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Date: Thu, 17 May 2018 12:52:39 -0700
From: William Tu <u9012063@...il.com>
To: Petr Machata <petrm@...lanox.com>
Cc: Linux Kernel Network Developers <netdev@...r.kernel.org>,
David Miller <davem@...emloft.net>,
Alexey Kuznetsov <kuznet@....inr.ac.ru>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
Dmitry Kozlov <xeb@...l.ru>
Subject: Re: [PATCH net 7/7] net: ip6_gre: Fix ip6erspan hlen calculation
On Thu, May 17, 2018 at 7:36 AM, Petr Machata <petrm@...lanox.com> wrote:
> Even though ip6erspan_tap_init() sets up hlen and tun_hlen according to
> what ERSPAN needs, it goes ahead to call ip6gre_tnl_link_config() which
> overwrites these settings with GRE-specific ones.
>
> Similarly for changelink callbacks, which are handled by
> ip6gre_changelink() calls ip6gre_tnl_change() calls
> ip6gre_tnl_link_config() as well.
>
> The difference ends up being 12 vs. 20 bytes, and this is generally not
> a problem, because a 12-byte request likely ends up allocating more and
> the extra 8 bytes are thus available. However correct it is not.
>
> So replace the newlink and changelink callbacks with an ERSPAN-specific
> ones, reusing the newly-introduced _common() functions.
>
> Signed-off-by: Petr Machata <petrm@...lanox.com>
> ---
Acked-by: William Tu <u9012063@...il.com>
Thanks, using ERSPAN-specific newlink and changelink is also on
my todo list. I'm hitting another issue related to the shared collect_md_tun
between erspan and gre, I will make my patch based on this series.
> net/ipv6/ip6_gre.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++-------
> 1 file changed, 65 insertions(+), 9 deletions(-)
>
> diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
> index c17e38b..36b1669 100644
> --- a/net/ipv6/ip6_gre.c
> +++ b/net/ipv6/ip6_gre.c
> @@ -81,6 +81,7 @@ static int ip6gre_tunnel_init(struct net_device *dev);
> static void ip6gre_tunnel_setup(struct net_device *dev);
> static void ip6gre_tunnel_link(struct ip6gre_net *ign, struct ip6_tnl *t);
> static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu);
> +static void ip6erspan_tnl_link_config(struct ip6_tnl *t, int set_mtu);
>
> /* Tunnel hash table */
>
> @@ -1751,6 +1752,19 @@ static const struct net_device_ops ip6gre_tap_netdev_ops = {
> .ndo_get_iflink = ip6_tnl_get_iflink,
> };
>
> +static int ip6erspan_calc_hlen(struct ip6_tnl *tunnel)
> +{
> + int t_hlen;
> +
> + tunnel->tun_hlen = 8;
> + tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen +
> + erspan_hdr_len(tunnel->parms.erspan_ver);
> +
> + t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);
> + tunnel->dev->hard_header_len = LL_MAX_HEADER + t_hlen;
> + return t_hlen;
> +}
> +
> static int ip6erspan_tap_init(struct net_device *dev)
> {
> struct ip6_tnl *tunnel;
> @@ -1774,12 +1788,7 @@ static int ip6erspan_tap_init(struct net_device *dev)
> return ret;
> }
>
> - tunnel->tun_hlen = 8;
> - tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen +
> - erspan_hdr_len(tunnel->parms.erspan_ver);
> - t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);
> -
> - dev->hard_header_len = LL_MAX_HEADER + t_hlen;
> + t_hlen = ip6erspan_calc_hlen(tunnel);
> dev->mtu = ETH_DATA_LEN - t_hlen;
> if (dev->type == ARPHRD_ETHER)
> dev->mtu -= ETH_HLEN;
> @@ -1787,7 +1796,7 @@ static int ip6erspan_tap_init(struct net_device *dev)
> dev->mtu -= 8;
>
> dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
> - ip6gre_tnl_link_config(tunnel, 1);
> + ip6erspan_tnl_link_config(tunnel, 1);
>
> return 0;
> }
> @@ -2118,6 +2127,53 @@ static void ip6erspan_tap_setup(struct net_device *dev)
> netif_keep_dst(dev);
> }
>
> +static int ip6erspan_newlink(struct net *src_net, struct net_device *dev,
> + struct nlattr *tb[], struct nlattr *data[],
> + struct netlink_ext_ack *extack)
> +{
> + int err = ip6gre_newlink_common(src_net, dev, tb, data, extack);
> + struct ip6_tnl *nt = netdev_priv(dev);
> + struct net *net = dev_net(dev);
> +
> + if (!err) {
> + ip6erspan_tnl_link_config(nt, !tb[IFLA_MTU]);
> + ip6gre_tunnel_link(net_generic(net, ip6gre_net_id), nt);
> + }
> + return err;
> +}
> +
> +static void ip6erspan_tnl_link_config(struct ip6_tnl *t, int set_mtu)
> +{
> + ip6gre_tnl_link_config_common(t);
> + ip6gre_tnl_link_config_route(t, set_mtu, ip6erspan_calc_hlen(t));
> +}
> +
> +static int ip6erspan_tnl_change(struct ip6_tnl *t,
> + const struct __ip6_tnl_parm *p, int set_mtu)
> +{
> + ip6gre_tnl_copy_tnl_parm(t, p);
> + ip6erspan_tnl_link_config(t, set_mtu);
> + return 0;
> +}
> +
> +static int ip6erspan_changelink(struct net_device *dev, struct nlattr *tb[],
> + struct nlattr *data[],
> + struct netlink_ext_ack *extack)
> +{
> + struct ip6gre_net *ign = net_generic(dev_net(dev), ip6gre_net_id);
> + struct __ip6_tnl_parm p;
> + struct ip6_tnl *t;
> +
> + t = ip6gre_changelink_common(dev, tb, data, &p, extack);
> + if (IS_ERR(t))
> + return PTR_ERR(t);
> +
> + ip6gre_tunnel_unlink(ign, t);
> + ip6erspan_tnl_change(t, &p, !tb[IFLA_MTU]);
> + ip6gre_tunnel_link(ign, t);
> + return 0;
> +}
> +
> static struct rtnl_link_ops ip6gre_link_ops __read_mostly = {
> .kind = "ip6gre",
> .maxtype = IFLA_GRE_MAX,
> @@ -2154,8 +2210,8 @@ static struct rtnl_link_ops ip6erspan_tap_ops __read_mostly = {
> .priv_size = sizeof(struct ip6_tnl),
> .setup = ip6erspan_tap_setup,
> .validate = ip6erspan_tap_validate,
> - .newlink = ip6gre_newlink,
> - .changelink = ip6gre_changelink,
> + .newlink = ip6erspan_newlink,
> + .changelink = ip6erspan_changelink,
> .get_size = ip6gre_get_size,
> .fill_info = ip6gre_fill_info,
> .get_link_net = ip6_tnl_get_link_net,
> --
> 2.4.11
>
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