Received: by 2002:a05:6a10:a0d1:0:0:0:0 with SMTP id j17csp4350956pxa; Mon, 10 Aug 2020 07:11:49 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxwap7IZG2KFnwnARztNTuyXMTULJsdOEQ8EmJCr17puXvuzm2pGxxtSYNtR8CibkUQ9rHX X-Received: by 2002:a17:906:3b18:: with SMTP id g24mr21370553ejf.508.1597068709414; Mon, 10 Aug 2020 07:11:49 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1597068709; cv=none; d=google.com; s=arc-20160816; b=XSn4xFk2LbXOmXytOnRajQSlQxIxyhlfnyvKDPtvu89uU6PNwMQSJ4vXaBTAHVaBb7 e5ldiVCQZgNG/6gH7tAkxKb3DJk2MjOyIAmi5Rh/lX7yT6h4pS9eG3hKEq715mP5Bebi Y7FwdAXS4Gf6ugXPsVk4gkRsSX7IIageBU68xd2EAlTzHutT/zyfu21vHyZaYDydUhlq xD1Ah02fPuh7CHjwHtdaIxT2WUiQbti9GeXK0msl/Q7+kUOTdb3Een+gXKjTDnPy7RNL /uCH8ZIrO8Ce9s4U+OWGqxxZe2VGqoYXBdIHPFq/FOLKJkWxNK3pH0XQsvkllSqKUbuK klFg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding :content-language:in-reply-to:mime-version:user-agent:date :message-id:autocrypt:from:references:cc:to:subject:dkim-signature; bh=+J/Oc1375S3Mr5QmPzxTFCZZPHRpST6WJPtH7+jp6BE=; b=X/iOb3m+dW1KDT9fzcA0kdE95Hp0UQ0GJgtt774EMmJ547jSt7zssYHaQfvMlGSEen 3igSoAyN2DuuxIfizwkziu0EiP6hGJptctFa7l1X7KqCY2CZHNJPjyD/yXOrnYlKmOWP YFVnVUyzogT7rMOS6D27c5P5Jl9wsDpzfINhFRwOu+4Fu03ujeS1XOtyEgCkq4HfgzZ/ PG3eEzsWwruJ+Zn5d30JMxEcOXH/jzQIRx25TzRO9lLf89yfgtF/tEfuVlZpNHryJQwm 53NjjIT0TiF0BUigdkTa2LhRIMtDTPf2KEZpAcr/hBAZ/uOXa04G/85aQHH/qQoq0ABm f7UA== ARC-Authentication-Results: i=1; mx.google.com; dkim=fail header.i=@gmail.com header.s=20161025 header.b=TdP0v+vu; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id v25si10728226ejb.238.2020.08.10.07.11.26; Mon, 10 Aug 2020 07:11:49 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=fail header.i=@gmail.com header.s=20161025 header.b=TdP0v+vu; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726897AbgHJOKi (ORCPT + 99 others); Mon, 10 Aug 2020 10:10:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726814AbgHJOKg (ORCPT ); Mon, 10 Aug 2020 10:10:36 -0400 Received: from mail-pg1-x541.google.com (mail-pg1-x541.google.com [IPv6:2607:f8b0:4864:20::541]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4FC09C061756 for ; Mon, 10 Aug 2020 07:10:36 -0700 (PDT) Received: by mail-pg1-x541.google.com with SMTP id o13so4942811pgf.0 for ; Mon, 10 Aug 2020 07:10:36 -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:content-language :content-transfer-encoding; bh=+J/Oc1375S3Mr5QmPzxTFCZZPHRpST6WJPtH7+jp6BE=; b=TdP0v+vul0dd83LHD9L+PL0bukX+v74d9vF+Fkcf3MoL42Hss5SPz/6A3tl/na4ynU aT2jkdSABwLxvJh8QgD5eugETWDmII9HDmon9vdjCx68BI7MJXg764THGeLs+CD6i4GB kJ1MHubbpXX4PdKMQGBa8x0OJBVYOwK0hldJ3LTVv6NZ3XYnC78xGUVKrGDmBmqLXE+N 3BGvSFetgywYbOqcnP8pJ7U1+weuIFyqdGHnkrU1/8Gh65ecHCnI30pZbgWFTEjqowx3 CC1qAzrRsjEn7O3rLoopQJqsmPXV7F+TTBptuyMVhG13GnHxhaFYkHLMu2A5ACcn+FQl euYQ== 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 :content-language:content-transfer-encoding; bh=+J/Oc1375S3Mr5QmPzxTFCZZPHRpST6WJPtH7+jp6BE=; b=O6DIcMcgK1Gz1Gg+NtMImmrSykqKR1rkFUC8IL2SSJ/INCVrLJddt/EvOszpLUucHC RFvSa3eIqTCsb/iHViIAN+wYHiA2KdvS3TfNUQ4E0ZYS2a3nYpQV7XXD1/Uw2NTQeumn QpYs6YP2Z2UnOm9320ayCr/LRF7LKs7Z6YivhSRb5IlUNuXWvWMHsxWJfNhO4XBL19zw IHx3py8CNq/kYsT6M4ZrEiFLlqk3NDujLVGdL0ICQKFAyOehl1wxEvKzVpFmFeAHFFRr cmXsviNqtsjaZ+d+BGYju1AViIGQf/1UUjzGUzlIXE0V6xsPzc/6rqA7jhGm64uIjhh0 avHQ== X-Gm-Message-State: AOAM530EWz7mdC1a6XZ9ddpUzb3UyfOcdmW4mZtH3+HfS2KUVpvc4YT0 WXu0YFf6amSdtPmgQIjJupw= X-Received: by 2002:a65:4507:: with SMTP id n7mr21600039pgq.180.1597068635169; Mon, 10 Aug 2020 07:10:35 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id q17sm22310855pfh.32.2020.08.10.07.10.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 10 Aug 2020 07:10:34 -0700 (PDT) Subject: Re: [PATCH] Revert "seqlock: lockdep assert non-preemptibility on seqcount_t write" To: Greg KH , "Ahmed S. Darwish" Cc: bigeasy@linutronix.de, 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> 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: Mon, 10 Aug 2020 07:10:32 -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: <20200810100502.GA2406768@kroah.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/10/20 3:05 AM, Greg KH wrote: > On Mon, Aug 10, 2020 at 11:54:28AM +0200, Ahmed S. Darwish wrote: >> This reverts commit 859247d39fb008ea812e8f0c398a58a20c12899e. >> >> Current implementation of lockdep_assert_preemption_disabled() uses >> per-CPU variables, which was done to untangle the existing >> seqlock.h<=>sched.h 'current->' task_struct circular dependency. >> >> Using per-CPU variables did not fully untangle the dependency for >> various non-x86 architectures though, resulting in multiple broken >> builds. For the affected architectures, raw_smp_processor_id() led >> back to 'current->', thus having the original seqlock.h<=>sched.h >> dependency in full-effect. >> >> For now, revert adding lockdep_assert_preemption_disabled() to >> seqlock.h. >> >> Reported-by: Guenter Roeck >> Link: https://lkml.kernel.org/r/20200808232122.GA176509@roeck-us.net >> Link: https://lkml.kernel.org/r/20200810085954.GA1591892@kroah.com >> References: Commit a21ee6055c30 ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables") >> Signed-off-by: Ahmed S. Darwish > > Reviewed-by: Greg Kroah-Hartman > > Even after this, there are still some build errors on arm32, but I don't > think they are due to this change: > > ERROR: modpost: "__aeabi_uldivmod" [drivers/net/ethernet/sfc/sfc.ko] undefined! This affects every 32 bit architecture. > ERROR: modpost: "__bad_udelay" [drivers/net/ethernet/aquantia/atlantic/atlantic.ko] undefined! > I don't think that is new. If anything, it is surprising that builds don't fail more widely because of it. AFAICS it was introduced back in 2018 (a hot 50-ms delay loop really isn't such a good idea). Guenter