[Intel-gfx] [PATCH 12/22] drm/msm: Use drm_mode_copy()

[Abhinav Kumar]

On 2/18/2022 2:03 AM, 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: Rob Clark <robdclark at gmail.com>
> Cc: Sean Paul <sean at poorly.run>
> Cc: Abhinav Kumar <quic_abhinavk at quicinc.com>
> Cc: linux-arm-msm at vger.kernel.org
> Cc: freedreno at lists.freedesktop.org
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Reviewed-by: Abhinav Kumar <quic_abhinavk at quicinc.com>
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c | 2 +-
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c | 2 +-
>   drivers/gpu/drm/msm/dp/dp_display.c                  | 2 +-
>   3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
> index 34a6940d12c5..57592052af23 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
> @@ -157,7 +157,7 @@ static void dpu_encoder_phys_cmd_mode_set(
>   		DPU_ERROR("invalid args\n");
>   		return;
>   	}
> -	phys_enc->cached_mode = *adj_mode;
> +	drm_mode_copy(&phys_enc->cached_mode, adj_mode);
>   	DPU_DEBUG_CMDENC(cmd_enc, "caching mode:\n");
>   	drm_mode_debug_printmodeline(adj_mode);
>   
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
> index e7813c6f7bd9..d5deca07b65a 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
> @@ -370,7 +370,7 @@ static void dpu_encoder_phys_vid_mode_set(
>   	struct dpu_encoder_irq *irq;
>   
>   	if (adj_mode) {
> -		phys_enc->cached_mode = *adj_mode;
> +		drm_mode_copy(&phys_enc->cached_mode, adj_mode);
>   		drm_mode_debug_printmodeline(adj_mode);
>   		DPU_DEBUG_VIDENC(phys_enc, "caching mode:\n");
>   	}
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 7cc4d21f2091..2ed6028ca8d6 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -825,7 +825,7 @@ static int dp_display_set_mode(struct msm_dp *dp_display,
>   
>   	dp = container_of(dp_display, struct dp_display_private, dp_display);
>   
> -	dp->panel->dp_mode.drm_mode = mode->drm_mode;
> +	drm_mode_copy(&dp->panel->dp_mode.drm_mode, &mode->drm_mode);
>   	dp->panel->dp_mode.bpp = mode->bpp;
>   	dp->panel->dp_mode.capabilities = mode->capabilities;
>   	dp_panel_init_panel_info(dp->panel);