IB/ipath: fix race with exposing reset file

We were accidentally exposing the "reset" sysfs file more than once
per device.

Signed-off-by: Bryan O'Sullivan <bos@pathscale.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/ipath/ipath_diag.c b/drivers/infiniband/hw/ipath/ipath_diag.c
index 7d3fb69..28ddceb 100644
--- a/drivers/infiniband/hw/ipath/ipath_diag.c
+++ b/drivers/infiniband/hw/ipath/ipath_diag.c
@@ -277,13 +277,14 @@
 
 bail:
 	spin_unlock_irqrestore(&ipath_devs_lock, flags);
-	mutex_unlock(&ipath_mutex);
 
 	/* Only expose a way to reset the device if we
 	   make it into diag mode. */
 	if (ret == 0)
 		ipath_expose_reset(&dd->pcidev->dev);
 
+	mutex_unlock(&ipath_mutex);
+
 	return ret;
 }