Resource handling: add 'insert_resource_expand_to_fit()' function
Not used anywhere yet, but this complements the existing plain
'insert_resource()' functionality with a version that can expand the
resource we are adding in order to fix up any conflicts it has with
existing resources.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/resource.c b/kernel/resource.c
index f5b518e..cf0a178 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -362,35 +362,21 @@
EXPORT_SYMBOL(allocate_resource);
-/**
- * insert_resource - Inserts a resource in the resource tree
- * @parent: parent of the new resource
- * @new: new resource to insert
- *
- * Returns 0 on success, -EBUSY if the resource can't be inserted.
- *
- * 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 children of
- * the new resource.
+/*
+ * Insert a resource into the resource tree. If successful, return NULL,
+ * otherwise return the conflicting resource (compare to __request_resource())
*/
-int insert_resource(struct resource *parent, struct resource *new)
+static struct resource * __insert_resource(struct resource *parent, struct resource *new)
{
- int result;
struct resource *first, *next;
- write_lock(&resource_lock);
-
for (;; parent = first) {
- result = 0;
first = __request_resource(parent, new);
if (!first)
- goto out;
+ return first;
- result = -EBUSY;
if (first == parent)
- goto out;
+ return first;
if ((first->start > new->start) || (first->end < new->end))
break;
@@ -401,15 +387,13 @@
for (next = first; ; next = next->sibling) {
/* Partial overlap? Bad, and unfixable */
if (next->start < new->start || next->end > new->end)
- goto out;
+ return next;
if (!next->sibling)
break;
if (next->sibling->start > new->end)
break;
}
- result = 0;
-
new->parent = parent;
new->sibling = next->sibling;
new->child = first;
@@ -426,10 +410,64 @@
next = next->sibling;
next->sibling = new;
}
+ return NULL;
+}
- out:
+/**
+ * insert_resource - Inserts a resource in the resource tree
+ * @parent: parent of the new resource
+ * @new: new resource to insert
+ *
+ * Returns 0 on success, -EBUSY if the resource can't be inserted.
+ *
+ * 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 children of
+ * the new resource.
+ */
+int insert_resource(struct resource *parent, struct resource *new)
+{
+ struct resource *conflict;
+
+ write_lock(&resource_lock);
+ conflict = __insert_resource(parent, new);
write_unlock(&resource_lock);
- return result;
+ return conflict ? -EBUSY : 0;
+}
+
+/**
+ * insert_resource_expand_to_fit - Insert a resource into the resource tree
+ * @parent: parent of the new resource
+ * @new: new resource to insert
+ *
+ * Insert a resource into the resource tree, possibly expanding it in order
+ * to make it encompass any conflicting resources.
+ */
+void insert_resource_expand_to_fit(struct resource *root, struct resource *new)
+{
+ if (new->parent)
+ return;
+
+ write_lock(&resource_lock);
+ for (;;) {
+ struct resource *conflict;
+
+ conflict = __insert_resource(root, new);
+ if (!conflict)
+ break;
+ if (conflict == root)
+ break;
+
+ /* Ok, expand resource to cover the conflict, then try again .. */
+ if (conflict->start < new->start)
+ new->start = conflict->start;
+ if (conflict->end > new->end)
+ new->end = conflict->end;
+
+ printk("Expanded resource %s due to conflict with %s\n", new->name, conflict->name);
+ }
+ write_unlock(&resource_lock);
}
/**