"Michael S. Tsirkin" <mst@xxxxxxxxxx> writes: > virtio spec requires that all drivers set DRIVER_OK > before using devices. While rpmsg isn't yet > included in the virtio 1 spec, previous spec versions > also required this. > > virtio rpmsg violates this rule: is calls kick > before setting DRIVER_OK. > > The fix isn't trivial since simply calling virtio_device_ready earlier > would mean we might get an interrupt in parallel with adding buffers. > > Instead, split kick out to prepare+notify calls. prepare before > virtio_device_ready - when we know we won't get interrupts. notify right > afterwards. > > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Applied. I'll wait for Ohad to ack before sending to Linus. BTW I assume you have a version of qemu which warns on these kind of failures? That'd be nice to have! Thanks, Rusty. > --- > > Note: compile-tested only. > > drivers/rpmsg/virtio_rpmsg_bus.c | 17 ++++++++++++++++- > 1 file changed, 16 insertions(+), 1 deletion(-) > > diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c > index 92f6af6..73354ee 100644 > --- a/drivers/rpmsg/virtio_rpmsg_bus.c > +++ b/drivers/rpmsg/virtio_rpmsg_bus.c > @@ -951,6 +951,7 @@ static int rpmsg_probe(struct virtio_device *vdev) > void *bufs_va; > int err = 0, i; > size_t total_buf_space; > + bool notify; > > vrp = kzalloc(sizeof(*vrp), GFP_KERNEL); > if (!vrp) > @@ -1030,8 +1031,22 @@ static int rpmsg_probe(struct virtio_device *vdev) > } > } > > + /* > + * Prepare to kick but don't notify yet - we can't do this before > + * device is ready. > + */ > + notify = virtqueue_kick_prepare(vrp->rvq); > + > + /* From this point on, we can notify and get callbacks. */ > + virtio_device_ready(vdev); > + > /* tell the remote processor it can start sending messages */ > - virtqueue_kick(vrp->rvq); > + /* > + * this might be concurrent with callbacks, but we are only > + * doing notify, not a full kick here, so that's ok. > + */ > + if (notify) > + virtqueue_notify(vrp->rvq); > > dev_info(&vdev->dev, "rpmsg host is online\n"); > > -- > MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
