Re: [PATCH 1/12]: MUTEX: Implement mutexes

[Nick Piggin]

Steven Rostedt wrote:
> On Fri, 2005-12-16 at 23:13 +0000, David Howells wrote:

> > This patch set does the following:
> >
> > (1) Renames DECLARE_MUTEX and DECLARE_MUTEX_LOCKED to be DECLARE_SEM_MUTEX and
> >     DECLARE_SEM_MUTEX_LOCKED for counting semaphores.
>
>
> Could we really get rid of that "MUTEX" part.  A counting semaphore is
> _not_ a mutex, although a mutex _is_ a counting semaphore.  As is a Jack
> Russell is a dog, but a dog is not a Jack Russell.

Really?

A Jack Russell is a dog because anything you say about a dog can
also be said about a Jack Russell.

A counting semaphore is a mutex for the same reason (and observe
that 99% of users use the semaphore as a mutex). A mutex definitely
is not a counting semaphore. David's implementation of mutexes
don't count at all.

If you want to use a semaphore as a mutex, DECLARE_SEM_MUTEX isn't
a terrible name.

--
SUSE Labs, Novell Inc.

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