Re: [PATCH net-next v1 2/3] gtp: Support creating flow-based gtp net_device

Hi Harald,

On 7/13/17, 12:35 AM, "Harald Welte" [off-list ref] wrote:

quoted

+static int gtp_dev_open(struct net_device *dev)
+{
+	struct gtp_dev *gtp = netdev_priv(dev);
+	struct net *net = gtp->net;
+	struct socket *sock1u;
+	struct socket *sock0;
+	struct udp_tunnel_sock_cfg tunnel_cfg;
+	struct udp_port_cfg udp_conf;
+	int err;
+
+	memset(&udp_conf, 0, sizeof(udp_conf));
+
+	udp_conf.family = AF_INET;
+	udp_conf.local_ip.s_addr = htonl(INADDR_ANY);
+	udp_conf.local_udp_port = htons(GTP1U_PORT);
+
+	err = udp_sock_create(gtp->net, &udp_conf, &sock1u);
+	if (err < 0)
+		return err;
+
+	udp_conf.local_udp_port = htons(GTP0_PORT);
+	err = udp_sock_create(gtp->net, &udp_conf, &sock0);
+	if (err < 0)
+		return err;

you're unconditionally binding to both GTP0 and GTP1 UDP ports.  This is
done selectively based on netlink attributes in the existing "normal"
non-OVS kernel code, i.e. the control is left to the user.

Is this function is only called/used in the context of OVS?  If so,
since you explicitly implement only GTPv1, why bind to GTPv0 port?

I had doubts on how this flow-based GTPv1 code path should fit in, which is why
the GTPv0 and the GTPv1 code pieces are mixed in my changes. Should I
explicitly claim that the flow-based change is for GTPv1 only?

quoted

+	setup_udp_tunnel_sock(net, sock1u, &tunnel_cfg);

even here, you're only setting up the v1 and not v0.

same reason as above.

quoted

+	/* Assume largest header, ie. GTPv0. */
+	dev->needed_headroom	= LL_MAX_HEADER +
+		sizeof(struct iphdr) +
+		sizeof(struct udphdr) +
+		sizeof(struct gtp0_header);

... and here you're using headroom for a GTPv0 header, despite (I think)
only supporting GTPv1 from this configuration?

Yes, only GTPv1 is supported.

quoted

+	err = gtp_hashtable_new(gtp, GTP_PDP_HASHSIZE); // JO: when to free??

I think that question about when to free needs to be resolved before any
merge.  Did you check that it persists even after the device is
closed/removed?

I didn't investigate it. What do you mean by persist?

Thanks
-Jiannan