linux-kernel - Re: [PATCH v4] mmc: dw_mmc: Fix the DTO/CTO timeout overflow calculation for 32-bit systems

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Date:   Wed, 28 Feb 2018 17:47:45 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Evgeniy Didin <Evgeniy.Didin@...opsys.com>
Cc:     linux-mmc@...r.kernel.org,
        Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        Douglas Anderson <dianders@...omium.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Jisheng Zhang <Jisheng.Zhang@...aptics.com>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Vineet Gupta <Vineet.Gupta1@...opsys.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-snps-arc@...ts.infradead.org, Stable <stable@...r.kernel.org>
Subject: Re: [PATCH v4] mmc: dw_mmc: Fix the DTO/CTO timeout overflow
 calculation for 32-bit systems

On Wed, Feb 28, 2018 at 1:53 PM, Evgeniy Didin
<Evgeniy.Didin@...opsys.com> wrote:
> In commit 9d9491a7da2a ("mmc: dw_mmc: Fix the DTO timeout calculation") and
> commit 4c2357f57dd5 ("mmc: dw_mmc: Fix the CTO timeout calculation")
> have been made changes which cause multiply overflow for 32-bit systems.
> The broken timeout calculations leads to unexpected ETIMEDOUT errors and
> causes stacktrace splat (such as below) during normal data exchange
> with SD-card.
>
> | Running :  4M-check-reassembly-tcp-cmykw2-rotatew2.out -v0 -w1
> | -  Info: Finished target initialization.
> | mmcblk0: error -110 transferring data, sector 320544, nr 2048, cmd response
> |  0x900, card status 0x0
>
> DIV_ROUND_UP_ULL helps to escape usage of __udivdi3() from libgcc and so
> code gets compiled on all 32-bit platforms as opposed to usage
> of DIV_ROUND_UP when we may only compile stuff on a very few arches.
>
> Lets cast this multiply to u64 type which prevents overflow.
>

FWIW,
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Tested-by: Vineet Gupta <Vineet.Gupta1@...opsys.com>
> Reported-by: Vineet Gupta <Vineet.Gupta1@...opsys.com> # ARC STAR 9001306872 HSDK, sdio: board crashes when copying big files
> Fixes: 9d9491a7da2a ("mmc: dw_mmc: Fix the DTO timeout calculation")
> Fixes: 4c2357f57dd5 ("mmc: dw_mmc: Fix the CTO timeout calculation")
>
> Signed-off-by: Evgeniy Didin <Evgeniy.Didin@...opsys.com>
>
> CC: Alexey Brodkin <abrodkin@...opsys.com>
> CC: Eugeniy Paltsev <paltsev@...opsys.com>
> CC: Douglas Anderson <dianders@...omium.org>
> CC: Ulf Hansson <ulf.hansson@...aro.org>
> CC: Andy Shevchenko <andy.shevchenko@...il.com>
> CC: Jisheng Zhang <Jisheng.Zhang@...aptics.com>
> CC: Shawn Lin <shawn.lin@...k-chips.com>
> CC: Vineet Gupta <Vineet.Gupta1@...opsys.com>
> CC: linux-kernel@...r.kernel.org
> CC: linux-snps-arc@...ts.infradead.org
> Cc: <stable@...r.kernel.org>
> ---
> Changes since v3:
> -Switch DIV_ROUND_UP macro to DIV_ROUND_UP_ULL
> -Make one patch from two patches
> -Modify commit message
>
> Changes sinve v2:
> -add fix for cto_ms
>
> Changes since v1:
> -uint64_t switched to u64
>
>  drivers/mmc/host/dw_mmc.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 0aa39975f33b..cba534d4c81b 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -409,7 +409,9 @@ static inline void dw_mci_set_cto(struct dw_mci *host)
>         cto_div = (mci_readl(host, CLKDIV) & 0xff) * 2;
>         if (cto_div == 0)
>                 cto_div = 1;
> -       cto_ms = DIV_ROUND_UP(MSEC_PER_SEC * cto_clks * cto_div, host->bus_hz);
> +
> +       cto_ms = DIV_ROUND_UP_ULL((u64)MSEC_PER_SEC * cto_clks * cto_div,
> +                                 host->bus_hz);
>
>         /* add a bit spare time */
>         cto_ms += 10;
> @@ -1944,8 +1946,9 @@ 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,
> -                              host->bus_hz);
> +
> +       drto_ms = DIV_ROUND_UP_ULL((u64)MSEC_PER_SEC * drto_clks * drto_div,
> +                                  host->bus_hz);
>
>         /* add a bit spare time */
>         drto_ms += 10;
> --
> 2.11.0
>



-- 
With Best Regards,
Andy Shevchenko