Re: [RESEND PATCH v1] moduleparam: Save information about built-in modules in separate file

Re: [RESEND PATCH v1] moduleparam: Save information about built-in modules in separate file

[Lucas De Marchi]

On Wed, Mar 27, 2019 at 8:40 AM Jessica Yu <jeyu@kernel.org> wrote:
> >No. There are definitely not all modules. I have a builtin sha256_generic,
> >but I can't find him in the /sys/module.
>
> Yeah, you'll only find builtin modules under /sys/module/ if it has any module
> parameters, otherwise you won't find it there. As Masahiro already mentioned,
> if a builtin module has any parameters, they would be accessible under /sys/module/.

Could we please change that and add the sysfs entry regardless of
what's being discussed
here? Not having the entry there simply because we don't have
parameters for that module
always annoyed me.

Lucas De Marchi

Re: [RESEND PATCH v1] moduleparam: Save information about built-in modules in separate file

[Greg KH]

On Thu, Mar 28, 2019 at 10:41:59AM -0700, Lucas De Marchi wrote:
> On Wed, Mar 27, 2019 at 8:40 AM Jessica Yu <jeyu@kernel.org> wrote:
> > >No. There are definitely not all modules. I have a builtin sha256_generic,
> > >but I can't find him in the /sys/module.
> >
> > Yeah, you'll only find builtin modules under /sys/module/ if it has any module
> > parameters, otherwise you won't find it there. As Masahiro already mentioned,
> > if a builtin module has any parameters, they would be accessible under /sys/module/.
> 
> Could we please change that and add the sysfs entry regardless of
> what's being discussed here? Not having the entry there simply because
> we don't have parameters for that module always annoyed me.

What is the sysfs directory going to show?  Will it just be empty?

Feel free to send a patch for this, but from what I remember, it wasn't
the easiest thing to do for some reason.  But given that the code was
implemented before git was, I can't quite remember.

thanks,

greg k-h

Re: [RESEND PATCH v1] moduleparam: Save information about built-in modules in separate file

[Dmitry Torokhov]

On Thu, Mar 28, 2019 at 11:45 AM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Thu, Mar 28, 2019 at 10:41:59AM -0700, Lucas De Marchi wrote:
> > On Wed, Mar 27, 2019 at 8:40 AM Jessica Yu <jeyu@kernel.org> wrote:
> > > >No. There are definitely not all modules. I have a builtin sha256_generic,
> > > >but I can't find him in the /sys/module.
> > >
> > > Yeah, you'll only find builtin modules under /sys/module/ if it has any module
> > > parameters, otherwise you won't find it there. As Masahiro already mentioned,
> > > if a builtin module has any parameters, they would be accessible under /sys/module/.
> >
> > Could we please change that and add the sysfs entry regardless of
> > what's being discussed here? Not having the entry there simply because
> > we don't have parameters for that module always annoyed me.

What is the benefit compared to wasting some memory for the directory?

>
> What is the sysfs directory going to show?  Will it just be empty?
>
> Feel free to send a patch for this, but from what I remember, it wasn't
> the easiest thing to do for some reason.  But given that the code was
> implemented before git was, I can't quite remember.

I am pretty sure we allow empty attribute groups, so it is probbaly as
simple as removing "If (!params) return 0;" form
module_param_sysfs_setup() and making sure we always create
"parameters" group instead of doing it on first visible parameter in
add_sysfs_param(). I suppose we no longer want to skip over parameters
that are not readable nor writable either?

Thanks.

-- 
Dmitry