Re: [PATCH] mmc: dw_mmc: Fix the DTO timeout overflow calculation for 32-bit systems

[Andy Shevchenko]

On Wed, Feb 21, 2018 at 7:57 PM, Evgeniy Didin
<Evgeniy.Didin@xxxxxxxxxxxx> wrote:
> In commit 9d9491a7da2a ("mmc: dw_mmc: Fix the DTO timeout calculation") have been made
> changes which can cause multiply overflow for 32-bit systems. It was caught on arc/hsdk board
> when "drto_ms" should be 671, but it was 70 and that caused a flow of stack-traces just copying
> file from mmc.
>
> Lets cast this multiply to long long int which prevents overflow.
>
> Signed-off-by: Evgeniy Didin <Evgeniy.Didin@xxxxxxxxxxxx>
> CC: Alexey Brodkin <abrodkin@xxxxxxxxxxxx>
> CC: Douglas Anderson <dianders@xxxxxxxxxxxx>
> CC: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> CC: linux-kernel@xxxxxxxxxxxxxxx
> CC: linux-snps-arc@xxxxxxxxxxxxxxxxxxx

> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -1944,7 +1944,7 @@ static void dw_mci_set_drto(struct dw_mci *host)
>         drto_div = (mci_readl(host, CLKDIV) & 0xff) * 2;
>         if (drto_div == 0)
>                 drto_div = 1;
> -       drto_ms = DIV_ROUND_UP(MSEC_PER_SEC * drto_clks * drto_div,
> +       drto_ms = DIV_ROUND_UP((uint64_t)MSEC_PER_SEC * drto_clks * drto_div,
>                                host->bus_hz);

Does the driver use uint64_t elsewhere?
Or simple u64?

-- 
With Best Regards,
Andy Shevchenko