IB/cm: Store and restore ah_attr during LAP msg processing

During CM LAP processing, ah_attr is reinitialized on receiving LAP
request. First likely during CM request processing.

ah_attr might get zero out if LAP processing fails.
Therefore, attempt to create new ah_attr for the LAP message.
If the initialization fails, continue with older ah_attr.
If the initialization passes, consider the new ah_attr by overwriting
the older one.
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/cm.c

@@ -452,6 +452,32 @@ static void cm_set_private_data(struct cm_id_private *cm_id_priv,
 	cm_id_priv->private_data_len = private_data_len;
 }
 
+static int cm_init_av_for_lap(struct cm_port *port, struct ib_wc *wc,
+			      struct ib_grh *grh, struct cm_av *av)
+{
+	struct rdma_ah_attr new_ah_attr;
+	int ret;
+
+	av->port = port;
+	av->pkey_index = wc->pkey_index;
+
+	/*
+	 * av->ah_attr might be initialized based on past wc during incoming
+	 * connect request or while sending out connect request. So initialize
+	 * a new ah_attr on stack. If initialization fails, old ah_attr is
+	 * used for sending any responses. If initialization is successful,
+	 * than new ah_attr is used by overwriting old one.
+	 */
+	ret = ib_init_ah_attr_from_wc(port->cm_dev->ib_device,
+				      port->port_num, wc,
+				      grh, &new_ah_attr);
+	if (ret)
+		return ret;
+
+	memcpy(&av->ah_attr, &new_ah_attr, sizeof(new_ah_attr));
+	return 0;
+}
+
 static int cm_init_av_for_response(struct cm_port *port, struct ib_wc *wc,
 				   struct ib_grh *grh, struct cm_av *av)
 {
@@ -3233,7 +3259,7 @@ static int cm_lap_handler(struct cm_work *work)
 		goto unlock;
 	}
 
-	ret = cm_init_av_for_response(work->port, work->mad_recv_wc->wc,
+	ret = cm_init_av_for_lap(work->port, work->mad_recv_wc->wc,
 				 work->mad_recv_wc->recv_buf.grh,
 				 &cm_id_priv->av);
 	if (ret)