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);
Nit: you could just use
LIST_HEAD(&stack);
to declare and initialize the variable in a single line.
> + 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/ ?
> + 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;
}
> + 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.
> + /* 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.
> + 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.
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