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Subject: [media] em28xx: use atomic bit operations for devices-in-use mask Author: Chris Rankin <[email protected]> Date: Sat Aug 20 08:21:03 2011 -0300 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: Chris Rankin <[email protected]> Signed-off-by: Mauro Carvalho Chehab <[email protected]> drivers/media/video/em28xx/em28xx-cards.c | 33 ++++++++++++++--------------- 1 files changed, 16 insertions(+), 17 deletions(-) --- http://git.linuxtv.org/media_tree.git?a=commitdiff;h=38b61eb2dac06fdc42815b004e9824d8196cfcfb diff --git a/drivers/media/video/em28xx/em28xx-cards.c b/drivers/media/video/em28xx/em28xx-cards.c index d947026..677db14 100644 --- a/drivers/media/video/em28xx/em28xx-cards.c +++ b/drivers/media/video/em28xx/em28xx-cards.c @@ -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 */ - nr = find_first_zero_bit(&em28xx_devused, EM28XX_MAXBOARDS); - em28xx_devused |= 1<<nr; + do { + nr = find_first_zero_bit(&em28xx_devused, EM28XX_MAXBOARDS); + 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; } _______________________________________________ linuxtv-commits mailing list [email protected] http://www.linuxtv.org/cgi-bin/mailman/listinfo/linuxtv-commits
