On 11/3/21 8:58 AM, Marek Vasut wrote:

...

As we see in the drm_connector_list_iter_next(), it could return NULL. In order to avoid the use of the NULL pointer, it may be better to check the return value.

Fixes: c42001e ("drm: mxsfb: Use drm_panel_bridge") Signed-off-by: Jiasheng Jiang jiasheng@iscas.ac.cn

---

drivers/gpu/drm/mxsfb/mxsfb_drv.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c b/drivers/gpu/drm/mxsfb/mxsfb_drv.c index 6da9355..b875c11 100644 --- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c +++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c @@ -145,6 +145,8 @@ static int mxsfb_attach_bridge(struct mxsfb_drm_private *mxsfb) */ drm_connector_list_iter_begin(drm, &iter); mxsfb->connector = drm_connector_list_iter_next(&iter);

• if (!mxsfb->connector)

• return 1;
  

In which case does this happen failure happen ? What is the test case ?

As fas as I am concerned, 'connector_list' in the drm_connector_list_iter_next() is initialized in the drm_mode_config_init(), which is 'connector_list->next = connector_list'. And therefore, the check in drm_connector_list_iter_next() that 'if (lhead->next == &config->connector_list)' is directly satisfied and returns NULL. I am not sure wheter it is designed on purpose. If not, please fix it.