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Calling ops.running() for such a donor produces a spurious running event. Simply suppressing ops.running() is not sufficient because the following put_prev_task_scx() would still invoke ops.stopping(), resulting in an unpaired stopping event. Introduce SCX_TASK_IS_RUNNING to track whether a task entered a real running transition. Set and clear the flag independently of ops.running() and ops.stopping(), as the callbacks are independently optional. Invoke ops.running() only for non-blocked tasks and invoke ops.stopping() only after a real running transition. This keeps the callbacks paired for proxy donors while preserving stopping notifications for schedulers which only implement ops.stopping(). Signed-off-by: Andrea Righi --- include/linux/sched/ext.h | 2 ++ kernel/sched/ext/ext.c | 33 +++++++++++++++++++++++++-------- 2 files changed, 27 insertions(+), 8 deletions(-) diff --git a/include/linux/sched/ext.h b/include/linux/sched/ext.h index 75cb8b119fb79..c6f58e1a66cdb 100644 --- a/include/linux/sched/ext.h +++ b/include/linux/sched/ext.h @@ -102,6 +102,8 @@ enum scx_ent_flags { SCX_TASK_SUB_INIT = 1 << 4, /* task being initialized for a sub sched */ SCX_TASK_IMMED = 1 << 5, /* task is on local DSQ with %SCX_ENQ_IMMED */ + SCX_TASK_IS_RUNNING = 1 << 6, /* entered a real running transition */ + /* * Bits 8 to 10 are used to carry task state: * diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index e7cf88b2be7f6..85e07cbe626f6 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -1985,9 +1985,13 @@ static bool dequeue_task_scx(struct rq *rq, struct task_struct *p, int core_deq_ * information meaningful to the BPF scheduler and can be suppressed by * skipping the callbacks if the task is !QUEUED. */ - if (SCX_HAS_OP(sch, stopping) && task_current(rq, p)) { - update_curr_scx(rq); - SCX_CALL_OP_TASK(sch, stopping, rq, p, false); + if (task_current(rq, p) && + (p->scx.flags & SCX_TASK_IS_RUNNING)) { + if (SCX_HAS_OP(sch, stopping)) { + update_curr_scx(rq); + SCX_CALL_OP_TASK(sch, stopping, rq, p, false); + } + p->scx.flags &= ~SCX_TASK_IS_RUNNING; } if (SCX_HAS_OP(sch, quiescent) && !task_on_rq_migrating(p)) @@ -2743,9 +2747,17 @@ static void set_next_task_scx(struct rq *rq, struct task_struct *p, bool first) p->se.exec_start = rq_clock_task(rq); - /* see dequeue_task_scx() on why we skip when !QUEUED */ - if (SCX_HAS_OP(sch, running) && (p->scx.flags & SCX_TASK_QUEUED)) - SCX_CALL_OP_TASK(sch, running, rq, p); + /* + * See dequeue_task_scx() for why we skip when !QUEUED. A blocked proxy + * donor is also skipped because it provides scheduling context but never + * runs itself. + */ + if ((p->scx.flags & SCX_TASK_QUEUED) && !task_is_blocked(p)) { + if (SCX_HAS_OP(sch, running)) + SCX_CALL_OP_TASK(sch, running, rq, p); + + p->scx.flags |= SCX_TASK_IS_RUNNING; + } clr_task_runnable(p, true); @@ -2834,8 +2846,13 @@ static void put_prev_task_scx(struct rq *rq, struct task_struct *p, update_curr_scx(rq); /* see dequeue_task_scx() on why we skip when !QUEUED */ - if (SCX_HAS_OP(sch, stopping) && (p->scx.flags & SCX_TASK_QUEUED)) - SCX_CALL_OP_TASK(sch, stopping, rq, p, true); + if ((p->scx.flags & SCX_TASK_QUEUED) && + (p->scx.flags & SCX_TASK_IS_RUNNING)) { + if (SCX_HAS_OP(sch, stopping)) + SCX_CALL_OP_TASK(sch, stopping, rq, p, true); + + p->scx.flags &= ~SCX_TASK_IS_RUNNING; + } if (p->scx.flags & SCX_TASK_QUEUED) { set_task_runnable(rq, p); -- 2.55.0