From owner-svn-src-head@freebsd.org Thu Aug 27 17:19:24 2015 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 811A59C370B; Thu, 27 Aug 2015 17:19:24 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id EE0611287; Thu, 27 Aug 2015 17:19:23 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kostik@localhost [127.0.0.1]) by kib.kiev.ua (8.15.2/8.15.2) with ESMTPS id t7RHJJva093184 (version=TLSv1 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO); Thu, 27 Aug 2015 20:19:19 +0300 (EEST) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua t7RHJJva093184 Received: (from kostik@localhost) by tom.home (8.15.2/8.15.2/Submit) id t7RHJJKO093183; Thu, 27 Aug 2015 20:19:19 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Thu, 27 Aug 2015 20:19:18 +0300 From: Konstantin Belousov To: Julien Charbon Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, John Baldwin Subject: Re: svn commit: r286880 - head/sys/kern Message-ID: <20150827171918.GM2072@kib.kiev.ua> References: <201508181015.t7IAFAex055889@repo.freebsd.org> <55DD69E5.4090904@selasky.org> <55DD74EB.30601@selasky.org> <55DE01F7.8040508@freebsd.org> <20150827104946.GH2072@kib.kiev.ua> <55DF3A93.8080507@freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55DF3A93.8080507@freebsd.org> User-Agent: Mutt/1.5.23 (2014-03-12) X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on tom.home X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 27 Aug 2015 17:19:24 -0000 On Thu, Aug 27, 2015 at 06:28:03PM +0200, Julien Charbon wrote: > > Hi Konstantin, > > On 27/08/15 12:49, Konstantin Belousov wrote: > > On Wed, Aug 26, 2015 at 08:14:15PM +0200, Julien Charbon wrote: > >> As I said, I am not opposed to back out this change, callout(9) API in > >> mpsafe mode is a already complex/subtle API, it won't change too much > >> the current complexity. > >> > >> Let say that if nobody screams until Friday 8/28, I will put back > >> r284245 and revert this change _and_ I will make this case clear in the > >> man page. > > > > [Replying to a random message in the whole set of conversations] > > > > There is one more case, besides TCP timers, which is equially, of not > > more, critical and sensitive WRT to the callout_stop(). Look at the > > sys/kern/subr_sleepqueue.c:sleepq_check_timeout(). Stray return of > > the false result from callout_stop() causes creation of the non-killable > > processes: the callout fired, we missed the wakeup and went to sleep > > by manually doing the context switch. Such thread cannot be woken up. > > > > I suspect that your fix is a better approach than my attempt to look > > at something similar at PR 200992 (may be not). > > This change (r286880) won't improve the PR 200992: > > r286880 only addresses a case where callout_stop() returns 1 instead of > 0. Thus the only thing that can do r286880 to PR 200992: > > - Don't change anything the issues > - Worsen the issue > > Sorry to kill your hope of a simple and elegant fix for PR 200992. Well, not that I am frustrated much. Thank you for taking a look. Did you read the patch attached to the PR ?