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Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: Prevent compiler from optimising the sched_avg_update() loop
  sched: Fix over-scheduling bug
  sched: Fix PROVE_RCU vs cpu_cgroup
This commit is contained in:
Linus Torvalds 2010-06-28 12:18:30 -07:00
commit f014d937d6
2 changed files with 79 additions and 65 deletions
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20
include/linux/cgroup.h
View File

@ -525,13 +525,21 @@ static inline struct cgroup_subsys_state *cgroup_subsys_state(
return cgrp->subsys[subsys_id];
}
static inline struct cgroup_subsys_state *task_subsys_state(
struct task_struct *task, int subsys_id)
/*
* function to get the cgroup_subsys_state which allows for extra
* rcu_dereference_check() conditions, such as locks used during the
* cgroup_subsys::attach() methods.
*/
#define task_subsys_state_check(task, subsys_id, __c) \
rcu_dereference_check(task->cgroups->subsys[subsys_id], \
rcu_read_lock_held() || \
lockdep_is_held(&task->alloc_lock) || \
cgroup_lock_is_held() || (__c))
static inline struct cgroup_subsys_state *
task_subsys_state(struct task_struct *task, int subsys_id)
{
return rcu_dereference_check(task->cgroups->subsys[subsys_id],
rcu_read_lock_held() ||
lockdep_is_held(&task->alloc_lock) ||
cgroup_lock_is_held());
return task_subsys_state_check(task, subsys_id, false);
}
static inline struct cgroup* task_cgroup(struct task_struct *task,

124
kernel/sched.c
View File

@ -306,52 +306,6 @@ static int init_task_group_load = INIT_TASK_GROUP_LOAD;
*/
struct task_group init_task_group;
/* return group to which a task belongs */
static inline struct task_group *task_group(struct task_struct *p)
{
struct task_group *tg;
#ifdef CONFIG_CGROUP_SCHED
tg = container_of(task_subsys_state(p, cpu_cgroup_subsys_id),
struct task_group, css);
#else
tg = &init_task_group;
#endif
return tg;
}
/* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
{
/*
* Strictly speaking this rcu_read_lock() is not needed since the
* task_group is tied to the cgroup, which in turn can never go away
* as long as there are tasks attached to it.
*
* However since task_group() uses task_subsys_state() which is an
* rcu_dereference() user, this quiets CONFIG_PROVE_RCU.
*/
rcu_read_lock();
#ifdef CONFIG_FAIR_GROUP_SCHED
p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
p->se.parent = task_group(p)->se[cpu];
#endif
#ifdef CONFIG_RT_GROUP_SCHED
p->rt.rt_rq = task_group(p)->rt_rq[cpu];
p->rt.parent = task_group(p)->rt_se[cpu];
#endif
rcu_read_unlock();
}
#else
static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { }
static inline struct task_group *task_group(struct task_struct *p)
{
return NULL;
}
#endif /* CONFIG_CGROUP_SCHED */
/* CFS-related fields in a runqueue */
@ -644,6 +598,49 @@ static inline int cpu_of(struct rq *rq)
#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
#define raw_rq() (&__raw_get_cpu_var(runqueues))
#ifdef CONFIG_CGROUP_SCHED
/*
* Return the group to which this tasks belongs.
*
* We use task_subsys_state_check() and extend the RCU verification
* with lockdep_is_held(&task_rq(p)->lock) because cpu_cgroup_attach()
* holds that lock for each task it moves into the cgroup. Therefore
* by holding that lock, we pin the task to the current cgroup.
*/
static inline struct task_group *task_group(struct task_struct *p)
{
struct cgroup_subsys_state *css;
css = task_subsys_state_check(p, cpu_cgroup_subsys_id,
lockdep_is_held(&task_rq(p)->lock));
return container_of(css, struct task_group, css);
}
/* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
{
#ifdef CONFIG_FAIR_GROUP_SCHED
p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
p->se.parent = task_group(p)->se[cpu];
#endif
#ifdef CONFIG_RT_GROUP_SCHED
p->rt.rt_rq = task_group(p)->rt_rq[cpu];
p->rt.parent = task_group(p)->rt_se[cpu];
#endif
}
#else /* CONFIG_CGROUP_SCHED */
static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { }
static inline struct task_group *task_group(struct task_struct *p)
{
return NULL;
}
#endif /* CONFIG_CGROUP_SCHED */
inline void update_rq_clock(struct rq *rq)
{
if (!rq->skip_clock_update)
@ -1257,6 +1254,12 @@ static void sched_avg_update(struct rq *rq)
s64 period = sched_avg_period();
while ((s64)(rq->clock - rq->age_stamp) > period) {
/*
* Inline assembly required to prevent the compiler
* optimising this loop into a divmod call.
* See __iter_div_u64_rem() for another example of this.
*/
asm("" : "+rm" (rq->age_stamp));
rq->age_stamp += period;
rq->rt_avg /= 2;
}
@ -1660,9 +1663,6 @@ static void update_shares(struct sched_domain *sd)
static void update_h_load(long cpu)
{
if (root_task_group_empty())
return;
walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
}
@ -4474,16 +4474,6 @@ recheck:
}
if (user) {
#ifdef CONFIG_RT_GROUP_SCHED
/*
* Do not allow realtime tasks into groups that have no runtime
* assigned.
*/
if (rt_bandwidth_enabled() && rt_policy(policy) &&
task_group(p)->rt_bandwidth.rt_runtime == 0)
return -EPERM;
#endif
retval = security_task_setscheduler(p, policy, param);
if (retval)
return retval;
@ -4499,6 +4489,22 @@ recheck:
* runqueue lock must be held.
*/
rq = __task_rq_lock(p);
#ifdef CONFIG_RT_GROUP_SCHED
if (user) {
/*
* Do not allow realtime tasks into groups that have no runtime
* assigned.
*/
if (rt_bandwidth_enabled() && rt_policy(policy) &&
task_group(p)->rt_bandwidth.rt_runtime == 0) {
__task_rq_unlock(rq);
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
return -EPERM;
}
}
#endif
/* recheck policy now with rq lock held */
if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
policy = oldpolicy = -1;