1 files changed, 12 insertions, 11 deletions

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index f41d5fe51abe..9993b692598f 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -125,6 +125,7 @@ static int open_collection(struct hid_parser *parser, unsigned type)
 {
         struct hid_collection *collection;
         unsigned usage;
+        int collection_index;
 
         usage = parser->local.usage[0];
 
@@ -167,13 +168,13 @@ static int open_collection(struct hid_parser *parser, unsigned type)
         parser->collection_stack[parser->collection_stack_ptr++] =
                 parser->device->maxcollection;
 
-        collection = parser->device->collection +
-                parser->device->maxcollection++;
+        collection_index = parser->device->maxcollection++;
+        collection = parser->device->collection + collection_index;
         collection->type = type;
         collection->usage = usage;
         collection->level = parser->collection_stack_ptr - 1;
-        collection->parent = parser->active_collection;
-        parser->active_collection = collection;
+        collection->parent_idx = (collection->level == 0) ? -1 :
+                parser->collection_stack[collection->level - 1];
 
         if (type == HID_COLLECTION_APPLICATION)
                 parser->device->maxapplication++;
@@ -192,8 +193,6 @@ static int close_collection(struct hid_parser *parser)
                 return -EINVAL;
         }
         parser->collection_stack_ptr--;
-        if (parser->active_collection)
-                parser->active_collection = parser->active_collection->parent;
         return 0;
 }
 
@@ -1006,10 +1005,12 @@ static void hid_apply_multiplier_to_field(struct hid_device *hid,
                 usage = &field->usage[i];
 
                 collection = &hid->collection[usage->collection_index];
-                while (collection && collection != multiplier_collection)
-                        collection = collection->parent;
+                while (collection->parent_idx != -1 &&
+                       collection != multiplier_collection)
+                        collection = &hid->collection[collection->parent_idx];
 
-                if (collection || multiplier_collection == NULL)
+                if (collection->parent_idx != -1 ||
+                    multiplier_collection == NULL)
                         usage->resolution_multiplier = effective_multiplier;
 
         }
@@ -1044,9 +1045,9 @@ static void hid_apply_multiplier(struct hid_device *hid,
          * applicable fields later.
          */
         multiplier_collection = &hid->collection[multiplier->usage->collection_index];
-        while (multiplier_collection &&
+        while (multiplier_collection->parent_idx != -1 &&
                multiplier_collection->type != HID_COLLECTION_LOGICAL)
-                multiplier_collection = multiplier_collection->parent;
+                multiplier_collection = &hid->collection[multiplier_collection->parent_idx];
 
         effective_multiplier = hid_calculate_multiplier(hid, multiplier);