smb: smbdirect: wrap rdma_disconnect() in rdma_[un]lock_handler()

This might not be needed, but it controls the order
of ib_drain_qp() and rdma_disconnect().

Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: metze-samba

fs/smb/common/smbdirect/smbdirect_socket.c

@@ -474,7 +474,20 @@ static void smbdirect_socket_cleanup_work(struct work_struct *work)
 	case SMBDIRECT_SOCKET_CONNECTED:
 	case SMBDIRECT_SOCKET_ERROR:
 		sc->status = SMBDIRECT_SOCKET_DISCONNECTING;
+		/*
+		 * Make sure we hold the callback lock
+		 * im order to coordinate with the
+		 * rdma_event handlers, typically
+		 * smbdirect_connection_rdma_event_handler(),
+		 * and smbdirect_socket_destroy().
+		 *
+		 * So that the order of ib_drain_qp()
+		 * and rdma_disconnect() is controlled
+		 * by the mutex.
+		 */
+		rdma_lock_handler(sc->rdma.cm_id);
 		rdma_disconnect(sc->rdma.cm_id);
+		rdma_unlock_handler(sc->rdma.cm_id);
 		break;
 
 	case SMBDIRECT_SOCKET_CREATED: