[PATCH] bonding: allow TSO being set on bonding master

[Eric Dumazet <eric.dumazet@gmail.com>]

From: Eric Dumazet <edumazet@google.com>

In some situations, we need to disable TSO on bonding slaves.

bonding device automatically unset TSO in bond_fix_features(), and
performance is not good because :

1) We consume more cpu cycles.

2) GSO segmentation has some bugs leading to out of order TCP packets
if this segmentation is done before virtual device. This particular
problem will be addressed in a separate patch.

This patch allows TSO being set/unset on the bonding master,
so that GSO segmentation is done after bonding layer.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
---
 drivers/net/bonding/bond_main.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index d0aade0..b429bb8 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1362,6 +1362,11 @@ static netdev_features_t bond_fix_features(struct net_device *dev,
 						     slave->dev->features,
 						     mask);
 	}
+	/* Allow TSO being used on bonding device :
+	 * Performing the GSO segmentation after bonding transmit
+	 * is a performance improvement.
+	 */
+	features |= mask & NETIF_F_ALL_TSO;
 
 out:
 	read_unlock(&bond->lock);