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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 4 Aug 2023 13:30:37 +0200
Subject: [PATCH 1/3] sched/core: Provide a method to check if a task is
PI-boosted.
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.9/older/patches-6.9-rt5.tar.xz
Provide a method to check if a task inherited the priority from another
task. This happens if a task owns a lock which is requested by a task
with higher priority. This can be used as a hint to add a preemption
point to the critical section.
Provide a function which reports true if the task is PI-boosted.
Link: https://lore.kernel.org/r/20230804113039.419794-2-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/sched.h | 1 +
kernel/sched/core.c | 15 +++++++++++++++
2 files changed, 16 insertions(+)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1795,6 +1795,7 @@ static inline int dl_task_check_affinity
}
#endif
+extern bool task_is_pi_boosted(const struct task_struct *p);
extern int yield_to(struct task_struct *p, bool preempt);
extern void set_user_nice(struct task_struct *p, long nice);
extern int task_prio(const struct task_struct *p);
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8911,6 +8911,21 @@ static inline void preempt_dynamic_init(
#endif /* #ifdef CONFIG_PREEMPT_DYNAMIC */
+/*
+ * task_is_pi_boosted - Check if task has been PI boosted.
+ * @p: Task to check.
+ *
+ * Return true if task is subject to priority inheritance.
+ */
+bool task_is_pi_boosted(const struct task_struct *p)
+{
+ int prio = p->prio;
+
+ if (!rt_prio(prio))
+ return false;
+ return prio != p->normal_prio;
+}
+
/**
* yield - yield the current processor to other threads.
*
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