Commit ee8c7c6c authored by Jordan Rome's avatar Jordan Rome Committed by Andrii Nakryiko
Browse files

bpf: Properly test iter/task tid filtering 



Previously test_task_tid was setting `linfo.task.tid`
to `getpid()` which is the same as `gettid()` for the
parent process. Instead create a new child thread
and set `linfo.task.tid` to `gettid()` to make sure
the tid filtering logic is working as expected.

Signed-off-by: default avatarJordan Rome <linux@jordanrome.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241016210048.1213935-2-linux@jordanrome.com
parent 9495a5b7

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

+22 −5
Original line number Diff line number Diff line
@@ -226,7 +226,7 @@ static void test_task_common_nocheck(struct bpf_iter_attach_opts *opts, 
	ASSERT_OK(pthread_create(&thread_id, NULL, &do_nothing_wait, NULL),

		  "pthread_create");



	skel->bss->tid = getpid();

	skel->bss->tid = gettid();



	do_dummy_read_opts(skel->progs.dump_task, opts);
@@ -249,25 +249,42 @@ static void test_task_common(struct bpf_iter_attach_opts *opts, int num_unknown, 
	ASSERT_EQ(num_known_tid, num_known, "check_num_known_tid");

}



static void test_task_tid(void)

static void *run_test_task_tid(void *arg)

{

	LIBBPF_OPTS(bpf_iter_attach_opts, opts);

	union bpf_iter_link_info linfo;

	int num_unknown_tid, num_known_tid;



	ASSERT_NEQ(getpid(), gettid(), "check_new_thread_id");



	memset(&linfo, 0, sizeof(linfo));

	linfo.task.tid = getpid();

	linfo.task.tid = gettid();

	opts.link_info = &linfo;

	opts.link_info_len = sizeof(linfo);

	test_task_common(&opts, 0, 1);



	linfo.task.tid = 0;

	linfo.task.pid = getpid();

	test_task_common(&opts, 1, 1);

	/* This includes the parent thread, this thread,

	 * and the do_nothing_wait thread

	 */

	test_task_common(&opts, 2, 1);



	test_task_common_nocheck(NULL, &num_unknown_tid, &num_known_tid);

	ASSERT_GT(num_unknown_tid, 1, "check_num_unknown_tid");

	ASSERT_GT(num_unknown_tid, 2, "check_num_unknown_tid");

	ASSERT_EQ(num_known_tid, 1, "check_num_known_tid");



	return NULL;

}



static void test_task_tid(void)

{

	pthread_t thread_id;



	/* Create a new thread so pid and tid aren't the same */

	ASSERT_OK(pthread_create(&thread_id, NULL, &run_test_task_tid, NULL),

		  "pthread_create");

	ASSERT_FALSE(pthread_join(thread_id, NULL), "pthread_join");

}



static void test_task_pid(void)