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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 B1111C433E6 for ; Thu, 28 Jan 2021 11:53:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6FF0F64DDE for ; Thu, 28 Jan 2021 11:53:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231175AbhA1LxV (ORCPT ); Thu, 28 Jan 2021 06:53:21 -0500 Received: from mail-eopbgr70110.outbound.protection.outlook.com ([40.107.7.110]:46087 "EHLO EUR04-HE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S229852AbhA1LxQ (ORCPT ); Thu, 28 Jan 2021 06:53:16 -0500 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=KVzXpGKygFymlegFnoMC8AVNPkKK709m2r0tIs3SkgGAIQ9DJ+sGk7niU2VfTV3Y/G+uanG4klcu6AzrxzjumZ6Xna0leeXk320nTdUlZY5j9v2z4GYznKWHff5spnBO7XWBWEzAJg6U7a/ar1BQKn5IYFs08MDjIjuWuc5+Qr75hKFaN/aBF0rq+1gqySclQLxeW0z+hIpzJ5pom/kIcb0neT9yXyvaIrtnmeiUKt1shVhR+L2f6tH/mBnDNSpQF3AsBfM8WORznIIqbt9X0/4kUWhDf60MRug6xM0npiEUlyY8bTt1EjX3j5bpHpAi48DLCbsJRdGYxwOBJ+pzUQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=zcu94ajSAYFybAcp6GwpcgnmA8g0e8bUC8fbWPkW0/8=; b=dy/5H40AS4w1KdAYrkQ4QxP6cCAJBuXUYwbyuJf1WP0wTYsSKaA7oNGghK4yODLKuWWJppJFMMw2Knskcs0tdzd2bpcWYYrQLGU8y9UVc6Z2MiGWMKl7l5+/UpyUve7LBtrsWDdUwa90bPKwPYBeASdLS6qjHBR/q+ZRSLdPzv3cPu8gW6owsqFVcRN799tlIPm56+elrPSutxHgtTVPDsZDasb/DQbX6S0uyrhUyZHS6wPQv3gJWhJdV2Yr8K7xe9lio3cCUSKgmbK4zwJru6g+kXK9LIz55uB0ld0Wh+e7xGyTm2aiPOxV1R4kE6h+szqo11SDOWM8ewWXkb7Byg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nokia.com; dmarc=pass action=none header.from=nokia.com; dkim=pass header.d=nokia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nokia.onmicrosoft.com; s=selector1-nokia-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=zcu94ajSAYFybAcp6GwpcgnmA8g0e8bUC8fbWPkW0/8=; b=t/5Z1kITg5lPSod3GR/Ye+YMiKNpvAZiLDhp4xByegL/iFDPp1Cy+ZmrRZVC7j7Z+QCOPrskHLW11KsoXBjqSVbjSi1BFdavT3w1RbAdQdiHLI7UGMcnR41jBeQJ6Maza4yE8bjvy2yUcAAaf8avtjp7FlivQA+YLPoDNPvuDEY= Authentication-Results: vger.kernel.org; dkim=none (message not signed) header.d=none;vger.kernel.org; dmarc=none action=none header.from=nokia.com; Received: from (2603:10a6:208:6e::15) by AM4PR0701MB2209.eurprd07.prod.outlook.com (2603:10a6:200:45::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3825.8; Thu, 28 Jan 2021 11:52:25 +0000 Received: from AM0PR07MB4531.eurprd07.prod.outlook.com ([fe80::e965:2884:260b:b29a]) by AM0PR07MB4531.eurprd07.prod.outlook.com ([fe80::e965:2884:260b:b29a%3]) with mapi id 15.20.3825.008; Thu, 28 Jan 2021 11:52:25 +0000 Subject: Re: [PATCH 1/6] MIPS: Octeon: Implement __smp_store_release() To: Peter Zijlstra Cc: Paul Burton , linux-mips@vger.kernel.org, Thomas Bogendoerfer , Will Deacon , Boqun Feng , Ingo Molnar , linux-kernel@vger.kernel.org References: <20210127203627.47510-1-alexander.sverdlin@nokia.com> <20210127203627.47510-2-alexander.sverdlin@nokia.com> From: Alexander Sverdlin Message-ID: Date: Thu, 28 Jan 2021 12:52:22 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [131.228.32.169] X-ClientProxiedBy: AM0PR10CA0012.EURPRD10.PROD.OUTLOOK.COM (2603:10a6:208:17c::22) To AM0PR07MB4531.eurprd07.prod.outlook.com (2603:10a6:208:6e::15) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from ulegcpsvhp1.emea.nsn-net.net (131.228.32.169) by AM0PR10CA0012.EURPRD10.PROD.OUTLOOK.COM (2603:10a6:208:17c::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3805.17 via Frontend Transport; Thu, 28 Jan 2021 11:52:24 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: 206aa486-f8dd-4692-93fa-08d8c3832dfc X-MS-TrafficTypeDiagnostic: AM4PR0701MB2209: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:107; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:AM0PR07MB4531.eurprd07.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(366004)(136003)(396003)(376002)(39860400002)(346002)(6512007)(8676002)(6916009)(4326008)(31696002)(83380400001)(2906002)(6486002)(8936002)(36756003)(44832011)(6506007)(86362001)(53546011)(52116002)(66946007)(66556008)(66476007)(956004)(26005)(4744005)(2616005)(16526019)(316002)(186003)(478600001)(5660300002)(54906003)(31686004)(45980500001)(43740500002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?dGl1Z0Zta0IxUnFjQ1pWNk83QlMwVGF1b3FwQUNNaXNHTmtJemZkdlJSQVli?= =?utf-8?B?UGx0OFRweXdneTllTmhNTWdLT1luODZaaEhrTmYxS0xMMlU2ai94MU0yKzk4?= =?utf-8?B?WEZwR29JSWdXckZTODV4QmlGYmxzZTREcjd2ZDY5QXJ1L3pwTEVFWWU1Z2hy?= =?utf-8?B?ODNXTkxDTy9ScUV4enMxbllSWE5lbTVHVGRvSGoxRFFUN3JnM0ErL0NuTDRs?= =?utf-8?B?RWJCNFplMHVZZ205RnMzTURoZVpUeWpwSUliZUd5ZXEydmxWd3psL0xFUmdZ?= =?utf-8?B?dmpYeGUxMXpHdXkyeThQb29CWkh5SGhHYmp6b2cwV0ZUOXBSNGd4b2dDUWpu?= =?utf-8?B?REpTbXdRTTdueUdjR1dVNEY4a2duSTBoYmNsdFhNUTFSSHRtUUNhK2VXL0V6?= =?utf-8?B?WGF2NngxSzJQVGZYai8wWEdPRWRJUVBJOVNoOUJUNVVvdFcwQXB4amdqTmk3?= =?utf-8?B?RzJNT2Y5N3dpS09weDVDUW5EOFpmcXpmM2k5Vy9mbk1HQTc0aEZ0WTlVaHhs?= =?utf-8?B?YmVMN0ZsRHB2SGZiWjBFK3JacnhYaDZGdmpkQVczeDFqSHpadkRYQ01LK3pI?= =?utf-8?B?UXVaU1NZaFBnOCswYzE4YW94SEFId3MvdWhXVHhwVDZqdHZFZjA4YkNFd25z?= =?utf-8?B?WVpuZWhYWHo1K0F2VTBxcmxRRE5PUHdpcTFJZVhQaENONGJITWg2VkNmZFZV?= =?utf-8?B?UGxESXpsRXp2bGoyTk4vR0RUdWdTYmlIMDUwOG82anVJaFQ1ODN6SWlIVk03?= =?utf-8?B?YWJOV3E3Z1lnM2tlM3JNbURnOXFEdHlVYUdQUEg2b3RBcTF0SDlZTTlOTmho?= =?utf-8?B?N0g4eDNqZkFmOGZIaklEUkpJL3FpM0ZveFNMUnpjaDFPVUI2QzNkak9aS0hJ?= =?utf-8?B?RXYyL3NQYmlVRStFc3RJL3ZJcXAxd0k5RFc5WGY2Z054bVdQREVLa2o1cU95?= =?utf-8?B?WXdTdU00aDhRdWN5QlBhU1ZPaEpjTnVobHkzaXp4T2FHcGs1R1o3bFY2WVJL?= =?utf-8?B?UkZ6dkliVVc3QkQ3dHpiYWt3RGhjZEVWNHRtR2pZOUNzTStmalVxQ2NHRldW?= =?utf-8?B?OVRnd1RVSVlLb2RqNXM5V0ZUdTJlMXBpeW54VjEzakwwcU9wZHlBK0ZiL1dQ?= =?utf-8?B?bSthWXZ3WGlRdE5pL0lFdU5MRUNGd1A4THJoVEhHZDRwSk1CdEpnRGliOUFa?= =?utf-8?B?YWljcFlPNzdaT2dPclMrNVFUYlFXSE81dWdWY0tId2FieHpvYmhmN2RpMVVy?= =?utf-8?B?eVJRSDF5bC9mYXkvOHBsenY0WU96VkpQWVluOVhUdy9zdzNxZ1lQRGJZT1lu?= =?utf-8?B?VWNpUVNVci9XQityeEovd0xiSjAzRko1MzNWSFUrMFcrMzVwOXhnd3BaR3Q5?= =?utf-8?B?S2gzdVJHSVJBUldVUnNHNWdFLzRGbE85VnhsNlBXbjBvUXM3d3Q3bHZwZzRM?= =?utf-8?Q?tpUQQabv?= X-OriginatorOrg: nokia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 206aa486-f8dd-4692-93fa-08d8c3832dfc X-MS-Exchange-CrossTenant-AuthSource: AM0PR07MB4531.eurprd07.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Jan 2021 11:52:25.4323 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 5d471751-9675-428d-917b-70f44f9630b0 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: PDKV2Ea0RD8BGuWOweOnQFa6mz2ujVOP12nNn+N2fwZip5cE3Lkr7AwszcvpuLJXjuth4oXqA1pgGTtZbyuY1HWu7a+YaUoSUkQ+7NcKQZs= X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM4PR0701MB2209 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Peter, On 28/01/2021 12:33, Peter Zijlstra wrote: > This, from commit 6b07d38aaa52 ("MIPS: Octeon: Use optimized memory > barrier primitives."): > > #define smp_mb__before_llsc() smp_wmb() > #define __smp_mb__before_llsc() __smp_wmb() > > is also dodgy as hell and really wants a comment too. I'm not buying the > Changelog of that commit either, __smp_mb__before_llsc should also > ensure the LL cannot happen earlier, but SYNCW has no effect on loads. > So what stops the load from being speculated? hmm, the commit message you point to above, says: "Since Octeon does not do speculative reads, this functions as a full barrier." -- Best regards, Alexander Sverdlin.