vfio: centralize module refcount in subsystem layer

Remove code duplication and move module refcounting to the subsystem
module.
Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20210518192133.59195-2-mgurtovoy@nvidia.comSigned-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/fsl-mc/vfio_fsl_mc.c

@@ -140,26 +140,18 @@ static int vfio_fsl_mc_open(struct vfio_device *core_vdev)
 {
 	struct vfio_fsl_mc_device *vdev =
 		container_of(core_vdev, struct vfio_fsl_mc_device, vdev);
-	int ret;
-
-	if (!try_module_get(THIS_MODULE))
-		return -ENODEV;
+	int ret = 0;
 
 	mutex_lock(&vdev->reflck->lock);
 	if (!vdev->refcnt) {
 		ret = vfio_fsl_mc_regions_init(vdev);
 		if (ret)
-			goto err_reg_init;
+			goto out;
 	}
 	vdev->refcnt++;
-
+out:
 	mutex_unlock(&vdev->reflck->lock);
 
-	return 0;
-
-err_reg_init:
-	mutex_unlock(&vdev->reflck->lock);
-	module_put(THIS_MODULE);
 	return ret;
 }
 
@@ -196,8 +188,6 @@ static void vfio_fsl_mc_release(struct vfio_device *core_vdev)
 	}
 
 	mutex_unlock(&vdev->reflck->lock);
-
-	module_put(THIS_MODULE);
 }
 
 static long vfio_fsl_mc_ioctl(struct vfio_device *core_vdev,

drivers/vfio/mdev/vfio_mdev.c

@@ -26,19 +26,10 @@ static int vfio_mdev_open(struct vfio_device *core_vdev)
 	struct mdev_device *mdev = to_mdev_device(core_vdev->dev);
 	struct mdev_parent *parent = mdev->type->parent;
 
-	int ret;
-
 	if (unlikely(!parent->ops->open))
 		return -EINVAL;
 
-	if (!try_module_get(THIS_MODULE))
-		return -ENODEV;
-
-	ret = parent->ops->open(mdev);
-	if (ret)
-		module_put(THIS_MODULE);
-
-	return ret;
+	return parent->ops->open(mdev);
 }
 
 static void vfio_mdev_release(struct vfio_device *core_vdev)
@@ -48,8 +39,6 @@ static void vfio_mdev_release(struct vfio_device *core_vdev)
 
 	if (likely(parent->ops->release))
 		parent->ops->release(mdev);
-
-	module_put(THIS_MODULE);
 }
 
 static long vfio_mdev_unlocked_ioctl(struct vfio_device *core_vdev,

drivers/vfio/pci/vfio_pci.c

@@ -558,8 +558,6 @@ static void vfio_pci_release(struct vfio_device *core_vdev)
 	}
 
 	mutex_unlock(&vdev->reflck->lock);
-
-	module_put(THIS_MODULE);
 }
 
 static int vfio_pci_open(struct vfio_device *core_vdev)
@@ -568,9 +566,6 @@ static int vfio_pci_open(struct vfio_device *core_vdev)
 		container_of(core_vdev, struct vfio_pci_device, vdev);
 	int ret = 0;
 
-	if (!try_module_get(THIS_MODULE))
-		return -ENODEV;
-
 	mutex_lock(&vdev->reflck->lock);
 
 	if (!vdev->refcnt) {
@@ -584,8 +579,6 @@ static int vfio_pci_open(struct vfio_device *core_vdev)
 	vdev->refcnt++;
 error:
 	mutex_unlock(&vdev->reflck->lock);
-	if (ret)
-		module_put(THIS_MODULE);
 	return ret;
 }
 

drivers/vfio/platform/vfio_platform_common.c

@@ -241,8 +241,6 @@ static void vfio_platform_release(struct vfio_device *core_vdev)
 	}
 
 	mutex_unlock(&driver_lock);
-
-	module_put(vdev->parent_module);
 }
 
 static int vfio_platform_open(struct vfio_device *core_vdev)
@@ -251,9 +249,6 @@ static int vfio_platform_open(struct vfio_device *core_vdev)
 		container_of(core_vdev, struct vfio_platform_device, vdev);
 	int ret;
 
-	if (!try_module_get(vdev->parent_module))
-		return -ENODEV;
-
 	mutex_lock(&driver_lock);
 
 	if (!vdev->refcnt) {
@@ -291,7 +286,6 @@ static int vfio_platform_open(struct vfio_device *core_vdev)
 	vfio_platform_regions_cleanup(vdev);
 err_reg:
 	mutex_unlock(&driver_lock);
-	module_put(vdev->parent_module);
 	return ret;
 }
 

drivers/vfio/vfio.c

@@ -1369,8 +1369,14 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
 	if (IS_ERR(device))
 		return PTR_ERR(device);
 
+	if (!try_module_get(device->dev->driver->owner)) {
+		vfio_device_put(device);
+		return -ENODEV;
+	}
+
 	ret = device->ops->open(device);
 	if (ret) {
+		module_put(device->dev->driver->owner);
 		vfio_device_put(device);
 		return ret;
 	}
@@ -1382,6 +1388,7 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
 	ret = get_unused_fd_flags(O_CLOEXEC);
 	if (ret < 0) {
 		device->ops->release(device);
+		module_put(device->dev->driver->owner);
 		vfio_device_put(device);
 		return ret;
 	}
@@ -1392,6 +1399,7 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
 		put_unused_fd(ret);
 		ret = PTR_ERR(filep);
 		device->ops->release(device);
+		module_put(device->dev->driver->owner);
 		vfio_device_put(device);
 		return ret;
 	}
@@ -1550,6 +1558,8 @@ static int vfio_device_fops_release(struct inode *inode, struct file *filep)
 
 	device->ops->release(device);
 
+	module_put(device->dev->driver->owner);
+
 	vfio_group_try_dissolve_container(device->group);
 
 	vfio_device_put(device);