Re: [PATCH v8 10/11] vfio/pci: Add dma-buf export support for MMIO regions

Leon Romanovsky
2025-11-19T20:51:01Z

On Wed, Nov 19, 2025 at 03:41:20PM -0400, Jason Gunthorpe wrote:
> On Tue, Nov 18, 2025 at 11:56:14PM +0000, Tian, Kevin wrote:
> > > > > + down_write(&vdev->memory_lock);
> > > > > + list_for_each_entry_safe(priv, tmp, &vdev->dmabufs, dmabufs_elm)
> > > > > {
> > > > > + if (!get_file_active(&priv->dmabuf->file))
> > > > > + continue;
> > > > > +
> > > > > + dma_resv_lock(priv->dmabuf->resv, NULL);
> > > > > + list_del_init(&priv->dmabufs_elm);
> > > > > + priv->vdev = NULL;
> > > > > + priv->revoked = true;
> > > > > + dma_buf_move_notify(priv->dmabuf);
> > > > > + dma_resv_unlock(priv->dmabuf->resv);
> > > > > + vfio_device_put_registration(&vdev->vdev);
> > > > > + fput(priv->dmabuf->file);
> > > >
> > > > dma_buf_put(priv->dmabuf), consistent with other places.
> > >
> > > Someone else said this, I don't agree, the above got the get via
> > >
> > > get_file_active() instead of a dma_buf version..
> > >
> > > So we should pair with get_file_active() vs fput().
> > >
> > > Christian rejected the idea of adding a dmabuf wrapper for
> > > get_file_active(), oh well.
> >
> > Okay then vfio_pci_dma_buf_move() should be changed. It uses
> > get_file_active() to pair dma_buf_put().
>
> Makes sense, Leon can you fix it?

Sure,

diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c
index e7511cad8e06..c67c1ca7e4bf 100644
--- a/drivers/vfio/pci/vfio_pci_dmabuf.c
+++ b/drivers/vfio/pci/vfio_pci_dmabuf.c
@@ -300,7 +300,7 @@ void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, bool revoked)
dma_buf_move_notify(priv->dmabuf);
dma_resv_unlock(priv->dmabuf->resv);
}
- dma_buf_put(priv->dmabuf);
+ fput(priv->dmabuf->file);
}
}

>
> Thanks,
> Jason