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Commit d41d5a01 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

cgroup: Fix cgroup_subsys::exit callback 



Make the ::exit method act like ::attach, it is after all very nearly
the same thing.

The bug had no effect on correctness - fixing it is an optimization for
the scheduler. Also, later perf-cgroups patches rely on it.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarPaul Menage <menage@google.com>
LKML-Reference: <1297160655.13327.92.camel@laptop>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent b00560f2

include/linux/cgroup.h

+2 −1
Original line number Diff line number Diff line
@@ -474,7 +474,8 @@ struct cgroup_subsys { 
			struct cgroup *old_cgrp, struct task_struct *tsk,

			bool threadgroup);

	void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);

	void (*exit)(struct cgroup_subsys *ss, struct task_struct *task);

	void (*exit)(struct cgroup_subsys *ss, struct cgroup *cgrp,

			struct cgroup *old_cgrp, struct task_struct *task);

	int (*populate)(struct cgroup_subsys *ss,

			struct cgroup *cgrp);

	void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);

kernel/cgroup.c

+18 −13
Original line number Diff line number Diff line
@@ -4230,20 +4230,8 @@ void cgroup_post_fork(struct task_struct *child) 
 */

void cgroup_exit(struct task_struct *tsk, int run_callbacks)

{

	int i;

	struct css_set *cg;



	if (run_callbacks && need_forkexit_callback) {

		/*

		 * modular subsystems can't use callbacks, so no need to lock

		 * the subsys array

		 */

		for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {

			struct cgroup_subsys *ss = subsys[i];

			if (ss->exit)

				ss->exit(ss, tsk);

		}

	}

	int i;



	/*

	 * Unlink from the css_set task list if necessary.
@@ -4261,7 +4249,24 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks) 
	task_lock(tsk);

	cg = tsk->cgroups;

	tsk->cgroups = &init_css_set;



	if (run_callbacks && need_forkexit_callback) {

		/*

		 * modular subsystems can't use callbacks, so no need to lock

		 * the subsys array

		 */

		for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {

			struct cgroup_subsys *ss = subsys[i];

			if (ss->exit) {

				struct cgroup *old_cgrp =

					rcu_dereference_raw(cg->subsys[i])->cgroup;

				struct cgroup *cgrp = task_cgroup(tsk, i);

				ss->exit(ss, cgrp, old_cgrp, tsk);

			}

		}

	}

	task_unlock(tsk);



	if (cg)

		put_css_set_taskexit(cg);

}

kernel/sched.c

+2 −4
Original line number Diff line number Diff line
@@ -606,9 +606,6 @@ static inline struct task_group *task_group(struct task_struct *p) 
	struct task_group *tg;

	struct cgroup_subsys_state *css;



	if (p->flags & PF_EXITING)

		return &root_task_group;



	css = task_subsys_state_check(p, cpu_cgroup_subsys_id,

			lockdep_is_held(&task_rq(p)->lock));

	tg = container_of(css, struct task_group, css);
@@ -8863,7 +8860,8 @@ cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, 
}



static void

cpu_cgroup_exit(struct cgroup_subsys *ss, struct task_struct *task)

cpu_cgroup_exit(struct cgroup_subsys *ss, struct cgroup *cgrp,

		struct cgroup *old_cgrp, struct task_struct *task)

{

	/*

	 * cgroup_exit() is called in the copy_process() failure path.