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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 28D11C1B0F2 for ; Wed, 20 Jun 2018 10:52:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D563220871 for ; Wed, 20 Jun 2018 10:52:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="FRLGhVBB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D563220871 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.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 S1752924AbeFTKwM (ORCPT ); Wed, 20 Jun 2018 06:52:12 -0400 Received: from mail-pl0-f68.google.com ([209.85.160.68]:38709 "EHLO mail-pl0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750793AbeFTKwL (ORCPT ); Wed, 20 Jun 2018 06:52:11 -0400 Received: by mail-pl0-f68.google.com with SMTP id d10-v6so1565759plo.5 for ; Wed, 20 Jun 2018 03:52:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=l569RuhWYVP20wPDF9XmbADynhofXNMx1ZIxGdE2ai0=; b=FRLGhVBB6+MsZUvkIK2cQ5LHglMe4SfK5t9Yjhl7ism1b/TbixenvCQkeyx5hLxUyY cuSnGBnfe6Y9Ev27XiZS0izOa6wnjKjMDplD3Xf1ZWyH18XdfnD1JInj3DLpfKFR+vVG XIo8qCJinzWQnqSB6yKMf1T9m3CfVoFBHxhQ5wS21YsUl0i6npRb7/OVwiyAzX4ReuU2 kbgMH5z7HF20OvY8quGtoQspb1LkEnwzcBYQnKdCbbFwGX1CK8NIeTY/HKd3u1x0zc6G x3COj4I9sGcK6PnftGI5NkVt3IJnY2B6Fdtm8zBGtj8eSBK+/pSbDT2h63xxaxxtrmf3 wIlA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=l569RuhWYVP20wPDF9XmbADynhofXNMx1ZIxGdE2ai0=; b=CdpcnLk9FjRvV6D0x2pPRKVette03g9nVQsDbHHIAJytiF005b0sIgyLDhiZtIttY3 ivDqlHSJe55YtnNt0WceZ/UVr+xUU/2TVUCu7x6RrtJJMHW2sCAnW3GSSoqBJyWU6wBw syWufSoJNY3yPBJ6m22B84UUpvv2BPloud1DWY+PVKhQKWnr3wWKrvhf7+3e6ATP65fU MIHzJJDmmzrzIz0jjJ8lcLt+3PKQ9DD2d5ApH4DHOuL/Hd7lIq/T11UQ2iQbxMuqeTEo usbFEmk4nz0u0622MtrPq1KpP2dM3l1rPF6CRw8jEVy3TCtab49QOhtgbP+ZEthSs9+j JBFw== X-Gm-Message-State: APt69E2Lt5YPklkAtaUMUZ3j+ALAVxHyKoxfkerMaaz50sxDDec4XvW0 qmJBw143Mk9+Gfs49CGA1sU= X-Google-Smtp-Source: ADUXVKLCA+1a8r1TydzuoUKnLtQMyDnspVlVjAsDWwV96BTsCtEZOpuY+eXGABz0ZcdnVqhBLktzIQ== X-Received: by 2002:a17:902:8685:: with SMTP id g5-v6mr23100470plo.180.1529491930959; Wed, 20 Jun 2018 03:52:10 -0700 (PDT) Received: from localhost ([110.70.59.159]) by smtp.gmail.com with ESMTPSA id h78-v6sm4565055pfh.141.2018.06.20.03.52.08 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 20 Jun 2018 03:52:09 -0700 (PDT) Date: Wed, 20 Jun 2018 19:52:06 +0900 From: Sergey Senozhatsky To: Steven Rostedt Cc: Sergey Senozhatsky , Petr Mladek , Maninder Singh , sergey.senozhatsky@gmail.com, 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: <20180620105206.GC444@jagdpanzerIV> References: <20180601090029epcas5p3cc93d4bfbebb3199f0a2684058da7e26~z-a_jkmrI2993329933epcas5p3q@epcas5p3.samsung.com> <20180618061550.GA27996@jagdpanzerIV> <20180618062306.GA29683@jagdpanzerIV> <20180619093244.ehj34uhpnpv6447f@pathway.suse.cz> <20180619094953.GB2631@jagdpanzerIV> <20180619092629.55146df7@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180619092629.55146df7@gandalf.local.home> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (06/19/18 09:26), Steven Rostedt wrote: > > > > 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]. > > > It's not that critical to have that change take immediate effect. It's > not a common operation, and I doubt anyone (but perhaps you ;-) will > even notice any difference. Quite possibly. In the background (what I didn't post) I thought that console_verbose() sets ignore_loglevel. So we could have a race condition - when console drags behind, something sets ignore_loglevel but it takes a while before "all" messages actually start to appear on the console. In the foreground (what I posted) I thought that the whole reason the patch exists was "In SMP printk can work asynchronously, logs can be missed on console because it checks current log level at time of console_unlock, not at time of storing logs" So console_sem may be scheduled out, or simply slow. Once again, it may take some time for ignore_loglevel to take any effect. But probably it's fine to have this new behaviour. -ss