From: Stephen Hemminger <stephen@networkplumber•org>
To: Daniel Borkmann <dborkman@redhat•com>
Cc: davem@davemloft•net, netdev@vger•kernel.org
Subject: Re: [PATCH net-next 1/2] net: vxlan: when lower dev unregisters remove vxlan dev as well
Date: Mon, 13 Jan 2014 18:22:32 -0800 [thread overview]
Message-ID: <20140113182232.355f9d20@nehalam.linuxnetplumber.net> (raw)
In-Reply-To: <1389634880-4138-2-git-send-email-dborkman@redhat.com>
On Mon, 13 Jan 2014 18:41:19 +0100
Daniel Borkmann <dborkman@redhat•com> wrote:
> We can create a vxlan device with an explicit underlying carrier.
> In that case, when the carrier link is being deleted from the
> system (e.g. due to module unload) we should also clean up all
> created vxlan devices on top of it since otherwise we're in an
> inconsistent state in vxlan device. In that case, the user needs
> to remove all such devices, while in case of other virtual devs
> that sit on top of physical ones, it is usually the case that
> these devices do unregister automatically as well and do not
> leave the burden on the user.
>
> This work is not necessary when vxlan device was not created with
> a real underlying device, as connections can resume in that case
> when driver is plugged again. But at least for the other cases,
> we should go ahead and do the cleanup on removal.
>
> We don't register the notifier during vxlan_newlink() here since
> I consider this event rather rare, and therefore we should not
> bloat vxlan's core structure unecessary. Also, we can simply make
> use of unregister_netdevice_many() to batch that. fdb is flushed
> upon ndo_stop().
>
> E.g. `ip -d link show vxlan13` after carrier removal before
> this patch:
>
> 5: vxlan13: <BROADCAST,MULTICAST> mtu 1450 qdisc noop state DOWN mode DEFAULT group default
> link/ether 1e:47:da:6d:4d:99 brd ff:ff:ff:ff:ff:ff promiscuity 0
> vxlan id 13 group 239.0.0.10 dev 2 port 32768 61000 ageing 300
> ^^^^^
> Signed-off-by: Daniel Borkmann <dborkman@redhat•com>
Since vxlan is running over UDP socket. I wonder if this could be
done better by implementing something equivalent to SO_BINDTODEVICE.
What happens to a user land application which has a UDP socket
and has done SO_BINDTODEVICE and device is removed? Is there an asynchronous
error, can the application recover? Why can't vxlan use the same mechanism?
next prev parent reply other threads:[~2014-01-14 2:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-13 17:41 [PATCH net-next 0/2] vxlan updates Daniel Borkmann
2014-01-13 17:41 ` [PATCH net-next 1/2] net: vxlan: when lower dev unregisters remove vxlan dev as well Daniel Borkmann
2014-01-14 2:22 ` Stephen Hemminger [this message]
2014-01-14 14:02 ` Daniel Borkmann
2014-01-13 17:41 ` [PATCH net-next 2/2] net: vxlan: properly cleanup devs on module unload Daniel Borkmann
2014-01-13 21:59 ` [PATCH net-next 0/2] vxlan updates Cong Wang
2014-01-15 7:39 ` David Miller
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