Subject: [PATCH 1/1] net: dsa: Fix of kernel panic in case of missing PHY.

From: Andrey Volkov <[email-masked]>
Date: Tue, 09 Dec 2014 18:31:49 +0100

Fix of kernel panic in case of missing PHY.

Signed-off-by: Andrey Volkov <[email-masked]>
---
 net/dsa/slave.c |   19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 528380a..6f89caa 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -512,7 +512,7 @@ static int dsa_slave_fixed_link_update(struct net_device *dev,
 }
 
 /* slave device setup *******************************************************/
-static void dsa_slave_phy_setup(struct dsa_slave_priv *p,
+static int dsa_slave_phy_setup(struct dsa_slave_priv *p,
 				struct net_device *slave_dev)
 {
 	struct dsa_switch *ds = p->parent;
@@ -533,7 +533,7 @@ static void dsa_slave_phy_setup(struct dsa_slave_priv *p,
 		ret = of_phy_register_fixed_link(port_dn);
 		if (ret) {
 			netdev_err(slave_dev, "failed to register fixed PHY\n");
-			return;
+			return ret;
 		}
 		phy_is_fixed = true;
 		phy_dn = port_dn;
@@ -555,12 +555,17 @@ static void dsa_slave_phy_setup(struct dsa_slave_priv *p,
 	 */
 	if (!p->phy) {
 		p->phy = ds->slave_mii_bus->phy_map[p->port];
-		phy_connect_direct(slave_dev, p->phy, dsa_slave_adjust_link,
+		if(p->phy)
+			phy_connect_direct(slave_dev, p->phy, dsa_slave_adjust_link,
 				   p->phy_interface);
+		else
+			return -ENODEV;
+
 	} else {
 		netdev_info(slave_dev, "attached PHY at address %d [%s]\n",
 			    p->phy->addr, p->phy->drv->name);
 	}
+	return 0;
 }
 
 int dsa_slave_suspend(struct net_device *slave_dev)
@@ -653,7 +658,13 @@ dsa_slave_create(struct dsa_switch *ds, struct device *parent,
 	p->old_link = -1;
 	p->old_duplex = -1;
 
-	dsa_slave_phy_setup(p, slave_dev);
+	ret = dsa_slave_phy_setup(p, slave_dev);
+	if (ret) {
+		netdev_err(master, "error %d registering interface %s\n",
+			   ret, slave_dev->name);
+		free_netdev(slave_dev);
+		return NULL;
+	}
 
 	ret = register_netdev(slave_dev);
 	if (ret) {