Re: [RFC PATCH 1/7] drivers: base: Add resource managed version of delayed work init

[Guenter Roeck]

On 2/13/21 7:59 AM, Hans de Goede wrote:
> Hi,
> 
> On 2/13/21 4:27 PM, Guenter Roeck wrote:
>> On 2/13/21 7:03 AM, Hans de Goede wrote:
>> [ ... ]
>>>
>>> I think something like this should work:
>>>
>>> static int devm_delayed_work_autocancel(struct device *dev, struct delayed_work *w,
>>> 					void (*worker)(struct work_struct *work)) {
>>> 	INIT_DELAYED_WORK(w, worker);
>>> 	return devm_add_action(dev, (void (*action)(void *))cancel_delayed_work_sync, w);
>>> }
>>>
>>> I'm not sure about the cast, that may need something like this instead:
>>>
>>> typedef void (*devm_action_func)(void *);
>>>
>>> static int devm_delayed_work_autocancel(struct device *dev, struct delayed_work *w,
>>> 					void (*worker)(struct work_struct *work)) {
>>> 	INIT_DELAYED_WORK(w, worker);
>>> 	return devm_add_action(dev, (devm_action_func)cancel_delayed_work_sync, w);
>>
>> Unfortunately, you can not type cast function pointers in C. It is against the C ABI.
>> I am sure it is done in a few places in the kernel anyway, but those are wrong.
> 
> I see, bummer.
> 
>> This is the reason why many calls to devm_add_action() point to functions such as
>>
>> static void visconti_clk_disable_unprepare(void *data)
>> {
>>         clk_disable_unprepare(data);
>> }
>>
>> which could otherwise be handled using typecasts.
> 
> Hmm, wouldn't something like this be a candidate for adding a:
> 
> devm_clk_prepare_enable() helper?
> 
> This seems better then having the driver(s) make + error check separate
> clk_prepare_enable() + devm_add_action_or_reset() calls ?
> 

I don't really want to go there anymore. The maintainer rejected it several times.

Guenter