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Commit 081aa458 authored by Li Zefan's avatar Li Zefan Committed by Tejun Heo
Browse files

cgroup: consolidate cgroup_attach_task() and cgroup_attach_proc() 



These two functions share most of the code.

Signed-off-by: default avatarLi Zefan <lizefan@huawei.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent bd2953eb

include/linux/cgroup.h

+2 −1
Original line number Diff line number Diff line
@@ -693,7 +693,8 @@ struct task_struct *cgroup_iter_next(struct cgroup *cgrp, 
					struct cgroup_iter *it);

void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it);

int cgroup_scan_tasks(struct cgroup_scanner *scan);

int cgroup_attach_task(struct cgroup *, struct task_struct *);

int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk,

		       bool threadgroup);

int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);



/*

kernel/cgroup.c

+20 −89
Original line number Diff line number Diff line
@@ -59,7 +59,7 @@ 
#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */

#include <linux/eventfd.h>

#include <linux/poll.h>

#include <linux/flex_array.h> /* used in cgroup_attach_proc */

#include <linux/flex_array.h> /* used in cgroup_attach_task */

#include <linux/kthread.h>



#include <linux/atomic.h>
@@ -1943,82 +1943,6 @@ static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, 
	put_css_set(oldcg);

}



/**

 * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp'

 * @cgrp: the cgroup the task is attaching to

 * @tsk: the task to be attached

 *

 * Call with cgroup_mutex and threadgroup locked. May take task_lock of

 * @tsk during call.

 */

int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)

{

	int retval = 0;

	struct cgroup_subsys *ss, *failed_ss = NULL;

	struct cgroup *oldcgrp;

	struct cgroupfs_root *root = cgrp->root;

	struct cgroup_taskset tset = { };

	struct css_set *newcg;



	/* @tsk either already exited or can't exit until the end */

	if (tsk->flags & PF_EXITING)

		return -ESRCH;



	/* Nothing to do if the task is already in that cgroup */

	oldcgrp = task_cgroup_from_root(tsk, root);

	if (cgrp == oldcgrp)

		return 0;



	tset.single.task = tsk;

	tset.single.cgrp = oldcgrp;



	for_each_subsys(root, ss) {

		if (ss->can_attach) {

			retval = ss->can_attach(cgrp, &tset);

			if (retval) {

				/*

				 * Remember on which subsystem the can_attach()

				 * failed, so that we only call cancel_attach()

				 * against the subsystems whose can_attach()

				 * succeeded. (See below)

				 */

				failed_ss = ss;

				goto out;

			}

		}

	}



	newcg = find_css_set(tsk->cgroups, cgrp);

	if (!newcg) {

		retval = -ENOMEM;

		goto out;

	}



	cgroup_task_migrate(cgrp, oldcgrp, tsk, newcg);



	for_each_subsys(root, ss) {

		if (ss->attach)

			ss->attach(cgrp, &tset);

	}



out:

	if (retval) {

		for_each_subsys(root, ss) {

			if (ss == failed_ss)

				/*

				 * This subsystem was the one that failed the

				 * can_attach() check earlier, so we don't need

				 * to call cancel_attach() against it or any

				 * remaining subsystems.

				 */

				break;

			if (ss->cancel_attach)

				ss->cancel_attach(cgrp, &tset);

		}

	}

	return retval;

}



/**

 * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'

 * @from: attach to all cgroups of a given task
@@ -2033,7 +1957,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) 
	for_each_active_root(root) {

		struct cgroup *from_cg = task_cgroup_from_root(from, root);



		retval = cgroup_attach_task(from_cg, tsk);

		retval = cgroup_attach_task(from_cg, tsk, false);

		if (retval)

			break;

	}
@@ -2044,21 +1968,22 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) 
EXPORT_SYMBOL_GPL(cgroup_attach_task_all);



/**

 * cgroup_attach_proc - attach all threads in a threadgroup to a cgroup

 * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup

 * @cgrp: the cgroup to attach to

 * @leader: the threadgroup leader task_struct of the group to be attached

 * @tsk: the task or the leader of the threadgroup to be attached

 * @threadgroup: attach the whole threadgroup?

 *

 * Call holding cgroup_mutex and the group_rwsem of the leader. Will take

 * task_lock of each thread in leader's threadgroup individually in turn.

 * task_lock of @tsk or each thread in the threadgroup individually in turn.

 */

static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)

int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk,

		       bool threadgroup)

{

	int retval, i, group_size;

	struct cgroup_subsys *ss, *failed_ss = NULL;

	/* guaranteed to be initialized later, but the compiler needs this */

	struct cgroupfs_root *root = cgrp->root;

	/* threadgroup list cursor and array */

	struct task_struct *tsk;

	struct task_struct *leader = tsk;

	struct task_and_cgroup *tc;

	struct flex_array *group;

	struct cgroup_taskset tset = { };
@@ -2070,7 +1995,10 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) 
	 * group - group_rwsem prevents new threads from appearing, and if

	 * threads exit, this will just be an over-estimate.

	 */

	group_size = get_nr_threads(leader);

	if (threadgroup)

		group_size = get_nr_threads(tsk);

	else

		group_size = 1;

	/* flex_array supports very large thread-groups better than kmalloc. */

	group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL);

	if (!group)
@@ -2080,7 +2008,6 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) 
	if (retval)

		goto out_free_group_list;



	tsk = leader;

	i = 0;

	/*

	 * Prevent freeing of tasks while we take a snapshot. Tasks that are
@@ -2109,6 +2036,9 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) 
		retval = flex_array_put(group, i, &ent, GFP_ATOMIC);

		BUG_ON(retval != 0);

		i++;



		if (!threadgroup)

			break;

	} while_each_thread(leader, tsk);

	rcu_read_unlock();

	/* remember the number of threads in the array for later. */
@@ -2262,9 +2192,10 @@ retry_find_task: 
			put_task_struct(tsk);

			goto retry_find_task;

		}

		ret = cgroup_attach_proc(cgrp, tsk);

	} else

		ret = cgroup_attach_task(cgrp, tsk);

	}



	ret = cgroup_attach_task(cgrp, tsk, threadgroup);



	threadgroup_unlock(tsk);



	put_task_struct(tsk);

kernel/cpuset.c

+1 −1
Original line number Diff line number Diff line
@@ -2008,7 +2008,7 @@ static void cpuset_do_move_task(struct task_struct *tsk, 
	struct cgroup *new_cgroup = scan->data;



	cgroup_lock();

	cgroup_attach_task(new_cgroup, tsk);

	cgroup_attach_task(new_cgroup, tsk, false);

	cgroup_unlock();

}