Re: [PATCH v1] drivers/hwmon/adm9240: fix data race in adm9240_fan_read

[Li Zhong <floridsleeves@xxxxxxxxx>]

On Thu, Sep 22, 2022 at 4:45 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> On 9/22/22 16:33, Li Zhong wrote:
> > In
> > adm9240_read()
> >    adm9240_fan_read()
> >      adm9240_write_fan_div(),
> >
> > it assumes that the caller of adm9240_write_fan_div() must hold
> > data->update_lock. Otherwise, it may cause data races when data is
> > updated by other threads.
> >
> > Signed-off-by: Li Zhong <floridsleeves@xxxxxxxxx>
> > ---
> >   drivers/hwmon/adm9240.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/hwmon/adm9240.c b/drivers/hwmon/adm9240.c
> > index 483cd757abd3..d93ae3147994 100644
> > --- a/drivers/hwmon/adm9240.c
> > +++ b/drivers/hwmon/adm9240.c
> > @@ -501,6 +501,7 @@ static int adm9240_fan_read(struct device *dev, u32 attr, int channel, long *val
> >
> >       switch (attr) {
> >       case hwmon_fan_input:
> > +             mutex_lock(&data->update_lock);
> >               err = regmap_read(data->regmap, ADM9240_REG_FAN(channel), &regval);
> >               if (err < 0)
> >                       return err;
>
> The mutex needs to be released here.
>
> > @@ -511,6 +512,7 @@ static int adm9240_fan_read(struct device *dev, u32 attr, int channel, long *val
> >                       if (err)
> >                               return err;
> >               }
> > +             mutex_unlock(&data->update_lock);
> >               *val = FAN_FROM_REG(regval, BIT(data->fan_div[channel]));
> >               break;
> >       case hwmon_fan_div:
>

Thanks. Fixed in v2 patch.