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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E21BBC48297 for ; Fri, 9 Feb 2024 09:49:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=CH4eQyWpZYz/BeQgl+S+WRFkCDjPlFJFQ2W0jC6VwoA=; b=GoKGBKxqiR33CZ c+w4jiLvqkvhlkWi0X8jSXRiXAGn3lkkk95nMVU3LKO6RzWwzPpYa0pzvkid9qVSbDhUiDNUZzj8T 5O8599bsxa9+dN0x3UixQxfUpfs6ijkP0uKjRfSRNx5v/NVk9TucZGAY4QJnQma0RDFczZKobcmEw nm5XpQZc1q1o/ODN0izS3prwkO7ipZ23Bxm2Zrvki0XSiTll/Nz3fEmvqpFCH8sRxjehsFz8H8Ees bjmehpjXjJ0DaDBciGF+HySoDoqsIrX7MliQ3EueL0bQwHLeqjR2fggIrTmz9/RuWYFOHU+kjL4bY wnqiLsDLKpMN30qpFuEg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rYNVl-0000000Gd9b-22M4; Fri, 09 Feb 2024 09:49:33 +0000 Received: from mgamail.intel.com ([198.175.65.16]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rYNVi-0000000Gd8o-2kV0 for linux-arm-kernel@lists.infradead.org; Fri, 09 Feb 2024 09:49:31 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1707472170; x=1739008170; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=ReUjtNoKI4AEfvdlJoQ9stY41QHkrHNfAjwN3V3muic=; b=km9lMYLSR1QjgxVYfKoPSa4l7DNJZNboyBB49oK5Uv07uYqYbEBW2v+V 6rhaomc5qcuTZmldJe4QJuGFPqAJ2EZmwhhFZtGCLkTyb8XeeNEdXI1H0 fg7J5dF9cDdlX78B/tHQcNutLlflIzieCe0rDOg8cv0Rzv9/Tir6dF3a/ 9Mwb+qUPG2JJWgrGa3/EFrY7QCxdLSQSq3ItAEMFQV8As4hnZTpdKBnfp i/9l5Xcnsl29vPI9nVWFPYjLfQysDch6E1wvCBQbeOjcTxeMk+k0XO1Fi V6tzmD4BQ2O+RHomhFznkdEFEYB1ga8aU00dZT4oVWN2TZq1wsfEU8Kfl Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10978"; a="1551785" X-IronPort-AV: E=Sophos;i="6.05,256,1701158400"; d="scan'208";a="1551785" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Feb 2024 01:49:27 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.05,256,1701158400"; d="scan'208";a="6515835" Received: from tassilo.jf.intel.com (HELO tassilo) ([10.54.38.190]) by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Feb 2024 01:49:27 -0800 Date: Fri, 9 Feb 2024 01:49:25 -0800 From: Andi Kleen To: Adrian Hunter Cc: Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Heiko Carstens , Thomas Richter , Hendrik Brueckner , Suzuki K Poulose , Mike Leach , James Clark , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, Yicong Yang , Jonathan Cameron , Will Deacon , Arnaldo Carvalho de Melo , Jiri Olsa , Namhyung Kim , Ian Rogers , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: Re: [PATCH V5 01/12] perf/core: Add aux_pause, aux_resume, aux_start_paused Message-ID: References: <20240208113127.22216-1-adrian.hunter@intel.com> <20240208113127.22216-2-adrian.hunter@intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240209_014930_761094_BEEE4D65 X-CRM114-Status: GOOD ( 14.54 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Feb 09, 2024 at 10:14:44AM +0200, Adrian Hunter wrote: > On 9/02/24 02:13, Andi Kleen wrote: > >> +static void __perf_event_aux_pause(struct perf_event *event, bool pause) > >> +{ > >> + if (pause) { > >> + if (!READ_ONCE(event->aux_paused)) { > >> + WRITE_ONCE(event->aux_paused, 1); > >> + event->pmu->stop(event, PERF_EF_PAUSE); > >> + } > >> + } else { > >> + if (READ_ONCE(event->aux_paused)) { > >> + WRITE_ONCE(event->aux_paused, 0); > >> + event->pmu->start(event, PERF_EF_RESUME); > >> + } > > > > This doesn't look atomic. Either the READ/WRITE once are not needed, > > or you need an actually atomic construct. > > Yes READ_ONCE / WRITE_ONCE is not really needed here. Normally you are supposed to add a comment on what the interaction is (similar to what is done for spinlock declarations) -Andi _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel