Re: [PATCH V2 3/5] vDPA: introduce vDPA bus

[Jason Wang]

On 2020/2/11 äå9:47, Jason Gunthorpe wrote:
> On Mon, Feb 10, 2020 at 11:56:06AM +0800, Jason Wang wrote:
> > +/**
> > + * vdpa_register_device - register a vDPA device
> > + * Callers must have a succeed call of vdpa_init_device() before.
> > + * @vdev: the vdpa device to be registered to vDPA bus
> > + *
> > + * Returns an error when fail to add to vDPA bus
> > + */
> > +int vdpa_register_device(struct vdpa_device *vdev)
> > +{
> > +	int err = device_add(&vdev->dev);
> > +
> > +	if (err) {
> > +		put_device(&vdev->dev);
> > +		ida_simple_remove(&vdpa_index_ida, vdev->index);
> > +	}
> This is a very dangerous construction, I've seen it lead to driver
> bugs. Better to require the driver to always do the put_device on
> error unwind


Ok.


> The ida_simple_remove should probably be part of the class release
> function to make everything work right


It looks to me bus instead of class is the correct abstraction here 
since the devices share a set of programming interface but not the 
semantics.

Or do you actually mean type here?


> > +/**
> > + * vdpa_unregister_driver - unregister a vDPA device driver
> > + * @drv: the vdpa device driver to be unregistered
> > + */
> > +void vdpa_unregister_driver(struct vdpa_driver *drv)
> > +{
> > +	driver_unregister(&drv->driver);
> > +}
> > +EXPORT_SYMBOL_GPL(vdpa_unregister_driver);
> > +
> > +static int vdpa_init(void)
> > +{
> > +	if (bus_register(&vdpa_bus) != 0)
> > +		panic("virtio bus registration failed");
> > +	return 0;
> > +}
> Linus will tell you not to kill the kernel - return the error code and
> propagate it up to the module init function.


Yes, will fix.


> > +/**
> > + * vDPA device - representation of a vDPA device
> > + * @dev: underlying device
> > + * @dma_dev: the actual device that is performing DMA
> > + * @config: the configuration ops for this device.
> > + * @index: device index
> > + */
> > +struct vdpa_device {
> > +	struct device dev;
> > +	struct device *dma_dev;
> > +	const struct vdpa_config_ops *config;
> > +	int index;
> unsigned values shuld be unsigned int
>
> Jason


Will fix.

Thanks

>