staging: most: hdm-usb: reduce context of list_del mutex

This patch reduces context of the list_del mutex for the function
hdm_enqueue().
Signed-off-by: Andrey Shvetsov <andrey.shvetsov@k2l.de>
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/most/hdm-usb/hdm_usb.c

@@ -663,15 +663,11 @@ static int hdm_enqueue(struct most_interface *iface, int channel,
 	init_completion(&anchor->urb_compl);
 	mbo->priv = anchor;
 
-	spin_lock_irqsave(&mdev->anchor_list_lock[channel], flags);
-	list_add_tail(&anchor->list, &mdev->anchor_list[channel]);
-	spin_unlock_irqrestore(&mdev->anchor_list_lock[channel], flags);
-
 	if ((mdev->padding_active[channel]) &&
 	    (conf->direction & MOST_CH_TX))
 		if (hdm_add_padding(mdev, channel, mbo)) {
 			retval = -EIO;
-			goto _error_1;
+			goto _error;
 		}
 
 	urb->transfer_dma = mbo->bus_address;
@@ -699,6 +695,10 @@ static int hdm_enqueue(struct most_interface *iface, int channel,
 	}
 	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 
+	spin_lock_irqsave(&mdev->anchor_list_lock[channel], flags);
+	list_add_tail(&anchor->list, &mdev->anchor_list[channel]);
+	spin_unlock_irqrestore(&mdev->anchor_list_lock[channel], flags);
+
 	retval = usb_submit_urb(urb, GFP_KERNEL);
 	if (retval) {
 		dev_err(dev, "URB submit failed with error %d.\n", retval);