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

[Greg KH <greg@kroah.com>]

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.
> 
> With out this patch kobject_unregister() will have some serious side effects.
> 
> Please apply.
> 
> signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
> 
> 
>  linux-2.6.10-rc1-mm4-askeshav/lib/kobject.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff -puN lib/kobject.c~kobject_unregister_fix lib/kobject.c
> --- linux-2.6.10-rc1-mm4/lib/kobject.c~kobject_unregister_fix	2004-11-10 13:43:42.243877455 -0800
> +++ linux-2.6.10-rc1-mm4-askeshav/lib/kobject.c	2004-11-10 13:46:30.788797265 -0800
> @@ -301,6 +301,8 @@ void kobject_del(struct kobject * kobj)
>  {
>  	kobject_hotplug(kobj, KOBJ_REMOVE);
>  	sysfs_remove_dir(kobj);
> +
> +	/* unlink does kobject_put() for us */
>  	unlink(kobj);
>  }
>  
> @@ -313,7 +315,6 @@ void kobject_unregister(struct kobject *
>  {
>  	pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
>  	kobject_del(kobj);
> -	kobject_put(kobj);
>  }

No, this is wrong.  Count the add and put in the sequence of:
	kobject_register()
	kobject_unregister()

they are balanced.

You mention you are seeing problems.  Have a trace?  Example code?

thanks,

gre k-h


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