selftests/bpf: ns_current_pid_tgid: Use test_progs's ns_ feature

Two subtests use the test_in_netns() function to run the test in a
dedicated network namespace. This can now be done directly through the
test_progs framework with a test name starting with 'ns_'.

Replace the use of test_in_netns() by test_ns_* calls.

Signed-off-by: Bastien Curutchet (eBPF Foundation) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

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

···
 		return;
 }
 
-static void test_in_netns(int (*fn)(void *), void *arg)
-{
-	struct nstoken *nstoken = NULL;
-
-	SYS(cleanup, "ip netns add ns_current_pid_tgid");
-	SYS(cleanup, "ip -net ns_current_pid_tgid link set dev lo up");
-
-	nstoken = open_netns("ns_current_pid_tgid");
-	if (!ASSERT_OK_PTR(nstoken, "open_netns"))
-		goto cleanup;
-
-	test_ns_current_pid_tgid_new_ns(fn, arg);
-
-cleanup:
-	if (nstoken)
-		close_netns(nstoken);
-	SYS_NOFAIL("ip netns del ns_current_pid_tgid");
-}
-
 /* TODO: use a different tracepoint */
 void serial_test_current_pid_tgid(void)
 {
···
 		test_current_pid_tgid_tp(NULL);
 	if (test__start_subtest("new_ns_tp"))
 		test_ns_current_pid_tgid_new_ns(test_current_pid_tgid_tp, NULL);
-	if (test__start_subtest("new_ns_cgrp")) {
-		int cgroup_fd = -1;
-
-		cgroup_fd = test__join_cgroup("/sock_addr");
-		if (ASSERT_GE(cgroup_fd, 0, "join_cgroup")) {
-			test_in_netns(test_current_pid_tgid_cgrp, &cgroup_fd);
-			close(cgroup_fd);
-		}
-	}
-	if (test__start_subtest("new_ns_sk_msg"))
-		test_in_netns(test_current_pid_tgid_sk_msg, NULL);
 }
+
+void test_ns_current_pid_tgid_cgrp(void)
+{
+	int cgroup_fd = test__join_cgroup("/sock_addr");
+
+	if (ASSERT_OK_FD(cgroup_fd, "join_cgroup")) {
+		test_ns_current_pid_tgid_new_ns(test_current_pid_tgid_cgrp, &cgroup_fd);
+		close(cgroup_fd);
+	}
+}
+
+void test_ns_current_pid_tgid_sk_msg(void)
+{
+	test_ns_current_pid_tgid_new_ns(test_current_pid_tgid_sk_msg, NULL);
+}
+
+