cgroup: rename cgroup->dummy_css to ->self and move it to the top

cgroup->dummy_css is used as the placeholder css when performing css
oriended operations on the cgroup.  We're gonna shift more cgroup
management to this css.  Let's rename it to ->self and move it to the
top.

This is pure rename and field relocation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index aa7353d..164851e 100644 (file)
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -143,6 +143,9 @@ enum {
 };
 
 struct cgroup {
+       /* self css with NULL ->ss, points back to this cgroup */
+       struct cgroup_subsys_state self;
+
        unsigned long flags;            /* "unsigned long" so bitops work */
 
        /*
@@ -224,9 +227,6 @@ struct cgroup {
        struct list_head pidlists;
        struct mutex pidlist_mutex;
 
-       /* dummy css with NULL ->ss, points back to this cgroup */
-       struct cgroup_subsys_state dummy_css;
-
        /* For css percpu_ref killing and RCU-protected deletion */
        struct rcu_head rcu_head;
        struct work_struct destroy_work;

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index f36fd9c..b57a949 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -220,7 +220,7 @@ static void cgroup_idr_remove(struct idr *idr, int id)
 /**
  * cgroup_css - obtain a cgroup's css for the specified subsystem
  * @cgrp: the cgroup of interest
- * @ss: the subsystem of interest (%NULL returns the dummy_css)
+ * @ss: the subsystem of interest (%NULL returns @cgrp->self)
  *
  * Return @cgrp's css (cgroup_subsys_state) associated with @ss.  This
  * function must be called either under cgroup_mutex or rcu_read_lock() and
@@ -235,13 +235,13 @@ static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
                return rcu_dereference_check(cgrp->subsys[ss->id],
                                        lockdep_is_held(&cgroup_mutex));
        else
-               return &cgrp->dummy_css;
+               return &cgrp->self;
 }
 
 /**
  * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
  * @cgrp: the cgroup of interest
- * @ss: the subsystem of interest (%NULL returns the dummy_css)
+ * @ss: the subsystem of interest (%NULL returns @cgrp->self)
  *
  * Similar to cgroup_css() but returns the effctive css, which is defined
  * as the matching css of the nearest ancestor including self which has @ss
@@ -254,7 +254,7 @@ static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
        lockdep_assert_held(&cgroup_mutex);
 
        if (!ss)
-               return &cgrp->dummy_css;
+               return &cgrp->self;
 
        if (!(cgrp->root->subsys_mask & (1 << ss->id)))
                return NULL;
@@ -288,7 +288,7 @@ struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
        if (cft->ss)
                return rcu_dereference_raw(cgrp->subsys[cft->ss->id]);
        else
-               return &cgrp->dummy_css;
+               return &cgrp->self;
 }
 EXPORT_SYMBOL_GPL(of_css);
 
@@ -1551,7 +1551,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
        INIT_LIST_HEAD(&cgrp->release_list);
        INIT_LIST_HEAD(&cgrp->pidlists);
        mutex_init(&cgrp->pidlist_mutex);
-       cgrp->dummy_css.cgroup = cgrp;
+       cgrp->self.cgroup = cgrp;
 
        for_each_subsys(ss, ssid)
                INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
@@ -3454,7 +3454,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
         * ->can_attach() fails.
         */
        do {
-               css_task_iter_start(&from->dummy_css, &it);
+               css_task_iter_start(&from->self, &it);
                task = css_task_iter_next(&it);
                if (task)
                        get_task_struct(task);
@@ -3719,7 +3719,7 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
        if (!array)
                return -ENOMEM;
        /* now, populate the array */
-       css_task_iter_start(&cgrp->dummy_css, &it);
+       css_task_iter_start(&cgrp->self, &it);
        while ((tsk = css_task_iter_next(&it))) {
                if (unlikely(n == length))
                        break;
@@ -3793,7 +3793,7 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
        }
        rcu_read_unlock();
 
-       css_task_iter_start(&cgrp->dummy_css, &it);
+       css_task_iter_start(&cgrp->self, &it);
        while ((tsk = css_task_iter_next(&it))) {
                switch (tsk->state) {
                case TASK_RUNNING:
@@ -4274,7 +4274,7 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
        init_cgroup_housekeeping(cgrp);
 
        cgrp->parent = parent;
-       cgrp->dummy_css.parent = &parent->dummy_css;
+       cgrp->self.parent = &parent->self;
        cgrp->root = root;
 
        if (notify_on_release(parent))