Re: [Qemu-devel] [PATCH RFC 0/7] Netfilter: Add each netdev a default filter

[Hailiang Zhang]

On 2016/1/22 18:07, Daniel P. Berrange wrote:
> On Fri, Jan 22, 2016 at 04:36:44PM +0800, zhanghailiang wrote:
> > This series is a prerequisite for COLO, here we add each netdev
> > a default buffer filter, it is disabled by default, and has
> > no side effect for delivering packets in net layer.
>
> Why can't whatever is launching QEMU just setup filters explicitly
> if they want to use COLO ? I'm not seeing an obvious compelling
> reason to add this by default and then add extra code to deal
> with special casing its behaviour.

The main reason is, we hope to support hot add network during VM's COLO
lifetime in the future. (I'm not quite sure if this usage case is really exist,
but we don't want the VM in COLO state has too many limitations.)

Maybe add an option that users can control if they want to use COLO or not is 
more
acceptable ? With this option, we can decide whether to add the default filter 
or not.
Or, we could dynamically add filter while users ask to go into COLO state for 
VM.
(We have discussed this before in community, and Jason suggested me to add 
default
filter for each netdev to support hot-add network during COLO state).

What's your suggestion ?

Thanks,
Hailiang

> > Besides, patch 1 fixes the ouput information of 'info network' command
> > for filter.
> >
> > zhanghailiang (7):
> >    net/filter: Fix the output information for command 'info network'
> >    net/filter: Add a 'status' property for filter object
> >    net/filter: Skip the disabled filter when delivering packets
> >    net/filter: Introduce a helper to add a filter to the netdev
> >    filter-buffer: Accept zero interval
> >    net/filter: Add a default filter to each netdev
> >    net/filter: prevent the default filter to be deleted
> >
> >   include/net/filter.h |  25 +++++++-
> >   net/dump.c           |   2 -
> >   net/filter-buffer.c  |  10 ----
> >   net/filter.c         | 163 +++++++++++++++++++++++++++++++++++++++++++++------
> >   net/net.c            |  27 ++++++++-
> >   5 files changed, 194 insertions(+), 33 deletions(-)
>
> Regards,
> Daniel