On Mon, Feb 03, 2025 at 03:25:17PM +0100, Greg Kroah-Hartman wrote:
> Many drivers abuse the platform driver/bus system as it provides a
> simple way to create and bind a device to a driver-specific set of
> probe/release functions. Instead of doing that, and wasting all of the
> memory associated with a platform device, here is a "faux" bus that
> can be used instead.
...
> +#include <linux/device/faux.h>
I would rather think that this goes after generic inclusions...
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
...somewhere here.
But looking into organisation of device.h and device/*.h,
I would rather think of the linux/faux_device.h.
> +#include "base.h"
I don't remember by heart what it does include, I would go with IWYU principle
and list above all what we use.
container_of.h
device.h
export.h
printk.h
types.h
...
> +static int faux_match(struct device *dev, const struct device_driver *drv)
> +{
> + struct faux_object *faux_obj = to_faux_object(dev);
> +
> + /* Match is simple, strcmp()! */
> + return (strcmp(faux_obj->name, drv->name) == 0);
Outer parentheses are not needed.
> +}
...
> +/**
> + * __faux_device_create - create and register a faux device and driver
> + * @name: name of the device and driver we are adding
> + * @faux_ops: struct faux_driver_ops that the new device will call back into, can be NULL
> + * @owner: module owner of the device/driver
> + *
> + * Create a new faux device and driver, both with the same name, and register
> + * them in the driver core properly. The probe() callback of @faux_ops will be
> + * called with the new device that is created for the caller to do something
> + * with.
The kernel-doc will complain on missing Return: section.
> + */
> +struct faux_device *__faux_device_create(const char *name,
> + struct faux_driver_ops *faux_ops,
> + struct module *owner)
> +{
> + struct device_driver *drv;
> + struct device *dev;
> + struct faux_object *faux_obj;
> + struct faux_device *faux_dev;
> + int ret;
> + faux_obj = kzalloc(sizeof(*faux_obj) + strlen(name) + 1, GFP_KERNEL);
Potential overflow. To avoid one may use struct_size() from overflow.h.
> + if (!faux_obj)
> + return NULL;
> +
> + /* Save off the name of the object into local memory */
> + strcpy(faux_obj->name, name);
> +
> + /* Initialize the driver portion and register it with the driver core */
> + faux_obj->faux_ops = faux_ops;
> + drv = &faux_obj->driver;
> +
> + drv->owner = owner;
> + drv->name = faux_obj->name;
> + drv->bus = &faux_bus_type;
> + drv->probe_type = PROBE_PREFER_ASYNCHRONOUS;
> +
> + ret = driver_register(drv);
> + if (ret) {
> + pr_err("%s: driver_register for %s faux driver failed with %d\n",
> + __func__, name, ret);
> + kfree(faux_obj);
> + return NULL;
> + }
> +
> + /* Initialize the device portion and register it with the driver core */
> + faux_dev = &faux_obj->faux_dev;
> + dev = &faux_dev->dev;
> +
> + device_initialize(dev);
> + dev->release = faux_device_release;
> + dev->parent = &faux_bus_root;
> + dev->bus = &faux_bus_type;
> + dev_set_name(dev, "%s", name);
> +
> + ret = device_add(dev);
> + if (ret) {
> + pr_err("%s: device_add for %s faux device failed with %d\n",
> + __func__, name, ret);
> + put_device(dev);
> + return NULL;
> + }
> +
> + return faux_dev;
> +}
> +EXPORT_SYMBOL_GPL(__faux_device_create);
...
> +#ifndef _FAUX_DEVICE_H_
> +#define _FAUX_DEVICE_H_
> +#include <linux/module.h>
+ container_of.h
> +#include <linux/device.h>
> +struct faux_device {
> + struct device dev;
> +};
> +#define to_faux_device(x) container_of_const((x), struct faux_device, dev)
> +
> +struct faux_driver_ops {
> + int (*probe)(struct faux_device *faux_dev);
> + void (*remove)(struct faux_device *faux_dev);
> +};
> +
> +#define faux_device_create(name, faux_ops) __faux_device_create(name, faux_ops, THIS_MODULE)
> +struct faux_device *__faux_device_create(const char *name,
> + struct faux_driver_ops *faux_ops,
> + struct module *module);
> +void faux_device_destroy(struct faux_device *faux_dev);
> +
> +#endif /* _FAUX_DEVICE_H_ */
--
With Best Regards,
Andy Shevchenko
