Edit File: lglock.h
/* * 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_double_lock(struct lglock *lg, int cpu1, int cpu2); void lg_double_unlock(struct lglock *lg, int cpu1, int cpu2); void lg_global_lock(struct lglock *lg); void lg_global_unlock(struct lglock *lg); #endif