Re: [Qemu-devel] [PATCH v2] net: Flush queued packets when guest resumes

[Stefan Hajnoczi]

On Tue, Jul 07, 2015 at 12:10:15PM +0300, Michael S. Tsirkin wrote:
> On Tue, Jul 07, 2015 at 04:58:29PM +0800, Jason Wang wrote:
> > 
> > 
> > On 07/07/2015 04:13 PM, Michael S. Tsirkin wrote:
> > > On Tue, Jul 07, 2015 at 09:21:07AM +0800, Fam Zheng wrote:
> > >> Since commit 6e99c63 "net/socket: Drop net_socket_can_send" and friends,
> > >> net queues need to be explicitly flushed after qemu_can_send_packet()
> > >> returns false, because the netdev side will disable the polling of fd.
> > >>
> > >> This fixes the case of "cont" after "stop" (or migration).
> > >>
> > >> Signed-off-by: Fam Zheng <address@hidden>
> > > Note virtio has its own handler which must be used to
> > > flush packets - this one might run too early or too late.
> > 
> > If runs too realy (DRIVER_OK is not set), then: packet will be dropped
> > (if this patch is used with "drop virtio_net_can_receive()", or the
> > queue will be purged since qemu_can_send_packet() returns false. If too
> > late, at least tap read poll will be enabled. So still looks ok?
> 
> It's still not helpful for virtio. So which cards are fixed?
> 
> I just find the comment
>       This fixes the case of "cont" after "stop" (or migration)
> too vague.
> Can you please include the info about what's broken in the commit log?

Max Fillipov reported that it's needed to fix the gdb stub:
https://lists.gnu.org/archive/html/qemu-devel/2015-07/msg01015.html

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