From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: ebiederm@xmission.com (Eric W. Biederman) To: Willy Tarreau Cc: Luis Henriques , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Michal Tesar , "David S. Miller" , tyler.hicks@canonical.com References: <20140512003203.088027167@1wt.eu> <20140611184644.GA5442@hercules> <20140611194657.GU28551@1wt.eu> <87sinanv6u.fsf@canonical.com> <20140614175047.GH15102@1wt.eu> <87simzgrbs.fsf@x220.int.ebiederm.org> <20140620225827.GF9639@1wt.eu> Date: Fri, 20 Jun 2014 17:19:15 -0700 In-Reply-To: <20140620225827.GF9639@1wt.eu> (Willy Tarreau's message of "Sat, 21 Jun 2014 00:58:27 +0200") Message-ID: <87y4wrf724.fsf@x220.int.ebiederm.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [ 059/143] sysctl net: Keep tcp_syn_retries inside the boundary Sender: linux-kernel-owner@vger.kernel.org List-ID: Willy Tarreau writes: > Hi Eric, > > On Fri, Jun 20, 2014 at 03:16:07PM -0700, Eric W. Biederman wrote: >> Willy Tarreau writes: >> >> > Hi Luis, >> > >> > On Thu, Jun 12, 2014 at 01:55:53PM +0100, Luis Henriques wrote: >> >> I was finally able to spend some more time with this and tried (a >> >> modified) Tyler's patch on top of 2.6.32.62, and it seems to work. >> >> Although I haven't done any extended testing, I don't see the two >> >> stack traces and the /proc/sys/net/ipv4/ directory seems to be >> >> correctly populated. >> >> >> >> I'm attaching the patch I've used, based on Tyler's. >> > >> > Would any of you or Tyler please kindly pass me a signed-off-by with >> > a commit message ? That would be great. Alternately I'd do it myself >> > and mention you authored them. >> >> If my memory serves it is possibe in 2.6.32 to set >> .ctl_name = CTL_UNNEEDED >> >> and not need to implement a .strategy routine at all. > > Ah that's quite interesting, thanks for the tip! > >> Given the fact that most people got the strategy routines >> slightly wrong and that sys_sysctl is effectively unused >> a strategy where you don't implement code that no-one >> will use in a backport I would be preferable. > > OK. > >> Since you have mentioned this has come up a couple of times if something >> else this will be something to think about for next time. > > I'm keeping your e-mail where I manage patches, hoping to recognize > this case next time. > >> I am puzzled why .ctl_name was populated in a backport at all. > > Oh it's simply because I didn't know it did not have to be there, > and among the few reviewers, I guess that it's not common to know > what version uses what semantics. I guess what I meant is that the field .ctl_name does not even exist anymore for the same reasons .strategy does not exist anymore. So I was just suprirsed that someone picked a randomish number and stuck it in there. If anyone actually were to use those randomish numbers in the binary sys_sysctl call their applications would break when they eventually moved to a more recent kernel. Which is one of the motivations it was decided there would be no more binary sysctls allocated around the 2.6.32 timeframe. > Thank you for the exaplanation, it's really helpful. We're not used > to backport sysctl changes but here I got caught a few times and have > found some sysctl.conf with bogus values in field a few times, so it > was really important to backport this one. Sysctl do have their uses, and at least 2.6.32 has runtime sysctl checks to keep the insanity to a dull roar. Eric