#! stap -p2

probe kernel.function("vfs_read") if (foo(2)) { }  # must not call functions

function foo(x) { return x }

# NB: If this condition is relaxed, then this will have to be blocked:
#    global y function foo () { return y++ }   # since global y is written-to
# but this one would be fine:
#    function foo () { return y++ }   # since y is written-to