Current implementation is recursive and in case of allocation
failure the existing @regions list is altered. A non recursive
version looks better for maintainability and simplifies the
error handling. We use a separate stack for overlapping segment
merging.
Note this new implementation may change the region order of
appearance in /sys/kernel/iommu_groups/<n>/reserved_regions
files but this order has never been documented, see
commit bc7d12b91bd3 ("iommu: Implement reserved_regions
iommu-group sysfs file"). Previously the regions were sorted
by start address. Now they are first sorted by type and within
a type they are sorted by start address.
Signed-off-by: Eric Auger <[email protected]>
---
---
drivers/iommu/iommu.c | 96 ++++++++++++++++++++++---------------------
1 file changed, 50 insertions(+), 46 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 0c674d80c37f..7479f3d38e61 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -229,60 +229,64 @@ static ssize_t iommu_group_show_name(struct iommu_group
*group, char *buf)
* @new: new region to insert
* @regions: list of regions
*
- * 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 region type and elements of the same
+ * type are sorted by start address. Overlapping segments of the
+ * same type are merged.
*/
static int iommu_insert_resv_region(struct iommu_resv_region *new,
struct list_head *regions)
{
- struct iommu_resv_region *region;
- phys_addr_t start = new->start;
- phys_addr_t end = new->start + new->length - 1;
- struct list_head *pos = regions->next;
+ struct iommu_resv_region *iter, *tmp, *nr, *top;
+ struct list_head low, high, stack;
+ bool added = false;
- while (pos != regions) {
- struct iommu_resv_region *entry =
- list_entry(pos, struct iommu_resv_region, list);
- phys_addr_t a = entry->start;
- phys_addr_t b = entry->start + entry->length - 1;
- int type = entry->type;
+ INIT_LIST_HEAD(&low);
+ INIT_LIST_HEAD(&high);
+ INIT_LIST_HEAD(&stack);
- if (end < a) {
- goto insert;
- } else if (start > b) {
- pos = pos->next;
- } else if ((start >= a) && (end <= b)) {
- if (new->type == type)
- return 0;
- else
- pos = pos->next;
- } else {
- if (new->type == type) {
- phys_addr_t new_start = min(a, start);
- phys_addr_t new_end = max(b, end);
- int ret;
-
- list_del(&entry->list);
- entry->start = new_start;
- entry->length = new_end - new_start + 1;
- ret = iommu_insert_resv_region(entry, regions);
- kfree(entry);
- return ret;
- } else {
- pos = pos->next;
- }
- }
- }
-insert:
- region = iommu_alloc_resv_region(new->start, new->length,
- new->prot, new->type);
- if (!region)
+ nr = iommu_alloc_resv_region(new->start, new->length,
+ new->prot, new->type);
+ if (!nr)
return -ENOMEM;
- list_add_tail(®ion->list, pos);
+ /*
+ * Elements are dispatched into 3 lists: low/high contain
+ * segments of lower/higher types than @new; only segments
+ * with same type as @new remain in @regions, including @new
+ * ordered inserted by start address
+ */
+ list_for_each_entry_safe(iter, tmp, regions, list) {
+ if (iter->type < nr->type) {
+ list_move_tail(&iter->list, &low);
+ } else if (iter->type > nr->type) {
+ list_move_tail(&iter->list, &high);
+ } else if (nr->start <= iter->start && !added) {
+ list_add_tail(&nr->list, &iter->list);
+ added = true;
+ }
+ }
+ if (!added)
+ list_add_tail(&nr->list, regions);
+
+ /* Merge overlapping segments in @regions, if any */
+ list_move(regions->next, &stack); /* move the 1st elt to the stack */
+ list_for_each_entry_safe(iter, tmp, regions, list) {
+ phys_addr_t top_end, iter_end = iter->start + iter->length - 1;
+
+ top = list_last_entry(&stack, struct iommu_resv_region, list);
+ top_end = top->start + top->length - 1;
+
+ if (iter->start > top_end + 1) {
+ list_move(&iter->list, &top->list);
+ } else {
+ top->length = max(top_end, iter_end) - top->start + 1;
+ list_del(&iter->list);
+ kfree(iter);
+ }
+ }
+ list_splice(&stack, regions);
+ list_splice(&low, regions);
+ list_splice_tail(&high, regions);
return 0;
}
--
2.20.1
