Re: [PATCH 2/2] locking/rwsem: Disable optimistic spinning for PA-RISC

Chris Metcalf
2014-06-06T17:20:04Z

On 6/6/2014 1:11 PM, Peter Zijlstra wrote:
> The thing is, all these archs are broken beyond this particular problem,
> Mikulas Patocka found a number of other spots.
>
> In any case, sure I can exclude more. Although ideally someone goes do
> that __atomic sparse thing to flush out all this.
>
> ---
> Subject: locking, mutex: Disable optimistic spinning on !RMW archs
>
> For some archs a regular store does not play nice with cmpxchg(), the
> optimistic spinning code (and various other places not caught by this)
> break this assumption and make things go boom.
>
> Until something better is found, disable optimistic spinning for these
> archs.
>
> [..]
>
> +config ARCH_NO_ATOMIC_RMW
> + def_bool y
> + depends on PARISC || SPARC32 || METAG_ATOMICITY_LOCK1 || (TILE && !TILEGX) || (ARC && !ARC_HAS_LLSC)

For tile:

Acked-by: Chris Metcalf <cmetcalf@tilera.com>

But you should use "TILEPRO" (added in kernel 3.5) instead of "(TILE && !TILEGX)".

--
Chris Metcalf, Tilera Corp.