[Devel] [PATCH 09/17] sched: add sched_boost_task helper

[Vladimir Davydov]

The helper is supposed to set the effective prio of a given task.
It will be used by the following patch.

In fact, we do not invent anything in this patch, because there is
rt_mutex_setprio, which already does the job. This patch only adds a new
wrapper.

Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
---
 include/linux/sched.h | 10 ++++++++++
 kernel/rtmutex.c      |  5 +++++
 kernel/sched/core.c   |  8 +++-----
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3bd2f50822b8..12dc066e0681 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2151,6 +2151,16 @@ extern int sched_setscheduler(struct task_struct *, int,
 			      const struct sched_param *);
 extern int sched_setscheduler_nocheck(struct task_struct *, int,
 				      const struct sched_param *);
+extern void __sched_boost_task(struct task_struct *p, int prio);
+static inline void sched_boost_task(struct task_struct *p, int prio)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&p->pi_lock, flags);
+	if (p->prio != prio)
+		__sched_boost_task(p, prio);
+	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+}
 extern struct task_struct *idle_task(int cpu);
 /**
  * is_idle_task - is the specified task an idle task?
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index 1e09308bf2a1..7776b0f17f8a 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -106,6 +106,11 @@ int rt_mutex_getprio(struct task_struct *task)
 		   task->normal_prio);
 }
 
+void rt_mutex_setprio(struct task_struct *p, int prio)
+{
+	__sched_boost_task(p, prio);
+}
+
 /*
  * Adjust the priority of a task, after its pi_waiters got modified.
  *
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 77d330cd2b79..85343cb3f269 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3978,10 +3978,8 @@ long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
 }
 EXPORT_SYMBOL(sleep_on_timeout);
 
-#ifdef CONFIG_RT_MUTEXES
-
 /*
- * rt_mutex_setprio - set the current priority of a task
+ * __sched_boot_task - set the current priority of a task
  * @p: task
  * @prio: prio value (kernel-internal form)
  *
@@ -3990,7 +3988,7 @@ EXPORT_SYMBOL(sleep_on_timeout);
  *
  * Used by the rt_mutex code to implement priority inheritance logic.
  */
-void rt_mutex_setprio(struct task_struct *p, int prio)
+void __sched_boost_task(struct task_struct *p, int prio)
 {
 	int oldprio, on_rq, running;
 	struct rq *rq;
@@ -4044,7 +4042,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
 out_unlock:
 	__task_rq_unlock(rq);
 }
-#endif
+
 void set_user_nice(struct task_struct *p, long nice)
 {
 	int old_prio, delta, on_rq;
-- 
2.1.4