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    SubjectRe: [BUG] ptraced process waiting on syscall may return kernel internal errnos
    > The freezer is crap... news at 11. Maybe a quick hack would be to let it
    > clear sigpending if tsk->mm == NULL but that's ugly. Note that there's
    > anything pretty about the freezer anyway...

    I think it might be made not too unreasonable by adding a TASK_FROZEN state.
    But I am still persuaded by my "hide in the corner" plan.

    > Well.. why was it _and_wake() in the first place anyway ? Or do I miss
    > something ? Why would we need to wake a thread for which we are removing
    > signals ?

    The bug was about a case where recalc_sigpending_tsk would set
    TIF_SIGPENDING when it hadn't been set before (wants_signal). It has
    nothing to do with the rm_from_queue_full being done there. It's just a
    violation of the necessary rule that when you set TIF_SIGPENDING on another
    thread you better call signal_wake_up on it.

    > What about something like:
    > do {
    > rm_from_queue_full(&mask, &t->pending);
    > - recalc_sigpending_and_wake(t);
    > t = next_thread(t);
    > } while (t != current);
    > + recalc_sigpending();

    There is no need for the +, just the -. The calling thread is the one
    where know there is certainly no perturbation of behavior due to leaving
    TIF_SIGPENDING set rather than clearing it. It's just going to exit the
    syscall and deal with signal state properly on the way out either way.
    Doing recalc_sigpending is an unnecessary optimization of the corner case.

    > So at the end of the day, easier to test it inside dequeue_signal().

    Before completely revamping the whole set of entrypoints to be saner all
    around, yes.

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      Last update: 2007-06-14 01:05    [W:0.020 / U:4.508 seconds]
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