diff --git a/package/linux/make.sh b/package/linux/make.sh
old mode 100644
new mode 100755
diff --git a/src/dns_client.c b/src/dns_client.c
index a4fa36b..6c01530 100644
--- a/src/dns_client.c
+++ b/src/dns_client.c
@@ -1774,10 +1774,10 @@ static int _DNS_client_create_socket_tls(struct dns_server_info *server_info, ch
 	}
 
 	// ? this cause ssl crash ?
-	// setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &yes, sizeof(yes));
-	// setsockopt(fd, IPPROTO_TCP, TCP_THIN_DUPACK, &yes, sizeof(yes));
-	// setsockopt(fd, IPPROTO_TCP, TCP_THIN_LINEAR_TIMEOUTS, &yes, sizeof(yes));
-	// set_sock_keepalive(fd, 15, 3, 4);
+	setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &yes, sizeof(yes));
+	setsockopt(fd, IPPROTO_TCP, TCP_THIN_DUPACK, &yes, sizeof(yes));
+	setsockopt(fd, IPPROTO_TCP, TCP_THIN_LINEAR_TIMEOUTS, &yes, sizeof(yes));
+	set_sock_keepalive(fd, 15, 3, 4);
 	setsockopt(fd, SOL_SOCKET, SO_PRIORITY, &priority, sizeof(priority));
 	setsockopt(fd, IPPROTO_IP, IP_TOS, &ip_tos, sizeof(ip_tos));
 
diff --git a/src/fast_ping.c b/src/fast_ping.c
index 54352bc..0f2781e 100644
--- a/src/fast_ping.c
+++ b/src/fast_ping.c
@@ -365,7 +365,12 @@ static void _fast_ping_close_host_sock(struct ping_host_struct *ping_host)
 
 static void _fast_ping_host_put(struct ping_host_struct *ping_host)
 {
-	if (!atomic_dec_and_test(&ping_host->ref)) {
+	int ref_cnt = atomic_dec_and_test(&ping_host->ref);
+	if (!ref_cnt) {
+		if (ref_cnt < 0) {
+			tlog(TLOG_ERROR, "invalid refcount of ping_host %s", ping_host->host);
+			abort();
+		}
 		return;
 	}
 
@@ -1081,15 +1086,19 @@ struct ping_host_struct *fast_ping_start(PING_TYPE type, const char *host, int c
 	pthread_mutex_unlock(&ping.map_lock);
 
 	_fast_ping_host_get(ping_host);
+	_fast_ping_host_get(ping_host);
+	// for ping race condition, get reference count twice
 	if (_fast_ping_sendping(ping_host) != 0) {
 		goto errout_remove;
 	}
 
 	ping_host->run = 1;
 	freeaddrinfo(gai);
+	_fast_ping_host_put(ping_host);
 	return ping_host;
 errout_remove:
 	fast_ping_stop(ping_host);
+	_fast_ping_host_put(ping_host);
 	ping_host = NULL;
 errout:
 	if (gai) {
diff --git a/src/util.c b/src/util.c
index e1fa339..fcc7289 100644
--- a/src/util.c
+++ b/src/util.c
@@ -1045,7 +1045,7 @@ void print_stack(void)
 	}
 	
 	tlog(TLOG_FATAL, "Stack:");
-	for (size_t idx = 0; idx < frame_num; ++idx) {
+	for (int idx = 0; idx < frame_num; ++idx) {
 		const void *addr = buffer[idx];
 		const char *symbol = "";