On Mon, Nov 23, 2015 at 10:32:53AM -0500, Alan Stern wrote:
> On Mon, 23 Nov 2015, Marek Szyprowski wrote:
>
> > From: Ruslan Bilovol <ruslan.bilovol@xxxxxxxxx>
> >
> > Change behavior during registration of gadgets and
> > gadget drivers in udc-core. Instead of previous
> > approach when for successful probe of usb gadget driver
> > at least one usb gadget should be already registered
> > use another one where gadget drivers and gadgets
> > can be registered in udc-core independently.
> >
> > Independent registration of gadgets and gadget drivers
> > is useful for built-in into kernel gadget and gadget
> > driver case - because it's possible that gadget is
> > really probed only on late_init stage (due to deferred
> > probe) whereas gadget driver's probe is silently failed
> > on module_init stage due to no any UDC added.
> >
> > Also it is useful for modules case - now there is no
> > difference what module to insert first: gadget module
> > or gadget driver one.
> >
> > Tested-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Ruslan Bilovol <ruslan.bilovol@xxxxxxxxx>
> > [simplified code as requested by Alan Stern and Felipe Balbi,
> > fixed checkpatch issues]
> > Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> > Tested-by: Peter Chen <peter.chen@xxxxxxxxxxxxx>
>
> I missed this the last time through...
>
> > @@ -403,6 +408,18 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
> > usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);
> > udc->vbus = true;
> >
> > + /* pick up one of pending gadget drivers */
> > + list_for_each_entry(driver, &gadget_driver_pending_list, pending) {
> > + if (!driver->udc_name || strcmp(driver->udc_name,
> > + dev_name(&udc->dev)) == 0) {
> > + ret = udc_bind_to_driver(udc, driver);
> > + if (ret)
> > + goto err4;
> > + list_del(&driver->pending);
>
> This has to be list_del_init(). And somewhere in
> usb_gadget_probe_driver() you need to do
> INIT_LIST_HEAD(&driver->pending).
>
> > @@ -577,6 +596,10 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
> > break;
> > }
> >
> > + if (ret) {
> > + list_del(&driver->pending);
>
> Otherwise this will cause a crash or corrupt some random area of
> memory.
>
Alan, would you please explain more what use case will cause memory
corruption for above code?
--
Best Regards,
Peter Chen
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