Re: [PATCH rt] Fix races in ptrace

[Alexander Fyodorov <halcy@yandex.ru>]

12.08.2013, 20:41, "Sebastian Andrzej Siewior" <bigeasy@linutronix.de>:
> * Alexander Fyodorov | 2013-07-24 20:23:27 [+0400]:
> Hi Alexander,

Hi Sebastian,

>> I ran into a race on 2.6.33-rt kernel which I think still exists in the latest RT patches. The following patch fixes it but it may be incomplete: probably spinlock should be taken in all other places that check saved_state too.  I only compile-tested this patch for 3.6-rt.
>
> It looks interresting, thanks for the report. Do you have maybe a
> test-case which can provoke the bug?

I can't publish the test but essentially it was doing the following: one process (application) has 20 threads sending signals to each other (creating contention for tasklist_lock and profiling events), and another one (profiler) attaches to the application and then does:
	for (;;) {
		pid = wait();
		ptrace(PTRACE_CONT, pid);
	}
Is there a need to write a test?
--
To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html