net_sched: switch to rcu_work

Commit 05f0fe6b74 ("RCU, workqueue: Implement rcu_work") introduces
new API's for dispatching work in a RCU callback. Now we can just
switch to the new API's for tc filters. This could get rid of a lot
of code.

Cc: Tejun Heo <tj@kernel.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_fw.c

@@ -47,10 +47,7 @@ struct fw_filter {
 #endif /* CONFIG_NET_CLS_IND */
 	struct tcf_exts		exts;
 	struct tcf_proto	*tp;
-	union {
-		struct work_struct	work;
-		struct rcu_head		rcu;
-	};
+	struct rcu_work		rwork;
 };
 
 static u32 fw_hash(u32 handle)
@@ -134,21 +131,14 @@ static void __fw_delete_filter(struct fw_filter *f)
 
 static void fw_delete_filter_work(struct work_struct *work)
 {
-	struct fw_filter *f = container_of(work, struct fw_filter, work);
-
+	struct fw_filter *f = container_of(to_rcu_work(work),
+					   struct fw_filter,
+					   rwork);
 	rtnl_lock();
 	__fw_delete_filter(f);
 	rtnl_unlock();
 }
 
-static void fw_delete_filter(struct rcu_head *head)
-{
-	struct fw_filter *f = container_of(head, struct fw_filter, rcu);
-
-	INIT_WORK(&f->work, fw_delete_filter_work);
-	tcf_queue_work(&f->work);
-}
-
 static void fw_destroy(struct tcf_proto *tp, struct netlink_ext_ack *extack)
 {
 	struct fw_head *head = rtnl_dereference(tp->root);
@@ -164,7 +154,7 @@ static void fw_destroy(struct tcf_proto *tp, struct netlink_ext_ack *extack)
 					 rtnl_dereference(f->next));
 			tcf_unbind_filter(tp, &f->res);
 			if (tcf_exts_get_net(&f->exts))
-				call_rcu(&f->rcu, fw_delete_filter);
+				tcf_queue_work(&f->rwork, fw_delete_filter_work);
 			else
 				__fw_delete_filter(f);
 		}
@@ -193,7 +183,7 @@ static int fw_delete(struct tcf_proto *tp, void *arg, bool *last,
 			RCU_INIT_POINTER(*fp, rtnl_dereference(f->next));
 			tcf_unbind_filter(tp, &f->res);
 			tcf_exts_get_net(&f->exts);
-			call_rcu(&f->rcu, fw_delete_filter);
+			tcf_queue_work(&f->rwork, fw_delete_filter_work);
 			ret = 0;
 			break;
 		}
@@ -316,7 +306,7 @@ static int fw_change(struct net *net, struct sk_buff *in_skb,
 		rcu_assign_pointer(*fp, fnew);
 		tcf_unbind_filter(tp, &f->res);
 		tcf_exts_get_net(&f->exts);
-		call_rcu(&f->rcu, fw_delete_filter);
+		tcf_queue_work(&f->rwork, fw_delete_filter_work);
 
 		*arg = fnew;
 		return err;