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

From: Waiman Long
Date: Mon Jun 02 2014 - 13:43:10 EST


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@xxxxxxxxxxxxx> 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
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