Re: [RFC PATCH v1 1/5] locking/atomic: Implement atomic_fetch_and_or
From: Peter Zijlstra <peterz@infradead.org>
Date: 2021-07-28 13:17:18
Subsystem:
atomic infrastructure, the rest · Maintainers:
Will Deacon, Peter Zijlstra, Boqun Feng, Linus Torvalds
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.
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..995d80db8578
--- /dev/null
+++ b/scripts/atomic/fallbacks/andnot_or@@ -0,0 +1,23 @@ +local try_order=${order} + +if meta_has_ret "${meta}"; then + :; +else + 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