From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751440AbdIAHXi (ORCPT <rfc822;w@1wt.eu>);
        Fri, 1 Sep 2017 03:23:38 -0400
Received: from smtprelay0208.hostedemail.com ([216.40.44.208]:47671 "EHLO
        smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL)
        by vger.kernel.org with ESMTP id S1751237AbdIAHXh (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 1 Sep 2017 03:23:37 -0400
X-Session-Marker: 6A6F6540706572636865732E636F6D
X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::::::::::::::::,RULES_HIT:41:355:379:541:599:960:973:981:988:989:1260:1277:1311:1313:1314:1345:1359:1373:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2198:2199:2393:2559:2562:2828:3138:3139:3140:3141:3142:3353:3622:3865:3866:3867:3868:3870:3871:3872:3873:3874:4043:4250:4321:4641:5007:6742:10004:10400:10848:11026:11232:11658:11914:12296:12438:12740:12895:13069:13311:13357:13439:13894:14659:14819:21080:21088:21433:21627:30012:30054:30060:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:2,LUA_SUMMARY:none
X-HE-Tag: shoes67_59652241ad558
X-Filterd-Recvd-Size: 2594
Message-ID: <1504250613.2361.5.camel@perches.com>
Subject: Re: printk: what is going on with additional newlines?
From: Joe Perches <joe@perches.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Petr Mladek <pmladek@suse.com>, Steven Rostedt <rostedt@goodmis.org>,
        Jan Kara <jack@suse.cz>, Andrew Morton <akpm@linux-foundation.org>,
        Jiri Slaby <jslaby@suse.com>, Andreas Mohr <andi@lisas.de>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Date: Fri, 01 Sep 2017 00:23:33 -0700
In-Reply-To: <20170901065925.GA12104@amd>
References: <20170815025625.1977-1-sergey.senozhatsky@gmail.com>
         <20170828090521.GA25025@amd>
         <CA+55aFx_o_FfCO+c62zMWH8H8rLJsnKZ1TWvMqyUs2A90QJgGg@mail.gmail.com>
         <20170829202447.GA20829@amd>
         <20170901014012.GA814@jagdpanzerIV.localdomain>
         <1504231464.2786.52.camel@perches.com> <20170901065925.GA12104@amd>
Content-Type: text/plain; charset="ISO-8859-1"
X-Mailer: Evolution 3.22.6-1ubuntu1 
Mime-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, 2017-09-01 at 08:59 +0200, Pavel Machek wrote:
> On Thu 2017-08-31 19:04:24, Joe Perches wrote:
> > On Fri, 2017-09-01 at 10:40 +0900, Sergey Senozhatsky wrote:
> > > On (08/29/17 22:24), Pavel Machek wrote:
> > > > > > In 4.13-rc, printk("foo"); printk("bar"); seems to produce
> > > > > > foo\nbar. That's... quite surprising/unwelcome. What is going on
> > > > > > there? Are timestamps responsible?
> > []
> > > > You are welcome not add checkpatch rules to prevent such code from being
> > > > merged...
> > 
> > Pavel, what does this mean?
> That should have been "welcome to".

Right.

Good luck with a checkpatch implementation.

> IMO pr_foo() is bad interface for debugging.

Why?

> I just want to see the data... and difference
> from userspace debugging actually hurts there.

How so?  What data is not available?

Making functions of the various pr_<level> uses
makes it easier to insert things like singletons
for any pr_fmt prefix which could save a few KB
and as well allow for centralized mechanisms to
emit logging messages with
	%ps, __builtin_return_address(0)
instead of using
	"%s <fmt>", __func__, args...
to save even more space.