From: Sebastian Andrzej Siewior 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/6.11/older/patches-6.11-rt7.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 --- 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 @@ -1814,6 +1814,7 @@ 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 @@ -7362,6 +7362,21 @@ static inline void preempt_dynamic_init( #endif /* 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; +} + int io_schedule_prepare(void) { int old_iowait = current->in_iowait;