From owner-svn-src-head@freebsd.org Thu Mar 3 12:41:45 2016 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 78B5B7D24; Thu, 3 Mar 2016 12:41:45 +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 EE1C3EA4; Thu, 3 Mar 2016 12:41:44 +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 u23Cfc3T069890 (version=TLSv1 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO); Thu, 3 Mar 2016 14:41:39 +0200 (EET) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua u23Cfc3T069890 Received: (from kostik@localhost) by tom.home (8.15.2/8.15.2/Submit) id u23Cfcph069888; Thu, 3 Mar 2016 14:41:38 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Thu, 3 Mar 2016 14:41:38 +0200 From: Konstantin Belousov To: Hans Petter Selasky Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r296320 - in head/sys: kern sys Message-ID: <20160303124138.GS67250@kib.kiev.ua> References: <201603021846.u22IkHWM010861@repo.freebsd.org> <56D82E45.3090205@selasky.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56D82E45.3090205@selasky.org> User-Agent: Mutt/1.5.24 (2015-08-30) 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: 2.1.21 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, 03 Mar 2016 12:41:45 -0000 On Thu, Mar 03, 2016 at 01:29:57PM +0100, Hans Petter Selasky wrote: > On 03/02/16 19:46, Konstantin Belousov wrote: > > Modified: head/sys/kern/subr_sleepqueue.c > > ============================================================================== > > --- head/sys/kern/subr_sleepqueue.c Wed Mar 2 16:36:24 2016 (r296319) > > +++ head/sys/kern/subr_sleepqueue.c Wed Mar 2 18:46:17 2016 (r296320) > > @@ -586,7 +586,8 @@ sleepq_check_timeout(void) > > * another CPU, so synchronize with it to avoid having it > > * accidentally wake up a subsequent sleep. > > */ > > - else if (callout_stop(&td->td_slpcallout) == 0) { > > + else if (_callout_stop_safe(&td->td_slpcallout, CS_MIGRBLOCK, NULL) > > + == 0) { > > td->td_flags |= TDF_TIMEOUT; > > TD_SET_SLEEPING(td); > > mi_switch(SW_INVOL | SWT_SLEEPQTIMO, NULL); > > The "td_slpcallout" is not drained anywhere, last time I checked. Does > this change require draining of the td_slpcallout in case the thread > immediately is exited/destroyed? callout_stop_safe(CS_MIGRBLOCK) is enough in this case. td_slpcallout is only reset from the sleepq code, and the fragment you cited is enough to guarantee that no spurious wakeup of the unrelated time-bound sleep happens, because TDF_TIMOFAIL flag cannot be cleared after that. Struct thread memory is type-stable, so callout subsystem never operates on the freed memory from td_slpcallout.