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authorMike Galbraith <efault@gmx.de>2011-01-13 04:54:50 +0100
committerIngo Molnar <mingo@elte.hu>2011-01-18 15:09:42 +0100
commitf44937718ce3b8360f72f6c68c9481712517a867 (patch)
tree72b07f4daa686e10f90b666f5b61b66b30bbed2d
parent8ecedd7a06d27a31dbb36fab88e2ba6e6edd43ca (diff)
sched, autogroup: Fix CONFIG_RT_GROUP_SCHED sched_setscheduler() failure
If CONFIG_RT_GROUP_SCHED is set, __sched_setscheduler() fails due to autogroup not allocating rt_runtime. Free unused/unusable rt_se and rt_rq, redirect RT tasks to the root task group, and tell __sched_setscheduler() that it's ok. Reported-and-tested-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1294890890.8089.39.camel@marge.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/sched.c3
-rw-r--r--kernel/sched_autogroup.c27
-rw-r--r--kernel/sched_autogroup.h4
3 files changed, 33 insertions, 1 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index a0eb0941fa84..6cbff6bd1a60 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4871,7 +4871,8 @@ recheck:
* assigned.
*/
if (rt_bandwidth_enabled() && rt_policy(policy) &&
- task_group(p)->rt_bandwidth.rt_runtime == 0) {
+ task_group(p)->rt_bandwidth.rt_runtime == 0 &&
+ !task_group_is_autogroup(task_group(p))) {
__task_rq_unlock(rq);
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
return -EPERM;
diff --git a/kernel/sched_autogroup.c b/kernel/sched_autogroup.c
index 938d52f80a2d..9fb656283157 100644
--- a/kernel/sched_autogroup.c
+++ b/kernel/sched_autogroup.c
@@ -27,6 +27,11 @@ static inline void autogroup_destroy(struct kref *kref)
{
struct autogroup *ag = container_of(kref, struct autogroup, kref);
+#ifdef CONFIG_RT_GROUP_SCHED
+ /* We've redirected RT tasks to the root task group... */
+ ag->tg->rt_se = NULL;
+ ag->tg->rt_rq = NULL;
+#endif
sched_destroy_group(ag->tg);
}
@@ -55,6 +60,10 @@ static inline struct autogroup *autogroup_task_get(struct task_struct *p)
return ag;
}
+#ifdef CONFIG_RT_GROUP_SCHED
+static void free_rt_sched_group(struct task_group *tg);
+#endif
+
static inline struct autogroup *autogroup_create(void)
{
struct autogroup *ag = kzalloc(sizeof(*ag), GFP_KERNEL);
@@ -72,6 +81,19 @@ static inline struct autogroup *autogroup_create(void)
init_rwsem(&ag->lock);
ag->id = atomic_inc_return(&autogroup_seq_nr);
ag->tg = tg;
+#ifdef CONFIG_RT_GROUP_SCHED
+ /*
+ * Autogroup RT tasks are redirected to the root task group
+ * so we don't have to move tasks around upon policy change,
+ * or flail around trying to allocate bandwidth on the fly.
+ * A bandwidth exception in __sched_setscheduler() allows
+ * the policy change to proceed. Thereafter, task_group()
+ * returns &root_task_group, so zero bandwidth is required.
+ */
+ free_rt_sched_group(tg);
+ tg->rt_se = root_task_group.rt_se;
+ tg->rt_rq = root_task_group.rt_rq;
+#endif
tg->autogroup = ag;
return ag;
@@ -106,6 +128,11 @@ task_wants_autogroup(struct task_struct *p, struct task_group *tg)
return true;
}
+static inline bool task_group_is_autogroup(struct task_group *tg)
+{
+ return tg != &root_task_group && tg->autogroup;
+}
+
static inline struct task_group *
autogroup_task_group(struct task_struct *p, struct task_group *tg)
{
diff --git a/kernel/sched_autogroup.h b/kernel/sched_autogroup.h
index 5358e241cb20..7b859ffe5dad 100644
--- a/kernel/sched_autogroup.h
+++ b/kernel/sched_autogroup.h
@@ -15,6 +15,10 @@ autogroup_task_group(struct task_struct *p, struct task_group *tg);
static inline void autogroup_init(struct task_struct *init_task) { }
static inline void autogroup_free(struct task_group *tg) { }
+static inline bool task_group_is_autogroup(struct task_group *tg)
+{
+ return 0;
+}
static inline struct task_group *
autogroup_task_group(struct task_struct *p, struct task_group *tg)