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=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 9F110C433DF for ; Fri, 14 Aug 2020 11:59:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 73ACB207DA for ; Fri, 14 Aug 2020 11:59:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Hu6Nw7Hu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726213AbgHNL7V (ORCPT ); Fri, 14 Aug 2020 07:59:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726139AbgHNL7U (ORCPT ); Fri, 14 Aug 2020 07:59:20 -0400 Received: from mail-ot1-x344.google.com (mail-ot1-x344.google.com [IPv6:2607:f8b0:4864:20::344]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3276AC061384 for ; Fri, 14 Aug 2020 04:59:20 -0700 (PDT) Received: by mail-ot1-x344.google.com with SMTP id 93so7363881otx.2 for ; Fri, 14 Aug 2020 04:59:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=JH6kRqU1JrNcyy+wqdaUc+Qi4AywqVy9VYsywI2jKC4=; b=Hu6Nw7Hu8gfRjU0uxCY5ypd0wl/SaFstId/H02InWTfOh1qjNcvA7OEJQlw3IhBFYB ZbDdyVhOAJfmgJPLz3PmRAehofZkwiWforKlGlPfVZQIxs3eCEuX4V2gDHWHM3H641P9 5/95uaTUUeEsQV99+U2SeqIJMG+fs5/ppn/EFQP55KtLY079BqtlK164t0WVWA5OqFb5 1lDfFXlAbAxHW6RF3Iwt9D61belaN+pbNqJ2YQHi6R4ezzBMyWU1/2akcilZkTOMaK+x 9NcEVvBOT/kpSK5KK9wGBG+pRvyZhrhPX+tolqxoNe1i5ESpRXzLfnkuMa1GsLGkrNPc yiWw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=JH6kRqU1JrNcyy+wqdaUc+Qi4AywqVy9VYsywI2jKC4=; b=FfahEn2Vf7RGdvlUeRWYBQXAWhfiwK3vF30hL5V/ftcLWNrpyOshFWDUmgi5QImGnp LSKgF84TIWizQGwoEV7osPWU2ngS5o+amMVXXgjCu1h+HmA9wsQPE5fRpi+XiAjjOw4w soyQFaXFc0XthwObH0jM490eBzX5DWoaxrYI2wz5STM3RCoNM+jOASG/6TBw3GfnEYa9 dAo1ZvB0eMDzO9dodR9udUbyiQssYqj7uqkHeWpANRZd+J3dGvwyccgaUlUAnaLtPhaO u2AKMFXIuzn5nJDYhbhjf0K3bdn/VebxHypz1alAdYQtCrf9ACb2iahiLm2XBcTr03HK /bsA== X-Gm-Message-State: AOAM530hKoGo4pboK+1cTD6VAbwnxWhHKQ4Ceh5cTMcxK1WEJ+lUrhRW nyVm7no5EVpyExoOw9OpKr9Pdmiu1sbYSwBEVh224Q== X-Google-Smtp-Source: ABdhPJxPPgMpYvrWwruSOJ6rg0e4RTwqBnrs8Barm0/v/AauhxO/vwMhNciGBE2/TazprcJkQc2m1wlC4NQSO0JC60I= X-Received: by 2002:a05:6830:1612:: with SMTP id g18mr1480092otr.251.1597406359387; Fri, 14 Aug 2020 04:59:19 -0700 (PDT) MIME-Version: 1.0 References: <20200721103016.3287832-1-elver@google.com> <20200721103016.3287832-9-elver@google.com> <20200721141859.GC10769@hirez.programming.kicks-ass.net> <20200814112826.GB68877@C02TD0UTHF1T.local> <20200814113149.GC68877@C02TD0UTHF1T.local> In-Reply-To: <20200814113149.GC68877@C02TD0UTHF1T.local> From: Marco Elver Date: Fri, 14 Aug 2020 13:59:08 +0200 Message-ID: Subject: Re: [PATCH 8/8] locking/atomics: Use read-write instrumentation for atomic RMWs To: Mark Rutland Cc: Peter Zijlstra , "Paul E. McKenney" , Will Deacon , Arnd Bergmann , Dmitry Vyukov , Alexander Potapenko , kasan-dev , LKML , linux-arch Content-Type: text/plain; charset="UTF-8" Sender: linux-arch-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Fri, 14 Aug 2020 at 13:31, Mark Rutland wrote: > On Fri, Aug 14, 2020 at 12:28:26PM +0100, Mark Rutland wrote: > > Hi, > > > > Sorry to come to this rather late -- this comment equally applies to v2 > > so I'm replying here to have context. > > ... and now I see that was already applied, so please ignore this! Thank you for the comment anyway. If this is something urgent, we could send a separate patch to change. My argument in favour of keeping it as-is was that the alternative would throw away the "type" and we no longer recognize a difference between arguments (in fairness, currently not important though). If, say, we get an RMW that has a constant argument though, the current version would do the "right thing" as far as I can tell. Maybe I'm overly conservative here, but it saves us worrying about some future use-case breaking this more than before. Thanks, -- Marco