From owner-svn-src-head@FreeBSD.ORG Mon Jun 14 10:44:42 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 8FCAE1065670; Mon, 14 Jun 2010 10:44:42 +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 25F768FC1C; Mon, 14 Jun 2010 10:44:41 +0000 (UTC) Received: from deviant.kiev.zoral.com.ua (root@deviant.kiev.zoral.com.ua [10.1.1.148]) by mail.zoral.com.ua (8.14.2/8.14.2) with ESMTP id o5EAhntb020362 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 14 Jun 2010 13:43:49 +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 (8.14.4/8.14.4) with ESMTP id o5EAhnje007869; Mon, 14 Jun 2010 13:43:49 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.4/8.14.4/Submit) id o5EAhnx3007868; Mon, 14 Jun 2010 13:43:49 +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: Mon, 14 Jun 2010 13:43:49 +0300 From: Kostik Belousov To: Lawrence Stewart Message-ID: <20100614104349.GF13238@deviant.kiev.zoral.com.ua> References: <201006130239.o5D2du3m086332@svn.freebsd.org> <20100613101025.GD1320@garage.freebsd.pl> <4C158B71.205@freebsd.org> <20100614085205.GD13238@deviant.kiev.zoral.com.ua> <4C1605A7.2000202@freebsd.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="VuBTcNUPe5zwk2q6" Content-Disposition: inline In-Reply-To: <4C1605A7.2000202@freebsd.org> 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=-2.3 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_50, DNS_FROM_OPENWHOIS autolearn=no 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, Pawel Jakub Dawidek Subject: Re: svn commit: r209119 - head/sys/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: Mon, 14 Jun 2010 10:44:42 -0000 --VuBTcNUPe5zwk2q6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jun 14, 2010 at 08:34:15PM +1000, Lawrence Stewart wrote: > On 06/14/10 18:52, Kostik Belousov wrote: > >On Mon, Jun 14, 2010 at 11:52:49AM +1000, Lawrence Stewart wrote: > >>On 06/13/10 20:10, Pawel Jakub Dawidek wrote: > >>>On Sun, Jun 13, 2010 at 02:39:55AM +0000, Lawrence Stewart wrote: > >>[snip] > >>>> > >>>>Modified: head/sys/sys/pcpu.h > >>>>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D > >>>>--- head/sys/sys/pcpu.h Sun Jun 13 01:27:29 2010 (r209118) > >>>>+++ head/sys/sys/pcpu.h Sun Jun 13 02:39:55 2010 (r209119) > >>>>@@ -106,6 +106,17 @@ extern uintptr_t dpcpu_off[]; > >>>> #define DPCPU_ID_GET(i, n) (*DPCPU_ID_PTR(i, n)) > >>>> #define DPCPU_ID_SET(i, n, v) (*DPCPU_ID_PTR(i, n) =3D v) > >>>> > >>>>+/* > >>>>+ * Utility macros. > >>>>+ */ > >>>>+#define DPCPU_SUM(n, var, sum) \ > >>>>+do { \ > >>>>+ (sum) =3D 0; \ > >>>>+ u_int i; \ > >>>>+ CPU_FOREACH(i) \ > >>>>+ (sum) +=3D (DPCPU_ID_PTR(i, n))->var; \ > >>>>+} while (0) > >>> > >>>I'd suggest first swapping variable declaration and '(sum) =3D 0;'. > >>>Also using 'i' as a counter in macro can easly lead to name collision. > >>>If you need to do it, I'd suggest '_i' or something. > >> > >>Given that the DPCPU variable name space is flat and variable names have > >>to be unique, perhaps something like the following would address the > >>concerns raised? > >> > >>#define DPCPU_SUM(n, var, sum) \ > >>do { \ > >> u_int _##n##_i; = \ > >> (sum) =3D 0; = \ > >> CPU_FOREACH(_##n##_i) = \ > >> (sum) +=3D (DPCPU_ID_PTR(_##n##_i, n))->var; = \ > >>} while (0) > > > >You do not have to jump through this. Mostly by convention, in our kernel > >sources, names with "_" prefix are reserved for the infrastructure (cann= ot > >say implementation). I think it is quite safe to use _i for the iteration > >variable. > > > >As an example of this, look at sys/sys/mount.h, implementation of > >VFS_NEEDGIANT, VFS_LOCK_GIANT etc macros. They do use gcc ({}) extension > >to provide function-like macros, but this is irrelevant. Or, look at > >the VFS_ASSERT_GIANT that is exactly like what you need. >=20 > Ok cool, thanks for the info and pointers (I didn't know about the ({})= =20 > extension or that "_" prefix was definitely reserved). I'm happy to use= =20 > _i. Does the following diff against head look suitable to commit? >=20 > --- a/sys/sys/pcpu.h Sun Jun 13 02:39:55 2010 +0000 > +++ b/sys/sys/pcpu.h Mon Jun 14 20:12:27 2010 +1000 > @@ -111,10 +111,10 @@ > */ > #define DPCPU_SUM(n, var, sum) \ > do { \ > + u_int _i; \ > (sum) =3D 0; \ > - u_int i; \ > - CPU_FOREACH(i) \ > - (sum) +=3D (DPCPU_ID_PTR(i, n))->var; \ > + CPU_FOREACH(_i) \ > + (sum) +=3D (DPCPU_ID_PTR(_i, n))->var; \ > } while (0) You might want to introduce local accumulator to prevent several evaluations of sum, to avoid possible side-effects. Then, after, the loop, do single asignment to the the sum. Or, you could ditch the sum at all, indeed using ({}) and returning the result. __typeof is your friend to select proper type of accumulator. --VuBTcNUPe5zwk2q6 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iEYEARECAAYFAkwWB+UACgkQC3+MBN1Mb4hroQCaAuxJCEfQ6P7UVv66i7jq3oiN YAgAn2ob8eHcCdmY6ed8XDf1j9hKHn15 =nJ7A -----END PGP SIGNATURE----- --VuBTcNUPe5zwk2q6--