Re: [PATCH 2/2] uacce: add uacce module

[zhangfei]

Hi, Greg

On 2019/8/19 äå6:24, Greg Kroah-Hartman wrote:
> > > > +static int uacce_create_chrdev(struct uacce *uacce)
> > > > +{
> > > > +	int ret;
> > > > +
> > > > +	ret = idr_alloc(&uacce_idr, uacce, 0, 0, GFP_KERNEL);
> > > > +	if (ret < 0)
> > > > +		return ret;
> > > > +
> > > Shouldn't this function create the memory needed for this structure?
> > > You are relying ont he caller to do it for you, why?
> > I think you mean uacce structure here.
> > Yes, currently we count on caller to prepare uacce structure and call
> > uacce_register(uacce).
> > We still think this method is simpler, prepare uacce, register uacce.
> > And there are other system using the same method, like crypto
> > (crypto_register_acomp), nand, etc.
> crypto is not a subsystem to ever try to emulate :)
>
> You are creating a structure with a lifetime that you control, don't
> have someone else create your memory, that's almost never what you want
> to do.  Most all driver subsystems create their own memory chunks for
> what they need to do, it's a much better pattern.
>
> Especially when you get into pointer lifetime issues...
OK, understand now, thanks for your patience.
will use this instead.
struct uacce_interface {
ÂÂÂÂÂÂÂ char name[32];
ÂÂÂÂÂÂÂ unsigned int flags;
ÂÂÂÂÂÂÂ struct uacce_ops *ops;
};
struct uacce *uacce_register(struct device *dev, struct uacce_interface 
*interface);
> > > > +}
> > > > +
> > > > +static int uacce_dev_match(struct device *dev, void *data)
> > > > +{
> > > > +	if (dev->parent == data)
> > > > +		return -EBUSY;
> > > There should be in-kernel functions for this now, no need for you to
> > > roll your own.
> > Sorry, do not find this function.
> > Only find class_find_device, which still require match.
> It is in linux-next, look there...
Suppose you mean the funcs: device_match_name, 
device_match_of_node,device_match_devt etc.
Here we need dev->parent, there still no such func.

Thanks