> Not sure. Suppose we call utrace_control(old, UTRACE_DETACH) right > before the tracee utrace_get_signal() calls ops->report_signal().
Then utrace_control() returns -EINPROGRESS. If it returned 0, then ops->report_signal will not be called. If that's not so, utrace_control is broken. > utrace_control()->get_utrace_lock() succeeds, but when utrace_control() > checks ->reporting it could be already cleared. If it's already cleared then that means that ops->report_signal has returned and its return value has been processed. If that's not so, utrace_control is broken. > > If it fails, then the old engine's callback has > > run or is starting to run, > > Yes, and we can't know (afaics) whether UTRACE_SIGNAL_DELIVER was > already returned or not. I don't follow. If utrace_control returned zero, then any callback has returned whatever it was going to return before the detach takes effect. If that's not so, utrace_control is broken. Thanks, Roland
