RDMA/siw: Fix potential NULL de-ref

In siw_connect() we have an error flow where there is no valid qp
pointer.  Make sure we don't try to de-ref in that situation.

Fixes: 6c52fdc2 ("rdma/siw: connection management")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Bernard Metzler <bmt@zurich.ibm.com>
Link: https://lore.kernel.org/r/20190819140257.19319-1-bmt@zurich.ibm.comSigned-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/siw/siw_cm.c

@@ -1515,7 +1515,7 @@ int siw_connect(struct iw_cm_id *id, struct iw_cm_conn_param *params)
 		}
 	}
 error:
-	siw_dbg_qp(qp, "failed: %d\n", rv);
+	siw_dbg(id->device, "failed: %d\n", rv);
 
 	if (cep) {
 		siw_socket_disassoc(s);
@@ -1540,7 +1540,8 @@ int siw_connect(struct iw_cm_id *id, struct iw_cm_conn_param *params)
 	} else if (s) {
 		sock_release(s);
 	}
-	siw_qp_put(qp);
+	if (qp)
+		siw_qp_put(qp);
 
 	return rv;
 }