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/metag/include/asm/atomic.h | 2 +
arch/metag/include/asm/atomic_lnkget.h | 36 +++++++++++++++++++++++++++++----
arch/metag/include/asm/atomic_lock1.h | 33 ++++++++++++++++++++++++++----
3 files changed, 63 insertions(+), 8 deletions(-)
--- a/arch/metag/include/asm/atomic.h
+++ b/arch/metag/include/asm/atomic.h
@@ -17,6 +17,8 @@
#include <asm/atomic_lnkget.h>
#endif
+#define atomic_fetch_or atomic_fetch_or
+
#define atomic_add_negative(a, v) (atomic_add_return((a), (v)) < 0)
#define atomic_dec_return(v) atomic_sub_return(1, (v))
--- a/arch/metag/include/asm/atomic_lnkget.h
+++ b/arch/metag/include/asm/atomic_lnkget.h
@@ -69,16 +69,44 @@ static inline int atomic_##op##_return(i
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)
\
+{ \
+ int result, temp; \
+ \
+ smp_mb(); \
+ \
+ asm volatile ( \
+ "1: LNKGETD %1, [%2]\n" \
+ " " #op " %0, %1, %3\n" \
+ " LNKSETD [%2], %0\n" \
+ " DEFR %0, TXSTAT\n" \
+ " ANDT %0, %0, #HI(0x3f000000)\n" \
+ " CMPT %0, #HI(0x02000000)\n" \
+ " BNZ 1b\n" \
+ : "=&d" (temp), "=&da" (result) \
+ : "da" (&v->counter), "bd" (i) \
+ : "cc"); \
+ \
+ smp_mb(); \
+ \
+ 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)
+
+ATOMIC_OPS(and)
+ATOMIC_OPS(or)
+ATOMIC_OPS(xor)
#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
--- a/arch/metag/include/asm/atomic_lock1.h
+++ b/arch/metag/include/asm/atomic_lock1.h
@@ -64,15 +64,40 @@ static inline int atomic_##op##_return(i
return result; \
}
-#define ATOMIC_OPS(op, c_op) ATOMIC_OP(op, c_op) ATOMIC_OP_RETURN(op, c_op)
+#define ATOMIC_FETCH_OP(op, c_op) \
+static inline int atomic_fetch_##op(int i, atomic_t *v)
\
+{ \
+ unsigned long result; \
+ unsigned long flags; \
+ \
+ __global_lock1(flags); \
+ result = v->counter; \
+ fence(); \
+ v->counter c_op i; \
+ __global_unlock1(flags); \
+ \
+ return result; \
+}
+
+#define ATOMIC_OPS(op, c_op) \
+ ATOMIC_OP(op, c_op) \
+ ATOMIC_OP_RETURN(op, c_op) \
+ ATOMIC_FETCH_OP(op, c_op)
ATOMIC_OPS(add, +=)
ATOMIC_OPS(sub, -=)
-ATOMIC_OP(and, &=)
-ATOMIC_OP(or, |=)
-ATOMIC_OP(xor, ^=)
#undef ATOMIC_OPS
+#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, ^=)
+
+#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
