linux/include/asm-generic/atomic.h
Mike Frysinger 7505cb60c2 asm-generic/atomic.h: allow SMP peeps to leverage this
Only a few core funcs need to be implemented for SMP systems, so allow the
arches to override them while getting the rest for free.

At least, this is enough to allow the Blackfin SMP port to use things.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Arun Sharma <asharma@fb.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-26 16:49:48 -07:00

197 lines
4.8 KiB
C

/*
* Generic C implementation of atomic counter operations. Usable on
* UP systems only. Do not include in machine independent code.
*
* Originally implemented for MN10300.
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#ifndef __ASM_GENERIC_ATOMIC_H
#define __ASM_GENERIC_ATOMIC_H
#ifdef CONFIG_SMP
/* Force people to define core atomics */
# if !defined(atomic_add_return) || !defined(atomic_sub_return) || \
!defined(atomic_clear_mask) || !defined(atomic_set_mask)
# error "SMP requires a little arch-specific magic"
# endif
#endif
/*
* Atomic operations that C can't guarantee us. Useful for
* resource counting etc..
*/
#define ATOMIC_INIT(i) { (i) }
#ifdef __KERNEL__
/**
* atomic_read - read atomic variable
* @v: pointer of type atomic_t
*
* Atomically reads the value of @v.
*/
#ifndef atomic_read
#define atomic_read(v) (*(volatile int *)&(v)->counter)
#endif
/**
* atomic_set - set atomic variable
* @v: pointer of type atomic_t
* @i: required value
*
* Atomically sets the value of @v to @i.
*/
#define atomic_set(v, i) (((v)->counter) = (i))
#include <linux/irqflags.h>
#include <asm/system.h>
/**
* atomic_add_return - add integer to atomic variable
* @i: integer value to add
* @v: pointer of type atomic_t
*
* Atomically adds @i to @v and returns the result
*/
#ifndef atomic_add_return
static inline int atomic_add_return(int i, atomic_t *v)
{
unsigned long flags;
int temp;
raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */
temp = v->counter;
temp += i;
v->counter = temp;
raw_local_irq_restore(flags);
return temp;
}
#endif
/**
* atomic_sub_return - subtract integer from atomic variable
* @i: integer value to subtract
* @v: pointer of type atomic_t
*
* Atomically subtracts @i from @v and returns the result
*/
#ifndef atomic_sub_return
static inline int atomic_sub_return(int i, atomic_t *v)
{
unsigned long flags;
int temp;
raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */
temp = v->counter;
temp -= i;
v->counter = temp;
raw_local_irq_restore(flags);
return temp;
}
#endif
static inline int atomic_add_negative(int i, atomic_t *v)
{
return atomic_add_return(i, v) < 0;
}
static inline void atomic_add(int i, atomic_t *v)
{
atomic_add_return(i, v);
}
static inline void atomic_sub(int i, atomic_t *v)
{
atomic_sub_return(i, v);
}
static inline void atomic_inc(atomic_t *v)
{
atomic_add_return(1, v);
}
static inline void atomic_dec(atomic_t *v)
{
atomic_sub_return(1, v);
}
#define atomic_dec_return(v) atomic_sub_return(1, (v))
#define atomic_inc_return(v) atomic_add_return(1, (v))
#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
#define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
#define cmpxchg_local(ptr, o, n) \
((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
(unsigned long)(n), sizeof(*(ptr))))
#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
static inline int __atomic_add_unless(atomic_t *v, int a, int u)
{
int c, old;
c = atomic_read(v);
while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
c = old;
return c;
}
/**
* atomic_clear_mask - Atomically clear bits in atomic variable
* @mask: Mask of the bits to be cleared
* @v: pointer of type atomic_t
*
* Atomically clears the bits set in @mask from @v
*/
#ifndef atomic_clear_mask
static inline void atomic_clear_mask(unsigned long mask, atomic_t *v)
{
unsigned long flags;
mask = ~mask;
raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
v->counter &= mask;
raw_local_irq_restore(flags);
}
#endif
/**
* atomic_set_mask - Atomically set bits in atomic variable
* @mask: Mask of the bits to be set
* @v: pointer of type atomic_t
*
* Atomically sets the bits set in @mask in @v
*/
#ifndef atomic_set_mask
static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
{
unsigned long flags;
raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
v->counter |= mask;
raw_local_irq_restore(flags);
}
#endif
/* Assume that atomic operations are already serializing */
#define smp_mb__before_atomic_dec() barrier()
#define smp_mb__after_atomic_dec() barrier()
#define smp_mb__before_atomic_inc() barrier()
#define smp_mb__after_atomic_inc() barrier()
#endif /* __KERNEL__ */
#endif /* __ASM_GENERIC_ATOMIC_H */