9 files changed, 187 insertions, 187 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index f46f3c69179c..4b40640240a4 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -614,7 +614,7 @@ u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off)
 {
         struct blkcg_policy *pol = blkcg_policy[pd->plid];
         struct blkcg_gq *pos_blkg;
-        struct cgroup *pos_cgrp;
+        struct cgroup_subsys_state *pos_css;
         u64 sum;
 
         lockdep_assert_held(pd->blkg->q->queue_lock);
@@ -622,7 +622,7 @@ u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off)
         sum = blkg_stat_read((void *)pd + off);
 
         rcu_read_lock();
-        blkg_for_each_descendant_pre(pos_blkg, pos_cgrp, pd_to_blkg(pd)) {
+        blkg_for_each_descendant_pre(pos_blkg, pos_css, pd_to_blkg(pd)) {
                 struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol);
                 struct blkg_stat *stat = (void *)pos_pd + off;
 
@@ -649,7 +649,7 @@ struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
 {
         struct blkcg_policy *pol = blkcg_policy[pd->plid];
         struct blkcg_gq *pos_blkg;
-        struct cgroup *pos_cgrp;
+        struct cgroup_subsys_state *pos_css;
         struct blkg_rwstat sum;
         int i;
 
@@ -658,7 +658,7 @@ struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
         sum = blkg_rwstat_read((void *)pd + off);
 
         rcu_read_lock();
-        blkg_for_each_descendant_pre(pos_blkg, pos_cgrp, pd_to_blkg(pd)) {
+        blkg_for_each_descendant_pre(pos_blkg, pos_css, pd_to_blkg(pd)) {
                 struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol);
                 struct blkg_rwstat *rwstat = (void *)pos_pd + off;
                 struct blkg_rwstat tmp;
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index b6802c46d68f..855538630300 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -184,11 +184,6 @@ static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
         return css ? container_of(css, struct blkcg, css) : NULL;
 }
 
-static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup)
-{
-        return css_to_blkcg(cgroup_css(cgroup, blkio_subsys_id));
-}
-
 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
 {
         return css_to_blkcg(task_css(tsk, blkio_subsys_id));
@@ -289,32 +284,31 @@ struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
 /**
  * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
  * @d_blkg: loop cursor pointing to the current descendant
- * @pos_cgrp: used for iteration
+ * @pos_css: used for iteration
  * @p_blkg: target blkg to walk descendants of
  *
  * Walk @c_blkg through the descendants of @p_blkg.  Must be used with RCU
  * read locked.  If called under either blkcg or queue lock, the iteration
  * is guaranteed to include all and only online blkgs.  The caller may
- * update @pos_cgrp by calling cgroup_rightmost_descendant() to skip
- * subtree.
+ * update @pos_css by calling css_rightmost_descendant() to skip subtree.
  */
-#define blkg_for_each_descendant_pre(d_blkg, pos_cgrp, p_blkg)          \
-        cgroup_for_each_descendant_pre((pos_cgrp), (p_blkg)->blkcg->css.cgroup) \
-                if (((d_blkg) = __blkg_lookup(cgroup_to_blkcg(pos_cgrp), \
+#define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg)           \
+        css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css)   \
+                if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
                                               (p_blkg)->q, false)))
 
 /**
  * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
  * @d_blkg: loop cursor pointing to the current descendant
- * @pos_cgrp: used for iteration
+ * @pos_css: used for iteration
  * @p_blkg: target blkg to walk descendants of
  *
  * Similar to blkg_for_each_descendant_pre() but performs post-order
  * traversal instead.  Synchronization rules are the same.
  */
-#define blkg_for_each_descendant_post(d_blkg, pos_cgrp, p_blkg)         \
-        cgroup_for_each_descendant_post((pos_cgrp), (p_blkg)->blkcg->css.cgroup) \
-                if (((d_blkg) = __blkg_lookup(cgroup_to_blkcg(pos_cgrp), \
+#define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg)          \
+        css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css)  \
+                if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
                                               (p_blkg)->q, false)))
 
 /**
@@ -577,7 +571,6 @@ static inline int blkcg_activate_policy(struct request_queue *q,
 static inline void blkcg_deactivate_policy(struct request_queue *q,
                                            const struct blkcg_policy *pol) { }
 
-static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; }
 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
 
 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 88bcfb651b0b..8cefa7f8590e 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1349,7 +1349,7 @@ static int tg_set_conf(struct cgroup_subsys_state *css, struct cftype *cft,
         struct throtl_grp *tg;
         struct throtl_service_queue *sq;
         struct blkcg_gq *blkg;
-        struct cgroup *pos_cgrp;
+        struct cgroup_subsys_state *pos_css;
         int ret;
 
         ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
@@ -1380,7 +1380,7 @@ static int tg_set_conf(struct cgroup_subsys_state *css, struct cftype *cft,
          * blk-throttle.
          */
         tg_update_has_rules(tg);
-        blkg_for_each_descendant_pre(blkg, pos_cgrp, ctx.blkg)
+        blkg_for_each_descendant_pre(blkg, pos_css, ctx.blkg)
                 tg_update_has_rules(blkg_to_tg(blkg));
 
         /*
@@ -1623,7 +1623,7 @@ void blk_throtl_drain(struct request_queue *q)
 {
         struct throtl_data *td = q->td;
         struct blkcg_gq *blkg;
-        struct cgroup *pos_cgrp;
+        struct cgroup_subsys_state *pos_css;
         struct bio *bio;
         int rw;
 
@@ -1636,7 +1636,7 @@ void blk_throtl_drain(struct request_queue *q)
          * better to walk service_queue tree directly but blkg walk is
          * easier.
          */
-        blkg_for_each_descendant_post(blkg, pos_cgrp, td->queue->root_blkg)
+        blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg)
                 tg_drain_bios(&blkg_to_tg(blkg)->service_queue);
 
         tg_drain_bios(&td_root_tg(td)->service_queue);
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index c288bce428f8..4bc22f4a1abb 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -779,68 +779,72 @@ static inline struct cgroup *cgroup_from_id(struct cgroup_subsys *ss, int id)
         return idr_find(&ss->root->cgroup_idr, id);
 }
 
-struct cgroup *cgroup_next_child(struct cgroup *pos, struct cgroup *cgrp);
+struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
+                                           struct cgroup_subsys_state *parent);
 
 /**
- * cgroup_for_each_child - iterate through children of a cgroup
- * @pos: the cgroup * to use as the loop cursor
- * @cgrp: cgroup whose children to walk
+ * css_for_each_child - iterate through children of a css
+ * @pos: the css * to use as the loop cursor
+ * @parent: css whose children to walk
  *
- * Walk @cgrp's children.  Must be called under rcu_read_lock().  A child
- * cgroup which hasn't finished ->css_online() or already has finished
+ * Walk @parent's children.  Must be called under rcu_read_lock().  A child
+ * css which hasn't finished ->css_online() or already has finished
  * ->css_offline() may show up during traversal and it's each subsystem's
  * responsibility to verify that each @pos is alive.
  *
  * If a subsystem synchronizes against the parent in its ->css_online() and
- * before starting iterating, a cgroup which finished ->css_online() is
+ * before starting iterating, a css which finished ->css_online() is
  * guaranteed to be visible in the future iterations.
  *
  * It is allowed to temporarily drop RCU read lock during iteration.  The
  * caller is responsible for ensuring that @pos remains accessible until
  * the start of the next iteration by, for example, bumping the css refcnt.
  */
-#define cgroup_for_each_child(pos, cgrp)                                \
-        for ((pos) = cgroup_next_child(NULL, (cgrp)); (pos);            \
-             (pos) = cgroup_next_child((pos), (cgrp)))
+#define css_for_each_child(pos, parent)                                 \
+        for ((pos) = css_next_child(NULL, (parent)); (pos);             \
+             (pos) = css_next_child((pos), (parent)))
 
-struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
-                                          struct cgroup *cgroup);
-struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos);
+struct cgroup_subsys_state *
+css_next_descendant_pre(struct cgroup_subsys_state *pos,
+                        struct cgroup_subsys_state *css);
+
+struct cgroup_subsys_state *
+css_rightmost_descendant(struct cgroup_subsys_state *pos);
 
 /**
- * cgroup_for_each_descendant_pre - pre-order walk of a cgroup's descendants
- * @pos: the cgroup * to use as the loop cursor
- * @cgroup: cgroup whose descendants to walk
+ * css_for_each_descendant_pre - pre-order walk of a css's descendants
+ * @pos: the css * to use as the loop cursor
+ * @root: css whose descendants to walk
  *
- * Walk @cgroup's descendants.  Must be called under rcu_read_lock().  A
- * descendant cgroup which hasn't finished ->css_online() or already has
+ * Walk @root's descendants.  Must be called under rcu_read_lock().  A
+ * descendant css which hasn't finished ->css_online() or already has
  * finished ->css_offline() may show up during traversal and it's each
  * subsystem's responsibility to verify that each @pos is alive.
  *
  * If a subsystem synchronizes against the parent in its ->css_online() and
  * before starting iterating, and synchronizes against @pos on each
- * iteration, any descendant cgroup which finished ->css_online() is
+ * iteration, any descendant css which finished ->css_online() is
  * guaranteed to be visible in the future iterations.
  *
  * In other words, the following guarantees that a descendant can't escape
  * state updates of its ancestors.
  *
- * my_online(@cgrp)
+ * my_online(@css)
  * {
- *      Lock @cgrp->parent and @cgrp;
- *      Inherit state from @cgrp->parent;
+ *      Lock @css's parent and @css;
+ *      Inherit state from the parent;
  *      Unlock both.
  * }
  *
- * my_update_state(@cgrp)
+ * my_update_state(@css)
  * {
- *      Lock @cgrp;
- *      Update @cgrp's state;
- *      Unlock @cgrp;
+ *      Lock @css;
+ *      Update @css's state;
+ *      Unlock @css;
  *
- *      cgroup_for_each_descendant_pre(@pos, @cgrp) {
+ *      css_for_each_descendant_pre(@pos, @css) {
  *              Lock @pos;
- *              Verify @pos is alive and inherit state from @pos->parent;
+ *              Verify @pos is alive and inherit state from @pos's parent;
  *              Unlock @pos;
  *      }
  * }
@@ -851,8 +855,7 @@ struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos);
  * visible by walking order and, as long as inheriting operations to the
  * same @pos are atomic to each other, multiple updates racing each other
  * still result in the correct state.  It's guaranateed that at least one
- * inheritance happens for any cgroup after the latest update to its
- * parent.
+ * inheritance happens for any css after the latest update to its parent.
  *
  * If checking parent's state requires locking the parent, each inheriting
  * iteration should lock and unlock both @pos->parent and @pos.
@@ -865,25 +868,26 @@ struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos);
  * caller is responsible for ensuring that @pos remains accessible until
  * the start of the next iteration by, for example, bumping the css refcnt.
  */
-#define cgroup_for_each_descendant_pre(pos, cgroup)                     \
-        for (pos = cgroup_next_descendant_pre(NULL, (cgroup)); (pos);   \
-             pos = cgroup_next_descendant_pre((pos), (cgroup)))
+#define css_for_each_descendant_pre(pos, css)                           \
+        for ((pos) = css_next_descendant_pre(NULL, (css)); (pos);       \
+             (pos) = css_next_descendant_pre((pos), (css)))
 
-struct cgroup *cgroup_next_descendant_post(struct cgroup *pos,
-                                           struct cgroup *cgroup);
+struct cgroup_subsys_state *
+css_next_descendant_post(struct cgroup_subsys_state *pos,
+                         struct cgroup_subsys_state *css);
 
 /**
- * cgroup_for_each_descendant_post - post-order walk of a cgroup's descendants
- * @pos: the cgroup * to use as the loop cursor
- * @cgroup: cgroup whose descendants to walk
+ * css_for_each_descendant_post - post-order walk of a css's descendants
+ * @pos: the css * to use as the loop cursor
+ * @css: css whose descendants to walk
  *
- * Similar to cgroup_for_each_descendant_pre() but performs post-order
+ * Similar to css_for_each_descendant_pre() but performs post-order
  * traversal instead.  Note that the walk visibility guarantee described in
  * pre-order walk doesn't apply the same to post-order walks.
  */
-#define cgroup_for_each_descendant_post(pos, cgroup)                    \
-        for (pos = cgroup_next_descendant_post(NULL, (cgroup)); (pos);  \
-             pos = cgroup_next_descendant_post((pos), (cgroup)))
+#define css_for_each_descendant_post(pos, css)                          \
+        for ((pos) = css_next_descendant_post(NULL, (css)); (pos);      \
+             (pos) = css_next_descendant_post((pos), (css)))
 
 /* A cgroup_iter should be treated as an opaque object */
 struct cgroup_iter {
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 2b7354faaca7..91eac33fac86 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2814,8 +2814,8 @@ static void cgroup_cfts_prepare(void)
         /*
          * Thanks to the entanglement with vfs inode locking, we can't walk
          * the existing cgroups under cgroup_mutex and create files.
-         * Instead, we use cgroup_for_each_descendant_pre() and drop RCU
-         * read lock before calling cgroup_addrm_files().
+         * Instead, we use css_for_each_descendant_pre() and drop RCU read
+         * lock before calling cgroup_addrm_files().
          */
         mutex_lock(&cgroup_mutex);
 }
@@ -2825,10 +2825,11 @@ static int cgroup_cfts_commit(struct cftype *cfts, bool is_add)
 {
         LIST_HEAD(pending);
         struct cgroup_subsys *ss = cfts[0].ss;
-        struct cgroup *cgrp, *root = &ss->root->top_cgroup;
+        struct cgroup *root = &ss->root->top_cgroup;
         struct super_block *sb = ss->root->sb;
         struct dentry *prev = NULL;
         struct inode *inode;
+        struct cgroup_subsys_state *css;
         u64 update_before;
         int ret = 0;
 
@@ -2861,7 +2862,9 @@ static int cgroup_cfts_commit(struct cftype *cfts, bool is_add)
 
         /* add/rm files for all cgroups created before */
         rcu_read_lock();
-        cgroup_for_each_descendant_pre(cgrp, root) {
+        css_for_each_descendant_pre(css, cgroup_css(root, ss->subsys_id)) {
+                struct cgroup *cgrp = css->cgroup;
+
                 if (cgroup_is_dead(cgrp))
                         continue;
 
@@ -3037,17 +3040,21 @@ static void cgroup_enable_task_cg_lists(void)
 }
 
 /**
- * cgroup_next_child - find the next child of a given cgroup
- * @pos: the current position (%NULL to initiate traversal)
- * @cgrp: cgroup whose descendants to walk
+ * css_next_child - find the next child of a given css
+ * @pos_css: the current position (%NULL to initiate traversal)
+ * @parent_css: css whose children to walk
  *
- * This function returns the next child of @cgrp and should be called under
- * RCU read lock.  The only requirement is that @cgrp and @pos are
- * accessible.  The next sibling is guaranteed to be returned regardless of
- * their states.
+ * This function returns the next child of @parent_css and should be called
+ * under RCU read lock.  The only requirement is that @parent_css and
+ * @pos_css are accessible.  The next sibling is guaranteed to be returned
+ * regardless of their states.
  */
-struct cgroup *cgroup_next_child(struct cgroup *pos, struct cgroup *cgrp)
+struct cgroup_subsys_state *
+css_next_child(struct cgroup_subsys_state *pos_css,
+               struct cgroup_subsys_state *parent_css)
 {
+        struct cgroup *pos = pos_css ? pos_css->cgroup : NULL;
+        struct cgroup *cgrp = parent_css->cgroup;
         struct cgroup *next;
 
         WARN_ON_ONCE(!rcu_read_lock_held());
@@ -3081,59 +3088,64 @@ struct cgroup *cgroup_next_child(struct cgroup *pos, struct cgroup *cgrp)
                                 break;
         }
 
-        if (&next->sibling != &cgrp->children)
-                return next;
-        return NULL;
+        if (&next->sibling == &cgrp->children)
+                return NULL;
+
+        if (parent_css->ss)
+                return cgroup_css(next, parent_css->ss->subsys_id);
+        else
+                return &next->dummy_css;
 }
-EXPORT_SYMBOL_GPL(cgroup_next_child);
+EXPORT_SYMBOL_GPL(css_next_child);
 
 /**
- * cgroup_next_descendant_pre - find the next descendant for pre-order walk
+ * css_next_descendant_pre - find the next descendant for pre-order walk
  * @pos: the current position (%NULL to initiate traversal)
- * @cgroup: cgroup whose descendants to walk
+ * @root: css whose descendants to walk
  *
- * To be used by cgroup_for_each_descendant_pre().  Find the next
- * descendant to visit for pre-order traversal of @cgroup's descendants.
+ * To be used by css_for_each_descendant_pre().  Find the next descendant
+ * to visit for pre-order traversal of @root's descendants.
  *
  * While this function requires RCU read locking, it doesn't require the
  * whole traversal to be contained in a single RCU critical section.  This
  * function will return the correct next descendant as long as both @pos
- * and @cgroup are accessible and @pos is a descendant of @cgroup.
+ * and @root are accessible and @pos is a descendant of @root.
  */
-struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
-                                          struct cgroup *cgroup)
+struct cgroup_subsys_state *
+css_next_descendant_pre(struct cgroup_subsys_state *pos,
+                        struct cgroup_subsys_state *root)
 {
-        struct cgroup *next;
+        struct cgroup_subsys_state *next;
 
         WARN_ON_ONCE(!rcu_read_lock_held());
 
-        /* if first iteration, pretend we just visited @cgroup */
+        /* if first iteration, pretend we just visited @root */
         if (!pos)
-                pos = cgroup;
+                pos = root;
 
         /* visit the first child if exists */
-        next = cgroup_next_child(NULL, pos);
+        next = css_next_child(NULL, pos);
         if (next)
                 return next;
 
         /* no child, visit my or the closest ancestor's next sibling */
-        while (pos != cgroup) {
-                next = cgroup_next_child(pos, pos->parent);
+        while (pos != root) {
+                next = css_next_child(pos, css_parent(pos));
                 if (next)
                         return next;
-                pos = pos->parent;
+                pos = css_parent(pos);
         }
 
         return NULL;
 }
-EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre);
+EXPORT_SYMBOL_GPL(css_next_descendant_pre);
 
 /**
- * cgroup_rightmost_descendant - return the rightmost descendant of a cgroup
- * @pos: cgroup of interest
+ * css_rightmost_descendant - return the rightmost descendant of a css
+ * @pos: css of interest
  *
- * Return the rightmost descendant of @pos.  If there's no descendant,
- * @pos is returned.  This can be used during pre-order traversal to skip
+ * Return the rightmost descendant of @pos.  If there's no descendant, @pos
+ * is returned.  This can be used during pre-order traversal to skip
  * subtree of @pos.
  *
  * While this function requires RCU read locking, it doesn't require the
@@ -3141,9 +3153,10 @@ EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre);
  * function will return the correct rightmost descendant as long as @pos is
  * accessible.
  */
-struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos)
+struct cgroup_subsys_state *
+css_rightmost_descendant(struct cgroup_subsys_state *pos)
 {
-        struct cgroup *last, *tmp;
+        struct cgroup_subsys_state *last, *tmp;
 
         WARN_ON_ONCE(!rcu_read_lock_held());
 
@@ -3151,62 +3164,64 @@ struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos)
                 last = pos;
                 /* ->prev isn't RCU safe, walk ->next till the end */
                 pos = NULL;
-                cgroup_for_each_child(tmp, last)
+                css_for_each_child(tmp, last)
                         pos = tmp;
         } while (pos);
 
         return last;
 }
-EXPORT_SYMBOL_GPL(cgroup_rightmost_descendant);
+EXPORT_SYMBOL_GPL(css_rightmost_descendant);
 
-static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos)
+static struct cgroup_subsys_state *
+css_leftmost_descendant(struct cgroup_subsys_state *pos)
 {
-        struct cgroup *last;
+        struct cgroup_subsys_state *last;
 
         do {
                 last = pos;
-                pos = cgroup_next_child(NULL, pos);
+                pos = css_next_child(NULL, pos);
         } while (pos);
 
         return last;
 }
 
 /**
- * cgroup_next_descendant_post - find the next descendant for post-order walk
+ * css_next_descendant_post - find the next descendant for post-order walk
  * @pos: the current position (%NULL to initiate traversal)
- * @cgroup: cgroup whose descendants to walk
+ * @root: css whose descendants to walk
  *
- * To be used by cgroup_for_each_descendant_post().  Find the next
- * descendant to visit for post-order traversal of @cgroup's descendants.
+ * To be used by css_for_each_descendant_post().  Find the next descendant
+ * to visit for post-order traversal of @root's descendants.
  *
  * While this function requires RCU read locking, it doesn't require the
  * whole traversal to be contained in a single RCU critical section.  This
  * function will return the correct next descendant as long as both @pos
  * and @cgroup are accessible and @pos is a descendant of @cgroup.
  */
-struct cgroup *cgroup_next_descendant_post(struct cgroup *pos,
-                                           struct cgroup *cgroup)
+struct cgroup_subsys_state *
+css_next_descendant_post(struct cgroup_subsys_state *pos,
+                         struct cgroup_subsys_state *root)
 {
-        struct cgroup *next;
+        struct cgroup_subsys_state *next;
 
         WARN_ON_ONCE(!rcu_read_lock_held());
 
         /* if first iteration, visit the leftmost descendant */
         if (!pos) {
-                next = cgroup_leftmost_descendant(cgroup);
-                return next != cgroup ? next : NULL;
+                next = css_leftmost_descendant(root);
+                return next != root ? next : NULL;
         }
 
         /* if there's an unvisited sibling, visit its leftmost descendant */
-        next = cgroup_next_child(pos, pos->parent);
+        next = css_next_child(pos, css_parent(pos));
         if (next)
-                return cgroup_leftmost_descendant(next);
+                return css_leftmost_descendant(next);
 
         /* no sibling left, visit parent */
-        next = pos->parent;
-        return next != cgroup ? next : NULL;
+        next = css_parent(pos);
+        return next != root ? next : NULL;
 }
-EXPORT_SYMBOL_GPL(cgroup_next_descendant_post);
+EXPORT_SYMBOL_GPL(css_next_descendant_post);
 
 void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it)
         __acquires(css_set_lock)
@@ -4549,9 +4564,9 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
         /*
          * Mark @cgrp dead.  This prevents further task migration and child
          * creation by disabling cgroup_lock_live_group().  Note that
-         * CGRP_DEAD assertion is depended upon by cgroup_next_child() to
+         * CGRP_DEAD assertion is depended upon by css_next_child() to
          * resume iteration after dropping RCU read lock.  See
-         * cgroup_next_child() for details.
+         * css_next_child() for details.
          */
         set_bit(CGRP_DEAD, &cgrp->flags);
 
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 19613ba51444..98ca48d9ceb4 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -50,11 +50,6 @@ static inline struct freezer *css_freezer(struct cgroup_subsys_state *css)
         return css ? container_of(css, struct freezer, css) : NULL;
 }
 
-static inline struct freezer *cgroup_freezer(struct cgroup *cgroup)
-{
-        return css_freezer(cgroup_css(cgroup, freezer_subsys_id));
-}
-
 static inline struct freezer *task_freezer(struct task_struct *task)
 {
         return css_freezer(task_css(task, freezer_subsys_id));
@@ -120,7 +115,7 @@ static int freezer_css_online(struct cgroup_subsys_state *css)
         /*
          * The following double locking and freezing state inheritance
          * guarantee that @cgroup can never escape ancestors' freezing
-         * states.  See cgroup_for_each_descendant_pre() for details.
+         * states.  See css_for_each_descendant_pre() for details.
          */
         if (parent)
                 spin_lock_irq(&parent->lock);
@@ -262,7 +257,7 @@ out:
 static void update_if_frozen(struct cgroup_subsys_state *css)
 {
         struct freezer *freezer = css_freezer(css);
-        struct cgroup *pos;
+        struct cgroup_subsys_state *pos;
         struct cgroup_iter it;
         struct task_struct *task;
 
@@ -275,8 +270,8 @@ static void update_if_frozen(struct cgroup_subsys_state *css)
                 goto out_unlock;
 
         /* are all (live) children frozen? */
-        cgroup_for_each_child(pos, css->cgroup) {
-                struct freezer *child = cgroup_freezer(pos);
+        css_for_each_child(pos, css) {
+                struct freezer *child = css_freezer(pos);
 
                 if ((child->state & CGROUP_FREEZER_ONLINE) &&
                     !(child->state & CGROUP_FROZEN))
@@ -309,13 +304,13 @@ out_unlock:
 static int freezer_read(struct cgroup_subsys_state *css, struct cftype *cft,
                         struct seq_file *m)
 {
-        struct cgroup *pos;
+        struct cgroup_subsys_state *pos;
 
         rcu_read_lock();
 
         /* update states bottom-up */
-        cgroup_for_each_descendant_post(pos, css->cgroup)
-                update_if_frozen(cgroup_css(pos, freezer_subsys_id));
+        css_for_each_descendant_post(pos, css)
+                update_if_frozen(pos);
         update_if_frozen(css);
 
         rcu_read_unlock();
@@ -396,7 +391,7 @@ static void freezer_apply_state(struct freezer *freezer, bool freeze,
  */
 static void freezer_change_state(struct freezer *freezer, bool freeze)
 {
-        struct cgroup *pos;
+        struct cgroup_subsys_state *pos;
 
         /* update @freezer */
         spin_lock_irq(&freezer->lock);
@@ -409,8 +404,8 @@ static void freezer_change_state(struct freezer *freezer, bool freeze)
          * CGROUP_FREEZING_PARENT.
          */
         rcu_read_lock();
-        cgroup_for_each_descendant_pre(pos, freezer->css.cgroup) {
-                struct freezer *pos_f = cgroup_freezer(pos);
+        css_for_each_descendant_pre(pos, &freezer->css) {
+                struct freezer *pos_f = css_freezer(pos);
                 struct freezer *parent = parent_freezer(pos_f);
 
                 /*
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 89b76e1d3aa1..be4f5036ea5e 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -210,29 +210,29 @@ static struct cpuset top_cpuset = {
 /**
  * cpuset_for_each_child - traverse online children of a cpuset
  * @child_cs: loop cursor pointing to the current child
- * @pos_cgrp: used for iteration
+ * @pos_css: used for iteration
  * @parent_cs: target cpuset to walk children of
  *
  * Walk @child_cs through the online children of @parent_cs.  Must be used
  * with RCU read locked.
  */
-#define cpuset_for_each_child(child_cs, pos_cgrp, parent_cs)            \
-        cgroup_for_each_child((pos_cgrp), (parent_cs)->css.cgroup)      \
-                if (is_cpuset_online(((child_cs) = cgroup_cs((pos_cgrp)))))
+#define cpuset_for_each_child(child_cs, pos_css, parent_cs)             \
+        css_for_each_child((pos_css), &(parent_cs)->css)                \
+                if (is_cpuset_online(((child_cs) = css_cs((pos_css)))))
 
 /**
  * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants
  * @des_cs: loop cursor pointing to the current descendant
- * @pos_cgrp: used for iteration
+ * @pos_css: used for iteration
  * @root_cs: target cpuset to walk ancestor of
  *
  * Walk @des_cs through the online descendants of @root_cs.  Must be used
- * with RCU read locked.  The caller may modify @pos_cgrp by calling
- * cgroup_rightmost_descendant() to skip subtree.
+ * with RCU read locked.  The caller may modify @pos_css by calling
+ * css_rightmost_descendant() to skip subtree.
  */
-#define cpuset_for_each_descendant_pre(des_cs, pos_cgrp, root_cs)       \
-        cgroup_for_each_descendant_pre((pos_cgrp), (root_cs)->css.cgroup) \
-                if (is_cpuset_online(((des_cs) = cgroup_cs((pos_cgrp)))))
+#define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs)        \
+        css_for_each_descendant_pre((pos_css), &(root_cs)->css)         \
+                if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
 
 /*
  * There are two global mutexes guarding cpuset structures - cpuset_mutex
@@ -430,7 +430,7 @@ static void free_trial_cpuset(struct cpuset *trial)
 
 static int validate_change(struct cpuset *cur, struct cpuset *trial)
 {
-        struct cgroup *cgrp;
+        struct cgroup_subsys_state *css;
         struct cpuset *c, *par;
         int ret;
 
@@ -438,7 +438,7 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial)
 
         /* Each of our child cpusets must be a subset of us */
         ret = -EBUSY;
-        cpuset_for_each_child(c, cgrp, cur)
+        cpuset_for_each_child(c, css, cur)
                 if (!is_cpuset_subset(c, trial))
                         goto out;
 
@@ -459,7 +459,7 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial)
          * overlap
          */
         ret = -EINVAL;
-        cpuset_for_each_child(c, cgrp, par) {
+        cpuset_for_each_child(c, css, par) {
                 if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
                     c != cur &&
                     cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
@@ -508,13 +508,13 @@ static void update_domain_attr_tree(struct sched_domain_attr *dattr,
                                     struct cpuset *root_cs)
 {
         struct cpuset *cp;
-        struct cgroup *pos_cgrp;
+        struct cgroup_subsys_state *pos_css;
 
         rcu_read_lock();
-        cpuset_for_each_descendant_pre(cp, pos_cgrp, root_cs) {
+        cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
                 /* skip the whole subtree if @cp doesn't have any CPU */
                 if (cpumask_empty(cp->cpus_allowed)) {
-                        pos_cgrp = cgroup_rightmost_descendant(pos_cgrp);
+                        pos_css = css_rightmost_descendant(pos_css);
                         continue;
                 }
 
@@ -589,7 +589,7 @@ static int generate_sched_domains(cpumask_var_t **domains,
         struct sched_domain_attr *dattr;  /* attributes for custom domains */
         int ndoms = 0;          /* number of sched domains in result */
         int nslot;              /* next empty doms[] struct cpumask slot */
-        struct cgroup *pos_cgrp;
+        struct cgroup_subsys_state *pos_css;
 
         doms = NULL;
         dattr = NULL;
@@ -618,7 +618,7 @@ static int generate_sched_domains(cpumask_var_t **domains,
         csn = 0;
 
         rcu_read_lock();
-        cpuset_for_each_descendant_pre(cp, pos_cgrp, &top_cpuset) {
+        cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {
                 /*
                  * Continue traversing beyond @cp iff @cp has some CPUs and
                  * isn't load balancing.  The former is obvious.  The
@@ -635,7 +635,7 @@ static int generate_sched_domains(cpumask_var_t **domains,
                         csa[csn++] = cp;
 
                 /* skip @cp's subtree */
-                pos_cgrp = cgroup_rightmost_descendant(pos_cgrp);
+                pos_css = css_rightmost_descendant(pos_css);
         }
         rcu_read_unlock();
 
@@ -886,16 +886,16 @@ static void update_tasks_cpumask_hier(struct cpuset *root_cs,
                                       bool update_root, struct ptr_heap *heap)
 {
         struct cpuset *cp;
-        struct cgroup *pos_cgrp;
+        struct cgroup_subsys_state *pos_css;
 
         if (update_root)
                 update_tasks_cpumask(root_cs, heap);
 
         rcu_read_lock();
-        cpuset_for_each_descendant_pre(cp, pos_cgrp, root_cs) {
+        cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
                 /* skip the whole subtree if @cp have some CPU */
                 if (!cpumask_empty(cp->cpus_allowed)) {
-                        pos_cgrp = cgroup_rightmost_descendant(pos_cgrp);
+                        pos_css = css_rightmost_descendant(pos_css);
                         continue;
                 }
                 if (!css_tryget(&cp->css))
@@ -1143,16 +1143,16 @@ static void update_tasks_nodemask_hier(struct cpuset *root_cs,
                                        bool update_root, struct ptr_heap *heap)
 {
         struct cpuset *cp;
-        struct cgroup *pos_cgrp;
+        struct cgroup_subsys_state *pos_css;
 
         if (update_root)
                 update_tasks_nodemask(root_cs, heap);
 
         rcu_read_lock();
-        cpuset_for_each_descendant_pre(cp, pos_cgrp, root_cs) {
+        cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
                 /* skip the whole subtree if @cp have some CPU */
                 if (!nodes_empty(cp->mems_allowed)) {
-                        pos_cgrp = cgroup_rightmost_descendant(pos_cgrp);
+                        pos_css = css_rightmost_descendant(pos_css);
                         continue;
                 }
                 if (!css_tryget(&cp->css))
@@ -1973,7 +1973,7 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
         struct cpuset *cs = css_cs(css);
         struct cpuset *parent = parent_cs(cs);
         struct cpuset *tmp_cs;
-        struct cgroup *pos_cgrp;
+        struct cgroup_subsys_state *pos_css;
 
         if (!parent)
                 return 0;
@@ -2005,7 +2005,7 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
          * (and likewise for mems) to the new cgroup.
          */
         rcu_read_lock();
-        cpuset_for_each_child(tmp_cs, pos_cgrp, parent) {
+        cpuset_for_each_child(tmp_cs, pos_css, parent) {
                 if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
                         rcu_read_unlock();
                         goto out_unlock;
@@ -2252,10 +2252,10 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
         /* if cpus or mems changed, we need to propagate to descendants */
         if (cpus_updated || mems_updated) {
                 struct cpuset *cs;
-                struct cgroup *pos_cgrp;
+                struct cgroup_subsys_state *pos_css;
 
                 rcu_read_lock();
-                cpuset_for_each_descendant_pre(cs, pos_cgrp, &top_cpuset) {
+                cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
                         if (!css_tryget(&cs->css))
                                 continue;
                         rcu_read_unlock();
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ab64dfc84f8c..2285319e23a9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1082,7 +1082,7 @@ struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
 static struct mem_cgroup *__mem_cgroup_iter_next(struct mem_cgroup *root,
                 struct mem_cgroup *last_visited)
 {
-        struct cgroup *prev_cgroup, *next_cgroup;
+        struct cgroup_subsys_state *prev_css, *next_css;
 
         /*
          * Root is not visited by cgroup iterators so it needs an
@@ -1091,11 +1091,9 @@ static struct mem_cgroup *__mem_cgroup_iter_next(struct mem_cgroup *root,
         if (!last_visited)
                 return root;
 
-        prev_cgroup = (last_visited == root) ? NULL
-                : last_visited->css.cgroup;
+        prev_css = (last_visited == root) ? NULL : &last_visited->css;
 skip_node:
-        next_cgroup = cgroup_next_descendant_pre(
-                        prev_cgroup, root->css.cgroup);
+        next_css = css_next_descendant_pre(prev_css, &root->css);
 
         /*
          * Even if we found a group we have to make sure it is
@@ -1104,13 +1102,13 @@ skip_node:
          * last_visited css is safe to use because it is
          * protected by css_get and the tree walk is rcu safe.
          */
-        if (next_cgroup) {
-                struct mem_cgroup *mem = mem_cgroup_from_cont(
-                                next_cgroup);
+        if (next_css) {
+                struct mem_cgroup *mem = mem_cgroup_from_css(next_css);
+
                 if (css_tryget(&mem->css))
                         return mem;
                 else {
-                        prev_cgroup = next_cgroup;
+                        prev_css = next_css;
                         goto skip_node;
                 }
         }
@@ -4939,10 +4937,10 @@ static void mem_cgroup_reparent_charges(struct mem_cgroup *memcg)
  */
 static inline bool __memcg_has_children(struct mem_cgroup *memcg)
 {
-        struct cgroup *pos;
+        struct cgroup_subsys_state *pos;
 
         /* bounce at first found */
-        cgroup_for_each_child(pos, memcg->css.cgroup)
+        css_for_each_child(pos, &memcg->css)
                 return true;
         return false;
 }
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index e0ca464fa854..9bf230aa28b0 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -56,11 +56,6 @@ static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s)
         return s ? container_of(s, struct dev_cgroup, css) : NULL;
 }
 
-static inline struct dev_cgroup *cgroup_to_devcgroup(struct cgroup *cgroup)
-{
-        return css_to_devcgroup(cgroup_css(cgroup, devices_subsys_id));
-}
-
 static inline struct dev_cgroup *task_devcgroup(struct task_struct *task)
 {
         return css_to_devcgroup(task_css(task, devices_subsys_id));
@@ -447,13 +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