Re: [uml-devel] T-mode processes

[Michael Richardson <mcr@sandelman.ottawa.on.ca>]

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>>>>> "Henrik" == Henrik Nordstrom <uml@hno.marasystems.com> writes:
    >> It may well be, but it isn't acceptable.  What would break if
    >> kill-9 got rid of processes being PTRACE'ed?

    Henrik> This discussion probably is more related to lkml than uml..

  Sure.

    Henrik> For one thing the SIGKILL needs to be notified to and acted
    Henrik> upon by the tracing parent process before it is delivered to
    Henrik> the killed process. It is possible (and certainly so in case
    Henrik> of UML) that the tracing parent wants to do something
    Henrik> entirely different when a traced whild receives SIGKILL or
    Henrik> other terminal action.

  I can't see a use for this :-)

  At least, when the tracing process has gone away, then the SIGKILL
should take effect.

    Henrik> The actual question is why a process can be left in traced
    Henrik> state without any parent tracing it.. You'll see the same
    Henrik> symptoms if you strace a process and then kills strace. My
    Henrik> guess is that this is from the basic question on how to
    Henrik> determine what to do with the traced process when the
    Henrik> tracing parent disappears without telling what the future
    Henrik> fate of this process should be.. neither killing or
    Henrik> untracing the process is safe options.

    Henrik> Any way, sending a SIGCONT to the stopped process gets it
    Henrik> going again, or killed in case a SIGKILL or other terminal
    Henrik> action is pending.

  Our test bed produces a dozen of these every night.
  If someone has an idea on how to get better intel on this, I'm happy
to cooperate.

- --
]     "Elmo went to the wrong fundraiser" - The Simpson         |  firewalls  [
]   Michael Richardson,    Xelerance Corporation, Ottawa, ON    |net architect[
] mcr@xelerance.com      http://www.sandelman.ottawa.on.ca/mcr/ |device driver[
] panic("Just another Debian GNU/Linux using, kernel hacking, security guy"); [


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