> utrace_attach_task() checks ->exit_state == EXIT_DEAD. Why? I mean, > how can it help, we don't hold any locks, target can change its > ->exit_state right after the check.
Good catch, thanks. This is a remnant of the utrace-indirect code, where utrace_first_engine() had an interlock with reap/release_task. (It's one of the several ways that arrangement is superior IMNSHO.) > I don't understand why utrace_release_task() doesn't set ->reap = 1 > unconditionally. In that case we could use this flag instead of > EXIT_DEAD to verify it is "safe" to attach or get_utrace_lock(). That's what I've made it do now. In the utrace-indirect setup, it was possible to avoid locks for the common case (nobody attached). > static inline int utrace_attach_delay(struct task_struct *target) [...] This is the same thing Ananth noticed. It was an unintended holdover from the utrace-indirect code organization. It's fixed now. Thanks, Roland
