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 C249CC54FCB for ; Fri, 24 Apr 2020 15:52:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 764BA2063A for ; Fri, 24 Apr 2020 15:52:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=arista.com header.i=@arista.com header.b="bzXgut1D" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728375AbgDXPwg (ORCPT ); Fri, 24 Apr 2020 11:52:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726301AbgDXPwg (ORCPT ); Fri, 24 Apr 2020 11:52:36 -0400 Received: from mail-wm1-x344.google.com (mail-wm1-x344.google.com [IPv6:2a00:1450:4864:20::344]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52E0EC09B046 for ; Fri, 24 Apr 2020 08:52:35 -0700 (PDT) Received: by mail-wm1-x344.google.com with SMTP id r26so11390553wmh.0 for ; Fri, 24 Apr 2020 08:52:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=googlenew; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=rtV64CdoXvodJnTwhQjpfJxxVe45YkDM4hkifaxGTP4=; b=bzXgut1D3RMLHq+6TOlFXEGKdoDJSQqqm0o8pV8jytLUrH58+0aLEm94VnDZ7AkrUk xNDfM0s8GOdUZw/OiJd+QDrUdBKATW8a1cdNYICSDa27AkURhZBYfJkGBYD2Xt4HIIcR e0V8tiumDDlPrTTe6Sz7iNk3kHEFW86jligXyvzUBSMc5/kdMKtoyCz4uA3IPASpNBBl jSuh4dsVYyUcdX92swDnfzTzkZ/QCt+sfkR3dBD/tvueKKon+0jVM0vSyMN+EBLKVvxF NFHcN2o45xlcYBTCwy6HyUD6CI1b8Jc6Umj/aeRzqjr3tx0ZX6qgpLI0sBHAQwMihfD4 QyNA== 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=rtV64CdoXvodJnTwhQjpfJxxVe45YkDM4hkifaxGTP4=; b=T2PI+bcMTVsidl4BtvxLqqvmJN+lsgJUBoQh/lXN38MA9/SdHMmKyEZ1uiGLkAlsXh wGMus873dB4FB5g/LhtlBKDQ/TxywTlTwFtNTRifESJS2IVH4iGjnh3nN5OFZMO9Iy3x ayrpA18Wq0hOsAtaC0gujyJSMBJMPCR/yiHlMFU01SQ02R+vyh8q4MyYqi6RG3EJm8Xi N0Zpoz7+teGgkHOfakEaTdu/dSs6VwauKsnd17ifgqe2VRy4r0JNKPEJYLdJVHHbByCq Q3+Z08eVQqJj4a6KD8OPBM0CDAewTS4u0PUB87Pxhs3Pw9m5feSSi9mABI7RXO37UU3I luzQ== X-Gm-Message-State: AGi0PuYuHVXqZXjn9F5zUydeikYrN4TuDiOwZymFXfvwrLI8lNoCw0Mx vARVtcOu4LaE+R619LWP+H7W5w== X-Google-Smtp-Source: APiQypLHoMtXgNvUu4rSXl4sbf4gXGV+tWNxmLDcuR0fz6lAjF9ERRKa1+QHe3UHlNpGkUzFVpTL3w== X-Received: by 2002:a1c:e408:: with SMTP id b8mr11014823wmh.68.1587743553991; Fri, 24 Apr 2020 08:52:33 -0700 (PDT) Received: from ?IPv6:2a02:8084:e84:2480:228:f8ff:fe6f:83a8? ([2a02:8084:e84:2480:228:f8ff:fe6f:83a8]) by smtp.gmail.com with ESMTPSA id q143sm3661290wme.31.2020.04.24.08.52.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 24 Apr 2020 08:52:33 -0700 (PDT) Subject: Re: [PATCH] printk: Add loglevel for "do not print to consoles". To: Steven Rostedt , Tetsuo Handa Cc: Petr Mladek , Sergey Senozhatsky , linux-kernel@vger.kernel.org, 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: Dmitry Safonov Message-ID: Date: Fri, 24 Apr 2020 16:52:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 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 4/24/20 4:42 PM, Steven Rostedt wrote: > On Sat, 25 Apr 2020 00:28:53 +0900 > Tetsuo Handa wrote: >> For those who analyze log files (instead of console output), the point of >> printk() is to save kernel messages into log files (via userspace syslog >> daemon). >> >> By the way, I think >> >> printk(KERN_NO_CONSOLES "hello\n") >> >> is almost same with doing >> >> saved_loglevel = console_loglevel; >> console_loglevel = CONSOLE_LOGLEVEL_SILENT; >> printk("hello\n"); >> console_loglevel = saved_loglevel; >> >> used by vkdb_printf(). > > 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. Though, I believe the reverse KERN_UNSUPPRESSED [1] still makes sense for sysrq/kdb where user expects their interactive messages to appear on console. And unfortunately, userspace depends on the loglevel of those messages as it is. With KERN_UNSUPPRESSED I hope to remove all those console_loglevel tricks and make it static variable for printk. [1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/ Thanks, Dmitry