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Diffstat (limited to 'kernel/include/linux/lglock.h')
| -rw-r--r-- | kernel/include/linux/lglock.h | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/kernel/include/linux/lglock.h b/kernel/include/linux/lglock.h new file mode 100644 index 000000000..9603a1500 --- /dev/null +++ b/kernel/include/linux/lglock.h @@ -0,0 +1,99 @@ +/* + * 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_SMP + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +#define LOCKDEP_INIT_MAP lockdep_init_map +#else +#define LOCKDEP_INIT_MAP(a, b, c, d) +#endif + +struct lglock { +#ifndef CONFIG_PREEMPT_RT_FULL + arch_spinlock_t __percpu *lock; +#else + struct rt_mutex __percpu *lock; +#endif +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct lock_class_key lock_key; + struct lockdep_map lock_dep_map; +#endif +}; + +#ifndef CONFIG_PREEMPT_RT_FULL +# 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 } +#else + +# define DEFINE_LGLOCK(name) \ + static DEFINE_PER_CPU(struct rt_mutex, name ## _lock) \ + = __RT_MUTEX_INITIALIZER( name ## _lock); \ + struct lglock name = { .lock = &name ## _lock } + +# define DEFINE_STATIC_LGLOCK(name) \ + static DEFINE_PER_CPU(struct rt_mutex, name ## _lock) \ + = __RT_MUTEX_INITIALIZER( name ## _lock); \ + static struct lglock name = { .lock = &name ## _lock } +#endif + +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); + +#ifndef CONFIG_PREEMPT_RT_FULL +#define lg_global_trylock_relax(name) lg_global_lock(name) +#else +void lg_global_trylock_relax(struct lglock *lg); +#endif + +#else +/* When !CONFIG_SMP, map lglock to spinlock */ +#define lglock spinlock +#define DEFINE_LGLOCK(name) DEFINE_SPINLOCK(name) +#define DEFINE_STATIC_LGLOCK(name) static DEFINE_SPINLOCK(name) +#define lg_lock_init(lg, name) spin_lock_init(lg) +#define lg_local_lock spin_lock +#define lg_local_unlock spin_unlock +#define lg_local_lock_cpu(lg, cpu) spin_lock(lg) +#define lg_local_unlock_cpu(lg, cpu) spin_unlock(lg) +#define lg_global_lock spin_lock +#define lg_global_unlock spin_unlock +#endif + +#endif |