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?
> 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 ...
> 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
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