classes are in a hash-table as well, for fast lookup:
280	*/
281	#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
282	#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
283	#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
284	#define classhashentry(key) (classhash_table + __classhashfn((key)))
285
286	static struct list_head classhash_table[CLASSHASH_SIZE];
287
288	/*
289	* We put the lock dependency chains into a hash-table as well, to cache
290	* their existence:
291	*/
292	#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
293	#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
294	#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
295	#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
296
297	static struct list_head chainhash_table[CHAINHASH_SIZE];
298
299	/*
300	* The hash key of the lock dependency chains is a hash itself too:
301	* it's a hash of all locks taken up to that lock, including that lock.
302	* It's a 64-bit hash, because it's important for the keys to be
303	* unique.
304	*/
305	#define iterate_chain_key(key1, key2) \
306	(((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
307	((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
308	(key2))
309
310	void lockdep_off(void)
311	{
312	current->lockdep_recursion++;
313	}
314	EXPORT_SYMBOL(lockdep_off);
315
316	void lockdep_on(void)
317	{
318	current->lockdep_recursion--;
319	}
320	EXPORT_SYMBOL(lockdep_on);
321
322	/*
323	* Debugging switches:
324	*/
325
326	#define VERBOSE 0
327	#define VERY_VERBOSE 0
328
329	#if VERBOSE
330	# define HARDIRQ_VERBOSE 1
331	# define SOFTIRQ_VERBOSE 1
332	# define RECLAIM_VERBOSE 1
333	#else
334	# define HARDIRQ_VERBOSE 0
335	# define SOFTIRQ_VERBOSE 0
336	# define RECLAIM_VERBOSE 0
337	#endif
338
339	#if VERBOSE \|\| HARDIRQ_VERBOSE \|\| SOFTIRQ_VERBOSE \|\| RECLAIM_VERBOSE
340	/*
341	* Quick filtering for interesting events:
342	*/
343	static int class_filter(struct lock_class *class)
344	{
345	#if 0
346	/* Example */
347	if (class->name_version == 1 &&
348	!strcmp(class->name, "lockname"))
349	return 1;
350	if (class->name_version == 1 &&
351	!strcmp(class->name, "&struct->lockfield"))
352	return 1;
353	#endif
354	/* Filter everything else. 1 would be to allow everything else */
355	return 0;
356	}
357	#endif
358
359	static int verbose(struct lock_class *class)
360	{
361	#if VERBOSE
362	return class_filter(class);
363	#endif
364	return 0;
365	}
366
367	/*
368	* Stack-trace: tightly packed array of stack backtrace
369	* addresses. Protected by the graph_lock.
370	*/
371	unsigned long nr_stack_trace_entries;
372	static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
373
374	static int save_trace(struct stack_trace *trace)
375	{
376	trace->nr_entries = 0;
377	trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
378	trace->entries = stack_trace + nr_stack_trace_entries;
379
380	trace->skip = 3;
381
382	save_stack_trace(trace);
383
384	/*
385	* Some daft arches put -1 at the end to indicate its a full trace.
386	*
387	* <rant> this is buggy anyway, since it takes a whole extra entry so a
388	* complete trace that maxes out the entries provided will be reported
389	* as incomplete, friggin useless </rant>
390	*/
391	if (trace->nr_entries != 0 &&
392	trace->entries[trace->nr_entries-1] == ULONG_MAX)
393	trace->nr_entries--;
394
395	trace->max_entries = trace->nr_entries;
396
397	nr_stack_trace_entries += trace->nr_entries;
398
399	if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
400	if (!debug_locks_off_graph_unlock())
401	return 0;
402
403	printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
404	printk("turning off the locking correctness validator.\n");
405	dump_stack();
406
407	return 0;
408	}
409
410	return 1;
411	}
412
413	unsigned int nr_hardirq_chains;
414	unsigned int nr_softirq_chains;
415	unsigned int nr_process_chains;
416	unsigned int max_lockdep_depth;
417
418	#ifdef CONFIG_DEBUG_LOCKDEP
419	/*
420	* We cannot printk in early bootup code. Not even early_printk()
421	* might work. So we mark any initialization errors and printk
422	* about it later on, in lockdep_info().
423	*/
424	static int lockdep_init_error;
425	static unsigned long lockdep_init_trace_data[20];
426	static struct stack_trace lockdep_init_trace = {
427	.max_entries = ARRAY_SIZE(lockdep_init_trace_data),
428	.entries = lockdep_init_trace_data,
429	};
430
431	/*
432	* Various lockdep statistics:
433	*/
434	atomic_t chain_lookup_hits;
435	atomic_t chain_lookup_misses;
436	atomic_t hardirqs_on_events;
437	atomic_t hardirqs_off_events;
438	atomic_t redundant_hardirqs_on;
439	atomic_t redundant_hardirqs_off;
440	atomic_t softirqs_on_events;
441	atomic_t softirqs_off_events;
442	atomic_t redundant_softirqs_on;
443	atomic_t redundant_softirqs_off;
444	atomic_t nr_unused_locks;
445	atomic_t nr_cyclic_checks;
446	atomic_t nr_find_usage_forwards_checks;
447	atomic_t nr_find_usage_backwards_checks;
448	#endif
449
450	/*
451	* Locking printouts:
452	*/
453
454	#define __USAGE(__STATE) \
455	[LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
456	[LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
457	[LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
458	[LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
459
460	static const char *usage_str[] =
461	{
462	#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
463	#include "lockdep_states.h"
464	#undef LOCKDEP_STATE
465	[LOCK_USED] = "INITIAL USE",
466	};
467
468	const char * __get_key_name(struct lockdep_subclass_key key, char str)
469	{
470	return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
471	}
472
473	static inline unsigned long lock_flag(enum lock_usage_bit bit)
474	{
475	return 1UL << bit;
476	}
477
478	static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
479	{
480	char c = '.';
481
482	if (class->usage_mask & lock_flag(bit + 2))
483	c = '+';
484	if (class->usage_mask & lock_flag(bit)) {
485	c = '-';
486	if (class->usage_mask & lock_flag(bit + 2))
487	c = '?';
488	}
489
490	return c;
491	}
492
493	void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
494	{
495	int i = 0;
496
497	#define LOCKDEP_STATE(__STATE) \
498	usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
499	usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
500	#include "lockdep_states.h"
501	#undef LOCKDEP_STATE
502
503	usage[i] = '\0';
504	}
505
506	static void print_lock_name(struct lock_class *class)
507	{
508	char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
509	const char *name;
510
511	get_usage_chars(class, usage);
512
513	name = class->name;
514	if (!name) {
515	name = __get_key_name(class->key, str);
516	printk(" (%s", name);
517	} else {
518	printk(" (%s", name);
519	if (class->name_version > 1)
520	printk("#%d", class->name_version);
521	if (class->subclass)
522	printk("/%d", class->subclass);
523	}
524	printk("){%s}", usage);
525	}
526
527	static void print_lockdep_cache(struct lockdep_map *lock)
528	{
529	const char *name;
530	char str[KSYM_NAME_LEN];
531
532	name = lock->name;
533	if (!name)
534	name = __get_key_name(lock->key->subkeys, str);
535
536	printk("%s", name);
537	}
538
539	static void print_lock(struct held_lock *hlock)
540	{
541	print_lock_name(hlock_class(hlock));
542	printk(", at: ");
543	print_ip_sym(hlock->acquire_ip);
544	}
545
546	static void lockdep_print_held_locks(struct task_struct *curr)
547	{
548	int i, depth = curr->lockdep_depth;
549
550	if (!depth) {
551	printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
552	return;
553	}
554	printk("%d lock%s held by %s/%d:\n",
555	depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
556
557	for (i = 0; i < depth; i++) {
558	printk(" #%d: ", i);
559	print_lock(curr->held_locks + i);
560	}
561	}
562
563	static void print_kernel_version(void)
564	{
565	printk("%s %.*s\n", init_utsname()->release,
566	(int)strcspn(init_utsname()->version, " "),
567	init_utsname()->version);
568	}
569
570	static int very_verbose(struct lock_class *class)
571	{
572	#if VERY_VERBOSE
573	return class_filter(class);
574	#endif
575	return 0;
576	}
577
578	/*
579	* Is this the address of a static object:
580	*/
581	static int static_obj(void *obj)
582	{
583	unsigned long start = (unsigned long) &_stext,
584	end = (unsigned long) &_end,
585	addr = (unsigned long) obj;
586
587	/*
588	* static variable?
589	*/
590	if ((addr >= start) && (addr < end))
591	return 1;
592
593	if (arch_is_kernel_data(addr))
594	return 1;
595
596	/*
597	* in-kernel percpu var?
598	*/
599	if (is_kernel_percpu_address(addr))
600	return 1;
601
602	/*
603	* module static or percpu var?
604	*/
605	return is_module_address(addr) \|\| is_module_percpu_address(addr);
606	}
607
608	/*
609	* To make lock name printouts unique, we calculate a unique
610	* class->name_version generation counter:
611	*/
612	static int count_matching_names(struct lock_class *new_class)
613	{
614	struct lock_class *class;
615	int count = 0;
616
617	if (!new_class->name)
618	return 0;
619
620	list_for_each_entry(class, &all_lock_classes, lock_entry) {
621	if (new_class->key - new_class->subclass == class->key)
622	return class->name_version;
623	if (class->name && !strcmp(class->name, new_class->name))
624	count = max(count, class->name_version);
625	}
626
627	return count + 1;
628	}
629
630	/*
631	* Register a lock's class in the hash-table, if the class is not present
632	* yet. Otherwise we look it up. We cache the result in the lock object
633	* itself, so actual lookup of the hash should be once per lock object.
634	*/
635	static inline struct lock_class *
636	look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
637	{
638	struct lockdep_subclass_key *key;
639	struct list_head *hash_head;
640	struct lock_class *class;
641
642	#ifdef CONFIG_DEBUG_LOCKDEP
643	/*
644	* If the architecture calls into lockdep before initializing
645	* the hashes then we'll warn about it later. (we cannot printk
646	* right now)
647	*/
648	if (unlikely(!lockdep_initialized)) {
649	lockdep_init();
650	lockdep_init_error = 1;
651	save_stack_trace(&lockdep_init_trace);
652	}
653	#endif
654
655	/*
656	* Static locks do not have their class-keys yet - for them the key
657	* is the lock object itself:
658	*/
659	if (unlikely(!lock->key))
660	lock->key = (void *)lock;
661
662	/*
663	* NOTE: the class-key must be unique. For dynamic locks, a static
664	* lock_class_key variable is passed in through the mutex_init()
665	* (or spin_lock_init()) call - which acts as the key. For static
666	* locks we use the lock object itself as the key.
667	*/
668	BUILD_BUG_ON(sizeof(struct lock_class_key) >
669	sizeof(struct lockdep_map));
670
671	key = lock->key->subkeys + subclass;
672
673	hash_head = classhashentry(key);
674
675	/*
676	* We can walk the hash lockfree, because the hash only
677	* grows, and we are careful when adding entries to the end:
678	*/
679	list_for_each_entry(class, hash_head, hash_entry) {
680	if (class->key == key) {
681	WARN_ON_ONCE(class->name != lock->name);
682	return class;
683	}
684	}
685
686	return NULL;
687	}
688
689	/*
690	* Register a lock's class in the hash-table, if the class is not present
691	* yet. Otherwise we look it up. We cache the result in the lock object
692	* itself, so actual lookup of the hash should be once per lock object.
693	*/
694	static inline struct lock_class *
695	register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
696	{
697	struct lockdep_subclass_key *key;
698	struct list_head *hash_head;
699	struct lock_class *class;
700	unsigned long flags;
701
702	class = look_up_lock_class(lock, subclass);
703	if (likely(class))
704	return class;
705
706	/*
707	* Debug-check: all keys must be persistent!
708	*/
709	if (!static_obj(lock->key)) {
710	debug_locks_off();
711	printk("INFO: trying to register non-static key.\n");
712	printk("the code is fine but needs lockdep annotation.\n");
713	printk("turning off the locking correctness validator.\n");
714	dump_stack();
715
716	return NULL;
717	}
718
719	key = lock->key->subkeys + subclass;
720	hash_head = classhashentry(key);
721
722	raw_local_irq_save(flags);
723	if (!graph_lock()) {
724	raw_local_irq_restore(flags);
725	return NULL;
726	}
727	/*
728	* We have to do the hash-walk again, to avoid races
729	* with another CPU:
730	*/
731	list_for_each_entry(class, hash_head, hash_entry)
732	if (class->key == key)
733	goto out_unlock_set;
734	/*
735	* Allocate a new key from the static array, and add it to
736	* the hash:
737	*/
738	if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
739	if (!debug_locks_off_graph_unlock()) {
740	raw_local_irq_restore(flags);
741	return NULL;
742	}
743	raw_local_irq_restore(flags);
744
745	printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
746	printk("turning off the locking correctness validator.\n");
747	dump_stack();
748	return NULL;
749	}
750	class = lock_classes + nr_lock_classes++;
751	debug_atomic_inc(&nr_unused_locks);
752	class->key = key;
753	class->name = lock->name;
754	class->subclass = subclass;
755	INIT_LIST_HEAD(&class->lock_entry);
756	INIT_LIST_HEAD(&class->locks_before);
757	INIT_LIST_HEAD(&class->locks_after);
758	class->name_version = count_matching_names(class);
759	/*
760	* We use RCU's safe list-add method to make
761	* parallel walking of the hash-list safe:
762	*/
763	list_add_tail_rcu(&class->hash_entry, hash_head);
764	/*
765	* Add it to the global list of classes:
766	*/
767	list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
768
769	if (verbose(class)) {
770	graph_unlock();
771	raw_local_irq_restore(flags);
772
773	printk("\nnew class %p: %s", class->key, class->name);
774	if (class->name_version > 1)
775	printk("#%d", class->name_version);
776	printk("\n");
777	dump_stack();
778
779	raw_local_irq_save(flags);
780	if (!graph_lock()) {
781	raw_local_irq_restore(flags);
782	return NULL;
783	}
784	}
785	out_unlock_set:
786	graph_unlock();
787	raw_local_irq_restore(flags);
788
789	if (!subclass \|\| force)
790	lock->class_cache = class;
791
792	if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
793	return NULL;
794
795	return class;
796	}
797
798	#ifdef CONFIG_PROVE_LOCKING
799	/*
800	* Allocate a lockdep entry. (assumes the graph_lock held, returns
801	* with NULL on failure)
802	*/
803	static struct lock_list *alloc_list_entry(void)
804	{
805	if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
806	if (!debug_locks_off_graph_unlock())
807	return NULL;
808
809	printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
810	printk("turning off the locking correctness validator.\n");
811	dump_stack();
812	return NULL;
813	}
814	return list_entries + nr_list_entries++;
815	}
816
817	/*
818	* Add a new dependency to the head of the list:
819	*/
820	static int add_lock_to_list(struct lock_class class, struct lock_class this,
821	struct list_head *head, unsigned long ip, int distance)
822	{
823	struct lock_list *entry;
824	/*
825	* Lock not present yet - get a new dependency struct and
826	* add it to the list:
827	*/
828	entry = alloc_list_entry();
829	if (!entry)
830	return 0;
831
832	if (!save_trace(&entry->trace))
833	return 0;
834
835	entry->class = this;
836	entry->distance = distance;
837	/*
838	* Since we never remove from the dependency list, the list can
839	* be walked lockless by other CPUs, it's only allocation
840	* that must be protected by the spinlock. But this also means
841	* we must make new entries visible only once writes to the
842	* entry become visible - hence the RCU op:
843	*/
844	list_add_tail_rcu(&entry->entry, head);
845
846	return 1;
847	}
848
849	/*
850	* For good efficiency of modular, we use power of 2
851	*/
852	#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
853	#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
854
855	/*
856	* The circular_queue and helpers is used to implement the
857	* breadth-first search(BFS)algorithem, by which we can build
858	* the shortest path from the next lock to be acquired to the
859	* previous held lock if there is a circular between them.
860	*/
861	struct circular_queue {
862	unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
863	unsigned int front, rear;
864	};
865
866	static struct circular_queue lock_cq;
867
868	unsigned int max_bfs_queue_depth;
869
870	static unsigned int lockdep_dependency_gen_id;
871
872	static inline void __cq_init(struct circular_queue *cq)
873	{
874	cq->front = cq->rear = 0;
875	lockdep_dependency_gen_id++;
876	}
877
878	static inline int __cq_empty(struct circular_queue *cq)
879	{
880	return (cq->front == cq->rear);
881	}
882
883	static inline int __cq_full(struct circular_queue *cq)
884	{
885	return ((cq->rear + 1) & CQ_MASK) == cq->front;
886	}
887
888	static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
889	{
890	if (__cq_full(cq))
891	return -1;
892
893	cq->element[cq->rear] = elem;
894	cq->rear = (cq->rear + 1) & CQ_MASK;
895	return 0;
896	}
897
898	static inline int __cq_dequeue(struct circular_queue cq, unsigned long elem)
899	{
900	if (__cq_empty(cq))
901	return -1;
902
903	*elem = cq->element[cq->front];
904	cq->front = (cq->front + 1) & CQ_MASK;
905	return 0;
906	}
907
908	static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
909	{
910	return (cq->rear - cq->front) & CQ_MASK;
911	}
912
913	static inline void mark_lock_accessed(struct lock_list *lock,
914	struct lock_list *parent)
915	{
916	unsigned long nr;
917
918	nr = lock - list_entries;
919	WARN_ON(nr >= nr_list_entries);
920	lock->parent = parent;
921	lock->class->dep_gen_id = lockdep_dependency_gen_id;
922	}
923
924	static inline unsigned long lock_accessed(struct lock_list *lock)
925	{
926	unsigned long nr;
927
928	nr = lock - list_entries;
929	WARN_ON(nr >= nr_list_entries);
930	return lock->class->dep_gen_id == lockdep_dependency_gen_id;
931	}
932
933	static inline struct lock_list get_lock_parent(struct lock_list child)
934	{
935	return child->parent;
936	}
937
938	static inline int get_lock_depth(struct lock_list *child)
939	{
940	int depth = 0;
941	struct lock_list *parent;
942
943	while ((parent = get_lock_parent(child))) {
944	child = parent;
945	depth++;
946	}
947	return depth;
948	}
949
950	static int __bfs(struct lock_list *source_entry,
951	void *data,
952	int (match)(struct lock_list entry, void *data),
953	struct lock_list **target_entry,
954	int forward)
955	{
956	struct lock_list *entry;
957	struct list_head *head;
958	struct circular_queue *cq = &lock_cq;
959	int ret = 1;
960
961	if (match(source_entry, data)) {
962	*target_entry = source_entry;
963	ret = 0;
964	goto exit;
965	}
966
967	if (forward)
968	head = &source_entry->class->locks_after;
969	else
970	head = &source_entry->class->locks_before;
971
972	if (list_empty(head))
973	goto exit;
974
975	__cq_init(cq);
976	__cq_enqueue(cq, (unsigned long)source_entry);
977
978	while (!__cq_empty(cq)) {
979	struct lock_list *lock;
980
981	__cq_dequeue(cq, (unsigned long *)&lock);
982
983	if (!lock->class) {
984	ret = -2;
985	goto exit;
986	}
987
988	if (forward)
989	head = &lock->class->locks_after;
990	else
991	head = &lock->class->locks_before;
992
993	list_for_each_entry(entry, head, entry) {
994	if (!lock_accessed(entry)) {
995	unsigned int cq_depth;
996	mark_lock_accessed(entry, lock);
997	if (match(entry, data)) {
998	*target_entry = entry;
999	ret = 0;
1000	goto exit;
1001	}
1002
1003	if (__cq_enqueue(cq, (unsigned long)entry)) {
1004	ret = -1;
1005	goto exit;
1006	}
1007	cq_depth = __cq_get_elem_count(cq);
1008	if (max_bfs_queue_depth < cq_depth)
1009	max_bfs_queue_depth = cq_depth;
1010	}
1011	}
1012	}
1013	exit:
1014	return ret;
1015	}
1016
1017	static inline int __bfs_forwards(struct lock_list *src_entry,
1018	void *data,
1019	int (match)(struct lock_list entry, void *data),
1020	struct lock_list **target_entry)
1021	{
1022	return __bfs(src_entry, data, match, target_entry, 1);
1023
1024	}
1025
1026	static inline int __bfs_backwards(struct lock_list *src_entry,
1027	void *data,
1028	int (match)(struct lock_list entry, void *data),
1029	struct lock_list **target_entry)
1030	{
1031	return __bfs(src_entry, data, match, target_entry, 0);
1032
1033	}
1034
1035	/*
1036	* Recursive, forwards-direction lock-dependency checking, used for
1037	* both noncyclic checking and for hardirq-unsafe/softirq-unsafe
1038	* checking.
1039	*/
1040
1041	/*
1042	* Print a dependency chain entry (this is only done when a deadlock
1043	* has been detected):
1044	*/
1045	static noinline int
1046	print_circular_bug_entry(struct lock_list *target, int depth)
1047	{
1048	if (debug_locks_silent)
1049	return 0;
1050	printk("\n-> #%u", depth);
1051	print_lock_name(target->class);
1052	printk(":\n");
1053	print_stack_trace(&target->trace, 6);
1054
1055	return 0;
1056	}
1057
1058	/*
1059	* When a circular dependency is detected, print the
1060	* header first:
1061	*/
1062	static noinline int
1063	print_circular_bug_header(struct lock_list *entry, unsigned int depth,
1064	struct held_lock *check_src,
1065	struct held_lock *check_tgt)
1066	{
1067	struct task_struct *curr = current;
1068
1069	if (debug_locks_silent)
1070	return 0;
1071
1072	printk("\n=======================================================\n");
1073	printk( "[ INFO: possible circular locking dependency detected ]\n");
1074	print_kernel_version();
1075	printk( "-------------------------------------------------------\n");
1076	printk("%s/%d is trying to acquire lock:\n",
1077	curr->comm, task_pid_nr(curr));
1078	print_lock(check_src);
1079	printk("\nbut task is already holding lock:\n");
1080	print_lock(check_tgt);
1081	printk("\nwhich lock already depends on the new lock.\n\n");
1082	printk("\nthe existing dependency chain (in reverse order) is:\n");
1083
1084	print_circular_bug_entry(entry, depth);
1085
1086	return 0;
1087	}
1088
1089	static inline int class_equal(struct lock_list entry, void data)
1090	{
1091	return entry->class == data;
1092	}
1093
1094	static noinline int print_circular_bug(struct lock_list *this,
1095	struct lock_list *target,
1096	struct held_lock *check_src,
1097	struct held_lock *check_tgt)
1098	{
1099	struct task_struct *curr = current;
1100	struct lock_list *parent;
1101	int depth;
1102
1103	if (!debug_locks_off_graph_unlock() \|\| debug_locks_silent)
1104	return 0;
1105
1106	if (!save_trace(&this->trace))
1107	return 0;
1108
1109	depth = get_lock_depth(target);
1110
1111	print_circular_bug_header(target, depth, check_src, check_tgt);
1112
1113	parent = get_lock_parent(target);
1114
1115	while (parent) {
1116	print_circular_bug_entry(parent, --depth);
1117	parent = get_lock_parent(parent);
1118	}
1119
1120	printk("\nother info that might help us debug this:\n\n");
1121	lockdep_print_held_locks(curr);
1122
1123	printk("\nstack backtrace:\n");
1124	dump_stack();
1125
1126	return 0;
1127	}
1128
1129	static noinline int print_bfs_bug(int ret)
1130	{
1131	if (!debug_locks_off_graph_unlock())
1132	return 0;
1133
1134	WARN(1, "lockdep bfs error:%d\n", ret);
1135
1136	return 0;
1137	}
1138
1139	static int noop_count(struct lock_list entry, void data)
1140	{
1141	((unsigned long )data)++;
1142	return 0;
1143	}
1144
1145	unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1146	{
1147	unsigned long count = 0;
1148	struct lock_list *uninitialized_var(target_entry);
1149
1150	__bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1151
1152	return count;
1153	}
1154	unsigned long lockdep_count_forward_deps(struct lock_class *class)
1155	{
1156	unsigned long ret, flags;
1157	struct lock_list this;
1158
1159	this.parent = NULL;
1160	this.class = class;
1161
1162	local_irq_save(flags);
1163	arch_spin_lock(&lockdep_lock);
1164	ret = __lockdep_count_forward_deps(&this);
1165	arch_spin_unlock(&lockdep_lock);
1166	local_irq_restore(flags);
1167
1168	return ret;
1169	}
1170
1171	unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1172	{
1173	unsigned long count = 0;
1174	struct lock_list *uninitialized_var(target_entry);
1175
1176	__bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1177
1178	return count;
1179	}
1180
1181	unsigned long lockdep_count_backward_deps(struct lock_class *class)
1182	{
1183	unsigned long ret, flags;
1184	struct lock_list this;
1185
1186	this.parent = NULL;
1187	this.class = class;
1188
1189	local_irq_save(flags);
1190	arch_spin_lock(&lockdep_lock);
1191	ret = __lockdep_count_backward_deps(&this);
1192	arch_spin_unlock(&lockdep_lock);
1193	local_irq_restore(flags);
1194
1195	return ret;
1196	}
1197
1198	/*
1199	* Prove that the dependency graph starting at <entry> can not
1200	* lead to <target>. Print an error and return 0 if it does.
1201	*/
1202	static noinline int
1203	check_noncircular(struct lock_list root, struct lock_class target,
1204	struct lock_list **target_entry)
1205	{
1206	int result;
1207
1208	debug_atomic_inc(&nr_cyclic_checks);
1209
1210	result = __bfs_forwards(root, target, class_equal, target_entry);
1211
1212	return result;
1213	}
1214
1215	#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
1216	/*
1217	* Forwards and backwards subgraph searching, for the purposes of
1218	* proving that two subgraphs can be connected by a new dependency
1219	* without creating any illegal irq-safe -> irq-unsafe lock dependency.
1220	*/
1221
1222	static inline int usage_match(struct lock_list entry, void bit)
1223	{
1224	return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
1225	}
1226
1227
1228
1229	/*
1230	* Find a node in the forwards-direction dependency sub-graph starting
1231	* at @root->class that matches @bit.
1232	*
1233	* Return 0 if such a node exists in the subgraph, and put that node
1234	* into *@target_entry.
1235	*
1236	* Return 1 otherwise and keep *@target_entry unchanged.
1237	* Return <0 on error.
1238	*/
1239	static int
1240	find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
1241	struct lock_list **target_entry)
1242	{
1243	int result;
1244
1245	debug_atomic_inc(&nr_find_usage_forwards_checks);
1246
1247	result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
1248
1249	return result;
1250	}
1251
1252	/*
1253	* Find a node in the backwards-direction dependency sub-graph starting
1254	* at @root->class that matches @bit.
1255	*
1256	* Return 0 if such a node exists in the subgraph, and put that node
1257	* into *@target_entry.
1258	*
1259	* Return 1 otherwise and keep *@target_entry unchanged.
1260	* Return <0 on error.
1261	*/
1262	static int
1263	find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
1264	struct lock_list **target_entry)
1265	{
1266	int result;
1267
1268	debug_atomic_inc(&nr_find_usage_backwards_checks);
1269
1270	result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
1271
1272	return result;
1273	}
1274
1275	static void print_lock_class_header(struct lock_class *class, int depth)
1276	{
1277	int bit;
1278
1279	printk("%*s->", depth, "");
1280	print_lock_name(class);
1281	printk(" ops: %lu", class->ops);
1282	printk(" {\n");
1283
1284	for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
1285	if (class->usage_mask & (1 << bit)) {
1286	int len = depth;
1287
1288	len += printk("%*s %s", depth, "", usage_str[bit]);
1289	len += printk(" at:\n");
1290	print_stack_trace(class->usage_traces + bit, len);
1291	}
1292	}
1293	printk("%*s }\n", depth, "");
1294
1295	printk("%*s ... key at: ",depth,"");
1296	print_ip_sym((unsigned long)class->key);
1297	}
1298
1299	/*
1300	* printk the shortest lock dependencies from @start to @end in reverse order:
1301	*/
1302	static void __used
1303	print_shortest_lock_dependencies(struct lock_list *leaf,
1304	struct lock_list *root)
1305	{
1306	struct lock_list *entry = leaf;
1307	int depth;
1308
1309	/compute depth from generated tree by BFS/
1310	depth = get_lock_depth(leaf);
1311
1312	do {
1313	print_lock_class_header(entry->class, depth);
1314	printk("%*s ... acquired at:\n", depth, "");
1315	print_stack_trace(&entry->trace, 2);
1316	printk("\n");
1317
1318	if (depth == 0 && (entry != root)) {
1319	printk("lockdep:%s bad BFS generated tree\n", __func__);
1320	break;
1321	}
1322
1323	entry = get_lock_parent(entry);
1324	depth--;
1325	} while (entry && (depth >= 0));
1326
1327	return;
1328	}
1329
1330	static int
1331	print_bad_irq_dependency(struct task_struct *curr,
1332	struct lock_list *prev_root,
1333	struct lock_list *next_root,
1334	struct lock_list *backwards_entry,
1335	struct lock_list *forwards_entry,
1336	struct held_lock *prev,
1337	struct held_lock *next,
1338	enum lock_usage_bit bit1,
1339	enum lock_usage_bit bit2,
1340	const char *irqclass)
1341	{
1342	if (!debug_locks_off_graph_unlock() \|\| debug_locks_silent)
1343	return 0;
1344
1345	printk("\n======================================================\n");
1346	printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
1347	irqclass, irqclass);
1348	print_kernel_version();
1349	printk( "------------------------------------------------------\n");
1350	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1351	curr->comm, task_pid_nr(curr),
1352	curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
1353	curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
1354	curr->hardirqs_enabled,
1355	curr->softirqs_enabled);
1356	print_lock(next);
1357
1358	printk("\nand this task is already holding:\n");
1359	print_lock(prev);
1360	printk("which would create a new lock dependency:\n");
1361	print_lock_name(hlock_class(prev));
1362	printk(" ->");
1363	print_lock_name(hlock_class(next));
1364	printk("\n");
1365
1366	printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
1367	irqclass);
1368	print_lock_name(backwards_entry->class);
1369	printk("\n... which became %s-irq-safe at:\n", irqclass);
1370
1371	print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
1372
1373	printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1374	print_lock_name(forwards_entry->class);
1375	printk("\n... which became %s-irq-unsafe at:\n", irqclass);
1376	printk("...");
1377
1378	print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
1379
1380	printk("\nother info that might help us debug this:\n\n");
1381	lockdep_print_held_locks(curr);
1382
1383	printk("\nthe dependencies between %s-irq-safe lock", irqclass);
1384	printk(" and the holding lock:\n");
1385	if (!save_trace(&prev_root->trace))
1386	return 0;
1387	print_shortest_lock_dependencies(backwards_entry, prev_root);
1388
1389	printk("\nthe dependencies between the lock to be acquired");
1390	printk(" and %s-irq-unsafe lock:\n", irqclass);
1391	if (!save_trace(&next_root->trace))
1392	return 0;
1393	print_shortest_lock_dependencies(forwards_entry, next_root);
1394
1395	printk("\nstack backtrace:\n");
1396	dump_stack();
1397
1398	return 0;
1399	}
1400
1401	static int
1402	check_usage(struct task_struct curr, struct held_lock prev,
1403	struct held_lock *next, enum lock_usage_bit bit_backwards,
1404	enum lock_usage_bit bit_forwards, const char *irqclass)
1405	{
1406	int ret;
1407	struct lock_list this, that;
1408	struct lock_list *uninitialized_var(target_entry);
1409	struct lock_list *uninitialized_var(target_entry1);
1410
1411	this.parent = NULL;
1412
1413	this.class = hlock_class(prev);
1414	ret = find_usage_backwards(&this, bit_backwards, &target_entry);
1415	if (ret < 0)
1416	return print_bfs_bug(ret);
1417	if (ret == 1)
1418	return ret;
1419
1420	that.parent = NULL;
1421	that.class = hlock_class(next);
1422	ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
1423	if (ret < 0)
1424	return print_bfs_bug(ret);
1425	if (ret == 1)
1426	return ret;
1427
1428	return print_bad_irq_dependency(curr, &this, &that,
1429	target_entry, target_entry1,
1430	prev, next,
1431	bit_backwards, bit_forwards, irqclass);
1432	}
1433
1434	static const char *state_names[] = {
1435	#define LOCKDEP_STATE(__STATE) \
1436	__stringify(__STATE),
1437	#include "lockdep_states.h"
1438	#undef LOCKDEP_STATE
1439	};
1440
1441	static const char *state_rnames[] = {
1442	#define LOCKDEP_STATE(__STATE) \
1443	__stringify(__STATE)"-READ",
1444	#include "lockdep_states.h"
1445	#undef LOCKDEP_STATE
1446	};
1447
1448	static inline const char *state_name(enum lock_usage_bit bit)
1449	{
1450	return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
1451	}
1452
1453	static int exclusive_bit(int new_bit)
1454	{
1455	/*
1456	* USED_IN
1457	* USED_IN_READ
1458	* ENABLED
1459	* ENABLED_READ
1460	*
1461	* bit 0 - write/read
1462	* bit 1 - used_in/enabled
1463	* bit 2+ state
1464	*/
1465
1466	int state = new_bit & ~3;
1467	int dir = new_bit & 2;
1468
1469	/*
1470	* keep state, bit flip the direction and strip read.
1471	*/
1472	return state \| (dir ^ 2);
1473	}
1474
1475	static int check_irq_usage(struct task_struct curr, struct held_lock prev,
1476	struct held_lock *next, enum lock_usage_bit bit)
1477	{
1478	/*
1479	* Prove that the new dependency does not connect a hardirq-safe
1480	* lock with a hardirq-unsafe lock - to achieve this we search
1481	* the backwards-subgraph starting at <prev>, and the
1482	* forwards-subgraph starting at <next>:
1483	*/
1484	if (!check_usage(curr, prev, next, bit,
1485	exclusive_bit(bit), state_name(bit)))
1486	return 0;
1487
1488	bit++; /* _READ */
1489
1490	/*
1491	* Prove that the new dependency does not connect a hardirq-safe-read
1492	* lock with a hardirq-unsafe lock - to achieve this we search
1493	* the backwards-subgraph starting at <prev>, and the
1494	* forwards-subgraph starting at <next>:
1495	*/
1496	if (!check_usage(curr, prev, next, bit,
1497	exclusive_bit(bit), state_name(bit)))
1498	return 0;
1499
1500	return 1;
1501	}
1502
1503	static int
1504	check_prev_add_irq(struct task_struct curr, struct held_lock prev,
1505	struct held_lock *next)
1506	{
1507	#define LOCKDEP_STATE(__STATE) \
1508	if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
1509	return 0;
1510	#include "lockdep_states.h"
1511	#undef LOCKDEP_STATE
1512
1513	return 1;
1514	}
1515
1516	static void inc_chains(void)
1517	{
1518	if (current->hardirq_context)
1519	nr_hardirq_chains++;
1520	else {
1521	if (current->softirq_context)
1522	nr_softirq_chains++;
1523	else
1524	nr_process_chains++;
1525	}
1526	}
1527
1528	#else
1529
1530	static inline int
1531	check_prev_add_irq(struct task_struct curr, struct held_lock prev,
1532	struct held_lock *next)
1533	{
1534	return 1;
1535	}
1536
1537	static inline void inc_chains(void)
1538	{
1539	nr_process_chains++;
1540	}
1541
1542	#endif
1543
1544	static int
1545	print_deadlock_bug(struct task_struct curr, struct held_lock prev,
1546	struct held_lock *next)
1547	{
1548	if (!debug_locks_off_graph_unlock() \|\| debug_locks_silent)
1549	return 0;
1550
1551	printk("\n=============================================\n");
1552	printk( "[ INFO: possible recursive locking detected ]\n");
1553	print_kernel_version();
1554	printk( "---------------------------------------------\n");
1555	printk("%s/%d is trying to acquire lock:\n",
1556	curr->comm, task_pid_nr(curr));
1557	print_lock(next);
1558	printk("\nbut task is already holding lock:\n");
1559	print_lock(prev);
1560
1561	printk("\nother info that might help us debug this:\n");
1562	lockdep_print_held_locks(curr);
1563
1564	printk("\nstack backtrace:\n");
1565	dump_stack();
1566
1567	return 0;
1568	}
1569
1570	/*
1571	* Check whether we are holding such a class already.
1572	*
1573	* (Note that this has to be done separately, because the graph cannot
1574	* detect such classes of deadlocks.)
1575	*
1576	* Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
1577	*/
1578	static int
1579	check_deadlock(struct task_struct curr, struct held_lock next,
1580	struct lockdep_map *next_instance, int read)
1581	{
1582	struct held_lock *prev;
1583	struct held_lock *nest = NULL;
1584	int i;
1585
1586	for (i = 0; i < curr->lockdep_depth; i++) {
1587	prev = curr->held_locks + i;
1588
1589	if (prev->instance == next->nest_lock)
1590	nest = prev;
1591
1592	if (hlock_class(prev) != hlock_class(next))
1593	continue;
1594
1595	/*
1596	* Allow read-after-read recursion of the same
1597	* lock class (i.e. read_lock(lock)+read_lock(lock)):
1598	*/
1599	if ((read == 2) && prev->read)
1600	return 2;
1601
1602	/*
1603	* We're holding the nest_lock, which serializes this lock's
1604	* nesting behaviour.
1605	*/
1606	if (nest)
1607	return 2;
1608
1609	return print_deadlock_bug(curr, prev, next);
1610	}
1611	return 1;
1612	}
1613
1614	/*
1615	* There was a chain-cache miss, and we are about to add a new dependency
1616	* to a previous lock. We recursively validate the following rules:
1617	*
1618	* - would the adding of the <prev> -> <next> dependency create a
1619	* circular dependency in the graph? [== circular deadlock]
1620	*
1621	* - does the new prev->next dependency connect any hardirq-safe lock
1622	* (in the full backwards-subgraph starting at <prev>) with any
1623	* hardirq-unsafe lock (in the full forwards-subgraph starting at
1624	* <next>)? [== illegal lock inversion with hardirq contexts]
1625	*
1626	* - does the new prev->next dependency connect any softirq-safe lock
1627	* (in the full backwards-subgraph starting at <prev>) with any
1628	* softirq-unsafe lock (in the full forwards-subgraph starting at
1629	* <next>)? [== illegal lock inversion with softirq contexts]
1630	*
1631	* any of these scenarios could lead to a deadlock.
1632	*
1633	* Then if all the validations pass, we add the forwards and backwards
1634	* dependency.
1635	*/
1636	static int
1637	check_prev_add(struct task_struct curr, struct held_lock prev,
1638	struct held_lock *next, int distance)
1639	{
1640	struct lock_list *entry;
1641	int ret;
1642	struct lock_list this;
1643	struct lock_list *uninitialized_var(target_entry);
1644
1645	/*
1646	* Prove that the new <prev> -> <next> dependency would not
1647	* create a circular dependency in the graph. (We do this by
1648	* forward-recursing into the graph starting at <next>, and
1649	* checking whether we can reach <prev>.)
1650	*
1651	* We are using global variables to control the recursion, to
1652	* keep the stackframe size of the recursive functions low:
1653	*/
1654	this.class = hlock_class(next);
1655	this.parent = NULL;
1656	ret = check_noncircular(&this, hlock_class(prev), &target_entry);
1657	if (unlikely(!ret))
1658	return print_circular_bug(&this, target_entry, next, prev);
1659	else if (unlikely(ret < 0))
1660	return print_bfs_bug(ret);
1661
1662	if (!check_prev_add_irq(curr, prev, next))
1663	return 0;
1664
1665	/*
1666	* For recursive read-locks we do all the dependency checks,
1667	* but we dont store read-triggered dependencies (only
1668	* write-triggered dependencies). This ensures that only the
1669	* write-side dependencies matter, and that if for example a
1670	* write-lock never takes any other locks, then the reads are
1671	* equivalent to a NOP.
1672	*/
1673	if (next->read == 2 \|\| prev->read == 2)
1674	return 1;
1675	/*
1676	* Is the <prev> -> <next> dependency already present?
1677	*
1678	* (this may occur even though this is a new chain: consider
1679	* e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
1680	* chains - the second one will be new, but L1 already has
1681	* L2 added to its dependency list, due to the first chain.)
1682	*/
1683	list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
1684	if (entry->class == hlock_class(next)) {
1685	if (distance == 1)
1686	entry->distance = 1;
1687	return 2;
1688	}
1689	}
1690
1691	/*
1692	* Ok, all validations passed, add the new lock
1693	* to the previous lock's dependency list:
1694	*/
1695	ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
1696	&hlock_class(prev)->locks_after,
1697	next->acquire_ip, distance);
1698
1699	if (!ret)
1700	return 0;
1701
1702	ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
1703	&hlock_class(next)->locks_before,
1704	next->acquire_ip, distance);
1705	if (!ret)
1706	return 0;
1707
1708	/*
1709	* Debugging printouts:
1710	*/
1711	if (verbose(hlock_class(prev)) \|\| verbose(hlock_class(next))) {
1712	graph_unlock();
1713	printk("\n new dependency: ");
1714	print_lock_name(hlock_class(prev));
1715	printk(" => ");
1716	print_lock_name(hlock_class(next));
1717	printk("\n");
1718	dump_stack();
1719	return graph_lock();
1720	}
1721	return 1;
1722	}
1723
1724	/*
1725	* Add the dependency to all directly-previous locks that are 'relevant'.
1726	* The ones that are relevant are (in increasing distance from curr):
1727	* all consecutive trylock entries and the final non-trylock entry - or
1728	* the end of this context's lock-chain - whichever comes first.
1729	*/
1730	static int
1731	check_prevs_add(struct task_struct curr, struct held_lock next)
1732	{
1733	int depth = curr->lockdep_depth;
1734	struct held_lock *hlock;
1735
1736	/*
1737	* Debugging checks.
1738	*
1739	* Depth must not be zero for a non-head lock:
1740	*/
1741	if (!depth)
1742	goto out_bug;
1743	/*
1744	* At least two relevant locks must exist for this
1745	* to be a head:
1746	*/
1747	if (curr->held_locks[depth].irq_context !=
1748	curr->held_locks[depth-1].irq_context)
1749	goto out_bug;
1750
1751	for (;;) {
1752	int distance = curr->lockdep_depth - depth + 1;
1753	hlock = curr->held_locks + depth-1;
1754	/*
1755	* Only non-recursive-read entries get new dependencies
1756	* added:
1757	*/
1758	if (hlock->read != 2) {
1759	if (!check_prev_add(curr, hlock, next, distance))
1760	return 0;
1761	/*
1762	* Stop after the first non-trylock entry,
1763	* as non-trylock entries have added their
1764	* own direct dependencies already, so this
1765	* lock is connected to them indirectly:
1766	*/
1767	if (!hlock->trylock)
1768	break;
1769	}
1770	depth--;
1771	/*
1772	* End of lock-stack?
1773	*/
1774	if (!depth)
1775	break;
1776	/*
1777	* Stop the search if we cross into another context:
1778	*/
1779	if (curr->held_locks[depth].irq_context !=
1780	curr->held_locks[depth-1].irq_context)
1781	break;
1782	}
1783	return 1;
1784	out_bug:
1785	if (!debug_locks_off_graph_unlock())
1786	return 0;
1787
1788	WARN_ON(1);
1789
1790	return 0;
1791	}
1792
1793	unsigned long nr_lock_chains;
1794	struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1795	int nr_chain_hlocks;
1796	static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
1797
1798	struct lock_class lock_chain_get_class(struct lock_chain chain, int i)
1799	{
1800	return lock_classes + chain_hlocks[chain->base + i];
1801	}
1802
1803	/*
1804	* Look up a dependency chain. If the key is not present yet then
1805	* add it and return 1 - in this case the new dependency chain is
1806	* validated. If the key is already hashed, return 0.
1807	* (On return with 1 graph_lock is held.)
1808	*/
1809	static inline int lookup_chain_cache(struct task_struct *curr,
1810	struct held_lock *hlock,
1811	u64 chain_key)
1812	{
1813	struct lock_class *class = hlock_class(hlock);
1814	struct list_head *hash_head = chainhashentry(chain_key);
1815	struct lock_chain *chain;
1816	struct held_lock hlock_curr, hlock_next;
1817	int i, j, n, cn;
1818
1819	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
1820	return 0;
1821	/*
1822	* We can walk it lock-free, because entries only get added
1823	* to the hash:
1824	*/
1825	list_for_each_entry(chain, hash_head, entry) {
1826	if (chain->chain_key == chain_key) {
1827	cache_hit:
1828	debug_atomic_inc(&chain_lookup_hits);
1829	if (very_verbose(class))
1830	printk("\nhash chain already cached, key: "
1831	"%016Lx tail class: [%p] %s\n",
1832	(unsigned long long)chain_key,
1833	class->key, class->name);
1834	return 0;
1835	}
1836	}
1837	if (very_verbose(class))
1838	printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
1839	(unsigned long long)chain_key, class->key, class->name);
1840	/*
1841	* Allocate a new chain entry from the static array, and add
1842	* it to the hash:
1843	*/
1844	if (!graph_lock())
1845	return 0;
1846	/*
1847	* We have to walk the chain again locked - to avoid duplicates:
1848	*/
1849	list_for_each_entry(chain, hash_head, entry) {
1850	if (chain->chain_key == chain_key) {
1851	graph_unlock();
1852	goto cache_hit;
1853	}
1854	}
1855	if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1856	if (!debug_locks_off_graph_unlock())
1857	return 0;
1858
1859	printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
1860	printk("turning off the locking correctness validator.\n");
1861	dump_stack();
1862	return 0;
1863	}
1864	chain = lock_chains + nr_lock_chains++;
1865	chain->chain_key = chain_key;
1866	chain->irq_context = hlock->irq_context;
1867	/* Find the first held_lock of current chain */
1868	hlock_next = hlock;
1869	for (i = curr->lockdep_depth - 1; i >= 0; i--) {
1870	hlock_curr = curr->held_locks + i;
1871	if (hlock_curr->irq_context != hlock_next->irq_context)
1872	break;
1873	hlock_next = hlock;
1874	}
1875	i++;
1876	chain->depth = curr->lockdep_depth + 1 - i;
1877	cn = nr_chain_hlocks;
1878	while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
1879	n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
1880	if (n == cn)
1881	break;
1882	cn = n;
1883	}
1884	if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
1885	chain->base = cn;
1886	for (j = 0; j < chain->depth - 1; j++, i++) {
1887	int lock_id = curr->held_locks[i].class_idx - 1;
1888	chain_hlocks[chain->base + j] = lock_id;
1889	}
1890	chain_hlocks[chain->base + j] = class - lock_classes;
1891	}
1892	list_add_tail_rcu(&chain->entry, hash_head);
1893	debug_atomic_inc(&chain_lookup_misses);
1894	inc_chains();
1895
1896	return 1;
1897	}
1898
1899	static int validate_chain(struct task_struct curr, struct lockdep_map lock,
1900	struct held_lock *hlock, int chain_head, u64 chain_key)
1901	{
1902	/*
1903	* Trylock needs to maintain the stack of held locks, but it
1904	* does not add new dependencies, because trylock can be done
1905	* in any order.
1906	*
1907	* We look up the chain_key and do the O(N^2) check and update of
1908	* the dependencies only if this is a new dependency chain.
1909	* (If lookup_chain_cache() returns with 1 it acquires
1910	* graph_lock for us)
1911	*/
1912	if (!hlock->trylock && (hlock->check == 2) &&
1913	lookup_chain_cache(curr, hlock, chain_key)) {
1914	/*
1915	* Check whether last held lock:
1916	*
1917	* - is irq-safe, if this lock is irq-unsafe
1918	* - is softirq-safe, if this lock is hardirq-unsafe
1919	*
1920	* And check whether the new lock's dependency graph
1921	* could lead back to the previous lock.
1922	*
1923	* any of these scenarios could lead to a deadlock. If
1924	* All validations
1925	*/
1926	int ret = check_deadlock(curr, hlock, lock, hlock->read);
1927
1928	if (!ret)
1929	return 0;
1930	/*
1931	* Mark recursive read, as we jump over it when
1932	* building dependencies (just like we jump over
1933	* trylock entries):
1934	*/
1935	if (ret == 2)
1936	hlock->read = 2;
1937	/*
1938	* Add dependency only if this lock is not the head
1939	* of the chain, and if it's not a secondary read-lock:
1940	*/
1941	if (!chain_head && ret != 2)
1942	if (!check_prevs_add(curr, hlock))
1943	return 0;
1944	graph_unlock();
1945	} else
1946	/* after lookup_chain_cache(): */
1947	if (unlikely(!debug_locks))
1948	return 0;
1949
1950	return 1;
1951	}
1952	#else
1953	static inline int validate_chain(struct task_struct *curr,
1954	struct lockdep_map lock, struct held_lock hlock,
1955	int chain_head, u64 chain_key)
1956	{
1957	return 1;
1958	}
1959	#endif
1960
1961	/*
1962	* We are building curr_chain_key incrementally, so double-check
1963	* it from scratch, to make sure that it's done correctly:
1964	*/
1965	static void check_chain_key(struct task_struct *curr)
1966	{
1967	#ifdef CONFIG_DEBUG_LOCKDEP
1968	struct held_lock hlock, prev_hlock = NULL;
1969	unsigned int i, id;
1970	u64 chain_key = 0;
1971
1972	for (i = 0; i < curr->lockdep_depth; i++) {
1973	hlock = curr->held_locks + i;
1974	if (chain_key != hlock->prev_chain_key) {
1975	debug_locks_off();
1976	WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
1977	curr->lockdep_depth, i,
1978	(unsigned long long)chain_key,
1979	(unsigned long long)hlock->prev_chain_key);
1980	return;
1981	}
1982	id = hlock->class_idx - 1;
1983	if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
1984	return;
1985
1986	if (prev_hlock && (prev_hlock->irq_context !=
1987	hlock->irq_context))
1988	chain_key = 0;
1989	chain_key = iterate_chain_key(chain_key, id);
1990	prev_hlock = hlock;
1991	}
1992	if (chain_key != curr->curr_chain_key) {
1993	debug_locks_off();
1994	WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
1995	curr->lockdep_depth, i,
1996	(unsigned long long)chain_key,
1997	(unsigned long long)curr->curr_chain_key);
1998	}
1999	#endif
2000	}
2001
2002	static int
2003	print_usage_bug(struct task_struct curr, struct held_lock this,
2004	enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
2005	{
2006	if (!debug_locks_off_graph_unlock() \|\| debug_locks_silent)
2007	return 0;
2008
2009	printk("\n=================================\n");
2010	printk( "[ INFO: inconsistent lock state ]\n");
2011	print_kernel_version();
2012	printk( "---------------------------------\n");
2013
2014	printk("inconsistent {%s} -> {%s} usage.\n",
2015	usage_str[prev_bit], usage_str[new_bit]);
2016
2017	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2018	curr->comm, task_pid_nr(curr),
2019	trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
2020	trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
2021	trace_hardirqs_enabled(curr),
2022	trace_softirqs_enabled(curr));
2023	print_lock(this);
2024
2025	printk("{%s} state was registered at:\n", usage_str[prev_bit]);
2026	print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
2027
2028	print_irqtrace_events(curr);
2029	printk("\nother info that might help us debug this:\n");
2030	lockdep_print_held_locks(curr);
2031
2032	printk("\nstack backtrace:\n");
2033	dump_stack();
2034
2035	return 0;
2036	}
2037
2038	/*
2039	* Print out an error if an invalid bit is set:
2040	*/
2041	static inline int
2042	valid_state(struct task_struct curr, struct held_lock this,
2043	enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
2044	{
2045	if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
2046	return print_usage_bug(curr, this, bad_bit, new_bit);
2047	return 1;
2048	}
2049
2050	static int mark_lock(struct task_struct curr, struct held_lock this,
2051	enum lock_usage_bit new_bit);
2052
2053	#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
2054
2055	/*
2056	* print irq inversion bug:
2057	*/
2058	static int
2059	print_irq_inversion_bug(struct task_struct *curr,
2060	struct lock_list root, struct lock_list other,
2061	struct held_lock *this, int forwards,
2062	const char *irqclass)
2063	{
2064	if (!debug_locks_off_graph_unlock() \|\| debug_locks_silent)
2065	return 0;
2066
2067	printk("\n=========================================================\n");
2068	printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
2069	print_kernel_version();
2070	printk( "---------------------------------------------------------\n");
2071	printk("%s/%d just changed the state of lock:\n",
2072	curr->comm, task_pid_nr(curr));
2073	print_lock(this);
2074	if (forwards)
2075	printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
2076	else
2077	printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2078	print_lock_name(other->class);
2079	printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
2080
2081	printk("\nother info that might help us debug this:\n");
2082	lockdep_print_held_locks(curr);
2083
2084	printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
2085	if (!save_trace(&root->trace))
2086	return 0;
2087	print_shortest_lock_dependencies(other, root);
2088
2089	printk("\nstack backtrace:\n");
2090	dump_stack();
2091
2092	return 0;
2093	}
2094
2095	/*
2096	* Prove that in the forwards-direction subgraph starting at <this>
2097	* there is no lock matching <mask>:
2098	*/
2099	static int
2100	check_usage_forwards(struct task_struct curr, struct held_lock this,
2101	enum lock_usage_bit bit, const char *irqclass)
2102	{
2103	int ret;
2104	struct lock_list root;
2105	struct lock_list *uninitialized_var(target_entry);
2106
2107	root.parent = NULL;
2108	root.class = hlock_class(this);
2109	ret = find_usage_forwards(&root, bit, &target_entry);
2110	if (ret < 0)
2111	return print_bfs_bug(ret);
2112	if (ret == 1)
2113	return ret;
2114
2115	return print_irq_inversion_bug(curr, &root, target_entry,
2116	this, 1, irqclass);
2117	}
2118
2119	/*
2120	* Prove that in the backwards-direction subgraph starting at <this>
2121	* there is no lock matching <mask>:
2122	*/
2123	static int
2124	check_usage_backwards(struct task_struct curr, struct held_lock this,
2125	enum lock_usage_bit bit, const char *irqclass)
2126	{
2127	int ret;
2128	struct lock_list root;
2129	struct lock_list *uninitialized_var(target_entry);
2130
2131	root.parent = NULL;
2132	root.class = hlock_class(this);
2133	ret = find_usage_backwards(&root, bit, &target_entry);
2134	if (ret < 0)
2135	return print_bfs_bug(ret);
2136	if (ret == 1)
2137	return ret;
2138
2139	return print_irq_inversion_bug(curr, &root, target_entry,
2140	this, 0, irqclass);
2141	}
2142
2143	void print_irqtrace_events(struct task_struct *curr)
2144	{
2145	printk("irq event stamp: %u\n", curr->irq_events);
2146	printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
2147	print_ip_sym(curr->hardirq_enable_ip);
2148	printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
2149	print_ip_sym(curr->hardirq_disable_ip);
2150	printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
2151	print_ip_sym(curr->softirq_enable_ip);
2152	printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
2153	print_ip_sym(curr->softirq_disable_ip);
2154	}
2155
2156	static int HARDIRQ_verbose(struct lock_class *class)
2157	{
2158	#if HARDIRQ_VERBOSE
2159	return class_filter(class);
2160	#endif
2161	return 0;
2162	}
2163
2164	static int SOFTIRQ_verbose(struct lock_class *class)
2165	{
2166	#if SOFTIRQ_VERBOSE
2167	return class_filter(class);
2168	#endif
2169	return 0;
2170	}
2171
2172	static int RECLAIM_FS_verbose(struct lock_class *class)
2173	{
2174	#if RECLAIM_VERBOSE
2175	return class_filter(class);
2176	#endif
2177	return 0;
2178	}
2179
2180	#define STRICT_READ_CHECKS 1
2181
2182	static int (state_verbose_f[])(struct lock_class class) = {
2183	#define LOCKDEP_STATE(__STATE) \
2184	__STATE##_verbose,
2185	#include "lockdep_states.h"
2186	#undef LOCKDEP_STATE
2187	};
2188
2189	static inline int state_verbose(enum lock_usage_bit bit,
2190	struct lock_class *class)
2191	{
2192	return state_verbose_f[bit >> 2](class);
2193	}
2194
2195	typedef int (check_usage_f)(struct task_struct , struct held_lock *,
2196	enum lock_usage_bit bit, const char *name);
2197
2198	static int
2199	mark_lock_irq(struct task_struct curr, struct held_lock this,
2200	enum lock_usage_bit new_bit)
2201	{
2202	int excl_bit = exclusive_bit(new_bit);
2203	int read = new_bit & 1;
2204	int dir = new_bit & 2;
2205
2206	/*
2207	* mark USED_IN has to look forwards -- to ensure no dependency
2208	* has ENABLED state, which would allow recursion deadlocks.
2209	*
2210	* mark ENABLED has to look backwards -- to ensure no dependee
2211	* has USED_IN state, which, again, would allow recursion deadlocks.
2212	*/
2213	check_usage_f usage = dir ?
2214	check_usage_backwards : check_usage_forwards;
2215
2216	/*
2217	* Validate that this particular lock does not have conflicting
2218	* usage states.
2219	*/
2220	if (!valid_state(curr, this, new_bit, excl_bit))
2221	return 0;
2222
2223	/*
2224	* Validate that the lock dependencies don't have conflicting usage
2225	* states.
2226	*/
2227	if ((!read \|\| !dir \|\| STRICT_READ_CHECKS) &&
2228	!usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2229	return 0;
2230
2231	/*
2232	* Check for read in write conflicts
2233	*/
2234	if (!read) {
2235	if (!valid_state(curr, this, new_bit, excl_bit + 1))
2236	return 0;
2237
2238	if (STRICT_READ_CHECKS &&
2239	!usage(curr, this, excl_bit + 1,
2240	state_name(new_bit + 1)))
2241	return 0;
2242	}
2243
2244	if (state_verbose(new_bit, hlock_class(this)))
2245	return 2;
2246
2247	return 1;
2248	}
2249
2250	enum mark_type {
2251	#define LOCKDEP_STATE(__STATE) __STATE,
2252	#include "lockdep_states.h"
2253	#undef LOCKDEP_STATE
2254	};
2255
2256	/*
2257	* Mark all held locks with a usage bit:
2258	*/
2259	static int
2260	mark_held_locks(struct task_struct *curr, enum mark_type mark)
2261	{
2262	enum lock_usage_bit usage_bit;
2263	struct held_lock *hlock;
2264	int i;
2265
2266	for (i = 0; i < curr->lockdep_depth; i++) {
2267	hlock = curr->held_locks + i;
2268
2269	usage_bit = 2 + (mark << 2); /* ENABLED */
2270	if (hlock->read)
2271	usage_bit += 1; /* READ */
2272
2273	BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2274
2275	if (!mark_lock(curr, hlock, usage_bit))
2276	return 0;
2277	}
2278
2279	return 1;
2280	}
2281
2282	/*
2283	* Debugging helper: via this flag we know that we are in
2284	* 'early bootup code', and will warn about any invalid irqs-on event:
2285	*/
2286	static int early_boot_irqs_enabled;
2287
2288	void early_boot_irqs_off(void)
2289	{
2290	early_boot_irqs_enabled = 0;
2291	}
2292
2293	void early_boot_irqs_on(void)
2294	{
2295	early_boot_irqs_enabled = 1;
2296	}
2297
2298	/*
2299	* Hardirqs will be enabled:
2300	*/
2301	void trace_hardirqs_on_caller(unsigned long ip)
2302	{
2303	struct task_struct *curr = current;
2304
2305	time_hardirqs_on(CALLER_ADDR0, ip);
2306
2307	if (unlikely(!debug_locks \|\| current->lockdep_recursion))
2308	return;
2309
2310	if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
2311	return;
2312
2313	if (unlikely(curr->hardirqs_enabled)) {
2314	debug_atomic_inc(&redundant_hardirqs_on);
2315	return;
2316	}
2317	/* we'll do an OFF -> ON transition: */
2318	curr->hardirqs_enabled = 1;
2319
2320	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2321	return;
2322	if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
2323	return;
2324	/*
2325	* We are going to turn hardirqs on, so set the
2326	* usage bit for all held locks:
2327	*/
2328	if (!mark_held_locks(curr, HARDIRQ))
2329	return;
2330	/*
2331	* If we have softirqs enabled, then set the usage
2332	* bit for all held locks. (disabled hardirqs prevented
2333	* this bit from being set before)
2334	*/
2335	if (curr->softirqs_enabled)
2336	if (!mark_held_locks(curr, SOFTIRQ))
2337	return;
2338
2339	curr->hardirq_enable_ip = ip;
2340	curr->hardirq_enable_event = ++curr->irq_events;
2341	debug_atomic_inc(&hardirqs_on_events);
2342	}
2343	EXPORT_SYMBOL(trace_hardirqs_on_caller);
2344
2345	void trace_hardirqs_on(void)
2346	{
2347	trace_hardirqs_on_caller(CALLER_ADDR0);
2348	}
2349	EXPORT_SYMBOL(trace_hardirqs_on);
2350
2351	/*
2352	* Hardirqs were disabled:
2353	*/
2354	void trace_hardirqs_off_caller(unsigned long ip)
2355	{
2356	struct task_struct *curr = current;
2357
2358	time_hardirqs_off(CALLER_ADDR0, ip);
2359
2360	if (unlikely(!debug_locks \|\| current->lockdep_recursion))
2361	return;
2362
2363	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2364	return;
2365
2366	if (curr->hardirqs_enabled) {
2367	/*
2368	* We have done an ON -> OFF transition:
2369	*/
2370	curr->hardirqs_enabled = 0;
2371	curr->hardirq_disable_ip = ip;
2372	curr->hardirq_disable_event = ++curr->irq_events;
2373	debug_atomic_inc(&hardirqs_off_events);
2374	} else
2375	debug_atomic_inc(&redundant_hardirqs_off);
2376	}
2377	EXPORT_SYMBOL(trace_hardirqs_off_caller);
2378
2379	void trace_hardirqs_off(void)
2380	{
2381	trace_hardirqs_off_caller(CALLER_ADDR0);
2382	}
2383	EXPORT_SYMBOL(trace_hardirqs_off);
2384
2385	/*
2386	* Softirqs will be enabled:
2387	*/
2388	void trace_softirqs_on(unsigned long ip)
2389	{
2390	struct task_struct *curr = current;
2391
2392	if (unlikely(!debug_locks))
2393	return;
2394
2395	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2396	return;
2397
2398	if (curr->softirqs_enabled) {
2399	debug_atomic_inc(&redundant_softirqs_on);
2400	return;
2401	}
2402
2403	/*
2404	* We'll do an OFF -> ON transition:
2405	*/
2406	curr->softirqs_enabled = 1;
2407	curr->softirq_enable_ip = ip;
2408	curr->softirq_enable_event = ++curr->irq_events;
2409	debug_atomic_inc(&softirqs_on_events);
2410	/*
2411	* We are going to turn softirqs on, so set the
2412	* usage bit for all held locks, if hardirqs are
2413	* enabled too:
2414	*/
2415	if (curr->hardirqs_enabled)
2416	mark_held_locks(curr, SOFTIRQ);
2417	}
2418
2419	/*
2420	* Softirqs were disabled:
2421	*/
2422	void trace_softirqs_off(unsigned long ip)
2423	{
2424	struct task_struct *curr = current;
2425
2426	if (unlikely(!debug_locks))
2427	return;
2428
2429	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2430	return;
2431
2432	if (curr->softirqs_enabled) {
2433	/*
2434	* We have done an ON -> OFF transition:
2435	*/
2436	curr->softirqs_enabled = 0;
2437	curr->softirq_disable_ip = ip;
2438	curr->softirq_disable_event = ++curr->irq_events;
2439	debug_atomic_inc(&softirqs_off_events);
2440	DEBUG_LOCKS_WARN_ON(!softirq_count());
2441	} else
2442	debug_atomic_inc(&redundant_softirqs_off);
2443	}
2444
2445	static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2446	{
2447	struct task_struct *curr = current;
2448
2449	if (unlikely(!debug_locks))
2450	return;
2451
2452	/* no reclaim without waiting on it */
2453	if (!(gfp_mask & __GFP_WAIT))
2454	return;
2455
2456	/* this guy won't enter reclaim */
2457	if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
2458	return;
2459
2460	/* We're only interested __GFP_FS allocations for now */
2461	if (!(gfp_mask & __GFP_FS))
2462	return;
2463
2464	if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2465	return;
2466
2467	mark_held_locks(curr, RECLAIM_FS);
2468	}
2469
2470	static void check_flags(unsigned long flags);
2471
2472	void lockdep_trace_alloc(gfp_t gfp_mask)
2473	{
2474	unsigned long flags;
2475
2476	if (unlikely(current->lockdep_recursion))
2477	return;
2478
2479	raw_local_irq_save(flags);
2480	check_flags(flags);
2481	current->lockdep_recursion = 1;
2482	__lockdep_trace_alloc(gfp_mask, flags);
2483	current->lockdep_recursion = 0;
2484	raw_local_irq_restore(flags);
2485	}
2486
2487	static int mark_irqflags(struct task_struct curr, struct held_lock hlock)
2488	{
2489	/*
2490	* If non-trylock use in a hardirq or softirq context, then
2491	* mark the lock as used in these contexts:
2492	*/
2493	if (!hlock->trylock) {
2494	if (hlock->read) {
2495	if (curr->hardirq_context)
2496	if (!mark_lock(curr, hlock,
2497	LOCK_USED_IN_HARDIRQ_READ))
2498	return 0;
2499	if (curr->softirq_context)
2500	if (!mark_lock(curr, hlock,
2501	LOCK_USED_IN_SOFTIRQ_READ))
2502	return 0;
2503	} else {
2504	if (curr->hardirq_context)
2505	if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
2506	return 0;
2507	if (curr->softirq_context)
2508	if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
2509	return 0;
2510	}
2511	}
2512	if (!hlock->hardirqs_off) {
2513	if (hlock->read) {
2514	if (!mark_lock(curr, hlock,
2515	LOCK_ENABLED_HARDIRQ_READ))
2516	return 0;
2517	if (curr->softirqs_enabled)
2518	if (!mark_lock(curr, hlock,
2519	LOCK_ENABLED_SOFTIRQ_READ))
2520	return 0;
2521	} else {
2522	if (!mark_lock(curr, hlock,
2523	LOCK_ENABLED_HARDIRQ))
2524	return 0;
2525	if (curr->softirqs_enabled)
2526	if (!mark_lock(curr, hlock,
2527	LOCK_ENABLED_SOFTIRQ))
2528	return 0;
2529	}
2530	}
2531
2532	/*
2533	* We reuse the irq context infrastructure more broadly as a general
2534	* context checking code. This tests GFP_FS recursion (a lock taken
2535	* during reclaim for a GFP_FS allocation is held over a GFP_FS
2536	* allocation).
2537	*/
2538	if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
2539	if (hlock->read) {
2540	if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
2541	return 0;
2542	} else {
2543	if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
2544	return 0;
2545	}
2546	}
2547
2548	return 1;
2549	}
2550
2551	static int separate_irq_context(struct task_struct *curr,
2552	struct held_lock *hlock)
2553	{
2554	unsigned int depth = curr->lockdep_depth;
2555
2556	/*
2557	* Keep track of points where we cross into an interrupt context:
2558	*/
2559	hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
2560	curr->softirq_context;
2561	if (depth) {
2562	struct held_lock *prev_hlock;
2563
2564	prev_hlock = curr->held_locks + depth-1;
2565	/*
2566	* If we cross into another context, reset the
2567	* hash key (this also prevents the checking and the
2568	* adding of the dependency to 'prev'):
2569	*/
2570	if (prev_hlock->irq_context != hlock->irq_context)
2571	return 1;
2572	}
2573	return 0;
2574	}
2575
2576	#else
2577
2578	static inline
2579	int mark_lock_irq(struct task_struct curr, struct held_lock this,
2580	enum lock_usage_bit new_bit)
2581	{
2582	WARN_ON(1);
2583	return 1;
2584	}
2585
2586	static inline int mark_irqflags(struct task_struct *curr,
2587	struct held_lock *hlock)
2588	{
2589	return 1;
2590	}
2591
2592	static inline int separate_irq_context(struct task_struct *curr,
2593	struct held_lock *hlock)
2594	{
2595	return 0;
2596	}
2597
2598	void lockdep_trace_alloc(gfp_t gfp_mask)
2599	{
2600	}
2601
2602	#endif
2603
2604	/*
2605	* Mark a lock with a usage bit, and validate the state transition:
2606	*/
2607	static int mark_lock(struct task_struct curr, struct held_lock this,
2608	enum lock_usage_bit new_bit)
2609	{
2610	unsigned int new_mask = 1 << new_bit, ret = 1;
2611
2612	/*
2613	* If already set then do not dirty the cacheline,
2614	* nor do any checks:
2615	*/
2616	if (likely(hlock_class(this)->usage_mask & new_mask))
2617	return 1;
2618
2619	if (!graph_lock())
2620	return 0;
2621	/*
2622	* Make sure we didnt race:
2623	*/
2624	if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
2625	graph_unlock();
2626	return 1;
2627	}
2628
2629	hlock_class(this)->usage_mask \|= new_mask;
2630
2631	if (!save_trace(hlock_class(this)->usage_traces + new_bit))
2632	return 0;
2633
2634	switch (new_bit) {
2635	#define LOCKDEP_STATE(__STATE) \
2636	case LOCK_USED_IN_##__STATE: \
2637	case LOCK_USED_IN_##__STATE##_READ: \
2638	case LOCK_ENABLED_##__STATE: \
2639	case LOCK_ENABLED_##__STATE##_READ:
2640	#include "lockdep_states.h"
2641	#undef LOCKDEP_STATE
2642	ret = mark_lock_irq(curr, this, new_bit);
2643	if (!ret)
2644	return 0;
2645	break;
2646	case LOCK_USED:
2647	debug_atomic_dec(&nr_unused_locks);
2648	break;
2649	default:
2650	if (!debug_locks_off_graph_unlock())
2651	return 0;
2652	WARN_ON(1);
2653	return 0;
2654	}
2655
2656	graph_unlock();
2657
2658	/*
2659	* We must printk outside of the graph_lock:
2660	*/
2661	if (ret == 2) {
2662	printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
2663	print_lock(this);
2664	print_irqtrace_events(curr);
2665	dump_stack();
2666	}
2667
2668	return ret;
2669	}
2670
2671	/*
2672	* Initialize a lock instance's lock-class mapping info:
2673	*/
2674	void lockdep_init_map(struct lockdep_map lock, const char name,
2675	struct lock_class_key *key, int subclass)
2676	{
2677	lock->class_cache = NULL;
2678	#ifdef CONFIG_LOCK_STAT
2679	lock->cpu = raw_smp_processor_id();
2680	#endif
2681
2682	if (DEBUG_LOCKS_WARN_ON(!name)) {
2683	lock->name = "NULL";
2684	return;
2685	}
2686
2687	lock->name = name;
2688
2689	if (DEBUG_LOCKS_WARN_ON(!key))
2690	return;
2691	/*
2692	* Sanity check, the lock-class key must be persistent:
2693	*/
2694	if (!static_obj(key)) {
2695	printk("BUG: key %p not in .data!\n", key);
2696	DEBUG_LOCKS_WARN_ON(1);
2697	return;
2698	}
2699	lock->key = key;
2700
2701	if (unlikely(!debug_locks))
2702	return;
2703
2704	if (subclass)
2705	register_lock_class(lock, subclass, 1);
2706	}
2707	EXPORT_SYMBOL_GPL(lockdep_init_map);
2708
2709	/*
2710	* This gets called for every mutex_lock()/spin_lock() operation.
2711	* We maintain the dependency maps and validate the locking attempt:
2712	*/
2713	static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
2714	int trylock, int read, int check, int hardirqs_off,
2715	struct lockdep_map *nest_lock, unsigned long ip,
2716	int references)
2717	{
2718	struct task_struct *curr = current;
2719	struct lock_class *class = NULL;
2720	struct held_lock *hlock;
2721	unsigned int depth, id;
2722	int chain_head = 0;
2723	int class_idx;
2724	u64 chain_key;
2725
2726	if (!prove_locking)
2727	check = 1;
2728
2729	if (unlikely(!debug_locks))
2730	return 0;
2731
2732	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2733	return 0;
2734
2735	if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
2736	debug_locks_off();
2737	printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
2738	printk("turning off the locking correctness validator.\n");
2739	dump_stack();
2740	return 0;
2741	}
2742
2743	if (!subclass)
2744	class = lock->class_cache;
2745	/*
2746	* Not cached yet or subclass?
2747	*/
2748	if (unlikely(!class)) {
2749	class = register_lock_class(lock, subclass, 0);
2750	if (!class)
2751	return 0;
2752	}
2753	debug_atomic_inc((atomic_t *)&class->ops);
2754	if (very_verbose(class)) {
2755	printk("\nacquire class [%p] %s", class->key, class->name);
2756	if (class->name_version > 1)
2757	printk("#%d", class->name_version);
2758	printk("\n");
2759	dump_stack();
2760	}
2761
2762	/*
2763	* Add the lock to the list of currently held locks.
2764	* (we dont increase the depth just yet, up until the
2765	* dependency checks are done)
2766	*/
2767	depth = curr->lockdep_depth;
2768	if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
2769	return 0;
2770
2771	class_idx = class - lock_classes + 1;
2772
2773	if (depth) {
2774	hlock = curr->held_locks + depth - 1;
2775	if (hlock->class_idx == class_idx && nest_lock) {
2776	if (hlock->references)
2777	hlock->references++;
2778	else
2779	hlock->references = 2;
2780
2781	return 1;
2782	}
2783	}
2784
2785	hlock = curr->held_locks + depth;
2786	if (DEBUG_LOCKS_WARN_ON(!class))
2787	return 0;
2788	hlock->class_idx = class_idx;
2789	hlock->acquire_ip = ip;
2790	hlock->instance = lock;
2791	hlock->nest_lock = nest_lock;
2792	hlock->trylock = trylock;
2793	hlock->read = read;
2794	hlock->check = check;
2795	hlock->hardirqs_off = !!hardirqs_off;
2796	hlock->references = references;
2797	#ifdef CONFIG_LOCK_STAT
2798	hlock->waittime_stamp = 0;
2799	hlock->holdtime_stamp = lockstat_clock();
2800	#endif
2801
2802	if (check == 2 && !mark_irqflags(curr, hlock))
2803	return 0;
2804
2805	/* mark it as used: */
2806	if (!mark_lock(curr, hlock, LOCK_USED))
2807	return 0;
2808
2809	/*
2810	* Calculate the chain hash: it's the combined hash of all the
2811	* lock keys along the dependency chain. We save the hash value
2812	* at every step so that we can get the current hash easily
2813	* after unlock. The chain hash is then used to cache dependency
2814	* results.
2815	*
2816	* The 'key ID' is what is the most compact key value to drive
2817	* the hash, not class->key.
2818	*/
2819	id = class - lock_classes;
2820	if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
2821	return 0;
2822
2823	chain_key = curr->curr_chain_key;
2824	if (!depth) {
2825	if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
2826	return 0;
2827	chain_head = 1;
2828	}
2829
2830	hlock->prev_chain_key = chain_key;
2831	if (separate_irq_context(curr, hlock)) {
2832	chain_key = 0;
2833	chain_head = 1;
2834	}
2835	chain_key = iterate_chain_key(chain_key, id);
2836
2837	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
2838	return 0;
2839
2840	curr->curr_chain_key = chain_key;
2841	curr->lockdep_depth++;
2842	check_chain_key(curr);
2843	#ifdef CONFIG_DEBUG_LOCKDEP
2844	if (unlikely(!debug_locks))
2845	return 0;
2846	#endif
2847	if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
2848	debug_locks_off();
2849	printk("BUG: MAX_LOCK_DEPTH too low!\n");
2850	printk("turning off the locking correctness validator.\n");
2851	dump_stack();
2852	return 0;
2853	}
2854
2855	if (unlikely(curr->lockdep_depth > max_lockdep_depth))
2856	max_lockdep_depth = curr->lockdep_depth;
2857
2858	return 1;
2859	}
2860
2861	static int
2862	print_unlock_inbalance_bug(struct task_struct curr, struct lockdep_map lock,
2863	unsigned long ip)
2864	{
2865	if (!debug_locks_off())
2866	return 0;
2867	if (debug_locks_silent)
2868	return 0;
2869
2870	printk("\n=====================================\n");
2871	printk( "[ BUG: bad unlock balance detected! ]\n");
2872	printk( "-------------------------------------\n");
2873	printk("%s/%d is trying to release lock (",
2874	curr->comm, task_pid_nr(curr));
2875	print_lockdep_cache(lock);
2876	printk(") at:\n");
2877	print_ip_sym(ip);
2878	printk("but there are no more locks to release!\n");
2879	printk("\nother info that might help us debug this:\n");
2880	lockdep_print_held_locks(curr);
2881
2882	printk("\nstack backtrace:\n");
2883	dump_stack();
2884
2885	return 0;
2886	}
2887
2888	/*
2889	* Common debugging checks for both nested and non-nested unlock:
2890	*/
2891	static int check_unlock(struct task_struct curr, struct lockdep_map lock,
2892	unsigned long ip)
2893	{
2894	if (unlikely(!debug_locks))
2895	return 0;
2896	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
2897	return 0;
2898
2899	if (curr->lockdep_depth <= 0)
2900	return print_unlock_inbalance_bug(curr, lock, ip);
2901
2902	return 1;
2903	}
2904
2905	static int match_held_lock(struct held_lock hlock, struct lockdep_map lock)
2906	{
2907	if (hlock->instance == lock)
2908	return 1;
2909
2910	if (hlock->references) {
2911	struct lock_class *class = lock->class_cache;
2912
2913	if (!class)
2914	class = look_up_lock_class(lock, 0);
2915
2916	if (DEBUG_LOCKS_WARN_ON(!class))
2917	return 0;
2918
2919	if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
2920	return 0;
2921
2922	if (hlock->class_idx == class - lock_classes + 1)
2923	return 1;
2924	}
2925
2926	return 0;
2927	}
2928
2929	static int
2930	__lock_set_class(struct lockdep_map lock, const char name,
2931	struct lock_class_key *key, unsigned int subclass,
2932	unsigned long ip)
2933	{
2934	struct task_struct *curr = current;
2935	struct held_lock hlock, prev_hlock;
2936	struct lock_class *class;
2937	unsigned int depth;
2938	int i;
2939
2940	depth = curr->lockdep_depth;
2941	if (DEBUG_LOCKS_WARN_ON(!depth))
2942	return 0;
2943
2944	prev_hlock = NULL;
2945	for (i = depth-1; i >= 0; i--) {
2946	hlock = curr->held_locks + i;
2947	/*
2948	* We must not cross into another context:
2949	*/
2950	if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
2951	break;
2952	if (match_held_lock(hlock, lock))
2953	goto found_it;
2954	prev_hlock = hlock;
2955	}
2956	return print_unlock_inbalance_bug(curr, lock, ip);
2957
2958	found_it:
2959	lockdep_init_map(lock, name, key, 0);
2960	class = register_lock_class(lock, subclass, 0);
2961	hlock->class_idx = class - lock_classes + 1;
2962
2963	curr->lockdep_depth = i;
2964	curr->curr_chain_key = hlock->prev_chain_key;
2965
2966	for (; i < depth; i++) {
2967	hlock = curr->held_locks + i;
2968	if (!__lock_acquire(hlock->instance,
2969	hlock_class(hlock)->subclass, hlock->trylock,
2970	hlock->read, hlock->check, hlock->hardirqs_off,
2971	hlock->nest_lock, hlock->acquire_ip,
2972	hlock->references))
2973	return 0;
2974	}
2975
2976	if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
2977	return 0;
2978	return 1;
2979	}
2980
2981	/*
2982	* Remove the lock to the list of currently held locks in a
2983	* potentially non-nested (out of order) manner. This is a
2984	* relatively rare operation, as all the unlock APIs default
2985	* to nested mode (which uses lock_release()):
2986	*/
2987	static int
2988	lock_release_non_nested(struct task_struct *curr,
2989	struct lockdep_map *lock, unsigned long ip)
2990	{
2991	struct held_lock hlock, prev_hlock;
2992	unsigned int depth;
2993	int i;
2994
2995	/*
2996	* Check whether the lock exists in the current stack
2997	* of held locks:
2998	*/
2999	depth = curr->lockdep_depth;
3000	if (DEBUG_LOCKS_WARN_ON(!depth))
3001	return 0;
3002
3003	prev_hlock = NULL;
3004	for (i = depth-1; i >= 0; i--) {
3005	hlock = curr->held_locks + i;
3006	/*
3007	* We must not cross into another context:
3008	*/
3009	if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3010	break;
3011	if (match_held_lock(hlock, lock))
3012	goto found_it;
3013	prev_hlock = hlock;
3014	}
3015	return print_unlock_inbalance_bug(curr, lock, ip);
3016
3017	found_it:
3018	if (hlock->instance == lock)
3019	lock_release_holdtime(hlock);
3020
3021	if (hlock->references) {
3022	hlock->references--;
3023	if (hlock->references) {
3024	/*
3025	* We had, and after removing one, still have
3026	* references, the current lock stack is still
3027	* valid. We're done!
3028	*/
3029	return 1;
3030	}
3031	}
3032
3033	/*
3034	* We have the right lock to unlock, 'hlock' points to it.
3035	* Now we remove it from the stack, and add back the other
3036	* entries (if any), recalculating the hash along the way:
3037	*/
3038
3039	curr->lockdep_depth = i;
3040	curr->curr_chain_key = hlock->prev_chain_key;
3041
3042	for (i++; i < depth; i++) {
3043	hlock = curr->held_locks + i;
3044	if (!__lock_acquire(hlock->instance,
3045	hlock_class(hlock)->subclass, hlock->trylock,
3046	hlock->read, hlock->check, hlock->hardirqs_off,
3047	hlock->nest_lock, hlock->acquire_ip,
3048	hlock->references))
3049	return 0;
3050	}
3051
3052	if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
3053	return 0;
3054	return 1;
3055	}
3056
3057	/*
3058	* Remove the lock to the list of currently held locks - this gets
3059	* called on mutex_unlock()/spin_unlock*() (or on a failed
3060	* mutex_lock_interruptible()). This is done for unlocks that nest
3061	* perfectly. (i.e. the current top of the lock-stack is unlocked)
3062	*/
3063	static int lock_release_nested(struct task_struct *curr,
3064	struct lockdep_map *lock, unsigned long ip)
3065	{
3066	struct held_lock *hlock;
3067	unsigned int depth;
3068
3069	/*
3070	* Pop off the top of the lock stack:
3071	*/
3072	depth = curr->lockdep_depth - 1;
3073	hlock = curr->held_locks + depth;
3074
3075	/*
3076	* Is the unlock non-nested:
3077	*/
3078	if (hlock->instance != lock \|\| hlock->references)
3079	return lock_release_non_nested(curr, lock, ip);
3080	curr->lockdep_depth--;
3081
3082	if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
3083	return 0;
3084
3085	curr->curr_chain_key = hlock->prev_chain_key;
3086
3087	lock_release_holdtime(hlock);
3088
3089	#ifdef CONFIG_DEBUG_LOCKDEP
3090	hlock->prev_chain_key = 0;
3091	hlock->class_idx = 0;
3092	hlock->acquire_ip = 0;
3093	hlock->irq_context = 0;
3094	#endif
3095	return 1;
3096	}
3097
3098	/*
3099	* Remove the lock to the list of currently held locks - this gets
3100	* called on mutex_unlock()/spin_unlock*() (or on a failed
3101	* mutex_lock_interruptible()). This is done for unlocks that nest
3102	* perfectly. (i.e. the current top of the lock-stack is unlocked)
3103	*/
3104	static void
3105	__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
3106	{
3107	struct task_struct *curr = current;
3108
3109	if (!check_unlock(curr, lock, ip))
3110	return;
3111
3112	if (nested) {
3113	if (!lock_release_nested(curr, lock, ip))
3114	return;
3115	} else {
3116	if (!lock_release_non_nested(curr, lock, ip))
3117	return;
3118	}
3119
3120	check_chain_key(curr);
3121	}
3122
3123	static int __lock_is_held(struct lockdep_map *lock)
3124	{
3125	struct task_struct *curr = current;
3126	int i;
3127
3128	for (i = 0; i < curr->lockdep_depth; i++) {
3129	struct held_lock *hlock = curr->held_locks + i;
3130
3131	if (match_held_lock(hlock, lock))
3132	return 1;
3133	}
3134
3135	return 0;
3136	}
3137
3138	/*
3139	* Check whether we follow the irq-flags state precisely:
3140	*/
3141	static void check_flags(unsigned long flags)
3142	{
3143	#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
3144	defined(CONFIG_TRACE_IRQFLAGS)
3145	if (!debug_locks)
3146	return;
3147
3148	if (irqs_disabled_flags(flags)) {
3149	if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
3150	printk("possible reason: unannotated irqs-off.\n");
3151	}
3152	} else {
3153	if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
3154	printk("possible reason: unannotated irqs-on.\n");
3155	}
3156	}
3157
3158	/*
3159	* We dont accurately track softirq state in e.g.
3160	* hardirq contexts (such as on 4KSTACKS), so only
3161	* check if not in hardirq contexts:
3162	*/
3163	if (!hardirq_count()) {
3164	if (softirq_count())
3165	DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
3166	else
3167	DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
3168	}
3169
3170	if (!debug_locks)
3171	print_irqtrace_events(current);
3172	#endif
3173	}
3174
3175	void lock_set_class(struct lockdep_map lock, const char name,
3176	struct lock_class_key *key, unsigned int subclass,
3177	unsigned long ip)
3178	{
3179	unsigned long flags;
3180
3181	if (unlikely(current->lockdep_recursion))
3182	return;
3183
3184	raw_local_irq_save(flags);
3185	current->lockdep_recursion = 1;
3186	check_flags(flags);
3187	if (__lock_set_class(lock, name, key, subclass, ip))
3188	check_chain_key(current);
3189	current->lockdep_recursion = 0;
3190	raw_local_irq_restore(flags);
3191	}
3192	EXPORT_SYMBOL_GPL(lock_set_class);
3193
3194	/*
3195	* We are not always called with irqs disabled - do that here,
3196	* and also avoid lockdep recursion:
3197	*/
3198	void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
3199	int trylock, int read, int check,
3200	struct lockdep_map *nest_lock, unsigned long ip)
3201	{
3202	unsigned long flags;
3203
3204	if (unlikely(current->lockdep_recursion))
3205	return;
3206
3207	raw_local_irq_save(flags);
3208	check_flags(flags);
3209
3210	current->lockdep_recursion = 1;
3211	trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
3212	__lock_acquire(lock, subclass, trylock, read, check,
3213	irqs_disabled_flags(flags), nest_lock, ip, 0);
3214	current->lockdep_recursion = 0;
3215	raw_local_irq_restore(flags);
3216	}
3217	EXPORT_SYMBOL_GPL(lock_acquire);
3218
3219	void lock_release(struct lockdep_map *lock, int nested,
3220	unsigned long ip)
3221	{
3222	unsigned long flags;
3223
3224	if (unlikely(current->lockdep_recursion))
3225	return;
3226
3227	raw_local_irq_save(flags);
3228	check_flags(flags);
3229	current->lockdep_recursion = 1;
3230	trace_lock_release(lock, nested, ip);
3231	__lock_release(lock, nested, ip);
3232	current->lockdep_recursion = 0;
3233	raw_local_irq_restore(flags);
3234	}
3235	EXPORT_SYMBOL_GPL(lock_release);
3236
3237	int lock_is_held(struct lockdep_map *lock)
3238	{
3239	unsigned long flags;
3240	int ret = 0;
3241
3242	if (unlikely(current->lockdep_recursion))
3243	return ret;
3244
3245	raw_local_irq_save(flags);
3246	check_flags(flags);
3247
3248	current->lockdep_recursion = 1;
3249	ret = __lock_is_held(lock);
3250	current->lockdep_recursion = 0;
3251	raw_local_irq_restore(flags);
3252
3253	return ret;
3254	}
3255	EXPORT_SYMBOL_GPL(lock_is_held);
3256
3257	void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
3258	{
3259	current->lockdep_reclaim_gfp = gfp_mask;
3260	}
3261
3262	void lockdep_clear_current_reclaim_state(void)
3263	{
3264	current->lockdep_reclaim_gfp = 0;
3265	}
3266
3267	#ifdef CONFIG_LOCK_STAT
3268	static int
3269	print_lock_contention_bug(struct task_struct curr, struct lockdep_map lock,
3270	unsigned long ip)
3271	{
3272	if (!debug_locks_off())
3273	return 0;
3274	if (debug_locks_silent)
3275	return 0;
3276
3277	printk("\n=================================\n");
3278	printk( "[ BUG: bad contention detected! ]\n");
3279	printk( "---------------------------------\n");
3280	printk("%s/%d is trying to contend lock (",
3281	curr->comm, task_pid_nr(curr));
3282	print_lockdep_cache(lock);
3283	printk(") at:\n");
3284	print_ip_sym(ip);
3285	printk("but there are no locks held!\n");
3286	printk("\nother info that might help us debug this:\n");
3287	lockdep_print_held_locks(curr);
3288
3289	printk("\nstack backtrace:\n");
3290	dump_stack();
3291
3292	return 0;
3293	}
3294
3295	static void
3296	__lock_contended(struct lockdep_map *lock, unsigned long ip)
3297	{
3298	struct task_struct *curr = current;
3299	struct held_lock hlock, prev_hlock;
3300	struct lock_class_stats *stats;
3301	unsigned int depth;
3302	int i, contention_point, contending_point;
3303
3304	depth = curr->lockdep_depth;
3305	if (DEBUG_LOCKS_WARN_ON(!depth))
3306	return;
3307
3308	prev_hlock = NULL;
3309	for (i = depth-1; i >= 0; i--) {
3310	hlock = curr->held_locks + i;
3311	/*
3312	* We must not cross into another context:
3313	*/
3314	if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3315	break;
3316	if (match_held_lock(hlock, lock))
3317	goto found_it;
3318	prev_hlock = hlock;
3319	}
3320	print_lock_contention_bug(curr, lock, ip);
3321	return;
3322
3323	found_it:
3324	if (hlock->instance != lock)
3325	return;
3326
3327	hlock->waittime_stamp = lockstat_clock();
3328
3329	contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
3330	contending_point = lock_point(hlock_class(hlock)->contending_point,
3331	lock->ip);
3332
3333	stats = get_lock_stats(hlock_class(hlock));
3334	if (contention_point < LOCKSTAT_POINTS)
3335	stats->contention_point[contention_point]++;
3336	if (contending_point < LOCKSTAT_POINTS)
3337	stats->contending_point[contending_point]++;
3338	if (lock->cpu != smp_processor_id())
3339	stats->bounces[bounce_contended + !!hlock->read]++;
3340	put_lock_stats(stats);
3341	}
3342
3343	static void
3344	__lock_acquired(struct lockdep_map *lock, unsigned long ip)
3345	{
3346	struct task_struct *curr = current;
3347	struct held_lock hlock, prev_hlock;
3348	struct lock_class_stats *stats;
3349	unsigned int depth;
3350	u64 now, waittime = 0;
3351	int i, cpu;
3352
3353	depth = curr->lockdep_depth;
3354	if (DEBUG_LOCKS_WARN_ON(!depth))
3355	return;
3356
3357	prev_hlock = NULL;
3358	for (i = depth-1; i >= 0; i--) {
3359	hlock = curr->held_locks + i;
3360	/*
3361	* We must not cross into another context:
3362	*/
3363	if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
3364	break;
3365	if (match_held_lock(hlock, lock))
3366	goto found_it;
3367	prev_hlock = hlock;
3368	}
3369	print_lock_contention_bug(curr, lock, _RET_IP_);
3370	return;
3371
3372	found_it:
3373	if (hlock->instance != lock)
3374	return;
3375
3376	cpu = smp_processor_id();
3377	if (hlock->waittime_stamp) {
3378	now = lockstat_clock();
3379	waittime = now - hlock->waittime_stamp;
3380	hlock->holdtime_stamp = now;
3381	}
3382
3383	trace_lock_acquired(lock, ip, waittime);
3384
3385	stats = get_lock_stats(hlock_class(hlock));
3386	if (waittime) {
3387	if (hlock->read)
3388	lock_time_inc(&stats->read_waittime, waittime);
3389	else
3390	lock_time_inc(&stats->write_waittime, waittime);
3391	}
3392	if (lock->cpu != cpu)
3393	stats->bounces[bounce_acquired + !!hlock->read]++;
3394	put_lock_stats(stats);
3395
3396	lock->cpu = cpu;
3397	lock->ip = ip;
3398	}
3399
3400	void lock_contended(struct lockdep_map *lock, unsigned long ip)
3401	{
3402	unsigned long flags;
3403
3404	if (unlikely(!lock_stat))
3405	return;
3406
3407	if (unlikely(current->lockdep_recursion))
3408	return;
3409
3410	raw_local_irq_save(flags);
3411	check_flags(flags);
3412	current->lockdep_recursion = 1;
3413	trace_lock_contended(lock, ip);
3414	__lock_contended(lock, ip);
3415	current->lockdep_recursion = 0;
3416	raw_local_irq_restore(flags);
3417	}
3418	EXPORT_SYMBOL_GPL(lock_contended);
3419
3420	void lock_acquired(struct lockdep_map *lock, unsigned long ip)
3421	{
3422	unsigned long flags;
3423
3424	if (unlikely(!lock_stat))
3425	return;
3426
3427	if (unlikely(current->lockdep_recursion))
3428	return;
3429
3430	raw_local_irq_save(flags);
3431	check_flags(flags);
3432	current->lockdep_recursion = 1;
3433	__lock_acquired(lock, ip);
3434	current->lockdep_recursion = 0;
3435	raw_local_irq_restore(flags);
3436	}
3437	EXPORT_SYMBOL_GPL(lock_acquired);
3438	#endif
3439
3440	/*
3441	* Used by the testsuite, sanitize the validator state
3442	* after a simulated failure:
3443	*/
3444
3445	void lockdep_reset(void)
3446	{
3447	unsigned long flags;
3448	int i;
3449
3450	raw_local_irq_save(flags);
3451	current->curr_chain_key = 0;
3452	current->lockdep_depth = 0;
3453	current->lockdep_recursion = 0;
3454	memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
3455	nr_hardirq_chains = 0;
3456	nr_softirq_chains = 0;
3457	nr_process_chains = 0;
3458	debug_locks = 1;
3459	for (i = 0; i < CHAINHASH_SIZE; i++)
3460	INIT_LIST_HEAD(chainhash_table + i);
3461	raw_local_irq_restore(flags);
3462	}
3463
3464	static void zap_class(struct lock_class *class)
3465	{
3466	int i;
3467
3468	/*
3469	* Remove all dependencies this lock is
3470	* involved in:
3471	*/
3472	for (i = 0; i < nr_list_entries; i++) {
3473	if (list_entries[i].class == class)
3474	list_del_rcu(&list_entries[i].entry);
3475	}
3476	/*
3477	* Unhash the class and remove it from the all_lock_classes list:
3478	*/
3479	list_del_rcu(&class->hash_entry);
3480	list_del_rcu(&class->lock_entry);
3481
3482	class->key = NULL;
3483	}
3484
3485	static inline int within(const void addr, void start, unsigned long size)
3486	{
3487	return addr >= start && addr < start + size;
3488	}
3489
3490	void lockdep_free_key_range(void *start, unsigned long size)
3491	{
3492	struct lock_class class, next;
3493	struct list_head *head;
3494	unsigned long flags;
3495	int i;
3496	int locked;
3497
3498	raw_local_irq_save(flags);
3499	locked = graph_lock();
3500
3501	/*
3502	* Unhash all classes that were created by this module:
3503	*/
3504	for (i = 0; i < CLASSHASH_SIZE; i++) {
3505	head = classhash_table + i;
3506	if (list_empty(head))
3507	continue;
3508	list_for_each_entry_safe(class, next, head, hash_entry) {
3509	if (within(class->key, start, size))
3510	zap_class(class);
3511	else if (within(class->name, start, size))
3512	zap_class(class);
3513	}
3514	}
3515
3516	if (locked)
3517	graph_unlock();
3518	raw_local_irq_restore(flags);
3519	}
3520
3521	void lockdep_reset_lock(struct lockdep_map *lock)
3522	{
3523	struct lock_class class, next;
3524	struct list_head *head;
3525	unsigned long flags;
3526	int i, j;
3527	int locked;
3528
3529	raw_local_irq_save(flags);
3530
3531	/*
3532	* Remove all classes this lock might have:
3533	*/
3534	for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
3535	/*
3536	* If the class exists we look it up and zap it:
3537	*/
3538	class = look_up_lock_class(lock, j);
3539	if (class)
3540	zap_class(class);
3541	}
3542	/*
3543	* Debug check: in the end all mapped classes should
3544	* be gone.
3545	*/
3546	locked = graph_lock();
3547	for (i = 0; i < CLASSHASH_SIZE; i++) {
3548	head = classhash_table + i;
3549	if (list_empty(head))
3550	continue;
3551	list_for_each_entry_safe(class, next, head, hash_entry) {
3552	if (unlikely(class == lock->class_cache)) {
3553	if (debug_locks_off_graph_unlock())
3554	WARN_ON(1);
3555	goto out_restore;
3556	}
3557	}
3558	}
3559	if (locked)
3560	graph_unlock();
3561
3562	out_restore:
3563	raw_local_irq_restore(flags);
3564	}
3565
3566	void lockdep_init(void)
3567	{
3568	int i;
3569
3570	/*
3571	* Some architectures have their own start_kernel()
3572	* code which calls lockdep_init(), while we also
3573	* call lockdep_init() from the start_kernel() itself,
3574	* and we want to initialize the hashes only once:
3575	*/
3576	if (lockdep_initialized)
3577	return;
3578
3579	for (i = 0; i < CLASSHASH_SIZE; i++)
3580	INIT_LIST_HEAD(classhash_table + i);
3581
3582	for (i = 0; i < CHAINHASH_SIZE; i++)
3583	INIT_LIST_HEAD(chainhash_table + i);
3584
3585	lockdep_initialized = 1;
3586	}
3587
3588	void __init lockdep_info(void)
3589	{
3590	printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
3591
3592	printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
3593	printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
3594	printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
3595	printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
3596	printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
3597	printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
3598	printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
3599
3600	printk(" memory used by lock dependency info: %lu kB\n",
3601	(sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
3602	sizeof(struct list_head) * CLASSHASH_SIZE +
3603	sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
3604	sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
3605	sizeof(struct list_head) * CHAINHASH_SIZE
3606	#ifdef CONFIG_PROVE_LOCKING
3607	+ sizeof(struct circular_queue)
3608	#endif
3609	) / 1024
3610	);
3611
3612	printk(" per task-struct memory footprint: %lu bytes\n",
3613	sizeof(struct held_lock) * MAX_LOCK_DEPTH);
3614
3615	#ifdef CONFIG_DEBUG_LOCKDEP
3616	if (lockdep_init_error) {
3617	printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
3618	printk("Call stack leading to lockdep invocation was:\n");
3619	print_stack_trace(&lockdep_init_trace, 0);
3620	}
3621	#endif
3622	}
3623
3624	static void
3625	print_freed_lock_bug(struct task_struct curr, const void mem_from,
3626	const void mem_to, struct held_lock hlock)
3627	{
3628	if (!debug_locks_off())
3629	return;
3630	if (debug_locks_silent)
3631	return;
3632
3633	printk("\n=========================\n");
3634	printk( "[ BUG: held lock freed! ]\n");
3635	printk( "-------------------------\n");
3636	printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3637	curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3638	print_lock(hlock);
3639	lockdep_print_held_locks(curr);
3640
3641	printk("\nstack backtrace:\n");
3642	dump_stack();
3643	}
3644
3645	static inline int not_in_range(const void* mem_from, unsigned long mem_len,
3646	const void* lock_from, unsigned long lock_len)
3647	{
3648	return lock_from + lock_len <= mem_from \|\|
3649	mem_from + mem_len <= lock_from;
3650	}
3651
3652	/*
3653	* Called when kernel memory is freed (or unmapped), or if a lock
3654	* is destroyed or reinitialized - this code checks whether there is
3655	* any held lock in the memory range of <from> to <to>:
3656	*/
3657	void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
3658	{
3659	struct task_struct *curr = current;
3660	struct held_lock *hlock;
3661	unsigned long flags;
3662	int i;
3663
3664	if (unlikely(!debug_locks))
3665	return;
3666
3667	local_irq_save(flags);
3668	for (i = 0; i < curr->lockdep_depth; i++) {
3669	hlock = curr->held_locks + i;
3670
3671	if (not_in_range(mem_from, mem_len, hlock->instance,
3672	sizeof(*hlock->instance)))
3673	continue;
3674
3675	print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
3676	break;
3677	}
3678	local_irq_restore(flags);
3679	}
3680	EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
3681
3682	static void print_held_locks_bug(struct task_struct *curr)
3683	{
3684	if (!debug_locks_off())
3685	return;
3686	if (debug_locks_silent)
3687	return;
3688
3689	printk("\n=====================================\n");
3690	printk( "[ BUG: lock held at task exit time! ]\n");
3691	printk( "-------------------------------------\n");
3692	printk("%s/%d is exiting with locks still held!\n",
3693	curr->comm, task_pid_nr(curr));
3694	lockdep_print_held_locks(curr);
3695
3696	printk("\nstack backtrace:\n");
3697	dump_stack();
3698	}
3699
3700	void debug_check_no_locks_held(struct task_struct *task)
3701	{
3702	if (unlikely(task->lockdep_depth > 0))
3703	print_held_locks_bug(task);
3704	}
3705
3706	void debug_show_all_locks(void)
3707	{
3708	struct task_struct g, p;
3709	int count = 10;
3710	int unlock = 1;
3711
3712	if (unlikely(!debug_locks)) {
3713	printk("INFO: lockdep is turned off.\n");
3714	return;
3715	}
3716	printk("\nShowing all locks held in the system:\n");
3717
3718	/*
3719	* Here we try to get the tasklist_lock as hard as possible,
3720	* if not successful after 2 seconds we ignore it (but keep
3721	* trying). This is to enable a debug printout even if a
3722	* tasklist_lock-holding task deadlocks or crashes.
3723	*/
3724	retry:
3725	if (!read_trylock(&tasklist_lock)) {
3726	if (count == 10)
3727	printk("hm, tasklist_lock locked, retrying... ");
3728	if (count) {
3729	count--;
3730	printk(" #%d", 10-count);
3731	mdelay(200);
3732	goto retry;
3733	}
3734	printk(" ignoring it.\n");
3735	unlock = 0;
3736	} else {
3737	if (count != 10)
3738	printk(KERN_CONT " locked it.\n");
3739	}
3740
3741	do_each_thread(g, p) {
3742	/*
3743	* It's not reliable to print a task's held locks
3744	* if it's not sleeping (or if it's not the current
3745	* task):
3746	*/
3747	if (p->state == TASK_RUNNING && p != current)
3748	continue;
3749	if (p->lockdep_depth)
3750	lockdep_print_held_locks(p);
3751	if (!unlock)
3752	if (read_trylock(&tasklist_lock))
3753	unlock = 1;
3754	} while_each_thread(g, p);
3755
3756	printk("\n");
3757	printk("=============================================\n\n");
3758
3759	if (unlock)
3760	read_unlock(&tasklist_lock);
3761	}
3762	EXPORT_SYMBOL_GPL(debug_show_all_locks);
3763
3764	/*
3765	* Careful: only use this function if you are sure that
3766	* the task cannot run in parallel!
3767	*/
3768	void __debug_show_held_locks(struct task_struct *task)
3769	{
3770	if (unlikely(!debug_locks)) {
3771	printk("INFO: lockdep is turned off.\n");
3772	return;
3773	}
3774	lockdep_print_held_locks(task);
3775	}
3776	EXPORT_SYMBOL_GPL(__debug_show_held_locks);
3777
3778	void debug_show_held_locks(struct task_struct *task)
3779	{
3780	__debug_show_held_locks(task);
3781	}
3782	EXPORT_SYMBOL_GPL(debug_show_held_locks);
3783
3784	void lockdep_sys_exit(void)
3785	{
3786	struct task_struct *curr = current;
3787
3788	if (unlikely(curr->lockdep_depth)) {
3789	if (!debug_locks_off())
3790	return;
3791	printk("\n================================================\n");
3792	printk( "[ BUG: lock held when returning to user space! ]\n");
3793	printk( "------------------------------------------------\n");
3794	printk("%s/%d is leaving the kernel with locks still held!\n",
3795	curr->comm, curr->pid);
3796	lockdep_print_held_locks(curr);
3797	}
3798	}
3799
3800	void lockdep_rcu_dereference(const char *file, const int line)
3801	{
3802	struct task_struct *curr = current;
3803
3804	if (!debug_locks_off())
3805	return;
3806	printk("\n===================================================\n");
3807	printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
3808	printk( "---------------------------------------------------\n");
3809	printk("%s:%d invoked rcu_dereference_check() without protection!\n",
3810	file, line);
3811	printk("\nother info that might help us debug this:\n\n");
3812	printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
3813	lockdep_print_held_locks(curr);
3814	printk("\nstack backtrace:\n");
3815	dump_stack();
3816	}
3817	EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);
3818

Download this file

Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master

Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9

Kernel

Kernel Git Source Tree

Root/kernel/lockdep.c

interactive