kernel-ark/include/linux/lglock.h
Lai Jiangshan 4b2c551f77 lglock: add DEFINE_STATIC_LGLOCK()
When the lglock doesn't need to be exported we can use
DEFINE_STATIC_LGLOCK().

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-10-10 01:15:44 -04:00

71 lines
2.3 KiB
C

/*
* Specialised local-global spinlock. Can only be declared as global variables
* to avoid overhead and keep things simple (and we don't want to start using
* these inside dynamically allocated structures).
*
* "local/global locks" (lglocks) can be used to:
*
* - Provide fast exclusive access to per-CPU data, with exclusive access to
* another CPU's data allowed but possibly subject to contention, and to
* provide very slow exclusive access to all per-CPU data.
* - Or to provide very fast and scalable read serialisation, and to provide
* very slow exclusive serialisation of data (not necessarily per-CPU data).
*
* Brlocks are also implemented as a short-hand notation for the latter use
* case.
*
* Copyright 2009, 2010, Nick Piggin, Novell Inc.
*/
#ifndef __LINUX_LGLOCK_H
#define __LINUX_LGLOCK_H
#include <linux/spinlock.h>
#include <linux/lockdep.h>
#include <linux/percpu.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
/* can make br locks by using local lock for read side, global lock for write */
#define br_lock_init(name) lg_lock_init(name, #name)
#define br_read_lock(name) lg_local_lock(name)
#define br_read_unlock(name) lg_local_unlock(name)
#define br_write_lock(name) lg_global_lock(name)
#define br_write_unlock(name) lg_global_unlock(name)
#define DEFINE_BRLOCK(name) DEFINE_LGLOCK(name)
#define DEFINE_STATIC_BRLOCK(name) DEFINE_STATIC_LGLOCK(name)
#ifdef CONFIG_DEBUG_LOCK_ALLOC
#define LOCKDEP_INIT_MAP lockdep_init_map
#else
#define LOCKDEP_INIT_MAP(a, b, c, d)
#endif
struct lglock {
arch_spinlock_t __percpu *lock;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lock_class_key lock_key;
struct lockdep_map lock_dep_map;
#endif
};
#define DEFINE_LGLOCK(name) \
static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock) \
= __ARCH_SPIN_LOCK_UNLOCKED; \
struct lglock name = { .lock = &name ## _lock }
#define DEFINE_STATIC_LGLOCK(name) \
static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock) \
= __ARCH_SPIN_LOCK_UNLOCKED; \
static struct lglock name = { .lock = &name ## _lock }
void lg_lock_init(struct lglock *lg, char *name);
void lg_local_lock(struct lglock *lg);
void lg_local_unlock(struct lglock *lg);
void lg_local_lock_cpu(struct lglock *lg, int cpu);
void lg_local_unlock_cpu(struct lglock *lg, int cpu);
void lg_global_lock(struct lglock *lg);
void lg_global_unlock(struct lglock *lg);
#endif