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

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Date:   Tue, 14 Feb 2023 10:51:46 -0800
From:   Tony Nguyen <anthony.l.nguyen@...el.com>
To:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        edumazet@...gle.com
Cc:     Jason Xing <kernelxing@...cent.com>, netdev@...r.kernel.org,
        anthony.l.nguyen@...el.com, maciej.fijalkowski@...el.com,
        magnus.karlsson@...el.com, ast@...nel.org, daniel@...earbox.net,
        hawk@...nel.org, john.fastabend@...il.com, bpf@...r.kernel.org,
        bjorn@...nel.org, Alexander Duyck <alexanderduyck@...com>,
        Chandan Kumar Rout <chandanx.rout@...el.com>
Subject: [PATCH net 3/3] ixgbe: add double of VLAN header when computing the max MTU

From: Jason Xing <kernelxing@...cent.com>

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 <kernelxing@...cent.com>
Reviewed-by: Alexander Duyck <alexanderduyck@...com>
Tested-by: Chandan Kumar Rout <chandanx.rout@...el.com> (A Contingent Worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 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 25ca329f7d3c..4507fba8747a 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");
-- 
2.38.1