5 files changed, 39 insertions, 6 deletions

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index af0e2c0394ac..5417f7b1187c 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -864,6 +864,14 @@ disconnect:
 	return err;
 }
 
+static void dsa_switch_teardown_tag_protocol(struct dsa_switch *ds)
+{
+	const struct dsa_device_ops *tag_ops = ds->dst->tag_ops;
+
+	if (tag_ops->disconnect)
+		tag_ops->disconnect(ds);
+}
+
 static int dsa_switch_setup(struct dsa_switch *ds)
 {
 	struct dsa_devlink_priv *dl_priv;
@@ -953,6 +961,8 @@ static void dsa_switch_teardown(struct dsa_switch *ds)
 		ds->slave_mii_bus = NULL;
 	}
 
+	dsa_switch_teardown_tag_protocol(ds);
+
 	if (ds->ops->teardown)
 		ds->ops->teardown(ds);
 
@@ -1409,9 +1419,9 @@ static enum dsa_tag_protocol dsa_get_tag_protocol(struct dsa_port *dp,
 static int dsa_port_parse_cpu(struct dsa_port *dp, struct net_device *master,
 			      const char *user_protocol)
 {
+	const struct dsa_device_ops *tag_ops = NULL;
 	struct dsa_switch *ds = dp->ds;
 	struct dsa_switch_tree *dst = ds->dst;
-	const struct dsa_device_ops *tag_ops;
 	enum dsa_tag_protocol default_proto;
 
 	/* Find out which protocol the switch would prefer. */
@@ -1434,10 +1444,17 @@ static int dsa_port_parse_cpu(struct dsa_port *dp, struct net_device *master,
 		}
 
 		tag_ops = dsa_find_tagger_by_name(user_protocol);
-	} else {
-		tag_ops = dsa_tag_driver_get(default_proto);
+		if (IS_ERR(tag_ops)) {
+			dev_warn(ds->dev,
+				 "Failed to find a tagging driver for protocol %s, using default\n",
+				 user_protocol);
+			tag_ops = NULL;
+		}
 	}
 
+	if (!tag_ops)
+		tag_ops = dsa_tag_driver_get(default_proto);
+
 	if (IS_ERR(tag_ops)) {
 		if (PTR_ERR(tag_ops) == -ENOPROTOOPT)
 			return -EPROBE_DEFER;
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index 6e65c7ffd6f3..71e9707d11d4 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -210,6 +210,7 @@ static inline struct net_device *dsa_master_find_slave(struct net_device *dev,
 extern struct rtnl_link_ops dsa_link_ops __read_mostly;
 
 /* port.c */
+bool dsa_port_supports_hwtstamp(struct dsa_port *dp, struct ifreq *ifr);
 void dsa_port_set_tag_protocol(struct dsa_port *cpu_dp,
 			       const struct dsa_device_ops *tag_ops);
 int dsa_port_set_state(struct dsa_port *dp, u8 state, bool do_fast_age);
diff --git a/net/dsa/master.c b/net/dsa/master.c
index 40367ab41cf8..421de166515f 100644
--- a/net/dsa/master.c
+++ b/net/dsa/master.c
@@ -204,8 +204,7 @@ static int dsa_master_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 		 * switch in the tree that is PTP capable.
 		 */
 		list_for_each_entry(dp, &dst->ports, list)
-			if (dp->ds->ops->port_hwtstamp_get ||
-			    dp->ds->ops->port_hwtstamp_set)
+			if (dsa_port_supports_hwtstamp(dp, ifr))
 				return -EBUSY;
 		break;
 	}
diff --git a/net/dsa/port.c b/net/dsa/port.c
index 208168276995..750fe68d9b2a 100644
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -110,6 +110,22 @@ static bool dsa_port_can_configure_learning(struct dsa_port *dp)
 	return !err;
 }
 
+bool dsa_port_supports_hwtstamp(struct dsa_port *dp, struct ifreq *ifr)
+{
+	struct dsa_switch *ds = dp->ds;
+	int err;
+
+	if (!ds->ops->port_hwtstamp_get || !ds->ops->port_hwtstamp_set)
+		return false;
+
+	/* "See through" shim implementations of the "get" method.
+	 * This will clobber the ifreq structure, but we will either return an
+	 * error, or the master will overwrite it with proper values.
+	 */
+	err = ds->ops->port_hwtstamp_get(ds, dp->index, ifr);
+	return err != -EOPNOTSUPP;
+}
+
 int dsa_port_set_state(struct dsa_port *dp, u8 state, bool do_fast_age)
 {
 	struct dsa_switch *ds = dp->ds;
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 1a59918d3b30..a9fde48cffd4 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -3145,7 +3145,7 @@ static int dsa_slave_netdevice_event(struct notifier_block *nb,
 	case NETDEV_CHANGELOWERSTATE: {
 		struct netdev_notifier_changelowerstate_info *info = ptr;
 		struct dsa_port *dp;
-		int err;
+		int err = 0;
 
 		if (dsa_slave_dev_check(dev)) {
 			dp = dsa_slave_to_port(dev);