On Sat, Mar 01, 2014 at 07:18:38PM +0100, Juri Lelli wrote:
> From 73bae0ad978db6e75f492eea9adff12ec9d6d2a3 Mon Sep 17 00:00:00 2001
> From: Juri Lelli <juri.le...@gmail.com>
> Date: Sat, 1 Mar 2014 16:43:30 +0100
> Subject: [PATCH] sched/core: restore __setscheduler() behavior
>
> Commit c365c29 introduced __setscheduler_params(), that is now used
> to only store a task's new scheduling parameters in the case it is
> priority boosted.
>
> Before this change, __setscheduler() was in charge of changing tasks
> normal_prio and prio, and the latter is used to actually perform
> sched_class change. Unfortunately, the commit above broke this
> behavior, causing tasks to remain in fair_sched_class.
>
> Restore the old behaviour setting normal_prio and prio to the right
> values after the __setscheduler_params() call.
Please also add a Fixes: tag when appropriate, and add to Cc all those
two were involved with the original patch.
Fixes: c365c292d059 ("sched: Consider pi boosting in setscheduler()")
> Signed-off-by: Juri Lelli <juri.le...@gmail.com>
> ---
> kernel/sched/core.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index ee8004c..04ae20d 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3206,6 +3206,13 @@ static void __setscheduler(struct rq *rq, struct
> task_struct *p,
> {
> __setscheduler_params(p, attr);
>
> + /*
> + * Since we checked before with rt_mutex_check_prio(),
> + * we don't have pi waiters or our top waiter has lower
> + * priority (user space view) than what we got.
> + */
> + p->prio = p->normal_prio = normal_prio(p);
> +
> if (dl_prio(p->prio))
> p->sched_class = &dl_sched_class;
> else if (rt_prio(p->prio))
So there is one more caller of this: normalize_task() but since that is
only used to force set all tasks to SCHED_NORMAL ignoring the PI stuff
seems perfectly fine.
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