diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c
index 53a31c7..20c4557 100644
--- a/drivers/scsi/device_handler/scsi_dh_rdac.c
+++ b/drivers/scsi/device_handler/scsi_dh_rdac.c
@@ -364,10 +364,7 @@
 	struct rdac_controller *ctlr;
 	ctlr = container_of(kref, struct rdac_controller, kref);
 
-	flush_workqueue(kmpath_rdacd);
-	spin_lock(&list_lock);
 	list_del(&ctlr->node);
-	spin_unlock(&list_lock);
 	kfree(ctlr);
 }
 
@@ -376,20 +373,17 @@
 {
 	struct rdac_controller *ctlr, *tmp;
 
-	spin_lock(&list_lock);
-
 	list_for_each_entry(tmp, &ctlr_list, node) {
 		if ((memcmp(tmp->array_id, array_id, UNIQUE_ID_LEN) == 0) &&
 			  (tmp->index == index) &&
 			  (tmp->host == sdev->host)) {
 			kref_get(&tmp->kref);
-			spin_unlock(&list_lock);
 			return tmp;
 		}
 	}
 	ctlr = kmalloc(sizeof(*ctlr), GFP_ATOMIC);
 	if (!ctlr)
-		goto done;
+		return NULL;
 
 	/* initialize fields of controller */
 	memcpy(ctlr->array_id, array_id, UNIQUE_ID_LEN);
@@ -405,8 +399,7 @@
 	INIT_WORK(&ctlr->ms_work, send_mode_select);
 	INIT_LIST_HEAD(&ctlr->ms_head);
 	list_add(&ctlr->node, &ctlr_list);
-done:
-	spin_unlock(&list_lock);
+
 	return ctlr;
 }
 
@@ -517,9 +510,12 @@
 			index = 0;
 		else
 			index = 1;
+
+		spin_lock(&list_lock);
 		h->ctlr = get_controller(index, array_name, array_id, sdev);
 		if (!h->ctlr)
 			err = SCSI_DH_RES_TEMP_UNAVAIL;
+		spin_unlock(&list_lock);
 	}
 	return err;
 }
@@ -906,7 +902,9 @@
 	return 0;
 
 clean_ctlr:
+	spin_lock(&list_lock);
 	kref_put(&h->ctlr->kref, release_controller);
+	spin_unlock(&list_lock);
 
 failed:
 	kfree(scsi_dh_data);
@@ -921,14 +919,19 @@
 	struct rdac_dh_data *h;
 	unsigned long flags;
 
-	spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
 	scsi_dh_data = sdev->scsi_dh_data;
+	h = (struct rdac_dh_data *) scsi_dh_data->buf;
+	if (h->ctlr && h->ctlr->ms_queued)
+		flush_workqueue(kmpath_rdacd);
+
+	spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
 	sdev->scsi_dh_data = NULL;
 	spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
 
-	h = (struct rdac_dh_data *) scsi_dh_data->buf;
+	spin_lock(&list_lock);
 	if (h->ctlr)
 		kref_put(&h->ctlr->kref, release_controller);
+	spin_unlock(&list_lock);
 	kfree(scsi_dh_data);
 	module_put(THIS_MODULE);
 	sdev_printk(KERN_NOTICE, sdev, "%s: Detached\n", RDAC_NAME);