From akpm@osdl.org Fri Jun 30 16:33:01 2006 From: Matthew Wilcox Message-Id: <200606300931.k5U9VOdN001627@shell0.pdx.osdl.net> Subject: Resources: insert identical resources above existing resources To: greg@kroah.com Cc: akpm@osdl.org, matthew@wil.cx, ink@jurassic.park.msu.ru, linux@dominikbrodowski.net Date: Fri, 30 Jun 2006 02:31:24 -0700 From: Matthew Wilcox 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 Cc: Ivan Kokshaysky Cc: Dominik Brodowski Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- kernel/resource.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-) --- gregkh-2.6.orig/kernel/resource.c +++ gregkh-2.6/kernel/resource.c @@ -341,12 +341,11 @@ 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) { @@ -354,20 +353,21 @@ int insert_resource(struct resource *par 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) {