[PATCH 3/7] blkcg: make blkcg_activate_policy() allow NULL ->pd_init_fn

[Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

blkg_create() allows NULL ->pd_init_fn() but blkcg_activate_policy()
doesn't.  As both in-kernel policies implement ->pd_init_fn, it
currently doesn't break anything.  Update blkcg_activate_policy() so
that its behavior is consistent with blkg_create().

Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Vivek Goyal <vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 block/blk-cgroup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 898f560..617a586 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1045,7 +1045,8 @@ int blkcg_activate_policy(struct request_queue *q,
 		blkg->pd[pol->plid] = pd;
 		pd->blkg = blkg;
 		pd->plid = pol->plid;
-		pol->pd_init_fn(blkg);
+		if (pol->pd_init_fn)
+			pol->pd_init_fn(blkg);
 
 		spin_unlock(&blkg->blkcg->lock);
 	}
-- 
2.4.3