[SCSI] scsi_dh: Change the scsidh_activate interface to be asynchronous

Make scsi_dh_activate() function asynchronous, by taking in two additional
parameters, one is the callback function and the other is the data to call
the callback function with.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
diff --git a/drivers/scsi/device_handler/scsi_dh_hp_sw.c b/drivers/scsi/device_handler/scsi_dh_hp_sw.c
index f7da753..0aacafc 100644
--- a/drivers/scsi/device_handler/scsi_dh_hp_sw.c
+++ b/drivers/scsi/device_handler/scsi_dh_hp_sw.c
@@ -268,7 +268,8 @@
  * activate the passive path (and deactivate the
  * previously active one).
  */
-static int hp_sw_activate(struct scsi_device *sdev)
+static int hp_sw_activate(struct scsi_device *sdev,
+				activate_complete fn, void *data)
 {
 	int ret = SCSI_DH_OK;
 	struct hp_sw_dh_data *h = get_hp_sw_data(sdev);
@@ -283,7 +284,9 @@
 				    HP_SW_NAME);
 	}
 
-	return ret;
+	if (fn)
+		fn(data, ret);
+	return 0;
 }
 
 static const struct scsi_dh_devlist hp_sw_dh_data_list[] = {