diff options
| author | Cheng Xu | 2011-05-14 14:20:02 +0800 |
|---|---|---|
| committer | Ingo Molnar | 2011-05-16 11:00:54 +0200 |
| commit | ec514c487c3d4b652943da7b0afbc094eee08cfa (patch) | |
| tree | d6766fd9a3f6eec2816a8191cf02f14564ba7473 | |
| parent | bd1a643e10eb8782b36b47c3602300319dd2fb00 (diff) | |
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>
| -rw-r--r-- | kernel/sched_rt.c | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c index e7cebdc65f82..f8fcf8297c5f 100644 --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -183,6 +183,14 @@ static inline u64 sched_rt_period(struct rt_rq *rt_rq) return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period); } +typedef struct task_group *rt_rq_iter_t; + +#define for_each_rt_rq(rt_rq, iter, rq) \ + for (iter = list_entry_rcu(task_groups.next, typeof(*iter), list); \ + (&iter->list != &task_groups) && \ + (rt_rq = iter->rt_rq[cpu_of(rq)]); \ + iter = list_entry_rcu(iter->list.next, typeof(*iter), list)) + static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq) { list_add_rcu(&rt_rq->leaf_rt_rq_list, @@ -288,6 +296,11 @@ static inline u64 sched_rt_period(struct rt_rq *rt_rq) return ktime_to_ns(def_rt_bandwidth.rt_period); } +typedef struct rt_rq *rt_rq_iter_t; + +#define for_each_rt_rq(rt_rq, iter, rq) \ + for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL) + static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq) { } @@ -402,12 +415,13 @@ next: static void __disable_runtime(struct rq *rq) { struct root_domain *rd = rq->rd; + rt_rq_iter_t iter; struct rt_rq *rt_rq; if (unlikely(!scheduler_running)) return; - for_each_leaf_rt_rq(rt_rq, rq) { + for_each_rt_rq(rt_rq, iter, rq) { struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq); s64 want; int i; @@ -487,6 +501,7 @@ static void disable_runtime(struct rq *rq) static void __enable_runtime(struct rq *rq) { + rt_rq_iter_t iter; struct rt_rq *rt_rq; if (unlikely(!scheduler_running)) @@ -495,7 +510,7 @@ static void __enable_runtime(struct rq *rq) /* * Reset each runqueue's bandwidth settings */ - for_each_leaf_rt_rq(rt_rq, rq) { + for_each_rt_rq(rt_rq, iter, rq) { struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq); raw_spin_lock(&rt_b->rt_runtime_lock); @@ -1796,10 +1811,11 @@ 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) { + rt_rq_iter_t iter; struct rt_rq *rt_rq; rcu_read_lock(); - for_each_leaf_rt_rq(rt_rq, cpu_rq(cpu)) + for_each_rt_rq(rt_rq, iter, cpu_rq(cpu)) print_rt_rq(m, cpu, rt_rq); rcu_read_unlock(); } |