1. 04 6月, 2010 1 次提交
    • S
      tracing/sched: Make preempt_schedule() notrace · d1f74e20
      Steven Rostedt 提交于
      The function tracer code uses ftrace_preempt_disable() to disable
      preemption instead of normal preempt_disable(). But there's a slight
      race condition that may cause it to lose a preemption check.
      
      This was made to keep the function tracer from recursing on itself
      by disabling preemption then having the enable call the function tracer
      again, causing infinite recursion.
      
      The bug was assumed to happen if the call was just in schedule, but
      this is incorrect. The bug is caused by preempt_schedule() which
      is called by preempt_enable(). The calling of preempt_enable() when
      NEED_RESCHED was set would call preempt_schedule() which would call
      the function tracer again.
      
      By making the preempt_schedule() and add_preempt_count() notrace
      then this will prevent the inifinite recursion. This is because
      the add_preempt_count() would stop the preempt_enable() in the
      function tracer from calling preempt_schedule() again.
      
      The sub_preempt_count() is also made notrace just to keep it
      symmetric.
      Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      d1f74e20
  2. 28 5月, 2010 39 次提交