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[147.75.48.161]) by mx.google.com with ESMTPS id h10-20020a63c00a000000b005dc957fe10bsi12692840pgg.701.2024.03.06.10.53.27 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Mar 2024 10:53:28 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-94450-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161; Authentication-Results: mx.google.com; arc=pass (i=1); spf=pass (google.com: domain of linux-kernel+bounces-94450-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) smtp.mailfrom="linux-kernel+bounces-94450-linux.lists.archive=gmail.com@vger.kernel.org" Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sy.mirrors.kernel.org (Postfix) with ESMTPS id 76F30B22AD8 for ; Wed, 6 Mar 2024 18:53:22 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 78D728060D; Wed, 6 Mar 2024 18:53:14 +0000 (UTC) Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E5B8713DBB7; Wed, 6 Mar 2024 18:53:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709751194; cv=none; b=WiBbbdmxY5z5Jfrk2A1Pz9jyDS3oCh37GlxJk2StQ8y1Rtvmf74dsNEWqAEX5CBI20S8wBbNIX6q1uzDysKBOw7MvlaalSw5TGDb5YGzjOldXMqsCEugvg2NNUIvpkh8VENmI6lleyMDx0WikpvApgczMxcXONL71rhStZn1OCY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709751194; c=relaxed/simple; bh=pTxcLZycLySNRRWtPcoZMpgtrgApnpFDXfUYU2x8wHc=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=WG0HxpT4cjIHtPtli5s2g7DoP8G5fuRToJgrlPfWASwKkyif5pFb0dVAtErZ9qN5fM3IxQxXthtK5N5ePwfxwsTC1XoqloCUd6VFUudAYU0utCdnK+kgrGFql8Bt+xjsONw9A39+mKTj+sWXS71LaFrd7qwaS/RdicByrjGQjM0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id ECD8AC433F1; Wed, 6 Mar 2024 18:53:11 +0000 (UTC) Date: Wed, 6 Mar 2024 13:55:04 -0500 From: Steven Rostedt To: Linus Torvalds Cc: "Paul E. McKenney" , linke li , joel@joelfernandes.org, boqun.feng@gmail.com, dave@stgolabs.net, frederic@kernel.org, jiangshanlai@gmail.com, josh@joshtriplett.org, linux-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, qiang.zhang1211@gmail.com, quic_neeraju@quicinc.com, rcu@vger.kernel.org Subject: Re: [PATCH] rcutorture: Fix rcu_torture_pipe_update_one()/rcu_torture_writer() data race and concurrency bug Message-ID: <20240306135504.2b3872ef@gandalf.local.home> In-Reply-To: References: <20240306103719.1d241b93@gandalf.local.home> <27665890-8314-4252-8622-1e019fee27e4@paulmck-laptop> <20240306130103.6da71ddf@gandalf.local.home> X-Mailer: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 6 Mar 2024 10:43:25 -0800 Linus Torvalds wrote: Thanks for the history lesson ;-) > So yes, READ_ONCE/WRITE_ONCE do control "tearing", but realistically, > it was always only about the "complex values" kind of tearing that the > old ACCESS_ONCE() model silently and incorrectly allowed. Now, are you OK with an addition of ADD_ONCE() and/or INC_ONCE()? So that we don't have to look at: WRITE_ONCE(a, READ_ONCE(a) + 1); ? -- Steve