On 10.03.20 12:19, Michael S. Tsirkin wrote:
> On Tue, Mar 10, 2020 at 12:12:50PM +0100, David Hildenbrand wrote:
>>>>  static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb)
>>>> @@ -971,7 +950,22 @@ static int virtballoon_probe(struct virtio_device 
>>>> *vdev)
>>>>                                              VIRTIO_BALLOON_CMD_ID_STOP);
>>>>            spin_lock_init(&vb->free_page_list_lock);
>>>>            INIT_LIST_HEAD(&vb->free_page_list);
>>>> +          /*
>>>> +           * We're allowed to reuse any free pages, even if they are
>>>> +           * still to be processed by the host.
>>>> +           */
>>>> +          err = virtio_balloon_register_shrinker(vb);
>>>> +          if (err)
>>>> +                  goto out_del_balloon_wq;
>>>>    }
>>>> +  if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) {
>>>> +          vb->oom_nb.notifier_call = virtio_balloon_oom_notify;
>>>> +          vb->oom_nb.priority = VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY;
>>>> +          err = register_oom_notifier(&vb->oom_nb);
>>>> +          if (err < 0)
>>>> +                  goto out_unregister_shrinker;
>>>> +  }
>>>> +
>>>
>>>
>>> Let's decide whether we want an empty line after }, or not, and stick to
>>> it. I prefer an empty line but no biggie as long as we are consistent.
>>
>> Can add one.
>>
>>>
>>>>    if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
>>>>            /* Start with poison val of 0 representing general init */
>>>>            __u32 poison_val = 0;
>>>> @@ -986,15 +980,6 @@ static int virtballoon_probe(struct virtio_device 
>>>> *vdev)
>>>>            virtio_cwrite(vb->vdev, struct virtio_balloon_config,
>>>>                          poison_val, &poison_val);
>>>>    }
>>>> -  /*
>>>> -   * We continue to use VIRTIO_BALLOON_F_DEFLATE_ON_OOM to decide if a
>>>> -   * shrinker needs to be registered to relieve memory pressure.
>>>> -   */
>>>> -  if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) {
>>>> -          err = virtio_balloon_register_shrinker(vb);
>>>> -          if (err)
>>>> -                  goto out_del_balloon_wq;
>>>> -  }
>>>>  
>>>>    vb->pr_dev_info.report = virtballoon_free_page_report;
>>>>    if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
>>>> @@ -1003,12 +988,12 @@ static int virtballoon_probe(struct virtio_device 
>>>> *vdev)
>>>>            capacity = virtqueue_get_vring_size(vb->reporting_vq);
>>>>            if (capacity < PAGE_REPORTING_CAPACITY) {
>>>>                    err = -ENOSPC;
>>>> -                  goto out_unregister_shrinker;
>>>> +                  goto out_unregister_oom;
>>>>            }
>>>>  
>>>>            err = page_reporting_register(&vb->pr_dev_info);
>>>>            if (err)
>>>> -                  goto out_unregister_shrinker;
>>>> +                  goto out_unregister_oom;
>>>>    }
>>>>  
>>>>    virtio_device_ready(vdev);
>>>> @@ -1017,8 +1002,11 @@ static int virtballoon_probe(struct virtio_device 
>>>> *vdev)
>>>>            virtballoon_changed(vdev);
>>>>    return 0;
>>>>  
>>>> +out_unregister_oom:
>>>> +  if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
>>>> +          unregister_oom_notifier(&vb->oom_nb);
>>>>  out_unregister_shrinker:
>>>> -  if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
>>>> +  if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
>>>>            virtio_balloon_unregister_shrinker(vb);
>>>
>>>
>>> What's with vdev versus vb->vdev here?
>>> I suggest we keep using vb->vdev to make the patch minimal if we can.
>>> Same elsewhere.
>>
>> As we touch this line either way, does it really make a difference? No
>> strong opinion. Can just do a vb->vdev and clean this up globally later.
>>
> 
> Let's just be consistent. I guess that means keep using vb->vdev
> everywhere.

It's already really inconsistent, so I'll use vb->vdev in this patch and
cleanup the other users later.

-- 
Thanks,

David / dhildenb

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