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Commit 5abb8855 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: consistently use @cset for struct css_set variables 



cgroup.c uses @cg for most struct css_set variables, which in itself
could be a bit confusing, but made much worse by the fact that there
are places which use @cg for struct cgroup variables.
compare_css_sets() epitomizes this confusion - @[old_]cg are struct
css_set while @cg[12] are struct cgroup.

It's not like the whole deal with cgroup, css_set and cg_cgroup_link
isn't already confusing enough.  Let's give it some sanity by
uniformly using @cset for all struct css_set variables.

* s/cg/cset/ for all css_set variables.

* s/oldcg/old_cset/ s/oldcgrp/old_cgrp/.  The same for the ones
  prefixed with "new".

* s/cg/cgrp/ for cgroup variables in compare_css_sets().

* s/css/cset/ for the cgroup variable in task_cgroup_from_root().

* Whiteline adjustments.

This patch is purely cosmetic.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent 3fc3db9a

kernel/cgroup.c

+109 −107
Original line number Diff line number Diff line
@@ -376,30 +376,32 @@ static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) 
 * compiled into their kernel but not actually in use */

static int use_task_css_set_links __read_mostly;



static void __put_css_set(struct css_set *cg, int taskexit)

static void __put_css_set(struct css_set *cset, int taskexit)

{

	struct cg_cgroup_link *link;

	struct cg_cgroup_link *saved_link;



	/*

	 * Ensure that the refcount doesn't hit zero while any readers

	 * can see it. Similar to atomic_dec_and_lock(), but for an

	 * rwlock

	 */

	if (atomic_add_unless(&cg->refcount, -1, 1))

	if (atomic_add_unless(&cset->refcount, -1, 1))

		return;

	write_lock(&css_set_lock);

	if (!atomic_dec_and_test(&cg->refcount)) {

	if (!atomic_dec_and_test(&cset->refcount)) {

		write_unlock(&css_set_lock);

		return;

	}



	/* This css_set is dead. unlink it and release cgroup refcounts */

	hash_del(&cg->hlist);

	hash_del(&cset->hlist);

	css_set_count--;



	list_for_each_entry_safe(link, saved_link, &cg->cg_links,

	list_for_each_entry_safe(link, saved_link, &cset->cg_links,

				 cg_link_list) {

		struct cgroup *cgrp = link->cgrp;



		list_del(&link->cg_link_list);

		list_del(&link->cgrp_link_list);
@@ -421,45 +423,45 @@ static void __put_css_set(struct css_set *cg, int taskexit) 
	}



	write_unlock(&css_set_lock);

	kfree_rcu(cg, rcu_head);

	kfree_rcu(cset, rcu_head);

}



/*

 * refcounted get/put for css_set objects

 */

static inline void get_css_set(struct css_set *cg)

static inline void get_css_set(struct css_set *cset)

{

	atomic_inc(&cg->refcount);

	atomic_inc(&cset->refcount);

}



static inline void put_css_set(struct css_set *cg)

static inline void put_css_set(struct css_set *cset)

{

	__put_css_set(cg, 0);

	__put_css_set(cset, 0);

}



static inline void put_css_set_taskexit(struct css_set *cg)

static inline void put_css_set_taskexit(struct css_set *cset)

{

	__put_css_set(cg, 1);

	__put_css_set(cset, 1);

}



/*

 * compare_css_sets - helper function for find_existing_css_set().

 * @cg: candidate css_set being tested

 * @old_cg: existing css_set for a task

 * @cset: candidate css_set being tested

 * @old_cset: existing css_set for a task

 * @new_cgrp: cgroup that's being entered by the task

 * @template: desired set of css pointers in css_set (pre-calculated)

 *

 * Returns true if "cg" matches "old_cg" except for the hierarchy

 * which "new_cgrp" belongs to, for which it should match "new_cgrp".

 */

static bool compare_css_sets(struct css_set *cg,

			     struct css_set *old_cg,

static bool compare_css_sets(struct css_set *cset,

			     struct css_set *old_cset,

			     struct cgroup *new_cgrp,

			     struct cgroup_subsys_state *template[])

{

	struct list_head *l1, *l2;



	if (memcmp(template, cg->subsys, sizeof(cg->subsys))) {

	if (memcmp(template, cset->subsys, sizeof(cset->subsys))) {

		/* Not all subsystems matched */

		return false;

	}
@@ -473,28 +475,28 @@ static bool compare_css_sets(struct css_set *cg, 
	 * candidates.

	 */



	l1 = &cg->cg_links;

	l2 = &old_cg->cg_links;

	l1 = &cset->cg_links;

	l2 = &old_cset->cg_links;

	while (1) {

		struct cg_cgroup_link *cgl1, *cgl2;

		struct cgroup *cg1, *cg2;

		struct cgroup *cgrp1, *cgrp2;



		l1 = l1->next;

		l2 = l2->next;

		/* See if we reached the end - both lists are equal length. */

		if (l1 == &cg->cg_links) {

			BUG_ON(l2 != &old_cg->cg_links);

		if (l1 == &cset->cg_links) {

			BUG_ON(l2 != &old_cset->cg_links);

			break;

		} else {

			BUG_ON(l2 == &old_cg->cg_links);

			BUG_ON(l2 == &old_cset->cg_links);

		}

		/* Locate the cgroups associated with these links. */

		cgl1 = list_entry(l1, struct cg_cgroup_link, cg_link_list);

		cgl2 = list_entry(l2, struct cg_cgroup_link, cg_link_list);

		cg1 = cgl1->cgrp;

		cg2 = cgl2->cgrp;

		cgrp1 = cgl1->cgrp;

		cgrp2 = cgl2->cgrp;

		/* Hierarchies should be linked in the same order. */

		BUG_ON(cg1->root != cg2->root);

		BUG_ON(cgrp1->root != cgrp2->root);



		/*

		 * If this hierarchy is the hierarchy of the cgroup
@@ -503,11 +505,11 @@ static bool compare_css_sets(struct css_set *cg, 
		 * hierarchy, then this css_set should point to the

		 * same cgroup as the old css_set.

		 */

		if (cg1->root == new_cgrp->root) {

			if (cg1 != new_cgrp)

		if (cgrp1->root == new_cgrp->root) {

			if (cgrp1 != new_cgrp)

				return false;

		} else {

			if (cg1 != cg2)

			if (cgrp1 != cgrp2)

				return false;

		}

	}
@@ -527,14 +529,13 @@ static bool compare_css_sets(struct css_set *cg, 
 * template: location in which to build the desired set of subsystem

 * state objects for the new cgroup group

 */

static struct css_set *find_existing_css_set(

	struct css_set *oldcg,

static struct css_set *find_existing_css_set(struct css_set *old_cset,

					struct cgroup *cgrp,

					struct cgroup_subsys_state *template[])

{

	int i;

	struct cgroupfs_root *root = cgrp->root;

	struct css_set *cg;

	struct css_set *cset;

	unsigned long key;



	/*
@@ -551,17 +552,17 @@ static struct css_set *find_existing_css_set( 
		} else {

			/* Subsystem is not in this hierarchy, so we

			 * don't want to change the subsystem state */

			template[i] = oldcg->subsys[i];

			template[i] = old_cset->subsys[i];

		}

	}



	key = css_set_hash(template);

	hash_for_each_possible(css_set_table, cg, hlist, key) {

		if (!compare_css_sets(cg, oldcg, cgrp, template))

	hash_for_each_possible(css_set_table, cset, hlist, key) {

		if (!compare_css_sets(cset, old_cset, cgrp, template))

			continue;



		/* This css_set matches what we need */

		return cg;

		return cset;

	}



	/* No existing cgroup group matched */
@@ -603,18 +604,18 @@ static int allocate_cg_links(int count, struct list_head *tmp) 
/**

 * link_css_set - a helper function to link a css_set to a cgroup

 * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links()

 * @cg: the css_set to be linked

 * @cset: the css_set to be linked

 * @cgrp: the destination cgroup

 */

static void link_css_set(struct list_head *tmp_cg_links,

			 struct css_set *cg, struct cgroup *cgrp)

			 struct css_set *cset, struct cgroup *cgrp)

{

	struct cg_cgroup_link *link;



	BUG_ON(list_empty(tmp_cg_links));

	link = list_first_entry(tmp_cg_links, struct cg_cgroup_link,

				cgrp_link_list);

	link->cg = cg;

	link->cg = cset;

	link->cgrp = cgrp;

	atomic_inc(&cgrp->count);

	list_move(&link->cgrp_link_list, &cgrp->css_sets);
@@ -622,7 +623,7 @@ static void link_css_set(struct list_head *tmp_cg_links, 
	 * Always add links to the tail of the list so that the list

	 * is sorted by order of hierarchy creation

	 */

	list_add_tail(&link->cg_link_list, &cg->cg_links);

	list_add_tail(&link->cg_link_list, &cset->cg_links);

}



/*
@@ -632,10 +633,10 @@ static void link_css_set(struct list_head *tmp_cg_links, 
 * substituted into the appropriate hierarchy. Must be called with

 * cgroup_mutex held

 */

static struct css_set *find_css_set(

	struct css_set *oldcg, struct cgroup *cgrp)

static struct css_set *find_css_set(struct css_set *old_cset,

				    struct cgroup *cgrp)

{

	struct css_set *res;

	struct css_set *cset;

	struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];



	struct list_head tmp_cg_links;
@@ -646,40 +647,40 @@ static struct css_set *find_css_set( 
	/* First see if we already have a cgroup group that matches

	 * the desired set */

	read_lock(&css_set_lock);

	res = find_existing_css_set(oldcg, cgrp, template);

	if (res)

		get_css_set(res);

	cset = find_existing_css_set(old_cset, cgrp, template);

	if (cset)

		get_css_set(cset);

	read_unlock(&css_set_lock);



	if (res)

		return res;

	if (cset)

		return cset;



	res = kmalloc(sizeof(*res), GFP_KERNEL);

	if (!res)

	cset = kmalloc(sizeof(*cset), GFP_KERNEL);

	if (!cset)

		return NULL;



	/* Allocate all the cg_cgroup_link objects that we'll need */

	if (allocate_cg_links(root_count, &tmp_cg_links) < 0) {

		kfree(res);

		kfree(cset);

		return NULL;

	}



	atomic_set(&res->refcount, 1);

	INIT_LIST_HEAD(&res->cg_links);

	INIT_LIST_HEAD(&res->tasks);

	INIT_HLIST_NODE(&res->hlist);

	atomic_set(&cset->refcount, 1);

	INIT_LIST_HEAD(&cset->cg_links);

	INIT_LIST_HEAD(&cset->tasks);

	INIT_HLIST_NODE(&cset->hlist);



	/* Copy the set of subsystem state objects generated in

	 * find_existing_css_set() */

	memcpy(res->subsys, template, sizeof(res->subsys));

	memcpy(cset->subsys, template, sizeof(cset->subsys));



	write_lock(&css_set_lock);

	/* Add reference counts and links from the new css_set. */

	list_for_each_entry(link, &oldcg->cg_links, cg_link_list) {

	list_for_each_entry(link, &old_cset->cg_links, cg_link_list) {

		struct cgroup *c = link->cgrp;

		if (c->root == cgrp->root)

			c = cgrp;

		link_css_set(&tmp_cg_links, res, c);

		link_css_set(&tmp_cg_links, cset, c);

	}



	BUG_ON(!list_empty(&tmp_cg_links));
@@ -687,12 +688,12 @@ static struct css_set *find_css_set( 
	css_set_count++;



	/* Add this cgroup group to the hash table */

	key = css_set_hash(res->subsys);

	hash_add(css_set_table, &res->hlist, key);

	key = css_set_hash(cset->subsys);

	hash_add(css_set_table, &cset->hlist, key);



	write_unlock(&css_set_lock);



	return res;

	return cset;

}



/*
@@ -702,7 +703,7 @@ static struct css_set *find_css_set( 
static struct cgroup *task_cgroup_from_root(struct task_struct *task,

					    struct cgroupfs_root *root)

{

	struct css_set *css;

	struct css_set *cset;

	struct cgroup *res = NULL;



	BUG_ON(!mutex_is_locked(&cgroup_mutex));
@@ -712,12 +713,12 @@ static struct cgroup *task_cgroup_from_root(struct task_struct *task, 
	 * task can't change groups, so the only thing that can happen

	 * is that it exits and its css is set back to init_css_set.

	 */

	css = task->cgroups;

	if (css == &init_css_set) {

	cset = task->cgroups;

	if (cset == &init_css_set) {

		res = &root->top_cgroup;

	} else {

		struct cg_cgroup_link *link;

		list_for_each_entry(link, &css->cg_links, cg_link_list) {

		list_for_each_entry(link, &cset->cg_links, cg_link_list) {

			struct cgroup *c = link->cgrp;

			if (c->root == root) {

				res = c;
@@ -1608,7 +1609,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, 
		struct cgroupfs_root *existing_root;

		const struct cred *cred;

		int i;

		struct css_set *cg;

		struct css_set *cset;



		BUG_ON(sb->s_root != NULL);
@@ -1666,8 +1667,8 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, 
		/* Link the top cgroup in this hierarchy into all

		 * the css_set objects */

		write_lock(&css_set_lock);

		hash_for_each(css_set_table, i, cg, hlist)

			link_css_set(&tmp_cg_links, cg, root_cgrp);

		hash_for_each(css_set_table, i, cset, hlist)

			link_css_set(&tmp_cg_links, cset, root_cgrp);

		write_unlock(&css_set_lock);



		free_cg_links(&tmp_cg_links);
@@ -1944,10 +1945,11 @@ EXPORT_SYMBOL_GPL(cgroup_taskset_size); 
 *

 * Must be called with cgroup_mutex and threadgroup locked.

 */

static void cgroup_task_migrate(struct cgroup *oldcgrp,

				struct task_struct *tsk, struct css_set *newcg)

static void cgroup_task_migrate(struct cgroup *old_cgrp,

				struct task_struct *tsk,

				struct css_set *new_cset)

{

	struct css_set *oldcg;

	struct css_set *old_cset;



	/*

	 * We are synchronized through threadgroup_lock() against PF_EXITING
@@ -1955,25 +1957,25 @@ static void cgroup_task_migrate(struct cgroup *oldcgrp, 
	 * css_set to init_css_set and dropping the old one.

	 */

	WARN_ON_ONCE(tsk->flags & PF_EXITING);

	oldcg = tsk->cgroups;

	old_cset = tsk->cgroups;



	task_lock(tsk);

	rcu_assign_pointer(tsk->cgroups, newcg);

	rcu_assign_pointer(tsk->cgroups, new_cset);

	task_unlock(tsk);



	/* Update the css_set linked lists if we're using them */

	write_lock(&css_set_lock);

	if (!list_empty(&tsk->cg_list))

		list_move(&tsk->cg_list, &newcg->tasks);

		list_move(&tsk->cg_list, &new_cset->tasks);

	write_unlock(&css_set_lock);



	/*

	 * We just gained a reference on oldcg by taking it from the task. As

	 * trading it for newcg is protected by cgroup_mutex, we're safe to drop

	 * it here; it will be freed under RCU.

	 * We just gained a reference on old_cset by taking it from the

	 * task. As trading it for new_cset is protected by cgroup_mutex,

	 * we're safe to drop it here; it will be freed under RCU.

	 */

	set_bit(CGRP_RELEASABLE, &oldcgrp->flags);

	put_css_set(oldcg);

	set_bit(CGRP_RELEASABLE, &old_cgrp->flags);

	put_css_set(old_cset);

}



/**
@@ -2925,7 +2927,7 @@ static void cgroup_advance_iter(struct cgroup *cgrp, 
{

	struct list_head *l = it->cg_link;

	struct cg_cgroup_link *link;

	struct css_set *cg;

	struct css_set *cset;



	/* Advance to the next non-empty css_set */

	do {
@@ -2935,10 +2937,10 @@ static void cgroup_advance_iter(struct cgroup *cgrp, 
			return;

		}

		link = list_entry(l, struct cg_cgroup_link, cgrp_link_list);

		cg = link->cg;

	} while (list_empty(&cg->tasks));

		cset = link->cg;

	} while (list_empty(&cset->tasks));

	it->cg_link = l;

	it->task = cg->tasks.next;

	it->task = cset->tasks.next;

}



/*
@@ -4516,7 +4518,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) 
	struct cgroup_subsys_state *css;

	int i, ret;

	struct hlist_node *tmp;

	struct css_set *cg;

	struct css_set *cset;

	unsigned long key;



	/* check name and function validity */
@@ -4583,17 +4585,17 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) 
	 * this is all done under the css_set_lock.

	 */

	write_lock(&css_set_lock);

	hash_for_each_safe(css_set_table, i, tmp, cg, hlist) {

	hash_for_each_safe(css_set_table, i, tmp, cset, hlist) {

		/* skip entries that we already rehashed */

		if (cg->subsys[ss->subsys_id])

		if (cset->subsys[ss->subsys_id])

			continue;

		/* remove existing entry */

		hash_del(&cg->hlist);

		hash_del(&cset->hlist);

		/* set new value */

		cg->subsys[ss->subsys_id] = css;

		cset->subsys[ss->subsys_id] = css;

		/* recompute hash and restore entry */

		key = css_set_hash(cg->subsys);

		hash_add(css_set_table, &cg->hlist, key);

		key = css_set_hash(cset->subsys);

		hash_add(css_set_table, &cset->hlist, key);

	}

	write_unlock(&css_set_lock);
@@ -4653,13 +4655,13 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) 
	 */

	write_lock(&css_set_lock);

	list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) {

		struct css_set *cg = link->cg;

		struct css_set *cset = link->cg;

		unsigned long key;



		hash_del(&cg->hlist);

		cg->subsys[ss->subsys_id] = NULL;

		key = css_set_hash(cg->subsys);

		hash_add(css_set_table, &cg->hlist, key);

		hash_del(&cset->hlist);

		cset->subsys[ss->subsys_id] = NULL;

		key = css_set_hash(cset->subsys);

		hash_add(css_set_table, &cset->hlist, key);

	}

	write_unlock(&css_set_lock);
@@ -5006,7 +5008,7 @@ void cgroup_post_fork(struct task_struct *child) 
 */

void cgroup_exit(struct task_struct *tsk, int run_callbacks)

{

	struct css_set *cg;

	struct css_set *cset;

	int i;



	/*
@@ -5023,7 +5025,7 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks) 


	/* Reassign the task to the init_css_set. */

	task_lock(tsk);

	cg = tsk->cgroups;

	cset = tsk->cgroups;

	tsk->cgroups = &init_css_set;



	if (run_callbacks && need_forkexit_callback) {
@@ -5036,7 +5038,7 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks) 


			if (ss->exit) {

				struct cgroup *old_cgrp =

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

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

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

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

			}
@@ -5044,7 +5046,7 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks) 
	}

	task_unlock(tsk);



	put_css_set_taskexit(cg);

	put_css_set_taskexit(cset);

}



static void check_for_release(struct cgroup *cgrp)
@@ -5453,12 +5455,12 @@ static int current_css_set_cg_links_read(struct cgroup *cont, 
					 struct seq_file *seq)

{

	struct cg_cgroup_link *link;

	struct css_set *cg;

	struct css_set *cset;



	read_lock(&css_set_lock);

	rcu_read_lock();

	cg = rcu_dereference(current->cgroups);

	list_for_each_entry(link, &cg->cg_links, cg_link_list) {

	cset = rcu_dereference(current->cgroups);

	list_for_each_entry(link, &cset->cg_links, cg_link_list) {

		struct cgroup *c = link->cgrp;

		const char *name;
@@ -5483,11 +5485,11 @@ static int cgroup_css_links_read(struct cgroup *cont, 


	read_lock(&css_set_lock);

	list_for_each_entry(link, &cont->css_sets, cgrp_link_list) {

		struct css_set *cg = link->cg;

		struct css_set *cset = link->cg;

		struct task_struct *task;

		int count = 0;

		seq_printf(seq, "css_set %p\n", cg);

		list_for_each_entry(task, &cg->tasks, cg_list) {

		seq_printf(seq, "css_set %p\n", cset);

		list_for_each_entry(task, &cset->tasks, cg_list) {

			if (count++ > MAX_TASKS_SHOWN_PER_CSS) {

				seq_puts(seq, "  ...\n");

				break;