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

["Michael S. Tsirkin" <mst@redhat.com>]

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.

> 
> > ---
> > 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
> >