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sched, autogroup: Fix CONFIG_RT_GROUP_SCHED sched_setscheduler() failure

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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>
This commit is contained in:
Mike Galbraith 2011-01-13 04:54:50 +01:00 committed by Ingo Molnar
parent 8ecedd7a06
commit f44937718c
3 changed files with 33 additions and 1 deletions
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3
kernel/sched.c
View File

@ -4871,7 +4871,8 @@ static int __sched_setscheduler(struct task_struct *p, int policy,
* assigned. * assigned.
*/ */
if (rt_bandwidth_enabled() && rt_policy(policy) && 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); __task_rq_unlock(rq);
raw_spin_unlock_irqrestore(&p->pi_lock, flags); raw_spin_unlock_irqrestore(&p->pi_lock, flags);
return -EPERM; return -EPERM;

27
kernel/sched_autogroup.c
View File

@ -27,6 +27,11 @@ static inline void autogroup_destroy(struct kref *kref)
{ {
struct autogroup *ag = container_of(kref, struct autogroup, 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); sched_destroy_group(ag->tg);
} }
@ -55,6 +60,10 @@ static inline struct autogroup *autogroup_task_get(struct task_struct *p)
return ag; 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) static inline struct autogroup *autogroup_create(void)
{ {
struct autogroup *ag = kzalloc(sizeof(*ag), GFP_KERNEL); struct autogroup *ag = kzalloc(sizeof(*ag), GFP_KERNEL);
@ -72,6 +81,19 @@ static inline struct autogroup *autogroup_create(void)
init_rwsem(&ag->lock); init_rwsem(&ag->lock);
ag->id = atomic_inc_return(&autogroup_seq_nr); ag->id = atomic_inc_return(&autogroup_seq_nr);
ag->tg = tg; 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; tg->autogroup = ag;
return ag; return ag;
@ -106,6 +128,11 @@ task_wants_autogroup(struct task_struct *p, struct task_group *tg)
return true; 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 * static inline struct task_group *
autogroup_task_group(struct task_struct *p, struct task_group *tg) autogroup_task_group(struct task_struct *p, struct task_group *tg)
{ {

4
kernel/sched_autogroup.h
View File

@ -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_init(struct task_struct *init_task) { }
static inline void autogroup_free(struct task_group *tg) { } 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 * static inline struct task_group *
autogroup_task_group(struct task_struct *p, struct task_group *tg) autogroup_task_group(struct task_struct *p, struct task_group *tg)