Re: [PATCH] padata: Fix possible divide-by-0 panic in padata_mt_helper()

[Waiman Long <longman@redhat.com>]

On 8/10/24 23:13, Herbert Xu wrote:
> On Sat, Aug 10, 2024 at 11:11:07PM -0400, Waiman Long wrote:
>>> Unless I'm missing something chunk_size cannot be zero before the
>>> division because that's the first thing we check upon entry into
>>> this function.
>> chunk_size is initialized as
>>
>> ps.chunk_size = job->size / (ps.nworks * load_balance_factor);
>>
>> chunk_size will be 0 if job->size < (ps.nworks * load_balance_factor). If
>> min_chunk is 0, chunk_size will remain 0.
> That's why I was suggesting that you replace the division by
> DIV_ROUND_UP.  That should ensure that ps.chunk_size is not zero.

Now I see what you mean. Yes, we can probably change that to a 
DIV_ROUND_UP operation to make sure that chunk_size is at least one 
unless job->size is 0. I still think the current patch is a bit more 
fail-safe.

Cheers, Longman