From a4daad6b0923030fbd3b00a01f570e4c3eef446b Mon Sep 17 00:00:00 2001
From: "David S. Miller" <davem@davemloft.net>
Date: Thu, 27 Jan 2011 22:01:53 -0800
Subject: [PATCH] net: Pre-COW metrics for TCP.
TCP is going to record metrics for the connection,
so pre-COW the route metrics at route cache entry
creation time.
This avoids several atomic operations that have to
occur if we COW the metrics after the entry reaches
global visibility.
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/net/flow.h | 3 ++-
include/net/inet_sock.h | 8 +++++++-
include/net/route.h | 4 ++++
net/ipv4/route.c | 26 +++++++++++++++++++++++---
4 files changed, 36 insertions(+), 5 deletions(-)
diff --git a/include/net/flow.h b/include/net/flow.h
index 240b7f356c7105..1ae901f2443684 100644
--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -48,7 +48,8 @@ struct flowi {
__u8 proto;
__u8 flags;
-#define FLOWI_FLAG_ANYSRC 0x01
+#define FLOWI_FLAG_ANYSRC 0x01
+#define FLOWI_FLAG_PRECOW_METRICS 0x02
union {
struct {
__be16 sport;
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 8181498fa96ca5..6e6dfd7576827c 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -219,7 +219,13 @@ static inline struct request_sock *inet_reqsk_alloc(struct request_sock_ops *ops
static inline __u8 inet_sk_flowi_flags(const struct sock *sk)
{
- return inet_sk(sk)->transparent ? FLOWI_FLAG_ANYSRC : 0;
+ __u8 flags = 0;
+
+ if (inet_sk(sk)->transparent)
+ flags |= FLOWI_FLAG_ANYSRC;
+ if (sk->sk_protocol == IPPROTO_TCP)
+ flags |= FLOWI_FLAG_PRECOW_METRICS;
+ return flags;
}
#endif /* _INET_SOCK_H */
diff --git a/include/net/route.h b/include/net/route.h
index 5677cbf0c6e659..e5864658dc76a2 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -182,6 +182,8 @@ static inline int ip_route_connect(struct rtable **rp, __be32 dst,
if (inet_sk(sk)->transparent)
fl.flags |= FLOWI_FLAG_ANYSRC;
+ if (protocol == IPPROTO_TCP)
+ fl.flags |= FLOWI_FLAG_PRECOW_METRICS;
if (!dst || !src) {
err = __ip_route_output_key(net, rp, &fl);
@@ -209,6 +211,8 @@ static inline int ip_route_newports(struct rtable **rp, u8 protocol,
fl.proto = protocol;
if (inet_sk(sk)->transparent)
fl.flags |= FLOWI_FLAG_ANYSRC;
+ if (protocol == IPPROTO_TCP)
+ fl.flags |= FLOWI_FLAG_PRECOW_METRICS;
ip_rt_put(*rp);
*rp = NULL;
security_sk_classify_flow(sk, &fl);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 68cee358d9a38a..dd57f489673611 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1857,6 +1857,28 @@ static unsigned int ipv4_default_mtu(const struct dst_entry *dst)
return mtu;
}
+static void rt_init_metrics(struct rtable *rt, struct fib_info *fi)
+{
+ if (!(rt->fl.flags & FLOWI_FLAG_PRECOW_METRICS)) {
+ no_cow:
+ rt->fi = fi;
+ atomic_inc(&fi->fib_clntref);
+ dst_init_metrics(&rt->dst, fi->fib_metrics, true);
+ } else {
+ struct inet_peer *peer;
+
+ if (!rt->peer)
+ rt_bind_peer(rt, 1);
+ peer = rt->peer;
+ if (!peer)
+ goto no_cow;
+ if (inet_metrics_new(peer))
+ memcpy(peer->metrics, fi->fib_metrics,
+ sizeof(u32) * RTAX_MAX);
+ dst_init_metrics(&rt->dst, peer->metrics, false);
+ }
+}
+
static void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag)
{
struct dst_entry *dst = &rt->dst;
@@ -1866,9 +1888,7 @@ static void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag)
if (FIB_RES_GW(*res) &&
FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK)
rt->rt_gateway = FIB_RES_GW(*res);
- rt->fi = fi;
- atomic_inc(&fi->fib_clntref);
- dst_init_metrics(dst, fi->fib_metrics, true);
+ rt_init_metrics(rt, fi);
#ifdef CONFIG_IP_ROUTE_CLASSID
dst->tclassid = FIB_RES_NH(*res).nh_tclassid;
#endif
--
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