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-rw-r--r--kernel/sched.c137
1 files changed, 76 insertions, 61 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index f8b8996228dd..f52a8801b7a2 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -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);
}
@@ -2494,7 +2494,16 @@ void sched_fork(struct task_struct *p, int clone_flags)
if (p->sched_class->task_fork)
p->sched_class->task_fork(p);
+ /*
+ * The child is not yet in the pid-hash so no cgroup attach races,
+ * and the cgroup is pinned to this child due to cgroup_fork()
+ * is ran before sched_fork().
+ *
+ * Silence PROVE_RCU.
+ */
+ rcu_read_lock();
set_task_cpu(p, cpu);
+ rcu_read_unlock();
#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
if (likely(sched_info_on()))
@@ -2864,9 +2873,9 @@ unsigned long nr_iowait(void)
return sum;
}
-unsigned long nr_iowait_cpu(void)
+unsigned long nr_iowait_cpu(int cpu)
{
- struct rq *this = this_rq();
+ struct rq *this = cpu_rq(cpu);
return atomic_read(&this->nr_iowait);
}
@@ -4465,16 +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;
@@ -4490,6 +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;