Merge branch 'for-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup updates from Tejun Heo:
 "A lot of activities on the cgroup front.  Most changes aren't visible
  to userland at all at this point and are laying foundation for the
  planned unified hierarchy.

   - The biggest change is decoupling the lifetime management of css
     (cgroup_subsys_state) from that of cgroup's.  Because controllers
     (cpu, memory, block and so on) will need to be dynamically enabled
     and disabled, css which is the association point between a cgroup
     and a controller may come and go dynamically across the lifetime of
     a cgroup.  Till now, css's were created when the associated cgroup
     was created and stayed till the cgroup got destroyed.

     Assumptions around this tight coupling permeated through cgroup
     core and controllers.  These assumptions are gradually removed,
     which consists bulk of patches, and css destruction path is
     completely decoupled from cgroup destruction path.  Note that
     decoupling of creation path is relatively easy on top of these
     changes and the patchset is pending for the next window.

   - cgroup has its own event mechanism cgroup.event_control, which is
     only used by memcg.  It is overly complex trying to achieve high
     flexibility whose benefits seem dubious at best.  Going forward,
     new events will simply generate file modified event and the
     existing mechanism is being made specific to memcg.  This pull
     request contains prepatory patches for such change.

   - Various fixes and cleanups"

Fixed up conflict in kernel/cgroup.c as per Tejun.

* 'for-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (69 commits)
  cgroup: fix cgroup_css() invocation in css_from_id()
  cgroup: make cgroup_write_event_control() use css_from_dir() instead of __d_cgrp()
  cgroup: make cgroup_event hold onto cgroup_subsys_state instead of cgroup
  cgroup: implement CFTYPE_NO_PREFIX
  cgroup: make cgroup_css() take cgroup_subsys * instead and allow NULL subsys
  cgroup: rename cgroup_css_from_dir() to css_from_dir() and update its syntax
  cgroup: fix cgroup_write_event_control()
  cgroup: fix subsystem file accesses on the root cgroup
  cgroup: change cgroup_from_id() to css_from_id()
  cgroup: use css_get() in cgroup_create() to check CSS_ROOT
  cpuset: remove an unncessary forward declaration
  cgroup: RCU protect each cgroup_subsys_state release
  cgroup: move subsys file removal to kill_css()
  cgroup: factor out kill_css()
  cgroup: decouple cgroup_subsys_state destruction from cgroup destruction
  cgroup: replace cgroup->css_kill_cnt with ->nr_css
  cgroup: bounce cgroup_subsys_state ref kill confirmation to a work item
  cgroup: move cgroup->subsys[] assignment to online_css()
  cgroup: reorganize css init / exit paths
  cgroup: add __rcu modifier to cgroup->subsys[]
  ...

1 files changed, 26 insertions, 39 deletions

diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index e8aad69f0d69..c123628d3f84 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -53,22 +53,17 @@ struct dev_cgroup {
 
 static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s)
 {
-	return container_of(s, struct dev_cgroup, css);
-}
-
-static inline struct dev_cgroup *cgroup_to_devcgroup(struct cgroup *cgroup)
-{
-	return css_to_devcgroup(cgroup_subsys_state(cgroup, devices_subsys_id));
+	return s ? container_of(s, struct dev_cgroup, css) : NULL;
 }
 
 static inline struct dev_cgroup *task_devcgroup(struct task_struct *task)
 {
-	return css_to_devcgroup(task_subsys_state(task, devices_subsys_id));
+	return css_to_devcgroup(task_css(task, devices_subsys_id));
 }
 
 struct cgroup_subsys devices_subsys;
 
-static int devcgroup_can_attach(struct cgroup *new_cgrp,
+static int devcgroup_can_attach(struct cgroup_subsys_state *new_css,
 				struct cgroup_taskset *set)
 {
 	struct task_struct *task = cgroup_taskset_first(set);
@@ -193,18 +188,16 @@ static inline bool is_devcg_online(const struct dev_cgroup *devcg)
 /**
  * devcgroup_online - initializes devcgroup's behavior and exceptions based on
  * 		      parent's
- * @cgroup: cgroup getting online
+ * @css: css getting online
  * returns 0 in case of success, error code otherwise
  */
-static int devcgroup_online(struct cgroup *cgroup)
+static int devcgroup_online(struct cgroup_subsys_state *css)
 {
-	struct dev_cgroup *dev_cgroup, *parent_dev_cgroup = NULL;
+	struct dev_cgroup *dev_cgroup = css_to_devcgroup(css);
+	struct dev_cgroup *parent_dev_cgroup = css_to_devcgroup(css_parent(css));
 	int ret = 0;
 
 	mutex_lock(&devcgroup_mutex);
-	dev_cgroup = cgroup_to_devcgroup(cgroup);
-	if (cgroup->parent)
-		parent_dev_cgroup = cgroup_to_devcgroup(cgroup->parent);
 
 	if (parent_dev_cgroup == NULL)
 		dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW;
@@ -219,9 +212,9 @@ static int devcgroup_online(struct cgroup *cgroup)
 	return ret;
 }
 
-static void devcgroup_offline(struct cgroup *cgroup)
+static void devcgroup_offline(struct cgroup_subsys_state *css)
 {
-	struct dev_cgroup *dev_cgroup = cgroup_to_devcgroup(cgroup);
+	struct dev_cgroup *dev_cgroup = css_to_devcgroup(css);
 
 	mutex_lock(&devcgroup_mutex);
 	dev_cgroup->behavior = DEVCG_DEFAULT_NONE;
@@ -231,7 +224,8 @@ static void devcgroup_offline(struct cgroup *cgroup)
 /*
  * called from kernel/cgroup.c with cgroup_lock() held.
  */
-static struct cgroup_subsys_state *devcgroup_css_alloc(struct cgroup *cgroup)
+static struct cgroup_subsys_state *
+devcgroup_css_alloc(struct cgroup_subsys_state *parent_css)
 {
 	struct dev_cgroup *dev_cgroup;
 
@@ -244,11 +238,10 @@ static struct cgroup_subsys_state *devcgroup_css_alloc(struct cgroup *cgroup)
 	return &dev_cgroup->css;
 }
 
-static void devcgroup_css_free(struct cgroup *cgroup)
+static void devcgroup_css_free(struct cgroup_subsys_state *css)
 {
-	struct dev_cgroup *dev_cgroup;
+	struct dev_cgroup *dev_cgroup = css_to_devcgroup(css);
 
-	dev_cgroup = cgroup_to_devcgroup(cgroup);
 	__dev_exception_clean(dev_cgroup);
 	kfree(dev_cgroup);
 }
@@ -291,10 +284,10 @@ static void set_majmin(char *str, unsigned m)
 		sprintf(str, "%u", m);
 }
 
-static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft,
-				struct seq_file *m)
+static int devcgroup_seq_read(struct cgroup_subsys_state *css,
+			      struct cftype *cft, struct seq_file *m)
 {
-	struct dev_cgroup *devcgroup = cgroup_to_devcgroup(cgroup);
+	struct dev_cgroup *devcgroup = css_to_devcgroup(css);
 	struct dev_exception_item *ex;
 	char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN];
 
@@ -394,12 +387,10 @@ static bool may_access(struct dev_cgroup *dev_cgroup,
 static int parent_has_perm(struct dev_cgroup *childcg,
 				  struct dev_exception_item *ex)
 {
-	struct cgroup *pcg = childcg->css.cgroup->parent;
-	struct dev_cgroup *parent;
+	struct dev_cgroup *parent = css_to_devcgroup(css_parent(&childcg->css));
 
-	if (!pcg)
+	if (!parent)
 		return 1;
-	parent = cgroup_to_devcgroup(pcg);
 	return may_access(parent, ex, childcg->behavior);
 }
 
@@ -451,13 +442,13 @@ static void revalidate_active_exceptions(struct dev_cgroup *devcg)
 static int propagate_exception(struct dev_cgroup *devcg_root,
 			       struct dev_exception_item *ex)
 {
-	struct cgroup *root = devcg_root->css.cgroup, *pos;
+	struct cgroup_subsys_state *pos;
 	int rc = 0;
 
 	rcu_read_lock();
 
-	cgroup_for_each_descendant_pre(pos, root) {
-		struct dev_cgroup *devcg = cgroup_to_devcgroup(pos);
+	css_for_each_descendant_pre(pos, &devcg_root->css) {
+		struct dev_cgroup *devcg = css_to_devcgroup(pos);
 
 		/*
 		 * Because devcgroup_mutex is held, no devcg will become
@@ -465,7 +456,7 @@ static int propagate_exception(struct dev_cgroup *devcg_root,
 		 * methods), and online ones are safe to access outside RCU
 		 * read lock without bumping refcnt.
 		 */
-		if (!is_devcg_online(devcg))
+		if (pos == &devcg_root->css || !is_devcg_online(devcg))
 			continue;
 
 		rcu_read_unlock();
@@ -524,15 +515,11 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
 	char temp[12];		/* 11 + 1 characters needed for a u32 */
 	int count, rc = 0;
 	struct dev_exception_item ex;
-	struct cgroup *p = devcgroup->css.cgroup;
-	struct dev_cgroup *parent = NULL;
+	struct dev_cgroup *parent = css_to_devcgroup(css_parent(&devcgroup->css));
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
-	if (p->parent)
-		parent = cgroup_to_devcgroup(p->parent);
-
 	memset(&ex, 0, sizeof(ex));
 	b = buffer;
 
@@ -677,13 +664,13 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
 	return rc;
 }
 
-static int devcgroup_access_write(struct cgroup *cgrp, struct cftype *cft,
-				  const char *buffer)
+static int devcgroup_access_write(struct cgroup_subsys_state *css,
+				  struct cftype *cft, const char *buffer)
 {
 	int retval;
 
 	mutex_lock(&devcgroup_mutex);
-	retval = devcgroup_update_access(cgroup_to_devcgroup(cgrp),
+	retval = devcgroup_update_access(css_to_devcgroup(css),
 					 cft->private, buffer);
 	mutex_unlock(&devcgroup_mutex);
 	return retval;