From owner-svn-src-head@FreeBSD.ORG Thu May 3 11:49:22 2012 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id A57C31065674; Thu, 3 May 2012 11:49:22 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.zoral.com.ua (mx0.zoral.com.ua [91.193.166.200]) by mx1.freebsd.org (Postfix) with ESMTP id 200E08FC17; Thu, 3 May 2012 11:49:21 +0000 (UTC) Received: from skuns.kiev.zoral.com.ua (localhost [127.0.0.1]) by mail.zoral.com.ua (8.14.2/8.14.2) with ESMTP id q43BnEPQ082065; Thu, 3 May 2012 14:49:14 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.5/8.14.5) with ESMTP id q43BnD7U026953; Thu, 3 May 2012 14:49:13 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.5/8.14.5/Submit) id q43BnDv0026952; Thu, 3 May 2012 14:49:13 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Thu, 3 May 2012 14:49:13 +0300 From: Konstantin Belousov To: Attilio Rao Message-ID: <20120503114913.GJ2358@deviant.kiev.zoral.com.ua> References: <201205031038.q43Ac2eZ032779@svn.freebsd.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="VSonL41MObbAuehL" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: clamav-milter 0.95.2 at skuns.kiev.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-4.0 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on skuns.kiev.zoral.com.ua Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r234952 - in head/sys: kern sys X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 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 May 2012 11:49:22 -0000 --VSonL41MObbAuehL Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 03, 2012 at 12:02:08PM +0100, Attilio Rao wrote: > 2012/5/3, Konstantin Belousov : > > Author: kib > > Date: Thu May 3 10:38:02 2012 > > New Revision: 234952 > > URL: http://svn.freebsd.org/changeset/base/234952 > > > > Log: > > When callout_reset_on() cannot immediately migrate a callout since it > > is running on other cpu, the CALLOUT_PENDING flag is temporarily > > cleared. Then, callout_stop() on this, in fact active, callout fails > > because CALLOUT_PENDING is not set, and callout_stop() returns 0. > > > > Now, in sleepq_check_timeout(), the failed callout_stop() causes the > > sleepq code to execute mi_switch() without even setting the wmesg, > > since the switch-out is supposed to be transient. In fact, the thread > > is put off the CPU for full timeout interval, instead of being put on > > runq immediately. Until timeout fires, the process is unkillable for > > obvious reasons. > > > > Fix this by marking the migrating callouts with CALLOUT_DFRMIGRATION > > flag. The flag is cleared by callout_stop_safe() when the function > > detects a migration, besides returning the success. The softclock() > > rechecks the flag for migrating callout and cancels its execution if > > the flag was cleared meantime. >=20 > Can you please clarify why you cannot simply drop the deferred > migration in the case !CALLOUT_PENDING in callout_stop_safe()? I probably can, I think I went with the route of committed patch because it is slightly less work. Also, the comment in the while() loop suggested me to rely on softclock. --VSonL41MObbAuehL Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (FreeBSD) iEYEARECAAYFAk+icLkACgkQC3+MBN1Mb4ifBgCguBFmr3XD/vfD28mhzWhtEXC0 3toAoMDSGc/ElSj2X5E+Y1QGocG/Gd1a =NClt -----END PGP SIGNATURE----- --VSonL41MObbAuehL--