for timer list is operated by per-cpu; and no interrupt service operates it too. So it's unnecessary for spinlock. Signed-off-by: Minggui Cao <minggui.cao@intel.com> Reviewed-by: Yin Fengwei <fengwei.yin@intel.com> Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com> Acked-by: Eddie Dong <eddie.dong@intel.com>