Michał Mirosław wrote, at 05/04/2011 08:36 PM:

2011/4/29 Shan Wei [off-list ref]:

quoted

The device drivers should not use NETIF_F_ALL_TSO mask to set hw_features(or features),
but have to explicitly set offload option. Because, This would make drivers automatically
clain to support any new TSO feature an the moment of NETIF_F_ALL_TSO is expanded.

Some code style tuning. Just compile test.

Signed-off-by: Shan Wei <redacted>
---
 drivers/net/loopback.c   |   18 ++++++++----------
 drivers/net/virtio_net.c |    9 ++++++---
 2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index d70fb76..bfb6a4a 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c

@@ -152,6 +152,9 @@ static const struct net_device_ops loopback_ops = {
       .ndo_get_stats64 = loopback_get_stats64,
 };

+#define LOOPBACK_USER_FEATURES (NETIF_F_TSO | NETIF_F_TSO_ECN | \
+                               NETIF_F_TSO6 | NETIF_F_UFO)
+
 /*
 * The loopback device is special. There is only one instance
 * per network namespace.

@@ -165,16 +168,11 @@ static void loopback_setup(struct net_device *dev)
       dev->type               = ARPHRD_LOOPBACK;      /* 0x0001*/
       dev->flags              = IFF_LOOPBACK;
       dev->priv_flags        &= ~IFF_XMIT_DST_RELEASE;
-       dev->hw_features        = NETIF_F_ALL_TSO | NETIF_F_UFO;
-       dev->features           = NETIF_F_SG | NETIF_F_FRAGLIST
-               | NETIF_F_ALL_TSO
-               | NETIF_F_UFO
-               | NETIF_F_NO_CSUM
-               | NETIF_F_RXCSUM
-               | NETIF_F_HIGHDMA
-               | NETIF_F_LLTX
-               | NETIF_F_NETNS_LOCAL
-               | NETIF_F_VLAN_CHALLENGED;
+       dev->hw_features        = LOOPBACK_USER_FEATURES;
+       dev->features           = NETIF_F_SG | NETIF_F_FRAGLIST
+               | LOOPBACK_USER_FEATURES | NETIF_F_NO_CSUM | NETIF_F_RXCSUM
+               | NETIF_F_HIGHDMA | NETIF_F_LLTX
+               | NETIF_F_NETNS_LOCAL | NETIF_F_VLAN_CHALLENGED;
       dev->ethtool_ops        = &loopback_ethtool_ops;
       dev->header_ops         = &eth_header_ops;
       dev->netdev_ops         = &loopback_ops;

You can add NETIF_F_HIGHDMA and NETIF_F_NO_CSUM to
LOOPBACK_USER_FEATURES in one go. NETIF_F_RXCSUM could match
NETIF_F_NO_CSUM state (this needs ndo_fix_features callback), but this
won't have much real functional impact.

Do you mean that defining LOOPBACK_USER_FEATURES as:
#define LOOPBACK_USER_FEATURES (NETIF_F_TSO | NETIF_F_TSO_ECN | \
                               NETIF_F_TSO6 | NETIF_F_UFO | NETIF_F_HIGHDMA | NETIF_F_NO_CSUM)

Is it necessary to add NETIF_F_NO_CSUM to hw_features?
After that, user can change TX hw csum offload(NETIF_F_NO_CSUM is disabled). But, this is not surportted before.

-- 
Best Regards
-----
Shan Wei