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Message-Id: <1303347458-14499-1-git-send-email-maheshb@google.com>
Date: Wed, 20 Apr 2011 17:57:38 -0700
From: Mahesh Bandewar <maheshb@...gle.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>,
Mahesh Bandewar <maheshb@...gle.com>
Subject: [PATCH net-next] 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 <maheshb@...gle.com>
---
include/linux/netdevice.h | 3 ++-
net/core/ethtool.c | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index cb8178a..c4d9dd7 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1067,6 +1067,7 @@ struct net_device {
#define NETIF_F_RXHASH (1 << 28) /* Receive hashing offload */
#define NETIF_F_RXCSUM (1 << 29) /* Receive checksumming offload */
#define NETIF_F_NOCACHE_COPY (1 << 30) /* Use no-cache copyfromuser */
+#define NETIF_F_LOOPBACK (1 << 31) /* Enable loopback */
/* Segmentation offload features */
#define NETIF_F_GSO_SHIFT 16
@@ -1082,7 +1083,7 @@ struct net_device {
/* = all defined minus driver/device-class-related */
#define NETIF_F_NEVER_CHANGE (NETIF_F_HIGHDMA | NETIF_F_VLAN_CHALLENGED | \
NETIF_F_LLTX | NETIF_F_NETNS_LOCAL)
-#define NETIF_F_ETHTOOL_BITS (0x7f3fffff & ~NETIF_F_NEVER_CHANGE)
+#define NETIF_F_ETHTOOL_BITS (0xff3fffff & ~NETIF_F_NEVER_CHANGE)
/* List of features with software fallbacks. */
#define NETIF_F_GSO_SOFTWARE (NETIF_F_TSO | NETIF_F_TSO_ECN | \
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 13d79f5..d177ce9 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -362,7 +362,7 @@ static const char netdev_features_strings[ETHTOOL_DEV_FEATURE_WORDS * 32][ETH_GS
/* NETIF_F_RXHASH */ "rx-hashing",
/* NETIF_F_RXCSUM */ "rx-checksum",
/* NETIF_F_NOCACHE_COPY */ "tx-nocache-copy"
- "",
+ /* NETIF_F_LOOPBACK */ "loopback",
};
static int __ethtool_get_sset_count(struct net_device *dev, int sset)
--
1.7.3.1
--
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