From: Vasily Averin <vvs@virtuozzo.com>
Date: Mon, 2 Aug 2021 11:52:54 +0300
Subject: bpf: use skb_expand_head in bpf_out_neigh_v4/6
Patch-mainline: v5.15-rc1
Git-commit: a1e975e117ad657dedafed2ab64ce4ddccc9883b
References: jsc#PED-1377

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
 net/core/filter.c |   27 +++++----------------------
 1 file changed, 5 insertions(+), 22 deletions(-)

--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2180,17 +2180,9 @@ static int bpf_out_neigh_v6(struct net *
 	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();
@@ -2214,8 +2206,7 @@ static int bpf_out_neigh_v6(struct net *
 	}
 	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;
@@ -2287,17 +2278,9 @@ static int bpf_out_neigh_v4(struct net *
 	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();