rcu: Protect rcu_boost() lockless accesses with ACCESS_ONCE()
This commit prevents random compiler optimizations by applying
ACCESS_ONCE() to lockless accesses.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 3ec85cb..d59913e 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1127,7 +1127,8 @@
struct task_struct *t;
struct list_head *tb;
- if (rnp->exp_tasks == NULL && rnp->boost_tasks == NULL)
+ if (ACCESS_ONCE(rnp->exp_tasks) == NULL &&
+ ACCESS_ONCE(rnp->boost_tasks) == NULL)
return 0; /* Nothing left to boost. */
raw_spin_lock_irqsave(&rnp->lock, flags);