Re: [PATCH v2] extcon: fix extcon_get_extcon_dev() error handling

Hi,

On 12/16/21 09:05, Dan Carpenter wrote:

On Thu, Dec 16, 2021 at 05:24:30PM +0900, Chanwoo Choi wrote:

quoted

On 12/16/21 4:52 PM, Dan Carpenter wrote:

quoted

On Thu, Dec 16, 2021 at 03:39:46PM +0900, Chanwoo Choi wrote:

quoted

Hi Dan,

First of all,  sorry for late reply.

There is one issue. About this issue, I already discussed on patch[1]
[1] https://lore.kernel.org/lkml/5BEB63C3.1020504@samsung.com/ (local)  

extcon_get_extcon_dev() is used for anywhere except for probe step.
But EPROBE_DEFER is only used on probe step.

So that it is not clear to return EPROBE_DEFER from extcon_get_extcon_dev()
because extcon_get_extcon_dev() never know either call it on probe function
or not.

Currently extcon_get_extcon_dev() is only called from probe so it's not
an issue.

Even if extcon_get_extcon_dev() is used on probe until now,
it is possible to use on anywhere as I commented.

It is difficult to agree this approach without any other solution.

Basically, the subsystem core never know either probe time or not.
It means that this issue should be handled in each device driver.

To be honest, I'm not sure how this differs from other functions which
return -EPROBE_DEFER.  How do other functions guarantee they will only
be called from probe()?

Right I have to agree with Dan here, all "get" functons for resources
like gpios, clks, regulators, phys, pwms, etc. may return -EPROBE_DEFER
and since these functions may return -EPROBE_DEFER they *must* only be
called from a driver's probe() function.

So I believe that the solution here is to simply add a kernel-doc comment
on extcon_get_extcon_dev() which documents that it may return -EPROBE_DEFER
and that it thus *must* only be called from a driver's probe() function.

Regards,

Hans

regards,
dan carpenter