netfilter: nf_ct_expect: Change __nf_ct_expect_check() return value.

Commit 4dee62b1b9b4 ("netfilter: nf_ct_expect: nf_ct_expect_insert()
returns void") inadvertently changed the successful return value of
nf_ct_expect_related_report() from 0 to 1 due to
__nf_ct_expect_check() returning 1 on success.  Prevent this
regression in the future by changing the return value of
__nf_ct_expect_check() to 0 on success.

Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Acked-by: Joe Stringer <joe@ovn.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_conntrack_expect.c

@@ -410,7 +410,7 @@ static inline int __nf_ct_expect_check(struct nf_conntrack_expect *expect)
 	struct net *net = nf_ct_exp_net(expect);
 	struct hlist_node *next;
 	unsigned int h;
-	int ret = 1;
+	int ret = 0;
 
 	if (!master_help) {
 		ret = -ESHUTDOWN;
@@ -460,7 +460,7 @@ int nf_ct_expect_related_report(struct nf_conntrack_expect *expect,
 
 	spin_lock_bh(&nf_conntrack_expect_lock);
 	ret = __nf_ct_expect_check(expect);
-	if (ret <= 0)
+	if (ret < 0)
 		goto out;
 
 	nf_ct_expect_insert(expect);