Hi Christoph,
On 8/6/19 9:32 AM, Christoph Hellwig wrote:
> A couple nitpicks below:
>
> On Thu, Aug 01, 2019 at 05:59:46PM +0200, Eric Auger wrote:
>> - * The new element is sorted by address with respect to the other
>> - * regions of the same type. In case it overlaps with another
>> - * region of the same type, regions are merged. In case it
>> - * overlaps with another region of different type, regions are
>> - * not merged.
>> + * Elements are sorted by start address and overlapping segments
>> + * of the same type are merged.
>> */
>> +int iommu_insert_resv_region(struct iommu_resv_region *new,
>> + struct list_head *regions)
>> {
>> + struct iommu_resv_region *iter, *tmp, *nr, *top;
>> + struct list_head stack;
>> + bool added = false;
>>
>> + INIT_LIST_HEAD(&stack);
Please forgive me for the delay. I am just back to the office.
>
> Nit: you could just use
>
> LIST_HEAD(&stack);
>
> to declare and initialize the variable in a single line.
done
>
>> + nr = iommu_alloc_resv_region(new->start, new->length,
>> + new->prot, new->type);
>> + if (!nr)
>> return -ENOMEM;
>>
>> + /* First add the new elt based on start address sorting */
>
> /elt/element/ ?
yes
>
>> + list_for_each_entry(iter, regions, list) {
>> + if (nr->start < iter->start) {
>> + list_add_tail(&nr->list, &iter->list);
>> + added = true;
>> + break;
>> + } else if (nr->start == iter->start && nr->type <= iter->type) {
>> + list_add_tail(&nr->list, &iter->list);
>> + added = true;
>> + break;
>> + }
>
> Nit: no need for an else after a a break. But then again both
> branches look identical, so why don't you just merge them:
>
> if (nr->start < iter->start ||
> (nr->start == iter->start && nr->type <= iter->type)) {
> list_add_tail(&nr->list, &iter->list);
> added = true;
> break;
I merged both
>
> }
>
>> + if (!added)
>> + list_add_tail(&nr->list, regions);
>
> Probably down to preference, but I'd just use a goto to jump past the
> list_add and save the added variable.
done
>
>> + /* Merge overlapping segments of type nr->type, if any */
>> + list_for_each_entry_safe(iter, tmp, regions, list) {
>> + phys_addr_t top_end, iter_end = iter->start + iter->length - 1;
>> + bool found = false;
>> +
>> + /* no merge needed on elements of different types than @nr */
>> + if (iter->type != nr->type) {
>> + list_move_tail(&iter->list, &stack);
>> + continue;
>> + }
>> +
>> + /* look for the last stack element of same type as @iter */
>> + list_for_each_entry_reverse(top, &stack, list)
>> + if (top->type == iter->type) {
>> + found = true;
>> + break;
>> + }
>> + if (!found) {
>
> Same here.
done
>
>> + list_move_tail(&iter->list, &stack);
>> + continue;
>> + }
>> +
>> + top_end = top->start + top->length - 1;
>> +
>> + if (iter->start > top_end + 1) {
>> + list_move_tail(&iter->list, &stack);
>> + } else {
>> + top->length = max(top_end, iter_end) - top->start + 1;
>> + list_del(&iter->list);
>> + kfree(iter);
>> + }
>
> I wonder if the body of the outer list_for_each_entry_safe loop would
> be a bit nicer in a helper, but again that is probably just down to
> personal preference.
I skipped that suggestion at the moment.
Hope that looks better in v3.
Thank you for your review!
Best Regards
Eric
>
