[PATCH] pktcdvd : add kobject_put when kobject register fails

[PATCH] pktcdvd : add kobject_put when kobject register fails

[Dave Young]

Kobject_put should be called when kobject register functioin fails, so the the kobj ref count touch zero and then the proper cleanup routines will be called.

Signed-off-by: Dave Young <hidave.darkstar@gmail.com> 

---
drivers/block/pktcdvd.c |    4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff -upr linux/drivers/block/pktcdvd.c linux.new/drivers/block/pktcdvd.c
--- linux/drivers/block/pktcdvd.c	2007-11-30 13:13:44.000000000 +0800
+++ linux.new/drivers/block/pktcdvd.c	2007-11-30 13:24:08.000000000 +0800
@@ -117,8 +117,10 @@ static struct pktcdvd_kobj* pkt_kobj_cre
 	p->kobj.parent = parent;
 	p->kobj.ktype = ktype;
 	p->pd = pd;
-	if (kobject_register(&p->kobj) != 0)
+	if (kobject_register(&p->kobj) != 0) {
+		kobject_put(&p->kobj);
 		return NULL;
+	}
 	return p;
 }
 /*

Re: [PATCH] pktcdvd : add kobject_put when kobject register fails

[Pekka Enberg]

Hi Dave,

On Dec 4, 2007 3:31 AM, Dave Young <hidave.darkstar@gmail.com> wrote:
> Kobject_put should be called when kobject register functioin fails, so the
> the kobj ref count touch zero and then the proper cleanup routines will be
> called.

[snip]

> diff -upr linux/drivers/block/pktcdvd.c linux.new/drivers/block/pktcdvd.c
> --- linux/drivers/block/pktcdvd.c       2007-11-30 13:13:44.000000000 +0800
> +++ linux.new/drivers/block/pktcdvd.c   2007-11-30 13:24:08.000000000 +0800
> @@ -117,8 +117,10 @@ static struct pktcdvd_kobj* pkt_kobj_cre
>         p->kobj.parent = parent;
>         p->kobj.ktype = ktype;
>         p->pd = pd;
> -       if (kobject_register(&p->kobj) != 0)
> +       if (kobject_register(&p->kobj) != 0) {
> +               kobject_put(&p->kobj);
>                 return NULL;

This looks wrong to me. AFAICT the only thing that can fail
kobject_register() is kobject_add() and it cleans up after itself. Am
I missing something here?

                           Pekka

Re: [PATCH] pktcdvd : add kobject_put when kobject register fails

[Dave Young]

On Dec 4, 2007 3:45 PM, Pekka Enberg <penberg@cs.helsinki.fi> wrote:
> Hi Dave,
>
> On Dec 4, 2007 3:31 AM, Dave Young <hidave.darkstar@gmail.com> wrote:
> > Kobject_put should be called when kobject register functioin fails, so the
> > the kobj ref count touch zero and then the proper cleanup routines will be
> > called.
>
> [snip]
>
> > diff -upr linux/drivers/block/pktcdvd.c linux.new/drivers/block/pktcdvd.c
> > --- linux/drivers/block/pktcdvd.c       2007-11-30 13:13:44.000000000 +0800
> > +++ linux.new/drivers/block/pktcdvd.c   2007-11-30 13:24:08.000000000 +0800
> > @@ -117,8 +117,10 @@ static struct pktcdvd_kobj* pkt_kobj_cre
> >         p->kobj.parent = parent;
> >         p->kobj.ktype = ktype;
> >         p->pd = pd;
> > -       if (kobject_register(&p->kobj) != 0)
> > +       if (kobject_register(&p->kobj) != 0) {
> > +               kobject_put(&p->kobj);
> >                 return NULL;
>
> This looks wrong to me. AFAICT the only thing that can fail
> kobject_register() is kobject_add() and it cleans up after itself. Am
> I missing something here?

Hi,
the kobject reference is get in kobject_init, and then kobject_add, if
kobject_add fail, it will only cleanup the reference got by itsself.

This topic is discussed in:
http://lkml.org/lkml/2007/11/30/9

Regards
dave
>
>                            Pekka
>

Re: [PATCH] pktcdvd : add kobject_put when kobject register fails

[Pekka J Enberg]

Hi Dave,

On Tue, 4 Dec 2007, Dave Young wrote:
> the kobject reference is get in kobject_init, and then kobject_add, if
> kobject_add fail, it will only cleanup the reference got by itsself.
> 
> This topic is discussed in:
> http://lkml.org/lkml/2007/11/30/9

Ok, thanks! Please the explanation to the changelog too.

Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>

			Pekka

Re: [PATCH] pktcdvd : add kobject_put when kobject register fails

[Dave Young]

On Tue, Dec 04, 2007 at 10:05:24AM +0200, Pekka J Enberg wrote:
> Hi Dave,
> 
> On Tue, 4 Dec 2007, Dave Young wrote:
> > the kobject reference is get in kobject_init, and then kobject_add, if
> > kobject_add fail, it will only cleanup the reference got by itsself.
> > 
> > This topic is discussed in:
> > http://lkml.org/lkml/2007/11/30/9
> 
> Ok, thanks! Please the explanation to the changelog too.
> 

Ok, lets add some explanation.
------------------------------

kobject_put should be called when kobject register functioin fails.

In kobject_register, the kobject reference is get in kobject_init, and then kobject_add. If kobject_add fail, it will only cleanup the reference got by itself.

Signed-off-by: Dave Young <hidave.darkstar@gmail.com> 
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>

---
drivers/block/pktcdvd.c |    4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff -upr linux/drivers/block/pktcdvd.c linux.new/drivers/block/pktcdvd.c
--- linux/drivers/block/pktcdvd.c	2007-11-30 13:13:44.000000000 +0800
+++ linux.new/drivers/block/pktcdvd.c	2007-11-30 13:24:08.000000000 +0800
@@ -117,8 +117,10 @@ static struct pktcdvd_kobj* pkt_kobj_cre
 	p->kobj.parent = parent;
 	p->kobj.ktype = ktype;
 	p->pd = pd;
-	if (kobject_register(&p->kobj) != 0)
+	if (kobject_register(&p->kobj) != 0) {
+		kobject_put(&p->kobj);
 		return NULL;
+	}
 	return p;
 }
 /*