Re: [PATCH v2 0/3] monitor: only run coroutine commands in qemu_aio_context

[Kevin Wolf <kwolf@redhat.com>]

Am 18.01.2024 um 15:48 hat Stefan Hajnoczi geschrieben:
> v2:
> - Filter image format in 141 test output [Kevin]
> - Fix pylint and mypy errors in 141 [Kevin]
> 
> Several bugs have been reported related to how QMP commands are rescheduled in
> qemu_aio_context:
> - https://gitlab.com/qemu-project/qemu/-/issues/1933
> - https://issues.redhat.com/browse/RHEL-17369
> - https://bugzilla.redhat.com/show_bug.cgi?id=2215192
> - https://bugzilla.redhat.com/show_bug.cgi?id=2214985
> 
> The first instance of the bug interacted with drain_call_rcu() temporarily
> dropping the BQL and resulted in vCPU threads entering device emulation code
> simultaneously (something that should never happen). I set out to make
> drain_call_rcu() safe to use in this environment, but Paolo and Kevin discussed
> the possibility of avoiding rescheduling the monitor_qmp_dispatcher_co()
> coroutine for non-coroutine commands. This would prevent monitor commands from
> running during vCPU thread aio_poll() entirely and addresses the root cause.
> 
> This patch series implements this idea. qemu-iotests is sensitive to the exact
> order in which QMP events and responses are emitted. Running QMP handlers in
> the iohandler AioContext causes some QMP events to be ordered differently than
> before. It is therefore necessary to adjust the reference output in many test
> cases. The actual QMP code change is small and everything else is just to make
> qemu-iotests happy.
> 
> If you have bugs related to the same issue, please retest them with these
> patches. Thanks!

Thanks, applied to the block branch.

Kevin