Re: [PATCH 04/47] block-rbd: Refactor two calls for memory allocations in rbd_dev_image_id()

Ilya Dryomov
2016-09-13T08:03:11Z

On Mon, Sep 12, 2016 at 8:45 PM, SF Markus Elfring
<elfring@users.sourceforge.net> wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Sun, 11 Sep 2016 14:48:41 +0200
>
> * Pass the sizes for memory allocations to the corresponding functions
> directly without storing the calculated values in an
> intermediate variable.
>
> * Delete the local variable "size" which became unnecessary with
> this refactoring.
>
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
> drivers/block/rbd.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index d61a066..c1da844 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -5833,7 +5833,6 @@ again:
> static int rbd_dev_image_id(struct rbd_device *rbd_dev)
> {
> int ret;
> - size_t size;
> char *object_name;
> void *response;
> char *image_id;
> @@ -5854,17 +5853,16 @@ static int rbd_dev_image_id(struct rbd_device *rbd_dev)
> * First, see if the format 2 image id file exists, and if
> * so, get the image's persistent id from it.
> */
> - size = sizeof (RBD_ID_PREFIX) + strlen(rbd_dev->spec->image_name);
> - object_name = kmalloc(size, GFP_NOIO);
> + object_name = kmalloc(sizeof(RBD_ID_PREFIX)
> + + strlen(rbd_dev->spec->image_name),
> + GFP_NOIO);
> if (!object_name)
> return -ENOMEM;
> sprintf(object_name, "%s%s", RBD_ID_PREFIX, rbd_dev->spec->image_name);
> dout("rbd id object name is %s\n", object_name);
>
> /* Response will be an encoded string, which includes a length */
> -
> - size = sizeof (__le32) + RBD_IMAGE_ID_LEN_MAX;
> - response = kzalloc(size, GFP_NOIO);
> + response = kzalloc(sizeof(__le32) + RBD_IMAGE_ID_LEN_MAX, GFP_NOIO);
> if (!response) {
> ret = -ENOMEM;
> goto out;
> --
> 2.10.0
>

How is this any better? If anything, it makes the first kmalloc() call
slightly less readable.

Thanks,

Ilya