From 3a1adb23a52c920304239efff377d3bc967febc2 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Mon, 18 Apr 2016 01:16:04 +0200
Subject: locking/atomic, arch/sparc: Implement
 atomic{,64}_fetch_{add,sub,and,or,xor}()

Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.

This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: James Y Knight <jyknight@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/sparc/lib/atomic32.c | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

(limited to 'arch/sparc/lib/atomic32.c')

diff --git a/arch/sparc/lib/atomic32.c b/arch/sparc/lib/atomic32.c
index b9d63c0a7aab..2c373329d5cb 100644
--- a/arch/sparc/lib/atomic32.c
+++ b/arch/sparc/lib/atomic32.c
@@ -27,39 +27,44 @@ static DEFINE_SPINLOCK(dummy);
 
 #endif /* SMP */
 
-#define ATOMIC_OP_RETURN(op, c_op)					\
-int atomic_##op##_return(int i, atomic_t *v)				\
+#define ATOMIC_FETCH_OP(op, c_op)					\
+int atomic_fetch_##op(int i, atomic_t *v)				\
 {									\
 	int ret;							\
 	unsigned long flags;						\
 	spin_lock_irqsave(ATOMIC_HASH(v), flags);			\
 									\
-	ret = (v->counter c_op i);					\
+	ret = v->counter;						\
+	v->counter c_op i;						\
 									\
 	spin_unlock_irqrestore(ATOMIC_HASH(v), flags);			\
 	return ret;							\
 }									\
-EXPORT_SYMBOL(atomic_##op##_return);
+EXPORT_SYMBOL(atomic_fetch_##op);
 
-#define ATOMIC_OP(op, c_op)						\
-void atomic_##op(int i, atomic_t *v)					\
+#define ATOMIC_OP_RETURN(op, c_op)					\
+int atomic_##op##_return(int i, atomic_t *v)				\
 {									\
+	int ret;							\
 	unsigned long flags;						\
 	spin_lock_irqsave(ATOMIC_HASH(v), flags);			\
 									\
-	v->counter c_op i;						\
+	ret = (v->counter c_op i);					\
 									\
 	spin_unlock_irqrestore(ATOMIC_HASH(v), flags);			\
+	return ret;							\
 }									\
-EXPORT_SYMBOL(atomic_##op);
+EXPORT_SYMBOL(atomic_##op##_return);
 
 ATOMIC_OP_RETURN(add, +=)
-ATOMIC_OP(and, &=)
-ATOMIC_OP(or, |=)
-ATOMIC_OP(xor, ^=)
 
+ATOMIC_FETCH_OP(add, +=)
+ATOMIC_FETCH_OP(and, &=)
+ATOMIC_FETCH_OP(or, |=)
+ATOMIC_FETCH_OP(xor, ^=)
+
+#undef ATOMIC_FETCH_OP
 #undef ATOMIC_OP_RETURN
-#undef ATOMIC_OP
 
 int atomic_xchg(atomic_t *v, int new)
 {
-- 
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