From 2b8b328b61c799957a456a5a8dab8cc7dea68575 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Mon, 28 Jan 2013 01:05:18 +0000 Subject: 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 Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- drivers/vhost/net.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-) (limited to 'drivers/vhost/net.c') diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index d10ad6f8df7e..959b1cd89e6a 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -165,12 +165,16 @@ static void tx_poll_stop(struct vhost_net *net) } /* 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 @@ static void vhost_net_disable_vq(struct vhost_net *n, 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 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd) 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; -- cgit v1.2.3