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

[michel@xxxxxxxxxxx (Michel Dänzer)]

From: Michel Dänzer <michel.daenzer@xxxxxxx>

Since xf86CursorCloseScreen runs after AMDGPUCloseScreen_KMS,
PointPriv->spriteFuncs doesn't point to the same struct in the latter as
in AMDGPUCursorInit_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: 69e20839bfeb ("Keep track of how many SW cursors are visible on
                      each screen")
(Ported from radeon commit 504b8721b17a672caf1ed3eab087027c02458cab)

Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
---
 src/amdgpu_kms.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/amdgpu_kms.c b/src/amdgpu_kms.c
index e1aae9952..90e1f2531 100644
--- a/src/amdgpu_kms.c
+++ b/src/amdgpu_kms.c
@@ -1551,10 +1551,12 @@ static Bool AMDGPUCursorInit_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))
@@ -1731,8 +1733,10 @@ static Bool AMDGPUCloseScreen_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