Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934119AbaFSRHa (ORCPT ); Thu, 19 Jun 2014 13:07:30 -0400 Received: from mail-vc0-f175.google.com ([209.85.220.175]:48055 "EHLO mail-vc0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932894AbaFSRH1 (ORCPT ); Thu, 19 Jun 2014 13:07:27 -0400 MIME-Version: 1.0 In-Reply-To: <53A030DB.3090009@linaro.org> References: <1401903034-20074-1-git-send-email-dianders@chromium.org> <53A030DB.3090009@linaro.org> Date: Thu, 19 Jun 2014 10:07:26 -0700 X-Google-Sender-Auth: bvNias8uLCHvbbQwUpjYSR6sIrU Message-ID: Subject: Re: [PATCH 1/3] clocksource: exynos_mct: Fix ftrace From: Doug Anderson To: Daniel Lezcano Cc: Kukjin Kim , Tomasz Figa , Vincent Guittot , Chirantan Ekbote , David Riley , Olof Johansson , linux-samsung-soc , Thomas Gleixner , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Daniel, On Tue, Jun 17, 2014 at 5:13 AM, Daniel Lezcano wrote: > On 06/04/2014 07:30 PM, Doug Anderson wrote: >> >> In (93bfb76 clocksource: exynos_mct: register sched_clock callback) we >> supported using the MCT as a scheduler clock. We properly marked >> exynos4_read_sched_clock() as notrace. However, we then went and >> called another function that _wasn't_ notrace. That means if you do: >> >> cd /sys/kernel/debug/tracing/ >> echo function_graph > current_tracer >> >> You'll get a crash. >> >> Fix this (but still let other readers of the MCT be trace-enabled) by >> adding an extra function. It's important to keep other users of MCT >> traceable because the MCT is actually quite slow. > > > Thanks for the explanation in the other email. > > I think the last sentence is a bit confusing because you are implicitly > saying you need these traces to investigate why the timer is slow which is > referring to something not related to this fix. Done >> Signed-off-by: Doug Anderson >> --- >> drivers/clocksource/exynos_mct.c | 9 +++++++-- >> 1 file changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/clocksource/exynos_mct.c >> b/drivers/clocksource/exynos_mct.c >> index 8d64200..ba3a683 100644 >> --- a/drivers/clocksource/exynos_mct.c >> +++ b/drivers/clocksource/exynos_mct.c >> @@ -165,7 +165,7 @@ static void exynos4_mct_frc_start(u32 hi, u32 lo) >> exynos4_mct_write(reg, EXYNOS4_MCT_G_TCON); >> } >> >> -static cycle_t exynos4_frc_read(struct clocksource *cs) >> +static inline cycle_t notrace _exynos4_frc_read(void) > > > Why inline ? Somehow I thought that without the "inline" that somehow exynos4_frc_read() would not be traceable. ...but this makes no sense so I've removed. -- 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/