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> > > > > + /* > > > > > + * Since this is called after changing class, this isn't quite right. > > > > > + * Specifically, this causes the task to get queued in the target class > > > > > + * and experience a 'spurious' wakeup. > > > > > + * > > > > > + * However, since 'spurious' wakeups are harmless, this shouldn't be a > > > > > + * problem. > > > > > + */ > > > > > + p->se.sched_delayed = 0; > > > > > + /* > > > > > + * While here, also clear the vlag, it makes little sense to carry that > > > > > + * over the excursion into the new class. > > > > > + */ > > > > > + p->se.vlag = 0; > > > > > > > > RQ lock is held, the task can't be current if it's ->sched_delayed; is a > > > > dequeue_task() not possible at this point? Or just not worth it? > > > > > > Hurmph, I really can't remember why I did it like this :-( > > > > Obviously I remember it right after hitting send... > > > > We've just done: > > > > dequeue_task(); > > p->sched_class = some_other_class; > > enqueue_task(); > > > > IOW, we're enqueued as some other class at this point. There is no way > > we can fix it up at this point. > > With just a little more sleep than last night, perhaps you're right > after all. Yes we're on a different class, but we can *still* dequeue it > again. Not quite get this. If the old class is cfs, the task is in a rb-tree. And if the new class is rt then the task is in the prio list. Just wonder would the rt.dequeue break the data of rb-tree? thanks, Chenyu