2007-12-04 01:31:18

by Dave Young

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

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 <[email protected]>

---
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;
}
/*

2007-12-04 07:45:23

by Pekka Enberg

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

Hi Dave,

On Dec 4, 2007 3:31 AM, Dave Young <[email protected]> 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

2007-12-04 08:00:45

by Dave Young

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

On Dec 4, 2007 3:45 PM, Pekka Enberg <[email protected]> wrote:
> Hi Dave,
>
> On Dec 4, 2007 3:31 AM, Dave Young <[email protected]> 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
>

2007-12-04 08:05:34

by Pekka Enberg

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

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 <[email protected]>

Pekka

2007-12-04 08:26:18

by Dave Young

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

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 <[email protected]>
Reviewed-by: Pekka Enberg <[email protected]>

---
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;
}
/*