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

[Don Dutile <ddutile-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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-sLpHqDYs0B2HXe+LvDLADg@public.gmane.org>
>> ---
>
> Acked-by: Alex Williamson<alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>
>>   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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