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Commit c6c6e3e0 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

[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: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent cfbba49d

include/linux/skbuff.h

+10 −2
Original line number Diff line number Diff line
@@ -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

 */