On Wed, Dec 23, 2020 at 9:47 AM wangyunjian <wangyunjian@xxxxxxxxxx> wrote:
>
> From: Yunjian Wang <wangyunjian@xxxxxxxxxx>
>
> Currently the driver don't drop a packet which can't be send 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 descriptior by ignoring the error.
> 2. in the case of transient failure (e.g -EAGAIN and -ENOMEM), the
> driver schedules the worker to try again.
>
Fixes: 3a4d5c94e959 ("vhost_net: a kernel-level virtio server")
Since I have a few other comments, a few minor typo corrections too:
don't -> doesn't, send -> sent, descriptior -> descriptor.
> Signed-off-by: Yunjian Wang <wangyunjian@xxxxxxxxxx>
>
> drivers/vhost/net.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index c8784dfafdd7..e49dd64d086a 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -827,9 +827,8 @@ 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)) {
> vhost_discard_vq_desc(vq, 1);
> vhost_net_enable_vq(net, vq);
> break;
> @@ -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) {
> @@ -931,9 +929,11 @@ 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) {
> + vhost_discard_vq_desc(vq, 1);
> + vhost_net_enable_vq(net, vq);
> + break;
> + }
> }
> if (err != len)
> pr_debug("Truncated TX packet: "
Probably my bad for feedback in patch 2/2, but now vhost will
incorrectly log bad packets as truncated packets.
This will need to be if (err >= 0 && err != len).
It would be nice if we could notify the guest in the transmit
descriptor when a packet was dropped due to failing integrity checks
(bad packet). But I don't think we easily can, so out of scope for
this fix.
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