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

[Christopher Friesen]

David Howells wrote:
> Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:

> > It seems to me it would be far far saner to define something like
> >
> > 	sleep_lock(&foo)
> > 	sleep_unlock(&foo)
> > 	sleep_trylock(&foo)
>
> Which would be a _lot_ more work. It would involve about ten times as many
> changes, I think, and thus be more prone to errors.

"lots of work" has never been a valid reason for not doing a kernel 
change...

In this case, introducing a new API means the changes can be made over time.

As time goes on you can convert more and more code to the mutex/sleep 
lock and any tricky code just stays with the older API until someone who 
understands it can vet it.

As Alan mentioned, the standard counting semaphore API is up/down. 
Making those refer to a sleeping mutex violates the principle of least 
surprise.

Chris

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