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authorPeter Zijlstra <peterz@infradead.org>2011-12-07 17:32:08 +0400
committerIngo Molnar <mingo@elte.hu>2011-12-08 08:45:48 +0400
commit067491b7313c41f49607fce782d29344d1472587 (patch)
tree06f6352372038f7f4171c8d8fc869e686665d32f /kernel/sched
parentcd490c5b285544dc1319cf79c2ca0528a6447f61 (diff)
downloadlinux-067491b7313c41f49607fce782d29344d1472587.tar.xz
sched, nohz: Fix missing RCU read lock
Yong Zhang reported: > [ INFO: suspicious RCU usage. ] > kernel/sched/fair.c:5091 suspicious rcu_dereference_check() usage! This is due to the sched_domain stuff being RCU protected and commit 0b005cf5 ("sched, nohz: Implement sched group, domain aware nohz idle load balancing") overlooking this fact. The sd variable only lives inside the for_each_domain() block, so we only need to wrap that. Reported-by: Yong Zhang <yong.zhang0@gmail.com> Tested-by: Yong Zhang <yong.zhang0@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Link: http://lkml.kernel.org/r/1323264728.32012.107.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/fair.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6482136f8991..a4d2b7abc3cd 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5088,23 +5088,28 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu)
if (rq->nr_running >= 2)
goto need_kick;
+ rcu_read_lock();
for_each_domain(cpu, sd) {
struct sched_group *sg = sd->groups;
struct sched_group_power *sgp = sg->sgp;
int nr_busy = atomic_read(&sgp->nr_busy_cpus);
if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1)
- goto need_kick;
+ goto need_kick_unlock;
if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
&& (cpumask_first_and(nohz.idle_cpus_mask,
sched_domain_span(sd)) < cpu))
- goto need_kick;
+ goto need_kick_unlock;
if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING)))
break;
}
+ rcu_read_unlock();
return 0;
+
+need_kick_unlock:
+ rcu_read_unlock();
need_kick:
return 1;
}