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-rw-r--r--kernel/resource.c103
1 files changed, 103 insertions, 0 deletions
diff --git a/kernel/resource.c b/kernel/resource.c
index ae246f97c5d..4aef8867fd4 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1021,6 +1021,109 @@ void __release_region(struct resource *parent, resource_size_t start,
}
EXPORT_SYMBOL(__release_region);
+#ifdef CONFIG_MEMORY_HOTREMOVE
+/**
+ * release_mem_region_adjustable - release a previously reserved memory region
+ * @parent: parent resource descriptor
+ * @start: resource start address
+ * @size: resource region size
+ *
+ * This interface is intended for memory hot-delete. The requested region
+ * is released from a currently busy memory resource. The requested region
+ * must either match exactly or fit into a single busy resource entry. In
+ * the latter case, the remaining resource is adjusted accordingly.
+ * Existing children of the busy memory resource must be immutable in the
+ * request.
+ *
+ * Note:
+ * - Additional release conditions, such as overlapping region, can be
+ * supported after they are confirmed as valid cases.
+ * - When a busy memory resource gets split into two entries, the code
+ * assumes that all children remain in the lower address entry for
+ * simplicity. Enhance this logic when necessary.
+ */
+int release_mem_region_adjustable(struct resource *parent,
+ resource_size_t start, resource_size_t size)
+{
+ struct resource **p;
+ struct resource *res;
+ struct resource *new_res;
+ resource_size_t end;
+ int ret = -EINVAL;
+
+ end = start + size - 1;
+ if ((start < parent->start) || (end > parent->end))
+ return ret;
+
+ /* The kzalloc() result gets checked later */
+ new_res = kzalloc(sizeof(struct resource), GFP_KERNEL);
+
+ p = &parent->child;
+ write_lock(&resource_lock);
+
+ while ((res = *p)) {
+ if (res->start >= end)
+ break;
+
+ /* look for the next resource if it does not fit into */
+ if (res->start > start || res->end < end) {
+ p = &res->sibling;
+ continue;
+ }
+
+ if (!(res->flags & IORESOURCE_MEM))
+ break;
+
+ if (!(res->flags & IORESOURCE_BUSY)) {
+ p = &res->child;
+ continue;
+ }
+
+ /* found the target resource; let's adjust accordingly */
+ if (res->start == start && res->end == end) {
+ /* free the whole entry */
+ *p = res->sibling;
+ kfree(res);
+ ret = 0;
+ } else if (res->start == start && res->end != end) {
+ /* adjust the start */
+ ret = __adjust_resource(res, end + 1,
+ res->end - end);
+ } else if (res->start != start && res->end == end) {
+ /* adjust the end */
+ ret = __adjust_resource(res, res->start,
+ start - res->start);
+ } else {
+ /* split into two entries */
+ if (!new_res) {
+ ret = -ENOMEM;
+ break;
+ }
+ new_res->name = res->name;
+ new_res->start = end + 1;
+ new_res->end = res->end;
+ new_res->flags = res->flags;
+ new_res->parent = res->parent;
+ new_res->sibling = res->sibling;
+ new_res->child = NULL;
+
+ ret = __adjust_resource(res, res->start,
+ start - res->start);
+ if (ret)
+ break;
+ res->sibling = new_res;
+ new_res = NULL;
+ }
+
+ break;
+ }
+
+ write_unlock(&resource_lock);
+ kfree(new_res);
+ return ret;
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+
/*
* Managed region resource
*/