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=-7.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 10E11C48BE5 for ; Sat, 19 Jun 2021 06:02:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E444161159 for ; Sat, 19 Jun 2021 06:02:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233766AbhFSGEl (ORCPT ); Sat, 19 Jun 2021 02:04:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55138 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233714AbhFSGEk (ORCPT ); Sat, 19 Jun 2021 02:04:40 -0400 Received: from mail-pl1-x634.google.com (mail-pl1-x634.google.com [IPv6:2607:f8b0:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0017C061574; Fri, 18 Jun 2021 23:02:28 -0700 (PDT) Received: by mail-pl1-x634.google.com with SMTP id h1so5786123plt.1; Fri, 18 Jun 2021 23:02:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:subject:to:cc:references:in-reply-to:mime-version :message-id:content-transfer-encoding; bh=6wKXgd/ZhGiTUrwlorOP1aKdH3EvNfTZEGLOVoYRfnA=; b=HqTuCzfRgtpxdtQsv5eXBAj6MY60ow4aM/DQATcTOrV/s2Z1lom+u5+UgkGJyFUMrR sBm4Hw8mpm1b2NWuVNjV5HlFClau9nEewZt/h5Noo7Rxilij1QenUcYn5TMTv2ep4BZh dezXiQiqQdwaClkPIiahsQD+wZr7r1cZzkkO94gYiK7GiRmDf84djWdzNhK6Dgtb4qgY OFedJiTkHTSjVlGO0m4koiJ3G1Q/py26GcIKMZ7f2d4P4OipQ7ebZz3xK/obxcf2M4EW TENafsgnBHGZNkqqvs4TCdkFQy6vdlx6ZMaNPOSS9IhtgLW2s2dztU5ieTx1F7/KHX/y Gsfw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:subject:to:cc:references:in-reply-to :mime-version:message-id:content-transfer-encoding; bh=6wKXgd/ZhGiTUrwlorOP1aKdH3EvNfTZEGLOVoYRfnA=; b=nnoUKQ1K4qhdtmlbSWTp3pzedw/7Pgmsb6iKAj2ly6Q/0egV+V5QYwllyhmK7/aLJH CTG/mZsXfH/un6rImrP83fiUev/S32rMtTfP0K3BX9jDSl97JQpRrH2ahVsySOiG8RDr Idtkp26MqyidxBwN3L+Pjy94B5Gl0x7PVfRXw4ZG1GLXrY4rMmQAhw6eGogQPvfGNy2x ZS8vitztEQ5f8Vps3c53Tk+do4adpVYic2eXEmI79Hl5LFe9nJWYZs/dhLLOR5Fan8MT HKBzV48zlwEuwbR61Y3ahv7xTOCIaeQXWhb3EMJQj/uWFJB/TWSF1bBggwCvvJxnVFP7 /XGQ== X-Gm-Message-State: AOAM532To7KAGTq9seqtrjGvGg1UL3GlyvF2WMEkaB9z8ukzqKm7Q3uQ GVcgzF7c50HHZgs/9Epb0jM= X-Google-Smtp-Source: ABdhPJyKMGe6svO1edmje4gRVg+O1L9zIRT6wzOtEKvbi1F4rLOfCjfJ9mjTw5mzRepW9QleX5pgcQ== X-Received: by 2002:a17:902:b218:b029:11a:bf7b:1a80 with SMTP id t24-20020a170902b218b029011abf7b1a80mr8106460plr.82.1624082548020; Fri, 18 Jun 2021 23:02:28 -0700 (PDT) Received: from localhost (60-242-147-73.tpgi.com.au. [60.242.147.73]) by smtp.gmail.com with ESMTPSA id s123sm9246118pfb.78.2021.06.18.23.02.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Jun 2021 23:02:27 -0700 (PDT) Date: Sat, 19 Jun 2021 16:02:21 +1000 From: Nicholas Piggin Subject: Re: [PATCH 8/8] membarrier: Rewrite sync_core_before_usermode() and improve documentation To: Andy Lutomirski , Mathieu Desnoyers Cc: Andrew Morton , Benjamin Herrenschmidt , Catalin Marinas , Dave Hansen , linux-arm-kernel , linux-kernel , linux-mm , linuxppc-dev , Michael Ellerman , Paul Mackerras , Peter Zijlstra , stable , Will Deacon , x86 References: <07a8b963002cb955b7516e61bad19514a3acaa82.1623813516.git.luto@kernel.org> <827549827.10547.1623941277868.JavaMail.zimbra@efficios.com> <26196903-4aee-33c4-bed8-8bf8c7b46793@kernel.org> <593983567.12619.1624033908849.JavaMail.zimbra@efficios.com> <1d617df2-57fa-4953-9c75-6de3909a6f14@www.fastmail.com> <639092151.13266.1624046981084.JavaMail.zimbra@efficios.com> In-Reply-To: <639092151.13266.1624046981084.JavaMail.zimbra@efficios.com> MIME-Version: 1.0 Message-Id: <1624080924.z61zvzi4cq.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Excerpts from Mathieu Desnoyers's message of June 19, 2021 6:09 am: > ----- On Jun 18, 2021, at 3:58 PM, Andy Lutomirski luto@kernel.org wrote: >=20 >> On Fri, Jun 18, 2021, at 9:31 AM, Mathieu Desnoyers wrote: >>> ----- On Jun 17, 2021, at 8:12 PM, Andy Lutomirski luto@kernel.org wrot= e: >>>=20 >>> > On 6/17/21 7:47 AM, Mathieu Desnoyers wrote: >>> >=20 >>> >> Please change back this #ifndef / #else / #endif within function for >>> >>=20 >>> >> if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE)) { >>> >> ... >>> >> } else { >>> >> ... >>> >> } >>> >>=20 >>> >> I don't think mixing up preprocessor and code logic makes it more re= adable. >>> >=20 >>> > I agree, but I don't know how to make the result work well. >>> > membarrier_sync_core_before_usermode() isn't defined in the !IS_ENABL= ED >>> > case, so either I need to fake up a definition or use #ifdef. >>> >=20 >>> > If I faked up a definition, I would want to assert, at build time, th= at >>> > it isn't called. I don't think we can do: >>> >=20 >>> > static void membarrier_sync_core_before_usermode() >>> > { >>> > BUILD_BUG_IF_REACHABLE(); >>> > } >>>=20 >>> Let's look at the context here: >>>=20 >>> static void ipi_sync_core(void *info) >>> { >>> [....] >>> membarrier_sync_core_before_usermode() >>> } >>>=20 >>> ^ this can be within #ifdef / #endif >>>=20 >>> static int membarrier_private_expedited(int flags, int cpu_id) >>> [...] >>> if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE)) >>> return -EINVAL; >>> if (!(atomic_read(&mm->membarrier_state) & >>> MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READ= Y)) >>> return -EPERM; >>> ipi_func =3D ipi_sync_core; >>>=20 >>> All we need to make the line above work is to define an empty ipi_sync_= core >>> function in the #else case after the ipi_sync_core() function definitio= n. >>>=20 >>> Or am I missing your point ? >>=20 >> Maybe? >>=20 >> My objection is that an empty ipi_sync_core is a lie =E2=80=94 it doesn= =E2=80=99t sync the core. >> I would be fine with that if I could have the compiler statically verify= that >> it=E2=80=99s not called, but I=E2=80=99m uncomfortable having it there i= f the implementation is >> actively incorrect. >=20 > I see. Another approach would be to implement a "setter" function to popu= late > "ipi_func". That setter function would return -EINVAL in its #ifndef CONF= IG_ARCH_HAS_MEMBARRIER_SYNC_CORE > implementation. I still don't get the problem with my suggestion. Sure the=20 ipi is a "lie", but it doesn't get used. That's how a lot of ifdef folding works out. E.g., diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index b5add64d9698..54cb32d064af 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -5,6 +5,15 @@ * membarrier system call */ #include "sched.h" +#ifdef CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE +#include +#else +static inline void membarrier_sync_core_before_usermode(void) +{ + compiletime_assert(0, "architecture does not implement membarrier_sync_co= re_before_usermode"); +} + +#endif =20 /* * For documentation purposes, here are some membarrier ordering 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=-5.5 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 0C83FC2B9F4 for ; Sat, 19 Jun 2021 06:03:03 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 19ED86113C for ; Sat, 19 Jun 2021 06:03:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 19ED86113C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4G6QFK02Dxz3c5L for ; Sat, 19 Jun 2021 16:03:01 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=HqTuCzfR; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gmail.com (client-ip=2607:f8b0:4864:20::1029; helo=mail-pj1-x1029.google.com; envelope-from=npiggin@gmail.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=HqTuCzfR; dkim-atps=neutral Received: from mail-pj1-x1029.google.com (mail-pj1-x1029.google.com [IPv6:2607:f8b0:4864:20::1029]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4G6QDp2kvfz301K for ; Sat, 19 Jun 2021 16:02:33 +1000 (AEST) Received: by mail-pj1-x1029.google.com with SMTP id h16so6942498pjv.2 for ; Fri, 18 Jun 2021 23:02:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:subject:to:cc:references:in-reply-to:mime-version :message-id:content-transfer-encoding; bh=6wKXgd/ZhGiTUrwlorOP1aKdH3EvNfTZEGLOVoYRfnA=; b=HqTuCzfRgtpxdtQsv5eXBAj6MY60ow4aM/DQATcTOrV/s2Z1lom+u5+UgkGJyFUMrR sBm4Hw8mpm1b2NWuVNjV5HlFClau9nEewZt/h5Noo7Rxilij1QenUcYn5TMTv2ep4BZh dezXiQiqQdwaClkPIiahsQD+wZr7r1cZzkkO94gYiK7GiRmDf84djWdzNhK6Dgtb4qgY OFedJiTkHTSjVlGO0m4koiJ3G1Q/py26GcIKMZ7f2d4P4OipQ7ebZz3xK/obxcf2M4EW TENafsgnBHGZNkqqvs4TCdkFQy6vdlx6ZMaNPOSS9IhtgLW2s2dztU5ieTx1F7/KHX/y Gsfw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:subject:to:cc:references:in-reply-to :mime-version:message-id:content-transfer-encoding; bh=6wKXgd/ZhGiTUrwlorOP1aKdH3EvNfTZEGLOVoYRfnA=; b=W6yKM+93VpDNnDEiQn02Mc320xFczask2U0cQc+CiT/FfGuBW+XJLdJWZAgMhHdcBp C4DF6fz/0zS5nveLCQ6vgOSOJpJBSgcDeSzFpqkOJtUDv4Tr6OMDR4UHnpbYwG1FKHIw ue1wm6NPrgdNflDiRLGALkLjQq3anvpm93OXYVue7myezSrTJ8feqhxcknCz55vXyWjq D1ZoOF/PZh63N6yEmoP5CgAD7X4pK3KJw3UbCx8Xa62k7txSW1Iy4YKCUjiBdqT057QI ia1j1/J33BMGH1XenBtqSXZccA70oIs62FkTsEB8zr4g9GdlkEhdQ97NxLCaHa2Qe4l3 rx+w== X-Gm-Message-State: AOAM532buf6X2ztmwXLjeXKumEdSEJBgemp76joKyAR4bC8qONcLH6aH M3qay+fX85r/pHtfbHAeGrQ= X-Google-Smtp-Source: ABdhPJyKMGe6svO1edmje4gRVg+O1L9zIRT6wzOtEKvbi1F4rLOfCjfJ9mjTw5mzRepW9QleX5pgcQ== X-Received: by 2002:a17:902:b218:b029:11a:bf7b:1a80 with SMTP id t24-20020a170902b218b029011abf7b1a80mr8106460plr.82.1624082548020; Fri, 18 Jun 2021 23:02:28 -0700 (PDT) Received: from localhost (60-242-147-73.tpgi.com.au. [60.242.147.73]) by smtp.gmail.com with ESMTPSA id s123sm9246118pfb.78.2021.06.18.23.02.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Jun 2021 23:02:27 -0700 (PDT) Date: Sat, 19 Jun 2021 16:02:21 +1000 From: Nicholas Piggin Subject: Re: [PATCH 8/8] membarrier: Rewrite sync_core_before_usermode() and improve documentation To: Andy Lutomirski , Mathieu Desnoyers References: <07a8b963002cb955b7516e61bad19514a3acaa82.1623813516.git.luto@kernel.org> <827549827.10547.1623941277868.JavaMail.zimbra@efficios.com> <26196903-4aee-33c4-bed8-8bf8c7b46793@kernel.org> <593983567.12619.1624033908849.JavaMail.zimbra@efficios.com> <1d617df2-57fa-4953-9c75-6de3909a6f14@www.fastmail.com> <639092151.13266.1624046981084.JavaMail.zimbra@efficios.com> In-Reply-To: <639092151.13266.1624046981084.JavaMail.zimbra@efficios.com> MIME-Version: 1.0 Message-Id: <1624080924.z61zvzi4cq.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Will Deacon , linux-mm , Peter Zijlstra , x86 , linux-kernel , stable , Dave Hansen , Paul Mackerras , Catalin Marinas , Andrew Morton , linuxppc-dev , linux-arm-kernel Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Excerpts from Mathieu Desnoyers's message of June 19, 2021 6:09 am: > ----- On Jun 18, 2021, at 3:58 PM, Andy Lutomirski luto@kernel.org wrote: >=20 >> On Fri, Jun 18, 2021, at 9:31 AM, Mathieu Desnoyers wrote: >>> ----- On Jun 17, 2021, at 8:12 PM, Andy Lutomirski luto@kernel.org wrot= e: >>>=20 >>> > On 6/17/21 7:47 AM, Mathieu Desnoyers wrote: >>> >=20 >>> >> Please change back this #ifndef / #else / #endif within function for >>> >>=20 >>> >> if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE)) { >>> >> ... >>> >> } else { >>> >> ... >>> >> } >>> >>=20 >>> >> I don't think mixing up preprocessor and code logic makes it more re= adable. >>> >=20 >>> > I agree, but I don't know how to make the result work well. >>> > membarrier_sync_core_before_usermode() isn't defined in the !IS_ENABL= ED >>> > case, so either I need to fake up a definition or use #ifdef. >>> >=20 >>> > If I faked up a definition, I would want to assert, at build time, th= at >>> > it isn't called. I don't think we can do: >>> >=20 >>> > static void membarrier_sync_core_before_usermode() >>> > { >>> > BUILD_BUG_IF_REACHABLE(); >>> > } >>>=20 >>> Let's look at the context here: >>>=20 >>> static void ipi_sync_core(void *info) >>> { >>> [....] >>> membarrier_sync_core_before_usermode() >>> } >>>=20 >>> ^ this can be within #ifdef / #endif >>>=20 >>> static int membarrier_private_expedited(int flags, int cpu_id) >>> [...] >>> if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE)) >>> return -EINVAL; >>> if (!(atomic_read(&mm->membarrier_state) & >>> MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READ= Y)) >>> return -EPERM; >>> ipi_func =3D ipi_sync_core; >>>=20 >>> All we need to make the line above work is to define an empty ipi_sync_= core >>> function in the #else case after the ipi_sync_core() function definitio= n. >>>=20 >>> Or am I missing your point ? >>=20 >> Maybe? >>=20 >> My objection is that an empty ipi_sync_core is a lie =E2=80=94 it doesn= =E2=80=99t sync the core. >> I would be fine with that if I could have the compiler statically verify= that >> it=E2=80=99s not called, but I=E2=80=99m uncomfortable having it there i= f the implementation is >> actively incorrect. >=20 > I see. Another approach would be to implement a "setter" function to popu= late > "ipi_func". That setter function would return -EINVAL in its #ifndef CONF= IG_ARCH_HAS_MEMBARRIER_SYNC_CORE > implementation. I still don't get the problem with my suggestion. Sure the=20 ipi is a "lie", but it doesn't get used. That's how a lot of ifdef folding works out. E.g., diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index b5add64d9698..54cb32d064af 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -5,6 +5,15 @@ * membarrier system call */ #include "sched.h" +#ifdef CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE +#include +#else +static inline void membarrier_sync_core_before_usermode(void) +{ + compiletime_assert(0, "architecture does not implement membarrier_sync_co= re_before_usermode"); +} + +#endif =20 /* * For documentation purposes, here are some membarrier ordering 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=-5.7 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 9C2ADC2B9F4 for ; Sat, 19 Jun 2021 06:04:41 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 5737B61057 for ; Sat, 19 Jun 2021 06:04:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5737B61057 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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:Message-Id:MIME-Version:In-Reply-To: References:Cc:To:Subject:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=YGdS/haRPF7Jku3RdKbKZPnDfHFsTQtDPZSfRWKbclA=; b=1/Qr7tf4pOpwiO P8V2wmqzub2IGzGNJzFkj9vj+4H+hPB7Y+wKfKItx7PX0a2MYQGx5RRnbzpWqZ3fqXU6UsbueSctb fITMS6Av1K9LCHAjpWP4v5xgMgJIUV4CZD1zC/R/SDXA45ZQ/pQjoJzmlCh8bL8Jvc7SV6Y17yv2y cwRRKWOWinDrt6tOpFfG5DtrUix+Xe9Z3ZlacZUJPwFL3NH+ifo4H20qGpEFAare4GbQZlNgGHlW1 DJwQyQ/v/WewZq4YZBTCRyztCfXhdI3bLLWvCdszwowDJhtsGPtJj5hrtHrNibQwF0dHmsRhu500Y O0re5x/QEGWnGLWgJ4PQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1luU3s-00GQkM-Fi; Sat, 19 Jun 2021 06:02:32 +0000 Received: from mail-pj1-x102f.google.com ([2607:f8b0:4864:20::102f]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1luU3o-00GQjD-NT for linux-arm-kernel@lists.infradead.org; Sat, 19 Jun 2021 06:02:30 +0000 Received: by mail-pj1-x102f.google.com with SMTP id p4-20020a17090a9304b029016f3020d867so5067305pjo.3 for ; Fri, 18 Jun 2021 23:02:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:subject:to:cc:references:in-reply-to:mime-version :message-id:content-transfer-encoding; bh=6wKXgd/ZhGiTUrwlorOP1aKdH3EvNfTZEGLOVoYRfnA=; b=HqTuCzfRgtpxdtQsv5eXBAj6MY60ow4aM/DQATcTOrV/s2Z1lom+u5+UgkGJyFUMrR sBm4Hw8mpm1b2NWuVNjV5HlFClau9nEewZt/h5Noo7Rxilij1QenUcYn5TMTv2ep4BZh dezXiQiqQdwaClkPIiahsQD+wZr7r1cZzkkO94gYiK7GiRmDf84djWdzNhK6Dgtb4qgY OFedJiTkHTSjVlGO0m4koiJ3G1Q/py26GcIKMZ7f2d4P4OipQ7ebZz3xK/obxcf2M4EW TENafsgnBHGZNkqqvs4TCdkFQy6vdlx6ZMaNPOSS9IhtgLW2s2dztU5ieTx1F7/KHX/y Gsfw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:subject:to:cc:references:in-reply-to :mime-version:message-id:content-transfer-encoding; bh=6wKXgd/ZhGiTUrwlorOP1aKdH3EvNfTZEGLOVoYRfnA=; b=tjEBKsefH39J8gHR5TV0QgHY7JiFu+v+GyztjhY4oaAM1623TdTFbyUg+BCBAhJkTx vMIxEp+rP5r7t/Rhoyw67rstcKUB1DUcL2rVkUwS01kemkhexvmWb8UL9flPPuT4muws lujEVYmYPCSW7c04A/DdXUTkGnZJ2M6QyXZfaUjsrXN+143X/LN2cKSeexy8SvKl+JiR wjqgGATdWGfYXTuV++YEOYxRopYHNtP5/m7RG0A1u39+E7gV70Tpkx3BpSzd/ZV8p9C/ g/89AiwhyQt0GizZssJ5qsuETY5jsPofsFrjldYiaM4TcUsvYp/67d0s8eXTYyS9882n jN9w== X-Gm-Message-State: AOAM530XUIdKvLgX4eYR6LhldId7eVWJcty+iWGvMUrxRNSMmZk1NmG+ 8hCurbMsg4afoJnZ9EgPYy8= X-Google-Smtp-Source: ABdhPJyKMGe6svO1edmje4gRVg+O1L9zIRT6wzOtEKvbi1F4rLOfCjfJ9mjTw5mzRepW9QleX5pgcQ== X-Received: by 2002:a17:902:b218:b029:11a:bf7b:1a80 with SMTP id t24-20020a170902b218b029011abf7b1a80mr8106460plr.82.1624082548020; Fri, 18 Jun 2021 23:02:28 -0700 (PDT) Received: from localhost (60-242-147-73.tpgi.com.au. [60.242.147.73]) by smtp.gmail.com with ESMTPSA id s123sm9246118pfb.78.2021.06.18.23.02.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Jun 2021 23:02:27 -0700 (PDT) Date: Sat, 19 Jun 2021 16:02:21 +1000 From: Nicholas Piggin Subject: Re: [PATCH 8/8] membarrier: Rewrite sync_core_before_usermode() and improve documentation To: Andy Lutomirski , Mathieu Desnoyers Cc: Andrew Morton , Benjamin Herrenschmidt , Catalin Marinas , Dave Hansen , linux-arm-kernel , linux-kernel , linux-mm , linuxppc-dev , Michael Ellerman , Paul Mackerras , Peter Zijlstra , stable , Will Deacon , x86 References: <07a8b963002cb955b7516e61bad19514a3acaa82.1623813516.git.luto@kernel.org> <827549827.10547.1623941277868.JavaMail.zimbra@efficios.com> <26196903-4aee-33c4-bed8-8bf8c7b46793@kernel.org> <593983567.12619.1624033908849.JavaMail.zimbra@efficios.com> <1d617df2-57fa-4953-9c75-6de3909a6f14@www.fastmail.com> <639092151.13266.1624046981084.JavaMail.zimbra@efficios.com> In-Reply-To: <639092151.13266.1624046981084.JavaMail.zimbra@efficios.com> MIME-Version: 1.0 Message-Id: <1624080924.z61zvzi4cq.astroid@bobo.none> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210618_230228_853811_B2B6C334 X-CRM114-Status: GOOD ( 20.72 ) 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; 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