lockdep.c 107.9 KB
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/*
 * kernel/lockdep.c
 *
 * Runtime locking correctness validator
 *
 * Started by Ingo Molnar:
 *
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 *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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 *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
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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 <linux/gfp.h>
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#include <linux/kmemcheck.h>
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#include <linux/random.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)) {
		/*
		 * The lockdep graph lock isn't locked while we expect it to
		 * be, we're confused now, bye!
		 */
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		return DEBUG_LOCKS_WARN_ON(1);
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	}
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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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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) {
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		/*
		 * Someone passed in garbage, we give up.
		 */
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		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)
{
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	return local_clock();
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}

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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)))

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static struct hlist_head classhash_table[CLASSHASH_SIZE];
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/*
 * 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)))

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static struct hlist_head chainhash_table[CHAINHASH_SIZE];
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/*
 * 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];

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static void print_lockdep_off(const char *bug_msg)
{
	printk(KERN_DEBUG "%s\n", bug_msg);
	printk(KERN_DEBUG "turning off the locking correctness validator.\n");
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#ifdef CONFIG_LOCK_STAT
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	printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
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#endif
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}

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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;

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		print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
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		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
/*
 * Various lockdep statistics:
 */
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DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
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#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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}

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static void __print_lock_name(struct lock_class *class)
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{
	char str[KSYM_NAME_LEN];
	const char *name;

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

static void print_lock_name(struct lock_class *class)
{
	char usage[LOCK_USAGE_CHARS];

	get_usage_chars(class, usage);

	printk(" (");
	__print_lock_name(class);
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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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	/*
	 * We can be called locklessly through debug_show_all_locks() so be
	 * extra careful, the hlock might have been released and cleared.
	 */
	unsigned int class_idx = hlock->class_idx;

	/* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
	barrier();

	if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
		printk("<RELEASED>\n");
		return;
	}

	print_lock_name(lock_classes + class_idx - 1);
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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_ident(void)
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{
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	printk("%s %.*s %s\n", init_utsname()->release,
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		(int)strcspn(init_utsname()->version, " "),
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		init_utsname()->version,
		print_tainted());
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}

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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#ifdef __KERNEL__
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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;

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	/*
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Peter Zijlstra 已提交
602
	 * static variable?
I
Ingo Molnar 已提交
603
	 */
P
Peter Zijlstra 已提交
604 605
	if ((addr >= start) && (addr < end))
		return 1;
I
Ingo Molnar 已提交
606

607 608 609
	if (arch_is_kernel_data(addr))
		return 1;

I
Ingo Molnar 已提交
610
	/*
611
	 * in-kernel percpu var?
I
Ingo Molnar 已提交
612
	 */
613 614
	if (is_kernel_percpu_address(addr))
		return 1;
I
Ingo Molnar 已提交
615

P
Peter Zijlstra 已提交
616
	/*
617
	 * module static or percpu var?
P
Peter Zijlstra 已提交
618
	 */
619
	return is_module_address(addr) || is_module_percpu_address(addr);
620
}
621
#endif
622

I
Ingo Molnar 已提交
623
/*
P
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624 625
 * To make lock name printouts unique, we calculate a unique
 * class->name_version generation counter:
I
Ingo Molnar 已提交
626
 */
P
Peter Zijlstra 已提交
627
static int count_matching_names(struct lock_class *new_class)
I
Ingo Molnar 已提交
628
{
P
Peter Zijlstra 已提交
629 630
	struct lock_class *class;
	int count = 0;
I
Ingo Molnar 已提交
631

P
Peter Zijlstra 已提交
632
	if (!new_class->name)
I
Ingo Molnar 已提交
633 634
		return 0;

635
	list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
P
Peter Zijlstra 已提交
636 637 638 639 640
		if (new_class->key - new_class->subclass == class->key)
			return class->name_version;
		if (class->name && !strcmp(class->name, new_class->name))
			count = max(count, class->name_version);
	}
I
Ingo Molnar 已提交
641

P
Peter Zijlstra 已提交
642
	return count + 1;
I
Ingo Molnar 已提交
643 644
}

P
Peter Zijlstra 已提交
645 646 647 648 649 650 651
/*
 * Register a lock's class in the hash-table, if the class is not present
 * yet. Otherwise we look it up. We cache the result in the lock object
 * itself, so actual lookup of the hash should be once per lock object.
 */
static inline struct lock_class *
look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
I
Ingo Molnar 已提交
652
{
P
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653
	struct lockdep_subclass_key *key;
654
	struct hlist_head *hash_head;
P
Peter Zijlstra 已提交
655
	struct lock_class *class;
I
Ingo Molnar 已提交
656

657 658 659 660 661 662 663 664 665 666
	if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
		debug_locks_off();
		printk(KERN_ERR
			"BUG: looking up invalid subclass: %u\n", subclass);
		printk(KERN_ERR
			"turning off the locking correctness validator.\n");
		dump_stack();
		return NULL;
	}

P
Peter Zijlstra 已提交
667 668 669 670 671 672
	/*
	 * Static locks do not have their class-keys yet - for them the key
	 * is the lock object itself:
	 */
	if (unlikely(!lock->key))
		lock->key = (void *)lock;
I
Ingo Molnar 已提交
673

P
Peter Zijlstra 已提交
674 675 676 677 678 679
	/*
	 * 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.
	 */
P
Peter Zijlstra 已提交
680 681
	BUILD_BUG_ON(sizeof(struct lock_class_key) >
			sizeof(struct lockdep_map));
I
Ingo Molnar 已提交
682

P
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683
	key = lock->key->subkeys + subclass;
684

P
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685
	hash_head = classhashentry(key);
686

P
Peter Zijlstra 已提交
687
	/*
688
	 * We do an RCU walk of the hash, see lockdep_free_key_range().
P
Peter Zijlstra 已提交
689
	 */
690 691 692
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return NULL;

693
	hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
P
Peter Zijlstra 已提交
694
		if (class->key == key) {
P
Peter Zijlstra 已提交
695 696 697 698
			/*
			 * Huh! same key, different name? Did someone trample
			 * on some memory? We're most confused.
			 */
P
Peter Zijlstra 已提交
699
			WARN_ON_ONCE(class->name != lock->name);
P
Peter Zijlstra 已提交
700
			return class;
P
Peter Zijlstra 已提交
701 702
		}
	}
I
Ingo Molnar 已提交
703

P
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704
	return NULL;
I
Ingo Molnar 已提交
705 706 707
}

/*
P
Peter Zijlstra 已提交
708 709 710
 * Register a lock's class in the hash-table, if the class is not present
 * yet. Otherwise we look it up. We cache the result in the lock object
 * itself, so actual lookup of the hash should be once per lock object.
I
Ingo Molnar 已提交
711
 */
712
static struct lock_class *
P
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713
register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
I
Ingo Molnar 已提交
714
{
P
Peter Zijlstra 已提交
715
	struct lockdep_subclass_key *key;
716
	struct hlist_head *hash_head;
P
Peter Zijlstra 已提交
717
	struct lock_class *class;
718 719

	DEBUG_LOCKS_WARN_ON(!irqs_disabled());
P
Peter Zijlstra 已提交
720 721 722

	class = look_up_lock_class(lock, subclass);
	if (likely(class))
723
		goto out_set_class_cache;
P
Peter Zijlstra 已提交
724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747

	/*
	 * 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);

	if (!graph_lock()) {
		return NULL;
	}
	/*
	 * We have to do the hash-walk again, to avoid races
	 * with another CPU:
	 */
748
	hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
P
Peter Zijlstra 已提交
749 750
		if (class->key == key)
			goto out_unlock_set;
751 752
	}

P
Peter Zijlstra 已提交
753 754 755 756 757 758 759 760 761
	/*
	 * 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()) {
			return NULL;
		}

762
		print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
763
		dump_stack();
P
Peter Zijlstra 已提交
764 765 766
		return NULL;
	}
	class = lock_classes + nr_lock_classes++;
767
	debug_atomic_inc(nr_unused_locks);
P
Peter Zijlstra 已提交
768 769 770 771 772 773 774 775 776 777 778
	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:
	 */
779
	hlist_add_head_rcu(&class->hash_entry, hash_head);
780 781 782 783
	/*
	 * Add it to the global list of classes:
	 */
	list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
P
Peter Zijlstra 已提交
784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800

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

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

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

801
out_set_class_cache:
P
Peter Zijlstra 已提交
802
	if (!subclass || force)
803 804 805
		lock->class_cache[0] = class;
	else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
		lock->class_cache[subclass] = class;
P
Peter Zijlstra 已提交
806

P
Peter Zijlstra 已提交
807 808 809 810
	/*
	 * Hash collision, did we smoke some? We found a class with a matching
	 * hash but the subclass -- which is hashed in -- didn't match.
	 */
P
Peter Zijlstra 已提交
811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827
	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;

828
		print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
829
		dump_stack();
P
Peter Zijlstra 已提交
830 831 832 833 834 835 836 837 838
		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,
Y
Yong Zhang 已提交
839 840
			    struct list_head *head, unsigned long ip,
			    int distance, struct stack_trace *trace)
P
Peter Zijlstra 已提交
841 842 843 844 845 846 847 848 849 850
{
	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;

851 852
	entry->class = this;
	entry->distance = distance;
Y
Yong Zhang 已提交
853
	entry->trace = *trace;
P
Peter Zijlstra 已提交
854
	/*
855 856 857
	 * Both allocation and removal are done under the graph lock; but
	 * iteration is under RCU-sched; see look_up_lock_class() and
	 * lockdep_free_key_range().
P
Peter Zijlstra 已提交
858 859 860 861 862 863
	 */
	list_add_tail_rcu(&entry->entry, head);

	return 1;
}

P
Peter Zijlstra 已提交
864 865 866
/*
 * For good efficiency of modular, we use power of 2
 */
P
Peter Zijlstra 已提交
867 868 869
#define MAX_CIRCULAR_QUEUE_SIZE		4096UL
#define CQ_MASK				(MAX_CIRCULAR_QUEUE_SIZE-1)

P
Peter Zijlstra 已提交
870 871
/*
 * The circular_queue and helpers is used to implement the
P
Peter Zijlstra 已提交
872 873 874
 * 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
875
 */
P
Peter Zijlstra 已提交
876 877 878 879 880 881 882
struct circular_queue {
	unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
	unsigned int  front, rear;
};

static struct circular_queue lock_cq;

883
unsigned int max_bfs_queue_depth;
P
Peter Zijlstra 已提交
884

885 886
static unsigned int lockdep_dependency_gen_id;

P
Peter Zijlstra 已提交
887 888 889
static inline void __cq_init(struct circular_queue *cq)
{
	cq->front = cq->rear = 0;
890
	lockdep_dependency_gen_id++;
P
Peter Zijlstra 已提交
891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931
}

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;
P
Peter Zijlstra 已提交
932

P
Peter Zijlstra 已提交
933
	nr = lock - list_entries;
P
Peter Zijlstra 已提交
934
	WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
P
Peter Zijlstra 已提交
935
	lock->parent = parent;
936
	lock->class->dep_gen_id = lockdep_dependency_gen_id;
P
Peter Zijlstra 已提交
937 938 939 940 941
}

static inline unsigned long lock_accessed(struct lock_list *lock)
{
	unsigned long nr;
P
Peter Zijlstra 已提交
942

P
Peter Zijlstra 已提交
943
	nr = lock - list_entries;
P
Peter Zijlstra 已提交
944
	WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
945
	return lock->class->dep_gen_id == lockdep_dependency_gen_id;
P
Peter Zijlstra 已提交
946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964
}

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;
}

965
static int __bfs(struct lock_list *source_entry,
P
Peter Zijlstra 已提交
966 967 968 969
		 void *data,
		 int (*match)(struct lock_list *entry, void *data),
		 struct lock_list **target_entry,
		 int forward)
970 971
{
	struct lock_list *entry;
972
	struct list_head *head;
973 974 975
	struct circular_queue *cq = &lock_cq;
	int ret = 1;

976
	if (match(source_entry, data)) {
977 978 979 980 981
		*target_entry = source_entry;
		ret = 0;
		goto exit;
	}

982 983 984 985 986 987 988 989 990
	if (forward)
		head = &source_entry->class->locks_after;
	else
		head = &source_entry->class->locks_before;

	if (list_empty(head))
		goto exit;

	__cq_init(cq);
991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007
	__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;

1008 1009 1010
		DEBUG_LOCKS_WARN_ON(!irqs_disabled());

		list_for_each_entry_rcu(entry, head, entry) {
1011
			if (!lock_accessed(entry)) {
1012
				unsigned int cq_depth;
1013
				mark_lock_accessed(entry, lock);
1014
				if (match(entry, data)) {
1015 1016 1017 1018 1019 1020 1021 1022 1023
					*target_entry = entry;
					ret = 0;
					goto exit;
				}

				if (__cq_enqueue(cq, (unsigned long)entry)) {
					ret = -1;
					goto exit;
				}
1024 1025 1026
				cq_depth = __cq_get_elem_count(cq);
				if (max_bfs_queue_depth < cq_depth)
					max_bfs_queue_depth = cq_depth;
1027 1028 1029 1030 1031 1032 1033
			}
		}
	}
exit:
	return ret;
}

1034
static inline int __bfs_forwards(struct lock_list *src_entry,
1035 1036 1037
			void *data,
			int (*match)(struct lock_list *entry, void *data),
			struct lock_list **target_entry)
1038
{
1039
	return __bfs(src_entry, data, match, target_entry, 1);
1040 1041 1042

}

1043
static inline int __bfs_backwards(struct lock_list *src_entry,
1044 1045 1046
			void *data,
			int (*match)(struct lock_list *entry, void *data),
			struct lock_list **target_entry)
1047
{
1048
	return __bfs(src_entry, data, match, target_entry, 0);
1049 1050 1051

}

P
Peter Zijlstra 已提交
1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062
/*
 * 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
1063
print_circular_bug_entry(struct lock_list *target, int depth)
P
Peter Zijlstra 已提交
1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074
{
	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;
}

1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124
static void
print_circular_lock_scenario(struct held_lock *src,
			     struct held_lock *tgt,
			     struct lock_list *prt)
{
	struct lock_class *source = hlock_class(src);
	struct lock_class *target = hlock_class(tgt);
	struct lock_class *parent = prt->class;

	/*
	 * A direct locking problem where unsafe_class lock is taken
	 * directly by safe_class lock, then all we need to show
	 * is the deadlock scenario, as it is obvious that the
	 * unsafe lock is taken under the safe lock.
	 *
	 * But if there is a chain instead, where the safe lock takes
	 * an intermediate lock (middle_class) where this lock is
	 * not the same as the safe lock, then the lock chain is
	 * used to describe the problem. Otherwise we would need
	 * to show a different CPU case for each link in the chain
	 * from the safe_class lock to the unsafe_class lock.
	 */
	if (parent != source) {
		printk("Chain exists of:\n  ");
		__print_lock_name(source);
		printk(" --> ");
		__print_lock_name(parent);
		printk(" --> ");
		__print_lock_name(target);
		printk("\n\n");
	}

	printk(" Possible unsafe locking scenario:\n\n");
	printk("       CPU0                    CPU1\n");
	printk("       ----                    ----\n");
	printk("  lock(");
	__print_lock_name(target);
	printk(");\n");
	printk("                               lock(");
	__print_lock_name(parent);
	printk(");\n");
	printk("                               lock(");
	__print_lock_name(target);
	printk(");\n");
	printk("  lock(");
	__print_lock_name(source);
	printk(");\n");
	printk("\n *** DEADLOCK ***\n\n");
}

P
Peter Zijlstra 已提交
1125 1126 1127 1128 1129
/*
 * When a circular dependency is detected, print the
 * header first:
 */
static noinline int
1130 1131 1132
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
1133 1134 1135
{
	struct task_struct *curr = current;

1136
	if (debug_locks_silent)
P
Peter Zijlstra 已提交
1137 1138
		return 0;

1139 1140 1141
	printk("\n");
	printk("======================================================\n");
	printk("[ INFO: possible circular locking dependency detected ]\n");
1142
	print_kernel_ident();
1143
	printk("-------------------------------------------------------\n");
P
Peter Zijlstra 已提交
1144
	printk("%s/%d is trying to acquire lock:\n",
1145
		curr->comm, task_pid_nr(curr));
1146
	print_lock(check_src);
P
Peter Zijlstra 已提交
1147
	printk("\nbut task is already holding lock:\n");
1148
	print_lock(check_tgt);
P
Peter Zijlstra 已提交
1149 1150 1151 1152 1153 1154 1155 1156
	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;
}

1157 1158 1159 1160 1161
static inline int class_equal(struct lock_list *entry, void *data)
{
	return entry->class == data;
}

1162 1163 1164 1165
static noinline int print_circular_bug(struct lock_list *this,
				struct lock_list *target,
				struct held_lock *check_src,
				struct held_lock *check_tgt)
P
Peter Zijlstra 已提交
1166 1167
{
	struct task_struct *curr = current;
1168
	struct lock_list *parent;
1169
	struct lock_list *first_parent;
1170
	int depth;
P
Peter Zijlstra 已提交
1171

1172
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
P
Peter Zijlstra 已提交
1173 1174
		return 0;

1175
	if (!save_trace(&this->trace))
P
Peter Zijlstra 已提交
1176 1177
		return 0;

1178 1179
	depth = get_lock_depth(target);

1180
	print_circular_bug_header(target, depth, check_src, check_tgt);
1181 1182

	parent = get_lock_parent(target);
1183
	first_parent = parent;
1184 1185 1186 1187 1188

	while (parent) {
		print_circular_bug_entry(parent, --depth);
		parent = get_lock_parent(parent);
	}
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	printk("\nother info that might help us debug this:\n\n");
1191 1192 1193
	print_circular_lock_scenario(check_src, check_tgt,
				     first_parent);

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	lockdep_print_held_locks(curr);

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

	return 0;
}

1202 1203 1204 1205 1206
static noinline int print_bfs_bug(int ret)
{
	if (!debug_locks_off_graph_unlock())
		return 0;

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	/*
	 * Breadth-first-search failed, graph got corrupted?
	 */
1210 1211 1212 1213 1214
	WARN(1, "lockdep bfs error:%d\n", ret);

	return 0;
}

1215
static int noop_count(struct lock_list *entry, void *data)
1216
{
1217 1218 1219
	(*(unsigned long *)data)++;
	return 0;
}
1220

1221
static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
1222 1223 1224
{
	unsigned long  count = 0;
	struct lock_list *uninitialized_var(target_entry);
1225

1226
	__bfs_forwards(this, (void *)&count, noop_count, &target_entry);
1227

1228
	return count;
1229 1230 1231 1232
}
unsigned long lockdep_count_forward_deps(struct lock_class *class)
{
	unsigned long ret, flags;
1233 1234 1235 1236
	struct lock_list this;

	this.parent = NULL;
	this.class = class;
1237 1238

	local_irq_save(flags);
1239
	arch_spin_lock(&lockdep_lock);
1240
	ret = __lockdep_count_forward_deps(&this);
1241
	arch_spin_unlock(&lockdep_lock);
1242 1243 1244 1245 1246
	local_irq_restore(flags);

	return ret;
}

1247
static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
1248
{
1249 1250
	unsigned long  count = 0;
	struct lock_list *uninitialized_var(target_entry);
1251

1252
	__bfs_backwards(this, (void *)&count, noop_count, &target_entry);
1253

1254
	return count;
1255 1256 1257 1258 1259
}

unsigned long lockdep_count_backward_deps(struct lock_class *class)
{
	unsigned long ret, flags;
1260 1261 1262 1263
	struct lock_list this;

	this.parent = NULL;
	this.class = class;
1264 1265

	local_irq_save(flags);
1266
	arch_spin_lock(&lockdep_lock);
1267
	ret = __lockdep_count_backward_deps(&this);
1268
	arch_spin_unlock(&lockdep_lock);
1269 1270 1271 1272 1273
	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
1279 1280
check_noncircular(struct lock_list *root, struct lock_class *target,
		struct lock_list **target_entry)
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1281
{
1282
	int result;
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1283

1284
	debug_atomic_inc(nr_cyclic_checks);
1285

1286
	result = __bfs_forwards(root, target, class_equal, target_entry);
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1287

1288 1289
	return result;
}
1290

1291
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
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/*
 * Forwards and backwards subgraph searching, for the purposes of
 * proving that two subgraphs can be connected by a new dependency
 * without creating any illegal irq-safe -> irq-unsafe lock dependency.
 */

1298 1299 1300 1301 1302 1303 1304
static inline int usage_match(struct lock_list *entry, void *bit)
{
	return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
}



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1305 1306
/*
 * Find a node in the forwards-direction dependency sub-graph starting
1307
 * at @root->class that matches @bit.
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1308
 *
1309 1310
 * Return 0 if such a node exists in the subgraph, and put that node
 * into *@target_entry.
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1311
 *
1312 1313
 * Return 1 otherwise and keep *@target_entry unchanged.
 * Return <0 on error.
I
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1314
 */
1315 1316 1317
static int
find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
			struct lock_list **target_entry)
I
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1318
{
1319
	int result;
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1320

1321
	debug_atomic_inc(nr_find_usage_forwards_checks);
I
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1322

1323 1324 1325
	result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);

	return result;
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1326 1327 1328 1329
}

/*
 * Find a node in the backwards-direction dependency sub-graph starting
1330
 * at @root->class that matches @bit.
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1331
 *
1332 1333
 * Return 0 if such a node exists in the subgraph, and put that node
 * into *@target_entry.
I
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1334
 *
1335 1336
 * Return 1 otherwise and keep *@target_entry unchanged.
 * Return <0 on error.
I
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1337
 */
1338 1339 1340
static int
find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
			struct lock_list **target_entry)
I
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1341
{
1342
	int result;
I
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1343

1344
	debug_atomic_inc(nr_find_usage_backwards_checks);
I
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1345

1346
	result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
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1347

1348
	return result;
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1349 1350
}

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1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394
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)) {
1395
			printk("lockdep:%s bad path found in chain graph\n", __func__);
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			break;
		}

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

	return;
}
1405

1406 1407 1408
static void
print_irq_lock_scenario(struct lock_list *safe_entry,
			struct lock_list *unsafe_entry,
1409 1410
			struct lock_class *prev_class,
			struct lock_class *next_class)
1411 1412 1413
{
	struct lock_class *safe_class = safe_entry->class;
	struct lock_class *unsafe_class = unsafe_entry->class;
1414
	struct lock_class *middle_class = prev_class;
1415 1416

	if (middle_class == safe_class)
1417
		middle_class = next_class;
1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461

	/*
	 * A direct locking problem where unsafe_class lock is taken
	 * directly by safe_class lock, then all we need to show
	 * is the deadlock scenario, as it is obvious that the
	 * unsafe lock is taken under the safe lock.
	 *
	 * But if there is a chain instead, where the safe lock takes
	 * an intermediate lock (middle_class) where this lock is
	 * not the same as the safe lock, then the lock chain is
	 * used to describe the problem. Otherwise we would need
	 * to show a different CPU case for each link in the chain
	 * from the safe_class lock to the unsafe_class lock.
	 */
	if (middle_class != unsafe_class) {
		printk("Chain exists of:\n  ");
		__print_lock_name(safe_class);
		printk(" --> ");
		__print_lock_name(middle_class);
		printk(" --> ");
		__print_lock_name(unsafe_class);
		printk("\n\n");
	}

	printk(" Possible interrupt unsafe locking scenario:\n\n");
	printk("       CPU0                    CPU1\n");
	printk("       ----                    ----\n");
	printk("  lock(");
	__print_lock_name(unsafe_class);
	printk(");\n");
	printk("                               local_irq_disable();\n");
	printk("                               lock(");
	__print_lock_name(safe_class);
	printk(");\n");
	printk("                               lock(");
	__print_lock_name(middle_class);
	printk(");\n");
	printk("  <Interrupt>\n");
	printk("    lock(");
	__print_lock_name(safe_class);
	printk(");\n");
	printk("\n *** DEADLOCK ***\n\n");
}

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1462 1463
static int
print_bad_irq_dependency(struct task_struct *curr,
1464 1465 1466 1467
			 struct lock_list *prev_root,
			 struct lock_list *next_root,
			 struct lock_list *backwards_entry,
			 struct lock_list *forwards_entry,
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1468 1469 1470 1471 1472 1473
			 struct held_lock *prev,
			 struct held_lock *next,
			 enum lock_usage_bit bit1,
			 enum lock_usage_bit bit2,
			 const char *irqclass)
{
1474
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
1475 1476
		return 0;

1477 1478 1479
	printk("\n");
	printk("======================================================\n");
	printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
I
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1480
		irqclass, irqclass);
1481
	print_kernel_ident();
1482
	printk("------------------------------------------------------\n");
I
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1483
	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
1484
		curr->comm, task_pid_nr(curr),
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1485 1486 1487 1488 1489 1490 1491 1492 1493
		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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1494
	print_lock_name(hlock_class(prev));
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1495
	printk(" ->");
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1496
	print_lock_name(hlock_class(next));
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1497 1498 1499 1500
	printk("\n");

	printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
		irqclass);
1501
	print_lock_name(backwards_entry->class);
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1502 1503
	printk("\n... which became %s-irq-safe at:\n", irqclass);

1504
	print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
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1505 1506

	printk("\nto a %s-irq-unsafe lock:\n", irqclass);
1507
	print_lock_name(forwards_entry->class);
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1508 1509 1510
	printk("\n... which became %s-irq-unsafe at:\n", irqclass);
	printk("...");

1511
	print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
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1512 1513

	printk("\nother info that might help us debug this:\n\n");
1514 1515
	print_irq_lock_scenario(backwards_entry, forwards_entry,
				hlock_class(prev), hlock_class(next));
1516

I
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1517 1518
	lockdep_print_held_locks(curr);

1519 1520 1521 1522 1523
	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);
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1524

1525 1526 1527 1528 1529
	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);
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1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542

	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;
1543
	struct lock_list this, that;
1544
	struct lock_list *uninitialized_var(target_entry);
1545
	struct lock_list *uninitialized_var(target_entry1);
1546 1547 1548 1549 1550

	this.parent = NULL;

	this.class = hlock_class(prev);
	ret = find_usage_backwards(&this, bit_backwards, &target_entry);
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1551 1552 1553 1554
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
1555

1556 1557 1558
	that.parent = NULL;
	that.class = hlock_class(next);
	ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
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1559 1560 1561 1562
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
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1563

1564 1565 1566
	return print_bad_irq_dependency(curr, &this, &that,
			target_entry, target_entry1,
			prev, next,
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Ingo Molnar 已提交
1567 1568 1569
			bit_backwards, bit_forwards, irqclass);
}

1570 1571
static const char *state_names[] = {
#define LOCKDEP_STATE(__STATE) \
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1572
	__stringify(__STATE),
1573 1574 1575 1576 1577 1578
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

static const char *state_rnames[] = {
#define LOCKDEP_STATE(__STATE) \
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1579
	__stringify(__STATE)"-READ",
1580 1581 1582 1583 1584
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};

static inline const char *state_name(enum lock_usage_bit bit)
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1585
{
1586 1587
	return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
}
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1588

1589 1590
static int exclusive_bit(int new_bit)
{
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1591
	/*
1592 1593 1594 1595 1596 1597 1598 1599
	 * USED_IN
	 * USED_IN_READ
	 * ENABLED
	 * ENABLED_READ
	 *
	 * bit 0 - write/read
	 * bit 1 - used_in/enabled
	 * bit 2+  state
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1600
	 */
1601 1602 1603

	int state = new_bit & ~3;
	int dir = new_bit & 2;
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1604 1605

	/*
1606
	 * keep state, bit flip the direction and strip read.
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1607
	 */
1608 1609 1610 1611 1612 1613
	return state | (dir ^ 2);
}

static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
			   struct held_lock *next, enum lock_usage_bit bit)
{
P
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1614
	/*
1615 1616
	 * Prove that the new dependency does not connect a hardirq-safe
	 * lock with a hardirq-unsafe lock - to achieve this we search
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1617 1618 1619
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
1620 1621
	if (!check_usage(curr, prev, next, bit,
			   exclusive_bit(bit), state_name(bit)))
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1622 1623
		return 0;

1624 1625
	bit++; /* _READ */

1626
	/*
1627 1628
	 * Prove that the new dependency does not connect a hardirq-safe-read
	 * lock with a hardirq-unsafe lock - to achieve this we search
1629 1630 1631
	 * the backwards-subgraph starting at <prev>, and the
	 * forwards-subgraph starting at <next>:
	 */
1632 1633
	if (!check_usage(curr, prev, next, bit,
			   exclusive_bit(bit), state_name(bit)))
1634 1635
		return 0;

1636 1637 1638 1639 1640 1641 1642 1643 1644
	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))	\
1645
		return 0;
1646 1647
#include "lockdep_states.h"
#undef LOCKDEP_STATE
1648

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	return 1;
}

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

#else

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

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

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1678 1679
#endif

1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699
static void
print_deadlock_scenario(struct held_lock *nxt,
			     struct held_lock *prv)
{
	struct lock_class *next = hlock_class(nxt);
	struct lock_class *prev = hlock_class(prv);

	printk(" Possible unsafe locking scenario:\n\n");
	printk("       CPU0\n");
	printk("       ----\n");
	printk("  lock(");
	__print_lock_name(prev);
	printk(");\n");
	printk("  lock(");
	__print_lock_name(next);
	printk(");\n");
	printk("\n *** DEADLOCK ***\n\n");
	printk(" May be due to missing lock nesting notation\n\n");
}

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Ingo Molnar 已提交
1700 1701 1702 1703
static int
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
		   struct held_lock *next)
{
1704
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
1705 1706
		return 0;

1707 1708 1709
	printk("\n");
	printk("=============================================\n");
	printk("[ INFO: possible recursive locking detected ]\n");
1710
	print_kernel_ident();
1711
	printk("---------------------------------------------\n");
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1712
	printk("%s/%d is trying to acquire lock:\n",
1713
		curr->comm, task_pid_nr(curr));
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1714 1715 1716 1717 1718
	print_lock(next);
	printk("\nbut task is already holding lock:\n");
	print_lock(prev);

	printk("\nother info that might help us debug this:\n");
1719
	print_deadlock_scenario(next, prev);
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1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740
	lockdep_print_held_locks(curr);

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

	return 0;
}

/*
 * Check whether we are holding such a class already.
 *
 * (Note that this has to be done separately, because the graph cannot
 * detect such classes of deadlocks.)
 *
 * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
 */
static int
check_deadlock(struct task_struct *curr, struct held_lock *next,
	       struct lockdep_map *next_instance, int read)
{
	struct held_lock *prev;
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1741
	struct held_lock *nest = NULL;
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1742 1743 1744 1745
	int i;

	for (i = 0; i < curr->lockdep_depth; i++) {
		prev = curr->held_locks + i;
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1746 1747 1748 1749

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

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1750
		if (hlock_class(prev) != hlock_class(next))
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1751
			continue;
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1752

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1753 1754
		/*
		 * Allow read-after-read recursion of the same
1755
		 * lock class (i.e. read_lock(lock)+read_lock(lock)):
I
Ingo Molnar 已提交
1756
		 */
1757
		if ((read == 2) && prev->read)
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1758
			return 2;
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1759 1760 1761 1762 1763 1764 1765 1766

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

I
Ingo Molnar 已提交
1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795
		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,
1796
	       struct held_lock *next, int distance, int *stack_saved)
I
Ingo Molnar 已提交
1797 1798 1799
{
	struct lock_list *entry;
	int ret;
1800 1801
	struct lock_list this;
	struct lock_list *uninitialized_var(target_entry);
Y
Yong Zhang 已提交
1802 1803 1804 1805 1806 1807 1808 1809
	/*
	 * Static variable, serialized by the graph_lock().
	 *
	 * We use this static variable to save the stack trace in case
	 * we call into this function multiple times due to encountering
	 * trylocks in the held lock stack.
	 */
	static struct stack_trace trace;
I
Ingo Molnar 已提交
1810 1811 1812 1813 1814 1815 1816 1817 1818 1819

	/*
	 * 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:
	 */
1820 1821 1822 1823 1824 1825 1826
	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);
1827

P
Peter Zijlstra 已提交
1828
	if (!check_prev_add_irq(curr, prev, next))
I
Ingo Molnar 已提交
1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848
		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
1849 1850
	list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
		if (entry->class == hlock_class(next)) {
1851 1852
			if (distance == 1)
				entry->distance = 1;
I
Ingo Molnar 已提交
1853
			return 2;
1854
		}
I
Ingo Molnar 已提交
1855 1856
	}

1857 1858 1859 1860 1861
	if (!*stack_saved) {
		if (!save_trace(&trace))
			return 0;
		*stack_saved = 1;
	}
Y
Yong Zhang 已提交
1862

I
Ingo Molnar 已提交
1863 1864 1865 1866
	/*
	 * Ok, all validations passed, add the new lock
	 * to the previous lock's dependency list:
	 */
D
Dave Jones 已提交
1867 1868
	ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
			       &hlock_class(prev)->locks_after,
Y
Yong Zhang 已提交
1869
			       next->acquire_ip, distance, &trace);
1870

I
Ingo Molnar 已提交
1871 1872
	if (!ret)
		return 0;
1873

D
Dave Jones 已提交
1874 1875
	ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
			       &hlock_class(next)->locks_before,
Y
Yong Zhang 已提交
1876
			       next->acquire_ip, distance, &trace);
1877 1878
	if (!ret)
		return 0;
I
Ingo Molnar 已提交
1879 1880

	/*
P
Peter Zijlstra 已提交
1881 1882
	 * Debugging printouts:
	 */
D
Dave Jones 已提交
1883
	if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
1884 1885
		/* We drop graph lock, so another thread can overwrite trace. */
		*stack_saved = 0;
P
Peter Zijlstra 已提交
1886 1887
		graph_unlock();
		printk("\n new dependency: ");
D
Dave Jones 已提交
1888
		print_lock_name(hlock_class(prev));
P
Peter Zijlstra 已提交
1889
		printk(" => ");
D
Dave Jones 已提交
1890
		print_lock_name(hlock_class(next));
P
Peter Zijlstra 已提交
1891
		printk("\n");
I
Ingo Molnar 已提交
1892
		dump_stack();
P
Peter Zijlstra 已提交
1893
		return graph_lock();
I
Ingo Molnar 已提交
1894
	}
P
Peter Zijlstra 已提交
1895 1896
	return 1;
}
I
Ingo Molnar 已提交
1897

P
Peter Zijlstra 已提交
1898 1899 1900 1901 1902 1903 1904 1905 1906 1907
/*
 * 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;
1908
	int stack_saved = 0;
P
Peter Zijlstra 已提交
1909
	struct held_lock *hlock;
1910

I
Ingo Molnar 已提交
1911
	/*
P
Peter Zijlstra 已提交
1912 1913 1914
	 * Debugging checks.
	 *
	 * Depth must not be zero for a non-head lock:
I
Ingo Molnar 已提交
1915
	 */
P
Peter Zijlstra 已提交
1916 1917
	if (!depth)
		goto out_bug;
I
Ingo Molnar 已提交
1918
	/*
P
Peter Zijlstra 已提交
1919 1920
	 * At least two relevant locks must exist for this
	 * to be a head:
I
Ingo Molnar 已提交
1921
	 */
P
Peter Zijlstra 已提交
1922 1923 1924
	if (curr->held_locks[depth].irq_context !=
			curr->held_locks[depth-1].irq_context)
		goto out_bug;
1925

P
Peter Zijlstra 已提交
1926 1927
	for (;;) {
		int distance = curr->lockdep_depth - depth + 1;
1928
		hlock = curr->held_locks + depth - 1;
P
Peter Zijlstra 已提交
1929 1930 1931 1932
		/*
		 * Only non-recursive-read entries get new dependencies
		 * added:
		 */
1933
		if (hlock->read != 2 && hlock->check) {
Y
Yong Zhang 已提交
1934
			if (!check_prev_add(curr, hlock, next,
1935
						distance, &stack_saved))
P
Peter Zijlstra 已提交
1936 1937 1938 1939 1940 1941 1942 1943 1944
				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;
1945
		}
P
Peter Zijlstra 已提交
1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957
		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
1958
	}
P
Peter Zijlstra 已提交
1959 1960 1961 1962
	return 1;
out_bug:
	if (!debug_locks_off_graph_unlock())
		return 0;
I
Ingo Molnar 已提交
1963

P
Peter Zijlstra 已提交
1964 1965 1966 1967 1968
	/*
	 * Clearly we all shouldn't be here, but since we made it we
	 * can reliable say we messed up our state. See the above two
	 * gotos for reasons why we could possibly end up here.
	 */
P
Peter Zijlstra 已提交
1969
	WARN_ON(1);
I
Ingo Molnar 已提交
1970

P
Peter Zijlstra 已提交
1971
	return 0;
I
Ingo Molnar 已提交
1972 1973
}

P
Peter Zijlstra 已提交
1974
unsigned long nr_lock_chains;
1975
struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
1976
int nr_chain_hlocks;
1977 1978 1979 1980 1981 1982
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
1983

1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
/*
 * Returns the index of the first held_lock of the current chain
 */
static inline int get_first_held_lock(struct task_struct *curr,
					struct held_lock *hlock)
{
	int i;
	struct held_lock *hlock_curr;

	for (i = curr->lockdep_depth - 1; i >= 0; i--) {
		hlock_curr = curr->held_locks + i;
		if (hlock_curr->irq_context != hlock->irq_context)
			break;

	}

	return ++i;
}

2003
#ifdef CONFIG_DEBUG_LOCKDEP
2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073
/*
 * Returns the next chain_key iteration
 */
static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
{
	u64 new_chain_key = iterate_chain_key(chain_key, class_idx);

	printk(" class_idx:%d -> chain_key:%016Lx",
		class_idx,
		(unsigned long long)new_chain_key);
	return new_chain_key;
}

static void
print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
{
	struct held_lock *hlock;
	u64 chain_key = 0;
	int depth = curr->lockdep_depth;
	int i;

	printk("depth: %u\n", depth + 1);
	for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
		hlock = curr->held_locks + i;
		chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);

		print_lock(hlock);
	}

	print_chain_key_iteration(hlock_next->class_idx, chain_key);
	print_lock(hlock_next);
}

static void print_chain_keys_chain(struct lock_chain *chain)
{
	int i;
	u64 chain_key = 0;
	int class_id;

	printk("depth: %u\n", chain->depth);
	for (i = 0; i < chain->depth; i++) {
		class_id = chain_hlocks[chain->base + i];
		chain_key = print_chain_key_iteration(class_id + 1, chain_key);

		print_lock_name(lock_classes + class_id);
		printk("\n");
	}
}

static void print_collision(struct task_struct *curr,
			struct held_lock *hlock_next,
			struct lock_chain *chain)
{
	printk("\n");
	printk("======================\n");
	printk("[chain_key collision ]\n");
	print_kernel_ident();
	printk("----------------------\n");
	printk("%s/%d: ", current->comm, task_pid_nr(current));
	printk("Hash chain already cached but the contents don't match!\n");

	printk("Held locks:");
	print_chain_keys_held_locks(curr, hlock_next);

	printk("Locks in cached chain:");
	print_chain_keys_chain(chain);

	printk("\nstack backtrace:\n");
	dump_stack();
}
2074
#endif
2075

2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090
/*
 * Checks whether the chain and the current held locks are consistent
 * in depth and also in content. If they are not it most likely means
 * that there was a collision during the calculation of the chain_key.
 * Returns: 0 not passed, 1 passed
 */
static int check_no_collision(struct task_struct *curr,
			struct held_lock *hlock,
			struct lock_chain *chain)
{
#ifdef CONFIG_DEBUG_LOCKDEP
	int i, j, id;

	i = get_first_held_lock(curr, hlock);

2091 2092
	if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
		print_collision(curr, hlock, chain);
2093
		return 0;
2094
	}
2095 2096 2097 2098

	for (j = 0; j < chain->depth - 1; j++, i++) {
		id = curr->held_locks[i].class_idx - 1;

2099 2100
		if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
			print_collision(curr, hlock, chain);
2101
			return 0;
2102
		}
2103 2104 2105 2106 2107
	}
#endif
	return 1;
}

I
Ingo Molnar 已提交
2108 2109
/*
 * Look up a dependency chain. If the key is not present yet then
2110 2111 2112
 * 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
2113
 */
2114 2115 2116
static inline int lookup_chain_cache(struct task_struct *curr,
				     struct held_lock *hlock,
				     u64 chain_key)
I
Ingo Molnar 已提交
2117
{
D
Dave Jones 已提交
2118
	struct lock_class *class = hlock_class(hlock);
2119
	struct hlist_head *hash_head = chainhashentry(chain_key);
I
Ingo Molnar 已提交
2120
	struct lock_chain *chain;
2121
	int i, j;
I
Ingo Molnar 已提交
2122

P
Peter Zijlstra 已提交
2123 2124 2125 2126 2127
	/*
	 * We might need to take the graph lock, ensure we've got IRQs
	 * disabled to make this an IRQ-safe lock.. for recursion reasons
	 * lockdep won't complain about its own locking errors.
	 */
2128 2129
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return 0;
I
Ingo Molnar 已提交
2130 2131 2132 2133
	/*
	 * We can walk it lock-free, because entries only get added
	 * to the hash:
	 */
2134
	hlist_for_each_entry_rcu(chain, hash_head, entry) {
I
Ingo Molnar 已提交
2135 2136
		if (chain->chain_key == chain_key) {
cache_hit:
2137
			debug_atomic_inc(chain_lookup_hits);
2138 2139 2140
			if (!check_no_collision(curr, hlock, chain))
				return 0;

2141
			if (very_verbose(class))
2142 2143 2144 2145
				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
2146 2147 2148
			return 0;
		}
	}
2149
	if (very_verbose(class))
2150 2151
		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
2152 2153 2154 2155
	/*
	 * Allocate a new chain entry from the static array, and add
	 * it to the hash:
	 */
2156 2157
	if (!graph_lock())
		return 0;
I
Ingo Molnar 已提交
2158 2159 2160
	/*
	 * We have to walk the chain again locked - to avoid duplicates:
	 */
2161
	hlist_for_each_entry(chain, hash_head, entry) {
I
Ingo Molnar 已提交
2162
		if (chain->chain_key == chain_key) {
2163
			graph_unlock();
I
Ingo Molnar 已提交
2164 2165 2166 2167
			goto cache_hit;
		}
	}
	if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
2168 2169 2170
		if (!debug_locks_off_graph_unlock())
			return 0;

2171
		print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
2172
		dump_stack();
I
Ingo Molnar 已提交
2173 2174 2175 2176
		return 0;
	}
	chain = lock_chains + nr_lock_chains++;
	chain->chain_key = chain_key;
2177
	chain->irq_context = hlock->irq_context;
2178
	i = get_first_held_lock(curr, hlock);
2179
	chain->depth = curr->lockdep_depth + 1 - i;
2180 2181 2182 2183 2184

	BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
	BUILD_BUG_ON((1UL << 6)  <= ARRAY_SIZE(curr->held_locks));
	BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));

2185 2186
	if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
		chain->base = nr_chain_hlocks;
2187
		for (j = 0; j < chain->depth - 1; j++, i++) {
D
Dave Jones 已提交
2188
			int lock_id = curr->held_locks[i].class_idx - 1;
2189 2190 2191 2192
			chain_hlocks[chain->base + j] = lock_id;
		}
		chain_hlocks[chain->base + j] = class - lock_classes;
	}
2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210

	if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
		nr_chain_hlocks += chain->depth;

#ifdef CONFIG_DEBUG_LOCKDEP
	/*
	 * Important for check_no_collision().
	 */
	if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
		if (debug_locks_off_graph_unlock())
			return 0;

		print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
		dump_stack();
		return 0;
	}
#endif

2211
	hlist_add_head_rcu(&chain->entry, hash_head);
2212
	debug_atomic_inc(chain_lookup_misses);
P
Peter Zijlstra 已提交
2213 2214 2215 2216 2217 2218
	inc_chains();

	return 1;
}

static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
2219
		struct held_lock *hlock, int chain_head, u64 chain_key)
P
Peter Zijlstra 已提交
2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230
{
	/*
	 * 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)
	 */
2231
	if (!hlock->trylock && hlock->check &&
2232
	    lookup_chain_cache(curr, hlock, chain_key)) {
P
Peter Zijlstra 已提交
2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267
		/*
		 * 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
2268 2269 2270

	return 1;
}
P
Peter Zijlstra 已提交
2271 2272 2273
#else
static inline int validate_chain(struct task_struct *curr,
	       	struct lockdep_map *lock, struct held_lock *hlock,
2274
		int chain_head, u64 chain_key)
P
Peter Zijlstra 已提交
2275 2276 2277
{
	return 1;
}
2278
#endif
I
Ingo Molnar 已提交
2279 2280 2281 2282 2283

/*
 * We are building curr_chain_key incrementally, so double-check
 * it from scratch, to make sure that it's done correctly:
 */
2284
static void check_chain_key(struct task_struct *curr)
I
Ingo Molnar 已提交
2285 2286 2287
{
#ifdef CONFIG_DEBUG_LOCKDEP
	struct held_lock *hlock, *prev_hlock = NULL;
2288
	unsigned int i;
I
Ingo Molnar 已提交
2289 2290 2291 2292 2293 2294
	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();
P
Peter Zijlstra 已提交
2295 2296 2297 2298
			/*
			 * We got mighty confused, our chain keys don't match
			 * with what we expect, someone trample on our task state?
			 */
2299
			WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
I
Ingo Molnar 已提交
2300 2301 2302 2303 2304
				curr->lockdep_depth, i,
				(unsigned long long)chain_key,
				(unsigned long long)hlock->prev_chain_key);
			return;
		}
P
Peter Zijlstra 已提交
2305 2306 2307
		/*
		 * Whoops ran out of static storage again?
		 */
2308
		if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
2309 2310
			return;

I
Ingo Molnar 已提交
2311 2312 2313
		if (prev_hlock && (prev_hlock->irq_context !=
							hlock->irq_context))
			chain_key = 0;
2314
		chain_key = iterate_chain_key(chain_key, hlock->class_idx);
I
Ingo Molnar 已提交
2315 2316 2317 2318
		prev_hlock = hlock;
	}
	if (chain_key != curr->curr_chain_key) {
		debug_locks_off();
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2319 2320 2321 2322
		/*
		 * More smoking hash instead of calculating it, damn see these
		 * numbers float.. I bet that a pink elephant stepped on my memory.
		 */
2323
		WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
I
Ingo Molnar 已提交
2324 2325 2326 2327 2328 2329 2330
			curr->lockdep_depth, i,
			(unsigned long long)chain_key,
			(unsigned long long)curr->curr_chain_key);
	}
#endif
}

2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348
static void
print_usage_bug_scenario(struct held_lock *lock)
{
	struct lock_class *class = hlock_class(lock);

	printk(" Possible unsafe locking scenario:\n\n");
	printk("       CPU0\n");
	printk("       ----\n");
	printk("  lock(");
	__print_lock_name(class);
	printk(");\n");
	printk("  <Interrupt>\n");
	printk("    lock(");
	__print_lock_name(class);
	printk(");\n");
	printk("\n *** DEADLOCK ***\n\n");
}

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2349 2350 2351 2352 2353 2354 2355
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;

2356 2357 2358
	printk("\n");
	printk("=================================\n");
	printk("[ INFO: inconsistent lock state ]\n");
2359
	print_kernel_ident();
2360
	printk("---------------------------------\n");
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Peter Zijlstra 已提交
2361 2362 2363 2364 2365

	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",
2366
		curr->comm, task_pid_nr(curr),
P
Peter Zijlstra 已提交
2367 2368 2369 2370 2371 2372 2373
		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
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2374
	print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
P
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2375 2376 2377

	print_irqtrace_events(curr);
	printk("\nother info that might help us debug this:\n");
2378 2379
	print_usage_bug_scenario(this);

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2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394
	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
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2395
	if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
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2396 2397 2398 2399 2400 2401 2402
		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);

2403
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
I
Ingo Molnar 已提交
2404 2405 2406 2407 2408

/*
 * print irq inversion bug:
 */
static int
2409 2410
print_irq_inversion_bug(struct task_struct *curr,
			struct lock_list *root, struct lock_list *other,
I
Ingo Molnar 已提交
2411 2412 2413
			struct held_lock *this, int forwards,
			const char *irqclass)
{
2414 2415 2416 2417
	struct lock_list *entry = other;
	struct lock_list *middle = NULL;
	int depth;

2418
	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
I
Ingo Molnar 已提交
2419 2420
		return 0;

2421 2422 2423
	printk("\n");
	printk("=========================================================\n");
	printk("[ INFO: possible irq lock inversion dependency detected ]\n");
2424
	print_kernel_ident();
2425
	printk("---------------------------------------------------------\n");
I
Ingo Molnar 已提交
2426
	printk("%s/%d just changed the state of lock:\n",
2427
		curr->comm, task_pid_nr(curr));
I
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2428 2429
	print_lock(this);
	if (forwards)
2430
		printk("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
I
Ingo Molnar 已提交
2431
	else
2432
		printk("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
2433
	print_lock_name(other->class);
I
Ingo Molnar 已提交
2434 2435 2436
	printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");

	printk("\nother info that might help us debug this:\n");
2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455

	/* Find a middle lock (if one exists) */
	depth = get_lock_depth(other);
	do {
		if (depth == 0 && (entry != root)) {
			printk("lockdep:%s bad path found in chain graph\n", __func__);
			break;
		}
		middle = entry;
		entry = get_lock_parent(entry);
		depth--;
	} while (entry && entry != root && (depth >= 0));
	if (forwards)
		print_irq_lock_scenario(root, other,
			middle ? middle->class : root->class, other->class);
	else
		print_irq_lock_scenario(other, root,
			middle ? middle->class : other->class, root->class);

I
Ingo Molnar 已提交
2456 2457
	lockdep_print_held_locks(curr);

2458 2459 2460 2461
	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
2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477

	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;
2478 2479
	struct lock_list root;
	struct lock_list *uninitialized_var(target_entry);
I
Ingo Molnar 已提交
2480

2481 2482 2483
	root.parent = NULL;
	root.class = hlock_class(this);
	ret = find_usage_forwards(&root, bit, &target_entry);
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2484 2485 2486 2487
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
I
Ingo Molnar 已提交
2488

2489
	return print_irq_inversion_bug(curr, &root, target_entry,
2490
					this, 1, irqclass);
I
Ingo Molnar 已提交
2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501
}

/*
 * 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;
2502 2503
	struct lock_list root;
	struct lock_list *uninitialized_var(target_entry);
I
Ingo Molnar 已提交
2504

2505 2506 2507
	root.parent = NULL;
	root.class = hlock_class(this);
	ret = find_usage_backwards(&root, bit, &target_entry);
P
Peter Zijlstra 已提交
2508 2509 2510 2511
	if (ret < 0)
		return print_bfs_bug(ret);
	if (ret == 1)
		return ret;
I
Ingo Molnar 已提交
2512

2513
	return print_irq_inversion_bug(curr, &root, target_entry,
2514
					this, 0, irqclass);
I
Ingo Molnar 已提交
2515 2516
}

2517
void print_irqtrace_events(struct task_struct *curr)
I
Ingo Molnar 已提交
2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529
{
	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);
}

2530
static int HARDIRQ_verbose(struct lock_class *class)
I
Ingo Molnar 已提交
2531
{
P
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2532 2533 2534
#if HARDIRQ_VERBOSE
	return class_filter(class);
#endif
I
Ingo Molnar 已提交
2535 2536 2537
	return 0;
}

2538
static int SOFTIRQ_verbose(struct lock_class *class)
I
Ingo Molnar 已提交
2539
{
P
Peter Zijlstra 已提交
2540 2541 2542 2543
#if SOFTIRQ_VERBOSE
	return class_filter(class);
#endif
	return 0;
I
Ingo Molnar 已提交
2544 2545
}

2546
static int RECLAIM_FS_verbose(struct lock_class *class)
2547 2548 2549 2550 2551 2552 2553
{
#if RECLAIM_VERBOSE
	return class_filter(class);
#endif
	return 0;
}

I
Ingo Molnar 已提交
2554 2555
#define STRICT_READ_CHECKS	1

2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568
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);
}

2569 2570 2571
typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
			     enum lock_usage_bit bit, const char *name);

2572
static int
2573 2574
mark_lock_irq(struct task_struct *curr, struct held_lock *this,
		enum lock_usage_bit new_bit)
2575
{
2576
	int excl_bit = exclusive_bit(new_bit);
2577
	int read = new_bit & 1;
2578 2579
	int dir = new_bit & 2;

2580 2581 2582 2583 2584 2585 2586
	/*
	 * 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.
	 */
2587 2588
	check_usage_f usage = dir ?
		check_usage_backwards : check_usage_forwards;
2589

2590 2591 2592 2593
	/*
	 * Validate that this particular lock does not have conflicting
	 * usage states.
	 */
2594 2595
	if (!valid_state(curr, this, new_bit, excl_bit))
		return 0;
2596

2597 2598 2599 2600 2601
	/*
	 * Validate that the lock dependencies don't have conflicting usage
	 * states.
	 */
	if ((!read || !dir || STRICT_READ_CHECKS) &&
2602
			!usage(curr, this, excl_bit, state_name(new_bit & ~1)))
2603
		return 0;
2604

2605 2606 2607 2608 2609 2610 2611 2612
	/*
	 * Check for read in write conflicts
	 */
	if (!read) {
		if (!valid_state(curr, this, new_bit, excl_bit + 1))
			return 0;

		if (STRICT_READ_CHECKS &&
2613 2614
			!usage(curr, this, excl_bit + 1,
				state_name(new_bit + 1)))
2615 2616
			return 0;
	}
2617

2618
	if (state_verbose(new_bit, hlock_class(this)))
2619 2620 2621 2622 2623
		return 2;

	return 1;
}

2624
enum mark_type {
2625 2626 2627
#define LOCKDEP_STATE(__STATE)	__STATE,
#include "lockdep_states.h"
#undef LOCKDEP_STATE
2628 2629
};

I
Ingo Molnar 已提交
2630 2631 2632
/*
 * Mark all held locks with a usage bit:
 */
2633
static int
2634
mark_held_locks(struct task_struct *curr, enum mark_type mark)
I
Ingo Molnar 已提交
2635 2636 2637 2638 2639 2640 2641 2642
{
	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;

2643 2644 2645 2646 2647
		usage_bit = 2 + (mark << 2); /* ENABLED */
		if (hlock->read)
			usage_bit += 1; /* READ */

		BUG_ON(usage_bit >= LOCK_USAGE_STATES);
2648

2649
		if (!hlock->check)
2650 2651
			continue;

2652
		if (!mark_lock(curr, hlock, usage_bit))
I
Ingo Molnar 已提交
2653 2654 2655 2656 2657 2658 2659 2660 2661
			return 0;
	}

	return 1;
}

/*
 * Hardirqs will be enabled:
 */
2662
static void __trace_hardirqs_on_caller(unsigned long ip)
I
Ingo Molnar 已提交
2663 2664 2665 2666 2667 2668 2669 2670 2671 2672
{
	struct task_struct *curr = current;

	/* we'll do an OFF -> ON transition: */
	curr->hardirqs_enabled = 1;

	/*
	 * We are going to turn hardirqs on, so set the
	 * usage bit for all held locks:
	 */
2673
	if (!mark_held_locks(curr, HARDIRQ))
I
Ingo Molnar 已提交
2674 2675 2676 2677 2678 2679 2680
		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)
2681
		if (!mark_held_locks(curr, SOFTIRQ))
I
Ingo Molnar 已提交
2682 2683
			return;

P
Peter Zijlstra 已提交
2684 2685
	curr->hardirq_enable_ip = ip;
	curr->hardirq_enable_event = ++curr->irq_events;
2686
	debug_atomic_inc(hardirqs_on_events);
P
Peter Zijlstra 已提交
2687
}
2688

2689
__visible void trace_hardirqs_on_caller(unsigned long ip)
2690 2691 2692 2693 2694 2695
{
	time_hardirqs_on(CALLER_ADDR0, ip);

	if (unlikely(!debug_locks || current->lockdep_recursion))
		return;

2696 2697 2698 2699 2700 2701 2702 2703 2704 2705
	if (unlikely(current->hardirqs_enabled)) {
		/*
		 * Neither irq nor preemption are disabled here
		 * so this is racy by nature but losing one hit
		 * in a stat is not a big deal.
		 */
		__debug_atomic_inc(redundant_hardirqs_on);
		return;
	}

P
Peter Zijlstra 已提交
2706 2707 2708 2709 2710
	/*
	 * We're enabling irqs and according to our state above irqs weren't
	 * already enabled, yet we find the hardware thinks they are in fact
	 * enabled.. someone messed up their IRQ state tracing.
	 */
2711 2712 2713
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return;

P
Peter Zijlstra 已提交
2714 2715 2716
	/*
	 * See the fine text that goes along with this variable definition.
	 */
2717 2718 2719
	if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
		return;

P
Peter Zijlstra 已提交
2720 2721 2722 2723
	/*
	 * Can't allow enabling interrupts while in an interrupt handler,
	 * that's general bad form and such. Recursion, limited stack etc..
	 */
2724 2725 2726
	if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
		return;

2727 2728 2729 2730
	current->lockdep_recursion = 1;
	__trace_hardirqs_on_caller(ip);
	current->lockdep_recursion = 0;
}
2731
EXPORT_SYMBOL(trace_hardirqs_on_caller);
P
Peter Zijlstra 已提交
2732

2733
void trace_hardirqs_on(void)
2734 2735 2736
{
	trace_hardirqs_on_caller(CALLER_ADDR0);
}
P
Peter Zijlstra 已提交
2737 2738 2739 2740 2741
EXPORT_SYMBOL(trace_hardirqs_on);

/*
 * Hardirqs were disabled:
 */
2742
__visible void trace_hardirqs_off_caller(unsigned long ip)
P
Peter Zijlstra 已提交
2743 2744 2745
{
	struct task_struct *curr = current;

2746
	time_hardirqs_off(CALLER_ADDR0, ip);
2747

P
Peter Zijlstra 已提交
2748 2749 2750
	if (unlikely(!debug_locks || current->lockdep_recursion))
		return;

P
Peter Zijlstra 已提交
2751 2752 2753 2754
	/*
	 * So we're supposed to get called after you mask local IRQs, but for
	 * some reason the hardware doesn't quite think you did a proper job.
	 */
P
Peter Zijlstra 已提交
2755 2756 2757 2758 2759 2760 2761 2762
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return;

	if (curr->hardirqs_enabled) {
		/*
		 * We have done an ON -> OFF transition:
		 */
		curr->hardirqs_enabled = 0;
2763
		curr->hardirq_disable_ip = ip;
P
Peter Zijlstra 已提交
2764
		curr->hardirq_disable_event = ++curr->irq_events;
2765
		debug_atomic_inc(hardirqs_off_events);
P
Peter Zijlstra 已提交
2766
	} else
2767
		debug_atomic_inc(redundant_hardirqs_off);
P
Peter Zijlstra 已提交
2768
}
2769
EXPORT_SYMBOL(trace_hardirqs_off_caller);
P
Peter Zijlstra 已提交
2770

2771
void trace_hardirqs_off(void)
2772 2773 2774
{
	trace_hardirqs_off_caller(CALLER_ADDR0);
}
P
Peter Zijlstra 已提交
2775 2776 2777 2778 2779 2780 2781 2782 2783
EXPORT_SYMBOL(trace_hardirqs_off);

/*
 * Softirqs will be enabled:
 */
void trace_softirqs_on(unsigned long ip)
{
	struct task_struct *curr = current;

2784
	if (unlikely(!debug_locks || current->lockdep_recursion))
P
Peter Zijlstra 已提交
2785 2786
		return;

P
Peter Zijlstra 已提交
2787 2788 2789 2790
	/*
	 * We fancy IRQs being disabled here, see softirq.c, avoids
	 * funny state and nesting things.
	 */
P
Peter Zijlstra 已提交
2791 2792 2793 2794
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return;

	if (curr->softirqs_enabled) {
2795
		debug_atomic_inc(redundant_softirqs_on);
P
Peter Zijlstra 已提交
2796 2797 2798
		return;
	}

2799
	current->lockdep_recursion = 1;
P
Peter Zijlstra 已提交
2800 2801 2802 2803 2804 2805
	/*
	 * We'll do an OFF -> ON transition:
	 */
	curr->softirqs_enabled = 1;
	curr->softirq_enable_ip = ip;
	curr->softirq_enable_event = ++curr->irq_events;
2806
	debug_atomic_inc(softirqs_on_events);
P
Peter Zijlstra 已提交
2807 2808 2809 2810 2811 2812
	/*
	 * 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)
2813
		mark_held_locks(curr, SOFTIRQ);
2814
	current->lockdep_recursion = 0;
P
Peter Zijlstra 已提交
2815 2816 2817 2818 2819 2820 2821 2822 2823
}

/*
 * Softirqs were disabled:
 */
void trace_softirqs_off(unsigned long ip)
{
	struct task_struct *curr = current;

2824
	if (unlikely(!debug_locks || current->lockdep_recursion))
P
Peter Zijlstra 已提交
2825 2826
		return;

P
Peter Zijlstra 已提交
2827 2828 2829
	/*
	 * We fancy IRQs being disabled here, see softirq.c
	 */
P
Peter Zijlstra 已提交
2830 2831 2832 2833 2834 2835 2836 2837 2838 2839
	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;
2840
		debug_atomic_inc(softirqs_off_events);
P
Peter Zijlstra 已提交
2841 2842 2843
		/*
		 * Whoops, we wanted softirqs off, so why aren't they?
		 */
P
Peter Zijlstra 已提交
2844 2845
		DEBUG_LOCKS_WARN_ON(!softirq_count());
	} else
2846
		debug_atomic_inc(redundant_softirqs_off);
P
Peter Zijlstra 已提交
2847 2848
}

2849
static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
2850 2851 2852 2853 2854 2855 2856
{
	struct task_struct *curr = current;

	if (unlikely(!debug_locks))
		return;

	/* no reclaim without waiting on it */
2857
	if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
2858 2859 2860 2861 2862 2863 2864 2865 2866 2867
		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;

P
Peter Zijlstra 已提交
2868 2869 2870
	/*
	 * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
	 */
2871
	if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
2872 2873 2874 2875 2876
		return;

	mark_held_locks(curr, RECLAIM_FS);
}

2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893
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);
}

P
Peter Zijlstra 已提交
2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920 2921
static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
{
	/*
	 * If non-trylock use in a hardirq or softirq context, then
	 * mark the lock as used in these contexts:
	 */
	if (!hlock->trylock) {
		if (hlock->read) {
			if (curr->hardirq_context)
				if (!mark_lock(curr, hlock,
						LOCK_USED_IN_HARDIRQ_READ))
					return 0;
			if (curr->softirq_context)
				if (!mark_lock(curr, hlock,
						LOCK_USED_IN_SOFTIRQ_READ))
					return 0;
		} else {
			if (curr->hardirq_context)
				if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
					return 0;
			if (curr->softirq_context)
				if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
					return 0;
		}
	}
	if (!hlock->hardirqs_off) {
		if (hlock->read) {
			if (!mark_lock(curr, hlock,
P
Peter Zijlstra 已提交
2922
					LOCK_ENABLED_HARDIRQ_READ))
P
Peter Zijlstra 已提交
2923 2924 2925
				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
P
Peter Zijlstra 已提交
2926
						LOCK_ENABLED_SOFTIRQ_READ))
P
Peter Zijlstra 已提交
2927 2928 2929
					return 0;
		} else {
			if (!mark_lock(curr, hlock,
P
Peter Zijlstra 已提交
2930
					LOCK_ENABLED_HARDIRQ))
P
Peter Zijlstra 已提交
2931 2932 2933
				return 0;
			if (curr->softirqs_enabled)
				if (!mark_lock(curr, hlock,
P
Peter Zijlstra 已提交
2934
						LOCK_ENABLED_SOFTIRQ))
P
Peter Zijlstra 已提交
2935 2936 2937 2938
					return 0;
		}
	}

2939 2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954
	/*
	 * 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;
		}
	}

P
Peter Zijlstra 已提交
2955 2956 2957
	return 1;
}

2958 2959 2960 2961 2962
static inline unsigned int task_irq_context(struct task_struct *task)
{
	return 2 * !!task->hardirq_context + !!task->softirq_context;
}

P
Peter Zijlstra 已提交
2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980 2981 2982 2983
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:
	 */
	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;
I
Ingo Molnar 已提交
2984 2985
}

P
Peter Zijlstra 已提交
2986
#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
I
Ingo Molnar 已提交
2987

P
Peter Zijlstra 已提交
2988 2989 2990
static inline
int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
		enum lock_usage_bit new_bit)
I
Ingo Molnar 已提交
2991
{
P
Peter Zijlstra 已提交
2992
	WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
P
Peter Zijlstra 已提交
2993 2994
	return 1;
}
I
Ingo Molnar 已提交
2995

P
Peter Zijlstra 已提交
2996 2997 2998 2999 3000
static inline int mark_irqflags(struct task_struct *curr,
		struct held_lock *hlock)
{
	return 1;
}
I
Ingo Molnar 已提交
3001

3002 3003 3004 3005 3006
static inline unsigned int task_irq_context(struct task_struct *task)
{
	return 0;
}

P
Peter Zijlstra 已提交
3007 3008 3009 3010
static inline int separate_irq_context(struct task_struct *curr,
		struct held_lock *hlock)
{
	return 0;
I
Ingo Molnar 已提交
3011 3012
}

3013 3014 3015 3016
void lockdep_trace_alloc(gfp_t gfp_mask)
{
}

P
Peter Zijlstra 已提交
3017
#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
I
Ingo Molnar 已提交
3018 3019

/*
P
Peter Zijlstra 已提交
3020
 * Mark a lock with a usage bit, and validate the state transition:
I
Ingo Molnar 已提交
3021
 */
3022
static int mark_lock(struct task_struct *curr, struct held_lock *this,
3023
			     enum lock_usage_bit new_bit)
I
Ingo Molnar 已提交
3024
{
P
Peter Zijlstra 已提交
3025
	unsigned int new_mask = 1 << new_bit, ret = 1;
I
Ingo Molnar 已提交
3026 3027

	/*
P
Peter Zijlstra 已提交
3028 3029
	 * If already set then do not dirty the cacheline,
	 * nor do any checks:
I
Ingo Molnar 已提交
3030
	 */
D
Dave Jones 已提交
3031
	if (likely(hlock_class(this)->usage_mask & new_mask))
P
Peter Zijlstra 已提交
3032 3033 3034 3035
		return 1;

	if (!graph_lock())
		return 0;
I
Ingo Molnar 已提交
3036
	/*
L
Lucas De Marchi 已提交
3037
	 * Make sure we didn't race:
I
Ingo Molnar 已提交
3038
	 */
D
Dave Jones 已提交
3039
	if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
P
Peter Zijlstra 已提交
3040 3041 3042
		graph_unlock();
		return 1;
	}
I
Ingo Molnar 已提交
3043

D
Dave Jones 已提交
3044
	hlock_class(this)->usage_mask |= new_mask;
I
Ingo Molnar 已提交
3045

D
Dave Jones 已提交
3046
	if (!save_trace(hlock_class(this)->usage_traces + new_bit))
P
Peter Zijlstra 已提交
3047
		return 0;
I
Ingo Molnar 已提交
3048

P
Peter Zijlstra 已提交
3049
	switch (new_bit) {
P
Peter Zijlstra 已提交
3050 3051 3052 3053 3054 3055 3056
#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
P
Peter Zijlstra 已提交
3057 3058 3059 3060 3061
		ret = mark_lock_irq(curr, this, new_bit);
		if (!ret)
			return 0;
		break;
	case LOCK_USED:
3062
		debug_atomic_dec(nr_unused_locks);
P
Peter Zijlstra 已提交
3063 3064 3065 3066 3067 3068 3069
		break;
	default:
		if (!debug_locks_off_graph_unlock())
			return 0;
		WARN_ON(1);
		return 0;
	}
I
Ingo Molnar 已提交
3070

P
Peter Zijlstra 已提交
3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081 3082 3083 3084
	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;
}
I
Ingo Molnar 已提交
3085 3086 3087 3088 3089

/*
 * Initialize a lock instance's lock-class mapping info:
 */
void lockdep_init_map(struct lockdep_map *lock, const char *name,
3090
		      struct lock_class_key *key, int subclass)
I
Ingo Molnar 已提交
3091
{
3092 3093 3094 3095 3096 3097
	int i;

	kmemcheck_mark_initialized(lock, sizeof(*lock));

	for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
		lock->class_cache[i] = NULL;
3098

3099 3100 3101 3102
#ifdef CONFIG_LOCK_STAT
	lock->cpu = raw_smp_processor_id();
#endif

P
Peter Zijlstra 已提交
3103 3104 3105
	/*
	 * Can't be having no nameless bastards around this place!
	 */
3106 3107
	if (DEBUG_LOCKS_WARN_ON(!name)) {
		lock->name = "NULL";
I
Ingo Molnar 已提交
3108
		return;
3109 3110 3111
	}

	lock->name = name;
I
Ingo Molnar 已提交
3112

P
Peter Zijlstra 已提交
3113 3114 3115
	/*
	 * No key, no joy, we need to hash something.
	 */
I
Ingo Molnar 已提交
3116 3117 3118 3119 3120 3121 3122
	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);
P
Peter Zijlstra 已提交
3123 3124 3125
		/*
		 * What it says above ^^^^^, I suggest you read it.
		 */
I
Ingo Molnar 已提交
3126 3127 3128 3129
		DEBUG_LOCKS_WARN_ON(1);
		return;
	}
	lock->key = key;
3130 3131 3132 3133

	if (unlikely(!debug_locks))
		return;

3134 3135 3136 3137 3138 3139 3140 3141
	if (subclass) {
		unsigned long flags;

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

		raw_local_irq_save(flags);
		current->lockdep_recursion = 1;
3142
		register_lock_class(lock, subclass, 1);
3143 3144 3145
		current->lockdep_recursion = 0;
		raw_local_irq_restore(flags);
	}
I
Ingo Molnar 已提交
3146 3147 3148
}
EXPORT_SYMBOL_GPL(lockdep_init_map);

3149
struct lock_class_key __lockdep_no_validate__;
K
Kent Overstreet 已提交
3150
EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
3151

3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187
static int
print_lock_nested_lock_not_held(struct task_struct *curr,
				struct held_lock *hlock,
				unsigned long ip)
{
	if (!debug_locks_off())
		return 0;
	if (debug_locks_silent)
		return 0;

	printk("\n");
	printk("==================================\n");
	printk("[ BUG: Nested lock was not taken ]\n");
	print_kernel_ident();
	printk("----------------------------------\n");

	printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
	print_lock(hlock);

	printk("\nbut this task is not holding:\n");
	printk("%s\n", hlock->nest_lock->name);

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

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

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

	return 0;
}

static int __lock_is_held(struct lockdep_map *lock);

I
Ingo Molnar 已提交
3188 3189 3190 3191 3192 3193
/*
 * 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,
3194
			  struct lockdep_map *nest_lock, unsigned long ip,
3195
			  int references, int pin_count)
I
Ingo Molnar 已提交
3196 3197
{
	struct task_struct *curr = current;
3198
	struct lock_class *class = NULL;
I
Ingo Molnar 已提交
3199
	struct held_lock *hlock;
3200
	unsigned int depth;
I
Ingo Molnar 已提交
3201
	int chain_head = 0;
3202
	int class_idx;
I
Ingo Molnar 已提交
3203 3204 3205 3206 3207
	u64 chain_key;

	if (unlikely(!debug_locks))
		return 0;

P
Peter Zijlstra 已提交
3208 3209 3210 3211 3212
	/*
	 * Lockdep should run with IRQs disabled, otherwise we could
	 * get an interrupt which would want to take locks, which would
	 * end up in lockdep and have you got a head-ache already?
	 */
I
Ingo Molnar 已提交
3213 3214 3215
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return 0;

3216 3217
	if (!prove_locking || lock->key == &__lockdep_no_validate__)
		check = 0;
3218

3219 3220
	if (subclass < NR_LOCKDEP_CACHING_CLASSES)
		class = lock->class_cache[subclass];
3221
	/*
3222
	 * Not cached?
3223
	 */
I
Ingo Molnar 已提交
3224
	if (unlikely(!class)) {
3225
		class = register_lock_class(lock, subclass, 0);
I
Ingo Molnar 已提交
3226 3227 3228
		if (!class)
			return 0;
	}
3229
	atomic_inc((atomic_t *)&class->ops);
I
Ingo Molnar 已提交
3230 3231 3232 3233 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243
	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;
P
Peter Zijlstra 已提交
3244 3245 3246
	/*
	 * Ran out of static storage for our per-task lock stack again have we?
	 */
I
Ingo Molnar 已提交
3247 3248 3249
	if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
		return 0;

3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261 3262 3263
	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;
		}
	}

I
Ingo Molnar 已提交
3264
	hlock = curr->held_locks + depth;
P
Peter Zijlstra 已提交
3265 3266 3267 3268
	/*
	 * Plain impossible, we just registered it and checked it weren't no
	 * NULL like.. I bet this mushroom I ate was good!
	 */
D
Dave Jones 已提交
3269 3270
	if (DEBUG_LOCKS_WARN_ON(!class))
		return 0;
3271
	hlock->class_idx = class_idx;
I
Ingo Molnar 已提交
3272 3273
	hlock->acquire_ip = ip;
	hlock->instance = lock;
P
Peter Zijlstra 已提交
3274
	hlock->nest_lock = nest_lock;
3275
	hlock->irq_context = task_irq_context(curr);
I
Ingo Molnar 已提交
3276 3277 3278
	hlock->trylock = trylock;
	hlock->read = read;
	hlock->check = check;
3279
	hlock->hardirqs_off = !!hardirqs_off;
3280
	hlock->references = references;
P
Peter Zijlstra 已提交
3281 3282
#ifdef CONFIG_LOCK_STAT
	hlock->waittime_stamp = 0;
3283
	hlock->holdtime_stamp = lockstat_clock();
P
Peter Zijlstra 已提交
3284
#endif
3285
	hlock->pin_count = pin_count;
I
Ingo Molnar 已提交
3286

3287
	if (check && !mark_irqflags(curr, hlock))
P
Peter Zijlstra 已提交
3288 3289
		return 0;

I
Ingo Molnar 已提交
3290
	/* mark it as used: */
3291
	if (!mark_lock(curr, hlock, LOCK_USED))
I
Ingo Molnar 已提交
3292
		return 0;
P
Peter Zijlstra 已提交
3293

I
Ingo Molnar 已提交
3294
	/*
3295
	 * Calculate the chain hash: it's the combined hash of all the
I
Ingo Molnar 已提交
3296 3297 3298 3299 3300 3301 3302 3303
	 * 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.
	 */
P
Peter Zijlstra 已提交
3304 3305 3306
	/*
	 * Whoops, we did it again.. ran straight out of our static allocation.
	 */
3307
	if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
I
Ingo Molnar 已提交
3308 3309 3310 3311
		return 0;

	chain_key = curr->curr_chain_key;
	if (!depth) {
P
Peter Zijlstra 已提交
3312 3313 3314
		/*
		 * How can we have a chain hash when we ain't got no keys?!
		 */
I
Ingo Molnar 已提交
3315 3316 3317 3318 3319 3320
		if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
			return 0;
		chain_head = 1;
	}

	hlock->prev_chain_key = chain_key;
P
Peter Zijlstra 已提交
3321 3322 3323
	if (separate_irq_context(curr, hlock)) {
		chain_key = 0;
		chain_head = 1;
I
Ingo Molnar 已提交
3324
	}
3325
	chain_key = iterate_chain_key(chain_key, class_idx);
I
Ingo Molnar 已提交
3326

3327 3328 3329
	if (nest_lock && !__lock_is_held(nest_lock))
		return print_lock_nested_lock_not_held(curr, hlock, ip);

3330
	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
P
Peter Zijlstra 已提交
3331
		return 0;
3332

3333
	curr->curr_chain_key = chain_key;
I
Ingo Molnar 已提交
3334 3335
	curr->lockdep_depth++;
	check_chain_key(curr);
3336 3337 3338 3339
#ifdef CONFIG_DEBUG_LOCKDEP
	if (unlikely(!debug_locks))
		return 0;
#endif
I
Ingo Molnar 已提交
3340 3341
	if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
		debug_locks_off();
3342 3343
		print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
		printk(KERN_DEBUG "depth: %i  max: %lu!\n",
3344 3345 3346 3347
		       curr->lockdep_depth, MAX_LOCK_DEPTH);

		lockdep_print_held_locks(current);
		debug_show_all_locks();
3348
		dump_stack();
3349

I
Ingo Molnar 已提交
3350 3351
		return 0;
	}
3352

I
Ingo Molnar 已提交
3353 3354 3355 3356 3357 3358 3359
	if (unlikely(curr->lockdep_depth > max_lockdep_depth))
		max_lockdep_depth = curr->lockdep_depth;

	return 1;
}

static int
3360
print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
I
Ingo Molnar 已提交
3361 3362 3363 3364 3365 3366 3367
			   unsigned long ip)
{
	if (!debug_locks_off())
		return 0;
	if (debug_locks_silent)
		return 0;

3368 3369 3370
	printk("\n");
	printk("=====================================\n");
	printk("[ BUG: bad unlock balance detected! ]\n");
3371
	print_kernel_ident();
3372
	printk("-------------------------------------\n");
I
Ingo Molnar 已提交
3373
	printk("%s/%d is trying to release lock (",
3374
		curr->comm, task_pid_nr(curr));
I
Ingo Molnar 已提交
3375 3376 3377 3378 3379 3380 3381 3382 3383 3384 3385 3386 3387
	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;
}

3388 3389 3390 3391 3392 3393
static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
{
	if (hlock->instance == lock)
		return 1;

	if (hlock->references) {
3394
		struct lock_class *class = lock->class_cache[0];
3395 3396 3397 3398

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

3399 3400 3401 3402 3403 3404 3405
		/*
		 * If look_up_lock_class() failed to find a class, we're trying
		 * to test if we hold a lock that has never yet been acquired.
		 * Clearly if the lock hasn't been acquired _ever_, we're not
		 * holding it either, so report failure.
		 */
		if (!class)
3406 3407
			return 0;

P
Peter Zijlstra 已提交
3408 3409 3410 3411 3412
		/*
		 * References, but not a lock we're actually ref-counting?
		 * State got messed up, follow the sites that change ->references
		 * and try to make sense of it.
		 */
3413 3414 3415 3416 3417 3418 3419 3420 3421 3422
		if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
			return 0;

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

	return 0;
}

3423
static int
3424 3425 3426
__lock_set_class(struct lockdep_map *lock, const char *name,
		 struct lock_class_key *key, unsigned int subclass,
		 unsigned long ip)
3427 3428 3429 3430 3431 3432 3433 3434
{
	struct task_struct *curr = current;
	struct held_lock *hlock, *prev_hlock;
	struct lock_class *class;
	unsigned int depth;
	int i;

	depth = curr->lockdep_depth;
P
Peter Zijlstra 已提交
3435 3436 3437 3438
	/*
	 * This function is about (re)setting the class of a held lock,
	 * yet we're not actually holding any locks. Naughty user!
	 */
3439 3440 3441 3442 3443 3444 3445 3446 3447 3448 3449
	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;
3450
		if (match_held_lock(hlock, lock))
3451 3452 3453
			goto found_it;
		prev_hlock = hlock;
	}
3454
	return print_unlock_imbalance_bug(curr, lock, ip);
3455 3456

found_it:
3457
	lockdep_init_map(lock, name, key, 0);
3458
	class = register_lock_class(lock, subclass, 0);
D
Dave Jones 已提交
3459
	hlock->class_idx = class - lock_classes + 1;
3460 3461 3462 3463 3464 3465 3466

	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
3467
			hlock_class(hlock)->subclass, hlock->trylock,
3468
				hlock->read, hlock->check, hlock->hardirqs_off,
3469
				hlock->nest_lock, hlock->acquire_ip,
3470
				hlock->references, hlock->pin_count))
3471 3472 3473
			return 0;
	}

P
Peter Zijlstra 已提交
3474 3475 3476 3477
	/*
	 * I took it apart and put it back together again, except now I have
	 * these 'spare' parts.. where shall I put them.
	 */
3478 3479 3480 3481 3482
	if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
		return 0;
	return 1;
}

I
Ingo Molnar 已提交
3483
/*
3484 3485 3486 3487 3488
 * 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()).
 *
 * @nested is an hysterical artifact, needs a tree wide cleanup.
I
Ingo Molnar 已提交
3489 3490
 */
static int
3491
__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
I
Ingo Molnar 已提交
3492
{
3493
	struct task_struct *curr = current;
I
Ingo Molnar 已提交
3494 3495 3496 3497
	struct held_lock *hlock, *prev_hlock;
	unsigned int depth;
	int i;

3498 3499 3500
	if (unlikely(!debug_locks))
		return 0;

I
Ingo Molnar 已提交
3501
	depth = curr->lockdep_depth;
P
Peter Zijlstra 已提交
3502 3503 3504 3505
	/*
	 * So we're all set to release this lock.. wait what lock? We don't
	 * own any locks, you've been drinking again?
	 */
3506 3507
	if (DEBUG_LOCKS_WARN_ON(depth <= 0))
		 return print_unlock_imbalance_bug(curr, lock, ip);
I
Ingo Molnar 已提交
3508

3509 3510 3511 3512
	/*
	 * Check whether the lock exists in the current stack
	 * of held locks:
	 */
I
Ingo Molnar 已提交
3513 3514 3515 3516 3517 3518 3519 3520
	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;
3521
		if (match_held_lock(hlock, lock))
I
Ingo Molnar 已提交
3522 3523 3524
			goto found_it;
		prev_hlock = hlock;
	}
3525
	return print_unlock_imbalance_bug(curr, lock, ip);
I
Ingo Molnar 已提交
3526 3527

found_it:
3528 3529 3530
	if (hlock->instance == lock)
		lock_release_holdtime(hlock);

P
Peter Zijlstra 已提交
3531 3532
	WARN(hlock->pin_count, "releasing a pinned lock\n");

3533 3534 3535 3536 3537 3538 3539 3540 3541 3542 3543
	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
3544

I
Ingo Molnar 已提交
3545 3546 3547 3548 3549
	/*
	 * 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:
	 */
3550

I
Ingo Molnar 已提交
3551 3552 3553 3554 3555 3556
	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
3557
			hlock_class(hlock)->subclass, hlock->trylock,
I
Ingo Molnar 已提交
3558
				hlock->read, hlock->check, hlock->hardirqs_off,
3559
				hlock->nest_lock, hlock->acquire_ip,
3560
				hlock->references, hlock->pin_count))
I
Ingo Molnar 已提交
3561 3562 3563
			return 0;
	}

P
Peter Zijlstra 已提交
3564 3565 3566 3567
	/*
	 * We had N bottles of beer on the wall, we drank one, but now
	 * there's not N-1 bottles of beer left on the wall...
	 */
I
Ingo Molnar 已提交
3568 3569
	if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
		return 0;
P
Peter Zijlstra 已提交
3570

I
Ingo Molnar 已提交
3571 3572 3573
	return 1;
}

3574
static int __lock_is_held(struct lockdep_map *lock)
I
Ingo Molnar 已提交
3575
{
3576 3577
	struct task_struct *curr = current;
	int i;
I
Ingo Molnar 已提交
3578

3579
	for (i = 0; i < curr->lockdep_depth; i++) {
3580
		struct held_lock *hlock = curr->held_locks + i;
I
Ingo Molnar 已提交
3581

3582
		if (match_held_lock(hlock, lock))
3583 3584
			return 1;
	}
P
Peter Zijlstra 已提交
3585

3586
	return 0;
I
Ingo Molnar 已提交
3587 3588
}

3589 3590 3591 3592 3593 3594 3595 3596 3597 3598 3599 3600 3601 3602 3603 3604 3605 3606 3607 3608 3609 3610 3611 3612 3613 3614 3615 3616 3617
static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
{
	struct pin_cookie cookie = NIL_COOKIE;
	struct task_struct *curr = current;
	int i;

	if (unlikely(!debug_locks))
		return cookie;

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

		if (match_held_lock(hlock, lock)) {
			/*
			 * Grab 16bits of randomness; this is sufficient to not
			 * be guessable and still allows some pin nesting in
			 * our u32 pin_count.
			 */
			cookie.val = 1 + (prandom_u32() >> 16);
			hlock->pin_count += cookie.val;
			return cookie;
		}
	}

	WARN(1, "pinning an unheld lock\n");
	return cookie;
}

static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
I
Ingo Molnar 已提交
3618 3619
{
	struct task_struct *curr = current;
P
Peter Zijlstra 已提交
3620
	int i;
I
Ingo Molnar 已提交
3621

P
Peter Zijlstra 已提交
3622
	if (unlikely(!debug_locks))
I
Ingo Molnar 已提交
3623 3624
		return;

P
Peter Zijlstra 已提交
3625 3626 3627 3628
	for (i = 0; i < curr->lockdep_depth; i++) {
		struct held_lock *hlock = curr->held_locks + i;

		if (match_held_lock(hlock, lock)) {
3629
			hlock->pin_count += cookie.val;
I
Ingo Molnar 已提交
3630
			return;
P
Peter Zijlstra 已提交
3631
		}
I
Ingo Molnar 已提交
3632 3633
	}

P
Peter Zijlstra 已提交
3634
	WARN(1, "pinning an unheld lock\n");
I
Ingo Molnar 已提交
3635 3636
}

3637
static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
3638 3639 3640 3641
{
	struct task_struct *curr = current;
	int i;

P
Peter Zijlstra 已提交
3642 3643 3644
	if (unlikely(!debug_locks))
		return;

3645
	for (i = 0; i < curr->lockdep_depth; i++) {
3646 3647
		struct held_lock *hlock = curr->held_locks + i;

P
Peter Zijlstra 已提交
3648 3649 3650 3651
		if (match_held_lock(hlock, lock)) {
			if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
				return;

3652 3653 3654 3655 3656
			hlock->pin_count -= cookie.val;

			if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
				hlock->pin_count = 0;

P
Peter Zijlstra 已提交
3657 3658
			return;
		}
3659 3660
	}

P
Peter Zijlstra 已提交
3661
	WARN(1, "unpinning an unheld lock\n");
3662 3663
}

I
Ingo Molnar 已提交
3664 3665 3666
/*
 * Check whether we follow the irq-flags state precisely:
 */
3667
static void check_flags(unsigned long flags)
I
Ingo Molnar 已提交
3668
{
3669 3670
#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
    defined(CONFIG_TRACE_IRQFLAGS)
I
Ingo Molnar 已提交
3671 3672 3673
	if (!debug_locks)
		return;

3674 3675 3676 3677 3678 3679 3680 3681 3682
	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
3683 3684 3685 3686 3687 3688 3689

	/*
	 * 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()) {
P
Peter Zijlstra 已提交
3690 3691
		if (softirq_count()) {
			/* like the above, but with softirqs */
I
Ingo Molnar 已提交
3692
			DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
P
Peter Zijlstra 已提交
3693 3694
		} else {
			/* lick the above, does it taste good? */
I
Ingo Molnar 已提交
3695
			DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
P
Peter Zijlstra 已提交
3696
		}
I
Ingo Molnar 已提交
3697 3698 3699 3700 3701 3702 3703
	}

	if (!debug_locks)
		print_irqtrace_events(current);
#endif
}

3704 3705 3706
void lock_set_class(struct lockdep_map *lock, const char *name,
		    struct lock_class_key *key, unsigned int subclass,
		    unsigned long ip)
3707 3708 3709 3710 3711 3712 3713 3714 3715
{
	unsigned long flags;

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

	raw_local_irq_save(flags);
	current->lockdep_recursion = 1;
	check_flags(flags);
3716
	if (__lock_set_class(lock, name, key, subclass, ip))
3717 3718 3719 3720
		check_chain_key(current);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
3721
EXPORT_SYMBOL_GPL(lock_set_class);
3722

I
Ingo Molnar 已提交
3723 3724 3725 3726
/*
 * We are not always called with irqs disabled - do that here,
 * and also avoid lockdep recursion:
 */
3727
void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
P
Peter Zijlstra 已提交
3728 3729
			  int trylock, int read, int check,
			  struct lockdep_map *nest_lock, unsigned long ip)
I
Ingo Molnar 已提交
3730 3731 3732 3733 3734 3735 3736 3737 3738 3739
{
	unsigned long flags;

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

	raw_local_irq_save(flags);
	check_flags(flags);

	current->lockdep_recursion = 1;
3740
	trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
I
Ingo Molnar 已提交
3741
	__lock_acquire(lock, subclass, trylock, read, check,
3742
		       irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
I
Ingo Molnar 已提交
3743 3744 3745 3746 3747
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquire);

3748
void lock_release(struct lockdep_map *lock, int nested,
3749
			  unsigned long ip)
I
Ingo Molnar 已提交
3750 3751 3752 3753 3754 3755 3756 3757 3758
{
	unsigned long flags;

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

	raw_local_irq_save(flags);
	check_flags(flags);
	current->lockdep_recursion = 1;
3759
	trace_lock_release(lock, ip);
3760 3761
	if (__lock_release(lock, nested, ip))
		check_chain_key(current);
I
Ingo Molnar 已提交
3762 3763 3764 3765 3766
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_release);

3767 3768 3769 3770 3771 3772
int lock_is_held(struct lockdep_map *lock)
{
	unsigned long flags;
	int ret = 0;

	if (unlikely(current->lockdep_recursion))
3773
		return 1; /* avoid false negative lockdep_assert_held() */
3774 3775 3776 3777 3778 3779 3780 3781 3782 3783 3784 3785 3786

	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);

3787
struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
P
Peter Zijlstra 已提交
3788
{
3789
	struct pin_cookie cookie = NIL_COOKIE;
P
Peter Zijlstra 已提交
3790 3791 3792
	unsigned long flags;

	if (unlikely(current->lockdep_recursion))
3793
		return cookie;
P
Peter Zijlstra 已提交
3794 3795 3796 3797 3798

	raw_local_irq_save(flags);
	check_flags(flags);

	current->lockdep_recursion = 1;
3799
	cookie = __lock_pin_lock(lock);
P
Peter Zijlstra 已提交
3800 3801
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
3802 3803

	return cookie;
P
Peter Zijlstra 已提交
3804 3805 3806
}
EXPORT_SYMBOL_GPL(lock_pin_lock);

3807 3808 3809 3810 3811 3812 3813 3814 3815 3816 3817 3818 3819 3820 3821 3822 3823 3824
void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
{
	unsigned long flags;

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

	raw_local_irq_save(flags);
	check_flags(flags);

	current->lockdep_recursion = 1;
	__lock_repin_lock(lock, cookie);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_repin_lock);

void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
P
Peter Zijlstra 已提交
3825 3826 3827 3828 3829 3830 3831 3832 3833 3834
{
	unsigned long flags;

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

	raw_local_irq_save(flags);
	check_flags(flags);

	current->lockdep_recursion = 1;
3835
	__lock_unpin_lock(lock, cookie);
P
Peter Zijlstra 已提交
3836 3837 3838 3839 3840
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_unpin_lock);

3841 3842 3843 3844 3845 3846 3847 3848 3849 3850
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
3851 3852 3853 3854 3855 3856 3857 3858 3859 3860
#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;

3861 3862 3863
	printk("\n");
	printk("=================================\n");
	printk("[ BUG: bad contention detected! ]\n");
3864
	print_kernel_ident();
3865
	printk("---------------------------------\n");
P
Peter Zijlstra 已提交
3866
	printk("%s/%d is trying to contend lock (",
3867
		curr->comm, task_pid_nr(curr));
P
Peter Zijlstra 已提交
3868 3869 3870 3871 3872 3873 3874 3875 3876 3877 3878 3879 3880 3881 3882 3883 3884 3885 3886 3887
	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
3888
	int i, contention_point, contending_point;
P
Peter Zijlstra 已提交
3889 3890

	depth = curr->lockdep_depth;
P
Peter Zijlstra 已提交
3891 3892 3893 3894
	/*
	 * Whee, we contended on this lock, except it seems we're not
	 * actually trying to acquire anything much at all..
	 */
P
Peter Zijlstra 已提交
3895 3896 3897 3898 3899 3900 3901 3902 3903 3904 3905
	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;
3906
		if (match_held_lock(hlock, lock))
P
Peter Zijlstra 已提交
3907 3908 3909 3910 3911 3912 3913
			goto found_it;
		prev_hlock = hlock;
	}
	print_lock_contention_bug(curr, lock, ip);
	return;

found_it:
3914 3915 3916
	if (hlock->instance != lock)
		return;

3917
	hlock->waittime_stamp = lockstat_clock();
P
Peter Zijlstra 已提交
3918

P
Peter Zijlstra 已提交
3919 3920 3921
	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
3922

D
Dave Jones 已提交
3923
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3924 3925 3926 3927
	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
3928 3929
	if (lock->cpu != smp_processor_id())
		stats->bounces[bounce_contended + !!hlock->read]++;
P
Peter Zijlstra 已提交
3930 3931 3932 3933
	put_lock_stats(stats);
}

static void
P
Peter Zijlstra 已提交
3934
__lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
3935 3936 3937 3938 3939
{
	struct task_struct *curr = current;
	struct held_lock *hlock, *prev_hlock;
	struct lock_class_stats *stats;
	unsigned int depth;
3940
	u64 now, waittime = 0;
P
Peter Zijlstra 已提交
3941
	int i, cpu;
P
Peter Zijlstra 已提交
3942 3943

	depth = curr->lockdep_depth;
P
Peter Zijlstra 已提交
3944 3945 3946 3947
	/*
	 * Yay, we acquired ownership of this lock we didn't try to
	 * acquire, how the heck did that happen?
	 */
P
Peter Zijlstra 已提交
3948 3949 3950 3951 3952 3953 3954 3955 3956 3957 3958
	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;
3959
		if (match_held_lock(hlock, lock))
P
Peter Zijlstra 已提交
3960 3961 3962 3963 3964 3965 3966
			goto found_it;
		prev_hlock = hlock;
	}
	print_lock_contention_bug(curr, lock, _RET_IP_);
	return;

found_it:
3967 3968 3969
	if (hlock->instance != lock)
		return;

P
Peter Zijlstra 已提交
3970 3971
	cpu = smp_processor_id();
	if (hlock->waittime_stamp) {
3972
		now = lockstat_clock();
P
Peter Zijlstra 已提交
3973 3974 3975
		waittime = now - hlock->waittime_stamp;
		hlock->holdtime_stamp = now;
	}
P
Peter Zijlstra 已提交
3976

3977
	trace_lock_acquired(lock, ip);
3978

D
Dave Jones 已提交
3979
	stats = get_lock_stats(hlock_class(hlock));
P
Peter Zijlstra 已提交
3980 3981 3982 3983 3984 3985 3986 3987
	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
3988
	put_lock_stats(stats);
P
Peter Zijlstra 已提交
3989 3990

	lock->cpu = cpu;
P
Peter Zijlstra 已提交
3991
	lock->ip = ip;
P
Peter Zijlstra 已提交
3992 3993 3994 3995 3996 3997 3998 3999 4000 4001 4002 4003 4004 4005 4006
}

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

	if (unlikely(!lock_stat))
		return;

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

	raw_local_irq_save(flags);
	check_flags(flags);
	current->lockdep_recursion = 1;
4007
	trace_lock_contended(lock, ip);
P
Peter Zijlstra 已提交
4008 4009 4010 4011 4012 4013
	__lock_contended(lock, ip);
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_contended);

P
Peter Zijlstra 已提交
4014
void lock_acquired(struct lockdep_map *lock, unsigned long ip)
P
Peter Zijlstra 已提交
4015 4016 4017 4018 4019 4020 4021 4022 4023 4024 4025 4026
{
	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
4027
	__lock_acquired(lock, ip);
P
Peter Zijlstra 已提交
4028 4029 4030 4031 4032 4033
	current->lockdep_recursion = 0;
	raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquired);
#endif

I
Ingo Molnar 已提交
4034 4035 4036 4037 4038 4039 4040 4041
/*
 * Used by the testsuite, sanitize the validator state
 * after a simulated failure:
 */

void lockdep_reset(void)
{
	unsigned long flags;
4042
	int i;
I
Ingo Molnar 已提交
4043 4044 4045 4046 4047 4048 4049 4050 4051 4052

	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;
4053
	for (i = 0; i < CHAINHASH_SIZE; i++)
4054
		INIT_HLIST_HEAD(chainhash_table + i);
I
Ingo Molnar 已提交
4055 4056 4057 4058 4059 4060 4061 4062 4063 4064 4065 4066 4067 4068 4069 4070 4071 4072
	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:
	 */
4073
	hlist_del_rcu(&class->hash_entry);
I
Ingo Molnar 已提交
4074 4075
	list_del_rcu(&class->lock_entry);

4076 4077
	RCU_INIT_POINTER(class->key, NULL);
	RCU_INIT_POINTER(class->name, NULL);
I
Ingo Molnar 已提交
4078 4079
}

4080
static inline int within(const void *addr, void *start, unsigned long size)
I
Ingo Molnar 已提交
4081 4082 4083 4084
{
	return addr >= start && addr < start + size;
}

4085 4086 4087 4088 4089 4090 4091 4092
/*
 * Used in module.c to remove lock classes from memory that is going to be
 * freed; and possibly re-used by other modules.
 *
 * We will have had one sync_sched() before getting here, so we're guaranteed
 * nobody will look up these exact classes -- they're properly dead but still
 * allocated.
 */
I
Ingo Molnar 已提交
4093 4094
void lockdep_free_key_range(void *start, unsigned long size)
{
4095
	struct lock_class *class;
4096
	struct hlist_head *head;
I
Ingo Molnar 已提交
4097 4098
	unsigned long flags;
	int i;
4099
	int locked;
I
Ingo Molnar 已提交
4100 4101

	raw_local_irq_save(flags);
4102
	locked = graph_lock();
I
Ingo Molnar 已提交
4103 4104 4105 4106 4107 4108

	/*
	 * Unhash all classes that were created by this module:
	 */
	for (i = 0; i < CLASSHASH_SIZE; i++) {
		head = classhash_table + i;
4109
		hlist_for_each_entry_rcu(class, head, hash_entry) {
I
Ingo Molnar 已提交
4110 4111
			if (within(class->key, start, size))
				zap_class(class);
4112 4113 4114
			else if (within(class->name, start, size))
				zap_class(class);
		}
I
Ingo Molnar 已提交
4115 4116
	}

4117 4118
	if (locked)
		graph_unlock();
I
Ingo Molnar 已提交
4119
	raw_local_irq_restore(flags);
4120 4121 4122 4123 4124 4125 4126 4127 4128 4129 4130 4131 4132 4133

	/*
	 * Wait for any possible iterators from look_up_lock_class() to pass
	 * before continuing to free the memory they refer to.
	 *
	 * sync_sched() is sufficient because the read-side is IRQ disable.
	 */
	synchronize_sched();

	/*
	 * XXX at this point we could return the resources to the pool;
	 * instead we leak them. We would need to change to bitmap allocators
	 * instead of the linear allocators we have now.
	 */
I
Ingo Molnar 已提交
4134 4135 4136 4137
}

void lockdep_reset_lock(struct lockdep_map *lock)
{
4138
	struct lock_class *class;
4139
	struct hlist_head *head;
I
Ingo Molnar 已提交
4140 4141
	unsigned long flags;
	int i, j;
4142
	int locked;
I
Ingo Molnar 已提交
4143 4144 4145 4146

	raw_local_irq_save(flags);

	/*
4147 4148 4149 4150 4151 4152 4153 4154 4155 4156 4157 4158 4159
	 * 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
4160
	 */
4161
	locked = graph_lock();
I
Ingo Molnar 已提交
4162 4163
	for (i = 0; i < CLASSHASH_SIZE; i++) {
		head = classhash_table + i;
4164
		hlist_for_each_entry_rcu(class, head, hash_entry) {
4165 4166 4167 4168 4169 4170
			int match = 0;

			for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
				match |= class == lock->class_cache[j];

			if (unlikely(match)) {
P
Peter Zijlstra 已提交
4171 4172 4173 4174
				if (debug_locks_off_graph_unlock()) {
					/*
					 * We all just reset everything, how did it match?
					 */
4175
					WARN_ON(1);
P
Peter Zijlstra 已提交
4176
				}
4177
				goto out_restore;
I
Ingo Molnar 已提交
4178 4179 4180
			}
		}
	}
4181 4182
	if (locked)
		graph_unlock();
4183 4184

out_restore:
I
Ingo Molnar 已提交
4185 4186 4187 4188 4189 4190 4191
	raw_local_irq_restore(flags);
}

void __init lockdep_info(void)
{
	printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");

4192
	printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
I
Ingo Molnar 已提交
4193 4194
	printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
	printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
4195
	printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
I
Ingo Molnar 已提交
4196 4197 4198 4199 4200 4201 4202 4203 4204
	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
4205
		sizeof(struct list_head) * CHAINHASH_SIZE
4206
#ifdef CONFIG_PROVE_LOCKING
4207
		+ sizeof(struct circular_queue)
4208
#endif
M
Ming Lei 已提交
4209
		) / 1024
4210
		);
I
Ingo Molnar 已提交
4211 4212 4213 4214 4215 4216 4217

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

static void
print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
4218
		     const void *mem_to, struct held_lock *hlock)
I
Ingo Molnar 已提交
4219 4220 4221 4222 4223 4224
{
	if (!debug_locks_off())
		return;
	if (debug_locks_silent)
		return;

4225 4226 4227
	printk("\n");
	printk("=========================\n");
	printk("[ BUG: held lock freed! ]\n");
4228
	print_kernel_ident();
4229
	printk("-------------------------\n");
I
Ingo Molnar 已提交
4230
	printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
4231
		curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
4232
	print_lock(hlock);
I
Ingo Molnar 已提交
4233 4234 4235 4236 4237 4238
	lockdep_print_held_locks(curr);

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

O
Oleg Nesterov 已提交
4239 4240 4241 4242 4243 4244 4245
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
4246 4247 4248 4249 4250 4251 4252 4253 4254 4255 4256 4257 4258 4259 4260 4261 4262 4263 4264
/*
 * 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
4265 4266
		if (not_in_range(mem_from, mem_len, hlock->instance,
					sizeof(*hlock->instance)))
I
Ingo Molnar 已提交
4267 4268
			continue;

O
Oleg Nesterov 已提交
4269
		print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
I
Ingo Molnar 已提交
4270 4271 4272 4273
		break;
	}
	local_irq_restore(flags);
}
4274
EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
I
Ingo Molnar 已提交
4275

4276
static void print_held_locks_bug(void)
I
Ingo Molnar 已提交
4277 4278 4279 4280 4281 4282
{
	if (!debug_locks_off())
		return;
	if (debug_locks_silent)
		return;

4283 4284
	printk("\n");
	printk("=====================================\n");
4285 4286
	printk("[ BUG: %s/%d still has locks held! ]\n",
	       current->comm, task_pid_nr(current));
4287
	print_kernel_ident();
4288
	printk("-------------------------------------\n");
4289
	lockdep_print_held_locks(current);
I
Ingo Molnar 已提交
4290 4291 4292 4293
	printk("\nstack backtrace:\n");
	dump_stack();
}

4294
void debug_check_no_locks_held(void)
I
Ingo Molnar 已提交
4295
{
4296 4297
	if (unlikely(current->lockdep_depth > 0))
		print_held_locks_bug();
I
Ingo Molnar 已提交
4298
}
4299
EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
I
Ingo Molnar 已提交
4300

4301
#ifdef __KERNEL__
I
Ingo Molnar 已提交
4302 4303 4304 4305 4306 4307
void debug_show_all_locks(void)
{
	struct task_struct *g, *p;
	int count = 10;
	int unlock = 1;

4308 4309 4310 4311
	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
I
Ingo Molnar 已提交
4312 4313 4314 4315 4316 4317 4318 4319 4320 4321 4322 4323 4324 4325 4326 4327 4328 4329 4330 4331
	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;
4332 4333 4334
	} else {
		if (count != 10)
			printk(KERN_CONT " locked it.\n");
I
Ingo Molnar 已提交
4335 4336 4337
	}

	do_each_thread(g, p) {
I
Ingo Molnar 已提交
4338 4339 4340 4341 4342 4343 4344
		/*
		 * 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
4345 4346 4347 4348 4349 4350 4351 4352 4353 4354 4355 4356 4357 4358
		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);
4359
#endif
I
Ingo Molnar 已提交
4360

4361 4362 4363 4364
/*
 * Careful: only use this function if you are sure that
 * the task cannot run in parallel!
 */
4365
void debug_show_held_locks(struct task_struct *task)
I
Ingo Molnar 已提交
4366
{
4367 4368 4369 4370
	if (unlikely(!debug_locks)) {
		printk("INFO: lockdep is turned off.\n");
		return;
	}
I
Ingo Molnar 已提交
4371 4372 4373
	lockdep_print_held_locks(task);
}
EXPORT_SYMBOL_GPL(debug_show_held_locks);
P
Peter Zijlstra 已提交
4374

4375
asmlinkage __visible void lockdep_sys_exit(void)
P
Peter Zijlstra 已提交
4376 4377 4378 4379 4380 4381
{
	struct task_struct *curr = current;

	if (unlikely(curr->lockdep_depth)) {
		if (!debug_locks_off())
			return;
4382 4383 4384
		printk("\n");
		printk("================================================\n");
		printk("[ BUG: lock held when returning to user space! ]\n");
4385
		print_kernel_ident();
4386
		printk("------------------------------------------------\n");
P
Peter Zijlstra 已提交
4387 4388 4389 4390 4391
		printk("%s/%d is leaving the kernel with locks still held!\n",
				curr->comm, curr->pid);
		lockdep_print_held_locks(curr);
	}
}
4392

4393
void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
4394 4395 4396
{
	struct task_struct *curr = current;

4397
#ifndef CONFIG_PROVE_RCU_REPEATEDLY
4398 4399
	if (!debug_locks_off())
		return;
4400 4401
#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
	/* Note: the following can be executed concurrently, so be careful. */
4402 4403 4404
	printk("\n");
	printk("===============================\n");
	printk("[ INFO: suspicious RCU usage. ]\n");
4405
	print_kernel_ident();
4406 4407
	printk("-------------------------------\n");
	printk("%s:%d %s!\n", file, line, s);
4408
	printk("\nother info that might help us debug this:\n\n");
4409 4410 4411
	printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
	       !rcu_lockdep_current_cpu_online()
			? "RCU used illegally from offline CPU!\n"
4412
			: !rcu_is_watching()
4413 4414 4415
				? "RCU used illegally from idle CPU!\n"
				: "",
	       rcu_scheduler_active, debug_locks);
4416 4417 4418 4419 4420 4421 4422 4423 4424 4425 4426 4427 4428 4429 4430 4431 4432 4433 4434

	/*
	 * If a CPU is in the RCU-free window in idle (ie: in the section
	 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
	 * considers that CPU to be in an "extended quiescent state",
	 * which means that RCU will be completely ignoring that CPU.
	 * Therefore, rcu_read_lock() and friends have absolutely no
	 * effect on a CPU running in that state. In other words, even if
	 * such an RCU-idle CPU has called rcu_read_lock(), RCU might well
	 * delete data structures out from under it.  RCU really has no
	 * choice here: we need to keep an RCU-free window in idle where
	 * the CPU may possibly enter into low power mode. This way we can
	 * notice an extended quiescent state to other CPUs that started a grace
	 * period. Otherwise we would delay any grace period as long as we run
	 * in the idle task.
	 *
	 * So complain bitterly if someone does call rcu_read_lock(),
	 * rcu_read_lock_bh() and so on from extended quiescent states.
	 */
4435
	if (!rcu_is_watching())
4436 4437
		printk("RCU used illegally from extended quiescent state!\n");

4438 4439 4440 4441
	lockdep_print_held_locks(curr);
	printk("\nstack backtrace:\n");
	dump_stack();
}
4442
EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);