[PATCH xf86-video-ati] Only change Set/MoveCursor hooks from what we expect

[Alex Deucher]

On Mon, Mar 5, 2018 at 12:44 PM, Michel Dänzer <michel at daenzer.net> wrote:
> From: Michel Dänzer <michel.daenzer at amd.com>
>
> Since xf86CursorCloseScreen runs after RADEONCloseScreen_KMS,
> PointPriv->spriteFuncs doesn't point to the same struct in the latter as
> in RADEONCursorInit_KMS. So we were restoring info->Set/MoveCursor to
> the wrong struct. Then in the next server generation,
> info->Set/MoveCursor would end up pointing to
> drmmode_sprite_set/move_cursor, resulting in an infinite loop if one of
> them was called.
>
> To avoid this, only change the Set/MoveCursor hooks if their values
> match our expectations, otherwise leave them as is. This is kind of a
> hack, but the alternative would be invasive and thus risky changes to
> the way we're wrapping CloseScreen, and it's not even clear that can
> work without changing xserver code.
>
> Fixes: 1fe8ca75974c ("Keep track of how many SW cursors are visible on
>                       each screen")
> Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>

Acked-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  src/radeon_kms.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/src/radeon_kms.c b/src/radeon_kms.c
> index 85390e306..790d4be16 100644
> --- a/src/radeon_kms.c
> +++ b/src/radeon_kms.c
> @@ -2017,10 +2017,12 @@ static Bool RADEONCursorInit_KMS(ScreenPtr pScreen)
>             return FALSE;
>         }
>
> -       info->SetCursor = PointPriv->spriteFuncs->SetCursor;
> -       info->MoveCursor = PointPriv->spriteFuncs->MoveCursor;
> -       PointPriv->spriteFuncs->SetCursor = drmmode_sprite_set_cursor;
> -       PointPriv->spriteFuncs->MoveCursor = drmmode_sprite_move_cursor;
> +       if (PointPriv->spriteFuncs->SetCursor != drmmode_sprite_set_cursor) {
> +           info->SetCursor = PointPriv->spriteFuncs->SetCursor;
> +           info->MoveCursor = PointPriv->spriteFuncs->MoveCursor;
> +           PointPriv->spriteFuncs->SetCursor = drmmode_sprite_set_cursor;
> +           PointPriv->spriteFuncs->MoveCursor = drmmode_sprite_move_cursor;
> +       }
>      }
>
>      if (xf86ReturnOptValBool(info->Options, OPTION_SW_CURSOR, FALSE))
> @@ -2184,8 +2186,10 @@ static Bool RADEONCloseScreen_KMS(ScreenPtr pScreen)
>         miPointerScreenPtr PointPriv =
>             dixLookupPrivate(&pScreen->devPrivates, miPointerScreenKey);
>
> -       PointPriv->spriteFuncs->SetCursor = info->SetCursor;
> -       PointPriv->spriteFuncs->MoveCursor = info->MoveCursor;
> +       if (PointPriv->spriteFuncs->SetCursor == drmmode_sprite_set_cursor) {
> +           PointPriv->spriteFuncs->SetCursor = info->SetCursor;
> +           PointPriv->spriteFuncs->MoveCursor = info->MoveCursor;
> +       }
>      }
>
>      pScreen->BlockHandler = info->BlockHandler;
> --
> 2.16.2
>
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