Re: [patch 00/10] mutex subsystem, -V5

From: Linus Torvalds
Date: Thu Dec 22 2005 - 12:44:22 EST




On Thu, 22 Dec 2005, Nicolas Pitre wrote:

> On Thu, 22 Dec 2005, Ingo Molnar wrote:
>
> > Changes since -V4:
> >
> > - removed __ARCH_WANT_XCHG_BASED_ATOMICS and implemented
> > CONFIG_MUTEX_XCHG_ALGORITHM instead, based on comments from
> > Christoph Hellwig.
> >
> > - updated ARM to use CONFIG_MUTEX_XCHG_ALGORITHM.
>
> This is still not what I'd like to see, per my previous comments.
>
> Do you have any strong reason for pursuing that route instead of going
> with my suggested approach?

I'd just prefer a

<asm-generic/mutex-xchg-algo.h>

and then any architecture can do whatever they damn well want, and
anybody who doesn't want to, can just include that header file.

No #ifdef's, no config options, no "generic fallback". Just
unconditionally do the sane thing.

I'm with whoever HATES those stupid __ARCH_xxx #defines. It's a sign of
bad design. Either it's a generic algorithm (and it can be in
<asm-generic> or it's not). In no case should we ever have __ARCH_HAS_xxx
(and yes, that includes cases where we _currently_ use __ARCH_HAS_xxx).

Linus
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