From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: [PATCH] sctp: make the max_burst min value to 1 Date: Mon, 02 Dec 2013 09:51:43 -0500 Message-ID: <529C9E7F.7040707@gmail.com> References: <529C2E01.3090005@huawei.com> <20131202115640.GA10857@hmsreliant.think-freely.org> <529C7707.5020908@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: David Miller , linux-sctp@vger.kernel.org, netdev@vger.kernel.org, dingtianhong@huawei.com To: Wang Weidong , Neil Horman Return-path: Received: from mail-yh0-f49.google.com ([209.85.213.49]:48291 "EHLO mail-yh0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751963Ab3LBOvq (ORCPT ); Mon, 2 Dec 2013 09:51:46 -0500 In-Reply-To: <529C7707.5020908@huawei.com> Sender: netdev-owner@vger.kernel.org List-ID: On 12/02/2013 07:03 AM, Wang Weidong wrote: > On 2013/12/2 19:56, Neil Horman wrote: >> On Mon, Dec 02, 2013 at 02:51:45PM +0800, Wang Weidong wrote: >>> From: Wang Weidong >>> >>> when I setted the max_burst to 0, do the lksctp-tools I got hang. >>> I found sctp_transport_burst_limited would make the cwnd to 0. >>> so I make the max_burst min value to 1. >>> Signed-off-by: Wang Weidong >>> --- >>> net/sctp/sysctl.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c >>> index 7637e8e..46832d3 100644 >>> --- a/net/sctp/sysctl.c >>> +++ b/net/sctp/sysctl.c >>> @@ -135,7 +135,7 @@ static struct ctl_table sctp_net_table[] = { >>> .maxlen = sizeof(int), >>> .mode = 0644, >>> .proc_handler = proc_dointvec_minmax, >>> - .extra1 = &zero, >>> + .extra1 = &one, >>> .extra2 = &int_max >>> }, >>> { >>> -- >>> 1.7.12 >>> >>> >> >> >> This seems like a band-aid to me. There are a few things wrong: >> >> 1) You can also set the the max_burst via setsockopt, and so this would need to >> be checked in that path as well. >> >> 2) I don't see how having a cwnd of zero would cause a hang. It looks like a >> cwnd of zero would perpetually place the association in a slow start state, >> which is silly but not illegal. >> > > Hm, Good suggestions. Ok, I will try it again and find the root cause. > Thanks! It's really simple. sctp_transport_burst_limited() should simply do nothing if max_burst is 0, essentially allowing unlimited bursts. -vlad > >> Please investigate the acutally root cause of the problem before just avoiding >> it like this. >> >> Thanks! >> Neil >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-sctp" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> > >