Re: [Qemu-devel] [PATCH v2] net-hub: Drop can_receive

[Stefan Hajnoczi]

On Tue, Jul 21, 2015 at 09:27:56AM +0800, Fam Zheng wrote:
> On Mon, 07/20 18:07, Stefan Hajnoczi wrote:
> > On Tue, Jul 07, 2015 at 05:41:56PM +0800, Fam Zheng wrote:
> > > On Tue, 07/07 09:37, Stefan Hajnoczi wrote:
> > > > On Tue, Jul 07, 2015 at 02:30:30PM +0800, Fam Zheng wrote:
> > > > > This moves the semantics from net_hub_port_can_receive to receive
> > > > > functions, by returning 0 if all receiving ports return 0. Also,
> > > > > remember to flush the source port's queue in that case.
> > > > > 
> > > > > Signed-off-by: Fam Zheng <address@hidden>
> > > > > ---
> > > > >  net/hub.c | 54 +++++++++++++++++++++++++++++-------------------------
> > > > >  1 file changed, 29 insertions(+), 25 deletions(-)
> > > > 
> > > > This patch revision doesn't take into account the special case code in
> > > > qemu_flush_or_purge_queued_packets(), which I mentioned in my reply to
> > > > the previous revision of this patch.
> > > > 
> > > > The queue is now flushed twice because you've introduced
> > > > net_hub_port_send_cb() but qemu_flush_or_purge_queued_packets() already
> > > > calls net_hub_flush().
> > > > 
> > > > If you want to get rid of net_hub_flush(), that's great.  But please
> > > > remove the duplicate code.
> > > 
> > > Right, I missed that. I'll remove the duplicate and send again.
> > 
> > Ping?
> 
> I thought the net_hub_flush in qemu_flush_or_purge_queued_packets already 
> makes
> sure net-hub is working, so it's just about cleaning up. That's why I deferred
> this to 2.5.  Am I wrong?

My concern was that your NIC patches remove .can_receive() functions but
net/hub.c still relies on them via qemu_can_send_packet().

After thinking about it more, the code should still work the same even
though net_hub_can_receive() is now mostly useless and should be removed
in QEMU 2.5.

We can leave this patch for now.

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