Re: [PATCH] kobject: fix double kobject_put in kobject_unregister()

From: Keshavamurthy Anil S
Date: Wed Nov 10 2004 - 17:45:37 EST

On Wed, Nov 10, 2004 at 10:30:16PM +0000, Russell King wrote:
> On Wed, Nov 10, 2004 at 02:19:23PM -0800, Keshavamurthy Anil S wrote:
> > Hi Greg,
> >
> > This patch fixes the problem where in kobject resources were getting
> > freed when those kobject were still in use due to double kobject_put()
> > getting called in the kobject_unregister() code path.
> Isn't it intended that, after an sysfs/kobject/device object is
> unregistered that the thread doing the unregistering must not
> dereference the memory associated with that object?
Yes, nobody is touching the resource once it is freed. But because of
double kobject_put() getting called in the kobject_unregister() code patch
I am seeing successive parent's kobject_unregister() causing panic as that kobject's
kobject_cleanup() gets called when childs kobject_unregiser() is getting called.
i.e patern's kobject_cleanup() gets called for some reason when clild's kobject_unregister()
is called. My patch fixes this issues.

> IOW, the sequence:
> allocate
> register (refcount >= 2 after this completes)
> unregister
> will automatically free the object once the last user has gone.
> --
> Russell King
> Linux kernel 2.6 ARM Linux -
> maintainer of: 2.6 PCMCIA -
> 2.6 Serial core
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at