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

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