> I was worried about the case when the TIF_SINGLESTEP tracee detaches > itself and escapes finish_resume_report()->user_disable_single_step(), > say, utrace_report_exec(). But probably we can ignore this.
No, I think that is indeed a problem. If no engine is still attached whose last callback returned UTRACE_SINGLESTEP, we should never return to user mode with single-step enabled. > Another concern was implicit detach, but thinking more I do not see > why utrace_resume() is better. > > OK, I'll do some testing and resend right now. In UTRACE_DETACH case > reset can be true but the tracee is running. But I don't think it > makes sense to check target->exit_state == 0, correct? I think it's OK if it's running with ->exit_state set (or even with just PF_EXITING set), i.e. already in kernel mode and never going back to user mode. (Then it's essentially equivalent to calling user_*_step while racing with a SIGKILL death, which has to be OK.) Any other kind of running would not be OK. Thanks, Roland
