nexthop: Emit a notification when a single nexthop is replaced

The notification is emitted after all the validation checks were
performed, but before the new configuration (i.e., 'struct nh_info') is
pointed at by the old shell (i.e., 'struct nexthop'). This prevents the
need to perform rollback in case the notification is vetoed.

The next patch will also emit a replace notification for all the nexthop
groups in which the nexthop is used.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 3f43693..11bfb1e 100644 (file)
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -1100,12 +1100,22 @@ static int replace_nexthop_single(struct net *net, struct nexthop *old,
                                  struct netlink_ext_ack *extack)
 {
        struct nh_info *oldi, *newi;
+       int err;
 
        if (new->is_group) {
                NL_SET_ERR_MSG(extack, "Can not replace a nexthop with a nexthop group.");
                return -EINVAL;
        }
 
+       err = call_nexthop_notifiers(net, NEXTHOP_EVENT_REPLACE, new, extack);
+       if (err)
+               return err;
+
+       /* Hardware flags were set on 'old' as 'new' is not in the red-black
+        * tree. Therefore, inherit the flags from 'old' to 'new'.
+        */
+       new->nh_flags |= old->nh_flags & (RTNH_F_OFFLOAD | RTNH_F_TRAP);
+
        oldi = rtnl_dereference(old->nh_info);
        newi = rtnl_dereference(new->nh_info);