netdev - [PATCH bpf-next] selftest/bpf: Switch recursion test to use htab_map_delete

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Date:   Sun, 3 Oct 2021 18:49:25 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andriin@...com>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>
Subject: [PATCH bpf-next] selftest/bpf: Switch recursion test to use
 htab_map_delete_elem

Currently the recursion test is hooking __htab_map_lookup_elem
function, which is invoked both from bpf_prog and bpf syscall.

But in our kernel build, the __htab_map_lookup_elem gets inlined
within the htab_map_lookup_elem, so it's not trigered and the
test fails.

Fixing this by using htab_map_delete_elem, which is not inlined
for bpf_prog calls (like htab_map_lookup_elem is) and is used
directly as pointer for map_delete_elem, so it won't disappear
by inlining.

Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 tools/testing/selftests/bpf/prog_tests/recursion.c | 10 +++++-----
 tools/testing/selftests/bpf/progs/recursion.c      |  9 +++------
 2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/recursion.c b/tools/testing/selftests/bpf/prog_tests/recursion.c
index 0e378d63fe18..f3af2627b599 100644
--- a/tools/testing/selftests/bpf/prog_tests/recursion.c
+++ b/tools/testing/selftests/bpf/prog_tests/recursion.c
@@ -20,18 +20,18 @@ void test_recursion(void)
 		goto out;
 
 	ASSERT_EQ(skel->bss->pass1, 0, "pass1 == 0");
-	bpf_map_lookup_elem(bpf_map__fd(skel->maps.hash1), &key, 0);
+	bpf_map_delete_elem(bpf_map__fd(skel->maps.hash1), &key);
 	ASSERT_EQ(skel->bss->pass1, 1, "pass1 == 1");
-	bpf_map_lookup_elem(bpf_map__fd(skel->maps.hash1), &key, 0);
+	bpf_map_delete_elem(bpf_map__fd(skel->maps.hash1), &key);
 	ASSERT_EQ(skel->bss->pass1, 2, "pass1 == 2");
 
 	ASSERT_EQ(skel->bss->pass2, 0, "pass2 == 0");
-	bpf_map_lookup_elem(bpf_map__fd(skel->maps.hash2), &key, 0);
+	bpf_map_delete_elem(bpf_map__fd(skel->maps.hash2), &key);
 	ASSERT_EQ(skel->bss->pass2, 1, "pass2 == 1");
-	bpf_map_lookup_elem(bpf_map__fd(skel->maps.hash2), &key, 0);
+	bpf_map_delete_elem(bpf_map__fd(skel->maps.hash2), &key);
 	ASSERT_EQ(skel->bss->pass2, 2, "pass2 == 2");
 
-	err = bpf_obj_get_info_by_fd(bpf_program__fd(skel->progs.on_lookup),
+	err = bpf_obj_get_info_by_fd(bpf_program__fd(skel->progs.on_delete),
 				     &prog_info, &prog_info_len);
 	if (!ASSERT_OK(err, "get_prog_info"))
 		goto out;
diff --git a/tools/testing/selftests/bpf/progs/recursion.c b/tools/testing/selftests/bpf/progs/recursion.c
index 49f679375b9d..3c2423bb19e2 100644
--- a/tools/testing/selftests/bpf/progs/recursion.c
+++ b/tools/testing/selftests/bpf/progs/recursion.c
@@ -24,8 +24,8 @@ struct {
 int pass1 = 0;
 int pass2 = 0;
 
-SEC("fentry/__htab_map_lookup_elem")
-int BPF_PROG(on_lookup, struct bpf_map *map)
+SEC("fentry/htab_map_delete_elem")
+int BPF_PROG(on_delete, struct bpf_map *map)
 {
 	int key = 0;
 
@@ -35,10 +35,7 @@ int BPF_PROG(on_lookup, struct bpf_map *map)
 	}
 	if (map == (void *)&hash2) {
 		pass2++;
-		/* htab_map_gen_lookup() will inline below call
-		 * into direct call to __htab_map_lookup_elem()
-		 */
-		bpf_map_lookup_elem(&hash2, &key);
+		bpf_map_delete_elem(&hash2, &key);
 		return 0;
 	}
 
-- 
2.31.1