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Commit 219badfa authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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ipv6: frags: get rid of ip6frag_skb_cb/FRAG6_CB 



ip6_frag_queue uses skb->cb[] to store the fragment offset, meaning that
we could use two cache lines per skb when finding the insertion point,
if for some reason inet6_skb_parm size is increased in the future.

By using skb->ip_defrag_offset instead of skb->cb[], we pack all
the fields in a single cache line, matching what we did for IPv4.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bf663371

net/ipv6/reassembly.c

+12 −18
Original line number Diff line number Diff line
@@ -62,13 +62,6 @@ 


static const char ip6_frag_cache_name[] = "ip6-frags";



struct ip6frag_skb_cb {

	struct inet6_skb_parm	h;

	int			offset;

};



#define FRAG6_CB(skb)	((struct ip6frag_skb_cb *)((skb)->cb))



static u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h)

{

	return 1 << (ipv6_get_dsfield(ipv6h) & INET_ECN_MASK);
@@ -250,13 +243,13 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb, 
	 * this fragment, right?

	 */

	prev = fq->q.fragments_tail;

	if (!prev || FRAG6_CB(prev)->offset < offset) {

	if (!prev || prev->ip_defrag_offset < offset) {

		next = NULL;

		goto found;

	}

	prev = NULL;

	for (next = fq->q.fragments; next != NULL; next = next->next) {

		if (FRAG6_CB(next)->offset >= offset)

		if (next->ip_defrag_offset >= offset)

			break;	/* bingo! */

		prev = next;

	}
@@ -271,14 +264,20 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb, 


	/* Check for overlap with preceding fragment. */

	if (prev &&

	    (FRAG6_CB(prev)->offset + prev->len) > offset)

	    (prev->ip_defrag_offset + prev->len) > offset)

		goto discard_fq;



	/* Look for overlap with succeeding segment. */

	if (next && FRAG6_CB(next)->offset < end)

	if (next && next->ip_defrag_offset < end)

		goto discard_fq;



	FRAG6_CB(skb)->offset = offset;

	/* Note : skb->ip_defrag_offset and skb->dev share the same location */

	dev = skb->dev;

	if (dev)

		fq->iif = dev->ifindex;

	/* Makes sure compiler wont do silly aliasing games */

	barrier();

	skb->ip_defrag_offset = offset;



	/* Insert this fragment in the chain of fragments. */

	skb->next = next;
@@ -289,11 +288,6 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb, 
	else

		fq->q.fragments = skb;



	dev = skb->dev;

	if (dev) {

		fq->iif = dev->ifindex;

		skb->dev = NULL;

	}

	fq->q.stamp = skb->tstamp;

	fq->q.meat += skb->len;

	fq->ecn |= ecn;
@@ -380,7 +374,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev, 
	}



	WARN_ON(head == NULL);

	WARN_ON(FRAG6_CB(head)->offset != 0);

	WARN_ON(head->ip_defrag_offset != 0);



	/* Unfragmented part is taken from the first segment. */

	payload_len = ((head->data - skb_network_header(head)) -