selftests/bpf: Let libbpf determine program type from section name

Now that libbpf can recognize SK_REUSEPORT programs, we no longer have to
pass a prog_type hint before loading the object file.
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191212102259.418536-3-jakub@cloudflare.com

tools/testing/selftests/bpf/progs/test_select_reuseport_kern.c

@@ -62,7 +62,7 @@ struct {
 	goto done;				\
 })
 
-SEC("select_by_skb_data")
+SEC("sk_reuseport")
 int _select_by_skb_data(struct sk_reuseport_md *reuse_md)
 {
 	__u32 linum, index = 0, flags = 0, index_zero = 0;

tools/testing/selftests/bpf/test_select_reuseport.c

@@ -87,19 +87,11 @@ static void prepare_bpf_obj(void)
 	struct bpf_program *prog;
 	struct bpf_map *map;
 	int err;
-	struct bpf_object_open_attr attr = {
-		.file = "test_select_reuseport_kern.o",
-		.prog_type = BPF_PROG_TYPE_SK_REUSEPORT,
-	};
 
-	obj = bpf_object__open_xattr(&attr);
+	obj = bpf_object__open("test_select_reuseport_kern.o");
 	CHECK(IS_ERR_OR_NULL(obj), "open test_select_reuseport_kern.o",
 	      "obj:%p PTR_ERR(obj):%ld\n", obj, PTR_ERR(obj));
 
-	prog = bpf_program__next(NULL, obj);
-	CHECK(!prog, "get first bpf_program", "!prog\n");
-	bpf_program__set_type(prog, attr.prog_type);
-
 	map = bpf_object__find_map_by_name(obj, "outer_map");
 	CHECK(!map, "find outer_map", "!map\n");
 	err = bpf_map__reuse_fd(map, outer_map);
@@ -108,6 +100,8 @@ static void prepare_bpf_obj(void)
 	err = bpf_object__load(obj);
 	CHECK(err, "load bpf_object", "err:%d\n", err);
 
+	prog = bpf_program__next(NULL, obj);
+	CHECK(!prog, "get first bpf_program", "!prog\n");
 	select_by_skb_data_prog = bpf_program__fd(prog);
 	CHECK(select_by_skb_data_prog == -1, "get prog fd",
 	      "select_by_skb_data_prog:%d\n", select_by_skb_data_prog);