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[78.210.255.2]) by smtp.googlemail.com with ESMTPSA id 88sm5731506wrc.33.2019.05.24.03.42.39 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 24 May 2019 03:42:40 -0700 (PDT) Subject: Re: [PATCH] clocksource/arm_arch_timer: Don't trace count reader functions To: Marc Zyngier , Julien Thierry , linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Mark Rutland , Thomas Gleixner , Steven Rostedt References: <1558689025-50679-1-git-send-email-julien.thierry@arm.com> <9adf92c2-b7a5-00a3-ff09-58484d9bb9db@arm.com> From: Daniel Lezcano Message-ID: Date: Fri, 24 May 2019 12:42:39 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <9adf92c2-b7a5-00a3-ff09-58484d9bb9db@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/05/2019 11:53, Marc Zyngier wrote: > On 24/05/2019 10:10, Julien Thierry wrote: >> With v5.2-rc1, The ftrace functions_graph tracer locks up whenever it is >> enabled on arm64. >> >> Since commit 0ea415390cd3 ("clocksource/arm_arch_timer: Use >> arch_timer_read_counter to access stable counters") a function pointer >> is consistently used to read the counter instead of potentially >> referencing an inlinable function. >> >> The graph tacers relies on accessing the timer counters to compute the > > nit: tracers > >> time spent in functions which causes the lockup when attempting to trace >> these code paths. >> >> Annontate the arm arch timer counter accessors as notrace. > > nit: Annotate > >> >> Fixes: 0ea415390cd3 ("clocksource/arm_arch_timer: Use >> arch_timer_read_counter to access stable counters") >> Signed-off-by: Julien Thierry >> Cc: Marc Zyngier >> Cc: Mark Rutland >> Cc: Daniel Lezcano >> Cc: Thomas Gleixner >> Cc: Steven Rostedt >> --- [ ... ] > Well spotted, thanks Julien. > > Acked-by: Marc Zyngier > > Daniel, can you please pick this up for the next batch of clocksource fixes? Sure. I will take care of fixing the comments, no need to resend. Thanks -- Daniel -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog