Re: [PATCH] a new lock algorithm with lock value and CS counts in the same atomic int

[Alexander Monakov <amonakov@ispras.ru>]

On Sun, 18 Jun 2017, Rich Felker wrote:
> > I suggest dropping this and spelling 'INT_MIN + current' as 'current - 1 -
> > INT_MAX' below.  (all you need is that INT_MIN <= -INT_MAX)
> 
> I think this can be dropped entirely for musl's purposes and
> essentially for all practical purposes.

In any case, the second half of that suggestion stands: using INT_MAX
consistently everywhere should be better for clarity.

> > > +				__syscall(SYS_futex, l, FUTEX_WAIT|FUTEX_PRIVATE, current, 0) != -ENOSYS
> > > +					|| __syscall(SYS_futex, l, FUTEX_WAIT, current, 0);
> > 
> > It's probably better to put this into a new static inline function in
> > pthread_impl.h next to __wake (e.g. __futexwait) and use it here and in __wait.
> 
> Is there a reason __wait doesn't work?

__wait doesn't fit here at all, for instance it manipulates a separate int with
waiters count.

Alexander