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

SF Markus Elfring
2016-09-13T08:37:00Z

>> @@ -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;
…
> How is this any better?

I find it useful to omit the local variable "size" here.

> If anything, it makes the first kmalloc() call slightly less readable.

I got an other impression. The refactored function call did not fit into a single line
because of a well-known length limitation.

Does the kzalloc() call look a bit nicer for you now?

Regards,
Markus