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" <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.
> >
> > 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
Input: xpad - handle "present" and "gone" correctly
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>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
---
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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