[PATCH 05/22] drm/radeon: Use drm_mode_copy()

[Alex Deucher]

Applied.  Thanks!

Alex

On Fri, Feb 18, 2022 at 5:04 AM Ville Syrjala
<ville.syrjala at linux.intel.com> 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: amd-gfx at lists.freedesktop.org
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/radeon/radeon_connectors.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
> index a7925a8290b2..0cb1345c6ba4 100644
> --- a/drivers/gpu/drm/radeon/radeon_connectors.c
> +++ b/drivers/gpu/drm/radeon/radeon_connectors.c
> @@ -777,7 +777,7 @@ static void radeon_fixup_lvds_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);
>                 }
>         }
>
> @@ -786,7 +786,7 @@ static void radeon_fixup_lvds_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;
> --
> 2.34.1
>