[E1000-devel] [RFC PATCH] igb: Enable SCTP checksum offloading

[Vlad Y. <vla...@hp...>]

Intel 82576 chipset supports SCTP checksum offloading.  This patch
enables this functionality in the driver.  A new NETIF feature
is introduced for SCTP checksum offload.  If the driver supports
CRC32c checksum, it can set this feature flag.

This is an RFC/RFT patch because I do not have access to hardware and
have no way to test this patch properly.  The values came from the
Intel 82576 Gigabit Ethernet Controller Datasheet.

Also, this has 2 patches rolled into one to simplify testing.  The
last hunk of this patchis the sctp change to look at the new feature bit.
That change will be split off when for the final submission.

This is really a request to look over the patch to see if things look right
and if you have time, run it on real hardware to make sure the offload really
works.  You can use 'netperf -t SCTP_STREAM' to test.

Signed-off-by: Vlad Yasevich <vla...@hp...>
---
 drivers/net/igb/e1000_82575.h |    1 +
 drivers/net/igb/igb_main.c    |    7 +++++++
 include/linux/netdevice.h     |    1 +
 net/sctp/output.c             |   11 ++++++++---
 4 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/net/igb/e1000_82575.h b/drivers/net/igb/e1000_82575.h
index eaf9770..0f16aba 100644
--- a/drivers/net/igb/e1000_82575.h
+++ b/drivers/net/igb/e1000_82575.h
@@ -130,6 +130,7 @@ struct e1000_adv_tx_context_desc {
 #define E1000_ADVTXD_MACLEN_SHIFT    9  /* Adv ctxt desc mac len shift */
 #define E1000_ADVTXD_TUCMD_IPV4    0x00000400  /* IP Packet Type: 1=IPv4 */
 #define E1000_ADVTXD_TUCMD_L4T_TCP 0x00000800  /* L4 Packet TYPE of TCP */
+#define E1000_ADVTXD_TUCMD_L4T_SCTP 0x00001000 /* L4 packet TYPE of SCTP */
 /* IPSec Encrypt Enable for ESP */
 #define E1000_ADVTXD_L4LEN_SHIFT     8  /* Adv ctxt L4LEN shift */
 #define E1000_ADVTXD_MSS_SHIFT      16  /* Adv ctxt MSS shift */
diff --git a/drivers/net/igb/igb_main.c b/drivers/net/igb/igb_main.c
index 7c4481b..cd8655c 100644
--- a/drivers/net/igb/igb_main.c
+++ b/drivers/net/igb/igb_main.c
@@ -1275,6 +1275,9 @@ static int __devinit igb_probe(struct pci_dev *pdev,
 	if (pci_using_dac)
 		netdev->features |= NETIF_F_HIGHDMA;

+	if (adapter->hw.mac.type == e1000_82576)
+		netdev->features |= NETIF_F_SCTP_CSUM;
+
 	adapter->en_mng_pt = igb_enable_mng_pass_thru(&adapter->hw);

 	/* before reading the NVM, reset the controller to put the device in a
@@ -3013,11 +3016,15 @@ static inline bool igb_tx_csum_adv(struct igb_adapter *adapter,
 				tu_cmd |= E1000_ADVTXD_TUCMD_IPV4;
 				if (ip_hdr(skb)->protocol == IPPROTO_TCP)
 					tu_cmd |= E1000_ADVTXD_TUCMD_L4T_TCP;
+				else if (ip_hdr(skb)->protocol == IPPROTO_SCTP)
+					tu_cmd |= E1000_ADVTXD_TUCMD_L4T_SCTP;
 				break;
 			case cpu_to_be16(ETH_P_IPV6):
 				/* XXX what about other V6 headers?? */
 				if (ipv6_hdr(skb)->nexthdr == IPPROTO_TCP)
 					tu_cmd |= E1000_ADVTXD_TUCMD_L4T_TCP;
+				else if (ipv6_hdr(skb)->nexthdr == IPPROTO_SCTP)
+					tu_cmd |= E1000_ADVTXD_TUCMD_L4T_SCTP;
 				break;
 			default:
 				if (unlikely(net_ratelimit()))
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index be3ebd7..267ffcf 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -660,6 +660,7 @@ struct net_device
 #define NETIF_F_NETNS_LOCAL	8192	/* Does not change network namespaces */
 #define NETIF_F_GRO		16384	/* Generic receive offload */
 #define NETIF_F_LRO		32768	/* large receive offload */
+#define NETIF_F_SCTP_CSUM	65536	/* SCTP checksum offload */

 	/* Segmentation offload features */
 #define NETIF_F_GSO_SHIFT	16
diff --git a/net/sctp/output.c b/net/sctp/output.c
index 7d08f52..ce8bf45 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -527,15 +527,20 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 	 * Note: Adler-32 is no longer applicable, as has been replaced
 	 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
 	 */
-	if (!sctp_checksum_disable && !(dst->dev->features & NETIF_F_NO_CSUM)) {
+	if (!sctp_checksum_disable &&
+	    !(dst->dev->features & (NETIF_F_NO_CSUM | NETIF_F_SCTP_CSUM))) {
 		__u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len);

 		/* 3) Put the resultant value into the checksum field in the
 		 *    common header, and leave the rest of the bits unchanged.
 		 */
 		sh->checksum = sctp_end_cksum(crc32);
-	} else
-		nskb->ip_summed = CHECKSUM_UNNECESSARY;
+	} else {
+		if (dst->dev->features & NETIF_F_SCTP_CSUM)
+			nskb->ip_summed = CHECKSUM_PARTIAL;
+		else
+			nskb->ip_summed = CHECKSUM_UNNECESSARY;
+	}

 	/* IP layer ECN support
 	 * From RFC 2481
-- 
1.5.4.3