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authorDhaval Giani <dhaval@linux.vnet.ibm.com>2008-02-28 04:51:56 -0500
committerIngo Molnar <mingo@elte.hu>2008-03-07 10:43:00 -0500
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)
7750 return total + to_ratio(period, runtime) < global_ratio; 7750 return total + to_ratio(period, runtime) < global_ratio;
7751} 7751}
7752 7752
7753/* Must be called with tasklist_lock held */
7754static inline int tg_has_rt_tasks(struct task_group *tg)
7755{
7756 struct task_struct *g, *p;
7757 do_each_thread(g, p) {
7758 if (rt_task(p) && rt_rq_of_se(&p->rt)->tg == tg)
7759 return 1;
7760 } while_each_thread(g, p);
7761 return 0;
7762}
7763
7753int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us) 7764int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
7754{ 7765{
7755 u64 rt_runtime, rt_period; 7766 u64 rt_runtime, rt_period;
@@ -7761,12 +7772,18 @@ int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
7761 rt_runtime = RUNTIME_INF; 7772 rt_runtime = RUNTIME_INF;
7762 7773
7763 mutex_lock(&rt_constraints_mutex); 7774 mutex_lock(&rt_constraints_mutex);
7775 read_lock(&tasklist_lock);
7776 if (rt_runtime_us == 0 && tg_has_rt_tasks(tg)) {
7777 err = -EBUSY;
7778 goto unlock;
7779 }
7764 if (!__rt_schedulable(tg, rt_period, rt_runtime)) { 7780 if (!__rt_schedulable(tg, rt_period, rt_runtime)) {
7765 err = -EINVAL; 7781 err = -EINVAL;
7766 goto unlock; 7782 goto unlock;
7767 } 7783 }
7768 tg->rt_runtime = rt_runtime; 7784 tg->rt_runtime = rt_runtime;
7769 unlock: 7785 unlock:
7786 read_unlock(&tasklist_lock);
7770 mutex_unlock(&rt_constraints_mutex); 7787 mutex_unlock(&rt_constraints_mutex);
7771 7788
7772 return err; 7789 return err;