sk-tcp: Print libsoccr_save() error message

Improve dump_tcp_conn_state() *debugibility*.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/sk-tcp.c

@@ -113,8 +113,10 @@ static int dump_tcp_conn_state(struct inet_sk_desc *sk)
 	struct libsoccr_sk_data data;
 
 	ret = libsoccr_save(socr, &data, sizeof(data));
-	if (ret < 0)
+	if (ret < 0) {
+		pr_err("libsoccr_save() failed with %d\n", ret);
 		goto err_r;
+	}
 	if (ret != sizeof(data)) {
 		pr_err("This libsocr is not supported (%d vs %d)\n",
 				ret, (int)sizeof(data));

soccr/soccr.c

@@ -374,10 +374,10 @@ int libsoccr_save(struct libsoccr_sk *sk, struct libsoccr_sk_data *data, unsigne
 	sk->flags |= SK_FLAG_FREE_SQ | SK_FLAG_FREE_RQ;
 
 	if (get_queue(sk->fd, TCP_RECV_QUEUE, &data->inq_seq, data->inq_len, &sk->recv_queue))
-		return -4;
+		return -5;
 
 	if (get_queue(sk->fd, TCP_SEND_QUEUE, &data->outq_seq, data->outq_len, &sk->send_queue))
-		return -5;
+		return -6;
 
 	return sizeof(struct libsoccr_sk_data);
 }