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Commit c196adf8 authored by Willem Penninckx's avatar Willem Penninckx Committed by Jiri Kosina
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HID: usbkbd: synchronize LED URB submission 



usb_kbd_event() and usb_kbd_led() can be called concurrently, but they are not
synchronized. They both readwrite kbd->leds, and usb_kbd_event() originally just
checked the URB status field, while urb.h states that "It [status field] should
not be examined before the URB is returned to the completion handler."

To fix this unsynchronized behavior, this patch introduces a boolean
representing whether the URB is submitted, and a spinlock.

Signed-off-by: default avatarWillem Penninckx <willem.penninckx@cs.kuleuven.be>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent f2c4826c

drivers/hid/usbhid/usbkbd.c

+58 −5
Original line number Diff line number Diff line
@@ -64,6 +64,32 @@ static const unsigned char usb_kbd_keycode[256] = { 
	150,158,159,128,136,177,178,176,142,152,173,140

};





/**

 * struct usb_kbd - state of each attached keyboard

 * @dev:	input device associated with this keyboard

 * @usbdev:	usb device associated with this keyboard

 * @old:	data received in the past from the @irq URB representing which

 *		keys were pressed. By comparing with the current list of keys

 *		that are pressed, we are able to see key releases.

 * @irq:	URB for receiving a list of keys that are pressed when a

 *		new key is pressed or a key that was pressed is released.

 * @led:	URB for sending LEDs (e.g. numlock, ...)

 * @newleds:	data that will be sent with the @led URB representing which LEDs

 		should be on

 * @name:	Name of the keyboard. @dev's name field points to this buffer

 * @phys:	Physical path of the keyboard. @dev's phys field points to this

 *		buffer

 * @new:	Buffer for the @irq URB

 * @cr:		Control request for @led URB

 * @leds:	Buffer for the @led URB

 * @new_dma:	DMA address for @irq URB

 * @leds_dma:	DMA address for @led URB

 * @leds_lock:	spinlock that protects @leds, @newleds, and @led_urb_submitted

 * @led_urb_submitted: indicates whether @led is in progress, i.e. it has been

 *		submitted and its completion handler has not returned yet

 *		without	resubmitting @led

 */

struct usb_kbd {

	struct input_dev *dev;

	struct usb_device *usbdev;
@@ -78,6 +104,10 @@ struct usb_kbd { 
	unsigned char *leds;

	dma_addr_t new_dma;

	dma_addr_t leds_dma;

	

	spinlock_t leds_lock;

	bool led_urb_submitted;



};



static void usb_kbd_irq(struct urb *urb)
@@ -136,44 +166,66 @@ static void usb_kbd_irq(struct urb *urb) 
static int usb_kbd_event(struct input_dev *dev, unsigned int type,

			 unsigned int code, int value)

{

	unsigned long flags;

	struct usb_kbd *kbd = input_get_drvdata(dev);



	if (type != EV_LED)

		return -1;



	spin_lock_irqsave(&kbd->leds_lock, flags);

	kbd->newleds = (!!test_bit(LED_KANA,    dev->led) << 3) | (!!test_bit(LED_COMPOSE, dev->led) << 3) |

		       (!!test_bit(LED_SCROLLL, dev->led) << 2) | (!!test_bit(LED_CAPSL,   dev->led) << 1) |

		       (!!test_bit(LED_NUML,    dev->led));



	if (kbd->led->status == -EINPROGRESS)

	if (kbd->led_urb_submitted){

		spin_unlock_irqrestore(&kbd->leds_lock, flags);

		return 0;

	}



	if (*(kbd->leds) == kbd->newleds)

	if (*(kbd->leds) == kbd->newleds){

		spin_unlock_irqrestore(&kbd->leds_lock, flags);

		return 0;

	}



	*(kbd->leds) = kbd->newleds;

	

	kbd->led->dev = kbd->usbdev;

	if (usb_submit_urb(kbd->led, GFP_ATOMIC))

		pr_err("usb_submit_urb(leds) failed\n");

	else

		kbd->led_urb_submitted = true;

	

	spin_unlock_irqrestore(&kbd->leds_lock, flags);

	

	return 0;

}



static void usb_kbd_led(struct urb *urb)

{

	unsigned long flags;

	struct usb_kbd *kbd = urb->context;



	if (urb->status)

		hid_warn(urb->dev, "led urb status %d received\n",

			 urb->status);



	if (*(kbd->leds) == kbd->newleds)

	spin_lock_irqsave(&kbd->leds_lock, flags);



	if (*(kbd->leds) == kbd->newleds){

		kbd->led_urb_submitted = false;

		spin_unlock_irqrestore(&kbd->leds_lock, flags);

		return;

	}



	*(kbd->leds) = kbd->newleds;

	

	kbd->led->dev = kbd->usbdev;

	if (usb_submit_urb(kbd->led, GFP_ATOMIC))

	if (usb_submit_urb(kbd->led, GFP_ATOMIC)){

		hid_err(urb->dev, "usb_submit_urb(leds) failed\n");

		kbd->led_urb_submitted = false;

	}

	spin_unlock_irqrestore(&kbd->leds_lock, flags);

	

}



static int usb_kbd_open(struct input_dev *dev)
@@ -252,6 +304,7 @@ static int usb_kbd_probe(struct usb_interface *iface, 


	kbd->usbdev = dev;

	kbd->dev = input_dev;

	spin_lock_init(&kbd->leds_lock);



	if (dev->manufacturer)

		strlcpy(kbd->name, dev->manufacturer, sizeof(kbd->name));