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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1F06C3DA7A for ; Fri, 6 Jan 2023 11:11:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232452AbjAFLLS (ORCPT ); Fri, 6 Jan 2023 06:11:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54282 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229580AbjAFLLO (ORCPT ); Fri, 6 Jan 2023 06:11:14 -0500 Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2001:67c:2178:6::1d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E9FE86C2A5 for ; Fri, 6 Jan 2023 03:11:12 -0800 (PST) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 615B824A78; Fri, 6 Jan 2023 11:11:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1673003471; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=eul2FPd2zLCNMUGfxO9nD9ZKEURRkihsAs1254cmjkY=; b=mKmDPD9bXvP3lLFudhIWnZixzxwIadXE0XiAYvL0sL7/wrP5RGao1f8mM3QyTdNWLsRe8/ LTecTDChPXq6T8tSgbmswqpBA5LZz3l6385KR4NqR8hKw2JStO+a10kN9wI99wvvWwnWxP 3SB/9mXaCpmdpsMDhYb0yj3mwag6tpU= Received: from suse.cz (unknown [10.100.208.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 17DC52C143; Fri, 6 Jan 2023 11:11:11 +0000 (UTC) Date: Fri, 6 Jan 2023 12:11:08 +0100 From: Petr Mladek To: John Ogness Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: [PATCH printk v4 8/8] printk: adjust string limit macros Message-ID: References: <20230105103735.880956-1-john.ogness@linutronix.de> <20230105103735.880956-9-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230105103735.880956-9-john.ogness@linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 2023-01-05 11:43:35, John Ogness wrote: > The various internal size limit macros have names and/or values that > do not fit well to their current usage. > > Rename the macros so that their purpose is clear and, if needed, > provide a more appropriate value. In general, the new macros and > values will lead to less memory usage. The new macros are... > > PRINTK_MESSAGE_MAX: > > This is the maximum size for a formatted message on a console, > devkmsg, or syslog. It does not matter which format the message has > (normal or extended). It replaces the use of CONSOLE_EXT_LOG_MAX for > console and devkmsg. It replaces the use of CONSOLE_LOG_MAX for > syslog. > > Historically, normal messages have been allowed to print up to 1kB, > whereas extended messages have been allowed to print up to 8kB. > However, the difference in lengths of these message types is not > significant and in multi-line records, normal messages are probably > larger. Also, because 1kB is only slightly above the allowed record > size, multi-line normal messages could be easily truncated during > formatting. > > This new macro should be significantly larger than the allowed > record size to allow sufficient space for extended or multi-line > prefix text. A value of 2kB should be plenty of space. For normal > messages this represents a doubling of the historically allowed > amount. For extended messages it reduces the excessive 8kB size, > thus reducing memory usage needed for message formatting. > > PRINTK_PREFIX_MAX: > > This is the maximum size allowed for a record prefix (used by > console and syslog). It replaces PREFIX_MAX. The value is left > unchanged. > > PRINTKRB_RECORD_MAX: > > This is the maximum size allowed to be reserved for a record in the > ringbuffer. It is used by all readers and writers with the printk > ringbuffer. It replaces LOG_LINE_MAX. > > Previously this was set to "1kB - PREFIX_MAX", which makes some > sense if 1kB is the limit for normal message output and prefixes are > enabled. However, with the allowance of larger output and the > existence of multi-line records, the value is rather bizarre. > > Round the value up to 1kB. > > Signed-off-by: John Ogness I like this. Reviewed-by: Petr Mladek Best Regards, Petr