lockdep.c 85.4 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 <asm/sections.h>

#include "lockdep_internals.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;
static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];

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

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static inline struct lock_class *hlock_class(struct held_lock *hlock)
{
	if (!hlock->class_idx) {
		DEBUG_LOCKS_WARN_ON(1);
		return NULL;
	}
	return lock_classes + hlock->class_idx - 1;
}

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

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

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

	return i;
}

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

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

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

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static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
{
	dst->min += src->min;
	dst->max += src->max;
	dst->total += src->total;
	dst->nr += src->nr;
}

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

	memset(&stats, 0, sizeof(struct lock_class_stats));
	for_each_possible_cpu(cpu) {
		struct lock_class_stats *pcs =
			&per_cpu(lock_stats, cpu)[class - lock_classes];

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

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

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		lock_time_add(&pcs->read_waittime, &stats.read_waittime);
		lock_time_add(&pcs->write_waittime, &stats.write_waittime);

		lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
		lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
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		for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
			stats.bounces[i] += pcs->bounces[i];
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	}

	return stats;
}

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

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

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

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

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

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

	if (!lock_stat)
		return;

	holdtime = sched_clock() - hlock->holdtime_stamp;

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	stats = get_lock_stats(hlock_class(hlock));
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	if (hlock->read)
		lock_time_inc(&stats->read_holdtime, holdtime);
	else
		lock_time_inc(&stats->write_holdtime, holdtime);
	put_lock_stats(stats);
}
#else
static inline void lock_release_holdtime(struct held_lock *hlock)
{
}
#endif

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/*
 * We keep a global list of all lock classes. The list only grows,
 * never shrinks. The list is only accessed with the lockdep
 * spinlock lock held.
 */
LIST_HEAD(all_lock_classes);

/*
 * The lockdep classes are in a hash-table as well, for fast lookup:
 */
#define CLASSHASH_BITS		(MAX_LOCKDEP_KEYS_BITS - 1)
#define CLASSHASH_SIZE		(1UL << CLASSHASH_BITS)
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#define __classhashfn(key)	hash_long((unsigned long)key, CLASSHASH_BITS)
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#define classhashentry(key)	(classhash_table + __classhashfn((key)))

static struct list_head classhash_table[CLASSHASH_SIZE];

/*
 * We put the lock dependency chains into a hash-table as well, to cache
 * their existence:
 */
#define CHAINHASH_BITS		(MAX_LOCKDEP_CHAINS_BITS-1)
#define CHAINHASH_SIZE		(1UL << CHAINHASH_BITS)
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#define __chainhashfn(chain)	hash_long(chain, CHAINHASH_BITS)
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#define chainhashentry(chain)	(chainhash_table + __chainhashfn((chain)))

static struct list_head chainhash_table[CHAINHASH_SIZE];

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

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

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

/*
 * Debugging switches:
 */

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

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

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

/*
 * Stack-trace: tightly packed array of stack backtrace
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 * addresses. Protected by the graph_lock.
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 */
unsigned long nr_stack_trace_entries;
static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];

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

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	trace->skip = 3;

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

	nr_stack_trace_entries += trace->nr_entries;

	if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
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		if (!debug_locks_off_graph_unlock())
			return 0;

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

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		return 0;
	}

	return 1;
}

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

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static unsigned int lockdep_dependency_gen_id;

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

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#ifdef CONFIG_DEBUG_LOCKDEP
/*
 * We cannot printk in early bootup code. Not even early_printk()
 * might work. So we mark any initialization errors and printk
 * about it later on, in lockdep_info().
 */
static int lockdep_init_error;
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static unsigned long lockdep_init_trace_data[20];
static struct stack_trace lockdep_init_trace = {
	.max_entries = ARRAY_SIZE(lockdep_init_trace_data),
	.entries = lockdep_init_trace_data,
};
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/*
 * Various lockdep statistics:
 */
atomic_t chain_lookup_hits;
atomic_t chain_lookup_misses;
atomic_t hardirqs_on_events;
atomic_t hardirqs_off_events;
atomic_t redundant_hardirqs_on;
atomic_t redundant_hardirqs_off;
atomic_t softirqs_on_events;
atomic_t softirqs_off_events;
atomic_t redundant_softirqs_on;
atomic_t redundant_softirqs_off;
atomic_t nr_unused_locks;
atomic_t nr_cyclic_checks;
atomic_t nr_cyclic_check_recursions;
atomic_t nr_find_usage_forwards_checks;
atomic_t nr_find_usage_forwards_recursions;
atomic_t nr_find_usage_backwards_checks;
atomic_t nr_find_usage_backwards_recursions;
# define debug_atomic_inc(ptr)		atomic_inc(ptr)
# define debug_atomic_dec(ptr)		atomic_dec(ptr)
# define debug_atomic_read(ptr)		atomic_read(ptr)
#else
# define debug_atomic_inc(ptr)		do { } while (0)
# define debug_atomic_dec(ptr)		do { } while (0)
# define debug_atomic_read(ptr)		0
#endif

/*
 * Locking printouts:
 */

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#define __STR(foo)	#foo
#define STR(foo)	__STR(foo)

#define __USAGE(__STATE)						\
	[LOCK_USED_IN_##__STATE] = "IN-"STR(__STATE)"-W",		\
	[LOCK_ENABLED_##__STATE] = STR(__STATE)"-ON-W",			\
	[LOCK_USED_IN_##__STATE##_READ] = "IN-"STR(__STATE)"-R",	\
	[LOCK_ENABLED_##__STATE##_READ] = STR(__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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}

void
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get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3,
					char *c4, char *c5, char *c6)
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{
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	*c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.', *c5 = '.', *c6 = '.';
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	if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
		*c1 = '+';
	else
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		if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
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			*c1 = '-';

	if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
		*c2 = '+';
	else
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		if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
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			*c2 = '-';

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	if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
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		*c3 = '-';
	if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
		*c3 = '+';
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		if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
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			*c3 = '?';
	}

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	if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
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		*c4 = '-';
	if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
		*c4 = '+';
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		if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
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			*c4 = '?';
	}
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	if (class->usage_mask & LOCKF_USED_IN_RECLAIM_FS)
		*c5 = '+';
	else
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		if (class->usage_mask & LOCKF_ENABLED_RECLAIM_FS)
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			*c5 = '-';

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	if (class->usage_mask & LOCKF_ENABLED_RECLAIM_FS_READ)
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		*c6 = '-';
	if (class->usage_mask & LOCKF_USED_IN_RECLAIM_FS_READ) {
		*c6 = '+';
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		if (class->usage_mask & LOCKF_ENABLED_RECLAIM_FS_READ)
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			*c6 = '?';
	}

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}

static void print_lock_name(struct lock_class *class)
{
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	char str[KSYM_NAME_LEN], c1, c2, c3, c4, c5, c6;
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	const char *name;

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	get_usage_chars(class, &c1, &c2, &c3, &c4, &c5, &c6);
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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("){%c%c%c%c%c%c}", c1, c2, c3, c4, c5, c6);
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}

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

	printk("%s", name);
}

static void print_lock(struct held_lock *hlock)
{
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	print_lock_name(hlock_class(hlock));
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	printk(", at: ");
	print_ip_sym(hlock->acquire_ip);
}

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

	if (!depth) {
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		printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
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		return;
	}
	printk("%d lock%s held by %s/%d:\n",
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		depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
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	for (i = 0; i < depth; i++) {
		printk(" #%d: ", i);
		print_lock(curr->held_locks + i);
	}
}

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

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

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

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

/*
 * printk all lock dependencies starting at <entry>:
 */
604 605
static void __used
print_lock_dependencies(struct lock_class *class, int depth)
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{
	struct lock_list *entry;

609 610 611
	if (lockdep_dependency_visit(class, depth))
		return;

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

	print_lock_class_header(class, depth);

	list_for_each_entry(entry, &class->locks_after, entry) {
618 619 620
		if (DEBUG_LOCKS_WARN_ON(!entry->class))
			return;

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

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

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static void print_kernel_version(void)
{
	printk("%s %.*s\n", init_utsname()->release,
		(int)strcspn(init_utsname()->version, " "),
		init_utsname()->version);
}

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

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/*
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 * Is this the address of a static object:
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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;
	}
674
#endif
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	/*
	 * module var?
	 */
	return is_module_address(addr);
680 681
}

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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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	if (!new_class->name)
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		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);
	}
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	return count + 1;
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}

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/*
 * Register a lock's class in the hash-table, if the class is not present
 * yet. Otherwise we look it up. We cache the result in the lock object
 * itself, so actual lookup of the hash should be once per lock object.
 */
static inline struct lock_class *
look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
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{
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	struct lockdep_subclass_key *key;
	struct list_head *hash_head;
	struct lock_class *class;
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#ifdef CONFIG_DEBUG_LOCKDEP
	/*
	 * If the architecture calls into lockdep before initializing
	 * the hashes then we'll warn about it later. (we cannot printk
	 * right now)
	 */
	if (unlikely(!lockdep_initialized)) {
		lockdep_init();
		lockdep_init_error = 1;
725
		save_stack_trace(&lockdep_init_trace);
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	}
#endif
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	/*
	 * Static locks do not have their class-keys yet - for them the key
	 * is the lock object itself:
	 */
	if (unlikely(!lock->key))
		lock->key = (void *)lock;
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	/*
	 * NOTE: the class-key must be unique. For dynamic locks, a static
	 * lock_class_key variable is passed in through the mutex_init()
	 * (or spin_lock_init()) call - which acts as the key. For static
	 * locks we use the lock object itself as the key.
	 */
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	BUILD_BUG_ON(sizeof(struct lock_class_key) >
			sizeof(struct lockdep_map));
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	key = lock->key->subkeys + subclass;
746

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	hash_head = classhashentry(key);
748

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	/*
	 * 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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	list_for_each_entry(class, hash_head, hash_entry) {
		if (class->key == key) {
			WARN_ON_ONCE(class->name != lock->name);
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			return class;
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		}
	}
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	return NULL;
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}

/*
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 * Register a lock's class in the hash-table, if the class is not present
 * yet. Otherwise we look it up. We cache the result in the lock object
 * itself, so actual lookup of the hash should be once per lock object.
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 */
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static inline struct lock_class *
register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
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{
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	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");
		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);
837 838 839 840
	/*
	 * Add it to the global list of classes:
	 */
	list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
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	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");
		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;

907 908
	entry->class = this;
	entry->distance = distance;
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	/*
	 * 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;
}

/*
 * Recursive, forwards-direction lock-dependency checking, used for
 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
 * checking.
 *
 * (to keep the stackframe of the recursive functions small we
 *  use these global variables, and we also mark various helper
 *  functions as noinline.)
 */
static struct held_lock *check_source, *check_target;

/*
 * Print a dependency chain entry (this is only done when a deadlock
 * has been detected):
 */
static noinline int
print_circular_bug_entry(struct lock_list *target, unsigned int depth)
{
	if (debug_locks_silent)
		return 0;
	printk("\n-> #%u", depth);
	print_lock_name(target->class);
	printk(":\n");
	print_stack_trace(&target->trace, 6);

	return 0;
}

/*
 * When a circular dependency is detected, print the
 * header first:
 */
static noinline int
print_circular_bug_header(struct lock_list *entry, unsigned int depth)
{
	struct task_struct *curr = current;

	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
		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",
966
		curr->comm, task_pid_nr(curr));
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	print_lock(check_source);
	printk("\nbut task is already holding lock:\n");
	print_lock(check_target);
	printk("\nwhich lock already depends on the new lock.\n\n");
	printk("\nthe existing dependency chain (in reverse order) is:\n");

	print_circular_bug_entry(entry, depth);

	return 0;
}

static noinline int print_circular_bug_tail(void)
{
	struct task_struct *curr = current;
	struct lock_list this;

	if (debug_locks_silent)
		return 0;

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	this.class = hlock_class(check_source);
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	if (!save_trace(&this.trace))
		return 0;

	print_circular_bug_entry(&this, 0);

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

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

	return 0;
}

#define RECURSION_LIMIT 40

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

	WARN_ON(1);

	return 0;
}

1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073
unsigned long __lockdep_count_forward_deps(struct lock_class *class,
					   unsigned int depth)
{
	struct lock_list *entry;
	unsigned long ret = 1;

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

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

	return ret;
}

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

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

	return ret;
}

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

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

	return ret;
}

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

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

	return ret;
}

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/*
 * Prove that the dependency graph starting at <entry> can not
 * lead to <target>. Print an error and return 0 if it does.
 */
static noinline int
check_noncircular(struct lock_class *source, unsigned int depth)
{
	struct lock_list *entry;

1083 1084 1085
	if (lockdep_dependency_visit(source, depth))
		return 1;

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	debug_atomic_inc(&nr_cyclic_check_recursions);
	if (depth > max_recursion_depth)
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		max_recursion_depth = depth;
1089
	if (depth >= RECURSION_LIMIT)
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		return print_infinite_recursion_bug();
	/*
	 * Check this lock's dependency list:
	 */
	list_for_each_entry(entry, &source->locks_after, entry) {
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		if (entry->class == hlock_class(check_target))
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			return print_circular_bug_header(entry, depth+1);
		debug_atomic_inc(&nr_cyclic_checks);
		if (!check_noncircular(entry->class, depth+1))
			return print_circular_bug_entry(entry, depth+1);
	}
	return 1;
}

1104
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
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/*
 * Forwards and backwards subgraph searching, for the purposes of
 * proving that two subgraphs can be connected by a new dependency
 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
 */
static enum lock_usage_bit find_usage_bit;
static struct lock_class *forwards_match, *backwards_match;

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

1129 1130 1131
	if (lockdep_dependency_visit(source, depth))
		return 1;

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	if (depth > max_recursion_depth)
		max_recursion_depth = depth;
1134
	if (depth >= RECURSION_LIMIT)
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		return print_infinite_recursion_bug();

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

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

/*
 * Find a node in the backwards-direction dependency sub-graph starting
 * at <source> that matches <find_usage_bit>.
 *
 * Return 2 if such a node exists in the subgraph, and put that node
 * into <backwards_match>.
 *
 * Return 1 otherwise and keep <backwards_match> unchanged.
 * Return 0 on error.
 */
1165
static noinline int
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find_usage_backwards(struct lock_class *source, unsigned int depth)
{
	struct lock_list *entry;
	int ret;

1171 1172 1173
	if (lockdep_dependency_visit(source, depth))
		return 1;

1174 1175 1176
	if (!__raw_spin_is_locked(&lockdep_lock))
		return DEBUG_LOCKS_WARN_ON(1);

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	if (depth > max_recursion_depth)
		max_recursion_depth = depth;
1179
	if (depth >= RECURSION_LIMIT)
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		return print_infinite_recursion_bug();

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

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	if (!source && debug_locks_off_graph_unlock()) {
		WARN_ON(1);
		return 0;
	}

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

static int
print_bad_irq_dependency(struct task_struct *curr,
			 struct held_lock *prev,
			 struct held_lock *next,
			 enum lock_usage_bit bit1,
			 enum lock_usage_bit bit2,
			 const char *irqclass)
{
1213
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
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1214 1215 1216 1217 1218
		return 0;

	printk("\n======================================================\n");
	printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
		irqclass, irqclass);
1219
	print_kernel_version();
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1220 1221
	printk(  "------------------------------------------------------\n");
	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1222
		curr->comm, task_pid_nr(curr),
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Ingo Molnar 已提交
1223 1224 1225 1226 1227 1228 1229 1230 1231
		curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
		curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
		curr->hardirqs_enabled,
		curr->softirqs_enabled);
	print_lock(next);

	printk("\nand this task is already holding:\n");
	print_lock(prev);
	printk("which would create a new lock dependency:\n");
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	print_lock_name(hlock_class(prev));
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1233
	printk(" ->");
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	print_lock_name(hlock_class(next));
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1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274
	printk("\n");

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

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

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

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

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

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

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

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

	return 0;
}

static int
check_usage(struct task_struct *curr, struct held_lock *prev,
	    struct held_lock *next, enum lock_usage_bit bit_backwards,
	    enum lock_usage_bit bit_forwards, const char *irqclass)
{
	int ret;

	find_usage_bit = bit_backwards;
	/* fills in <backwards_match> */
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	ret = find_usage_backwards(hlock_class(prev), 0);
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1276 1277 1278 1279
	if (!ret || ret == 1)
		return ret;

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

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static int
check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
		struct held_lock *next)
{
	/*
	 * Prove that the new dependency does not connect a hardirq-safe
	 * lock with a hardirq-unsafe lock - to achieve this we search
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
	if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
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1299
					LOCK_ENABLED_HARDIRQ, "hard"))
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		return 0;

	/*
	 * Prove that the new dependency does not connect a hardirq-safe-read
	 * lock with a hardirq-unsafe lock - to achieve this we search
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
	if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
P
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1309
					LOCK_ENABLED_HARDIRQ, "hard-read"))
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1310 1311 1312 1313 1314 1315 1316 1317 1318
		return 0;

	/*
	 * Prove that the new dependency does not connect a softirq-safe
	 * lock with a softirq-unsafe lock - to achieve this we search
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
	if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
P
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1319
					LOCK_ENABLED_SOFTIRQ, "soft"))
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		return 0;
	/*
	 * Prove that the new dependency does not connect a softirq-safe-read
	 * lock with a softirq-unsafe lock - to achieve this we search
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
	if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
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1328
					LOCK_ENABLED_SOFTIRQ, "soft"))
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1329 1330
		return 0;

1331 1332 1333 1334 1335 1336 1337
	/*
	 * Prove that the new dependency does not connect a reclaim-fs-safe
	 * lock with a reclaim-fs-unsafe lock - to achieve this we search
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
	if (!check_usage(curr, prev, next, LOCK_USED_IN_RECLAIM_FS,
1338
					LOCK_ENABLED_RECLAIM_FS, "reclaim-fs"))
1339 1340 1341 1342 1343 1344 1345 1346 1347
		return 0;

	/*
	 * Prove that the new dependency does not connect a reclaim-fs-safe-read
	 * lock with a reclaim-fs-unsafe lock - to achieve this we search
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
	if (!check_usage(curr, prev, next, LOCK_USED_IN_RECLAIM_FS_READ,
1348
					LOCK_ENABLED_RECLAIM_FS, "reclaim-fs-read"))
1349 1350
		return 0;

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1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379
	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++;
}

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1380 1381 1382 1383 1384 1385
#endif

static int
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
		   struct held_lock *next)
{
1386
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
1387 1388 1389 1390
		return 0;

	printk("\n=============================================\n");
	printk(  "[ INFO: possible recursive locking detected ]\n");
1391
	print_kernel_version();
I
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1392 1393
	printk(  "---------------------------------------------\n");
	printk("%s/%d is trying to acquire lock:\n",
1394
		curr->comm, task_pid_nr(curr));
I
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1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420
	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;
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Peter Zijlstra 已提交
1421
	struct held_lock *nest = NULL;
I
Ingo Molnar 已提交
1422 1423 1424 1425
	int i;

	for (i = 0; i < curr->lockdep_depth; i++) {
		prev = curr->held_locks + i;
P
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1426 1427 1428 1429

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

D
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1430
		if (hlock_class(prev) != hlock_class(next))
I
Ingo Molnar 已提交
1431
			continue;
P
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1432

I
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1433 1434
		/*
		 * Allow read-after-read recursion of the same
1435
		 * lock class (i.e. read_lock(lock)+read_lock(lock)):
I
Ingo Molnar 已提交
1436
		 */
1437
		if ((read == 2) && prev->read)
I
Ingo Molnar 已提交
1438
			return 2;
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1439 1440 1441 1442 1443 1444 1445 1446

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

I
Ingo Molnar 已提交
1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475
		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,
1476
	       struct held_lock *next, int distance)
I
Ingo Molnar 已提交
1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491
{
	struct lock_list *entry;
	int ret;

	/*
	 * Prove that the new <prev> -> <next> dependency would not
	 * create a circular dependency in the graph. (We do this by
	 * forward-recursing into the graph starting at <next>, and
	 * checking whether we can reach <prev>.)
	 *
	 * We are using global variables to control the recursion, to
	 * keep the stackframe size of the recursive functions low:
	 */
	check_source = next;
	check_target = prev;
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1492
	if (!(check_noncircular(hlock_class(next), 0)))
I
Ingo Molnar 已提交
1493 1494
		return print_circular_bug_tail();

P
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1495
	if (!check_prev_add_irq(curr, prev, next))
I
Ingo Molnar 已提交
1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515
		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.)
	 */
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1516 1517
	list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
		if (entry->class == hlock_class(next)) {
1518 1519
			if (distance == 1)
				entry->distance = 1;
I
Ingo Molnar 已提交
1520
			return 2;
1521
		}
I
Ingo Molnar 已提交
1522 1523 1524 1525 1526 1527
	}

	/*
	 * Ok, all validations passed, add the new lock
	 * to the previous lock's dependency list:
	 */
D
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1528 1529 1530
	ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
			       &hlock_class(prev)->locks_after,
			       next->acquire_ip, distance);
1531

I
Ingo Molnar 已提交
1532 1533
	if (!ret)
		return 0;
1534

D
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1535 1536 1537
	ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
			       &hlock_class(next)->locks_before,
			       next->acquire_ip, distance);
1538 1539
	if (!ret)
		return 0;
I
Ingo Molnar 已提交
1540 1541

	/*
P
Peter Zijlstra 已提交
1542 1543
	 * Debugging printouts:
	 */
D
Dave Jones 已提交
1544
	if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
P
Peter Zijlstra 已提交
1545 1546
		graph_unlock();
		printk("\n new dependency: ");
D
Dave Jones 已提交
1547
		print_lock_name(hlock_class(prev));
P
Peter Zijlstra 已提交
1548
		printk(" => ");
D
Dave Jones 已提交
1549
		print_lock_name(hlock_class(next));
P
Peter Zijlstra 已提交
1550
		printk("\n");
I
Ingo Molnar 已提交
1551
		dump_stack();
P
Peter Zijlstra 已提交
1552
		return graph_lock();
I
Ingo Molnar 已提交
1553
	}
P
Peter Zijlstra 已提交
1554 1555
	return 1;
}
I
Ingo Molnar 已提交
1556

P
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1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567
/*
 * 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;
1568

I
Ingo Molnar 已提交
1569
	/*
P
Peter Zijlstra 已提交
1570 1571 1572
	 * Debugging checks.
	 *
	 * Depth must not be zero for a non-head lock:
I
Ingo Molnar 已提交
1573
	 */
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1574 1575
	if (!depth)
		goto out_bug;
I
Ingo Molnar 已提交
1576
	/*
P
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1577 1578
	 * At least two relevant locks must exist for this
	 * to be a head:
I
Ingo Molnar 已提交
1579
	 */
P
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1580 1581 1582
	if (curr->held_locks[depth].irq_context !=
			curr->held_locks[depth-1].irq_context)
		goto out_bug;
1583

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1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601
	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;
1602
		}
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1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614
		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
1615
	}
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1616 1617 1618 1619
	return 1;
out_bug:
	if (!debug_locks_off_graph_unlock())
		return 0;
I
Ingo Molnar 已提交
1620

P
Peter Zijlstra 已提交
1621
	WARN_ON(1);
I
Ingo Molnar 已提交
1622

P
Peter Zijlstra 已提交
1623
	return 0;
I
Ingo Molnar 已提交
1624 1625
}

P
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1626
unsigned long nr_lock_chains;
1627
struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1628
int nr_chain_hlocks;
1629 1630 1631 1632 1633 1634
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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1635

I
Ingo Molnar 已提交
1636 1637
/*
 * Look up a dependency chain. If the key is not present yet then
1638 1639 1640
 * 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
1641
 */
1642 1643 1644
static inline int lookup_chain_cache(struct task_struct *curr,
				     struct held_lock *hlock,
				     u64 chain_key)
I
Ingo Molnar 已提交
1645
{
D
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1646
	struct lock_class *class = hlock_class(hlock);
I
Ingo Molnar 已提交
1647 1648
	struct list_head *hash_head = chainhashentry(chain_key);
	struct lock_chain *chain;
1649
	struct held_lock *hlock_curr, *hlock_next;
1650
	int i, j, n, cn;
I
Ingo Molnar 已提交
1651

1652 1653
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return 0;
I
Ingo Molnar 已提交
1654 1655 1656 1657 1658 1659 1660 1661
	/*
	 * 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);
1662
			if (very_verbose(class))
1663 1664 1665 1666
				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
1667 1668 1669
			return 0;
		}
	}
1670
	if (very_verbose(class))
1671 1672
		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
1673 1674 1675 1676
	/*
	 * Allocate a new chain entry from the static array, and add
	 * it to the hash:
	 */
1677 1678
	if (!graph_lock())
		return 0;
I
Ingo Molnar 已提交
1679 1680 1681 1682 1683
	/*
	 * 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) {
1684
			graph_unlock();
I
Ingo Molnar 已提交
1685 1686 1687 1688
			goto cache_hit;
		}
	}
	if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1689 1690 1691
		if (!debug_locks_off_graph_unlock())
			return 0;

I
Ingo Molnar 已提交
1692 1693 1694 1695 1696 1697
		printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
		printk("turning off the locking correctness validator.\n");
		return 0;
	}
	chain = lock_chains + nr_lock_chains++;
	chain->chain_key = chain_key;
1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708
	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;
1709 1710 1711 1712 1713 1714 1715 1716 1717
	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;
1718
		for (j = 0; j < chain->depth - 1; j++, i++) {
D
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1719
			int lock_id = curr->held_locks[i].class_idx - 1;
1720 1721 1722 1723
			chain_hlocks[chain->base + j] = lock_id;
		}
		chain_hlocks[chain->base + j] = class - lock_classes;
	}
I
Ingo Molnar 已提交
1724 1725
	list_add_tail_rcu(&chain->entry, hash_head);
	debug_atomic_inc(&chain_lookup_misses);
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1726 1727 1728 1729 1730 1731
	inc_chains();

	return 1;
}

static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1732
		struct held_lock *hlock, int chain_head, u64 chain_key)
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{
	/*
	 * 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) &&
1745
	    lookup_chain_cache(curr, hlock, chain_key)) {
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		/*
		 * 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;
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	return 1;
}
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#else
static inline int validate_chain(struct task_struct *curr,
	       	struct lockdep_map *lock, struct held_lock *hlock,
1787
		int chain_head, u64 chain_key)
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{
	return 1;
}
1791
#endif
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/*
 * We are building curr_chain_key incrementally, so double-check
 * it from scratch, to make sure that it's done correctly:
 */
1797
static void check_chain_key(struct task_struct *curr)
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{
#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();
1808
			WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
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				curr->lockdep_depth, i,
				(unsigned long long)chain_key,
				(unsigned long long)hlock->prev_chain_key);
			return;
		}
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		id = hlock->class_idx - 1;
1815 1816 1817
		if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
			return;

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		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();
1826
		WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
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			curr->lockdep_depth, i,
			(unsigned long long)chain_key,
			(unsigned long long)curr->curr_chain_key);
	}
#endif
}

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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",
1850
		curr->comm, task_pid_nr(curr),
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		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]);
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	print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
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	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)
{
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	if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
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		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);

1885
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
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/*
 * print irq inversion bug:
 */
static int
print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
			struct held_lock *this, int forwards,
			const char *irqclass)
{
1895
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
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		return 0;

	printk("\n=========================================================\n");
	printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
1900
	print_kernel_version();
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	printk(  "---------------------------------------------------------\n");
	printk("%s/%d just changed the state of lock:\n",
1903
		curr->comm, task_pid_nr(curr));
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	print_lock(this);
	if (forwards)
		printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
	else
		printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
	print_lock_name(other);
	printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");

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

	printk("\nthe first lock's dependencies:\n");
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	print_lock_dependencies(hlock_class(this), 0);
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1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938

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

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

	return 0;
}

/*
 * Prove that in the forwards-direction subgraph starting at <this>
 * there is no lock matching <mask>:
 */
static int
check_usage_forwards(struct task_struct *curr, struct held_lock *this,
		     enum lock_usage_bit bit, const char *irqclass)
{
	int ret;

	find_usage_bit = bit;
	/* fills in <forwards_match> */
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	ret = find_usage_forwards(hlock_class(this), 0);
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1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957
	if (!ret || ret == 1)
		return ret;

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

/*
 * Prove that in the backwards-direction subgraph starting at <this>
 * there is no lock matching <mask>:
 */
static int
check_usage_backwards(struct task_struct *curr, struct held_lock *this,
		      enum lock_usage_bit bit, const char *irqclass)
{
	int ret;

	find_usage_bit = bit;
	/* fills in <backwards_match> */
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	ret = find_usage_backwards(hlock_class(this), 0);
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	if (!ret || ret == 1)
		return ret;

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

1965
void print_irqtrace_events(struct task_struct *curr)
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1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977
{
	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);
}

1978
static int HARDIRQ_verbose(struct lock_class *class)
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1979
{
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#if HARDIRQ_VERBOSE
	return class_filter(class);
#endif
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	return 0;
}

1986
static int SOFTIRQ_verbose(struct lock_class *class)
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1987
{
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#if SOFTIRQ_VERBOSE
	return class_filter(class);
#endif
	return 0;
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}

1994
static int RECLAIM_FS_verbose(struct lock_class *class)
1995 1996 1997 1998 1999 2000 2001
{
#if RECLAIM_VERBOSE
	return class_filter(class);
#endif
	return 0;
}

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#define STRICT_READ_CHECKS	1

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027
static const char *state_names[] = {
#define LOCKDEP_STATE(__STATE) \
	STR(__STATE),
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

static inline const char *state_name(enum lock_usage_bit bit)
{
	return state_names[bit >> 2];
}

static const char *state_rnames[] = {
#define LOCKDEP_STATE(__STATE) \
	STR(__STATE)"-READ",
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

static inline const char *state_rname(enum lock_usage_bit bit)
{
	return state_rnames[bit >> 2];
}

2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040
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);
}

2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059
static int exclusive_bit(int new_bit)
{
	/*
	 * USED_IN
	 * USED_IN_READ
	 * ENABLED
	 * ENABLED_READ
	 *
	 * bit 0 - write/read
	 * bit 1 - used_in/enabled
	 * bit 2+  state
	 */

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

	return state | (dir ^ 2);
}

2060 2061 2062
typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
			     enum lock_usage_bit bit, const char *name);

2063
static int
2064
mark_lock_irq(struct task_struct *curr, struct held_lock *this, int new_bit)
2065
{
2066 2067 2068
	const char *name = state_name(new_bit);
	const char *rname = state_rname(new_bit);

2069
	int excl_bit = exclusive_bit(new_bit);
2070
	int read = new_bit & 1;
2071 2072 2073 2074
	int dir = new_bit & 2;

	check_usage_f usage = dir ?
		check_usage_backwards : check_usage_forwards;
2075

2076 2077
	if (!valid_state(curr, this, new_bit, excl_bit))
		return 0;
2078

2079
	if (!read && !valid_state(curr, this, new_bit, excl_bit + 1))
2080
		return 0;
2081

2082 2083
	if ((!read || (!dir || STRICT_READ_CHECKS)) &&
			!usage(curr, this, excl_bit, name))
2084
		return 0;
2085

2086 2087 2088
	if ((!read && STRICT_READ_CHECKS) &&
			!usage(curr, this, excl_bit + 1, rname))
		return 0;
2089

2090
	if (state_verbose(new_bit, hlock_class(this)))
2091 2092 2093 2094 2095
		return 2;

	return 1;
}

2096
enum mark_type {
2097 2098 2099
#define LOCKDEP_STATE(__STATE)	__STATE,
#include "lockdep_states.h"
#undef LOCKDEP_STATE
2100 2101
};

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/*
 * Mark all held locks with a usage bit:
 */
2105
static int
2106
mark_held_locks(struct task_struct *curr, enum mark_type mark)
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{
	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;

2115 2116 2117 2118 2119
		usage_bit = 2 + (mark << 2); /* ENABLED */
		if (hlock->read)
			usage_bit += 1; /* READ */

		BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2120

2121
		if (!mark_lock(curr, hlock, usage_bit))
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			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:
 */
2147
void trace_hardirqs_on_caller(unsigned long ip)
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2148 2149 2150
{
	struct task_struct *curr = current;

2151
	time_hardirqs_on(CALLER_ADDR0, ip);
2152

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2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173
	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:
	 */
2174
	if (!mark_held_locks(curr, HARDIRQ))
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		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)
2182
		if (!mark_held_locks(curr, SOFTIRQ))
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			return;

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	curr->hardirq_enable_ip = ip;
	curr->hardirq_enable_event = ++curr->irq_events;
	debug_atomic_inc(&hardirqs_on_events);
}
2189
EXPORT_SYMBOL(trace_hardirqs_on_caller);
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2191
void trace_hardirqs_on(void)
2192 2193 2194
{
	trace_hardirqs_on_caller(CALLER_ADDR0);
}
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EXPORT_SYMBOL(trace_hardirqs_on);

/*
 * Hardirqs were disabled:
 */
2200
void trace_hardirqs_off_caller(unsigned long ip)
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2201 2202 2203
{
	struct task_struct *curr = current;

2204
	time_hardirqs_off(CALLER_ADDR0, ip);
2205

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	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;
2217
		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);
}
2223
EXPORT_SYMBOL(trace_hardirqs_off_caller);
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2225
void trace_hardirqs_off(void)
2226 2227 2228
{
	trace_hardirqs_off_caller(CALLER_ADDR0);
}
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2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261
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)
2262
		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);
}

2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315
void lockdep_trace_alloc(gfp_t gfp_mask)
{
	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;

	if (DEBUG_LOCKS_WARN_ON(irqs_disabled()))
		return;

	mark_held_locks(curr, RECLAIM_FS);
}

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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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2344
					LOCK_ENABLED_HARDIRQ_READ))
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2345 2346 2347
				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
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2348
						LOCK_ENABLED_SOFTIRQ_READ))
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2349 2350 2351
					return 0;
		} else {
			if (!mark_lock(curr, hlock,
P
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2352
					LOCK_ENABLED_HARDIRQ))
P
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2353 2354 2355
				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
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2356
						LOCK_ENABLED_SOFTIRQ))
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					return 0;
		}
	}

2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376
	/*
	 * 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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2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402
	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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}

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2405
#else
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2406

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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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2410
{
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2411 2412 2413
	WARN_ON(1);
	return 1;
}
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2414

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2415 2416 2417 2418 2419
static inline int mark_irqflags(struct task_struct *curr,
		struct held_lock *hlock)
{
	return 1;
}
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2420

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2421 2422 2423 2424
static inline int separate_irq_context(struct task_struct *curr,
		struct held_lock *hlock)
{
	return 0;
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2425 2426
}

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2427
#endif
I
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2428 2429

/*
P
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2430
 * Mark a lock with a usage bit, and validate the state transition:
I
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2431
 */
2432
static int mark_lock(struct task_struct *curr, struct held_lock *this,
2433
			     enum lock_usage_bit new_bit)
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Ingo Molnar 已提交
2434
{
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2435
	unsigned int new_mask = 1 << new_bit, ret = 1;
I
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2436 2437

	/*
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2438 2439
	 * If already set then do not dirty the cacheline,
	 * nor do any checks:
I
Ingo Molnar 已提交
2440
	 */
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	if (likely(hlock_class(this)->usage_mask & new_mask))
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2442 2443 2444 2445
		return 1;

	if (!graph_lock())
		return 0;
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2446
	/*
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Peter Zijlstra 已提交
2447
	 * Make sure we didnt race:
I
Ingo Molnar 已提交
2448
	 */
D
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2449
	if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
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2450 2451 2452
		graph_unlock();
		return 1;
	}
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2453

D
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2454
	hlock_class(this)->usage_mask |= new_mask;
I
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2455

D
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2456
	if (!save_trace(hlock_class(this)->usage_traces + new_bit))
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2457
		return 0;
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2458

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2459
	switch (new_bit) {
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2460 2461 2462 2463 2464 2465 2466
#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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2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479
		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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2480

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2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494
	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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2495 2496 2497 2498 2499

/*
 * Initialize a lock instance's lock-class mapping info:
 */
void lockdep_init_map(struct lockdep_map *lock, const char *name,
2500
		      struct lock_class_key *key, int subclass)
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Ingo Molnar 已提交
2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518
{
	if (unlikely(!debug_locks))
		return;

	if (DEBUG_LOCKS_WARN_ON(!key))
		return;
	if (DEBUG_LOCKS_WARN_ON(!name))
		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->name = name;
	lock->key = key;
2519
	lock->class_cache = NULL;
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2520 2521 2522
#ifdef CONFIG_LOCK_STAT
	lock->cpu = raw_smp_processor_id();
#endif
2523 2524
	if (subclass)
		register_lock_class(lock, subclass, 1);
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Ingo Molnar 已提交
2525 2526 2527 2528 2529 2530 2531 2532 2533
}
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,
P
Peter Zijlstra 已提交
2534
			  struct lockdep_map *nest_lock, unsigned long ip)
I
Ingo Molnar 已提交
2535 2536
{
	struct task_struct *curr = current;
2537
	struct lock_class *class = NULL;
I
Ingo Molnar 已提交
2538 2539 2540 2541 2542
	struct held_lock *hlock;
	unsigned int depth, id;
	int chain_head = 0;
	u64 chain_key;

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2543 2544 2545
	if (!prove_locking)
		check = 1;

I
Ingo Molnar 已提交
2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558
	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");
		return 0;
	}

2559 2560 2561 2562 2563
	if (!subclass)
		class = lock->class_cache;
	/*
	 * Not cached yet or subclass?
	 */
I
Ingo Molnar 已提交
2564
	if (unlikely(!class)) {
2565
		class = register_lock_class(lock, subclass, 0);
I
Ingo Molnar 已提交
2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587
		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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2588 2589 2590
	if (DEBUG_LOCKS_WARN_ON(!class))
		return 0;
	hlock->class_idx = class - lock_classes + 1;
I
Ingo Molnar 已提交
2591 2592
	hlock->acquire_ip = ip;
	hlock->instance = lock;
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2593
	hlock->nest_lock = nest_lock;
I
Ingo Molnar 已提交
2594 2595 2596
	hlock->trylock = trylock;
	hlock->read = read;
	hlock->check = check;
2597
	hlock->hardirqs_off = !!hardirqs_off;
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2598 2599 2600 2601
#ifdef CONFIG_LOCK_STAT
	hlock->waittime_stamp = 0;
	hlock->holdtime_stamp = sched_clock();
#endif
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Ingo Molnar 已提交
2602

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2603 2604 2605
	if (check == 2 && !mark_irqflags(curr, hlock))
		return 0;

I
Ingo Molnar 已提交
2606
	/* mark it as used: */
2607
	if (!mark_lock(curr, hlock, LOCK_USED))
I
Ingo Molnar 已提交
2608
		return 0;
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2609

I
Ingo Molnar 已提交
2610
	/*
2611
	 * Calculate the chain hash: it's the combined hash of all the
I
Ingo Molnar 已提交
2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630 2631
	 * lock keys along the dependency chain. We save the hash value
	 * at every step so that we can get the current hash easily
	 * after unlock. The chain hash is then used to cache dependency
	 * results.
	 *
	 * The 'key ID' is what is the most compact key value to drive
	 * the hash, not class->key.
	 */
	id = class - lock_classes;
	if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
		return 0;

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

	hlock->prev_chain_key = chain_key;
P
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2632 2633 2634
	if (separate_irq_context(curr, hlock)) {
		chain_key = 0;
		chain_head = 1;
I
Ingo Molnar 已提交
2635 2636 2637
	}
	chain_key = iterate_chain_key(chain_key, id);

2638
	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
P
Peter Zijlstra 已提交
2639
		return 0;
2640

2641
	curr->curr_chain_key = chain_key;
I
Ingo Molnar 已提交
2642 2643
	curr->lockdep_depth++;
	check_chain_key(curr);
2644 2645 2646 2647
#ifdef CONFIG_DEBUG_LOCKDEP
	if (unlikely(!debug_locks))
		return 0;
#endif
I
Ingo Molnar 已提交
2648 2649 2650 2651 2652 2653
	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");
		return 0;
	}
2654

I
Ingo Molnar 已提交
2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673
	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 (",
2674
		curr->comm, task_pid_nr(curr));
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Ingo Molnar 已提交
2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704
	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;
}

2705
static int
2706 2707 2708
__lock_set_class(struct lockdep_map *lock, const char *name,
		 struct lock_class_key *key, unsigned int subclass,
		 unsigned long ip)
2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734
{
	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:
2735
	lockdep_init_map(lock, name, key, 0);
2736
	class = register_lock_class(lock, subclass, 0);
D
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2737
	hlock->class_idx = class - lock_classes + 1;
2738 2739 2740 2741 2742 2743 2744

	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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2745
			hlock_class(hlock)->subclass, hlock->trylock,
2746
				hlock->read, hlock->check, hlock->hardirqs_off,
P
Peter Zijlstra 已提交
2747
				hlock->nest_lock, hlock->acquire_ip))
2748 2749 2750 2751 2752 2753 2754 2755
			return 0;
	}

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

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2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788 2789 2790 2791 2792
/*
 * Remove the lock to the list of currently held locks in a
 * potentially non-nested (out of order) manner. This is a
 * relatively rare operation, as all the unlock APIs default
 * to nested mode (which uses lock_release()):
 */
static int
lock_release_non_nested(struct task_struct *curr,
			struct lockdep_map *lock, unsigned long ip)
{
	struct held_lock *hlock, *prev_hlock;
	unsigned int depth;
	int i;

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

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

found_it:
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2793 2794
	lock_release_holdtime(hlock);

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2795 2796 2797 2798 2799 2800 2801 2802 2803 2804 2805
	/*
	 * We have the right lock to unlock, 'hlock' points to it.
	 * Now we remove it from the stack, and add back the other
	 * entries (if any), recalculating the hash along the way:
	 */
	curr->lockdep_depth = i;
	curr->curr_chain_key = hlock->prev_chain_key;

	for (i++; i < depth; i++) {
		hlock = curr->held_locks + i;
		if (!__lock_acquire(hlock->instance,
D
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2806
			hlock_class(hlock)->subclass, hlock->trylock,
I
Ingo Molnar 已提交
2807
				hlock->read, hlock->check, hlock->hardirqs_off,
P
Peter Zijlstra 已提交
2808
				hlock->nest_lock, hlock->acquire_ip))
I
Ingo Molnar 已提交
2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841 2842 2843 2844 2845 2846
			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;

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2847 2848
	lock_release_holdtime(hlock);

I
Ingo Molnar 已提交
2849 2850
#ifdef CONFIG_DEBUG_LOCKDEP
	hlock->prev_chain_key = 0;
D
Dave Jones 已提交
2851
	hlock->class_idx = 0;
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Ingo Molnar 已提交
2852 2853 2854 2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885
	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:
 */
2886
static void check_flags(unsigned long flags)
I
Ingo Molnar 已提交
2887
{
2888 2889
#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
    defined(CONFIG_TRACE_IRQFLAGS)
I
Ingo Molnar 已提交
2890 2891 2892
	if (!debug_locks)
		return;

2893 2894 2895 2896 2897 2898 2899 2900 2901
	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");
		}
	}
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2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919

	/*
	 * 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
}

2920 2921 2922
void lock_set_class(struct lockdep_map *lock, const char *name,
		    struct lock_class_key *key, unsigned int subclass,
		    unsigned long ip)
2923 2924 2925 2926 2927 2928 2929 2930 2931
{
	unsigned long flags;

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

	raw_local_irq_save(flags);
	current->lockdep_recursion = 1;
	check_flags(flags);
2932
	if (__lock_set_class(lock, name, key, subclass, ip))
2933 2934 2935 2936
		check_chain_key(current);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
2937
EXPORT_SYMBOL_GPL(lock_set_class);
2938

I
Ingo Molnar 已提交
2939 2940 2941 2942
/*
 * We are not always called with irqs disabled - do that here,
 * and also avoid lockdep recursion:
 */
2943
void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
P
Peter Zijlstra 已提交
2944 2945
			  int trylock, int read, int check,
			  struct lockdep_map *nest_lock, unsigned long ip)
I
Ingo Molnar 已提交
2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956
{
	unsigned long flags;

	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
2957
		       irqs_disabled_flags(flags), nest_lock, ip);
I
Ingo Molnar 已提交
2958 2959 2960 2961 2962
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquire);

2963
void lock_release(struct lockdep_map *lock, int nested,
2964
			  unsigned long ip)
I
Ingo Molnar 已提交
2965 2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979
{
	unsigned long flags;

	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);

2980 2981 2982 2983 2984 2985 2986 2987 2988 2989
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
2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003
#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 (",
3004
		curr->comm, task_pid_nr(curr));
P
Peter Zijlstra 已提交
3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024
	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
3025
	int i, contention_point, contending_point;
P
Peter Zijlstra 已提交
3026 3027 3028 3029 3030 3031 3032 3033 3034 3035 3036 3037 3038 3039 3040 3041 3042 3043 3044 3045 3046 3047 3048

	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
3049 3050 3051
	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
3052

D
Dave Jones 已提交
3053
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3054 3055 3056 3057
	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
3058 3059
	if (lock->cpu != smp_processor_id())
		stats->bounces[bounce_contended + !!hlock->read]++;
P
Peter Zijlstra 已提交
3060 3061 3062 3063
	put_lock_stats(stats);
}

static void
P
Peter Zijlstra 已提交
3064
__lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3065 3066 3067 3068 3069 3070
{
	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
3071 3072
	s64 waittime = 0;
	int i, cpu;
P
Peter Zijlstra 已提交
3073 3074 3075 3076 3077 3078 3079 3080 3081 3082 3083 3084 3085 3086 3087 3088 3089 3090 3091 3092 3093

	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
3094 3095 3096 3097 3098 3099
	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
3100

D
Dave Jones 已提交
3101
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3102 3103 3104 3105 3106 3107 3108 3109
	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
3110
	put_lock_stats(stats);
P
Peter Zijlstra 已提交
3111 3112

	lock->cpu = cpu;
P
Peter Zijlstra 已提交
3113
	lock->ip = ip;
P
Peter Zijlstra 已提交
3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134
}

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

	if (unlikely(!lock_stat))
		return;

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

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

P
Peter Zijlstra 已提交
3135
void lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3136 3137 3138 3139 3140 3141 3142 3143 3144 3145 3146 3147
{
	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
3148
	__lock_acquired(lock, ip);
P
Peter Zijlstra 已提交
3149 3150 3151 3152 3153 3154
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquired);
#endif

I
Ingo Molnar 已提交
3155 3156 3157 3158 3159 3160 3161 3162
/*
 * Used by the testsuite, sanitize the validator state
 * after a simulated failure:
 */

void lockdep_reset(void)
{
	unsigned long flags;
3163
	int i;
I
Ingo Molnar 已提交
3164 3165 3166 3167 3168 3169 3170 3171 3172 3173

	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;
3174 3175
	for (i = 0; i < CHAINHASH_SIZE; i++)
		INIT_LIST_HEAD(chainhash_table + i);
I
Ingo Molnar 已提交
3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196
	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);

3197
	class->key = NULL;
I
Ingo Molnar 已提交
3198 3199
}

3200
static inline int within(const void *addr, void *start, unsigned long size)
I
Ingo Molnar 已提交
3201 3202 3203 3204 3205 3206 3207 3208 3209 3210
{
	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;
3211
	int locked;
I
Ingo Molnar 已提交
3212 3213

	raw_local_irq_save(flags);
3214
	locked = graph_lock();
I
Ingo Molnar 已提交
3215 3216 3217 3218 3219 3220 3221 3222

	/*
	 * 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;
3223
		list_for_each_entry_safe(class, next, head, hash_entry) {
I
Ingo Molnar 已提交
3224 3225
			if (within(class->key, start, size))
				zap_class(class);
3226 3227 3228
			else if (within(class->name, start, size))
				zap_class(class);
		}
I
Ingo Molnar 已提交
3229 3230
	}

3231 3232
	if (locked)
		graph_unlock();
I
Ingo Molnar 已提交
3233 3234 3235 3236 3237
	raw_local_irq_restore(flags);
}

void lockdep_reset_lock(struct lockdep_map *lock)
{
3238
	struct lock_class *class, *next;
I
Ingo Molnar 已提交
3239 3240 3241
	struct list_head *head;
	unsigned long flags;
	int i, j;
3242
	int locked;
I
Ingo Molnar 已提交
3243 3244 3245 3246

	raw_local_irq_save(flags);

	/*
3247 3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259
	 * 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
3260
	 */
3261
	locked = graph_lock();
I
Ingo Molnar 已提交
3262 3263 3264 3265 3266
	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) {
3267
			if (unlikely(class == lock->class_cache)) {
3268 3269
				if (debug_locks_off_graph_unlock())
					WARN_ON(1);
3270
				goto out_restore;
I
Ingo Molnar 已提交
3271 3272 3273
			}
		}
	}
3274 3275
	if (locked)
		graph_unlock();
3276 3277

out_restore:
I
Ingo Molnar 已提交
3278 3279 3280
	raw_local_irq_restore(flags);
}

3281
void lockdep_init(void)
I
Ingo Molnar 已提交
3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306
{
	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");

3307
	printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
I
Ingo Molnar 已提交
3308 3309
	printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
	printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3310
	printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
I
Ingo Molnar 已提交
3311 3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325
	printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
	printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
	printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);

	printk(" memory used by lock dependency info: %lu kB\n",
		(sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
		sizeof(struct list_head) * CLASSHASH_SIZE +
		sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
		sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
		sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);

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

#ifdef CONFIG_DEBUG_LOCKDEP
3326 3327 3328 3329 3330
	if (lockdep_init_error) {
		printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
		printk("Call stack leading to lockdep invocation was:\n");
		print_stack_trace(&lockdep_init_trace, 0);
	}
I
Ingo Molnar 已提交
3331 3332 3333 3334 3335
#endif
}

static void
print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3336
		     const void *mem_to, struct held_lock *hlock)
I
Ingo Molnar 已提交
3337 3338 3339 3340 3341 3342 3343 3344 3345 3346
{
	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",
3347
		curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3348
	print_lock(hlock);
I
Ingo Molnar 已提交
3349 3350 3351 3352 3353 3354
	lockdep_print_held_locks(curr);

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

O
Oleg Nesterov 已提交
3355 3356 3357 3358 3359 3360 3361
static inline int not_in_range(const void* mem_from, unsigned long mem_len,
				const void* lock_from, unsigned long lock_len)
{
	return lock_from + lock_len <= mem_from ||
		mem_from + mem_len <= lock_from;
}

I
Ingo Molnar 已提交
3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380
/*
 * Called when kernel memory is freed (or unmapped), or if a lock
 * is destroyed or reinitialized - this code checks whether there is
 * any held lock in the memory range of <from> to <to>:
 */
void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
{
	struct task_struct *curr = current;
	struct held_lock *hlock;
	unsigned long flags;
	int i;

	if (unlikely(!debug_locks))
		return;

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

O
Oleg Nesterov 已提交
3381 3382
		if (not_in_range(mem_from, mem_len, hlock->instance,
					sizeof(*hlock->instance)))
I
Ingo Molnar 已提交
3383 3384
			continue;

O
Oleg Nesterov 已提交
3385
		print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
I
Ingo Molnar 已提交
3386 3387 3388 3389
		break;
	}
	local_irq_restore(flags);
}
3390
EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
I
Ingo Molnar 已提交
3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 3401 3402

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",
3403
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421
	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;

3422 3423 3424 3425
	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
I
Ingo Molnar 已提交
3426 3427 3428 3429 3430 3431 3432 3433 3434 3435 3436 3437 3438 3439 3440 3441 3442 3443 3444 3445
	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;
3446 3447 3448
	} else {
		if (count != 10)
			printk(KERN_CONT " locked it.\n");
I
Ingo Molnar 已提交
3449 3450 3451
	}

	do_each_thread(g, p) {
I
Ingo Molnar 已提交
3452 3453 3454 3455 3456 3457 3458
		/*
		 * It's not reliable to print a task's held locks
		 * if it's not sleeping (or if it's not the current
		 * task):
		 */
		if (p->state == TASK_RUNNING && p != current)
			continue;
I
Ingo Molnar 已提交
3459 3460 3461 3462 3463 3464 3465 3466 3467 3468 3469 3470 3471 3472 3473
		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);

3474 3475 3476 3477 3478
/*
 * Careful: only use this function if you are sure that
 * the task cannot run in parallel!
 */
void __debug_show_held_locks(struct task_struct *task)
I
Ingo Molnar 已提交
3479
{
3480 3481 3482 3483
	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
I
Ingo Molnar 已提交
3484 3485
	lockdep_print_held_locks(task);
}
3486 3487 3488 3489 3490 3491
EXPORT_SYMBOL_GPL(__debug_show_held_locks);

void debug_show_held_locks(struct task_struct *task)
{
		__debug_show_held_locks(task);
}
I
Ingo Molnar 已提交
3492
EXPORT_SYMBOL_GPL(debug_show_held_locks);
P
Peter Zijlstra 已提交
3493 3494 3495 3496 3497 3498 3499 3500 3501 3502 3503 3504 3505 3506 3507 3508

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);
	}
}