Resources: insert identical resources above existing resources

If you have two resources which aree exactly the same size,
insert_resource() currently inserts the new one below the existing one.
This is wrong because there's no way to insert a resource of the same size
above an existing one.

I took this opportunity to rewrite the initial loop to be a for-loop
instead of a goto-loop and fix the documentation.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/kernel/resource.c b/kernel/resource.c
index 46286434af8066af359143df81244e0c3024de19..9db38a1a75208cb36bb8c68cd51f6ba7b293ce5f 100644 (file)
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -344,12 +344,11 @@ EXPORT_SYMBOL(allocate_resource);
  *
  * Returns 0 on success, -EBUSY if the resource can't be inserted.
  *
- * This function is equivalent of request_resource when no conflict
+ * This function is equivalent to request_resource when no conflict
  * happens. If a conflict happens, and the conflicting resources
  * entirely fit within the range of the new resource, then the new
- * resource is inserted and the conflicting resources become childs of
- * the new resource.  Otherwise the new resource becomes the child of
- * the conflicting resource
+ * resource is inserted and the conflicting resources become children of
+ * the new resource.
  */
 int insert_resource(struct resource *parent, struct resource *new)
 {
@@ -357,20 +356,21 @@ int insert_resource(struct resource *parent, struct resource *new)
        struct resource *first, *next;
 
        write_lock(&resource_lock);
- begin:
-       result = 0;
-       first = __request_resource(parent, new);
-       if (!first)
-               goto out;
 
-       result = -EBUSY;
-       if (first == parent)
-               goto out;
+       for (;; parent = first) {
+               result = 0;
+               first = __request_resource(parent, new);
+               if (!first)
+                       goto out;
 
-       /* Resource fully contained by the clashing resource? Recurse into it */
-       if (first->start <= new->start && first->end >= new->end) {
-               parent = first;
-               goto begin;
+               result = -EBUSY;
+               if (first == parent)
+                       goto out;
+
+               if ((first->start > new->start) || (first->end < new->end))
+                       break;
+               if ((first->start == new->start) && (first->end == new->end))
+                       break;
        }
 
        for (next = first; ; next = next->sibling) {