Re: [patch 5/9] mutex subsystem, core

[Oleg Nesterov <oleg@tv-sign.ru>]

Ingo Molnar wrote:
> 
> > This is a minor issue, but still I think it makes sense to optimize
> > for uncontended case:
> >
> >       old_val = atomic_xchg(&lock->count, 0); // no sleepers
> >
> >       if (old_val == 1) {
> >               // sleepers ?
> >               if (!list_empty(&lock->wait_list))
> >                       // need to wakeup them
> >                       atomic_set(&lock->count, -1);
> >               ...
> >       }
> >       [*]
> 
> but then we'd have to set it to -1 again, at [*], because we are now

Oh! You are right, thanks.

Oleg.
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