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

[Thomas Gleixner]

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.

Thanks,

	tglx