linux-kernel - Question about prio_changed

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Message-ID: <20160219134345.70ff4aa0@utopia>
Date:	Fri, 19 Feb 2016 13:43:45 +0100
From:	luca abeni <luca.abeni@...tn.it>
To:	Juri Lelli <juri.lelli@....com>, linux-kernel@...r.kernel.org
Cc:	Peter Zijlstra <peterz@...radead.org>
Subject: Question about prio_changed_dl()

Hi,

when playing with the __dl_{add,sub}_ac() stuff recently posted by
Juri, I found something that looks strange in prio_changed_dl():

static void prio_changed_dl(struct rq *rq, struct task_struct *p,
			    int oldprio)
{
	if (task_on_rq_queued(p) || rq->curr == p) {
		[...]
	} else
		switched_to_dl(rq, p);
}
but switched_to_dl() does:
static void switched_to_dl(struct rq *rq, struct task_struct *p)
{
	if (task_on_rq_queued(p) && rq->curr != p) {
		[...]
	}
}

so, prio_changed_dl() invokes switched_to_dl() if task_on_rq_queued()
is false, but in this case switched_to_dl() does nothing... Am I
missing something, or the
	} else
		switched_to_dl(rq, p);
is useless?
(BTW, it seems to me that switched_to_dl() is never invoked, for some
reason...)


			Thanks,
				Luca

If you wonder how this is related to __dl_{add,sub}_ac(), I am going to
write an email about it in a short time :)