[PATCH 3.18 009/120] neighbour: confirm neigh entries when ARP packet is received

Greg Kroah-Hartman
2018-10-11T15:36:50Z

From: Vasily Khoruzhick <vasilykh@arista.com>

[ Upstream commit f0e0d04413fcce9bc76388839099aee93cd0d33b ]

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 sense to confirm it when ARP packet is received.

Fixes: 77d7123342dc ("neighbour: update neigh timestamps iff update is effective")
Signed-off-by: Vasily Khoruzhick <vasilykh@arista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/neighbour.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1147,6 +1147,12 @@ int neigh_update(struct neighbour *neigh
lladdr = neigh->ha;
}

+ /* Update confirmed timestamp for neighbour entry after we
+ * received ARP packet even if it doesn't change IP to MAC binding.
+ */
+ 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.
*/
@@ -1170,15 +1176,12 @@ int neigh_update(struct neighbour *neigh
}
}

- /* Update timestamps only once we know we will make a change to the
+ /* Update timestamp only once we know we will make a change to the
* 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);