From: Jason Wang Date: Mon, 28 Jan 2013 01:05:18 +0000 (+0000) Subject: vhost_net: handle polling errors when setting backend X-Git-Tag: Ubuntu-5.0.0-8.9~14380^2~36 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=2b8b328b61c799957a456a5a8dab8cc7dea68575;p=mirror_ubuntu-disco-kernel.git 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 --- 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; diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 34389f75fe65..9759249e6d90 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -77,26 +77,38 @@ void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, init_poll_funcptr(&poll->table, vhost_poll_func); poll->mask = mask; poll->dev = dev; + poll->wqh = NULL; vhost_work_init(&poll->work, fn); } /* Start polling a file. We add ourselves to file's wait queue. The caller must * keep a reference to a file until after vhost_poll_stop is called. */ -void vhost_poll_start(struct vhost_poll *poll, struct file *file) +int vhost_poll_start(struct vhost_poll *poll, struct file *file) { unsigned long mask; + int ret = 0; mask = file->f_op->poll(file, &poll->table); if (mask) vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask); + if (mask & POLLERR) { + if (poll->wqh) + remove_wait_queue(poll->wqh, &poll->wait); + ret = -EINVAL; + } + + return ret; } /* Stop polling a file. After this function returns, it becomes safe to drop the * file reference. You must also flush afterwards. */ void vhost_poll_stop(struct vhost_poll *poll) { - remove_wait_queue(poll->wqh, &poll->wait); + if (poll->wqh) { + remove_wait_queue(poll->wqh, &poll->wait); + poll->wqh = NULL; + } } static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work, @@ -792,7 +804,7 @@ long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp) fput(filep); if (pollstart && vq->handle_kick) - vhost_poll_start(&vq->poll, vq->kick); + r = vhost_poll_start(&vq->poll, vq->kick); mutex_unlock(&vq->mutex); diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 2639c58b23ab..17261e277c02 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -42,7 +42,7 @@ void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work); void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, unsigned long mask, struct vhost_dev *dev); -void vhost_poll_start(struct vhost_poll *poll, struct file *file); +int vhost_poll_start(struct vhost_poll *poll, struct file *file); void vhost_poll_stop(struct vhost_poll *poll); void vhost_poll_flush(struct vhost_poll *poll); void vhost_poll_queue(struct vhost_poll *poll);