dsa: slave: Don't reference NULL pointer during phy_disconnect

When the phy is disconnected, the parent pointer to the netdev it was
attached to is set to NULL. The code then tries to suspend the phy,
but dsa_slave_fixed_link_update needs the parent pointer to determine
which switch the phy is connected to. So it dereferenced a NULL
pointer. Check for this condition.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 4 deletions

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 27bf03d11670..49056d90b179 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -896,11 +896,15 @@ static void dsa_slave_adjust_link(struct net_device *dev)
 static int dsa_slave_fixed_link_update(struct net_device *dev,
                                        struct fixed_phy_status *status)
 {
-        struct dsa_slave_priv *p = netdev_priv(dev);
-        struct dsa_switch *ds = p->parent;
+        struct dsa_slave_priv *p;
+        struct dsa_switch *ds;
 
-        if (ds->drv->fixed_link_update)
-                ds->drv->fixed_link_update(ds, p->port, status);
+        if (dev) {
+                p = netdev_priv(dev);
+                ds = p->parent;
+                if (ds->drv->fixed_link_update)
+                        ds->drv->fixed_link_update(ds, p->port, status);
+        }
 
         return 0;
 }