From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 71E26C12002 for ; Thu, 15 Jul 2021 03:23:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 598F161377 for ; Thu, 15 Jul 2021 03:23:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231682AbhGODZy (ORCPT ); Wed, 14 Jul 2021 23:25:54 -0400 Received: from foss.arm.com ([217.140.110.172]:46162 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230495AbhGODZx (ORCPT ); Wed, 14 Jul 2021 23:25:53 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 494BF1042; Wed, 14 Jul 2021 20:23:01 -0700 (PDT) Received: from [10.163.66.71] (unknown [10.163.66.71]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C4C5E3F7D8; Wed, 14 Jul 2021 20:22:57 -0700 (PDT) Subject: Re: [PATCH 4/5] coresight: trbe: Move irq_work queue processing To: Suzuki K Poulose , linux-arm-kernel@lists.infradead.org Cc: coresight@lists.linaro.org, linux-kernel@vger.kernel.org, al.grant@arm.com, leo.yan@linaro.org, mathieu.poirier@linaro.org, mike.leach@linaro.org, peterz@infradead.org, Tamas.Zsoldos@arm.com, will@kernel.org References: <20210712113830.2803257-1-suzuki.poulose@arm.com> <20210712113830.2803257-5-suzuki.poulose@arm.com> From: Anshuman Khandual Message-ID: <390617ae-c5bd-b73a-c48c-e62b7f5330ca@arm.com> Date: Thu, 15 Jul 2021 08:53:46 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210712113830.2803257-5-suzuki.poulose@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/12/21 5:08 PM, Suzuki K Poulose wrote: > The TRBE driver issues the irq_work_run() to ensure that > any pending disable event callback has been processed. But this > is done before we mark the AUX buffer as TRUNCATED, making > the call pointless. Move the call after the current handle > has been closed. So there is a possibility that a disable event gets missed before the buffer is marked TRUNCATED ? But even then would not another disable event be triggered again subsequently ? Just trying to understand what is the actual problem because of the current placement of irq_work_run() ? > > Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver") > Reported-by: Tamas Zsoldos > Cc: Anshuman Khandual > Cc: Mathieu Poirier > Cc: Mike Leach > Cc: Peter Zijlstra (Intel) > Cc: Leo Yan > Cc: Will Deacon > Signed-off-by: Suzuki K Poulose > --- > drivers/hwtracing/coresight/coresight-trbe.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c > index ec38cf17b693..c0c264264427 100644 > --- a/drivers/hwtracing/coresight/coresight-trbe.c > +++ b/drivers/hwtracing/coresight/coresight-trbe.c > @@ -723,6 +723,14 @@ static void trbe_handle_overflow(struct perf_output_handle *handle) > perf_aux_output_flag(handle, PERF_AUX_FLAG_CORESIGHT_FORMAT_RAW | > PERF_AUX_FLAG_TRUNCATED); > perf_aux_output_end(handle, size); > + > + /* > + * Ensure perf callbacks have completed. Since we > + * always TRUNCATE the buffer on IRQ, the event > + * is scheduled to be disabled. Make sure that happens > + * as soon as possible. > + */ > + irq_work_run(); > } > > static bool is_perf_trbe(struct perf_output_handle *handle) > @@ -777,12 +785,6 @@ static irqreturn_t arm_trbe_irq_handler(int irq, void *dev) > if (!is_perf_trbe(handle)) > return IRQ_NONE; > > - /* > - * Ensure perf callbacks have completed, which may disable > - * the trace buffer in response to a TRUNCATION flag. > - */ > - irq_work_run(); > - > act = trbe_get_fault_act(status); > switch (act) { > case TRBE_FAULT_ACT_WRAP: >