xen-blkfront: handle backend CLOSED without CLOSING

commit 3661371701e714f0cea4120f6a365340858fb4e4 upstream.

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.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 69b45fc9727680e796951e1afe6f5de0b21350bb..1735b0d17e29686d189b13c6e5f52ab7fb29d0a1 100644 (file)
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1518,13 +1518,16 @@ static void blkback_changed(struct xenbus_device *dev,
        case XenbusStateReconfiguring:
        case XenbusStateReconfigured:
        case XenbusStateUnknown:
-       case XenbusStateClosed:
                break;
 
        case XenbusStateConnected:
                blkfront_connect(info);
                break;
 
+       case XenbusStateClosed:
+               if (dev->state == XenbusStateClosed)
+                       break;
+               /* Missed the backend's Closing state -- fallthrough */
        case XenbusStateClosing:
                blkfront_closing(info);
                break;