On Sun, Nov 01, 2015 at 04:31:35PM +0100, Pavel Rojtberg wrote:
> From: "Pierre-Loup A. Griffais" <pgriffais@xxxxxxxxxxxxxxxxx>
>
> Handle the "a new device is present" message properly by dynamically
> creating the input device at this point in time. This means we now do
> not "preallocate" all 4 devices when a single
> wireless base station is seen. This requires a workqueue as we are in
> interrupt context when we learn about this.
>
> Also properly disconnect any devices that we are told are removed.
>
> Signed-off-by: "Pierre-Loup A. Griffais" <pgriffais@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Pavel Rojtberg <rojtberg@xxxxxxxxx>
> ---
> drivers/input/joystick/xpad.c | 66 +++++++++++++++++++++++++++++++++++++++++-------------------------
> 1 file changed, 41 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/input/joystick/xpad.c b/drivers/input/joystick/xpad.c
> index fd4100d..23e5613 100644
> --- a/drivers/input/joystick/xpad.c
> +++ b/drivers/input/joystick/xpad.c
> @@ -343,8 +343,12 @@ struct usb_xpad {
> int xtype; /* type of xbox device */
> int pad_nr; /* the order x360 pads were attached */
> const char *name; /* name of the device */
> + struct work_struct work; /* init/remove device from callback */
> };
>
> +static int xpad_init_input(struct usb_xpad *xpad);
> +static void xpad_deinit_input(struct usb_xpad *xpad);
> +
> /*
> * xpad_process_packet
> *
> @@ -497,6 +501,22 @@ static void xpad360_process_packet(struct usb_xpad *xpad,
>
> static void xpad_identify_controller(struct usb_xpad *xpad);
>
> +static void presence_work_function(struct work_struct *work)
> +{
> + struct usb_xpad *xpad = container_of(work, struct usb_xpad, work);
> + int error;
> +
> + if (xpad->pad_present) {
> + error = xpad_init_input(xpad);
> + if (error) {
> + /* complain only, not much else we can do here */
> + dev_err(&xpad->dev->dev, "unable to init device\n");
> + }
> + } else {
> + xpad_deinit_input(xpad);
> + }
> +}
> +
> /*
> * xpad360w_process_packet
> *
> @@ -513,17 +533,16 @@ static void xpad_identify_controller(struct usb_xpad *xpad);
> */
> static void xpad360w_process_packet(struct usb_xpad *xpad, u16 cmd, unsigned char *data)
> {
> + int presence;
> +
> /* Presence change */
> if (data[0] & 0x08) {
> - if (data[1] & 0x80) {
> - xpad->pad_present = 1;
> - /*
> - * Light up the segment corresponding to
> - * controller number.
> - */
> - xpad_identify_controller(xpad);
> - } else
> - xpad->pad_present = 0;
> + presence = (data[1] & 0x80) != 0;
> +
> + if (xpad->pad_present != presence) {
> + xpad->pad_present = presence;
> + schedule_work(&xpad->work);
> + }
I think this is racy: we'll crash if we get motion packets before we
finish creating input device. I think we should be returning whether we
want to have xpad->irq_in URB be re-submitted and in case we scheduke
work we'd return "false" and have work resubmit IRQ when it is done
creating or destroying input device.
--
Dmitry
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