From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754044AbcAHEz2 (ORCPT ); Thu, 7 Jan 2016 23:55:28 -0500 Received: from mail-ig0-f172.google.com ([209.85.213.172]:36826 "EHLO mail-ig0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753612AbcAHEz1 (ORCPT ); Thu, 7 Jan 2016 23:55:27 -0500 Date: Fri, 8 Jan 2016 12:54:53 +0800 From: Boqun Feng To: "Paul E. McKenney" Cc: Stephen Rothwell , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo , Christoph Lameter Subject: Re: linux-next: build failure after merge of the rcu tree Message-ID: <20160108045453.GB4300@fixme-laptop.cn.ibm.com> References: <20160107195725.3a130b4d@canb.auug.org.au> <20160107180244.GR3818@linux.vnet.ibm.com> <20160108071932.060a9bcc@canb.auug.org.au> <20160107205220.GU3818@linux.vnet.ibm.com> <20160108013631.GA11410@fixme-laptop.cn.ibm.com> <20160108034157.GZ3818@linux.vnet.ibm.com> <20160108150850.1ec97e78@canb.auug.org.au> <20160108044835.GB3818@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="UHN/qo2QbUvPLonB" Content-Disposition: inline In-Reply-To: <20160108044835.GB3818@linux.vnet.ibm.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --UHN/qo2QbUvPLonB Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jan 07, 2016 at 08:48:35PM -0800, Paul E. McKenney wrote: > On Fri, Jan 08, 2016 at 03:08:50PM +1100, Stephen Rothwell wrote: > > Hi Paul, > >=20 > > On Thu, 7 Jan 2016 19:41:57 -0800 "Paul E. McKenney" wrote: > > > > > > Indeed, I suspect that SRCU might not be the only thing that would li= ke > > > static per-CPU variables. ;-) > >=20 > > from include/linux/percpu-defs.h: > >=20 > > * s390 and alpha modules require percpu variables to be defined as > > * weak to force the compiler to generate GOT based external > > * references for them. This is necessary because percpu sections > > * will be located outside of the usually addressable area. > > * > > * This definition puts the following two extra restrictions when > > * defining percpu variables. > > * > > * 1. The symbol must be globally unique, even the static ones. > > * 2. Static percpu variables cannot be defined inside a function. > > * > > * Archs which need weak percpu definitions should define > > * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary. > > * > > * To ensure that the generic code observes the above two > > * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak > > * definition is used for all cases. > >=20 > > so they can be static, but must be globally unique. Interesting ;-) Thank you. >=20 > Thank you for the tutorial! I have updated the patch to use a unique > name for the srcu_struct added by rcuperf.c. >=20 Plus a comment for DEFINE_STATIC_SRCU saying srcu can be defined as static but must have a unique name for this reason? Regards, Boqun > Thanx, Paul >=20 --UHN/qo2QbUvPLonB Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAABCAAGBQJWj0EUAAoJEEl56MO1B/q4Rq0IAKFHlCsK41xTpXIbtd50B//u YniiX/Wd/5bNeD5oJYgrUbBg6eIpw56qGh7IObLQ1Hd6SDFKq2R7XN3/CQgxTTji wki9CLSgpqj2CZM4Wl6eyk6xpxj9WC0XetkmdBm3ZIQh7ZGz9VpbQnYIePa60Ut3 00tlKlBNzLeB5VULvFWneUSfT7PPwaFXxIKzPbegW7n4max7LCysgirWeygXJVZo gQqJLq7MSfiEUf0AZYSCjCzDgPSnrKF1ZgYoqe9Dlu/cy04BhYCaY2Sbg5snw6Hc ye2yqTZZ5BMmIblyU8iCsMzEVj3SxZb1dtA/h90kLsnhxclvt3tF1oco47NCR6E= =Id3q -----END PGP SIGNATURE----- --UHN/qo2QbUvPLonB--