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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2008-09-23 15:33:44 +0200
committerIngo Molnar <mingo@elte.hu>2008-09-23 16:23:16 +0200
commit4653f803e6e0d970ffeac0efd2c01743eb6c5228 (patch)
tree5de138ab4aa31c2df68062209f0b166a94739843 /kernel/sched.c
parent78333cdd0e472180743d35988e576d6ecc6f6ddb (diff)
sched: more sanity checks on the bandwidth settings
While playing around with it, I noticed we missed some sanity checks. Also add some comments while we're there. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c33
1 files changed, 28 insertions, 5 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 669c49aa57f..e1299de1765 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -8866,11 +8866,29 @@ static int tg_schedulable(struct task_group *tg, void *data)
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;
@@ -8978,19 +8996,24 @@ long sched_group_rt_period(struct task_group *tg)
static int sched_rt_global_constraints(void)
{
- struct task_group *tg = &root_task_group;
- u64 rt_runtime, rt_period;
+ u64 runtime, period;
int ret = 0;
if (sysctl_sched_rt_period <= 0)
return -EINVAL;
- rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
- rt_runtime = tg->rt_bandwidth.rt_runtime;
+ runtime = global_rt_runtime();
+ period = global_rt_period();
+
+ /*
+ * Sanity check on the sysctl variables.
+ */
+ if (runtime > period && runtime != RUNTIME_INF)
+ return -EINVAL;
mutex_lock(&rt_constraints_mutex);
read_lock(&tasklist_lock);
- ret = __rt_schedulable(tg, rt_period, rt_runtime);
+ ret = __rt_schedulable(NULL, 0, 0);
read_unlock(&tasklist_lock);
mutex_unlock(&rt_constraints_mutex);