Messages in this thread | | | Date | Mon, 27 Jun 2011 15:47:13 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] ptrace: make former thread ID available via PTRACE_GETEVENTMSG after PTRACE_EVENT_EXEC stop (v.2) |
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On 06/27, Tejun Heo wrote: > > Hello, Oleg, Denys. > > On Sun, Jun 26, 2011 at 10:04:42PM +0200, Oleg Nesterov wrote: > > May be PT_TRACE_EXEC makes more sense. Note that > > ptrace_event_enabled() was recently added. > > Do we want to enable this silently? Wouldn't it be better to make it > dependent on PT_SEIZED?
Hmm. Not sure I understand. Why can't PTRACE_SEIZE add PT_TRACE_EXEC (and PT_TRACESYSGOOD) along with PT_SEIZED during attach?
I think this makes more sense, this way the tracer can disable this later via PTRACE_SETOPTIONS if it wants. Not that I think this is really useful but still. Otherwise we are going to silently disable PTRACE_O_TRACEEXEC, this may be confusing.
But. If we want the PT_TRACE_EXEC behaviour for PT_SEIZED task (personally I think we do), then we should probably record the old pid unconditionally, the tracer can attach later.
Even in this case ptrace_event(PTRACE_EVENT_EXEC) can race with detach + attach in theory, but I think in this case we do not care.
Oleg.
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