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    SubjectRe: [PATCH 03/10] ptrace: implement PTRACE_SEIZE
    Hello, Pedro.

    On Thu, May 26, 2011 at 11:01:42AM +0100, Pedro Alves wrote:
    > SYSGOOD makes sense, it just enables a means to distinguish syscall
    > SIGTRAPs from regular SIGTRAPs -- it doesn't cause child stops itself.
    > TRACE_EXEC, I'm not so sure. (and it appears to have been proposed
    > on the premise that SEIZE would still report the SIGTRAP).
    > Why would that make sense, and not TRACE_FORK, for example? I can imagine
    > a tracer only caring for syscall entry/exit, and not needing a special
    > event on exec. IMO, any kind of event that forces a child stop that
    > would't happen if the child wasn't traced should have to be enabled
    > explicitly.

    The problem with exec is that very weird things happen during exec.
    Tasks change their ids, tracees get silently pruned and so on, so
    there might not be a transparent way for a ptracer to deal with it.
    It needs to be notified and handle the situation whether it wants or
    not.

    What I was saying was there won't be SIGTRAP. In general, we're
    trying to move away from kernel implicitly sending actual signals. If
    we enable it by default, it will be a proper ptrace trap.

    Thanks.

    --
    tejun


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