When the 'cont' command resumes guest execution the vm change state
handlers are invoked. Unfortunately there is no explicit ordering
between classic qemu_add_vm_change_state_handler() callbacks. When two
layers of code both use vm change state handlers, we don't control which
handler runs first.
virtio-scsi with iothreads hits a deadlock when a failed SCSI command is
restarted and completes before the iothread is re-initialized.
This patch uses the new qdev_add_vm_change_state_handler() API to
guarantee that virtio-scsi's virtio change state handler executes before
the SCSI bus children. This way DMA is restarted after the iothread has
re-initialized.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
1a8c091c4e