Re: [PATCH v2 27/35] media: em28xx: cx231xx: fix opencoded find_and_set_bit()

Hans Verkuil
2023-12-04T08:40:04Z

On 03/12/2023 20:32, Yury Norov wrote:
> Functions in the media/usb drivers opencode find_and_set_bit() by
> polling on a found bit in a while-loop.
>
> Signed-off-by: Yury Norov <yury.norov@gmail.com>

Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Feel free to take this yourself through the bitmap tree.

It's a nice improvement.

Regards,

Hans

> ---
> drivers/media/usb/cx231xx/cx231xx-cards.c | 16 ++++------
> drivers/media/usb/em28xx/em28xx-cards.c | 37 +++++++++--------------
> 2 files changed, 21 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/media/usb/cx231xx/cx231xx-cards.c b/drivers/media/usb/cx231xx/cx231xx-cards.c
> index 92efe6c1f47b..b314603932d7 100644
> --- a/drivers/media/usb/cx231xx/cx231xx-cards.c
> +++ b/drivers/media/usb/cx231xx/cx231xx-cards.c
> @@ -1708,16 +1708,12 @@ static int cx231xx_usb_probe(struct usb_interface *interface,
> return -ENODEV;
>
> /* Check to see next free device and mark as used */
> - do {
> - nr = find_first_zero_bit(&cx231xx_devused, CX231XX_MAXBOARDS);
> - if (nr >= CX231XX_MAXBOARDS) {
> - /* No free device slots */
> - dev_err(d,
> - "Supports only %i devices.\n",
> - CX231XX_MAXBOARDS);
> - return -ENOMEM;
> - }
> - } while (test_and_set_bit(nr, &cx231xx_devused));
> + nr = find_and_set_bit(&cx231xx_devused, CX231XX_MAXBOARDS);
> + if (nr >= CX231XX_MAXBOARDS) {
> + /* No free device slots */
> + dev_err(d, "Supports only %i devices.\n", CX231XX_MAXBOARDS);
> + return -ENOMEM;
> + }
>
> udev = usb_get_dev(interface_to_usbdev(interface));
>
> diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c
> index 4d037c92af7c..af4809fe74a8 100644
> --- a/drivers/media/usb/em28xx/em28xx-cards.c
> +++ b/drivers/media/usb/em28xx/em28xx-cards.c
> @@ -3684,17 +3684,14 @@ static int em28xx_duplicate_dev(struct em28xx *dev)
> return -ENOMEM;
> }
> /* Check to see next free device and mark as used */
> - do {
> - nr = find_first_zero_bit(em28xx_devused, EM28XX_MAXBOARDS);
> - if (nr >= EM28XX_MAXBOARDS) {
> - /* No free device slots */
> - dev_warn(&dev->intf->dev, ": Supports only %i em28xx boards.\n",
> - EM28XX_MAXBOARDS);
> - kfree(sec_dev);
> - dev->dev_next = NULL;
> - return -ENOMEM;
> - }
> - } while (test_and_set_bit(nr, em28xx_devused));
> + nr = find_and_set_bit(em28xx_devused, EM28XX_MAXBOARDS);
> + if (nr >= EM28XX_MAXBOARDS) {
> + /* No free device slots */
> + dev_warn(&dev->intf->dev, ": Supports only %i em28xx boards.\n", EM28XX_MAXBOARDS);
> + kfree(sec_dev);
> + dev->dev_next = NULL;
> + return -ENOMEM;
> + }
> sec_dev->devno = nr;
> snprintf(sec_dev->name, 28, "em28xx #%d", nr);
> sec_dev->dev_next = NULL;
> @@ -3827,17 +3824,13 @@ static int em28xx_usb_probe(struct usb_interface *intf,
> udev = usb_get_dev(interface_to_usbdev(intf));
>
> /* Check to see next free device and mark as used */
> - do {
> - nr = find_first_zero_bit(em28xx_devused, EM28XX_MAXBOARDS);
> - if (nr >= EM28XX_MAXBOARDS) {
> - /* No free device slots */
> - dev_err(&intf->dev,
> - "Driver supports up to %i em28xx boards.\n",
> - EM28XX_MAXBOARDS);
> - retval = -ENOMEM;
> - goto err_no_slot;
> - }
> - } while (test_and_set_bit(nr, em28xx_devused));
> + nr = find_and_set_bit(em28xx_devused, EM28XX_MAXBOARDS);
> + if (nr >= EM28XX_MAXBOARDS) {
> + /* No free device slots */
> + dev_err(&intf->dev, "Driver supports up to %i em28xx boards.\n", EM28XX_MAXBOARDS);
> + retval = -ENOMEM;
> + goto err_no_slot;
> + }
>
> /* Don't register audio interfaces */
> if (intf->altsetting[0].desc.bInterfaceClass == USB_CLASS_AUDIO) {