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=-6.4 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 0ADAAC433E1 for ; Wed, 19 Aug 2020 16:15:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BCD782083B for ; Wed, 19 Aug 2020 16:15:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="IR1k0y6b" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726884AbgHSQP0 (ORCPT ); Wed, 19 Aug 2020 12:15:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38614 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726640AbgHSQPS (ORCPT ); Wed, 19 Aug 2020 12:15:18 -0400 Received: from mail-pj1-x1044.google.com (mail-pj1-x1044.google.com [IPv6:2607:f8b0:4864:20::1044]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DA112C061757 for ; Wed, 19 Aug 2020 09:15:17 -0700 (PDT) Received: by mail-pj1-x1044.google.com with SMTP id e4so1342851pjd.0 for ; Wed, 19 Aug 2020 09:15:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:subject:to:cc:references:from:autocrypt:message-id:date :user-agent:mime-version:in-reply-to; bh=CkoBycTdFJbVwVUZgNhAFw6X5ZkP+re1+Sfuv+Eawwk=; b=IR1k0y6byO8sngJ5HRjTb7yA/92hiW+wczvFdz60zvKus6pflamZQhZoELyeB2E0rp WV7ITyBUR7kDAquJuuG5ACFuB6JN9WjsFq/LhydkQGjdiGwZusMKs6MAsw/jUti9Wyst 43FDYb3n4+L94faUt0/hxG6W3I2MfX3mfEsvcHEWDVnoYMNZSnEitz15yXFg9n0+4yao x6YEn+eJUy7MINMeW0e0mjwwaazTN3BpmAOmL/oTVEGrlr84G8Rbst8/92Sz6aX8dGTV aaLM6LZV7ED/QcZL3sCfw3hJUE0aJkS+SlM5QENI1y3WUHRs3YPAQAdQkEsBPBVgJ1SX vK2A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:subject:to:cc:references:from:autocrypt :message-id:date:user-agent:mime-version:in-reply-to; bh=CkoBycTdFJbVwVUZgNhAFw6X5ZkP+re1+Sfuv+Eawwk=; b=QDoKhfq+qXyeCXbT36oa7VZ2kyjtgicIOMz9zUUOIjEhU0uzG1BoUeNFQNxzF5qISX 5QwMtxtCtLuasvp4O6MELRPeKjp7ShpbYlyJAQM7CuaWQoRf4VVqC1ew4ctfPunL9JqA WMTeiUDi6s6CvmY8qX7qcj7Sc0qE+cub8HTsVlIE3QWfD7+788/kZ04jhwrJ2D5YAkQ8 lDE2Sh27lDOshbu9jYWbrS5pjWfvRZG6jONMwdnqdtTDs6SiUNAXIloXv6VCzamJB3QJ dptJI+b5mRFY4EbWBS6oXiONQP529BKfj5DhNcOCEpYQNjfFRl8iVGHxTKn1SAFrUl0e dThg== X-Gm-Message-State: AOAM533xXmYbbvGBjqK6iE+XN06HIYUDFh/JzWGWl+p4ZkGd/FYRGhA6 /3qR5SYw4Jj6hJouqzX8zrs= X-Google-Smtp-Source: ABdhPJwpeUA6Cp36nPXL7rQZvCFaOCN3XRyAo3IGSkECFfOZhwpEFWhs0Rq5XOpBbMx/d7gfv12VTA== X-Received: by 2002:a17:902:7d85:: with SMTP id a5mr19403438plm.148.1597853717375; Wed, 19 Aug 2020 09:15:17 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id l24sm26264045pff.20.2020.08.19.09.15.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 19 Aug 2020 09:15:16 -0700 (PDT) Subject: Re: [PATCH] Revert "seqlock: lockdep assert non-preemptibility on seqcount_t write" To: =?UTF-8?Q?Valdis_Kl=c4=93tnieks?= , Sebastian Andrzej Siewior Cc: Mark Starovoytov , Igor Russkikh , "David S. Miller" , Greg KH , "Ahmed S. Darwish" , linux-kernel@vger.kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, tglx@linutronix.de, will@kernel.org References: <20200810085954.GA1591892@kroah.com> <20200810095428.2602276-1-a.darwish@linutronix.de> <20200810100502.GA2406768@kroah.com> <169454.1597791078@turing-police> <20200819070022.semyxepadnvtmtcr@linutronix.de> <15863.1597822443@turing-police> From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAlVcphcFCRmg06EACgkQyx8mb86fmYFg0RAA nzXJzuPkLJaOmSIzPAqqnutACchT/meCOgMEpS5oLf6xn5ySZkl23OxuhpMZTVX+49c9pvBx hpvl5bCWFu5qC1jC2eWRYU+aZZE4sxMaAGeWenQJsiG9lP8wkfCJP3ockNu0ZXXAXwIbY1O1 c+l11zQkZw89zNgWgKobKzrDMBFOYtAh0pAInZ9TSn7oA4Ctejouo5wUugmk8MrDtUVXmEA9 7f9fgKYSwl/H7dfKKsS1bDOpyJlqhEAH94BHJdK/b1tzwJCFAXFhMlmlbYEk8kWjcxQgDWMu GAthQzSuAyhqyZwFcOlMCNbAcTSQawSo3B9yM9mHJne5RrAbVz4TWLnEaX8gA5xK3uCNCeyI sqYuzA4OzcMwnnTASvzsGZoYHTFP3DQwf2nzxD6yBGCfwNGIYfS0i8YN8XcBgEcDFMWpOQhT Pu3HeztMnF3HXrc0t7e5rDW9zCh3k2PA6D2NV4fews9KDFhLlTfCVzf0PS1dRVVWM+4jVl6l HRIAgWp+2/f8dx5vPc4Ycp4IsZN0l1h9uT7qm1KTwz+sSl1zOqKD/BpfGNZfLRRxrXthvvY8 BltcuZ4+PGFTcRkMytUbMDFMF9Cjd2W9dXD35PEtvj8wnEyzIos8bbgtLrGTv/SYhmPpahJA l8hPhYvmAvpOmusUUyB30StsHIU2LLccUPPOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAlVcpi8FCRmg08MACgkQyx8mb86fmYHNRQ/+ J0OZsBYP4leJvQF8lx9zif+v4ZY/6C9tTcUv/KNAE5leyrD4IKbnV4PnbrVhjq861it/zRQW cFpWQszZyWRwNPWUUz7ejmm9lAwPbr8xWT4qMSA43VKQ7ZCeTQJ4TC8kjqtcbw41SjkjrcTG wF52zFO4bOWyovVAPncvV9eGA/vtnd3xEZXQiSt91kBSqK28yjxAqK/c3G6i7IX2rg6pzgqh hiH3/1qM2M/LSuqAv0Rwrt/k+pZXE+B4Ud42hwmMr0TfhNxG+X7YKvjKC+SjPjqp0CaztQ0H nsDLSLElVROxCd9m8CAUuHplgmR3seYCOrT4jriMFBtKNPtj2EE4DNV4s7k0Zy+6iRQ8G8ng QjsSqYJx8iAR8JRB7Gm2rQOMv8lSRdjva++GT0VLXtHULdlzg8VjDnFZ3lfz5PWEOeIMk7Rj trjv82EZtrhLuLjHRCaG50OOm0hwPSk1J64R8O3HjSLdertmw7eyAYOo4RuWJguYMg5DRnBk WkRwrSuCn7UG+qVWZeKEsFKFOkynOs3pVbcbq1pxbhk3TRWCGRU5JolI4ohy/7JV1TVbjiDI HP/aVnm6NC8of26P40Pg8EdAhajZnHHjA7FrJXsy3cyIGqvg9os4rNkUWmrCfLLsZDHD8FnU mDW4+i+XlNFUPUYMrIKi9joBhu18ssf5i5Q= Message-ID: Date: Wed, 19 Aug 2020 09:15:14 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <15863.1597822443@turing-police> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="R5ny2Hr4xMT4iUvdJepl6mR3v8KtgAsh0" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --R5ny2Hr4xMT4iUvdJepl6mR3v8KtgAsh0 Content-Type: multipart/mixed; boundary="7etqfthk5t6j4xxTmavMJ9ZLowvlkYtBL" --7etqfthk5t6j4xxTmavMJ9ZLowvlkYtBL Content-Type: text/plain; charset=UTF-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 8/19/20 12:34 AM, Valdis Kl=C4=93tnieks wrote: > On Wed, 19 Aug 2020 09:00:22 +0200, Sebastian Andrzej Siewior said: >> On 2020-08-18 17:56:49 [-0700], Guenter Roeck wrote: >>> Nice catch. FWIW, there is no obvious reason why this would need to b= e atomic. >>> The calling code does not set a lock, meaning there can be two (or mo= re) >>> callers entering this code. Weird, especially since the code looks li= ke it >>> would actually need a mutex to work correctly. It might be interestin= g to >>> see what happens if there are, say, half a dozen scripts/processes tr= ying >>> to read the hwmon attribute introduced by this patch at the same time= =2E >> >> =3D> https://lkml.kernel.org/r/20200818161439.3dkf6jzp3vuwmvvh@linutro= nix.de >=20 > Looks reasonable to me, though I've not verified that it's preemptible = at that > point... >=20 hw_atl_b0_get_mac_temp is called through the .hw_get_mac_temp callback. This callback is executed from aq_hwmon_read(), which in turn is called from the hwmon core, more specifically from hwmon_attr_show(). Calls from the hwmon core are unlocked. Guenter --7etqfthk5t6j4xxTmavMJ9ZLowvlkYtBL-- --R5ny2Hr4xMT4iUvdJepl6mR3v8KtgAsh0 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEiHPvMQj9QTOCiqgVyx8mb86fmYEFAl89UBIACgkQyx8mb86f mYE2Zw/+O8qwhmPTiHgUk7kSzCLZYUD2ff80lIaKw0Kqb+03oWbn85Lt3C81Db5i sugtFHPq1KOKJBXFITCE1AXjjr2p2M5ZvRKA2u867zKORkcu+fo5b7Dw4fZ6exmh d/dqm+7+y1+2Bn5Wep0B5ZhDQIBc7341Xbr6jtcD6hg3eqcnST99IsJduTZpVl7Y SfWPq+EUJyRfThw27pqKN2x9DL4y4vYET8plcPSEKJP/IJIlRanO+cNNYYC6mHny 5nPUC9E5pzcn3LNzipAD+CFFmi3vlk6EymrypbMCBCqTzIsgnbEYvARTFm1sy03k Qiaj2k2R2oz4zU16DkJCKoADss+MhLeMrechbcr1E7EgPz2GmT8KyXd4rNz8S8VY pK2+BD21POe07ZjAXA0iv5m8onL1BDfLmtpek5bB3B3JcsHSdiEAAziECCujxNcz CkKImTM9EGtDNHkcN1QDY94PO7GoA9NvvS1KKB2KVas2kbEXPBcbnGaiH6/9BXO7 3tztFENx3fME+rqM/O8aXD0W742sO7lifT3wQ9kkxj9YFmaKpEhsK1QRS63u6RWQ 78k4cgpi3DbClb3C7BQPVqwSZAbVFRnsX0cSu/voWjukWrVSUHwXel5dZdbGhzyF GVjc9rCcst26vXxDISEhKSWuSnfIvI4lDakJseP4jxpcfyXczYc= =iJtF -----END PGP SIGNATURE----- --R5ny2Hr4xMT4iUvdJepl6mR3v8KtgAsh0--