| 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 | /* can make br locks by using local lock for read side, global lock for write */ |
| 29 | #define br_lock_init(name) lg_lock_init(name, #name) |
| 30 | #define br_read_lock(name) lg_local_lock(name) |
| 31 | #define br_read_unlock(name) lg_local_unlock(name) |
| 32 | #define br_write_lock(name) lg_global_lock(name) |
| 33 | #define br_write_unlock(name) lg_global_unlock(name) |
| 34 | |
| 35 | #define DEFINE_BRLOCK(name) DEFINE_LGLOCK(name) |
| 36 | #define DEFINE_STATIC_BRLOCK(name) DEFINE_STATIC_LGLOCK(name) |
| 37 | |
| 38 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| 39 | #define LOCKDEP_INIT_MAP lockdep_init_map |
| 40 | #else |
| 41 | #define LOCKDEP_INIT_MAP(a, b, c, d) |
| 42 | #endif |
| 43 | |
| 44 | struct lglock { |
| 45 | arch_spinlock_t __percpu *lock; |
| 46 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| 47 | struct lock_class_key lock_key; |
| 48 | struct lockdep_map lock_dep_map; |
| 49 | #endif |
| 50 | }; |
| 51 | |
| 52 | #define DEFINE_LGLOCK(name) \ |
| 53 | static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock) \ |
| 54 | = __ARCH_SPIN_LOCK_UNLOCKED; \ |
| 55 | struct lglock name = { .lock = &name ## _lock } |
| 56 | |
| 57 | #define DEFINE_STATIC_LGLOCK(name) \ |
| 58 | static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock) \ |
| 59 | = __ARCH_SPIN_LOCK_UNLOCKED; \ |
| 60 | static struct lglock name = { .lock = &name ## _lock } |
| 61 | |
| 62 | void lg_lock_init(struct lglock *lg, char *name); |
| 63 | void lg_local_lock(struct lglock *lg); |
| 64 | void lg_local_unlock(struct lglock *lg); |
| 65 | void lg_local_lock_cpu(struct lglock *lg, int cpu); |
| 66 | void lg_local_unlock_cpu(struct lglock *lg, int cpu); |
| 67 | void lg_global_lock(struct lglock *lg); |
| 68 | void lg_global_unlock(struct lglock *lg); |
| 69 | |
| 70 | #endif |