Re: PATCH? trace_remove_event_call() should fail if call is active

From: Steven Rostedt
Date: Wed Jul 03 2013 - 14:02:35 EST


On Wed, 2013-07-03 at 19:54 +0200, Oleg Nesterov wrote:
> On 07/03, Oleg Nesterov wrote:
> >
> > IOW. So far _I think_ we just need the additional changes in
> > trace_remove_event_call() if it succeeds (with the patch I sent)
> > to prevent the races like above, but I didn't even try to think
> > about this problem.
>
> And I guess greatly underestimated the problem(s). When I look at
> this code now, it seems that, say, event_enable_write() will use
> the already freed ftrace_event_file in this case.
>
> Still I think this is another (although closely related) problem.

Correct, and I think if we fix that problem, it will encapsulate fixing
the kprobe race too.

-- Steve


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