linux-kernel - Re: [PATCH v9 03/12] vfio: Rearrange functions to get vfio

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Date:   Wed, 19 Oct 2016 11:26:20 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Kirti Wankhede <kwankhede@...dia.com>
Cc:     <pbonzini@...hat.com>, <kraxel@...hat.com>, <cjia@...dia.com>,
        <qemu-devel@...gnu.org>, <kvm@...r.kernel.org>,
        <kevin.tian@...el.com>, <jike.song@...el.com>,
        <bjsdjshi@...ux.vnet.ibm.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v9 03/12] vfio: Rearrange functions to get vfio_group
 from dev

On Tue, 18 Oct 2016 02:52:03 +0530
Kirti Wankhede <kwankhede@...dia.com> wrote:

> Rearrange functions to have common function to increment container_users.
> 
> Signed-off-by: Kirti Wankhede <kwankhede@...dia.com>
> Signed-off-by: Neo Jia <cjia@...dia.com>
> 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);
>