Re: [PATCH V2 1/1] null_blk: add moddule parameter check

[Damien Le Moal <dlemoal@kernel.org>]

On 4/11/23 02:47, Nitesh Shetty wrote:
>> static int g_gb = 250;
>> -module_param_named(gb, g_gb, int, 0444);
>> +NULL_PARAM(gb, 1, INT_MAX);
> 
> This value gets converted to mb, for dev->size calculation in
> null_alloc_dev. I think either there should be a type conversion or
> this module parameter max value can be reduced to smaller value.

Yeah, good catch. it is multiplied by 1024, and assigned to dev->size which is
an unsigned long. So that could overflow on 32-bits arch. So this needs some fixing.

I would still allow a very large value as possible though, to allow testing for
overflows.

> 
>> +device_param_cb(gb, &null_gb_param_ops, &g_gb, 0444);
>> MODULE_PARM_DESC(gb, "Size in GB");

Chaitanya,

Another thing: did you check if setting all these arguments through configfs
also gets the same min/max value treatment ? Ideally, we want both configuration
interfaces (module args and configfs) to be equivalent.

(Note: please use dlemoal@kernel.org. wdc.com addresses do not work right now)