Q: generic module{init,exit} boilerplate

Q: generic module{init,exit} boilerplate

[H Hartley Sweeten]

Hello all,

There are a number of drivers/modules in the kernel that have
a "do nothing" module init/exit of the form:

static int __init foo_init(void)
{
	return 0;
}
module_init(foo_init);

static void __exit foo_exit(void)
{
}
module_exit(foo_exit);

Is it worth creating a generic helper macro to handle this boilerplate?
Something along the lines of the module_driver() macro. Each use would
replace about 10 lines-of-code with a single line.

If so what would be a good name for the macro and what header would
be the appropriate place for it to reside?

Thanks for any replies!
Hartley

Re: Q: generic module{init,exit} boilerplate

[Dan Carpenter]

On Thu, Jan 10, 2013 at 11:12:43AM -0600, H Hartley Sweeten wrote:
> Hello all,
> 
> There are a number of drivers/modules in the kernel that have
> a "do nothing" module init/exit of the form:
> 

Do you have a real life example?  Why would people do that?

regards,
dan carpenter

Re: Q: generic module{init,exit} boilerplate

[Julia Lawall]

On Thu, 10 Jan 2013, Dan Carpenter wrote:

> On Thu, Jan 10, 2013 at 11:12:43AM -0600, H Hartley Sweeten wrote:
> > Hello all,
> >
> > There are a number of drivers/modules in the kernel that have
> > a "do nothing" module init/exit of the form:
> >
>
> Do you have a real life example?  Why would people do that?

I find 39 occurrences, although the first one I looked at had a big #if 0
in the module_init function.  Here are some examples:

drivers/media/common/saa7146/saa7146_fops.c
drivers/media/platform/soc_camera/soc_mediabus.c
drivers/tty/serial/suncore.c

There are also a bunch of comedi drivers.  Around half of the examples are
sound drivers, eg:

sound/synth/emux/emux.c
sound/synth/util_mem.c
sound/isa/sb/sb16_csp.c

julia

RE: Q: generic module{init,exit} boilerplate

[H Hartley Sweeten]

On Thursday, January 10, 2013 11:58 AM, Julia Lawall wrote:
> On Thu, 10 Jan 2013, Dan Carpenter wrote:
>
>> On Thu, Jan 10, 2013 at 11:12:43AM -0600, H Hartley Sweeten wrote:
>>> Hello all,
>>>
>>> There are a number of drivers/modules in the kernel that have
>>> a "do nothing" module init/exit of the form:
>>>
>>
>> Do you have a real life example?  Why would people do that?
>
> I find 39 occurrences, although the first one I looked at had a big #if 0
> in the module_init function.  Here are some examples:
>
> drivers/media/common/saa7146/saa7146_fops.c
> drivers/media/platform/soc_camera/soc_mediabus.c
> drivers/tty/serial/suncore.c
>
> There are also a bunch of comedi drivers.  Around half of the examples are
> sound drivers, eg:
>
> sound/synth/emux/emux.c
> sound/synth/util_mem.c
> sound/isa/sb/sb16_csp.c

Most of them appear to be in modules that provide exported functions for
other drivers/modules. These modules do nothing by themselves so I guess
they have the do nothing module_{init,exit} just because it's required since
they can be modules.

That brings up the question...

Do these types of helper modules actually require the module_{init,exit}?
Would the module load properly without it? They don't _do_ anything other
than EXPORT a number of symbols for other modules.

Regards,
Hartley