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/powerpc/include/asm/atomic.h | 83 +++++++++++++++++++++++++++++++++-----
1 file changed, 74 insertions(+), 9 deletions(-)
--- a/arch/powerpc/include/asm/atomic.h
+++ b/arch/powerpc/include/asm/atomic.h
@@ -78,21 +78,53 @@ static inline int atomic_##op##_return_r
return t; \
}
+#define ATOMIC_FETCH_OP_RELAXED(op, asm_op) \
+static inline int atomic_fetch_##op##_relaxed(int a, atomic_t *v) \
+{ \
+ int res, t; \
+ \
+ __asm__ __volatile__( \
+"1: lwarx %0,0,%4 # atomic_fetch_" #op "_relaxed\n" \
+ #asm_op " %1,%3,%0\n" \
+ PPC405_ERR77(0, %4) \
+" stwcx. %1,0,%4\n" \
+" bne- 1b\n" \
+ : "=&r" (res), "=&r" (t), "+m" (v->counter) \
+ : "r" (a), "r" (&v->counter) \
+ : "cc"); \
+ \
+ return res; \
+}
+
#define ATOMIC_OPS(op, asm_op) \
ATOMIC_OP(op, asm_op) \
- ATOMIC_OP_RETURN_RELAXED(op, asm_op)
+ ATOMIC_OP_RETURN_RELAXED(op, asm_op) \
+ ATOMIC_FETCH_OP_RELAXED(op, asm_op)
ATOMIC_OPS(add, add)
ATOMIC_OPS(sub, subf)
-ATOMIC_OP(and, and)
-ATOMIC_OP(or, or)
-ATOMIC_OP(xor, xor)
-
#define atomic_add_return_relaxed atomic_add_return_relaxed
#define atomic_sub_return_relaxed atomic_sub_return_relaxed
+#define atomic_fetch_add_relaxed atomic_fetch_add_relaxed
+#define atomic_fetch_sub_relaxed atomic_fetch_sub_relaxed
+
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(op, asm_op) \
+ ATOMIC_OP(op, asm_op) \
+ ATOMIC_FETCH_OP_RELAXED(op, asm_op)
+
+ATOMIC_OPS(and, and)
+ATOMIC_OPS(or, or)
+ATOMIC_OPS(xor, xor)
+
+#define atomic_fetch_and_relaxed atomic_fetch_and_relaxed
+#define atomic_fetch_or_relaxed atomic_fetch_or_relaxed
+#define atomic_fetch_xor_relaxed atomic_fetch_xor_relaxed
+
#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP_RELAXED
#undef ATOMIC_OP_RETURN_RELAXED
#undef ATOMIC_OP
@@ -329,20 +361,53 @@ atomic64_##op##_return_relaxed(long a, a
return t; \
}
+#define ATOMIC64_FETCH_OP_RELAXED(op, asm_op) \
+static inline long \
+atomic64_fetch_##op##_relaxed(long a, atomic64_t *v) \
+{ \
+ long res, t; \
+ \
+ __asm__ __volatile__( \
+"1: ldarx %0,0,%4 # atomic64_fetch_" #op "_relaxed\n" \
+ #asm_op " %1,%3,%0\n" \
+" stdcx. %1,0,%4\n" \
+" bne- 1b\n" \
+ : "=&r" (res), "=&r" (t), "+m" (v->counter) \
+ : "r" (a), "r" (&v->counter) \
+ : "cc"); \
+ \
+ return t; \
+}
+
#define ATOMIC64_OPS(op, asm_op) \
ATOMIC64_OP(op, asm_op) \
- ATOMIC64_OP_RETURN_RELAXED(op, asm_op)
+ ATOMIC64_OP_RETURN_RELAXED(op, asm_op) \
+ ATOMIC64_FETCH_OP_RELAXED(op, asm_op)
ATOMIC64_OPS(add, add)
ATOMIC64_OPS(sub, subf)
-ATOMIC64_OP(and, and)
-ATOMIC64_OP(or, or)
-ATOMIC64_OP(xor, xor)
#define atomic64_add_return_relaxed atomic64_add_return_relaxed
#define atomic64_sub_return_relaxed atomic64_sub_return_relaxed
+#define atomic64_fetch_add_relaxed atomic64_fetch_add_relaxed
+#define atomic64_fetch_sub_relaxed atomic64_fetch_sub_relaxed
+
+#undef ATOMIC64_OPS
+#define ATOMIC64_OPS(op, asm_op) \
+ ATOMIC64_OP(op, asm_op) \
+ ATOMIC64_FETCH_OP_RELAXED(op, asm_op)
+
+ATOMIC64_OPS(and, and)
+ATOMIC64_OPS(or, or)
+ATOMIC64_OPS(xor, xor)
+
+#define atomic64_fetch_and_relaxed atomic64_fetch_and_relaxed
+#define atomic64_fetch_or_relaxed atomic64_fetch_or_relaxed
+#define atomic64_fetch_xor_relaxed atomic64_fetch_xor_relaxed
+
#undef ATOPIC64_OPS
+#undef ATOMIC64_FETCH_OP_RELAXED
#undef ATOMIC64_OP_RETURN_RELAXED
#undef ATOMIC64_OP
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