[tip:sched/core] sched/rt: Add a helper to test for a RT task

[tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com>]

Commit-ID:  ff0d4a9dc16b1f4c954f6407c233ab848bdfe8b0
Gitweb:     https://git.kernel.org/tip/ff0d4a9dc16b1f4c954f6407c233ab848bdfe8b0
Author:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Wed, 4 Oct 2017 17:49:00 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 10 Oct 2017 11:45:38 +0200

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@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jens Axboe <axboe@fb.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171004154901.26904-1-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 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 f93329a..1330016 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_realtime(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.