diff options
Diffstat (limited to 'include/linux/lglock.h')
| -rw-r--r-- | include/linux/lglock.h | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/include/linux/lglock.h b/include/linux/lglock.h new file mode 100644 index 00000000..87f402cc --- /dev/null +++ b/include/linux/lglock.h @@ -0,0 +1,200 @@ +/* + * 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> + +/* can make br locks by using local lock for read side, global lock for write */ +#define br_lock_init(name) name##_lock_init() +#define br_read_lock(name) name##_local_lock() +#define br_read_unlock(name) name##_local_unlock() +#define br_write_lock(name) name##_global_lock_online() +#define br_write_unlock(name) name##_global_unlock_online() + +#define DECLARE_BRLOCK(name) DECLARE_LGLOCK(name) +#define DEFINE_BRLOCK(name) DEFINE_LGLOCK(name) + + +#define lg_lock_init(name) name##_lock_init() +#define lg_local_lock(name) name##_local_lock() +#define lg_local_unlock(name) name##_local_unlock() +#define lg_local_lock_cpu(name, cpu) name##_local_lock_cpu(cpu) +#define lg_local_unlock_cpu(name, cpu) name##_local_unlock_cpu(cpu) +#define lg_global_lock(name) name##_global_lock() +#define lg_global_unlock(name) name##_global_unlock() +#define lg_global_lock_online(name) name##_global_lock_online() +#define lg_global_unlock_online(name) name##_global_unlock_online() + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +#define LOCKDEP_INIT_MAP lockdep_init_map + +#define DEFINE_LGLOCK_LOCKDEP(name) \ + struct lock_class_key name##_lock_key; \ + struct lockdep_map name##_lock_dep_map; \ + EXPORT_SYMBOL(name##_lock_dep_map) + +#else +#define LOCKDEP_INIT_MAP(a, b, c, d) + +#define DEFINE_LGLOCK_LOCKDEP(name) +#endif + + +#define DECLARE_LGLOCK(name) \ + extern void name##_lock_init(void); \ + extern void name##_local_lock(void); \ + extern void name##_local_unlock(void); \ + extern void name##_local_lock_cpu(int cpu); \ + extern void name##_local_unlock_cpu(int cpu); \ + extern void name##_global_lock(void); \ + extern void name##_global_unlock(void); \ + extern void name##_global_lock_online(void); \ + extern void name##_global_unlock_online(void); \ + +#define DEFINE_LGLOCK(name) \ + \ + DEFINE_SPINLOCK(name##_cpu_lock); \ + cpumask_t name##_cpus __read_mostly; \ + DEFINE_PER_CPU(arch_spinlock_t, name##_lock); \ + DEFINE_LGLOCK_LOCKDEP(name); \ + \ + static int \ + name##_lg_cpu_callback(struct notifier_block *nb, \ + unsigned long action, void *hcpu) \ + { \ + switch (action & ~CPU_TASKS_FROZEN) { \ + case CPU_UP_PREPARE: \ + spin_lock(&name##_cpu_lock); \ + cpu_set((unsigned long)hcpu, name##_cpus); \ + spin_unlock(&name##_cpu_lock); \ + break; \ + case CPU_UP_CANCELED: case CPU_DEAD: \ + spin_lock(&name##_cpu_lock); \ + cpu_clear((unsigned long)hcpu, name##_cpus); \ + spin_unlock(&name##_cpu_lock); \ + } \ + return NOTIFY_OK; \ + } \ + static struct notifier_block name##_lg_cpu_notifier = { \ + .notifier_call = name##_lg_cpu_callback, \ + }; \ + void name##_lock_init(void) { \ + int i; \ + LOCKDEP_INIT_MAP(&name##_lock_dep_map, #name, &name##_lock_key, 0); \ + for_each_possible_cpu(i) { \ + arch_spinlock_t *lock; \ + lock = &per_cpu(name##_lock, i); \ + *lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; \ + } \ + register_hotcpu_notifier(&name##_lg_cpu_notifier); \ + get_online_cpus(); \ + for_each_online_cpu(i) \ + cpu_set(i, name##_cpus); \ + put_online_cpus(); \ + } \ + EXPORT_SYMBOL(name##_lock_init); \ + \ + void name##_local_lock(void) { \ + arch_spinlock_t *lock; \ + preempt_disable(); \ + rwlock_acquire_read(&name##_lock_dep_map, 0, 0, _THIS_IP_); \ + lock = &__get_cpu_var(name##_lock); \ + arch_spin_lock(lock); \ + } \ + EXPORT_SYMBOL(name##_local_lock); \ + \ + void name##_local_unlock(void) { \ + arch_spinlock_t *lock; \ + rwlock_release(&name##_lock_dep_map, 1, _THIS_IP_); \ + lock = &__get_cpu_var(name##_lock); \ + arch_spin_unlock(lock); \ + preempt_enable(); \ + } \ + EXPORT_SYMBOL(name##_local_unlock); \ + \ + void name##_local_lock_cpu(int cpu) { \ + arch_spinlock_t *lock; \ + preempt_disable(); \ + rwlock_acquire_read(&name##_lock_dep_map, 0, 0, _THIS_IP_); \ + lock = &per_cpu(name##_lock, cpu); \ + arch_spin_lock(lock); \ + } \ + EXPORT_SYMBOL(name##_local_lock_cpu); \ + \ + void name##_local_unlock_cpu(int cpu) { \ + arch_spinlock_t *lock; \ + rwlock_release(&name##_lock_dep_map, 1, _THIS_IP_); \ + lock = &per_cpu(name##_lock, cpu); \ + arch_spin_unlock(lock); \ + preempt_enable(); \ + } \ + EXPORT_SYMBOL(name##_local_unlock_cpu); \ + \ + void name##_global_lock_online(void) { \ + int i; \ + spin_lock(&name##_cpu_lock); \ + rwlock_acquire(&name##_lock_dep_map, 0, 0, _RET_IP_); \ + for_each_cpu(i, &name##_cpus) { \ + arch_spinlock_t *lock; \ + lock = &per_cpu(name##_lock, i); \ + arch_spin_lock(lock); \ + } \ + } \ + EXPORT_SYMBOL(name##_global_lock_online); \ + \ + void name##_global_unlock_online(void) { \ + int i; \ + rwlock_release(&name##_lock_dep_map, 1, _RET_IP_); \ + for_each_cpu(i, &name##_cpus) { \ + arch_spinlock_t *lock; \ + lock = &per_cpu(name##_lock, i); \ + arch_spin_unlock(lock); \ + } \ + spin_unlock(&name##_cpu_lock); \ + } \ + EXPORT_SYMBOL(name##_global_unlock_online); \ + \ + void name##_global_lock(void) { \ + int i; \ + preempt_disable(); \ + rwlock_acquire(&name##_lock_dep_map, 0, 0, _RET_IP_); \ + for_each_possible_cpu(i) { \ + arch_spinlock_t *lock; \ + lock = &per_cpu(name##_lock, i); \ + arch_spin_lock(lock); \ + } \ + } \ + EXPORT_SYMBOL(name##_global_lock); \ + \ + void name##_global_unlock(void) { \ + int i; \ + rwlock_release(&name##_lock_dep_map, 1, _RET_IP_); \ + for_each_possible_cpu(i) { \ + arch_spinlock_t *lock; \ + lock = &per_cpu(name##_lock, i); \ + arch_spin_unlock(lock); \ + } \ + preempt_enable(); \ + } \ + EXPORT_SYMBOL(name##_global_unlock); +#endif |