Re: [RFC PATCH v1 1/5] locking/atomic: Implement atomic_fetch_and_or

[Peter Zijlstra <peterz@infradead.org>]

On Wed, Jul 28, 2021 at 03:16:54PM +0200, Peter Zijlstra wrote:
> On Wed, Jul 28, 2021 at 02:58:35PM +0200, Peter Zijlstra wrote:
> > The below isn't quite right, because it'll use try_cmpxchg() for
> > atomic_andnot_or(), which by being a void atomic should be _relaxed. I'm
> > not entirely sure how to make that happen in a hurry.
> > 
> > ---
> 
> This seems to do the trick.
> 

Mark suggested this, which is probably nicer still.

---
diff --git a/scripts/atomic/atomics.tbl b/scripts/atomic/atomics.tbl
index fbee2f6190d9..3aaa0caa6b2d 100755
--- a/scripts/atomic/atomics.tbl
+++ b/scripts/atomic/atomics.tbl
@@ -39,3 +39,4 @@ inc_not_zero		b	v
 inc_unless_negative	b	v
 dec_unless_positive	b	v
 dec_if_positive		i	v
+andnot_or		vF	v	i:m	i:o
diff --git a/scripts/atomic/fallbacks/andnot_or b/scripts/atomic/fallbacks/andnot_or
new file mode 100644
index 000000000000..0fb3a728c0ff
--- /dev/null
+++ b/scripts/atomic/fallbacks/andnot_or
@@ -0,0 +1,24 @@
+local try_order=${order}
+
+#
+# non-value returning atomics are implicity relaxed
+#
+if [ -z "${retstmt}" ]; then
+	try_order="_relaxed"
+fi
+
+cat <<EOF
+static __always_inline ${ret}
+arch_${atomic}_${pfx}andnot_or${sfx}${order}(${atomic}_t *v, ${int} m, ${int} o)
+{
+	${retstmt}({
+		${int} N, O = atomic_read(v);
+		do {
+			N = O;
+			N &= ~m;
+			N |= o;
+		} while (!arch_${atomic}_try_cmpxchg${try_order}(v, &O, N));
+		O;
+	});
+}
+EOF
diff --git a/scripts/atomic/fallbacks/fetch_andnot_or b/scripts/atomic/fallbacks/fetch_andnot_or
deleted file mode 100644
index e69de29bb2d1..000000000000