[PATCH NET v3 7/7] bpf: use skb_expand_head in bpf_out_neigh_v4/6

[Vasily Averin <vvs@virtuozzo.com>]

Unlike skb_realloc_headroom, new helper skb_expand_head
does not allocate a new skb if possible.

Additionally this patch replaces commonly used dereferencing with variables.

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
---
 net/core/filter.c | 27 +++++----------------------
 1 file changed, 5 insertions(+), 22 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index d70187c..9c2f434 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2179,17 +2179,9 @@ static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb,
 	skb->tstamp = 0;
 
 	if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
-		struct sk_buff *skb2;
-
-		skb2 = skb_realloc_headroom(skb, hh_len);
-		if (unlikely(!skb2)) {
-			kfree_skb(skb);
+		skb = skb_expand_head(skb, hh_len);
+		if (!skb)
 			return -ENOMEM;
-		}
-		if (skb->sk)
-			skb_set_owner_w(skb2, skb->sk);
-		consume_skb(skb);
-		skb = skb2;
 	}
 
 	rcu_read_lock_bh();
@@ -2213,8 +2205,7 @@ static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb,
 	}
 	rcu_read_unlock_bh();
 	if (dst)
-		IP6_INC_STATS(dev_net(dst->dev),
-			      ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
+		IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
 out_drop:
 	kfree_skb(skb);
 	return -ENETDOWN;
@@ -2286,17 +2277,9 @@ static int bpf_out_neigh_v4(struct net *net, struct sk_buff *skb,
 	skb->tstamp = 0;
 
 	if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
-		struct sk_buff *skb2;
-
-		skb2 = skb_realloc_headroom(skb, hh_len);
-		if (unlikely(!skb2)) {
-			kfree_skb(skb);
+		skb = skb_expand_head(skb, hh_len);
+		if (!skb)
 			return -ENOMEM;
-		}
-		if (skb->sk)
-			skb_set_owner_w(skb2, skb->sk);
-		consume_skb(skb);
-		skb = skb2;
 	}
 
 	rcu_read_lock_bh();
-- 
1.8.3.1