On Tue, 1 Nov 2022 08:38:21 -0300
Jason Gunthorpe <jgg@xxxxxxxx> wrote:
> On Tue, Nov 01, 2022 at 08:49:28AM +0000, Tian, Kevin wrote:
> > > From: Anthony DeRossi <ajderossi@xxxxxxxxx>
> > > Sent: Thursday, October 27, 2022 3:43 AM
> > >
> > > -static bool vfio_pci_dev_set_needs_reset(struct vfio_device_set *dev_set)
> > > +static bool vfio_pci_core_needs_reset(struct vfio_pci_core_device *vdev)
> > > {
> > > + struct vfio_device_set *dev_set = vdev->vdev.dev_set;
> > > struct vfio_pci_core_device *cur;
> > > bool needs_reset = false;
> > >
> > > + if (vdev->vdev.open_count > 1)
> > > + return false;
> >
> > WARN_ON()
> >
> > > +
> > > list_for_each_entry(cur, &dev_set->device_list, vdev.dev_set_list) {
> > > - /* No VFIO device in the set can have an open device FD */
> > > - if (cur->vdev.open_count)
> > > + /* Only the VFIO device being reset can have an open FD */
> > > + if (cur != vdev && cur->vdev.open_count)
> > > return false;
> >
> > not caused by this patch but while at it...
> >
> > open_count is defined not for driver use:
> >
> > /* Members below here are private, not for driver use */
> > unsigned int index;
> > struct device device; /* device.kref covers object life circle */
> > refcount_t refcount; /* user count on registered device*/
> > unsigned int open_count;
> > struct completion comp;
> > struct list_head group_next;
> > struct list_head iommu_entry;
> >
> > prefer to a wrapper or move it to the public section of vfio_device.
>
> I've been meaning to take a deeper look, but I'm thinking vfio_pci
> doesn't need open_count at all any more.
>
> open_count was from before we changed the core code to call
> open_device only once. If we are only a call chain from
> open_device/close_device then we know that the open_count must be 1.
That accounts for the first test, we don't need to test open_count on
the calling device in this path, but the idea here is that we want to
test whether we're the last close_device among the set. Not sure how
we'd do that w/o some visibility to open_count. Maybe we need a
vfio_device_set_open_count() that when 1 we know we're the first open
or last close? Thanks,
Alex
