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authorDhaval Giani <dhaval@linux.vnet.ibm.com>2008-02-28 15:21:56 +0530
committerIngo Molnar <mingo@elte.hu>2008-03-07 16:43:00 +0100
commit521f1a2489c41f8b1181b0a8eb52e1c34284d50b (patch)
treecfe339df98dcb65aaae6c45021ac92cdf60c6540 /kernel
parent2692a2406b9262bbb101708815be99ec2988e48b (diff)
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index b8ee864c7481..52b98675acb2 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7750,6 +7750,17 @@ static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
return total + to_ratio(period, runtime) < global_ratio;
}
+/* Must be called with tasklist_lock held */
+static inline int tg_has_rt_tasks(struct task_group *tg)
+{
+ struct task_struct *g, *p;
+ do_each_thread(g, p) {
+ if (rt_task(p) && rt_rq_of_se(&p->rt)->tg == tg)
+ return 1;
+ } while_each_thread(g, p);
+ return 0;
+}
+
int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
{
u64 rt_runtime, rt_period;
@@ -7761,12 +7772,18 @@ int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
rt_runtime = RUNTIME_INF;
mutex_lock(&rt_constraints_mutex);
+ read_lock(&tasklist_lock);
+ if (rt_runtime_us == 0 && tg_has_rt_tasks(tg)) {
+ err = -EBUSY;
+ goto unlock;
+ }
if (!__rt_schedulable(tg, rt_period, rt_runtime)) {
err = -EINVAL;
goto unlock;
}
tg->rt_runtime = rt_runtime;
unlock:
+ read_unlock(&tasklist_lock);
mutex_unlock(&rt_constraints_mutex);
return err;

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