lkml.org 
[lkml]   [2021]   [Sep]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH][next] rtc: msc313: Fix unintentional sign extension issue on left shift of a u16
Hi Romain,

On Tue, 28 Sept 2021 at 22:55, Romain Perier <romain.perier@gmail.com> wrote:
>
> Hi,
>
> Le mar. 28 sept. 2021 à 15:31, Daniel Palmer <daniel@0x0f.com> a écrit :
> The crazy stuff being, I ran rtctest from selftests and rtc-range (1)
> that tests a variety
> of dates including 2038 and 2106 for example. Both tests passed :) (probably
> because *this case* specifically did not happen while running the test)

I suspect it works because for reading the time because seconds is a
u32 not unsigned long like the other functions.
So if the high word of the register is read, is promoted to a wider
type and sign extended it doesn't actually matter because it gets
truncated to 32 bits so the sign extended part is gone.

Cheers,

Daniel

\
 
 \ /
  Last update: 2021-09-29 14:55    [W:0.045 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site