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>
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 68cee35..dd57f48 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1857,6 +1857,28 @@
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 @@
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