igb: Update MTU so that it is always at least a standard frame size

This change makes it so that we limit the lower bound for max_frame_size to
the size of a standard Ethernet frame.  This allows for feature parity with
other Intel based drivers such as ixgbe.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 94295a06c124..1a0137d68109 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -4813,6 +4813,10 @@ static int igb_change_mtu(struct net_device *netdev, int new_mtu)
                 return -EINVAL;
         }
 
+        /* adjust max frame to be at least the size of a standard frame */
+        if (max_frame < (ETH_FRAME_LEN + ETH_FCS_LEN))
+                max_frame = ETH_FRAME_LEN + ETH_FCS_LEN;
+
         while (test_and_set_bit(__IGB_RESETTING, &adapter->state))
                 msleep(1);