[PATCH net 3/7] net: ip6_gre: Split up ip6gre_tnl_link_config()

[Petr Machata]

The function ip6gre_tnl_link_config() is used for setting up
configuration of both ip6gretap and ip6erspan tunnels. Split the
function into the common part and the route-lookup part. The latter then
takes the calculated header length as an argument. This split will allow
the patches down the line to sneak in a custom header length computation
for the ERSPAN tunnel.

Signed-off-by: Petr Machata <pe...@mellanox.com>
---
 net/ipv6/ip6_gre.c | 38 ++++++++++++++++++++++++++------------
 1 file changed, 26 insertions(+), 12 deletions(-)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 53b1531..78ba6b9 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -1022,12 +1022,11 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff 
*skb,
        return NETDEV_TX_OK;
 }
 
-static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu)
+static void ip6gre_tnl_link_config_common(struct ip6_tnl *t)
 {
        struct net_device *dev = t->dev;
        struct __ip6_tnl_parm *p = &t->parms;
        struct flowi6 *fl6 = &t->fl.u.ip6;
-       int t_hlen;
 
        if (dev->type != ARPHRD_ETHER) {
                memcpy(dev->dev_addr, &p->laddr, sizeof(struct in6_addr));
@@ -1054,12 +1053,13 @@ static void ip6gre_tnl_link_config(struct ip6_tnl *t, 
int set_mtu)
                dev->flags |= IFF_POINTOPOINT;
        else
                dev->flags &= ~IFF_POINTOPOINT;
+}
 
-       t->tun_hlen = gre_calc_hlen(t->parms.o_flags);
-
-       t->hlen = t->encap_hlen + t->tun_hlen;
-
-       t_hlen = t->hlen + sizeof(struct ipv6hdr);
+static void ip6gre_tnl_link_config_route(struct ip6_tnl *t, int set_mtu,
+                                        int t_hlen)
+{
+       const struct __ip6_tnl_parm *p = &t->parms;
+       struct net_device *dev = t->dev;
 
        if (p->flags & IP6_TNL_F_CAP_XMIT) {
                int strict = (ipv6_addr_type(&p->raddr) &
@@ -1091,6 +1091,24 @@ static void ip6gre_tnl_link_config(struct ip6_tnl *t, 
int set_mtu)
        }
 }
 
+static int ip6gre_calc_hlen(struct ip6_tnl *tunnel)
+{
+       int t_hlen;
+
+       tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);
+       tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen;
+
+       t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);
+       tunnel->dev->hard_header_len = LL_MAX_HEADER + t_hlen;
+       return t_hlen;
+}
+
+static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu)
+{
+       ip6gre_tnl_link_config_common(t);
+       ip6gre_tnl_link_config_route(t, set_mtu, ip6gre_calc_hlen(t));
+}
+
 static int ip6gre_tnl_change(struct ip6_tnl *t,
        const struct __ip6_tnl_parm *p, int set_mtu)
 {
@@ -1384,11 +1402,7 @@ static int ip6gre_tunnel_init_common(struct net_device 
*dev)
                return ret;
        }
 
-       tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);
-       tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen;
-       t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);
-
-       dev->hard_header_len = LL_MAX_HEADER + t_hlen;
+       t_hlen = ip6gre_calc_hlen(tunnel);
        dev->mtu = ETH_DATA_LEN - t_hlen;
        if (dev->type == ARPHRD_ETHER)
                dev->mtu -= ETH_HLEN;
-- 
2.4.11