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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 CC973C432BE for ; Fri, 23 Jul 2021 12:46:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD43960E8C for ; Fri, 23 Jul 2021 12:46:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234977AbhGWMFy (ORCPT ); Fri, 23 Jul 2021 08:05:54 -0400 Received: from foss.arm.com ([217.140.110.172]:45458 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234931AbhGWMFv (ORCPT ); Fri, 23 Jul 2021 08:05:51 -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 55D9311D4; Fri, 23 Jul 2021 05:46:25 -0700 (PDT) Received: from ewhatever.cambridge.arm.com (ewhatever.cambridge.arm.com [10.1.197.1]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id DE8C33F694; Fri, 23 Jul 2021 05:46:23 -0700 (PDT) From: Suzuki K Poulose To: coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, tamas.zsoldos@arm.com, al.grant@arm.com, leo.yan@linaro.org, mike.leach@linaro.org, mathieu.poirier@linaro.org, suzuki.poulose@arm.com, anshuman.khandual@arm.com, jinlmao@qti.qualcomm.com Subject: [PATCH v2 03/10] coresight: etm-pmu: Ensure the AUX handle is valid Date: Fri, 23 Jul 2021 13:46:04 +0100 Message-Id: <20210723124611.3828908-4-suzuki.poulose@arm.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20210723124611.3828908-1-suzuki.poulose@arm.com> References: <20210723124611.3828908-1-suzuki.poulose@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The ETM perf infrastructure closes out a handle during event_stop or on an error in starting the event. In either case, it is possible for a "sink" to update/close the handle, under certain circumstances. (e.g no space in ring buffer.). So, ensure that we handle this gracefully in the PMU driver by verifying the handle is still valid. Cc: Mathieu Poirier Cc: Mike Leach Cc: Anshuman Khandual Cc: Leo Yan Signed-off-by: Suzuki K Poulose --- .../hwtracing/coresight/coresight-etm-perf.c | 27 ++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c index 6f398377fec9..a6ab603afee4 100644 --- a/drivers/hwtracing/coresight/coresight-etm-perf.c +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c @@ -450,8 +450,15 @@ static void etm_event_start(struct perf_event *event, int flags) fail_disable_path: coresight_disable_path(path); fail_end_stop: - perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); - perf_aux_output_end(handle, 0); + /* + * Check if the handle is still associated with the event, + * to handle cases where if the sink failed to start the + * trace and TRUNCATED the handle already. + */ + if (READ_ONCE(handle->event)) { + perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); + perf_aux_output_end(handle, 0); + } fail: event->hw.state = PERF_HES_STOPPED; goto out; @@ -519,7 +526,21 @@ static void etm_event_stop(struct perf_event *event, int mode) size = sink_ops(sink)->update_buffer(sink, handle, event_data->snk_config); - perf_aux_output_end(handle, size); + /* + * Make sure the handle is still valid as the + * sink could have closed it from an IRQ. + * The sink driver must handle the race with + * update_buffer() and IRQ. Thus either we + * should get a valid handle and valid size + * (which may be 0). + * + * But we should never get a non-zero size with + * an invalid handle. + */ + if (READ_ONCE(handle->event)) + perf_aux_output_end(handle, size); + else + WARN_ON(size); } /* Disabling the path make its elements available to other sessions */ -- 2.24.1