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| author | Peter Zijlstra <peterz@infradead.org> | 2011-12-07 14:32:08 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-12-08 05:45:48 +0100 |
| commit | 067491b7313c41f49607fce782d29344d1472587 (patch) | |
| tree | 06f6352372038f7f4171c8d8fc869e686665d32f /kernel/sched | |
| parent | cd490c5b285544dc1319cf79c2ca0528a6447f61 (diff) | |
| download | lwn-067491b7313c41f49607fce782d29344d1472587.tar.gz lwn-067491b7313c41f49607fce782d29344d1472587.zip | |
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.c | 9 |
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; } |