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			monitor_qmp_dispatcher_co() runs in the iohandler AioContext that is not polled during nested event loops. The coroutine currently reschedules itself in the main loop's qemu_aio_context AioContext, which is polled during nested event loops. One known problem is that QMP device-add calls drain_call_rcu(), which temporarily drops the BQL, leading to all sorts of havoc like other vCPU threads re-entering device emulation code while another vCPU thread is waiting in device emulation code with aio_poll(). Paolo Bonzini suggested running non-coroutine QMP handlers in the iohandler AioContext. This avoids trouble with nested event loops. His original idea was to move coroutine rescheduling to monitor_qmp_dispatch(), but I resorted to moving it to qmp_dispatch() because we don't know if the QMP handler needs to run in coroutine context in monitor_qmp_dispatch(). monitor_qmp_dispatch() would have been nicer since it's associated with the monitor implementation and not as general as qmp_dispatch(), which is also used by qemu-ga. A number of qemu-iotests need updated .out files because the order of QMP events vs QMP responses has changed. Solves Issue #1933. Cc: qemu-stable@nongnu.org Fixes: 7bed89958bfbf40df9ca681cefbdca63abdde39d ("device_core: use drain_call_rcu in in qmp_device_add") Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2215192 Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2214985 Buglink: https://issues.redhat.com/browse/RHEL-17369 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-ID: <20240118144823.1497953-4-stefanha@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Tested-by: Fiona Ebner <f.ebner@proxmox.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
		
			
				
	
	
		
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| QA output created by 127
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| Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=65536
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| Formatting 'TEST_DIR/t.IMGFMT.overlay0', fmt=IMGFMT size=65536 backing_file=TEST_DIR/t.IMGFMT backing_fmt=IMGFMT
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| Formatting 'TEST_DIR/t.IMGFMT.overlay1', fmt=IMGFMT size=65536 backing_file=TEST_DIR/t.IMGFMT backing_fmt=IMGFMT
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| wrote 42/42 bytes at offset 0
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| 42 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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| { 'execute': 'qmp_capabilities' }
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| {"return": {}}
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| { 'execute': 'drive-mirror',
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|        'arguments': {
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|            'job-id': 'mirror',
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|            'device': 'source',
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|            'target': 'TEST_DIR/t.IMGFMT.overlay1',
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|            'mode':   'existing',
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|            'sync':   'top'
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|        } }
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| {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "created", "id": "mirror"}}
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| {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "running", "id": "mirror"}}
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| {"return": {}}
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| {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "ready", "id": "mirror"}}
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| {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "mirror", "len": 65536, "offset": 65536, "speed": 0, "type": "mirror"}}
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| { 'execute': 'block-job-complete',
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|        'arguments': { 'device': 'mirror' } }
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| {"return": {}}
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| {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "waiting", "id": "mirror"}}
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| {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "pending", "id": "mirror"}}
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| {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "mirror", "len": 65536, "offset": 65536, "speed": 0, "type": "mirror"}}
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| { 'execute': 'quit' }
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| {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "concluded", "id": "mirror"}}
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| {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "null", "id": "mirror"}}
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| {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false, "reason": "host-qmp-quit"}}
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| {"return": {}}
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| *** done
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