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Date: Wed, 11 May 2011 15:34:36 +0800
From: Cheng Xu <chengxu@...ux.vnet.ibm.com>
To: Ingo Molnar <mingo@...e.hu>
CC: Peter Zijlstra <peterz@...radead.org>,
Paul Mckenney <paulmck@...ux.vnet.ibm.com>,
LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] sched: rt_rq runtime leakage bug fix
This patch is to fix bug report https://lkml.org/lkml/2011/4/26/13
Function __disable_runtime() reports leakage of rt_rq runtime. The root cause is __disable_runtime() assumes it iterates through all the existing rt_rq's while walking rq->leaf_rt_rq_list, which actually contains only runnable rt_rq's. This problem also applies to __enable_runtime() and print_rt_stats().
The patch is based on above analysis, appears to fix the problem, but is only lightly tested.
Signed-off-by: Cheng Xu <chengxu@...ux.vnet.ibm.com>
Tested-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
kernel/sched_rt.c | 31 ++++++++++++++++++++++++-------
1 files changed, 24 insertions(+), 7 deletions(-)
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index e7cebdc..7f478ff 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -183,6 +183,13 @@ static inline u64 sched_rt_period(struct rt_rq *rt_rq)
return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
}
+#define rt_rq_of_rq_decls(name) struct task_group *name
+
+#define list_for_rt_rq_of_rq(iterator, rq) \
+ list_for_each_entry_rcu(iterator, &task_groups, list)
+
+#define rt_rq_of_rq_deref(iterator, rq) (iterator->rt_rq[cpu_of(rq)])
+
static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
{
list_add_rcu(&rt_rq->leaf_rt_rq_list,
@@ -288,6 +295,13 @@ static inline u64 sched_rt_period(struct rt_rq *rt_rq)
return ktime_to_ns(def_rt_bandwidth.rt_period);
}
+#define rt_rq_of_rq_decls(name) struct rt_rq *name
+
+#define list_for_rt_rq_of_rq(iterator, rq) \
+ for (iterator = &rq->rt; iterator; iterator = NULL)
+
+#define rt_rq_of_rq_deref(iterator, rq) (iterator)
+
static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
{
}
@@ -402,12 +416,13 @@ next:
static void __disable_runtime(struct rq *rq)
{
struct root_domain *rd = rq->rd;
- struct rt_rq *rt_rq;
+ rt_rq_of_rq_decls(iterator);
if (unlikely(!scheduler_running))
return;
- for_each_leaf_rt_rq(rt_rq, rq) {
+ list_for_rt_rq_of_rq(iterator, rq) {
+ struct rt_rq *rt_rq = rt_rq_of_rq_deref(iterator, rq);
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
s64 want;
int i;
@@ -487,7 +502,7 @@ static void disable_runtime(struct rq *rq)
static void __enable_runtime(struct rq *rq)
{
- struct rt_rq *rt_rq;
+ rt_rq_of_rq_decls(iterator);
if (unlikely(!scheduler_running))
return;
@@ -495,7 +510,8 @@ static void __enable_runtime(struct rq *rq)
/*
* Reset each runqueue's bandwidth settings
*/
- for_each_leaf_rt_rq(rt_rq, rq) {
+ list_for_rt_rq_of_rq(iterator, rq) {
+ struct rt_rq *rt_rq = rt_rq_of_rq_deref(iterator, rq);
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
raw_spin_lock(&rt_b->rt_runtime_lock);
@@ -1796,11 +1812,12 @@ extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
static void print_rt_stats(struct seq_file *m, int cpu)
{
- struct rt_rq *rt_rq;
+ rt_rq_of_rq_decls(iterator);
+ struct rq *rq = cpu_rq(cpu);
rcu_read_lock();
- for_each_leaf_rt_rq(rt_rq, cpu_rq(cpu))
- print_rt_rq(m, cpu, rt_rq);
+ list_for_rt_rq_of_rq(iterator, rq)
+ print_rt_rq(m, cpu, rt_rq_of_rq_deref(iterator, rq));
rcu_read_unlock();
}
#endif /* CONFIG_SCHED_DEBUG */
--
1.7.1
--
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