Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753476Ab2H3VRz (ORCPT ); Thu, 30 Aug 2012 17:17:55 -0400 Received: from e1.ny.us.ibm.com ([32.97.182.141]:48618 "EHLO e1.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753011Ab2H3VOW (ORCPT ); Thu, 30 Aug 2012 17:14:22 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, patches@linaro.org, Alessio Igor Bogani , Avi Kivity , Chris Metcalf , Christoph Lameter , Geoff Levand , Gilad Ben Yossef , Hakan Akkan , "H. Peter Anvin" , Ingo Molnar , Kevin Hilman , Max Krasnyansky , Stephen Hemminger , Sven-Thorsten Dietrich , "Paul E. McKenney" Subject: [PATCH tip/core/rcu 11/26] rcu: Exit RCU extended QS on user preemption Date: Thu, 30 Aug 2012 14:05:28 -0700 Message-Id: <1346360743-3628-11-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.8 In-Reply-To: <1346360743-3628-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20120830210520.GA2824@linux.vnet.ibm.com> <1346360743-3628-1-git-send-email-paulmck@linux.vnet.ibm.com> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12083021-6078-0000-0000-00000ED8C60C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2183 Lines: 65 From: Frederic Weisbecker When exceptions or irq are about to resume userspace, if the task needs to be rescheduled, the arch low level code calls schedule() directly. At that time we may be in extended quiescent state from RCU POV: the exception is not anymore protected inside rcu_user_exit() - rcu_user_enter() and the irq has called rcu_irq_exit() already. Create a new API schedule_user() that calls schedule() inside rcu_user_exit()-rcu_user_enter() in order to protect it. Archs will need to rely on it now to implement user preemption safely. Signed-off-by: Frederic Weisbecker Cc: Alessio Igor Bogani Cc: Andrew Morton Cc: Avi Kivity Cc: Chris Metcalf Cc: Christoph Lameter Cc: Geoff Levand Cc: Gilad Ben Yossef Cc: Hakan Akkan Cc: H. Peter Anvin Cc: Ingo Molnar Cc: Josh Triplett Cc: Kevin Hilman Cc: Max Krasnyansky Cc: Peter Zijlstra Cc: Stephen Hemminger Cc: Steven Rostedt Cc: Sven-Thorsten Dietrich Cc: Thomas Gleixner Signed-off-by: Paul E. McKenney --- kernel/sched/core.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0bd599b..e841dfc 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3463,6 +3463,13 @@ asmlinkage void __sched schedule(void) } EXPORT_SYMBOL(schedule); +asmlinkage void __sched schedule_user(void) +{ + rcu_user_exit(); + schedule(); + rcu_user_enter(); +} + /** * schedule_preempt_disabled - called with preemption disabled * -- 1.7.8 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/