On 2021/10/13 上午10:27, Steven Rostedt wrote: > On Wed, 13 Oct 2021 09:50:17 +0800 > 王贇 <yun.wang@xxxxxxxxxxxxxxxxx> wrote: > >>>> - preempt_enable_notrace(); >>>> ftrace_test_recursion_unlock(bit); >>>> } >>> >>> I don't like this change much. We have preempt_disable there not because >>> of ftrace_test_recursion, but because of RCU. ftrace_test_recursion was >>> added later. Yes, it would work with the change, but it would also hide >>> things which should not be hidden in my opinion. >> >> Not very sure about the backgroup stories, but just found this in >> 'Documentation/trace/ftrace-uses.rst': >> >> Note, on success, >> ftrace_test_recursion_trylock() will disable preemption, and the >> ftrace_test_recursion_unlock() will enable it again (if it was previously >> enabled). > > Right that part is to be fixed by what you are adding here. > > The point that Miroslav is complaining about is that the preemption > disabling is special in this case, and not just from the recursion > point of view, which is why the comment is still required. My bad... the title do confusing people, will rewrite it. Regards, Michael Wang > > -- Steve > > >> >> Seems like this lock pair was supposed to take care the preemtion itself?
