[PATCH v12 1/9] iommu: Introduce a callback to struct iommu_resv_region

[Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>]

A callback is introduced to struct iommu_resv_region to free memory
allocations associated with the reserved region. This will be useful
when we introduce support for IORT RMR based reserved regions.

Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Tested-by: Steven Price <steven.price@xxxxxxx>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
---
 drivers/iommu/iommu.c | 16 +++++++++++-----
 include/linux/iommu.h |  2 ++
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index f2c45b85b9fc..ffcfa684e80c 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2597,16 +2597,22 @@ void iommu_put_resv_regions(struct device *dev, struct list_head *list)
  * @list: reserved region list for device
  *
  * IOMMU drivers can use this to implement their .put_resv_regions() callback
- * for simple reservations. Memory allocated for each reserved region will be
- * freed. If an IOMMU driver allocates additional resources per region, it is
- * going to have to implement a custom callback.
+ * for simple reservations. If a per region callback is provided that will be
+ * used to free all memory allocations associated with the reserved region or
+ * else just free up the memory for the regions. If an IOMMU driver allocates
+ * additional resources per region, it is going to have to implement a custom
+ * callback.
  */
 void generic_iommu_put_resv_regions(struct device *dev, struct list_head *list)
 {
 	struct iommu_resv_region *entry, *next;
 
-	list_for_each_entry_safe(entry, next, list, list)
-		kfree(entry);
+	list_for_each_entry_safe(entry, next, list, list) {
+		if (entry->free)
+			entry->free(dev, entry);
+		else
+			kfree(entry);
+	}
 }
 EXPORT_SYMBOL(generic_iommu_put_resv_regions);
 
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 9208eca4b0d1..68bcfb3a06d7 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -134,6 +134,7 @@ enum iommu_resv_type {
  * @length: Length of the region in bytes
  * @prot: IOMMU Protection flags (READ/WRITE/...)
  * @type: Type of the reserved region
+ * @free: Callback to free associated memory allocations
  */
 struct iommu_resv_region {
 	struct list_head	list;
@@ -141,6 +142,7 @@ struct iommu_resv_region {
 	size_t			length;
 	int			prot;
 	enum iommu_resv_type	type;
+	void (*free)(struct device *dev, struct iommu_resv_region *region);
 };
 
 /**
-- 
2.17.1