[Intel-gfx] [PATCH] drm/crtc-helper: Fixup error handling in drm_helper_crtc_mode_set

[John Hunter]

On Thu, Jul 2, 2015 at 9:16 PM, Daniel Vetter <daniel.vetter at ffwll.ch>
wrote:

> In
>
> commit 9f658b7b62e7aefc1ee067136126eca3f58cabfd
> Author: Daniel Stone <daniels at collabora.com>
> Date:   Fri May 22 13:34:45 2015 +0100
>
>     drm/crtc_helper: Replace open-coded CRTC state helpers
>
> error handling code was broken, resulting in the first path not being
> checked correctly. Fix this by using the same pattern as in the
> transitional plane helper function drm_plane_helper_update.
>
> v2: Simplify the cleanup code while at it too.
>
> v3: After some debugging with John we realized that the above patch
> from Daniel also accidentally removed the if (crtc_state) check. This
> is legal when transitioning to atomic, when the initial state reset
> isn't all wired up yet properly. Reinstate that check to fix the bug
> John has hit.
>
> Cc: Daniel Stone <daniels at collabora.com>
> CC: Sean Paul <seanpaul at chromium.org>
> Cc: John Hunter <zhaojunwang at pku.edu.cn>
> Reported-by: John Hunter <zhaojunwang at pku.edu.cn>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
>
Tested-by: Zhao Junwang <zhjwpku at gmail.com>

> ---
>  drivers/gpu/drm/drm_crtc_helper.c | 24 +++++++++++-------------
>  1 file changed, 11 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_crtc_helper.c
> b/drivers/gpu/drm/drm_crtc_helper.c
> index 393114df88a3..93104f3555f5 100644
> --- a/drivers/gpu/drm/drm_crtc_helper.c
> +++ b/drivers/gpu/drm/drm_crtc_helper.c
> @@ -927,15 +927,13 @@ int drm_helper_crtc_mode_set(struct drm_crtc *crtc,
> struct drm_display_mode *mod
>
>         if (crtc->funcs->atomic_duplicate_state)
>                 crtc_state = crtc->funcs->atomic_duplicate_state(crtc);
> -       else {
> +       else if (crtc->state)
> +               crtc_state = drm_atomic_helper_crtc_duplicate_state(crtc);
> +       else
>                 crtc_state = kzalloc(sizeof(*crtc_state), GFP_KERNEL);
> -               if (!crtc_state)
> -                       return -ENOMEM;
> -               if (crtc->state)
> -                       __drm_atomic_helper_crtc_duplicate_state(crtc,
> crtc_state);
> -               else
> -                       crtc_state->crtc = crtc;
> -       }
> +
> +       if (!crtc_state)
> +               return -ENOMEM;
>
>         crtc_state->planes_changed = true;
>         crtc_state->mode_changed = true;
> @@ -957,11 +955,11 @@ int drm_helper_crtc_mode_set(struct drm_crtc *crtc,
> struct drm_display_mode *mod
>         ret = drm_helper_crtc_mode_set_base(crtc, x, y, old_fb);
>
>  out:
> -       if (crtc->funcs->atomic_destroy_state)
> -               crtc->funcs->atomic_destroy_state(crtc, crtc_state);
> -       else {
> -               __drm_atomic_helper_crtc_destroy_state(crtc, crtc_state);
> -               kfree(crtc_state);
> +       if (crtc_state) {
> +               if (crtc->funcs->atomic_destroy_state)
> +                       crtc->funcs->atomic_destroy_state(crtc,
> crtc_state);
> +               else
> +                       drm_atomic_helper_crtc_destroy_state(crtc,
> crtc_state);
>         }
>
>         return ret;
> --
> 2.1.4
>
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>



-- 
Best regards
Junwang Zhao
Microprocessor Research and Develop Center
Department of Computer Science &Technology
Peking University
Beijing, 100871, PRC
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