On Thu, May 27, 2021 at 1:00 PM Jason Wang [off-list ref] wrote:

在 2021/5/27 下午12:57, Yongji Xie 写道:

quoted

On Thu, May 27, 2021 at 12:13 PM Jason Wang [off-list ref] wrote:

quoted

在 2021/5/17 下午5:55, Xie Yongji 写道:

quoted

+
+static int vduse_dev_msg_sync(struct vduse_dev *dev,
+                           struct vduse_dev_msg *msg)
+{
+     init_waitqueue_head(&msg->waitq);
+     spin_lock(&dev->msg_lock);
+     vduse_enqueue_msg(&dev->send_list, msg);
+     wake_up(&dev->waitq);
+     spin_unlock(&dev->msg_lock);
+     wait_event_killable(msg->waitq, msg->completed);

What happens if the userspace(malicous) doesn't give a response forever?

It looks like a DOS. If yes, we need to consider a way to fix that.

How about using wait_event_killable_timeout() instead?

Probably, and then we need choose a suitable timeout and more important,
need to report the failure to virtio.

Makes sense to me. But it looks like some
vdpa_config_ops/virtio_config_ops such as set_status() didn't have a
return value.  Now I add a WARN_ON() for the failure. Do you mean we
need to add some change for virtio core to handle the failure?

Thanks,
Yongji