linux-kernel - [PATCH] net: microchip: sparx5: reduce stack usage

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Message-Id: <20230217095815.2407377-1-arnd@kernel.org>
Date:   Fri, 17 Feb 2023 10:58:06 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Lars Povlsen <lars.povlsen@...rochip.com>,
        Steen Hegelund <Steen.Hegelund@...rochip.com>,
        Daniel Machon <daniel.machon@...rochip.com>,
        UNGLinuxDriver@...rochip.com,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Horatiu Vultur <horatiu.vultur@...rochip.com>,
        Yang Yingliang <yangyingliang@...wei.com>,
        linux-arm-kernel@...ts.infradead.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] net: microchip: sparx5: reduce stack usage

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

The vcap_admin structures in vcap_api_next_lookup_advanced_test()
take several hundred bytes of stack frame, but when CONFIG_KASAN_STACK
is enabled, each one of them also has extra padding before and after
it, which ends up blowing the warning limit:

In file included from drivers/net/ethernet/microchip/vcap/vcap_api.c:3521:
drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c: In function 'vcap_api_next_lookup_advanced_test':
drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c:1954:1: error: the frame size of 1448 bytes is larger than 1400 bytes [-Werror=frame-larger-than=]
 1954 | }

Reduce the total stack usage by replacing the five structures with
an array that only needs one pair of padding areas.

Fixes: 1f741f001160 ("net: microchip: sparx5: Add KUNIT tests for enabling/disabling chains")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 .../ethernet/microchip/vcap/vcap_api_kunit.c  | 26 +++++++++----------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c b/drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c
index 0a1d4d740567..c07f25e791c7 100644
--- a/drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c
+++ b/drivers/net/ethernet/microchip/vcap/vcap_api_kunit.c
@@ -1876,53 +1876,51 @@ static void vcap_api_next_lookup_basic_test(struct kunit *test)
 
 static void vcap_api_next_lookup_advanced_test(struct kunit *test)
 {
-	struct vcap_admin admin1 = {
+	struct vcap_admin admin[] = {
+	{
 		.vtype = VCAP_TYPE_IS0,
 		.vinst = 0,
 		.first_cid = 1000000,
 		.last_cid =  1199999,
 		.lookups = 6,
 		.lookups_per_instance = 2,
-	};
-	struct vcap_admin admin2 = {
+	}, {
 		.vtype = VCAP_TYPE_IS0,
 		.vinst = 1,
 		.first_cid = 1200000,
 		.last_cid =  1399999,
 		.lookups = 6,
 		.lookups_per_instance = 2,
-	};
-	struct vcap_admin admin3 = {
+	}, {
 		.vtype = VCAP_TYPE_IS0,
 		.vinst = 2,
 		.first_cid = 1400000,
 		.last_cid =  1599999,
 		.lookups = 6,
 		.lookups_per_instance = 2,
-	};
-	struct vcap_admin admin4 = {
+	}, {
 		.vtype = VCAP_TYPE_IS2,
 		.vinst = 0,
 		.first_cid = 8000000,
 		.last_cid = 8199999,
 		.lookups = 4,
 		.lookups_per_instance = 2,
-	};
-	struct vcap_admin admin5 = {
+	}, {
 		.vtype = VCAP_TYPE_IS2,
 		.vinst = 1,
 		.first_cid = 8200000,
 		.last_cid = 8399999,
 		.lookups = 4,
 		.lookups_per_instance = 2,
+	}
 	};
 	bool ret;
 
-	vcap_test_api_init(&admin1);
-	list_add_tail(&admin2.list, &test_vctrl.list);
-	list_add_tail(&admin3.list, &test_vctrl.list);
-	list_add_tail(&admin4.list, &test_vctrl.list);
-	list_add_tail(&admin5.list, &test_vctrl.list);
+	vcap_test_api_init(&admin[0]);
+	list_add_tail(&admin[1].list, &test_vctrl.list);
+	list_add_tail(&admin[2].list, &test_vctrl.list);
+	list_add_tail(&admin[3].list, &test_vctrl.list);
+	list_add_tail(&admin[4].list, &test_vctrl.list);
 
 	ret = vcap_is_next_lookup(&test_vctrl, 1000000, 1001000);
 	KUNIT_EXPECT_EQ(test, false, ret);
-- 
2.39.1