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=-8.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 CC87EC4338F for ; Mon, 9 Aug 2021 12:52:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF94460EDF for ; Mon, 9 Aug 2021 12:52:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234163AbhHIMxP (ORCPT ); Mon, 9 Aug 2021 08:53:15 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:30630 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233806AbhHIMxM (ORCPT ); Mon, 9 Aug 2021 08:53:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1628513572; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Y9n7ilQ/jZQShw/lv6UZt5QMdO7+QAD+IE5YP5J7ceE=; b=BhernUFGFNZKQ42JryJKo/baHDxJAF9PQa8yuh+ElL5q99p8vtB7VVSH12aRKR/xXcbQ5l h+GCUyuBZK7jAmeIUiFL+uxN0XmAgKkBF+COmfN3nENH/mISRvYYT1ElQpsj5lC0NPFMQa QXlOXUF2Ymyokk9Zr2MA0c3WjG4gNYk= Received: from mail-qv1-f71.google.com (mail-qv1-f71.google.com [209.85.219.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-223-4HuzDPvXMAyFzsMuExSgTg-1; Mon, 09 Aug 2021 08:52:50 -0400 X-MC-Unique: 4HuzDPvXMAyFzsMuExSgTg-1 Received: by mail-qv1-f71.google.com with SMTP id v19-20020ad455530000b029032620cab853so12218938qvy.8 for ; Mon, 09 Aug 2021 05:52:50 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:subject:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=Y9n7ilQ/jZQShw/lv6UZt5QMdO7+QAD+IE5YP5J7ceE=; b=IrIGnUHcrFdl7k5DebotO5d5nTJRW3ER3grK62qa2ixnuEfaL0itV1+xsd+Q4g0OA+ gFNDH2q7kJpeeaOf0LoDusF1Jie1W08hkHBwfQXL3nVr4SX4nAkU/uqCQoPA2yjduwNE FwY7cLJQsJtmcjzRrCWcikI5YkUjfOB3BTkyv6xNknTdlrjS/m+OE1iYCAtXECzP5JO2 uyWrXer90ZXpxXIzHCWxc+RILPwhEdRYLADO6gNIFFkqo45vBdg9MPrp59fq+OpayP/k vJrSxZyiprXm6XN+314A9YFuK7zq84xSg4AkMz59RjfldtVRpm5fYQeVOB211z+ATWqD YKOA== X-Gm-Message-State: AOAM530Jm3ISfN65Xm7qS2j9wUb8uIpikZ4QsnoOjd5bpUWJz2kMKcDJ /4VgpoSRrrwzA9eWLF8gEdsfDkknmUr7b20bAOMDfN3pAtJC9envfYhL+ljlwdGxt0zggURxewi Bgw2+vSulP9bHZJgZEiZUUSsX X-Received: by 2002:ad4:4972:: with SMTP id p18mr23280408qvy.26.1628513570423; Mon, 09 Aug 2021 05:52:50 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxSTxvOKVdldJV8XjyLO3Qkmc93SmmUfXz6tQOHAE06DB4NzXZqyjTHk25Oql1BTGJFV+7NYA== X-Received: by 2002:ad4:4972:: with SMTP id p18mr23280394qvy.26.1628513570267; Mon, 09 Aug 2021 05:52:50 -0700 (PDT) Received: from llong.remote.csb ([2601:191:8500:76c0::cdbc]) by smtp.gmail.com with ESMTPSA id p187sm8946260qkd.101.2021.08.09.05.52.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 09 Aug 2021 05:52:49 -0700 (PDT) From: Waiman Long X-Google-Original-From: Waiman Long Subject: Re: [PATCH] semaphore: Add might_sleep() to down_*() family To: Xiaoming Ni , Waiman Long , linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@redhat.com, will@kernel.org, boqun.feng@gmail.com Cc: wangle6@huawei.com, xiaoqian9@huawei.com, shaolexi@huawei.com References: <20210809021215.19991-1-nixiaoming@huawei.com> <48cddad4-0388-ae8b-f98b-1629b9ae590a@redhat.com> <1a5b0f50-b071-2d1c-5277-b6d7f652c257@huawei.com> Message-ID: <65fe396a-b10d-2388-8229-05fd43d58927@redhat.com> Date: Mon, 9 Aug 2021 08:52:48 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <1a5b0f50-b071-2d1c-5277-b6d7f652c257@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/8/21 11:51 PM, Xiaoming Ni wrote: > On 2021/8/9 11:01, Waiman Long wrote: >> >> I think it is simpler to just put a "might_sleep()" in >> __down_common() which is the function where sleep can actually happen. >> > > If the actual atomic context hibernation occurs, the corresponding > alarm log is generated in __schedule_bug(). >     __schedule() >         --> schedule_debug() >             --> __schedule_bug() > > However, "might_sleep()" indicates the possibility of sleep, so that > code writers can identify and fix the problem as soon as possible, but > does not trigger atomic context sleep. > > Is it better to put "might_sleep()" in each down API entry than > __down_common() to help identify potential code problems? Putting "might_sleep()" in each down_*() functions mean that whenever we add a new API function, we have to remember to add "might_sleep()". If we put it in down_common(), it will work for any newly added API function in the future even though I doubt we will add any. Cheers, Longman