Commit-ID: 4f89b336fd1edf0c88875d0b7fcdc288c7de903d Gitweb: http://git.kernel.org/tip/4f89b336fd1edf0c88875d0b7fcdc288c7de903d Author: Paul E. McKenney <paul.mckenney@xxxxxxxxxx> AuthorDate: Fri, 9 Dec 2011 14:43:47 -0800 Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> CommitDate: Sun, 11 Dec 2011 10:33:19 -0800 rcu: Apply ACCESS_ONCE() to rcu_boost() return value Both TINY_RCU's and TREE_RCU's implementations of rcu_boost() access the ->boost_tasks and ->exp_tasks fields without preventing concurrent changes to these fields. This commit therefore applies ACCESS_ONCE in order to prevent compiler mischief. Signed-off-by: Paul E. McKenney <paul.mckenney@xxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> --- kernel/rcutiny_plugin.h | 4 ++-- kernel/rcutree_plugin.h | 3 ++- 2 files changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h index dfa97cb..9cb1ae4 100644 --- a/kernel/rcutiny_plugin.h +++ b/kernel/rcutiny_plugin.h @@ -312,8 +312,8 @@ static int rcu_boost(void) rt_mutex_lock(&mtx); rt_mutex_unlock(&mtx); /* Keep lockdep happy. */ - return rcu_preempt_ctrlblk.boost_tasks != NULL || - rcu_preempt_ctrlblk.exp_tasks != NULL; + return ACCESS_ONCE(rcu_preempt_ctrlblk.boost_tasks) != NULL || + ACCESS_ONCE(rcu_preempt_ctrlblk.exp_tasks) != NULL; } /* diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index f55f10b..8bb35d7 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1232,7 +1232,8 @@ static int rcu_boost(struct rcu_node *rnp) rt_mutex_lock(&mtx); /* Side effect: boosts task t's priority. */ rt_mutex_unlock(&mtx); /* Keep lockdep happy. */ - return rnp->exp_tasks != NULL || rnp->boost_tasks != NULL; + return ACCESS_ONCE(rnp->exp_tasks) != NULL || + ACCESS_ONCE(rnp->boost_tasks) != NULL; } /* -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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