Commit f392e51c authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: update cgroup->subsys_mask to ->child_subsys_mask and restore cgroup_root->subsys_mask 



94419627 ("cgroup: move ->subsys_mask from cgroupfs_root to
cgroup") moved ->subsys_mask from cgroup_root to cgroup to prepare for
the unified hierarhcy; however, it turns out that carrying the
subsys_mask of the children in the parent, instead of itself, is a lot
more natural.  This patch restores cgroup_root->subsys_mask and morphs
cgroup->subsys_mask into cgroup->child_subsys_mask.

* Uses of root->cgrp.subsys_mask are restored to root->subsys_mask.

* Remove automatic setting and clearing of cgrp->subsys_mask and
  instead just inherit ->child_subsys_mask from the parent during
  cgroup creation.  Note that this doesn't affect any current
  behaviors.

* Undo __kill_css() separation.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent ea8fd3b4

include/linux/cgroup.h

+5 −2
Original line number Diff line number Diff line
@@ -173,8 +173,8 @@ struct cgroup { 
	 */

	u64 serial_nr;



	/* The bitmask of subsystems attached to this cgroup */

	unsigned long subsys_mask;

	/* the bitmask of subsystems enabled on the child cgroups */

	unsigned long child_subsys_mask;



	/* Private pointers for each registered subsystem */

	struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
@@ -282,6 +282,9 @@ enum { 
struct cgroup_root {

	struct kernfs_root *kf_root;



	/* The bitmask of subsystems attached to this hierarchy */

	unsigned long subsys_mask;



	/* Unique id for this hierarchy. */

	int hierarchy_id;

kernel/cgroup.c

+27 −37
Original line number Diff line number Diff line
@@ -529,7 +529,7 @@ static struct css_set *find_existing_css_set(struct css_set *old_cset, 
	 * won't change, so no need for locking.

	 */

	for_each_subsys(ss, i) {

		if (root->cgrp.subsys_mask & (1UL << i)) {

		if (root->subsys_mask & (1UL << i)) {

			/* Subsystem is in this hierarchy. So we want

			 * the subsystem state from the new

			 * cgroup */
@@ -742,7 +742,7 @@ static void cgroup_destroy_root(struct cgroup_root *root) 
	BUG_ON(!list_empty(&cgrp->children));



	/* Rebind all subsystems back to the default hierarchy */

	rebind_subsystems(&cgrp_dfl_root, cgrp->subsys_mask);

	rebind_subsystems(&cgrp_dfl_root, root->subsys_mask);



	/*

	 * Release all the links from cset_links to this hierarchy's
@@ -1050,8 +1050,11 @@ static int rebind_subsystems(struct cgroup_root *dst_root, 
		ss->root = dst_root;

		css->cgroup = &dst_root->cgrp;



		src_root->cgrp.subsys_mask &= ~(1 << ssid);

		dst_root->cgrp.subsys_mask |= 1 << ssid;

		src_root->subsys_mask &= ~(1 << ssid);

		src_root->cgrp.child_subsys_mask &= ~(1 << ssid);



		dst_root->subsys_mask |= 1 << ssid;

		dst_root->cgrp.child_subsys_mask |= 1 << ssid;



		if (ss->bind)

			ss->bind(css);
@@ -1069,7 +1072,7 @@ static int cgroup_show_options(struct seq_file *seq, 
	int ssid;



	for_each_subsys(ss, ssid)

		if (root->cgrp.subsys_mask & (1 << ssid))

		if (root->subsys_mask & (1 << ssid))

			seq_printf(seq, ",%s", ss->name);

	if (root->flags & CGRP_ROOT_SANE_BEHAVIOR)

		seq_puts(seq, ",sane_behavior");
@@ -1273,12 +1276,12 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) 
	if (ret)

		goto out_unlock;



	if (opts.subsys_mask != root->cgrp.subsys_mask || opts.release_agent)

	if (opts.subsys_mask != root->subsys_mask || opts.release_agent)

		pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",

			   task_tgid_nr(current), current->comm);



	added_mask = opts.subsys_mask & ~root->cgrp.subsys_mask;

	removed_mask = root->cgrp.subsys_mask & ~opts.subsys_mask;

	added_mask = opts.subsys_mask & ~root->subsys_mask;

	removed_mask = root->subsys_mask & ~opts.subsys_mask;



	/* Don't allow flags or name to change at remount */

	if (((opts.flags ^ root->flags) & CGRP_ROOT_OPTION_MASK) ||
@@ -1535,7 +1538,7 @@ retry: 
		 * subsystems) then they must match.

		 */

		if ((opts.subsys_mask || opts.none) &&

		    (opts.subsys_mask != root->cgrp.subsys_mask)) {

		    (opts.subsys_mask != root->subsys_mask)) {

			if (!name_match)

				continue;

			ret = -EBUSY;
@@ -3658,8 +3661,6 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss) 
	cgroup_get(cgrp);

	css_get(css->parent);



	cgrp->subsys_mask |= 1 << ss->id;



	if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&

	    parent->parent) {

		pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
@@ -3780,13 +3781,15 @@ static long cgroup_create(struct cgroup *parent, const char *name, 


	/* let's create and online css's */

	for_each_subsys(ss, ssid) {

		if (root->cgrp.subsys_mask & (1 << ssid)) {

		if (parent->child_subsys_mask & (1 << ssid)) {

			err = create_css(cgrp, ss);

			if (err)

				goto err_destroy;

		}

	}



	cgrp->child_subsys_mask = parent->child_subsys_mask;



	kernfs_activate(kn);



	mutex_unlock(&cgroup_mutex);
@@ -3882,7 +3885,16 @@ static void css_killed_ref_fn(struct percpu_ref *ref) 
	queue_work(cgroup_destroy_wq, &css->destroy_work);

}



static void __kill_css(struct cgroup_subsys_state *css)

/**

 * kill_css - destroy a css

 * @css: css to destroy

 *

 * This function initiates destruction of @css by removing cgroup interface

 * files and putting its base reference.  ->css_offline() will be invoked

 * asynchronously once css_tryget() is guaranteed to fail and when the

 * reference count reaches zero, @css will be released.

 */

static void kill_css(struct cgroup_subsys_state *css)

{

	lockdep_assert_held(&cgroup_tree_mutex);
@@ -3911,28 +3923,6 @@ static void __kill_css(struct cgroup_subsys_state *css) 
	percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);

}



/**

 * kill_css - destroy a css

 * @css: css to destroy

 *

 * This function initiates destruction of @css by removing cgroup interface

 * files and putting its base reference.  ->css_offline() will be invoked

 * asynchronously once css_tryget() is guaranteed to fail and when the

 * reference count reaches zero, @css will be released.

 */

static void kill_css(struct cgroup_subsys_state *css)

{

	struct cgroup *cgrp = css->cgroup;



	lockdep_assert_held(&cgroup_tree_mutex);



	/* if already killed, noop */

	if (cgrp->subsys_mask & (1 << css->ss->id)) {

		cgrp->subsys_mask &= ~(1 << css->ss->id);

		__kill_css(css);

	}

}



/**

 * cgroup_destroy_locked - the first stage of cgroup destruction

 * @cgrp: cgroup to be destroyed
@@ -4145,7 +4135,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) 


	BUG_ON(online_css(css));



	cgrp_dfl_root.cgrp.subsys_mask |= 1 << ss->id;

	cgrp_dfl_root.subsys_mask |= 1 << ss->id;



	mutex_unlock(&cgroup_mutex);

	mutex_unlock(&cgroup_tree_mutex);
@@ -4302,7 +4292,7 @@ int proc_cgroup_show(struct seq_file *m, void *v) 


		seq_printf(m, "%d:", root->hierarchy_id);

		for_each_subsys(ss, ssid)

			if (root->cgrp.subsys_mask & (1 << ssid))

			if (root->subsys_mask & (1 << ssid))

				seq_printf(m, "%s%s", count++ ? "," : "", ss->name);

		if (strlen(root->name))

			seq_printf(m, "%sname=%s", count ? "," : "",

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