sctp: add feature bit for SCTP offload in hardware

this is the sctp code to enable hardware crc32c offload for
adapters that support it.

Originally by: Vlad Yasevich <vladislav.yasevich@hp.com>

modified by Jesse Brandeburg <jesse.brandeburg@intel.com>

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 16 insertions, 3 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index fe20d171acf1..f8c3619d551f 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -670,7 +670,9 @@ struct net_device
 #define NETIF_F_GRO             16384   /* Generic receive offload */
 #define NETIF_F_LRO             32768   /* large receive offload */
 
+/* the GSO_MASK reserves bits 16 through 23 */
 #define NETIF_F_FCOE_CRC        (1 << 24) /* FCoE CRC32 */
+#define NETIF_F_SCTP_CSUM       (1 << 25) /* 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 7d08f522ec84..f0c91df59d4e 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -412,6 +412,7 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 
         /* Build the SCTP header.  */
         sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr));
+        skb_reset_transport_header(nskb);
         sh->source = htons(packet->source_port);
         sh->dest   = htons(packet->destination_port);
 
@@ -527,15 +528,25 @@ 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          * Note: Adler-32 is no longer applicable, as has been replaced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) {
+                        /* no need to seed psuedo checksum for SCTP */
+                        nskb->ip_summed = CHECKSUM_PARTIAL;
+                        nskb->csum_start = (skb_transport_header(nskb) -
+                                            nskb->head);
+                        nskb->csum_offset = offsetof(struct sctphdr, checksum);
+                } else {
+                        nskb->ip_summed = CHECKSUM_UNNECESSARY;
+                }
+        }
 
         /* IP layer ECN support
          * From RFC 2481