cgroup: consistently use @cset for struct css_set variables
authorTejun Heo <tj@kernel.org>
Thu, 13 Jun 2013 04:04:49 +0000 (21:04 -0700)
committerTejun Heo <tj@kernel.org>
Thu, 13 Jun 2013 17:55:17 +0000 (10:55 -0700)
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: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
kernel/cgroup.c

index d4a329f5874c3ce86a5e210b54b2bda600ba1fdf..1f5a4e101ed16d052beb6a3319ba71e486504df5 100644 (file)
@@ -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,
-       struct cgroup *cgrp,
-       struct cgroup_subsys_state *template[])
+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;