sched/rt: Move RT related code from sched/core.c to sched/rt.c
This helps making sched/core.c smaller and hopefully easier to understand and maintain.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170621182203.30626-3-nicolas.pitre@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 581d5c7..45caf93 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2449,6 +2449,316 @@ const struct sched_class rt_sched_class = {
.update_curr = update_curr_rt,
};
+#ifdef CONFIG_RT_GROUP_SCHED
+/*
+ * Ensure that the real time constraints are schedulable.
+ */
+static DEFINE_MUTEX(rt_constraints_mutex);
+
+/* Must be called with tasklist_lock held */
+static inline int tg_has_rt_tasks(struct task_group *tg)
+{
+ struct task_struct *g, *p;
+
+ /*
+ * Autogroups do not have RT tasks; see autogroup_create().
+ */
+ if (task_group_is_autogroup(tg))
+ return 0;
+
+ for_each_process_thread(g, p) {
+ if (rt_task(p) && task_group(p) == tg)
+ return 1;
+ }
+
+ return 0;
+}
+
+struct rt_schedulable_data {
+ struct task_group *tg;
+ u64 rt_period;
+ u64 rt_runtime;
+};
+
+static int tg_rt_schedulable(struct task_group *tg, void *data)
+{
+ struct rt_schedulable_data *d = data;
+ struct task_group *child;
+ unsigned long total, sum = 0;
+ u64 period, runtime;
+
+ period = ktime_to_ns(tg->rt_bandwidth.rt_period);
+ runtime = tg->rt_bandwidth.rt_runtime;
+
+ if (tg == d->tg) {
+ period = d->rt_period;
+ runtime = d->rt_runtime;
+ }
+
+ /*
+ * Cannot have more runtime than the period.
+ */
+ if (runtime > period && runtime != RUNTIME_INF)
+ return -EINVAL;
+
+ /*
+ * Ensure we don't starve existing RT tasks.
+ */
+ if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
+ return -EBUSY;
+
+ total = to_ratio(period, runtime);
+
+ /*
+ * Nobody can have more than the global setting allows.
+ */
+ if (total > to_ratio(global_rt_period(), global_rt_runtime()))
+ return -EINVAL;
+
+ /*
+ * The sum of our children's runtime should not exceed our own.
+ */
+ list_for_each_entry_rcu(child, &tg->children, siblings) {
+ period = ktime_to_ns(child->rt_bandwidth.rt_period);
+ runtime = child->rt_bandwidth.rt_runtime;
+
+ if (child == d->tg) {
+ period = d->rt_period;
+ runtime = d->rt_runtime;
+ }
+
+ sum += to_ratio(period, runtime);
+ }
+
+ if (sum > total)
+ return -EINVAL;
+
+ return 0;
+}
+
+static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
+{
+ int ret;
+
+ struct rt_schedulable_data data = {
+ .tg = tg,
+ .rt_period = period,
+ .rt_runtime = runtime,
+ };
+
+ rcu_read_lock();
+ ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
+ rcu_read_unlock();
+
+ return ret;
+}
+
+static int tg_set_rt_bandwidth(struct task_group *tg,
+ u64 rt_period, u64 rt_runtime)
+{
+ int i, err = 0;
+
+ /*
+ * Disallowing the root group RT runtime is BAD, it would disallow the
+ * kernel creating (and or operating) RT threads.
+ */
+ if (tg == &root_task_group && rt_runtime == 0)
+ return -EINVAL;
+
+ /* No period doesn't make any sense. */
+ if (rt_period == 0)
+ return -EINVAL;
+
+ mutex_lock(&rt_constraints_mutex);
+ read_lock(&tasklist_lock);
+ err = __rt_schedulable(tg, rt_period, rt_runtime);
+ if (err)
+ goto unlock;
+
+ raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
+ tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
+ tg->rt_bandwidth.rt_runtime = rt_runtime;
+
+ for_each_possible_cpu(i) {
+ struct rt_rq *rt_rq = tg->rt_rq[i];
+
+ raw_spin_lock(&rt_rq->rt_runtime_lock);
+ rt_rq->rt_runtime = rt_runtime;
+ raw_spin_unlock(&rt_rq->rt_runtime_lock);
+ }
+ raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
+unlock:
+ read_unlock(&tasklist_lock);
+ mutex_unlock(&rt_constraints_mutex);
+
+ return err;
+}
+
+int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
+{
+ u64 rt_runtime, rt_period;
+
+ rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
+ rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
+ if (rt_runtime_us < 0)
+ rt_runtime = RUNTIME_INF;
+
+ return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
+}
+
+long sched_group_rt_runtime(struct task_group *tg)
+{
+ u64 rt_runtime_us;
+
+ if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
+ return -1;
+
+ rt_runtime_us = tg->rt_bandwidth.rt_runtime;
+ do_div(rt_runtime_us, NSEC_PER_USEC);
+ return rt_runtime_us;
+}
+
+int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
+{
+ u64 rt_runtime, rt_period;
+
+ rt_period = rt_period_us * NSEC_PER_USEC;
+ rt_runtime = tg->rt_bandwidth.rt_runtime;
+
+ return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
+}
+
+long sched_group_rt_period(struct task_group *tg)
+{
+ u64 rt_period_us;
+
+ rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
+ do_div(rt_period_us, NSEC_PER_USEC);
+ return rt_period_us;
+}
+
+static int sched_rt_global_constraints(void)
+{
+ int ret = 0;
+
+ mutex_lock(&rt_constraints_mutex);
+ read_lock(&tasklist_lock);
+ ret = __rt_schedulable(NULL, 0, 0);
+ read_unlock(&tasklist_lock);
+ mutex_unlock(&rt_constraints_mutex);
+
+ return ret;
+}
+
+int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
+{
+ /* Don't accept realtime tasks when there is no way for them to run */
+ if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
+ return 0;
+
+ return 1;
+}
+
+#else /* !CONFIG_RT_GROUP_SCHED */
+static int sched_rt_global_constraints(void)
+{
+ unsigned long flags;
+ int i;
+
+ raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
+ for_each_possible_cpu(i) {
+ struct rt_rq *rt_rq = &cpu_rq(i)->rt;
+
+ raw_spin_lock(&rt_rq->rt_runtime_lock);
+ rt_rq->rt_runtime = global_rt_runtime();
+ raw_spin_unlock(&rt_rq->rt_runtime_lock);
+ }
+ raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
+
+ return 0;
+}
+#endif /* CONFIG_RT_GROUP_SCHED */
+
+static int sched_rt_global_validate(void)
+{
+ if (sysctl_sched_rt_period <= 0)
+ return -EINVAL;
+
+ if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
+ (sysctl_sched_rt_runtime > sysctl_sched_rt_period))
+ return -EINVAL;
+
+ return 0;
+}
+
+static void sched_rt_do_global(void)
+{
+ def_rt_bandwidth.rt_runtime = global_rt_runtime();
+ def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
+}
+
+int sched_rt_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ int old_period, old_runtime;
+ static DEFINE_MUTEX(mutex);
+ int ret;
+
+ mutex_lock(&mutex);
+ old_period = sysctl_sched_rt_period;
+ old_runtime = sysctl_sched_rt_runtime;
+
+ ret = proc_dointvec(table, write, buffer, lenp, ppos);
+
+ if (!ret && write) {
+ ret = sched_rt_global_validate();
+ if (ret)
+ goto undo;
+
+ ret = sched_dl_global_validate();
+ if (ret)
+ goto undo;
+
+ ret = sched_rt_global_constraints();
+ if (ret)
+ goto undo;
+
+ sched_rt_do_global();
+ sched_dl_do_global();
+ }
+ if (0) {
+undo:
+ sysctl_sched_rt_period = old_period;
+ sysctl_sched_rt_runtime = old_runtime;
+ }
+ mutex_unlock(&mutex);
+
+ return ret;
+}
+
+int sched_rr_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ int ret;
+ static DEFINE_MUTEX(mutex);
+
+ mutex_lock(&mutex);
+ ret = proc_dointvec(table, write, buffer, lenp, ppos);
+ /*
+ * Make sure that internally we keep jiffies.
+ * Also, writing zero resets the timeslice to default:
+ */
+ if (!ret && write) {
+ sched_rr_timeslice =
+ sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
+ msecs_to_jiffies(sysctl_sched_rr_timeslice);
+ }
+ mutex_unlock(&mutex);
+ return ret;
+}
+
#ifdef CONFIG_SCHED_DEBUG
extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
