linux-kernel - Re: printk: what is going on with additional newlines?

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Message-Id: <201708300541.IHE65621.SFMHVFOQOOtJFL@I-love.SAKURA.ne.jp>
Date:   Wed, 30 Aug 2017 05:41:20 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     torvalds@...ux-foundation.org, sergey.senozhatsky.work@...il.com
Cc:     pavel@....cz, sergey.senozhatsky@...il.com, pmladek@...e.com,
        rostedt@...dmis.org, jack@...e.cz, akpm@...ux-foundation.org,
        jslaby@...e.com, andi@...as.de, linux-kernel@...r.kernel.org
Subject: Re: printk: what is going on with additional newlines?

Linus Torvalds wrote:
> On Tue, Aug 29, 2017 at 10:00 AM, Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
> >
> > I refuse to help those things. We mis-designed things
> 
> Actually, let me rephrase that:
> 
> It might actually be a good idea to help those things, by making
> helper functions available that do the marshalling.
> 
> So not calling "printk()" directly, but having a set of simple
> "buffer_print()" functions where each user has its own buffer, and
> then the "buffer_print()" functions will help people do nicely output
> data.
> 
> So if the issue is that people want to print (for example) hex dumps
> one character at a time, but don't want to have each character show up
> on a line of their own, I think we might well add a few functions to
> help dop that.
> 
> But they wouldn't be "printk". They would be the buffering functions
> that then call printk when tyhey have buffered a line.
> 
> That avoids the whole nasty issue with printk - printk wants to show
> stuff early (because _maybe_ it's critical) and printk wants to make
> log records with timestamps and loglevels. And printk has serious
> locking issues that are really nasty and fundamental.
> 
> A private buffer has none of those issues.

Yes, I posted "[PATCH] printk: Add best-effort printk() buffering." at
http://lkml.kernel.org/r/1493560477-3016-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp .

> 
>                  Linus
>