Re: [PATCH v2] RFC: ksmbd: Create module_kobject if builtin

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Fri, Oct 24, 2025 at 12:49:44AM +0200, Linus Walleij wrote:
> Adding a call to lookup_or_create_module_kobject() to ksmbd
> makes /sys/modules/ksmbd appear even when ksmbd is compiled
> into the kernel.

Ick, no, please do not.  Otherwise you will see this pop up in all
drivers/modules for the same "reason".

> This is nice when you boot a custom kernel on OpenWrt because
> the startup script does things such as:
> 
> [ ! -e /sys/module/ksmbd ] && modprobe ksmbd 2> /dev/null
> if [ ! -e /sys/module/ksmbd ]; then
>     logger -p daemon.error -t 'ksmbd' "modprobe of ksmbd "
>     "module failed, can\'t start ksmbd!"
>      exit 1
> fi
> 
> which makes the script not work with a compiled-in ksmbd.

Please fix the start up script to not do this.  Don't work around broken
userspace by changing the kernel.

> Since I actually turn off modules and compile all my modules
> into the kernel, I can't change the script to just check
> cat /lib/modules/$(uname -r)/modules.builtin | grep ksmbd
> either: no /lib/modules directory.

Then do something else to determine if ksmbd is in the running kernel,
don't rely on a modules sysfs file like that.

> An option would be to change the script to proceed and
> just assume the module is compiled in but it feels wrong.

Agreed, surely there is some other way to "know" if that kernel feature
is present or not, right?  Mount a filesystem?  Something else?

> If this approach is acceptable I am happy to generalize this
> to something that any module that wants a /sys/modules/foo
> file can use to get just that.

No, please do not do that.  Just fix userspace.

thanks,

greg k-h