vfio/ccw: Use the new device life cycle helpers

ccw is the only exception which cannot use vfio_alloc_device() because
its private device structure is designed to serve both mdev and parent.
Life cycle of the parent is managed by css_driver so vfio_ccw_private
must be allocated/freed in css_driver probe/remove path instead of
conforming to vfio core life cycle for mdev.

Given that use a wait/completion scheme so the mdev remove path waits
after vfio_put_device() until receiving a completion notification from
@release. The completion indicates that all active references on
vfio_device have been released.

After that point although free of vfio_ccw_private is delayed to
css_driver it's at least guaranteed to have no parallel reference on
released vfio device part from other code paths.

memset() in @probe is removed. vfio_device is either already cleared
when probed for the first time or cleared in @release from last probe.

The right fix is to introduce separate structures for mdev and parent,
but this won't happen in short term per prior discussions.

Remove vfio_init/uninit_group_dev() as no user now.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Link: https://lore.kernel.org/r/20220921104401.38898-14-kevin.tian@intel.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 5 insertions, 18 deletions

diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index b9c6a97d647a..12952858d903 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -483,28 +483,13 @@ static struct vfio_device *vfio_group_get_device(struct vfio_group *group,
 /*
  * VFIO driver API
  */
-void vfio_init_group_dev(struct vfio_device *device, struct device *dev,
-			 const struct vfio_device_ops *ops)
-{
-	init_completion(&device->comp);
-	device->dev = dev;
-	device->ops = ops;
-}
-EXPORT_SYMBOL_GPL(vfio_init_group_dev);
-
-void vfio_uninit_group_dev(struct vfio_device *device)
-{
-	vfio_release_device_set(device);
-}
-EXPORT_SYMBOL_GPL(vfio_uninit_group_dev);
-
 /* Release helper called by vfio_put_device() */
 void vfio_device_release(struct kref *kref)
 {
 	struct vfio_device *device =
 			container_of(kref, struct vfio_device, kref);
 
-	vfio_uninit_group_dev(device);
+	vfio_release_device_set(device);
 
 	/*
 	 * kvfree() cannot be done here due to a life cycle mess in
@@ -562,7 +547,9 @@ int vfio_init_device(struct vfio_device *device, struct device *dev,
 {
 	int ret;
 
-	vfio_init_group_dev(device, dev, ops);
+	init_completion(&device->comp);
+	device->dev = dev;
+	device->ops = ops;
 
 	if (ops->init) {
 		ret = ops->init(device);
@@ -574,7 +561,7 @@ int vfio_init_device(struct vfio_device *device, struct device *dev,
 	return 0;
 
 out_uninit:
-	vfio_uninit_group_dev(device);
+	vfio_release_device_set(device);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(vfio_init_device);