[SKB]: Introduce skb_queue_walk_safe()

This patch provides a method for walking skb lists while inserting or
removing skbs from the list.

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -1471,6 +1471,11 @@ static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
 		     prefetch(skb->next), (skb != (struct sk_buff *)(queue));	\
 		     skb = skb->next)
 
+#define skb_queue_walk_safe(queue, skb, tmp)					\
+		for (skb = (queue)->next, tmp = skb->next;			\
+		     skb != (struct sk_buff *)(queue);				\
+		     skb = tmp, tmp = skb->next)
+
 #define skb_queue_reverse_walk(queue, skb) \
 		for (skb = (queue)->prev;					\
 		     prefetch(skb->prev), (skb != (struct sk_buff *)(queue));	\