Re: [PATCH v3] vfio/ap_ops: Add missed vfio_uninit_group_dev()

Tony Krowiak
2021-09-22T13:05:20Z

On 9/21/21 8:11 AM, Jason Gunthorpe wrote:
> Without this call an xarray entry is leaked when the vfio_ap device is
> unprobed. It was missed when the below patch was rebased across the
> dev_set patch. Keep the remove function in the same order as the error
> unwind in probe.
>
> Fixes: eb0feefd4c02 ("vfio/ap_ops: Convert to use vfio_register_group_dev()")
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Tested-by: Tony Krowiak <akrowiak@linux.ibm.com>
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
> drivers/s390/crypto/vfio_ap_ops.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> v3:
> - Keep the remove sequence the same as remove to avoid a lockdep splat
> v2: https://lore.kernel.org/r/0-v2-25656bbbb814+41-ap_uninit_jgg@nvidia.com/
> - Fix corrupted diff
> v1: https://lore.kernel.org/r/0-v1-3a05c6000668+2ce62-ap_uninit_jgg@nvidia.com/
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 118939a7729a1e..623d5269a52ce5 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -361,6 +361,7 @@ static int vfio_ap_mdev_probe(struct mdev_device *mdev)
> mutex_lock(&matrix_dev->lock);
> list_del(&matrix_mdev->node);
> mutex_unlock(&matrix_dev->lock);
> + vfio_uninit_group_dev(&matrix_mdev->vdev);
> kfree(matrix_mdev);
> err_dec_available:
> atomic_inc(&matrix_dev->available_instances);
> @@ -376,9 +377,10 @@ static void vfio_ap_mdev_remove(struct mdev_device *mdev)
> mutex_lock(&matrix_dev->lock);
> vfio_ap_mdev_reset_queues(matrix_mdev);
> list_del(&matrix_mdev->node);
> + mutex_unlock(&matrix_dev->lock);
> + vfio_uninit_group_dev(&matrix_mdev->vdev);
> kfree(matrix_mdev);
> atomic_inc(&matrix_dev->available_instances);

I think the above line of code should be done under the
matrix_dev->lock after removing the matrix_mdev from
the list since it is changing a value in matrix_dev.

> - mutex_unlock(&matrix_dev->lock);
> }
>
> static ssize_t name_show(struct mdev_type *mtype,
>
> base-commit: 6880fa6c56601bb8ed59df6c30fd390cc5f6dd8f