Re: [PATCH v5 10/17] iommu: Introduce iommu_group_mutex_assert()

[Jason Gunthorpe <jgg@ziepe.ca>]

On Tue, Jan 16, 2024 at 04:53:28PM +0000, Vasant Hegde wrote:

> +/**
> + * iommu_group_mutex_assert - Check device group mutex lock
> + * @dev: the device that has group param set
> + *
> + * This function is called by an iommu driver to check whether it holds
> + * group mutex lock for the given device or not.
> + *
> + * Note that this function must be called after device group param is set.
> + */
> +void iommu_group_mutex_assert(struct device *dev)
> +{
> +	struct iommu_group *group = dev->iommu_group;
> +
> +	lockdep_assert_held(&group->mutex);
> +}
> +EXPORT_SYMBOL_GPL(iommu_group_mutex_assert);
> +
>  static struct device *iommu_group_first_dev(struct iommu_group *group)
>  {
>  	lockdep_assert_held(&group->mutex);
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 7f6342bc71c3..c983b6a1ebce 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -751,6 +751,7 @@ extern int iommu_group_set_name(struct iommu_group *group, const char *name);
>  extern int iommu_group_add_device(struct iommu_group *group,
>  				  struct device *dev);
>  extern void iommu_group_remove_device(struct device *dev);
> +extern void iommu_group_mutex_assert(struct device *dev);

This shouldn't be unconditional. Like this outside the other ifdefs:

#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_IOMMU)
void iommu_group_mutex_assert(struct device *dev);
#else
static inline void iommu_group_mutex_assert(struct device *dev)
{
}
#endif

And a similar ifdef around the implementation I suppose.

Jason