Commit 80c6eed4 authored Aug 01, 2012 by Philipp Reisner

drbd: More random to the connect logic



Since the listening socket is open all the time, it was possible to
get into stable "initial packet S crossed" loops.

* when both sides realize in the drbd_socket_okay() call at the end
  of the loop that the other side closed the main socket you had
  the chance to get into a stable loop with repeated "packet S crossed"
  messages.

* when both sides do not realize with the drbd_socket_okay() call at the end
  of the loop that the other side closed the main socket you had
  the chance to get into a stable loop with alternating "packet S crossed"
  "packet M crossed" messages.

In order to break out these stable loops randomize the behaviour if
such a crossing of P_INITIAL_DATA or P_INITIAL_META packets is detected.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

parent 92f14951

drivers/block/drbd/drbd_receiver.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -949,20 +949,25 @@ static int conn_connect(struct drbd_tconn *tconn)
		if (sock.socket) {
		conn_warn(tconn, "initial packet S crossed\n");
		sock_release(sock.socket);
		sock.socket = s;
		goto randomize;
		}
		sock.socket = s;
		break;
		case P_INITIAL_META:
		set_bit(DISCARD_CONCURRENT, &tconn->flags);
		if (msock.socket) {
		conn_warn(tconn, "initial packet M crossed\n");
		sock_release(msock.socket);
		msock.socket = s;
		goto randomize;
		}
		msock.socket = s;
		set_bit(DISCARD_CONCURRENT, &tconn->flags);
		break;
		default:
		conn_warn(tconn, "Error receiving initial packet\n");
		sock_release(s);
		randomize:
		if (random32() & 1)
		goto retry;
		}