Re: [PATCH v2] introduce atomic_pointer to fix a race condition in cancelable mcs spinlocks

Waiman Long
2014-06-02T17:43:04Z

On 06/02/2014 01:12 PM, Davidlohr Bueso wrote:
> On Mon, 2014-06-02 at 10:09 -0700, Linus Torvalds wrote:
>> On Mon, Jun 2, 2014 at 9:25 AM, Peter Zijlstra<peterz@infradead.org> wrote:
>>> And I can't say I'm a particular fan of these ops either, as alternative
>>> I'm almost inclined to just exclude parisc from using opt spinning.
>> Please do.
> I agree, this is the best way out of this mess. Furthermore, it would
> also be nice to consolidate opt spinning in a common CONFIG option --
> right now mutexes and rwsems create their own dependencies.
>

I would suggest adding a RWSEM_SPIN_ON_OWNER to control opt spinning in
rwsem. Currently MUTEX_SPIN_ON_OWNER is doing that for mutex, and it is
disabled when mutex debugging is turned on. So I think it is better to
allow them to be disabled separately.

-Longman