[1/5] Input: xpad: handle "present" and "gone" correctly

Commit Message

Pavel Rojtberg Nov. 1, 2015, 3:31 p.m. UTC

From: "Pierre-Loup A. Griffais" <[e-mail]>

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" <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Pavel Rojtberg <[e-mail]>
---
 drivers/input/joystick/xpad.c | 66 +++++++++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 41 insertions(+), 25 deletions(-)

Comments

Dmitry Torokhov Dec. 10, 2015, 7:02 a.m. UTC | #1

On Sun, Nov 01, 2015 at 04:31:35PM +0100, Pavel Rojtberg wrote:
> From: "Pierre-Loup A. Griffais" <[e-mail]>
> 
> 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" <[e-mail]>
> Signed-off-by: Greg Kroah-Hartman <[e-mail]>
> Signed-off-by: Pavel Rojtberg <[e-mail]>
> ---
>  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.

Patch

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);
+		}
 	}
 
 	/* Valid pad data */
@@ -1001,14 +1020,7 @@  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;
 
@@ -1241,6 +1253,7 @@  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, presence_work_function);
 
 	if (xpad->xtype == XTYPE_UNKNOWN) {
 		if (intf->cur_altsetting->desc.bInterfaceClass == USB_CLASS_VENDOR_SPEC) {
@@ -1277,10 +1290,6 @@  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 +1301,7 @@  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 +1313,16 @@  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 {
+		xpad->pad_present = 1;
+		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:
@@ -1327,13 +1339,17 @@  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) {
 		usb_kill_urb(xpad->irq_in);
 	}
 
+	cancel_work_sync(&xpad->work);
+
+	if (xpad->pad_present)
+		xpad_deinit_input(xpad);
+
 	usb_free_urb(xpad->irq_in);
 	usb_free_coherent(xpad->udev, XPAD_PKT_LEN,
 			xpad->idata, xpad->idata_dma);