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SubjectRe: [PATCH] sound_core.c: Remove BKL from soundcore_open
On Sun, 11 Oct 2009 20:17:59 +0100
Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

> > it's getting time though to bite the bullet and make it a real
> > normal mutex. Lockdep will then flag a bunch of sh*t we'll need to
> > fix, but without doing that we're never going to really make
> > progress.
>
> It won't. Instead you get situations like one ioctl blocking another
> to an unrelated device that just causes weird failures and performance
> problems, or in some cases deadlocks.

yes the bkl using code will be slower because it'll now hit contention.

The deadlocks we need to catch imo; those are the behaviors that are
the worst offenders in terms of BKL weird behavior.

>
> Open routines block so it takes about 5 seconds of thought to realise
> that using a mutex here is brain dead and doesn't work.

it also takes 5 seconds to realize "uh oh. they block. BKL is rather
limited in what it provides".


--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org


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