Commit f4f809f6 authored by Roman Gushchin's avatar Roman Gushchin Committed by Tejun Heo
Browse files

cgroup: inline cgroup_task_freeze() 



After the introduction of the cgroup.kill there is only one call site
of cgroup_task_freeze() left: cgroup_exit(). cgroup_task_freeze() is
currently taking rcu_read_lock() to read task's cgroup flags, but
because it's always called with css_set_lock locked, the rcu protection
is excessive.

Simplify the code by inlining cgroup_task_freeze().

v2: fix build

Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 85e3b86e

include/linux/cgroup.h

+0 −18
Original line number Diff line number Diff line
@@ -906,20 +906,6 @@ void cgroup_freeze(struct cgroup *cgrp, bool freeze); 
void cgroup_freezer_migrate_task(struct task_struct *task, struct cgroup *src,

				 struct cgroup *dst);



static inline bool cgroup_task_freeze(struct task_struct *task)

{

	bool ret;



	if (task->flags & PF_KTHREAD)

		return false;



	rcu_read_lock();

	ret = test_bit(CGRP_FREEZE, &task_dfl_cgroup(task)->flags);

	rcu_read_unlock();



	return ret;

}



static inline bool cgroup_task_frozen(struct task_struct *task)

{

	return task->frozen;
@@ -929,10 +915,6 @@ static inline bool cgroup_task_frozen(struct task_struct *task) 


static inline void cgroup_enter_frozen(void) { }

static inline void cgroup_leave_frozen(bool always_leave) { }

static inline bool cgroup_task_freeze(struct task_struct *task)

{

	return false;

}

static inline bool cgroup_task_frozen(struct task_struct *task)

{

	return false;

kernel/cgroup/cgroup.c

+2 −1
Original line number Diff line number Diff line
@@ -6267,7 +6267,8 @@ void cgroup_exit(struct task_struct *tsk) 
	cset->nr_tasks--;



	WARN_ON_ONCE(cgroup_task_frozen(tsk));

	if (unlikely(cgroup_task_freeze(tsk)))

	if (unlikely(!(tsk->flags & PF_KTHREAD) &&

		     test_bit(CGRP_FREEZE, &task_dfl_cgroup(tsk)->flags)))

		cgroup_update_frozen(task_dfl_cgroup(tsk));



	spin_unlock_irq(&css_set_lock);