From 5282e06fd4d021c57a5ad770581fb611de517ae7 Mon Sep 17 00:00:00 2001
From: Adam Ierymenko <adam.ierymenko@zerotier.com>
Date: Mon, 16 Nov 2020 19:08:09 -0500
Subject: [PATCH] Tun/tap flags fix.

---
 osdep/LinuxEthernetTap.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/osdep/LinuxEthernetTap.cpp b/osdep/LinuxEthernetTap.cpp
index 89caccf57..ebd295a80 100644
--- a/osdep/LinuxEthernetTap.cpp
+++ b/osdep/LinuxEthernetTap.cpp
@@ -174,7 +174,6 @@ LinuxEthernetTap::LinuxEthernetTap(
 	::ioctl(_fd,TUNSETPERSIST,0); // valgrind may generate a false alarm here
 	_dev = ifr.ifr_name;
 	::fcntl(_fd,F_SETFD,fcntl(_fd,F_GETFD) | FD_CLOEXEC);
-	::fcntl(_fd,F_SETFL,O_NONBLOCK);
 
 	(void)::pipe(_shutdownSignalPipe);
 
@@ -450,7 +449,7 @@ void LinuxEthernetTap::threadMain()
 			return;
 		}
 
-		if (fcntl(_fd,F_SETFL,fcntl(_fd,F_GETFL) & ~O_NONBLOCK) == -1) {
+		if (fcntl(_fd,F_SETFL,O_NONBLOCK) == -1) {
 			::close(sock);
 			printf("WARNING: ioctl() failed setting up Linux tap device (set non-blocking)\n");
 			return;