linux-kernel - Re: [PATCH v2 4/8] power: supply: core: tabularize HWMON temperature labels

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Message-ID: <20200403165639.GA1966@qmqm.qmqm.pl>
Date:   Fri, 3 Apr 2020 18:56:39 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Andrey Smirnov <andrew.smirnov@...il.com>,
        Sebastian Reichel <sebastian.reichel@...labora.com>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 4/8] power: supply: core: tabularize HWMON temperature
 labels

On Fri, Apr 03, 2020 at 09:47:40AM -0700, Guenter Roeck wrote:
> On 4/3/20 9:23 AM, Michał Mirosław wrote:
> > Rework power_supply_hwmon_read_string() to check it's parameters.
> > This allows to extend it later with labels for other types of
> > measurements.
> > 
> > Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> > ---
> > v2: split from fix temperature labels
> > ---
> >  drivers/power/supply/power_supply_hwmon.c | 21 +++++++++++++++++++--
> >  1 file changed, 19 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/power/supply/power_supply_hwmon.c b/drivers/power/supply/power_supply_hwmon.c
> > index 67b6ee60085e..48c73994732c 100644
> > --- a/drivers/power/supply/power_supply_hwmon.c
> > +++ b/drivers/power/supply/power_supply_hwmon.c
> > @@ -43,6 +43,11 @@ static int power_supply_hwmon_curr_to_property(u32 attr)
> >  	}
> >  }
> >  
> > +static const char *const ps_temp_label[] = {
> > +	"temp",
> > +	"ambient temp",
> > +};
> > +
> >  static int power_supply_hwmon_temp_to_property(u32 attr, int channel)
> >  {
> >  	if (channel) {
> > @@ -144,8 +149,20 @@ static int power_supply_hwmon_read_string(struct device *dev,
> >  					  u32 attr, int channel,
> >  					  const char **str)
> >  {
> > -	*str = channel ? "temp ambient" : "temp";
> > -	return 0;
> > +	if (channel < 0)
> > +		return -EINVAL;
> > +
> 
> This is unnecessary.
> 
> > +	switch (type) {
> > +	case hwmon_temp:
> > +		if (channel >= ARRAY_SIZE(ps_temp_label))
> > +			return -EINVAL;
> 
> As is this. We don't usually check boundaries like this for
> in-kernel APIs, and I personally would not want to have it
> introduced in the kernel more than necessary. This just increases
> kernel image size with zero benefit.

I'll amend other patches in the same spirit, then. I like the code size
argument.

Best Regards,
Michał Mirosław