On Wed, Jan 15, 2014 at 10:22:45AM +0100, Ingo Molnar wrote:
> 1)
>
> There's this change to __setscheduler():
>
> -__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
> +/* Actually do priority change: must hold pi & rq lock. */
> +static void __setscheduler(struct rq *rq, struct task_struct *p,
> + const struct sched_attr *attr)
> {
> + int policy = attr->sched_policy;
> +
> p->policy = policy;
> - p->rt_priority = prio;
> +
> + if (rt_policy(policy))
> + p->rt_priority = attr->sched_priority;
> + else
> + p->static_prio = NICE_TO_PRIO(attr->sched_nice);
> +
>
>
> doesnt this change keep p->rt_priority uninitialized in the
> normalize_task() case?
>
> I.e. rt_priority should still be set unconditionally. In the
> SCHED_NORMAL case that will be a zero initialization.
But why? SCHED_NORMAL doesn't care about rt_priority afaict. And once it
gets priority boosted we'll set the rt_priority again to whatever is
propagated from the pi-chain.
> 2)
>
> It's not clear why this change to __setscheduler() was done:
>
> /*
> * Allow unprivileged RT tasks to decrease priority:
> */
> if (user && !capable(CAP_SYS_NICE)) {
> + if (fair_policy(policy)) {
> + if (!can_nice(p, attr->sched_nice))
> + return -EPERM;
> + }
> +
> if (rt_policy(policy)) {o
Bah, I'm pretty sure I wrote that :/ And I can't for the life of me
remember why I did that. Complete fail there.
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