From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754685Ab3ILQvS (ORCPT ); Thu, 12 Sep 2013 12:51:18 -0400 Received: from mail-pb0-f44.google.com ([209.85.160.44]:43664 "EHLO mail-pb0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754603Ab3ILQvL (ORCPT ); Thu, 12 Sep 2013 12:51:11 -0400 From: Soren Brinkmann To: Rob Herring , Pawel Moll , Mark Rutland , Stephen Warren , Ian Campbell , Russell King , Michal Simek , Thomas Gleixner , Daniel Lezcano , Stephen Boyd Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 1/2] tick: broadcast: Deny per-cpu clockevents from being broadcast sources Date: Thu, 12 Sep 2013 09:50:39 -0700 Message-Id: <1379004640-15117-2-git-send-email-soren.brinkmann@xilinx.com> X-Mailer: git-send-email 1.8.4 In-Reply-To: <1379004640-15117-1-git-send-email-soren.brinkmann@xilinx.com> References: <1379004640-15117-1-git-send-email-soren.brinkmann@xilinx.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Stephen Boyd On most ARM systems the per-cpu clockevents are truly per-cpu in the sense that they can't be controlled on any other CPU besides the CPU that they interrupt. If one of these clockevents were to become a broadcast source we will run into a lot of trouble because the broadcast source is enabled on the first CPU to go into deep idle (if that CPU suffers from FEAT_C3_STOP) and that could be a different CPU than what the clockevent is interrupting (or even worse the CPU that the clockevent interrupts could be offline). Theoretically it's possible to support per-cpu clockevents as the broadcast source but so far we haven't needed this and supporting it is rather complicated. Let's just deny the possibility for now until this becomes a reality (let's hope it never does!). Reported-by: Sören Brinkmann Signed-off-by: Stephen Boyd --- kernel/time/tick-broadcast.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 218bcb5..d3539e5 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -77,6 +77,9 @@ static bool tick_check_broadcast_device(struct clock_event_device *curdev, !(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) return false; + if (cpumask_equal(newdev->cpumask, cpumask_of(smp_processor_id()))) + return false; + return !curdev || newdev->rating > curdev->rating; } -- 1.8.4