Re: [PATCH] tcp_lp: use 64-bit arithmetic instead of 32-bit

[Gustavo A. R. Silva]

Hi Alan,

Quoting Alan Cox <gnomes@xxxxxxxxxxxxxxxxxxx>:

> On Wed, 31 Jan 2018 18:24:07 -0600
> "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx> wrote:
>
> > Cast to s64 some variables and a macro in order to give the
> > compiler complete information about the proper arithmetic to
> > use. Notice that these elements are used in contexts that
> > expect expressions of type s64 (64 bits, signed).
> >
> > Currently such expression are being evaluated using 32-bit
> > arithmetic.
>
> The question you need to ask is 'can it overflow 32bit maths', otherwise
> you are potentially making the system do extra work for no reason.

Yeah, I get your point and it seems that in this particular case there  
is no risk of a 32bit overflow, but in general and IMHO as the code  
evolves, the use of incorrect arithmetic may have security  
implications in the future, so I advocate for code correctness in this  
case.

Thanks
--
Gustavo