Re: [ 84/95] virtio_blk: fix config handler race

From: Asias He
Date: Sun Sep 09 2012 - 22:45:01 EST


On 09/10/2012 10:26 AM, Rusty Russell wrote:
> Ben Hutchings <ben@xxxxxxxxxxxxxxx> writes:
>
>> 3.2-stable review patch. If anyone has any objections, please let me know.
>>
>> ------------------
>>
>> From: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
>>
>> commit 4678d6f970c2f7c0cbfefc0cc666432d153b321b upstream.
>>
>> Fix a theoretical race related to config work
>
> ???
>
> From Documentation/stable_kernel_rules.txt:
>
> - No "theoretical race condition" issues, unless an explanation of how the
> race can be exploited is also provided.
>
> Similarly, '[ 85/95] virtio_blk: Drop unused request tracking list'
> is a marginal perf improvement, why is it in there?

This also drops the following line which may trigger a BUG in hot
-unplug path.

/* Nothing should be pending. */
BUG_ON(!list_empty(&vblk->reqs));

So, this patch is needed to fix up the hot-unplug bug along with the others.

>
> Neither of these were cc:stable; did someone request them specifically?
>
> Confused,
> Rusty.
>


--
Asias
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