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=-6.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,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 90C96C433E7 for ; Thu, 15 Oct 2020 18:39:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 218C8212CC for ; Thu, 15 Oct 2020 18:39:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="JeKQa4xU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733078AbgJOSje (ORCPT ); Thu, 15 Oct 2020 14:39:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39622 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731154AbgJOSje (ORCPT ); Thu, 15 Oct 2020 14:39:34 -0400 Received: from mail-il1-x143.google.com (mail-il1-x143.google.com [IPv6:2607:f8b0:4864:20::143]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2FE9BC061755 for ; Thu, 15 Oct 2020 11:39:33 -0700 (PDT) Received: by mail-il1-x143.google.com with SMTP id l16so5573982ilt.13 for ; Thu, 15 Oct 2020 11:39:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=2eYPjnhMkoKRh274ZnfDYxEkN/cASuQVhfeqtpp/wFo=; b=JeKQa4xUyeVsPYFmaCn7c933kxLOMPieHLwq4xeMoEO/okGMXehToHvd+0ig7XaIgP fHneyQ60wBUcEpxPUpTELURgj5bQIelk0vJP0TgRDXW95Vd8u5nZkWrMtNgvymK2D3DB 7wfN4oY2FqabCqGYCmGCUeKOhtK4TzCIlswIXurPRrYIKYwZH7CYwdNoMmCoICJcSgsf /meK+N6OQ4aCTmXZRGkygQvKXvUTKx8lVeno6q4vHbW7SAbYuof8VFNhuZloauqDFQWX WhveX7ppMApDxhOhALQer1AszJqIBPle/oM35KL+bH/UNuLDQ1qiwNLLPRkowndfDMnt 9vPQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=2eYPjnhMkoKRh274ZnfDYxEkN/cASuQVhfeqtpp/wFo=; b=f8xAfNhg0/eWFd+IHrs8X4jCOJSeNctcbsfi5RnPmat5Bh9ai0VP4gMu4r86t7f6Iy f3epdFIA1F23A4uF8IZ+GSzof43/kjY29hbH4ieHOJDDjrWQiIl+jvNv1DDqWHQuoYZp ruOFjITksvzYNEnPQzcymtY1HT7j/t56uo2D2dFgFSjSs6cTbeI22QFey2VgFzze+AcN ZWozYW3dslGxaJBIWUgIdq+NbhePEkeCkEBjUgGegR1X3QIUckUOT9PrqUT8zOgOlGaj NKdYGS+vObxEI7lBQ42tS0TUEq1AcnDIO8yMoZ2YR/DhMm9tMavorH4POQzWEtHnuPhR 1ULg== X-Gm-Message-State: AOAM532yphsQBmqmpfJaxPeI4iWpD1+vq3K2jx0BY1L44JWr0LY1Ybqc rWv6qM4oZgRGPTrNYuSTH+inZA== X-Google-Smtp-Source: ABdhPJybMiCJjWUTEv4UBJhuJh14Xu+AxKMOZureDclwvHKWgahxfC7F1dxi9KPo+YQpk2Hu4SMh7A== X-Received: by 2002:a92:cd42:: with SMTP id v2mr3868619ilq.65.1602787172427; Thu, 15 Oct 2020 11:39:32 -0700 (PDT) Received: from [192.168.1.30] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id o17sm3391972ila.47.2020.10.15.11.39.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 15 Oct 2020 11:39:31 -0700 (PDT) Subject: Re: [PATCH 5/5] task_work: use TIF_NOTIFY_SIGNAL if available To: Oleg Nesterov Cc: linux-kernel@vger.kernel.org, io-uring@vger.kernel.org, peterz@infradead.org, tglx@linutronix.de, Roman Gershman References: <20201015131701.511523-1-axboe@kernel.dk> <20201015131701.511523-6-axboe@kernel.dk> <20201015154953.GM24156@redhat.com> From: Jens Axboe Message-ID: Date: Thu, 15 Oct 2020 12:39:31 -0600 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: <20201015154953.GM24156@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 10/15/20 9:49 AM, Oleg Nesterov wrote: > On 10/15, Jens Axboe wrote: >> >> Reviewed-by: Oleg Nesterov > > Yes, but ... > >> +static void task_work_notify_signal(struct task_struct *task) >> +{ >> +#if defined(CONFIG_GENERIC_ENTRY) && defined(TIF_NOTIFY_SIGNAL) > > as long as defined(CONFIG_GENERIC_ENTRY) goes away ;) > > Thomas, I strongly, strongly disagree with you. But even if you are right > and only CONFIG_GENERIC_ENTRY arches should use TIF_NOTIFY_SIGNAL, why should > this series check CONFIG_GENERIC_ENTRY ? > > You can simply nack the patch which adds TIF_NOTIFY_SIGNAL to > arch/xxx/include/asm/thread_info.h. This seems to be the biggest area of contention right now. Just to summarize, we have two options: 1) We leave the CONFIG_GENERIC_ENTRY requirement, which means that the rest of the cleanups otherwise enabled by this series will not be able to move forward until the very last arch is converted to the generic entry code. 2) We go back to NOT having the CONFIG_GENERIC_ENTRY requirement, and archs can easily opt-in to TIF_NOTIFY_SIGNAL independently of switching to the generic entry code. I understand Thomas's reasoning in wanting to push archs towards the generic entry code, and I fully support that. However, it does seem like the road paved by #1 is long and potentially neverending, which would leave us with never being able to kill the various bits of code that we otherwise would be able to. Thomas, I do agree with Oleg on this one, I think we can make quicker progress on cleanups with option #2. This isn't really going to hinder any arch conversion to the generic entry code, as arch patches would be funeled through the arch trees anyway. Thomas? -- Jens Axboe