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Subject[PATCH 08/13] atomics/arc: define atomic64_fetch_add_unless()
Date
As a step towards unifying the atomic/atomic64/atomic_long APIs, this
patch converts the arch/arc 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: Vineet Gupta <vgupta@synopsys.com>
---
arch/arc/include/asm/atomic.h | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/arch/arc/include/asm/atomic.h b/arch/arc/include/asm/atomic.h
index 60da80481c5d..335ddc21ed03 100644
--- a/arch/arc/include/asm/atomic.h
+++ b/arch/arc/include/asm/atomic.h
@@ -531,41 +531,40 @@ static inline long long atomic64_dec_if_positive(atomic64_t *v)
}

/**
- * 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.
*
- * if (v != u) { v += a; ret = 1} else {ret = 0}
- * Returns 1 iff @v was not @u (i.e. if add actually happened)
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns the old value of @v
*/
-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;
- int op_done;
+ long long old, temp;

smp_mb();

__asm__ __volatile__(
"1: llockd %0, [%2] \n"
- " mov %1, 1 \n"
" brne %L0, %L4, 2f # continue to add since v != u \n"
" breq.d %H0, %H4, 3f # return since v == u \n"
- " mov %1, 0 \n"
"2: \n"
- " add.f %L0, %L0, %L3 \n"
- " adc %H0, %H0, %H3 \n"
- " scondd %0, [%2] \n"
+ " add.f %L1, %L0, %L3 \n"
+ " adc %H1, %H0, %H3 \n"
+ " scondd %1, [%2] \n"
" bnz 1b \n"
"3: \n"
- : "=&r"(val), "=&r" (op_done)
+ : "=&r"(old), "=&r" (temp)
: "r"(&v->counter), "r"(a), "r"(u)
: "cc"); /* memory clobber comes from smp_mb() */

smp_mb();

- return op_done;
+ return old;
}
+#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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