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sched: don't allow rt_runtime_us to be zero for groups having rt tasks
This patch checks if we can set the rt_runtime_us to 0. If there is a realtime task in the group, we don't want to set the rt_runtime_us as 0 or bad things will happen. (that task wont get any CPU time despite being TASK_RUNNNG) Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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2692a2406b
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521f1a2489
1 changed files with 17 additions and 0 deletions
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@ -7750,6 +7750,17 @@ static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
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return total + to_ratio(period, runtime) < global_ratio;
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}
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/* Must be called with tasklist_lock held */
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static inline int tg_has_rt_tasks(struct task_group *tg)
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{
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struct task_struct *g, *p;
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do_each_thread(g, p) {
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if (rt_task(p) && rt_rq_of_se(&p->rt)->tg == tg)
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return 1;
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} while_each_thread(g, p);
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return 0;
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}
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int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
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{
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u64 rt_runtime, rt_period;
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@ -7761,12 +7772,18 @@ int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
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rt_runtime = RUNTIME_INF;
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mutex_lock(&rt_constraints_mutex);
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read_lock(&tasklist_lock);
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if (rt_runtime_us == 0 && tg_has_rt_tasks(tg)) {
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err = -EBUSY;
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goto unlock;
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}
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if (!__rt_schedulable(tg, rt_period, rt_runtime)) {
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err = -EINVAL;
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goto unlock;
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}
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tg->rt_runtime = rt_runtime;
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unlock:
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read_unlock(&tasklist_lock);
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mutex_unlock(&rt_constraints_mutex);
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return err;
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