Messages in this thread | | | Date | Tue, 28 Oct 2008 20:55:57 -0400 (EDT) | From | Steven Rostedt <> | Subject | Re: [PATCH] ftrace: fix current_tracer error return |
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On Wed, 29 Oct 2008, Fr?d?ric Weisbecker wrote: > > > > My test scripts automatically set or unset /proc/sys/kernel/ftrace_enabled > > > > I believe I wanted that to be default off when dynamic ftrace was not > > active. Currently, it really shouldn't matter, because there's a check to > > make sure that ftrace has a registered function before calling it. > > > > That was just my preference. But if you find it less confusing, then > > having ftrace_enabled as default on even when dynamic ftrace is not > > enabled, is fine with me. > > > > -- Steve > > > > > > Thanks. I guess this bug was there for several days. But since I
But this was not a bug :-/
I believe I purposely set it that way. The bug was that you did not know that you could enable it with /proc/sys/kernel/ftrace_enabled ;-)
> always used dynamic ftrace, I've not > seen it until yesterday. (BTW I didn't tested with dynamic since this > patch). I had one other bug that made the set of > function tracer blocking during the write on current_trace with > dynamic ftrace. I will have a look on it.
Hmm, that could be a bug, but I do not know the details.
> > Actually one thing that makes me a bit confused is the use of these > two vars: ftrace_enabled and ftrace_disabled. > They are not used for the same purpose but their name suggest the same > role.... :-)
Well, the code documents it pretty well:
/* ftrace_enabled is a method to turn ftrace on or off */ int ftrace_enabled __read_mostly; static int last_ftrace_enabled;
/* * ftrace_disabled is set when an anomaly is discovered. * ftrace_disabled is much stronger than ftrace_enabled. */ static int ftrace_disabled __read_mostly;
-- Steve
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