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authorDavid S. Miller <davem@davemloft.net>2012-06-20 08:22:05 +0400
committerDavid S. Miller <davem@davemloft.net>2012-06-20 08:22:05 +0400
commit41063e9dd11956f2d285e12e4342e1d232ba0ea2 (patch)
treed4df2f51044b4724a4767f0498c3df2f606b5ad7 /net/ipv4/ip_input.c
parentf9242b6b28d61295f2bf7e8adfb1060b382e5381 (diff)
downloadlinux-41063e9dd11956f2d285e12e4342e1d232ba0ea2.tar.xz
ipv4: Early TCP socket demux.
Input packet processing for local sockets involves two major demuxes. One for the route and one for the socket. But we can optimize this down to one demux for certain kinds of local sockets. Currently we only do this for established TCP sockets, but it could at least in theory be expanded to other kinds of connections. If a TCP socket is established then it's identity is fully specified. This means that whatever input route was used during the three-way handshake must work equally well for the rest of the connection since the keys will not change. Once we move to established state, we cache the receive packet's input route to use later. Like the existing cached route in sk->sk_dst_cache used for output packets, we have to check for route invalidations using dst->obsolete and dst->ops->check(). Early demux occurs outside of a socket locked section, so when a route invalidation occurs we defer the fixup of sk->sk_rx_dst until we are actually inside of established state packet processing and thus have the socket locked. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ip_input.c')
-rw-r--r--net/ipv4/ip_input.c39
1 files changed, 26 insertions, 13 deletions
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index c4fe1d271131..93b092c9a394 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -323,19 +323,32 @@ static int ip_rcv_finish(struct sk_buff *skb)
* how the packet travels inside Linux networking.
*/
if (skb_dst(skb) == NULL) {
- int err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
- iph->tos, skb->dev);
- if (unlikely(err)) {
- if (err == -EHOSTUNREACH)
- IP_INC_STATS_BH(dev_net(skb->dev),
- IPSTATS_MIB_INADDRERRORS);
- else if (err == -ENETUNREACH)
- IP_INC_STATS_BH(dev_net(skb->dev),
- IPSTATS_MIB_INNOROUTES);
- else if (err == -EXDEV)
- NET_INC_STATS_BH(dev_net(skb->dev),
- LINUX_MIB_IPRPFILTER);
- goto drop;
+ const struct net_protocol *ipprot;
+ int protocol = iph->protocol;
+ int err;
+
+ rcu_read_lock();
+ ipprot = rcu_dereference(inet_protos[protocol]);
+ err = -ENOENT;
+ if (ipprot && ipprot->early_demux)
+ err = ipprot->early_demux(skb);
+ rcu_read_unlock();
+
+ if (err) {
+ err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
+ iph->tos, skb->dev);
+ if (unlikely(err)) {
+ if (err == -EHOSTUNREACH)
+ IP_INC_STATS_BH(dev_net(skb->dev),
+ IPSTATS_MIB_INADDRERRORS);
+ else if (err == -ENETUNREACH)
+ IP_INC_STATS_BH(dev_net(skb->dev),
+ IPSTATS_MIB_INNOROUTES);
+ else if (err == -EXDEV)
+ NET_INC_STATS_BH(dev_net(skb->dev),
+ LINUX_MIB_IPRPFILTER);
+ goto drop;
+ }
}
}