Re: [PATCH 2/2] locking/percpu-rwsem: Introduce bias knob

From: Paul E. McKenney
Date: Fri Jul 15 2016 - 14:01:32 EST


On Fri, Jul 15, 2016 at 06:49:39PM +0200, Oleg Nesterov wrote:
> On 07/15, Paul E. McKenney wrote:
> > On Fri, Jul 15, 2016 at 03:45:24PM +0200, Oleg Nesterov wrote:
> > > On 07/15, Paul E. McKenney wrote:
> > > >
> > > > On Fri, Jul 15, 2016 at 03:27:09PM +0200, Oleg Nesterov wrote:
> > > > >
> > > > > Heh ;) I too think it should be renamed. I'd suggest
> > > > >
> > > > > __rcu_sync_enter(rss);
> > > > >
> > > > > although I do not really mind and agree with any name.
> > > >
> > > > Hmmm... Why not just move the checks out into the caller? That
> > > > would make the intent much more clear.
> > >
> > > Hmm. which caller?
> >
> > The ones associated with a percpu_rwsem_bias of PERCPU_RWSEM_READER.
>
> Ah. But if we add __rcu_sync_enter() instead of bias/PERCPU_RWSEM_READER.
>
> IOW, please ignore 2/2 which adds PERCPU_RWSEM_READER, the new version
> just adds rcu_sync_sabotage() which should be renamed (and use GP_PASSED).

OK, then move the checks out into the callers that would have used
__rcu_sync_enter(). ;-)

Thanx, Paul