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) <pet...@infradead.org>
---
arch/h8300/include/asm/atomic.h | 31 +++++++++++++++++++++++++------
1 file changed, 25 insertions(+), 6 deletions(-)
--- a/arch/h8300/include/asm/atomic.h
+++ b/arch/h8300/include/asm/atomic.h
@@ -28,6 +28,19 @@ static inline int atomic_##op##_return(i
return ret; \
}
+#define ATOMIC_FETCH_OP(op, c_op) \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ h8300flags flags; \
+ int ret; \
+ \
+ flags = arch_local_irq_save(); \
+ ret = v->counter; \
+ v->counter c_op i; \
+ arch_local_irq_restore(flags); \
+ return ret; \
+}
+
#define ATOMIC_OP(op, c_op) \
static inline void atomic_##op(int i, atomic_t *v) \
{ \
@@ -41,17 +54,23 @@ static inline void atomic_##op(int i, at
ATOMIC_OP_RETURN(add, +=)
ATOMIC_OP_RETURN(sub, -=)
-ATOMIC_OP(and, &=)
-ATOMIC_OP(or, |=)
-ATOMIC_OP(xor, ^=)
+#define atomic_fetch_or atomic_fetch_or
+#define ATOMIC_OPS(op, c_op) \
+ ATOMIC_OP(op, c_op) \
+ ATOMIC_FETCH_OP(op, c_op)
+
+ATOMIC_OPS(and, &=)
+ATOMIC_OPS(or, |=)
+ATOMIC_OPS(xor, ^=)
+ATOMIC_OPS(add, +=)
+ATOMIC_OPS(sub, -=)
+
+#undef ATOMIC_OPS
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
-#define atomic_add(i, v) (void)atomic_add_return(i, v)
#define atomic_add_negative(a, v) (atomic_add_return((a), (v)) < 0)
-
-#define atomic_sub(i, v) (void)atomic_sub_return(i, v)
#define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
#define atomic_inc_return(v) atomic_add_return(1, v)
