Re: [PATCH v2] vhost_net: revert upend_idx only on retriable error
From: Jason Wang <jasowang@redhat.com>
Date: 2023-05-11 07:32:36
Also in:
kvm, lkml, virtualization
On Tue, Apr 25, 2023 at 4:44 AM Andrey Smetanin [off-list ref] wrote:
Fix possible virtqueue used buffers leak and corresponding stuck in case of temporary -EIO from sendmsg() which is produced by tun driver while backend device is not up. In case of no-retriable error and zcopy do not revert upend_idx to pass packet data (that is update used_idx in corresponding vhost_zerocopy_signal_used()) as if packet data has been transferred successfully. v2: set vq->heads[ubuf->desc].len equal to VHOST_DMA_DONE_LEN in case of fake successful transmit. Signed-off-by: Andrey Smetanin <redacted>
Acked-by: Jason Wang <jasowang@redhat.com> Thanks
quoted hunk
--- drivers/vhost/net.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 20265393aee7..0791fbdb3975 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c@@ -934,13 +934,18 @@ static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock) err = sock->ops->sendmsg(sock, &msg, len); if (unlikely(err < 0)) { + bool retry = err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS; + if (zcopy_used) { if (vq->heads[ubuf->desc].len == VHOST_DMA_IN_PROGRESS) vhost_net_ubuf_put(ubufs); - nvq->upend_idx = ((unsigned)nvq->upend_idx - 1) - % UIO_MAXIOV; + if (retry) + nvq->upend_idx = ((unsigned)nvq->upend_idx - 1) + % UIO_MAXIOV; + else + vq->heads[ubuf->desc].len = VHOST_DMA_DONE_LEN; } - if (err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS) { + if (retry) { vhost_discard_vq_desc(vq, 1); vhost_net_enable_vq(net, vq); break; --2.25.1