On Fri, 18 Feb 2022, Ville Syrjala ville.syrjala@linux.intel.com wrote:
From: Ville Syrjälä ville.syrjala@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
Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula jani.nikula@intel.com
drivers/gpu/drm/i915/display/intel_display.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c index 74c5a99ab276..661e36435793 100644 --- a/drivers/gpu/drm/i915/display/intel_display.c +++ b/drivers/gpu/drm/i915/display/intel_display.c @@ -5506,8 +5506,10 @@ intel_crtc_copy_uapi_to_hw_state_modeset(struct intel_atomic_state *state,
crtc_state->hw.enable = crtc_state->uapi.enable; crtc_state->hw.active = crtc_state->uapi.active;
- crtc_state->hw.mode = crtc_state->uapi.mode;
- crtc_state->hw.adjusted_mode = crtc_state->uapi.adjusted_mode;
drm_mode_copy(&crtc_state->hw.mode,
&crtc_state->uapi.mode);drm_mode_copy(&crtc_state->hw.adjusted_mode,
&crtc_state->uapi.adjusted_mode);crtc_state->hw.scaling_filter = crtc_state->uapi.scaling_filter;
intel_crtc_copy_uapi_to_hw_state_nomodeset(state, crtc);
@@ -5584,9 +5586,12 @@ copy_bigjoiner_crtc_state_modeset(struct intel_atomic_state *state, memset(&slave_crtc_state->hw, 0, sizeof(slave_crtc_state->hw)); slave_crtc_state->hw.enable = master_crtc_state->hw.enable; slave_crtc_state->hw.active = master_crtc_state->hw.active;
- slave_crtc_state->hw.mode = master_crtc_state->hw.mode;
- slave_crtc_state->hw.pipe_mode = master_crtc_state->hw.pipe_mode;
- slave_crtc_state->hw.adjusted_mode = master_crtc_state->hw.adjusted_mode;
drm_mode_copy(&slave_crtc_state->hw.mode,
&master_crtc_state->hw.mode);drm_mode_copy(&slave_crtc_state->hw.pipe_mode,
&master_crtc_state->hw.pipe_mode);drm_mode_copy(&slave_crtc_state->hw.adjusted_mode,
&master_crtc_state->hw.adjusted_mode);slave_crtc_state->hw.scaling_filter = master_crtc_state->hw.scaling_filter;
copy_bigjoiner_crtc_state_nomodeset(state, slave_crtc);