drm: Use idr_init_base(1) when using id==0 for invalid
Use the new idr_init_base() function to create an IDR that knows id==0
is never allocated as it maps to an invalid identifier. By knowing that
id==0 is invalid, the IDR can start from id=1 instead avoiding the issue
of having to start each lookup from the zeroth leaf as id==0 is always
unused (and thus the tree-of-bitmaps indicate that is the first
available).
References: 6ce711f27500 ("idr: Make 1-based IDRs more efficient")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Christian Konig <christian.koenig@amd.com>
Cc: Dave Airlie <airlied@redhat.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Christian König <christian.koenig@amd.com> as well.
Link: https://patchwork.freedesktop.org/patch/msgid/20180212145533.30046-1-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 0b7b0d1..d4f4ce4 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -546,7 +546,7 @@ static int drm_syncobj_export_sync_file(struct drm_file *file_private,
void
drm_syncobj_open(struct drm_file *file_private)
{
- idr_init(&file_private->syncobj_idr);
+ idr_init_base(&file_private->syncobj_idr, 1);
spin_lock_init(&file_private->syncobj_table_lock);
}