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-rw-r--r--Documentation/networking/ip-sysctl.txt10
-rw-r--r--include/net/netns/ipv4.h3
-rw-r--r--net/ipv4/fib_semantics.c34
-rw-r--r--net/ipv4/sysctl_net_ipv4.c11
4 files changed, 53 insertions, 5 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index b183e2b..6c7f365b 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -63,6 +63,16 @@ fwmark_reflect - BOOLEAN
fwmark of the packet they are replying to.
Default: 0
+fib_multipath_use_neigh - BOOLEAN
+ Use status of existing neighbor entry when determining nexthop for
+ multipath routes. If disabled, neighbor information is not used and
+ packets could be directed to a failed nexthop. Only valid for kernels
+ built with CONFIG_IP_ROUTE_MULTIPATH enabled.
+ Default: 0 (disabled)
+ Possible values:
+ 0 - disabled
+ 1 - enabled
+
route/max_size - INTEGER
Maximum number of routes allowed in the kernel. Increase
this when using large numbers of interfaces and/or routes.
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index a69cde3..d061ffe 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -133,6 +133,9 @@ struct netns_ipv4 {
struct fib_rules_ops *mr_rules_ops;
#endif
#endif
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+ int sysctl_fib_multipath_use_neigh;
+#endif
atomic_t rt_genid;
};
#endif
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index d97268e..ab64d9f 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1559,21 +1559,45 @@ int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
}
#ifdef CONFIG_IP_ROUTE_MULTIPATH
+static bool fib_good_nh(const struct fib_nh *nh)
+{
+ int state = NUD_REACHABLE;
+
+ if (nh->nh_scope == RT_SCOPE_LINK) {
+ struct neighbour *n;
+
+ rcu_read_lock_bh();
+
+ n = __ipv4_neigh_lookup_noref(nh->nh_dev, nh->nh_gw);
+ if (n)
+ state = n->nud_state;
+
+ rcu_read_unlock_bh();
+ }
+
+ return !!(state & NUD_VALID);
+}
void fib_select_multipath(struct fib_result *res, int hash)
{
struct fib_info *fi = res->fi;
+ struct net *net = fi->fib_net;
+ bool first = false;
for_nexthops(fi) {
if (hash > atomic_read(&nh->nh_upper_bound))
continue;
- res->nh_sel = nhsel;
- return;
+ if (!net->ipv4.sysctl_fib_multipath_use_neigh ||
+ fib_good_nh(nh)) {
+ res->nh_sel = nhsel;
+ return;
+ }
+ if (!first) {
+ res->nh_sel = nhsel;
+ first = true;
+ }
} endfor_nexthops(fi);
-
- /* Race condition: route has just become dead. */
- res->nh_sel = 0;
}
#endif
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 1e1fe60..bb04195 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -960,6 +960,17 @@ static struct ctl_table ipv4_net_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+ {
+ .procname = "fib_multipath_use_neigh",
+ .data = &init_net.ipv4.sysctl_fib_multipath_use_neigh,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &one,
+ },
+#endif
{ }
};
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