virtio_net: validate ethtool port setting and explain the user validation

We should validate the port setting that we got from the user and check
if it's what we've set it to (PORT_OTHER), also add explanation that
ignoring advertising is good as long as we don't have autonegotiation.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index c9fd52a8e6ec5f05d3459ba26994a449df764ec6..fb0eae42bf398c977fec8f2c4f59d74e5d9b4394 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1386,11 +1386,13 @@ static bool virtnet_validate_ethtool_cmd(const struct ethtool_cmd *cmd)
        struct ethtool_cmd diff1 = *cmd;
        struct ethtool_cmd diff2 = {};
 
-       /* advertising and cmd are usually set, ignore port because we set it */
+       /* cmd is always set so we need to clear it, validate the port type
+        * and also without autonegotiation we can ignore advertising
+        */
        ethtool_cmd_speed_set(&diff1, 0);
+       diff2.port = PORT_OTHER;
        diff1.advertising = 0;
        diff1.duplex = 0;
-       diff1.port = 0;
        diff1.cmd = 0;
 
        return !memcmp(&diff1, &diff2, sizeof(diff1));