On Tue, 02/20 13:10, Stefan Hajnoczi wrote:
> 1. virtio_scsi_handle_cmd_vq() racing with iothread_stop_all() hits the
> virtio_scsi_ctx_check() assertion failure because the BDS AioContext
> has been modified by iothread_stop_all().
Does this patch fix the issue completely? IIUC virtio_scsi_handle_cmd can
already be entered at the time of main thread calling virtio_scsi_clear_aio(),
so this race condition still exists:
main thread iothread
-----------------------------------------------------------------------------
vm_shutdown
...
virtio_bus_stop_ioeventfd
virtio_scsi_dataplane_stop
aio_poll()
...
virtio_scsi_data_plane_handle_cmd()
aio_context_acquire(s->ctx)
virtio_scsi_acquire(s).enter
virtio_scsi_clear_aio()
aio_context_release(s->ctx)
virtio_scsi_acquire(s).return
virtio_scsi_handle_cmd_vq()
...
virtqueue_pop()
Is it possible that the above virtqueue_pop() still returns one element that was
queued before vm_shutdown() was called?
If so I think we additionally need to an "s->ioeventfd_stopped" flag set in
virtio_scsi_stop_ioeventfd() and check it in
virtio_scsi_data_plane_handle_cmd().
Fam
