selftests/bpf: Stop using bpf_program__load

bpf_program__load is not supposed to be used directly. Replace it with
bpf_object__ APIs for the reference_tracking prog_test, which is the
last offender in bpf selftests.

Some additional complexity is added for this test, namely the use of one
bpf_object to iterate through progs, while a second bpf_object is
created and opened/closed to test actual loading of progs. This is
because the test was doing bpf_program__load then __unload to test
loading of individual progs and same semantics with
bpf_object__load/__unload result in failure to load an __unload-ed obj.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210917182911.2426606-3-davemarchevsky@fb.com

tools/testing/selftests/bpf/prog_tests/reference_tracking.c

 // SPDX-License-Identifier: GPL-2.0
 #include <test_progs.h>
 
+static void toggle_object_autoload_progs(const struct bpf_object *obj,
+					 const char *title_load)
+{
+	struct bpf_program *prog;
+
+	bpf_object__for_each_program(prog, obj) {
+		const char *title = bpf_program__section_name(prog);
+
+		if (!strcmp(title_load, title))
+			bpf_program__set_autoload(prog, true);
+		else
+			bpf_program__set_autoload(prog, false);
+	}
+}
+
 void test_reference_tracking(void)
 {
 	const char *file = "test_sk_lookup_kern.o";
@@ -9,21 +24,21 @@ void test_reference_tracking(void)
 		.object_name = obj_name,
 		.relaxed_maps = true,
 	);
-	struct bpf_object *obj;
+	struct bpf_object *obj_iter, *obj = NULL;
 	struct bpf_program *prog;
 	__u32 duration = 0;
 	int err = 0;
 
-	obj = bpf_object__open_file(file, &open_opts);
-	if (!ASSERT_OK_PTR(obj, "obj_open_file"))
+	obj_iter = bpf_object__open_file(file, &open_opts);
+	if (!ASSERT_OK_PTR(obj_iter, "obj_iter_open_file"))
 		return;
 
-	if (CHECK(strcmp(bpf_object__name(obj), obj_name), "obj_name",
+	if (CHECK(strcmp(bpf_object__name(obj_iter), obj_name), "obj_name",
 		  "wrong obj name '%s', expected '%s'\n",
-		  bpf_object__name(obj), obj_name))
+		  bpf_object__name(obj_iter), obj_name))
 		goto cleanup;
 
-	bpf_object__for_each_program(prog, obj) {
+	bpf_object__for_each_program(prog, obj_iter) {
 		const char *title;
 
 		/* Ignore .text sections */
@@ -34,19 +49,27 @@ void test_reference_tracking(void)
 		if (!test__start_subtest(title))
 			continue;
 
+		obj = bpf_object__open_file(file, &open_opts);
+		if (!ASSERT_OK_PTR(obj, "obj_open_file"))
+			goto cleanup;
+
+		toggle_object_autoload_progs(obj, title);
 		/* Expect verifier failure if test name has 'err' */
 		if (strstr(title, "err_") != NULL) {
 			libbpf_print_fn_t old_print_fn;
 
 			old_print_fn = libbpf_set_print(NULL);
-			err = !bpf_program__load(prog, "GPL", 0);
+			err = !bpf_object__load(obj);
 			libbpf_set_print(old_print_fn);
 		} else {
-			err = bpf_program__load(prog, "GPL", 0);
+			err = bpf_object__load(obj);
 		}
 		CHECK(err, title, "\n");
+		bpf_object__close(obj);
+		obj = NULL;
 	}
 
 cleanup:
 	bpf_object__close(obj);
+	bpf_object__close(obj_iter);
 }