[PATCH net v2 3/3] ixgbe: add double of VLAN header when computing the max MTU

[PATCH net v2 3/3] ixgbe: add double of VLAN header when computing the max MTU

[Jason Xing]

From: Jason Xing <kernelxing@tencent.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@tencent.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
---
v2: add reviewed-by label.
---
 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");
-- 
2.37.3

RE: [Intel-wired-lan] [PATCH net v2 3/3] ixgbe: add double of VLAN header when computing the max MTU

[Rout, ChandanX]

>-----Original Message-----
>From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of
>Jason Xing
>Sent: 09 February 2023 08:11
>To: alexander.duyck@gmail.com; Brandeburg, Jesse
><jesse.brandeburg@intel.com>; Nguyen, Anthony L
><anthony.l.nguyen@intel.com>; davem@davemloft.net;
>edumazet@google.com; kuba@kernel.org; pabeni@redhat.com;
>richardcochran@gmail.com; ast@kernel.org; daniel@iogearbox.net;
>hawk@kernel.org; john.fastabend@gmail.com; Lobakin, Alexandr
><alexandr.lobakin@intel.com>; Fijalkowski, Maciej
><maciej.fijalkowski@intel.com>
>Cc: kerneljasonxing@gmail.com; netdev@vger.kernel.org; Alexander Duyck
><alexanderduyck@fb.com>; linux-kernel@vger.kernel.org; intel-wired-
>lan@lists.osuosl.org; bpf@vger.kernel.org; Jason Xing
><kernelxing@tencent.com>
>Subject: [Intel-wired-lan] [PATCH net v2 3/3] ixgbe: add double of VLAN
>header when computing the max MTU
>
>From: Jason Xing <kernelxing@tencent.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@tencent.com>
>Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
>---
>v2: add reviewed-by label.
>---
> drivers/net/ethernet/intel/ixgbe/ixgbe.h      | 2 ++
> drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 3 +--
> 2 files changed, 3 insertions(+), 2 deletions(-)
>

Tested-by: Chandan Kumar Rout <chandanx.rout@intel.com> (A Contingent Worker at Intel)