Potential bug in queue_count_set

[luzmaximilian@gmail.com (Maximilian Luz)]

>>>
>>> It looks like lines 154, 155 don't achieve anything as `n` is not being
>>> used afterwards. Sorry if this is already known or a non-issue, just
>>> wanted to let you guys know.
>>>
>>
>> It looks like module parameter "write_queues" is set to the actual given
>> value (val) without considering reduced number of queues in case given
>> value is greater than nr_cpus.
>>
>> I think that might need sprintf() or something like this to make the
>> actual value reduced in that case.
> 
> 
> Sorry, the "val" is const so that we cannot go through it with sprintf().
> My bad.  This function might return an error if invalid number is given.
> 
> Sorry for the confusion.
> 
> Have posted patches for it.
>    http://lists.infradead.org/pipermail/linux-nvme/2019-April/023369.html

I honestly know too little about module-parameters to give a qualified
answer here, but could returning -EINVAL here break things?

 From what I can tell it should be possible to bypass the param_set_int
function and set *(kp->arg) directly, which would reproduce the
param_set_int functionality (kernel/params.c:223).

Alternatively one could argue that after a successful kstrtoint call, we
can strncpy the input into a buffer with fixed length of 11 (10 digits +
null, if I'm not mistaken) and use that as input for param_set_int.