On (Wed) 06 Aug 2014 [16:05:41], Amos Kong wrote: > On Wed, Aug 06, 2014 at 01:35:15AM +0800, Amos Kong wrote: > > When we try to hot-remove a busy virtio-rng device from QEMU monitor, > > the device can't be hot-removed. Because virtio-rng driver hangs at > > wait_for_completion_killable(). > > > > This patch fixed the hang by completing have_data completion before > > unregistering a virtio-rng device. > > Hi Amit, > > Before applying this patch, it's blocking insider wait_for_completion_killable() > Applied this patch, wait_for_completion_killable() returns 0, > and vi->data_avail becomes 0, then rng_get_date() will return 0. Thanks for checking this. > Is it expected result? I think what will happen is vi->data_avail will be set to whatever it was set last. In case of a previous successful read request, the data_avail will be set to whatever number of bytes the host gave. On doing a hot-unplug on the succeeding wait, the value in data_avail will be re-used, and the hwrng core will wrongly take some bytes in the buffer as input from the host. So, I think we need to set vi->data_avail = 0; before calling wait_event_completion_killable(). Amit _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
