Re: [PATCH] sbsa_gwdt: Calculate timeout with 64-bit math

[Guenter Roeck]

On 10/14/23 02:12, Darren Hart wrote:
> On Tue, Sep 26, 2023 at 05:45:13AM -0700, Guenter Roeck wrote:
> > On Thu, Sep 21, 2023 at 02:02:36AM -0700, Darren Hart wrote:
> > > Commit abd3ac7902fb ("watchdog: sbsa: Support architecture version 1")
> > > introduced new timer math for watchdog revision 1 with the 48 bit offset
> > > register.
> > >
> > > The gwdt->clk and timeout are u32, but the argument being calculated is
> > > u64. Without a cast, the compiler performs u32 operations, truncating
> > > intermediate steps, resulting in incorrect values.
> > >
> > > A watchdog revision 1 implementation with a gwdt->clk of 1GHz and a
> > > timeout of 600s writes 3647256576 to the one shot watchdog instead of
> > > 300000000000, resulting in the watchdog firing in 3.6s instead of 600s.
> > >
> > > Force u64 math by casting the first argument (gwdt->clk) as a u64. Make
> > > the order of operations explicit with parenthesis.
> > >
> > > Fixes: abd3ac7902fb ("watchdog: sbsa: Support architecture version 1")
> > > Reported-by: Vanshidhar Konda <vanshikonda@xxxxxxxxxxxxxxxxxxxxxx>
> > > Signed-off-by: Darren Hart <darren@xxxxxxxxxxxxxxxxxxxxxx>
> > > Cc: Wim Van Sebroeck <wim@xxxxxxxxxxxxxxxxxx>
> > > Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> > > Cc: linux-watchdog@xxxxxxxxxxxxxxx
> > > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > > Cc: <stable@xxxxxxxxxxxxxxx> # 5.14.x
> >
> > Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
>
> Guenter or Wim, I haven't seen this land in the RCs or in next yet. Have
> you already picked it up? Anything more needed from me?
>
> Thanks,

Sorry, I am suffering from what I can only describe as a severe case of
maintainer/reviewer PTSD, and I have yet to find a way of dealing with that.

Guenter