Messages in this thread | | | From | Pedro Alves <> | Subject | Re: execve-under-ptrace API bug (was Re: Ptrace documentation, draft #3) | Date | Thu, 2 Jun 2011 11:57:12 +0100 |
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On Tuesday 31 May 2011 14:51:16, Oleg Nesterov wrote:
> The main problem is: it is not clear do we really want EVENT_EXIT > in this case. I think we do, Roland thought we do not. OTOH I never > really the purpose of EVENT_EXIT, but this doesn't matter. > > If we decide we do want this notification (in this case), then we > need fixes. EVENT_EXIT is not reliable. Say, the thread can exit > before it dequeues SIGKILL and in this case it doesn't stop. > Also. If we guarantee EVENT_EXIT in this case, then probably the > implicit SIGKILL should not wakeup the TASK_TRACED tracee (except > the new PTRACE_LISTEN case). > > In short: currently I do not know what should be documented. I do > not know the original intent, I can only see what the code actually > does.
Daniel Jacobowitz said when he submitted it:
<http://lkml.indiana.edu/hypermail/linux/kernel/0302.0/1051.html>
"PTRACE_EVENT_EXIT, which triggers in do_exit(). This is useful to quickly find out where a program is making an exit syscall from, etc. - it triggers before the mm is released, so we can still get backtraces et cetera."
That said, GDB was never made to use it:
/* Do not enable PTRACE_O_TRACEEXIT until GDB is more prepared to support read-only process state. */
-- Pedro Alves
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