Jason Wang
2021-May-27 05:40 UTC
[PATCH v7 11/12] vduse: Introduce VDUSE - vDPA Device in Userspace
? 2021/5/27 ??1:08, Yongji Xie ??:> On Thu, May 27, 2021 at 1:00 PM Jason Wang <jasowang at redhat.com> wrote: >> >> ? 2021/5/27 ??12:57, Yongji Xie ??: >>> On Thu, May 27, 2021 at 12:13 PM Jason Wang <jasowang at redhat.com> wrote: >>>> ? 2021/5/17 ??5:55, Xie Yongji ??: >>>>> + >>>>> +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?Maybe, but I'm not sure how hard we can do that. We had NEEDS_RESET but it looks we don't implement it. Or a rough idea is that maybe need some relaxing to be coupled loosely with userspace. E.g the device (control path) is implemented in the kernel but the datapath is implemented in the userspace like TUN/TAP. Thanks> > Thanks, > Yongji >