* [PATCH] power: supply: da9150: use div64_u64() instead of do_div()
@ 2022-02-09 8:39 Qing Wang
2022-02-11 20:50 ` Sebastian Reichel
0 siblings, 1 reply; 4+ messages in thread
From: Qing Wang @ 2022-02-09 8:39 UTC (permalink / raw)
To: Support Opensource, Sebastian Reichel, linux-pm, linux-kernel; +Cc: Wang Qing
From: Wang Qing <wangqing@vivo.com>
do_div() does a 64-by-32 division.
When the divisor is u64, do_div() truncates it to 32 bits, this means it
can test non-zero and be truncated to zero for division.
fix do_div.cocci warning:
do_div() does a 64-by-32 division, please consider using div64_u64 instead.
Signed-off-by: Wang Qing <wangqing@vivo.com>
---
drivers/power/supply/da9150-fg.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/power/supply/da9150-fg.c b/drivers/power/supply/da9150-fg.c
index 6e36782..896491a
--- a/drivers/power/supply/da9150-fg.c
+++ b/drivers/power/supply/da9150-fg.c
@@ -250,7 +250,7 @@ static int da9150_fg_current_avg(struct da9150_fg *fg,
div = (u64) (sd_gain * shunt_val * 65536ULL);
do_div(div, 1000000);
res = (u64) (iavg * 1000000ULL);
- do_div(res, div);
+ div64_u64(res, div);
val->intval = (int) res;
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] power: supply: da9150: use div64_u64() instead of do_div()
2022-02-09 8:39 [PATCH] power: supply: da9150: use div64_u64() instead of do_div() Qing Wang
@ 2022-02-11 20:50 ` Sebastian Reichel
2022-02-11 20:53 ` Christophe JAILLET
0 siblings, 1 reply; 4+ messages in thread
From: Sebastian Reichel @ 2022-02-11 20:50 UTC (permalink / raw)
To: Qing Wang; +Cc: Support Opensource, linux-pm, linux-kernel
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Hi,
On Wed, Feb 09, 2022 at 12:39:46AM -0800, Qing Wang wrote:
> From: Wang Qing <wangqing@vivo.com>
>
> do_div() does a 64-by-32 division.
> When the divisor is u64, do_div() truncates it to 32 bits, this means it
> can test non-zero and be truncated to zero for division.
>
> fix do_div.cocci warning:
> do_div() does a 64-by-32 division, please consider using div64_u64 instead.
>
> Signed-off-by: Wang Qing <wangqing@vivo.com>
> ---
Thanks, queued.
-- Sebastian
> drivers/power/supply/da9150-fg.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/power/supply/da9150-fg.c b/drivers/power/supply/da9150-fg.c
> index 6e36782..896491a
> --- a/drivers/power/supply/da9150-fg.c
> +++ b/drivers/power/supply/da9150-fg.c
> @@ -250,7 +250,7 @@ static int da9150_fg_current_avg(struct da9150_fg *fg,
> div = (u64) (sd_gain * shunt_val * 65536ULL);
> do_div(div, 1000000);
> res = (u64) (iavg * 1000000ULL);
> - do_div(res, div);
> + div64_u64(res, div);
>
> val->intval = (int) res;
>
> --
> 2.7.4
>
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] power: supply: da9150: use div64_u64() instead of do_div()
2022-02-11 20:50 ` Sebastian Reichel
@ 2022-02-11 20:53 ` Christophe JAILLET
2022-02-11 21:40 ` Sebastian Reichel
0 siblings, 1 reply; 4+ messages in thread
From: Christophe JAILLET @ 2022-02-11 20:53 UTC (permalink / raw)
To: Sebastian Reichel, Qing Wang; +Cc: Support Opensource, linux-pm, linux-kernel
Le 11/02/2022 à 21:50, Sebastian Reichel a écrit :
> Hi,
>
> On Wed, Feb 09, 2022 at 12:39:46AM -0800, Qing Wang wrote:
>> From: Wang Qing <wangqing@vivo.com>
>>
>> do_div() does a 64-by-32 division.
>> When the divisor is u64, do_div() truncates it to 32 bits, this means it
>> can test non-zero and be truncated to zero for division.
>>
>> fix do_div.cocci warning:
>> do_div() does a 64-by-32 division, please consider using div64_u64 instead.
>>
>> Signed-off-by: Wang Qing <wangqing@vivo.com>
>> ---
>
> Thanks, queued.
All these patches are broken and should be NACKed, fixed or reverted if
applied.
See [1].
CJ
[1]:
https://lore.kernel.org/linux-kernel/19b96972-cee7-937f-21ce-c78982ed2048@linaro.org/
>
> -- Sebastian
>
>> drivers/power/supply/da9150-fg.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/power/supply/da9150-fg.c b/drivers/power/supply/da9150-fg.c
>> index 6e36782..896491a
>> --- a/drivers/power/supply/da9150-fg.c
>> +++ b/drivers/power/supply/da9150-fg.c
>> @@ -250,7 +250,7 @@ static int da9150_fg_current_avg(struct da9150_fg *fg,
>> div = (u64) (sd_gain * shunt_val * 65536ULL);
>> do_div(div, 1000000);
>> res = (u64) (iavg * 1000000ULL);
>> - do_div(res, div);
>> + div64_u64(res, div);
>>
>> val->intval = (int) res;
>>
>> --
>> 2.7.4
>>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] power: supply: da9150: use div64_u64() instead of do_div()
2022-02-11 20:53 ` Christophe JAILLET
@ 2022-02-11 21:40 ` Sebastian Reichel
0 siblings, 0 replies; 4+ messages in thread
From: Sebastian Reichel @ 2022-02-11 21:40 UTC (permalink / raw)
To: Christophe JAILLET; +Cc: Qing Wang, Support Opensource, linux-pm, linux-kernel
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Hi,
On Fri, Feb 11, 2022 at 09:53:08PM +0100, Christophe JAILLET wrote:
> Le 11/02/2022 à 21:50, Sebastian Reichel a écrit :
> > Hi,
> >
> > On Wed, Feb 09, 2022 at 12:39:46AM -0800, Qing Wang wrote:
> > > From: Wang Qing <wangqing@vivo.com>
> > >
> > > do_div() does a 64-by-32 division.
> > > When the divisor is u64, do_div() truncates it to 32 bits, this means it
> > > can test non-zero and be truncated to zero for division.
> > >
> > > fix do_div.cocci warning:
> > > do_div() does a 64-by-32 division, please consider using div64_u64 instead.
> > >
> > > Signed-off-by: Wang Qing <wangqing@vivo.com>
> > > ---
> >
> > Thanks, queued.
>
> All these patches are broken and should be NACKed, fixed or reverted if
> applied.
>
> See [1].
>
> CJ
>
> [1]: https://lore.kernel.org/linux-kernel/19b96972-cee7-937f-21ce-c78982ed2048@linaro.org/
Oops, thanks for the hint. Patch dropped. I actually missed the
do_div(div, 1000000) during my review (probably should go sleeping),
so div should be within safe range in the second do_div() anyways.
-- Sebastian
>
> >
> > -- Sebastian
> >
> > > drivers/power/supply/da9150-fg.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/power/supply/da9150-fg.c b/drivers/power/supply/da9150-fg.c
> > > index 6e36782..896491a
> > > --- a/drivers/power/supply/da9150-fg.c
> > > +++ b/drivers/power/supply/da9150-fg.c
> > > @@ -250,7 +250,7 @@ static int da9150_fg_current_avg(struct da9150_fg *fg,
> > > div = (u64) (sd_gain * shunt_val * 65536ULL);
> > > do_div(div, 1000000);
> > > res = (u64) (iavg * 1000000ULL);
> > > - do_div(res, div);
> > > + div64_u64(res, div);
> > > val->intval = (int) res;
> > > --
> > > 2.7.4
> > >
>
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^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-02-11 21:40 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2022-02-09 8:39 [PATCH] power: supply: da9150: use div64_u64() instead of do_div() Qing Wang
2022-02-11 20:50 ` Sebastian Reichel
2022-02-11 20:53 ` Christophe JAILLET
2022-02-11 21:40 ` Sebastian Reichel
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