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Subject[PATCH 09/13] atomics/arm: define atomic64_fetch_add_unless()
Date
As a step towards unifying the atomic/atomic64/atomic_long APIs, this
patch converts the arch/arm 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: Russell King <linux@armlinux.org.uk>
---
arch/arm/include/asm/atomic.h | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h
index 74460aa00fa0..852e1fee72b0 100644
--- a/arch/arm/include/asm/atomic.h
+++ b/arch/arm/include/asm/atomic.h
@@ -486,11 +486,11 @@ static inline long long atomic64_dec_if_positive(atomic64_t *v)
return result;
}

-static inline int atomic64_add_unless(atomic64_t *v, long long a, long long u)
+static inline long long atomic64_fetch_add_unless(atomic64_t *v, long long a,
+ long long u)
{
- long long val;
+ long long oldval, newval;
unsigned long tmp;
- int ret = 1;

smp_mb();
prefetchw(&v->counter);
@@ -499,23 +499,23 @@ static inline int atomic64_add_unless(atomic64_t *v, long long a, long long u)
"1: ldrexd %0, %H0, [%4]\n"
" teq %0, %5\n"
" teqeq %H0, %H5\n"
-" moveq %1, #0\n"
" beq 2f\n"
-" adds %Q0, %Q0, %Q6\n"
-" adc %R0, %R0, %R6\n"
-" strexd %2, %0, %H0, [%4]\n"
+" adds %Q1, %Q0, %Q6\n"
+" adc %R1, %R0, %R6\n"
+" strexd %2, %1, %H1, [%4]\n"
" teq %2, #0\n"
" bne 1b\n"
"2:"
- : "=&r" (val), "+r" (ret), "=&r" (tmp), "+Qo" (v->counter)
+ : "=&r" (oldval), "=&r" (newval), "=&r" (tmp), "+Qo" (v->counter)
: "r" (&v->counter), "r" (u), "r" (a)
: "cc");

- if (ret)
+ if (oldval != u)
smp_mb();

- return ret;
+ return oldval;
}
+#define atomic64_fetch_add_unless atomic64_fetch_add_unless

#define atomic64_add_negative(a, v) (atomic64_add_return((a), (v)) < 0)
#define atomic64_inc(v) atomic64_add(1LL, (v))
--
2.11.0
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