diff options
| -rw-r--r-- | include/linux/lglock.h | 85 | ||||
| -rw-r--r-- | kernel/locking/Makefile | 1 | ||||
| -rw-r--r-- | kernel/locking/lglock.c | 105 |
3 files changed, 191 insertions, 0 deletions
diff --git a/include/linux/lglock.h b/include/linux/lglock.h new file mode 100644 index 000000000000..d0f59aeca769 --- /dev/null +++ b/include/linux/lglock.h @@ -0,0 +1,85 @@ +/* + * 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 { + arch_spinlock_t __percpu *lock; +#ifdef CONFIG_DEBUG_LOCK_ALLOC + 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 } + +#define lg_lock_init(lock) \ +do { \ + static struct lock_class_key __key; \ + \ + lockdep_init_map(&(lock)->lock_dep_map, #lock, &__key, 0); \ +} while (0) + +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); + +#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 diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile index 6f88e352cd4f..31322a4275cd 100644 --- a/kernel/locking/Makefile +++ b/kernel/locking/Makefile @@ -18,6 +18,7 @@ obj-$(CONFIG_LOCKDEP) += lockdep_proc.o endif obj-$(CONFIG_SMP) += spinlock.o obj-$(CONFIG_LOCK_SPIN_ON_OWNER) += osq_lock.o +obj-$(CONFIG_SMP) += lglock.o obj-$(CONFIG_PROVE_LOCKING) += spinlock.o obj-$(CONFIG_QUEUED_SPINLOCKS) += qspinlock.o obj-$(CONFIG_RT_MUTEXES) += rtmutex.o diff --git a/kernel/locking/lglock.c b/kernel/locking/lglock.c new file mode 100644 index 000000000000..7c6fd364879b --- /dev/null +++ b/kernel/locking/lglock.c @@ -0,0 +1,105 @@ +/* See include/linux/lglock.h for description */ +#include <linux/module.h> +#include <linux/lglock.h> +#include <linux/cpu.h> +#include <linux/string.h> + +/* + * Note there is no uninit, so lglocks cannot be defined in + * modules (but it's fine to use them from there) + * Could be added though, just undo lg_lock_init + */ + +void lg_local_lock(struct lglock *lg) +{ + arch_spinlock_t *lock; + + preempt_disable(); + lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_); + lock = this_cpu_ptr(lg->lock); + arch_spin_lock(lock); +} +EXPORT_SYMBOL(lg_local_lock); + +void lg_local_unlock(struct lglock *lg) +{ + arch_spinlock_t *lock; + + lock_release(&lg->lock_dep_map, 1, _RET_IP_); + lock = this_cpu_ptr(lg->lock); + arch_spin_unlock(lock); + preempt_enable(); +} +EXPORT_SYMBOL(lg_local_unlock); + +void lg_local_lock_cpu(struct lglock *lg, int cpu) +{ + arch_spinlock_t *lock; + + preempt_disable(); + lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_); + lock = per_cpu_ptr(lg->lock, cpu); + arch_spin_lock(lock); +} +EXPORT_SYMBOL(lg_local_lock_cpu); + +void lg_local_unlock_cpu(struct lglock *lg, int cpu) +{ + arch_spinlock_t *lock; + + lock_release(&lg->lock_dep_map, 1, _RET_IP_); + lock = per_cpu_ptr(lg->lock, cpu); + arch_spin_unlock(lock); + preempt_enable(); +} +EXPORT_SYMBOL(lg_local_unlock_cpu); + +void lg_double_lock(struct lglock *lg, int cpu1, int cpu2) +{ + BUG_ON(cpu1 == cpu2); + + /* lock in cpu order, just like lg_global_lock */ + if (cpu2 < cpu1) + swap(cpu1, cpu2); + + preempt_disable(); + lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_); + arch_spin_lock(per_cpu_ptr(lg->lock, cpu1)); + arch_spin_lock(per_cpu_ptr(lg->lock, cpu2)); +} + +void lg_double_unlock(struct lglock *lg, int cpu1, int cpu2) +{ + lock_release(&lg->lock_dep_map, 1, _RET_IP_); + arch_spin_unlock(per_cpu_ptr(lg->lock, cpu1)); + arch_spin_unlock(per_cpu_ptr(lg->lock, cpu2)); + preempt_enable(); +} + +void lg_global_lock(struct lglock *lg) +{ + int i; + + preempt_disable(); + lock_acquire_exclusive(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_); + for_each_possible_cpu(i) { + arch_spinlock_t *lock; + lock = per_cpu_ptr(lg->lock, i); + arch_spin_lock(lock); + } +} +EXPORT_SYMBOL(lg_global_lock); + +void lg_global_unlock(struct lglock *lg) +{ + int i; + + lock_release(&lg->lock_dep_map, 1, _RET_IP_); + for_each_possible_cpu(i) { + arch_spinlock_t *lock; + lock = per_cpu_ptr(lg->lock, i); + arch_spin_unlock(lock); + } + preempt_enable(); +} +EXPORT_SYMBOL(lg_global_unlock); |