iommu: Allow taking a reference on a group directly (13f59a78) · Commits · 戴 / test

iommu_group_get_for_dev() expects that the IOMMU driver's device_group callback return a group with a reference held for the given device. Whilst allocating a new group is fine, and pci_device_group() correctly handles reusing an existing group, there is no general means for IOMMU drivers doing their own group lookup to take additional references on an existing group pointer without having to also store device pointers or resort to elaborate trickery. Add an IOMMU-driver-specific function to fill the hole. Acked-by:

Sricharan R <sricharan@codeaurora.org> Signed-off-by:

Robin Murphy <robin.murphy@arm.com> Signed-off-by:

Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -551,6 +551,19 @@ struct iommu_group iommu_group_get(struct device dev)
		}
		EXPORT_SYMBOL_GPL(iommu_group_get);

		/**
		* iommu_group_ref_get - Increment reference on a group
		* @group: the group to use, must not be NULL
		*
		* This function is called by iommu drivers to take additional references on an
		* existing group. Returns the given group for convenience.
		*/
		struct iommu_group iommu_group_ref_get(struct iommu_group group)
		{
		kobject_get(group->devices_kobj);
		return group;
		}

		/**
		* iommu_group_put - Decrement group reference
		* @group: the group to use

include/linux/iommu.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -253,6 +253,7 @@ extern void iommu_group_remove_device(struct device *dev);
		extern int iommu_group_for_each_dev(struct iommu_group group, void data,
		int (fn)(struct device , void *));
		extern struct iommu_group iommu_group_get(struct device dev);
		extern struct iommu_group iommu_group_ref_get(struct iommu_group group);
		extern void iommu_group_put(struct iommu_group *group);
		extern int iommu_group_register_notifier(struct iommu_group *group,
		struct notifier_block *nb);

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