linux/arch/sh/include/asm/atomic.h
Pranith Kumar 2291059c85 locking,arch: Use ACCESS_ONCE() instead of cast to volatile in atomic_read()
Use the much more reader friendly ACCESS_ONCE() instead of the cast to volatile.
This is purely a stylistic change.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
Link: http://lkml.kernel.org/r/1411482607-20948-1-git-send-email-bobby.prani@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-03 06:06:23 +02:00

67 lines
1.6 KiB
C

#ifndef __ASM_SH_ATOMIC_H
#define __ASM_SH_ATOMIC_H
/*
* Atomic operations that C can't guarantee us. Useful for
* resource counting etc..
*
*/
#include <linux/compiler.h>
#include <linux/types.h>
#include <asm/cmpxchg.h>
#include <asm/barrier.h>
#define ATOMIC_INIT(i) { (i) }
#define atomic_read(v) ACCESS_ONCE((v)->counter)
#define atomic_set(v,i) ((v)->counter = (i))
#if defined(CONFIG_GUSA_RB)
#include <asm/atomic-grb.h>
#elif defined(CONFIG_CPU_SH4A)
#include <asm/atomic-llsc.h>
#else
#include <asm/atomic-irq.h>
#endif
#define atomic_add_negative(a, v) (atomic_add_return((a), (v)) < 0)
#define atomic_dec_return(v) atomic_sub_return(1, (v))
#define atomic_inc_return(v) atomic_add_return(1, (v))
#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
#define atomic_sub_and_test(i,v) (atomic_sub_return((i), (v)) == 0)
#define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0)
#define atomic_inc(v) atomic_add(1, (v))
#define atomic_dec(v) atomic_sub(1, (v))
#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
#define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
/**
* __atomic_add_unless - add unless the number is a given value
* @v: pointer of type atomic_t
* @a: the amount to add to v...
* @u: ...unless v is equal to u.
*
* Atomically adds @a to @v, so long as it was not @u.
* Returns the old value of @v.
*/
static inline int __atomic_add_unless(atomic_t *v, int a, int u)
{
int c, old;
c = atomic_read(v);
for (;;) {
if (unlikely(c == (u)))
break;
old = atomic_cmpxchg((v), c, c + (a));
if (likely(old == c))
break;
c = old;
}
return c;
}
#endif /* __ASM_SH_ATOMIC_H */