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=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 296DDC433E2 for ; Sun, 19 Jul 2020 03:43:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0869B207DD for ; Sun, 19 Jul 2020 03:43:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="hb/74Vi3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726620AbgGSDnQ (ORCPT ); Sat, 18 Jul 2020 23:43:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47258 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726359AbgGSDnP (ORCPT ); Sat, 18 Jul 2020 23:43:15 -0400 Received: from mail-pj1-x1042.google.com (mail-pj1-x1042.google.com [IPv6:2607:f8b0:4864:20::1042]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E90BBC0619D2 for ; Sat, 18 Jul 2020 20:43:14 -0700 (PDT) Received: by mail-pj1-x1042.google.com with SMTP id ch3so8422415pjb.5 for ; Sat, 18 Jul 2020 20:43:14 -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; bh=1T+jh3W0scfcnuMl49PwBnYGAGM1oxS7ItKUJQINCeQ=; b=hb/74Vi3K6fWinqsDmMmRpLg0iU4bTITUl88+EjkSaYsj1wAgJuZG4vRaHVdmKWdG0 oEOF3tamNVmX5GkgGKnMtxsg+xGCpLue5v3p0akz+ph3pvyYk2hr6Zbnft5a+gk2Sopw 7w5L7l3pUQ4ot7ZuMZzzaKPROB/PwGHrqkl2qXAQ5bL7pI3RiHXnvpiXvoNFl9Bm5uC/ HLjfipCUu6vBKMr8K+a4C8tQtPf6PWVr9Nycwzk7284HtBdo9LlLMjiJa8O+f6hZZaYt DMAm4+uoJvrbdcStt9c7zAFwrZ2T5d6nCGXfYyXRHNHQIvN0R2FPRo9TXuLg3yj+EfQw l2kQ== 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; bh=1T+jh3W0scfcnuMl49PwBnYGAGM1oxS7ItKUJQINCeQ=; b=OdRODhaZigo2LGF5vJZ4lKaWyMjldEEVODtu3J2BELZ+44c2ctmP4vZja/5p8ddXjC PmAzY5oJ3Jtv6hEAHKpIpYHOhiXAc4bScQQJhlI2e6Y1A9lNLXeXp3RsXrzetDRRwn5M AUcMDbOOhdMZdX1Rk978QZpF6jDJ01+P8FO6P7wjAo3DhOWjB167wB4lmx5YwpsMDceu Vlp0jK/AYWFbKwg3LeVyT+YKdKiIiuBywVzhg7wSk7ohkH55Mh2CzifHZKdmaW9A50R4 VY3Eo/MOPjwe//0hNlf9in7CdsocPaWuCLcKX/rzQClhZCcf1xyq90Ew40mJic4inpsp VnJA== X-Gm-Message-State: AOAM532qyLx0zjPvDRVe7geD849TSceQnpBTRhRw1ydmfxYVlFM2RyIg 6yXt9pnoEQXUuBbYowZeZXU= X-Google-Smtp-Source: ABdhPJwOzfXrGodK4X9wqgPOinhduh1qLcO2IjhVoI8/76munxpfiVXlFyQSgGn4Vpa9eAPnyzMqpQ== X-Received: by 2002:a17:902:9042:: with SMTP id w2mr13073419plz.8.1595130194284; Sat, 18 Jul 2020 20:43:14 -0700 (PDT) Received: from localhost ([2409:10:2e40:5100:6e29:95ff:fe2d:8f34]) by smtp.gmail.com with ESMTPSA id cv7sm6752345pjb.9.2020.07.18.20.43.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 18 Jul 2020 20:43:13 -0700 (PDT) Date: Sun, 19 Jul 2020 12:43:12 +0900 From: Sergey Senozhatsky To: Marco Elver Cc: John Ogness , Petr Mladek , Peter Zijlstra , Sergey Senozhatsky , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Greg Kroah-Hartman , Andrea Parri , Thomas Gleixner , Paul McKenney , kexec@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 4/4] printk: use the lockless ringbuffer Message-ID: <20200719034312.GA566736@jagdpanzerIV.localdomain> References: <20200709132344.760-1-john.ogness@linutronix.de> <20200709132344.760-5-john.ogness@linutronix.de> <20200718121053.GA691245@elver.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200718121053.GA691245@elver.google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marco, On (20/07/18 14:10), Marco Elver wrote: > > It seems this causes a regression observed at least with newline-only > printks. I noticed this during -next testing because various debugging > tools (K*SAN, lockdep, etc.) use e.g. pr_{err,warn,info}("\n") to format > reports. > > Without wanting to wait for a report from one of these debugging tools, > a simple reproducer is below. Without this patch, the expected newline > is printed. Empty/blank lines carry no valuable payload, could you please explain why do you consider this to be a regression? -ss