hsr: remove unnecessary rcu_read_lock() in hsr module

In order to access the port list, the hsr_port_get_hsr() is used.
And this is protected by RTNL and RCU.
The hsr_fill_info(), hsr_check_carrier(), hsr_dev_open() and
hsr_get_max_mtu() are protected by RTNL.
So, rcu_read_lock() in these functions are not necessary.
The hsr_handle_frame() also uses rcu_read_lock() but this function
is called by packet path.
It's already protected by RCU.
So, the rcu_read_lock() in hsr_handle_frame() can be removed.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/hsr/hsr_device.c

@@ -57,24 +57,19 @@ static void hsr_set_operstate(struct hsr_port *master, bool has_carrier)
 static bool hsr_check_carrier(struct hsr_port *master)
 {
 	struct hsr_port *port;
-	bool has_carrier;
 
-	has_carrier = false;
+	ASSERT_RTNL();
 
-	rcu_read_lock();
-	hsr_for_each_port(master->hsr, port)
+	hsr_for_each_port(master->hsr, port) {
 		if (port->type != HSR_PT_MASTER && is_slave_up(port->dev)) {
-			has_carrier = true;
-			break;
+			netif_carrier_on(master->dev);
+			return true;
 		}
-	rcu_read_unlock();
+	}
 
-	if (has_carrier)
-		netif_carrier_on(master->dev);
-	else
-		netif_carrier_off(master->dev);
+	netif_carrier_off(master->dev);
 
-	return has_carrier;
+	return false;
 }
 
 static void hsr_check_announce(struct net_device *hsr_dev,
@@ -118,11 +113,9 @@ int hsr_get_max_mtu(struct hsr_priv *hsr)
 	struct hsr_port *port;
 
 	mtu_max = ETH_DATA_LEN;
-	rcu_read_lock();
 	hsr_for_each_port(hsr, port)
 		if (port->type != HSR_PT_MASTER)
 			mtu_max = min(port->dev->mtu, mtu_max);
-	rcu_read_unlock();
 
 	if (mtu_max < HSR_HLEN)
 		return 0;
@@ -157,7 +150,6 @@ static int hsr_dev_open(struct net_device *dev)
 	hsr = netdev_priv(dev);
 	designation = '\0';
 
-	rcu_read_lock();
 	hsr_for_each_port(hsr, port) {
 		if (port->type == HSR_PT_MASTER)
 			continue;
@@ -175,7 +167,6 @@ static int hsr_dev_open(struct net_device *dev)
 			netdev_warn(dev, "Slave %c (%s) is not up; please bring it up to get a fully working HSR network\n",
 				    designation, port->dev->name);
 	}
-	rcu_read_unlock();
 
 	if (designation == '\0')
 		netdev_warn(dev, "No slave devices configured\n");

net/hsr/hsr_netlink.c

@@ -79,29 +79,20 @@ static int hsr_newlink(struct net *src_net, struct net_device *dev,
 
 static int hsr_fill_info(struct sk_buff *skb, const struct net_device *dev)
 {
-	struct hsr_priv *hsr;
+	struct hsr_priv *hsr = netdev_priv(dev);
 	struct hsr_port *port;
-	int res;
-
-	hsr = netdev_priv(dev);
-
-	res = 0;
 
-	rcu_read_lock();
 	port = hsr_port_get_hsr(hsr, HSR_PT_SLAVE_A);
-	if (port)
-		res = nla_put_u32(skb, IFLA_HSR_SLAVE1, port->dev->ifindex);
-	rcu_read_unlock();
-	if (res)
-		goto nla_put_failure;
+	if (port) {
+		if (nla_put_u32(skb, IFLA_HSR_SLAVE1, port->dev->ifindex))
+			goto nla_put_failure;
+	}
 
-	rcu_read_lock();
 	port = hsr_port_get_hsr(hsr, HSR_PT_SLAVE_B);
-	if (port)
-		res = nla_put_u32(skb, IFLA_HSR_SLAVE2, port->dev->ifindex);
-	rcu_read_unlock();
-	if (res)
-		goto nla_put_failure;
+	if (port) {
+		if (nla_put_u32(skb, IFLA_HSR_SLAVE2, port->dev->ifindex))
+			goto nla_put_failure;
+	}
 
 	if (nla_put(skb, IFLA_HSR_SUPERVISION_ADDR, ETH_ALEN,
 		    hsr->sup_multicast_addr) ||

net/hsr/hsr_slave.c

@@ -25,7 +25,6 @@ static rx_handler_result_t hsr_handle_frame(struct sk_buff **pskb)
 		return RX_HANDLER_PASS;
 	}
 
-	rcu_read_lock(); /* hsr->node_db, hsr->ports */
 	port = hsr_port_get_rcu(skb->dev);
 	if (!port)
 		goto finish_pass;
@@ -45,11 +44,9 @@ static rx_handler_result_t hsr_handle_frame(struct sk_buff **pskb)
 	hsr_forward_skb(skb, port);
 
 finish_consume:
-	rcu_read_unlock(); /* hsr->node_db, hsr->ports */
 	return RX_HANDLER_CONSUMED;
 
 finish_pass:
-	rcu_read_unlock(); /* hsr->node_db, hsr->ports */
 	return RX_HANDLER_PASS;
 }