On Fri, Mar 25, 2016 at 9:10 AM, Ben Greear <gree...@candelatech.com> wrote:
> I am suspicious that this will break at least some drivers. I grepped
> around
> for ip_summed, and found this, for instance:
>
> davicom/dm9000.c
>
> /* The DM9000 is not smart enough to leave fragmented packets alone.
> */
> if (dm->ip_summed != ip_summed) {
> if (ip_summed == CHECKSUM_NONE)
> iow(dm, DM9000_TCCR, 0);
> else
> iow(dm, DM9000_TCCR, TCCR_IP | TCCR_UDP | TCCR_TCP);
> dm->ip_summed = ip_summed;
> }
>
>
> It is taking action based on ip_summed == CHECKSUM_NONE, and your change
> will probably break that.
>
> I would suggest that we try to make any fix specific only to veth,
> at least for now. A tree-wide audit of drivers is probably required
> to safely make the kind of change you propose above.
>
> So, unless you can explain why your change is safe, then I do not plan
> to test it.
I just blindly trust the comments there:
* CHECKSUM_UNNECESSARY:
*
* This has the same meaning on as CHECKSUM_NONE for checksum offload on
* output.
Let's Cc Tom who wrote this comment.
On the other hand, hyperv got this correctly:
if ((skb->ip_summed == CHECKSUM_NONE) ||
(skb->ip_summed == CHECKSUM_UNNECESSARY))
goto do_send;
So I believe dm9000 needs to fix.
Thanks.
