[PATCH 1/2] net: Support RXFCS feature flag.

[PATCH 1/2] net: Support RXFCS feature flag.

[greearb]

From: Ben Greear <greearb@candelatech.com>

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>
---
:100644 100644 4b1c0dc... 7d27812... M	Documentation/networking/netdev-features.txt
:100644 100644 77f5202... d133186... M	include/linux/netdev_features.h
:100644 100644 3f79db1... 0801619... M	net/core/ethtool.c
 Documentation/networking/netdev-features.txt |    6 ++++++
 include/linux/netdev_features.h              |    2 ++
 net/core/ethtool.c                           |    1 +
 3 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/Documentation/networking/netdev-features.txt b/Documentation/networking/netdev-features.txt
index 4b1c0dc..7d27812 100644
--- 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 77f5202..d133186 100644
--- 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 3f79db1..0801619 100644
--- 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)
-- 
1.7.3.4

[PATCH 2/2] e100: Support RXFCS feature flag.

[greearb]

From: Ben Greear <greearb@candelatech.com>

This allows e100 to be configured to append the
Ethernet FCS to the skb.

Useful for sniffing networks.

Signed-off-by: Ben Greear <greearb@candelatech.com>
---
:100644 100644 485ab8c... 68b393b... M	drivers/net/ethernet/intel/e100.c
 drivers/net/ethernet/intel/e100.c |   15 ++++++++++++---
 1 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/e100.c b/drivers/net/ethernet/intel/e100.c
index 485ab8c..68b393b 100644
--- a/drivers/net/ethernet/intel/e100.c
+++ b/drivers/net/ethernet/intel/e100.c
@@ -1089,6 +1089,7 @@ static void e100_configure(struct nic *nic, struct cb *cb, struct sk_buff *skb)
 {
 	struct config *config = &cb->u.config;
 	u8 *c = (u8 *)config;
+	struct net_device *netdev = nic->netdev;
 
 	cb->command = cpu_to_le16(cb_config);
 
@@ -1132,6 +1133,9 @@ static void e100_configure(struct nic *nic, struct cb *cb, struct sk_buff *skb)
 		config->promiscuous_mode = 0x1;		/* 1=on, 0=off */
 	}
 
+	if (unlikely(netdev->features & NETIF_F_RXFCS))
+		config->rx_crc_transfer = 0x1;	/* 1=save, 0=discard */
+
 	if (nic->flags & multicast_all)
 		config->multicast_all = 0x1;		/* 1=accept, 0=no */
 
@@ -1919,6 +1923,7 @@ static int e100_rx_indicate(struct nic *nic, struct rx *rx,
 	struct sk_buff *skb = rx->skb;
 	struct rfd *rfd = (struct rfd *)skb->data;
 	u16 rfd_status, actual_size;
+	u16 fcs_pad = 0;
 
 	if (unlikely(work_done && *work_done >= work_to_do))
 		return -EAGAIN;
@@ -1951,9 +1956,11 @@ static int e100_rx_indicate(struct nic *nic, struct rx *rx,
 	}
 
 	/* Get actual data size */
+	if (unlikely(dev->features & NETIF_F_RXFCS))
+		fcs_pad = 4;
 	actual_size = le16_to_cpu(rfd->actual_size) & 0x3FFF;
-	if (unlikely(actual_size > RFD_BUF_LEN - sizeof(struct rfd)))
-		actual_size = RFD_BUF_LEN - sizeof(struct rfd);
+	if (unlikely(actual_size > RFD_BUF_LEN + fcs_pad - sizeof(struct rfd)))
+		actual_size = RFD_BUF_LEN + fcs_pad - sizeof(struct rfd);
 
 	/* Get data */
 	pci_unmap_single(nic->pdev, rx->dma_addr,
@@ -1980,7 +1987,7 @@ static int e100_rx_indicate(struct nic *nic, struct rx *rx,
 	if (unlikely(!(rfd_status & cb_ok))) {
 		/* Don't indicate if hardware indicates errors */
 		dev_kfree_skb_any(skb);
-	} else if (actual_size > ETH_DATA_LEN + VLAN_ETH_HLEN) {
+	} else if (actual_size > ETH_DATA_LEN + VLAN_ETH_HLEN + fcs_pad) {
 		/* Don't indicate oversized frames */
 		nic->rx_over_length_errors++;
 		dev_kfree_skb_any(skb);
@@ -2754,6 +2761,8 @@ static int __devinit e100_probe(struct pci_dev *pdev,
 	if (!(netdev = alloc_etherdev(sizeof(struct nic))))
 		return -ENOMEM;
 
+	netdev->hw_features |= NETIF_F_RXFCS;
+
 	netdev->netdev_ops = &e100_netdev_ops;
 	SET_ETHTOOL_OPS(netdev, &e100_ethtool_ops);
 	netdev->watchdog_timeo = E100_WATCHDOG_PERIOD;
-- 
1.7.3.4

Re: [PATCH 2/2] e100: Support RXFCS feature flag.

[Ben Greear]

On 02/06/2012 10:39 AM, greearb@candelatech.com wrote:
> From: Ben Greear<greearb@candelatech.com>
>
> This allows e100 to be configured to append the
> Ethernet FCS to the skb.
>
> Useful for sniffing networks.

This patch actually works in testing, but I think I might
be getting lucky somehow.  I think I need to add an ndo_set_features
method that resets the chip when the rxfcs flag is toggled...

So, please do not apply this version of this patch, I'll
re-send these when I complete that change and test it.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

[PATCH 0/2] Enable RXFCS as a feature.

[greearb]

From: Ben Greear <greearb@candelatech.com>

These patches are on top of the features work that
Michal Miroslaw posted recently.

A small patch to ethtool is needed as well.

These are just for comment until his patches go in.

Ben Greear (2):
  net:  Support RXFCS feature flag.
  e100:  Support RXFCS feature flag.

 drivers/net/e100.c              |   15 ++++++++++++---
 include/linux/ethtool.h         |    1 +
 include/linux/netdev_features.h |    2 ++
 net/core/ethtool.c              |   10 ++++++++--
 4 files changed, 23 insertions(+), 5 deletions(-)

-- 
1.7.3.4

[PATCH 2/2] e100: Support RXFCS feature flag.

[greearb]

From: Ben Greear <greearb@candelatech.com>

This allows e100 to be configured to append the
Ethernet FCS to the skb.

Useful for sniffing networks.

Signed-off-by: Ben Greear <greearb@candelatech.com>
---
:100644 100644 c1352c6... 761f6f5... M	drivers/net/e100.c
 drivers/net/e100.c |   15 ++++++++++++---
 1 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/net/e100.c b/drivers/net/e100.c
index c1352c6..761f6f5 100644
--- a/drivers/net/e100.c
+++ b/drivers/net/e100.c
@@ -1089,6 +1089,7 @@ static void e100_configure(struct nic *nic, struct cb *cb, struct sk_buff *skb)
 {
 	struct config *config = &cb->u.config;
 	u8 *c = (u8 *)config;
+	struct net_device *netdev = nic->netdev;
 
 	cb->command = cpu_to_le16(cb_config);
 
@@ -1132,6 +1133,9 @@ static void e100_configure(struct nic *nic, struct cb *cb, struct sk_buff *skb)
 		config->promiscuous_mode = 0x1;		/* 1=on, 0=off */
 	}
 
+	if (netdev->wanted_features & NETIF_F_RXFCS)
+		config->rx_crc_transfer = 0x1;	/* 1=save, 0=discard */
+
 	if (nic->flags & multicast_all)
 		config->multicast_all = 0x1;		/* 1=accept, 0=no */
 
@@ -1919,6 +1923,7 @@ static int e100_rx_indicate(struct nic *nic, struct rx *rx,
 	struct sk_buff *skb = rx->skb;
 	struct rfd *rfd = (struct rfd *)skb->data;
 	u16 rfd_status, actual_size;
+	u16 fcs_pad = 0;
 
 	if (unlikely(work_done && *work_done >= work_to_do))
 		return -EAGAIN;
@@ -1951,9 +1956,11 @@ static int e100_rx_indicate(struct nic *nic, struct rx *rx,
 	}
 
 	/* Get actual data size */
+	if (dev->wanted_features & NETIF_F_RXFCS)
+		fcs_pad = 4;
 	actual_size = le16_to_cpu(rfd->actual_size) & 0x3FFF;
-	if (unlikely(actual_size > RFD_BUF_LEN - sizeof(struct rfd)))
-		actual_size = RFD_BUF_LEN - sizeof(struct rfd);
+	if (unlikely(actual_size > RFD_BUF_LEN + fcs_pad - sizeof(struct rfd)))
+		actual_size = RFD_BUF_LEN + fcs_pad - sizeof(struct rfd);
 
 	/* Get data */
 	pci_unmap_single(nic->pdev, rx->dma_addr,
@@ -1980,7 +1987,7 @@ static int e100_rx_indicate(struct nic *nic, struct rx *rx,
 	if (unlikely(!(rfd_status & cb_ok))) {
 		/* Don't indicate if hardware indicates errors */
 		dev_kfree_skb_any(skb);
-	} else if (actual_size > ETH_DATA_LEN + VLAN_ETH_HLEN) {
+	} else if (actual_size > ETH_DATA_LEN + VLAN_ETH_HLEN + fcs_pad) {
 		/* Don't indicate oversized frames */
 		nic->rx_over_length_errors++;
 		dev_kfree_skb_any(skb);
@@ -2761,6 +2768,8 @@ static int __devinit e100_probe(struct pci_dev *pdev,
 		return -ENOMEM;
 	}
 
+	netdev->hw_features |= NETIF_F_RXFCS;
+
 	netdev->netdev_ops = &e100_netdev_ops;
 	SET_ETHTOOL_OPS(netdev, &e100_ethtool_ops);
 	netdev->watchdog_timeo = E100_WATCHDOG_PERIOD;
-- 
1.7.3.4