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

From: Guenter Roeck <linux@roeck-us.net>
To: Hans de Goede <hdegoede@redhat.com>,
	Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>,
	mazziesaccount@gmail.com
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	MyungJoo Ham <myungjoo.ham@samsung.com>,
	Chanwoo Choi <cw00.choi@samsung.com>,
	Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Jean Delvare <jdelvare@suse.com>,
	Mark Gross <mgross@linux.intel.com>,
	Sebastian Reichel <sre@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>,
	Wim Van Sebroeck <wim@linux-watchdog.org>,
	Saravana Kannan <saravanak@google.com>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Joerg Roedel <jroedel@suse.de>,
	Dan Williams <dan.j.williams@intel.com>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	linux-hwmon@vger.kernel.org, platform-driver-x86@vger.kernel.org,
	linux-pm@vger.kernel.org, linux-watchdog@vger.kernel.org
Subject: Re: [RFC PATCH 1/7] drivers: base: Add resource managed version of delayed work init
Date: Sat, 13 Feb 2021 10:17:29 -0800	[thread overview]
Message-ID: <7fc66c14-5dc5-d7b4-60ec-060bcf2d78cf@roeck-us.net> (raw)
In-Reply-To: <16140f5b-c504-1c07-9f0c-3813d686d157@redhat.com>

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