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=-11.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 7792BC55ABD for ; Thu, 12 Nov 2020 09:29:16 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id ED582221FE for ; Thu, 12 Nov 2020 09:29:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="EL4X5TnQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ED582221FE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=AygxyHwtN1cNKHoTUAO1pbww3MSJdiBBd4fsT02MV+E=; b=EL4X5TnQN6KHVysPwU5YkN6/U 4Cm6EswjPMZzsaVV9VgD4K043t9APmmzoSxbHml32/O4WLlLHZboxKBOekwqts1GU86Tv4+ICT0Hj qIZGPK/14dpVPHK9jAKGDVxe3EHRyjDSvoE9j5dSq2v02RrZeAmMPHJPqyBOb7KG1Zn/Lk8qOl54o e/tMKIyP7rbcxpeExQ8lutReuuCS9L0f6tf+KTZdRXWBVexXG1mSJvElY0mzYMYL/P1UgEkzGzSo1 Mp7ZKI7LUed8wQGL2Kk+0/km6JiBWSfPQKY8tZrGzavP5OzhB5z3s77++PvW7mhubAVH0zMJFXFE1 688WrbHUA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kd8tl-0003Tz-6R; Thu, 12 Nov 2020 09:28:09 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kd8ti-0003TB-AT for linux-arm-kernel@lists.infradead.org; Thu, 12 Nov 2020 09:28:07 +0000 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 7BB8C1FB; Thu, 12 Nov 2020 01:28:04 -0800 (PST) Received: from [10.57.23.123] (unknown [10.57.23.123]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 38CD03F73C; Thu, 12 Nov 2020 01:28:03 -0800 (PST) Subject: Re: [RFC 09/11] coresight: etm-perf: Disable the path before capturing the trace data To: Anshuman Khandual , linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org References: <1605012309-24812-1-git-send-email-anshuman.khandual@arm.com> <1605012309-24812-10-git-send-email-anshuman.khandual@arm.com> From: Suzuki K Poulose Message-ID: <1ad992f4-5981-6ff1-470b-875e30d3c229@arm.com> Date: Thu, 12 Nov 2020 09:27:56 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.1 MIME-Version: 1.0 In-Reply-To: <1605012309-24812-10-git-send-email-anshuman.khandual@arm.com> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201112_042806_483826_7358032A X-CRM114-Status: GOOD ( 21.64 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, mathieu.poirier@linaro.org, mike.leach@linaro.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 11/10/20 12:45 PM, Anshuman Khandual wrote: > perf handle structure needs to be shared with the TRBE IRQ handler for > capturing trace data and restarting the handle. There is a probability > of an undefined reference based crash when etm event is being stopped > while a TRBE IRQ also getting processed. This happens due the release > of perf handle via perf_aux_output_end(). This stops the sinks via the > link before releasing the handle, which will ensure that a simultaneous > TRBE IRQ could not happen. > > Signed-off-by: Anshuman Khandual > --- > This might cause problem with traditional sink devices which can be > operated in both sysfs and perf mode. This needs to be addressed > correctly. One option would be to move the update_buffer callback > into the respective sink devices. e.g, disable(). > > drivers/hwtracing/coresight/coresight-etm-perf.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c > index 534e205..1a37991 100644 > --- a/drivers/hwtracing/coresight/coresight-etm-perf.c > +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c > @@ -429,7 +429,9 @@ static void etm_event_stop(struct perf_event *event, int mode) > > size = sink_ops(sink)->update_buffer(sink, handle, > event_data->snk_config); > + coresight_disable_path(path); > perf_aux_output_end(handle, size); > + return; > } As you mentioned, this is not ideal where another session could be triggered on the sink from a different ETM (not for per-CPU sink) in a different mode before you collect the buffer. I believe the best option is to leave the update_buffer() to disable_hw. This would need to pass on the "handle" to the disable_path. That way the races can be handled inside the sinks. Also, this aligns the perf mode of the sinks with that of the sysfs mode. Suzuki _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel