Re: [RFC][PATCH 3/4] tracing/kprobes: Fail to unregister if probeevent files are open

From: Oleg Nesterov
Date: Thu Aug 01 2013 - 09:16:41 EST

On 07/31, Steven Rostedt wrote:
> On Wed, 2013-07-31 at 22:40 +0200, Oleg Nesterov wrote:
> >
> > This should be fine. Either event_remove() path takes event_mutex
> > first and then ->write() fails, or ftrace_event_enable_disable()
> > actually disables this even successfully.
> Actually I meant while in unregister_trace_probe(), it gets by the
> trace_probe_is_enabled() part first, then the write succeeds (as the
> event_mutex isn't taken till unregister_probe_event()). The the
> unregister_probe_event fails,

Yes sure. In this case evrything is clear. But this looks as if
unregister_probe_event() should not fail. IOW, this looks as if
the bug was introduce by the previous "trace_remove_event_call()
should fail if call/file is in use" change.


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