On 11/01/2016 11:44 AM, Alex Williamson wrote:
> On Tue, 01 Nov 2016 11:08:15 +0800
> Jike Song <jike.song@xxxxxxxxx> wrote:
>> On 10/27/2016 05:29 AM, Kirti Wankhede wrote:
>>> +static int mdev_attach_iommu(struct mdev_device *mdev)
>>> +{
>>> + int ret;
>>> + struct iommu_group *group;
>>> +
>>> + group = iommu_group_alloc();
>>> + if (IS_ERR(group))
>>> + return PTR_ERR(group);
>>
>> Maybe I overthought, but where the iommu_group is released? On successful
>> return you already have a ref, I didn't find an iommu_group_put after that.
> ...
>>> +
>>> + ret = iommu_group_add_device(group, &mdev->dev);
>>> + if (ret)
>>> + goto attach_fail;
>>> +
>>> + dev_info(&mdev->dev, "MDEV: group_id = %d\n",
>>> + iommu_group_id(group));
>>> +attach_fail:
>>> + iommu_group_put(group);
>>> + return ret;
>>> +}
>>> +
>>> +static void mdev_detach_iommu(struct mdev_device *mdev)
>>> +{
>>> + iommu_group_remove_device(&mdev->dev);
>
> Here. Adding a device to the group takes a group reference so we can
> 'put' the group to release the reference from the alloc as soon as a
> device is added. When we remove the device, that reference is removed
> and this should result in a release of the group if all other
> references are balanced. Thanks,
Now I understand, thanks :)
--
Thanks,
Jike
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