[PATCH net-next 2/3] mctp: serial: enforce fixed MTU
From: Jeremy Kerr <jk@codeconstruct.com.au>
Date: 2021-11-23 12:51:11
Subsystem:
management component transport protocol (mctp), networking drivers, the rest · Maintainers:
Jeremy Kerr, Matt Johnston, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The current serial driver requires a maximum MTU of 68, and it doesn't make sense to set a MTU below the MCTP-required baseline (of 68) either. This change sets the min_mtu & max_mtu of the mctp netdev, essentially disallowing changes. By using these instead of a ndo_change_mtu op, we get the netlink extacks reported too. Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au> --- drivers/net/mctp/mctp-serial.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/net/mctp/mctp-serial.c b/drivers/net/mctp/mctp-serial.c
index c958d773a82a..5687ad3220cd 100644
--- a/drivers/net/mctp/mctp-serial.c
+++ b/drivers/net/mctp/mctp-serial.c@@ -410,7 +410,14 @@ static const struct net_device_ops mctp_serial_netdev_ops = { static void mctp_serial_setup(struct net_device *ndev) { ndev->type = ARPHRD_MCTP; + + /* we limit at the fixed MTU, which is also the MCTP-standard + * baseline MTU, so is also our minimum + */ ndev->mtu = MCTP_SERIAL_MTU; + ndev->max_mtu = MCTP_SERIAL_MTU; + ndev->min_mtu = MCTP_SERIAL_MTU; + ndev->hard_header_len = 0; ndev->addr_len = 0; ndev->tx_queue_len = DEFAULT_TX_QUEUE_LEN;
--
2.33.0