net: sched: act_gact: remove dependency on rtnl lock

Use tcf spinlock to protect gact action private state from concurrent
modification during dump and init. Remove rtnl assertion that is no longer
necessary.
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/act_gact.c

@@ -113,7 +113,7 @@ static int tcf_gact_init(struct net *net, struct nlattr *nla,
 
 	gact = to_gact(*a);
 
-	ASSERT_RTNL();
+	spin_lock(&gact->tcf_lock);
 	gact->tcf_action = parm->action;
 #ifdef CONFIG_GACT_PROB
 	if (p_parm) {
@@ -126,6 +126,8 @@ static int tcf_gact_init(struct net *net, struct nlattr *nla,
 		gact->tcfg_ptype   = p_parm->ptype;
 	}
 #endif
+	spin_unlock(&gact->tcf_lock);
+
 	if (ret == ACT_P_CREATED)
 		tcf_idr_insert(tn, *a);
 	return ret;
@@ -178,10 +180,11 @@ static int tcf_gact_dump(struct sk_buff *skb, struct tc_action *a,
 		.index   = gact->tcf_index,
 		.refcnt  = refcount_read(&gact->tcf_refcnt) - ref,
 		.bindcnt = atomic_read(&gact->tcf_bindcnt) - bind,
-		.action  = gact->tcf_action,
 	};
 	struct tcf_t t;
 
+	spin_lock(&gact->tcf_lock);
+	opt.action = gact->tcf_action;
 	if (nla_put(skb, TCA_GACT_PARMS, sizeof(opt), &opt))
 		goto nla_put_failure;
 #ifdef CONFIG_GACT_PROB
@@ -199,9 +202,12 @@ static int tcf_gact_dump(struct sk_buff *skb, struct tc_action *a,
 	tcf_tm_dump(&t, &gact->tcf_tm);
 	if (nla_put_64bit(skb, TCA_GACT_TM, sizeof(t), &t, TCA_GACT_PAD))
 		goto nla_put_failure;
+	spin_unlock(&gact->tcf_lock);
+
 	return skb->len;
 
 nla_put_failure:
+	spin_unlock(&gact->tcf_lock);
 	nlmsg_trim(skb, b);
 	return -1;
 }