Re: [PATCH 01/12] module: Move modprobe_path and modules_disabled ctl_tables into the module subsys

[Petr Pavlu <petr.pavlu@suse.com>]

On 5/9/25 14:54, Joel Granados wrote:
> Move module sysctl (modprobe_path and modules_disabled) out of sysctl.c
> and into the modules subsystem. Make the modprobe_path variable static
> as it no longer needs to be exported. Remove module.h from the includes
> in sysctl as it no longer uses any module exported variables.
> 
> This is part of a greater effort to move ctl tables into their
> respective subsystems which will reduce the merge conflicts in
> kernel/sysctl.c.
> 
> Signed-off-by: Joel Granados <joel.granados@kernel.org>
> [...]
> --- a/kernel/module/kmod.c
> +++ b/kernel/module/kmod.c
> @@ -60,7 +60,7 @@ static DEFINE_SEMAPHORE(kmod_concurrent_max, MAX_KMOD_CONCURRENT);
>  /*
>  	modprobe_path is set via /proc/sys.
>  */
> -char modprobe_path[KMOD_PATH_LEN] = CONFIG_MODPROBE_PATH;
> +static char modprobe_path[KMOD_PATH_LEN] = CONFIG_MODPROBE_PATH;
>  
>  static void free_modprobe_argv(struct subprocess_info *info)
>  {
> @@ -177,3 +177,33 @@ int __request_module(bool wait, const char *fmt, ...)
>  	return ret;
>  }
>  EXPORT_SYMBOL(__request_module);
> +
> +#ifdef CONFIG_MODULES
> +static const struct ctl_table kmod_sysctl_table[] = {
> +	{
> +		.procname	= "modprobe",
> +		.data		= &modprobe_path,
> +		.maxlen		= KMOD_PATH_LEN,
> +		.mode		= 0644,
> +		.proc_handler	= proc_dostring,
> +	},
> +	{
> +		.procname	= "modules_disabled",
> +		.data		= &modules_disabled,
> +		.maxlen		= sizeof(int),
> +		.mode		= 0644,
> +		/* only handle a transition from default "0" to "1" */
> +		.proc_handler	= proc_dointvec_minmax,
> +		.extra1		= SYSCTL_ONE,
> +		.extra2		= SYSCTL_ONE,
> +	},

This is minor.. but the file kernel/module/kmod.c contains the logic to
request direct modprobe invocation by the kernel. Registering the
modprobe_path sysctl here is appropriate. However, the modules_disabled
setting affects the entire module loader so I don't think it's best to
register it here.

I suggest keeping a single table for the module sysctl values but moving
it to kernel/module/main.c. This means the variable modprobe_path must
retain external linkage, on the other hand, modules_disabled can be made
static.

-- 
Thanks,
Petr

> +};
> +
> +static int __init init_kmod_sysctl(void)
> +{
> +	register_sysctl_init("kernel", kmod_sysctl_table);
> +	return 0;
> +}
> +
> +subsys_initcall(init_kmod_sysctl);
> +#endif