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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, 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 A206AC3524E for ; Wed, 19 Feb 2020 21:33:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 776C724656 for ; Wed, 19 Feb 2020 21:33:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=broadcom.com header.i=@broadcom.com header.b="cYcZaClt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727874AbgBSVdd (ORCPT ); Wed, 19 Feb 2020 16:33:33 -0500 Received: from mail-wr1-f68.google.com ([209.85.221.68]:46153 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727775AbgBSVdb (ORCPT ); Wed, 19 Feb 2020 16:33:31 -0500 Received: by mail-wr1-f68.google.com with SMTP id z7so2227883wrl.13 for ; Wed, 19 Feb 2020 13:33:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=yDc3+2LTXdeT4DFS6yiHXemjisG4SKrPsn7wcWKNyc0=; b=cYcZaCltkuSpbD/WoHJZ+CIv9gG+julOvJ1jka7rOBCY5GMl9cks8jtPmd4v6WArov 1mHzdIUClTgGLHl2fqzIiUqoBc8skRZLZ8VCXOzUhSxYUtPRmmsLAY/U0BJ56qUcmUmH RCcTREkweJYOkTucwK/nzuiNGNow0+L6tS9qQ= 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=yDc3+2LTXdeT4DFS6yiHXemjisG4SKrPsn7wcWKNyc0=; b=XtXszZBJMzxkq0BKPcHsqvZBMwROCTr2Yk10lDwG2/qslQNJUs33LX4LCfDvus9U7b grVKJzGxyRTNmT6+E5xt2ApmP903n0Ez+McCW0BnjYK1AxDcqow7UM5nSyksTEzrPBR2 DeXkvQGIq8SFg44018Kz4f/scXEFhTMg6t5kyzOHW7QGsYJ3UnyK40k/lrYr4+zdtl+4 TNT7c0ivt6E2IN5Z8dBCoOqmu6vaW1cYnhZYYdo+edT1Z8zU6U/un/f8c9CdSXA5wHL/ HnDxH3Wh9g5AkREEANtUscL4GcMUvYwfEAUVOusVsR0W0ZbEQ7FzrHeVl4ptlFpXEglR QQNg== X-Gm-Message-State: APjAAAUOYK0dGKjM5Fpiy2z7ny7+f8tp5971wnxESYN2rtMyztbx7ER4 3EGAgU+RHeE3d7nv2IdcMmQwjg== X-Google-Smtp-Source: APXvYqxO0pamPxMf/8ILBFlAvOSGJ6ULjaU2B+PG28ryNIhHvKKg9F63tlUJbqWykPnAHbIThnz+8g== X-Received: by 2002:adf:90e1:: with SMTP id i88mr39007634wri.95.1582148009688; Wed, 19 Feb 2020 13:33:29 -0800 (PST) Received: from [192.168.178.129] (f140230.upc-f.chello.nl. [80.56.140.230]) by smtp.gmail.com with ESMTPSA id h13sm1626791wrw.54.2020.02.19.13.33.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 19 Feb 2020 13:33:29 -0800 (PST) Subject: Re: [PATCH] cfg80211: Pass lockdep expression to RCU lists To: Johannes Berg , Amol Grover , "David S . Miller" , Jakub Kicinski Cc: linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, Joel Fernandes , Madhuparna Bhowmik , "Paul E . McKenney" References: <20200219091102.10709-1-frextrite@gmail.com> <407d6295-6990-4ef6-7d36-e08a942607c8@broadcom.com> <855dec1f598d8b43400089cd0c5a7ac9b3533fc7.camel@sipsolutions.net> From: Arend Van Spriel Message-ID: <795b0dd6-23e7-8780-7cde-cf309f08109f@broadcom.com> Date: Wed, 19 Feb 2020 22:33:29 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <855dec1f598d8b43400089cd0c5a7ac9b3533fc7.camel@sipsolutions.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/19/2020 10:29 PM, Johannes Berg wrote: > On Wed, 2020-02-19 at 22:27 +0100, Arend Van Spriel wrote: >> On 2/19/2020 10:13 AM, Johannes Berg wrote: >>> On Wed, 2020-02-19 at 14:41 +0530, Amol Grover wrote: >>>> >>>> - WARN_ON_ONCE(!rcu_read_lock_held() && !lockdep_rtnl_is_held()); >>>> - >>>> - list_for_each_entry_rcu(pos, &rdev->sched_scan_req_list, list) { >>>> + list_for_each_entry_rcu(pos, &rdev->sched_scan_req_list, list, >>>> + lockdep_rtnl_is_held()) { >>> >>> Huh, I didn't even know you _could_ do that :) >> >> Me neither ;-). Above you are removing the WARN_ON_ONCE() entirely. >> Would it not be good to keep the WARN_ON_ONCE() with only the >> !rcu_read_lock_held() check. > > Not needed, the macro expansion will already contain > rcu_read_lock_any_held() just like in all the other cases where you pass > a lockdep condition to RCU helpers. Ah, yes. I see it in __list_check_rcu(). Thanks, Arend