[NET]: Update comments for skb checksums
Rusty (whose comments we should all study and emulate :) pointed
out that our comments for skb checksums are no longer up-to-date.
So here is a patch to
1) add the case of partial checksums on input;
2) update partial checksum case to mention csum_start/csum_offset;
3) mention the new IPv6 feature bit.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 625d73b..9391e4a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -65,13 +65,20 @@
* is able to produce some skb->csum, it MUST use COMPLETE,
* not UNNECESSARY.
*
+ * PARTIAL: identical to the case for output below. This may occur
+ * on a packet received directly from another Linux OS, e.g.,
+ * a virtualised Linux kernel on the same host. The packet can
+ * be treated in the same way as UNNECESSARY except that on
+ * output (i.e., forwarding) the checksum must be filled in
+ * by the OS or the hardware.
+ *
* B. Checksumming on output.
*
* NONE: skb is checksummed by protocol or csum is not required.
*
* PARTIAL: device is required to csum packet as seen by hard_start_xmit
- * from skb->transport_header to the end and to record the checksum
- * at skb->transport_header + skb->csum.
+ * from skb->csum_start to the end and to record the checksum
+ * at skb->csum_start + skb->csum_offset.
*
* Device must show its capabilities in dev->features, set
* at device setup time.
@@ -82,6 +89,7 @@
* TCP/UDP over IPv4. Sigh. Vendors like this
* way by an unknown reason. Though, see comment above
* about CHECKSUM_UNNECESSARY. 8)
+ * NETIF_F_IPV6_CSUM about as dumb as the last one but does IPv6 instead.
*
* Any questions? No questions, good. --ANK
*/