Re: [PATCH] iommu: add a function to find an iommu group by id

[Don Dutile]

On 03/25/2013 10:28 AM, Alex Williamson wrote:
> On Mon, 2013-03-25 at 10:23 +1100, Alexey Kardashevskiy wrote:
> > As IOMMU groups are exposed to the user space by their numbers,
> > the user space can use them in various kernel APIs so the kernel
> > might need an API to find a group by its ID.
> >
> > As an example, QEMU VFIO on PPC64 platform needs it to associate
> > a logical bus number (LIOBN) with a specific IOMMU group in order
> > to support in-kernel handling of DMA map/unmap requests.
> >
> > The patch adds the iommu_group_get_by_id(id) function which performs
> > such search.
>
> Subject: [PATCH v3]....
>
> v2 was the last one, where's the changelog for v3?
> > v2: fixed reference counting.
and changed function name...

> > Signed-off-by: Alexey Kardashevskiy<aik@xxxxxxxxx>
> > ---
>
> Acked-by: Alex Williamson<alex.williamson@xxxxxxxxxx>
>
> >   drivers/iommu/iommu.c |   29 +++++++++++++++++++++++++++++
> >   include/linux/iommu.h |    1 +
> >   2 files changed, 30 insertions(+)
> >
> > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> > index 1065a1a..0de83eb 100644
> > --- a/drivers/iommu/iommu.c
> > +++ b/drivers/iommu/iommu.c
> > @@ -204,6 +204,35 @@ again:
> >   }
> >   EXPORT_SYMBOL_GPL(iommu_group_alloc);
> >
> > +struct iommu_group *iommu_group_get_by_id(int id)
> > +{
> > +	struct kobject *group_kobj;
> > +	struct iommu_group *group;
> > +	const char *name;
> > +
> > +	if (!iommu_group_kset)
> > +		return NULL;
> > +
> > +	name = kasprintf(GFP_KERNEL, "%d", id);
> > +	if (!name)
> > +		return NULL;
> > +
> > +	group_kobj = kset_find_obj(iommu_group_kset, name);
> > +	kfree(name);
> > +
> > +	if (!group_kobj)
> > +		return NULL;
> > +
> > +	group = container_of(group_kobj, struct iommu_group, kobj);
> > +	BUG_ON(group->id != id);
> > +
> > +	kobject_get(group->devices_kobj);
> > +	kobject_put(&group->kobj);
> > +
> > +	return group;
> > +}
> > +EXPORT_SYMBOL_GPL(iommu_group_get_by_id);
> > +
> >   /**
> >    * iommu_group_get_iommudata - retrieve iommu_data registered for a group
> >    * @group: the group
> > diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> > index f3b99e1..00e5d7d 100644
> > --- a/include/linux/iommu.h
> > +++ b/include/linux/iommu.h
> > @@ -113,6 +113,7 @@ struct iommu_ops {
> >   extern int bus_set_iommu(struct bus_type *bus, struct iommu_ops *ops);
> >   extern bool iommu_present(struct bus_type *bus);
> >   extern struct iommu_domain *iommu_domain_alloc(struct bus_type *bus);
> > +extern struct iommu_group *iommu_group_get_by_id(int id);
> >   extern void iommu_domain_free(struct iommu_domain *domain);
> >   extern int iommu_attach_device(struct iommu_domain *domain,
> >   			       struct device *dev);
>
>
>
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