Re: [PATCH v4 5/5] usb: gadget: udc-core: independent registration of gadgets and gadget drivers

[Alan Stern]

On Mon, 16 Mar 2015, Ruslan Bilovol wrote:

> >> +     if (ret) {
> >> +             struct usb_gadget_driver *tmp;
> >> +
> >> +             list_for_each_entry(tmp, &gadget_driver_pending_list, pending)
> >> +                     if (tmp == driver) {
> >> +                             list_del(&driver->pending);
> >> +                             ret = 0;
> >> +                             break;
> >> +                     }
> >> +     }
> >
> > You could avoid this loop and simply do list_del(&driver->pending), if
> > you made sure driver->pending was initialized.
> 
> It would be good to avoid this loop but the question is how to make sure
> that driver->pending is not only initialized (prev and next are not NULL),
> but also contains valid data?

It's easy.  In usb_gadget_probe_driver() do
INIT_LIST_HEAD(&driver->pending), and in usb_gadget_remove_driver()  
replace your list_del() with list_del_init().

Alan Stern

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