On Wed, 10 Apr 2024, Thomas Zimmermann <tzimmermann@xxxxxxx> wrote:
> Protect the code in udl_get_edid_block() with drm_dev_enter() and
> drm_dev_exit(), so that all callers automatically invoke it. The
> function uses hardware resources, which can be hot-unplugged at
> any time. The other code in udl_connector_detect() does not use the
> resources of the hardware device and therefore does not require
> protection.
>
> This change will allow to use udl_get_edid_block() in various
> contexts easily.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> ---
> drivers/gpu/drm/udl/udl_modeset.c | 20 +++++++++++---------
> 1 file changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/udl/udl_modeset.c b/drivers/gpu/drm/udl/udl_modeset.c
> index 751da3a294c44..3df9fc38388b4 100644
> --- a/drivers/gpu/drm/udl/udl_modeset.c
> +++ b/drivers/gpu/drm/udl/udl_modeset.c
> @@ -434,13 +434,18 @@ static int udl_get_edid_block(void *data, u8 *buf, unsigned int block, size_t le
> struct drm_device *dev = &udl->drm;
> struct usb_device *udev = udl_to_usb_device(udl);
> u8 *read_buff;
> - int ret;
> + int idx, ret;
> size_t i;
>
> read_buff = kmalloc(2, GFP_KERNEL);
> if (!read_buff)
> return -ENOMEM;
>
> + if (!drm_dev_enter(dev, &idx)) {
> + ret = -ENODEV;
> + goto err_kfree;
> + }
> +
> for (i = 0; i < len; i++) {
> int bval = (i + block * EDID_LENGTH) << 8;
>
> @@ -449,20 +454,23 @@ static int udl_get_edid_block(void *data, u8 *buf, unsigned int block, size_t le
> 0xA1, read_buff, 2, USB_CTRL_GET_TIMEOUT);
> if (ret < 0) {
> drm_err(dev, "Read EDID byte %zu failed err %x\n", i, ret);
> - goto err_kfree;
> + goto err_drm_dev_exit;
> } else if (ret < 1) {
> ret = -EIO;
> drm_err(dev, "Read EDID byte %zu failed\n", i);
> - goto err_kfree;
> + goto err_drm_dev_exit;
> }
>
> buf[i] = read_buff[1];
> }
>
> + drm_dev_exit(idx);
> kfree(read_buff);
>
> return 0;
>
> +err_drm_dev_exit:
> + drm_dev_exit(idx);
> err_kfree:
> kfree(read_buff);
> return ret;
> @@ -474,21 +482,15 @@ static enum drm_connector_status udl_connector_detect(struct drm_connector *conn
> struct udl_device *udl = to_udl(dev);
> struct udl_connector *udl_connector = to_udl_connector(connector);
> enum drm_connector_status status = connector_status_disconnected;
> - int idx;
>
> /* cleanup previous EDID */
> kfree(udl_connector->edid);
> udl_connector->edid = NULL;
>
> - if (!drm_dev_enter(dev, &idx))
> - return connector_status_disconnected;
> -
> udl_connector->edid = drm_do_get_edid(connector, udl_get_edid_block, udl);
> if (udl_connector->edid)
> status = connector_status_connected;
>
> - drm_dev_exit(idx);
> -
> return status;
> }
--
Jani Nikula, Intel
