linux-next: build failure after merge of the drm-misc tree

[Matthew Wilcox]

On Tue, Apr 02, 2019 at 01:55:03PM +0800, Qiang Yu wrote:
> Thanks, patch is:
> Reviewed-by: Qiang Yu <yuq825 at gmail.com>

This looks like a fairly naive conversion from the old IDR API to the
XArray API.  You should be able to remove mgr->lock entirely, relying on
the xa_lock for synchronising free and get.  If you think it's worth it,
you could even use kfree_rcu() to free the ctx and kref_get_unless_zero()
and then your get path would be lock-free.