linux-kernel - [PATCH] drm/test: reduce stack size in drm_exec

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Message-Id: <20250610093350.2645965-1-arnd@kernel.org>
Date: Tue, 10 Jun 2025 11:33:46 +0200
From: Arnd Bergmann <arnd@...nel.org>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>
Cc: Arnd Bergmann <arnd@...db.de>,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] drm/test: reduce stack size in drm_exec_test

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

test_prepare_array() is one of the functions that uses more than
a kilobyte of stack on 64-bit machines, though it stays under
the usual warning limit of 2KB:

drivers/gpu/drm/tests/drm_exec_test.c: In function 'test_prepare_array':
drivers/gpu/drm/tests/drm_exec_test.c:171:1: error: the frame size of 1304 bytes is larger than 1280 bytes [-Werror=frame-larger-than=]

In order to eventually lower that limit, change the two large
drm_gem_object objects to be statically allocated. This works here
because the tests are always called sequentially, and it is simpler than
using kzalloc().

Fixes: 9710631cc8f3 ("drm: add drm_exec selftests v4")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/gpu/drm/tests/drm_exec_test.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/tests/drm_exec_test.c b/drivers/gpu/drm/tests/drm_exec_test.c
index d6c4dd1194a0..f2ac06a07707 100644
--- a/drivers/gpu/drm/tests/drm_exec_test.c
+++ b/drivers/gpu/drm/tests/drm_exec_test.c
@@ -18,6 +18,8 @@
 
 #include "../lib/drm_random.h"
 
+static struct drm_gem_object gobj, gobj2;
+
 struct drm_exec_priv {
 	struct device *dev;
 	struct drm_device *drm;
@@ -54,7 +56,6 @@ static void sanitycheck(struct kunit *test)
 static void test_lock(struct kunit *test)
 {
 	struct drm_exec_priv *priv = test->priv;
-	struct drm_gem_object gobj = { };
 	struct drm_exec exec;
 	int ret;
 
@@ -74,7 +75,6 @@ static void test_lock(struct kunit *test)
 static void test_lock_unlock(struct kunit *test)
 {
 	struct drm_exec_priv *priv = test->priv;
-	struct drm_gem_object gobj = { };
 	struct drm_exec exec;
 	int ret;
 
@@ -101,7 +101,6 @@ static void test_lock_unlock(struct kunit *test)
 static void test_duplicates(struct kunit *test)
 {
 	struct drm_exec_priv *priv = test->priv;
-	struct drm_gem_object gobj = { };
 	struct drm_exec exec;
 	int ret;
 
@@ -128,7 +127,6 @@ static void test_duplicates(struct kunit *test)
 static void test_prepare(struct kunit *test)
 {
 	struct drm_exec_priv *priv = test->priv;
-	struct drm_gem_object gobj = { };
 	struct drm_exec exec;
 	int ret;
 
@@ -150,13 +148,11 @@ static void test_prepare(struct kunit *test)
 static void test_prepare_array(struct kunit *test)
 {
 	struct drm_exec_priv *priv = test->priv;
-	struct drm_gem_object gobj1 = { };
-	struct drm_gem_object gobj2 = { };
-	struct drm_gem_object *array[] = { &gobj1, &gobj2 };
+	struct drm_gem_object *array[] = { &gobj, &gobj2 };
 	struct drm_exec exec;
 	int ret;
 
-	drm_gem_private_object_init(priv->drm, &gobj1, PAGE_SIZE);
+	drm_gem_private_object_init(priv->drm, &gobj, PAGE_SIZE);
 	drm_gem_private_object_init(priv->drm, &gobj2, PAGE_SIZE);
 
 	drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT, 0);
@@ -166,7 +162,7 @@ static void test_prepare_array(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, ret, 0);
 	drm_exec_fini(&exec);
 
-	drm_gem_private_object_fini(&gobj1);
+	drm_gem_private_object_fini(&gobj);
 	drm_gem_private_object_fini(&gobj2);
 }
 
-- 
2.39.5