Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * Specialised local-global spinlock. Can only be declared as global variables
3 * to avoid overhead and keep things simple (and we don't want to start using
4 * these inside dynamically allocated structures).
5 *
6 * "local/global locks" (lglocks) can be used to:
7 *
8 * - Provide fast exclusive access to per-CPU data, with exclusive access to
9 * another CPU's data allowed but possibly subject to contention, and to
10 * provide very slow exclusive access to all per-CPU data.
11 * - Or to provide very fast and scalable read serialisation, and to provide
12 * very slow exclusive serialisation of data (not necessarily per-CPU data).
13 *
14 * Brlocks are also implemented as a short-hand notation for the latter use
15 * case.
16 *
17 * Copyright 2009, 2010, Nick Piggin, Novell Inc.
18 */
19#ifndef __LINUX_LGLOCK_H
20#define __LINUX_LGLOCK_H
21
22#include <linux/spinlock.h>
23#include <linux/lockdep.h>
24#include <linux/percpu.h>
25#include <linux/cpu.h>
26#include <linux/notifier.h>
27
28#ifdef CONFIG_SMP
29
30#ifdef CONFIG_DEBUG_LOCK_ALLOC
31#define LOCKDEP_INIT_MAP lockdep_init_map
32#else
33#define LOCKDEP_INIT_MAP(a, b, c, d)
34#endif
35
36struct lglock {
37 arch_spinlock_t __percpu *lock;
38#ifdef CONFIG_DEBUG_LOCK_ALLOC
39 struct lock_class_key lock_key;
40 struct lockdep_map lock_dep_map;
41#endif
42};
43
44#define DEFINE_LGLOCK(name) \
45 static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock) \
46 = __ARCH_SPIN_LOCK_UNLOCKED; \
47 struct lglock name = { .lock = &name ## _lock }
48
49#define DEFINE_STATIC_LGLOCK(name) \
50 static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock) \
51 = __ARCH_SPIN_LOCK_UNLOCKED; \
52 static struct lglock name = { .lock = &name ## _lock }
53
54void lg_lock_init(struct lglock *lg, char *name);
55
56void lg_local_lock(struct lglock *lg);
57void lg_local_unlock(struct lglock *lg);
58void lg_local_lock_cpu(struct lglock *lg, int cpu);
59void lg_local_unlock_cpu(struct lglock *lg, int cpu);
60
61void lg_double_lock(struct lglock *lg, int cpu1, int cpu2);
62void lg_double_unlock(struct lglock *lg, int cpu1, int cpu2);
63
64void lg_global_lock(struct lglock *lg);
65void lg_global_unlock(struct lglock *lg);
66
67#else
68/* When !CONFIG_SMP, map lglock to spinlock */
69#define lglock spinlock
70#define DEFINE_LGLOCK(name) DEFINE_SPINLOCK(name)
71#define DEFINE_STATIC_LGLOCK(name) static DEFINE_SPINLOCK(name)
72#define lg_lock_init(lg, name) spin_lock_init(lg)
73#define lg_local_lock spin_lock
74#define lg_local_unlock spin_unlock
75#define lg_local_lock_cpu(lg, cpu) spin_lock(lg)
76#define lg_local_unlock_cpu(lg, cpu) spin_unlock(lg)
77#define lg_global_lock spin_lock
78#define lg_global_unlock spin_unlock
79#endif
80
81#endif