linux-kernel - Re: [PATCH] HID: hid-sensor-custom: remove useless variable

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Date:   Sun, 11 Apr 2021 09:06:35 -0700
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>, jikos@...nel.org,
        benjamin.tissoires@...hat.com, linux-input@...r.kernel.org,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] HID: hid-sensor-custom: remove useless variable

On Sun, 2021-04-11 at 14:56 +0100, Jonathan Cameron wrote:
> On Fri, 09 Apr 2021 11:19:12 -0700
> Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com> wrote:
> 
> > On Fri, 2021-04-09 at 15:15 +0800, Jiapeng Chong wrote:
> > > Fix the following gcc warning:
> > > 
> > > drivers/hid/hid-sensor-custom.c:400:7: warning: variable ‘ret’
> > > set
> > > but
> > > not used [-Wunused-but-set-variable].
> > > 
> > > Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
> > > Signed-off-by: Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>  
> > Acked-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com
> 
> Perhaps better to return ret if it is non zero?
> I can't immediately figure out if there is a reason we know that
> can't
> happen.
Only time it can fail when there is no report descriptor or the field
index is >= report->maxfield.
But since the attribute is registered from the report descriptor and
index, this can't happen.
But we can enhance sensor_hub_set_feature() to fail when
 hid_set_field() fails. There is one case where field->logical_minimum
< 0  and value is out of range.

Thanks,
Srinivas


> 
> Jonathan
> 
> > > ---
> > >  drivers/hid/hid-sensor-custom.c | 5 ++---
> > >  1 file changed, 2 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/hid/hid-sensor-custom.c b/drivers/hid/hid-
> > > sensor-custom.c
> > > index 2628bc5..e430673 100644
> > > --- a/drivers/hid/hid-sensor-custom.c
> > > +++ b/drivers/hid/hid-sensor-custom.c
> > > @@ -397,15 +397,14 @@ static ssize_t store_value(struct device
> > > *dev,
> > > struct device_attribute *attr,
> > >  
> > >  	if (!strncmp(name, "value", strlen("value"))) {
> > >  		u32 report_id;
> > > -		int ret;
> > >  
> > >  		if (kstrtoint(buf, 0, &value) != 0)
> > >  			return -EINVAL;
> > >  
> > >  		report_id = sensor_inst->fields[field_index].attribute.
> > >  								report_
> > > id;
> > > -		ret = sensor_hub_set_feature(sensor_inst->hsdev,
> > > report_id,
> > > -					     index, sizeof(value),
> > > &value);
> > > +		sensor_hub_set_feature(sensor_inst->hsdev, report_id,
> > > index,
> > > +				       sizeof(value), &value);
> > >  	} else
> > >  		return -EINVAL;
> > >