| 1 | |
| 2 | * Specialised local-global spinlock. Can only be declared as global variables
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| 3 | * to avoid overhead and keep things simple (and we don't want to start using
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| 4 | * these inside dynamically allocated structures).
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| 5 | *
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| 6 | * "local/global locks" (lglocks) can be used to:
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| 7 | *
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| 8 | * - Provide fast exclusive access to per-CPU data, with exclusive access to
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| 9 | * another CPU's data allowed but possibly subject to contention, and to
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| 10 | * provide very slow exclusive access to all per-CPU data.
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| 11 | * - Or to provide very fast and scalable read serialisation, and to provide
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| 12 | * very slow exclusive serialisation of data (not necessarily per-CPU data).
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| 13 | *
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| 14 | * Brlocks are also implemented as a short-hand notation for the latter use
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| 15 | * case.
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| 16 | *
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| 17 | * Copyright 2009, 2010, Nick Piggin, Novell Inc.
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| 18 |
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| 19 | #ifndef __LINUX_LGLOCK_H
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| 20 | #define __LINUX_LGLOCK_H
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| 21 |
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| 22 | #include <linux/spinlock.h>
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| 23 | #include <linux/lockdep.h>
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| 24 | #include <linux/percpu.h>
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| 25 | #include <linux/cpu.h>
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| 26 | #include <linux/notifier.h>
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| 27 |
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| 28 | #ifdef CONFIG_DEBUG_LOCK_ALLOC
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| 29 | #define LOCKDEP_INIT_MAP lockdep_init_map
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| 30 | #else
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| 31 | #define LOCKDEP_INIT_MAP(a, b, c, d)
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| 32 | #endif
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| 33 |
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| 34 | struct lglock {
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| 35 | arch_spinlock_t __percpu *lock;
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| 36 | #ifdef CONFIG_DEBUG_LOCK_ALLOC
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| 37 | struct lock_class_key lock_key;
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| 38 | struct lockdep_map lock_dep_map;
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| 39 | #endif
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| 40 | };
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| 41 |
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| 42 | #define DEFINE_LGLOCK(name) \
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| 43 | static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock) \
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| 44 | = __ARCH_SPIN_LOCK_UNLOCKED; \
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| 45 | struct lglock name = { .lock = &name ## _lock }
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| 46 |
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| 47 | #define DEFINE_STATIC_LGLOCK(name) \
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| 48 | static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock) \
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| 49 | = __ARCH_SPIN_LOCK_UNLOCKED; \
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| 50 | static struct lglock name = { .lock = &name ## _lock }
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| 51 |
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| 52 | void lg_lock_init(struct lglock *lg, char *name);
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| 53 | void lg_local_lock(struct lglock *lg);
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| 54 | void lg_local_unlock(struct lglock *lg);
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| 55 | void lg_local_lock_cpu(struct lglock *lg, int cpu);
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| 56 | void lg_local_unlock_cpu(struct lglock *lg, int cpu);
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| 57 | void lg_global_lock(struct lglock *lg);
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| 58 | void lg_global_unlock(struct lglock *lg);
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| 59 |
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| 60 | #endif
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