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@xxxxxxxxxxxxx>
---
arch/m32r/include/asm/atomic.h | 38 ++++++++++++++++++++++++++++++++++----
1 file changed, 34 insertions(+), 4 deletions(-)
--- a/arch/m32r/include/asm/atomic.h
+++ b/arch/m32r/include/asm/atomic.h
@@ -89,16 +89,46 @@ static __inline__ int atomic_##op##_retu
return result; \
}
-#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
+#define ATOMIC_FETCH_OP(op) \
+static __inline__ int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ unsigned long flags; \
+ int result, val; \
+ \
+ local_irq_save(flags); \
+ __asm__ __volatile__ ( \
+ "# atomic_fetch_" #op " \n\t" \
+ DCACHE_CLEAR("%0", "r4", "%2") \
+ M32R_LOCK" %1, @%2; \n\t" \
+ "mv %0, %1 \n\t" \
+ #op " %1, %3; \n\t" \
+ M32R_UNLOCK" %1, @%2; \n\t" \
+ : "=&r" (result), "=&r" (val) \
+ : "r" (&v->counter), "r" (i) \
+ : "memory" \
+ __ATOMIC_CLOBBER \
+ ); \
+ local_irq_restore(flags); \
+ \
+ return result; \
+}
+
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op) ATOMIC_FETCH_OP(op)
ATOMIC_OPS(add)
ATOMIC_OPS(sub)
-ATOMIC_OP(and)
-ATOMIC_OP(or)
-ATOMIC_OP(xor)
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op)
+
+#define atomic_fetch_or atomic_fetch_or
+
+ATOMIC_OPS(and)
+ATOMIC_OPS(or)
+ATOMIC_OPS(xor)
#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
--
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