[PATCH 1/2] HID: Use krealloc

[Joe Perches]

This kmalloc/memcpy is equivalent to krealloc, so use krealloc
to avoid a possibly unnecessary memcpy.

Miscellanea:

o Add temporary variables osize and nsize to improve readability
o krealloc has a defect and does not support GFP_ZERO
  so the memset must be kept

Signed-off-by: Joe Perches <j...@perches.com>
---
 drivers/hid/hid-core.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index e9e87d337446..b1ebf53ca879 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -131,21 +131,19 @@ static int open_collection(struct hid_parser *parser, 
unsigned type)
        }
 
        if (parser->device->maxcollection == parser->device->collection_size) {
-               collection = kmalloc(sizeof(struct hid_collection) *
-                               parser->device->collection_size * 2, 
GFP_KERNEL);
-               if (collection == NULL) {
-                       hid_err(parser->device, "failed to reallocate 
collection array\n");
+               unsigned int osize = parser->device->collection_size;
+               unsigned int nsize = osize * 2;
+
+               collection = krealloc(parser->device->collection,
+                                     nsize * sizeof(struct hid_collection),
+                                     GFP_KERNEL);
+               if (!collection)
                        return -ENOMEM;
-               }
-               memcpy(collection, parser->device->collection,
-                       sizeof(struct hid_collection) *
-                       parser->device->collection_size);
-               memset(collection + parser->device->collection_size, 0,
-                       sizeof(struct hid_collection) *
-                       parser->device->collection_size);
-               kfree(parser->device->collection);
+
+               memset(collection + osize, 0,
+                      sizeof(struct hid_collection) * osize);
                parser->device->collection = collection;
-               parser->device->collection_size *= 2;
+               parser->device->collection_size = nsize;
        }
 
        parser->collection_stack[parser->collection_stack_ptr++] =
-- 
2.10.0.rc2.1.g053435c