Re: [PATCH net 3/5] fm10k: Implement ndo_gso_check()

On Wed, Nov 05, 2014 at 06:54:00PM -0800, Alexander Duyck wrote:

On 11/04/2014 01:56 PM, Joe Stringer wrote:

quoted

ndo_gso_check() was recently introduced to allow NICs to report the
offloading support that they have on a per-skb basis. Add an
implementation for this driver which checks for something that looks
like VXLAN.

Implementation shamelessly stolen from Tom Herbert:
http://thread.gmane.org/gmane.linux.network/332428/focus=333111

Signed-off-by: Joe Stringer <redacted>
---
Should this driver report support for GSO on packets with tunnel headers
up to 64B like the i40e driver does?
---
 drivers/net/ethernet/intel/fm10k/fm10k_netdev.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c b/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c
index 8811364..b9ef622 100644
--- a/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c
+++ b/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c

@@ -1350,6 +1350,17 @@ static void fm10k_dfwd_del_station(struct net_device *dev, void *priv)
 	}
 }
 
+static bool fm10k_gso_check(struct sk_buff *skb, struct net_device *dev)
+{
+	if ((skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL) &&
+	    (skb->inner_protocol_type != ENCAP_TYPE_ETHER ||
+	     skb->inner_protocol != htons(ETH_P_TEB) ||
+	     skb_inner_mac_header(skb) - skb_transport_header(skb) != 16))
+		return false;
+
+	return true;
+}
+
 static const struct net_device_ops fm10k_netdev_ops = {
 	.ndo_open		= fm10k_open,
 	.ndo_stop		= fm10k_close,

@@ -1372,6 +1383,7 @@ static const struct net_device_ops fm10k_netdev_ops = {
 	.ndo_do_ioctl		= fm10k_ioctl,
 	.ndo_dfwd_add_station	= fm10k_dfwd_add_station,
 	.ndo_dfwd_del_station	= fm10k_dfwd_del_station,
+	.ndo_gso_check		= fm10k_gso_check,
 };
 
 #define DEFAULT_DEBUG_LEVEL_SHIFT 3

I'm thinking this check is far too simplistic.  If you look the fm10k
driver already has fm10k_tx_encap_offload() in the TSO function for
verifying if it can support offloading tunnels or not.  I would
recommend starting there or possibly even just adapting that function to
suit your purpose.

Thanks,

Alex

Would it be enough to just call fm10k_tx_encap_offload() in a way that echoes fm10k_tso()?

+static bool fm10k_gso_check(struct sk_buff *skb, struct net_device *dev)
+{
+       if (skb->encapsulation && !fm10k_tx_encap_offload(skb))
+               return false;
+
+       return true;
+}

Thanks,
Joe