vhost_net: handle polling errors when setting backend
Currently, the polling errors were ignored, which can lead following issues:
- vhost remove itself unconditionally from waitqueue when stopping the poll,
this may crash the kernel since the previous attempt of starting may fail to
add itself to the waitqueue
- userspace may think the backend were successfully set even when the polling
failed.
Solve this by:
- check poll->wqh before trying to remove from waitqueue
- report polling errors in vhost_poll_start(), tx_poll_start(), the return value
will be checked and returned when userspace want to set the backend
After this fix, there still could be a polling failure after backend is set, it
will addressed by the next patch.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index d10ad6f..959b1cd 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -165,12 +165,16 @@
}
/* Caller must have TX VQ lock */
-static void tx_poll_start(struct vhost_net *net, struct socket *sock)
+static int tx_poll_start(struct vhost_net *net, struct socket *sock)
{
+ int ret;
+
if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED))
- return;
- vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
- net->tx_poll_state = VHOST_NET_POLL_STARTED;
+ return 0;
+ ret = vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
+ if (!ret)
+ net->tx_poll_state = VHOST_NET_POLL_STARTED;
+ return ret;
}
/* In case of DMA done not in order in lower device driver for some reason.
@@ -642,20 +646,23 @@
vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
}
-static void vhost_net_enable_vq(struct vhost_net *n,
+static int vhost_net_enable_vq(struct vhost_net *n,
struct vhost_virtqueue *vq)
{
struct socket *sock;
+ int ret;
sock = rcu_dereference_protected(vq->private_data,
lockdep_is_held(&vq->mutex));
if (!sock)
- return;
+ return 0;
if (vq == n->vqs + VHOST_NET_VQ_TX) {
n->tx_poll_state = VHOST_NET_POLL_STOPPED;
- tx_poll_start(n, sock);
+ ret = tx_poll_start(n, sock);
} else
- vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
+ ret = vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
+
+ return ret;
}
static struct socket *vhost_net_stop_vq(struct vhost_net *n,
@@ -833,7 +840,9 @@
r = vhost_init_used(vq);
if (r)
goto err_used;
- vhost_net_enable_vq(n, vq);
+ r = vhost_net_enable_vq(n, vq);
+ if (r)
+ goto err_used;
oldubufs = vq->ubufs;
vq->ubufs = ubufs;