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authorAndy Lutomirski <luto@amacapital.net>2014-11-29 08:13:51 -0800
committerIngo Molnar <mingo@kernel.org>2014-12-08 11:44:19 +0100
commitfd7de1e8d5b2b2b35e71332fafb899f584597150 (patch)
tree7b0ff7aad0d8c984748557dfec52fad02b54a045 /kernel
parent36ce98818a4df66c8134c31fd6e768b4119c7a90 (diff)
downloadlinux-fd7de1e8d5b2b2b35e71332fafb899f584597150.tar.bz2
sched: Add missing rcu protection to wake_up_all_idle_cpus
Locklessly doing is_idle_task(rq->curr) is only okay because of RCU protection. The older variant of the broken code checked rq->curr == rq->idle instead and therefore didn't need RCU. Fixes: f6be8af1c95d ("sched: Add new API wake_up_if_idle() to wake up the idle cpu") Signed-off-by: Andy Lutomirski <luto@amacapital.net> Reviewed-by: Chuansheng Liu <chuansheng.liu@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/729365dddca178506dfd0a9451006344cd6808bc.1417277372.git.luto@amacapital.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d44d0c59122b..88f49bc935ed 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1628,8 +1628,10 @@ void wake_up_if_idle(int cpu)
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
- if (!is_idle_task(rq->curr))
- return;
+ rcu_read_lock();
+
+ if (!is_idle_task(rcu_dereference(rq->curr)))
+ goto out;
if (set_nr_if_polling(rq->idle)) {
trace_sched_wake_idle_without_ipi(cpu);
@@ -1640,6 +1642,9 @@ void wake_up_if_idle(int cpu)
/* Else cpu is not in idle, do nothing here */
raw_spin_unlock_irqrestore(&rq->lock, flags);
}
+
+out:
+ rcu_read_unlock();
}
bool cpus_share_cache(int this_cpu, int that_cpu)