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Date: Thu, 15 Dec 2011 21:22:01 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>, "Ted Ts'o" <tytso@mit.edu>,
        Greg KH <greg@kroah.com>, linux-kernel <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@elte.hu>
Subject: Re: printk() vs tty_io
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>  - Make a special "debug printk" that is not synchronous. Just make it
> buffer things, and have it actually print out from a worker thread or
> whatever. This one *only* takes the lock for that buffer itself, and
> works everywhere. We could probably even do tricks to make it
> NMI-safe.

No buffer lock needed within limits - our kfifo implementation doesn't
need them on sensible hardware.

Alan