cgroup: netprio: remove unnecessary task_netprioidx

Since the tasks have been migrated to the cgroup,
there is no need to call task_netprioidx to get
task's cgroup id.
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/netprio_cgroup.c

@@ -222,11 +222,10 @@ static void net_prio_attach(struct cgroup_subsys_state *css,
 			    struct cgroup_taskset *tset)
 {
 	struct task_struct *p;
-	void *v;
+	void *v = (void *)(unsigned long)css->cgroup->id;
 
 	cgroup_taskset_for_each(p, css, tset) {
 		task_lock(p);
-		v = (void *)(unsigned long)task_netprioidx(p);
 		iterate_fd(p->files, 0, update_netprio, v);
 		task_unlock(p);
 	}