sctp: set the skb->ip_summed correctly when sending over loopback.

Loopback used to clobber the ip_summed filed which sctp then used to figure out if it needed to do checksumming or not. Now that loopback doesn't do that any more, sctp needs to set the ip_summed field correctly.

---
 net/sctp/output.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

index 0dc4a7d..225c712 100644
@@ -533,7 +533,8 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 	if (!(dst->dev->features & NETIF_F_NO_CSUM)) {
 		crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len);
 		crc32 = sctp_end_cksum(crc32);
-	}
+	} else
+		nskb->ip_summed = CHECKSUM_UNNECESSARY;
 
 	/* 3) Put the resultant value into the checksum field in the
 	 *    common header, and leave the rest of the bits unchanged.

1.5.3.5

From: Vlad Yasevich <[email protected]>
Date: Wed, 17 Sep 2008 16:03:01 -0400

That's a silly regression, sorry about that Vlad.

Applied to net-2.6, thanks!