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[79.178.32.166]) by smtp.gmail.com with ESMTPSA id u10sm14272328wmd.43.2020.12.27.03.09.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 27 Dec 2020 03:09:35 -0800 (PST) Date: Sun, 27 Dec 2020 06:09:32 -0500 From: "Michael S. Tsirkin" To: wangyunjian Cc: netdev@vger.kernel.org, jasowang@redhat.com, willemdebruijn.kernel@gmail.com, virtualization@lists.linux-foundation.org, jerry.lilijun@huawei.com, chenchanghu@huawei.com, xudingke@huawei.com, brian.huangbin@huawei.com Subject: Re: [PATCH net v5 2/2] vhost_net: fix tx queue stuck when sendmsg fails Message-ID: <20201227060159-mutt-send-email-mst@kernel.org> References: <1608881073-19004-1-git-send-email-wangyunjian@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1608881073-19004-1-git-send-email-wangyunjian@huawei.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Dec 25, 2020 at 03:24:33PM +0800, wangyunjian wrote: > From: Yunjian Wang > > 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 > Acked-by: Willem de Bruijn > --- > 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