Re: [PATCH v14 1/3] safemath: Add ALIGN_UP_OVF() that checks for {over,under}flow

[Gao Xiang]

On 2024/5/18 17:20, Vladimir 'phcoder' Serbinenko wrote:
> Le ven. 17 mai 2024, 21:26, Gao Xiang <hsiangkao@linux.alibaba.com 
> <mailto:hsiangkao@linux.alibaba.com>> a écrit :
>
>     Hi Vladimir,
>
>     On 2024/5/18 00:38, Vladimir 'phcoder' Serbinenko wrote:
>      > I think that given that align is a non zero const we can trust it.
>
>       From the EROFS specific cases, they are always non-zero values,
>     So I agree with you on this..
>
>     Yet Daniel said ".. Be careful with underflows too." in
>     Zkcv7G7MJBg8sKiE@tomti.i.net-space.pl">https://lore.kernel.org/r/Zkcv7G7MJBg8sKiE@tomti.i.net-space.pl 
> <Zkcv7G7MJBg8sKiE@tomti.i.net-space.pl">https://lore.kernel.org/r/Zkcv7G7MJBg8sKiE@tomti.i.net-space.pl>
>     although I'm not quite sure but I guess like this.
>
>     Also as a generic helper, I think `align` could be zero if it's
>     a variable..
>
>
> It's rare for align to be a variable and then additional checks are needed that 
> align is a power of 2. And power of 2 is never zero. This check is better done 
> on the caller side. You just need a comment specify that it's caller 
> responsibility to check it.

I'd like to know Daniel's comment about this first, there are already
too many comments out of nits.  I'm fine with updating such nits but
I would like to confirm _which comment_ I should follow for
upstreaming.

Thanks,
Gao Xiang

>     Anyway, either way works for EROFS.   I just try my best to do
>     what I could do for this first series for upstreaming and we
>     could move forward to the next step..
>
>     Thanks,
>     Gao Xiang