On Thu, Apr 04, 2013 at 08:07:44AM -0600, Toshi Kani wrote:
> On Thu, 2013-04-04 at 14:48 +0800, Ram Pai wrote:
> > On Wed, Apr 03, 2013 at 01:55:05PM -0600, Toshi Kani wrote:
> > > On Wed, 2013-04-03 at 13:37 +0800, Ram Pai wrote:
> > > > On Tue, Apr 02, 2013 at 10:17:29AM -0600, Toshi Kani wrote:
> > > > > + while ((res = *p)) {
> >
> > ...snip...
> >
> > > > > + if (res->start > start || res->end < end) {
> > > >
> > > > This check looks sub-optimal; possbily wrong, to me. if the res->start
> > > > is greater than 'start', then obviously its sibling's start will
> > > > also be greater than 'start'. So it will loop through all the
> > > > resources unnecesarily.
> > >
> > > I think this check is necessary to check if the requested range fits
> > > into a resource. It needs to check both sides to verify this. I will
> > > add some comment on this check.
> > >
> > > > you might want something like
> > > >
> > > > if (start >= res->end) {
> > >
> > > I agree that this list is sorted, so we can optimize an error case (i.e.
> > > no matching entry is found) with an additional check. I will add the
> > > following check at the beginning of the while loop.
> > >
> > > if (res->start >= end)
> > > break;
> > >
> > > I also realized that the function returns 0 when no matching entry is
> > > found. I will change it to return -EINVAL as well.
> >
> > ok. this will take care of it.
> >
> > >
> > > >
> > > > > + p = &res->sibling;
> > > > > + continue;
> > > > > + }
> > > > > +
> > > > > + if (!(res->flags & IORESOURCE_MEM)) {
> > > > > + ret = -EINVAL;
> > > > > + break;
> > > > > + }
> > > > > +
> > > > > + if (!(res->flags & IORESOURCE_BUSY)) {
> > > > > + p = &res->child;
> > > > > + continue;
> > > > > + }
> > > > > +
> > > > > + if (res->start == start && res->end == end) {
> > > > > + /* free the whole entry */
> > > > > + *p = res->sibling;
> > > > > + kfree(res);
> > > >
> > > > This is incomplete. the prev resource's sibling should now point to
> > > > this resource's sibling. The parent's child has to be updated if
> > > > this resource is the first child resource. no?
> > >
> > > If this resource is the first child, *p is set to &parent->child. So,
> > > it will update the parents' child.
> >
> > But if the resource is not the parent's first child? will it update the
> > previous siblings ->sibling ?
>
> Yes. When it continues in the while loop, p is set to &res->sibling.
> So, it will update the previous sibling's ->sibling.
You are right. It does update the pointers correctly. I mis-read the
code.
RP
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