e1000e: remove use of IP payload checksum

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.

CC: stable <stable@vger.kernel.org> [3.4]
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>
diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index 31d37a2..623e30b 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -496,7 +496,7 @@
  * @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);
@@ -511,8 +511,8 @@
 	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;
@@ -523,19 +523,7 @@
 		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++;
 }
 
@@ -954,8 +942,7 @@
 		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);
 
@@ -1341,8 +1328,7 @@
 		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);
 
@@ -1512,9 +1498,8 @@
 			}
 		}
 
-		/* 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);
 
@@ -3098,19 +3083,10 @@
 
 	/* 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) {
@@ -5241,22 +5217,10 @@
 	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 */
@@ -6030,17 +5994,6 @@
 			 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;