Hi,

On 2/15/21 8:22 AM, Vaittinen, Matti wrote:

On Sat, 2021-02-13 at 16:59 +0100, Hans de Goede wrote:

quoted

Hi,

On 2/13/21 4:27 PM, Guenter Roeck wrote:

quoted

On 2/13/21 7:03 AM, Hans de Goede wrote:
[ ... ]

quoted

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.

I think using devm_add_action() is still a good idea.

Yes, we could also just have a 1 line static inline function to do
the function-cast. Like this:

static inline void devm_delayed_work_autocancel_func(void *work)
{
	cancel_delayed_work_sync(work);
}

static inline 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_delayed_work_autocancel_func, w);
}

Both functions will then simply be compiled out in files which do not
use them.

quoted

If we add a devm_clk_prepare_enable() helper that should probably be
added
to drivers/clk/clk-devres.c and not to drivers/base/devres.c .

I also still wonder if we cannot find a better place for this new
devm_delayed_work_autocancel() helper but nothing comes to mind.

I don't like the idea of including device.h from workqueue.h - and I
think this would be necessary if we added
devm_delayed_work_autocancel() as inline in workqueue.h, right?

Yes.

I also see strong objection towards the devm managed clean-ups.

Yes it seems that there are some people who don't like this, where as
others do like them.

How about adding some devm-helpers.c in drivers/base - where we could
collect devm-based helpers - and which could be enabled by own CONFIG -
and left out by those who dislike it?

I would make this something configurable through Kconfig, but if
go the static inline route, which I'm in favor of then we could just
have a:

include/linux/devm-cleanup-helpers.h

And put everything (including kdoc texts) there.

This way the functionality is 100% opt-in (by explicitly including
the header if you want the helpers) which hopefully makes this a
bit more acceptable to people who don't like this style of cleanups.

I would be even happy to act as the upstream maintainer for such a
include/linux/devm-cleanup-helpers.h file, I can maintain it as part
of the platform-drivers-x86 tree (with its own MAINTAINERS entry).

Greg, would this be an acceptable solution to you ?

Regards,

Hans