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 <linux/stringify.h>
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#include <linux/bitops.h>
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#include <asm/sections.h>

#include "lockdep_internals.h"

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#define CREATE_TRACE_POINTS
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#include <trace/events/lock.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 arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
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static int graph_lock(void)
{
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	arch_spin_lock(&lockdep_lock);
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	/*
	 * 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) {
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		arch_spin_unlock(&lockdep_lock);
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		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 && !arch_spin_is_locked(&lockdep_lock))
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		return DEBUG_LOCKS_WARN_ON(1);

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

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	arch_spin_unlock(&lockdep_lock);
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	return ret;
}
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static int lockdep_initialized;

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

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

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#ifdef CONFIG_LOCK_STAT
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static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS],
		      cpu_lock_stats);
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static inline u64 lockstat_clock(void)
{
	return cpu_clock(smp_processor_id());
}

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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;
}

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static void lock_time_inc(struct lock_time *lt, u64 time)
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{
	if (time > lt->max)
		lt->max = time;

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	if (time < lt->min || !lt->nr)
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		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)
{
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	if (!src->nr)
		return;

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

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

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	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 =
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			&per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
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		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 =
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			&per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
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		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)
{
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	return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
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}

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

static void lock_release_holdtime(struct held_lock *hlock)
{
	struct lock_class_stats *stats;
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	u64 holdtime;
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	if (!lock_stat)
		return;

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	holdtime = lockstat_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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	/*
	 * Some daft arches put -1 at the end to indicate its a full trace.
	 *
	 * <rant> this is buggy anyway, since it takes a whole extra entry so a
	 * complete trace that maxes out the entries provided will be reported
	 * as incomplete, friggin useless </rant>
	 */
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	if (trace->nr_entries != 0 &&
	    trace->entries[trace->nr_entries-1] == ULONG_MAX)
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		trace->nr_entries--;

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	trace->max_entries = trace->nr_entries;

	nr_stack_trace_entries += trace->nr_entries;

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	if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
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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;

#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_find_usage_forwards_checks;
atomic_t nr_find_usage_backwards_checks;
#endif

/*
 * Locking printouts:
 */

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#define __USAGE(__STATE)						\
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	[LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W",	\
	[LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W",		\
	[LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
	[LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
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static const char *usage_str[] =
{
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#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
#include "lockdep_states.h"
#undef LOCKDEP_STATE
	[LOCK_USED] = "INITIAL USE",
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};

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

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static inline unsigned long lock_flag(enum lock_usage_bit bit)
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{
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	return 1UL << bit;
}
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static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
{
	char c = '.';

	if (class->usage_mask & lock_flag(bit + 2))
		c = '+';
	if (class->usage_mask & lock_flag(bit)) {
		c = '-';
		if (class->usage_mask & lock_flag(bit + 2))
			c = '?';
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	}

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	return c;
}
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void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
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{
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	int i = 0;
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#define LOCKDEP_STATE(__STATE) 						\
	usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);	\
	usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
#include "lockdep_states.h"
#undef LOCKDEP_STATE

	usage[i] = '\0';
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}

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

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	get_usage_chars(class, usage);
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	name = class->name;
	if (!name) {
		name = __get_key_name(class->key, str);
		printk(" (%s", name);
	} else {
		printk(" (%s", name);
		if (class->name_version > 1)
			printk("#%d", class->name_version);
		if (class->subclass)
			printk("/%d", class->subclass);
	}
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	printk("){%s}", usage);
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}

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

	printk("%s", name);
}

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

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

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

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

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

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

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	/*
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	 * static variable?
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	 */
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	if ((addr >= start) && (addr < end))
		return 1;
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	if (arch_is_kernel_data(addr))
		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;
	}
610
#endif
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	/*
	 * module var?
	 */
	return is_module_address(addr);
616 617
}

I
Ingo Molnar 已提交
618
/*
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 * To make lock name printouts unique, we calculate a unique
 * class->name_version generation counter:
I
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621
 */
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622
static int count_matching_names(struct lock_class *new_class)
I
Ingo Molnar 已提交
623
{
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624 625
	struct lock_class *class;
	int count = 0;
I
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626

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627
	if (!new_class->name)
I
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628 629
		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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637
	return count + 1;
I
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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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Ingo Molnar 已提交
647
{
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	struct lockdep_subclass_key *key;
	struct list_head *hash_head;
	struct lock_class *class;
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651

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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;
661
		save_stack_trace(&lockdep_init_trace);
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	}
#endif
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664

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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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680

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	key = lock->key->subkeys + subclass;
682

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683
	hash_head = classhashentry(key);
684

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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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692
			return class;
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		}
	}
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695

P
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696
	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.
I
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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)
I
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706
{
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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");
757
		dump_stack();
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758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773
		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);
774 775 776 777
	/*
	 * Add it to the global list of classes:
	 */
	list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
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778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820

	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");
821
		dump_stack();
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Peter Zijlstra 已提交
822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844
		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;

845 846
	entry->class = this;
	entry->distance = distance;
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Peter Zijlstra 已提交
847 848 849 850 851 852 853 854 855 856 857 858
	/*
	 * Since we never remove from the dependency list, the list can
	 * be walked lockless by other CPUs, it's only allocation
	 * that must be protected by the spinlock. But this also means
	 * we must make new entries visible only once writes to the
	 * entry become visible - hence the RCU op:
	 */
	list_add_tail_rcu(&entry->entry, head);

	return 1;
}

P
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859 860 861
/*
 * For good efficiency of modular, we use power of 2
 */
P
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862 863 864
#define MAX_CIRCULAR_QUEUE_SIZE		4096UL
#define CQ_MASK				(MAX_CIRCULAR_QUEUE_SIZE-1)

P
Peter Zijlstra 已提交
865 866
/*
 * The circular_queue and helpers is used to implement the
P
Peter Zijlstra 已提交
867 868 869
 * breadth-first search(BFS)algorithem, by which we can build
 * the shortest path from the next lock to be acquired to the
 * previous held lock if there is a circular between them.
P
Peter Zijlstra 已提交
870
 */
P
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871 872 873 874 875 876 877
struct circular_queue {
	unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
	unsigned int  front, rear;
};

static struct circular_queue lock_cq;

878
unsigned int max_bfs_queue_depth;
P
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879

880 881
static unsigned int lockdep_dependency_gen_id;

P
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882 883 884
static inline void __cq_init(struct circular_queue *cq)
{
	cq->front = cq->rear = 0;
885
	lockdep_dependency_gen_id++;
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886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926
}

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

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

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

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

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

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

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

static inline void mark_lock_accessed(struct lock_list *lock,
					struct lock_list *parent)
{
	unsigned long nr;
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927

P
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928 929 930
	nr = lock - list_entries;
	WARN_ON(nr >= nr_list_entries);
	lock->parent = parent;
931
	lock->class->dep_gen_id = lockdep_dependency_gen_id;
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932 933 934 935 936
}

static inline unsigned long lock_accessed(struct lock_list *lock)
{
	unsigned long nr;
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937

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938 939
	nr = lock - list_entries;
	WARN_ON(nr >= nr_list_entries);
940
	return lock->class->dep_gen_id == lockdep_dependency_gen_id;
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941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959
}

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

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

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

960
static int __bfs(struct lock_list *source_entry,
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961 962 963 964
		 void *data,
		 int (*match)(struct lock_list *entry, void *data),
		 struct lock_list **target_entry,
		 int forward)
965 966
{
	struct lock_list *entry;
967
	struct list_head *head;
968 969 970
	struct circular_queue *cq = &lock_cq;
	int ret = 1;

971
	if (match(source_entry, data)) {
972 973 974 975 976
		*target_entry = source_entry;
		ret = 0;
		goto exit;
	}

977 978 979 980 981 982 983 984 985
	if (forward)
		head = &source_entry->class->locks_after;
	else
		head = &source_entry->class->locks_before;

	if (list_empty(head))
		goto exit;

	__cq_init(cq);
986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004
	__cq_enqueue(cq, (unsigned long)source_entry);

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

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

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

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

		list_for_each_entry(entry, head, entry) {
			if (!lock_accessed(entry)) {
1005
				unsigned int cq_depth;
1006
				mark_lock_accessed(entry, lock);
1007
				if (match(entry, data)) {
1008 1009 1010 1011 1012 1013 1014 1015 1016
					*target_entry = entry;
					ret = 0;
					goto exit;
				}

				if (__cq_enqueue(cq, (unsigned long)entry)) {
					ret = -1;
					goto exit;
				}
1017 1018 1019
				cq_depth = __cq_get_elem_count(cq);
				if (max_bfs_queue_depth < cq_depth)
					max_bfs_queue_depth = cq_depth;
1020 1021 1022 1023 1024 1025 1026
			}
		}
	}
exit:
	return ret;
}

1027
static inline int __bfs_forwards(struct lock_list *src_entry,
1028 1029 1030
			void *data,
			int (*match)(struct lock_list *entry, void *data),
			struct lock_list **target_entry)
1031
{
1032
	return __bfs(src_entry, data, match, target_entry, 1);
1033 1034 1035

}

1036
static inline int __bfs_backwards(struct lock_list *src_entry,
1037 1038 1039
			void *data,
			int (*match)(struct lock_list *entry, void *data),
			struct lock_list **target_entry)
1040
{
1041
	return __bfs(src_entry, data, match, target_entry, 0);
1042 1043 1044

}

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Peter Zijlstra 已提交
1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055
/*
 * Recursive, forwards-direction lock-dependency checking, used for
 * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
 * checking.
 */

/*
 * Print a dependency chain entry (this is only done when a deadlock
 * has been detected):
 */
static noinline int
1056
print_circular_bug_entry(struct lock_list *target, int depth)
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Peter Zijlstra 已提交
1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072
{
	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
1073 1074 1075
print_circular_bug_header(struct lock_list *entry, unsigned int depth,
			struct held_lock *check_src,
			struct held_lock *check_tgt)
P
Peter Zijlstra 已提交
1076 1077 1078
{
	struct task_struct *curr = current;

1079
	if (debug_locks_silent)
P
Peter Zijlstra 已提交
1080 1081 1082 1083 1084 1085 1086
		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",
1087
		curr->comm, task_pid_nr(curr));
1088
	print_lock(check_src);
P
Peter Zijlstra 已提交
1089
	printk("\nbut task is already holding lock:\n");
1090
	print_lock(check_tgt);
P
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1091 1092 1093 1094 1095 1096 1097 1098
	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;
}

1099 1100 1101 1102 1103
static inline int class_equal(struct lock_list *entry, void *data)
{
	return entry->class == data;
}

1104 1105 1106 1107
static noinline int print_circular_bug(struct lock_list *this,
				struct lock_list *target,
				struct held_lock *check_src,
				struct held_lock *check_tgt)
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1108 1109
{
	struct task_struct *curr = current;
1110
	struct lock_list *parent;
1111
	int depth;
P
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1112

1113
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
P
Peter Zijlstra 已提交
1114 1115
		return 0;

1116
	if (!save_trace(&this->trace))
P
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1117 1118
		return 0;

1119 1120
	depth = get_lock_depth(target);

1121
	print_circular_bug_header(target, depth, check_src, check_tgt);
1122 1123 1124 1125 1126 1127 1128

	parent = get_lock_parent(target);

	while (parent) {
		print_circular_bug_entry(parent, --depth);
		parent = get_lock_parent(parent);
	}
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1129 1130 1131 1132 1133 1134 1135 1136 1137 1138

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

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

	return 0;
}

1139 1140 1141 1142 1143 1144 1145 1146 1147 1148
static noinline int print_bfs_bug(int ret)
{
	if (!debug_locks_off_graph_unlock())
		return 0;

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

	return 0;
}

1149
static int noop_count(struct lock_list *entry, void *data)
1150
{
1151 1152 1153
	(*(unsigned long *)data)++;
	return 0;
}
1154

1155 1156 1157 1158
unsigned long __lockdep_count_forward_deps(struct lock_list *this)
{
	unsigned long  count = 0;
	struct lock_list *uninitialized_var(target_entry);
1159

1160
	__bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1161

1162
	return count;
1163 1164 1165 1166
}
unsigned long lockdep_count_forward_deps(struct lock_class *class)
{
	unsigned long ret, flags;
1167 1168 1169 1170
	struct lock_list this;

	this.parent = NULL;
	this.class = class;
1171 1172

	local_irq_save(flags);
1173
	arch_spin_lock(&lockdep_lock);
1174
	ret = __lockdep_count_forward_deps(&this);
1175
	arch_spin_unlock(&lockdep_lock);
1176 1177 1178 1179 1180
	local_irq_restore(flags);

	return ret;
}

1181
unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1182
{
1183 1184
	unsigned long  count = 0;
	struct lock_list *uninitialized_var(target_entry);
1185

1186
	__bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1187

1188
	return count;
1189 1190 1191 1192 1193
}

unsigned long lockdep_count_backward_deps(struct lock_class *class)
{
	unsigned long ret, flags;
1194 1195 1196 1197
	struct lock_list this;

	this.parent = NULL;
	this.class = class;
1198 1199

	local_irq_save(flags);
1200
	arch_spin_lock(&lockdep_lock);
1201
	ret = __lockdep_count_backward_deps(&this);
1202
	arch_spin_unlock(&lockdep_lock);
1203 1204 1205 1206 1207
	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
1213 1214
check_noncircular(struct lock_list *root, struct lock_class *target,
		struct lock_list **target_entry)
P
Peter Zijlstra 已提交
1215
{
1216
	int result;
P
Peter Zijlstra 已提交
1217

1218
	debug_atomic_inc(&nr_cyclic_checks);
1219

1220
	result = __bfs_forwards(root, target, class_equal, target_entry);
I
Ingo Molnar 已提交
1221

1222 1223
	return result;
}
1224

1225
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
I
Ingo Molnar 已提交
1226 1227 1228 1229 1230 1231
/*
 * 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.
 */

1232 1233 1234 1235 1236 1237 1238
static inline int usage_match(struct lock_list *entry, void *bit)
{
	return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
}



I
Ingo Molnar 已提交
1239 1240
/*
 * Find a node in the forwards-direction dependency sub-graph starting
1241
 * at @root->class that matches @bit.
I
Ingo Molnar 已提交
1242
 *
1243 1244
 * Return 0 if such a node exists in the subgraph, and put that node
 * into *@target_entry.
I
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1245
 *
1246 1247
 * Return 1 otherwise and keep *@target_entry unchanged.
 * Return <0 on error.
I
Ingo Molnar 已提交
1248
 */
1249 1250 1251
static int
find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
			struct lock_list **target_entry)
I
Ingo Molnar 已提交
1252
{
1253
	int result;
I
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1254 1255 1256

	debug_atomic_inc(&nr_find_usage_forwards_checks);

1257 1258 1259
	result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);

	return result;
I
Ingo Molnar 已提交
1260 1261 1262 1263
}

/*
 * Find a node in the backwards-direction dependency sub-graph starting
1264
 * at @root->class that matches @bit.
I
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1265
 *
1266 1267
 * Return 0 if such a node exists in the subgraph, and put that node
 * into *@target_entry.
I
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1268
 *
1269 1270
 * Return 1 otherwise and keep *@target_entry unchanged.
 * Return <0 on error.
I
Ingo Molnar 已提交
1271
 */
1272 1273 1274
static int
find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
			struct lock_list **target_entry)
I
Ingo Molnar 已提交
1275
{
1276
	int result;
I
Ingo Molnar 已提交
1277 1278 1279

	debug_atomic_inc(&nr_find_usage_backwards_checks);

1280
	result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
D
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1281

1282
	return result;
I
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1283 1284
}

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1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338
static void print_lock_class_header(struct lock_class *class, int depth)
{
	int bit;

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

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

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

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

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

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

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

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

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

	return;
}
1339

I
Ingo Molnar 已提交
1340 1341
static int
print_bad_irq_dependency(struct task_struct *curr,
1342 1343 1344 1345
			 struct lock_list *prev_root,
			 struct lock_list *next_root,
			 struct lock_list *backwards_entry,
			 struct lock_list *forwards_entry,
I
Ingo Molnar 已提交
1346 1347 1348 1349 1350 1351
			 struct held_lock *prev,
			 struct held_lock *next,
			 enum lock_usage_bit bit1,
			 enum lock_usage_bit bit2,
			 const char *irqclass)
{
1352
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
1353 1354 1355 1356 1357
		return 0;

	printk("\n======================================================\n");
	printk(  "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
		irqclass, irqclass);
1358
	print_kernel_version();
I
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1359 1360
	printk(  "------------------------------------------------------\n");
	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1361
		curr->comm, task_pid_nr(curr),
I
Ingo Molnar 已提交
1362 1363 1364 1365 1366 1367 1368 1369 1370
		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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1371
	print_lock_name(hlock_class(prev));
I
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1372
	printk(" ->");
D
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1373
	print_lock_name(hlock_class(next));
I
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1374 1375 1376 1377
	printk("\n");

	printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
		irqclass);
1378
	print_lock_name(backwards_entry->class);
I
Ingo Molnar 已提交
1379 1380
	printk("\n... which became %s-irq-safe at:\n", irqclass);

1381
	print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
I
Ingo Molnar 已提交
1382 1383

	printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1384
	print_lock_name(forwards_entry->class);
I
Ingo Molnar 已提交
1385 1386 1387
	printk("\n... which became %s-irq-unsafe at:\n", irqclass);
	printk("...");

1388
	print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
I
Ingo Molnar 已提交
1389 1390 1391 1392

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

1393 1394 1395 1396 1397
	printk("\nthe dependencies between %s-irq-safe lock", irqclass);
	printk(" and the holding lock:\n");
	if (!save_trace(&prev_root->trace))
		return 0;
	print_shortest_lock_dependencies(backwards_entry, prev_root);
I
Ingo Molnar 已提交
1398

1399 1400 1401 1402 1403
	printk("\nthe dependencies between the lock to be acquired");
	printk(" and %s-irq-unsafe lock:\n", irqclass);
	if (!save_trace(&next_root->trace))
		return 0;
	print_shortest_lock_dependencies(forwards_entry, next_root);
I
Ingo Molnar 已提交
1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416

	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;
1417
	struct lock_list this, that;
1418
	struct lock_list *uninitialized_var(target_entry);
1419
	struct lock_list *uninitialized_var(target_entry1);
1420 1421 1422 1423 1424

	this.parent = NULL;

	this.class = hlock_class(prev);
	ret = find_usage_backwards(&this, bit_backwards, &target_entry);
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1425 1426 1427 1428
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
1429

1430 1431 1432
	that.parent = NULL;
	that.class = hlock_class(next);
	ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
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1433 1434 1435 1436
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
I
Ingo Molnar 已提交
1437

1438 1439 1440
	return print_bad_irq_dependency(curr, &this, &that,
			target_entry, target_entry1,
			prev, next,
I
Ingo Molnar 已提交
1441 1442 1443
			bit_backwards, bit_forwards, irqclass);
}

1444 1445
static const char *state_names[] = {
#define LOCKDEP_STATE(__STATE) \
P
Peter Zijlstra 已提交
1446
	__stringify(__STATE),
1447 1448 1449 1450 1451 1452
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

static const char *state_rnames[] = {
#define LOCKDEP_STATE(__STATE) \
P
Peter Zijlstra 已提交
1453
	__stringify(__STATE)"-READ",
1454 1455 1456 1457 1458
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

static inline const char *state_name(enum lock_usage_bit bit)
P
Peter Zijlstra 已提交
1459
{
1460 1461
	return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
}
P
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1462

1463 1464
static int exclusive_bit(int new_bit)
{
P
Peter Zijlstra 已提交
1465
	/*
1466 1467 1468 1469 1470 1471 1472 1473
	 * USED_IN
	 * USED_IN_READ
	 * ENABLED
	 * ENABLED_READ
	 *
	 * bit 0 - write/read
	 * bit 1 - used_in/enabled
	 * bit 2+  state
P
Peter Zijlstra 已提交
1474
	 */
1475 1476 1477

	int state = new_bit & ~3;
	int dir = new_bit & 2;
P
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1478 1479

	/*
1480
	 * keep state, bit flip the direction and strip read.
P
Peter Zijlstra 已提交
1481
	 */
1482 1483 1484 1485 1486 1487
	return state | (dir ^ 2);
}

static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
			   struct held_lock *next, enum lock_usage_bit bit)
{
P
Peter Zijlstra 已提交
1488
	/*
1489 1490
	 * Prove that the new dependency does not connect a hardirq-safe
	 * lock with a hardirq-unsafe lock - to achieve this we search
P
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1491 1492 1493
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
1494 1495
	if (!check_usage(curr, prev, next, bit,
			   exclusive_bit(bit), state_name(bit)))
P
Peter Zijlstra 已提交
1496 1497
		return 0;

1498 1499
	bit++; /* _READ */

1500
	/*
1501 1502
	 * Prove that the new dependency does not connect a hardirq-safe-read
	 * lock with a hardirq-unsafe lock - to achieve this we search
1503 1504 1505
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
1506 1507
	if (!check_usage(curr, prev, next, bit,
			   exclusive_bit(bit), state_name(bit)))
1508 1509
		return 0;

1510 1511 1512 1513 1514 1515 1516 1517 1518
	return 1;
}

static int
check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
		struct held_lock *next)
{
#define LOCKDEP_STATE(__STATE)						\
	if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE))	\
1519
		return 0;
1520 1521
#include "lockdep_states.h"
#undef LOCKDEP_STATE
1522

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1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551
	return 1;
}

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

#else

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

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

I
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1552 1553 1554 1555 1556 1557
#endif

static int
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
		   struct held_lock *next)
{
1558
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
1559 1560 1561 1562
		return 0;

	printk("\n=============================================\n");
	printk(  "[ INFO: possible recursive locking detected ]\n");
1563
	print_kernel_version();
I
Ingo Molnar 已提交
1564 1565
	printk(  "---------------------------------------------\n");
	printk("%s/%d is trying to acquire lock:\n",
1566
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592
	print_lock(next);
	printk("\nbut task is already holding lock:\n");
	print_lock(prev);

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

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

	return 0;
}

/*
 * Check whether we are holding such a class already.
 *
 * (Note that this has to be done separately, because the graph cannot
 * detect such classes of deadlocks.)
 *
 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
 */
static int
check_deadlock(struct task_struct *curr, struct held_lock *next,
	       struct lockdep_map *next_instance, int read)
{
	struct held_lock *prev;
P
Peter Zijlstra 已提交
1593
	struct held_lock *nest = NULL;
I
Ingo Molnar 已提交
1594 1595 1596 1597
	int i;

	for (i = 0; i < curr->lockdep_depth; i++) {
		prev = curr->held_locks + i;
P
Peter Zijlstra 已提交
1598 1599 1600 1601

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

D
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1602
		if (hlock_class(prev) != hlock_class(next))
I
Ingo Molnar 已提交
1603
			continue;
P
Peter Zijlstra 已提交
1604

I
Ingo Molnar 已提交
1605 1606
		/*
		 * Allow read-after-read recursion of the same
1607
		 * lock class (i.e. read_lock(lock)+read_lock(lock)):
I
Ingo Molnar 已提交
1608
		 */
1609
		if ((read == 2) && prev->read)
I
Ingo Molnar 已提交
1610
			return 2;
P
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1611 1612 1613 1614 1615 1616 1617 1618

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

I
Ingo Molnar 已提交
1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647
		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,
1648
	       struct held_lock *next, int distance)
I
Ingo Molnar 已提交
1649 1650 1651
{
	struct lock_list *entry;
	int ret;
1652 1653
	struct lock_list this;
	struct lock_list *uninitialized_var(target_entry);
I
Ingo Molnar 已提交
1654 1655 1656 1657 1658 1659 1660 1661 1662 1663

	/*
	 * 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:
	 */
1664 1665 1666 1667 1668 1669 1670
	this.class = hlock_class(next);
	this.parent = NULL;
	ret = check_noncircular(&this, hlock_class(prev), &target_entry);
	if (unlikely(!ret))
		return print_circular_bug(&this, target_entry, next, prev);
	else if (unlikely(ret < 0))
		return print_bfs_bug(ret);
1671

P
Peter Zijlstra 已提交
1672
	if (!check_prev_add_irq(curr, prev, next))
I
Ingo Molnar 已提交
1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692
		return 0;

	/*
	 * For recursive read-locks we do all the dependency checks,
	 * but we dont store read-triggered dependencies (only
	 * write-triggered dependencies). This ensures that only the
	 * write-side dependencies matter, and that if for example a
	 * write-lock never takes any other locks, then the reads are
	 * equivalent to a NOP.
	 */
	if (next->read == 2 || prev->read == 2)
		return 1;
	/*
	 * Is the <prev> -> <next> dependency already present?
	 *
	 * (this may occur even though this is a new chain: consider
	 *  e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
	 *  chains - the second one will be new, but L1 already has
	 *  L2 added to its dependency list, due to the first chain.)
	 */
D
Dave Jones 已提交
1693 1694
	list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
		if (entry->class == hlock_class(next)) {
1695 1696
			if (distance == 1)
				entry->distance = 1;
I
Ingo Molnar 已提交
1697
			return 2;
1698
		}
I
Ingo Molnar 已提交
1699 1700 1701 1702 1703 1704
	}

	/*
	 * Ok, all validations passed, add the new lock
	 * to the previous lock's dependency list:
	 */
D
Dave Jones 已提交
1705 1706 1707
	ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
			       &hlock_class(prev)->locks_after,
			       next->acquire_ip, distance);
1708

I
Ingo Molnar 已提交
1709 1710
	if (!ret)
		return 0;
1711

D
Dave Jones 已提交
1712 1713 1714
	ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
			       &hlock_class(next)->locks_before,
			       next->acquire_ip, distance);
1715 1716
	if (!ret)
		return 0;
I
Ingo Molnar 已提交
1717 1718

	/*
P
Peter Zijlstra 已提交
1719 1720
	 * Debugging printouts:
	 */
D
Dave Jones 已提交
1721
	if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
P
Peter Zijlstra 已提交
1722 1723
		graph_unlock();
		printk("\n new dependency: ");
D
Dave Jones 已提交
1724
		print_lock_name(hlock_class(prev));
P
Peter Zijlstra 已提交
1725
		printk(" => ");
D
Dave Jones 已提交
1726
		print_lock_name(hlock_class(next));
P
Peter Zijlstra 已提交
1727
		printk("\n");
I
Ingo Molnar 已提交
1728
		dump_stack();
P
Peter Zijlstra 已提交
1729
		return graph_lock();
I
Ingo Molnar 已提交
1730
	}
P
Peter Zijlstra 已提交
1731 1732
	return 1;
}
I
Ingo Molnar 已提交
1733

P
Peter Zijlstra 已提交
1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744
/*
 * 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;
1745

I
Ingo Molnar 已提交
1746
	/*
P
Peter Zijlstra 已提交
1747 1748 1749
	 * Debugging checks.
	 *
	 * Depth must not be zero for a non-head lock:
I
Ingo Molnar 已提交
1750
	 */
P
Peter Zijlstra 已提交
1751 1752
	if (!depth)
		goto out_bug;
I
Ingo Molnar 已提交
1753
	/*
P
Peter Zijlstra 已提交
1754 1755
	 * At least two relevant locks must exist for this
	 * to be a head:
I
Ingo Molnar 已提交
1756
	 */
P
Peter Zijlstra 已提交
1757 1758 1759
	if (curr->held_locks[depth].irq_context !=
			curr->held_locks[depth-1].irq_context)
		goto out_bug;
1760

P
Peter Zijlstra 已提交
1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778
	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;
1779
		}
P
Peter Zijlstra 已提交
1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791
		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
1792
	}
P
Peter Zijlstra 已提交
1793 1794 1795 1796
	return 1;
out_bug:
	if (!debug_locks_off_graph_unlock())
		return 0;
I
Ingo Molnar 已提交
1797

P
Peter Zijlstra 已提交
1798
	WARN_ON(1);
I
Ingo Molnar 已提交
1799

P
Peter Zijlstra 已提交
1800
	return 0;
I
Ingo Molnar 已提交
1801 1802
}

P
Peter Zijlstra 已提交
1803
unsigned long nr_lock_chains;
1804
struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1805
int nr_chain_hlocks;
1806 1807 1808 1809 1810 1811
static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];

struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
{
	return lock_classes + chain_hlocks[chain->base + i];
}
P
Peter Zijlstra 已提交
1812

I
Ingo Molnar 已提交
1813 1814
/*
 * Look up a dependency chain. If the key is not present yet then
1815 1816 1817
 * 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
1818
 */
1819 1820 1821
static inline int lookup_chain_cache(struct task_struct *curr,
				     struct held_lock *hlock,
				     u64 chain_key)
I
Ingo Molnar 已提交
1822
{
D
Dave Jones 已提交
1823
	struct lock_class *class = hlock_class(hlock);
I
Ingo Molnar 已提交
1824 1825
	struct list_head *hash_head = chainhashentry(chain_key);
	struct lock_chain *chain;
1826
	struct held_lock *hlock_curr, *hlock_next;
1827
	int i, j, n, cn;
I
Ingo Molnar 已提交
1828

1829 1830
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return 0;
I
Ingo Molnar 已提交
1831 1832 1833 1834 1835 1836 1837 1838
	/*
	 * 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);
1839
			if (very_verbose(class))
1840 1841 1842 1843
				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
1844 1845 1846
			return 0;
		}
	}
1847
	if (very_verbose(class))
1848 1849
		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
1850 1851 1852 1853
	/*
	 * Allocate a new chain entry from the static array, and add
	 * it to the hash:
	 */
1854 1855
	if (!graph_lock())
		return 0;
I
Ingo Molnar 已提交
1856 1857 1858 1859 1860
	/*
	 * 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) {
1861
			graph_unlock();
I
Ingo Molnar 已提交
1862 1863 1864 1865
			goto cache_hit;
		}
	}
	if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
1866 1867 1868
		if (!debug_locks_off_graph_unlock())
			return 0;

I
Ingo Molnar 已提交
1869 1870
		printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
		printk("turning off the locking correctness validator.\n");
1871
		dump_stack();
I
Ingo Molnar 已提交
1872 1873 1874 1875
		return 0;
	}
	chain = lock_chains + nr_lock_chains++;
	chain->chain_key = chain_key;
1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886
	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;
1887 1888 1889 1890 1891 1892 1893 1894 1895
	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;
1896
		for (j = 0; j < chain->depth - 1; j++, i++) {
D
Dave Jones 已提交
1897
			int lock_id = curr->held_locks[i].class_idx - 1;
1898 1899 1900 1901
			chain_hlocks[chain->base + j] = lock_id;
		}
		chain_hlocks[chain->base + j] = class - lock_classes;
	}
I
Ingo Molnar 已提交
1902 1903
	list_add_tail_rcu(&chain->entry, hash_head);
	debug_atomic_inc(&chain_lookup_misses);
P
Peter Zijlstra 已提交
1904 1905 1906 1907 1908 1909
	inc_chains();

	return 1;
}

static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
1910
		struct held_lock *hlock, int chain_head, u64 chain_key)
P
Peter Zijlstra 已提交
1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922
{
	/*
	 * 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) &&
1923
	    lookup_chain_cache(curr, hlock, chain_key)) {
P
Peter Zijlstra 已提交
1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958
		/*
		 * Check whether last held lock:
		 *
		 * - is irq-safe, if this lock is irq-unsafe
		 * - is softirq-safe, if this lock is hardirq-unsafe
		 *
		 * And check whether the new lock's dependency graph
		 * could lead back to the previous lock.
		 *
		 * any of these scenarios could lead to a deadlock. If
		 * All validations
		 */
		int ret = check_deadlock(curr, hlock, lock, hlock->read);

		if (!ret)
			return 0;
		/*
		 * Mark recursive read, as we jump over it when
		 * building dependencies (just like we jump over
		 * trylock entries):
		 */
		if (ret == 2)
			hlock->read = 2;
		/*
		 * Add dependency only if this lock is not the head
		 * of the chain, and if it's not a secondary read-lock:
		 */
		if (!chain_head && ret != 2)
			if (!check_prevs_add(curr, hlock))
				return 0;
		graph_unlock();
	} else
		/* after lookup_chain_cache(): */
		if (unlikely(!debug_locks))
			return 0;
I
Ingo Molnar 已提交
1959 1960 1961

	return 1;
}
P
Peter Zijlstra 已提交
1962 1963 1964
#else
static inline int validate_chain(struct task_struct *curr,
	       	struct lockdep_map *lock, struct held_lock *hlock,
1965
		int chain_head, u64 chain_key)
P
Peter Zijlstra 已提交
1966 1967 1968
{
	return 1;
}
1969
#endif
I
Ingo Molnar 已提交
1970 1971 1972 1973 1974

/*
 * We are building curr_chain_key incrementally, so double-check
 * it from scratch, to make sure that it's done correctly:
 */
1975
static void check_chain_key(struct task_struct *curr)
I
Ingo Molnar 已提交
1976 1977 1978 1979 1980 1981 1982 1983 1984 1985
{
#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();
1986
			WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
I
Ingo Molnar 已提交
1987 1988 1989 1990 1991
				curr->lockdep_depth, i,
				(unsigned long long)chain_key,
				(unsigned long long)hlock->prev_chain_key);
			return;
		}
D
Dave Jones 已提交
1992
		id = hlock->class_idx - 1;
1993 1994 1995
		if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
			return;

I
Ingo Molnar 已提交
1996 1997 1998 1999 2000 2001 2002 2003
		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();
2004
		WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
I
Ingo Molnar 已提交
2005 2006 2007 2008 2009 2010 2011
			curr->lockdep_depth, i,
			(unsigned long long)chain_key,
			(unsigned long long)curr->curr_chain_key);
	}
#endif
}

P
Peter Zijlstra 已提交
2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027
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",
2028
		curr->comm, task_pid_nr(curr),
P
Peter Zijlstra 已提交
2029 2030 2031 2032 2033 2034 2035
		trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
		trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
		trace_hardirqs_enabled(curr),
		trace_softirqs_enabled(curr));
	print_lock(this);

	printk("{%s} state was registered at:\n", usage_str[prev_bit]);
D
Dave Jones 已提交
2036
	print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
P
Peter Zijlstra 已提交
2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054

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

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

	return 0;
}

/*
 * Print out an error if an invalid bit is set:
 */
static inline int
valid_state(struct task_struct *curr, struct held_lock *this,
	    enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
{
D
Dave Jones 已提交
2055
	if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
P
Peter Zijlstra 已提交
2056 2057 2058 2059 2060 2061 2062
		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);

2063
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
I
Ingo Molnar 已提交
2064 2065 2066 2067 2068

/*
 * print irq inversion bug:
 */
static int
2069 2070
print_irq_inversion_bug(struct task_struct *curr,
			struct lock_list *root, struct lock_list *other,
I
Ingo Molnar 已提交
2071 2072 2073
			struct held_lock *this, int forwards,
			const char *irqclass)
{
2074
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
2075 2076 2077 2078
		return 0;

	printk("\n=========================================================\n");
	printk(  "[ INFO: possible irq lock inversion dependency detected ]\n");
2079
	print_kernel_version();
I
Ingo Molnar 已提交
2080 2081
	printk(  "---------------------------------------------------------\n");
	printk("%s/%d just changed the state of lock:\n",
2082
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
2083 2084
	print_lock(this);
	if (forwards)
2085
		printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
I
Ingo Molnar 已提交
2086
	else
2087
		printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2088
	print_lock_name(other->class);
I
Ingo Molnar 已提交
2089 2090 2091 2092 2093
	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);

2094 2095 2096 2097
	printk("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
	if (!save_trace(&root->trace))
		return 0;
	print_shortest_lock_dependencies(other, root);
I
Ingo Molnar 已提交
2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113

	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;
2114 2115
	struct lock_list root;
	struct lock_list *uninitialized_var(target_entry);
I
Ingo Molnar 已提交
2116

2117 2118 2119
	root.parent = NULL;
	root.class = hlock_class(this);
	ret = find_usage_forwards(&root, bit, &target_entry);
P
Peter Zijlstra 已提交
2120 2121 2122 2123
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
I
Ingo Molnar 已提交
2124

2125
	return print_irq_inversion_bug(curr, &root, target_entry,
2126
					this, 1, irqclass);
I
Ingo Molnar 已提交
2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137
}

/*
 * 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;
2138 2139
	struct lock_list root;
	struct lock_list *uninitialized_var(target_entry);
I
Ingo Molnar 已提交
2140

2141 2142 2143
	root.parent = NULL;
	root.class = hlock_class(this);
	ret = find_usage_backwards(&root, bit, &target_entry);
P
Peter Zijlstra 已提交
2144 2145 2146 2147
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
I
Ingo Molnar 已提交
2148

2149
	return print_irq_inversion_bug(curr, &root, target_entry,
2150
					this, 0, irqclass);
I
Ingo Molnar 已提交
2151 2152
}

2153
void print_irqtrace_events(struct task_struct *curr)
I
Ingo Molnar 已提交
2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165
{
	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);
}

2166
static int HARDIRQ_verbose(struct lock_class *class)
I
Ingo Molnar 已提交
2167
{
P
Peter Zijlstra 已提交
2168 2169 2170
#if HARDIRQ_VERBOSE
	return class_filter(class);
#endif
I
Ingo Molnar 已提交
2171 2172 2173
	return 0;
}

2174
static int SOFTIRQ_verbose(struct lock_class *class)
I
Ingo Molnar 已提交
2175
{
P
Peter Zijlstra 已提交
2176 2177 2178 2179
#if SOFTIRQ_VERBOSE
	return class_filter(class);
#endif
	return 0;
I
Ingo Molnar 已提交
2180 2181
}

2182
static int RECLAIM_FS_verbose(struct lock_class *class)
2183 2184 2185 2186 2187 2188 2189
{
#if RECLAIM_VERBOSE
	return class_filter(class);
#endif
	return 0;
}

I
Ingo Molnar 已提交
2190 2191
#define STRICT_READ_CHECKS	1

2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204
static int (*state_verbose_f[])(struct lock_class *class) = {
#define LOCKDEP_STATE(__STATE) \
	__STATE##_verbose,
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

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

2205 2206 2207
typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
			     enum lock_usage_bit bit, const char *name);

2208
static int
2209 2210
mark_lock_irq(struct task_struct *curr, struct held_lock *this,
		enum lock_usage_bit new_bit)
2211
{
2212
	int excl_bit = exclusive_bit(new_bit);
2213
	int read = new_bit & 1;
2214 2215
	int dir = new_bit & 2;

2216 2217 2218 2219 2220 2221 2222
	/*
	 * mark USED_IN has to look forwards -- to ensure no dependency
	 * has ENABLED state, which would allow recursion deadlocks.
	 *
	 * mark ENABLED has to look backwards -- to ensure no dependee
	 * has USED_IN state, which, again, would allow  recursion deadlocks.
	 */
2223 2224
	check_usage_f usage = dir ?
		check_usage_backwards : check_usage_forwards;
2225

2226 2227 2228 2229
	/*
	 * Validate that this particular lock does not have conflicting
	 * usage states.
	 */
2230 2231
	if (!valid_state(curr, this, new_bit, excl_bit))
		return 0;
2232

2233 2234 2235 2236 2237
	/*
	 * Validate that the lock dependencies don't have conflicting usage
	 * states.
	 */
	if ((!read || !dir || STRICT_READ_CHECKS) &&
2238
			!usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2239
		return 0;
2240

2241 2242 2243 2244 2245 2246 2247 2248
	/*
	 * Check for read in write conflicts
	 */
	if (!read) {
		if (!valid_state(curr, this, new_bit, excl_bit + 1))
			return 0;

		if (STRICT_READ_CHECKS &&
2249 2250
			!usage(curr, this, excl_bit + 1,
				state_name(new_bit + 1)))
2251 2252
			return 0;
	}
2253

2254
	if (state_verbose(new_bit, hlock_class(this)))
2255 2256 2257 2258 2259
		return 2;

	return 1;
}

2260
enum mark_type {
2261 2262 2263
#define LOCKDEP_STATE(__STATE)	__STATE,
#include "lockdep_states.h"
#undef LOCKDEP_STATE
2264 2265
};

I
Ingo Molnar 已提交
2266 2267 2268
/*
 * Mark all held locks with a usage bit:
 */
2269
static int
2270
mark_held_locks(struct task_struct *curr, enum mark_type mark)
I
Ingo Molnar 已提交
2271 2272 2273 2274 2275 2276 2277 2278
{
	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;

2279 2280 2281 2282 2283
		usage_bit = 2 + (mark << 2); /* ENABLED */
		if (hlock->read)
			usage_bit += 1; /* READ */

		BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2284

2285
		if (!mark_lock(curr, hlock, usage_bit))
I
Ingo Molnar 已提交
2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310
			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:
 */
2311
void trace_hardirqs_on_caller(unsigned long ip)
I
Ingo Molnar 已提交
2312 2313 2314
{
	struct task_struct *curr = current;

2315
	time_hardirqs_on(CALLER_ADDR0, ip);
2316

I
Ingo Molnar 已提交
2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337
	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:
	 */
2338
	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)
2346
		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);
}
2353
EXPORT_SYMBOL(trace_hardirqs_on_caller);
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2355
void trace_hardirqs_on(void)
2356 2357 2358
{
	trace_hardirqs_on_caller(CALLER_ADDR0);
}
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EXPORT_SYMBOL(trace_hardirqs_on);

/*
 * Hardirqs were disabled:
 */
2364
void trace_hardirqs_off_caller(unsigned long ip)
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{
	struct task_struct *curr = current;

2368
	time_hardirqs_off(CALLER_ADDR0, ip);
2369

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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;
2381
		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);
}
2387
EXPORT_SYMBOL(trace_hardirqs_off_caller);
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2389
void trace_hardirqs_off(void)
2390 2391 2392
{
	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)
2426
		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);
}

2455
static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473
{
	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;

2474
	if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2475 2476 2477 2478 2479
		return;

	mark_held_locks(curr, RECLAIM_FS);
}

2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496
static void check_flags(unsigned long flags);

void lockdep_trace_alloc(gfp_t gfp_mask)
{
	unsigned long flags;

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

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

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static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
{
	/*
	 * If non-trylock use in a hardirq or softirq context, then
	 * mark the lock as used in these contexts:
	 */
	if (!hlock->trylock) {
		if (hlock->read) {
			if (curr->hardirq_context)
				if (!mark_lock(curr, hlock,
						LOCK_USED_IN_HARDIRQ_READ))
					return 0;
			if (curr->softirq_context)
				if (!mark_lock(curr, hlock,
						LOCK_USED_IN_SOFTIRQ_READ))
					return 0;
		} else {
			if (curr->hardirq_context)
				if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
					return 0;
			if (curr->softirq_context)
				if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
					return 0;
		}
	}
	if (!hlock->hardirqs_off) {
		if (hlock->read) {
			if (!mark_lock(curr, hlock,
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					LOCK_ENABLED_HARDIRQ_READ))
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				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
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						LOCK_ENABLED_SOFTIRQ_READ))
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					return 0;
		} else {
			if (!mark_lock(curr, hlock,
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					LOCK_ENABLED_HARDIRQ))
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				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
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						LOCK_ENABLED_SOFTIRQ))
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					return 0;
		}
	}

2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557
	/*
	 * 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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static inline
int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
		enum lock_usage_bit new_bit)
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{
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	WARN_ON(1);
	return 1;
}
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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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}

2608 2609 2610 2611
void lockdep_trace_alloc(gfp_t gfp_mask)
{
}

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#endif
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/*
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 * Mark a lock with a usage bit, and validate the state transition:
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 */
2617
static int mark_lock(struct task_struct *curr, struct held_lock *this,
2618
			     enum lock_usage_bit new_bit)
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{
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	unsigned int new_mask = 1 << new_bit, ret = 1;
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	/*
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	 * If already set then do not dirty the cacheline,
	 * nor do any checks:
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2625
	 */
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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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	/*
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	 * Make sure we didnt race:
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	 */
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	if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
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		graph_unlock();
		return 1;
	}
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	hlock_class(this)->usage_mask |= new_mask;
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	if (!save_trace(hlock_class(this)->usage_traces + new_bit))
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		return 0;
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	switch (new_bit) {
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#define LOCKDEP_STATE(__STATE)			\
	case LOCK_USED_IN_##__STATE:		\
	case LOCK_USED_IN_##__STATE##_READ:	\
	case LOCK_ENABLED_##__STATE:		\
	case LOCK_ENABLED_##__STATE##_READ:
#include "lockdep_states.h"
#undef LOCKDEP_STATE
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		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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	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,
2685
		      struct lock_class_key *key, int subclass)
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2686
{
2687 2688 2689 2690 2691 2692 2693
	lock->class_cache = NULL;
#ifdef CONFIG_LOCK_STAT
	lock->cpu = raw_smp_processor_id();
#endif

	if (DEBUG_LOCKS_WARN_ON(!name)) {
		lock->name = "NULL";
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		return;
2695 2696 2697
	}

	lock->name = name;
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	if (DEBUG_LOCKS_WARN_ON(!key))
		return;
	/*
	 * Sanity check, the lock-class key must be persistent:
	 */
	if (!static_obj(key)) {
		printk("BUG: key %p not in .data!\n", key);
		DEBUG_LOCKS_WARN_ON(1);
		return;
	}
	lock->key = key;
2710 2711 2712 2713

	if (unlikely(!debug_locks))
		return;

2714 2715
	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,
2725 2726
			  struct lockdep_map *nest_lock, unsigned long ip,
			  int references)
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{
	struct task_struct *curr = current;
2729
	struct lock_class *class = NULL;
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	struct held_lock *hlock;
	unsigned int depth, id;
	int chain_head = 0;
2733
	int class_idx;
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	u64 chain_key;

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	if (!prove_locking)
		check = 1;

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	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");
2749
		dump_stack();
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		return 0;
	}

2753 2754 2755 2756 2757
	if (!subclass)
		class = lock->class_cache;
	/*
	 * Not cached yet or subclass?
	 */
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2758
	if (unlikely(!class)) {
2759
		class = register_lock_class(lock, subclass, 0);
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2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780
		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;

2781 2782 2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794
	class_idx = class - lock_classes + 1;

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

			return 1;
		}
	}

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	hlock = curr->held_locks + depth;
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	if (DEBUG_LOCKS_WARN_ON(!class))
		return 0;
2798
	hlock->class_idx = class_idx;
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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;
2805
	hlock->hardirqs_off = !!hardirqs_off;
2806
	hlock->references = references;
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#ifdef CONFIG_LOCK_STAT
	hlock->waittime_stamp = 0;
2809
	hlock->holdtime_stamp = lockstat_clock();
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#endif
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	if (check == 2 && !mark_irqflags(curr, hlock))
		return 0;

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2815
	/* mark it as used: */
2816
	if (!mark_lock(curr, hlock, LOCK_USED))
I
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2817
		return 0;
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2818

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2819
	/*
2820
	 * 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;
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2844 2845 2846
	}
	chain_key = iterate_chain_key(chain_key, id);

2847
	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
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		return 0;
2849

2850
	curr->curr_chain_key = chain_key;
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2851 2852
	curr->lockdep_depth++;
	check_chain_key(curr);
2853 2854 2855 2856
#ifdef CONFIG_DEBUG_LOCKDEP
	if (unlikely(!debug_locks))
		return 0;
#endif
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	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");
2861
		dump_stack();
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2862 2863
		return 0;
	}
2864

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2865 2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883
	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 (",
2884
		curr->comm, task_pid_nr(curr));
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	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;
}

2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938
static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
{
	if (hlock->instance == lock)
		return 1;

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

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

		if (DEBUG_LOCKS_WARN_ON(!class))
			return 0;

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

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

	return 0;
}

2939
static int
2940 2941 2942
__lock_set_class(struct lockdep_map *lock, const char *name,
		 struct lock_class_key *key, unsigned int subclass,
		 unsigned long ip)
2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960 2961
{
	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;
2962
		if (match_held_lock(hlock, lock))
2963 2964 2965 2966 2967 2968
			goto found_it;
		prev_hlock = hlock;
	}
	return print_unlock_inbalance_bug(curr, lock, ip);

found_it:
2969
	lockdep_init_map(lock, name, key, 0);
2970
	class = register_lock_class(lock, subclass, 0);
D
Dave Jones 已提交
2971
	hlock->class_idx = class - lock_classes + 1;
2972 2973 2974 2975 2976 2977 2978

	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
2979
			hlock_class(hlock)->subclass, hlock->trylock,
2980
				hlock->read, hlock->check, hlock->hardirqs_off,
2981 2982
				hlock->nest_lock, hlock->acquire_ip,
				hlock->references))
2983 2984 2985 2986 2987 2988 2989 2990
			return 0;
	}

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

I
Ingo Molnar 已提交
2991 2992 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
/*
 * 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;
3021
		if (match_held_lock(hlock, lock))
I
Ingo Molnar 已提交
3022 3023 3024 3025 3026 3027
			goto found_it;
		prev_hlock = hlock;
	}
	return print_unlock_inbalance_bug(curr, lock, ip);

found_it:
3028 3029 3030 3031 3032 3033 3034 3035 3036 3037 3038 3039 3040 3041
	if (hlock->instance == lock)
		lock_release_holdtime(hlock);

	if (hlock->references) {
		hlock->references--;
		if (hlock->references) {
			/*
			 * We had, and after removing one, still have
			 * references, the current lock stack is still
			 * valid. We're done!
			 */
			return 1;
		}
	}
P
Peter Zijlstra 已提交
3042

I
Ingo Molnar 已提交
3043 3044 3045 3046 3047
	/*
	 * 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:
	 */
3048

I
Ingo Molnar 已提交
3049 3050 3051 3052 3053 3054
	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
3055
			hlock_class(hlock)->subclass, hlock->trylock,
I
Ingo Molnar 已提交
3056
				hlock->read, hlock->check, hlock->hardirqs_off,
3057 3058
				hlock->nest_lock, hlock->acquire_ip,
				hlock->references))
I
Ingo Molnar 已提交
3059 3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070 3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081 3082 3083 3084 3085 3086 3087
			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:
	 */
3088
	if (hlock->instance != lock || hlock->references)
I
Ingo Molnar 已提交
3089 3090 3091 3092 3093 3094 3095 3096
		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
3097 3098
	lock_release_holdtime(hlock);

I
Ingo Molnar 已提交
3099 3100
#ifdef CONFIG_DEBUG_LOCKDEP
	hlock->prev_chain_key = 0;
D
Dave Jones 已提交
3101
	hlock->class_idx = 0;
I
Ingo Molnar 已提交
3102 3103 3104 3105 3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132
	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);
}

3133 3134 3135 3136 3137 3138
static int __lock_is_held(struct lockdep_map *lock)
{
	struct task_struct *curr = current;
	int i;

	for (i = 0; i < curr->lockdep_depth; i++) {
3139 3140 3141
		struct held_lock *hlock = curr->held_locks + i;

		if (match_held_lock(hlock, lock))
3142 3143 3144 3145 3146 3147
			return 1;
	}

	return 0;
}

I
Ingo Molnar 已提交
3148 3149 3150
/*
 * Check whether we follow the irq-flags state precisely:
 */
3151
static void check_flags(unsigned long flags)
I
Ingo Molnar 已提交
3152
{
3153 3154
#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
    defined(CONFIG_TRACE_IRQFLAGS)
I
Ingo Molnar 已提交
3155 3156 3157
	if (!debug_locks)
		return;

3158 3159 3160 3161 3162 3163 3164 3165 3166
	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
3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184

	/*
	 * 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
}

3185 3186 3187
void lock_set_class(struct lockdep_map *lock, const char *name,
		    struct lock_class_key *key, unsigned int subclass,
		    unsigned long ip)
3188 3189 3190 3191 3192 3193 3194 3195 3196
{
	unsigned long flags;

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

	raw_local_irq_save(flags);
	current->lockdep_recursion = 1;
	check_flags(flags);
3197
	if (__lock_set_class(lock, name, key, subclass, ip))
3198 3199 3200 3201
		check_chain_key(current);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
3202
EXPORT_SYMBOL_GPL(lock_set_class);
3203

I
Ingo Molnar 已提交
3204 3205 3206 3207
/*
 * We are not always called with irqs disabled - do that here,
 * and also avoid lockdep recursion:
 */
3208
void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
P
Peter Zijlstra 已提交
3209 3210
			  int trylock, int read, int check,
			  struct lockdep_map *nest_lock, unsigned long ip)
I
Ingo Molnar 已提交
3211 3212 3213
{
	unsigned long flags;

3214 3215
	trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);

I
Ingo Molnar 已提交
3216 3217 3218 3219 3220 3221 3222 3223
	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,
3224
		       irqs_disabled_flags(flags), nest_lock, ip, 0);
I
Ingo Molnar 已提交
3225 3226 3227 3228 3229
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquire);

3230
void lock_release(struct lockdep_map *lock, int nested,
3231
			  unsigned long ip)
I
Ingo Molnar 已提交
3232 3233 3234
{
	unsigned long flags;

3235 3236
	trace_lock_release(lock, nested, ip);

I
Ingo Molnar 已提交
3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247 3248
	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);

3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261 3262 3263 3264 3265 3266 3267 3268
int lock_is_held(struct lockdep_map *lock)
{
	unsigned long flags;
	int ret = 0;

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

	raw_local_irq_save(flags);
	check_flags(flags);

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

	return ret;
}
EXPORT_SYMBOL_GPL(lock_is_held);

3269 3270 3271 3272 3273 3274 3275 3276 3277 3278
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
3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292
#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 (",
3293
		curr->comm, task_pid_nr(curr));
P
Peter Zijlstra 已提交
3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313
	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
3314
	int i, contention_point, contending_point;
P
Peter Zijlstra 已提交
3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327

	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;
3328
		if (match_held_lock(hlock, lock))
P
Peter Zijlstra 已提交
3329 3330 3331 3332 3333 3334 3335
			goto found_it;
		prev_hlock = hlock;
	}
	print_lock_contention_bug(curr, lock, ip);
	return;

found_it:
3336 3337 3338
	if (hlock->instance != lock)
		return;

3339
	hlock->waittime_stamp = lockstat_clock();
P
Peter Zijlstra 已提交
3340

P
Peter Zijlstra 已提交
3341 3342 3343
	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
3344

D
Dave Jones 已提交
3345
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3346 3347 3348 3349
	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
3350 3351
	if (lock->cpu != smp_processor_id())
		stats->bounces[bounce_contended + !!hlock->read]++;
P
Peter Zijlstra 已提交
3352 3353 3354 3355
	put_lock_stats(stats);
}

static void
P
Peter Zijlstra 已提交
3356
__lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3357 3358 3359 3360 3361
{
	struct task_struct *curr = current;
	struct held_lock *hlock, *prev_hlock;
	struct lock_class_stats *stats;
	unsigned int depth;
3362
	u64 now, waittime = 0;
P
Peter Zijlstra 已提交
3363
	int i, cpu;
P
Peter Zijlstra 已提交
3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376

	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;
3377
		if (match_held_lock(hlock, lock))
P
Peter Zijlstra 已提交
3378 3379 3380 3381 3382 3383 3384
			goto found_it;
		prev_hlock = hlock;
	}
	print_lock_contention_bug(curr, lock, _RET_IP_);
	return;

found_it:
3385 3386 3387
	if (hlock->instance != lock)
		return;

P
Peter Zijlstra 已提交
3388 3389
	cpu = smp_processor_id();
	if (hlock->waittime_stamp) {
3390
		now = lockstat_clock();
P
Peter Zijlstra 已提交
3391 3392 3393
		waittime = now - hlock->waittime_stamp;
		hlock->holdtime_stamp = now;
	}
P
Peter Zijlstra 已提交
3394

3395 3396
	trace_lock_acquired(lock, ip, waittime);

D
Dave Jones 已提交
3397
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3398 3399 3400 3401 3402 3403 3404 3405
	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
3406
	put_lock_stats(stats);
P
Peter Zijlstra 已提交
3407 3408

	lock->cpu = cpu;
P
Peter Zijlstra 已提交
3409
	lock->ip = ip;
P
Peter Zijlstra 已提交
3410 3411 3412 3413 3414 3415
}

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

3416 3417
	trace_lock_contended(lock, ip);

P
Peter Zijlstra 已提交
3418 3419 3420 3421 3422 3423 3424 3425 3426 3427 3428 3429 3430 3431 3432
	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
3433
void lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3434 3435 3436 3437 3438 3439 3440 3441 3442 3443 3444 3445
{
	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
3446
	__lock_acquired(lock, ip);
P
Peter Zijlstra 已提交
3447 3448 3449 3450 3451 3452
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquired);
#endif

I
Ingo Molnar 已提交
3453 3454 3455 3456 3457 3458 3459 3460
/*
 * Used by the testsuite, sanitize the validator state
 * after a simulated failure:
 */

void lockdep_reset(void)
{
	unsigned long flags;
3461
	int i;
I
Ingo Molnar 已提交
3462 3463 3464 3465 3466 3467 3468 3469 3470 3471

	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;
3472 3473
	for (i = 0; i < CHAINHASH_SIZE; i++)
		INIT_LIST_HEAD(chainhash_table + i);
I
Ingo Molnar 已提交
3474 3475 3476 3477 3478 3479 3480 3481 3482 3483 3484 3485 3486 3487 3488 3489 3490 3491 3492 3493 3494
	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);

3495
	class->key = NULL;
I
Ingo Molnar 已提交
3496 3497
}

3498
static inline int within(const void *addr, void *start, unsigned long size)
I
Ingo Molnar 已提交
3499 3500 3501 3502 3503 3504 3505 3506 3507 3508
{
	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;
3509
	int locked;
I
Ingo Molnar 已提交
3510 3511

	raw_local_irq_save(flags);
3512
	locked = graph_lock();
I
Ingo Molnar 已提交
3513 3514 3515 3516 3517 3518 3519 3520

	/*
	 * 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;
3521
		list_for_each_entry_safe(class, next, head, hash_entry) {
I
Ingo Molnar 已提交
3522 3523
			if (within(class->key, start, size))
				zap_class(class);
3524 3525 3526
			else if (within(class->name, start, size))
				zap_class(class);
		}
I
Ingo Molnar 已提交
3527 3528
	}

3529 3530
	if (locked)
		graph_unlock();
I
Ingo Molnar 已提交
3531 3532 3533 3534 3535
	raw_local_irq_restore(flags);
}

void lockdep_reset_lock(struct lockdep_map *lock)
{
3536
	struct lock_class *class, *next;
I
Ingo Molnar 已提交
3537 3538 3539
	struct list_head *head;
	unsigned long flags;
	int i, j;
3540
	int locked;
I
Ingo Molnar 已提交
3541 3542 3543 3544

	raw_local_irq_save(flags);

	/*
3545 3546 3547 3548 3549 3550 3551 3552 3553 3554 3555 3556 3557
	 * 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
3558
	 */
3559
	locked = graph_lock();
I
Ingo Molnar 已提交
3560 3561 3562 3563 3564
	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) {
3565
			if (unlikely(class == lock->class_cache)) {
3566 3567
				if (debug_locks_off_graph_unlock())
					WARN_ON(1);
3568
				goto out_restore;
I
Ingo Molnar 已提交
3569 3570 3571
			}
		}
	}
3572 3573
	if (locked)
		graph_unlock();
3574 3575

out_restore:
I
Ingo Molnar 已提交
3576 3577 3578
	raw_local_irq_restore(flags);
}

3579
void lockdep_init(void)
I
Ingo Molnar 已提交
3580 3581 3582 3583 3584 3585 3586 3587 3588 3589 3590 3591 3592 3593 3594 3595 3596 3597 3598 3599 3600 3601 3602 3603 3604
{
	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");

3605
	printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
I
Ingo Molnar 已提交
3606 3607
	printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
	printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
3608
	printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
I
Ingo Molnar 已提交
3609 3610 3611 3612 3613 3614 3615 3616 3617
	printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
	printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
	printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);

	printk(" memory used by lock dependency info: %lu kB\n",
		(sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
		sizeof(struct list_head) * CLASSHASH_SIZE +
		sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
		sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
M
Ming Lei 已提交
3618
		sizeof(struct list_head) * CHAINHASH_SIZE
3619
#ifdef CONFIG_PROVE_LOCKING
3620
		+ sizeof(struct circular_queue)
3621
#endif
M
Ming Lei 已提交
3622
		) / 1024
3623
		);
I
Ingo Molnar 已提交
3624 3625 3626 3627 3628

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

#ifdef CONFIG_DEBUG_LOCKDEP
3629 3630 3631 3632 3633
	if (lockdep_init_error) {
		printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
		printk("Call stack leading to lockdep invocation was:\n");
		print_stack_trace(&lockdep_init_trace, 0);
	}
I
Ingo Molnar 已提交
3634 3635 3636 3637 3638
#endif
}

static void
print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
3639
		     const void *mem_to, struct held_lock *hlock)
I
Ingo Molnar 已提交
3640 3641 3642 3643 3644 3645 3646 3647 3648 3649
{
	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",
3650
		curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
3651
	print_lock(hlock);
I
Ingo Molnar 已提交
3652 3653 3654 3655 3656 3657
	lockdep_print_held_locks(curr);

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

O
Oleg Nesterov 已提交
3658 3659 3660 3661 3662 3663 3664
static inline int not_in_range(const void* mem_from, unsigned long mem_len,
				const void* lock_from, unsigned long lock_len)
{
	return lock_from + lock_len <= mem_from ||
		mem_from + mem_len <= lock_from;
}

I
Ingo Molnar 已提交
3665 3666 3667 3668 3669 3670 3671 3672 3673 3674 3675 3676 3677 3678 3679 3680 3681 3682 3683
/*
 * Called when kernel memory is freed (or unmapped), or if a lock
 * is destroyed or reinitialized - this code checks whether there is
 * any held lock in the memory range of <from> to <to>:
 */
void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
{
	struct task_struct *curr = current;
	struct held_lock *hlock;
	unsigned long flags;
	int i;

	if (unlikely(!debug_locks))
		return;

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

O
Oleg Nesterov 已提交
3684 3685
		if (not_in_range(mem_from, mem_len, hlock->instance,
					sizeof(*hlock->instance)))
I
Ingo Molnar 已提交
3686 3687
			continue;

O
Oleg Nesterov 已提交
3688
		print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
I
Ingo Molnar 已提交
3689 3690 3691 3692
		break;
	}
	local_irq_restore(flags);
}
3693
EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
I
Ingo Molnar 已提交
3694 3695 3696 3697 3698 3699 3700 3701 3702 3703 3704 3705

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",
3706
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
3707 3708 3709 3710 3711 3712 3713 3714 3715 3716 3717 3718 3719 3720 3721 3722 3723 3724
	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;

3725 3726 3727 3728
	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
I
Ingo Molnar 已提交
3729 3730 3731 3732 3733 3734 3735 3736 3737 3738 3739 3740 3741 3742 3743 3744 3745 3746 3747 3748
	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;
3749 3750 3751
	} else {
		if (count != 10)
			printk(KERN_CONT " locked it.\n");
I
Ingo Molnar 已提交
3752 3753 3754
	}

	do_each_thread(g, p) {
I
Ingo Molnar 已提交
3755 3756 3757 3758 3759 3760 3761
		/*
		 * It's not reliable to print a task's held locks
		 * if it's not sleeping (or if it's not the current
		 * task):
		 */
		if (p->state == TASK_RUNNING && p != current)
			continue;
I
Ingo Molnar 已提交
3762 3763 3764 3765 3766 3767 3768 3769 3770 3771 3772 3773 3774 3775 3776
		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);

3777 3778 3779 3780 3781
/*
 * Careful: only use this function if you are sure that
 * the task cannot run in parallel!
 */
void __debug_show_held_locks(struct task_struct *task)
I
Ingo Molnar 已提交
3782
{
3783 3784 3785 3786
	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
I
Ingo Molnar 已提交
3787 3788
	lockdep_print_held_locks(task);
}
3789 3790 3791 3792 3793 3794
EXPORT_SYMBOL_GPL(__debug_show_held_locks);

void debug_show_held_locks(struct task_struct *task)
{
		__debug_show_held_locks(task);
}
I
Ingo Molnar 已提交
3795
EXPORT_SYMBOL_GPL(debug_show_held_locks);
P
Peter Zijlstra 已提交
3796 3797 3798 3799 3800 3801 3802 3803 3804 3805 3806 3807 3808 3809 3810 3811

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);
	}
}
3812 3813 3814 3815 3816 3817 3818

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

	if (!debug_locks_off())
		return;
3819 3820 3821
	printk("\n===================================================\n");
	printk(  "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
	printk(  "---------------------------------------------------\n");
3822 3823 3824 3825 3826 3827 3828 3829
	printk("%s:%d invoked rcu_dereference_check() without protection!\n",
			file, line);
	printk("\nother info that might help us debug this:\n\n");
	lockdep_print_held_locks(curr);
	printk("\nstack backtrace:\n");
	dump_stack();
}
EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);