Re: [RFC PATCH v2] ptr_ring: linked list fallback

[Jason Wang]

On 2018å02æ28æ 11:28, Jason Wang wrote:
> > > Well I believe the main user for this is qdisc, which use skb array. 
> > > And we
> > > can not use what implemented in this patch directly for sk_buff 
> > > without some
> > > changes on the data structure.
> > Why not? skb has next and prev pointers at 1st two fields:
> >
> > struct sk_buff {
> > ÂÂÂÂÂÂÂÂ union {
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct {
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ /* These two members must be first. */
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct sk_buffÂÂÂÂÂÂÂÂÂ *next;
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct sk_buffÂÂÂÂÂÂÂÂÂ *prev;
> > ...
> > }
> >
> > so it's just a question of casting to struct plist.
>
> Well, then the casting can only be done in skb_array implementation? 

Ok, could be done in ptr ring. But still looks tricky, because of the 
different meaning of prev and last.

Thanks