skbuff: add check for non-linear to warn_if_lro and needs_linearize

We can avoid an unecessary cache miss by checking if the skb is non-linear
before accessing gso_size/gso_type in skb_warn_if_lro, the same can also be
done to avoid a cache miss on nr_frags if data_len is 0.
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -2129,7 +2129,8 @@ static inline bool skb_warn_if_lro(const struct sk_buff *skb)
 	/* LRO sets gso_size but not gso_type, whereas if GSO is really
 	 * wanted then gso_type will be set. */
 	struct skb_shared_info *shinfo = skb_shinfo(skb);
-	if (shinfo->gso_size != 0 && unlikely(shinfo->gso_type == 0)) {
+	if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
+	    unlikely(shinfo->gso_type == 0)) {
 		__skb_warn_lro_forwarding(skb);
 		return true;
 	}

net/core/dev.c

@@ -2103,9 +2103,10 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
 static inline int skb_needs_linearize(struct sk_buff *skb,
 				      struct net_device *dev)
 {
-	return (skb_has_frags(skb) && !(dev->features & NETIF_F_FRAGLIST)) ||
-	       (skb_shinfo(skb)->nr_frags && (!(dev->features & NETIF_F_SG) ||
-					      illegal_highdma(dev, skb)));
+	return skb_is_nonlinear(skb) &&
+	       ((skb_has_frags(skb) && !(dev->features & NETIF_F_FRAGLIST)) ||
+	        (skb_shinfo(skb)->nr_frags && (!(dev->features & NETIF_F_SG) ||
+					      illegal_highdma(dev, skb))));
 }
 
 /**