vsock/test: add a final full barrier after run all tests

If the last test fails, the other side still completes correctly,
which could lead to false positives.

Let's add a final barrier that ensures that the last test has finished
correctly on both sides, but also that the two sides agree on the
number of tests to be performed.

Fixes: 2f65b44e199c ("VSOCK: add full barrier between test cases")
Reviewed-by: Luigi Leonardi <[e-mail]>
Signed-off-by: Stefano Garzarella <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/vsock/util.c

···
 
 		printf("ok\n");
 	}
+
+	printf("All tests have been executed. Waiting other peer...");
+	fflush(stdout);
+
+	/*
+	 * Final full barrier, to ensure that all tests have been run and
+	 * that even the last one has been successful on both sides.
+	 */
+	control_writeln("COMPLETED");
+	control_expectln("COMPLETED");
+
+	printf("ok\n");
 }
 
 void list_tests(const struct test_case *test_cases)