On Mon, Dec 28, 2020 at 11:55:36AM +0000, wangyunjian wrote: > > -----Original Message----- > > From: Michael S. Tsirkin [mailto:mst@xxxxxxxxxx] > > Sent: Sunday, December 27, 2020 7:21 PM > > To: wangyunjian <wangyunjian@xxxxxxxxxx> > > Cc: netdev@xxxxxxxxxxxxxxx; jasowang@xxxxxxxxxx; > > willemdebruijn.kernel@xxxxxxxxx; virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx; > > Lilijun (Jerry) <jerry.lilijun@xxxxxxxxxx>; chenchanghu > > <chenchanghu@xxxxxxxxxx>; xudingke <xudingke@xxxxxxxxxx>; huangbin (J) > > <brian.huangbin@xxxxxxxxxx> > > Subject: Re: [PATCH net v5 2/2] vhost_net: fix tx queue stuck when sendmsg > > fails > > > > On Fri, Dec 25, 2020 at 03:24:33PM +0800, wangyunjian wrote: > > > From: Yunjian Wang <wangyunjian@xxxxxxxxxx> > > > > > > Currently the driver doesn't drop a packet which can't be sent by tun > > > (e.g bad packet). In this case, the driver will always process the > > > same packet lead to the tx queue stuck. > > > > So not making progress on a bad packet has some advantages, e.g. this is > > easier to debug. > > When is it important to drop the packet and continue? > > In the case, the VM will not be able to send packets persistently. Services of VM > are affected. > > Thanks Well VM can always harm itself right? Just halt the CPU, services will be affected ;) > > > > > > > To fix this issue: > > > 1. in the case of persistent failure (e.g bad packet), the driver > > > can skip this descriptor by ignoring the error. > > > 2. in the case of transient failure (e.g -ENOBUFS, -EAGAIN and -ENOMEM), > > > the driver schedules the worker to try again. > > > > > > Fixes: 3a4d5c94e959 ("vhost_net: a kernel-level virtio server") > > > > I'd just drop this tag, looks more like a feature than a bug ... > > OK > > > > > > > > Signed-off-by: Yunjian Wang <wangyunjian@xxxxxxxxxx> > > > Acked-by: Willem de Bruijn <willemb@xxxxxxxxxx> > > > --- > > > drivers/vhost/net.c | 16 ++++++++-------- > > > 1 file changed, 8 insertions(+), 8 deletions(-) > > > > > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index > > > c8784dfafdd7..01558fb2c552 100644 > > > --- a/drivers/vhost/net.c > > > +++ b/drivers/vhost/net.c > > > @@ -827,14 +827,13 @@ static void handle_tx_copy(struct vhost_net *net, > > struct socket *sock) > > > msg.msg_flags &= ~MSG_MORE; > > > } > > > > > > - /* TODO: Check specific error and bomb out unless ENOBUFS? */ > > > err = sock->ops->sendmsg(sock, &msg, len); > > > - if (unlikely(err < 0)) { > > > + if (unlikely(err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS)) > > > +{ > > > vhost_discard_vq_desc(vq, 1); > > > vhost_net_enable_vq(net, vq); > > > break; > > > } > > > - if (err != len) > > > + if (err >= 0 && err != len) > > > pr_debug("Truncated TX packet: len %d != %zd\n", > > > err, len); > > > done: > > > @@ -922,7 +921,6 @@ static void handle_tx_zerocopy(struct vhost_net > > *net, struct socket *sock) > > > msg.msg_flags &= ~MSG_MORE; > > > } > > > > > > - /* TODO: Check specific error and bomb out unless ENOBUFS? */ > > > err = sock->ops->sendmsg(sock, &msg, len); > > > if (unlikely(err < 0)) { > > > if (zcopy_used) { > > > @@ -931,11 +929,13 @@ static void handle_tx_zerocopy(struct vhost_net > > *net, struct socket *sock) > > > nvq->upend_idx = ((unsigned)nvq->upend_idx - 1) > > > % UIO_MAXIOV; > > > } > > > - vhost_discard_vq_desc(vq, 1); > > > - vhost_net_enable_vq(net, vq); > > > - break; > > > + if (err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS) { > > > + vhost_discard_vq_desc(vq, 1); > > > + vhost_net_enable_vq(net, vq); > > > + break; > > > + } > > > } > > > - if (err != len) > > > + if (err >= 0 && err != len) > > > pr_debug("Truncated TX packet: " > > > " len %d != %zd\n", err, len); > > > if (!zcopy_used) > > > -- > > > 2.23.0 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
