1 files changed, 27 insertions, 1 deletions

diff --git a/kernel/resource.c b/kernel/resource.c
index 3ff40178dce..c8dc249da5c 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -419,6 +419,9 @@ static int __find_resource(struct resource *root, struct resource *old,
                 else
                         tmp.end = root->end;
 
+                if (tmp.end < tmp.start)
+                        goto next;
+
                 resource_clip(&tmp, constraint->min, constraint->max);
                 arch_remove_reservations(&tmp);
 
@@ -436,8 +439,10 @@ static int __find_resource(struct resource *root, struct resource *old,
                                 return 0;
                         }
                 }
-                if (!this)
+
+next:           if (!this || this->end == root->end)
                         break;
+
                 if (this != old)
                         tmp.start = this->end + 1;
                 this = this->sibling;
@@ -553,6 +558,27 @@ int allocate_resource(struct resource *root, struct resource *new,
 
 EXPORT_SYMBOL(allocate_resource);
 
+/**
+ * lookup_resource - find an existing resource by a resource start address
+ * @root: root resource descriptor
+ * @start: resource start address
+ *
+ * Returns a pointer to the resource if found, NULL otherwise
+ */
+struct resource *lookup_resource(struct resource *root, resource_size_t start)
+{
+        struct resource *res;
+
+        read_lock(&resource_lock);
+        for (res = root->child; res; res = res->sibling) {
+                if (res->start == start)
+                        break;
+        }
+        read_unlock(&resource_lock);
+
+        return res;
+}
+
 /*
  * Insert a resource into the resource tree. If successful, return NULL,
  * otherwise return the conflicting resource (compare to __request_resource())