Re: [PATCH-tip v3 02/14] locking/rwsem: Make owner available even if !CONFIG_RWSEM_SPIN_ON_OWNER
From: Peter Zijlstra
Date: Fri Apr 12 2019 - 03:05:58 EST
On Fri, Apr 12, 2019 at 09:02:09AM +0200, Ingo Molnar wrote:
> * Waiman Long <longman@xxxxxxxxxx> wrote:
> > On 04/11/2019 04:12 AM, Peter Zijlstra wrote:
> > > On Wed, Apr 10, 2019 at 02:42:19PM -0400, Waiman Long wrote:
> > >> The owner field in the rw_semaphore structure is used primarily for
> > >> optimistic spinning. However, identifying the rwsem owner can also be
> > >> helpful in debugging as well as tracing locking related issues when
> > >> analyzing crash dump. The owner field may also store state information
> > >> that can be important to the operation of the rwsem.
> > >>
> > >> So the owner field is now made a permanent member of the rw_semaphore
> > >> structure irrespective of CONFIG_RWSEM_SPIN_ON_OWNER.
> > > sem->owner is still initialized under CONFIG_RWSEM_SPIN_ON_OWNER.
> > Oh, you are right. I missed that part. I will fix it in the next version.
> Could you please post the next series against tip:WIP.locking/core, which
> is already being dogfood-ed in -tip and which I'm running on my desktop?
> I'll backmerge any fixes as needed/requested.
Urgh, please no, that's going to be hell to review :/