On Thu, Mar 24, 2022 at 8:54 AM Hillf Danton <hdanton@xxxxxxxx> wrote:
>
> On Tue, 22 Mar 2022 09:59:14 +0800 Jason Wang wrote:
> >
> > Yes, there will be no "infinite" loop, but since the loop is triggered
> > by userspace. It looks to me it will delay the flush/drain of the
> > workqueue forever which is still suboptimal.
>
> Usually it is barely possible to shoot two birds using a stone.
>
> Given the "forever", I am inclined to not running faster, hehe, though
> another cobble is to add another line in the loop checking if mvdev is
> unregistered, and for example make mvdev->cvq unready before destroying
> workqueue.
>
> static void mlx5_vdpa_dev_del(struct vdpa_mgmt_dev *v_mdev, struct vdpa_device *dev)
> {
> struct mlx5_vdpa_mgmtdev *mgtdev = container_of(v_mdev, struct mlx5_vdpa_mgmtdev, mgtdev);
> struct mlx5_vdpa_dev *mvdev = to_mvdev(dev);
> struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
>
> mlx5_notifier_unregister(mvdev->mdev, &ndev->nb);
> destroy_workqueue(mvdev->wq);
> _vdpa_unregister_device(dev);
> mgtdev->ndev = NULL;
> }
>
Yes, so we had
1) using a quota for re-requeue
2) using something like
while (READ_ONCE(cvq->ready)) {
...
cond_resched();
}
There should not be too much difference except we need to use
cancel_work_sync() instead of flush_work for 1).
I would keep the code as is but if you stick I can change.
Thanks
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