drm/vmwgfx: Don't overwrite KMS surface dirty tracker

[ Upstream commit c6cb77c ]

We were overwriting the surface's dirty tracker here causing a memory leak.

Reported-by: Mika Penttilä <mpenttil@redhat.com>
Closes: https://lore.kernel.org/dri-devel/8c53f3c6-c6de-46fe-a8ca-d98dd52b3abe@redhat.com/
Fixes: 9655441 ("drm/vmwgfx: Refactor cursor handling")
Signed-off-by: Ian Forbes <ian.forbes@broadcom.com>
Reviewed-by: Maaz Mombasawala <maaz.mombasawala@broadcom.com>
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Link: https://patch.msgid.link/20260302200330.66763-1-ian.forbes@broadcom.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: en4bz

drivers/gpu/drm/vmwgfx/vmwgfx_kms.c

@@ -771,7 +771,8 @@ static struct drm_framebuffer *vmw_kms_fb_create(struct drm_device *dev,
 		ret = vmw_bo_dirty_add(bo);
 		if (!ret && surface && surface->res.func->dirty_alloc) {
 			surface->res.coherent = true;
-			ret = surface->res.func->dirty_alloc(&surface->res);
+			if (surface->res.dirty == NULL)
+				ret = surface->res.func->dirty_alloc(&surface->res);
 		}
 		ttm_bo_unreserve(&bo->tbo);
 	}