Re: [Bug? Report] kref problem

Greg KH
2006-03-16T17:20:45Z

On Thu, Mar 16, 2006 at 08:10:04PM +0300, Artem B. Bityutskiy wrote:
> On Thu, 2006-03-16 at 20:07 +0300, Artem B. Bityutskiy wrote:
> > On Thu, 2006-03-16 at 08:53 -0800, Greg KH wrote:
> > > > static void a_release(struct kobject *kobj)
> > > > {
> > > > struct my_obj_a *a;
> > > >
> > > > printk("%s\n", __FUNCTION__);
> > > > a = container_of(kobj, struct my_obj_a, kobj);
> > > > sysfs_remove_dir(&a->kobj);
> > >
> > > Woah, don't do that here, the kobject core already does this. A release
> > > function is for you to release the memory you have created with this
> > > kobject, not to mess with sysfs.
> > So do you mean this (attached) ? Anyway I end up with -1 kref.
> >
> Pardon, forgot to attach.

> #include <linux/kernel.h>
> #include <linux/init.h>
> #include <linux/module.h>
> #include <linux/kobject.h>
> #include <linux/stat.h>
>
> static void a_release(struct kobject *kobj);
>
> static struct kobj_type a_ktype = {
> .release = a_release
> };
>
> static void b_release(struct kobject *kobj);
>
> static struct kobj_type b_ktype = {
> .release = b_release
> };
>
> struct my_obj_a
> {
> struct kobject kobj;
> } a;
>
> struct my_obj_b
> {
> struct kobject kobj;
> } b;
>
> static __init int test_init(void)
> {
> int err;
>
> kobject_init(&a.kobj);
> a.kobj.ktype = &a_ktype;
> err = kobject_set_name(&a.kobj, "A");
> if (err)
> return err;
> printk("a inited, kref %d\n", atomic_read(&a.kobj.kref.refcount));
>
> kobject_init(&b.kobj);
> b.kobj.ktype = &b_ktype;
> b.kobj.parent = &a.kobj;
> err = kobject_set_name(&b.kobj, "B");
> if (err)
> goto out_a;
> printk("b inited, kref %d\n", atomic_read(&b.kobj.kref.refcount));
>
> err = sysfs_create_dir(&a.kobj);

Again, why are you trying to call the sysfs raw functions? You are not
registering the kobject with the kobject core, so bad things are
happening. Why not call kobject_register() or kobject_add(), like it is
documented to do so?

Because of this, you are seeing odd things happen.

thanks,

greg k-h