> Can't understand why do we need TIF_SINGLE_STEP at all. I think you mean "why we need to set it in do_signal" here, not "why do we need it to exist at all". > Just pass current->thread.per_info.single_step to > tracehook_signal_handler() ? Yes. I believe this is what Martin meant, and it's what I meant to endorse. do_signal should not do anything with TIF_SINGLE_STEP at all. Its only purpose should be to communicate from the low-level trap assembly code up to the return-to-user assembly code so it calls do_single_step. Thanks, Roland -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html