netfilter: nf_ct_sip: Use mod_timer_pending()

timer_del() followed by timer_add() can be replaced by
mod_timer_pending().
Signed-off-by: Gao Feng <fgao@ikuai8.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_conntrack_sip.c

@@ -809,14 +809,12 @@ static int refresh_signalling_expectation(struct nf_conn *ct,
 		    exp->tuple.dst.protonum != proto ||
 		    exp->tuple.dst.u.udp.port != port)
 			continue;
-		if (!del_timer(&exp->timeout))
-			continue;
+		if (mod_timer_pending(&exp->timeout, jiffies + expires * HZ)) {
 			exp->flags &= ~NF_CT_EXPECT_INACTIVE;
-		exp->timeout.expires = jiffies + expires * HZ;
-		add_timer(&exp->timeout);
 			found = 1;
 			break;
 		}
+	}
 	spin_unlock_bh(&nf_conntrack_expect_lock);
 	return found;
 }