linux-kernel - [PATCH 1/2] sched/rt: Add a helper to test for a RT task

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Date:   Wed,  4 Oct 2017 17:49:00 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>, Jens Axboe <axboe@...com>,
        tglx@...utronix.de,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 1/2] sched/rt: Add a helper to test for a RT task

This helper returns true if a task has elevated priority which is true
for RT tasks (SCHED_RR and SCHED_FIFO) and also for SCHED_DEADLINE.
A task which runs at RT priority due to PI-boosting is not considered as
one with elevated priority.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 include/linux/sched/rt.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/sched/rt.h b/include/linux/sched/rt.h
index f93329aba31a..30a86b8178f8 100644
--- a/include/linux/sched/rt.h
+++ b/include/linux/sched/rt.h
@@ -17,6 +17,17 @@ static inline int rt_task(struct task_struct *p)
 	return rt_prio(p->prio);
 }
 
+static inline bool task_is_elevated(struct task_struct *tsk)
+{
+	int policy = tsk->policy;
+
+	if (policy == SCHED_FIFO || policy == SCHED_RR)
+		return true;
+	if (policy == SCHED_DEADLINE)
+		return true;
+	return false;
+}
+
 #ifdef CONFIG_RT_MUTEXES
 /*
  * Must hold either p->pi_lock or task_rq(p)->lock.
-- 
2.14.2