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 16D52C54E94 for ; Thu, 26 Jan 2023 11:16:05 +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=u+ktaW+Io8n/El/NcZwGG4RNCZoi91g5Myzb+DdZOd8=; b=vWZ1++Fxt7vhFc X/q8569dZNFH+sk/zzHsdqqvjXyOOas+AosrLsh6C7QKythQOqa3wOVPdby01qnLeGXQhldkYUsAz 3hBRri/w4MSg9ScgBTPytdcPFA8Vp+yjpcHY84pye/3UfgXlsPd1TJPt6MGKpWuxbIZyLaujroZJc BK0D5/sDUwf43xiRmWBn7OlFKDX7uYqi87bmrv5KfFqsScNoYHHoG6LOO3c+iXaAKPwF42GaQm0Wc 1vuh6gui+bVVcGy5KGY1Vz8v/omUZgct0GstZtxQgwMyjg7frsOoHiCwIgCpZu4rs15eutr10FTZe ERU4xjNp0bW3GociyRTQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pL0EW-00Agl9-4T; Thu, 26 Jan 2023 11:15:56 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pL0ER-00AgiX-QO for linux-riscv@lists.infradead.org; Thu, 26 Jan 2023 11:15:54 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 32F024B3; Thu, 26 Jan 2023 03:16:31 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.10.122]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 402733F71E; Thu, 26 Jan 2023 03:15:40 -0800 (PST) Date: Thu, 26 Jan 2023 11:15:37 +0000 From: Mark Rutland To: Jules Maselbas Cc: Yann Sionneau , Arnd Bergmann , Jonathan Corbet , Thomas Gleixner , Marc Zyngier , Rob Herring , Krzysztof Kozlowski , Will Deacon , Peter Zijlstra , Boqun Feng , Eric Biederman , Kees Cook , Oleg Nesterov , Ingo Molnar , Waiman Long , "Aneesh Kumar K.V" , Andrew Morton , Nick Piggin , Paul Moore , Eric Paris , Christian Brauner , Paul Walmsley , Palmer Dabbelt , Albert Ou , Guillaume Thouvenin , Clement Leger , Vincent Chardon , Marc =?utf-8?B?UG91bGhpw6hz?= , Julian Vetter , Samuel Jones , Ashley Lesdalons , Thomas Costis , Marius Gligor , Jonathan Borne , Julien Villette , Luc Michel , Louis Morhet , Julien Hascoet , Jean-Christophe Pince , Guillaume Missonnier , Alex Michon , Huacai Chen , WANG Xuerui , Shaokun Zhang , John Garry , Guangbin Huang , Bharat Bhushan , Bibo Mao , Atish Patra , "Jason A. Donenfeld" , Qi Liu , Jiaxun Yang , Catalin Marinas , Mark Brown , Janosch Frank , Alexey Dobriyan , Benjamin Mugnier , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-audit@redhat.com, linux-riscv@lists.infradead.org, bpf@vger.kernel.org Subject: Re: [RFC PATCH v2 11/31] kvx: Add atomic/locking headers Message-ID: References: <20230120141002.2442-1-ysionneau@kalray.eu> <20230120141002.2442-12-ysionneau@kalray.eu> <20230126095720.GF5952@tellis.lin.mbt.kalray.eu> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230126095720.GF5952@tellis.lin.mbt.kalray.eu> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230126_031552_006388_DC6B0F52 X-CRM114-Status: GOOD ( 22.66 ) X-BeenThere: linux-riscv@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-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Hi Jules, On Thu, Jan 26, 2023 at 10:57:20AM +0100, Jules Maselbas wrote: > Hi Mark, > > On Fri, Jan 20, 2023 at 03:18:48PM +0000, Mark Rutland wrote: > > On Fri, Jan 20, 2023 at 03:09:42PM +0100, Yann Sionneau wrote: > > > +#define ATOMIC64_RETURN_OP(op, c_op) \ > > > +static inline long arch_atomic64_##op##_return(long i, atomic64_t *v) \ > > > +{ \ > > > + long new, old, ret; \ > > > + \ > > > + do { \ > > > + old = v->counter; \ > > > > This should be arch_atomic64_read(v), in order to avoid the potential for the > > compiler to replay the access and introduce ABA races and other such problems. > Thanks for the suggestion, this will be into v3. > > > For details, see: > > > > https://lore.kernel.org/lkml/Y70SWXHDmOc3RhMd@osiris/ > > https://lore.kernel.org/lkml/Y71LoCIl+IFdy9D8@FVFF77S0Q05N/ > > > > I see that the generic 32-bit atomic code suffers from that issue, and we > > should fix it. > I took a look at the generic 32-bit atomic, but I am unsure if this > needs to be done for both the SMP and non-SMP implementations. But I > can send a first patch and we can discuss from there. Sounds good to me; thanks! [...] > > > +static inline int arch_atomic_add_return(int i, atomic_t *v) > > > +{ > > > + int new, old, ret; > > > + > > > + do { > > > + old = v->counter; > > > > Likewise, arch_atomic64_read(v) here. > ack, this will bt arch_atomic_read(v) here since this is not atomic64_t > here. Ah, yes, my bad! Thanks, Mark. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv