nexthop: Allow setting "offload" and "trap" indications on nexthops

Add a function that can be called by device drivers to set "offload" or
"trap" indication on nexthops following nexthop notifications.

Changes since RFC:
* s/nexthop_hw_flags_set/nexthop_set_hw_flags/
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/nexthop.h

@@ -145,6 +145,7 @@ struct nh_notifier_info {
 
 int register_nexthop_notifier(struct net *net, struct notifier_block *nb);
 int unregister_nexthop_notifier(struct net *net, struct notifier_block *nb);
+void nexthop_set_hw_flags(struct net *net, u32 id, bool offload, bool trap);
 
 /* caller is holding rcu or rtnl; no reference taken to nexthop */
 struct nexthop *nexthop_find_by_id(struct net *net, u32 id);

net/ipv4/nexthop.c

@@ -2081,6 +2081,27 @@ int unregister_nexthop_notifier(struct net *net, struct notifier_block *nb)
 }
 EXPORT_SYMBOL(unregister_nexthop_notifier);
 
+void nexthop_set_hw_flags(struct net *net, u32 id, bool offload, bool trap)
+{
+	struct nexthop *nexthop;
+
+	rcu_read_lock();
+
+	nexthop = nexthop_find_by_id(net, id);
+	if (!nexthop)
+		goto out;
+
+	nexthop->nh_flags &= ~(RTNH_F_OFFLOAD | RTNH_F_TRAP);
+	if (offload)
+		nexthop->nh_flags |= RTNH_F_OFFLOAD;
+	if (trap)
+		nexthop->nh_flags |= RTNH_F_TRAP;
+
+out:
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL(nexthop_set_hw_flags);
+
 static void __net_exit nexthop_net_exit(struct net *net)
 {
 	rtnl_lock();