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Date:   Thu, 30 Sep 2021 20:33:16 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc:     Intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org,
        Tvrtko Ursulin <tvrtko.ursulin@intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>
Subject: Re: [RFC 1/6] sched: Add nice value change notifier
Message-ID: <20210930183316.GC4323@worktop.programming.kicks-ass.net>
References: <20210930171552.501553-1-tvrtko.ursulin@linux.intel.com>
 <20210930171552.501553-2-tvrtko.ursulin@linux.intel.com>
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In-Reply-To: <20210930171552.501553-2-tvrtko.ursulin@linux.intel.com>
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On Thu, Sep 30, 2021 at 06:15:47PM +0100, Tvrtko Ursulin wrote:
>  void set_user_nice(struct task_struct *p, long nice)
>  {
>  	bool queued, running;
> -	int old_prio;
> +	int old_prio, ret;
>  	struct rq_flags rf;
>  	struct rq *rq;
>  
> @@ -6913,6 +6945,9 @@ void set_user_nice(struct task_struct *p, long nice)
>  	 */
>  	p->sched_class->prio_changed(rq, p, old_prio);
>  
> +	ret = atomic_notifier_call_chain(&user_nice_notifier_list, nice, p);
> +	WARN_ON_ONCE(ret != NOTIFY_DONE);
> +
>  out_unlock:
>  	task_rq_unlock(rq, p, &rf);
>  }

No, we're not going to call out to exported, and potentially unbounded,
functions under scheduler locks.