Re: Are "skb->data" physically continuous?

[Rask Ingemann Lambertsen (rask@sygehus.dk)]

On Tue, 16 Sep 2003 14:16:21 +0300, Nick Patavalis wrote
> How should the kernel be notified if the calculation of a checksum
> failed (checksum does not match). Reading the e100 source, I see that
> if the checksums (any of the checksums, I presume) of a packet are
> invalid, then the driver sets "skb->ip_summed" to CHECKSUM_NONE; but
> won't this force the kernel to re-calculate the checksums, although
> they are, in this case, a-priori known to be invalid?

AFAIK, the only way you can tell the kernel that the packet failed the 
checksum is to flag it with CHECKSUM_NONE (which is the default for a freshly 
allocated skb). And yes, this does make the kernel find the checksum failure 
by rechecking the checksum itself. While this mean double work, checksum 
failures are assumed to be rare so this shouldn't be a performance problem.

-- 
Regards,
Rask Ingemann Lambertsen

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