From: Ido Schimmel <idosch@nvidia.com>
Date: Tue, 4 Feb 2025 14:55:43 +0000 (+0200)
Subject: vxlan: Read jiffies once when updating FDB 'used' time
X-Git-Tag: v6.15-rc1~160^2~391^2~6
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1370c45d6e7e3cbac4b6dc71f54fd6e167848900;p=thirdparty%2Flinux.git

vxlan: Read jiffies once when updating FDB 'used' time

Avoid two volatile reads in the data path. Instead, read jiffies once
and only if an FDB entry was found.

Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20250204145549.1216254-3-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c
index 2f2c6606f7191..676a93ce3a197 100644
--- a/drivers/net/vxlan/vxlan_core.c
+++ b/drivers/net/vxlan/vxlan_core.c
@@ -434,8 +434,12 @@ static struct vxlan_fdb *vxlan_find_mac(struct vxlan_dev *vxlan,
 	struct vxlan_fdb *f;
 
 	f = __vxlan_find_mac(vxlan, mac, vni);
-	if (f && READ_ONCE(f->used) != jiffies)
-		WRITE_ONCE(f->used, jiffies);
+	if (f) {
+		unsigned long now = jiffies;
+
+		if (READ_ONCE(f->used) != now)
+			WRITE_ONCE(f->used, now);
+	}
 
 	return f;
 }