netdev - Re: [PATCH] geneve: fix max

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Date:	Mon, 27 Jun 2016 19:53:51 -0700
From:	Jesse Gross <jesse@...nel.org>
To:	严海双 <yanhaishuang@...s.chinamobile.com>
Cc:	zhuyj <zyjzyj2000@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Pravin B Shelar <pshelar@...ira.com>,
	Tom Herbert <tom@...bertland.com>,
	netdev <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] geneve: fix max_mtu setting

On Mon, Jun 27, 2016 at 6:27 PM, 严海双 <yanhaishuang@...s.chinamobile.com> wrote:
>
> On Jun 28, 2016, at 12:10 AM, Jesse Gross <jesse@...nel.org> wrote:
>
> On Sun, Jun 26, 2016 at 6:13 PM, Haishuang Yan
> <yanhaishuang@...s.chinamobile.com> wrote:
>
>
> On Jun 26, 2016, at 8:35 PM, zhuyj <zyjzyj2000@...il.com> wrote:
>
> +       if (geneve->remote.sa.sa_family == AF_INET)
> +               max_mtu -= sizeof(struct iphdr);
> +       else
> +               max_mtu -= sizeof(struct ipv6hdr);
>
> Sorry, if sa_family is not AF_NET, it is AF_INET6?
>
> There is a lot of macros in include/linux/socket.h.
>
> Zhu Yanjun
>
>
> There are only two enumerations AF_INET and AF_INET6 have been assigned in
> geneve_newlink:
>
>
> There's actually a third possibility: AF_UNSPEC, which is the default
> if neither remote type is specified. This is used by lightweight
> tunnels and should be able to work with either IPv4/v6. For the
> purposes of the MTU calculation this means that the IPv4 header size
> should be used to avoid disallowing potentially valid configurations.
>
>
> Yes, you’re right. Thanks for you advise. I will send a v2 commit like this:
>
>        if (geneve->remote.sa.sa_family == AF_INET6)
>               max_mtu -= sizeof(struct ipv6hdr);
>        else
>               max_mtu -= sizeof(struct iphdr);
>
> Is this ok?

Yes, that looks fine to me.