virtio_rpmsg: set DRIVER_OK before using device
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@redhat.com>
Acked-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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 @@
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 @@
}
}
+ /*
+ * 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");