[ 125/187] e1000e: remove use of IP payload checksum

Greg Kroah-Hartman
2012-07-12T23:01:40Z

From: Bruce Allan <bruce.w.allan@intel.com>

commit 2e1706f234f86ff71056ef69683d734fbf7e9e40 upstream.

Currently only used when packet split mode is enabled with jumbo frames,
IP payload checksum (for fragmented UDP packets) is mutually exclusive with
receive hashing offload since the hardware uses the same space in the
receive descriptor for the hardware-provided packet checksum and the RSS
hash, respectively. Users currently must disable jumbos when receive
hashing offload is enabled, or vice versa, because of this incompatibility.
Since testing has shown that IP payload checksum does not provide any real
benefit, just remove it so that there is no longer a choice between jumbos
or receive hashing offload but not both as done in other Intel GbE drivers
(e.g. e1000, igb).

Also, add a missing check for IP checksum error reported by the hardware;
let the stack verify the checksum when this happens.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/ethernet/intel/e1000e/defines.h | 1
drivers/net/ethernet/intel/e1000e/netdev.c | 75 +++++-----------------------
2 files changed, 15 insertions(+), 61 deletions(-)

--- a/drivers/net/ethernet/intel/e1000e/defines.h
+++ b/drivers/net/ethernet/intel/e1000e/defines.h
@@ -101,6 +101,7 @@
#define E1000_RXD_ERR_SEQ 0x04 /* Sequence Error */
#define E1000_RXD_ERR_CXE 0x10 /* Carrier Extension Error */
#define E1000_RXD_ERR_TCPE 0x20 /* TCP/UDP Checksum Error */
+#define E1000_RXD_ERR_IPE 0x40 /* IP Checksum Error */
#define E1000_RXD_ERR_RXE 0x80 /* Rx Data Error */
#define E1000_RXD_SPC_VLAN_MASK 0x0FFF /* VLAN ID is in lower 12 bits */

--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -495,7 +495,7 @@ static void e1000_receive_skb(struct e10
* @sk_buff: socket buffer with received data
**/
static void e1000_rx_checksum(struct e1000_adapter *adapter, u32 status_err,
- __le16 csum, struct sk_buff *skb)
+ struct sk_buff *skb)
{
u16 status = (u16)status_err;
u8 errors = (u8)(status_err >> 24);
@@ -510,8 +510,8 @@ static void e1000_rx_checksum(struct e10
if (status & E1000_RXD_STAT_IXSM)
return;

- /* TCP/UDP checksum error bit is set */
- if (errors & E1000_RXD_ERR_TCPE) {
+ /* TCP/UDP checksum error bit or IP checksum error bit is set */
+ if (errors & (E1000_RXD_ERR_TCPE | E1000_RXD_ERR_IPE)) {
/* let the stack verify checksum errors */
adapter->hw_csum_err++;
return;
@@ -522,19 +522,7 @@ static void e1000_rx_checksum(struct e10
return;

/* It must be a TCP or UDP packet with a valid checksum */
- if (status & E1000_RXD_STAT_TCPCS) {
- /* TCP checksum is good */
- skb->ip_summed = CHECKSUM_UNNECESSARY;
- } else {
- /*
- * IP fragment with UDP payload
- * Hardware complements the payload checksum, so we undo it
- * and then put the value in host order for further stack use.
- */
- __sum16 sum = (__force __sum16)swab16((__force u16)csum);
- skb->csum = csum_unfold(~sum);
- skb->ip_summed = CHECKSUM_COMPLETE;
- }
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
adapter->hw_csum_good++;
}

@@ -978,8 +966,7 @@ static bool e1000_clean_rx_irq(struct e1
skb_put(skb, length);

/* Receive Checksum Offload */
- e1000_rx_checksum(adapter, staterr,
- rx_desc->wb.lower.hi_dword.csum_ip.csum, skb);
+ e1000_rx_checksum(adapter, staterr, skb);

e1000_rx_hash(netdev, rx_desc->wb.lower.hi_dword.rss, skb);

@@ -1360,8 +1347,7 @@ copydone:
total_rx_bytes += skb->len;
total_rx_packets++;

- e1000_rx_checksum(adapter, staterr,
- rx_desc->wb.lower.hi_dword.csum_ip.csum, skb);
+ e1000_rx_checksum(adapter, staterr, skb);

e1000_rx_hash(netdev, rx_desc->wb.lower.hi_dword.rss, skb);

@@ -1531,9 +1517,8 @@ static bool e1000_clean_jumbo_rx_irq(str
}
}

- /* Receive Checksum Offload XXX recompute due to CRC strip? */
- e1000_rx_checksum(adapter, staterr,
- rx_desc->wb.lower.hi_dword.csum_ip.csum, skb);
+ /* Receive Checksum Offload */
+ e1000_rx_checksum(adapter, staterr, skb);

e1000_rx_hash(netdev, rx_desc->wb.lower.hi_dword.rss, skb);

@@ -3120,19 +3105,10 @@ static void e1000_configure_rx(struct e1

/* Enable Receive Checksum Offload for TCP and UDP */
rxcsum = er32(RXCSUM);
- if (adapter->netdev->features & NETIF_F_RXCSUM) {
+ if (adapter->netdev->features & NETIF_F_RXCSUM)
rxcsum |= E1000_RXCSUM_TUOFL;
-
- /*
- * IPv4 payload checksum for UDP fragments must be
- * used in conjunction with packet-split.
- */
- if (adapter->rx_ps_pages)
- rxcsum |= E1000_RXCSUM_IPPCSE;
- } else {
+ else
rxcsum &= ~E1000_RXCSUM_TUOFL;
- /* no need to clear IPPCSE as it defaults to 0 */
- }
ew32(RXCSUM, rxcsum);

if (adapter->hw.mac.type == e1000_pch2lan) {
@@ -5260,22 +5236,10 @@ static int e1000_change_mtu(struct net_d
int max_frame = new_mtu + ETH_HLEN + ETH_FCS_LEN;

/* Jumbo frame support */
- if (max_frame > ETH_FRAME_LEN + ETH_FCS_LEN) {
- if (!(adapter->flags & FLAG_HAS_JUMBO_FRAMES)) {
- e_err("Jumbo Frames not supported.\n");
- return -EINVAL;
- }
-
- /*
- * IP payload checksum (enabled with jumbos/packet-split when
- * Rx checksum is enabled) and generation of RSS hash is
- * mutually exclusive in the hardware.
- */
- if ((netdev->features & NETIF_F_RXCSUM) &&
- (netdev->features & NETIF_F_RXHASH)) {
- e_err("Jumbo frames cannot be enabled when both receive checksum offload and receive hashing are enabled. Disable one of the receive offload features before enabling jumbos.\n");
- return -EINVAL;
- }
+ if ((max_frame > ETH_FRAME_LEN + ETH_FCS_LEN) &&
+ !(adapter->flags & FLAG_HAS_JUMBO_FRAMES)) {
+ e_err("Jumbo Frames not supported.\n");
+ return -EINVAL;
}

/* Supported frame sizes */
@@ -6049,17 +6013,6 @@ static int e1000_set_features(struct net
NETIF_F_RXALL)))
return 0;

- /*
- * IP payload checksum (enabled with jumbos/packet-split when Rx
- * checksum is enabled) and generation of RSS hash is mutually
- * exclusive in the hardware.
- */
- if (adapter->rx_ps_pages &&
- (features & NETIF_F_RXCSUM) && (features & NETIF_F_RXHASH)) {
- e_err("Enabling both receive checksum offload and receive hashing is not possible with jumbo frames. Disable jumbos or enable only one of the receive offload features.\n");
- return -EINVAL;
- }
-
if (changed & NETIF_F_RXFCS) {
if (features & NETIF_F_RXFCS) {
adapter->flags2 &= ~FLAG2_CRC_STRIPPING;