On Mon, 2009-11-23 at 11:43 +0200, Michael S. Tsirkin wrote:
> should be !npage->private
> and nesting is too deep here:
> this is cleaner in a give_a_page subroutine
> as it was.
This will be addressed with Rusty's comment.
> > + /* use private to chain big packets */
>
> packets? or pages?
Will change it to chain pages for big packets
> > + p->private = (unsigned long)0;
>
> the comment is not really helpful:
> you say you use private to chain but 0 does not
> chain anything. You also do not need the cast to long?
Ok.
> > + if (len > (PAGE_SIZE - f->page_offset))
>
> brackets around math are not needed.
OK.
> typo
>
> > + * header and data */
Got it.
> please think of a way to get rid of magic constants like 6 and 2
> here and elsewhere.
Will do.
> replace MAX_SKB_FRAGS + 2 with something symbolic? We have it in 2 palces now.
> And comment.
Ok, I can change it.
> terrible goto based loop
> move stuff into subfunction, it will be much
> more manageable, and convert this to a simple
> for loop.
Will change it to different functions based on Rusty's comment.
> and here it is MAX_SKB_FRAGS + 1
I think I should use MAX_SKB_FRAGS + 2 instead. Now I only use
MAX_SKB_FRAGS + 1 but allocated + 2.
> > + page->private = (unsigned long)first_page;
> > + first_page = page;
> > + if (--i == 1) {
>
> this is pretty hairy ... has to be this way?
> What you are trying to do here
> is fill buffer with pages, in a loop, with first one
> using a partial page, and then add it.
> Is that it?
Yes.
> So please code this in a straight forward manner.
> it should be as simple as:
> offset = XXX
> for (i = 0; i < MAX_SKB_FRAGS + 2; ++i) {
>
> sg_set_buf(sg + i, p + offset, PAGE_SIZE - offset);
> offset = 0;
>
> }
Ok, looks more neat.
> space around +
> sg + 1 here is same as &sg[i] in fact?
Ok.
> callback -> destructor?
Ok.
I will integrate these comments with Rusty's and resubmit the patch set.
Thanks
Shirley
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