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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 905D6C4338F for ; Mon, 9 Aug 2021 11:15:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 68FCD61078 for ; Mon, 9 Aug 2021 11:15:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235037AbhHILPx (ORCPT ); Mon, 9 Aug 2021 07:15:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234994AbhHILPq (ORCPT ); Mon, 9 Aug 2021 07:15:46 -0400 Received: from mail-pl1-x629.google.com (mail-pl1-x629.google.com [IPv6:2607:f8b0:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 37F1AC06179C for ; Mon, 9 Aug 2021 04:15:26 -0700 (PDT) Received: by mail-pl1-x629.google.com with SMTP id k2so15919954plk.13 for ; Mon, 09 Aug 2021 04:15:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=FZ/7kJOb7OY5ptxZfvGqxtGsWJ55PVJlZ2QX0AXu9A8=; b=kdAvEdB/yldBJNpXv5zSGItPMdpNTknsNOOyo0nT3IXC0awSQfbwp3stGSyCdLu+Cd 1fd3XlStrOjWcpdWlPsk6NDyWhQIuNZ6FXksrIU6j7OUC6VxgdValWi4EgDf7XADTkGF eSxGJeQSdkb+GRbB2RGvnkreGGGxwEAXzByw4hiR2lfXtK8sWlYyJbODOSQ8/G1Ci5XX OFT+JoHYBZQvVMf9pBCZ7ynIQp/i5HgrpBFSATop8yU3dmejoFw+r4l2T3i5NIJgWrRM zDt+pLk5D/im4eR0A29vyYPoOPmV3nXiFANUjZoQoaqaDyDNortvkJq8pdgFP0DW6HB7 Z3gw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=FZ/7kJOb7OY5ptxZfvGqxtGsWJ55PVJlZ2QX0AXu9A8=; b=s5TaeyZ7uZIGVGS5tjaeN5OGMaqVk+Jv+3NkMKvXHBn0KtMVb+aZzzVUaNO1Oxy5ND sb4XpCuFNQkGLHHKxrHhoFoJZlXyS+8K9DqkDSd/OkHu/pkP2at4bpkHTshJJMt3dAqo 8oIBKLZJZjksDQcD5lql98vwl5w3C6lwtMZkO1OM1O1jkFhUjdJTUDUdiAOcbrX6aEI3 PH+FU1qI6TH80DH73Y+3vodEgqhNSsTqMZ0/gXM12MjYpCMQPgR/GGdrbHyYZ/wr/kOK QM6lk4FsnZsyLO7mn9P9mHavdpBYVDYva1QnNgUe5o45zpf366qLJzFM2rdj4ZG4VTX5 mvzw== X-Gm-Message-State: AOAM530MFvcMqZI1I8aYokRsS67HkfdqKXQADbeoomC6vcS1iV5Jx5HD GxHiT+Ky0Mnhumqx7FPcLgaakQ== X-Google-Smtp-Source: ABdhPJw30uCIZl48Vo0v+CpxJamxTo4LAr6gws5su6sX5H9i6/3icWWjZ6QV5LRtx5/+c2IHKMe9jw== X-Received: by 2002:a17:90b:4a90:: with SMTP id lp16mr24619127pjb.74.1628507725704; Mon, 09 Aug 2021 04:15:25 -0700 (PDT) Received: from localhost ([210.0.159.74]) by smtp.gmail.com with ESMTPSA id a21sm20504697pfi.15.2021.08.09.04.15.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Aug 2021 04:15:25 -0700 (PDT) From: Leo Yan To: Arnaldo Carvalho de Melo , Peter Zijlstra , Adrian Hunter , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Thomas Gleixner , Borislav Petkov , "H. Peter Anvin" , Mathieu Poirier , Suzuki K Poulose , Mike Leach , Michael Petlan , "Frank Ch. Eigler" , Song Liu , x86@kernel.org, =?UTF-8?q?Daniel=20D=C3=ADaz?= , Andrii Nakryiko , Alexei Starovoitov , Sedat Dilek , Andi Kleen , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, coresight@lists.linaro.org Cc: Leo Yan Subject: [PATCH v5 3/9] coresight: tmc-etf: Add comment for store ordering Date: Mon, 9 Aug 2021 19:14:01 +0800 Message-Id: <20210809111407.596077-4-leo.yan@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210809111407.596077-1-leo.yan@linaro.org> References: <20210809111407.596077-1-leo.yan@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org Since the function CS_LOCK() has contained memory barrier mb(), it ensures the visibility of the AUX trace data before updating the aux_head, thus it's needless to add any explicit barrier anymore. Add comment to make clear for the barrier usage for ETF. Signed-off-by: Leo Yan --- drivers/hwtracing/coresight/coresight-tmc-etf.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c index cd0fb7bfba68..8debd4f40f06 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c @@ -553,6 +553,11 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev, if (buf->snapshot) handle->head += to_read; + /* + * CS_LOCK() contains mb() so it can ensure visibility of the AUX trace + * data before the aux_head is updated via perf_aux_output_end(), which + * is expected by the perf ring buffer. + */ CS_LOCK(drvdata->base); out: spin_unlock_irqrestore(&drvdata->spinlock, flags); -- 2.25.1