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Subject[PATCH 07/13] atomics/alpha: define atomic64_fetch_add_unless()
Date
As a step towards unifying the atomic/atomic64/atomic_long APIs, this
patch converts the arch/alpha implementation of atomic64_add_unless() into
an implementation of atomic64_fetch_add_unless().

A wrapper in <linux/atomic.h> will build atomic_add_unless() atop of
this, provided it is given a preprocessor definition.

No functional change is intended as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
---
arch/alpha/include/asm/atomic.h | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/arch/alpha/include/asm/atomic.h b/arch/alpha/include/asm/atomic.h
index 4a800a3424a3..dcb7bbeeae02 100644
--- a/arch/alpha/include/asm/atomic.h
+++ b/arch/alpha/include/asm/atomic.h
@@ -238,35 +238,36 @@ static __inline__ int atomic_fetch_add_unless(atomic_t *v, int a, int u)
#define atomic_fetch_add_unless atomic_fetch_add_unless

/**
- * atomic64_add_unless - add unless the number is a given value
+ * atomic64_fetch_add_unless - add unless the number is a given value
* @v: pointer of type atomic64_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 true iff @v was not @u.
+ * Returns the old value of @v.
*/
-static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u)
+static __inline__ int atomic64_fetch_add_unless(atomic64_t *v, long a, long u)
{
- long c, tmp;
+ long c, new, old;
smp_mb();
__asm__ __volatile__(
- "1: ldq_l %[tmp],%[mem]\n"
- " cmpeq %[tmp],%[u],%[c]\n"
- " addq %[tmp],%[a],%[tmp]\n"
+ "1: ldq_l %[old],%[mem]\n"
+ " cmpeq %[old],%[u],%[c]\n"
+ " addq %[old],%[a],%[new]\n"
" bne %[c],2f\n"
- " stq_c %[tmp],%[mem]\n"
- " beq %[tmp],3f\n"
+ " stq_c %[new],%[mem]\n"
+ " beq %[new],3f\n"
"2:\n"
".subsection 2\n"
"3: br 1b\n"
".previous"
- : [tmp] "=&r"(tmp), [c] "=&r"(c)
+ : [old] "=&r"(old), [new] "=&r"(new), [c] "=&r"(c)
: [mem] "m"(*v), [a] "rI"(a), [u] "rI"(u)
: "memory");
smp_mb();
- return !c;
+ return old;
}
+#define atomic64_fetch_add_unless atomic64_fetch_add_unless

/*
* atomic64_dec_if_positive - decrement by 1 if old value positive
--
2.11.0
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