forked from luck/tmp_suning_uos_patched
eea62f831b
lglocks and brlocks are currently generated with some complicated macros in lglock.h. But there's no reason to not just use common utility functions and put all the data into a common data structure. Since there are at least two users it makes sense to share this code in a library. This is also easier maintainable than a macro forest. This will also make it later possible to dynamically allocate lglocks and also use them in modules (this would both still need some additional, but now straightforward, code) [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by: Andi Kleen <ak@linux.intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
74 lines
2.3 KiB
C
74 lines
2.3 KiB
C
/*
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* Specialised local-global spinlock. Can only be declared as global variables
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* to avoid overhead and keep things simple (and we don't want to start using
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* these inside dynamically allocated structures).
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*
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* "local/global locks" (lglocks) can be used to:
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*
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* - Provide fast exclusive access to per-CPU data, with exclusive access to
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* another CPU's data allowed but possibly subject to contention, and to
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* provide very slow exclusive access to all per-CPU data.
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* - Or to provide very fast and scalable read serialisation, and to provide
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* very slow exclusive serialisation of data (not necessarily per-CPU data).
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*
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* Brlocks are also implemented as a short-hand notation for the latter use
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* case.
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*
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* Copyright 2009, 2010, Nick Piggin, Novell Inc.
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*/
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#ifndef __LINUX_LGLOCK_H
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#define __LINUX_LGLOCK_H
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#include <linux/spinlock.h>
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#include <linux/lockdep.h>
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#include <linux/percpu.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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/* can make br locks by using local lock for read side, global lock for write */
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#define br_lock_init(name) lg_lock_init(name, #name)
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#define br_read_lock(name) lg_local_lock(name)
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#define br_read_unlock(name) lg_local_unlock(name)
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#define br_write_lock(name) lg_global_lock(name)
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#define br_write_unlock(name) lg_global_unlock(name)
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#define DEFINE_BRLOCK(name) DEFINE_LGLOCK(name)
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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#define LOCKDEP_INIT_MAP lockdep_init_map
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#define DEFINE_LGLOCK_LOCKDEP(name) \
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struct lock_class_key name##_lock_key; \
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struct lockdep_map name##_lock_dep_map; \
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EXPORT_SYMBOL(name##_lock_dep_map)
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#else
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#define LOCKDEP_INIT_MAP(a, b, c, d)
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#define DEFINE_LGLOCK_LOCKDEP(name)
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#endif
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struct lglock {
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arch_spinlock_t __percpu *lock;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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struct lock_class_key lock_key;
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struct lockdep_map lock_dep_map;
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#endif
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};
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#define DEFINE_LGLOCK(name) \
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DEFINE_LGLOCK_LOCKDEP(name); \
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DEFINE_PER_CPU(arch_spinlock_t, name ## _lock) \
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= __ARCH_SPIN_LOCK_UNLOCKED; \
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struct lglock name = { .lock = &name ## _lock }
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void lg_lock_init(struct lglock *lg, char *name);
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void lg_local_lock(struct lglock *lg);
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void lg_local_unlock(struct lglock *lg);
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void lg_local_lock_cpu(struct lglock *lg, int cpu);
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void lg_local_unlock_cpu(struct lglock *lg, int cpu);
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void lg_global_lock(struct lglock *lg);
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void lg_global_unlock(struct lglock *lg);
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#endif
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