net: Add and use skb_mark_not_on_list().
An SKB is not on a list if skb->next is NULL.
Codify this convention into a helper function and use it
where we are dequeueing an SKB and need to mark it as such.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index 45ba07a..2d42cb0 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -189,7 +189,7 @@ static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb
struct sk_buff *nskb = segs->next;
int err;
- segs->next = NULL;
+ skb_mark_not_on_list(segs);
err = xfrm_output2(net, sk, segs);
if (unlikely(err)) {