netdev - [PATCH net-next v2 4/4] ibmvnic: Handle TSO backing device errata

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Date:   Mon, 12 Mar 2018 11:51:05 -0500
From:   Thomas Falcon <tlfalcon@...ux.vnet.ibm.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, jallen@...ux.vnet.ibm.com,
        nfont@...ux.vnet.ibm.com,
        Thomas Falcon <tlfalcon@...ux.vnet.ibm.com>
Subject: [PATCH net-next v2 4/4] ibmvnic: Handle TSO backing device errata

TSO packets with one segment or with an MSS less than 224 can
cause errors on some backing devices, so disable GSO in those cases.

Signed-off-by: Thomas Falcon <tlfalcon@...ux.vnet.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 7ed87fb..e02d3b9 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -2049,6 +2049,23 @@ static int ibmvnic_change_mtu(struct net_device *netdev, int new_mtu)
 	return wait_for_reset(adapter);
 }
 
+static netdev_features_t ibmvnic_features_check(struct sk_buff *skb,
+						struct net_device *dev,
+						netdev_features_t features)
+{
+	/* Some backing hardware adapters can not
+	 * handle packets with a MSS less than 224
+	 * or with only one segment.
+	 */
+	if (skb_is_gso(skb)) {
+		if (skb_shinfo(skb)->gso_size < 224 ||
+		    skb_shinfo(skb)->gso_segs == 1)
+			features &= ~NETIF_F_GSO_MASK;
+	}
+
+	return features;
+}
+
 static const struct net_device_ops ibmvnic_netdev_ops = {
 	.ndo_open		= ibmvnic_open,
 	.ndo_stop		= ibmvnic_close,
@@ -2061,6 +2078,7 @@ static const struct net_device_ops ibmvnic_netdev_ops = {
 	.ndo_poll_controller	= ibmvnic_netpoll_controller,
 #endif
 	.ndo_change_mtu		= ibmvnic_change_mtu,
+	.ndo_features_check     = ibmvnic_features_check,
 };
 
 /* ethtool functions */
-- 
2.7.5