From c6c6e3e05c0b4349824efcdd36650e7be9d5c7c3 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Tue, 10 Jul 2007 22:41:55 -0700 Subject: [PATCH] [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 Signed-off-by: David S. Miller --- include/linux/skbuff.h | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 625d73b07ab7..9391e4a4c344 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 */