From owner-svn-src-head@FreeBSD.ORG Fri Aug 27 21:54:16 2010 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 EB91210656A8; Fri, 27 Aug 2010 21:54:16 +0000 (UTC) (envelope-from pjd@garage.freebsd.pl) Received: from mail.garage.freebsd.pl (60.wheelsystems.com [83.12.187.60]) by mx1.freebsd.org (Postfix) with ESMTP id 929248FC1F; Fri, 27 Aug 2010 21:54:16 +0000 (UTC) Received: by mail.garage.freebsd.pl (Postfix, from userid 65534) id A1D6E45EE5; Fri, 27 Aug 2010 23:54:14 +0200 (CEST) Received: from localhost (chello089077043238.chello.pl [89.77.43.238]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.garage.freebsd.pl (Postfix) with ESMTP id 9DF1945EA4; Fri, 27 Aug 2010 23:54:08 +0200 (CEST) Date: Fri, 27 Aug 2010 23:54:02 +0200 From: Pawel Jakub Dawidek To: Kostik Belousov Message-ID: <20100827215402.GB2077@garage.freebsd.pl> References: <201008272049.o7RKn63o007138@svn.freebsd.org> <20100827213827.GD2396@deviant.kiev.zoral.com.ua> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="TakKZr9L6Hm6aLOc" Content-Disposition: inline In-Reply-To: <20100827213827.GD2396@deviant.kiev.zoral.com.ua> User-Agent: Mutt/1.4.2.3i X-PGP-Key-URL: http://people.freebsd.org/~pjd/pjd.asc X-OS: FreeBSD 9.0-CURRENT amd64 X-Spam-Checker-Version: SpamAssassin 3.0.4 (2005-06-05) on mail.garage.freebsd.pl X-Spam-Level: X-Spam-Status: No, score=-0.6 required=4.5 tests=BAYES_00,RCVD_IN_SORBS_DUL autolearn=no version=3.0.4 Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r211896 - head/sbin/hastd 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: Fri, 27 Aug 2010 21:54:17 -0000 --TakKZr9L6Hm6aLOc Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Aug 28, 2010 at 12:38:27AM +0300, Kostik Belousov wrote: > > --- head/sbin/hastd/primary.c Fri Aug 27 20:48:12 2010 (r211895) > > +++ head/sbin/hastd/primary.c Fri Aug 27 20:49:06 2010 (r211896) > > @@ -1988,7 +1988,9 @@ guard_thread(void *arg) > > rw_unlock(&hio_remote_lock[ii]); > > } > > } > > - (void)cv_timedwait(&hio_guard_cond, &hio_guard_lock, timeout); > > + /* Sleep only if a signal wasn't delivered in the meantime. */ > > + if (!sigexit_received && !sighup_received && !sigchld_received) > > + cv_timedwait(&hio_guard_cond, &hio_guard_lock, timeout); > > mtx_unlock(&hio_guard_lock); > > } > > /* NOTREACHED */ > I wanted to say that this is racy, because if a signal is delivered after > the check is done but before the sleep, you loose. Yes, I know it is racy, but the race isn't critical anymore, as we will eventually wait at most 10 seconds to handle signals. > After looking at the signal handler, I noted that you call not async-safe > functions in the handler. This is easy way to get undefined behaviour, > i.e. probably crash. And wakeup from the handler would have the same > race as sigXXX_received check. Which aren't async-safe? pthread stuff? --=20 Pawel Jakub Dawidek http://www.wheelsystems.com pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! --TakKZr9L6Hm6aLOc Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (FreeBSD) iEYEARECAAYFAkx4M/oACgkQForvXbEpPzSemQCePvHcTbrskj5kyX4ZspOgCWoh /iYAnAsnL57koDHXhA3063IMp9YU5jcJ =2+VM -----END PGP SIGNATURE----- --TakKZr9L6Hm6aLOc--