Michael S. Tsirkin
2020-Dec-27 11:09 UTC
[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 at huawei.com> > > 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. > > 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") > Signed-off-by: Yunjian Wang <wangyunjian at huawei.com> > Acked-by: Willem de Bruijn <willemb at google.com> > --- > 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; > }Hmm, there's the case of link being temporarily down (e.g. for reconfigure), which IIRC returns EIO. It's also probably a good idea to keep unlikely(err < 0) around and then just regular err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS since that first test can be done faster.> - 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) {same here> + 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