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virtio-scsi: restart DMA after iothread 

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>
This commit is contained in:
Stefan Hajnoczi 2019-06-20 18:37:09 +01:00 committed by Kevin Wolf
parent e965ffa70a
commit 1a8c091c4e
2 changed files with 4 additions and 4 deletions
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4
hw/scsi/scsi-bus.c
View File

@ -207,8 +207,8 @@ static void scsi_qdev_realize(DeviceState *qdev, Error **errp)
error_propagate(errp, local_err);
return;
}
dev->vmsentry = qemu_add_vm_change_state_handler(scsi_dma_restart_cb,
dev);
dev->vmsentry = qdev_add_vm_change_state_handler(DEVICE(dev),
scsi_dma_restart_cb, dev);
}
static void scsi_qdev_unrealize(DeviceState *qdev, Error **errp)

4
hw/virtio/virtio.c
View File

@ -2362,8 +2362,8 @@ void virtio_init(VirtIODevice *vdev, const char *name,
} else {
vdev->config = NULL;
}
vdev->vmstate = qemu_add_vm_change_state_handler(virtio_vmstate_change,
vdev);
vdev->vmstate = qdev_add_vm_change_state_handler(DEVICE(vdev),
virtio_vmstate_change, vdev);
vdev->device_endian = virtio_default_endian();
vdev->use_guest_notifier_mask = true;
}