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Commit 38b61eb2 authored by Chris Rankin's avatar Chris Rankin Committed by Mauro Carvalho Chehab
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[media] em28xx: use atomic bit operations for devices-in-use mask 



Use atomic bit operations for the em28xx_devused mask, to prevent an
unlikely race condition should two adapters be plugged in
simultaneously. The operations also clearer than explicit bit
manipulation anyway.

Signed-off-by: default avatarChris Rankin <rankincj@yahoo.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent f38f3339

drivers/media/video/em28xx/em28xx-cards.c

+16 −17
Original line number Diff line number Diff line
@@ -60,7 +60,7 @@ static unsigned int card[] = {[0 ... (EM28XX_MAXBOARDS - 1)] = UNSET }; 
module_param_array(card,  int, NULL, 0444);

MODULE_PARM_DESC(card,     "card type");



/* Bitmask marking allocated devices from 0 to EM28XX_MAXBOARDS */

/* Bitmask marking allocated devices from 0 to EM28XX_MAXBOARDS - 1 */

static unsigned long em28xx_devused;



struct em28xx_hash_table {
@@ -2793,7 +2793,7 @@ void em28xx_release_resources(struct em28xx *dev) 
	usb_put_dev(dev->udev);



	/* Mark device as unused */

	em28xx_devused &= ~(1 << dev->devno);

	clear_bit(dev->devno, &em28xx_devused);

};



/*
@@ -3015,8 +3015,16 @@ static int em28xx_usb_probe(struct usb_interface *interface, 
	udev = usb_get_dev(interface_to_usbdev(interface));



	/* Check to see next free device and mark as used */

	do {

		nr = find_first_zero_bit(&em28xx_devused, EM28XX_MAXBOARDS);

	em28xx_devused |= 1<<nr;

		if (nr >= EM28XX_MAXBOARDS) {

			/* No free device slots */

			printk(DRIVER_NAME ": Supports only %i em28xx boards.\n",

					EM28XX_MAXBOARDS);

			retval = -ENOMEM;

			goto err_no_slot;

		}

	} while (test_and_set_bit(nr, &em28xx_devused));



	/* Don't register audio interfaces */

	if (interface->altsetting[0].desc.bInterfaceClass == USB_CLASS_AUDIO) {
@@ -3027,7 +3035,6 @@ static int em28xx_usb_probe(struct usb_interface *interface, 
			ifnum,

			interface->altsetting[0].desc.bInterfaceClass);



		em28xx_devused &= ~(1<<nr);

		retval = -ENODEV;

		goto err;

	}
@@ -3132,24 +3139,14 @@ static int em28xx_usb_probe(struct usb_interface *interface, 
		printk(DRIVER_NAME ": Device initialization failed.\n");

		printk(DRIVER_NAME ": Device must be connected to a high-speed"

		       " USB 2.0 port.\n");

		em28xx_devused &= ~(1<<nr);

		retval = -ENODEV;

		goto err;

	}



	if (nr >= EM28XX_MAXBOARDS) {

		printk(DRIVER_NAME ": Supports only %i em28xx boards.\n",

				EM28XX_MAXBOARDS);

		em28xx_devused &= ~(1<<nr);

		retval = -ENOMEM;

		goto err;

	}



	/* allocate memory for our device state and initialize it */

	dev = kzalloc(sizeof(*dev), GFP_KERNEL);

	if (dev == NULL) {

		em28xx_err(DRIVER_NAME ": out of memory!\n");

		em28xx_devused &= ~(1<<nr);

		retval = -ENOMEM;

		goto err;

	}
@@ -3177,7 +3174,6 @@ static int em28xx_usb_probe(struct usb_interface *interface, 


	if (dev->alt_max_pkt_size == NULL) {

		em28xx_errdev("out of memory!\n");

		em28xx_devused &= ~(1<<nr);

		kfree(dev);

		retval = -ENOMEM;

		goto err;
@@ -3204,7 +3200,6 @@ static int em28xx_usb_probe(struct usb_interface *interface, 
	mutex_lock(&dev->lock);

	retval = em28xx_init_dev(&dev, udev, interface, nr);

	if (retval) {

		em28xx_devused &= ~(1<<dev->devno);

		mutex_unlock(&dev->lock);

		kfree(dev);

		goto err;
@@ -3220,6 +3215,10 @@ static int em28xx_usb_probe(struct usb_interface *interface, 
	return 0;



err:

	clear_bit(nr, &em28xx_devused);



err_no_slot:

	usb_put_dev(udev);

	return retval;

}