netdev - [PATCH] neighbour: confirm neigh entries when ARP packet is received

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Message-Id: <20180829024825.3808-1-vasilykh@arista.com>
Date:   Tue, 28 Aug 2018 19:48:25 -0700
From:   Vasily Khoruzhick <vasilykh@...sta.com>
To:     Ihar Hrachyshka <ihrachys@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Jim Westfall <jwestfall@...realistic.net>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Vasily Khoruzhick <anarsoul@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Wolfgang Bumiller <w.bumiller@...xmox.com>,
        Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org
Cc:     Vasily Khoruzhick <vasilykh@...sta.com>
Subject: [PATCH] neighbour: confirm neigh entries when ARP packet is received

Update 'confirmed' timestamp when ARP packet is received. It shouldn't
affect locktime logic and anyway entry can be confirmed by any higher-layer
protocol. Thus it makes no sense not to confirm it when ARP packet is
received.

Fixes: 77d7123342 ("neighbour: update neigh timestamps iff update is
effective")

Signed-off-by: Vasily Khoruzhick <vasilykh@...sta.com>
---
 net/core/neighbour.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index aa19d86937af..901418ef70ea 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1180,6 +1180,9 @@ int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new,
 		lladdr = neigh->ha;
 	}
 
+	if (new & NUD_CONNECTED)
+		neigh->confirmed = jiffies;
+
 	/* If entry was valid and address is not changed,
 	   do not change entry state, if new one is STALE.
 	 */
@@ -1205,11 +1208,8 @@ int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new,
 	 * neighbour entry. Otherwise we risk to move the locktime window with
 	 * noop updates and ignore relevant ARP updates.
 	 */
-	if (new != old || lladdr != neigh->ha) {
-		if (new & NUD_CONNECTED)
-			neigh->confirmed = jiffies;
+	if (new != old || lladdr != neigh->ha)
 		neigh->updated = jiffies;
-	}
 
 	if (new != old) {
 		neigh_del_timer(neigh);
-- 
2.18.0