On Sun, May 21, 2023 at 07:31:38PM +0800, Baolu Lu wrote:
> I revisited this patch. And I still have some questions.
>
> On 5/20/23 2:42 AM, Jason Gunthorpe wrote:
> > -/*
> > - * Remove the iommu_group from the struct device. The attached group must be put
> > - * by the caller after releaseing the group->mutex.
> > - */
> > +/* Remove the iommu_group from the struct device. */
> > static void __iommu_group_remove_device(struct device *dev)
> > {
> > struct iommu_group *group = dev->iommu_group;
> > struct group_device *device;
> > + mutex_lock(&group->mutex);
> > lockdep_assert_held(&group->mutex);
>
> By moving mutex_lock/unlock into this helper, above
> lockdep_assert_held() is unnecessary.
Woops, got it thanks
> The group->devices_kobj was increased on the probe device path twice:
>
> - iommu_init_device() - allocate the group
> - iommu_group_add_device() - add device to the group
>
> But, on the release path, it seems that group->devices_kobj is only
> decreased once.
>
> Did I overlook anything? Otherwise, the group will never be released,
> right?
Your answer was right, when VFIO uses add/remove device it doesn't do
init_device.
Jason
