[PATCH 04/22] drm/amdgpu: Use drm_mode_copy()

[Alex Deucher]

Applied.  Thanks!

Alex

On Fri, Feb 18, 2022 at 11:32 AM Harry Wentland <harry.wentland at amd.com> wrote:
>
>
>
> On 2022-02-18 05:03, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> >
> > struct drm_display_mode embeds a list head, so overwriting
> > the full struct with another one will corrupt the list
> > (if the destination mode is on a list). Use drm_mode_copy()
> > instead which explicitly preserves the list head of
> > the destination mode.
> >
> > Even if we know the destination mode is not on any list
> > using drm_mode_copy() seems decent as it sets a good
> > example. Bad examples of not using it might eventually
> > get copied into code where preserving the list head
> > actually matters.
> >
> > Obviously one case not covered here is when the mode
> > itself is embedded in a larger structure and the whole
> > structure is copied. But if we are careful when copying
> > into modes embedded in structures I think we can be a
> > little more reassured that bogus list heads haven't been
> > propagated in.
> >
> > @is_mode_copy@
> > @@
> > drm_mode_copy(...)
> > {
> > ...
> > }
> >
> > @depends on !is_mode_copy@
> > struct drm_display_mode *mode;
> > expression E, S;
> > @@
> > (
> > - *mode = E
> > + drm_mode_copy(mode, &E)
> > |
> > - memcpy(mode, E, S)
> > + drm_mode_copy(mode, E)
> > )
> >
> > @depends on !is_mode_copy@
> > struct drm_display_mode mode;
> > expression E;
> > @@
> > (
> > - mode = E
> > + drm_mode_copy(&mode, &E)
> > |
> > - memcpy(&mode, E, S)
> > + drm_mode_copy(&mode, E)
> > )
> >
> > @@
> > struct drm_display_mode *mode;
> > @@
> > - &*mode
> > + mode
> >
> > Cc: Alex Deucher <alexander.deucher at amd.com>
> > Cc: Harry Wentland <harry.wentland at amd.com>
> > Cc: Leo Li <sunpeng.li at amd.com>
> > Cc: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
> > Cc: amd-gfx at lists.freedesktop.org
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Reviewed-by: Harry Wentland <harry.wentland at amd.com>
>
> Harry
>
> > ---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c    | 4 ++--
> >  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 6 +++---
> >  2 files changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> > index fa20261aa928..673078faa27a 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> > @@ -626,7 +626,7 @@ amdgpu_connector_fixup_lcd_native_mode(struct drm_encoder *encoder,
> >               if (mode->type & DRM_MODE_TYPE_PREFERRED) {
> >                       if (mode->hdisplay != native_mode->hdisplay ||
> >                           mode->vdisplay != native_mode->vdisplay)
> > -                             memcpy(native_mode, mode, sizeof(*mode));
> > +                             drm_mode_copy(native_mode, mode);
> >               }
> >       }
> >
> > @@ -635,7 +635,7 @@ amdgpu_connector_fixup_lcd_native_mode(struct drm_encoder *encoder,
> >               list_for_each_entry_safe(mode, t, &connector->probed_modes, head) {
> >                       if (mode->hdisplay == native_mode->hdisplay &&
> >                           mode->vdisplay == native_mode->vdisplay) {
> > -                             *native_mode = *mode;
> > +                             drm_mode_copy(native_mode, mode);
> >                               drm_mode_set_crtcinfo(native_mode, CRTC_INTERLACE_HALVE_V);
> >                               DRM_DEBUG_KMS("Determined LVDS native mode details from EDID\n");
> >                               break;
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > index bd23c9e481eb..514280699ad5 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > @@ -6318,7 +6318,7 @@ get_highest_refresh_rate_mode(struct amdgpu_dm_connector *aconnector,
> >               }
> >       }
> >
> > -     aconnector->freesync_vid_base = *m_pref;
> > +     drm_mode_copy(&aconnector->freesync_vid_base, m_pref);
> >       return m_pref;
> >  }
> >
> > @@ -6432,8 +6432,8 @@ create_stream_for_sink(struct amdgpu_dm_connector *aconnector,
> >               recalculate_timing = is_freesync_video_mode(&mode, aconnector);
> >               if (recalculate_timing) {
> >                       freesync_mode = get_highest_refresh_rate_mode(aconnector, false);
> > -                     saved_mode = mode;
> > -                     mode = *freesync_mode;
> > +                     drm_mode_copy(&saved_mode, &mode);
> > +                     drm_mode_copy(&mode, freesync_mode);
> >               } else {
> >                       decide_crtc_timing_for_drm_display_mode(
> >                               &mode, preferred_mode, scale);
>