lockdep.c 90.7 KB
Newer Older
I
Ingo Molnar 已提交
1 2 3 4 5 6 7
/*
 * kernel/lockdep.c
 *
 * Runtime locking correctness validator
 *
 * Started by Ingo Molnar:
 *
P
Peter Zijlstra 已提交
8 9
 *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
I
Ingo Molnar 已提交
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
 *
 * this code maps all the lock dependencies as they occur in a live kernel
 * and will warn about the following classes of locking bugs:
 *
 * - lock inversion scenarios
 * - circular lock dependencies
 * - hardirq/softirq safe/unsafe locking bugs
 *
 * Bugs are reported even if the current locking scenario does not cause
 * any deadlock at this point.
 *
 * I.e. if anytime in the past two locks were taken in a different order,
 * even if it happened for another task, even if those were different
 * locks (but of the same class as this lock), this code will detect it.
 *
 * Thanks to Arjan van de Ven for coming up with the initial idea of
 * mapping lock dependencies runtime.
 */
28
#define DISABLE_BRANCH_PROFILING
I
Ingo Molnar 已提交
29 30 31 32 33 34 35 36 37 38 39 40
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/kallsyms.h>
#include <linux/interrupt.h>
#include <linux/stacktrace.h>
#include <linux/debug_locks.h>
#include <linux/irqflags.h>
41
#include <linux/utsname.h>
P
Peter Zijlstra 已提交
42
#include <linux/hash.h>
43
#include <linux/ftrace.h>
P
Peter Zijlstra 已提交
44
#include <linux/stringify.h>
45
#include <linux/bitops.h>
46
#include <linux/gfp.h>
P
Peter Zijlstra 已提交
47

I
Ingo Molnar 已提交
48 49 50 51
#include <asm/sections.h>

#include "lockdep_internals.h"

52
#define CREATE_TRACE_POINTS
53
#include <trace/events/lock.h>
54

P
Peter Zijlstra 已提交
55 56 57 58 59 60 61 62 63 64 65 66 67 68
#ifdef CONFIG_PROVE_LOCKING
int prove_locking = 1;
module_param(prove_locking, int, 0644);
#else
#define prove_locking 0
#endif

#ifdef CONFIG_LOCK_STAT
int lock_stat = 1;
module_param(lock_stat, int, 0644);
#else
#define lock_stat 0
#endif

I
Ingo Molnar 已提交
69
/*
70 71
 * lockdep_lock: protects the lockdep graph, the hashes and the
 *               class/list/hash allocators.
I
Ingo Molnar 已提交
72 73 74
 *
 * This is one of the rare exceptions where it's justified
 * to use a raw spinlock - we really dont want the spinlock
75
 * code to recurse back into the lockdep code...
I
Ingo Molnar 已提交
76
 */
77
static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
78 79 80

static int graph_lock(void)
{
81
	arch_spin_lock(&lockdep_lock);
82 83 84 85 86 87 88
	/*
	 * Make sure that if another CPU detected a bug while
	 * walking the graph we dont change it (while the other
	 * CPU is busy printing out stuff with the graph lock
	 * dropped already)
	 */
	if (!debug_locks) {
89
		arch_spin_unlock(&lockdep_lock);
90 91
		return 0;
	}
92 93
	/* prevent any recursions within lockdep from causing deadlocks */
	current->lockdep_recursion++;
94 95 96 97 98
	return 1;
}

static inline int graph_unlock(void)
{
99
	if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
100 101
		return DEBUG_LOCKS_WARN_ON(1);

102
	current->lockdep_recursion--;
103
	arch_spin_unlock(&lockdep_lock);
104 105 106 107 108 109 110 111 112 113 114
	return 0;
}

/*
 * Turn lock debugging off and return with 0 if it was off already,
 * and also release the graph lock:
 */
static inline int debug_locks_off_graph_unlock(void)
{
	int ret = debug_locks_off();

115
	arch_spin_unlock(&lockdep_lock);
116 117 118

	return ret;
}
I
Ingo Molnar 已提交
119 120 121 122

static int lockdep_initialized;

unsigned long nr_list_entries;
P
Peter Zijlstra 已提交
123
static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
I
Ingo Molnar 已提交
124 125 126 127 128 129 130 131 132 133

/*
 * All data structures here are protected by the global debug_lock.
 *
 * Mutex key structs only get allocated, once during bootup, and never
 * get freed - this significantly simplifies the debugging code.
 */
unsigned long nr_lock_classes;
static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];

D
Dave Jones 已提交
134 135 136 137 138 139 140 141 142
static inline struct lock_class *hlock_class(struct held_lock *hlock)
{
	if (!hlock->class_idx) {
		DEBUG_LOCKS_WARN_ON(1);
		return NULL;
	}
	return lock_classes + hlock->class_idx - 1;
}

P
Peter Zijlstra 已提交
143
#ifdef CONFIG_LOCK_STAT
144 145
static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
		      cpu_lock_stats);
P
Peter Zijlstra 已提交
146

147 148 149 150 151
static inline u64 lockstat_clock(void)
{
	return cpu_clock(smp_processor_id());
}

P
Peter Zijlstra 已提交
152
static int lock_point(unsigned long points[], unsigned long ip)
P
Peter Zijlstra 已提交
153 154 155
{
	int i;

P
Peter Zijlstra 已提交
156 157 158
	for (i = 0; i < LOCKSTAT_POINTS; i++) {
		if (points[i] == 0) {
			points[i] = ip;
P
Peter Zijlstra 已提交
159 160
			break;
		}
P
Peter Zijlstra 已提交
161
		if (points[i] == ip)
P
Peter Zijlstra 已提交
162 163 164 165 166 167
			break;
	}

	return i;
}

168
static void lock_time_inc(struct lock_time *lt, u64 time)
P
Peter Zijlstra 已提交
169 170 171 172
{
	if (time > lt->max)
		lt->max = time;

173
	if (time < lt->min || !lt->nr)
P
Peter Zijlstra 已提交
174 175 176 177 178 179
		lt->min = time;

	lt->total += time;
	lt->nr++;
}

180 181
static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
{
182 183 184 185 186 187 188 189 190
	if (!src->nr)
		return;

	if (src->max > dst->max)
		dst->max = src->max;

	if (src->min < dst->min || !dst->nr)
		dst->min = src->min;

191 192 193 194 195 196 197 198 199 200 201 202
	dst->total += src->total;
	dst->nr += src->nr;
}

struct lock_class_stats lock_stats(struct lock_class *class)
{
	struct lock_class_stats stats;
	int cpu, i;

	memset(&stats, 0, sizeof(struct lock_class_stats));
	for_each_possible_cpu(cpu) {
		struct lock_class_stats *pcs =
203
			&per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
204 205 206 207

		for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
			stats.contention_point[i] += pcs->contention_point[i];

P
Peter Zijlstra 已提交
208 209 210
		for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
			stats.contending_point[i] += pcs->contending_point[i];

211 212 213 214 215
		lock_time_add(&pcs->read_waittime, &stats.read_waittime);
		lock_time_add(&pcs->write_waittime, &stats.write_waittime);

		lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
		lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
P
Peter Zijlstra 已提交
216 217 218

		for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
			stats.bounces[i] += pcs->bounces[i];
219 220 221 222 223 224 225 226 227 228 229
	}

	return stats;
}

void clear_lock_stats(struct lock_class *class)
{
	int cpu;

	for_each_possible_cpu(cpu) {
		struct lock_class_stats *cpu_stats =
230
			&per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
231 232 233 234

		memset(cpu_stats, 0, sizeof(struct lock_class_stats));
	}
	memset(class->contention_point, 0, sizeof(class->contention_point));
P
Peter Zijlstra 已提交
235
	memset(class->contending_point, 0, sizeof(class->contending_point));
236 237
}

P
Peter Zijlstra 已提交
238 239
static struct lock_class_stats *get_lock_stats(struct lock_class *class)
{
240
	return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
P
Peter Zijlstra 已提交
241 242 243 244
}

static void put_lock_stats(struct lock_class_stats *stats)
{
245
	put_cpu_var(cpu_lock_stats);
P
Peter Zijlstra 已提交
246 247 248 249 250
}

static void lock_release_holdtime(struct held_lock *hlock)
{
	struct lock_class_stats *stats;
251
	u64 holdtime;
P
Peter Zijlstra 已提交
252 253 254 255

	if (!lock_stat)
		return;

256
	holdtime = lockstat_clock() - hlock->holdtime_stamp;
P
Peter Zijlstra 已提交
257

D
Dave Jones 已提交
258
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
259 260 261 262 263 264 265 266 267 268 269 270
	if (hlock->read)
		lock_time_inc(&stats->read_holdtime, holdtime);
	else
		lock_time_inc(&stats->write_holdtime, holdtime);
	put_lock_stats(stats);
}
#else
static inline void lock_release_holdtime(struct held_lock *hlock)
{
}
#endif

I
Ingo Molnar 已提交
271 272 273 274 275 276 277 278 279 280 281 282
/*
 * We keep a global list of all lock classes. The list only grows,
 * never shrinks. The list is only accessed with the lockdep
 * spinlock lock held.
 */
LIST_HEAD(all_lock_classes);

/*
 * The lockdep classes are in a hash-table as well, for fast lookup:
 */
#define CLASSHASH_BITS		(MAX_LOCKDEP_KEYS_BITS - 1)
#define CLASSHASH_SIZE		(1UL << CLASSHASH_BITS)
P
Peter Zijlstra 已提交
283
#define __classhashfn(key)	hash_long((unsigned long)key, CLASSHASH_BITS)
I
Ingo Molnar 已提交
284 285 286 287 288 289 290 291 292 293
#define classhashentry(key)	(classhash_table + __classhashfn((key)))

static struct list_head classhash_table[CLASSHASH_SIZE];

/*
 * We put the lock dependency chains into a hash-table as well, to cache
 * their existence:
 */
#define CHAINHASH_BITS		(MAX_LOCKDEP_CHAINS_BITS-1)
#define CHAINHASH_SIZE		(1UL << CHAINHASH_BITS)
P
Peter Zijlstra 已提交
294
#define __chainhashfn(chain)	hash_long(chain, CHAINHASH_BITS)
I
Ingo Molnar 已提交
295 296 297 298 299 300 301 302 303 304 305
#define chainhashentry(chain)	(chainhash_table + __chainhashfn((chain)))

static struct list_head chainhash_table[CHAINHASH_SIZE];

/*
 * The hash key of the lock dependency chains is a hash itself too:
 * it's a hash of all locks taken up to that lock, including that lock.
 * It's a 64-bit hash, because it's important for the keys to be
 * unique.
 */
#define iterate_chain_key(key1, key2) \
306 307
	(((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
	((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
I
Ingo Molnar 已提交
308 309
	(key2))

310
void lockdep_off(void)
I
Ingo Molnar 已提交
311 312 313 314 315
{
	current->lockdep_recursion++;
}
EXPORT_SYMBOL(lockdep_off);

316
void lockdep_on(void)
I
Ingo Molnar 已提交
317 318 319 320 321 322 323 324 325 326
{
	current->lockdep_recursion--;
}
EXPORT_SYMBOL(lockdep_on);

/*
 * Debugging switches:
 */

#define VERBOSE			0
327
#define VERY_VERBOSE		0
I
Ingo Molnar 已提交
328 329 330 331

#if VERBOSE
# define HARDIRQ_VERBOSE	1
# define SOFTIRQ_VERBOSE	1
332
# define RECLAIM_VERBOSE	1
I
Ingo Molnar 已提交
333 334 335
#else
# define HARDIRQ_VERBOSE	0
# define SOFTIRQ_VERBOSE	0
336
# define RECLAIM_VERBOSE	0
I
Ingo Molnar 已提交
337 338
#endif

339
#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
I
Ingo Molnar 已提交
340 341 342 343 344
/*
 * Quick filtering for interesting events:
 */
static int class_filter(struct lock_class *class)
{
A
Andi Kleen 已提交
345 346
#if 0
	/* Example */
I
Ingo Molnar 已提交
347
	if (class->name_version == 1 &&
A
Andi Kleen 已提交
348
			!strcmp(class->name, "lockname"))
I
Ingo Molnar 已提交
349 350
		return 1;
	if (class->name_version == 1 &&
A
Andi Kleen 已提交
351
			!strcmp(class->name, "&struct->lockfield"))
I
Ingo Molnar 已提交
352
		return 1;
A
Andi Kleen 已提交
353
#endif
354 355
	/* Filter everything else. 1 would be to allow everything else */
	return 0;
I
Ingo Molnar 已提交
356 357 358 359 360 361 362 363 364 365 366 367 368
}
#endif

static int verbose(struct lock_class *class)
{
#if VERBOSE
	return class_filter(class);
#endif
	return 0;
}

/*
 * Stack-trace: tightly packed array of stack backtrace
369
 * addresses. Protected by the graph_lock.
I
Ingo Molnar 已提交
370 371 372 373 374 375 376 377 378 379
 */
unsigned long nr_stack_trace_entries;
static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];

static int save_trace(struct stack_trace *trace)
{
	trace->nr_entries = 0;
	trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
	trace->entries = stack_trace + nr_stack_trace_entries;

380 381
	trace->skip = 3;

C
Christoph Hellwig 已提交
382
	save_stack_trace(trace);
I
Ingo Molnar 已提交
383

P
Peter Zijlstra 已提交
384 385 386 387 388 389 390
	/*
	 * Some daft arches put -1 at the end to indicate its a full trace.
	 *
	 * <rant> this is buggy anyway, since it takes a whole extra entry so a
	 * complete trace that maxes out the entries provided will be reported
	 * as incomplete, friggin useless </rant>
	 */
391 392
	if (trace->nr_entries != 0 &&
	    trace->entries[trace->nr_entries-1] == ULONG_MAX)
P
Peter Zijlstra 已提交
393 394
		trace->nr_entries--;

I
Ingo Molnar 已提交
395 396 397 398
	trace->max_entries = trace->nr_entries;

	nr_stack_trace_entries += trace->nr_entries;

P
Peter Zijlstra 已提交
399
	if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
400 401 402 403 404 405 406
		if (!debug_locks_off_graph_unlock())
			return 0;

		printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
		printk("turning off the locking correctness validator.\n");
		dump_stack();

I
Ingo Molnar 已提交
407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424
		return 0;
	}

	return 1;
}

unsigned int nr_hardirq_chains;
unsigned int nr_softirq_chains;
unsigned int nr_process_chains;
unsigned int max_lockdep_depth;

#ifdef CONFIG_DEBUG_LOCKDEP
/*
 * We cannot printk in early bootup code. Not even early_printk()
 * might work. So we mark any initialization errors and printk
 * about it later on, in lockdep_info().
 */
static int lockdep_init_error;
425 426 427 428 429
static unsigned long lockdep_init_trace_data[20];
static struct stack_trace lockdep_init_trace = {
	.max_entries = ARRAY_SIZE(lockdep_init_trace_data),
	.entries = lockdep_init_trace_data,
};
I
Ingo Molnar 已提交
430 431 432 433

/*
 * Various lockdep statistics:
 */
434
DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
I
Ingo Molnar 已提交
435 436 437 438 439 440
#endif

/*
 * Locking printouts:
 */

P
Peter Zijlstra 已提交
441
#define __USAGE(__STATE)						\
P
Peter Zijlstra 已提交
442 443 444 445
	[LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",	\
	[LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",		\
	[LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
	[LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
P
Peter Zijlstra 已提交
446

I
Ingo Molnar 已提交
447 448
static const char *usage_str[] =
{
P
Peter Zijlstra 已提交
449 450 451 452
#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
#include "lockdep_states.h"
#undef LOCKDEP_STATE
	[LOCK_USED] = "INITIAL USE",
I
Ingo Molnar 已提交
453 454 455 456
};

const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
{
A
Alexey Dobriyan 已提交
457
	return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
I
Ingo Molnar 已提交
458 459
}

460
static inline unsigned long lock_flag(enum lock_usage_bit bit)
I
Ingo Molnar 已提交
461
{
462 463
	return 1UL << bit;
}
I
Ingo Molnar 已提交
464

465 466 467 468 469 470 471 472 473 474
static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
{
	char c = '.';

	if (class->usage_mask & lock_flag(bit + 2))
		c = '+';
	if (class->usage_mask & lock_flag(bit)) {
		c = '-';
		if (class->usage_mask & lock_flag(bit + 2))
			c = '?';
I
Ingo Molnar 已提交
475 476
	}

477 478
	return c;
}
479

P
Peter Zijlstra 已提交
480
void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
481
{
P
Peter Zijlstra 已提交
482
	int i = 0;
483

P
Peter Zijlstra 已提交
484 485 486 487 488 489 490
#define LOCKDEP_STATE(__STATE) 						\
	usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);	\
	usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
#include "lockdep_states.h"
#undef LOCKDEP_STATE

	usage[i] = '\0';
I
Ingo Molnar 已提交
491 492 493 494
}

static void print_lock_name(struct lock_class *class)
{
P
Peter Zijlstra 已提交
495
	char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
I
Ingo Molnar 已提交
496 497
	const char *name;

P
Peter Zijlstra 已提交
498
	get_usage_chars(class, usage);
I
Ingo Molnar 已提交
499 500 501 502 503 504 505 506 507 508 509 510

	name = class->name;
	if (!name) {
		name = __get_key_name(class->key, str);
		printk(" (%s", name);
	} else {
		printk(" (%s", name);
		if (class->name_version > 1)
			printk("#%d", class->name_version);
		if (class->subclass)
			printk("/%d", class->subclass);
	}
P
Peter Zijlstra 已提交
511
	printk("){%s}", usage);
I
Ingo Molnar 已提交
512 513 514 515 516
}

static void print_lockdep_cache(struct lockdep_map *lock)
{
	const char *name;
517
	char str[KSYM_NAME_LEN];
I
Ingo Molnar 已提交
518 519 520 521 522 523 524 525 526 527

	name = lock->name;
	if (!name)
		name = __get_key_name(lock->key->subkeys, str);

	printk("%s", name);
}

static void print_lock(struct held_lock *hlock)
{
D
Dave Jones 已提交
528
	print_lock_name(hlock_class(hlock));
I
Ingo Molnar 已提交
529 530 531 532 533 534 535 536 537
	printk(", at: ");
	print_ip_sym(hlock->acquire_ip);
}

static void lockdep_print_held_locks(struct task_struct *curr)
{
	int i, depth = curr->lockdep_depth;

	if (!depth) {
538
		printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
539 540 541
		return;
	}
	printk("%d lock%s held by %s/%d:\n",
542
		depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
543 544 545 546 547 548 549

	for (i = 0; i < depth; i++) {
		printk(" #%d: ", i);
		print_lock(curr->held_locks + i);
	}
}

P
Peter Zijlstra 已提交
550 551 552 553 554 555 556 557 558 559 560 561 562 563 564
static void print_kernel_version(void)
{
	printk("%s %.*s\n", init_utsname()->release,
		(int)strcspn(init_utsname()->version, " "),
		init_utsname()->version);
}

static int very_verbose(struct lock_class *class)
{
#if VERY_VERBOSE
	return class_filter(class);
#endif
	return 0;
}

I
Ingo Molnar 已提交
565
/*
P
Peter Zijlstra 已提交
566
 * Is this the address of a static object:
I
Ingo Molnar 已提交
567
 */
P
Peter Zijlstra 已提交
568
static int static_obj(void *obj)
I
Ingo Molnar 已提交
569
{
P
Peter Zijlstra 已提交
570 571 572 573
	unsigned long start = (unsigned long) &_stext,
		      end   = (unsigned long) &_end,
		      addr  = (unsigned long) obj;

I
Ingo Molnar 已提交
574
	/*
P
Peter Zijlstra 已提交
575
	 * static variable?
I
Ingo Molnar 已提交
576
	 */
P
Peter Zijlstra 已提交
577 578
	if ((addr >= start) && (addr < end))
		return 1;
I
Ingo Molnar 已提交
579

580 581 582
	if (arch_is_kernel_data(addr))
		return 1;

I
Ingo Molnar 已提交
583
	/*
584
	 * in-kernel percpu var?
I
Ingo Molnar 已提交
585
	 */
586 587
	if (is_kernel_percpu_address(addr))
		return 1;
I
Ingo Molnar 已提交
588

P
Peter Zijlstra 已提交
589
	/*
590
	 * module static or percpu var?
P
Peter Zijlstra 已提交
591
	 */
592
	return is_module_address(addr) || is_module_percpu_address(addr);
593 594
}

I
Ingo Molnar 已提交
595
/*
P
Peter Zijlstra 已提交
596 597
 * To make lock name printouts unique, we calculate a unique
 * class->name_version generation counter:
I
Ingo Molnar 已提交
598
 */
P
Peter Zijlstra 已提交
599
static int count_matching_names(struct lock_class *new_class)
I
Ingo Molnar 已提交
600
{
P
Peter Zijlstra 已提交
601 602
	struct lock_class *class;
	int count = 0;
I
Ingo Molnar 已提交
603

P
Peter Zijlstra 已提交
604
	if (!new_class->name)
I
Ingo Molnar 已提交
605 606
		return 0;

P
Peter Zijlstra 已提交
607 608 609 610 611 612
	list_for_each_entry(class, &all_lock_classes, lock_entry) {
		if (new_class->key - new_class->subclass == class->key)
			return class->name_version;
		if (class->name && !strcmp(class->name, new_class->name))
			count = max(count, class->name_version);
	}
I
Ingo Molnar 已提交
613

P
Peter Zijlstra 已提交
614
	return count + 1;
I
Ingo Molnar 已提交
615 616
}

P
Peter Zijlstra 已提交
617 618 619 620 621 622 623
/*
 * Register a lock's class in the hash-table, if the class is not present
 * yet. Otherwise we look it up. We cache the result in the lock object
 * itself, so actual lookup of the hash should be once per lock object.
 */
static inline struct lock_class *
look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
I
Ingo Molnar 已提交
624
{
P
Peter Zijlstra 已提交
625 626 627
	struct lockdep_subclass_key *key;
	struct list_head *hash_head;
	struct lock_class *class;
I
Ingo Molnar 已提交
628

P
Peter Zijlstra 已提交
629 630 631 632 633 634 635 636 637
#ifdef CONFIG_DEBUG_LOCKDEP
	/*
	 * If the architecture calls into lockdep before initializing
	 * the hashes then we'll warn about it later. (we cannot printk
	 * right now)
	 */
	if (unlikely(!lockdep_initialized)) {
		lockdep_init();
		lockdep_init_error = 1;
638
		save_stack_trace(&lockdep_init_trace);
P
Peter Zijlstra 已提交
639 640
	}
#endif
I
Ingo Molnar 已提交
641

P
Peter Zijlstra 已提交
642 643 644 645 646 647
	/*
	 * Static locks do not have their class-keys yet - for them the key
	 * is the lock object itself:
	 */
	if (unlikely(!lock->key))
		lock->key = (void *)lock;
I
Ingo Molnar 已提交
648

P
Peter Zijlstra 已提交
649 650 651 652 653 654
	/*
	 * NOTE: the class-key must be unique. For dynamic locks, a static
	 * lock_class_key variable is passed in through the mutex_init()
	 * (or spin_lock_init()) call - which acts as the key. For static
	 * locks we use the lock object itself as the key.
	 */
P
Peter Zijlstra 已提交
655 656
	BUILD_BUG_ON(sizeof(struct lock_class_key) >
			sizeof(struct lockdep_map));
I
Ingo Molnar 已提交
657

P
Peter Zijlstra 已提交
658
	key = lock->key->subkeys + subclass;
659

P
Peter Zijlstra 已提交
660
	hash_head = classhashentry(key);
661

P
Peter Zijlstra 已提交
662 663 664 665
	/*
	 * We can walk the hash lockfree, because the hash only
	 * grows, and we are careful when adding entries to the end:
	 */
P
Peter Zijlstra 已提交
666 667 668
	list_for_each_entry(class, hash_head, hash_entry) {
		if (class->key == key) {
			WARN_ON_ONCE(class->name != lock->name);
P
Peter Zijlstra 已提交
669
			return class;
P
Peter Zijlstra 已提交
670 671
		}
	}
I
Ingo Molnar 已提交
672

P
Peter Zijlstra 已提交
673
	return NULL;
I
Ingo Molnar 已提交
674 675 676
}

/*
P
Peter Zijlstra 已提交
677 678 679
 * Register a lock's class in the hash-table, if the class is not present
 * yet. Otherwise we look it up. We cache the result in the lock object
 * itself, so actual lookup of the hash should be once per lock object.
I
Ingo Molnar 已提交
680
 */
P
Peter Zijlstra 已提交
681 682
static inline struct lock_class *
register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
I
Ingo Molnar 已提交
683
{
P
Peter Zijlstra 已提交
684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733
	struct lockdep_subclass_key *key;
	struct list_head *hash_head;
	struct lock_class *class;
	unsigned long flags;

	class = look_up_lock_class(lock, subclass);
	if (likely(class))
		return class;

	/*
	 * Debug-check: all keys must be persistent!
 	 */
	if (!static_obj(lock->key)) {
		debug_locks_off();
		printk("INFO: trying to register non-static key.\n");
		printk("the code is fine but needs lockdep annotation.\n");
		printk("turning off the locking correctness validator.\n");
		dump_stack();

		return NULL;
	}

	key = lock->key->subkeys + subclass;
	hash_head = classhashentry(key);

	raw_local_irq_save(flags);
	if (!graph_lock()) {
		raw_local_irq_restore(flags);
		return NULL;
	}
	/*
	 * We have to do the hash-walk again, to avoid races
	 * with another CPU:
	 */
	list_for_each_entry(class, hash_head, hash_entry)
		if (class->key == key)
			goto out_unlock_set;
	/*
	 * Allocate a new key from the static array, and add it to
	 * the hash:
	 */
	if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
		if (!debug_locks_off_graph_unlock()) {
			raw_local_irq_restore(flags);
			return NULL;
		}
		raw_local_irq_restore(flags);

		printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
		printk("turning off the locking correctness validator.\n");
734
		dump_stack();
P
Peter Zijlstra 已提交
735 736 737
		return NULL;
	}
	class = lock_classes + nr_lock_classes++;
738
	debug_atomic_inc(nr_unused_locks);
P
Peter Zijlstra 已提交
739 740 741 742 743 744 745 746 747 748 749 750
	class->key = key;
	class->name = lock->name;
	class->subclass = subclass;
	INIT_LIST_HEAD(&class->lock_entry);
	INIT_LIST_HEAD(&class->locks_before);
	INIT_LIST_HEAD(&class->locks_after);
	class->name_version = count_matching_names(class);
	/*
	 * We use RCU's safe list-add method to make
	 * parallel walking of the hash-list safe:
	 */
	list_add_tail_rcu(&class->hash_entry, hash_head);
751 752 753 754
	/*
	 * Add it to the global list of classes:
	 */
	list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
P
Peter Zijlstra 已提交
755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797

	if (verbose(class)) {
		graph_unlock();
		raw_local_irq_restore(flags);

		printk("\nnew class %p: %s", class->key, class->name);
		if (class->name_version > 1)
			printk("#%d", class->name_version);
		printk("\n");
		dump_stack();

		raw_local_irq_save(flags);
		if (!graph_lock()) {
			raw_local_irq_restore(flags);
			return NULL;
		}
	}
out_unlock_set:
	graph_unlock();
	raw_local_irq_restore(flags);

	if (!subclass || force)
		lock->class_cache = class;

	if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
		return NULL;

	return class;
}

#ifdef CONFIG_PROVE_LOCKING
/*
 * Allocate a lockdep entry. (assumes the graph_lock held, returns
 * with NULL on failure)
 */
static struct lock_list *alloc_list_entry(void)
{
	if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
		if (!debug_locks_off_graph_unlock())
			return NULL;

		printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
		printk("turning off the locking correctness validator.\n");
798
		dump_stack();
P
Peter Zijlstra 已提交
799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821
		return NULL;
	}
	return list_entries + nr_list_entries++;
}

/*
 * Add a new dependency to the head of the list:
 */
static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
			    struct list_head *head, unsigned long ip, int distance)
{
	struct lock_list *entry;
	/*
	 * Lock not present yet - get a new dependency struct and
	 * add it to the list:
	 */
	entry = alloc_list_entry();
	if (!entry)
		return 0;

	if (!save_trace(&entry->trace))
		return 0;

822 823
	entry->class = this;
	entry->distance = distance;
P
Peter Zijlstra 已提交
824 825 826 827 828 829 830 831 832 833 834 835
	/*
	 * Since we never remove from the dependency list, the list can
	 * be walked lockless by other CPUs, it's only allocation
	 * that must be protected by the spinlock. But this also means
	 * we must make new entries visible only once writes to the
	 * entry become visible - hence the RCU op:
	 */
	list_add_tail_rcu(&entry->entry, head);

	return 1;
}

P
Peter Zijlstra 已提交
836 837 838
/*
 * For good efficiency of modular, we use power of 2
 */
P
Peter Zijlstra 已提交
839 840 841
#define MAX_CIRCULAR_QUEUE_SIZE		4096UL
#define CQ_MASK				(MAX_CIRCULAR_QUEUE_SIZE-1)

P
Peter Zijlstra 已提交
842 843
/*
 * The circular_queue and helpers is used to implement the
P
Peter Zijlstra 已提交
844 845 846
 * breadth-first search(BFS)algorithem, by which we can build
 * the shortest path from the next lock to be acquired to the
 * previous held lock if there is a circular between them.
P
Peter Zijlstra 已提交
847
 */
P
Peter Zijlstra 已提交
848 849 850 851 852 853 854
struct circular_queue {
	unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
	unsigned int  front, rear;
};

static struct circular_queue lock_cq;

855
unsigned int max_bfs_queue_depth;
P
Peter Zijlstra 已提交
856

857 858
static unsigned int lockdep_dependency_gen_id;

P
Peter Zijlstra 已提交
859 860 861
static inline void __cq_init(struct circular_queue *cq)
{
	cq->front = cq->rear = 0;
862
	lockdep_dependency_gen_id++;
P
Peter Zijlstra 已提交
863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903
}

static inline int __cq_empty(struct circular_queue *cq)
{
	return (cq->front == cq->rear);
}

static inline int __cq_full(struct circular_queue *cq)
{
	return ((cq->rear + 1) & CQ_MASK) == cq->front;
}

static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
{
	if (__cq_full(cq))
		return -1;

	cq->element[cq->rear] = elem;
	cq->rear = (cq->rear + 1) & CQ_MASK;
	return 0;
}

static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
{
	if (__cq_empty(cq))
		return -1;

	*elem = cq->element[cq->front];
	cq->front = (cq->front + 1) & CQ_MASK;
	return 0;
}

static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
{
	return (cq->rear - cq->front) & CQ_MASK;
}

static inline void mark_lock_accessed(struct lock_list *lock,
					struct lock_list *parent)
{
	unsigned long nr;
P
Peter Zijlstra 已提交
904

P
Peter Zijlstra 已提交
905 906 907
	nr = lock - list_entries;
	WARN_ON(nr >= nr_list_entries);
	lock->parent = parent;
908
	lock->class->dep_gen_id = lockdep_dependency_gen_id;
P
Peter Zijlstra 已提交
909 910 911 912 913
}

static inline unsigned long lock_accessed(struct lock_list *lock)
{
	unsigned long nr;
P
Peter Zijlstra 已提交
914

P
Peter Zijlstra 已提交
915 916
	nr = lock - list_entries;
	WARN_ON(nr >= nr_list_entries);
917
	return lock->class->dep_gen_id == lockdep_dependency_gen_id;
P
Peter Zijlstra 已提交
918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936
}

static inline struct lock_list *get_lock_parent(struct lock_list *child)
{
	return child->parent;
}

static inline int get_lock_depth(struct lock_list *child)
{
	int depth = 0;
	struct lock_list *parent;

	while ((parent = get_lock_parent(child))) {
		child = parent;
		depth++;
	}
	return depth;
}

937
static int __bfs(struct lock_list *source_entry,
P
Peter Zijlstra 已提交
938 939 940 941
		 void *data,
		 int (*match)(struct lock_list *entry, void *data),
		 struct lock_list **target_entry,
		 int forward)
942 943
{
	struct lock_list *entry;
944
	struct list_head *head;
945 946 947
	struct circular_queue *cq = &lock_cq;
	int ret = 1;

948
	if (match(source_entry, data)) {
949 950 951 952 953
		*target_entry = source_entry;
		ret = 0;
		goto exit;
	}

954 955 956 957 958 959 960 961 962
	if (forward)
		head = &source_entry->class->locks_after;
	else
		head = &source_entry->class->locks_before;

	if (list_empty(head))
		goto exit;

	__cq_init(cq);
963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981
	__cq_enqueue(cq, (unsigned long)source_entry);

	while (!__cq_empty(cq)) {
		struct lock_list *lock;

		__cq_dequeue(cq, (unsigned long *)&lock);

		if (!lock->class) {
			ret = -2;
			goto exit;
		}

		if (forward)
			head = &lock->class->locks_after;
		else
			head = &lock->class->locks_before;

		list_for_each_entry(entry, head, entry) {
			if (!lock_accessed(entry)) {
982
				unsigned int cq_depth;
983
				mark_lock_accessed(entry, lock);
984
				if (match(entry, data)) {
985 986 987 988 989 990 991 992 993
					*target_entry = entry;
					ret = 0;
					goto exit;
				}

				if (__cq_enqueue(cq, (unsigned long)entry)) {
					ret = -1;
					goto exit;
				}
994 995 996
				cq_depth = __cq_get_elem_count(cq);
				if (max_bfs_queue_depth < cq_depth)
					max_bfs_queue_depth = cq_depth;
997 998 999 1000 1001 1002 1003
			}
		}
	}
exit:
	return ret;
}

1004
static inline int __bfs_forwards(struct lock_list *src_entry,
1005 1006 1007
			void *data,
			int (*match)(struct lock_list *entry, void *data),
			struct lock_list **target_entry)
1008
{
1009
	return __bfs(src_entry, data, match, target_entry, 1);
1010 1011 1012

}

1013
static inline int __bfs_backwards(struct lock_list *src_entry,
1014 1015 1016
			void *data,
			int (*match)(struct lock_list *entry, void *data),
			struct lock_list **target_entry)
1017
{
1018
	return __bfs(src_entry, data, match, target_entry, 0);
1019 1020 1021

}

P
Peter Zijlstra 已提交
1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032
/*
 * Recursive, forwards-direction lock-dependency checking, used for
 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
 * checking.
 */

/*
 * Print a dependency chain entry (this is only done when a deadlock
 * has been detected):
 */
static noinline int
1033
print_circular_bug_entry(struct lock_list *target, int depth)
P
Peter Zijlstra 已提交
1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049
{
	if (debug_locks_silent)
		return 0;
	printk("\n-> #%u", depth);
	print_lock_name(target->class);
	printk(":\n");
	print_stack_trace(&target->trace, 6);

	return 0;
}

/*
 * When a circular dependency is detected, print the
 * header first:
 */
static noinline int
1050 1051 1052
print_circular_bug_header(struct lock_list *entry, unsigned int depth,
			struct held_lock *check_src,
			struct held_lock *check_tgt)
P
Peter Zijlstra 已提交
1053 1054 1055
{
	struct task_struct *curr = current;

1056
	if (debug_locks_silent)
P
Peter Zijlstra 已提交
1057 1058 1059 1060 1061 1062 1063
		return 0;

	printk("\n=======================================================\n");
	printk(  "[ INFO: possible circular locking dependency detected ]\n");
	print_kernel_version();
	printk(  "-------------------------------------------------------\n");
	printk("%s/%d is trying to acquire lock:\n",
1064
		curr->comm, task_pid_nr(curr));
1065
	print_lock(check_src);
P
Peter Zijlstra 已提交
1066
	printk("\nbut task is already holding lock:\n");
1067
	print_lock(check_tgt);
P
Peter Zijlstra 已提交
1068 1069 1070 1071 1072 1073 1074 1075
	printk("\nwhich lock already depends on the new lock.\n\n");
	printk("\nthe existing dependency chain (in reverse order) is:\n");

	print_circular_bug_entry(entry, depth);

	return 0;
}

1076 1077 1078 1079 1080
static inline int class_equal(struct lock_list *entry, void *data)
{
	return entry->class == data;
}

1081 1082 1083 1084
static noinline int print_circular_bug(struct lock_list *this,
				struct lock_list *target,
				struct held_lock *check_src,
				struct held_lock *check_tgt)
P
Peter Zijlstra 已提交
1085 1086
{
	struct task_struct *curr = current;
1087
	struct lock_list *parent;
1088
	int depth;
P
Peter Zijlstra 已提交
1089

1090
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
P
Peter Zijlstra 已提交
1091 1092
		return 0;

1093
	if (!save_trace(&this->trace))
P
Peter Zijlstra 已提交
1094 1095
		return 0;

1096 1097
	depth = get_lock_depth(target);

1098
	print_circular_bug_header(target, depth, check_src, check_tgt);
1099 1100 1101 1102 1103 1104 1105

	parent = get_lock_parent(target);

	while (parent) {
		print_circular_bug_entry(parent, --depth);
		parent = get_lock_parent(parent);
	}
P
Peter Zijlstra 已提交
1106 1107 1108 1109 1110 1111 1112 1113 1114 1115

	printk("\nother info that might help us debug this:\n\n");
	lockdep_print_held_locks(curr);

	printk("\nstack backtrace:\n");
	dump_stack();

	return 0;
}

1116 1117 1118 1119 1120 1121 1122 1123 1124 1125
static noinline int print_bfs_bug(int ret)
{
	if (!debug_locks_off_graph_unlock())
		return 0;

	WARN(1, "lockdep bfs error:%d\n", ret);

	return 0;
}

1126
static int noop_count(struct lock_list *entry, void *data)
1127
{
1128 1129 1130
	(*(unsigned long *)data)++;
	return 0;
}
1131

1132 1133 1134 1135
unsigned long __lockdep_count_forward_deps(struct lock_list *this)
{
	unsigned long  count = 0;
	struct lock_list *uninitialized_var(target_entry);
1136

1137
	__bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1138

1139
	return count;
1140 1141 1142 1143
}
unsigned long lockdep_count_forward_deps(struct lock_class *class)
{
	unsigned long ret, flags;
1144 1145 1146 1147
	struct lock_list this;

	this.parent = NULL;
	this.class = class;
1148 1149

	local_irq_save(flags);
1150
	arch_spin_lock(&lockdep_lock);
1151
	ret = __lockdep_count_forward_deps(&this);
1152
	arch_spin_unlock(&lockdep_lock);
1153 1154 1155 1156 1157
	local_irq_restore(flags);

	return ret;
}

1158
unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1159
{
1160 1161
	unsigned long  count = 0;
	struct lock_list *uninitialized_var(target_entry);
1162

1163
	__bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1164

1165
	return count;
1166 1167 1168 1169 1170
}

unsigned long lockdep_count_backward_deps(struct lock_class *class)
{
	unsigned long ret, flags;
1171 1172 1173 1174
	struct lock_list this;

	this.parent = NULL;
	this.class = class;
1175 1176

	local_irq_save(flags);
1177
	arch_spin_lock(&lockdep_lock);
1178
	ret = __lockdep_count_backward_deps(&this);
1179
	arch_spin_unlock(&lockdep_lock);
1180 1181 1182 1183 1184
	local_irq_restore(flags);

	return ret;
}

P
Peter Zijlstra 已提交
1185 1186 1187 1188 1189
/*
 * Prove that the dependency graph starting at <entry> can not
 * lead to <target>. Print an error and return 0 if it does.
 */
static noinline int
1190 1191
check_noncircular(struct lock_list *root, struct lock_class *target,
		struct lock_list **target_entry)
P
Peter Zijlstra 已提交
1192
{
1193
	int result;
P
Peter Zijlstra 已提交
1194

1195
	debug_atomic_inc(nr_cyclic_checks);
1196

1197
	result = __bfs_forwards(root, target, class_equal, target_entry);
I
Ingo Molnar 已提交
1198

1199 1200
	return result;
}
1201

1202
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
I
Ingo Molnar 已提交
1203 1204 1205 1206 1207 1208
/*
 * Forwards and backwards subgraph searching, for the purposes of
 * proving that two subgraphs can be connected by a new dependency
 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
 */

1209 1210 1211 1212 1213 1214 1215
static inline int usage_match(struct lock_list *entry, void *bit)
{
	return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
}



I
Ingo Molnar 已提交
1216 1217
/*
 * Find a node in the forwards-direction dependency sub-graph starting
1218
 * at @root->class that matches @bit.
I
Ingo Molnar 已提交
1219
 *
1220 1221
 * Return 0 if such a node exists in the subgraph, and put that node
 * into *@target_entry.
I
Ingo Molnar 已提交
1222
 *
1223 1224
 * Return 1 otherwise and keep *@target_entry unchanged.
 * Return <0 on error.
I
Ingo Molnar 已提交
1225
 */
1226 1227 1228
static int
find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
			struct lock_list **target_entry)
I
Ingo Molnar 已提交
1229
{
1230
	int result;
I
Ingo Molnar 已提交
1231

1232
	debug_atomic_inc(nr_find_usage_forwards_checks);
I
Ingo Molnar 已提交
1233

1234 1235 1236
	result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);

	return result;
I
Ingo Molnar 已提交
1237 1238 1239 1240
}

/*
 * Find a node in the backwards-direction dependency sub-graph starting
1241
 * at @root->class that matches @bit.
I
Ingo Molnar 已提交
1242
 *
1243 1244
 * Return 0 if such a node exists in the subgraph, and put that node
 * into *@target_entry.
I
Ingo Molnar 已提交
1245
 *
1246 1247
 * Return 1 otherwise and keep *@target_entry unchanged.
 * Return <0 on error.
I
Ingo Molnar 已提交
1248
 */
1249 1250 1251
static int
find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
			struct lock_list **target_entry)
I
Ingo Molnar 已提交
1252
{
1253
	int result;
I
Ingo Molnar 已提交
1254

1255
	debug_atomic_inc(nr_find_usage_backwards_checks);
I
Ingo Molnar 已提交
1256

1257
	result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
D
Dave Jones 已提交
1258

1259
	return result;
I
Ingo Molnar 已提交
1260 1261
}

P
Peter Zijlstra 已提交
1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315
static void print_lock_class_header(struct lock_class *class, int depth)
{
	int bit;

	printk("%*s->", depth, "");
	print_lock_name(class);
	printk(" ops: %lu", class->ops);
	printk(" {\n");

	for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
		if (class->usage_mask & (1 << bit)) {
			int len = depth;

			len += printk("%*s   %s", depth, "", usage_str[bit]);
			len += printk(" at:\n");
			print_stack_trace(class->usage_traces + bit, len);
		}
	}
	printk("%*s }\n", depth, "");

	printk("%*s ... key      at: ",depth,"");
	print_ip_sym((unsigned long)class->key);
}

/*
 * printk the shortest lock dependencies from @start to @end in reverse order:
 */
static void __used
print_shortest_lock_dependencies(struct lock_list *leaf,
				struct lock_list *root)
{
	struct lock_list *entry = leaf;
	int depth;

	/*compute depth from generated tree by BFS*/
	depth = get_lock_depth(leaf);

	do {
		print_lock_class_header(entry->class, depth);
		printk("%*s ... acquired at:\n", depth, "");
		print_stack_trace(&entry->trace, 2);
		printk("\n");

		if (depth == 0 && (entry != root)) {
			printk("lockdep:%s bad BFS generated tree\n", __func__);
			break;
		}

		entry = get_lock_parent(entry);
		depth--;
	} while (entry && (depth >= 0));

	return;
}
1316

I
Ingo Molnar 已提交
1317 1318
static int
print_bad_irq_dependency(struct task_struct *curr,
1319 1320 1321 1322
			 struct lock_list *prev_root,
			 struct lock_list *next_root,
			 struct lock_list *backwards_entry,
			 struct lock_list *forwards_entry,
I
Ingo Molnar 已提交
1323 1324 1325 1326 1327 1328
			 struct held_lock *prev,
			 struct held_lock *next,
			 enum lock_usage_bit bit1,
			 enum lock_usage_bit bit2,
			 const char *irqclass)
{
1329
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
1330 1331 1332 1333 1334
		return 0;

	printk("\n======================================================\n");
	printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
		irqclass, irqclass);
1335
	print_kernel_version();
I
Ingo Molnar 已提交
1336 1337
	printk(  "------------------------------------------------------\n");
	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1338
		curr->comm, task_pid_nr(curr),
I
Ingo Molnar 已提交
1339 1340 1341 1342 1343 1344 1345 1346 1347
		curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
		curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
		curr->hardirqs_enabled,
		curr->softirqs_enabled);
	print_lock(next);

	printk("\nand this task is already holding:\n");
	print_lock(prev);
	printk("which would create a new lock dependency:\n");
D
Dave Jones 已提交
1348
	print_lock_name(hlock_class(prev));
I
Ingo Molnar 已提交
1349
	printk(" ->");
D
Dave Jones 已提交
1350
	print_lock_name(hlock_class(next));
I
Ingo Molnar 已提交
1351 1352 1353 1354
	printk("\n");

	printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
		irqclass);
1355
	print_lock_name(backwards_entry->class);
I
Ingo Molnar 已提交
1356 1357
	printk("\n... which became %s-irq-safe at:\n", irqclass);

1358
	print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
I
Ingo Molnar 已提交
1359 1360

	printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1361
	print_lock_name(forwards_entry->class);
I
Ingo Molnar 已提交
1362 1363 1364
	printk("\n... which became %s-irq-unsafe at:\n", irqclass);
	printk("...");

1365
	print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
I
Ingo Molnar 已提交
1366 1367 1368 1369

	printk("\nother info that might help us debug this:\n\n");
	lockdep_print_held_locks(curr);

1370 1371 1372 1373 1374
	printk("\nthe dependencies between %s-irq-safe lock", irqclass);
	printk(" and the holding lock:\n");
	if (!save_trace(&prev_root->trace))
		return 0;
	print_shortest_lock_dependencies(backwards_entry, prev_root);
I
Ingo Molnar 已提交
1375

1376 1377 1378 1379 1380
	printk("\nthe dependencies between the lock to be acquired");
	printk(" and %s-irq-unsafe lock:\n", irqclass);
	if (!save_trace(&next_root->trace))
		return 0;
	print_shortest_lock_dependencies(forwards_entry, next_root);
I
Ingo Molnar 已提交
1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393

	printk("\nstack backtrace:\n");
	dump_stack();

	return 0;
}

static int
check_usage(struct task_struct *curr, struct held_lock *prev,
	    struct held_lock *next, enum lock_usage_bit bit_backwards,
	    enum lock_usage_bit bit_forwards, const char *irqclass)
{
	int ret;
1394
	struct lock_list this, that;
1395
	struct lock_list *uninitialized_var(target_entry);
1396
	struct lock_list *uninitialized_var(target_entry1);
1397 1398 1399 1400 1401

	this.parent = NULL;

	this.class = hlock_class(prev);
	ret = find_usage_backwards(&this, bit_backwards, &target_entry);
P
Peter Zijlstra 已提交
1402 1403 1404 1405
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
1406

1407 1408 1409
	that.parent = NULL;
	that.class = hlock_class(next);
	ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
P
Peter Zijlstra 已提交
1410 1411 1412 1413
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
I
Ingo Molnar 已提交
1414

1415 1416 1417
	return print_bad_irq_dependency(curr, &this, &that,
			target_entry, target_entry1,
			prev, next,
I
Ingo Molnar 已提交
1418 1419 1420
			bit_backwards, bit_forwards, irqclass);
}

1421 1422
static const char *state_names[] = {
#define LOCKDEP_STATE(__STATE) \
P
Peter Zijlstra 已提交
1423
	__stringify(__STATE),
1424 1425 1426 1427 1428 1429
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

static const char *state_rnames[] = {
#define LOCKDEP_STATE(__STATE) \
P
Peter Zijlstra 已提交
1430
	__stringify(__STATE)"-READ",
1431 1432 1433 1434 1435
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

static inline const char *state_name(enum lock_usage_bit bit)
P
Peter Zijlstra 已提交
1436
{
1437 1438
	return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
}
P
Peter Zijlstra 已提交
1439

1440 1441
static int exclusive_bit(int new_bit)
{
P
Peter Zijlstra 已提交
1442
	/*
1443 1444 1445 1446 1447 1448 1449 1450
	 * USED_IN
	 * USED_IN_READ
	 * ENABLED
	 * ENABLED_READ
	 *
	 * bit 0 - write/read
	 * bit 1 - used_in/enabled
	 * bit 2+  state
P
Peter Zijlstra 已提交
1451
	 */
1452 1453 1454

	int state = new_bit & ~3;
	int dir = new_bit & 2;
P
Peter Zijlstra 已提交
1455 1456

	/*
1457
	 * keep state, bit flip the direction and strip read.
P
Peter Zijlstra 已提交
1458
	 */
1459 1460 1461 1462 1463 1464
	return state | (dir ^ 2);
}

static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
			   struct held_lock *next, enum lock_usage_bit bit)
{
P
Peter Zijlstra 已提交
1465
	/*
1466 1467
	 * Prove that the new dependency does not connect a hardirq-safe
	 * lock with a hardirq-unsafe lock - to achieve this we search
P
Peter Zijlstra 已提交
1468 1469 1470
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
1471 1472
	if (!check_usage(curr, prev, next, bit,
			   exclusive_bit(bit), state_name(bit)))
P
Peter Zijlstra 已提交
1473 1474
		return 0;

1475 1476
	bit++; /* _READ */

1477
	/*
1478 1479
	 * Prove that the new dependency does not connect a hardirq-safe-read
	 * lock with a hardirq-unsafe lock - to achieve this we search
1480 1481 1482
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
1483 1484
	if (!check_usage(curr, prev, next, bit,
			   exclusive_bit(bit), state_name(bit)))
1485 1486
		return 0;

1487 1488 1489 1490 1491 1492 1493 1494 1495
	return 1;
}

static int
check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
		struct held_lock *next)
{
#define LOCKDEP_STATE(__STATE)						\
	if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE))	\
1496
		return 0;
1497 1498
#include "lockdep_states.h"
#undef LOCKDEP_STATE
1499

P
Peter Zijlstra 已提交
1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528
	return 1;
}

static void inc_chains(void)
{
	if (current->hardirq_context)
		nr_hardirq_chains++;
	else {
		if (current->softirq_context)
			nr_softirq_chains++;
		else
			nr_process_chains++;
	}
}

#else

static inline int
check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
		struct held_lock *next)
{
	return 1;
}

static inline void inc_chains(void)
{
	nr_process_chains++;
}

I
Ingo Molnar 已提交
1529 1530 1531 1532 1533 1534
#endif

static int
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
		   struct held_lock *next)
{
1535
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
1536 1537 1538 1539
		return 0;

	printk("\n=============================================\n");
	printk(  "[ INFO: possible recursive locking detected ]\n");
1540
	print_kernel_version();
I
Ingo Molnar 已提交
1541 1542
	printk(  "---------------------------------------------\n");
	printk("%s/%d is trying to acquire lock:\n",
1543
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569
	print_lock(next);
	printk("\nbut task is already holding lock:\n");
	print_lock(prev);

	printk("\nother info that might help us debug this:\n");
	lockdep_print_held_locks(curr);

	printk("\nstack backtrace:\n");
	dump_stack();

	return 0;
}

/*
 * Check whether we are holding such a class already.
 *
 * (Note that this has to be done separately, because the graph cannot
 * detect such classes of deadlocks.)
 *
 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
 */
static int
check_deadlock(struct task_struct *curr, struct held_lock *next,
	       struct lockdep_map *next_instance, int read)
{
	struct held_lock *prev;
P
Peter Zijlstra 已提交
1570
	struct held_lock *nest = NULL;
I
Ingo Molnar 已提交
1571 1572 1573 1574
	int i;

	for (i = 0; i < curr->lockdep_depth; i++) {
		prev = curr->held_locks + i;
P
Peter Zijlstra 已提交
1575 1576 1577 1578

		if (prev->instance == next->nest_lock)
			nest = prev;

D
Dave Jones 已提交
1579
		if (hlock_class(prev) != hlock_class(next))
I
Ingo Molnar 已提交
1580
			continue;
P
Peter Zijlstra 已提交
1581

I
Ingo Molnar 已提交
1582 1583
		/*
		 * Allow read-after-read recursion of the same
1584
		 * lock class (i.e. read_lock(lock)+read_lock(lock)):
I
Ingo Molnar 已提交
1585
		 */
1586
		if ((read == 2) && prev->read)
I
Ingo Molnar 已提交
1587
			return 2;
P
Peter Zijlstra 已提交
1588 1589 1590 1591 1592 1593 1594 1595

		/*
		 * We're holding the nest_lock, which serializes this lock's
		 * nesting behaviour.
		 */
		if (nest)
			return 2;

I
Ingo Molnar 已提交
1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624
		return print_deadlock_bug(curr, prev, next);
	}
	return 1;
}

/*
 * There was a chain-cache miss, and we are about to add a new dependency
 * to a previous lock. We recursively validate the following rules:
 *
 *  - would the adding of the <prev> -> <next> dependency create a
 *    circular dependency in the graph? [== circular deadlock]
 *
 *  - does the new prev->next dependency connect any hardirq-safe lock
 *    (in the full backwards-subgraph starting at <prev>) with any
 *    hardirq-unsafe lock (in the full forwards-subgraph starting at
 *    <next>)? [== illegal lock inversion with hardirq contexts]
 *
 *  - does the new prev->next dependency connect any softirq-safe lock
 *    (in the full backwards-subgraph starting at <prev>) with any
 *    softirq-unsafe lock (in the full forwards-subgraph starting at
 *    <next>)? [== illegal lock inversion with softirq contexts]
 *
 * any of these scenarios could lead to a deadlock.
 *
 * Then if all the validations pass, we add the forwards and backwards
 * dependency.
 */
static int
check_prev_add(struct task_struct *curr, struct held_lock *prev,
1625
	       struct held_lock *next, int distance)
I
Ingo Molnar 已提交
1626 1627 1628
{
	struct lock_list *entry;
	int ret;
1629 1630
	struct lock_list this;
	struct lock_list *uninitialized_var(target_entry);
I
Ingo Molnar 已提交
1631 1632 1633 1634 1635 1636 1637 1638 1639 1640

	/*
	 * Prove that the new <prev> -> <next> dependency would not
	 * create a circular dependency in the graph. (We do this by
	 * forward-recursing into the graph starting at <next>, and
	 * checking whether we can reach <prev>.)
	 *
	 * We are using global variables to control the recursion, to
	 * keep the stackframe size of the recursive functions low:
	 */
1641 1642 1643 1644 1645 1646 1647
	this.class = hlock_class(next);
	this.parent = NULL;
	ret = check_noncircular(&this, hlock_class(prev), &target_entry);
	if (unlikely(!ret))
		return print_circular_bug(&this, target_entry, next, prev);
	else if (unlikely(ret < 0))
		return print_bfs_bug(ret);
1648

P
Peter Zijlstra 已提交
1649
	if (!check_prev_add_irq(curr, prev, next))
I
Ingo Molnar 已提交
1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669
		return 0;

	/*
	 * For recursive read-locks we do all the dependency checks,
	 * but we dont store read-triggered dependencies (only
	 * write-triggered dependencies). This ensures that only the
	 * write-side dependencies matter, and that if for example a
	 * write-lock never takes any other locks, then the reads are
	 * equivalent to a NOP.
	 */
	if (next->read == 2 || prev->read == 2)
		return 1;
	/*
	 * Is the <prev> -> <next> dependency already present?
	 *
	 * (this may occur even though this is a new chain: consider
	 *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
	 *  chains - the second one will be new, but L1 already has
	 *  L2 added to its dependency list, due to the first chain.)
	 */
D
Dave Jones 已提交
1670 1671
	list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
		if (entry->class == hlock_class(next)) {
1672 1673
			if (distance == 1)
				entry->distance = 1;
I
Ingo Molnar 已提交
1674
			return 2;
1675
		}
I
Ingo Molnar 已提交
1676 1677 1678 1679 1680 1681
	}

	/*
	 * Ok, all validations passed, add the new lock
	 * to the previous lock's dependency list:
	 */
D
Dave Jones 已提交
1682 1683 1684
	ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
			       &hlock_class(prev)->locks_after,
			       next->acquire_ip, distance);
1685

I
Ingo Molnar 已提交
1686 1687
	if (!ret)
		return 0;
1688

D
Dave Jones 已提交
1689 1690 1691
	ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
			       &hlock_class(next)->locks_before,
			       next->acquire_ip, distance);
1692 1693
	if (!ret)
		return 0;
I
Ingo Molnar 已提交
1694 1695

	/*
P
Peter Zijlstra 已提交
1696 1697
	 * Debugging printouts:
	 */
D
Dave Jones 已提交
1698
	if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
P
Peter Zijlstra 已提交
1699 1700
		graph_unlock();
		printk("\n new dependency: ");
D
Dave Jones 已提交
1701
		print_lock_name(hlock_class(prev));
P
Peter Zijlstra 已提交
1702
		printk(" => ");
D
Dave Jones 已提交
1703
		print_lock_name(hlock_class(next));
P
Peter Zijlstra 已提交
1704
		printk("\n");
I
Ingo Molnar 已提交
1705
		dump_stack();
P
Peter Zijlstra 已提交
1706
		return graph_lock();
I
Ingo Molnar 已提交
1707
	}
P
Peter Zijlstra 已提交
1708 1709
	return 1;
}
I
Ingo Molnar 已提交
1710

P
Peter Zijlstra 已提交
1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721
/*
 * Add the dependency to all directly-previous locks that are 'relevant'.
 * The ones that are relevant are (in increasing distance from curr):
 * all consecutive trylock entries and the final non-trylock entry - or
 * the end of this context's lock-chain - whichever comes first.
 */
static int
check_prevs_add(struct task_struct *curr, struct held_lock *next)
{
	int depth = curr->lockdep_depth;
	struct held_lock *hlock;
1722

I
Ingo Molnar 已提交
1723
	/*
P
Peter Zijlstra 已提交
1724 1725 1726
	 * Debugging checks.
	 *
	 * Depth must not be zero for a non-head lock:
I
Ingo Molnar 已提交
1727
	 */
P
Peter Zijlstra 已提交
1728 1729
	if (!depth)
		goto out_bug;
I
Ingo Molnar 已提交
1730
	/*
P
Peter Zijlstra 已提交
1731 1732
	 * At least two relevant locks must exist for this
	 * to be a head:
I
Ingo Molnar 已提交
1733
	 */
P
Peter Zijlstra 已提交
1734 1735 1736
	if (curr->held_locks[depth].irq_context !=
			curr->held_locks[depth-1].irq_context)
		goto out_bug;
1737

P
Peter Zijlstra 已提交
1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755
	for (;;) {
		int distance = curr->lockdep_depth - depth + 1;
		hlock = curr->held_locks + depth-1;
		/*
		 * Only non-recursive-read entries get new dependencies
		 * added:
		 */
		if (hlock->read != 2) {
			if (!check_prev_add(curr, hlock, next, distance))
				return 0;
			/*
			 * Stop after the first non-trylock entry,
			 * as non-trylock entries have added their
			 * own direct dependencies already, so this
			 * lock is connected to them indirectly:
			 */
			if (!hlock->trylock)
				break;
1756
		}
P
Peter Zijlstra 已提交
1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768
		depth--;
		/*
		 * End of lock-stack?
		 */
		if (!depth)
			break;
		/*
		 * Stop the search if we cross into another context:
		 */
		if (curr->held_locks[depth].irq_context !=
				curr->held_locks[depth-1].irq_context)
			break;
I
Ingo Molnar 已提交
1769
	}
P
Peter Zijlstra 已提交
1770 1771 1772 1773
	return 1;
out_bug:
	if (!debug_locks_off_graph_unlock())
		return 0;
I
Ingo Molnar 已提交
1774

P
Peter Zijlstra 已提交
1775
	WARN_ON(1);
I
Ingo Molnar 已提交
1776

P
Peter Zijlstra 已提交
1777
	return 0;
I
Ingo Molnar 已提交
1778 1779
}

P
Peter Zijlstra 已提交
1780
unsigned long nr_lock_chains;
1781
struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1782
int nr_chain_hlocks;
1783 1784 1785 1786 1787 1788
static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];

struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
{
	return lock_classes + chain_hlocks[chain->base + i];
}
P
Peter Zijlstra 已提交
1789

I
Ingo Molnar 已提交
1790 1791
/*
 * Look up a dependency chain. If the key is not present yet then
1792 1793 1794
 * add it and return 1 - in this case the new dependency chain is
 * validated. If the key is already hashed, return 0.
 * (On return with 1 graph_lock is held.)
I
Ingo Molnar 已提交
1795
 */
1796 1797 1798
static inline int lookup_chain_cache(struct task_struct *curr,
				     struct held_lock *hlock,
				     u64 chain_key)
I
Ingo Molnar 已提交
1799
{
D
Dave Jones 已提交
1800
	struct lock_class *class = hlock_class(hlock);
I
Ingo Molnar 已提交
1801 1802
	struct list_head *hash_head = chainhashentry(chain_key);
	struct lock_chain *chain;
1803
	struct held_lock *hlock_curr, *hlock_next;
1804
	int i, j, n, cn;
I
Ingo Molnar 已提交
1805

1806 1807
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return 0;
I
Ingo Molnar 已提交
1808 1809 1810 1811 1812 1813 1814
	/*
	 * We can walk it lock-free, because entries only get added
	 * to the hash:
	 */
	list_for_each_entry(chain, hash_head, entry) {
		if (chain->chain_key == chain_key) {
cache_hit:
1815
			debug_atomic_inc(chain_lookup_hits);
1816
			if (very_verbose(class))
1817 1818 1819 1820
				printk("\nhash chain already cached, key: "
					"%016Lx tail class: [%p] %s\n",
					(unsigned long long)chain_key,
					class->key, class->name);
I
Ingo Molnar 已提交
1821 1822 1823
			return 0;
		}
	}
1824
	if (very_verbose(class))
1825 1826
		printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
			(unsigned long long)chain_key, class->key, class->name);
I
Ingo Molnar 已提交
1827 1828 1829 1830
	/*
	 * Allocate a new chain entry from the static array, and add
	 * it to the hash:
	 */
1831 1832
	if (!graph_lock())
		return 0;
I
Ingo Molnar 已提交
1833 1834 1835 1836 1837
	/*
	 * We have to walk the chain again locked - to avoid duplicates:
	 */
	list_for_each_entry(chain, hash_head, entry) {
		if (chain->chain_key == chain_key) {
1838
			graph_unlock();
I
Ingo Molnar 已提交
1839 1840 1841 1842
			goto cache_hit;
		}
	}
	if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1843 1844 1845
		if (!debug_locks_off_graph_unlock())
			return 0;

I
Ingo Molnar 已提交
1846 1847
		printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
		printk("turning off the locking correctness validator.\n");
1848
		dump_stack();
I
Ingo Molnar 已提交
1849 1850 1851 1852
		return 0;
	}
	chain = lock_chains + nr_lock_chains++;
	chain->chain_key = chain_key;
1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863
	chain->irq_context = hlock->irq_context;
	/* Find the first held_lock of current chain */
	hlock_next = hlock;
	for (i = curr->lockdep_depth - 1; i >= 0; i--) {
		hlock_curr = curr->held_locks + i;
		if (hlock_curr->irq_context != hlock_next->irq_context)
			break;
		hlock_next = hlock;
	}
	i++;
	chain->depth = curr->lockdep_depth + 1 - i;
1864 1865 1866 1867 1868 1869 1870 1871 1872
	cn = nr_chain_hlocks;
	while (cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS) {
		n = cmpxchg(&nr_chain_hlocks, cn, cn + chain->depth);
		if (n == cn)
			break;
		cn = n;
	}
	if (likely(cn + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
		chain->base = cn;
1873
		for (j = 0; j < chain->depth - 1; j++, i++) {
D
Dave Jones 已提交
1874
			int lock_id = curr->held_locks[i].class_idx - 1;
1875 1876 1877 1878
			chain_hlocks[chain->base + j] = lock_id;
		}
		chain_hlocks[chain->base + j] = class - lock_classes;
	}
I
Ingo Molnar 已提交
1879
	list_add_tail_rcu(&chain->entry, hash_head);
1880
	debug_atomic_inc(chain_lookup_misses);
P
Peter Zijlstra 已提交
1881 1882 1883 1884 1885 1886
	inc_chains();

	return 1;
}

static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1887
		struct held_lock *hlock, int chain_head, u64 chain_key)
P
Peter Zijlstra 已提交
1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899
{
	/*
	 * Trylock needs to maintain the stack of held locks, but it
	 * does not add new dependencies, because trylock can be done
	 * in any order.
	 *
	 * We look up the chain_key and do the O(N^2) check and update of
	 * the dependencies only if this is a new dependency chain.
	 * (If lookup_chain_cache() returns with 1 it acquires
	 * graph_lock for us)
	 */
	if (!hlock->trylock && (hlock->check == 2) &&
1900
	    lookup_chain_cache(curr, hlock, chain_key)) {
P
Peter Zijlstra 已提交
1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935
		/*
		 * Check whether last held lock:
		 *
		 * - is irq-safe, if this lock is irq-unsafe
		 * - is softirq-safe, if this lock is hardirq-unsafe
		 *
		 * And check whether the new lock's dependency graph
		 * could lead back to the previous lock.
		 *
		 * any of these scenarios could lead to a deadlock. If
		 * All validations
		 */
		int ret = check_deadlock(curr, hlock, lock, hlock->read);

		if (!ret)
			return 0;
		/*
		 * Mark recursive read, as we jump over it when
		 * building dependencies (just like we jump over
		 * trylock entries):
		 */
		if (ret == 2)
			hlock->read = 2;
		/*
		 * Add dependency only if this lock is not the head
		 * of the chain, and if it's not a secondary read-lock:
		 */
		if (!chain_head && ret != 2)
			if (!check_prevs_add(curr, hlock))
				return 0;
		graph_unlock();
	} else
		/* after lookup_chain_cache(): */
		if (unlikely(!debug_locks))
			return 0;
I
Ingo Molnar 已提交
1936 1937 1938

	return 1;
}
P
Peter Zijlstra 已提交
1939 1940 1941
#else
static inline int validate_chain(struct task_struct *curr,
	       	struct lockdep_map *lock, struct held_lock *hlock,
1942
		int chain_head, u64 chain_key)
P
Peter Zijlstra 已提交
1943 1944 1945
{
	return 1;
}
1946
#endif
I
Ingo Molnar 已提交
1947 1948 1949 1950 1951

/*
 * We are building curr_chain_key incrementally, so double-check
 * it from scratch, to make sure that it's done correctly:
 */
1952
static void check_chain_key(struct task_struct *curr)
I
Ingo Molnar 已提交
1953 1954 1955 1956 1957 1958 1959 1960 1961 1962
{
#ifdef CONFIG_DEBUG_LOCKDEP
	struct held_lock *hlock, *prev_hlock = NULL;
	unsigned int i, id;
	u64 chain_key = 0;

	for (i = 0; i < curr->lockdep_depth; i++) {
		hlock = curr->held_locks + i;
		if (chain_key != hlock->prev_chain_key) {
			debug_locks_off();
1963
			WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
I
Ingo Molnar 已提交
1964 1965 1966 1967 1968
				curr->lockdep_depth, i,
				(unsigned long long)chain_key,
				(unsigned long long)hlock->prev_chain_key);
			return;
		}
D
Dave Jones 已提交
1969
		id = hlock->class_idx - 1;
1970 1971 1972
		if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
			return;

I
Ingo Molnar 已提交
1973 1974 1975 1976 1977 1978 1979 1980
		if (prev_hlock && (prev_hlock->irq_context !=
							hlock->irq_context))
			chain_key = 0;
		chain_key = iterate_chain_key(chain_key, id);
		prev_hlock = hlock;
	}
	if (chain_key != curr->curr_chain_key) {
		debug_locks_off();
1981
		WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
I
Ingo Molnar 已提交
1982 1983 1984 1985 1986 1987 1988
			curr->lockdep_depth, i,
			(unsigned long long)chain_key,
			(unsigned long long)curr->curr_chain_key);
	}
#endif
}

P
Peter Zijlstra 已提交
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
static int
print_usage_bug(struct task_struct *curr, struct held_lock *this,
		enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
{
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
		return 0;

	printk("\n=================================\n");
	printk(  "[ INFO: inconsistent lock state ]\n");
	print_kernel_version();
	printk(  "---------------------------------\n");

	printk("inconsistent {%s} -> {%s} usage.\n",
		usage_str[prev_bit], usage_str[new_bit]);

	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
2005
		curr->comm, task_pid_nr(curr),
P
Peter Zijlstra 已提交
2006 2007 2008 2009 2010 2011 2012
		trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
		trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
		trace_hardirqs_enabled(curr),
		trace_softirqs_enabled(curr));
	print_lock(this);

	printk("{%s} state was registered at:\n", usage_str[prev_bit]);
D
Dave Jones 已提交
2013
	print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
P
Peter Zijlstra 已提交
2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031

	print_irqtrace_events(curr);
	printk("\nother info that might help us debug this:\n");
	lockdep_print_held_locks(curr);

	printk("\nstack backtrace:\n");
	dump_stack();

	return 0;
}

/*
 * Print out an error if an invalid bit is set:
 */
static inline int
valid_state(struct task_struct *curr, struct held_lock *this,
	    enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
{
D
Dave Jones 已提交
2032
	if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
P
Peter Zijlstra 已提交
2033 2034 2035 2036 2037 2038 2039
		return print_usage_bug(curr, this, bad_bit, new_bit);
	return 1;
}

static int mark_lock(struct task_struct *curr, struct held_lock *this,
		     enum lock_usage_bit new_bit);

2040
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
I
Ingo Molnar 已提交
2041 2042 2043 2044 2045

/*
 * print irq inversion bug:
 */
static int
2046 2047
print_irq_inversion_bug(struct task_struct *curr,
			struct lock_list *root, struct lock_list *other,
I
Ingo Molnar 已提交
2048 2049 2050
			struct held_lock *this, int forwards,
			const char *irqclass)
{
2051
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
2052 2053 2054 2055
		return 0;

	printk("\n=========================================================\n");
	printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2056
	print_kernel_version();
I
Ingo Molnar 已提交
2057 2058
	printk(  "---------------------------------------------------------\n");
	printk("%s/%d just changed the state of lock:\n",
2059
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
2060 2061
	print_lock(this);
	if (forwards)
2062
		printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
I
Ingo Molnar 已提交
2063
	else
2064
		printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2065
	print_lock_name(other->class);
I
Ingo Molnar 已提交
2066 2067 2068 2069 2070
	printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");

	printk("\nother info that might help us debug this:\n");
	lockdep_print_held_locks(curr);

2071 2072 2073 2074
	printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
	if (!save_trace(&root->trace))
		return 0;
	print_shortest_lock_dependencies(other, root);
I
Ingo Molnar 已提交
2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090

	printk("\nstack backtrace:\n");
	dump_stack();

	return 0;
}

/*
 * Prove that in the forwards-direction subgraph starting at <this>
 * there is no lock matching <mask>:
 */
static int
check_usage_forwards(struct task_struct *curr, struct held_lock *this,
		     enum lock_usage_bit bit, const char *irqclass)
{
	int ret;
2091 2092
	struct lock_list root;
	struct lock_list *uninitialized_var(target_entry);
I
Ingo Molnar 已提交
2093

2094 2095 2096
	root.parent = NULL;
	root.class = hlock_class(this);
	ret = find_usage_forwards(&root, bit, &target_entry);
P
Peter Zijlstra 已提交
2097 2098 2099 2100
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
I
Ingo Molnar 已提交
2101

2102
	return print_irq_inversion_bug(curr, &root, target_entry,
2103
					this, 1, irqclass);
I
Ingo Molnar 已提交
2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114
}

/*
 * Prove that in the backwards-direction subgraph starting at <this>
 * there is no lock matching <mask>:
 */
static int
check_usage_backwards(struct task_struct *curr, struct held_lock *this,
		      enum lock_usage_bit bit, const char *irqclass)
{
	int ret;
2115 2116
	struct lock_list root;
	struct lock_list *uninitialized_var(target_entry);
I
Ingo Molnar 已提交
2117

2118 2119 2120
	root.parent = NULL;
	root.class = hlock_class(this);
	ret = find_usage_backwards(&root, bit, &target_entry);
P
Peter Zijlstra 已提交
2121 2122 2123 2124
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
I
Ingo Molnar 已提交
2125

2126
	return print_irq_inversion_bug(curr, &root, target_entry,
2127
					this, 0, irqclass);
I
Ingo Molnar 已提交
2128 2129
}

2130
void print_irqtrace_events(struct task_struct *curr)
I
Ingo Molnar 已提交
2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142
{
	printk("irq event stamp: %u\n", curr->irq_events);
	printk("hardirqs last  enabled at (%u): ", curr->hardirq_enable_event);
	print_ip_sym(curr->hardirq_enable_ip);
	printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
	print_ip_sym(curr->hardirq_disable_ip);
	printk("softirqs last  enabled at (%u): ", curr->softirq_enable_event);
	print_ip_sym(curr->softirq_enable_ip);
	printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
	print_ip_sym(curr->softirq_disable_ip);
}

2143
static int HARDIRQ_verbose(struct lock_class *class)
I
Ingo Molnar 已提交
2144
{
P
Peter Zijlstra 已提交
2145 2146 2147
#if HARDIRQ_VERBOSE
	return class_filter(class);
#endif
I
Ingo Molnar 已提交
2148 2149 2150
	return 0;
}

2151
static int SOFTIRQ_verbose(struct lock_class *class)
I
Ingo Molnar 已提交
2152
{
P
Peter Zijlstra 已提交
2153 2154 2155 2156
#if SOFTIRQ_VERBOSE
	return class_filter(class);
#endif
	return 0;
I
Ingo Molnar 已提交
2157 2158
}

2159
static int RECLAIM_FS_verbose(struct lock_class *class)
2160 2161 2162 2163 2164 2165 2166
{
#if RECLAIM_VERBOSE
	return class_filter(class);
#endif
	return 0;
}

I
Ingo Molnar 已提交
2167 2168
#define STRICT_READ_CHECKS	1

2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181
static int (*state_verbose_f[])(struct lock_class *class) = {
#define LOCKDEP_STATE(__STATE) \
	__STATE##_verbose,
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

static inline int state_verbose(enum lock_usage_bit bit,
				struct lock_class *class)
{
	return state_verbose_f[bit >> 2](class);
}

2182 2183 2184
typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
			     enum lock_usage_bit bit, const char *name);

2185
static int
2186 2187
mark_lock_irq(struct task_struct *curr, struct held_lock *this,
		enum lock_usage_bit new_bit)
2188
{
2189
	int excl_bit = exclusive_bit(new_bit);
2190
	int read = new_bit & 1;
2191 2192
	int dir = new_bit & 2;

2193 2194 2195 2196 2197 2198 2199
	/*
	 * mark USED_IN has to look forwards -- to ensure no dependency
	 * has ENABLED state, which would allow recursion deadlocks.
	 *
	 * mark ENABLED has to look backwards -- to ensure no dependee
	 * has USED_IN state, which, again, would allow  recursion deadlocks.
	 */
2200 2201
	check_usage_f usage = dir ?
		check_usage_backwards : check_usage_forwards;
2202

2203 2204 2205 2206
	/*
	 * Validate that this particular lock does not have conflicting
	 * usage states.
	 */
2207 2208
	if (!valid_state(curr, this, new_bit, excl_bit))
		return 0;
2209

2210 2211 2212 2213 2214
	/*
	 * Validate that the lock dependencies don't have conflicting usage
	 * states.
	 */
	if ((!read || !dir || STRICT_READ_CHECKS) &&
2215
			!usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2216
		return 0;
2217

2218 2219 2220 2221 2222 2223 2224 2225
	/*
	 * Check for read in write conflicts
	 */
	if (!read) {
		if (!valid_state(curr, this, new_bit, excl_bit + 1))
			return 0;

		if (STRICT_READ_CHECKS &&
2226 2227
			!usage(curr, this, excl_bit + 1,
				state_name(new_bit + 1)))
2228 2229
			return 0;
	}
2230

2231
	if (state_verbose(new_bit, hlock_class(this)))
2232 2233 2234 2235 2236
		return 2;

	return 1;
}

2237
enum mark_type {
2238 2239 2240
#define LOCKDEP_STATE(__STATE)	__STATE,
#include "lockdep_states.h"
#undef LOCKDEP_STATE
2241 2242
};

I
Ingo Molnar 已提交
2243 2244 2245
/*
 * Mark all held locks with a usage bit:
 */
2246
static int
2247
mark_held_locks(struct task_struct *curr, enum mark_type mark)
I
Ingo Molnar 已提交
2248 2249 2250 2251 2252 2253 2254 2255
{
	enum lock_usage_bit usage_bit;
	struct held_lock *hlock;
	int i;

	for (i = 0; i < curr->lockdep_depth; i++) {
		hlock = curr->held_locks + i;

2256 2257 2258 2259 2260
		usage_bit = 2 + (mark << 2); /* ENABLED */
		if (hlock->read)
			usage_bit += 1; /* READ */

		BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2261

2262
		if (!mark_lock(curr, hlock, usage_bit))
I
Ingo Molnar 已提交
2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287
			return 0;
	}

	return 1;
}

/*
 * Debugging helper: via this flag we know that we are in
 * 'early bootup code', and will warn about any invalid irqs-on event:
 */
static int early_boot_irqs_enabled;

void early_boot_irqs_off(void)
{
	early_boot_irqs_enabled = 0;
}

void early_boot_irqs_on(void)
{
	early_boot_irqs_enabled = 1;
}

/*
 * Hardirqs will be enabled:
 */
2288
void trace_hardirqs_on_caller(unsigned long ip)
I
Ingo Molnar 已提交
2289 2290 2291
{
	struct task_struct *curr = current;

2292
	time_hardirqs_on(CALLER_ADDR0, ip);
2293

I
Ingo Molnar 已提交
2294 2295 2296 2297 2298 2299 2300
	if (unlikely(!debug_locks || current->lockdep_recursion))
		return;

	if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
		return;

	if (unlikely(curr->hardirqs_enabled)) {
2301
		debug_atomic_inc(redundant_hardirqs_on);
I
Ingo Molnar 已提交
2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314
		return;
	}
	/* we'll do an OFF -> ON transition: */
	curr->hardirqs_enabled = 1;

	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return;
	if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
		return;
	/*
	 * We are going to turn hardirqs on, so set the
	 * usage bit for all held locks:
	 */
2315
	if (!mark_held_locks(curr, HARDIRQ))
I
Ingo Molnar 已提交
2316 2317 2318 2319 2320 2321 2322
		return;
	/*
	 * If we have softirqs enabled, then set the usage
	 * bit for all held locks. (disabled hardirqs prevented
	 * this bit from being set before)
	 */
	if (curr->softirqs_enabled)
2323
		if (!mark_held_locks(curr, SOFTIRQ))
I
Ingo Molnar 已提交
2324 2325
			return;

P
Peter Zijlstra 已提交
2326 2327
	curr->hardirq_enable_ip = ip;
	curr->hardirq_enable_event = ++curr->irq_events;
2328
	debug_atomic_inc(hardirqs_on_events);
P
Peter Zijlstra 已提交
2329
}
2330
EXPORT_SYMBOL(trace_hardirqs_on_caller);
P
Peter Zijlstra 已提交
2331

2332
void trace_hardirqs_on(void)
2333 2334 2335
{
	trace_hardirqs_on_caller(CALLER_ADDR0);
}
P
Peter Zijlstra 已提交
2336 2337 2338 2339 2340
EXPORT_SYMBOL(trace_hardirqs_on);

/*
 * Hardirqs were disabled:
 */
2341
void trace_hardirqs_off_caller(unsigned long ip)
P
Peter Zijlstra 已提交
2342 2343 2344
{
	struct task_struct *curr = current;

2345
	time_hardirqs_off(CALLER_ADDR0, ip);
2346

P
Peter Zijlstra 已提交
2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357
	if (unlikely(!debug_locks || current->lockdep_recursion))
		return;

	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return;

	if (curr->hardirqs_enabled) {
		/*
		 * We have done an ON -> OFF transition:
		 */
		curr->hardirqs_enabled = 0;
2358
		curr->hardirq_disable_ip = ip;
P
Peter Zijlstra 已提交
2359
		curr->hardirq_disable_event = ++curr->irq_events;
2360
		debug_atomic_inc(hardirqs_off_events);
P
Peter Zijlstra 已提交
2361
	} else
2362
		debug_atomic_inc(redundant_hardirqs_off);
P
Peter Zijlstra 已提交
2363
}
2364
EXPORT_SYMBOL(trace_hardirqs_off_caller);
P
Peter Zijlstra 已提交
2365

2366
void trace_hardirqs_off(void)
2367 2368 2369
{
	trace_hardirqs_off_caller(CALLER_ADDR0);
}
P
Peter Zijlstra 已提交
2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385
EXPORT_SYMBOL(trace_hardirqs_off);

/*
 * Softirqs will be enabled:
 */
void trace_softirqs_on(unsigned long ip)
{
	struct task_struct *curr = current;

	if (unlikely(!debug_locks))
		return;

	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return;

	if (curr->softirqs_enabled) {
2386
		debug_atomic_inc(redundant_softirqs_on);
P
Peter Zijlstra 已提交
2387 2388 2389 2390 2391 2392 2393 2394 2395
		return;
	}

	/*
	 * We'll do an OFF -> ON transition:
	 */
	curr->softirqs_enabled = 1;
	curr->softirq_enable_ip = ip;
	curr->softirq_enable_event = ++curr->irq_events;
2396
	debug_atomic_inc(softirqs_on_events);
P
Peter Zijlstra 已提交
2397 2398 2399 2400 2401 2402
	/*
	 * We are going to turn softirqs on, so set the
	 * usage bit for all held locks, if hardirqs are
	 * enabled too:
	 */
	if (curr->hardirqs_enabled)
2403
		mark_held_locks(curr, SOFTIRQ);
P
Peter Zijlstra 已提交
2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425
}

/*
 * Softirqs were disabled:
 */
void trace_softirqs_off(unsigned long ip)
{
	struct task_struct *curr = current;

	if (unlikely(!debug_locks))
		return;

	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return;

	if (curr->softirqs_enabled) {
		/*
		 * We have done an ON -> OFF transition:
		 */
		curr->softirqs_enabled = 0;
		curr->softirq_disable_ip = ip;
		curr->softirq_disable_event = ++curr->irq_events;
2426
		debug_atomic_inc(softirqs_off_events);
P
Peter Zijlstra 已提交
2427 2428
		DEBUG_LOCKS_WARN_ON(!softirq_count());
	} else
2429
		debug_atomic_inc(redundant_softirqs_off);
P
Peter Zijlstra 已提交
2430 2431
}

2432
static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450
{
	struct task_struct *curr = current;

	if (unlikely(!debug_locks))
		return;

	/* no reclaim without waiting on it */
	if (!(gfp_mask & __GFP_WAIT))
		return;

	/* this guy won't enter reclaim */
	if ((curr->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
		return;

	/* We're only interested __GFP_FS allocations for now */
	if (!(gfp_mask & __GFP_FS))
		return;

2451
	if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2452 2453 2454 2455 2456
		return;

	mark_held_locks(curr, RECLAIM_FS);
}

2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473
static void check_flags(unsigned long flags);

void lockdep_trace_alloc(gfp_t gfp_mask)
{
	unsigned long flags;

	if (unlikely(current->lockdep_recursion))
		return;

	raw_local_irq_save(flags);
	check_flags(flags);
	current->lockdep_recursion = 1;
	__lockdep_trace_alloc(gfp_mask, flags);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}

P
Peter Zijlstra 已提交
2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501
static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
{
	/*
	 * If non-trylock use in a hardirq or softirq context, then
	 * mark the lock as used in these contexts:
	 */
	if (!hlock->trylock) {
		if (hlock->read) {
			if (curr->hardirq_context)
				if (!mark_lock(curr, hlock,
						LOCK_USED_IN_HARDIRQ_READ))
					return 0;
			if (curr->softirq_context)
				if (!mark_lock(curr, hlock,
						LOCK_USED_IN_SOFTIRQ_READ))
					return 0;
		} else {
			if (curr->hardirq_context)
				if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
					return 0;
			if (curr->softirq_context)
				if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
					return 0;
		}
	}
	if (!hlock->hardirqs_off) {
		if (hlock->read) {
			if (!mark_lock(curr, hlock,
P
Peter Zijlstra 已提交
2502
					LOCK_ENABLED_HARDIRQ_READ))
P
Peter Zijlstra 已提交
2503 2504 2505
				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
P
Peter Zijlstra 已提交
2506
						LOCK_ENABLED_SOFTIRQ_READ))
P
Peter Zijlstra 已提交
2507 2508 2509
					return 0;
		} else {
			if (!mark_lock(curr, hlock,
P
Peter Zijlstra 已提交
2510
					LOCK_ENABLED_HARDIRQ))
P
Peter Zijlstra 已提交
2511 2512 2513
				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
P
Peter Zijlstra 已提交
2514
						LOCK_ENABLED_SOFTIRQ))
P
Peter Zijlstra 已提交
2515 2516 2517 2518
					return 0;
		}
	}

2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534
	/*
	 * We reuse the irq context infrastructure more broadly as a general
	 * context checking code. This tests GFP_FS recursion (a lock taken
	 * during reclaim for a GFP_FS allocation is held over a GFP_FS
	 * allocation).
	 */
	if (!hlock->trylock && (curr->lockdep_reclaim_gfp & __GFP_FS)) {
		if (hlock->read) {
			if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS_READ))
					return 0;
		} else {
			if (!mark_lock(curr, hlock, LOCK_USED_IN_RECLAIM_FS))
					return 0;
		}
	}

P
Peter Zijlstra 已提交
2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560
	return 1;
}

static int separate_irq_context(struct task_struct *curr,
		struct held_lock *hlock)
{
	unsigned int depth = curr->lockdep_depth;

	/*
	 * Keep track of points where we cross into an interrupt context:
	 */
	hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
				curr->softirq_context;
	if (depth) {
		struct held_lock *prev_hlock;

		prev_hlock = curr->held_locks + depth-1;
		/*
		 * If we cross into another context, reset the
		 * hash key (this also prevents the checking and the
		 * adding of the dependency to 'prev'):
		 */
		if (prev_hlock->irq_context != hlock->irq_context)
			return 1;
	}
	return 0;
I
Ingo Molnar 已提交
2561 2562
}

P
Peter Zijlstra 已提交
2563
#else
I
Ingo Molnar 已提交
2564

P
Peter Zijlstra 已提交
2565 2566 2567
static inline
int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
		enum lock_usage_bit new_bit)
I
Ingo Molnar 已提交
2568
{
P
Peter Zijlstra 已提交
2569 2570 2571
	WARN_ON(1);
	return 1;
}
I
Ingo Molnar 已提交
2572

P
Peter Zijlstra 已提交
2573 2574 2575 2576 2577
static inline int mark_irqflags(struct task_struct *curr,
		struct held_lock *hlock)
{
	return 1;
}
I
Ingo Molnar 已提交
2578

P
Peter Zijlstra 已提交
2579 2580 2581 2582
static inline int separate_irq_context(struct task_struct *curr,
		struct held_lock *hlock)
{
	return 0;
I
Ingo Molnar 已提交
2583 2584
}

2585 2586 2587 2588
void lockdep_trace_alloc(gfp_t gfp_mask)
{
}

P
Peter Zijlstra 已提交
2589
#endif
I
Ingo Molnar 已提交
2590 2591

/*
P
Peter Zijlstra 已提交
2592
 * Mark a lock with a usage bit, and validate the state transition:
I
Ingo Molnar 已提交
2593
 */
2594
static int mark_lock(struct task_struct *curr, struct held_lock *this,
2595
			     enum lock_usage_bit new_bit)
I
Ingo Molnar 已提交
2596
{
P
Peter Zijlstra 已提交
2597
	unsigned int new_mask = 1 << new_bit, ret = 1;
I
Ingo Molnar 已提交
2598 2599

	/*
P
Peter Zijlstra 已提交
2600 2601
	 * If already set then do not dirty the cacheline,
	 * nor do any checks:
I
Ingo Molnar 已提交
2602
	 */
D
Dave Jones 已提交
2603
	if (likely(hlock_class(this)->usage_mask & new_mask))
P
Peter Zijlstra 已提交
2604 2605 2606 2607
		return 1;

	if (!graph_lock())
		return 0;
I
Ingo Molnar 已提交
2608
	/*
P
Peter Zijlstra 已提交
2609
	 * Make sure we didnt race:
I
Ingo Molnar 已提交
2610
	 */
D
Dave Jones 已提交
2611
	if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
P
Peter Zijlstra 已提交
2612 2613 2614
		graph_unlock();
		return 1;
	}
I
Ingo Molnar 已提交
2615

D
Dave Jones 已提交
2616
	hlock_class(this)->usage_mask |= new_mask;
I
Ingo Molnar 已提交
2617

D
Dave Jones 已提交
2618
	if (!save_trace(hlock_class(this)->usage_traces + new_bit))
P
Peter Zijlstra 已提交
2619
		return 0;
I
Ingo Molnar 已提交
2620

P
Peter Zijlstra 已提交
2621
	switch (new_bit) {
P
Peter Zijlstra 已提交
2622 2623 2624 2625 2626 2627 2628
#define LOCKDEP_STATE(__STATE)			\
	case LOCK_USED_IN_##__STATE:		\
	case LOCK_USED_IN_##__STATE##_READ:	\
	case LOCK_ENABLED_##__STATE:		\
	case LOCK_ENABLED_##__STATE##_READ:
#include "lockdep_states.h"
#undef LOCKDEP_STATE
P
Peter Zijlstra 已提交
2629 2630 2631 2632 2633
		ret = mark_lock_irq(curr, this, new_bit);
		if (!ret)
			return 0;
		break;
	case LOCK_USED:
2634
		debug_atomic_dec(nr_unused_locks);
P
Peter Zijlstra 已提交
2635 2636 2637 2638 2639 2640 2641
		break;
	default:
		if (!debug_locks_off_graph_unlock())
			return 0;
		WARN_ON(1);
		return 0;
	}
I
Ingo Molnar 已提交
2642

P
Peter Zijlstra 已提交
2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656
	graph_unlock();

	/*
	 * We must printk outside of the graph_lock:
	 */
	if (ret == 2) {
		printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
		print_lock(this);
		print_irqtrace_events(curr);
		dump_stack();
	}

	return ret;
}
I
Ingo Molnar 已提交
2657 2658 2659 2660 2661

/*
 * Initialize a lock instance's lock-class mapping info:
 */
void lockdep_init_map(struct lockdep_map *lock, const char *name,
2662
		      struct lock_class_key *key, int subclass)
I
Ingo Molnar 已提交
2663
{
2664 2665 2666 2667 2668 2669 2670
	lock->class_cache = NULL;
#ifdef CONFIG_LOCK_STAT
	lock->cpu = raw_smp_processor_id();
#endif

	if (DEBUG_LOCKS_WARN_ON(!name)) {
		lock->name = "NULL";
I
Ingo Molnar 已提交
2671
		return;
2672 2673 2674
	}

	lock->name = name;
I
Ingo Molnar 已提交
2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686

	if (DEBUG_LOCKS_WARN_ON(!key))
		return;
	/*
	 * Sanity check, the lock-class key must be persistent:
	 */
	if (!static_obj(key)) {
		printk("BUG: key %p not in .data!\n", key);
		DEBUG_LOCKS_WARN_ON(1);
		return;
	}
	lock->key = key;
2687 2688 2689 2690

	if (unlikely(!debug_locks))
		return;

2691 2692
	if (subclass)
		register_lock_class(lock, subclass, 1);
I
Ingo Molnar 已提交
2693 2694 2695 2696 2697 2698 2699 2700 2701
}
EXPORT_SYMBOL_GPL(lockdep_init_map);

/*
 * This gets called for every mutex_lock*()/spin_lock*() operation.
 * We maintain the dependency maps and validate the locking attempt:
 */
static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
			  int trylock, int read, int check, int hardirqs_off,
2702 2703
			  struct lockdep_map *nest_lock, unsigned long ip,
			  int references)
I
Ingo Molnar 已提交
2704 2705
{
	struct task_struct *curr = current;
2706
	struct lock_class *class = NULL;
I
Ingo Molnar 已提交
2707 2708 2709
	struct held_lock *hlock;
	unsigned int depth, id;
	int chain_head = 0;
2710
	int class_idx;
I
Ingo Molnar 已提交
2711 2712
	u64 chain_key;

P
Peter Zijlstra 已提交
2713 2714 2715
	if (!prove_locking)
		check = 1;

I
Ingo Molnar 已提交
2716 2717 2718 2719 2720 2721 2722 2723 2724 2725
	if (unlikely(!debug_locks))
		return 0;

	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return 0;

	if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
		debug_locks_off();
		printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
		printk("turning off the locking correctness validator.\n");
2726
		dump_stack();
I
Ingo Molnar 已提交
2727 2728 2729
		return 0;
	}

2730 2731 2732 2733 2734
	if (!subclass)
		class = lock->class_cache;
	/*
	 * Not cached yet or subclass?
	 */
I
Ingo Molnar 已提交
2735
	if (unlikely(!class)) {
2736
		class = register_lock_class(lock, subclass, 0);
I
Ingo Molnar 已提交
2737 2738 2739
		if (!class)
			return 0;
	}
2740
	atomic_inc((atomic_t *)&class->ops);
I
Ingo Molnar 已提交
2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755 2756 2757
	if (very_verbose(class)) {
		printk("\nacquire class [%p] %s", class->key, class->name);
		if (class->name_version > 1)
			printk("#%d", class->name_version);
		printk("\n");
		dump_stack();
	}

	/*
	 * Add the lock to the list of currently held locks.
	 * (we dont increase the depth just yet, up until the
	 * dependency checks are done)
	 */
	depth = curr->lockdep_depth;
	if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
		return 0;

2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771
	class_idx = class - lock_classes + 1;

	if (depth) {
		hlock = curr->held_locks + depth - 1;
		if (hlock->class_idx == class_idx && nest_lock) {
			if (hlock->references)
				hlock->references++;
			else
				hlock->references = 2;

			return 1;
		}
	}

I
Ingo Molnar 已提交
2772
	hlock = curr->held_locks + depth;
D
Dave Jones 已提交
2773 2774
	if (DEBUG_LOCKS_WARN_ON(!class))
		return 0;
2775
	hlock->class_idx = class_idx;
I
Ingo Molnar 已提交
2776 2777
	hlock->acquire_ip = ip;
	hlock->instance = lock;
P
Peter Zijlstra 已提交
2778
	hlock->nest_lock = nest_lock;
I
Ingo Molnar 已提交
2779 2780 2781
	hlock->trylock = trylock;
	hlock->read = read;
	hlock->check = check;
2782
	hlock->hardirqs_off = !!hardirqs_off;
2783
	hlock->references = references;
P
Peter Zijlstra 已提交
2784 2785
#ifdef CONFIG_LOCK_STAT
	hlock->waittime_stamp = 0;
2786
	hlock->holdtime_stamp = lockstat_clock();
P
Peter Zijlstra 已提交
2787
#endif
I
Ingo Molnar 已提交
2788

P
Peter Zijlstra 已提交
2789 2790 2791
	if (check == 2 && !mark_irqflags(curr, hlock))
		return 0;

I
Ingo Molnar 已提交
2792
	/* mark it as used: */
2793
	if (!mark_lock(curr, hlock, LOCK_USED))
I
Ingo Molnar 已提交
2794
		return 0;
P
Peter Zijlstra 已提交
2795

I
Ingo Molnar 已提交
2796
	/*
2797
	 * Calculate the chain hash: it's the combined hash of all the
I
Ingo Molnar 已提交
2798 2799 2800 2801 2802 2803 2804 2805 2806 2807 2808 2809 2810 2811 2812 2813 2814 2815 2816 2817
	 * lock keys along the dependency chain. We save the hash value
	 * at every step so that we can get the current hash easily
	 * after unlock. The chain hash is then used to cache dependency
	 * results.
	 *
	 * The 'key ID' is what is the most compact key value to drive
	 * the hash, not class->key.
	 */
	id = class - lock_classes;
	if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
		return 0;

	chain_key = curr->curr_chain_key;
	if (!depth) {
		if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
			return 0;
		chain_head = 1;
	}

	hlock->prev_chain_key = chain_key;
P
Peter Zijlstra 已提交
2818 2819 2820
	if (separate_irq_context(curr, hlock)) {
		chain_key = 0;
		chain_head = 1;
I
Ingo Molnar 已提交
2821 2822 2823
	}
	chain_key = iterate_chain_key(chain_key, id);

2824
	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
P
Peter Zijlstra 已提交
2825
		return 0;
2826

2827
	curr->curr_chain_key = chain_key;
I
Ingo Molnar 已提交
2828 2829
	curr->lockdep_depth++;
	check_chain_key(curr);
2830 2831 2832 2833
#ifdef CONFIG_DEBUG_LOCKDEP
	if (unlikely(!debug_locks))
		return 0;
#endif
I
Ingo Molnar 已提交
2834 2835 2836 2837
	if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
		debug_locks_off();
		printk("BUG: MAX_LOCK_DEPTH too low!\n");
		printk("turning off the locking correctness validator.\n");
2838
		dump_stack();
I
Ingo Molnar 已提交
2839 2840
		return 0;
	}
2841

I
Ingo Molnar 已提交
2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856 2857 2858 2859 2860
	if (unlikely(curr->lockdep_depth > max_lockdep_depth))
		max_lockdep_depth = curr->lockdep_depth;

	return 1;
}

static int
print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
			   unsigned long ip)
{
	if (!debug_locks_off())
		return 0;
	if (debug_locks_silent)
		return 0;

	printk("\n=====================================\n");
	printk(  "[ BUG: bad unlock balance detected! ]\n");
	printk(  "-------------------------------------\n");
	printk("%s/%d is trying to release lock (",
2861
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
2862 2863 2864 2865 2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891
	print_lockdep_cache(lock);
	printk(") at:\n");
	print_ip_sym(ip);
	printk("but there are no more locks to release!\n");
	printk("\nother info that might help us debug this:\n");
	lockdep_print_held_locks(curr);

	printk("\nstack backtrace:\n");
	dump_stack();

	return 0;
}

/*
 * Common debugging checks for both nested and non-nested unlock:
 */
static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
			unsigned long ip)
{
	if (unlikely(!debug_locks))
		return 0;
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return 0;

	if (curr->lockdep_depth <= 0)
		return print_unlock_inbalance_bug(curr, lock, ip);

	return 1;
}

2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915
static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
{
	if (hlock->instance == lock)
		return 1;

	if (hlock->references) {
		struct lock_class *class = lock->class_cache;

		if (!class)
			class = look_up_lock_class(lock, 0);

		if (DEBUG_LOCKS_WARN_ON(!class))
			return 0;

		if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
			return 0;

		if (hlock->class_idx == class - lock_classes + 1)
			return 1;
	}

	return 0;
}

2916
static int
2917 2918 2919
__lock_set_class(struct lockdep_map *lock, const char *name,
		 struct lock_class_key *key, unsigned int subclass,
		 unsigned long ip)
2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938
{
	struct task_struct *curr = current;
	struct held_lock *hlock, *prev_hlock;
	struct lock_class *class;
	unsigned int depth;
	int i;

	depth = curr->lockdep_depth;
	if (DEBUG_LOCKS_WARN_ON(!depth))
		return 0;

	prev_hlock = NULL;
	for (i = depth-1; i >= 0; i--) {
		hlock = curr->held_locks + i;
		/*
		 * We must not cross into another context:
		 */
		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
			break;
2939
		if (match_held_lock(hlock, lock))
2940 2941 2942 2943 2944 2945
			goto found_it;
		prev_hlock = hlock;
	}
	return print_unlock_inbalance_bug(curr, lock, ip);

found_it:
2946
	lockdep_init_map(lock, name, key, 0);
2947
	class = register_lock_class(lock, subclass, 0);
D
Dave Jones 已提交
2948
	hlock->class_idx = class - lock_classes + 1;
2949 2950 2951 2952 2953 2954 2955

	curr->lockdep_depth = i;
	curr->curr_chain_key = hlock->prev_chain_key;

	for (; i < depth; i++) {
		hlock = curr->held_locks + i;
		if (!__lock_acquire(hlock->instance,
D
Dave Jones 已提交
2956
			hlock_class(hlock)->subclass, hlock->trylock,
2957
				hlock->read, hlock->check, hlock->hardirqs_off,
2958 2959
				hlock->nest_lock, hlock->acquire_ip,
				hlock->references))
2960 2961 2962 2963 2964 2965 2966 2967
			return 0;
	}

	if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
		return 0;
	return 1;
}

I
Ingo Molnar 已提交
2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996 2997
/*
 * Remove the lock to the list of currently held locks in a
 * potentially non-nested (out of order) manner. This is a
 * relatively rare operation, as all the unlock APIs default
 * to nested mode (which uses lock_release()):
 */
static int
lock_release_non_nested(struct task_struct *curr,
			struct lockdep_map *lock, unsigned long ip)
{
	struct held_lock *hlock, *prev_hlock;
	unsigned int depth;
	int i;

	/*
	 * Check whether the lock exists in the current stack
	 * of held locks:
	 */
	depth = curr->lockdep_depth;
	if (DEBUG_LOCKS_WARN_ON(!depth))
		return 0;

	prev_hlock = NULL;
	for (i = depth-1; i >= 0; i--) {
		hlock = curr->held_locks + i;
		/*
		 * We must not cross into another context:
		 */
		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
			break;
2998
		if (match_held_lock(hlock, lock))
I
Ingo Molnar 已提交
2999 3000 3001 3002 3003 3004
			goto found_it;
		prev_hlock = hlock;
	}
	return print_unlock_inbalance_bug(curr, lock, ip);

found_it:
3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018
	if (hlock->instance == lock)
		lock_release_holdtime(hlock);

	if (hlock->references) {
		hlock->references--;
		if (hlock->references) {
			/*
			 * We had, and after removing one, still have
			 * references, the current lock stack is still
			 * valid. We're done!
			 */
			return 1;
		}
	}
P
Peter Zijlstra 已提交
3019

I
Ingo Molnar 已提交
3020 3021 3022 3023 3024
	/*
	 * We have the right lock to unlock, 'hlock' points to it.
	 * Now we remove it from the stack, and add back the other
	 * entries (if any), recalculating the hash along the way:
	 */
3025

I
Ingo Molnar 已提交
3026 3027 3028 3029 3030 3031
	curr->lockdep_depth = i;
	curr->curr_chain_key = hlock->prev_chain_key;

	for (i++; i < depth; i++) {
		hlock = curr->held_locks + i;
		if (!__lock_acquire(hlock->instance,
D
Dave Jones 已提交
3032
			hlock_class(hlock)->subclass, hlock->trylock,
I
Ingo Molnar 已提交
3033
				hlock->read, hlock->check, hlock->hardirqs_off,
3034 3035
				hlock->nest_lock, hlock->acquire_ip,
				hlock->references))
I
Ingo Molnar 已提交
3036 3037 3038 3039 3040 3041 3042 3043 3044 3045 3046 3047 3048 3049 3050 3051 3052 3053 3054 3055 3056 3057 3058 3059 3060 3061 3062 3063 3064
			return 0;
	}

	if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
		return 0;
	return 1;
}

/*
 * Remove the lock to the list of currently held locks - this gets
 * called on mutex_unlock()/spin_unlock*() (or on a failed
 * mutex_lock_interruptible()). This is done for unlocks that nest
 * perfectly. (i.e. the current top of the lock-stack is unlocked)
 */
static int lock_release_nested(struct task_struct *curr,
			       struct lockdep_map *lock, unsigned long ip)
{
	struct held_lock *hlock;
	unsigned int depth;

	/*
	 * Pop off the top of the lock stack:
	 */
	depth = curr->lockdep_depth - 1;
	hlock = curr->held_locks + depth;

	/*
	 * Is the unlock non-nested:
	 */
3065
	if (hlock->instance != lock || hlock->references)
I
Ingo Molnar 已提交
3066 3067 3068 3069 3070 3071 3072 3073
		return lock_release_non_nested(curr, lock, ip);
	curr->lockdep_depth--;

	if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
		return 0;

	curr->curr_chain_key = hlock->prev_chain_key;

P
Peter Zijlstra 已提交
3074 3075
	lock_release_holdtime(hlock);

I
Ingo Molnar 已提交
3076 3077
#ifdef CONFIG_DEBUG_LOCKDEP
	hlock->prev_chain_key = 0;
D
Dave Jones 已提交
3078
	hlock->class_idx = 0;
I
Ingo Molnar 已提交
3079 3080 3081 3082 3083 3084 3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108 3109
	hlock->acquire_ip = 0;
	hlock->irq_context = 0;
#endif
	return 1;
}

/*
 * Remove the lock to the list of currently held locks - this gets
 * called on mutex_unlock()/spin_unlock*() (or on a failed
 * mutex_lock_interruptible()). This is done for unlocks that nest
 * perfectly. (i.e. the current top of the lock-stack is unlocked)
 */
static void
__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
{
	struct task_struct *curr = current;

	if (!check_unlock(curr, lock, ip))
		return;

	if (nested) {
		if (!lock_release_nested(curr, lock, ip))
			return;
	} else {
		if (!lock_release_non_nested(curr, lock, ip))
			return;
	}

	check_chain_key(curr);
}

3110 3111 3112 3113 3114 3115
static int __lock_is_held(struct lockdep_map *lock)
{
	struct task_struct *curr = current;
	int i;

	for (i = 0; i < curr->lockdep_depth; i++) {
3116 3117 3118
		struct held_lock *hlock = curr->held_locks + i;

		if (match_held_lock(hlock, lock))
3119 3120 3121 3122 3123 3124
			return 1;
	}

	return 0;
}

I
Ingo Molnar 已提交
3125 3126 3127
/*
 * Check whether we follow the irq-flags state precisely:
 */
3128
static void check_flags(unsigned long flags)
I
Ingo Molnar 已提交
3129
{
3130 3131
#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
    defined(CONFIG_TRACE_IRQFLAGS)
I
Ingo Molnar 已提交
3132 3133 3134
	if (!debug_locks)
		return;

3135 3136 3137 3138 3139 3140 3141 3142 3143
	if (irqs_disabled_flags(flags)) {
		if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
			printk("possible reason: unannotated irqs-off.\n");
		}
	} else {
		if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
			printk("possible reason: unannotated irqs-on.\n");
		}
	}
I
Ingo Molnar 已提交
3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161

	/*
	 * We dont accurately track softirq state in e.g.
	 * hardirq contexts (such as on 4KSTACKS), so only
	 * check if not in hardirq contexts:
	 */
	if (!hardirq_count()) {
		if (softirq_count())
			DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
		else
			DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
	}

	if (!debug_locks)
		print_irqtrace_events(current);
#endif
}

3162 3163 3164
void lock_set_class(struct lockdep_map *lock, const char *name,
		    struct lock_class_key *key, unsigned int subclass,
		    unsigned long ip)
3165 3166 3167 3168 3169 3170 3171 3172 3173
{
	unsigned long flags;

	if (unlikely(current->lockdep_recursion))
		return;

	raw_local_irq_save(flags);
	current->lockdep_recursion = 1;
	check_flags(flags);
3174
	if (__lock_set_class(lock, name, key, subclass, ip))
3175 3176 3177 3178
		check_chain_key(current);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
3179
EXPORT_SYMBOL_GPL(lock_set_class);
3180

I
Ingo Molnar 已提交
3181 3182 3183 3184
/*
 * We are not always called with irqs disabled - do that here,
 * and also avoid lockdep recursion:
 */
3185
void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
P
Peter Zijlstra 已提交
3186 3187
			  int trylock, int read, int check,
			  struct lockdep_map *nest_lock, unsigned long ip)
I
Ingo Molnar 已提交
3188 3189 3190 3191 3192 3193 3194 3195 3196 3197
{
	unsigned long flags;

	if (unlikely(current->lockdep_recursion))
		return;

	raw_local_irq_save(flags);
	check_flags(flags);

	current->lockdep_recursion = 1;
3198
	trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
I
Ingo Molnar 已提交
3199
	__lock_acquire(lock, subclass, trylock, read, check,
3200
		       irqs_disabled_flags(flags), nest_lock, ip, 0);
I
Ingo Molnar 已提交
3201 3202 3203 3204 3205
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquire);

3206
void lock_release(struct lockdep_map *lock, int nested,
3207
			  unsigned long ip)
I
Ingo Molnar 已提交
3208 3209 3210 3211 3212 3213 3214 3215 3216
{
	unsigned long flags;

	if (unlikely(current->lockdep_recursion))
		return;

	raw_local_irq_save(flags);
	check_flags(flags);
	current->lockdep_recursion = 1;
3217
	trace_lock_release(lock, nested, ip);
I
Ingo Molnar 已提交
3218 3219 3220 3221 3222 3223
	__lock_release(lock, nested, ip);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_release);

3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243
int lock_is_held(struct lockdep_map *lock)
{
	unsigned long flags;
	int ret = 0;

	if (unlikely(current->lockdep_recursion))
		return ret;

	raw_local_irq_save(flags);
	check_flags(flags);

	current->lockdep_recursion = 1;
	ret = __lock_is_held(lock);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);

	return ret;
}
EXPORT_SYMBOL_GPL(lock_is_held);

3244 3245 3246 3247 3248 3249 3250 3251 3252 3253
void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
{
	current->lockdep_reclaim_gfp = gfp_mask;
}

void lockdep_clear_current_reclaim_state(void)
{
	current->lockdep_reclaim_gfp = 0;
}

P
Peter Zijlstra 已提交
3254 3255 3256 3257 3258 3259 3260 3261 3262 3263 3264 3265 3266 3267
#ifdef CONFIG_LOCK_STAT
static int
print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
			   unsigned long ip)
{
	if (!debug_locks_off())
		return 0;
	if (debug_locks_silent)
		return 0;

	printk("\n=================================\n");
	printk(  "[ BUG: bad contention detected! ]\n");
	printk(  "---------------------------------\n");
	printk("%s/%d is trying to contend lock (",
3268
		curr->comm, task_pid_nr(curr));
P
Peter Zijlstra 已提交
3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288
	print_lockdep_cache(lock);
	printk(") at:\n");
	print_ip_sym(ip);
	printk("but there are no locks held!\n");
	printk("\nother info that might help us debug this:\n");
	lockdep_print_held_locks(curr);

	printk("\nstack backtrace:\n");
	dump_stack();

	return 0;
}

static void
__lock_contended(struct lockdep_map *lock, unsigned long ip)
{
	struct task_struct *curr = current;
	struct held_lock *hlock, *prev_hlock;
	struct lock_class_stats *stats;
	unsigned int depth;
P
Peter Zijlstra 已提交
3289
	int i, contention_point, contending_point;
P
Peter Zijlstra 已提交
3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302

	depth = curr->lockdep_depth;
	if (DEBUG_LOCKS_WARN_ON(!depth))
		return;

	prev_hlock = NULL;
	for (i = depth-1; i >= 0; i--) {
		hlock = curr->held_locks + i;
		/*
		 * We must not cross into another context:
		 */
		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
			break;
3303
		if (match_held_lock(hlock, lock))
P
Peter Zijlstra 已提交
3304 3305 3306 3307 3308 3309 3310
			goto found_it;
		prev_hlock = hlock;
	}
	print_lock_contention_bug(curr, lock, ip);
	return;

found_it:
3311 3312 3313
	if (hlock->instance != lock)
		return;

3314
	hlock->waittime_stamp = lockstat_clock();
P
Peter Zijlstra 已提交
3315

P
Peter Zijlstra 已提交
3316 3317 3318
	contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
	contending_point = lock_point(hlock_class(hlock)->contending_point,
				      lock->ip);
P
Peter Zijlstra 已提交
3319

D
Dave Jones 已提交
3320
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3321 3322 3323 3324
	if (contention_point < LOCKSTAT_POINTS)
		stats->contention_point[contention_point]++;
	if (contending_point < LOCKSTAT_POINTS)
		stats->contending_point[contending_point]++;
P
Peter Zijlstra 已提交
3325 3326
	if (lock->cpu != smp_processor_id())
		stats->bounces[bounce_contended + !!hlock->read]++;
P
Peter Zijlstra 已提交
3327 3328 3329 3330
	put_lock_stats(stats);
}

static void
P
Peter Zijlstra 已提交
3331
__lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3332 3333 3334 3335 3336
{
	struct task_struct *curr = current;
	struct held_lock *hlock, *prev_hlock;
	struct lock_class_stats *stats;
	unsigned int depth;
3337
	u64 now, waittime = 0;
P
Peter Zijlstra 已提交
3338
	int i, cpu;
P
Peter Zijlstra 已提交
3339 3340 3341 3342 3343 3344 3345 3346 3347 3348 3349 3350 3351

	depth = curr->lockdep_depth;
	if (DEBUG_LOCKS_WARN_ON(!depth))
		return;

	prev_hlock = NULL;
	for (i = depth-1; i >= 0; i--) {
		hlock = curr->held_locks + i;
		/*
		 * We must not cross into another context:
		 */
		if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
			break;
3352
		if (match_held_lock(hlock, lock))
P
Peter Zijlstra 已提交
3353 3354 3355 3356 3357 3358 3359
			goto found_it;
		prev_hlock = hlock;
	}
	print_lock_contention_bug(curr, lock, _RET_IP_);
	return;

found_it:
3360 3361 3362
	if (hlock->instance != lock)
		return;

P
Peter Zijlstra 已提交
3363 3364
	cpu = smp_processor_id();
	if (hlock->waittime_stamp) {
3365
		now = lockstat_clock();
P
Peter Zijlstra 已提交
3366 3367 3368
		waittime = now - hlock->waittime_stamp;
		hlock->holdtime_stamp = now;
	}
P
Peter Zijlstra 已提交
3369

3370 3371
	trace_lock_acquired(lock, ip, waittime);

D
Dave Jones 已提交
3372
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3373 3374 3375 3376 3377 3378 3379 3380
	if (waittime) {
		if (hlock->read)
			lock_time_inc(&stats->read_waittime, waittime);
		else
			lock_time_inc(&stats->write_waittime, waittime);
	}
	if (lock->cpu != cpu)
		stats->bounces[bounce_acquired + !!hlock->read]++;
P
Peter Zijlstra 已提交
3381
	put_lock_stats(stats);
P
Peter Zijlstra 已提交
3382 3383

	lock->cpu = cpu;
P
Peter Zijlstra 已提交
3384
	lock->ip = ip;
P
Peter Zijlstra 已提交
3385 3386 3387 3388 3389 3390 3391 3392 3393 3394 3395 3396 3397 3398 3399
}

void lock_contended(struct lockdep_map *lock, unsigned long ip)
{
	unsigned long flags;

	if (unlikely(!lock_stat))
		return;

	if (unlikely(current->lockdep_recursion))
		return;

	raw_local_irq_save(flags);
	check_flags(flags);
	current->lockdep_recursion = 1;
3400
	trace_lock_contended(lock, ip);
P
Peter Zijlstra 已提交
3401 3402 3403 3404 3405 3406
	__lock_contended(lock, ip);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_contended);

P
Peter Zijlstra 已提交
3407
void lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419
{
	unsigned long flags;

	if (unlikely(!lock_stat))
		return;

	if (unlikely(current->lockdep_recursion))
		return;

	raw_local_irq_save(flags);
	check_flags(flags);
	current->lockdep_recursion = 1;
P
Peter Zijlstra 已提交
3420
	__lock_acquired(lock, ip);
P
Peter Zijlstra 已提交
3421 3422 3423 3424 3425 3426
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquired);
#endif

I
Ingo Molnar 已提交
3427 3428 3429 3430 3431 3432 3433 3434
/*
 * Used by the testsuite, sanitize the validator state
 * after a simulated failure:
 */

void lockdep_reset(void)
{
	unsigned long flags;
3435
	int i;
I
Ingo Molnar 已提交
3436 3437 3438 3439 3440 3441 3442 3443 3444 3445

	raw_local_irq_save(flags);
	current->curr_chain_key = 0;
	current->lockdep_depth = 0;
	current->lockdep_recursion = 0;
	memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
	nr_hardirq_chains = 0;
	nr_softirq_chains = 0;
	nr_process_chains = 0;
	debug_locks = 1;
3446 3447
	for (i = 0; i < CHAINHASH_SIZE; i++)
		INIT_LIST_HEAD(chainhash_table + i);
I
Ingo Molnar 已提交
3448 3449 3450 3451 3452 3453 3454 3455 3456 3457 3458 3459 3460 3461 3462 3463 3464 3465 3466 3467 3468
	raw_local_irq_restore(flags);
}

static void zap_class(struct lock_class *class)
{
	int i;

	/*
	 * Remove all dependencies this lock is
	 * involved in:
	 */
	for (i = 0; i < nr_list_entries; i++) {
		if (list_entries[i].class == class)
			list_del_rcu(&list_entries[i].entry);
	}
	/*
	 * Unhash the class and remove it from the all_lock_classes list:
	 */
	list_del_rcu(&class->hash_entry);
	list_del_rcu(&class->lock_entry);

3469
	class->key = NULL;
I
Ingo Molnar 已提交
3470 3471
}

3472
static inline int within(const void *addr, void *start, unsigned long size)
I
Ingo Molnar 已提交
3473 3474 3475 3476 3477 3478 3479 3480 3481 3482
{
	return addr >= start && addr < start + size;
}

void lockdep_free_key_range(void *start, unsigned long size)
{
	struct lock_class *class, *next;
	struct list_head *head;
	unsigned long flags;
	int i;
3483
	int locked;
I
Ingo Molnar 已提交
3484 3485

	raw_local_irq_save(flags);
3486
	locked = graph_lock();
I
Ingo Molnar 已提交
3487 3488 3489 3490 3491 3492 3493 3494

	/*
	 * Unhash all classes that were created by this module:
	 */
	for (i = 0; i < CLASSHASH_SIZE; i++) {
		head = classhash_table + i;
		if (list_empty(head))
			continue;
3495
		list_for_each_entry_safe(class, next, head, hash_entry) {
I
Ingo Molnar 已提交
3496 3497
			if (within(class->key, start, size))
				zap_class(class);
3498 3499 3500
			else if (within(class->name, start, size))
				zap_class(class);
		}
I
Ingo Molnar 已提交
3501 3502
	}

3503 3504
	if (locked)
		graph_unlock();
I
Ingo Molnar 已提交
3505 3506 3507 3508 3509
	raw_local_irq_restore(flags);
}

void lockdep_reset_lock(struct lockdep_map *lock)
{
3510
	struct lock_class *class, *next;
I
Ingo Molnar 已提交
3511 3512 3513
	struct list_head *head;
	unsigned long flags;
	int i, j;
3514
	int locked;
I
Ingo Molnar 已提交
3515 3516 3517 3518

	raw_local_irq_save(flags);

	/*
3519 3520 3521 3522 3523 3524 3525 3526 3527 3528 3529 3530 3531
	 * Remove all classes this lock might have:
	 */
	for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
		/*
		 * If the class exists we look it up and zap it:
		 */
		class = look_up_lock_class(lock, j);
		if (class)
			zap_class(class);
	}
	/*
	 * Debug check: in the end all mapped classes should
	 * be gone.
I
Ingo Molnar 已提交
3532
	 */
3533
	locked = graph_lock();
I
Ingo Molnar 已提交
3534 3535 3536 3537 3538
	for (i = 0; i < CLASSHASH_SIZE; i++) {
		head = classhash_table + i;
		if (list_empty(head))
			continue;
		list_for_each_entry_safe(class, next, head, hash_entry) {
3539
			if (unlikely(class == lock->class_cache)) {
3540 3541
				if (debug_locks_off_graph_unlock())
					WARN_ON(1);
3542
				goto out_restore;
I
Ingo Molnar 已提交
3543 3544 3545
			}
		}
	}
3546 3547
	if (locked)
		graph_unlock();
3548 3549

out_restore:
I
Ingo Molnar 已提交
3550 3551 3552
	raw_local_irq_restore(flags);
}

3553
void lockdep_init(void)
I
Ingo Molnar 已提交
3554 3555 3556 3557 3558 3559 3560 3561 3562 3563 3564 3565 3566 3567 3568 3569 3570 3571 3572 3573 3574 3575 3576 3577 3578
{
	int i;

	/*
	 * Some architectures have their own start_kernel()
	 * code which calls lockdep_init(), while we also
	 * call lockdep_init() from the start_kernel() itself,
	 * and we want to initialize the hashes only once:
	 */
	if (lockdep_initialized)
		return;

	for (i = 0; i < CLASSHASH_SIZE; i++)
		INIT_LIST_HEAD(classhash_table + i);

	for (i = 0; i < CHAINHASH_SIZE; i++)
		INIT_LIST_HEAD(chainhash_table + i);

	lockdep_initialized = 1;
}

void __init lockdep_info(void)
{
	printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");

3579
	printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
I
Ingo Molnar 已提交
3580 3581
	printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
	printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3582
	printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
I
Ingo Molnar 已提交
3583 3584 3585 3586 3587 3588 3589 3590 3591
	printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
	printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
	printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);

	printk(" memory used by lock dependency info: %lu kB\n",
		(sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
		sizeof(struct list_head) * CLASSHASH_SIZE +
		sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
		sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
M
Ming Lei 已提交
3592
		sizeof(struct list_head) * CHAINHASH_SIZE
3593
#ifdef CONFIG_PROVE_LOCKING
3594
		+ sizeof(struct circular_queue)
3595
#endif
M
Ming Lei 已提交
3596
		) / 1024
3597
		);
I
Ingo Molnar 已提交
3598 3599 3600 3601 3602

	printk(" per task-struct memory footprint: %lu bytes\n",
		sizeof(struct held_lock) * MAX_LOCK_DEPTH);

#ifdef CONFIG_DEBUG_LOCKDEP
3603 3604 3605 3606 3607
	if (lockdep_init_error) {
		printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
		printk("Call stack leading to lockdep invocation was:\n");
		print_stack_trace(&lockdep_init_trace, 0);
	}
I
Ingo Molnar 已提交
3608 3609 3610 3611 3612
#endif
}

static void
print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3613
		     const void *mem_to, struct held_lock *hlock)
I
Ingo Molnar 已提交
3614 3615 3616 3617 3618 3619 3620 3621 3622 3623
{
	if (!debug_locks_off())
		return;
	if (debug_locks_silent)
		return;

	printk("\n=========================\n");
	printk(  "[ BUG: held lock freed! ]\n");
	printk(  "-------------------------\n");
	printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3624
		curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3625
	print_lock(hlock);
I
Ingo Molnar 已提交
3626 3627 3628 3629 3630 3631
	lockdep_print_held_locks(curr);

	printk("\nstack backtrace:\n");
	dump_stack();
}

O
Oleg Nesterov 已提交
3632 3633 3634 3635 3636 3637 3638
static inline int not_in_range(const void* mem_from, unsigned long mem_len,
				const void* lock_from, unsigned long lock_len)
{
	return lock_from + lock_len <= mem_from ||
		mem_from + mem_len <= lock_from;
}

I
Ingo Molnar 已提交
3639 3640 3641 3642 3643 3644 3645 3646 3647 3648 3649 3650 3651 3652 3653 3654 3655 3656 3657
/*
 * Called when kernel memory is freed (or unmapped), or if a lock
 * is destroyed or reinitialized - this code checks whether there is
 * any held lock in the memory range of <from> to <to>:
 */
void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
{
	struct task_struct *curr = current;
	struct held_lock *hlock;
	unsigned long flags;
	int i;

	if (unlikely(!debug_locks))
		return;

	local_irq_save(flags);
	for (i = 0; i < curr->lockdep_depth; i++) {
		hlock = curr->held_locks + i;

O
Oleg Nesterov 已提交
3658 3659
		if (not_in_range(mem_from, mem_len, hlock->instance,
					sizeof(*hlock->instance)))
I
Ingo Molnar 已提交
3660 3661
			continue;

O
Oleg Nesterov 已提交
3662
		print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
I
Ingo Molnar 已提交
3663 3664 3665 3666
		break;
	}
	local_irq_restore(flags);
}
3667
EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
I
Ingo Molnar 已提交
3668 3669 3670 3671 3672 3673 3674 3675 3676 3677 3678 3679

static void print_held_locks_bug(struct task_struct *curr)
{
	if (!debug_locks_off())
		return;
	if (debug_locks_silent)
		return;

	printk("\n=====================================\n");
	printk(  "[ BUG: lock held at task exit time! ]\n");
	printk(  "-------------------------------------\n");
	printk("%s/%d is exiting with locks still held!\n",
3680
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
3681 3682 3683 3684 3685 3686 3687 3688 3689 3690 3691 3692 3693 3694 3695 3696 3697 3698
	lockdep_print_held_locks(curr);

	printk("\nstack backtrace:\n");
	dump_stack();
}

void debug_check_no_locks_held(struct task_struct *task)
{
	if (unlikely(task->lockdep_depth > 0))
		print_held_locks_bug(task);
}

void debug_show_all_locks(void)
{
	struct task_struct *g, *p;
	int count = 10;
	int unlock = 1;

3699 3700 3701 3702
	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
I
Ingo Molnar 已提交
3703 3704 3705 3706 3707 3708 3709 3710 3711 3712 3713 3714 3715 3716 3717 3718 3719 3720 3721 3722
	printk("\nShowing all locks held in the system:\n");

	/*
	 * Here we try to get the tasklist_lock as hard as possible,
	 * if not successful after 2 seconds we ignore it (but keep
	 * trying). This is to enable a debug printout even if a
	 * tasklist_lock-holding task deadlocks or crashes.
	 */
retry:
	if (!read_trylock(&tasklist_lock)) {
		if (count == 10)
			printk("hm, tasklist_lock locked, retrying... ");
		if (count) {
			count--;
			printk(" #%d", 10-count);
			mdelay(200);
			goto retry;
		}
		printk(" ignoring it.\n");
		unlock = 0;
3723 3724 3725
	} else {
		if (count != 10)
			printk(KERN_CONT " locked it.\n");
I
Ingo Molnar 已提交
3726 3727 3728
	}

	do_each_thread(g, p) {
I
Ingo Molnar 已提交
3729 3730 3731 3732 3733 3734 3735
		/*
		 * It's not reliable to print a task's held locks
		 * if it's not sleeping (or if it's not the current
		 * task):
		 */
		if (p->state == TASK_RUNNING && p != current)
			continue;
I
Ingo Molnar 已提交
3736 3737 3738 3739 3740 3741 3742 3743 3744 3745 3746 3747 3748 3749 3750
		if (p->lockdep_depth)
			lockdep_print_held_locks(p);
		if (!unlock)
			if (read_trylock(&tasklist_lock))
				unlock = 1;
	} while_each_thread(g, p);

	printk("\n");
	printk("=============================================\n\n");

	if (unlock)
		read_unlock(&tasklist_lock);
}
EXPORT_SYMBOL_GPL(debug_show_all_locks);

3751 3752 3753 3754 3755
/*
 * Careful: only use this function if you are sure that
 * the task cannot run in parallel!
 */
void __debug_show_held_locks(struct task_struct *task)
I
Ingo Molnar 已提交
3756
{
3757 3758 3759 3760
	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
I
Ingo Molnar 已提交
3761 3762
	lockdep_print_held_locks(task);
}
3763 3764 3765 3766 3767 3768
EXPORT_SYMBOL_GPL(__debug_show_held_locks);

void debug_show_held_locks(struct task_struct *task)
{
		__debug_show_held_locks(task);
}
I
Ingo Molnar 已提交
3769
EXPORT_SYMBOL_GPL(debug_show_held_locks);
P
Peter Zijlstra 已提交
3770 3771 3772 3773 3774 3775 3776 3777 3778 3779 3780 3781 3782 3783 3784 3785

void lockdep_sys_exit(void)
{
	struct task_struct *curr = current;

	if (unlikely(curr->lockdep_depth)) {
		if (!debug_locks_off())
			return;
		printk("\n================================================\n");
		printk(  "[ BUG: lock held when returning to user space! ]\n");
		printk(  "------------------------------------------------\n");
		printk("%s/%d is leaving the kernel with locks still held!\n",
				curr->comm, curr->pid);
		lockdep_print_held_locks(curr);
	}
}
3786 3787 3788 3789 3790 3791 3792

void lockdep_rcu_dereference(const char *file, const int line)
{
	struct task_struct *curr = current;

	if (!debug_locks_off())
		return;
3793 3794 3795
	printk("\n===================================================\n");
	printk(  "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
	printk(  "---------------------------------------------------\n");
3796 3797 3798
	printk("%s:%d invoked rcu_dereference_check() without protection!\n",
			file, line);
	printk("\nother info that might help us debug this:\n\n");
3799
	printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
3800 3801 3802 3803 3804
	lockdep_print_held_locks(curr);
	printk("\nstack backtrace:\n");
	dump_stack();
}
EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);