[PATCH net-next] ethtool: reset #lanes when lanes is omitted

[Andy Roulin <aroulin@nvidia.com>]

If the number of lanes was forced and then subsequently the user
omits this parameter, the ksettings->lanes is reset. The driver
should then reset the number of lanes to the device's default
for the specified speed.

However, although the ksettings->lanes is set to 0, the mod variable
is not set to true to indicate the driver and userspace should be
notified of the changes.

Fixes: 012ce4dd3102 ("ethtool: Extend link modes settings uAPI with lanes")
Signed-off-by: Andy Roulin <aroulin@nvidia.com>
Reviewed-by: Danielle Ratson <danieller@nvidia.com>
---
 net/ethtool/linkmodes.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/ethtool/linkmodes.c b/net/ethtool/linkmodes.c
index fab66c169b9f..20165e07ef90 100644
--- a/net/ethtool/linkmodes.c
+++ b/net/ethtool/linkmodes.c
@@ -270,11 +270,12 @@ static int ethnl_update_linkmodes(struct genl_info *info, struct nlattr **tb,
 					    "lanes configuration not supported by device");
 			return -EOPNOTSUPP;
 		}
-	} else if (!lsettings->autoneg) {
-		/* If autoneg is off and lanes parameter is not passed from user,
-		 * set the lanes parameter to 0.
+	} else if (!lsettings->autoneg && ksettings->lanes) {
+		/* If autoneg is off and lanes parameter is not passed from user but
+		 * it was defined previously then set the lanes parameter to 0.
 		 */
 		ksettings->lanes = 0;
+		*mod = true;
 	}
 
 	ret = ethnl_update_bitset(ksettings->link_modes.advertising,
-- 
2.20.1