[1/2,v3] mmc: dw_mmc: Fix the DTO timeout overflow calculation for 32-bit systems

In commit 9d9491a7da2a ("mmc: dw_mmc: Fix the DTO timeout calculation") have been made
changes which cause multiply overflow for 32-bit systems.
The broken timeout calculations caused false interrupt latency warnings
and stacktrace splat (such as below) when accessing the 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
| mmc_host mmc0: Bus speed (slot 0) = 50000000Hz (slot req 400000Hz, actual
| 396825HZ div = 63)
| mmc_host mmc0: Bus speed (slot 0) = 50000000Hz (slot req 25000000Hz, actual
|  25000000HZ div = 1)
| ------------[ cut here ]------------
| softirq: huh, entered softirq 6 TASKLET 6f6a9412 with preempt_count 00000101,
| exited with 00000100?
| WARNING: CPU: 2 PID: 0 at ../lib/scatterlist.c:652 sg_miter_next+0x28/0x20c
| Modules linked in:
| CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.15.0 #57
|
| Stack Trace:
|  arc_unwind_core.constprop.1+0xd0/0xf4
|  dump_stack+0x68/0x80
|  warn_slowpath_null+0x4e/0xec
|  sg_miter_next+0x28/0x20c
|  dw_mci_read_data_pio+0x44/0x190
|  dw_mmc f000a000.mmc: Unexpected interrupt latency
|   dw_mci_interrupt+0x3ee/0x530
|  __handle_irq_event_percpu+0x56/0x150
|  handle_irq_event+0x34/0x78
|  handle_level_irq+0x8e/0x120
|  generic_handle_irq+0x1c/0x2c
|  idu_cascade_isr+0x30/0x6c
|  __handle_domain_irq+0x72/0xc8
|  ret_from_exception+0x0/0x8
|---[ end trace 2a58c9af6c25fe51 ]---

Lets cast this multiply to u64 type which prevents overflow.

Tested-by: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Fixes: ARC STAR 9001306872 HSDK, sdio: board crashes when copying big files

Signed-off-by: Evgeniy Didin <Evgeniy.Didin@synopsys.com>

CC: Alexey Brodkin <abrodkin@synopsys.com>
CC: Eugeniy Paltsev <paltsev@synopsys.com>
CC: Douglas Anderson <dianders@chromium.org>
CC: Ulf Hansson <ulf.hansson@linaro.org>
CC: linux-kernel@vger.kernel.org
CC: linux-snps-arc@lists.infradead.org
Cc: <stable@vger.kernel.org> #  9d9491a7da2a mmc: dw_mmc: Fix the DTO timeout calculation
---
Nothing changed since v2.
 drivers/mmc/host/dw_mmc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

On Mon, Feb 26, 2018 at 4:34 PM, Evgeniy Didin
<Evgeniy.Didin@synopsys.com> wrote:
> In commit 9d9491a7da2a ("mmc: dw_mmc: Fix the DTO timeout calculation") have been made
> changes which cause multiply overflow for 32-bit systems.
> The broken timeout calculations caused false interrupt latency warnings
> and stacktrace splat (such as below) when accessing the SD Card.

> +       drto_ms = DIV_ROUND_UP((u64)MSEC_PER_SEC * drto_clks * drto_div,
>                                host->bus_hz);

Same as per patch 2.

> Tested-by: Vineet Gupta <Vineet.Gupta1@synopsys.com>
> Fixes: ARC STAR 9001306872 HSDK, sdio: board crashes when copying big files
> 
> Signed-off-by: Evgeniy Didin <Evgeniy.Didin@synopsys.com>
> 
> CC: Alexey Brodkin <abrodkin@synopsys.com>
> CC: Eugeniy Paltsev <paltsev@synopsys.com>
> CC: Douglas Anderson <dianders@chromium.org>
> CC: Ulf Hansson <ulf.hansson@linaro.org>
> CC: linux-kernel@vger.kernel.org
> CC: linux-snps-arc@lists.infradead.org
> Cc: <stable@vger.kernel.org> #  9d9491a7da2a mmc: dw_mmc: Fix the DTO timeout calculation

As I said, the correct tag may be:

Reported-by: Vineet Gupta <Vineet.Gupta1@synopsys.com> # ARC STAR 
9001306872 HSDK, sdio: board crashes when copying big files
Tested-by: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Fixes: 9d9491a7da2a ("mmc: dw_mmc: Fix the DTO timeout calculation")
Cc: <stable@vger.kernel.org>
Signed-off-by: Evgeniy Didin <Evgeniy.Didin@synopsys.com>
...
...


> ---
> Nothing changed since v2.
>   drivers/mmc/host/dw_mmc.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 

> -	drto_ms = DIV_ROUND_UP(MSEC_PER_SEC * drto_clks * drto_div,
> +
> +	drto_ms = DIV_ROUND_UP((u64)MSEC_PER_SEC * drto_clks * drto_div,
>   			       host->bus_hz);
>   

Hmm?

#define DIV_ROUND_DOWN_ULL(ll, d) \
	({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; })

#define DIV_ROUND_UP_ULL(ll, d)		DIV_ROUND_DOWN_ULL((ll) + (d) - 1, (d))


It uses intermediate unsigned long long _tmp for your "multiply", namely
MSEC_PER_SEC * drto_clks * drto_div, which could solves the problem.
So I don't see why DIV_ROUND_UP_ULL can't work for you?


>   	/* add a bit spare time */
>

> 
> #define DIV_ROUND_DOWN_ULL(ll, d) \
>      ({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; })
> 
> #define DIV_ROUND_UP_ULL(ll, d)        DIV_ROUND_DOWN_ULL((ll) + (d) - 
> 1, (d))
> 
> 
> It uses intermediate unsigned long long _tmp for your "multiply", namely
> MSEC_PER_SEC * drto_clks * drto_div, which could solves the problem.
> So I don't see why DIV_ROUND_UP_ULL can't work for you?

Take back.  I misunderstood your "multiply", sorry.

> 
> 
>>       /* add a bit spare time */
>>
> 
> 
>

Hi Evgeniy,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.16-rc3 next-20180228]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Evgeniy-Didin/mmc-dw_mmc-Fix-the-DTO-timeout-overflow-calculation-for-32-bit-systems/20180228-141447
config: arm-exynos_defconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=arm 

All errors (new ones prefixed by >>):

   drivers/mmc/host/dw_mmc.o: In function `dw_mci_set_drto':
>> dw_mmc.c:(.text+0x1644): undefined reference to `__aeabi_uldivmod'

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