lockdep.c 86.9 KB
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/*
 * kernel/lockdep.c
 *
 * Runtime locking correctness validator
 *
 * Started by Ingo Molnar:
 *
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 *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
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 *
 * 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.
 */
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#define DISABLE_BRANCH_PROFILING
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#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>
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#include <linux/utsname.h>
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#include <linux/hash.h>
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#include <linux/ftrace.h>
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#include <linux/stringify.h>
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#include <linux/bitops.h>
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#include <asm/sections.h>

#include "lockdep_internals.h"

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#define CREATE_TRACE_POINTS
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#include <trace/events/lockdep.h>
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#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

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/*
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 * lockdep_lock: protects the lockdep graph, the hashes and the
 *               class/list/hash allocators.
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 *
 * This is one of the rare exceptions where it's justified
 * to use a raw spinlock - we really dont want the spinlock
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 * code to recurse back into the lockdep code...
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 */
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static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;

static int graph_lock(void)
{
	__raw_spin_lock(&lockdep_lock);
	/*
	 * 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) {
		__raw_spin_unlock(&lockdep_lock);
		return 0;
	}
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	/* prevent any recursions within lockdep from causing deadlocks */
	current->lockdep_recursion++;
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	return 1;
}

static inline int graph_unlock(void)
{
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	if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
		return DEBUG_LOCKS_WARN_ON(1);

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	current->lockdep_recursion--;
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	__raw_spin_unlock(&lockdep_lock);
	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();

	__raw_spin_unlock(&lockdep_lock);

	return ret;
}
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static int lockdep_initialized;

unsigned long nr_list_entries;
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struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
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/*
 * 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];

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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;
}

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#ifdef CONFIG_LOCK_STAT
static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);

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static int lock_point(unsigned long points[], unsigned long ip)
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{
	int i;

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	for (i = 0; i < LOCKSTAT_POINTS; i++) {
		if (points[i] == 0) {
			points[i] = ip;
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			break;
		}
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		if (points[i] == ip)
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			break;
	}

	return i;
}

static void lock_time_inc(struct lock_time *lt, s64 time)
{
	if (time > lt->max)
		lt->max = time;

	if (time < lt->min || !lt->min)
		lt->min = time;

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

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static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
{
	dst->min += src->min;
	dst->max += src->max;
	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 =
			&per_cpu(lock_stats, cpu)[class - lock_classes];

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

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

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

	return stats;
}

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

	for_each_possible_cpu(cpu) {
		struct lock_class_stats *cpu_stats =
			&per_cpu(lock_stats, cpu)[class - lock_classes];

		memset(cpu_stats, 0, sizeof(struct lock_class_stats));
	}
	memset(class->contention_point, 0, sizeof(class->contention_point));
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	memset(class->contending_point, 0, sizeof(class->contending_point));
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}

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static struct lock_class_stats *get_lock_stats(struct lock_class *class)
{
	return &get_cpu_var(lock_stats)[class - lock_classes];
}

static void put_lock_stats(struct lock_class_stats *stats)
{
	put_cpu_var(lock_stats);
}

static void lock_release_holdtime(struct held_lock *hlock)
{
	struct lock_class_stats *stats;
	s64 holdtime;

	if (!lock_stat)
		return;

	holdtime = sched_clock() - hlock->holdtime_stamp;

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	stats = get_lock_stats(hlock_class(hlock));
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	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

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/*
 * 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)
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#define __classhashfn(key)	hash_long((unsigned long)key, CLASSHASH_BITS)
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#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)
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#define __chainhashfn(chain)	hash_long(chain, CHAINHASH_BITS)
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#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) \
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	(((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
	((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
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	(key2))

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void lockdep_off(void)
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{
	current->lockdep_recursion++;
}
EXPORT_SYMBOL(lockdep_off);

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void lockdep_on(void)
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{
	current->lockdep_recursion--;
}
EXPORT_SYMBOL(lockdep_on);

/*
 * Debugging switches:
 */

#define VERBOSE			0
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#define VERY_VERBOSE		0
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#if VERBOSE
# define HARDIRQ_VERBOSE	1
# define SOFTIRQ_VERBOSE	1
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# define RECLAIM_VERBOSE	1
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#else
# define HARDIRQ_VERBOSE	0
# define SOFTIRQ_VERBOSE	0
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# define RECLAIM_VERBOSE	0
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#endif

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#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE || RECLAIM_VERBOSE
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/*
 * Quick filtering for interesting events:
 */
static int class_filter(struct lock_class *class)
{
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#if 0
	/* Example */
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	if (class->name_version == 1 &&
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			!strcmp(class->name, "lockname"))
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		return 1;
	if (class->name_version == 1 &&
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			!strcmp(class->name, "&struct->lockfield"))
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		return 1;
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#endif
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	/* Filter everything else. 1 would be to allow everything else */
	return 0;
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}
#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
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 * addresses. Protected by the graph_lock.
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 */
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;

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	trace->skip = 3;

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	save_stack_trace(trace);
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	trace->max_entries = trace->nr_entries;

	nr_stack_trace_entries += trace->nr_entries;

	if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
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		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();

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		return 0;
	}

	return 1;
}

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

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static unsigned int lockdep_dependency_gen_id;

static bool lockdep_dependency_visit(struct lock_class *source,
				     unsigned int depth)
{
	if (!depth)
		lockdep_dependency_gen_id++;
	if (source->dep_gen_id == lockdep_dependency_gen_id)
		return true;
	source->dep_gen_id = lockdep_dependency_gen_id;
	return false;
}

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#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;
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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,
};
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/*
 * Various lockdep statistics:
 */
atomic_t chain_lookup_hits;
atomic_t chain_lookup_misses;
atomic_t hardirqs_on_events;
atomic_t hardirqs_off_events;
atomic_t redundant_hardirqs_on;
atomic_t redundant_hardirqs_off;
atomic_t softirqs_on_events;
atomic_t softirqs_off_events;
atomic_t redundant_softirqs_on;
atomic_t redundant_softirqs_off;
atomic_t nr_unused_locks;
atomic_t nr_cyclic_checks;
atomic_t nr_cyclic_check_recursions;
atomic_t nr_find_usage_forwards_checks;
atomic_t nr_find_usage_forwards_recursions;
atomic_t nr_find_usage_backwards_checks;
atomic_t nr_find_usage_backwards_recursions;
#endif

/*
 * Locking printouts:
 */

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#define __USAGE(__STATE)						\
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	[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",
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static const char *usage_str[] =
{
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#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
#include "lockdep_states.h"
#undef LOCKDEP_STATE
	[LOCK_USED] = "INITIAL USE",
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};

const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
{
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	return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
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}

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static inline unsigned long lock_flag(enum lock_usage_bit bit)
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{
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	return 1UL << bit;
}
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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 = '?';
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	}

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	return c;
}
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void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
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{
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	int i = 0;
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#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';
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}

static void print_lock_name(struct lock_class *class)
{
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	char str[KSYM_NAME_LEN], usage[LOCK_USAGE_CHARS];
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	const char *name;

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	get_usage_chars(class, usage);
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	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);
	}
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	printk("){%s}", usage);
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}

static void print_lockdep_cache(struct lockdep_map *lock)
{
	const char *name;
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	char str[KSYM_NAME_LEN];
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	name = lock->name;
	if (!name)
		name = __get_key_name(lock->key->subkeys, str);

	printk("%s", name);
}

static void print_lock(struct held_lock *hlock)
{
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	print_lock_name(hlock_class(hlock));
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	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) {
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		printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
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		return;
	}
	printk("%d lock%s held by %s/%d:\n",
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		depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
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	for (i = 0; i < depth; i++) {
		printk(" #%d: ", i);
		print_lock(curr->held_locks + i);
	}
}

static void print_lock_class_header(struct lock_class *class, int depth)
{
	int bit;

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	printk("%*s->", depth, "");
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	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;

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

/*
 * printk all lock dependencies starting at <entry>:
 */
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static void __used
print_lock_dependencies(struct lock_class *class, int depth)
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{
	struct lock_list *entry;

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	if (lockdep_dependency_visit(class, depth))
		return;

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	if (DEBUG_LOCKS_WARN_ON(depth >= 20))
		return;

	print_lock_class_header(class, depth);

	list_for_each_entry(entry, &class->locks_after, entry) {
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		if (DEBUG_LOCKS_WARN_ON(!entry->class))
			return;

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		print_lock_dependencies(entry->class, depth + 1);

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

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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;
}

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/*
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 * Is this the address of a static object:
I
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623
 */
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static int static_obj(void *obj)
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625
{
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	unsigned long start = (unsigned long) &_stext,
		      end   = (unsigned long) &_end,
		      addr  = (unsigned long) obj;
#ifdef CONFIG_SMP
	int i;
#endif

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633
	/*
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	 * static variable?
I
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635
	 */
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636 637
	if ((addr >= start) && (addr < end))
		return 1;
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638

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639
#ifdef CONFIG_SMP
I
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640
	/*
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	 * percpu var?
I
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642
	 */
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	for_each_possible_cpu(i) {
		start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
		end   = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
					+ per_cpu_offset(i);
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647

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648 649 650
		if ((addr >= start) && (addr < end))
			return 1;
	}
651
#endif
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	/*
	 * module var?
	 */
	return is_module_address(addr);
657 658
}

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659
/*
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 * To make lock name printouts unique, we calculate a unique
 * class->name_version generation counter:
I
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 */
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663
static int count_matching_names(struct lock_class *new_class)
I
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664
{
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665 666
	struct lock_class *class;
	int count = 0;
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667

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	if (!new_class->name)
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669 670
		return 0;

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671 672 673 674 675 676
	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);
	}
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	return count + 1;
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}

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/*
 * 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)
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{
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	struct lockdep_subclass_key *key;
	struct list_head *hash_head;
	struct lock_class *class;
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#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;
702
		save_stack_trace(&lockdep_init_trace);
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	}
#endif
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	/*
	 * 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;
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712

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713 714 715 716 717 718
	/*
	 * 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.
	 */
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	BUILD_BUG_ON(sizeof(struct lock_class_key) >
			sizeof(struct lockdep_map));
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721

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	key = lock->key->subkeys + subclass;
723

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724
	hash_head = classhashentry(key);
725

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726 727 728 729
	/*
	 * We can walk the hash lockfree, because the hash only
	 * grows, and we are careful when adding entries to the end:
	 */
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730 731 732
	list_for_each_entry(class, hash_head, hash_entry) {
		if (class->key == key) {
			WARN_ON_ONCE(class->name != lock->name);
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733
			return class;
P
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734 735
		}
	}
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736

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737
	return NULL;
I
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738 739 740
}

/*
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741 742 743
 * 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
744
 */
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static inline struct lock_class *
register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
I
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747
{
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748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797
	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");
798
		dump_stack();
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799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814
		return NULL;
	}
	class = lock_classes + nr_lock_classes++;
	debug_atomic_inc(&nr_unused_locks);
	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);
815 816 817 818
	/*
	 * Add it to the global list of classes:
	 */
	list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
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Peter Zijlstra 已提交
819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861

	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");
862
		dump_stack();
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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
		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;

886 887
	entry->class = this;
	entry->distance = distance;
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888 889 890 891 892 893 894 895 896 897 898 899
	/*
	 * 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;
}

900
unsigned long bfs_accessed[BITS_TO_LONGS(MAX_LOCKDEP_ENTRIES)];
901
static struct circular_queue  lock_cq;
902

903 904 905 906 907 908
static int __search_shortest_path(struct lock_list *source_entry,
				struct lock_class *target,
				struct lock_list **target_entry,
				int forward)
{
	struct lock_list *entry;
909
	struct list_head *head;
910 911 912 913 914 915 916 917 918
	struct circular_queue *cq = &lock_cq;
	int ret = 1;

	if (source_entry->class == target) {
		*target_entry = source_entry;
		ret = 0;
		goto exit;
	}

919 920 921 922 923 924 925 926 927
	if (forward)
		head = &source_entry->class->locks_after;
	else
		head = &source_entry->class->locks_before;

	if (list_empty(head))
		goto exit;

	__cq_init(cq);
928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980
	__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)) {
				mark_lock_accessed(entry, lock);
				if (entry->class == target) {
					*target_entry = entry;
					ret = 0;
					goto exit;
				}

				if (__cq_enqueue(cq, (unsigned long)entry)) {
					ret = -1;
					goto exit;
				}
			}
		}
	}
exit:
	return ret;
}

static inline int __search_forward_shortest_path(struct lock_list *src_entry,
				struct lock_class *target,
				struct lock_list **target_entry)
{
	return __search_shortest_path(src_entry, target, target_entry, 1);

}

static inline int __search_backward_shortest_path(struct lock_list *src_entry,
				struct lock_class *target,
				struct lock_list **target_entry)
{
	return __search_shortest_path(src_entry, target, target_entry, 0);

}

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Peter Zijlstra 已提交
981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017
/*
 * Recursive, forwards-direction lock-dependency checking, used for
 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
 * checking.
 *
 * (to keep the stackframe of the recursive functions small we
 *  use these global variables, and we also mark various helper
 *  functions as noinline.)
 */
static struct held_lock *check_source, *check_target;

/*
 * Print a dependency chain entry (this is only done when a deadlock
 * has been detected):
 */
static noinline int
print_circular_bug_entry(struct lock_list *target, unsigned int depth)
{
	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
print_circular_bug_header(struct lock_list *entry, unsigned int depth)
{
	struct task_struct *curr = current;

1018
	if (debug_locks_silent)
P
Peter Zijlstra 已提交
1019 1020 1021 1022 1023 1024 1025
		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",
1026
		curr->comm, task_pid_nr(curr));
P
Peter Zijlstra 已提交
1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037
	print_lock(check_source);
	printk("\nbut task is already holding lock:\n");
	print_lock(check_target);
	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;
}

1038
static noinline int print_circular_bug(void)
P
Peter Zijlstra 已提交
1039 1040 1041
{
	struct task_struct *curr = current;
	struct lock_list this;
1042 1043 1044 1045
	struct lock_list *target;
	struct lock_list *parent;
	int result;
	unsigned long depth;
P
Peter Zijlstra 已提交
1046

1047
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
P
Peter Zijlstra 已提交
1048 1049
		return 0;

D
Dave Jones 已提交
1050
	this.class = hlock_class(check_source);
1051
	this.parent = NULL;
P
Peter Zijlstra 已提交
1052 1053 1054
	if (!save_trace(&this.trace))
		return 0;

1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073
	result = __search_forward_shortest_path(&this,
						hlock_class(check_target),
						&target);
	if (result) {
		printk("\n%s:search shortest path failed:%d\n", __func__,
			result);
		return 0;
	}

	depth = get_lock_depth(target);

	print_circular_bug_header(target, depth);

	parent = get_lock_parent(target);

	while (parent) {
		print_circular_bug_entry(parent, --depth);
		parent = get_lock_parent(parent);
	}
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1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095

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

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

	return 0;
}

#define RECURSION_LIMIT 40

static int noinline print_infinite_recursion_bug(void)
{
	if (!debug_locks_off_graph_unlock())
		return 0;

	WARN_ON(1);

	return 0;
}

1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156
unsigned long __lockdep_count_forward_deps(struct lock_class *class,
					   unsigned int depth)
{
	struct lock_list *entry;
	unsigned long ret = 1;

	if (lockdep_dependency_visit(class, depth))
		return 0;

	/*
	 * Recurse this class's dependency list:
	 */
	list_for_each_entry(entry, &class->locks_after, entry)
		ret += __lockdep_count_forward_deps(entry->class, depth + 1);

	return ret;
}

unsigned long lockdep_count_forward_deps(struct lock_class *class)
{
	unsigned long ret, flags;

	local_irq_save(flags);
	__raw_spin_lock(&lockdep_lock);
	ret = __lockdep_count_forward_deps(class, 0);
	__raw_spin_unlock(&lockdep_lock);
	local_irq_restore(flags);

	return ret;
}

unsigned long __lockdep_count_backward_deps(struct lock_class *class,
					    unsigned int depth)
{
	struct lock_list *entry;
	unsigned long ret = 1;

	if (lockdep_dependency_visit(class, depth))
		return 0;
	/*
	 * Recurse this class's dependency list:
	 */
	list_for_each_entry(entry, &class->locks_before, entry)
		ret += __lockdep_count_backward_deps(entry->class, depth + 1);

	return ret;
}

unsigned long lockdep_count_backward_deps(struct lock_class *class)
{
	unsigned long ret, flags;

	local_irq_save(flags);
	__raw_spin_lock(&lockdep_lock);
	ret = __lockdep_count_backward_deps(class, 0);
	__raw_spin_unlock(&lockdep_lock);
	local_irq_restore(flags);

	return ret;
}

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1157 1158 1159 1160 1161 1162 1163 1164 1165
/*
 * 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
check_noncircular(struct lock_class *source, unsigned int depth)
{
	struct lock_list *entry;

1166 1167 1168
	if (lockdep_dependency_visit(source, depth))
		return 1;

P
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1169 1170
	debug_atomic_inc(&nr_cyclic_check_recursions);
	if (depth > max_recursion_depth)
I
Ingo Molnar 已提交
1171
		max_recursion_depth = depth;
1172
	if (depth >= RECURSION_LIMIT)
I
Ingo Molnar 已提交
1173 1174 1175 1176 1177
		return print_infinite_recursion_bug();
	/*
	 * Check this lock's dependency list:
	 */
	list_for_each_entry(entry, &source->locks_after, entry) {
D
Dave Jones 已提交
1178
		if (entry->class == hlock_class(check_target))
1179
			return 2;
I
Ingo Molnar 已提交
1180
		debug_atomic_inc(&nr_cyclic_checks);
1181 1182
		if (check_noncircular(entry->class, depth+1) == 2)
			return 2;
I
Ingo Molnar 已提交
1183 1184 1185 1186
	}
	return 1;
}

1187

1188
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
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Ingo Molnar 已提交
1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212
/*
 * 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.
 */
static enum lock_usage_bit find_usage_bit;
static struct lock_class *forwards_match, *backwards_match;

/*
 * Find a node in the forwards-direction dependency sub-graph starting
 * at <source> that matches <find_usage_bit>.
 *
 * Return 2 if such a node exists in the subgraph, and put that node
 * into <forwards_match>.
 *
 * Return 1 otherwise and keep <forwards_match> unchanged.
 * Return 0 on error.
 */
static noinline int
find_usage_forwards(struct lock_class *source, unsigned int depth)
{
	struct lock_list *entry;
	int ret;

1213 1214 1215
	if (lockdep_dependency_visit(source, depth))
		return 1;

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Ingo Molnar 已提交
1216 1217
	if (depth > max_recursion_depth)
		max_recursion_depth = depth;
1218
	if (depth >= RECURSION_LIMIT)
I
Ingo Molnar 已提交
1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248
		return print_infinite_recursion_bug();

	debug_atomic_inc(&nr_find_usage_forwards_checks);
	if (source->usage_mask & (1 << find_usage_bit)) {
		forwards_match = source;
		return 2;
	}

	/*
	 * Check this lock's dependency list:
	 */
	list_for_each_entry(entry, &source->locks_after, entry) {
		debug_atomic_inc(&nr_find_usage_forwards_recursions);
		ret = find_usage_forwards(entry->class, depth+1);
		if (ret == 2 || ret == 0)
			return ret;
	}
	return 1;
}

/*
 * Find a node in the backwards-direction dependency sub-graph starting
 * at <source> that matches <find_usage_bit>.
 *
 * Return 2 if such a node exists in the subgraph, and put that node
 * into <backwards_match>.
 *
 * Return 1 otherwise and keep <backwards_match> unchanged.
 * Return 0 on error.
 */
1249
static noinline int
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1250 1251 1252 1253 1254
find_usage_backwards(struct lock_class *source, unsigned int depth)
{
	struct lock_list *entry;
	int ret;

1255 1256 1257
	if (lockdep_dependency_visit(source, depth))
		return 1;

1258 1259 1260
	if (!__raw_spin_is_locked(&lockdep_lock))
		return DEBUG_LOCKS_WARN_ON(1);

I
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1261 1262
	if (depth > max_recursion_depth)
		max_recursion_depth = depth;
1263
	if (depth >= RECURSION_LIMIT)
I
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1264 1265 1266 1267 1268 1269 1270 1271
		return print_infinite_recursion_bug();

	debug_atomic_inc(&nr_find_usage_backwards_checks);
	if (source->usage_mask & (1 << find_usage_bit)) {
		backwards_match = source;
		return 2;
	}

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1272 1273 1274 1275 1276
	if (!source && debug_locks_off_graph_unlock()) {
		WARN_ON(1);
		return 0;
	}

I
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1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296
	/*
	 * Check this lock's dependency list:
	 */
	list_for_each_entry(entry, &source->locks_before, entry) {
		debug_atomic_inc(&nr_find_usage_backwards_recursions);
		ret = find_usage_backwards(entry->class, depth+1);
		if (ret == 2 || ret == 0)
			return ret;
	}
	return 1;
}

static int
print_bad_irq_dependency(struct task_struct *curr,
			 struct held_lock *prev,
			 struct held_lock *next,
			 enum lock_usage_bit bit1,
			 enum lock_usage_bit bit2,
			 const char *irqclass)
{
1297
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
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1298 1299 1300 1301 1302
		return 0;

	printk("\n======================================================\n");
	printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
		irqclass, irqclass);
1303
	print_kernel_version();
I
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1304 1305
	printk(  "------------------------------------------------------\n");
	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1306
		curr->comm, task_pid_nr(curr),
I
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1307 1308 1309 1310 1311 1312 1313 1314 1315
		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");
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	print_lock_name(hlock_class(prev));
I
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1317
	printk(" ->");
D
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	print_lock_name(hlock_class(next));
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1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358
	printk("\n");

	printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
		irqclass);
	print_lock_name(backwards_match);
	printk("\n... which became %s-irq-safe at:\n", irqclass);

	print_stack_trace(backwards_match->usage_traces + bit1, 1);

	printk("\nto a %s-irq-unsafe lock:\n", irqclass);
	print_lock_name(forwards_match);
	printk("\n... which became %s-irq-unsafe at:\n", irqclass);
	printk("...");

	print_stack_trace(forwards_match->usage_traces + bit2, 1);

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

	printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
	print_lock_dependencies(backwards_match, 0);

	printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
	print_lock_dependencies(forwards_match, 0);

	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;

	find_usage_bit = bit_backwards;
	/* fills in <backwards_match> */
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	ret = find_usage_backwards(hlock_class(prev), 0);
I
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1360 1361 1362 1363
	if (!ret || ret == 1)
		return ret;

	find_usage_bit = bit_forwards;
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	ret = find_usage_forwards(hlock_class(next), 0);
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	if (!ret || ret == 1)
		return ret;
	/* ret == 2 */
	return print_bad_irq_dependency(curr, prev, next,
			bit_backwards, bit_forwards, irqclass);
}

1372 1373
static const char *state_names[] = {
#define LOCKDEP_STATE(__STATE) \
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1374
	__stringify(__STATE),
1375 1376 1377 1378 1379 1380
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

static const char *state_rnames[] = {
#define LOCKDEP_STATE(__STATE) \
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1381
	__stringify(__STATE)"-READ",
1382 1383 1384 1385 1386
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

static inline const char *state_name(enum lock_usage_bit bit)
P
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1387
{
1388 1389
	return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
}
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1390

1391 1392
static int exclusive_bit(int new_bit)
{
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1393
	/*
1394 1395 1396 1397 1398 1399 1400 1401
	 * USED_IN
	 * USED_IN_READ
	 * ENABLED
	 * ENABLED_READ
	 *
	 * bit 0 - write/read
	 * bit 1 - used_in/enabled
	 * bit 2+  state
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1402
	 */
1403 1404 1405

	int state = new_bit & ~3;
	int dir = new_bit & 2;
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1406 1407

	/*
1408
	 * keep state, bit flip the direction and strip read.
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Peter Zijlstra 已提交
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	 */
1410 1411 1412 1413 1414 1415
	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
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1416
	/*
1417 1418
	 * Prove that the new dependency does not connect a hardirq-safe
	 * lock with a hardirq-unsafe lock - to achieve this we search
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1419 1420 1421
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
1422 1423
	if (!check_usage(curr, prev, next, bit,
			   exclusive_bit(bit), state_name(bit)))
P
Peter Zijlstra 已提交
1424 1425
		return 0;

1426 1427
	bit++; /* _READ */

1428
	/*
1429 1430
	 * Prove that the new dependency does not connect a hardirq-safe-read
	 * lock with a hardirq-unsafe lock - to achieve this we search
1431 1432 1433
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
1434 1435
	if (!check_usage(curr, prev, next, bit,
			   exclusive_bit(bit), state_name(bit)))
1436 1437
		return 0;

1438 1439 1440 1441 1442 1443 1444 1445 1446
	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))	\
1447
		return 0;
1448 1449
#include "lockdep_states.h"
#undef LOCKDEP_STATE
1450

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1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479
	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
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1480 1481 1482 1483 1484 1485
#endif

static int
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
		   struct held_lock *next)
{
1486
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
1487 1488 1489 1490
		return 0;

	printk("\n=============================================\n");
	printk(  "[ INFO: possible recursive locking detected ]\n");
1491
	print_kernel_version();
I
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1492 1493
	printk(  "---------------------------------------------\n");
	printk("%s/%d is trying to acquire lock:\n",
1494
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520
	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
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1521
	struct held_lock *nest = NULL;
I
Ingo Molnar 已提交
1522 1523 1524 1525
	int i;

	for (i = 0; i < curr->lockdep_depth; i++) {
		prev = curr->held_locks + i;
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1526 1527 1528 1529

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

D
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1530
		if (hlock_class(prev) != hlock_class(next))
I
Ingo Molnar 已提交
1531
			continue;
P
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1532

I
Ingo Molnar 已提交
1533 1534
		/*
		 * Allow read-after-read recursion of the same
1535
		 * lock class (i.e. read_lock(lock)+read_lock(lock)):
I
Ingo Molnar 已提交
1536
		 */
1537
		if ((read == 2) && prev->read)
I
Ingo Molnar 已提交
1538
			return 2;
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1539 1540 1541 1542 1543 1544 1545 1546

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

I
Ingo Molnar 已提交
1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575
		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,
1576
	       struct held_lock *next, int distance)
I
Ingo Molnar 已提交
1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591
{
	struct lock_list *entry;
	int ret;

	/*
	 * 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:
	 */
	check_source = next;
	check_target = prev;
1592

1593 1594 1595
	if (check_noncircular(hlock_class(next), 0) == 2)
		return print_circular_bug();

P
Peter Zijlstra 已提交
1596
	if (!check_prev_add_irq(curr, prev, next))
I
Ingo Molnar 已提交
1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616
		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
1617 1618
	list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
		if (entry->class == hlock_class(next)) {
1619 1620
			if (distance == 1)
				entry->distance = 1;
I
Ingo Molnar 已提交
1621
			return 2;
1622
		}
I
Ingo Molnar 已提交
1623 1624 1625 1626 1627 1628
	}

	/*
	 * Ok, all validations passed, add the new lock
	 * to the previous lock's dependency list:
	 */
D
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1629 1630 1631
	ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
			       &hlock_class(prev)->locks_after,
			       next->acquire_ip, distance);
1632

I
Ingo Molnar 已提交
1633 1634
	if (!ret)
		return 0;
1635

D
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1636 1637 1638
	ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
			       &hlock_class(next)->locks_before,
			       next->acquire_ip, distance);
1639 1640
	if (!ret)
		return 0;
I
Ingo Molnar 已提交
1641 1642

	/*
P
Peter Zijlstra 已提交
1643 1644
	 * Debugging printouts:
	 */
D
Dave Jones 已提交
1645
	if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
P
Peter Zijlstra 已提交
1646 1647
		graph_unlock();
		printk("\n new dependency: ");
D
Dave Jones 已提交
1648
		print_lock_name(hlock_class(prev));
P
Peter Zijlstra 已提交
1649
		printk(" => ");
D
Dave Jones 已提交
1650
		print_lock_name(hlock_class(next));
P
Peter Zijlstra 已提交
1651
		printk("\n");
I
Ingo Molnar 已提交
1652
		dump_stack();
P
Peter Zijlstra 已提交
1653
		return graph_lock();
I
Ingo Molnar 已提交
1654
	}
P
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1655 1656
	return 1;
}
I
Ingo Molnar 已提交
1657

P
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1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668
/*
 * 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;
1669

I
Ingo Molnar 已提交
1670
	/*
P
Peter Zijlstra 已提交
1671 1672 1673
	 * Debugging checks.
	 *
	 * Depth must not be zero for a non-head lock:
I
Ingo Molnar 已提交
1674
	 */
P
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1675 1676
	if (!depth)
		goto out_bug;
I
Ingo Molnar 已提交
1677
	/*
P
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1678 1679
	 * At least two relevant locks must exist for this
	 * to be a head:
I
Ingo Molnar 已提交
1680
	 */
P
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1681 1682 1683
	if (curr->held_locks[depth].irq_context !=
			curr->held_locks[depth-1].irq_context)
		goto out_bug;
1684

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1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702
	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;
1703
		}
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1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715
		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
1716
	}
P
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1717 1718 1719 1720
	return 1;
out_bug:
	if (!debug_locks_off_graph_unlock())
		return 0;
I
Ingo Molnar 已提交
1721

P
Peter Zijlstra 已提交
1722
	WARN_ON(1);
I
Ingo Molnar 已提交
1723

P
Peter Zijlstra 已提交
1724
	return 0;
I
Ingo Molnar 已提交
1725 1726
}

P
Peter Zijlstra 已提交
1727
unsigned long nr_lock_chains;
1728
struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1729
int nr_chain_hlocks;
1730 1731 1732 1733 1734 1735
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
1736

I
Ingo Molnar 已提交
1737 1738
/*
 * Look up a dependency chain. If the key is not present yet then
1739 1740 1741
 * 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
1742
 */
1743 1744 1745
static inline int lookup_chain_cache(struct task_struct *curr,
				     struct held_lock *hlock,
				     u64 chain_key)
I
Ingo Molnar 已提交
1746
{
D
Dave Jones 已提交
1747
	struct lock_class *class = hlock_class(hlock);
I
Ingo Molnar 已提交
1748 1749
	struct list_head *hash_head = chainhashentry(chain_key);
	struct lock_chain *chain;
1750
	struct held_lock *hlock_curr, *hlock_next;
1751
	int i, j, n, cn;
I
Ingo Molnar 已提交
1752

1753 1754
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return 0;
I
Ingo Molnar 已提交
1755 1756 1757 1758 1759 1760 1761 1762
	/*
	 * 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:
			debug_atomic_inc(&chain_lookup_hits);
1763
			if (very_verbose(class))
1764 1765 1766 1767
				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
1768 1769 1770
			return 0;
		}
	}
1771
	if (very_verbose(class))
1772 1773
		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
1774 1775 1776 1777
	/*
	 * Allocate a new chain entry from the static array, and add
	 * it to the hash:
	 */
1778 1779
	if (!graph_lock())
		return 0;
I
Ingo Molnar 已提交
1780 1781 1782 1783 1784
	/*
	 * 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) {
1785
			graph_unlock();
I
Ingo Molnar 已提交
1786 1787 1788 1789
			goto cache_hit;
		}
	}
	if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1790 1791 1792
		if (!debug_locks_off_graph_unlock())
			return 0;

I
Ingo Molnar 已提交
1793 1794
		printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
		printk("turning off the locking correctness validator.\n");
1795
		dump_stack();
I
Ingo Molnar 已提交
1796 1797 1798 1799
		return 0;
	}
	chain = lock_chains + nr_lock_chains++;
	chain->chain_key = chain_key;
1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810
	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;
1811 1812 1813 1814 1815 1816 1817 1818 1819
	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;
1820
		for (j = 0; j < chain->depth - 1; j++, i++) {
D
Dave Jones 已提交
1821
			int lock_id = curr->held_locks[i].class_idx - 1;
1822 1823 1824 1825
			chain_hlocks[chain->base + j] = lock_id;
		}
		chain_hlocks[chain->base + j] = class - lock_classes;
	}
I
Ingo Molnar 已提交
1826 1827
	list_add_tail_rcu(&chain->entry, hash_head);
	debug_atomic_inc(&chain_lookup_misses);
P
Peter Zijlstra 已提交
1828 1829 1830 1831 1832 1833
	inc_chains();

	return 1;
}

static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1834
		struct held_lock *hlock, int chain_head, u64 chain_key)
P
Peter Zijlstra 已提交
1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846
{
	/*
	 * 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) &&
1847
	    lookup_chain_cache(curr, hlock, chain_key)) {
P
Peter Zijlstra 已提交
1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882
		/*
		 * 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
1883 1884 1885

	return 1;
}
P
Peter Zijlstra 已提交
1886 1887 1888
#else
static inline int validate_chain(struct task_struct *curr,
	       	struct lockdep_map *lock, struct held_lock *hlock,
1889
		int chain_head, u64 chain_key)
P
Peter Zijlstra 已提交
1890 1891 1892
{
	return 1;
}
1893
#endif
I
Ingo Molnar 已提交
1894 1895 1896 1897 1898

/*
 * We are building curr_chain_key incrementally, so double-check
 * it from scratch, to make sure that it's done correctly:
 */
1899
static void check_chain_key(struct task_struct *curr)
I
Ingo Molnar 已提交
1900 1901 1902 1903 1904 1905 1906 1907 1908 1909
{
#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();
1910
			WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
I
Ingo Molnar 已提交
1911 1912 1913 1914 1915
				curr->lockdep_depth, i,
				(unsigned long long)chain_key,
				(unsigned long long)hlock->prev_chain_key);
			return;
		}
D
Dave Jones 已提交
1916
		id = hlock->class_idx - 1;
1917 1918 1919
		if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
			return;

I
Ingo Molnar 已提交
1920 1921 1922 1923 1924 1925 1926 1927
		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();
1928
		WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
I
Ingo Molnar 已提交
1929 1930 1931 1932 1933 1934 1935
			curr->lockdep_depth, i,
			(unsigned long long)chain_key,
			(unsigned long long)curr->curr_chain_key);
	}
#endif
}

P
Peter Zijlstra 已提交
1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951
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",
1952
		curr->comm, task_pid_nr(curr),
P
Peter Zijlstra 已提交
1953 1954 1955 1956 1957 1958 1959
		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
1960
	print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
P
Peter Zijlstra 已提交
1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978

	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
1979
	if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
P
Peter Zijlstra 已提交
1980 1981 1982 1983 1984 1985 1986
		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);

1987
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
I
Ingo Molnar 已提交
1988 1989 1990 1991 1992 1993 1994 1995 1996

/*
 * print irq inversion bug:
 */
static int
print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
			struct held_lock *this, int forwards,
			const char *irqclass)
{
1997
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
1998 1999 2000 2001
		return 0;

	printk("\n=========================================================\n");
	printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2002
	print_kernel_version();
I
Ingo Molnar 已提交
2003 2004
	printk(  "---------------------------------------------------------\n");
	printk("%s/%d just changed the state of lock:\n",
2005
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
2006 2007
	print_lock(this);
	if (forwards)
2008
		printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
I
Ingo Molnar 已提交
2009
	else
2010
		printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
I
Ingo Molnar 已提交
2011 2012 2013 2014 2015 2016 2017
	print_lock_name(other);
	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);

	printk("\nthe first lock's dependencies:\n");
D
Dave Jones 已提交
2018
	print_lock_dependencies(hlock_class(this), 0);
I
Ingo Molnar 已提交
2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040

	printk("\nthe second lock's dependencies:\n");
	print_lock_dependencies(other, 0);

	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;

	find_usage_bit = bit;
	/* fills in <forwards_match> */
D
Dave Jones 已提交
2041
	ret = find_usage_forwards(hlock_class(this), 0);
I
Ingo Molnar 已提交
2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059
	if (!ret || ret == 1)
		return ret;

	return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
}

/*
 * 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;

	find_usage_bit = bit;
	/* fills in <backwards_match> */
D
Dave Jones 已提交
2060
	ret = find_usage_backwards(hlock_class(this), 0);
I
Ingo Molnar 已提交
2061 2062 2063 2064 2065 2066
	if (!ret || ret == 1)
		return ret;

	return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
}

2067
void print_irqtrace_events(struct task_struct *curr)
I
Ingo Molnar 已提交
2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079
{
	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);
}

2080
static int HARDIRQ_verbose(struct lock_class *class)
I
Ingo Molnar 已提交
2081
{
P
Peter Zijlstra 已提交
2082 2083 2084
#if HARDIRQ_VERBOSE
	return class_filter(class);
#endif
I
Ingo Molnar 已提交
2085 2086 2087
	return 0;
}

2088
static int SOFTIRQ_verbose(struct lock_class *class)
I
Ingo Molnar 已提交
2089
{
P
Peter Zijlstra 已提交
2090 2091 2092 2093
#if SOFTIRQ_VERBOSE
	return class_filter(class);
#endif
	return 0;
I
Ingo Molnar 已提交
2094 2095
}

2096
static int RECLAIM_FS_verbose(struct lock_class *class)
2097 2098 2099 2100 2101 2102 2103
{
#if RECLAIM_VERBOSE
	return class_filter(class);
#endif
	return 0;
}

I
Ingo Molnar 已提交
2104 2105
#define STRICT_READ_CHECKS	1

2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118
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);
}

2119 2120 2121
typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
			     enum lock_usage_bit bit, const char *name);

2122
static int
2123 2124
mark_lock_irq(struct task_struct *curr, struct held_lock *this,
		enum lock_usage_bit new_bit)
2125
{
2126
	int excl_bit = exclusive_bit(new_bit);
2127
	int read = new_bit & 1;
2128 2129
	int dir = new_bit & 2;

2130 2131 2132 2133 2134 2135 2136
	/*
	 * 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.
	 */
2137 2138
	check_usage_f usage = dir ?
		check_usage_backwards : check_usage_forwards;
2139

2140 2141 2142 2143
	/*
	 * Validate that this particular lock does not have conflicting
	 * usage states.
	 */
2144 2145
	if (!valid_state(curr, this, new_bit, excl_bit))
		return 0;
2146

2147 2148 2149 2150 2151
	/*
	 * Validate that the lock dependencies don't have conflicting usage
	 * states.
	 */
	if ((!read || !dir || STRICT_READ_CHECKS) &&
2152
			!usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2153
		return 0;
2154

2155 2156 2157 2158 2159 2160 2161 2162
	/*
	 * Check for read in write conflicts
	 */
	if (!read) {
		if (!valid_state(curr, this, new_bit, excl_bit + 1))
			return 0;

		if (STRICT_READ_CHECKS &&
2163 2164
			!usage(curr, this, excl_bit + 1,
				state_name(new_bit + 1)))
2165 2166
			return 0;
	}
2167

2168
	if (state_verbose(new_bit, hlock_class(this)))
2169 2170 2171 2172 2173
		return 2;

	return 1;
}

2174
enum mark_type {
2175 2176 2177
#define LOCKDEP_STATE(__STATE)	__STATE,
#include "lockdep_states.h"
#undef LOCKDEP_STATE
2178 2179
};

I
Ingo Molnar 已提交
2180 2181 2182
/*
 * Mark all held locks with a usage bit:
 */
2183
static int
2184
mark_held_locks(struct task_struct *curr, enum mark_type mark)
I
Ingo Molnar 已提交
2185 2186 2187 2188 2189 2190 2191 2192
{
	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;

2193 2194 2195 2196 2197
		usage_bit = 2 + (mark << 2); /* ENABLED */
		if (hlock->read)
			usage_bit += 1; /* READ */

		BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2198

2199
		if (!mark_lock(curr, hlock, usage_bit))
I
Ingo Molnar 已提交
2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224
			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:
 */
2225
void trace_hardirqs_on_caller(unsigned long ip)
I
Ingo Molnar 已提交
2226 2227 2228
{
	struct task_struct *curr = current;

2229
	time_hardirqs_on(CALLER_ADDR0, ip);
2230

I
Ingo Molnar 已提交
2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251
	if (unlikely(!debug_locks || current->lockdep_recursion))
		return;

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

	if (unlikely(curr->hardirqs_enabled)) {
		debug_atomic_inc(&redundant_hardirqs_on);
		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:
	 */
2252
	if (!mark_held_locks(curr, HARDIRQ))
I
Ingo Molnar 已提交
2253 2254 2255 2256 2257 2258 2259
		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)
2260
		if (!mark_held_locks(curr, SOFTIRQ))
I
Ingo Molnar 已提交
2261 2262
			return;

P
Peter Zijlstra 已提交
2263 2264 2265 2266
	curr->hardirq_enable_ip = ip;
	curr->hardirq_enable_event = ++curr->irq_events;
	debug_atomic_inc(&hardirqs_on_events);
}
2267
EXPORT_SYMBOL(trace_hardirqs_on_caller);
P
Peter Zijlstra 已提交
2268

2269
void trace_hardirqs_on(void)
2270 2271 2272
{
	trace_hardirqs_on_caller(CALLER_ADDR0);
}
P
Peter Zijlstra 已提交
2273 2274 2275 2276 2277
EXPORT_SYMBOL(trace_hardirqs_on);

/*
 * Hardirqs were disabled:
 */
2278
void trace_hardirqs_off_caller(unsigned long ip)
P
Peter Zijlstra 已提交
2279 2280 2281
{
	struct task_struct *curr = current;

2282
	time_hardirqs_off(CALLER_ADDR0, ip);
2283

P
Peter Zijlstra 已提交
2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294
	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;
2295
		curr->hardirq_disable_ip = ip;
P
Peter Zijlstra 已提交
2296 2297 2298 2299 2300
		curr->hardirq_disable_event = ++curr->irq_events;
		debug_atomic_inc(&hardirqs_off_events);
	} else
		debug_atomic_inc(&redundant_hardirqs_off);
}
2301
EXPORT_SYMBOL(trace_hardirqs_off_caller);
P
Peter Zijlstra 已提交
2302

2303
void trace_hardirqs_off(void)
2304 2305 2306
{
	trace_hardirqs_off_caller(CALLER_ADDR0);
}
P
Peter Zijlstra 已提交
2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339
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) {
		debug_atomic_inc(&redundant_softirqs_on);
		return;
	}

	/*
	 * We'll do an OFF -> ON transition:
	 */
	curr->softirqs_enabled = 1;
	curr->softirq_enable_ip = ip;
	curr->softirq_enable_event = ++curr->irq_events;
	debug_atomic_inc(&softirqs_on_events);
	/*
	 * 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)
2340
		mark_held_locks(curr, SOFTIRQ);
P
Peter Zijlstra 已提交
2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368
}

/*
 * 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;
		debug_atomic_inc(&softirqs_off_events);
		DEBUG_LOCKS_WARN_ON(!softirq_count());
	} else
		debug_atomic_inc(&redundant_softirqs_off);
}

2369
static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387
{
	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;

2388
	if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2389 2390 2391 2392 2393
		return;

	mark_held_locks(curr, RECLAIM_FS);
}

2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410
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);
}

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2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438
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
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2439
					LOCK_ENABLED_HARDIRQ_READ))
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2440 2441 2442
				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
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2443
						LOCK_ENABLED_SOFTIRQ_READ))
P
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2444 2445 2446
					return 0;
		} else {
			if (!mark_lock(curr, hlock,
P
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2447
					LOCK_ENABLED_HARDIRQ))
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2448 2449 2450
				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
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2451
						LOCK_ENABLED_SOFTIRQ))
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2452 2453 2454 2455
					return 0;
		}
	}

2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471
	/*
	 * 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;
		}
	}

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2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496 2497
	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;
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2498 2499
}

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2500
#else
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2501

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static inline
int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
		enum lock_usage_bit new_bit)
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2505
{
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2506 2507 2508
	WARN_ON(1);
	return 1;
}
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2509

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2510 2511 2512 2513 2514
static inline int mark_irqflags(struct task_struct *curr,
		struct held_lock *hlock)
{
	return 1;
}
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2515

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2516 2517 2518 2519
static inline int separate_irq_context(struct task_struct *curr,
		struct held_lock *hlock)
{
	return 0;
I
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2520 2521
}

2522 2523 2524 2525
void lockdep_trace_alloc(gfp_t gfp_mask)
{
}

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2526
#endif
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2527 2528

/*
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2529
 * Mark a lock with a usage bit, and validate the state transition:
I
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2530
 */
2531
static int mark_lock(struct task_struct *curr, struct held_lock *this,
2532
			     enum lock_usage_bit new_bit)
I
Ingo Molnar 已提交
2533
{
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2534
	unsigned int new_mask = 1 << new_bit, ret = 1;
I
Ingo Molnar 已提交
2535 2536

	/*
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2537 2538
	 * If already set then do not dirty the cacheline,
	 * nor do any checks:
I
Ingo Molnar 已提交
2539
	 */
D
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2540
	if (likely(hlock_class(this)->usage_mask & new_mask))
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2541 2542 2543 2544
		return 1;

	if (!graph_lock())
		return 0;
I
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2545
	/*
P
Peter Zijlstra 已提交
2546
	 * Make sure we didnt race:
I
Ingo Molnar 已提交
2547
	 */
D
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2548
	if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
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2549 2550 2551
		graph_unlock();
		return 1;
	}
I
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2552

D
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2553
	hlock_class(this)->usage_mask |= new_mask;
I
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2554

D
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2555
	if (!save_trace(hlock_class(this)->usage_traces + new_bit))
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2556
		return 0;
I
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2557

P
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2558
	switch (new_bit) {
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2559 2560 2561 2562 2563 2564 2565
#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
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2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578
		ret = mark_lock_irq(curr, this, new_bit);
		if (!ret)
			return 0;
		break;
	case LOCK_USED:
		debug_atomic_dec(&nr_unused_locks);
		break;
	default:
		if (!debug_locks_off_graph_unlock())
			return 0;
		WARN_ON(1);
		return 0;
	}
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Ingo Molnar 已提交
2579

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2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593
	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;
}
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2594 2595 2596 2597 2598

/*
 * Initialize a lock instance's lock-class mapping info:
 */
void lockdep_init_map(struct lockdep_map *lock, const char *name,
2599
		      struct lock_class_key *key, int subclass)
I
Ingo Molnar 已提交
2600
{
2601 2602 2603 2604 2605 2606 2607
	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
2608
		return;
2609 2610 2611
	}

	lock->name = name;
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2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623

	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;
2624 2625 2626 2627

	if (unlikely(!debug_locks))
		return;

2628 2629
	if (subclass)
		register_lock_class(lock, subclass, 1);
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Ingo Molnar 已提交
2630 2631 2632 2633 2634 2635 2636 2637 2638
}
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,
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2639
			  struct lockdep_map *nest_lock, unsigned long ip)
I
Ingo Molnar 已提交
2640 2641
{
	struct task_struct *curr = current;
2642
	struct lock_class *class = NULL;
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Ingo Molnar 已提交
2643 2644 2645 2646 2647
	struct held_lock *hlock;
	unsigned int depth, id;
	int chain_head = 0;
	u64 chain_key;

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2648 2649 2650
	if (!prove_locking)
		check = 1;

I
Ingo Molnar 已提交
2651 2652 2653 2654 2655 2656 2657 2658 2659 2660
	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");
2661
		dump_stack();
I
Ingo Molnar 已提交
2662 2663 2664
		return 0;
	}

2665 2666 2667 2668 2669
	if (!subclass)
		class = lock->class_cache;
	/*
	 * Not cached yet or subclass?
	 */
I
Ingo Molnar 已提交
2670
	if (unlikely(!class)) {
2671
		class = register_lock_class(lock, subclass, 0);
I
Ingo Molnar 已提交
2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688 2689 2690 2691 2692 2693
		if (!class)
			return 0;
	}
	debug_atomic_inc((atomic_t *)&class->ops);
	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;

	hlock = curr->held_locks + depth;
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2694 2695 2696
	if (DEBUG_LOCKS_WARN_ON(!class))
		return 0;
	hlock->class_idx = class - lock_classes + 1;
I
Ingo Molnar 已提交
2697 2698
	hlock->acquire_ip = ip;
	hlock->instance = lock;
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2699
	hlock->nest_lock = nest_lock;
I
Ingo Molnar 已提交
2700 2701 2702
	hlock->trylock = trylock;
	hlock->read = read;
	hlock->check = check;
2703
	hlock->hardirqs_off = !!hardirqs_off;
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2704 2705 2706 2707
#ifdef CONFIG_LOCK_STAT
	hlock->waittime_stamp = 0;
	hlock->holdtime_stamp = sched_clock();
#endif
I
Ingo Molnar 已提交
2708

P
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2709 2710 2711
	if (check == 2 && !mark_irqflags(curr, hlock))
		return 0;

I
Ingo Molnar 已提交
2712
	/* mark it as used: */
2713
	if (!mark_lock(curr, hlock, LOCK_USED))
I
Ingo Molnar 已提交
2714
		return 0;
P
Peter Zijlstra 已提交
2715

I
Ingo Molnar 已提交
2716
	/*
2717
	 * Calculate the chain hash: it's the combined hash of all the
I
Ingo Molnar 已提交
2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737
	 * 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
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2738 2739 2740
	if (separate_irq_context(curr, hlock)) {
		chain_key = 0;
		chain_head = 1;
I
Ingo Molnar 已提交
2741 2742 2743
	}
	chain_key = iterate_chain_key(chain_key, id);

2744
	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
P
Peter Zijlstra 已提交
2745
		return 0;
2746

2747
	curr->curr_chain_key = chain_key;
I
Ingo Molnar 已提交
2748 2749
	curr->lockdep_depth++;
	check_chain_key(curr);
2750 2751 2752 2753
#ifdef CONFIG_DEBUG_LOCKDEP
	if (unlikely(!debug_locks))
		return 0;
#endif
I
Ingo Molnar 已提交
2754 2755 2756 2757
	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");
2758
		dump_stack();
I
Ingo Molnar 已提交
2759 2760
		return 0;
	}
2761

I
Ingo Molnar 已提交
2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780
	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 (",
2781
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
2782 2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794 2795 2796 2797 2798 2799 2800 2801 2802 2803 2804 2805 2806 2807 2808 2809 2810 2811
	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;
}

2812
static int
2813 2814 2815
__lock_set_class(struct lockdep_map *lock, const char *name,
		 struct lock_class_key *key, unsigned int subclass,
		 unsigned long ip)
2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841
{
	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;
		if (hlock->instance == lock)
			goto found_it;
		prev_hlock = hlock;
	}
	return print_unlock_inbalance_bug(curr, lock, ip);

found_it:
2842
	lockdep_init_map(lock, name, key, 0);
2843
	class = register_lock_class(lock, subclass, 0);
D
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2844
	hlock->class_idx = class - lock_classes + 1;
2845 2846 2847 2848 2849 2850 2851

	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
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2852
			hlock_class(hlock)->subclass, hlock->trylock,
2853
				hlock->read, hlock->check, hlock->hardirqs_off,
P
Peter Zijlstra 已提交
2854
				hlock->nest_lock, hlock->acquire_ip))
2855 2856 2857 2858 2859 2860 2861 2862
			return 0;
	}

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

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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 2892 2893 2894 2895 2896 2897 2898 2899
/*
 * 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;
		if (hlock->instance == lock)
			goto found_it;
		prev_hlock = hlock;
	}
	return print_unlock_inbalance_bug(curr, lock, ip);

found_it:
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2900 2901
	lock_release_holdtime(hlock);

I
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2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912
	/*
	 * 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:
	 */
	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
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2913
			hlock_class(hlock)->subclass, hlock->trylock,
I
Ingo Molnar 已提交
2914
				hlock->read, hlock->check, hlock->hardirqs_off,
P
Peter Zijlstra 已提交
2915
				hlock->nest_lock, hlock->acquire_ip))
I
Ingo Molnar 已提交
2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953
			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:
	 */
	if (hlock->instance != lock)
		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
2954 2955
	lock_release_holdtime(hlock);

I
Ingo Molnar 已提交
2956 2957
#ifdef CONFIG_DEBUG_LOCKDEP
	hlock->prev_chain_key = 0;
D
Dave Jones 已提交
2958
	hlock->class_idx = 0;
I
Ingo Molnar 已提交
2959 2960 2961 2962 2963 2964 2965 2966 2967 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
	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);
}

/*
 * Check whether we follow the irq-flags state precisely:
 */
2993
static void check_flags(unsigned long flags)
I
Ingo Molnar 已提交
2994
{
2995 2996
#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
    defined(CONFIG_TRACE_IRQFLAGS)
I
Ingo Molnar 已提交
2997 2998 2999
	if (!debug_locks)
		return;

3000 3001 3002 3003 3004 3005 3006 3007 3008
	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
3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026

	/*
	 * 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
}

3027 3028 3029
void lock_set_class(struct lockdep_map *lock, const char *name,
		    struct lock_class_key *key, unsigned int subclass,
		    unsigned long ip)
3030 3031 3032 3033 3034 3035 3036 3037 3038
{
	unsigned long flags;

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

	raw_local_irq_save(flags);
	current->lockdep_recursion = 1;
	check_flags(flags);
3039
	if (__lock_set_class(lock, name, key, subclass, ip))
3040 3041 3042 3043
		check_chain_key(current);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
3044
EXPORT_SYMBOL_GPL(lock_set_class);
3045

I
Ingo Molnar 已提交
3046 3047 3048 3049
/*
 * We are not always called with irqs disabled - do that here,
 * and also avoid lockdep recursion:
 */
3050
void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
P
Peter Zijlstra 已提交
3051 3052
			  int trylock, int read, int check,
			  struct lockdep_map *nest_lock, unsigned long ip)
I
Ingo Molnar 已提交
3053 3054 3055
{
	unsigned long flags;

3056 3057
	trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);

I
Ingo Molnar 已提交
3058 3059 3060 3061 3062 3063 3064 3065
	if (unlikely(current->lockdep_recursion))
		return;

	raw_local_irq_save(flags);
	check_flags(flags);

	current->lockdep_recursion = 1;
	__lock_acquire(lock, subclass, trylock, read, check,
P
Peter Zijlstra 已提交
3066
		       irqs_disabled_flags(flags), nest_lock, ip);
I
Ingo Molnar 已提交
3067 3068 3069 3070 3071
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquire);

3072
void lock_release(struct lockdep_map *lock, int nested,
3073
			  unsigned long ip)
I
Ingo Molnar 已提交
3074 3075 3076
{
	unsigned long flags;

3077 3078
	trace_lock_release(lock, nested, ip);

I
Ingo Molnar 已提交
3079 3080 3081 3082 3083 3084 3085 3086 3087 3088 3089 3090
	if (unlikely(current->lockdep_recursion))
		return;

	raw_local_irq_save(flags);
	check_flags(flags);
	current->lockdep_recursion = 1;
	__lock_release(lock, nested, ip);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_release);

3091 3092 3093 3094 3095 3096 3097 3098 3099 3100
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
3101 3102 3103 3104 3105 3106 3107 3108 3109 3110 3111 3112 3113 3114
#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 (",
3115
		curr->comm, task_pid_nr(curr));
P
Peter Zijlstra 已提交
3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135
	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
3136
	int i, contention_point, contending_point;
P
Peter Zijlstra 已提交
3137 3138 3139 3140 3141 3142 3143 3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159

	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;
		if (hlock->instance == lock)
			goto found_it;
		prev_hlock = hlock;
	}
	print_lock_contention_bug(curr, lock, ip);
	return;

found_it:
	hlock->waittime_stamp = sched_clock();

P
Peter Zijlstra 已提交
3160 3161 3162
	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
3163

D
Dave Jones 已提交
3164
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3165 3166 3167 3168
	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
3169 3170
	if (lock->cpu != smp_processor_id())
		stats->bounces[bounce_contended + !!hlock->read]++;
P
Peter Zijlstra 已提交
3171 3172 3173 3174
	put_lock_stats(stats);
}

static void
P
Peter Zijlstra 已提交
3175
__lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3176 3177 3178 3179 3180 3181
{
	struct task_struct *curr = current;
	struct held_lock *hlock, *prev_hlock;
	struct lock_class_stats *stats;
	unsigned int depth;
	u64 now;
P
Peter Zijlstra 已提交
3182 3183
	s64 waittime = 0;
	int i, cpu;
P
Peter Zijlstra 已提交
3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204

	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;
		if (hlock->instance == lock)
			goto found_it;
		prev_hlock = hlock;
	}
	print_lock_contention_bug(curr, lock, _RET_IP_);
	return;

found_it:
P
Peter Zijlstra 已提交
3205 3206 3207 3208 3209 3210
	cpu = smp_processor_id();
	if (hlock->waittime_stamp) {
		now = sched_clock();
		waittime = now - hlock->waittime_stamp;
		hlock->holdtime_stamp = now;
	}
P
Peter Zijlstra 已提交
3211

3212 3213
	trace_lock_acquired(lock, ip, waittime);

D
Dave Jones 已提交
3214
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3215 3216 3217 3218 3219 3220 3221 3222
	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
3223
	put_lock_stats(stats);
P
Peter Zijlstra 已提交
3224 3225

	lock->cpu = cpu;
P
Peter Zijlstra 已提交
3226
	lock->ip = ip;
P
Peter Zijlstra 已提交
3227 3228 3229 3230 3231 3232
}

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

3233 3234
	trace_lock_contended(lock, ip);

P
Peter Zijlstra 已提交
3235 3236 3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247 3248 3249
	if (unlikely(!lock_stat))
		return;

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

	raw_local_irq_save(flags);
	check_flags(flags);
	current->lockdep_recursion = 1;
	__lock_contended(lock, ip);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_contended);

P
Peter Zijlstra 已提交
3250
void lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261 3262
{
	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
3263
	__lock_acquired(lock, ip);
P
Peter Zijlstra 已提交
3264 3265 3266 3267 3268 3269
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquired);
#endif

I
Ingo Molnar 已提交
3270 3271 3272 3273 3274 3275 3276 3277
/*
 * Used by the testsuite, sanitize the validator state
 * after a simulated failure:
 */

void lockdep_reset(void)
{
	unsigned long flags;
3278
	int i;
I
Ingo Molnar 已提交
3279 3280 3281 3282 3283 3284 3285 3286 3287 3288

	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;
3289 3290
	for (i = 0; i < CHAINHASH_SIZE; i++)
		INIT_LIST_HEAD(chainhash_table + i);
I
Ingo Molnar 已提交
3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311
	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);

3312
	class->key = NULL;
I
Ingo Molnar 已提交
3313 3314
}

3315
static inline int within(const void *addr, void *start, unsigned long size)
I
Ingo Molnar 已提交
3316 3317 3318 3319 3320 3321 3322 3323 3324 3325
{
	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;
3326
	int locked;
I
Ingo Molnar 已提交
3327 3328

	raw_local_irq_save(flags);
3329
	locked = graph_lock();
I
Ingo Molnar 已提交
3330 3331 3332 3333 3334 3335 3336 3337

	/*
	 * 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;
3338
		list_for_each_entry_safe(class, next, head, hash_entry) {
I
Ingo Molnar 已提交
3339 3340
			if (within(class->key, start, size))
				zap_class(class);
3341 3342 3343
			else if (within(class->name, start, size))
				zap_class(class);
		}
I
Ingo Molnar 已提交
3344 3345
	}

3346 3347
	if (locked)
		graph_unlock();
I
Ingo Molnar 已提交
3348 3349 3350 3351 3352
	raw_local_irq_restore(flags);
}

void lockdep_reset_lock(struct lockdep_map *lock)
{
3353
	struct lock_class *class, *next;
I
Ingo Molnar 已提交
3354 3355 3356
	struct list_head *head;
	unsigned long flags;
	int i, j;
3357
	int locked;
I
Ingo Molnar 已提交
3358 3359 3360 3361

	raw_local_irq_save(flags);

	/*
3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374
	 * 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
3375
	 */
3376
	locked = graph_lock();
I
Ingo Molnar 已提交
3377 3378 3379 3380 3381
	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) {
3382
			if (unlikely(class == lock->class_cache)) {
3383 3384
				if (debug_locks_off_graph_unlock())
					WARN_ON(1);
3385
				goto out_restore;
I
Ingo Molnar 已提交
3386 3387 3388
			}
		}
	}
3389 3390
	if (locked)
		graph_unlock();
3391 3392

out_restore:
I
Ingo Molnar 已提交
3393 3394 3395
	raw_local_irq_restore(flags);
}

3396
void lockdep_init(void)
I
Ingo Molnar 已提交
3397 3398 3399 3400 3401 3402 3403 3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421
{
	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");

3422
	printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
I
Ingo Molnar 已提交
3423 3424
	printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
	printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3425
	printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
I
Ingo Molnar 已提交
3426 3427 3428 3429 3430 3431 3432 3433 3434 3435 3436 3437 3438 3439 3440
	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 +
		sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);

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

#ifdef CONFIG_DEBUG_LOCKDEP
3441 3442 3443 3444 3445
	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
3446 3447 3448 3449 3450
#endif
}

static void
print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3451
		     const void *mem_to, struct held_lock *hlock)
I
Ingo Molnar 已提交
3452 3453 3454 3455 3456 3457 3458 3459 3460 3461
{
	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",
3462
		curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3463
	print_lock(hlock);
I
Ingo Molnar 已提交
3464 3465 3466 3467 3468 3469
	lockdep_print_held_locks(curr);

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

O
Oleg Nesterov 已提交
3470 3471 3472 3473 3474 3475 3476
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
3477 3478 3479 3480 3481 3482 3483 3484 3485 3486 3487 3488 3489 3490 3491 3492 3493 3494 3495
/*
 * 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
3496 3497
		if (not_in_range(mem_from, mem_len, hlock->instance,
					sizeof(*hlock->instance)))
I
Ingo Molnar 已提交
3498 3499
			continue;

O
Oleg Nesterov 已提交
3500
		print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
I
Ingo Molnar 已提交
3501 3502 3503 3504
		break;
	}
	local_irq_restore(flags);
}
3505
EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
I
Ingo Molnar 已提交
3506 3507 3508 3509 3510 3511 3512 3513 3514 3515 3516 3517

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",
3518
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
3519 3520 3521 3522 3523 3524 3525 3526 3527 3528 3529 3530 3531 3532 3533 3534 3535 3536
	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;

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	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
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	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;
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	} else {
		if (count != 10)
			printk(KERN_CONT " locked it.\n");
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	}

	do_each_thread(g, p) {
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		/*
		 * 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;
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		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);

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/*
 * 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)
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{
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	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
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	lockdep_print_held_locks(task);
}
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EXPORT_SYMBOL_GPL(__debug_show_held_locks);

void debug_show_held_locks(struct task_struct *task)
{
		__debug_show_held_locks(task);
}
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EXPORT_SYMBOL_GPL(debug_show_held_locks);
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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);
	}
}