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kernel/linux-imx6_3.14.28/include/linux/lglock.h 1.9 KB
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  /*
   * 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>
  
  #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