forked from luck/tmp_suning_uos_patched
sched: Fix rt_rq runtime leakage bug
This patch is to fix the real-time scheduler bug reported at: https://lkml.org/lkml/2011/4/26/13 That is, when running multiple real-time threads on every logical CPUs and then turning off one CPU, the kernel will bug at function __disable_runtime(). Function __disable_runtime() bugs and 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. Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Cheng Xu <chengxu@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/4DCE1F12.6040609@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -183,6 +183,14 @@ static inline u64 sched_rt_period(struct rt_rq *rt_rq)
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return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
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}
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typedef struct task_group *rt_rq_iter_t;
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#define for_each_rt_rq(rt_rq, iter, rq) \
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for (iter = list_entry_rcu(task_groups.next, typeof(*iter), list); \
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(&iter->list != &task_groups) && \
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(rt_rq = iter->rt_rq[cpu_of(rq)]); \
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iter = list_entry_rcu(iter->list.next, typeof(*iter), list))
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static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
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{
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list_add_rcu(&rt_rq->leaf_rt_rq_list,
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@ -288,6 +296,11 @@ static inline u64 sched_rt_period(struct rt_rq *rt_rq)
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return ktime_to_ns(def_rt_bandwidth.rt_period);
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}
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typedef struct rt_rq *rt_rq_iter_t;
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#define for_each_rt_rq(rt_rq, iter, rq) \
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for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
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static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
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{
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}
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@ -402,12 +415,13 @@ static int do_balance_runtime(struct rt_rq *rt_rq)
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static void __disable_runtime(struct rq *rq)
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{
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struct root_domain *rd = rq->rd;
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rt_rq_iter_t iter;
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struct rt_rq *rt_rq;
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if (unlikely(!scheduler_running))
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return;
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for_each_leaf_rt_rq(rt_rq, rq) {
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for_each_rt_rq(rt_rq, iter, rq) {
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struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
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s64 want;
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int i;
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@ -487,6 +501,7 @@ static void disable_runtime(struct rq *rq)
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static void __enable_runtime(struct rq *rq)
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{
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rt_rq_iter_t iter;
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struct rt_rq *rt_rq;
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if (unlikely(!scheduler_running))
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@ -495,7 +510,7 @@ static void __enable_runtime(struct rq *rq)
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/*
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* Reset each runqueue's bandwidth settings
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*/
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for_each_leaf_rt_rq(rt_rq, rq) {
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for_each_rt_rq(rt_rq, iter, rq) {
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struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
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raw_spin_lock(&rt_b->rt_runtime_lock);
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@ -1796,10 +1811,11 @@ extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
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static void print_rt_stats(struct seq_file *m, int cpu)
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{
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rt_rq_iter_t iter;
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struct rt_rq *rt_rq;
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rcu_read_lock();
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for_each_leaf_rt_rq(rt_rq, cpu_rq(cpu))
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for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
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print_rt_rq(m, cpu, rt_rq);
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rcu_read_unlock();
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}
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