linux-kernel - Re: [PATCH 2/6] xen-blkfront: handle backend CLOSED without CLOSING

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Message-Id: <506EE6CD020000780009FF4E@nat28.tlf.novell.com>
Date:	Fri, 05 Oct 2012 12:55:25 +0100
From:	"Jan Beulich" <JBeulich@...e.com>
To:	"David Vrabel" <david.vrabel@...rix.com>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>
Cc:	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/6] xen-blkfront: handle backend CLOSED without
 CLOSING

>>> On 05.10.12 at 13:42, David Vrabel <david.vrabel@...rix.com> wrote:
> On 02/10/12 21:02, Konrad Rzeszutek Wilk wrote:
>> On Mon, Oct 01, 2012 at 06:19:19PM +0100, David Vrabel wrote:
>>> On 25/09/12 18:53, David Vrabel wrote:
>>>> On 21/09/12 17:04, David Vrabel wrote:
>>>>> From: David Vrabel <david.vrabel@...rix.com>
>>>>>
>>>>> Backend drivers shouldn't transistion to CLOSED unless the frontend is
>>>>> CLOSED.  If a backend does transition to CLOSED too soon then the
>>>>> frontend may not see the CLOSING state and will not properly shutdown.
>>>>>
>>>>> So, treat an unexpected backend CLOSED state the same as CLOSING.
>>>>
>>>> Didn't handle the frontend block device being mounted. Updated patch here.
>>>
>>> Konrad, can you ack this updated patch if you're happy with it.
>> 
>> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
>> 
>> Or should I just carry it in my for-jens-3.7 bug-fixes queue and ask
>> Jen to pull it once rc0 is out?
> 
> This seems easiest, if Jan is happy with the patch.

I see the point of your explanation yesterday, but am still not
convinced that the early cleanup in spite of active users of the
disk can't cause any problems (like dangling pointers or NULL
dereferences).

Jan

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