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 8D050C19F28 for ; Wed, 27 Jul 2022 01:21:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240123AbiG0BVu (ORCPT ); Tue, 26 Jul 2022 21:21:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229906AbiG0BVt (ORCPT ); Tue, 26 Jul 2022 21:21:49 -0400 Received: from box.fidei.email (box.fidei.email [71.19.144.250]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BA40933E06 for ; Tue, 26 Jul 2022 18:21:48 -0700 (PDT) Received: from authenticated-user (box.fidei.email [71.19.144.250]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits)) (No client certificate requested) by box.fidei.email (Postfix) with ESMTPSA id A72848078B; Tue, 26 Jul 2022 21:21:47 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=dorminy.me; s=mail; t=1658884908; bh=zpERFVraOY7oepf0OcR/CGz0VVdNyPa7aWGZPCdnywI=; h=Date:Subject:To:References:From:In-Reply-To:From; b=KF8LBuBo7qo093RE5mlXOeTY+v10r0XnuTn/5hLzewU7vBt9ADu3l/Wcd9YR26opq Q70S7xh5/4UBcTWO41WfyzK3u37d6zdSZffF/EnmJMyGynLG+1dXqN0orGtpDudbRC u+3GWdDIITtgSAh7VzB3Y2P/nP4KNK7d3tFkCDdd4JZ6xD9KnU4JUhrbaL743eUi28 LZ4OWam33rBhHtg1zvHYCtgsTXA29fZ5mCou+PcQMLVNsYO7kaufbOh3yLnX7tg9AG Cbjaqi0iteFzEyxRa3feVL2Qs4gmgXgawtZ6zNpu1i/Cu8byDSaK4dAhibgK2itlYu IleErEQzZrPrg== Message-ID: Date: Tue, 26 Jul 2022 21:21:45 -0400 MIME-Version: 1.0 Subject: Re: [PATCH v2 2/4] btrfs: make __btrfs_dump_space_info() output better formatted Content-Language: en-US To: Boris Burkov , dsterba@suse.cz, Qu Wenruo , Qu Wenruo , linux-btrfs@vger.kernel.org, Johannes Thumshirn References: <20220719213804.GT13489@twin.jikos.cz> <3cfc9569-ff22-c04d-f7d0-fea1396ba4b5@gmx.com> <20220726181353.GJ13489@twin.jikos.cz> <20220726213928.GP13489@twin.jikos.cz> From: Sweet Tea Dorminy In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 7/26/22 19:21, Boris Burkov wrote: > On Tue, Jul 26, 2022 at 11:39:28PM +0200, David Sterba wrote: >> On Tue, Jul 26, 2022 at 01:53:33PM -0700, Boris Burkov wrote: >>>> Yes we shold care about readability but kernel printk output lines can >>>> be interleaved, single line is much easier to grep for and all the >>>> values are from one event. The format where it's a series of "key=value" >>>> is common and I think we're used to it from tracepoints too. There are >>>> lines that do not put "=" between keys and values we could unify that >>>> eventually. >>> >>> Agreed that a long line is OK, and preferable to full on splitting. >>> >>> What about making some btrfs printing macros that use KERN_CONT? I think >>> that would do what Qu wants without splitting the lines or being bad for >>> ratelimiting. >> >> IIRC I've read some discussions about KERN_CONT suggesting not to use >> it, I'll ask what's the status. > > I just saw a comment at its definition that reads: > > /* > * Annotation for a "continued" line of log printout (only done after a > * line that had no enclosing \n). Only to be used by core/arch code > * during early bootup (a continued line is not SMP-safe otherwise). > */ > #define KERN_CONT KERN_SOH "c" > > So that's not an encouraging sign. OTOH, I found some code in > ext4/super.c that prints its errors with KERN_CONT here: > 'ext4: super.c: Update logging style using KERN_CONT Some other log message from somewhere else could be emitted to the printk ringbuffer between the original and the continued message. In such a case, the continued message instead gets treated as its own message of loglevel default. (kernel/printk/printk.c:2173ish) Using KERN_CONT seems like it has a lot of potential for confusion, especially if the default message level has been changed to be different from the original messages' level.