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    SubjectRe: system gets stuck in a lock during boot
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    On Mon, 2009-08-24 at 14:13 +0800, Li Zefan wrote:
    > Peter Zijlstra wrote:
    > > On Mon, 2009-08-24 at 10:41 +0800, Li Zefan wrote:
    > >
    > >>> @@ -940,7 +940,7 @@ event_create_dir(struct ftrace_event_call *call, struct dentr
    > >>> entry = trace_create_file("enable", 0644, call->dir, call,
    > >>> enable);
    > >>>
    > >>> - if (call->id)
    > >>> + if (call->id && call->profile_enable)
    > >> We do an extra check on ->profile_enable, shouldn't cause bug..
    > >>
    > >>> entry = trace_create_file("id", 0444, call->dir, call,
    > >>> id);
    > >> Any way, I don't think this commit does the right thing:
    > >>
    > >> - If CONFIG_EVENT_PROFILE=y, we'll create events/<dir>/<event>/id,
    > >> except events/ftrace/<event>/id.
    > >>
    > >> - if CONFIG_EVENT_PROFILE=n, there's no 'id' file at all!
    > >>
    > >> I think it's better to skip ftrace/ dir in perf tool code, instead of
    > >> skipping creating id files in ftrace code.
    > >
    > > No, it does do the right thing. Your patch breaks things because not all
    > > tracepoints are created through TRACE_EVENT() and will thus not have
    > > their profile_enable/disable hooks set.
    > >
    > > By giving them an ID file, there is no way to distinguish good from bad
    > > tracepoints.
    > >
    >
    > But removing the id file from events/ftrace/ might break some ftrace
    > binary parsers?
    >
    > And this commit makes 'id' file disapeared with CONFIG_EVENT_PROFILE=n.

    I introduced the id file for EVENT_PROFILE, tough luck if someone else
    relies on it.

    > > Expempting ftrace is no solid solution, suppose someone else does a
    > > TRACE_EVENT_FORMAT() tracepoint, how would you know you could use it as
    > > a profile event source?
    > >
    >
    > Agree.
    >
    > > The id files really must stay conditional.
    > >
    >
    > I don't think it's a good idea to connect it with perfcounter
    > this way. Wouldn't adding a 'profilable' file more intuitive?

    its called: id ;-)


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