linux-kernel - Re: [PATCH 3/3] lockdep: Use line-buffered printk() for lockdep messages.

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Message-ID: <20181106125753.nhuztqefadglbvec@pathway.suse.cz>
Date:   Tue, 6 Nov 2018 13:57:53 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Dmitriy Vyukov <dvyukov@...gle.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Alexander Potapenko <glider@...gle.com>,
        Fengguang Wu <fengguang.wu@...el.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        Ingo Molnar <mingo@...hat.com>,
        Will Deacon <will.deacon@....com>
Subject: Re: [PATCH 3/3] lockdep: Use line-buffered printk() for lockdep
 messages.

On Tue 2018-11-06 18:05:44, Sergey Senozhatsky wrote:
> On (11/06/18 09:38), Petr Mladek wrote:
> > 
> > If you would want to avoid buffering, you could set the number
> > of buffers to zero. Then it would always fallback to
> > the direct printk().

This comment was a hint for Peter and his workarounds. He ignores most
of printk() code and writes messages directly to the serial console.


> This printk-fallback makes me wonder if 'cont' really can ever go away.
> We would totally break cont printk-s that trapped into printk-fallback;
> as opposed to current sometimes-cont-works-just-fine.

It could break things totally only when the new approach completely
fails. I you have any doubts or suggestions then please comment on
the patch adding the API.

Best Regards,
Petr