linux-kernel - Re: [PATCH] kobject: make sure kobj->ktype is set before kobject

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Message-ID: <20071129172134.74849579@gondolin.boeblingen.de.ibm.com>
Date:	Thu, 29 Nov 2007 17:21:34 +0100
From:	Cornelia Huck <cornelia.huck@...ibm.com>
To:	Kay Sievers <kay.sievers@...y.org>
Cc:	Alan Stern <stern@...land.harvard.edu>, Greg KH <greg@...ah.com>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	Jonathan Corbet <corbet@....net>,
	Randy Dunlap <randy.dunlap@...cle.com>
Subject: Re: [PATCH] kobject: make sure kobj->ktype is set before
 kobject_init

On Thu, 29 Nov 2007 17:04:40 +0100,
Kay Sievers <kay.sievers@...y.org> wrote:

> On Thu, 2007-11-29 at 10:54 -0500, Alan Stern wrote:
> > On Thu, 29 Nov 2007, Kay Sievers wrote:
> > 
> > > > And if someone calls kobject_put() after kobject_init() to clean up,
> > > > their release function will not be called if they didn't set the ktype.
> > > > So the check really belongs into kobject_init() IMO.
> > 
> > Right.  And even though cleaning up no longer needs to drop a reference
> > to the kset, it still might need to free the kobject's name.  So for 
> > example, either of these sequences:
> > 
> > 	kobject_init();			kobject_set_name();
> > 	kobject_set_name();		kobject_init();
> > 	...				...
> > 	kobject_free();			kobject_free();
> > 
> > would leak memory.
> 
> Yeah, only the kobject_put() would free the name.
> 
> > In fact, if we were designing the kobject API from scratch, I'd suggest 
> > making the ktype value an argument to kobject_init() so that it 
> > _couldn't_ be omitted.
> 
> Sounds fine, maybe we should also pass the name along, so it will be
> obvious what happens here:
>   int kobject_init(struct kobject *kobj, struct kobj_type *type, const char *fmt, ...)

Agreed. Better don't hide too much.
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