Re: [PATCH] net: stmmac: Move debugfs init/exit to ->probe()/->remove()

[Jose Abreu]

On 26-11-2018 15:34, Thierry Reding wrote:
> On Fri, Nov 23, 2018 at 12:44:02PM +0000, Jose Abreu wrote:
>> On 23-11-2018 12:21, Thierry Reding wrote:
>>> From: Thierry Reding <treding@xxxxxxxxxx>
>>>
>>> Setting up and tearing down debugfs is current unbalanced, as seen by
>>> this error during resume from suspend:
>>>
>>>     [  752.134067] dwc-eth-dwmac 2490000.ethernet eth0: ERROR failed to create debugfs directory
>>>     [  752.134347] dwc-eth-dwmac 2490000.ethernet eth0: stmmac_hw_setup: failed debugFS registration
>>>
>>> The imbalance happens because the driver creates the debugfs hierarchy
>>> when the device is opened and tears it down when the device is closed.
>>> There's little gain in that, and it could be argued that it is even
>>> surprising because it's not usually done for other devices. Fix the
>>> imbalance by moving the debugfs creation and teardown to the driver's
>>> ->probe() and ->remove() implementations instead.
>>>
>>> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
>>> ---
>>>
>> Did you test trying to dump "descriptors_status" file when
>> interface is not open ? I think that's the main reason why this
>> is not in probe ...
> Indeed, that seems to cause a hang. Still, it doesn't sound like the
> right things to repeatedly create and remove debugfs files just because
> we can't provide the contents when the device is down.

Agree.

>
> How about we return an empty file or an error code instead when the
> interface is down?

I think an error code would be more suitable (ENODEV/EBUSY ?).
Can you submit v2 ?

Thanks and Best Regards,
Jose Miguel Abreu

>
> Thierry