linux-kernel - Re: [RFC][PATCHv5 3/7] printk: introduce per-cpu safe

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Date:   Tue, 13 Dec 2016 00:28:36 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jan Kara <jack@...e.cz>, Tejun Heo <tj@...nel.org>,
        Calvin Owens <calvinowens@...com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [RFC][PATCHv5 3/7] printk: introduce per-cpu safe_print seq
 buffer

On (12/12/16 14:54), Petr Mladek wrote:
[..]
> > > Hmm, I wanted to describe why we need another per-CPU buffer in NMI
> > > and I am not sure that we really need it.
> > 
> > NMI-printk can interrupt safe-printk's vsnprintf() in the middle of
> > the "while (*fmt)" loop: safe-priNMI-PRINTK
> 
> But this already happens when any of the WARNs is triggered
> inside vsnprintf(). Either this is safe or we are in
> trouble.
[..]
> Well, I am not sure if we should bother.

well, I'd probably agree that we shouldn't care. I'd may be even
say that nested warnings from vsnprintf() are not so important to
over-complicated everything (comparing to lost NMI-printk messages,
which are really important).


> Well, is it that bad to ask for better comments?

ok, I'll take a look. gotta re-base the series once again anyway.

> Or am I dumb and it was all obvious?

of course no! I never said that. never! :)
my apologies.

	-ss