linux-kernel - Re: [PATCH] staging: pi433: use div

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 28 Jul 2017 16:26:42 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Marcus Wolf <marcus.wolf@...f-entwicklungen.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devel@...verdev.osuosl.org
Subject: Re: [PATCH] staging: pi433: use div_u64 for 64-bit division

On Fri, Jul 28, 2017 at 4:21 PM, Marcus Wolf
<marcus.wolf@...f-entwicklungen.de> wrote:
> Hi Arnd,
>
> we already have a patch for this:
> [PATCH 1/1] staging: pi433: fix problem with division in rf69_set_deviation
>  from 20.07.2017
>
> Maybe I did something wrong, but my first solution was exactly like your
> proposal. As far as I remeber, I wasn't able to compile it that way. Therefore I
> made a little bit more complicated fix. If I did something wrong and yours is
> fine, we should go for yours, because it is a shorter solution.

I think the problem with your original patch is that it doesn't work
for 'u64 factor':
do_div() is a bit tricky to work with, and it does not always accept a 64-bit
divisor, while div_u64 will simply convert the divisor to a u32.

You can also make 'factor' a 'u32' and keep using do_div.

        Arnd