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Commit bec3cfdc authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: skb_segment() provides list head and tail 



Its unfortunate we have to walk again skb list to find the tail
after segmentation, even if data is probably hot in cpu caches.

skb_segment() can store the tail of the list into segs->prev,
and validate_xmit_skb_list() can immediately get the tail.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 45d9cc7c

net/core/dev.c

+15 −12
Original line number Original line Diff line number Diff line
@@ -2724,22 +2724,25 @@ struct sk_buff *validate_xmit_skb_list(struct sk_buff *skb, struct net_device *d 
{

{

	struct sk_buff *next, *head = NULL, *tail;

	struct sk_buff *next, *head = NULL, *tail;





	while (skb) {

	for (; skb != NULL; skb = next) {

		next = skb->next;

		next = skb->next;

		skb->next = NULL;

		skb->next = NULL;



		/* in case skb wont be segmented, point to itself */

		skb->prev = skb;



		skb = validate_xmit_skb(skb, dev);

		skb = validate_xmit_skb(skb, dev);

		if (skb) {

		if (!skb)

			struct sk_buff *end = skb;

			continue;





			while (end->next)

				end = end->next;

		if (!head)

		if (!head)

			head = skb;

			head = skb;

		else

		else

			tail->next = skb;

			tail->next = skb;

			tail = end;

		/* If skb was segmented, skb->prev points to

		}

		 * the last segment. If not, it still contains skb.

		skb = next;

		 */

		tail = skb->prev;

	}

	}

	return head;

	return head;

}

}

net/core/skbuff.c

+5 −0
Original line number Original line Diff line number Diff line
@@ -3083,6 +3083,11 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, 
		}

		}

	} while ((offset += len) < head_skb->len);

	} while ((offset += len) < head_skb->len);





	/* Some callers want to get the end of the list.

	 * Put it in segs->prev to avoid walking the list.

	 * (see validate_xmit_skb_list() for example)

	 */

	segs->prev = tail;

	return segs;

	return segs;





err:

err: