task_dead_and_done(9)

💖 NAME 💖

ok so this is task_dead_and_done from the Kernel API Manual (section 9, bestie, the kernel one) — it's the little bool that answers the question "is this task dead and done running?" 🫶

---

✨ SYNOPSIS ✨

bool task_dead_and_done (struct task_struct *p );

---

🎀 ARGUMENTS 🎀

• p — the target task 👑 that's the one you're asking about, no cap

---

🦋 DESCRIPTION 🦋

okay so picture this: once sched_ext_dead removes the dead task from scx_tasks and exits it, that task literally does not exist from SCX's POV anymore. gone. ghosted. 💀

but here's the messy part — certain sched_class ops can still get invoked on these dead tasks, and that leads to failures. like, for real, e.g. sched_setscheduler may try to switch a task which finished sched_ext_dead back into SCX, and that triggers invalid SCX task state transitions and worse. 😭 worse!! we don't want worse!!

so once a task has finished the final switch, sched_ext_dead is the only thing that needs to happen on the task. periodt. 💅

use this test to short-circuit sched_class operations which may be called on dead tasks 🧚 that's the whole vibe check: dead + done? then skip the op, bestie.

---

🌈 SEE ALSO 🌈

this list is long long, but every single one of these is part of the family, so here we go — also peep the kernel file ./kernel/sched/ext/ext.c 🍓:

scx_is_descendant(9), rq_is_open(9), scx_fill_cmask_scratch(9), scx_call_op_set_cpumask(9), nldsq_next_task(9), nldsq_cursor_next_task(9), nldsq_cursor_lost_task(9), scx_task_iter_start(9), scx_task_iter_unlock(9), scx_task_iter_relock(9), scx_task_iter_stop(9), scx_task_iter_next(9), scx_task_iter_next_locked(9), scx_dump_event(9), wait_ops_state(9), scx_cpu_valid(9), schedule_deferred(9), schedule_deferred_locked(9), dsq_insert_head(9), set_task_slice_keep_oob(9), scx_task_slice_ended(9), move_remote_task_to_local_dsq(9), unlink_dsq_and_switch_rq_lock(9), move_task_between_dsqs(9), dispatch_to_local_dsq(9), finish_dispatch(9), scx_prio_less(9), __scx_init_task(9), scx_tg_sched(9), scx_tg_knob_sched(9), handle_lockup(9), scx_rcu_cpu_stall(9), scx_softlockup(9), scx_hardlockup(9), unbypass_renotify_idle(9), scx_bypass(9), scx_propagate_exit_irq_workfn(9), scx_flush_disable_work(9), print_scx_info(9), scx_bpf_dsq_insert___v2(9), __scx_bpf_dsq_insert_vtime(9), scx_bpf_dispatch_nr_slots(9), scx_bpf_dispatch_cancel(9), scx_bpf_dsq_move_to_local___v2(9), scx_bpf_dsq_move_set_slice(9), scx_bpf_dsq_move_set_vtime(9), scx_bpf_dsq_move(9), scx_bpf_dsq_move_vtime(9), scx_bpf_reenqueue_local(9), scx_bpf_create_dsq(9), scx_bpf_task_set_slice(9), scx_bpf_task_set_dsq_vtime(9), scx_bpf_kick_cpu(9), scx_bpf_kick_cid(9), scx_bpf_dsq_nr_queued(9), scx_bpf_destroy_dsq(9), bpf_iter_scx_dsq_new(9), bpf_iter_scx_dsq_next(9), bpf_iter_scx_dsq_destroy(9), scx_bpf_dsq_peek(9), scx_bpf_dsq_reenq(9), scx_bpf_reenqueue_local___v2(9), scx_bpf_exit_bstr(9), scx_bpf_error_bstr(9), scx_bpf_dump_bstr(9), scx_bpf_cpuperf_cap(9), scx_bpf_cidperf_cap(9), scx_bpf_cpuperf_cur(9), scx_bpf_cidperf_cur(9), scx_bpf_cpuperf_set(9), scx_bpf_cidperf_set(9), scx_bpf_nr_node_ids(9), scx_bpf_nr_cpu_ids(9), scx_bpf_nr_cids(9), scx_bpf_nr_online_cids(9), scx_bpf_online_cmask(9), scx_bpf_this_cid(9), scx_bpf_get_possible_cpumask(9), scx_bpf_get_online_cpumask(9), scx_bpf_put_cpumask(9), scx_bpf_task_running(9), scx_bpf_task_cpu(9), scx_bpf_task_cid(9), scx_bpf_locked_rq(9), scx_bpf_cpu_curr(9), scx_bpf_cid_curr(9), scx_bpf_tid_to_task(9), scx_bpf_now(9), scx_bpf_events(9), scx_bpf_task_cgroup(9)

---

🌸 the cute sign-off 🌸

this whole page lives in ./kernel/sched/ext, it's dated October 2026, and it's filed under task_dead_and_done(9) — mwah, go check if your task is dead and done before you touch it, ily, bye! 💜🎀✨