lockdep.c 91.1 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:
 */

static const char *usage_str[] =
{
	[LOCK_USED] =			"initial-use ",
	[LOCK_USED_IN_HARDIRQ] =	"in-hardirq-W",
	[LOCK_USED_IN_SOFTIRQ] =	"in-softirq-W",
	[LOCK_ENABLED_SOFTIRQS] =	"softirq-on-W",
	[LOCK_ENABLED_HARDIRQS] =	"hardirq-on-W",
	[LOCK_USED_IN_HARDIRQ_READ] =	"in-hardirq-R",
	[LOCK_USED_IN_SOFTIRQ_READ] =	"in-softirq-R",
	[LOCK_ENABLED_SOFTIRQS_READ] =	"softirq-on-R",
	[LOCK_ENABLED_HARDIRQS_READ] =	"hardirq-on-R",
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	[LOCK_USED_IN_RECLAIM_FS] =	"in-reclaim-W",
	[LOCK_USED_IN_RECLAIM_FS_READ] = "in-reclaim-R",
	[LOCK_HELD_OVER_RECLAIM_FS] =	"ov-reclaim-W",
	[LOCK_HELD_OVER_RECLAIM_FS_READ] = "ov-reclaim-R",
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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
		if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
			*c1 = '-';

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

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

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

	if (class->usage_mask & LOCKF_HELD_OVER_RECLAIM_FS_READ)
		*c6 = '-';
	if (class->usage_mask & LOCKF_USED_IN_RECLAIM_FS_READ) {
		*c6 = '+';
		if (class->usage_mask & LOCKF_HELD_OVER_RECLAIM_FS_READ)
			*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>:
 */
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static void __used
print_lock_dependencies(struct lock_class *class, int depth)
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{
	struct lock_list *entry;

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	if (lockdep_dependency_visit(class, depth))
		return;

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

	print_lock_class_header(class, depth);

	list_for_each_entry(entry, &class->locks_after, entry) {
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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687
{
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688 689
	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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744

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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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		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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	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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1281 1282 1283 1284 1285 1286 1287
	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,
					LOCK_ENABLED_HARDIRQS, "hard"))
		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,
					LOCK_ENABLED_HARDIRQS, "hard-read"))
		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,
					LOCK_ENABLED_SOFTIRQS, "soft"))
		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,
					LOCK_ENABLED_SOFTIRQS, "soft"))
		return 0;

1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350
	/*
	 * 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,
					LOCK_HELD_OVER_RECLAIM_FS, "reclaim-fs"))
		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,
					LOCK_HELD_OVER_RECLAIM_FS, "reclaim-fs-read"))
		return 0;

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	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)
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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();
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1392 1393
	printk(  "---------------------------------------------\n");
	printk("%s/%d is trying to acquire lock:\n",
1394
		curr->comm, task_pid_nr(curr));
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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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1421
	struct held_lock *nest = NULL;
I
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1422 1423 1424 1425
	int i;

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

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

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

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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:
	 */
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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
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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

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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
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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
	 */
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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
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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
}

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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
{
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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++) {
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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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1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744
{
	/*
	 * 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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1818 1819 1820 1821 1822 1823 1824 1825
		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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Peter Zijlstra 已提交
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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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	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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{
	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);
}

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

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

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

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2002 2003
#define STRICT_READ_CHECKS	1

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static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
		enum lock_usage_bit new_bit)
I
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2006
{
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	int ret = 1;
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	switch(new_bit) {
I
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2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031
	case LOCK_USED_IN_HARDIRQ:
		if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
			return 0;
		if (!valid_state(curr, this, new_bit,
				 LOCK_ENABLED_HARDIRQS_READ))
			return 0;
		/*
		 * just marked it hardirq-safe, check that this lock
		 * took no hardirq-unsafe lock in the past:
		 */
		if (!check_usage_forwards(curr, this,
					  LOCK_ENABLED_HARDIRQS, "hard"))
			return 0;
#if STRICT_READ_CHECKS
		/*
		 * just marked it hardirq-safe, check that this lock
		 * took no hardirq-unsafe-read lock in the past:
		 */
		if (!check_usage_forwards(curr, this,
				LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
			return 0;
#endif
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		if (hardirq_verbose(hlock_class(this)))
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			ret = 2;
		break;
	case LOCK_USED_IN_SOFTIRQ:
		if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
			return 0;
		if (!valid_state(curr, this, new_bit,
				 LOCK_ENABLED_SOFTIRQS_READ))
			return 0;
		/*
		 * just marked it softirq-safe, check that this lock
		 * took no softirq-unsafe lock in the past:
		 */
		if (!check_usage_forwards(curr, this,
					  LOCK_ENABLED_SOFTIRQS, "soft"))
			return 0;
#if STRICT_READ_CHECKS
		/*
		 * just marked it softirq-safe, check that this lock
		 * took no softirq-unsafe-read lock in the past:
		 */
		if (!check_usage_forwards(curr, this,
				LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
			return 0;
#endif
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		if (softirq_verbose(hlock_class(this)))
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			ret = 2;
		break;
2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084
	case LOCK_USED_IN_RECLAIM_FS:
		if (!valid_state(curr, this, new_bit, LOCK_HELD_OVER_RECLAIM_FS))
			return 0;
		if (!valid_state(curr, this, new_bit,
				 LOCK_HELD_OVER_RECLAIM_FS_READ))
			return 0;
		/*
		 * just marked it reclaim-fs-safe, check that this lock
		 * took no reclaim-fs-unsafe lock in the past:
		 */
		if (!check_usage_forwards(curr, this,
					  LOCK_HELD_OVER_RECLAIM_FS, "reclaim-fs"))
			return 0;
#if STRICT_READ_CHECKS
		/*
		 * just marked it reclaim-fs-safe, check that this lock
		 * took no reclaim-fs-unsafe-read lock in the past:
		 */
		if (!check_usage_forwards(curr, this,
				LOCK_HELD_OVER_RECLAIM_FS_READ, "reclaim-fs-read"))
			return 0;
#endif
		if (reclaim_verbose(hlock_class(this)))
			ret = 2;
		break;
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	case LOCK_USED_IN_HARDIRQ_READ:
		if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
			return 0;
		/*
		 * just marked it hardirq-read-safe, check that this lock
		 * took no hardirq-unsafe lock in the past:
		 */
		if (!check_usage_forwards(curr, this,
					  LOCK_ENABLED_HARDIRQS, "hard"))
			return 0;
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		if (hardirq_verbose(hlock_class(this)))
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2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107
			ret = 2;
		break;
	case LOCK_USED_IN_SOFTIRQ_READ:
		if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
			return 0;
		/*
		 * just marked it softirq-read-safe, check that this lock
		 * took no softirq-unsafe lock in the past:
		 */
		if (!check_usage_forwards(curr, this,
					  LOCK_ENABLED_SOFTIRQS, "soft"))
			return 0;
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2108
		if (softirq_verbose(hlock_class(this)))
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2109 2110
			ret = 2;
		break;
2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123
	case LOCK_USED_IN_RECLAIM_FS_READ:
		if (!valid_state(curr, this, new_bit, LOCK_HELD_OVER_RECLAIM_FS))
			return 0;
		/*
		 * just marked it reclaim-fs-read-safe, check that this lock
		 * took no reclaim-fs-unsafe lock in the past:
		 */
		if (!check_usage_forwards(curr, this,
					  LOCK_HELD_OVER_RECLAIM_FS, "reclaim-fs"))
			return 0;
		if (reclaim_verbose(hlock_class(this)))
			ret = 2;
		break;
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2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146
	case LOCK_ENABLED_HARDIRQS:
		if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
			return 0;
		if (!valid_state(curr, this, new_bit,
				 LOCK_USED_IN_HARDIRQ_READ))
			return 0;
		/*
		 * just marked it hardirq-unsafe, check that no hardirq-safe
		 * lock in the system ever took it in the past:
		 */
		if (!check_usage_backwards(curr, this,
					   LOCK_USED_IN_HARDIRQ, "hard"))
			return 0;
#if STRICT_READ_CHECKS
		/*
		 * just marked it hardirq-unsafe, check that no
		 * hardirq-safe-read lock in the system ever took
		 * it in the past:
		 */
		if (!check_usage_backwards(curr, this,
				   LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
			return 0;
#endif
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		if (hardirq_verbose(hlock_class(this)))
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2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172
			ret = 2;
		break;
	case LOCK_ENABLED_SOFTIRQS:
		if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
			return 0;
		if (!valid_state(curr, this, new_bit,
				 LOCK_USED_IN_SOFTIRQ_READ))
			return 0;
		/*
		 * just marked it softirq-unsafe, check that no softirq-safe
		 * lock in the system ever took it in the past:
		 */
		if (!check_usage_backwards(curr, this,
					   LOCK_USED_IN_SOFTIRQ, "soft"))
			return 0;
#if STRICT_READ_CHECKS
		/*
		 * just marked it softirq-unsafe, check that no
		 * softirq-safe-read lock in the system ever took
		 * it in the past:
		 */
		if (!check_usage_backwards(curr, this,
				   LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
			return 0;
#endif
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2173
		if (softirq_verbose(hlock_class(this)))
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2174 2175
			ret = 2;
		break;
2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201
	case LOCK_HELD_OVER_RECLAIM_FS:
		if (!valid_state(curr, this, new_bit, LOCK_USED_IN_RECLAIM_FS))
			return 0;
		if (!valid_state(curr, this, new_bit,
				 LOCK_USED_IN_RECLAIM_FS_READ))
			return 0;
		/*
		 * just marked it reclaim-fs-unsafe, check that no reclaim-fs-safe
		 * lock in the system ever took it in the past:
		 */
		if (!check_usage_backwards(curr, this,
					   LOCK_USED_IN_RECLAIM_FS, "reclaim-fs"))
			return 0;
#if STRICT_READ_CHECKS
		/*
		 * just marked it softirq-unsafe, check that no
		 * softirq-safe-read lock in the system ever took
		 * it in the past:
		 */
		if (!check_usage_backwards(curr, this,
				   LOCK_USED_IN_RECLAIM_FS_READ, "reclaim-fs-read"))
			return 0;
#endif
		if (reclaim_verbose(hlock_class(this)))
			ret = 2;
		break;
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2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213
	case LOCK_ENABLED_HARDIRQS_READ:
		if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
			return 0;
#if STRICT_READ_CHECKS
		/*
		 * just marked it hardirq-read-unsafe, check that no
		 * hardirq-safe lock in the system ever took it in the past:
		 */
		if (!check_usage_backwards(curr, this,
					   LOCK_USED_IN_HARDIRQ, "hard"))
			return 0;
#endif
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2214
		if (hardirq_verbose(hlock_class(this)))
I
Ingo Molnar 已提交
2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228
			ret = 2;
		break;
	case LOCK_ENABLED_SOFTIRQS_READ:
		if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
			return 0;
#if STRICT_READ_CHECKS
		/*
		 * just marked it softirq-read-unsafe, check that no
		 * softirq-safe lock in the system ever took it in the past:
		 */
		if (!check_usage_backwards(curr, this,
					   LOCK_USED_IN_SOFTIRQ, "soft"))
			return 0;
#endif
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2229
		if (softirq_verbose(hlock_class(this)))
I
Ingo Molnar 已提交
2230 2231
			ret = 2;
		break;
2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246
	case LOCK_HELD_OVER_RECLAIM_FS_READ:
		if (!valid_state(curr, this, new_bit, LOCK_USED_IN_RECLAIM_FS))
			return 0;
#if STRICT_READ_CHECKS
		/*
		 * just marked it reclaim-fs-read-unsafe, check that no
		 * reclaim-fs-safe lock in the system ever took it in the past:
		 */
		if (!check_usage_backwards(curr, this,
					   LOCK_USED_IN_RECLAIM_FS, "reclaim-fs"))
			return 0;
#endif
		if (reclaim_verbose(hlock_class(this)))
			ret = 2;
		break;
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	default:
		WARN_ON(1);
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		break;
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2250 2251 2252 2253 2254
	}

	return ret;
}

2255 2256 2257 2258 2259 2260
enum mark_type {
	HARDIRQ,
	SOFTIRQ,
	RECLAIM_FS,
};

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2261 2262 2263
/*
 * Mark all held locks with a usage bit:
 */
2264
static int
2265
mark_held_locks(struct task_struct *curr, enum mark_type mark)
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Ingo Molnar 已提交
2266 2267 2268 2269 2270 2271 2272 2273
{
	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;

2274 2275
		switch (mark) {
		case HARDIRQ:
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2276 2277 2278 2279
			if (hlock->read)
				usage_bit = LOCK_ENABLED_HARDIRQS_READ;
			else
				usage_bit = LOCK_ENABLED_HARDIRQS;
2280 2281 2282
			break;

		case SOFTIRQ:
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Ingo Molnar 已提交
2283 2284 2285 2286
			if (hlock->read)
				usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
			else
				usage_bit = LOCK_ENABLED_SOFTIRQS;
2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297
			break;

		case RECLAIM_FS:
			if (hlock->read)
				usage_bit = LOCK_HELD_OVER_RECLAIM_FS_READ;
			else
				usage_bit = LOCK_HELD_OVER_RECLAIM_FS;
			break;

		default:
			BUG();
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		}
2299

2300
		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:
 */
2326
void trace_hardirqs_on_caller(unsigned long ip)
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{
	struct task_struct *curr = current;

2330
	time_hardirqs_on(CALLER_ADDR0, ip);
2331

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	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:
	 */
2353
	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)
2361
		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);
}
2368
EXPORT_SYMBOL(trace_hardirqs_on_caller);
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2370
void trace_hardirqs_on(void)
2371 2372 2373
{
	trace_hardirqs_on_caller(CALLER_ADDR0);
}
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EXPORT_SYMBOL(trace_hardirqs_on);

/*
 * Hardirqs were disabled:
 */
2379
void trace_hardirqs_off_caller(unsigned long ip)
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{
	struct task_struct *curr = current;

2383
	time_hardirqs_off(CALLER_ADDR0, ip);
2384

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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;
2396
		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);
}
2402
EXPORT_SYMBOL(trace_hardirqs_off_caller);
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2404
void trace_hardirqs_off(void)
2405 2406 2407
{
	trace_hardirqs_off_caller(CALLER_ADDR0);
}
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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)
2441
		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);
}

2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494
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,
					LOCK_ENABLED_HARDIRQS_READ))
				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
						LOCK_ENABLED_SOFTIRQS_READ))
					return 0;
		} else {
			if (!mark_lock(curr, hlock,
					LOCK_ENABLED_HARDIRQS))
				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
						LOCK_ENABLED_SOFTIRQS))
					return 0;
		}
	}

2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555
	/*
	 * 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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	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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#else
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2585

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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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2589
{
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	WARN_ON(1);
	return 1;
}
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2593

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static inline int mark_irqflags(struct task_struct *curr,
		struct held_lock *hlock)
{
	return 1;
}
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static inline int separate_irq_context(struct task_struct *curr,
		struct held_lock *hlock)
{
	return 0;
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}

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#endif
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2607 2608

/*
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 * Mark a lock with a usage bit, and validate the state transition:
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 */
2611
static int mark_lock(struct task_struct *curr, struct held_lock *this,
2612
			     enum lock_usage_bit new_bit)
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2613
{
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	unsigned int new_mask = 1 << new_bit, ret = 1;
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2615 2616

	/*
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2617 2618
	 * If already set then do not dirty the cacheline,
	 * nor do any checks:
I
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2619
	 */
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	if (likely(hlock_class(this)->usage_mask & new_mask))
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		return 1;

	if (!graph_lock())
		return 0;
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2625
	/*
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	 * Make sure we didnt race:
I
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2627
	 */
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	if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
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2629 2630 2631
		graph_unlock();
		return 1;
	}
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2632

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2633
	hlock_class(this)->usage_mask |= new_mask;
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2634

D
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	if (!save_trace(hlock_class(this)->usage_traces + new_bit))
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2636
		return 0;
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2637

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2638 2639 2640 2641 2642 2643 2644 2645 2646
	switch (new_bit) {
	case LOCK_USED_IN_HARDIRQ:
	case LOCK_USED_IN_SOFTIRQ:
	case LOCK_USED_IN_HARDIRQ_READ:
	case LOCK_USED_IN_SOFTIRQ_READ:
	case LOCK_ENABLED_HARDIRQS:
	case LOCK_ENABLED_SOFTIRQS:
	case LOCK_ENABLED_HARDIRQS_READ:
	case LOCK_ENABLED_SOFTIRQS_READ:
2647 2648 2649 2650
	case LOCK_USED_IN_RECLAIM_FS:
	case LOCK_USED_IN_RECLAIM_FS_READ:
	case LOCK_HELD_OVER_RECLAIM_FS:
	case LOCK_HELD_OVER_RECLAIM_FS_READ:
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		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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2664

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	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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/*
 * Initialize a lock instance's lock-class mapping info:
 */
void lockdep_init_map(struct lockdep_map *lock, const char *name,
2684
		      struct lock_class_key *key, int subclass)
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2685 2686 2687 2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702
{
	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;
2703
	lock->class_cache = NULL;
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#ifdef CONFIG_LOCK_STAT
	lock->cpu = raw_smp_processor_id();
#endif
2707 2708
	if (subclass)
		register_lock_class(lock, subclass, 1);
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}
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
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2718
			  struct lockdep_map *nest_lock, unsigned long ip)
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{
	struct task_struct *curr = current;
2721
	struct lock_class *class = NULL;
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2722 2723 2724 2725 2726
	struct held_lock *hlock;
	unsigned int depth, id;
	int chain_head = 0;
	u64 chain_key;

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	if (!prove_locking)
		check = 1;

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2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742
	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;
	}

2743 2744 2745 2746 2747
	if (!subclass)
		class = lock->class_cache;
	/*
	 * Not cached yet or subclass?
	 */
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2748
	if (unlikely(!class)) {
2749
		class = register_lock_class(lock, subclass, 0);
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2750 2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771
		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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	if (DEBUG_LOCKS_WARN_ON(!class))
		return 0;
	hlock->class_idx = class - lock_classes + 1;
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	hlock->acquire_ip = ip;
	hlock->instance = lock;
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	hlock->nest_lock = nest_lock;
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	hlock->trylock = trylock;
	hlock->read = read;
	hlock->check = check;
2781
	hlock->hardirqs_off = !!hardirqs_off;
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#ifdef CONFIG_LOCK_STAT
	hlock->waittime_stamp = 0;
	hlock->holdtime_stamp = sched_clock();
#endif
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2786

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

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2790
	/* mark it as used: */
2791
	if (!mark_lock(curr, hlock, LOCK_USED))
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2792
		return 0;
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2794
	/*
2795
	 * Calculate the chain hash: it's the combined hash of all the
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	 * lock keys along the dependency chain. We save the hash value
	 * at every step so that we can get the current hash easily
	 * after unlock. The chain hash is then used to cache dependency
	 * results.
	 *
	 * The 'key ID' is what is the most compact key value to drive
	 * the hash, not class->key.
	 */
	id = class - lock_classes;
	if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
		return 0;

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

	hlock->prev_chain_key = chain_key;
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	if (separate_irq_context(curr, hlock)) {
		chain_key = 0;
		chain_head = 1;
I
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2819 2820 2821
	}
	chain_key = iterate_chain_key(chain_key, id);

2822
	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
P
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2823
		return 0;
2824

2825
	curr->curr_chain_key = chain_key;
I
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2826 2827
	curr->lockdep_depth++;
	check_chain_key(curr);
2828 2829 2830 2831
#ifdef CONFIG_DEBUG_LOCKDEP
	if (unlikely(!debug_locks))
		return 0;
#endif
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2832 2833 2834 2835 2836 2837
	if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
		debug_locks_off();
		printk("BUG: MAX_LOCK_DEPTH too low!\n");
		printk("turning off the locking correctness validator.\n");
		return 0;
	}
2838

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2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856 2857
	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 (",
2858
		curr->comm, task_pid_nr(curr));
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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 2886 2887 2888
	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;
}

2889
static int
2890 2891 2892
__lock_set_class(struct lockdep_map *lock, const char *name,
		 struct lock_class_key *key, unsigned int subclass,
		 unsigned long ip)
2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918
{
	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:
2919
	lockdep_init_map(lock, name, key, 0);
2920
	class = register_lock_class(lock, subclass, 0);
D
Dave Jones 已提交
2921
	hlock->class_idx = class - lock_classes + 1;
2922 2923 2924 2925 2926 2927 2928

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

	for (; i < depth; i++) {
		hlock = curr->held_locks + i;
		if (!__lock_acquire(hlock->instance,
D
Dave Jones 已提交
2929
			hlock_class(hlock)->subclass, hlock->trylock,
2930
				hlock->read, hlock->check, hlock->hardirqs_off,
P
Peter Zijlstra 已提交
2931
				hlock->nest_lock, hlock->acquire_ip))
2932 2933 2934 2935 2936 2937 2938 2939
			return 0;
	}

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

I
Ingo Molnar 已提交
2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976
/*
 * Remove the lock to the list of currently held locks in a
 * potentially non-nested (out of order) manner. This is a
 * relatively rare operation, as all the unlock APIs default
 * to nested mode (which uses lock_release()):
 */
static int
lock_release_non_nested(struct task_struct *curr,
			struct lockdep_map *lock, unsigned long ip)
{
	struct held_lock *hlock, *prev_hlock;
	unsigned int depth;
	int i;

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

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

found_it:
P
Peter Zijlstra 已提交
2977 2978
	lock_release_holdtime(hlock);

I
Ingo Molnar 已提交
2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989
	/*
	 * We have the right lock to unlock, 'hlock' points to it.
	 * Now we remove it from the stack, and add back the other
	 * entries (if any), recalculating the hash along the way:
	 */
	curr->lockdep_depth = i;
	curr->curr_chain_key = hlock->prev_chain_key;

	for (i++; i < depth; i++) {
		hlock = curr->held_locks + i;
		if (!__lock_acquire(hlock->instance,
D
Dave Jones 已提交
2990
			hlock_class(hlock)->subclass, hlock->trylock,
I
Ingo Molnar 已提交
2991
				hlock->read, hlock->check, hlock->hardirqs_off,
P
Peter Zijlstra 已提交
2992
				hlock->nest_lock, hlock->acquire_ip))
I
Ingo Molnar 已提交
2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 3030
			return 0;
	}

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

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

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

	/*
	 * Is the unlock non-nested:
	 */
	if (hlock->instance != lock)
		return lock_release_non_nested(curr, lock, ip);
	curr->lockdep_depth--;

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

	curr->curr_chain_key = hlock->prev_chain_key;

P
Peter Zijlstra 已提交
3031 3032
	lock_release_holdtime(hlock);

I
Ingo Molnar 已提交
3033 3034
#ifdef CONFIG_DEBUG_LOCKDEP
	hlock->prev_chain_key = 0;
D
Dave Jones 已提交
3035
	hlock->class_idx = 0;
I
Ingo Molnar 已提交
3036 3037 3038 3039 3040 3041 3042 3043 3044 3045 3046 3047 3048 3049 3050 3051 3052 3053 3054 3055 3056 3057 3058 3059 3060 3061 3062 3063 3064 3065 3066 3067 3068 3069
	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:
 */
3070
static void check_flags(unsigned long flags)
I
Ingo Molnar 已提交
3071
{
3072 3073
#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
    defined(CONFIG_TRACE_IRQFLAGS)
I
Ingo Molnar 已提交
3074 3075 3076
	if (!debug_locks)
		return;

3077 3078 3079 3080 3081 3082 3083 3084 3085
	if (irqs_disabled_flags(flags)) {
		if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
			printk("possible reason: unannotated irqs-off.\n");
		}
	} else {
		if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
			printk("possible reason: unannotated irqs-on.\n");
		}
	}
I
Ingo Molnar 已提交
3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103

	/*
	 * 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
}

3104 3105 3106
void lock_set_class(struct lockdep_map *lock, const char *name,
		    struct lock_class_key *key, unsigned int subclass,
		    unsigned long ip)
3107 3108 3109 3110 3111 3112 3113 3114 3115
{
	unsigned long flags;

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

	raw_local_irq_save(flags);
	current->lockdep_recursion = 1;
	check_flags(flags);
3116
	if (__lock_set_class(lock, name, key, subclass, ip))
3117 3118 3119 3120
		check_chain_key(current);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
3121
EXPORT_SYMBOL_GPL(lock_set_class);
3122

I
Ingo Molnar 已提交
3123 3124 3125 3126
/*
 * We are not always called with irqs disabled - do that here,
 * and also avoid lockdep recursion:
 */
3127
void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
P
Peter Zijlstra 已提交
3128 3129
			  int trylock, int read, int check,
			  struct lockdep_map *nest_lock, unsigned long ip)
I
Ingo Molnar 已提交
3130 3131 3132 3133 3134 3135 3136 3137 3138 3139 3140
{
	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
3141
		       irqs_disabled_flags(flags), nest_lock, ip);
I
Ingo Molnar 已提交
3142 3143 3144 3145 3146
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquire);

3147
void lock_release(struct lockdep_map *lock, int nested,
3148
			  unsigned long ip)
I
Ingo Molnar 已提交
3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163
{
	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);

3164 3165 3166 3167 3168 3169 3170 3171 3172 3173
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
3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187
#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 (",
3188
		curr->comm, task_pid_nr(curr));
P
Peter Zijlstra 已提交
3189 3190 3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208
	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
3209
	int i, contention_point, contending_point;
P
Peter Zijlstra 已提交
3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232

	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
3233 3234 3235
	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
3236

D
Dave Jones 已提交
3237
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3238 3239 3240 3241
	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
3242 3243
	if (lock->cpu != smp_processor_id())
		stats->bounces[bounce_contended + !!hlock->read]++;
P
Peter Zijlstra 已提交
3244 3245 3246 3247
	put_lock_stats(stats);
}

static void
P
Peter Zijlstra 已提交
3248
__lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3249 3250 3251 3252 3253 3254
{
	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
3255 3256
	s64 waittime = 0;
	int i, cpu;
P
Peter Zijlstra 已提交
3257 3258 3259 3260 3261 3262 3263 3264 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276 3277

	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
3278 3279 3280 3281 3282 3283
	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
3284

D
Dave Jones 已提交
3285
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3286 3287 3288 3289 3290 3291 3292 3293
	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
3294
	put_lock_stats(stats);
P
Peter Zijlstra 已提交
3295 3296

	lock->cpu = cpu;
P
Peter Zijlstra 已提交
3297
	lock->ip = ip;
P
Peter Zijlstra 已提交
3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318
}

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
3319
void lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331
{
	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
3332
	__lock_acquired(lock, ip);
P
Peter Zijlstra 已提交
3333 3334 3335 3336 3337 3338
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquired);
#endif

I
Ingo Molnar 已提交
3339 3340 3341 3342 3343 3344 3345 3346
/*
 * Used by the testsuite, sanitize the validator state
 * after a simulated failure:
 */

void lockdep_reset(void)
{
	unsigned long flags;
3347
	int i;
I
Ingo Molnar 已提交
3348 3349 3350 3351 3352 3353 3354 3355 3356 3357

	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;
3358 3359
	for (i = 0; i < CHAINHASH_SIZE; i++)
		INIT_LIST_HEAD(chainhash_table + i);
I
Ingo Molnar 已提交
3360 3361 3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380
	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);

3381
	class->key = NULL;
I
Ingo Molnar 已提交
3382 3383
}

3384
static inline int within(const void *addr, void *start, unsigned long size)
I
Ingo Molnar 已提交
3385 3386 3387 3388 3389 3390 3391 3392 3393 3394
{
	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;
3395
	int locked;
I
Ingo Molnar 已提交
3396 3397

	raw_local_irq_save(flags);
3398
	locked = graph_lock();
I
Ingo Molnar 已提交
3399 3400 3401 3402 3403 3404 3405 3406

	/*
	 * 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;
3407
		list_for_each_entry_safe(class, next, head, hash_entry) {
I
Ingo Molnar 已提交
3408 3409
			if (within(class->key, start, size))
				zap_class(class);
3410 3411 3412
			else if (within(class->name, start, size))
				zap_class(class);
		}
I
Ingo Molnar 已提交
3413 3414
	}

3415 3416
	if (locked)
		graph_unlock();
I
Ingo Molnar 已提交
3417 3418 3419 3420 3421
	raw_local_irq_restore(flags);
}

void lockdep_reset_lock(struct lockdep_map *lock)
{
3422
	struct lock_class *class, *next;
I
Ingo Molnar 已提交
3423 3424 3425
	struct list_head *head;
	unsigned long flags;
	int i, j;
3426
	int locked;
I
Ingo Molnar 已提交
3427 3428 3429 3430

	raw_local_irq_save(flags);

	/*
3431 3432 3433 3434 3435 3436 3437 3438 3439 3440 3441 3442 3443
	 * 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
3444
	 */
3445
	locked = graph_lock();
I
Ingo Molnar 已提交
3446 3447 3448 3449 3450
	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) {
3451
			if (unlikely(class == lock->class_cache)) {
3452 3453
				if (debug_locks_off_graph_unlock())
					WARN_ON(1);
3454
				goto out_restore;
I
Ingo Molnar 已提交
3455 3456 3457
			}
		}
	}
3458 3459
	if (locked)
		graph_unlock();
3460 3461

out_restore:
I
Ingo Molnar 已提交
3462 3463 3464
	raw_local_irq_restore(flags);
}

3465
void lockdep_init(void)
I
Ingo Molnar 已提交
3466 3467 3468 3469 3470 3471 3472 3473 3474 3475 3476 3477 3478 3479 3480 3481 3482 3483 3484 3485 3486 3487 3488 3489 3490
{
	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");

3491
	printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
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	printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
	printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3494
	printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
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	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
3510 3511 3512 3513 3514
	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);
	}
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#endif
}

static void
print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3520
		     const void *mem_to, struct held_lock *hlock)
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{
	if (!debug_locks_off())
		return;
	if (debug_locks_silent)
		return;

	printk("\n=========================\n");
	printk(  "[ BUG: held lock freed! ]\n");
	printk(  "-------------------------\n");
	printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
3531
		curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3532
	print_lock(hlock);
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	lockdep_print_held_locks(curr);

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

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Oleg Nesterov 已提交
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static inline int not_in_range(const void* mem_from, unsigned long mem_len,
				const void* lock_from, unsigned long lock_len)
{
	return lock_from + lock_len <= mem_from ||
		mem_from + mem_len <= lock_from;
}

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/*
 * Called when kernel memory is freed (or unmapped), or if a lock
 * is destroyed or reinitialized - this code checks whether there is
 * any held lock in the memory range of <from> to <to>:
 */
void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
{
	struct task_struct *curr = current;
	struct held_lock *hlock;
	unsigned long flags;
	int i;

	if (unlikely(!debug_locks))
		return;

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

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

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		print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
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		break;
	}
	local_irq_restore(flags);
}
3574
EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
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static void print_held_locks_bug(struct task_struct *curr)
{
	if (!debug_locks_off())
		return;
	if (debug_locks_silent)
		return;

	printk("\n=====================================\n");
	printk(  "[ BUG: lock held at task exit time! ]\n");
	printk(  "-------------------------------------\n");
	printk("%s/%d is exiting with locks still held!\n",
3587
		curr->comm, task_pid_nr(curr));
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	lockdep_print_held_locks(curr);

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

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

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

3606 3607 3608 3609
	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
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	printk("\nShowing all locks held in the system:\n");

	/*
	 * Here we try to get the tasklist_lock as hard as possible,
	 * if not successful after 2 seconds we ignore it (but keep
	 * trying). This is to enable a debug printout even if a
	 * tasklist_lock-holding task deadlocks or crashes.
	 */
retry:
	if (!read_trylock(&tasklist_lock)) {
		if (count == 10)
			printk("hm, tasklist_lock locked, retrying... ");
		if (count) {
			count--;
			printk(" #%d", 10-count);
			mdelay(200);
			goto retry;
		}
		printk(" ignoring it.\n");
		unlock = 0;
3630 3631 3632
	} else {
		if (count != 10)
			printk(KERN_CONT " locked it.\n");
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	}

	do_each_thread(g, p) {
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		/*
		 * It's not reliable to print a task's held locks
		 * if it's not sleeping (or if it's not the current
		 * task):
		 */
		if (p->state == TASK_RUNNING && p != current)
			continue;
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		if (p->lockdep_depth)
			lockdep_print_held_locks(p);
		if (!unlock)
			if (read_trylock(&tasklist_lock))
				unlock = 1;
	} while_each_thread(g, p);

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

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

3658 3659 3660 3661 3662
/*
 * Careful: only use this function if you are sure that
 * the task cannot run in parallel!
 */
void __debug_show_held_locks(struct task_struct *task)
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{
3664 3665 3666 3667
	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
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	lockdep_print_held_locks(task);
}
3670 3671 3672 3673 3674 3675
EXPORT_SYMBOL_GPL(__debug_show_held_locks);

void debug_show_held_locks(struct task_struct *task)
{
		__debug_show_held_locks(task);
}
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EXPORT_SYMBOL_GPL(debug_show_held_locks);
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void lockdep_sys_exit(void)
{
	struct task_struct *curr = current;

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