Subject: [PATCH net 3/3] ixgbe: add double of VLAN header when computing the max MTU

From: Jason Xing <[email-masked]>
Date: Sat, 4 Feb 2023 21:35:35 +0800

From: Jason Xing <[email-masked]>

Include the second VLAN HLEN into account when computing the maximum
MTU size as other drivers do.

Fixes: fabf1bce103a ("ixgbe: Prevent unsupported configurations with XDP")
Signed-off-by: Jason Xing <[email-masked]>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe.h      | 2 ++
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 3 +--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
index bc68b8f2176d..8736ca4b2628 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
@@ -73,6 +73,8 @@
 #define IXGBE_RXBUFFER_4K    4096
 #define IXGBE_MAX_RXBUFFER  16384  /* largest size for a single descriptor */
 
+#define IXGBE_PKT_HDR_PAD   (ETH_HLEN + ETH_FCS_LEN + (VLAN_HLEN * 2))
+
 /* Attempt to maximize the headroom available for incoming frames.  We
  * use a 2K buffer for receives and need 1536/1534 to store the data for
  * the frame.  This leaves us with 512 bytes of room.  From that we need
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 2c1b6eb60436..149f7baf40fe 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -6801,8 +6801,7 @@ static int ixgbe_change_mtu(struct net_device *netdev, int new_mtu)
 	struct ixgbe_adapter *adapter = netdev_priv(netdev);
 
 	if (ixgbe_enabled_xdp_adapter(adapter)) {
-		int new_frame_size = new_mtu + ETH_HLEN + ETH_FCS_LEN +
-				     VLAN_HLEN;
+		int new_frame_size = new_mtu + IXGBE_PKT_HDR_PAD;
 
 		if (new_frame_size > ixgbe_max_xdp_frame_size(adapter)) {
 			e_warn(probe, "Requested MTU size is not supported with XDP\n");
-- 
2.37.3