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From:   Yi-ming Tseng <yimingtseng@google.com>
Date:   Wed, 21 Jun 2023 16:39:58 +0800
Message-ID: <CAA5JqK5MUv-uC1xFNUB-TzjYH-J7VONGcFu2Em6OQnKL2C13Tg@mail.gmail.com>
Subject: Re: [PATCH] PM: domains: fix overflow in genpd_parse_state
To:     "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     Ulf Hansson <ulf.hansson@linaro.org>,
        Kevin Hilman <khilman@kernel.org>,
        Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
        marscheng@google.com, n.zhandarovich@fintech.ru
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Oh I just found there is a similar patch from Nikita Zhandarovich
and it will be applied in v6.5. I think we can drop this patch. Thanks
and sorry for duplicated patches.

The patch from Nikita Zhandarovich and the discussion:
https://lore.kernel.org/all/CAJZ5v0gx7bD9EZKPQWyAAZ6hSKjK4hr-nkrJu84HEK-g2A=
MAaw@mail.gmail.com/

Thanks again.

On Sat, Jun 17, 2023 at 1:44=E2=80=AFAM Rafael J. Wysocki <rafael@kernel.or=
g> wrote:
>
> On Tue, May 30, 2023 at 1:42=E2=80=AFPM YiMing Tseng <yimingtseng@google.=
com> wrote:
> >
> > Add type casters to prevent 32-bit overflow before assigning to s64
> > variables. It allows full 32-bit range support for latency and
> > residency.
>
> OK, but is it really a practical problem?
>
> Ulf, what do you think?
>
> > Signed-off-by: YiMing Tseng <yimingtseng@google.com>
> > ---
> >  drivers/base/power/domain.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> > index 32084e38b73d..26a04cd8d8dc 100644
> > --- a/drivers/base/power/domain.c
> > +++ b/drivers/base/power/domain.c
> > @@ -2939,10 +2939,10 @@ static int genpd_parse_state(struct genpd_power=
_state *genpd_state,
> >
> >         err =3D of_property_read_u32(state_node, "min-residency-us", &r=
esidency);
> >         if (!err)
> > -               genpd_state->residency_ns =3D 1000 * residency;
> > +               genpd_state->residency_ns =3D (s64)1000 * residency;
> >
> > -       genpd_state->power_on_latency_ns =3D 1000 * exit_latency;
> > -       genpd_state->power_off_latency_ns =3D 1000 * entry_latency;
> > +       genpd_state->power_on_latency_ns =3D (s64)1000 * exit_latency;
> > +       genpd_state->power_off_latency_ns =3D (s64)1000 * entry_latency=
;
> >         genpd_state->fwnode =3D &state_node->fwnode;
> >
> >         return 0;
> > --