kthread: unexport kthread_blkcg

kthread_blkcg is only used by the built-in blk-cgroup code.

Signed-off-by: Christoph Hellwig <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

Author: Christoph Hellwig

include/linux/kthread.h

@@ -222,9 +222,5 @@ void kthread_associate_blkcg(struct cgroup_subsys_state *css);
 struct cgroup_subsys_state *kthread_blkcg(void);
 #else
 static inline void kthread_associate_blkcg(struct cgroup_subsys_state *css) { }
-static inline struct cgroup_subsys_state *kthread_blkcg(void)
-{
-	return NULL;
-}
 #endif
 #endif /* _LINUX_KTHREAD_H */

kernel/kthread.c

@@ -1522,5 +1522,4 @@ struct cgroup_subsys_state *kthread_blkcg(void)
 	}
 	return NULL;
 }
-EXPORT_SYMBOL(kthread_blkcg);
 #endif