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

[Stefan Hajnoczi]

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.

Stefan

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