ipvs: avoid kfree_rcu without 2nd arg

Avoid possible synchronize_rcu() as part from the
kfree_rcu() call when 2nd arg is not provided.
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/ip_vs.h

@@ -461,6 +461,7 @@ void ip_vs_stats_free(struct ip_vs_stats *stats);
 
 /* Multiple chains processed in same tick */
 struct ip_vs_est_tick_data {
+	struct rcu_head		rcu_head;
 	struct hlist_head	chains[IPVS_EST_TICK_CHAINS];
 	DECLARE_BITMAP(present, IPVS_EST_TICK_CHAINS);
 	DECLARE_BITMAP(full, IPVS_EST_TICK_CHAINS);

net/netfilter/ipvs/ip_vs_est.c

@@ -549,7 +549,7 @@ void ip_vs_stop_estimator(struct netns_ipvs *ipvs, struct ip_vs_stats *stats)
 	__set_bit(row, kd->avail);
 	if (!kd->tick_len[row]) {
 		RCU_INIT_POINTER(kd->ticks[row], NULL);
-		kfree_rcu(td);
+		kfree_rcu(td, rcu_head);
 	}
 	kd->est_count--;
 	if (kd->est_count) {