Re: [PATCH] drm/amd/display: Use separate iterator for preferred mode lookup

[Yibiao Li]

On Fri, Oct 16, 2026 at 09:50:44AM -0600, Alex Hung wrote:
> Reviewed-by: Alex Hung <alex.hung@xxxxxxx>

Thanks for the review, Alex!

Best regards,
Yibiao


On Fri, 16 Oct 2026 09:50:44 -0600, Alex Hung <alex.hung@xxxxxxx> wrote:
> Reviewed-by: Alex Hung <alex.hung@xxxxxxx>
>
> On 10/7/26 23:17, Yibiao Li wrote:
> > [Some people who received this message don't often get email from biaobiao2233@xxxxxxxxx. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> >
> > From: Yibiao Li <biaobiao2233@xxxxxxxxx>
> >
> > create_stream_for_sink() uses preferred_mode both as the list iterator
> > and as the selected mode. This triggers a false positive from
> > scripts/coccinelle/iterators/use_after_iter.cocci: native_mode_found
> > already ensures that an exhausted iterator is replaced before use.
> >
> > Use a separate iterator and assign preferred_mode only when a preferred
> > entry is found. This keeps the selected mode separate from the iterator
> > state and makes native_mode_found unnecessary. Preserve the fallback to
> > the first entry, or NULL when the list is empty.
> >
> > No functional change intended.
> >
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Link: https://lore.kernel.org/oe-kbuild-all/202609190901.yKTzhsGz-lkp@xxxxxxxxx/
> > Assisted-by: LLM coccinelle
> > Signed-off-by: Yibiao Li <biaobiao2233@xxxxxxxxx>
> > ---
> >   .../drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c    | 10 +++++-----
> >   1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
> > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
> > index d386bb1475..ceea8fe481 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
> > @@ -1453,12 +1453,12 @@ create_stream_for_sink(struct drm_connector *connector,
> >          struct drm_device *dev = connector->dev;
> >          struct amdgpu_dm_connector *aconnector = NULL;
> >          struct drm_display_mode *preferred_mode = NULL;
> > +       struct drm_display_mode *connector_mode;
> >          const struct drm_connector_state *con_state = &dm_state->base;
> >          struct dc_stream_state *stream = NULL;
> >          struct drm_display_mode mode;
> >          struct drm_display_mode saved_mode;
> >          struct drm_display_mode *freesync_mode = NULL;
> > -       bool native_mode_found = false;
> >          bool recalculate_timing = false;
> >          bool scale = dm_state->scaling != RMX_OFF;
> >          int mode_refresh;
> > @@ -1509,14 +1509,14 @@ create_stream_for_sink(struct drm_connector *connector,
> >          stream->timing.flags.LTE_340MCSC_SCRAMBLE =
> >                  connector->display_info.hdmi.scdc.scrambling.low_rates;
> >
> > -       list_for_each_entry(preferred_mode, &connector->modes, head) {
> > +       list_for_each_entry(connector_mode, &connector->modes, head) {
> >                  /* Search for preferred mode */
> > -               if (preferred_mode->type & DRM_MODE_TYPE_PREFERRED) {
> > -                       native_mode_found = true;
> > +               if (connector_mode->type & DRM_MODE_TYPE_PREFERRED) {
> > +                       preferred_mode = connector_mode;
> >                          break;
> >                  }
> >          }
> > -       if (!native_mode_found)
> > +       if (!preferred_mode)
> >                  preferred_mode = list_first_entry_or_null(
> >                                  &connector->modes,
> >                                  struct drm_display_mode,
> > --
> > 2.43.0