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Date: Wed, 4 May 2011 18:28:57 -0700
From: Mahesh Bandewar <maheshb@...gle.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>,
Ben Hutchings <bhutchings@...arflare.com>,
Michał Mirosław <mirq-linux@...e.qmqm.pl>,
Tom Herbert <therbert@...gle.com>,
Mahesh Bandewar <maheshb@...gle.com>
Subject: Re: [PATCHv2 1/2] net: Allow ethtool to set interface in loopback mode.
Please discard this, I do not wish to create a new thread for this.
Thanks,
--mahesh..
On Wed, May 4, 2011 at 6:26 PM, Mahesh Bandewar <maheshb@...gle.com> wrote:
> 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>
> ---
> Changes since v1
> Added NETIF_F_LOOPBACK in loopback device's feature-set.
>
> drivers/net/loopback.c | 3 ++-
> include/linux/netdevice.h | 3 ++-
> net/core/ethtool.c | 2 +-
> 3 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
> index d70fb76..4ce9e5f 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;
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index d5de66a..e7244ed 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_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 d8b1a8d..f26649d 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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