Messages in this thread | | | Date | Wed, 29 Oct 2008 02:09:23 +0100 | From | "Frédéric Weisbecker" <> | Subject | Re: [PATCH] ftrace: fix current_tracer error return |
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2008/10/29 Steven Rostedt <rostedt@goodmis.org>: > > 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 ;-)
Ah ok. I better understand now. But IMHO I guess that would better for developpers who will use it to have something directly enabled whithout touching this file at each start.
> >> 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;
Oops... I missed it.
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