resource: add release_child_resources

Useful for freeing a portion of the resource tree, e.g. when trying to
reallocate resources more efficiently.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/kernel/resource.c b/kernel/resource.c
index 7fd123ad00aa..24e9e60c1459 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -188,6 +188,36 @@ static int __release_resource(struct resource *old)
         return -EINVAL;
 }
 
+static void __release_child_resources(struct resource *r)
+{
+        struct resource *tmp, *p;
+        resource_size_t size;
+
+        p = r->child;
+        r->child = NULL;
+        while (p) {
+                tmp = p;
+                p = p->sibling;
+
+                tmp->parent = NULL;
+                tmp->sibling = NULL;
+                __release_child_resources(tmp);
+
+                printk(KERN_DEBUG "release child resource %pR\n", tmp);
+                /* need to restore size, and keep flags */
+                size = resource_size(tmp);
+                tmp->start = 0;
+                tmp->end = size - 1;
+        }
+}
+
+void release_child_resources(struct resource *r)
+{
+        write_lock(&resource_lock);
+        __release_child_resources(r);
+        write_unlock(&resource_lock);
+}
+
 /**
  * request_resource - request and reserve an I/O or memory resource
  * @root: root resource descriptor