Commit 58ab6d25 authored by pengdonglin's avatar pengdonglin Committed by Tejun Heo
Browse files

cgroup/cpuset: Remove redundant rcu_read_lock/unlock() in spin_lock 



Since commit a8bb74ac ("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 <longman@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarpengdonglin <pengdonglin@xiaomi.com>
Signed-off-by: default avatarpengdonglin <dolinux.peng@gmail.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 3ee4211e

kernel/cgroup/cpuset.c

+0 −6
Original line number Diff line number Diff line
@@ -4107,7 +4107,6 @@ 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)
@@ -4129,7 +4128,6 @@ 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);

}
@@ -4202,9 +4200,7 @@ 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;
@@ -4299,10 +4295,8 @@ 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;