Re: [Qemu-devel] [PATCH v9 03/12] vfio: Rearrange functions to get vfio_group from dev

[Alex Williamson]

On Tue, 18 Oct 2016 02:52:03 +0530
Kirti Wankhede <address@hidden> wrote:

> Rearrange functions to have common function to increment container_users.
> 
> Signed-off-by: Kirti Wankhede <address@hidden>
> Signed-off-by: Neo Jia <address@hidden>
> Change-Id: I1f93262bdbab75094bc24b087b29da35ba70c4c6
> ---
>  drivers/vfio/vfio.c | 57 
> ++++++++++++++++++++++++++++++++++-------------------
>  1 file changed, 37 insertions(+), 20 deletions(-)

Ideally these would be two separate patches, one pulling
vfio_group_get_from_dev() out of vfio_device_get_from_dev() and
replacing the existing use, the other doing the same for
vfio_group_add_container_user().  Otherwise it looks good.  Thanks,

Alex

> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index d1d70e0b011b..2e83bdf007fe 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -480,6 +480,21 @@ static struct vfio_group *vfio_group_get_from_minor(int 
> minor)
>       return group;
>  }
>  
> +static struct vfio_group *vfio_group_get_from_dev(struct device *dev)
> +{
> +     struct iommu_group *iommu_group;
> +     struct vfio_group *group;
> +
> +     iommu_group = iommu_group_get(dev);
> +     if (!iommu_group)
> +             return NULL;
> +
> +     group = vfio_group_get_from_iommu(iommu_group);
> +     iommu_group_put(iommu_group);
> +
> +     return group;
> +}
> +
>  /**
>   * Device objects - create, release, get, put, search
>   */
> @@ -811,16 +826,10 @@ EXPORT_SYMBOL_GPL(vfio_add_group_dev);
>   */
>  struct vfio_device *vfio_device_get_from_dev(struct device *dev)
>  {
> -     struct iommu_group *iommu_group;
>       struct vfio_group *group;
>       struct vfio_device *device;
>  
> -     iommu_group = iommu_group_get(dev);
> -     if (!iommu_group)
> -             return NULL;
> -
> -     group = vfio_group_get_from_iommu(iommu_group);
> -     iommu_group_put(iommu_group);
> +     group = vfio_group_get_from_dev(dev);
>       if (!group)
>               return NULL;
>  
> @@ -1376,6 +1385,23 @@ static bool vfio_group_viable(struct vfio_group *group)
>                                        group, vfio_dev_viable) == 0);
>  }
>  
> +static int vfio_group_add_container_user(struct vfio_group *group)
> +{
> +     if (!atomic_inc_not_zero(&group->container_users))
> +             return -EINVAL;
> +
> +     if (group->noiommu) {
> +             atomic_dec(&group->container_users);
> +             return -EPERM;
> +     }
> +     if (!group->container->iommu_driver || !vfio_group_viable(group)) {
> +             atomic_dec(&group->container_users);
> +             return -EINVAL;
> +     }
> +
> +     return 0;
> +}
> +
>  static const struct file_operations vfio_device_fops;
>  
>  static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
> @@ -1685,23 +1711,14 @@ static const struct file_operations vfio_device_fops 
> = {
>  struct vfio_group *vfio_group_get_external_user(struct file *filep)
>  {
>       struct vfio_group *group = filep->private_data;
> +     int ret;
>  
>       if (filep->f_op != &vfio_group_fops)
>               return ERR_PTR(-EINVAL);
>  
> -     if (!atomic_inc_not_zero(&group->container_users))
> -             return ERR_PTR(-EINVAL);
> -
> -     if (group->noiommu) {
> -             atomic_dec(&group->container_users);
> -             return ERR_PTR(-EPERM);
> -     }
> -
> -     if (!group->container->iommu_driver ||
> -                     !vfio_group_viable(group)) {
> -             atomic_dec(&group->container_users);
> -             return ERR_PTR(-EINVAL);
> -     }
> +     ret = vfio_group_add_container_user(group);
> +     if (ret)
> +             return ERR_PTR(ret);
>  
>       vfio_group_get(group);
>