> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Wednesday, March 24, 2021 1:55 AM
>
> This is only done once, we don't need to generate code to initialize a
> structure stored in the ELF .data segment. Fill in the three required
> .driver members directly instead of copying data into them during
> mdev_register_driver().
>
> Further the to_mdev_driver() function doesn't belong in a public header,
> just inline it into the two places that need it. Finally, we can now
> clearly see that 'drv' derived from dev->driver cannot be NULL, firstly
> because the driver core forbids it, and secondly because NULL won't pass
> through the container_of(). Remove the dead code.
>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> ---
> Documentation/driver-api/vfio-mediated-device.rst | 5 +----
> drivers/vfio/mdev/mdev_driver.c | 15 +++++++--------
> drivers/vfio/mdev/vfio_mdev.c | 8 ++++++--
> include/linux/mdev.h | 6 +-----
> 4 files changed, 15 insertions(+), 19 deletions(-)
>
> diff --git a/Documentation/driver-api/vfio-mediated-device.rst
> b/Documentation/driver-api/vfio-mediated-device.rst
> index c43c1dc3333373..1779b85f014e2f 100644
> --- a/Documentation/driver-api/vfio-mediated-device.rst
> +++ b/Documentation/driver-api/vfio-mediated-device.rst
> @@ -98,13 +98,11 @@ structure to represent a mediated device's driver::
>
> /*
> * struct mdev_driver [2] - Mediated device's driver
> - * @name: driver name
> * @probe: called when new device created
> * @remove: called when device removed
> * @driver: device driver structure
> */
> struct mdev_driver {
> - const char *name;
> int (*probe) (struct mdev_device *dev);
> void (*remove) (struct mdev_device *dev);
> struct device_driver driver;
> @@ -115,8 +113,7 @@ to register and unregister itself with the core driver:
>
> * Register::
>
> - extern int mdev_register_driver(struct mdev_driver *drv,
> - struct module *owner);
> + extern int mdev_register_driver(struct mdev_driver *drv);
>
> * Unregister::
>
> diff --git a/drivers/vfio/mdev/mdev_driver.c
> b/drivers/vfio/mdev/mdev_driver.c
> index 44c3ba7e56d923..041699571b7e55 100644
> --- a/drivers/vfio/mdev/mdev_driver.c
> +++ b/drivers/vfio/mdev/mdev_driver.c
> @@ -39,7 +39,8 @@ static void mdev_detach_iommu(struct mdev_device
> *mdev)
>
> static int mdev_probe(struct device *dev)
> {
> - struct mdev_driver *drv = to_mdev_driver(dev->driver);
> + struct mdev_driver *drv =
> + container_of(dev->driver, struct mdev_driver, driver);
> struct mdev_device *mdev = to_mdev_device(dev);
> int ret;
>
> @@ -47,7 +48,7 @@ static int mdev_probe(struct device *dev)
> if (ret)
> return ret;
>
> - if (drv && drv->probe) {
> + if (drv->probe) {
> ret = drv->probe(mdev);
> if (ret)
> mdev_detach_iommu(mdev);
> @@ -58,10 +59,11 @@ static int mdev_probe(struct device *dev)
>
> static int mdev_remove(struct device *dev)
> {
> - struct mdev_driver *drv = to_mdev_driver(dev->driver);
> + struct mdev_driver *drv =
> + container_of(dev->driver, struct mdev_driver, driver);
> struct mdev_device *mdev = to_mdev_device(dev);
>
> - if (drv && drv->remove)
> + if (drv->remove)
> drv->remove(mdev);
>
> mdev_detach_iommu(mdev);
> @@ -79,16 +81,13 @@ EXPORT_SYMBOL_GPL(mdev_bus_type);
> /**
> * mdev_register_driver - register a new MDEV driver
> * @drv: the driver to register
> - * @owner: module owner of driver to be registered
> *
> * Returns a negative value on error, otherwise 0.
> **/
> -int mdev_register_driver(struct mdev_driver *drv, struct module *owner)
> +int mdev_register_driver(struct mdev_driver *drv)
> {
> /* initialize common driver fields */
> - drv->driver.name = drv->name;
> drv->driver.bus = &mdev_bus_type;
> - drv->driver.owner = owner;
>
> /* register with core */
> return driver_register(&drv->driver);
> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
> index 91b7b8b9eb9cb8..cc9507ed85a181 100644
> --- a/drivers/vfio/mdev/vfio_mdev.c
> +++ b/drivers/vfio/mdev/vfio_mdev.c
> @@ -152,14 +152,18 @@ static void vfio_mdev_remove(struct mdev_device
> *mdev)
> }
>
> static struct mdev_driver vfio_mdev_driver = {
> - .name = "vfio_mdev",
> + .driver = {
> + .name = "vfio_mdev",
> + .owner = THIS_MODULE,
> + .mod_name = KBUILD_MODNAME,
> + },
> .probe = vfio_mdev_probe,
> .remove = vfio_mdev_remove,
> };
>
> static int __init vfio_mdev_init(void)
> {
> - return mdev_register_driver(&vfio_mdev_driver, THIS_MODULE);
> + return mdev_register_driver(&vfio_mdev_driver);
> }
>
> static void __exit vfio_mdev_exit(void)
> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
> index 52f7ea19dd0f56..cb771c712da0f4 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -137,21 +137,17 @@ struct mdev_type_attribute
> mdev_type_attr_##_name = \
>
> /**
> * struct mdev_driver - Mediated device driver
> - * @name: driver name
> * @probe: called when new device created
> * @remove: called when device removed
> * @driver: device driver structure
> *
> **/
> struct mdev_driver {
> - const char *name;
> int (*probe)(struct mdev_device *dev);
> void (*remove)(struct mdev_device *dev);
> struct device_driver driver;
> };
>
> -#define to_mdev_driver(drv) container_of(drv, struct mdev_driver, driver)
> -
> static inline void *mdev_get_drvdata(struct mdev_device *mdev)
> {
> return mdev->driver_data;
> @@ -170,7 +166,7 @@ extern struct bus_type mdev_bus_type;
> int mdev_register_device(struct device *dev, const struct mdev_parent_ops
> *ops);
> void mdev_unregister_device(struct device *dev);
>
> -int mdev_register_driver(struct mdev_driver *drv, struct module *owner);
> +int mdev_register_driver(struct mdev_driver *drv);
> void mdev_unregister_driver(struct mdev_driver *drv);
>
> struct device *mdev_parent_dev(struct mdev_device *mdev);
> --
> 2.31.0
