On Fri, Jul 17, 2015 at 09:52:26AM -0400, Alan Stern wrote: > On Fri, 17 Jul 2015, Peter Chen wrote: > > > There are several benefits for doing like this: > > > > - hc_driver can be customized for each hcd > > - Other hcd hc_driver's initialization will not affect current one. > > We run out NULL pointer dereference problem when one hcd is started > > by module_init, and the other is started by otg thread at SMP platform. > > The reason for this problem is ehci_init_driver will do memory copy > > for current uniform hc_driver, and this memory copy will do memset (as 0) > > first, so when the first hcd is running usb_add_hcd, and the second > > hcd may clear the uniform hc_driver's space (at ehci_init_driver), > > then the first hcd will meet NULL pointer at the same time. > > It seems to me the real problem is that ehci_init_driver gets called at > the wrong time. It's not supposed to be called whenever a new host > controller is initialized; rather, it should be called just once when > the driver is initialized. This means the call should be in a > module_init routine in host.c, not in ci_hdrc_host_init. > But we have no platform driver dedicated for host controller, is it a must? The core driver requests io_address, interrupt, dma_mask, etc for both device and host driver, and device and host part (we does not take it as a driver) should not request resources again. Would you accept it as another use case for ehci driver? > If you need to customize the hc_driver structure for each host > controller then yes, a separate copy is needed. But otherwise there's > no need to make a copy. > > Alan Stern > -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
