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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: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <4-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Jason Gunthorpe 2021-04-06 16:40:27 -03:00 committed by Alex Williamson
parent 2a3d15f270
commit 91b9969d9c
4 changed files with 15 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
Documentation/driver-api/vfio-mediated-device.rst
View File

@ -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::

15
drivers/vfio/mdev/mdev_driver.c
View File

@ -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);

8
drivers/vfio/mdev/vfio_mdev.c
View File

@ -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)

6
include/linux/mdev.h
View File

@ -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);