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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 743A1C5CFC1 for ; Tue, 19 Jun 2018 10:52:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B40C2083D for ; Tue, 19 Jun 2018 10:52:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3B40C2083D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937635AbeFSKwT (ORCPT ); Tue, 19 Jun 2018 06:52:19 -0400 Received: from mx2.suse.de ([195.135.220.15]:55130 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936108AbeFSKwQ (ORCPT ); Tue, 19 Jun 2018 06:52:16 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext-too.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 997ECAC84; Tue, 19 Jun 2018 10:52:14 +0000 (UTC) Date: Tue, 19 Jun 2018 12:52:13 +0200 From: Petr Mladek To: Sergey Senozhatsky Cc: Maninder Singh , sergey.senozhatsky@gmail.com, rostedt@goodmis.org, linux-kernel@vger.kernel.org, a.sahrawat@samsung.com, pankaj.m@samsung.com, v.narang@samsung.com Subject: Re: [PATCH v2] printk: make sure to print log on console. Message-ID: <20180619105213.uzf6ba3oo3475icz@pathway.suse.cz> References: <20180601090029epcas5p3cc93d4bfbebb3199f0a2684058da7e26~z-a_jkmrI2993329933epcas5p3q@epcas5p3.samsung.com> <20180618061550.GA27996@jagdpanzerIV> <20180618062306.GA29683@jagdpanzerIV> <20180619093244.ehj34uhpnpv6447f@pathway.suse.cz> <20180619094953.GB2631@jagdpanzerIV> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180619094953.GB2631@jagdpanzerIV> User-Agent: NeoMutt/20170421 (1.8.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 2018-06-19 18:49:53, Sergey Senozhatsky wrote: > On (06/19/18 11:32), Petr Mladek wrote: > > > - if (suppress_message_printing(msg->level)) { > > > + if (!ignore_loglevel && (msg->flags & LOG_NOCONS)) { > > > > > > > > > `ignore_loglevel' is a module param and can change any time via > > > /sys/module/printk/parameters/ignore_loglevel > > > we need to respect its value. > > > > I would prefer to keep the patch as is. I see it the following way. > > > > Also console_loglevel can be changed anytime by /proc/sys/kernel/printk. > > The patch basically moves the decision about the message visibility from > > console_unlock() to vprintk_emit(). The logic is easier when all > > aspects are handled in a single location and only once. > > But when I set /sys/module/printk/parameters/ignore_loglevel I naturally > expect it to take an immediate action. Without waiting for the consoles > to catch up and to discard N messages [if the consoles were behind the > logbuf head]. Yeah, I understand this view. I thought about it as well. But did you ever needed this behavior in the real life? I personally changed ignore_loglevel only before I wanted to reproduce a bug. Then it would be perfectly fine to handle it only in vprintk_emit(). In fact, it would be even better because it would affect only messages that happened after I triggered the bug. Anyway, changing ignore_loglevel during a printk flood has undefined behavior by definition. If you do this manually, it would depend on the speed of the console, your typing capabilities, possibility to login as administrator, load of the system, ... If you do this by a script, you would probably do it in advance. I do not see this a reason for a more complicated and even schizophrenic logic. Best Regards, Petr