ipc,rcu: convert call_rcu(free_un) to kfree_rcu()

index 0e0d49b..243437e 100644
@@ -689,12 +689,6 @@ static int count_semzcnt (struct sem_array * sma, ushort semnum)
 	return semzcnt;
 }
 
-static void free_un(struct rcu_head *head)
-{
-	struct sem_undo *un = container_of(head, struct sem_undo, rcu);
-	kfree(un);
-}
-
 /* Free a semaphore set. freeary() is called with sem_ids.rw_mutex locked
  * as a writer and the spinlock for this semaphore set hold. sem_ids.rw_mutex
  * remains locked on exit.

@@ -714,7 +708,7 @@ static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 		un->semid = -1;
 		list_del_rcu(&un->list_proc);
 		spin_unlock(&un->ulp->lock);
-		call_rcu(&un->rcu, free_un);
+		kfree_rcu(un, rcu);
 	}
 
 	/* Wake up all pending processes and let them fail with EIDRM. */

@@ -1610,7 +1604,7 @@ void exit_sem(struct task_struct *tsk)
 		sem_unlock(sma);
 		wake_up_sem_queue_do(&tasks);
 
-		call_rcu(&un->rcu, free_un);
+		kfree_rcu(un, rcu);
 	}
 	kfree(ulp);
 }