Re: [RFC] kern: simple futex for gnumach

[Richard Braun]

On Sun, Sep 22, 2013 at 10:28:47AM +0200, Marin Ramesa wrote:
> On 22.09.2013 02:08:41, Richard Braun wrote:
> > Also, futex_wait_lock looks to be local to futex_wait...
> 
> Yes it is. But if I introduce a more global lock that should imply that 
> there is another operation that is a candidate for being protected by 
> the lock. Which one would that be? Or you had something else in 
> mind ... ?

If it stays this way, the lock just doesn't protect anything... Not to
mention the lock isn't even initialized at all.

I guess for a first attempt, protecting the global hash table Samuel
mentioned, and each futex instance with their own lock, should do. But
if we need to explain that, it might be a sign that you need more
experience on the subject. Maybe try a userspace proof of concept based
on the algorithms presented in "Futexes are tricky" first. This would
also allow more complete testing since simple locks are noops in GNU
Mach.

-- 
Richard Braun