1 files changed, 15 insertions, 3 deletions

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 72607174ea5a..bcf02f608cbf 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -166,9 +166,21 @@ static ssize_t show_duplex(struct device *dev,
 
         if (netif_running(netdev)) {
                 struct ethtool_cmd cmd;
-                if (!__ethtool_get_settings(netdev, &cmd))
-                        ret = sprintf(buf, "%s\n",
-                                      cmd.duplex ? "full" : "half");
+                if (!__ethtool_get_settings(netdev, &cmd)) {
+                        const char *duplex;
+                        switch (cmd.duplex) {
+                        case DUPLEX_HALF:
+                                duplex = "half";
+                                break;
+                        case DUPLEX_FULL:
+                                duplex = "full";
+                                break;
+                        default:
+                                duplex = "unknown";
+                                break;
+                        }
+                        ret = sprintf(buf, "%s\n", duplex);
+                }
         }
         rtnl_unlock();
         return ret;