Re: [PATCH RFC] hotplug/Linux: Add --wait to iptables calls.

[Ian Campbell <ian.campbell@citrix.com>]

On Mon, 2015-06-01 at 16:08 +0100, Jan Beulich wrote:
> >>> On 01.06.15 at 16:59, <anthony.perard@citrix.com> wrote:
> > --- a/tools/hotplug/Linux/vif-common.sh
> > +++ b/tools/hotplug/Linux/vif-common.sh
> > @@ -130,9 +130,9 @@ frob_iptable()
> >      local c="-D"
> >    fi
> >  
> > -  iptables "$c" FORWARD -m physdev --physdev-is-bridged --physdev-in "$dev" \
> > +  iptables --wait "$c" FORWARD -m physdev --physdev-is-bridged --physdev-in "$dev" \
> >      "$@" -j ACCEPT 2>/dev/null &&
> > -  iptables "$c" FORWARD -m physdev --physdev-is-bridged --physdev-out "$dev" \
> > +  iptables --wait "$c" FORWARD -m physdev --physdev-is-bridged --physdev-out "$dev" \
> >      -j ACCEPT 2>/dev/null
> >  
> >    if [ \( "$command" == "online" -o "$command" == "add" \) -a $? -ne 0 ]
> 
> Looking at my oldest system's "iptables --help" I can't spot such an
> option (which doesn't necessarily mean it's not supported). Did you
> make sure all (older) distros we care about actually support this?

It's not really clear if/why --wait is the solution to the problem of
another party using iptables-{save,restore} to do their own network
management in the first place.

If OpenStack is doing save/modify/restore then what stops us rewriting
things in the middle and then getting those changes clobbered on
restore? Surely iptables-save can't exit holding the lock...

And if nova-network is managing networking do we really need to do it
too?

Ian.