LXR linux/include/linux/lglock.h

   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_DEBUG_LOCK_ALLOC
  29#define LOCKDEP_INIT_MAP lockdep_init_map
  30#else
  31#define LOCKDEP_INIT_MAP(a, b, c, d)
  32#endif
  33
  34struct lglock {
  35        arch_spinlock_t __percpu *lock;
  36#ifdef CONFIG_DEBUG_LOCK_ALLOC
  37        struct lock_class_key lock_key;
  38        struct lockdep_map    lock_dep_map;
  39#endif
  40};
  41
  42#define DEFINE_LGLOCK(name)                                             \
  43        static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock)           \
  44        = __ARCH_SPIN_LOCK_UNLOCKED;                                    \
  45        struct lglock name = { .lock = &name ## _lock }
  46
  47#define DEFINE_STATIC_LGLOCK(name)                                      \
  48        static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock)           \
  49        = __ARCH_SPIN_LOCK_UNLOCKED;                                    \
  50        static struct lglock name = { .lock = &name ## _lock }
  51
  52void lg_lock_init(struct lglock *lg, char *name);
  53void lg_local_lock(struct lglock *lg);
  54void lg_local_unlock(struct lglock *lg);
  55void lg_local_lock_cpu(struct lglock *lg, int cpu);
  56void lg_local_unlock_cpu(struct lglock *lg, int cpu);
  57void lg_global_lock(struct lglock *lg);
  58void lg_global_unlock(struct lglock *lg);
  59
  60#endif
  61