net: hsr: create an API to get hsr port type

Since the introduction of HSR_PT_INTERLINK in commit 5055ccc ("net:
hsr: Provide RedBox support (HSR-SAN)"), we see that different port
types require different settings for hardware offload, which was not the
case before when we only had HSR_PT_SLAVE_A and HSR_PT_SLAVE_B. But
there is currently no way to know which port is which type, so create
the hsr_get_port_type() API function and export it.

When hsr_get_port_type() is called from the device driver, the port can
must be found in the HSR port list. An important use case is for this
function to work from offloading drivers' NETDEV_CHANGEUPPER handler,
which is triggered by hsr_portdev_setup() -> netdev_master_upper_dev_link().
Therefore, we need to move the addition of the hsr_port to the HSR port
list prior to calling hsr_portdev_setup(). This makes the error
restoration path also more similar to hsr_del_port(), where
kfree_rcu(port) is already used.

Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Lukasz Majewski <lukma@denx.de>
Signed-off-by: Xiaoliang Yang <xiaoliang.yang_1@nxp.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Łukasz Majewski <lukma@nabladev.com>
Link: https://patch.msgid.link/20251130131657.65080-3-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Xiaoliang Yang

include/linux/if_hsr.h

@@ -43,6 +43,8 @@ extern bool is_hsr_master(struct net_device *dev);
 extern int hsr_get_version(struct net_device *dev, enum hsr_version *ver);
 struct net_device *hsr_get_port_ndev(struct net_device *ndev,
 				     enum hsr_port_type pt);
+int hsr_get_port_type(struct net_device *hsr_dev, struct net_device *dev,
+		      enum hsr_port_type *type);
 #else
 static inline bool is_hsr_master(struct net_device *dev)
 {
@@ -59,6 +61,13 @@ static inline struct net_device *hsr_get_port_ndev(struct net_device *ndev,
 {
 	return ERR_PTR(-EINVAL);
 }
+
+static inline int hsr_get_port_type(struct net_device *hsr_dev,
+				    struct net_device *dev,
+				    enum hsr_port_type *type)
+{
+	return -EINVAL;
+}
 #endif /* CONFIG_HSR */
 
 #endif /*_LINUX_IF_HSR_H_*/

net/hsr/hsr_device.c

@@ -690,6 +690,26 @@ struct net_device *hsr_get_port_ndev(struct net_device *ndev,
 }
 EXPORT_SYMBOL(hsr_get_port_ndev);
 
+int hsr_get_port_type(struct net_device *hsr_dev, struct net_device *dev,
+		      enum hsr_port_type *type)
+{
+	struct hsr_priv *hsr = netdev_priv(hsr_dev);
+	struct hsr_port *port;
+
+	rcu_read_lock();
+	hsr_for_each_port(hsr, port) {
+		if (port->dev == dev) {
+			*type = port->type;
+			rcu_read_unlock();
+			return 0;
+		}
+	}
+	rcu_read_unlock();
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL(hsr_get_port_type);
+
 /* Default multicast address for HSR Supervision frames */
 static const unsigned char def_multicast_addr[ETH_ALEN] __aligned(2) = {
 	0x01, 0x15, 0x4e, 0x00, 0x01, 0x00

net/hsr/hsr_slave.c

@@ -207,22 +207,23 @@ int hsr_add_port(struct hsr_priv *hsr, struct net_device *dev,
 	port->type = type;
 	ether_addr_copy(port->original_macaddress, dev->dev_addr);
 
+	list_add_tail_rcu(&port->port_list, &hsr->ports);
+
 	if (type != HSR_PT_MASTER) {
 		res = hsr_portdev_setup(hsr, dev, port, extack);
 		if (res)
 			goto fail_dev_setup;
 	}
 
-	list_add_tail_rcu(&port->port_list, &hsr->ports);
-
 	master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
 	netdev_update_features(master->dev);
 	dev_set_mtu(master->dev, hsr_get_max_mtu(hsr));
 
 	return 0;
 
 fail_dev_setup:
-	kfree(port);
+	list_del_rcu(&port->port_list);
+	kfree_rcu(port, rcu);
 	return res;
 }