Re: [v2] locking/percpu-rwsem: Optimize readers and reduce global impact

[Guenter Roeck]

On 08/31/2016 01:09 AM, Peter Zijlstra wrote:
> On Tue, Aug 30, 2016 at 10:21:02PM -0700, Guenter Roeck wrote:
> > Peter,
> >
> > The call to rcu_sync_is_idle() causes the following build error when building
> > x86_64:allmodconfig.
> >
> > ERROR: "rcu_sync_lockdep_assert" [kernel/locking/locktorture.ko] undefined!
> > ERROR: "rcu_sync_lockdep_assert" [fs/ext4/ext4.ko] undefined!
> >
> > I think this was also reported by the 0-day build bot.
> >
> > The simple fix would of course be to export rcu_sync_lockdep_assert. Before I
> > apply that change to the Android code (where the patch has been aplied and
> > the problem is seen) - do you by any chance have a better solution in mind ?
>
> Nope, that's exactly what Ingo did when he ran into this. If you look at
> commit 80127a39681b ("locking/percpu-rwsem: Optimize readers and reduce
> global impact"), you'll notice the last hunk:
Ah, I missed that, and didn't realize that it is already upstream. Thanks a lot!

Guenter