Re: [PATCH v2 1/3] virtio: add ability to delete vq through a pointer

[Pan Nengyuan <pannengyuan@huawei.com>]

On 2019/12/10 0:58, Michael S. Tsirkin wrote:
> On Mon, Dec 09, 2019 at 11:43:20AM -0500, Michael S. Tsirkin wrote:
>> On Wed, Dec 04, 2019 at 03:31:54PM +0800, pannengyuan@huawei.com wrote:
>>> From: Pan Nengyuan <pannengyuan@huawei.com>
>>>
>>> Devices tend to maintain vq pointers, allow deleting them trough a vq pointer.
>>
>> You want to also mention something about clearing
>> .used_elems to avoid chances of double free.
>>
>>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>>> Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
>>
>>
>> So let's just name the new one virtio_del_queue then,
>> and drop the old one.
> 
> I tried but it seems like too much work.

Yes, some of them do not maintain the vq pointer, so can we just rename
the virtio_delete_queue to avoid confusion?

I have sent a new version before your reply, can you check whether it's
appropriate or not?

> 
>>
>>> ---
>>> Changes v2 to v1:
>>> - add a new function virtio_delete_queue to cleanup vq through a vq pointer
>>> ---
>>>  hw/virtio/virtio.c         | 16 +++++++++++-----
>>>  include/hw/virtio/virtio.h |  2 ++
>>>  2 files changed, 13 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>>> index 04716b5..6de3cfd 100644
>>> --- a/hw/virtio/virtio.c
>>> +++ b/hw/virtio/virtio.c
>>> @@ -2330,17 +2330,23 @@ VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
>>>      return &vdev->vq[i];
>>>  }
>>>  
>>> +void virtio_delete_queue(VirtQueue *vq)
>>> +{
>>> +    vq->vring.num = 0;
>>> +    vq->vring.num_default = 0;
>>> +    vq->handle_output = NULL;
>>> +    vq->handle_aio_output = NULL;
>>> +    g_free(vq->used_elems);
>>> +    vq->used_elems = NULL;
>>> +}
>>> +
>>>  void virtio_del_queue(VirtIODevice *vdev, int n)
>>>  {
>>>      if (n < 0 || n >= VIRTIO_QUEUE_MAX) {
>>>          abort();
>>>      }
>>>  
>>> -    vdev->vq[n].vring.num = 0;
>>> -    vdev->vq[n].vring.num_default = 0;
>>> -    vdev->vq[n].handle_output = NULL;
>>> -    vdev->vq[n].handle_aio_output = NULL;
>>> -    g_free(vdev->vq[n].used_elems);
>>> +    virtio_delete_queue(&vdev->vq[n]);
>>>  }
>>>  
>>>  static void virtio_set_isr(VirtIODevice *vdev, int value)
>>> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
>>> index c32a815..e18756d 100644
>>> --- a/include/hw/virtio/virtio.h
>>> +++ b/include/hw/virtio/virtio.h
>>> @@ -183,6 +183,8 @@ VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
>>>  
>>>  void virtio_del_queue(VirtIODevice *vdev, int n);
>>>  
>>> +void virtio_delete_queue(VirtQueue *vq);
>>> +
>>>  void virtqueue_push(VirtQueue *vq, const VirtQueueElement *elem,
>>>                      unsigned int len);
>>>  void virtqueue_flush(VirtQueue *vq, unsigned int count);
>>> -- 
>>> 2.7.2.windows.1
>>>
> 
> 
> .
>