Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Rahul Rameshbabu via ltp <ltp@lists.linux.it>]

On Wed, 28 Jun, 2023 22:46:32 +0200 Andrew Lunn <andrew@lunn.ch> wrote:
> On Wed, Jun 28, 2023 at 01:38:50PM -0700, Jakub Kicinski wrote:
>> On Wed, 28 Jun 2023 03:16:43 +0200 Andrew Lunn wrote:
>> > > +	} else if (attr == &dev_attr_max_phase_adjustment.attr) {
>> > > +		if (!info->adjphase || !info->getmaxphase)
>> > > +			mode = 0;  
>> > 
>> > Maybe it is time to turn this into a switch statement?
>> 
>> I don't think we can switch on pointers in C.
>
> https://elixir.bootlin.com/linux/latest/source/drivers/net/phy/sfp.c#L749
>
> Works for temperature sensors, voltage sensors, current sensors, and
> power sensors. Maybe hwmon is different to what is going on here, but
> both a sysfs files.

Sorry, the only switch cases I see in the link you shared are for an
integral type enum and a u32. I do not see a pointer type being used in
a switch in sfp_hwmon_is_visible?

I believe Jakub is right about pointer types + switches in C. pointer
types are not considered integral types. Here is a compiler explorer
example to demonstrate. This slipped my mind during our discussion.

https://godbolt.org/z/nKr3x7cT8

  <source>: In function 'main':
  <source>:6:13: error: switch quantity not an integer
      6 |     switch (data) {
        |             ^~~~
  Compiler returned: 1

-- Rahul Rameshbabu

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