Re: don't use module_init in non-modular ... (was: Re: [PATCH] m68k:don't use module_init in non-modular mvme16x/rtc.c code)

From: Geert Uytterhoeven
Date: Sun Jan 19 2014 - 04:40:38 EST

Hi Paul,

On Thu, Jan 16, 2014 at 11:15 PM, Paul Gortmaker
<paul.gortmaker@xxxxxxxxxxxxx> wrote:
> The rtc.o is built for obj-y, i.e. always built in. It will
> never be modular, so using module_init as an alias for __initcall
> can be somewhat misleading.
> Fix this up now, so that we can relocate module_init from
> init.h into module.h in the future. If we don't do this, we'd
> have to add module.h to obviously non-modular code, and that
> would be a worse thing.

The word "module" has different meanings: it can be a "loadable kernel module",
or just a "code module". include/linux/init.h seems to agree with this:
* module_init() - driver initialization entry point
* @x: function to be run at kernel boot time or module insertion
* module_init() will either be called during do_initcalls() (if
* builtin) or at module insertion time (if a module). There can only
* be one per module.
#define module_init(x) __initcall(x);

I can understand you want to restrict "module_init()" to real loadable
modules, but "device_initcall()" sounds like a real bad name or this.

Furthermore, many places that contain always compiled-in code and
currently only use module_init() should probably start using module_exit()
as well, to do the proper cleanups to make kexec work.

So I'm not really convinced this is the way we want to go...

> Note that direct use of __initcall is discouraged, vs. one
> of the priority categorized subgroups. As __initcall gets
> mapped onto device_initcall, our use of device_initcall
> directly in this change means that the runtime impact is
> zero -- it will remain at level 6 in initcall ordering.
> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Cc: linux-m68k@xxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
> diff --git a/arch/m68k/mvme16x/rtc.c b/arch/m68k/mvme16x/rtc.c
> index 6ef7a81a3b12..1755e2f7137d 100644
> --- a/arch/m68k/mvme16x/rtc.c
> +++ b/arch/m68k/mvme16x/rtc.c
> @@ -161,4 +161,4 @@ static int __init rtc_MK48T08_init(void)
> printk(KERN_INFO "MK48T08 Real Time Clock Driver v%s\n", RTC_VERSION);
> return misc_register(&rtc_dev);
> }
> -module_init(rtc_MK48T08_init);
> +device_initcall(rtc_MK48T08_init);



Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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