mei: move write cb to completion on credentials failures

commit e09ee853 upstream.

The credentials handling was pushed to the write handlers
but error handling wasn't done properly.
Move write callbacks to completion queue to destroy them
and to notify a blocked writer about the failure

Fixes: 136698e5 (mei: push credentials inside the irq write handler)
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/misc/mei/client.c

@@ -819,7 +819,7 @@ int mei_cl_irq_write(struct mei_cl *cl, struct mei_cl_cb *cb,
 
 	rets = mei_cl_flow_ctrl_creds(cl);
 	if (rets < 0)
-		return rets;
+		goto err;
 
 	if (rets == 0) {
 		cl_dbg(dev, cl, "No flow control credentials: not sending.\n");
@@ -853,23 +853,27 @@ int mei_cl_irq_write(struct mei_cl *cl, struct mei_cl_cb *cb,
 			cb->request_buffer.size, cb->buf_idx);
 
 	rets = mei_write_message(dev, &mei_hdr, buf->data + cb->buf_idx);
-	if (rets) {
-		cl->status = rets;
-		list_move_tail(&cb->list, &cmpl_list->list);
-		return rets;
-	}
+	if (rets)
+		goto err;
 
 	cl->status = 0;
 	cl->writing_state = MEI_WRITING;
 	cb->buf_idx += mei_hdr.length;
 
 	if (mei_hdr.msg_complete) {
-		if (mei_cl_flow_ctrl_reduce(cl))
-			return -EIO;
+		if (mei_cl_flow_ctrl_reduce(cl)) {
+			rets = -EIO;
+			goto err;
+		}
 		list_move_tail(&cb->list, &dev->write_waiting_list.list);
 	}
 
 	return 0;
+
+err:
+	cl->status = rets;
+	list_move_tail(&cb->list, &cmpl_list->list);
+	return rets;
 }
 
 /**