From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759344Ab3DYSba (ORCPT ); Thu, 25 Apr 2013 14:31:30 -0400 Received: from wolverine01.qualcomm.com ([199.106.114.254]:23302 "EHLO wolverine01.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759333Ab3DYSb2 (ORCPT ); Thu, 25 Apr 2013 14:31:28 -0400 X-IronPort-AV: E=Sophos;i="4.87,552,1363158000"; d="scan'208";a="41426320" Message-ID: <5179767F.5030405@codeaurora.org> Date: Thu, 25 Apr 2013 11:31:27 -0700 From: Stephen Boyd User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:17.0) Gecko/20130328 Thunderbird/17.0.5 MIME-Version: 1.0 To: arm@kernel.org CC: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, John Stultz , Thomas Gleixner , Mark Rutland Subject: Re: [PATCH/RESEND] ARM: arch_timer: Silence debug preempt warnings References: <1366241178-16626-1-git-send-email-sboyd@codeaurora.org> In-Reply-To: <1366241178-16626-1-git-send-email-sboyd@codeaurora.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/17/13 16:26, Stephen Boyd wrote: > Hot-plugging with CONFIG_DEBUG_PREEMPT=y on a device with arm > architected timers causes a slew of "using smp_processor_id() in > preemptible" warnings: > > BUG: using smp_processor_id() in preemptible [00000000] code: sh/111 > caller is arch_timer_cpu_notify+0x14/0xc8 > > This happens because sometimes the cpu notifier, > arch_timer_cpu_notify(), is called in preemptible context and > other times in non-preemptible context but we use this_cpu_ptr() > to retrieve the clockevent in all cases. We're only going to > actually use the pointer in non-preemptible context though, so > push the this_cpu_ptr() access down into the cases to force the > checks to occur only in non-preemptible contexts. > > Cc: John Stultz > Cc: Thomas Gleixner > Cc: Mark Rutland > Acked-by: Marc Zyngier > Signed-off-by: Stephen Boyd > --- > > Resending to arm-soc maintainers instead of timekeeping maintainers. Who > maintains this driver? Ping. > > drivers/clocksource/arm_arch_timer.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c > index d7ad425..a65a710 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -248,14 +248,16 @@ static void __cpuinit arch_timer_stop(struct clock_event_device *clk) > static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self, > unsigned long action, void *hcpu) > { > - struct clock_event_device *evt = this_cpu_ptr(arch_timer_evt); > - > + /* > + * Grab cpu pointer in each case to avoid spurious > + * preemptible warnings > + */ > switch (action & ~CPU_TASKS_FROZEN) { > case CPU_STARTING: > - arch_timer_setup(evt); > + arch_timer_setup(this_cpu_ptr(arch_timer_evt)); > break; > case CPU_DYING: > - arch_timer_stop(evt); > + arch_timer_stop(this_cpu_ptr(arch_timer_evt)); > break; > } > -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation