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fragment: add fast path for in-order fragments

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add fast path for in-order fragments

As the fragments are sent in order in most of OSes, such as Windows, Darwin and
FreeBSD, 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  |   12 ++++++++++++
 net/ipv6/reassembly.c   |   11 +++++++++++
 3 files changed, 24 insertions(+)
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Changli Gao 2010-06-29 04:39:37 +00:00 committed by David S. Miller
parent 4ce3c183fc
commit d6bebca92c
3 changed files with 24 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/inet_frag.h
View File

@ -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;

12
net/ipv4/ip_fragment.c
View File

@ -314,6 +314,7 @@ 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;
@ -386,6 +387,11 @@ 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 || FRAG_CB(prev)->offset < offset) {
next = NULL;
goto found;
}
prev = NULL;
for (next = qp->q.fragments; next != NULL; next = next->next) {
if (FRAG_CB(next)->offset >= offset)
@ -393,6 +399,7 @@ 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.
@ -451,6 +458,8 @@ 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
@ -504,6 +513,8 @@ 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);
@ -574,6 +585,7 @@ 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:

11
net/ipv6/reassembly.c
View File

@ -333,6 +333,11 @@ 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 || FRAG6_CB(prev)->offset < offset) {
next = NULL;
goto found;
}
prev = NULL;
for(next = fq->q.fragments; next != NULL; next = next->next) {
if (FRAG6_CB(next)->offset >= offset)
@ -340,6 +345,7 @@ 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.
@ -397,6 +403,8 @@ 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
@ -463,6 +471,8 @@ 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);
@ -549,6 +559,7 @@ 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: