Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

On Maw, 2005-12-13 at 15:39 +0000, David Howells wrote:
>  (3) Some people want mutexes to be:
> 
>      (a) only releasable in the same context as they were taken
> 
>      (b) not accessible in interrupt context, or that (a) applies here also
> 
>      (c) not initialisable to the locked state
> 
>      But this means that the current usages all have to be carefully audited,
>      and sometimes that unobvious.

Only if you insist on replacing them immediately. If you submit a
*small* patch which just adds the new mutexes then a series of small
patches can gradually convert code where mutexes are better. People will
naturally hit the hot and critical points first meaning that in a short
time the users of semaphores will be those who need it, and those who
are not critical to performance.

There is a problemn with init_MUTEX*/DECLARE_MUTEX naming being used for
semaphore struct init and I don't see a nice way to fix that either. I'd
rather see people just have to fix those as compiler errors (or a perl
-e regexp run to make them all init_SEM/DECLARE_SEM before any other
changes are made).


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