net: remove netdevice gso_min_segs

After introduction of ndo_features_check(), we believe that very
specific checks for rare features should not be done in core
networking stack.

No driver uses gso_min_segs yet, so we revert this feature and save
few instructions per tx packet in fast path.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -1586,8 +1586,6 @@ enum netdev_priv_flags {
  *	@gso_max_size:	Maximum size of generic segmentation offload
  *	@gso_max_segs:	Maximum number of segments that can be passed to the
  *			NIC for GSO
- *	@gso_min_segs:	Minimum number of segments that can be passed to the
- *			NIC for GSO
  *
  *	@dcbnl_ops:	Data Center Bridging netlink ops
  *	@num_tc:	Number of traffic classes in the net device
@@ -1858,7 +1856,7 @@ struct net_device {
 	unsigned int		gso_max_size;
 #define GSO_MAX_SEGS		65535
 	u16			gso_max_segs;
-	u16			gso_min_segs;
+
 #ifdef CONFIG_DCB
 	const struct dcbnl_rtnl_ops *dcbnl_ops;
 #endif

net/core/dev.c

@@ -2831,7 +2831,7 @@ netdev_features_t netif_skb_features(struct sk_buff *skb)
 	netdev_features_t features = dev->features;
 	u16 gso_segs = skb_shinfo(skb)->gso_segs;
 
-	if (gso_segs > dev->gso_max_segs || gso_segs < dev->gso_min_segs)
+	if (gso_segs > dev->gso_max_segs)
 		features &= ~NETIF_F_GSO_MASK;
 
 	/* If encapsulation offload request, verify we are testing
@@ -7429,7 +7429,6 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
 
 	dev->gso_max_size = GSO_MAX_SIZE;
 	dev->gso_max_segs = GSO_MAX_SEGS;
-	dev->gso_min_segs = 0;
 
 	INIT_LIST_HEAD(&dev->napi_list);
 	INIT_LIST_HEAD(&dev->unreg_list);