Commit 91b9969d authored by Jason Gunthorpe's avatar Jason Gunthorpe Committed by Alex Williamson
Browse files

vfio/mdev: Simplify driver registration 



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.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Message-Id: <4-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 2a3d15f2

Documentation/driver-api/vfio-mediated-device.rst

+1 −4
Original line number Diff line number Diff line
@@ -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::

drivers/vfio/mdev/mdev_driver.c

+7 −8
Original line number Diff line number Diff line
@@ -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);

drivers/vfio/mdev/vfio_mdev.c

+6 −2
Original line number Diff line number Diff line
@@ -152,14 +152,18 @@ static void vfio_mdev_remove(struct mdev_device *mdev) 
}



static struct mdev_driver vfio_mdev_driver = {

	.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)

include/linux/mdev.h

+1 −5
Original line number Diff line number Diff line
@@ -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);