2015-12-15 0:29 GMT+01:00 Dmitry Torokhov <dmitry.torok...@gmail.com>:
> On Wed, Dec 09, 2015 at 11:02:39PM -0800, Dmitry Torokhov wrote:
>> On Sun, Nov 01, 2015 at 04:31:35PM +0100, Pavel Rojtberg wrote:
>> > From: "Pierre-Loup A. Griffais" <pgriff...@valvesoftware.com>
>> >
>> > 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.
>> >
>> > 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.
>
> Hmm, after I thought about it some more I am not sure that simply
> not submitting any more input URBs is sufficient: what will happen if
> the device sends motion event before we send our query (I.e. user is
> holding a button on the controller). I think it is safer to make sure we
> are not accessing half-created or half-gone input device when
> processing packet.
>
> Could you please take a look at the new version of this patch below?
>
> Thanks!
>
> --
> Dmitry
just tested it - everything still works. The approach also looks good to me.
>
> Input: xpad - handle "present" and "gone" correctly
>
> From: Pierre-Loup A. Griffais <pgriff...@valvesoftware.com>
>
> 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" <pgriff...@valvesoftware.com>
> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
> Signed-off-by: Pavel Rojtberg <rojtb...@gmail.com>
> Signed-off-by: Dmitry Torokhov <dmitry.torok...@gmail.com>
> ---
> drivers/input/joystick/xpad.c | 107
> ++++++++++++++++++++++++++---------------
> 1 file changed, 69 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/input/joystick/xpad.c b/drivers/input/joystick/xpad.c
> index c44cbd4..1d51d24 100644
> --- a/drivers/input/joystick/xpad.c
> +++ b/drivers/input/joystick/xpad.c
> @@ -76,6 +76,8 @@
> */
>
> #include <linux/kernel.h>
> +#include <linux/input.h>
> +#include <linux/rcupdate.h>
> #include <linux/slab.h>
> #include <linux/stat.h>
> #include <linux/module.h>
> @@ -319,10 +321,12 @@ MODULE_DEVICE_TABLE(usb, xpad_table);
>
> struct usb_xpad {
> struct input_dev *dev; /* input device interface */
> + struct input_dev __rcu *x360w_dev;
> struct usb_device *udev; /* usb device */
> struct usb_interface *intf; /* usb interface */
>
> - int pad_present;
> + bool pad_present;
> + bool input_created;
>
> struct urb *irq_in; /* urb for interrupt in report */
> unsigned char *idata; /* input data */
> @@ -343,8 +347,12 @@ 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
> *
> @@ -424,11 +432,9 @@ static void xpad_process_packet(struct usb_xpad *xpad,
> u16 cmd, unsigned char *d
> * http://www.free60.org/wiki/Gamepad
> */
>
> -static void xpad360_process_packet(struct usb_xpad *xpad,
> +static void xpad360_process_packet(struct usb_xpad *xpad, struct input_dev
> *dev,
> u16 cmd, unsigned char *data)
> {
> - struct input_dev *dev = xpad->dev;
> -
> /* digital pad */
> if (xpad->mapping & MAP_DPAD_TO_BUTTONS) {
> /* dpad as buttons (left, right, up, down) */
> @@ -495,7 +501,30 @@ static void xpad360_process_packet(struct usb_xpad *xpad,
> input_sync(dev);
> }
>
> -static void xpad_identify_controller(struct usb_xpad *xpad);
> +static void xpad_presence_work(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: %d\n", error);
> + } else {
> + rcu_assign_pointer(xpad->x360w_dev, xpad->dev);
> + }
> + } else {
> + RCU_INIT_POINTER(xpad->x360w_dev, NULL);
> + synchronize_rcu();
> + /*
> + * Now that we are sure xpad360w_process_packet is not
> + * using input device we can get rid of it.
> + */
> + xpad_deinit_input(xpad);
> + }
> +}
>
> /*
> * xpad360w_process_packet
> @@ -513,24 +542,28 @@ static void xpad_identify_controller(struct usb_xpad
> *xpad);
> */
> static void xpad360w_process_packet(struct usb_xpad *xpad, u16 cmd, unsigned
> char *data)
> {
> + struct input_dev *dev;
> + bool present;
> +
> /* 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;
> + present = (data[1] & 0x80) != 0;
> +
> + if (xpad->pad_present != present) {
> + xpad->pad_present = present;
> + schedule_work(&xpad->work);
> + }
> }
>
> /* Valid pad data */
> if (data[1] != 0x1)
> return;
>
> - xpad360_process_packet(xpad, cmd, &data[4]);
> + rcu_read_lock();
> + dev = rcu_dereference(xpad->x360w_dev);
> + if (dev)
> + xpad360_process_packet(xpad, dev, cmd, &data[4]);
> + rcu_read_unlock();
> }
>
> /*
> @@ -659,7 +692,7 @@ static void xpad_irq_in(struct urb *urb)
>
> switch (xpad->xtype) {
> case XTYPE_XBOX360:
> - xpad360_process_packet(xpad, 0, xpad->idata);
> + xpad360_process_packet(xpad, xpad->dev, 0, xpad->idata);
> break;
> case XTYPE_XBOX360W:
> xpad360w_process_packet(xpad, 0, xpad->idata);
> @@ -1001,14 +1034,7 @@ static int xpad_led_probe(struct usb_xpad *xpad)
> if (error)
> goto err_free_id;
>
> - if (xpad->xtype == XTYPE_XBOX360) {
> - /*
> - * Light up the segment corresponding to controller
> - * number on wired devices. On wireless we'll do that
> - * when they respond to "presence" packet.
> - */
> - xpad_identify_controller(xpad);
> - }
> + xpad_identify_controller(xpad);
>
> return 0;
>
> @@ -1097,8 +1123,11 @@ static void xpad_set_up_abs(struct input_dev
> *input_dev, signed short abs)
>
> static void xpad_deinit_input(struct usb_xpad *xpad)
> {
> - xpad_led_disconnect(xpad);
> - input_unregister_device(xpad->dev);
> + if (xpad->input_created) {
> + xpad->input_created = false;
> + xpad_led_disconnect(xpad);
> + input_unregister_device(xpad->dev);
> + }
> }
>
> static int xpad_init_input(struct usb_xpad *xpad)
> @@ -1181,6 +1210,7 @@ static int xpad_init_input(struct usb_xpad *xpad)
> if (error)
> goto err_disconnect_led;
>
> + xpad->input_created = true;
> return 0;
>
> err_disconnect_led:
> @@ -1241,6 +1271,7 @@ static int xpad_probe(struct usb_interface *intf, const
> struct usb_device_id *id
> xpad->mapping = xpad_device[i].mapping;
> xpad->xtype = xpad_device[i].xtype;
> xpad->name = xpad_device[i].name;
> + INIT_WORK(&xpad->work, xpad_presence_work);
>
> if (xpad->xtype == XTYPE_UNKNOWN) {
> if (intf->cur_altsetting->desc.bInterfaceClass ==
> USB_CLASS_VENDOR_SPEC) {
> @@ -1277,10 +1308,6 @@ static int xpad_probe(struct usb_interface *intf,
> const struct usb_device_id *id
>
> usb_set_intfdata(intf, xpad);
>
> - error = xpad_init_input(xpad);
> - if (error)
> - goto err_deinit_output;
> -
> if (xpad->xtype == XTYPE_XBOX360W) {
> /*
> * Submit the int URB immediately rather than waiting for open
> @@ -1292,7 +1319,7 @@ static int xpad_probe(struct usb_interface *intf, const
> struct usb_device_id *id
> xpad->irq_in->dev = xpad->udev;
> error = usb_submit_urb(xpad->irq_in, GFP_KERNEL);
> if (error)
> - goto err_deinit_input;
> + goto err_deinit_output;
>
> /*
> * Send presence packet.
> @@ -1304,13 +1331,15 @@ static int xpad_probe(struct usb_interface *intf,
> const struct usb_device_id *id
> error = xpad_inquiry_pad_presence(xpad);
> if (error)
> goto err_kill_in_urb;
> + } else {
> + error = xpad_init_input(xpad);
> + if (error)
> + goto err_deinit_output;
> }
> return 0;
>
> err_kill_in_urb:
> usb_kill_urb(xpad->irq_in);
> -err_deinit_input:
> - xpad_deinit_input(xpad);
> err_deinit_output:
> xpad_deinit_output(xpad);
> err_free_in_urb:
> @@ -1327,17 +1356,19 @@ static void xpad_disconnect(struct usb_interface
> *intf)
> {
> struct usb_xpad *xpad = usb_get_intfdata (intf);
>
> - xpad_deinit_input(xpad);
> - xpad_deinit_output(xpad);
> -
> - if (xpad->xtype == XTYPE_XBOX360W) {
> + if (xpad->xtype == XTYPE_XBOX360W)
> usb_kill_urb(xpad->irq_in);
> - }
> +
> + cancel_work_sync(&xpad->work);
> +
> + xpad_deinit_input(xpad);
>
> usb_free_urb(xpad->irq_in);
> usb_free_coherent(xpad->udev, XPAD_PKT_LEN,
> xpad->idata, xpad->idata_dma);
>
> + xpad_deinit_output(xpad);
> +
> kfree(xpad);
>
> usb_set_intfdata(intf, NULL);
--
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