[PATCH] fragment: add fast path

* [PATCH] fragment: add fast path
@ 2010-06-13 23:16 Changli Gao
  2010-06-14  1:18 ` David Miller
  2010-06-14  5:35 ` Eric Dumazet
  0 siblings, 2 replies; 13+ messages in thread
From: Changli Gao @ 2010-06-13 23:16 UTC (permalink / raw)
  To: David S. Miller
  Cc: Alexey Kuznetsov, Pekka Savola (ipv6),
	James Morris, Hideaki YOSHIFUJI, Patrick McHardy, netdev,
	Changli Gao

add fast path

As the fragments are usually in order, it is likely the new fragments are
at the end of the inet_frag_queue. In the fast path, we check if the skb at the
end of the inet_frag_queue is the prev we expect.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
----
 include/net/inet_frag.h |    1 +
 net/ipv4/ip_fragment.c  |   17 +++++++++++++++++
 net/ipv6/reassembly.c   |   16 ++++++++++++++++
 3 files changed, 34 insertions(+)

diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index 39f2dc9..16ff29a 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -20,6 +20,7 @@ struct inet_frag_queue {
 	atomic_t		refcnt;
 	struct timer_list	timer;      /* when will this queue expire? */
 	struct sk_buff		*fragments; /* list of received fragments */
+	struct sk_buff		*fragments_tail;
 	ktime_t			stamp;
 	int			len;        /* total length of orig datagram */
 	int			meat;
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 75347ea..d8c36d4 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -317,6 +317,7 @@ static int ip_frag_reinit(struct ipq *qp)
 	qp->q.len = 0;
 	qp->q.meat = 0;
 	qp->q.fragments = NULL;
+	qp->q.fragments_tail = NULL;
 	qp->iif = 0;
 
 	return 0;
@@ -389,6 +390,16 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 	 * in the chain of fragments so far.  We must know where to put
 	 * this fragment, right?
 	 */
+	prev = qp->q.fragments_tail;
+	if (prev) {
+		if (FRAG_CB(prev)->offset < offset) {
+			next = NULL;
+			goto found;
+		}
+	} else {
+		next = NULL;
+		goto found;
+	}
 	prev = NULL;
 	for (next = qp->q.fragments; next != NULL; next = next->next) {
 		if (FRAG_CB(next)->offset >= offset)
@@ -396,6 +407,7 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 		prev = next;
 	}
 
+found:
 	/* We found where to put this one.  Check for overlap with
 	 * preceding fragment, and, if needed, align things so that
 	 * any overlaps are eliminated.
@@ -454,6 +466,8 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 
 	/* Insert this fragment in the chain of fragments. */
 	skb->next = next;
+	if (!next)
+		qp->q.fragments_tail = skb;
 	if (prev)
 		prev->next = skb;
 	else
@@ -507,6 +521,8 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
 			goto out_nomem;
 
 		fp->next = head->next;
+		if (!fp->next)
+			qp->q.fragments_tail = fp;
 		prev->next = fp;
 
 		skb_morph(head, qp->q.fragments);
@@ -578,6 +594,7 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
 	iph->tot_len = htons(len);
 	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS);
 	qp->q.fragments = NULL;
+	qp->q.fragments_tail = NULL;
 	return 0;
 
 out_nomem:
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 6d4292f..dc15624 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -336,6 +336,16 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 	 * in the chain of fragments so far.  We must know where to put
 	 * this fragment, right?
 	 */
+	prev = fq->q.fragments_tail;
+	if (prev) {
+		if (FRAG6_CB(prev)->offset < offset) {
+			next = NULL;
+			goto found;
+		}
+	} else {
+		next = NULL;
+		goto found;
+	}
 	prev = NULL;
 	for(next = fq->q.fragments; next != NULL; next = next->next) {
 		if (FRAG6_CB(next)->offset >= offset)
@@ -343,6 +353,7 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 		prev = next;
 	}
 
+found:
 	/* We found where to put this one.  Check for overlap with
 	 * preceding fragment, and, if needed, align things so that
 	 * any overlaps are eliminated.
@@ -400,6 +411,8 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
 
 	/* Insert this fragment in the chain of fragments. */
 	skb->next = next;
+	if (!next)
+		fq->q.fragments_tail = skb;
 	if (prev)
 		prev->next = skb;
 	else
@@ -466,6 +479,8 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 			goto out_oom;
 
 		fp->next = head->next;
+		if (!fp->next)
+			fq->q.fragments_tail = fp;
 		prev->next = fp;
 
 		skb_morph(head, fq->q.fragments);
@@ -553,6 +568,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
 	IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
 	rcu_read_unlock();
 	fq->q.fragments = NULL;
+	fq->q.fragments_tail = NULL;
 	return 1;
 
 out_oversize:

^ permalink raw reply related	[flat|nested] 13+ messages in thread