[libvirt] [PATCH] qemu: Allow empty script path to <interface/>

[Daniel P. Berrange]

On Thu, Feb 02, 2017 at 02:49:48PM +0100, Michal Privoznik wrote:
> Before 9c17d665fdc5f (v1.3.2 - I know, right?) it was possible to
> have the following interface configuration:
> 
>   <interface type='ethernet'/>
>     <script path=''/>
>   </interface>
> 
> This resulted in -netdev tap,script=,.. Fortunately, qemu helped
> us to get away with this as it just ignored the empty script
> path. However, after the commit mentioned above it's libvirtd
> who is executing the script. Unfortunately without special
> case-ing empty script path.
> 
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  docs/news.xml        | 10 ++++++++++
>  src/util/virnetdev.c |  4 ++++
>  2 files changed, 14 insertions(+)

ACK because this causes upgrade problems when using migration. Applications
like OpenStack use migration as their upgrade mechanism. ie to upgrade a new
version of Nova, you would install it on a new compute host and migrate your
guests across. For nova to fix its buggy usage, users would have to upgrade
Nova in-place on existing nodes which is contrary to its normal practice of
using migration for all upgradess


Regards,
Daniel
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