Messages in this thread | | | From | Zang MingJie <> | Subject | Re: [PATCH] net: preserve IP control block during GSO segmentation | Date | Mon, 11 Jan 2016 15:45:57 +0800 |
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On 01/08/2016 08:13 PM, David Laight wrote: > You could set SKB_SGO_CB_OFFSET to sizeof ((skb)->cb) - sizeof (struct skb_gso_cb) > so that the end of 'cb' is always used. > (Assuming the former is a multiple of 4.) > > It might be worth using an on-stack structure passed through as a separate > parameter - it doesn't look as though it has to be queued with the skb. > (Clearly a bigger change.)
I would definitely prefer the stack structure.
As a kernel developer, sometime I can hardly figure out which struct current cb is without debug it, and the worst they are not documented anywhere. I can hardly know the life time of the cb types.
If using a stack, things can be much easier. only an extra var to store the stack top:
int cb_top;
and several macro to manage the stack:
SKB_CB_PUSH(skb, type) SKB_CB_POP(skb) SKB_CB_TOP(skb, type)
and maybe a debug variable to store current cb type.
All current cb macro can be replaced by SKB_CB_TOP.
Although it is a big change, I think it worths, for both performance and maintainability
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