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=-2.2 required=3.0 tests=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 1CA5BC54FCB for ; Fri, 24 Apr 2020 16:10:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 032292075A for ; Fri, 24 Apr 2020 16:10:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728082AbgDXQK6 (ORCPT ); Fri, 24 Apr 2020 12:10:58 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:58074 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726920AbgDXQK5 (ORCPT ); Fri, 24 Apr 2020 12:10:57 -0400 Received: from fsav302.sakura.ne.jp (fsav302.sakura.ne.jp [153.120.85.133]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 03OGAIaW043241; Sat, 25 Apr 2020 01:10:18 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav302.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav302.sakura.ne.jp); Sat, 25 Apr 2020 01:10:18 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav302.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 03OGAIJf043237 (version=TLSv1.2 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sat, 25 Apr 2020 01:10:18 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [PATCH] printk: Add loglevel for "do not print to consoles". To: Steven Rostedt Cc: Petr Mladek , Sergey Senozhatsky , linux-kernel@vger.kernel.org, Dmitry Safonov , Michal Hocko , Yafang Shao References: <20200424024239.63607-1-penguin-kernel@I-love.SAKURA.ne.jp> <20200424092816.62a61b1d@gandalf.local.home> <579fbe97-9aae-2b67-03ff-01291b9cbb7d@i-love.sakura.ne.jp> <20200424103131.7987f890@gandalf.local.home> <7ec0b0a3-39ae-0f1c-b8c2-e1e9e60f1223@i-love.sakura.ne.jp> <20200424114225.5a3bab7e@gandalf.local.home> From: Tetsuo Handa Message-ID: Date: Sat, 25 Apr 2020 01:10:15 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200424114225.5a3bab7e@gandalf.local.home> Content-Type: text/plain; charset=utf-8 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 2020/04/25 0:42, Steven Rostedt wrote: > You can also use the tracing ring buffer for this, as it has been safe in > all these contexts for a very long time. And that ring buffer is something > that you can use outside of tracing (oprofile uses it). Some messages are read from printk() source and other messages are read from non-printk() source will loose ordering of messages (i.e. non-understandable log files). For those who analyze log files, multiple sources are not acceptable. > And both shouldn't be done within the kernel. The "CONSOLE_LOGLEVEL_SILENT" > if for user decided policy, not the kernel making that policy for the user. KERN_NO_CONSOLES is a mechanism for implementing user decided policy. As long as userspace can control whether to use KERN_NO_CONSOLES (e.g. sysctl), there should be no problem with adding KERN_NO_CONSOLES (i.e. this patch) to the kernel side.