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

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Message-ID: <CAHk-=wizC7pn=+F5kNWaz65hb=meyVGLgkGGfZ82mNXp=-E=tQ@mail.gmail.com>
Date:   Fri, 9 Nov 2018 08:08:13 -0600
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     sergey.senozhatsky.work@...il.com
Cc:     penguin-kernel@...ove.sakura.ne.jp, Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        dvyukov@...gle.com, Steven Rostedt <rostedt@...dmis.org>,
        glider@...gle.com, fengguang.wu@...el.com, jpoimboe@...hat.com,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Will Deacon <will.deacon@....com>
Subject: Re: [PATCH 3/3] lockdep: Use line-buffered printk() for lockdep messages.

On Fri, Nov 9, 2018 at 12:12 AM Sergey Senozhatsky
<sergey.senozhatsky.work@...il.com> wrote:
>
> Dunno. I guess we still haven't heard from Linus because he did quite a good
> job setting up his 'email filters' ;)

Not filters, just long threads that I lurk on.

I don't actually care too much about this - the part I care about is
that when panics etc happen, things go out with a true best effort.

And "best effort" actually means "reality", not "theory". I don't care
one whit for some broken odd serial console that has a lock and
deadlocks if you get a panic just in the right place. I care about the
main printk/tty code doing the right thing, and avoiding the locks
with the scheduler and timers etc. So the timestamping and wakeup code
needing locks - or thinking you can delay things and print them out
later (when no later happens because you're panicing in an NMI) -
*that* is what I care deeply about.

Something like having a line buffering interface for random debugging
messages etc, I just don't get excited about. It just needs to be
simple enough and robust enough. You guys seem to be talking it out
ok.

             Linus