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>
diff --git a/arch/sparc/lib/atomic32.c b/arch/sparc/lib/atomic32.c
index b9d63c0..2c37332 100644
--- a/arch/sparc/lib/atomic32.c
+++ b/arch/sparc/lib/atomic32.c
@@ -27,6 +27,21 @@
#endif /* SMP */
+#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; \
+ v->counter c_op i; \
+ \
+ spin_unlock_irqrestore(ATOMIC_HASH(v), flags); \
+ return ret; \
+} \
+EXPORT_SYMBOL(atomic_fetch_##op);
+
#define ATOMIC_OP_RETURN(op, c_op) \
int atomic_##op##_return(int i, atomic_t *v) \
{ \
@@ -41,25 +56,15 @@
} \
EXPORT_SYMBOL(atomic_##op##_return);
-#define ATOMIC_OP(op, c_op) \
-void atomic_##op(int i, atomic_t *v) \
-{ \
- unsigned long flags; \
- spin_lock_irqsave(ATOMIC_HASH(v), flags); \
- \
- v->counter c_op i; \
- \
- spin_unlock_irqrestore(ATOMIC_HASH(v), flags); \
-} \
-EXPORT_SYMBOL(atomic_##op);
-
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)
{