From 49fb9cfe37259eb878ac0cb62eed3c80e9869900 Mon Sep 17 00:00:00 2001
From: Claudio-Daniel Freire <claudio-daniel.freire@inria.fr>
Date: Wed, 3 Aug 2011 12:31:22 +0200
Subject: [PATCH] Set TUN/TAP devices to ONE_QUEUE mode, which is more stable.
 Otherwise, heavily-loaded tunnels can destabilize PlanetLab kernels.

---
 src/nepi/testbeds/planetlab/scripts/tunalloc.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/nepi/testbeds/planetlab/scripts/tunalloc.c b/src/nepi/testbeds/planetlab/scripts/tunalloc.c
index 6adcf24a..9101392a 100644
--- a/src/nepi/testbeds/planetlab/scripts/tunalloc.c
+++ b/src/nepi/testbeds/planetlab/scripts/tunalloc.c
@@ -11,7 +11,11 @@
 #include <stdio.h>
 #include <string.h>
 #include <errno.h>
+#include <unistd.h>
 #include <sys/socket.h>
+#include <sys/fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/ioctl.h>
 #include <linux/if.h>
 #include <linux/if_tun.h>
 
@@ -91,5 +95,13 @@ int tun_alloc(int iftype, char *if_name)
     }
 
     remotefd = receive_vif_fd(control_fd, if_name);
+    
+    /* set "safe" (non-breaking) queueing mode IFF_ONE_QUEUE */
+    struct ifreq ifr;
+    if (0 == fcntl(remotefd, TUNGETIFF, &ifr)) {
+        ifr.ifr_flags |= IFF_ONE_QUEUE;
+        fcntl(remotefd, TUNSETIFF, &ifr);
+    }
+    
     return remotefd;
 }
-- 
2.47.0