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From: Alberto Garcia <berto@igalia.com>
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Date: Mon, 14 Jan 2019 15:40:39 +0100
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Subject: Re: [Qemu-devel] [PATCH] throttle-groups: fix restart coroutine
 iothread race
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To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>, qemu-block@nongnu.org, Max Reitz <mreitz@redhat.com>

On Mon 14 Jan 2019 02:35:53 PM CET, Stefan Hajnoczi wrote:
> On Fri, Jan 11, 2019 at 03:14:08PM +0100, Alberto Garcia wrote:
>> On Fri 11 Jan 2019 02:24:16 PM CET, Kevin Wolf wrote:
>> >> >> The following QMP command leads to a crash when iothreads are used:
>> >> >>
>> >> >>   { 'execute': 'device_del', 'arguments': {'id': 'data'} }
>> >> >
>> >> > How did you reproduce this? Do you have a test case?
>> >> 
>> >> Ok, I finally reproduced it, the patch looks good to me.
>> >
>> > Can it be turned into a qemu-iotests case or is it too complicated for
>> > that?
>> 
>> I can reproduce the problem reliably with this:
>> 
>> { "execute": "qmp_capabilities" }
>> { "execute": "blockdev-add",
>>   "arguments": {"driver": "null-co", "node-name": "hd0"}}
>> { "execute": "object-add",
>>   "arguments": {"qom-type": "iothread", "id": "iothread0"}}
>> { "execute": "device_add",
>>   "arguments": {"id": "scsi0", "driver": "virtio-scsi-pci",
>>                 "iothread": "iothread0"}}
>> { "execute": "device_add",
>>   "arguments": {"id": "scsi-hd0", "driver": "scsi-hd", "drive": "hd0"}}
>> { "execute": "block_set_io_throttle",
>>   "arguments": {"id": "scsi-hd0", "bps": 0, "bps_rd": 0, "bps_wr": 0,
>>                 "iops": 1000, "iops_rd": 0, "iops_wr": 0}}
>> { "execute": "device_del", "arguments": {"id": "scsi-hd0"}}
>> 
>> But this doesn't crash if I put it in an iotest.
>
> I've been able to reproduce this in an iotest, please see v2 of this
> series.

That iotest doesn't crash for me :-?

Berto