Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761544AbZANJsD (ORCPT ); Wed, 14 Jan 2009 04:48:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757217AbZANJrx (ORCPT ); Wed, 14 Jan 2009 04:47:53 -0500 Received: from pan.madism.org ([88.191.52.104]:45979 "EHLO hermes.madism.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755690AbZANJrw (ORCPT ); Wed, 14 Jan 2009 04:47:52 -0500 X-Greylist: delayed 344 seconds by postgrey-1.27 at vger.kernel.org; Wed, 14 Jan 2009 04:47:52 EST From: Pierre Habouzit To: Wei Yongjun , Vlad Yasevich , " David S. Miller" Cc: linux-kernel@vger.kernel.org, Pierre Habouzit Subject: [PATCH] sctp: if backlog is 0, listening shall not be deactivated. Date: Wed, 14 Jan 2009 10:42:03 +0100 Message-Id: <1231926123-26196-1-git-send-email-pierre.habouzit@intersec.com> X-Mailer: git-send-email 1.6.1.161.g5e07b.dirty Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2679 Lines: 92 POSIX hints that when 0 is used for the listen backlog argument, the kernel shall chose a default automatic value. TCP for example, works this way. Signed-off-by: Pierre Habouzit --- net/sctp/socket.c | 20 -------------------- 1 files changed, 0 insertions(+), 20 deletions(-) To put a bit of background, I stumbled against this while doing a code that basically did: struct sctp_event_subscribe events; /* ... */ fd = socket(AF_INET, SOCK_SEQPACKETS, IPPROTO_SCTP); sctp_bindx(fd, ....); events = (struct sctp_event_subscribe){ .sctp_data_io_event = 1, .sctp_association_event = 1, }; setsockopt(fd, SOL_SCTP, SCTP_EVENTS, &events, sizeof(events)); listen(fd, 0); len = sctp_recvmsg(fd, .....); The latter call instead of blocking like I expected returned with errno == ENOTCONN. I know POSIX doesn't _require_ listen() to accept 0 as a valid backlog, but the other listen() implementation I have used in the kernel do, and it looks really surprising for the programmer (who really searches the error elsewhere). Fortunately I had another working code at hand and I managed to find the problem resorting to reverting the changes I made to the original code line per line (*sigh*). I'm unsure if the diff shouldn't do instead: if (!backlog) backlog = 1; I'm not really comfortable around the kernel core ;) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index ff0a8f8..da1d96a 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -5866,16 +5866,6 @@ SCTP_STATIC int sctp_seqpacket_listen(struct sock *sk, int backlog) if (!sctp_style(sk, UDP)) return -EINVAL; - /* If backlog is zero, disable listening. */ - if (!backlog) { - if (sctp_sstate(sk, CLOSED)) - return 0; - - sctp_unhash_endpoint(ep); - sk->sk_state = SCTP_SS_CLOSED; - return 0; - } - /* Return if we are already listening. */ if (sctp_sstate(sk, LISTENING)) return 0; @@ -5919,16 +5909,6 @@ SCTP_STATIC int sctp_stream_listen(struct sock *sk, int backlog) struct sctp_sock *sp = sctp_sk(sk); struct sctp_endpoint *ep = sp->ep; - /* If backlog is zero, disable listening. */ - if (!backlog) { - if (sctp_sstate(sk, CLOSED)) - return 0; - - sctp_unhash_endpoint(ep); - sk->sk_state = SCTP_SS_CLOSED; - return 0; - } - if (sctp_sstate(sk, LISTENING)) return 0; -- 1.6.1.161.g5e07b.dirty -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/