From: Tom Zanussi <tom.zanussi@linux.intel.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 04/11] tracing: fix disabling of soft disable
Date: Fri, 21 Jun 2013 16:14:39 -0500 [thread overview]
Message-ID: <1371849279.6453.44.camel@empanada> (raw)
In-Reply-To: <1371847171.18733.128.camel@gandalf.local.home>
On Fri, 2013-06-21 at 16:39 -0400, Steven Rostedt wrote:
> On Fri, 2013-06-21 at 20:12 +0900, Masami Hiramatsu wrote:
> > (2013/06/21 3:31), Tom Zanussi wrote:
> > > The comment on the soft disable 'disable' case of
> > > __ftrace_event_enable_disable() states that the soft disable bit
> > > should be cleared in that case, but currently only the soft mode bit
> > > is actually cleared.
> > >
> > > This essentially leaves the standard non-soft-enable enable/disable
> > > paths as the only way to clear the soft disable flag, but the soft
> > > disable bit should also be cleared when removing a trigger with '!'.
> >
> > Indeed, the soft-disabled flag may remain after the event itself
> > disabled. However that soft-disabled flag will be cleared when
> > the event is re-enabled. it seems no bad side-effect.
> >
> > Thus I doubt this patch is separately required. I guess this is
> > required for adding new trigger flag, isn't it? :)
>
> Tom, I'm guessing Masami is correct here. It's needed for the trigger
> work to work, correct?
>
Well, the trigger should really work without this - this is basically
just a cleanup I added because it bothered me that I couldn't completely
revert the enable state back to the original state that existed before I
added the trigger (by reverting the trigger using '!'). It also just
seemed obviously correct from looking at the code as well (though I
agree, it's hard to keep the state machine of that function in your head
in order to prove it correct, and the straggling soft-disable state
hasn't bothered anyone until now, so maybe it's not worth it..)
In any case, if the SOFT_DISABLED bit is erroneously set but there are
no triggers, it shouldn't be a problem, since the trigger calls would
just return immediately, so not having this patch wouldn't break
anything...
Tom
> Either way, I probably could add it as a clean up patch regardless. I'll
> just have to test the hell out of it some more, as the accounting for
> soft-disable vs real disable was a PITA.
>
> -- Steve
>
next prev parent reply other threads:[~2013-06-21 21:14 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-20 18:31 [PATCH 00/11] tracing: trace event triggers Tom Zanussi
2013-06-20 18:31 ` [PATCH 01/11] tracing: simplify event_enable_read() Tom Zanussi
2013-06-21 6:52 ` Masami Hiramatsu
2013-06-20 18:31 ` [PATCH 02/11] tracing: add missing syscall_metadata comment Tom Zanussi
2013-06-21 7:06 ` Masami Hiramatsu
2013-06-21 19:48 ` Steven Rostedt
2013-06-20 18:31 ` [PATCH 03/11] tracing: add soft disable for syscall events Tom Zanussi
2013-06-21 6:53 ` zhangwei(Jovi)
2013-06-21 20:22 ` Steven Rostedt
2013-06-22 5:08 ` Jovi Zhang
2013-06-22 11:45 ` Steven Rostedt
2013-06-20 18:31 ` [PATCH 04/11] tracing: fix disabling of soft disable Tom Zanussi
2013-06-21 11:12 ` Masami Hiramatsu
2013-06-21 20:39 ` Steven Rostedt
2013-06-21 21:14 ` Tom Zanussi [this message]
2013-06-22 5:25 ` Tom Zanussi
2013-07-01 11:38 ` Masami Hiramatsu
2013-06-20 18:31 ` [PATCH 05/11] tracing: add basic event trigger framework Tom Zanussi
2013-06-21 12:12 ` Masami Hiramatsu
2013-06-20 18:31 ` [PATCH 06/11] tracing: add 'traceon' and 'traceoff' event trigger commands Tom Zanussi
2013-06-20 18:31 ` [PATCH 07/11] tracing: add 'snapshot' event trigger command Tom Zanussi
2013-06-20 18:31 ` [PATCH 08/11] tracing: add 'stacktrace' " Tom Zanussi
2013-06-20 18:31 ` [PATCH 09/11] tracing: add 'enable_event' and 'disable_event' event trigger commands Tom Zanussi
2013-06-20 18:31 ` [PATCH 10/11] tracing: add and use generic set_trigger_filter() implementation Tom Zanussi
2013-06-21 4:18 ` Masami Hiramatsu
2013-06-21 17:59 ` Tom Zanussi
2013-06-22 11:53 ` Steven Rostedt
2013-06-20 18:31 ` [PATCH 11/11] tracing: add documentation for trace event triggers Tom Zanussi
2013-06-21 19:45 ` [PATCH 00/11] tracing: " Steven Rostedt
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