tcp: Get TCP_INFO once per socket

Right now we get SOL_TCP.TCP_INFO option twice, but one time
is enough.
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/sk-tcp.c

@@ -75,17 +75,16 @@ static int tcp_repair_on(int fd)
 	return ret;
 }
 
-static int refresh_inet_sk(struct inet_sk_desc *sk)
+static int refresh_inet_sk(struct inet_sk_desc *sk, struct tcp_info *ti)
 {
 	int size;
-	struct tcp_info info;
 
-	if (dump_opt(sk->rfd, SOL_TCP, TCP_INFO, &info)) {
+	if (dump_opt(sk->rfd, SOL_TCP, TCP_INFO, ti)) {
 		pr_perror("Failed to obtain TCP_INFO");
 		return -1;
 	}
 
-	switch (info.tcpi_state) {
+	switch (ti->tcpi_state) {
 	case TCP_ESTABLISHED:
 	case TCP_CLOSE:
 		break;
@@ -263,31 +262,25 @@ err_recv:
 	goto err_buf;
 }
 
-static int tcp_stream_get_options(int sk, TcpStreamEntry *tse)
+static int tcp_stream_get_options(int sk, struct tcp_info *ti, TcpStreamEntry *tse)
 {
 	int ret;
 	socklen_t auxl;
-	struct tcp_info ti;
 	int val;
 
-	auxl = sizeof(ti);
-	ret = getsockopt(sk, SOL_TCP, TCP_INFO, &ti, &auxl);
-	if (ret < 0)
-		goto err_sopt;
-
 	auxl = sizeof(tse->mss_clamp);
 	ret = getsockopt(sk, SOL_TCP, TCP_MAXSEG, &tse->mss_clamp, &auxl);
 	if (ret < 0)
 		goto err_sopt;
 
-	tse->opt_mask = ti.tcpi_options;
-	if (ti.tcpi_options & TCPI_OPT_WSCALE) {
-		tse->snd_wscale = ti.tcpi_snd_wscale;
-		tse->rcv_wscale = ti.tcpi_rcv_wscale;
+	tse->opt_mask = ti->tcpi_options;
+	if (ti->tcpi_options & TCPI_OPT_WSCALE) {
+		tse->snd_wscale = ti->tcpi_snd_wscale;
+		tse->rcv_wscale = ti->tcpi_rcv_wscale;
 		tse->has_rcv_wscale = true;
 	}
 
-	if (ti.tcpi_options & TCPI_OPT_TIMESTAMPS) {
+	if (ti->tcpi_options & TCPI_OPT_TIMESTAMPS) {
 		auxl = sizeof(val);
 		ret = getsockopt(sk, SOL_TCP, TCP_TIMESTAMP, &val, &auxl);
 		if (ret < 0)
@@ -299,9 +292,9 @@ static int tcp_stream_get_options(int sk, TcpStreamEntry *tse)
 
 	pr_info("\toptions: mss_clamp %x wscale %x tstamp %d sack %d\n",
 			(int)tse->mss_clamp,
-			ti.tcpi_options & TCPI_OPT_WSCALE ? (int)tse->snd_wscale : -1,
-			ti.tcpi_options & TCPI_OPT_TIMESTAMPS ? 1 : 0,
-			ti.tcpi_options & TCPI_OPT_SACK ? 1 : 0);
+			ti->tcpi_options & TCPI_OPT_WSCALE ? (int)tse->snd_wscale : -1,
+			ti->tcpi_options & TCPI_OPT_TIMESTAMPS ? 1 : 0,
+			ti->tcpi_options & TCPI_OPT_SACK ? 1 : 0);
 
 	return 0;
 
@@ -313,11 +306,12 @@ err_sopt:
 static int dump_tcp_conn_state(struct inet_sk_desc *sk)
 {
 	int ret, aux;
+	struct tcp_info ti;
 	struct cr_img *img;
 	TcpStreamEntry tse = TCP_STREAM_ENTRY__INIT;
 	char *in_buf, *out_buf;
 
-	ret = refresh_inet_sk(sk);
+	ret = refresh_inet_sk(sk, &ti);
 	if (ret < 0)
 		goto err_r;
 
@@ -350,7 +344,7 @@ static int dump_tcp_conn_state(struct inet_sk_desc *sk)
 	 */
 
 	pr_info("Reading options for socket\n");
-	ret = tcp_stream_get_options(sk->rfd, &tse);
+	ret = tcp_stream_get_options(sk->rfd, &ti, &tse);
 	if (ret < 0)
 		goto err_opt;