Re: [PATCH V3 2/8] Add a new zerocopy device flag

[Shirley Ma]

On Tue, 2011-05-03 at 10:42 -0700, Shirley Ma wrote:
> Better to prevent this kind of skbs to be used in skb_clone, expand
> head
> for now.

I looked at the code, skb_clone shouldn't have any problem since ubuf
callback is only called after the lower device DMA has done. I can
modify the zerocopy len to 256 bytes so expand head should be OK as
well. So we only need to prevent recycle skb. I also checked the device
drivers, only a few device do RX buffers recycle. So there shouldn't be
any problem.

I will add more comments here to make sure when ZEROCOPY flag is set,
the ubuf callback should only be called when last reference to this skb
is gone.


Thanks
Shirley

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