netdev - Re: [Xen-devel] [PATCH net-next] xen-netfront: clean up code in xennet_release_rx

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Message-ID: <52D6AAA4.7090108@citrix.com>
Date:	Wed, 15 Jan 2014 15:35:00 +0000
From:	Andrew Bennieston <andrew.bennieston@...rix.com>
To:	annie li <annie.li@...cle.com>
CC:	Wei Liu <wei.liu2@...rix.com>, <netdev@...r.kernel.org>,
	<ian.campbell@...rix.com>, <xen-devel@...ts.xen.org>
Subject: Re: [Xen-devel] [PATCH net-next] xen-netfront: clean up code in xennet_release_rx_bufs

On 15/01/14 14:15, annie li wrote:
>
> On 2014-1-15 19:02, Andrew Bennieston wrote:
>> On 15/01/14 10:07, Wei Liu wrote:
>>> On Fri, Jan 10, 2014 at 06:48:38AM +0800, Annie Li wrote:
>>>> Current netfront only grants pages for grant copy, not for grant
>>>> transfer, so
>>>> remove corresponding transfer code and add receiving copy code in
>>>> xennet_release_rx_bufs.
>>>>
>>>
>>> This path seldom gets call -- not that many people unload xen-netfront
>>> driver. If Annie has tested this patch and it works as expected I think
>>> it's fine.
>>>
>> In XenServer we have seen a number of cases where unplugging and
>> replugging VIFs results in leakage of grant references, eventually
>> leading to a case where you cannot plug a VIF (after ~ 400 such
>> cycles)...
>>
>> It's worth pointing out, as far as this patch is concerned, that
>> gnttab_end_foreign_access() can fail,
>
> Just like what Wei mentioned, it is gnttab_end_foreign_access_ref here,
> right?
Yes, sorry - I forgot to type the _ref part!
>
>> which is not taken into account here.
>
> Good point, gnttab_end_foreign_access_ref fails for grant which is in use.
>
> Thanks
> Annie
>>
>> Andrew.
>>
>>> I'm not netfront maintainer but I'm happy to add
>>> Acked-by: Wei Liu <wei.liu2@...rix.com>
>>> if Annie confirms she's tested this patch.
>>>
>>> Wei.
>>>
>>> _______________________________________________
>>> Xen-devel mailing list
>>> Xen-devel@...ts.xen.org
>>> http://lists.xen.org/xen-devel
>>>
>>
>

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