> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Wednesday, October 26, 2022 2:12 AM
>
> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
>
> These complement the group interfaces and are for use by VFIO. The main
s/VFIO/iommufd/
> difference is that multiple devices in the same group can all share the
> ownership by passing the same ownership pointer.
>
> Move the common code into shared functions.
>
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> ---
> drivers/iommu/iommu.c | 116 +++++++++++++++++++++++++++++++++-------
> --
> include/linux/iommu.h | 13 +++++
> 2 files changed, 104 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 65a3b3d886dc00..e34dde68ae2b0d 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -3148,14 +3148,33 @@ static int
> __iommu_group_alloc_blocking_domain(struct iommu_group *group)
> return 0;
> }
>
> +static int __iommu_take_dma_ownership(struct iommu_group *group, void
> *owner)
> +{
> + int ret;
> +
> + if (group->domain && group->domain != group->default_domain)
> + return -EBUSY;
remove the space before -EBUSY
> +int iommu_device_claim_dma_owner(struct device *dev, void *owner)
> {
> - int ret;
> + struct iommu_group *group = iommu_group_get(dev);
> + int ret = 0;
> +
> + if (!group)
> + return -ENODEV;
>
> mutex_lock(&group->mutex);
> - if (WARN_ON(!group->owner_cnt || !group->owner))
> + if (group->owner_cnt) {
> + if (group->owner != owner) {
> + ret = -EPERM;
> + goto unlock_out;
> + }
check owner!=NULL otherwise this call may inadvertently succeed
if the caller assigns a NULL owner while the group has already been
grabbed by a kernel driver.
