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Date: Thu, 16 Oct 2008 17:25:57 +0200
From: Avi Kivity <avi@redhat.com>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] Re: [PATCH]: fix QEMU SCSI lock up
References: <20080924225946.GA28588@dmt.cnet> <48DACF6F.40301@us.ibm.com>
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To: qemu-devel@nongnu.org
Cc: Marcelo Tosatti <mtosatti@redhat.com>

Avi Kivity wrote:
> Anthony Liguori wrote:
>   
>>> For reasons that I do not fully understand, bdrv_aio_read() does
>>> not return immediately, but instead it calls scsi_read_data()
>>> recursively.
>>>       
>> This bothers me.  bdrv_aio_read() should never immediately invoke the
>> callback to prevent exactly this sort of problem.  Perhaps this was a
>> bug that has since been fixed?  Is this still reproducible?
>>     
>
> qcow2 metadata is synchronous, and if the disk is empty, there will be
> no data I/O, so bdrv_aio_read() will never be invoked.
>
> Maybe we should fix this in qcow2 (and the other block formats) by
> scheduling a BH.
>   

FWIW, I was told this reproduces on kvm-77 (which has the latest qemu 
scsi bits).

-- 
error compiling committee.c: too many arguments to function