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=unavailable 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 0DAF6C47082 for ; Mon, 7 Jun 2021 10:03:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E97D860BBB for ; Mon, 7 Jun 2021 10:03:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230289AbhFGKFC (ORCPT ); Mon, 7 Jun 2021 06:05:02 -0400 Received: from mga02.intel.com ([134.134.136.20]:26060 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230193AbhFGKFB (ORCPT ); Mon, 7 Jun 2021 06:05:01 -0400 IronPort-SDR: cm9Wjz515AL50obghruQKJGgVQsmjbo1kvlBgnIJwAQ9SvWU/ARP8BjThQ0tfEsYQFoQrfSWdA K9RYw4GQgbtA== X-IronPort-AV: E=McAfee;i="6200,9189,10007"; a="191702897" X-IronPort-AV: E=Sophos;i="5.83,254,1616482800"; d="scan'208";a="191702897" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jun 2021 03:03:10 -0700 IronPort-SDR: cbVVM/RFVTOe4XSIG7lwLwdbgOmk2k7ZtwC1WPlisFYzxgfhY0yfh0NbxQ3HFRKIJ9ZCrEnjrx gpWRjhYPNSrA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.83,254,1616482800"; d="scan'208";a="484723038" Received: from ahunter-desktop.fi.intel.com (HELO [10.237.72.174]) ([10.237.72.174]) by fmsmga002.fm.intel.com with ESMTP; 07 Jun 2021 03:03:06 -0700 Subject: Re: [PATCH v2 7/8] perf auxtrace: Use WRITE_ONCE() for updating aux_tail To: Leo Yan , Arnaldo Carvalho de Melo , Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Thomas Gleixner , x86@kernel.org, "H. Peter Anvin" , Mathieu Poirier , Suzuki K Poulose , Mike Leach , Andi Kleen , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org References: <20210602103007.184993-1-leo.yan@linaro.org> <20210602103007.184993-8-leo.yan@linaro.org> From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Message-ID: Date: Mon, 7 Jun 2021 13:03:24 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210602103007.184993-8-leo.yan@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On 2/06/21 1:30 pm, Leo Yan wrote: > Use WRITE_ONCE() for updating aux_tail, so can avoid unexpected memory > behaviour. > > Signed-off-by: Leo Yan Acked-by: Adrian Hunter > --- > tools/perf/util/auxtrace.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h > index e625bc76cdde..abc4282f5272 100644 > --- a/tools/perf/util/auxtrace.h > +++ b/tools/perf/util/auxtrace.h > @@ -458,7 +458,7 @@ static inline void auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail) > > /* Ensure all reads are done before we write the tail out */ > smp_mb(); > - pc->aux_tail = tail; > + WRITE_ONCE(pc->aux_tail, tail); > } > > int auxtrace_mmap__mmap(struct auxtrace_mmap *mm, >