From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751443AbbI0ETg (ORCPT ); Sun, 27 Sep 2015 00:19:36 -0400 Received: from e34.co.us.ibm.com ([32.97.110.152]:41564 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750788AbbI0ETf (ORCPT ); Sun, 27 Sep 2015 00:19:35 -0400 X-IBM-Helo: d03dlp03.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org Date: Sat, 26 Sep 2015 21:19:30 -0700 From: "Paul E. McKenney" To: mingo@kernel.org Cc: linux-kernel@vger.kernel.org, msalter@redhat.com, linux@roeck-us.net, oleg@redhat.com, sasha.levin@oracle.com Subject: [GIT PULL rcu/urgent] Fix two more 4.3 regressions Message-ID: <20150927041930.GA32426@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15092704-0017-0000-0000-00000E2E2B43 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Ingo, This series contains two small fixes for regressions introduced during the past merge window: 1. Recent versions of gcc are fatally confused by use of a const int variable for array bounds in inline functions, one of which was introduced by 114b7fd4b (rcu: Create rcu_sync infrastructure). For more information on the gcc bug, see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67055#c13 This workaround for that gcc bug, courtesy of Oleg Nesterov, simply substitutes the constant expression for the two uses of the const int variable. 2. Commit 2cd6ffafec06 (rcu: Extend expedited funnel locking to rcu_data structure) extended contention-reducing funnel locking from the rcu_node structures to the rcu_data structures, but failed to create a separate lock class for the rcu_sched_data structures, which is needed due to the fact that synchronize_rcu_expedited() invokes synchronize_sched_expedited(). In the absence of this separate lock class, lockdep can give false-positive splats. This commit therefore creates the required lock class so that lockdep can see that there is in fact no deadlock. Both fixes have been exposed to -next and 0day Test Robot testing. These changes are available in the git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git for-mingo for you to fetch changes up to 19a5ecde086a6a5287978b12ae948fa691b197b7: rcu: Suppress lockdep false positive for rcp->exp_funnel_mutex (2015-09-20 21:01:22 -0700) ---------------------------------------------------------------- Oleg Nesterov (1): rcu: Change _wait_rcu_gp() to work around GCC bug 67055 Paul E. McKenney (1): rcu: Suppress lockdep false positive for rcp->exp_funnel_mutex include/linux/rcupdate.h | 11 +++++------ kernel/rcu/tree.c | 5 +++++ 2 files changed, 10 insertions(+), 6 deletions(-)