From eed2a12f1ed9aabf0676f4d0db34aad51976c5c6 Mon Sep 17 00:00:00 2001 From: Mahesh Bandewar Date: Wed, 4 May 2011 15:30:11 +0000 Subject: net: Allow ethtool to set interface in loopback mode. This patch enables ethtool to set the loopback mode on a given interface. By configuring the interface in loopback mode in conjunction with a policy route / rule, a userland application can stress the egress / ingress path exposing the flows of the change in progress and potentially help developer(s) understand the impact of those changes without even sending a packet out on the network. Following set of commands illustrates one such example - a) ip -4 addr add 192.168.1.1/24 dev eth1 b) ip -4 rule add from all iif eth1 lookup 250 c) ip -4 route add local 0/0 dev lo proto kernel scope host table 250 d) arp -Ds 192.168.1.100 eth1 e) arp -Ds 192.168.1.200 eth1 f) sysctl -w net.ipv4.ip_nonlocal_bind=1 g) sysctl -w net.ipv4.conf.all.accept_local=1 # Assuming that the machine has 8 cores h) taskset 000f netserver -L 192.168.1.200 i) taskset 00f0 netperf -t TCP_CRR -L 192.168.1.100 -H 192.168.1.200 -l 30 Signed-off-by: Mahesh Bandewar Acked-by: Ben Hutchings Signed-off-by: David S. Miller --- drivers/net/loopback.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/net/loopback.c') diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c index d70fb76edb77..4ce9e5f2c069 100644 --- a/drivers/net/loopback.c +++ b/drivers/net/loopback.c @@ -174,7 +174,8 @@ static void loopback_setup(struct net_device *dev) | NETIF_F_HIGHDMA | NETIF_F_LLTX | NETIF_F_NETNS_LOCAL - | NETIF_F_VLAN_CHALLENGED; + | NETIF_F_VLAN_CHALLENGED + | NETIF_F_LOOPBACK; dev->ethtool_ops = &loopback_ethtool_ops; dev->header_ops = ð_header_ops; dev->netdev_ops = &loopback_ops; -- cgit v1.2.3-59-g8ed1b