linux-kernel - [PATCH] drm/tests: reduce drm_mm

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Date:   Thu, 15 Dec 2022 17:34:49 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Maíra Canal <maira.canal@....br>,
        Daniel Latypov <dlatypov@...gle.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev
Subject: [PATCH] drm/tests: reduce drm_mm_test stack usage

From: Arnd Bergmann <arnd@...db.de>

The check_reserve_boundaries function uses a lot of kernel stack,
and it gets inlined by clang, which makes __drm_test_mm_reserve
use even more of it, to the point of hitting the warning limit:

drivers/gpu/drm/tests/drm_mm_test.c:344:12: error: stack frame size (1048) exceeds limit (1024) in '__drm_test_mm_reserve' [-Werror,-Wframe-larger-than]

When building with gcc, this does not happen, but the structleak
plugin can similarly increase the stack usage and needs to be
disabled, as we do for all other kunit users.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/gpu/drm/tests/Makefile      | 2 ++
 drivers/gpu/drm/tests/drm_mm_test.c | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tests/Makefile b/drivers/gpu/drm/tests/Makefile
index b29ef1085cad..f896ef85c2f2 100644
--- a/drivers/gpu/drm/tests/Makefile
+++ b/drivers/gpu/drm/tests/Makefile
@@ -12,3 +12,5 @@ obj-$(CONFIG_DRM_KUNIT_TEST) += \
 	drm_mm_test.o \
 	drm_plane_helper_test.o \
 	drm_rect_test.o
+
+CFLAGS_drm_mm_test.o := $(DISABLE_STRUCTLEAK_PLUGIN)
diff --git a/drivers/gpu/drm/tests/drm_mm_test.c b/drivers/gpu/drm/tests/drm_mm_test.c
index 89f12d3b4a21..90a5becc99b8 100644
--- a/drivers/gpu/drm/tests/drm_mm_test.c
+++ b/drivers/gpu/drm/tests/drm_mm_test.c
@@ -298,7 +298,7 @@ static bool expect_reserve_fail(struct kunit *test, struct drm_mm *mm, struct dr
 	return false;
 }
 
-static bool check_reserve_boundaries(struct kunit *test, struct drm_mm *mm,
+static bool noinline_for_stack check_reserve_boundaries(struct kunit *test, struct drm_mm *mm,
 				     unsigned int count,
 				     u64 size)
 {
-- 
2.35.1