Re: [Qemu-devel] [PATCH] throttle-groups: fix restart coroutine iothread race

[Alberto Garcia]

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.

Berto