Commit 3eba0505 authored by Chengming Zhou's avatar Chengming Zhou Committed by Peter Zijlstra
Browse files

sched/cpuacct: Remove redundant RCU read lock 



The cpuacct_account_field() and it's cgroup v2 wrapper
cgroup_account_cputime_field() is only called from cputime
in task_group_account_field(), which is already in RCU read-side
critical section. So remove these redundant RCU read lock.

Suggested-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarChengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220220051426.5274-3-zhouchengming@bytedance.com
parent dc6e0818

include/linux/cgroup.h

+0 −2
Original line number Diff line number Diff line
@@ -804,11 +804,9 @@ static inline void cgroup_account_cputime_field(struct task_struct *task, 


	cpuacct_account_field(task, index, delta_exec);



	rcu_read_lock();

	cgrp = task_dfl_cgroup(task);

	if (cgroup_parent(cgrp))

		__cgroup_account_cputime_field(cgrp, index, delta_exec);

	rcu_read_unlock();

}



#else	/* CONFIG_CGROUPS */

kernel/sched/cpuacct.c

+0 −2
Original line number Diff line number Diff line
@@ -352,10 +352,8 @@ void cpuacct_account_field(struct task_struct *tsk, int index, u64 val) 
{

	struct cpuacct *ca;



	rcu_read_lock();

	for (ca = task_ca(tsk); ca != &root_cpuacct; ca = parent_ca(ca))

		__this_cpu_add(ca->cpustat->cpustat[index], val);

	rcu_read_unlock();

}



struct cgroup_subsys cpuacct_cgrp_subsys = {