linux-kernel - Re: [PATCH] x86: mcheck: call put_device on device

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Date:	Sat, 30 Nov 2013 12:25:44 +0100
From:	Levente Kurusa <levex@...ux.com>
To:	Borislav Petkov <bp@...en8.de>
CC:	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Tony Luck <tony.luck@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	EDAC <linux-edac@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: mcheck: call put_device on device_register failure

2013-11-30 12:12, Borislav Petkov:
> On Sat, Nov 30, 2013 at 08:30:33AM +0100, Levente Kurusa wrote:
>> No, if the call to put_device gives up the last reference to the
>> device, then device_release gets called which in turn frees the memory
>> associated with it. In this case, mce_device_release() will get
>> called, which is just a simple kfree call.
> 
> Aah, that's that delayed freeing the driver core does, right. Now you
> made me go and look into detail:
> 
> device_unregister
> |->put_device
>   |->kobject_put
>      |->kref_put(&kobj->kref, kobject_release)
> 	|->kref_sub(kref, 1, release)
> 	   |->release
> 	   |->kobject_release
> 	      |->kobject_cleanup
> 	         |->t->release
> 		 |->device_release
> 		    |->mce_device_release
> 
Now this tree makes me wonder if there are devices where
the author forgot to set a device_release or when the put_device
is not called. I will take a look into this.
> 
> Ok, I see it now. :-) :-)
> 
> Thanks, I'll take your patch as-is.
> 
Awesome, thanks! :-)


-- 
Regards,
Levente Kurusa
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