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,USER_AGENT_GIT 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 C1694C07E96 for ; Sun, 11 Jul 2021 10:41:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AC1E3611ED for ; Sun, 11 Jul 2021 10:41:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232371AbhGKKoN (ORCPT ); Sun, 11 Jul 2021 06:44:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48472 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232085AbhGKKoJ (ORCPT ); Sun, 11 Jul 2021 06:44:09 -0400 Received: from mail-pj1-x1034.google.com (mail-pj1-x1034.google.com [IPv6:2607:f8b0:4864:20::1034]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 77542C0613DD for ; Sun, 11 Jul 2021 03:41:22 -0700 (PDT) Received: by mail-pj1-x1034.google.com with SMTP id i16-20020a17090acf90b02901736d9d2218so3737273pju.1 for ; Sun, 11 Jul 2021 03:41:22 -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=tvAJvuDnRJDe9YMY5R2L+q2C0nSKQeIr4jFz4M7hp0E=; b=er914k1odHGQXFxKzwCAlSjDGT1lEhzg/54+63PQydsGFVX2c9kqX4DPnaoiLiqnTP Sw261DSe/328/xnD6Q0ZHboHc2K56SXChdQ8gad+HDOsfl/dCd/Zkfda9mRDkkuz4V/F PxnXcnEgmWJSCgPt0zXCAszYveUShnZMGHu5vn5yxmAVcIC0pjjHzjY1X6lRErUI/oa6 PbqT1IFNUz5O3YrANKzyUQ/XhuAG3SdAY3lRCQzDVoUvMMdrEFpLSQw1ENZ9znLkXwvM wM6qimqRDCqFO3Wq2+eZ1BIfH/Im3aalssq5IIu+S5UCtJLL58kuPYMZwjGiJfUrW15c 73jA== 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=tvAJvuDnRJDe9YMY5R2L+q2C0nSKQeIr4jFz4M7hp0E=; b=GFEO0ZNpUX6aedLNYMeBZ8eZ7KX+u/56KH7dsJxjrqyjRa3UqlGcnbcKyikig6gnci BNK5jvxMhDUbOfCo2Pcc98YMJIFUnWgm5/IeTYxu+KpxkioHLsFe2pFlNDak6Dn2fvAM SOW6kJwE+RF4+hbkjPQK/PS6T6m3UQt7AFryUjeFN7Z2dfJREv8lNhtPDWFVfw/Xw4gm 19EDEDWd7Jy+iXyJjJcT9gEs1mQsJEBbaOWVXm9W8DNV/AKwapm5bSpqrH3BW+YH0Awh OEzJBjFxzdsIfN3h1JeHEdcuhJn/ar7NUMZjespFR4IeIoMdphK3mr3vSR71yLQUTgSQ 8Feg== X-Gm-Message-State: AOAM5314NI1KYglXDxEYaSKJ6JL2ZI5Avo3viKeDV9YfCNWANvNeVAML PG6r2gFnfYgTgl8qSVs+JSP04w== X-Google-Smtp-Source: ABdhPJx3EsK700CJoPDmV2uQscNMM5W/vzqGJIPYWH/E+Oq8jMLYvmO+fUcusoi8LDNTAkzV9oH4bg== X-Received: by 2002:a17:90a:4681:: with SMTP id z1mr7368243pjf.156.1626000082010; Sun, 11 Jul 2021 03:41:22 -0700 (PDT) Received: from localhost ([103.127.241.250]) by smtp.gmail.com with ESMTPSA id d191sm13945165pga.27.2021.07.11.03.41.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 11 Jul 2021 03:41:21 -0700 (PDT) From: Leo Yan To: Arnaldo Carvalho de Melo , Adrian Hunter , Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Thomas Gleixner , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Mathieu Poirier , Suzuki K Poulose , Mike Leach , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org Cc: Leo Yan Subject: [PATCH v4 02/11] coresight: tmc-etr: Add barrier after updating AUX ring buffer Date: Sun, 11 Jul 2021 18:40:56 +0800 Message-Id: <20210711104105.505728-3-leo.yan@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210711104105.505728-1-leo.yan@linaro.org> References: <20210711104105.505728-1-leo.yan@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since a memory barrier is required between AUX trace data store and aux_head store, and the AUX trace data is filled with memcpy(), it's sufficient to use smp_wmb() so can ensure the trace data is visible prior to updating aux_head. Signed-off-by: Leo Yan --- drivers/hwtracing/coresight/coresight-tmc-etr.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c index acdb59e0e661..713205db15a1 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -1563,6 +1563,14 @@ tmc_update_etr_buffer(struct coresight_device *csdev, */ if (etr_perf->snapshot) handle->head += size; + + /* + * It requires the ordering between the AUX trace data and aux_head + * store, below smp_wmb() ensures the AUX trace data is visible prior + * to updating aux_head. + */ + smp_wmb(); + out: /* * Don't set the TRUNCATED flag in snapshot mode because 1) the -- 2.25.1