linux-kernel - Re: [PATCH 3/4] modules: proper cleanup of kobject without CONFIG

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Message-Id: <1211456661.7496.6.camel@iris.sw.ru>
Date:	Thu, 22 May 2008 15:44:21 +0400
From:	"Denis V. Lunev" <den@...nvz.org>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	akpm@...ux-foundation.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, Kay Sievers <kay.sievers@...y.org>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: Re: [PATCH 3/4] modules: proper cleanup of kobject without
	CONFIG_SYSFS

On Thu, 2008-05-22 at 19:20 +1000, Rusty Russell wrote:
> On Tuesday 20 May 2008 19:59:48 Denis V. Lunev wrote:
> > kobject: '<NULL>' (ffffffffa0104050): is not initialized, yet kobject_put()
> 
> Thanks Denis.
> 
> This patch masks a deeper problem; looks like you can't load any modules with 
> CONFIG_SYSFS=n:
> 
> kernel/module.c:
> int mod_sysfs_init(struct module *mod)
> {
> 	int err;
> 	struct kobject *kobj;
> 
> 	if (!module_sysfs_initialized) {
> 		printk(KERN_ERR "%s: module sysfs not initialized\n",
> 		       mod->name);
> 		err = -EINVAL;
> 		goto out;
> 	}
> 
> AFAICT, module_sysfs_initialized is not ever set if !CONFIG_SYSFS.
> 
> I can't see the point of module_sysfs_initialized.  It was introduced by Greg 
> in commit 823bccfc ("remove "struct subsystem" as it is no longer needed").
> 
> Greg, what were you trying to do here?  Modules can't be loaded before 
> param_sysfs_init(): are you trying to handle the case where the 
> kset_create_and_add() fails?

Basically you miss
static inline int mod_sysfs_init(struct module *mod)
{
        return 0;
}
in include/linux/module.h

So, without CONFIG_SYSFS a dummy stab for mod_sysfs_init is called.

Regards,
	Den

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