RE: [Xen-devel] page_list_splice

[Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>]

> >Without this clause, I get a null-pointer (actually null+4) 
> >dereference... I think I must be missing some basic
> >difference between normal list code and page_list code.
> 
> The basic difference is that page_list_head has NULL pointers 
> when empty,
> whereas 'normal' lists heads have pointers to itself. So as 
> Keir already
> stated, yes, the second conditional is needed.

Thanks (Keir too) for the confirmation.

> >Anyway, could you take a look at the routine to see if
> 
> The one question I would have is whether you indeed intend this to be
> an insertion at the head of the list - inserting at the tail 
> would seem
> more natural. The 'normal' list accessors allow doing this by simply
> passing &head->prev as the second argument, but since the page lists
> aren't symmetric this cannot be done that way by the invoking 
> code (and
> hence a suffix-less version of page_list_splice() would seem to more
> naturally splice to the end of the existing list, while if 
> splicing to the
> beginning is indeed intended I'd favor calling it 
> page_list_splice_head()
> or some such).

Good feedback.  But I was just adapting the "official" (in
Xen and Linux) list.h list_splice() routine routine which
apparently inserts at the head.  For my usage, head vs
tail doesn't matter.

Thanks,
Dan

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