From: pengdonglin Since commit a8bb74acd8efe ("rcu: Consolidate RCU-sched update-side function definitions") there is no difference between rcu_read_lock(), rcu_read_lock_bh() and rcu_read_lock_sched() in terms of RCU read section and the relevant grace period. That means that spin_lock(), which implies rcu_read_lock_sched(), also implies rcu_read_lock(). There is no need no explicitly start a RCU read section if one has already been started implicitly by spin_lock(). Simplify the code and remove the inner rcu_read_lock() invocation. Cc: Waiman Long Cc: Johannes Weiner Acked-by: Waiman Long Signed-off-by: pengdonglin Signed-off-by: pengdonglin --- kernel/cgroup/cpuset.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 27adb04df675..9b7e8e8e9411 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -4073,7 +4073,6 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) struct cpuset *cs; spin_lock_irqsave(&callback_lock, flags); - rcu_read_lock(); cs = task_cs(tsk); if (cs != &top_cpuset) @@ -4095,7 +4094,6 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) cpumask_copy(pmask, possible_mask); } - rcu_read_unlock(); spin_unlock_irqrestore(&callback_lock, flags); } @@ -4168,9 +4166,7 @@ nodemask_t cpuset_mems_allowed(struct task_struct *tsk) unsigned long flags; spin_lock_irqsave(&callback_lock, flags); - rcu_read_lock(); guarantee_online_mems(task_cs(tsk), &mask); - rcu_read_unlock(); spin_unlock_irqrestore(&callback_lock, flags); return mask; @@ -4265,10 +4261,8 @@ bool cpuset_current_node_allowed(int node, gfp_t gfp_mask) /* Not hardwall and node outside mems_allowed: scan up cpusets */ spin_lock_irqsave(&callback_lock, flags); - rcu_read_lock(); cs = nearest_hardwall_ancestor(task_cs(current)); allowed = node_isset(node, cs->mems_allowed); - rcu_read_unlock(); spin_unlock_irqrestore(&callback_lock, flags); return allowed; -- 2.34.1