Release 4.15 kernel/locking/lockdep.c

/*
 * kernel/lockdep.c
 *
 * Runtime locking correctness validator
 *
 * Started by Ingo Molnar:
 *
 *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
 *
 * 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.
 */

#define DISABLE_BRANCH_PROFILING
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <linux/sched/task.h>
#include <linux/sched/mm.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>
#include <linux/utsname.h>
#include <linux/hash.h>
#include <linux/ftrace.h>
#include <linux/stringify.h>
#include <linux/bitops.h>
#include <linux/gfp.h>
#include <linux/random.h>
#include <linux/jhash.h>
#include <linux/nmi.h>

#include <asm/sections.h>

#include "lockdep_internals.h"


#define CREATE_TRACE_POINTS
#include <trace/events/lock.h>

#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

/*
 * lockdep_lock: protects the lockdep graph, the hashes and the
 *               class/list/hash allocators.
 *
 * This is one of the rare exceptions where it's justified
 * to use a raw spinlock - we really dont want the spinlock
 * code to recurse back into the lockdep code...
 */

static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;



static int graph_lock(void)
{
	arch_spin_lock(&lockdep_lock);
	/*
         * Make sure that if another CPU detected a bug while
         * walking the graph we dont change it (while the other
         * CPU is busy printing out stuff with the graph lock
         * dropped already)
         */
	if (!debug_locks) {
		arch_spin_unlock(&lockdep_lock);
		return 0;
	}
	/* prevent any recursions within lockdep from causing deadlocks */
	current->lockdep_recursion++;
	return 1;
}

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static inline int graph_unlock(void)
{
	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!
                 */
		return DEBUG_LOCKS_WARN_ON(1);
	}

	current->lockdep_recursion--;
	arch_spin_unlock(&lockdep_lock);
	return 0;
}

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/*
 * 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();

	arch_spin_unlock(&lockdep_lock);

	return ret;
}

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unsigned long nr_list_entries;

static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];

/*
 * All data structures here are protected by the global debug_lock.
 *
 * Mutex key structs only get allocated, once during bootup, and never
 * get freed - this significantly simplifies the debugging code.
 */

unsigned long nr_lock_classes;

static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];



static inline struct lock_class *hlock_class(struct held_lock *hlock)
{
	if (!hlock->class_idx) {
		/*
                 * Someone passed in garbage, we give up.
                 */
		DEBUG_LOCKS_WARN_ON(1);
		return NULL;
	}
	return lock_classes + hlock->class_idx - 1;
}

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



static inline u64 lockstat_clock(void)
{
	return local_clock();
}

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

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

	return i;
}

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

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

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

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Frank Rowand
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static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
{
	if (!src->nr)
		return;

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

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

	dst->total += src->total;
	dst->nr += src->nr;
}

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

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

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

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

		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);

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

	return stats;
}

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

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

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

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

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

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static void lock_release_holdtime(struct held_lock *hlock)
{
	struct lock_class_stats *stats;
	u64 holdtime;

	if (!lock_stat)
		return;

	holdtime = lockstat_clock() - hlock->holdtime_stamp;

	stats = get_lock_stats(hlock_class(hlock));
	if (hlock->read)
		lock_time_inc(&stats->read_holdtime, holdtime);
	else
		lock_time_inc(&stats->write_holdtime, holdtime);
	put_lock_stats(stats);
}
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#else


static inline void lock_release_holdtime(struct held_lock *hlock)
{
}
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#endif

/*
 * 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)

#define __classhashfn(key)	hash_long((unsigned long)key, CLASSHASH_BITS)

#define classhashentry(key)	(classhash_table + __classhashfn((key)))


static struct hlist_head classhash_table[CLASSHASH_SIZE];

/*
 * We put the lock dependency chains into a hash-table as well, to cache
 * their existence:
 */

#define CHAINHASH_BITS		(MAX_LOCKDEP_CHAINS_BITS-1)

#define CHAINHASH_SIZE		(1UL << CHAINHASH_BITS)

#define __chainhashfn(chain)	hash_long(chain, CHAINHASH_BITS)

#define chainhashentry(chain)	(chainhash_table + __chainhashfn((chain)))


static struct hlist_head chainhash_table[CHAINHASH_SIZE];

/*
 * The hash key of the lock dependency chains is a hash itself too:
 * it's a hash of all locks taken up to that lock, including that lock.
 * It's a 64-bit hash, because it's important for the keys to be
 * unique.
 */


static inline u64 iterate_chain_key(u64 key, u32 idx)
{
	u32 k0 = key, k1 = key >> 32;

	__jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */

	return k0 | (u64)k1 << 32;
}

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



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

/*
 * Debugging switches:
 */


#define VERBOSE			0

#define VERY_VERBOSE		0

#if VERBOSE

# define HARDIRQ_VERBOSE	1

# define SOFTIRQ_VERBOSE	1
#else

# define HARDIRQ_VERBOSE	0

# define SOFTIRQ_VERBOSE	0
#endif

#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
/*
 * Quick filtering for interesting events:
 */


static int class_filter(struct lock_class *class)
{
#if 0
	/* Example */
	if (class->name_version == 1 &&
                        !strcmp(class->name, "lockname"))
                return 1;
        if (class->name_version == 1 &&
                        !strcmp(class->name, "&struct->lockfield"))
                return 1;
#endif
	/* 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;
}

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/*
 * Stack-trace: tightly packed array of stack backtrace
 * addresses. Protected by the graph_lock.
 */

unsigned long nr_stack_trace_entries;

static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];



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");
#ifdef CONFIG_LOCK_STAT
	printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
#endif
}

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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;

	trace->skip = 3;

	save_stack_trace(trace);

	/*
         * 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>
         */
	if (trace->nr_entries != 0 &&
	    trace->entries[trace->nr_entries-1] == ULONG_MAX)
		trace->nr_entries--;

	trace->max_entries = trace->nr_entries;

	nr_stack_trace_entries += trace->nr_entries;

	if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
		if (!debug_locks_off_graph_unlock())
			return 0;

		print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
		dump_stack();

		return 0;
	}

	return 1;
}

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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:
 */
DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
#endif

/*
 * Locking printouts:
 */


#define __USAGE(__STATE)						\
	[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",


static const char *usage_str[] =
{

#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
#include "lockdep_states.h"

#undef LOCKDEP_STATE
	[LOCK_USED] = "INITIAL USE",
};



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

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static inline unsigned long lock_flag(enum lock_usage_bit bit)
{
	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 = '?';
	}

	return c;
}

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void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
{
	int i = 0;


#define LOCKDEP_STATE(__STATE) 						\
	usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE);     \
        usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
#include "lockdep_states.h"

#undef LOCKDEP_STATE

	usage[i] = '\0';
}

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

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

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static void print_lockdep_cache(struct lockdep_map *lock)
{
	const char *name;
	char str[KSYM_NAME_LEN];

	name = lock->name;
	if (!name)
		name = __get_key_name(lock->key->subkeys, str);

	printk(KERN_CONT "%s", name);
}

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static void print_lock(struct held_lock *hlock)
{
	/*
         * 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(KERN_CONT "<RELEASED>\n");
		return;
	}

	print_lock_name(lock_classes + class_idx - 1);
	printk(KERN_CONT ", at: [<%p>] %pS\n",
		(void *)hlock->acquire_ip, (void *)hlock->acquire_ip);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Peter Zijlstra
39
50.65%
1
25.00%
Ingo Molnar
21
27.27%
1
25.00%
Dmitriy Vyukov
16
20.78%
1
25.00%
Dave Jones
1
1.30%
1
25.00%
Total
77
100.00%
4
100.00%



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

	if (!depth) {
		printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
		return;
	}
	printk("%d lock%s held by %s/%d:\n",
		depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));

	for (i = 0; i < depth; i++) {
		printk(" #%d: ", i);
		print_lock(curr->held_locks + i);
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ingo Molnar
91
93.81%
1
50.00%
Pavel Emelyanov
6
6.19%
1
50.00%
Total
97
100.00%
2
100.00%



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

Contributors
Person
Tokens
Prop
Commits
CommitProp
Peter Zijlstra
16
41.03%
1
25.00%
Ingo Molnar
16
41.03%
1
25.00%
Ben Hutchings
5
12.82%
1
25.00%
Andi Kleen
2
5.13%
1
25.00%
Total
39
100.00%
4
100.00%



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

Contributors
Person
Tokens
Prop
Commits
CommitProp
Peter Zijlstra
21
84.00%
1
50.00%
Ingo Molnar
4
16.00%
1
50.00%
Total
25
100.00%
2
100.00%

/*
 * Is this the address of a static object:
 */
#ifdef __KERNEL__


static int static_obj(void *obj)
{
	unsigned long start = (unsigned long) &_stext,
		      end   = (unsigned long) &_end,
		      addr  = (unsigned long) obj;

	/*
         * static variable?
         */
	if ((addr >= start) && (addr < end))
		return 1;

	if (arch_is_kernel_data(addr))
		return 1;

	/*
         * in-kernel percpu var?
         */
	if (is_kernel_percpu_address(addr))
		return 1;

	/*
         * module static or percpu var?
         */
	return is_module_address(addr) || is_module_percpu_address(addr);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Peter Zijlstra
53
59.55%
1
25.00%
Lei Ming
16
17.98%
1
25.00%
Tejun Heo
10
11.24%
1
25.00%
Mike Frysinger
10
11.24%
1
25.00%
Total
89
100.00%
4
100.00%

#endif

/*
 * To make lock name printouts unique, we calculate a unique
 * class->name_version generation counter:
 */


static int count_matching_names(struct lock_class *new_class)
{
	struct lock_class *class;
	int count = 0;

	if (!new_class->name)
		return 0;

	list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
		if (new_class->key - new_class->subclass == class->key)
			return class->name_version;
		if (class->name && !strcmp(class->name, new_class->name))
			count = max(count, class->name_version);
	}

	return count + 1;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Peter Zijlstra
61
64.89%
2
33.33%
Ingo Molnar
26
27.66%
1
16.67%
David S. Miller
3
3.19%
1
16.67%
Jarek Poplawski
3
3.19%
1
16.67%
Andi Kleen
1
1.06%
1
16.67%
Total
94
100.00%
6
100.00%

/*
 * 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)
{
	struct lockdep_subclass_key *key;
	struct hlist_head *hash_head;
	struct lock_class *class;
	bool is_static = false;

	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;
	}

	/*
         * Static locks do not have their class-keys yet - for them the key
         * is the lock object itself. If the lock is in the per cpu area,
         * the canonical address of the lock (per cpu offset removed) is
         * used.
         */
	if (unlikely(!lock->key)) {
		unsigned long can_addr, addr = (unsigned long)lock;

		if (__is_kernel_percpu_address(addr, &can_addr))
			lock->key = (void *)can_addr;
		else if (__is_module_percpu_address(addr, &can_addr))
			lock->key = (void *)can_addr;
		else if (static_obj(lock))
			lock->key = (void *)lock;
		else
			return ERR_PTR(-EINVAL);
		is_static = true;
	}

	/*
         * 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.
         */
	BUILD_BUG_ON(sizeof(struct lock_class_key) >
			sizeof(struct lockdep_map));

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

	hash_head = classhashentry(key);

	/*
         * We do an RCU walk of the hash, see lockdep_free_key_range().
         */
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return NULL;

	hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
		if (class->key == key) {
			/*
                         * Huh! same key, different name? Did someone trample
                         * on some memory? We're most confused.
                         */
			WARN_ON_ONCE(class->name != lock->name);
			return class;
		}
	}

	return is_static || static_obj(lock->key) ? NULL : ERR_PTR(-EINVAL);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Peter Zijlstra
127
47.57%
4
44.44%
Thomas Gleixner
96
35.96%
1
11.11%
Hitoshi Mitake
34
12.73%
1
11.11%
Ingo Molnar
7
2.62%
1
11.11%
Andrew Morton
2
0.75%
1
11.11%
Jarek Poplawski
1
0.37%
1
11.11%
Total
267
100.00%
9
100.00%

/*
 * 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 struct lock_class *

register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
{
	struct lockdep_subclass_key *key;
	struct hlist_head *hash_head;
	struct lock_class *class;

	DEBUG_LOCKS_WARN_ON(!irqs_disabled());

	class = look_up_lock_class(lock, subclass);
	if (likely(!IS_ERR_OR_NULL(class)))
		goto out_set_class_cache;

	/*
         * Debug-check: all keys must be persistent!
         */
	if (IS_ERR(class)) {
		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:
         */
	hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
		if (class->key == key)
			goto out_unlock_set;
	}

	/*
         * Allocate a new key from the static array, and add it to
         * the hash:
         */
	if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
		if (!debug_locks_off_graph_unlock()) {
			return NULL;
		}

		print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
		dump_stack();
		return NULL;
	}
	class = lock_classes + nr_lock_classes++;
	debug_atomic_inc(nr_unused_locks);
	class->key = key;
	class->name = lock->name;
	class->subclass = subclass;
	INIT_LIST_HEAD(&class->lock_entry);
	INIT_LIST_HEAD(&class->locks_before);
	INIT_LIST_HEAD(&class->locks_after);
	class->name_version = count_matching_names(class);
	/*
         * We use RCU's safe list-add method to make
         * parallel walking of the hash-list safe:
         */
	hlist_add_head_rcu(&class->hash_entry, hash_head);
	/*
         * Add it to the global list of classes:
         */
	list_add_tail_rcu(&class->lock_entry, &all_lock_classes);

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

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