Re: [PATCH net] vhost_net: don't continue to call the recvmsg when meet errors

[Jason Wang]

On 2016å11æ30æ 21:40, Michael S. Tsirkin wrote:
> On Wed, Nov 30, 2016 at 08:10:57PM +0800, Yunjian Wang wrote:
> > When we meet an error(err=-EBADFD) recvmsg,
> How do you get EBADFD? Won't vhost_net_rx_peek_head_len
> return 0 in this case, breaking the loop?
>
> > the error handling in vhost
> > handle_rx() will continue. This will cause a soft CPU lockup in vhost thread.
> >
> > Signed-off-by: Yunjian Wang <wangyunjian@xxxxxxxxxx>
> > ---
> >   drivers/vhost/net.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> > index 5dc128a..edc470b 100644
> > --- a/drivers/vhost/net.c
> > +++ b/drivers/vhost/net.c
> > @@ -717,6 +717,9 @@ static void handle_rx(struct vhost_net *net)
> >   			pr_debug("Discarded rx packet: "
> >   				 " len %d, expected %zd\n", err, sock_len);
> >   			vhost_discard_vq_desc(vq, headcount);
> > +			/* Don't continue to do, when meet errors. */
> > +			if (err < 0)
> > +				goto out;
> You might get e.g. EAGAIN and I think you need to retry
> in this case.

Yes.

> >   			continue;
> >   		}
> >   		/* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
> > --
> > 1.9.5.msysgit.1