Re: [PATCH] eeepc-laptop: remove possible use of uninitialized value

Frans Klaver
2014-09-10T14:43:08Z

On Wed, Sep 10, 2014 at 5:33 AM, Darren Hart <dvhart@infradead.org> wrote:
> On Tue, Sep 09, 2014 at 10:50:08AM +0200, Paul Bolle wrote:
>> Hi Darren,
>>
>> On Sat, 2014-09-06 at 23:17 +0200, Rafael J. Wysocki wrote:
>> > On Friday, September 05, 2014 07:17:57 PM Darren Hart wrote:
>> > > On Thu, Sep 04, 2014 at 09:08:08AM +0200, Paul Bolle wrote:
>> > > [...]
>> > > > static ssize_t store_sys_acpi(struct device *dev, int cm,
>> > > > @@ -278,12 +276,13 @@ static ssize_t store_sys_acpi(struct device *dev, int cm,
>> > > > struct eeepc_laptop *eeepc = dev_get_drvdata(dev);
>> > > > int rv, value;
>> > > >
>> > > > - rv = parse_arg(buf, count, &value);
>> > > > - if (rv > 0)
>> > > > - value = set_acpi(eeepc, cm, value);
>> > > > + rv = parse_arg(buf, &value);
>> > > > + if (rv < 0)
>> > > > + return rv;
>> > > > + value = set_acpi(eeepc, cm, value);
>> > > > if (value < 0)
>> > >
>> > > I suppose it's harmless, but it would be more explicit to reuse rv here instead
>> > > of value.
>>
>> Fine with me.
>>
>> > > > return -EIO;
>> > >
>> > > And as with Frans' version, I suggest propogating the error. We're talking about
>> > > a missing/invalid ACPI control method name here, ENODEV seems approprirate.
>> > >
>> > > Rafael, do you have a strong preference about what to return in such an event?
>> >
>> > No, I don't, although -ENXIO could be used here too.
>>
>> If you could say what value you'd like best I'll resend using that
>> value. (I don't know what the effect is of using a specific error here,
>> so I guess I'll have to bluff about it in the commit explanation.)
>
> First, I would prefer we propogate the error code rather than remap it.
>
> We could consider changing what the callee returns...
>
> #define EIO 5 /* I/O error */
> #define ENXIO 6 /* No such device or address */
> #define ENODEV 19 /* No such device */
>
> Of those, ENXIO seems like the most appropriate in this case.

Would it be fair to say that for consistency we should then also
change the return values of acpi_setter_handle()? It has the same
basic layout and checks as set_acpi() and get_acpi() have.