Re: [PATCH] drm/selftest: plane_helper: Put test structures in static storage

On Wed, Mar 2, 2022 at 4:00 PM Nathan Chancellor nathan@kernel.org wrote:

Clang warns on certain 32-bit architectures:

drivers/gpu/drm/selftests/test-drm_plane_helper.c:76:5: warning: stack frame size (1064) exceeds limit (1024) in 'igt_check_plane_state' [-Wframe-larger-than] int igt_check_plane_state(void *ignored) ^ 1 warning generated.

The structures in igt_check_plane_state() total 1008 bytes, so any small amount of inlining will cause the stack frame to exceed the 32-bit limit of 1024, triggering the warning.

Move these structures to static storage, which dramatically reduces the amount of stack space in igt_check_plane_state(). There is no testing impact, as igt_check_plane_state() is only called once in the driver.

Fixes: 943e6a8beeac ("mock a drm_plane in igt_check_plane_state to make the test more robust") Link: https://github.com/ClangBuiltLinux/linux/issues/1600 Reported-by: kernel test robot lkp@intel.com Suggested-by: Nick Desaulniers ndesaulniers@google.com Signed-off-by: Nathan Chancellor nathan@kernel.org

Thanks for the patch! Reviewed-by: Nick Desaulniers ndesaulniers@google.com

---

drivers/gpu/drm/selftests/test-drm_plane_helper.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/selftests/test-drm_plane_helper.c b/drivers/gpu/drm/selftests/test-drm_plane_helper.c index ceebeede55ea..b61273e9c403 100644 --- a/drivers/gpu/drm/selftests/test-drm_plane_helper.c +++ b/drivers/gpu/drm/selftests/test-drm_plane_helper.c @@ -77,7 +77,7 @@ int igt_check_plane_state(void *ignored) { int ret;

•   const struct drm_crtc_state crtc_state = {
  

•   static const struct drm_crtc_state crtc_state = {
            .crtc = ZERO_SIZE_PTR,
            .enable = true,
            .active = true,
  

@@ -87,14 +87,14 @@ int igt_check_plane_state(void *ignored) DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC) }, };

•   struct drm_plane plane = {
  

•   static struct drm_plane plane = {
            .dev = NULL
    };
  

•   struct drm_framebuffer fb = {
  

•   static struct drm_framebuffer fb = {
            .width = 2048,
            .height = 2048
    };
  

•   struct drm_plane_state plane_state = {
  

•   static struct drm_plane_state plane_state = {
            .plane = &plane,
            .crtc = ZERO_SIZE_PTR,
            .fb = &fb,
  
  

base-commit: 9ae2ac4d31a85ce59cc560d514a31b95f4ace154

2.35.1