ipv4: Add FLOWI_FLAG_KNOWN_NH
Add flag to request that output route should be
returned with known rt_gateway, in case we want to use
it as nexthop for neighbour resolving.
The returned route can be cached as follows:
- in NH exception: because the cached routes are not shared
with other destinations
- in FIB NH: when using gateway because all destinations for
NH share same gateway
As last option, to return rt_gateway!=0 we have to
set DST_NOCACHE.
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/flow.h b/include/net/flow.h
index e1dd508..628e11b 100644
--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -21,6 +21,7 @@
__u8 flowic_flags;
#define FLOWI_FLAG_ANYSRC 0x01
#define FLOWI_FLAG_CAN_SLEEP 0x02
+#define FLOWI_FLAG_KNOWN_NH 0x04
__u32 flowic_secid;
};
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 3a116cb..1a0da8d 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1762,6 +1762,7 @@
struct in_device *in_dev;
u16 type = res->type;
struct rtable *rth;
+ bool do_cache;
in_dev = __in_dev_get_rcu(dev_out);
if (!in_dev)
@@ -1798,24 +1799,36 @@
}
fnhe = NULL;
+ do_cache = fi != NULL;
if (fi) {
struct rtable __rcu **prth;
+ struct fib_nh *nh = &FIB_RES_NH(*res);
- fnhe = find_exception(&FIB_RES_NH(*res), fl4->daddr);
+ fnhe = find_exception(nh, fl4->daddr);
if (fnhe)
prth = &fnhe->fnhe_rth;
- else
- prth = __this_cpu_ptr(FIB_RES_NH(*res).nh_pcpu_rth_output);
+ else {
+ if (unlikely(fl4->flowi4_flags &
+ FLOWI_FLAG_KNOWN_NH &&
+ !(nh->nh_gw &&
+ nh->nh_scope == RT_SCOPE_LINK))) {
+ do_cache = false;
+ goto add;
+ }
+ prth = __this_cpu_ptr(nh->nh_pcpu_rth_output);
+ }
rth = rcu_dereference(*prth);
if (rt_cache_valid(rth)) {
dst_hold(&rth->dst);
return rth;
}
}
+
+add:
rth = rt_dst_alloc(dev_out,
IN_DEV_CONF_GET(in_dev, NOPOLICY),
IN_DEV_CONF_GET(in_dev, NOXFRM),
- fi);
+ do_cache);
if (!rth)
return ERR_PTR(-ENOBUFS);