Messages in this thread Patch in this message | | | From | Song Chen <> | Subject | [PATCH] kernel/sched/core: adjust rt_priority accordingly when prio is changed | Date | Wed, 1 Feb 2023 18:01:20 +0800 |
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When a high priority process is acquiring a rtmutex which is held by a low priority process, the latter's priority will be boosted up by calling rt_mutex_setprio->__setscheduler_prio.
However, p->prio is changed but p->rt_priority is not, as a result, the equation between prio and rt_priority is broken, which is:
prio = MAX_RT_PRIO - 1 - rt_priority
It's confusing to the user when it calls sched_getparam, which only returns rt_priority.
This patch addresses this issue by adjusting rt_priority according to the new value of prio, what's more, it also returns normal_prio for CFS processes instead of just a zero.
Signed-off-by: Song Chen <chensong_2000@189.cn> --- kernel/sched/core.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index bb1ee6d7bdde..1c2c4ada08cc 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6933,14 +6933,16 @@ EXPORT_SYMBOL(default_wake_function); static void __setscheduler_prio(struct task_struct *p, int prio) { + p->prio = prio; + if (dl_prio(prio)) p->sched_class = &dl_sched_class; - else if (rt_prio(prio)) + else if (rt_prio(prio)) { + p->rt_priority = MAX_RT_PRIO - 1 - prio; p->sched_class = &rt_sched_class; + } else p->sched_class = &fair_sched_class; - - p->prio = prio; } #ifdef CONFIG_RT_MUTEXES @@ -8058,6 +8060,8 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) if (task_has_rt_policy(p)) lp.sched_priority = p->rt_priority; + else + lp.sched_priority = normal_prio(p); rcu_read_unlock(); /* -- 2.25.1
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