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Date: Tue, 23 Jun 2009 21:31:55 +0300
From: Avi Kivity <avi@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] block: Clean up after deleting BHs
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To: Christoph Hellwig <hch@lst.de>
Cc: qemu-devel@nongnu.org

On 06/23/2009 09:26 PM, Christoph Hellwig wrote:
> On Tue, Jun 23, 2009 at 07:57:01PM +0300, Avi Kivity wrote:
>    
>>> I think not having the state of the private acb area cleared over a
>>> free/realloc cycle is pretty dangerous.  Wouldn't it be better to always
>>> clear that space in qemu_aio_get?
>>>
>>>        
>> Maybe, but that's a bigger change.  Let's start with this (in stable-
>> too) and rework aio later.
>>      
>
> It's actually smaller - half the size to be exact :)
>
> Signed-off-by: Christoph Hellwig<hch@lst.de>
>
> Index: qemu/block.c
> ===================================================================
> --- qemu.orig/block.c	2009-06-23 20:16:48.283930485 +0200
> +++ qemu/block.c	2009-06-23 20:16:57.158834441 +0200
> @@ -1515,6 +1515,7 @@ void *qemu_aio_get(AIOPool *pool, BlockD
>       acb->bs = bs;
>       acb->cb = cb;
>       acb->opaque = opaque;
> +    memset(acb + 1, 0, pool->aiocb_size - sizeof(BlockDriverAIOCB));
>       return acb;
>   }
>    

I meant in an omg we have to look at all the consequences way rather 
than byte count.  This patch is somewhat less local.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.