lockdep.c 88.3 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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static 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;

#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);
	}
}

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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:
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 */
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static int static_obj(void *obj)
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{
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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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	/*
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	 * static variable?
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	 */
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	if ((addr >= start) && (addr < end))
		return 1;
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#ifdef CONFIG_SMP
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	/*
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	 * percpu var?
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	 */
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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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		if ((addr >= start) && (addr < end))
			return 1;
	}
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#endif
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	/*
	 * module var?
	 */
	return is_module_address(addr);
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}

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/*
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 * To make lock name printouts unique, we calculate a unique
 * class->name_version generation counter:
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 */
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static int count_matching_names(struct lock_class *new_class)
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{
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	struct lock_class *class;
	int count = 0;
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604
	if (!new_class->name)
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Ingo Molnar 已提交
605 606
		return 0;

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	list_for_each_entry(class, &all_lock_classes, lock_entry) {
		if (new_class->key - new_class->subclass == class->key)
			return class->name_version;
		if (class->name && !strcmp(class->name, new_class->name))
			count = max(count, class->name_version);
	}
I
Ingo Molnar 已提交
613

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

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

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

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

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

P
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658
	key = lock->key->subkeys + subclass;
659

P
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660
	hash_head = classhashentry(key);
661

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

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

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

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

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

		return NULL;
	}

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

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

		printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
		printk("turning off the locking correctness validator.\n");
734
		dump_stack();
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Peter Zijlstra 已提交
735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750
		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);
751 752 753 754
	/*
	 * 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
755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797

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

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

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

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

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

	return class;
}

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

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

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

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

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

	return 1;
}

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Peter Zijlstra 已提交
836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852
/*For good efficiency of modular, we use power of 2*/
#define MAX_CIRCULAR_QUEUE_SIZE		4096UL
#define CQ_MASK				(MAX_CIRCULAR_QUEUE_SIZE-1)

/* The circular_queue and helpers is used to implement the
 * breadth-first search(BFS)algorithem, by which we can build
 * the shortest path from the next lock to be acquired to the
 * previous held lock if there is a circular between them.
 * */
struct circular_queue {
	unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
	unsigned int  front, rear;
};

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

853
unsigned int max_bfs_queue_depth;
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Peter Zijlstra 已提交
854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930

static inline void __cq_init(struct circular_queue *cq)
{
	cq->front = cq->rear = 0;
	bitmap_zero(bfs_accessed, MAX_LOCKDEP_ENTRIES);
}

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

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

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

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

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

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

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

static inline void mark_lock_accessed(struct lock_list *lock,
					struct lock_list *parent)
{
	unsigned long nr;
	nr = lock - list_entries;
	WARN_ON(nr >= nr_list_entries);
	lock->parent = parent;
	set_bit(nr, bfs_accessed);
}

static inline unsigned long lock_accessed(struct lock_list *lock)
{
	unsigned long nr;
	nr = lock - list_entries;
	WARN_ON(nr >= nr_list_entries);
	return test_bit(nr, bfs_accessed);
}

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

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

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

931
static int __bfs(struct lock_list *source_entry,
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932 933 934 935
		 void *data,
		 int (*match)(struct lock_list *entry, void *data),
		 struct lock_list **target_entry,
		 int forward)
936 937
{
	struct lock_list *entry;
938
	struct list_head *head;
939 940 941
	struct circular_queue *cq = &lock_cq;
	int ret = 1;

942
	if (match(source_entry, data)) {
943 944 945 946 947
		*target_entry = source_entry;
		ret = 0;
		goto exit;
	}

948 949 950 951 952 953 954 955 956
	if (forward)
		head = &source_entry->class->locks_after;
	else
		head = &source_entry->class->locks_before;

	if (list_empty(head))
		goto exit;

	__cq_init(cq);
957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975
	__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)) {
976
				unsigned int cq_depth;
977
				mark_lock_accessed(entry, lock);
978
				if (match(entry, data)) {
979 980 981 982 983 984 985 986 987
					*target_entry = entry;
					ret = 0;
					goto exit;
				}

				if (__cq_enqueue(cq, (unsigned long)entry)) {
					ret = -1;
					goto exit;
				}
988 989 990
				cq_depth = __cq_get_elem_count(cq);
				if (max_bfs_queue_depth < cq_depth)
					max_bfs_queue_depth = cq_depth;
991 992 993 994 995 996 997
			}
		}
	}
exit:
	return ret;
}

998
static inline int __bfs_forwards(struct lock_list *src_entry,
999 1000 1001
			void *data,
			int (*match)(struct lock_list *entry, void *data),
			struct lock_list **target_entry)
1002
{
1003
	return __bfs(src_entry, data, match, target_entry, 1);
1004 1005 1006

}

1007
static inline int __bfs_backwards(struct lock_list *src_entry,
1008 1009 1010
			void *data,
			int (*match)(struct lock_list *entry, void *data),
			struct lock_list **target_entry)
1011
{
1012
	return __bfs(src_entry, data, match, target_entry, 0);
1013 1014 1015

}

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Peter Zijlstra 已提交
1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026
/*
 * Recursive, forwards-direction lock-dependency checking, used for
 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
 * checking.
 */

/*
 * Print a dependency chain entry (this is only done when a deadlock
 * has been detected):
 */
static noinline int
1027
print_circular_bug_entry(struct lock_list *target, int depth)
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Peter Zijlstra 已提交
1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043
{
	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
1044 1045 1046
print_circular_bug_header(struct lock_list *entry, unsigned int depth,
			struct held_lock *check_src,
			struct held_lock *check_tgt)
P
Peter Zijlstra 已提交
1047 1048 1049
{
	struct task_struct *curr = current;

1050
	if (debug_locks_silent)
P
Peter Zijlstra 已提交
1051 1052 1053 1054 1055 1056 1057
		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",
1058
		curr->comm, task_pid_nr(curr));
1059
	print_lock(check_src);
P
Peter Zijlstra 已提交
1060
	printk("\nbut task is already holding lock:\n");
1061
	print_lock(check_tgt);
P
Peter Zijlstra 已提交
1062 1063 1064 1065 1066 1067 1068 1069
	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;
}

1070 1071 1072 1073 1074
static inline int class_equal(struct lock_list *entry, void *data)
{
	return entry->class == data;
}

1075 1076 1077 1078
static noinline int print_circular_bug(struct lock_list *this,
				struct lock_list *target,
				struct held_lock *check_src,
				struct held_lock *check_tgt)
P
Peter Zijlstra 已提交
1079 1080
{
	struct task_struct *curr = current;
1081
	struct lock_list *parent;
1082
	int depth;
P
Peter Zijlstra 已提交
1083

1084
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
P
Peter Zijlstra 已提交
1085 1086
		return 0;

1087
	if (!save_trace(&this->trace))
P
Peter Zijlstra 已提交
1088 1089
		return 0;

1090 1091
	depth = get_lock_depth(target);

1092
	print_circular_bug_header(target, depth, check_src, check_tgt);
1093 1094 1095 1096 1097 1098 1099

	parent = get_lock_parent(target);

	while (parent) {
		print_circular_bug_entry(parent, --depth);
		parent = get_lock_parent(parent);
	}
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Peter Zijlstra 已提交
1100 1101 1102 1103 1104 1105 1106 1107 1108 1109

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

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

	return 0;
}

1110 1111 1112 1113 1114 1115 1116 1117 1118 1119
static noinline int print_bfs_bug(int ret)
{
	if (!debug_locks_off_graph_unlock())
		return 0;

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

	return 0;
}

1120
static int noop_count(struct lock_list *entry, void *data)
1121
{
1122 1123 1124
	(*(unsigned long *)data)++;
	return 0;
}
1125

1126 1127 1128 1129
unsigned long __lockdep_count_forward_deps(struct lock_list *this)
{
	unsigned long  count = 0;
	struct lock_list *uninitialized_var(target_entry);
1130

1131
	__bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1132

1133
	return count;
1134 1135 1136 1137
}
unsigned long lockdep_count_forward_deps(struct lock_class *class)
{
	unsigned long ret, flags;
1138 1139 1140 1141
	struct lock_list this;

	this.parent = NULL;
	this.class = class;
1142 1143 1144

	local_irq_save(flags);
	__raw_spin_lock(&lockdep_lock);
1145
	ret = __lockdep_count_forward_deps(&this);
1146 1147 1148 1149 1150 1151
	__raw_spin_unlock(&lockdep_lock);
	local_irq_restore(flags);

	return ret;
}

1152
unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1153
{
1154 1155
	unsigned long  count = 0;
	struct lock_list *uninitialized_var(target_entry);
1156

1157
	__bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1158

1159
	return count;
1160 1161 1162 1163 1164
}

unsigned long lockdep_count_backward_deps(struct lock_class *class)
{
	unsigned long ret, flags;
1165 1166 1167 1168
	struct lock_list this;

	this.parent = NULL;
	this.class = class;
1169 1170 1171

	local_irq_save(flags);
	__raw_spin_lock(&lockdep_lock);
1172
	ret = __lockdep_count_backward_deps(&this);
1173 1174 1175 1176 1177 1178
	__raw_spin_unlock(&lockdep_lock);
	local_irq_restore(flags);

	return ret;
}

P
Peter Zijlstra 已提交
1179 1180 1181 1182 1183
/*
 * 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
1184 1185
check_noncircular(struct lock_list *root, struct lock_class *target,
		struct lock_list **target_entry)
P
Peter Zijlstra 已提交
1186
{
1187
	int result;
P
Peter Zijlstra 已提交
1188

1189
	debug_atomic_inc(&nr_cyclic_checks);
1190

1191
	result = __bfs_forwards(root, target, class_equal, target_entry);
I
Ingo Molnar 已提交
1192

1193 1194
	return result;
}
1195

1196
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
I
Ingo Molnar 已提交
1197 1198 1199 1200 1201 1202
/*
 * 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.
 */

1203 1204 1205 1206 1207 1208 1209
static inline int usage_match(struct lock_list *entry, void *bit)
{
	return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
}



I
Ingo Molnar 已提交
1210 1211
/*
 * Find a node in the forwards-direction dependency sub-graph starting
1212
 * at @root->class that matches @bit.
I
Ingo Molnar 已提交
1213
 *
1214 1215
 * Return 0 if such a node exists in the subgraph, and put that node
 * into *@target_entry.
I
Ingo Molnar 已提交
1216
 *
1217 1218
 * Return 1 otherwise and keep *@target_entry unchanged.
 * Return <0 on error.
I
Ingo Molnar 已提交
1219
 */
1220 1221 1222
static int
find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
			struct lock_list **target_entry)
I
Ingo Molnar 已提交
1223
{
1224
	int result;
I
Ingo Molnar 已提交
1225 1226 1227

	debug_atomic_inc(&nr_find_usage_forwards_checks);

1228 1229 1230
	result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);

	return result;
I
Ingo Molnar 已提交
1231 1232 1233 1234
}

/*
 * Find a node in the backwards-direction dependency sub-graph starting
1235
 * at @root->class that matches @bit.
I
Ingo Molnar 已提交
1236
 *
1237 1238
 * Return 0 if such a node exists in the subgraph, and put that node
 * into *@target_entry.
I
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1239
 *
1240 1241
 * Return 1 otherwise and keep *@target_entry unchanged.
 * Return <0 on error.
I
Ingo Molnar 已提交
1242
 */
1243 1244 1245
static int
find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
			struct lock_list **target_entry)
I
Ingo Molnar 已提交
1246
{
1247
	int result;
I
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1248 1249 1250

	debug_atomic_inc(&nr_find_usage_backwards_checks);

1251
	result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
D
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1252

1253
	return result;
I
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1254 1255
}

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1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309
static void print_lock_class_header(struct lock_class *class, int depth)
{
	int bit;

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

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

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

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

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

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

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

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

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

	return;
}
1310

I
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1311 1312
static int
print_bad_irq_dependency(struct task_struct *curr,
1313 1314 1315 1316
			 struct lock_list *prev_root,
			 struct lock_list *next_root,
			 struct lock_list *backwards_entry,
			 struct lock_list *forwards_entry,
I
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1317 1318 1319 1320 1321 1322
			 struct held_lock *prev,
			 struct held_lock *next,
			 enum lock_usage_bit bit1,
			 enum lock_usage_bit bit2,
			 const char *irqclass)
{
1323
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
1324 1325 1326 1327 1328
		return 0;

	printk("\n======================================================\n");
	printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
		irqclass, irqclass);
1329
	print_kernel_version();
I
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1330 1331
	printk(  "------------------------------------------------------\n");
	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1332
		curr->comm, task_pid_nr(curr),
I
Ingo Molnar 已提交
1333 1334 1335 1336 1337 1338 1339 1340 1341
		curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
		curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
		curr->hardirqs_enabled,
		curr->softirqs_enabled);
	print_lock(next);

	printk("\nand this task is already holding:\n");
	print_lock(prev);
	printk("which would create a new lock dependency:\n");
D
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1342
	print_lock_name(hlock_class(prev));
I
Ingo Molnar 已提交
1343
	printk(" ->");
D
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1344
	print_lock_name(hlock_class(next));
I
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1345 1346 1347 1348
	printk("\n");

	printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
		irqclass);
1349
	print_lock_name(backwards_entry->class);
I
Ingo Molnar 已提交
1350 1351
	printk("\n... which became %s-irq-safe at:\n", irqclass);

1352
	print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
I
Ingo Molnar 已提交
1353 1354

	printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1355
	print_lock_name(forwards_entry->class);
I
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1356 1357 1358
	printk("\n... which became %s-irq-unsafe at:\n", irqclass);
	printk("...");

1359
	print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
I
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1360 1361 1362 1363

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

1364 1365 1366 1367 1368
	printk("\nthe dependencies between %s-irq-safe lock", irqclass);
	printk(" and the holding lock:\n");
	if (!save_trace(&prev_root->trace))
		return 0;
	print_shortest_lock_dependencies(backwards_entry, prev_root);
I
Ingo Molnar 已提交
1369

1370 1371 1372 1373 1374
	printk("\nthe dependencies between the lock to be acquired");
	printk(" and %s-irq-unsafe lock:\n", irqclass);
	if (!save_trace(&next_root->trace))
		return 0;
	print_shortest_lock_dependencies(forwards_entry, next_root);
I
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1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387

	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;
1388
	struct lock_list this, that;
1389
	struct lock_list *uninitialized_var(target_entry);
1390
	struct lock_list *uninitialized_var(target_entry1);
1391 1392 1393 1394 1395

	this.parent = NULL;

	this.class = hlock_class(prev);
	ret = find_usage_backwards(&this, bit_backwards, &target_entry);
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1396 1397 1398 1399
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
1400

1401 1402 1403
	that.parent = NULL;
	that.class = hlock_class(next);
	ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
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1404 1405 1406 1407
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
I
Ingo Molnar 已提交
1408

1409 1410 1411
	return print_bad_irq_dependency(curr, &this, &that,
			target_entry, target_entry1,
			prev, next,
I
Ingo Molnar 已提交
1412 1413 1414
			bit_backwards, bit_forwards, irqclass);
}

1415 1416
static const char *state_names[] = {
#define LOCKDEP_STATE(__STATE) \
P
Peter Zijlstra 已提交
1417
	__stringify(__STATE),
1418 1419 1420 1421 1422 1423
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

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

static inline const char *state_name(enum lock_usage_bit bit)
P
Peter Zijlstra 已提交
1430
{
1431 1432
	return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
}
P
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1433

1434 1435
static int exclusive_bit(int new_bit)
{
P
Peter Zijlstra 已提交
1436
	/*
1437 1438 1439 1440 1441 1442 1443 1444
	 * USED_IN
	 * USED_IN_READ
	 * ENABLED
	 * ENABLED_READ
	 *
	 * bit 0 - write/read
	 * bit 1 - used_in/enabled
	 * bit 2+  state
P
Peter Zijlstra 已提交
1445
	 */
1446 1447 1448

	int state = new_bit & ~3;
	int dir = new_bit & 2;
P
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1449 1450

	/*
1451
	 * keep state, bit flip the direction and strip read.
P
Peter Zijlstra 已提交
1452
	 */
1453 1454 1455 1456 1457 1458
	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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1459
	/*
1460 1461
	 * 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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1462 1463 1464
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
1465 1466
	if (!check_usage(curr, prev, next, bit,
			   exclusive_bit(bit), state_name(bit)))
P
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1467 1468
		return 0;

1469 1470
	bit++; /* _READ */

1471
	/*
1472 1473
	 * Prove that the new dependency does not connect a hardirq-safe-read
	 * lock with a hardirq-unsafe lock - to achieve this we search
1474 1475 1476
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
1477 1478
	if (!check_usage(curr, prev, next, bit,
			   exclusive_bit(bit), state_name(bit)))
1479 1480
		return 0;

1481 1482 1483 1484 1485 1486 1487 1488 1489
	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))	\
1490
		return 0;
1491 1492
#include "lockdep_states.h"
#undef LOCKDEP_STATE
1493

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1494 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 1521 1522
	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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1523 1524 1525 1526 1527 1528
#endif

static int
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
		   struct held_lock *next)
{
1529
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
1530 1531 1532 1533
		return 0;

	printk("\n=============================================\n");
	printk(  "[ INFO: possible recursive locking detected ]\n");
1534
	print_kernel_version();
I
Ingo Molnar 已提交
1535 1536
	printk(  "---------------------------------------------\n");
	printk("%s/%d is trying to acquire lock:\n",
1537
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563
	print_lock(next);
	printk("\nbut task is already holding lock:\n");
	print_lock(prev);

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

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

	return 0;
}

/*
 * Check whether we are holding such a class already.
 *
 * (Note that this has to be done separately, because the graph cannot
 * detect such classes of deadlocks.)
 *
 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
 */
static int
check_deadlock(struct task_struct *curr, struct held_lock *next,
	       struct lockdep_map *next_instance, int read)
{
	struct held_lock *prev;
P
Peter Zijlstra 已提交
1564
	struct held_lock *nest = NULL;
I
Ingo Molnar 已提交
1565 1566 1567 1568
	int i;

	for (i = 0; i < curr->lockdep_depth; i++) {
		prev = curr->held_locks + i;
P
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1569 1570 1571 1572

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

D
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1573
		if (hlock_class(prev) != hlock_class(next))
I
Ingo Molnar 已提交
1574
			continue;
P
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1575

I
Ingo Molnar 已提交
1576 1577
		/*
		 * Allow read-after-read recursion of the same
1578
		 * lock class (i.e. read_lock(lock)+read_lock(lock)):
I
Ingo Molnar 已提交
1579
		 */
1580
		if ((read == 2) && prev->read)
I
Ingo Molnar 已提交
1581
			return 2;
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1582 1583 1584 1585 1586 1587 1588 1589

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

I
Ingo Molnar 已提交
1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618
		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,
1619
	       struct held_lock *next, int distance)
I
Ingo Molnar 已提交
1620 1621 1622
{
	struct lock_list *entry;
	int ret;
1623 1624
	struct lock_list this;
	struct lock_list *uninitialized_var(target_entry);
I
Ingo Molnar 已提交
1625 1626 1627 1628 1629 1630 1631 1632 1633 1634

	/*
	 * 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:
	 */
1635 1636 1637 1638 1639 1640 1641
	this.class = hlock_class(next);
	this.parent = NULL;
	ret = check_noncircular(&this, hlock_class(prev), &target_entry);
	if (unlikely(!ret))
		return print_circular_bug(&this, target_entry, next, prev);
	else if (unlikely(ret < 0))
		return print_bfs_bug(ret);
1642

P
Peter Zijlstra 已提交
1643
	if (!check_prev_add_irq(curr, prev, next))
I
Ingo Molnar 已提交
1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663
		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
1664 1665
	list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
		if (entry->class == hlock_class(next)) {
1666 1667
			if (distance == 1)
				entry->distance = 1;
I
Ingo Molnar 已提交
1668
			return 2;
1669
		}
I
Ingo Molnar 已提交
1670 1671 1672 1673 1674 1675
	}

	/*
	 * Ok, all validations passed, add the new lock
	 * to the previous lock's dependency list:
	 */
D
Dave Jones 已提交
1676 1677 1678
	ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
			       &hlock_class(prev)->locks_after,
			       next->acquire_ip, distance);
1679

I
Ingo Molnar 已提交
1680 1681
	if (!ret)
		return 0;
1682

D
Dave Jones 已提交
1683 1684 1685
	ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
			       &hlock_class(next)->locks_before,
			       next->acquire_ip, distance);
1686 1687
	if (!ret)
		return 0;
I
Ingo Molnar 已提交
1688 1689

	/*
P
Peter Zijlstra 已提交
1690 1691
	 * Debugging printouts:
	 */
D
Dave Jones 已提交
1692
	if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
P
Peter Zijlstra 已提交
1693 1694
		graph_unlock();
		printk("\n new dependency: ");
D
Dave Jones 已提交
1695
		print_lock_name(hlock_class(prev));
P
Peter Zijlstra 已提交
1696
		printk(" => ");
D
Dave Jones 已提交
1697
		print_lock_name(hlock_class(next));
P
Peter Zijlstra 已提交
1698
		printk("\n");
I
Ingo Molnar 已提交
1699
		dump_stack();
P
Peter Zijlstra 已提交
1700
		return graph_lock();
I
Ingo Molnar 已提交
1701
	}
P
Peter Zijlstra 已提交
1702 1703
	return 1;
}
I
Ingo Molnar 已提交
1704

P
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1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715
/*
 * 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;
1716

I
Ingo Molnar 已提交
1717
	/*
P
Peter Zijlstra 已提交
1718 1719 1720
	 * Debugging checks.
	 *
	 * Depth must not be zero for a non-head lock:
I
Ingo Molnar 已提交
1721
	 */
P
Peter Zijlstra 已提交
1722 1723
	if (!depth)
		goto out_bug;
I
Ingo Molnar 已提交
1724
	/*
P
Peter Zijlstra 已提交
1725 1726
	 * At least two relevant locks must exist for this
	 * to be a head:
I
Ingo Molnar 已提交
1727
	 */
P
Peter Zijlstra 已提交
1728 1729 1730
	if (curr->held_locks[depth].irq_context !=
			curr->held_locks[depth-1].irq_context)
		goto out_bug;
1731

P
Peter Zijlstra 已提交
1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749
	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;
1750
		}
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Peter Zijlstra 已提交
1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762
		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
1763
	}
P
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1764 1765 1766 1767
	return 1;
out_bug:
	if (!debug_locks_off_graph_unlock())
		return 0;
I
Ingo Molnar 已提交
1768

P
Peter Zijlstra 已提交
1769
	WARN_ON(1);
I
Ingo Molnar 已提交
1770

P
Peter Zijlstra 已提交
1771
	return 0;
I
Ingo Molnar 已提交
1772 1773
}

P
Peter Zijlstra 已提交
1774
unsigned long nr_lock_chains;
1775
struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1776
int nr_chain_hlocks;
1777 1778 1779 1780 1781 1782
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];
}
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1783

I
Ingo Molnar 已提交
1784 1785
/*
 * Look up a dependency chain. If the key is not present yet then
1786 1787 1788
 * 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
1789
 */
1790 1791 1792
static inline int lookup_chain_cache(struct task_struct *curr,
				     struct held_lock *hlock,
				     u64 chain_key)
I
Ingo Molnar 已提交
1793
{
D
Dave Jones 已提交
1794
	struct lock_class *class = hlock_class(hlock);
I
Ingo Molnar 已提交
1795 1796
	struct list_head *hash_head = chainhashentry(chain_key);
	struct lock_chain *chain;
1797
	struct held_lock *hlock_curr, *hlock_next;
1798
	int i, j, n, cn;
I
Ingo Molnar 已提交
1799

1800 1801
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return 0;
I
Ingo Molnar 已提交
1802 1803 1804 1805 1806 1807 1808 1809
	/*
	 * 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);
1810
			if (very_verbose(class))
1811 1812 1813 1814
				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
1815 1816 1817
			return 0;
		}
	}
1818
	if (very_verbose(class))
1819 1820
		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
1821 1822 1823 1824
	/*
	 * Allocate a new chain entry from the static array, and add
	 * it to the hash:
	 */
1825 1826
	if (!graph_lock())
		return 0;
I
Ingo Molnar 已提交
1827 1828 1829 1830 1831
	/*
	 * 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) {
1832
			graph_unlock();
I
Ingo Molnar 已提交
1833 1834 1835 1836
			goto cache_hit;
		}
	}
	if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1837 1838 1839
		if (!debug_locks_off_graph_unlock())
			return 0;

I
Ingo Molnar 已提交
1840 1841
		printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
		printk("turning off the locking correctness validator.\n");
1842
		dump_stack();
I
Ingo Molnar 已提交
1843 1844 1845 1846
		return 0;
	}
	chain = lock_chains + nr_lock_chains++;
	chain->chain_key = chain_key;
1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857
	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;
1858 1859 1860 1861 1862 1863 1864 1865 1866
	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;
1867
		for (j = 0; j < chain->depth - 1; j++, i++) {
D
Dave Jones 已提交
1868
			int lock_id = curr->held_locks[i].class_idx - 1;
1869 1870 1871 1872
			chain_hlocks[chain->base + j] = lock_id;
		}
		chain_hlocks[chain->base + j] = class - lock_classes;
	}
I
Ingo Molnar 已提交
1873 1874
	list_add_tail_rcu(&chain->entry, hash_head);
	debug_atomic_inc(&chain_lookup_misses);
P
Peter Zijlstra 已提交
1875 1876 1877 1878 1879 1880
	inc_chains();

	return 1;
}

static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1881
		struct held_lock *hlock, int chain_head, u64 chain_key)
P
Peter Zijlstra 已提交
1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893
{
	/*
	 * 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) &&
1894
	    lookup_chain_cache(curr, hlock, chain_key)) {
P
Peter Zijlstra 已提交
1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929
		/*
		 * 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
1930 1931 1932

	return 1;
}
P
Peter Zijlstra 已提交
1933 1934 1935
#else
static inline int validate_chain(struct task_struct *curr,
	       	struct lockdep_map *lock, struct held_lock *hlock,
1936
		int chain_head, u64 chain_key)
P
Peter Zijlstra 已提交
1937 1938 1939
{
	return 1;
}
1940
#endif
I
Ingo Molnar 已提交
1941 1942 1943 1944 1945

/*
 * We are building curr_chain_key incrementally, so double-check
 * it from scratch, to make sure that it's done correctly:
 */
1946
static void check_chain_key(struct task_struct *curr)
I
Ingo Molnar 已提交
1947 1948 1949 1950 1951 1952 1953 1954 1955 1956
{
#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();
1957
			WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
I
Ingo Molnar 已提交
1958 1959 1960 1961 1962
				curr->lockdep_depth, i,
				(unsigned long long)chain_key,
				(unsigned long long)hlock->prev_chain_key);
			return;
		}
D
Dave Jones 已提交
1963
		id = hlock->class_idx - 1;
1964 1965 1966
		if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
			return;

I
Ingo Molnar 已提交
1967 1968 1969 1970 1971 1972 1973 1974
		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();
1975
		WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
I
Ingo Molnar 已提交
1976 1977 1978 1979 1980 1981 1982
			curr->lockdep_depth, i,
			(unsigned long long)chain_key,
			(unsigned long long)curr->curr_chain_key);
	}
#endif
}

P
Peter Zijlstra 已提交
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998
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",
1999
		curr->comm, task_pid_nr(curr),
P
Peter Zijlstra 已提交
2000 2001 2002 2003 2004 2005 2006
		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
2007
	print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
P
Peter Zijlstra 已提交
2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025

	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
2026
	if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
P
Peter Zijlstra 已提交
2027 2028 2029 2030 2031 2032 2033
		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);

2034
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
I
Ingo Molnar 已提交
2035 2036 2037 2038 2039

/*
 * print irq inversion bug:
 */
static int
2040 2041
print_irq_inversion_bug(struct task_struct *curr,
			struct lock_list *root, struct lock_list *other,
I
Ingo Molnar 已提交
2042 2043 2044
			struct held_lock *this, int forwards,
			const char *irqclass)
{
2045
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
2046 2047 2048 2049
		return 0;

	printk("\n=========================================================\n");
	printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2050
	print_kernel_version();
I
Ingo Molnar 已提交
2051 2052
	printk(  "---------------------------------------------------------\n");
	printk("%s/%d just changed the state of lock:\n",
2053
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
2054 2055
	print_lock(this);
	if (forwards)
2056
		printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
I
Ingo Molnar 已提交
2057
	else
2058
		printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2059
	print_lock_name(other->class);
I
Ingo Molnar 已提交
2060 2061 2062 2063 2064
	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);

2065 2066 2067 2068
	printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
	if (!save_trace(&root->trace))
		return 0;
	print_shortest_lock_dependencies(other, root);
I
Ingo Molnar 已提交
2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084

	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;
2085 2086
	struct lock_list root;
	struct lock_list *uninitialized_var(target_entry);
I
Ingo Molnar 已提交
2087

2088 2089 2090
	root.parent = NULL;
	root.class = hlock_class(this);
	ret = find_usage_forwards(&root, bit, &target_entry);
P
Peter Zijlstra 已提交
2091 2092 2093 2094
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
I
Ingo Molnar 已提交
2095

2096
	return print_irq_inversion_bug(curr, &root, target_entry,
2097
					this, 1, irqclass);
I
Ingo Molnar 已提交
2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108
}

/*
 * 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;
2109 2110
	struct lock_list root;
	struct lock_list *uninitialized_var(target_entry);
I
Ingo Molnar 已提交
2111

2112 2113 2114
	root.parent = NULL;
	root.class = hlock_class(this);
	ret = find_usage_backwards(&root, bit, &target_entry);
P
Peter Zijlstra 已提交
2115 2116 2117 2118
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
I
Ingo Molnar 已提交
2119

2120
	return print_irq_inversion_bug(curr, &root, target_entry,
2121
					this, 1, irqclass);
I
Ingo Molnar 已提交
2122 2123
}

2124
void print_irqtrace_events(struct task_struct *curr)
I
Ingo Molnar 已提交
2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136
{
	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);
}

2137
static int HARDIRQ_verbose(struct lock_class *class)
I
Ingo Molnar 已提交
2138
{
P
Peter Zijlstra 已提交
2139 2140 2141
#if HARDIRQ_VERBOSE
	return class_filter(class);
#endif
I
Ingo Molnar 已提交
2142 2143 2144
	return 0;
}

2145
static int SOFTIRQ_verbose(struct lock_class *class)
I
Ingo Molnar 已提交
2146
{
P
Peter Zijlstra 已提交
2147 2148 2149 2150
#if SOFTIRQ_VERBOSE
	return class_filter(class);
#endif
	return 0;
I
Ingo Molnar 已提交
2151 2152
}

2153
static int RECLAIM_FS_verbose(struct lock_class *class)
2154 2155 2156 2157 2158 2159 2160
{
#if RECLAIM_VERBOSE
	return class_filter(class);
#endif
	return 0;
}

I
Ingo Molnar 已提交
2161 2162
#define STRICT_READ_CHECKS	1

2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175
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);
}

2176 2177 2178
typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
			     enum lock_usage_bit bit, const char *name);

2179
static int
2180 2181
mark_lock_irq(struct task_struct *curr, struct held_lock *this,
		enum lock_usage_bit new_bit)
2182
{
2183
	int excl_bit = exclusive_bit(new_bit);
2184
	int read = new_bit & 1;
2185 2186
	int dir = new_bit & 2;

2187 2188 2189 2190 2191 2192 2193
	/*
	 * 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.
	 */
2194 2195
	check_usage_f usage = dir ?
		check_usage_backwards : check_usage_forwards;
2196

2197 2198 2199 2200
	/*
	 * Validate that this particular lock does not have conflicting
	 * usage states.
	 */
2201 2202
	if (!valid_state(curr, this, new_bit, excl_bit))
		return 0;
2203

2204 2205 2206 2207 2208
	/*
	 * Validate that the lock dependencies don't have conflicting usage
	 * states.
	 */
	if ((!read || !dir || STRICT_READ_CHECKS) &&
2209
			!usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2210
		return 0;
2211

2212 2213 2214 2215 2216 2217 2218 2219
	/*
	 * Check for read in write conflicts
	 */
	if (!read) {
		if (!valid_state(curr, this, new_bit, excl_bit + 1))
			return 0;

		if (STRICT_READ_CHECKS &&
2220 2221
			!usage(curr, this, excl_bit + 1,
				state_name(new_bit + 1)))
2222 2223
			return 0;
	}
2224

2225
	if (state_verbose(new_bit, hlock_class(this)))
2226 2227 2228 2229 2230
		return 2;

	return 1;
}

2231
enum mark_type {
2232 2233 2234
#define LOCKDEP_STATE(__STATE)	__STATE,
#include "lockdep_states.h"
#undef LOCKDEP_STATE
2235 2236
};

I
Ingo Molnar 已提交
2237 2238 2239
/*
 * Mark all held locks with a usage bit:
 */
2240
static int
2241
mark_held_locks(struct task_struct *curr, enum mark_type mark)
I
Ingo Molnar 已提交
2242 2243 2244 2245 2246 2247 2248 2249
{
	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;

2250 2251 2252 2253 2254
		usage_bit = 2 + (mark << 2); /* ENABLED */
		if (hlock->read)
			usage_bit += 1; /* READ */

		BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2255

2256
		if (!mark_lock(curr, hlock, usage_bit))
I
Ingo Molnar 已提交
2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281
			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:
 */
2282
void trace_hardirqs_on_caller(unsigned long ip)
I
Ingo Molnar 已提交
2283 2284 2285
{
	struct task_struct *curr = current;

2286
	time_hardirqs_on(CALLER_ADDR0, ip);
2287

I
Ingo Molnar 已提交
2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308
	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:
	 */
2309
	if (!mark_held_locks(curr, HARDIRQ))
I
Ingo Molnar 已提交
2310 2311 2312 2313 2314 2315 2316
		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)
2317
		if (!mark_held_locks(curr, SOFTIRQ))
I
Ingo Molnar 已提交
2318 2319
			return;

P
Peter Zijlstra 已提交
2320 2321 2322 2323
	curr->hardirq_enable_ip = ip;
	curr->hardirq_enable_event = ++curr->irq_events;
	debug_atomic_inc(&hardirqs_on_events);
}
2324
EXPORT_SYMBOL(trace_hardirqs_on_caller);
P
Peter Zijlstra 已提交
2325

2326
void trace_hardirqs_on(void)
2327 2328 2329
{
	trace_hardirqs_on_caller(CALLER_ADDR0);
}
P
Peter Zijlstra 已提交
2330 2331 2332 2333 2334
EXPORT_SYMBOL(trace_hardirqs_on);

/*
 * Hardirqs were disabled:
 */
2335
void trace_hardirqs_off_caller(unsigned long ip)
P
Peter Zijlstra 已提交
2336 2337 2338
{
	struct task_struct *curr = current;

2339
	time_hardirqs_off(CALLER_ADDR0, ip);
2340

P
Peter Zijlstra 已提交
2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351
	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;
2352
		curr->hardirq_disable_ip = ip;
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		curr->hardirq_disable_event = ++curr->irq_events;
		debug_atomic_inc(&hardirqs_off_events);
	} else
		debug_atomic_inc(&redundant_hardirqs_off);
}
2358
EXPORT_SYMBOL(trace_hardirqs_off_caller);
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2360
void trace_hardirqs_off(void)
2361 2362 2363
{
	trace_hardirqs_off_caller(CALLER_ADDR0);
}
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2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396
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)
2397
		mark_held_locks(curr, SOFTIRQ);
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}

/*
 * 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);
}

2426
static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444
{
	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;

2445
	if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2446 2447 2448 2449 2450
		return;

	mark_held_locks(curr, RECLAIM_FS);
}

2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467
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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2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495
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,
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					LOCK_ENABLED_HARDIRQ_READ))
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2497 2498 2499
				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
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2500
						LOCK_ENABLED_SOFTIRQ_READ))
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2501 2502 2503
					return 0;
		} else {
			if (!mark_lock(curr, hlock,
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					LOCK_ENABLED_HARDIRQ))
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				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
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2508
						LOCK_ENABLED_SOFTIRQ))
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					return 0;
		}
	}

2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528
	/*
	 * 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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2529 2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554
	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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2555 2556
}

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2557
#else
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2558

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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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2562
{
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2563 2564 2565
	WARN_ON(1);
	return 1;
}
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2566

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2567 2568 2569 2570 2571
static inline int mark_irqflags(struct task_struct *curr,
		struct held_lock *hlock)
{
	return 1;
}
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2572

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2573 2574 2575 2576
static inline int separate_irq_context(struct task_struct *curr,
		struct held_lock *hlock)
{
	return 0;
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2577 2578
}

2579 2580 2581 2582
void lockdep_trace_alloc(gfp_t gfp_mask)
{
}

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2583
#endif
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2584 2585

/*
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2586
 * Mark a lock with a usage bit, and validate the state transition:
I
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2587
 */
2588
static int mark_lock(struct task_struct *curr, struct held_lock *this,
2589
			     enum lock_usage_bit new_bit)
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Ingo Molnar 已提交
2590
{
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2591
	unsigned int new_mask = 1 << new_bit, ret = 1;
I
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2592 2593

	/*
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2594 2595
	 * If already set then do not dirty the cacheline,
	 * nor do any checks:
I
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2596
	 */
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2597
	if (likely(hlock_class(this)->usage_mask & new_mask))
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2598 2599 2600 2601
		return 1;

	if (!graph_lock())
		return 0;
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2602
	/*
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2603
	 * Make sure we didnt race:
I
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2604
	 */
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2605
	if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
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2606 2607 2608
		graph_unlock();
		return 1;
	}
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2609

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2610
	hlock_class(this)->usage_mask |= new_mask;
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2611

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2612
	if (!save_trace(hlock_class(this)->usage_traces + new_bit))
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2613
		return 0;
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2614

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2615
	switch (new_bit) {
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#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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2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635
		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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2636

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2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650
	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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2651 2652 2653 2654 2655

/*
 * Initialize a lock instance's lock-class mapping info:
 */
void lockdep_init_map(struct lockdep_map *lock, const char *name,
2656
		      struct lock_class_key *key, int subclass)
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2657
{
2658 2659 2660 2661 2662 2663 2664
	lock->class_cache = NULL;
#ifdef CONFIG_LOCK_STAT
	lock->cpu = raw_smp_processor_id();
#endif

	if (DEBUG_LOCKS_WARN_ON(!name)) {
		lock->name = "NULL";
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Ingo Molnar 已提交
2665
		return;
2666 2667 2668
	}

	lock->name = name;
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2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680

	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;
2681 2682 2683 2684

	if (unlikely(!debug_locks))
		return;

2685 2686
	if (subclass)
		register_lock_class(lock, subclass, 1);
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2687 2688 2689 2690 2691 2692 2693 2694 2695
}
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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2696
			  struct lockdep_map *nest_lock, unsigned long ip)
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2697 2698
{
	struct task_struct *curr = current;
2699
	struct lock_class *class = NULL;
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2700 2701 2702 2703 2704
	struct held_lock *hlock;
	unsigned int depth, id;
	int chain_head = 0;
	u64 chain_key;

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2705 2706 2707
	if (!prove_locking)
		check = 1;

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2708 2709 2710 2711 2712 2713 2714 2715 2716 2717
	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");
2718
		dump_stack();
I
Ingo Molnar 已提交
2719 2720 2721
		return 0;
	}

2722 2723 2724 2725 2726
	if (!subclass)
		class = lock->class_cache;
	/*
	 * Not cached yet or subclass?
	 */
I
Ingo Molnar 已提交
2727
	if (unlikely(!class)) {
2728
		class = register_lock_class(lock, subclass, 0);
I
Ingo Molnar 已提交
2729 2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750
		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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2751 2752 2753
	if (DEBUG_LOCKS_WARN_ON(!class))
		return 0;
	hlock->class_idx = class - lock_classes + 1;
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2754 2755
	hlock->acquire_ip = ip;
	hlock->instance = lock;
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2756
	hlock->nest_lock = nest_lock;
I
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2757 2758 2759
	hlock->trylock = trylock;
	hlock->read = read;
	hlock->check = check;
2760
	hlock->hardirqs_off = !!hardirqs_off;
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2761 2762 2763 2764
#ifdef CONFIG_LOCK_STAT
	hlock->waittime_stamp = 0;
	hlock->holdtime_stamp = sched_clock();
#endif
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2765

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2766 2767 2768
	if (check == 2 && !mark_irqflags(curr, hlock))
		return 0;

I
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2769
	/* mark it as used: */
2770
	if (!mark_lock(curr, hlock, LOCK_USED))
I
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2771
		return 0;
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2772

I
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2773
	/*
2774
	 * Calculate the chain hash: it's the combined hash of all the
I
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2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794
	 * 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;
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2795 2796 2797
	if (separate_irq_context(curr, hlock)) {
		chain_key = 0;
		chain_head = 1;
I
Ingo Molnar 已提交
2798 2799 2800
	}
	chain_key = iterate_chain_key(chain_key, id);

2801
	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
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2802
		return 0;
2803

2804
	curr->curr_chain_key = chain_key;
I
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2805 2806
	curr->lockdep_depth++;
	check_chain_key(curr);
2807 2808 2809 2810
#ifdef CONFIG_DEBUG_LOCKDEP
	if (unlikely(!debug_locks))
		return 0;
#endif
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2811 2812 2813 2814
	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");
2815
		dump_stack();
I
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2816 2817
		return 0;
	}
2818

I
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2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837
	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 (",
2838
		curr->comm, task_pid_nr(curr));
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2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867 2868
	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;
}

2869
static int
2870 2871 2872
__lock_set_class(struct lockdep_map *lock, const char *name,
		 struct lock_class_key *key, unsigned int subclass,
		 unsigned long ip)
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
{
	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:
2899
	lockdep_init_map(lock, name, key, 0);
2900
	class = register_lock_class(lock, subclass, 0);
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	hlock->class_idx = class - lock_classes + 1;
2902 2903 2904 2905 2906 2907 2908

	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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2909
			hlock_class(hlock)->subclass, hlock->trylock,
2910
				hlock->read, hlock->check, hlock->hardirqs_off,
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2911
				hlock->nest_lock, hlock->acquire_ip))
2912 2913 2914 2915 2916 2917 2918 2919
			return 0;
	}

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

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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 2954 2955 2956
/*
 * 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:
P
Peter Zijlstra 已提交
2957 2958
	lock_release_holdtime(hlock);

I
Ingo Molnar 已提交
2959 2960 2961 2962 2963 2964 2965 2966 2967 2968 2969
	/*
	 * 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
Dave Jones 已提交
2970
			hlock_class(hlock)->subclass, hlock->trylock,
I
Ingo Molnar 已提交
2971
				hlock->read, hlock->check, hlock->hardirqs_off,
P
Peter Zijlstra 已提交
2972
				hlock->nest_lock, hlock->acquire_ip))
I
Ingo Molnar 已提交
2973 2974 2975 2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010
			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
3011 3012
	lock_release_holdtime(hlock);

I
Ingo Molnar 已提交
3013 3014
#ifdef CONFIG_DEBUG_LOCKDEP
	hlock->prev_chain_key = 0;
D
Dave Jones 已提交
3015
	hlock->class_idx = 0;
I
Ingo Molnar 已提交
3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 3030 3031 3032 3033 3034 3035 3036 3037 3038 3039 3040 3041 3042 3043 3044 3045 3046 3047 3048 3049
	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:
 */
3050
static void check_flags(unsigned long flags)
I
Ingo Molnar 已提交
3051
{
3052 3053
#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
    defined(CONFIG_TRACE_IRQFLAGS)
I
Ingo Molnar 已提交
3054 3055 3056
	if (!debug_locks)
		return;

3057 3058 3059 3060 3061 3062 3063 3064 3065
	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
3066 3067 3068 3069 3070 3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081 3082 3083

	/*
	 * 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
}

3084 3085 3086
void lock_set_class(struct lockdep_map *lock, const char *name,
		    struct lock_class_key *key, unsigned int subclass,
		    unsigned long ip)
3087 3088 3089 3090 3091 3092 3093 3094 3095
{
	unsigned long flags;

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

	raw_local_irq_save(flags);
	current->lockdep_recursion = 1;
	check_flags(flags);
3096
	if (__lock_set_class(lock, name, key, subclass, ip))
3097 3098 3099 3100
		check_chain_key(current);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
3101
EXPORT_SYMBOL_GPL(lock_set_class);
3102

I
Ingo Molnar 已提交
3103 3104 3105 3106
/*
 * We are not always called with irqs disabled - do that here,
 * and also avoid lockdep recursion:
 */
3107
void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
P
Peter Zijlstra 已提交
3108 3109
			  int trylock, int read, int check,
			  struct lockdep_map *nest_lock, unsigned long ip)
I
Ingo Molnar 已提交
3110 3111 3112
{
	unsigned long flags;

3113 3114
	trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);

I
Ingo Molnar 已提交
3115 3116 3117 3118 3119 3120 3121 3122
	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
3123
		       irqs_disabled_flags(flags), nest_lock, ip);
I
Ingo Molnar 已提交
3124 3125 3126 3127 3128
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquire);

3129
void lock_release(struct lockdep_map *lock, int nested,
3130
			  unsigned long ip)
I
Ingo Molnar 已提交
3131 3132 3133
{
	unsigned long flags;

3134 3135
	trace_lock_release(lock, nested, ip);

I
Ingo Molnar 已提交
3136 3137 3138 3139 3140 3141 3142 3143 3144 3145 3146 3147
	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);

3148 3149 3150 3151 3152 3153 3154 3155 3156 3157
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
3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171
#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 (",
3172
		curr->comm, task_pid_nr(curr));
P
Peter Zijlstra 已提交
3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192
	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
3193
	int i, contention_point, contending_point;
P
Peter Zijlstra 已提交
3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215 3216

	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
3217 3218 3219
	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
3220

D
Dave Jones 已提交
3221
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3222 3223 3224 3225
	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
3226 3227
	if (lock->cpu != smp_processor_id())
		stats->bounces[bounce_contended + !!hlock->read]++;
P
Peter Zijlstra 已提交
3228 3229 3230 3231
	put_lock_stats(stats);
}

static void
P
Peter Zijlstra 已提交
3232
__lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3233 3234 3235 3236 3237 3238
{
	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
3239 3240
	s64 waittime = 0;
	int i, cpu;
P
Peter Zijlstra 已提交
3241 3242 3243 3244 3245 3246 3247 3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261

	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
3262 3263 3264 3265 3266 3267
	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
3268

3269 3270
	trace_lock_acquired(lock, ip, waittime);

D
Dave Jones 已提交
3271
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3272 3273 3274 3275 3276 3277 3278 3279
	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
3280
	put_lock_stats(stats);
P
Peter Zijlstra 已提交
3281 3282

	lock->cpu = cpu;
P
Peter Zijlstra 已提交
3283
	lock->ip = ip;
P
Peter Zijlstra 已提交
3284 3285 3286 3287 3288 3289
}

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

3290 3291
	trace_lock_contended(lock, ip);

P
Peter Zijlstra 已提交
3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306
	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
3307
void lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318 3319
{
	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
3320
	__lock_acquired(lock, ip);
P
Peter Zijlstra 已提交
3321 3322 3323 3324 3325 3326
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquired);
#endif

I
Ingo Molnar 已提交
3327 3328 3329 3330 3331 3332 3333 3334
/*
 * Used by the testsuite, sanitize the validator state
 * after a simulated failure:
 */

void lockdep_reset(void)
{
	unsigned long flags;
3335
	int i;
I
Ingo Molnar 已提交
3336 3337 3338 3339 3340 3341 3342 3343 3344 3345

	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;
3346 3347
	for (i = 0; i < CHAINHASH_SIZE; i++)
		INIT_LIST_HEAD(chainhash_table + i);
I
Ingo Molnar 已提交
3348 3349 3350 3351 3352 3353 3354 3355 3356 3357 3358 3359 3360 3361 3362 3363 3364 3365 3366 3367 3368
	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);

3369
	class->key = NULL;
I
Ingo Molnar 已提交
3370 3371
}

3372
static inline int within(const void *addr, void *start, unsigned long size)
I
Ingo Molnar 已提交
3373 3374 3375 3376 3377 3378 3379 3380 3381 3382
{
	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;
3383
	int locked;
I
Ingo Molnar 已提交
3384 3385

	raw_local_irq_save(flags);
3386
	locked = graph_lock();
I
Ingo Molnar 已提交
3387 3388 3389 3390 3391 3392 3393 3394

	/*
	 * 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;
3395
		list_for_each_entry_safe(class, next, head, hash_entry) {
I
Ingo Molnar 已提交
3396 3397
			if (within(class->key, start, size))
				zap_class(class);
3398 3399 3400
			else if (within(class->name, start, size))
				zap_class(class);
		}
I
Ingo Molnar 已提交
3401 3402
	}

3403 3404
	if (locked)
		graph_unlock();
I
Ingo Molnar 已提交
3405 3406 3407 3408 3409
	raw_local_irq_restore(flags);
}

void lockdep_reset_lock(struct lockdep_map *lock)
{
3410
	struct lock_class *class, *next;
I
Ingo Molnar 已提交
3411 3412 3413
	struct list_head *head;
	unsigned long flags;
	int i, j;
3414
	int locked;
I
Ingo Molnar 已提交
3415 3416 3417 3418

	raw_local_irq_save(flags);

	/*
3419 3420 3421 3422 3423 3424 3425 3426 3427 3428 3429 3430 3431
	 * 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
3432
	 */
3433
	locked = graph_lock();
I
Ingo Molnar 已提交
3434 3435 3436 3437 3438
	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) {
3439
			if (unlikely(class == lock->class_cache)) {
3440 3441
				if (debug_locks_off_graph_unlock())
					WARN_ON(1);
3442
				goto out_restore;
I
Ingo Molnar 已提交
3443 3444 3445
			}
		}
	}
3446 3447
	if (locked)
		graph_unlock();
3448 3449

out_restore:
I
Ingo Molnar 已提交
3450 3451 3452
	raw_local_irq_restore(flags);
}

3453
void lockdep_init(void)
I
Ingo Molnar 已提交
3454 3455 3456 3457 3458 3459 3460 3461 3462 3463 3464 3465 3466 3467 3468 3469 3470 3471 3472 3473 3474 3475 3476 3477 3478
{
	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");

3479
	printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
I
Ingo Molnar 已提交
3480 3481
	printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
	printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3482
	printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
I
Ingo Molnar 已提交
3483 3484 3485 3486 3487 3488 3489 3490 3491
	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 +
3492 3493 3494 3495 3496
		sizeof(struct list_head) * CHAINHASH_SIZE) / 1024
#ifdef CONFIG_PROVE_LOCKING
		+ sizeof(struct circular_queue) + sizeof(bfs_accessed)
#endif
		);
I
Ingo Molnar 已提交
3497 3498 3499 3500 3501

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

#ifdef CONFIG_DEBUG_LOCKDEP
3502 3503 3504 3505 3506
	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
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#endif
}

static void
print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3512
		     const void *mem_to, struct held_lock *hlock)
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Ingo Molnar 已提交
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{
	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",
3523
		curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3524
	print_lock(hlock);
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	lockdep_print_held_locks(curr);

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

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Oleg Nesterov 已提交
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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;
}

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/*
 * 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;

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		if (not_in_range(mem_from, mem_len, hlock->instance,
					sizeof(*hlock->instance)))
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			continue;

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		print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
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		break;
	}
	local_irq_restore(flags);
}
3566
EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
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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",
3579
		curr->comm, task_pid_nr(curr));
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Ingo Molnar 已提交
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	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;

3598 3599 3600 3601
	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;
3622 3623 3624
	} 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);

3650 3651 3652 3653 3654
/*
 * 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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Ingo Molnar 已提交
3655
{
3656 3657 3658 3659
	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
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	lockdep_print_held_locks(task);
}
3662 3663 3664 3665 3666 3667
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);
	}
}