Hi Kevin,
On 2022/8/18 15:46, Tian, Kevin wrote:
From: Jason Gunthorpe <jgg@xxxxxxxxxx>
Sent: Tuesday, August 16, 2022 12:50 AM
This counts the number of devices attached to a vfio_group, ie the number
of items in the group->device_list.
It is only read in vfio_pin_pages(), however that function already does
vfio_assert_device_open(). Given an opened device has to already be
properly setup with a group, this test and variable are redundant. Remove
it.
I didn't get the rationale behind. The original check was for whether
the group is singleton. Why is it equivalent to the condition of an
opened device?
Though I do think this check is unnecessary. All the devices in the group
share the container and iommu domain which is what the pinning
operation applies to. I'm not sure why the singleton restriction was
added in the first place.
see if your confusion is addressed in below link?
https://lore.kernel.org/kvm/BN9PR11MB5276F9EB0295CBD485A58D308C6D9@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/T/#m42eaf1548235810820d7e2ad1491092c4b0bbcba
--
Regards,
Yi Liu
