Re: [patch V2 2/7] futex: Hash private futexes per process

[Darren Hart]

On Sat, May 07, 2016 at 10:45:57AM +0200, Thomas Gleixner wrote:
> On Fri, 6 May 2016, Darren Hart wrote:
>  > It would be good to have a way to detect that the process private hash table was
> > > successfully created. Perhaps a /proc/pid/ feature? This would allow us to write
> > > a functional futex test for tools/testing/selftests/futex
> > 
> > I suppose we could just use FUTEX_PREALLOC_HASH for this purpose, passing in the
> > default hash size. This will either return the default, the previously set
> > value, or 0, indicating the global hash is being used. That should be sufficient
> > for programatically determining the state of the system.
> 
> Right.
>  
> > The /proc/pid/futex_hash_size option may still be convenient for other purposes.
> > Perhaps with a -1 indicating it hasn't been set yet.
> 
> Dunno, whether that's valuable, but it can be done on top.

Agreed. We can leave that to the kselftest patch, and if it's easily done
without this, then we're done. If not, we can look at it then.

-- 
Darren Hart
Intel Open Source Technology Center