net: Support RXFCS feature flag.

When set on hardware that supports the feature,
this causes the Ethernet FCS to be appended
to the end of the skb.

Useful for sniffing packets.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/Documentation/networking/netdev-features.txt b/Documentation/networking/netdev-features.txt
index 4b1c0dcef84cc39675fc9c4e5ae4013930fd8529..7d2781230d30ec566164aa09d120752b69b6e947 100644 (file)
--- a/Documentation/networking/netdev-features.txt
+++ b/Documentation/networking/netdev-features.txt
@@ -152,3 +152,9 @@ NETIF_F_VLAN_CHALLENGED should be set for devices which can't cope with VLAN
 headers. Some drivers set this because the cards can't handle the bigger MTU.
 [FIXME: Those cases could be fixed in VLAN code by allowing only reduced-MTU
 VLANs. This may be not useful, though.]
+
+*  rx-fcs
+
+This requests that the NIC append the Ethernet Frame Checksum (FCS)
+to the end of the skb data.  This allows sniffers and other tools to
+read the CRC recorded by the NIC on receipt of the packet.

diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
index 77f5202977ceb6ced9785142189bd2d5e702539e..d1331865f830b2207e61305a5e4dac23c17c2533 100644 (file)
--- a/include/linux/netdev_features.h
+++ b/include/linux/netdev_features.h
@@ -54,6 +54,7 @@ enum {
        NETIF_F_RXCSUM_BIT,             /* Receive checksumming offload */
        NETIF_F_NOCACHE_COPY_BIT,       /* Use no-cache copyfromuser */
        NETIF_F_LOOPBACK_BIT,           /* Enable loopback */
+       NETIF_F_RXFCS_BIT,              /* Append FCS to skb pkt data */
 
        /*
         * Add your fresh new feature above and remember to update
@@ -98,6 +99,7 @@ enum {
 #define NETIF_F_TSO            __NETIF_F(TSO)
 #define NETIF_F_UFO            __NETIF_F(UFO)
 #define NETIF_F_VLAN_CHALLENGED        __NETIF_F(VLAN_CHALLENGED)
+#define NETIF_F_RXFCS          __NETIF_F(RXFCS)
 
 /* Features valid for ethtool to change */
 /* = all defined minus driver/device-class-related */

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 3f79db1b612a6f1042c3eb0e98e980c62e8d2c02..080161924a0d499359dd8d2f00404ac276783c17 100644 (file)
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -73,6 +73,7 @@ static const char netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN]
        [NETIF_F_RXCSUM_BIT] =           "rx-checksum",
        [NETIF_F_NOCACHE_COPY_BIT] =     "tx-nocache-copy",
        [NETIF_F_LOOPBACK_BIT] =         "loopback",
+       [NETIF_F_RXFCS_BIT] =            "rx-fcs",
 };
 
 static int ethtool_get_features(struct net_device *dev, void __user *useraddr)