char release_agent_path[PATH_MAX];
};
-
/*
* The "rootnode" hierarchy is the "dummy hierarchy", reserved for the
* subsystems that are otherwise unattached - it never has more than a
*/
static struct cgroupfs_root rootnode;
+/*
+ * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
+ * cgroup_subsys->use_id != 0.
+ */
+#define CSS_ID_MAX (65535)
+struct css_id {
+ /*
+ * The css to which this ID points. This pointer is set to valid value
+ * after cgroup is populated. If cgroup is removed, this will be NULL.
+ * This pointer is expected to be RCU-safe because destroy()
+ * is called after synchronize_rcu(). But for safe use, css_is_removed()
+ * css_tryget() should be used for avoiding race.
+ */
+ struct cgroup_subsys_state *css;
+ /*
+ * ID of this css.
+ */
+ unsigned short id;
+ /*
+ * Depth in hierarchy which this ID belongs to.
+ */
+ unsigned short depth;
+ /*
+ * ID is freed by RCU. (and lookup routine is RCU safe.)
+ */
+ struct rcu_head rcu_head;
+ /*
+ * Hierarchy of CSS ID belongs to.
+ */
+ unsigned short stack[0]; /* Array of Length (depth+1) */
+};
+
+
/* The list of hierarchy roots */
static LIST_HEAD(roots);
static struct css_set init_css_set;
static struct cg_cgroup_link init_css_set_link;
+static int cgroup_subsys_init_idr(struct cgroup_subsys *ss);
+
/* css_set_lock protects the list of css_set objects, and the
* chain of tasks off each css_set. Nests outside task->alloc_lock
* due to cgroup_iter_start() */
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
};
+static int alloc_css_id(struct cgroup_subsys *ss,
+ struct cgroup *parent, struct cgroup *child);
+
static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb)
{
struct inode *inode = new_inode(sb);
if (ss->populate && (err = ss->populate(ss, cgrp)) < 0)
return err;
}
+ /* This cgroup is ready now */
+ for_each_subsys(cgrp->root, ss) {
+ struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
+ /*
+ * Update id->css pointer and make this css visible from
+ * CSS ID functions. This pointer will be dereferened
+ * from RCU-read-side without locks.
+ */
+ if (css->id)
+ rcu_assign_pointer(css->id->css, css);
+ }
return 0;
}
css->cgroup = cgrp;
atomic_set(&css->refcnt, 1);
css->flags = 0;
+ css->id = NULL;
if (cgrp == dummytop)
set_bit(CSS_ROOT, &css->flags);
BUG_ON(cgrp->subsys[ss->subsys_id]);
goto err_destroy;
}
init_cgroup_css(css, ss, cgrp);
+ if (ss->use_id)
+ if (alloc_css_id(ss, parent, cgrp))
+ goto err_destroy;
+ /* At error, ->destroy() callback has to free assigned ID. */
}
cgroup_lock_hierarchy(root);
struct cgroup_subsys *ss = subsys[i];
if (!ss->early_init)
cgroup_init_subsys(ss);
+ if (ss->use_id)
+ cgroup_subsys_init_idr(ss);
}
/* Add init_css_set to the hash table */
return 1;
}
__setup("cgroup_disable=", cgroup_disable);
+
+/*
+ * Functons for CSS ID.
+ */
+
+/*
+ *To get ID other than 0, this should be called when !cgroup_is_removed().
+ */
+unsigned short css_id(struct cgroup_subsys_state *css)
+{
+ struct css_id *cssid = rcu_dereference(css->id);
+
+ if (cssid)
+ return cssid->id;
+ return 0;
+}
+
+unsigned short css_depth(struct cgroup_subsys_state *css)
+{
+ struct css_id *cssid = rcu_dereference(css->id);
+
+ if (cssid)
+ return cssid->depth;
+ return 0;
+}
+
+bool css_is_ancestor(struct cgroup_subsys_state *child,
+ struct cgroup_subsys_state *root)
+{
+ struct css_id *child_id = rcu_dereference(child->id);
+ struct css_id *root_id = rcu_dereference(root->id);
+
+ if (!child_id || !root_id || (child_id->depth < root_id->depth))
+ return false;
+ return child_id->stack[root_id->depth] == root_id->id;
+}
+
+static void __free_css_id_cb(struct rcu_head *head)
+{
+ struct css_id *id;
+
+ id = container_of(head, struct css_id, rcu_head);
+ kfree(id);
+}
+
+void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css)
+{
+ struct css_id *id = css->id;
+ /* When this is called before css_id initialization, id can be NULL */
+ if (!id)
+ return;
+
+ BUG_ON(!ss->use_id);
+
+ rcu_assign_pointer(id->css, NULL);
+ rcu_assign_pointer(css->id, NULL);
+ spin_lock(&ss->id_lock);
+ idr_remove(&ss->idr, id->id);
+ spin_unlock(&ss->id_lock);
+ call_rcu(&id->rcu_head, __free_css_id_cb);
+}
+
+/*
+ * This is called by init or create(). Then, calls to this function are
+ * always serialized (By cgroup_mutex() at create()).
+ */
+
+static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth)
+{
+ struct css_id *newid;
+ int myid, error, size;
+
+ BUG_ON(!ss->use_id);
+
+ size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1);
+ newid = kzalloc(size, GFP_KERNEL);
+ if (!newid)
+ return ERR_PTR(-ENOMEM);
+ /* get id */
+ if (unlikely(!idr_pre_get(&ss->idr, GFP_KERNEL))) {
+ error = -ENOMEM;
+ goto err_out;
+ }
+ spin_lock(&ss->id_lock);
+ /* Don't use 0. allocates an ID of 1-65535 */
+ error = idr_get_new_above(&ss->idr, newid, 1, &myid);
+ spin_unlock(&ss->id_lock);
+
+ /* Returns error when there are no free spaces for new ID.*/
+ if (error) {
+ error = -ENOSPC;
+ goto err_out;
+ }
+ if (myid > CSS_ID_MAX)
+ goto remove_idr;
+
+ newid->id = myid;
+ newid->depth = depth;
+ return newid;
+remove_idr:
+ error = -ENOSPC;
+ spin_lock(&ss->id_lock);
+ idr_remove(&ss->idr, myid);
+ spin_unlock(&ss->id_lock);
+err_out:
+ kfree(newid);
+ return ERR_PTR(error);
+
+}
+
+static int __init cgroup_subsys_init_idr(struct cgroup_subsys *ss)
+{
+ struct css_id *newid;
+ struct cgroup_subsys_state *rootcss;
+
+ spin_lock_init(&ss->id_lock);
+ idr_init(&ss->idr);
+
+ rootcss = init_css_set.subsys[ss->subsys_id];
+ newid = get_new_cssid(ss, 0);
+ if (IS_ERR(newid))
+ return PTR_ERR(newid);
+
+ newid->stack[0] = newid->id;
+ newid->css = rootcss;
+ rootcss->id = newid;
+ return 0;
+}
+
+static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent,
+ struct cgroup *child)
+{
+ int subsys_id, i, depth = 0;
+ struct cgroup_subsys_state *parent_css, *child_css;
+ struct css_id *child_id, *parent_id = NULL;
+
+ subsys_id = ss->subsys_id;
+ parent_css = parent->subsys[subsys_id];
+ child_css = child->subsys[subsys_id];
+ depth = css_depth(parent_css) + 1;
+ parent_id = parent_css->id;
+
+ child_id = get_new_cssid(ss, depth);
+ if (IS_ERR(child_id))
+ return PTR_ERR(child_id);
+
+ for (i = 0; i < depth; i++)
+ child_id->stack[i] = parent_id->stack[i];
+ child_id->stack[depth] = child_id->id;
+ /*
+ * child_id->css pointer will be set after this cgroup is available
+ * see cgroup_populate_dir()
+ */
+ rcu_assign_pointer(child_css->id, child_id);
+
+ return 0;
+}
+
+/**
+ * css_lookup - lookup css by id
+ * @ss: cgroup subsys to be looked into.
+ * @id: the id
+ *
+ * Returns pointer to cgroup_subsys_state if there is valid one with id.
+ * NULL if not. Should be called under rcu_read_lock()
+ */
+struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id)
+{
+ struct css_id *cssid = NULL;
+
+ BUG_ON(!ss->use_id);
+ cssid = idr_find(&ss->idr, id);
+
+ if (unlikely(!cssid))
+ return NULL;
+
+ return rcu_dereference(cssid->css);
+}
+
+/**
+ * css_get_next - lookup next cgroup under specified hierarchy.
+ * @ss: pointer to subsystem
+ * @id: current position of iteration.
+ * @root: pointer to css. search tree under this.
+ * @foundid: position of found object.
+ *
+ * Search next css under the specified hierarchy of rootid. Calling under
+ * rcu_read_lock() is necessary. Returns NULL if it reaches the end.
+ */
+struct cgroup_subsys_state *
+css_get_next(struct cgroup_subsys *ss, int id,
+ struct cgroup_subsys_state *root, int *foundid)
+{
+ struct cgroup_subsys_state *ret = NULL;
+ struct css_id *tmp;
+ int tmpid;
+ int rootid = css_id(root);
+ int depth = css_depth(root);
+
+ if (!rootid)
+ return NULL;
+
+ BUG_ON(!ss->use_id);
+ /* fill start point for scan */
+ tmpid = id;
+ while (1) {
+ /*
+ * scan next entry from bitmap(tree), tmpid is updated after
+ * idr_get_next().
+ */
+ spin_lock(&ss->id_lock);
+ tmp = idr_get_next(&ss->idr, &tmpid);
+ spin_unlock(&ss->id_lock);
+
+ if (!tmp)
+ break;
+ if (tmp->depth >= depth && tmp->stack[depth] == rootid) {
+ ret = rcu_dereference(tmp->css);
+ if (ret) {
+ *foundid = tmpid;
+ break;
+ }
+ }
+ /* continue to scan from next id */
+ tmpid = tmpid + 1;
+ }
+ return ret;
+}
+
projects / linux-2.6-omap-h63xx.git / blobdiff