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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 B8D3FC55ABD for ; Wed, 11 Nov 2020 16:04:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5EBD0206A1 for ; Wed, 11 Nov 2020 16:04:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="0CqMK5PU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726771AbgKKQER (ORCPT ); Wed, 11 Nov 2020 11:04:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49220 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726011AbgKKQER (ORCPT ); Wed, 11 Nov 2020 11:04:17 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DA5D8C0613D1; Wed, 11 Nov 2020 08:04:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=iYncmeZ9hvqZ5/y+et8tVxToCOeVVwCuQgUXF3Dmkj4=; b=0CqMK5PUx1fsDBB/jOcqQIpgNM M+GiTSC5T9DjE7PhhSZm4YjEavlB1/uKv1I7eZszR4YpuY1jw8YBuurUirKwb5syHvGYMxCrJe8cY Q8eEWVLkmNRaX6T7AzYpyowIka4gtGzLam+WF6Gn230uO0fF+FBXrLgji1Z2Qu9EVsmHCu/m6UBbF ag6vTEU787J+pfXBjvCy+/2dz/CRbC/LoGiWwaHtldRe5mUpDNHSMzmCfuoZnHzezuzWWl44nBNsx lKtE2HPyfOw4deNAiHJmyxm86HofJdLI5pZ/WviNNn9MaM4rkm03gF+rwDktJJi6RZqEQuqID+bHY SOEJJG3A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kcsbU-000191-Md; Wed, 11 Nov 2020 16:04:12 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 5B61B301324; Wed, 11 Nov 2020 17:04:11 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 47E98203E65AF; Wed, 11 Nov 2020 17:04:11 +0100 (CET) Date: Wed, 11 Nov 2020 17:04:11 +0100 From: Peter Zijlstra To: Shuah Khan Cc: corbet@lwn.net, keescook@chromium.org, gregkh@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 01/13] seqnum_ops: Introduce Sequence Number Ops Message-ID: <20201111160411.GF2628@hirez.programming.kicks-ass.net> References: <20201111082320.GR2611@hirez.programming.kicks-ass.net> <7207fad6-6ca4-529b-60a8-63db998d10d9@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7207fad6-6ca4-529b-60a8-63db998d10d9@linuxfoundation.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 11, 2020 at 08:56:49AM -0700, Shuah Khan wrote: > Why would you say no to read and inc? Because they don't guarantee uniqueness (bar wrapping), which is the only reason to use an atomic to begin with.