xen-fbfront: handle backend CLOSED without CLOSING

Backend drivers shouldn't transistion to CLOSED unless the frontend is
CLOSED.  If a backend does transition to CLOSED too soon then the
frontend may not see the CLOSING state and will not properly shutdown.

So, treat an unexpected backend CLOSED state the same as CLOSING.

Acked-by: Florian Tobias Schandinat <[email protected]>
Signed-off-by: David Vrabel <[email protected]>
Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>

diff --git a/drivers/video/xen-fbfront.c b/drivers/video/xen-fbfront.c
index b7f5173ff9e94214ed40c3c40f4444324e128888..917bb5681684d31490e1b228b60db57cc0d53a7b 100644 (file)
--- a/drivers/video/xen-fbfront.c
+++ b/drivers/video/xen-fbfront.c
@@ -641,7 +641,6 @@ static void xenfb_backend_changed(struct xenbus_device *dev,
        case XenbusStateReconfiguring:
        case XenbusStateReconfigured:
        case XenbusStateUnknown:
-       case XenbusStateClosed:
                break;
 
        case XenbusStateInitWait:
@@ -670,6 +669,10 @@ InitWait:
                info->feature_resize = val;
                break;
 
+       case XenbusStateClosed:
+               if (dev->state == XenbusStateClosed)
+                       break;
+               /* Missed the backend's CLOSING state -- fallthrough */
        case XenbusStateClosing:
                xenbus_frontend_closed(dev);
                break;