struct list_head css_sets;
struct list_head allcg_node; /* cgroupfs_root->allcg_list */
+ struct list_head cft_q_node; /* used during cftype add/rm */
/*
* Linked list running through all cgroups that can
* - the 'cftype' of the file is file->f_dentry->d_fsdata
*/
-#define MAX_CFTYPE_NAME 64
+/* cftype->flags */
+#define CFTYPE_ONLY_ON_ROOT (1U << 0) /* only create on root cg */
+#define CFTYPE_NOT_ON_ROOT (1U << 1) /* don't create onp root cg */
+
+#define MAX_CFTYPE_NAME 64
+
struct cftype {
/*
* By convention, the name should begin with the name of the
- * subsystem, followed by a period
+ * subsystem, followed by a period. Zero length string indicates
+ * end of cftype array.
*/
char name[MAX_CFTYPE_NAME];
int private;
*/
size_t max_write_len;
+ /* CFTYPE_* flags */
+ unsigned int flags;
+
int (*open)(struct inode *inode, struct file *file);
ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft,
struct file *file,
struct eventfd_ctx *eventfd);
};
+/*
+ * cftype_sets describe cftypes belonging to a subsystem and are chained at
+ * cgroup_subsys->cftsets. Each cftset points to an array of cftypes
+ * terminated by zero length name.
+ */
+struct cftype_set {
+ struct list_head node; /* chained at subsys->cftsets */
+ const struct cftype *cfts;
+};
+
struct cgroup_scanner {
struct cgroup *cg;
int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan);
const struct cftype cft[],
int count);
+int cgroup_add_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts);
+
int cgroup_is_removed(const struct cgroup *cgrp);
int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
struct idr idr;
spinlock_t id_lock;
+ /* list of cftype_sets */
+ struct list_head cftsets;
+
+ /* base cftypes, automatically [de]registered with subsys itself */
+ struct cftype *base_cftypes;
+ struct cftype_set base_cftset;
+
/* should be defined only by modular subsystems */
struct module *module;
};
struct dentry *dentry;
int error;
umode_t mode;
-
char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
+
+ /* does @cft->flags tell us to skip creation on @cgrp? */
+ if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent)
+ return 0;
+ if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent)
+ return 0;
+
if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) {
strcpy(name, subsys->name);
strcat(name, ".");
}
EXPORT_SYMBOL_GPL(cgroup_add_files);
+static DEFINE_MUTEX(cgroup_cft_mutex);
+
+static void cgroup_cfts_prepare(void)
+ __acquires(&cgroup_cft_mutex) __acquires(&cgroup_mutex)
+{
+ /*
+ * Thanks to the entanglement with vfs inode locking, we can't walk
+ * the existing cgroups under cgroup_mutex and create files.
+ * Instead, we increment reference on all cgroups and build list of
+ * them using @cgrp->cft_q_node. Grab cgroup_cft_mutex to ensure
+ * exclusive access to the field.
+ */
+ mutex_lock(&cgroup_cft_mutex);
+ mutex_lock(&cgroup_mutex);
+}
+
+static void cgroup_cfts_commit(struct cgroup_subsys *ss,
+ const struct cftype *cfts)
+ __releases(&cgroup_mutex) __releases(&cgroup_cft_mutex)
+{
+ LIST_HEAD(pending);
+ struct cgroup *cgrp, *n;
+ int count = 0;
+
+ while (cfts[count].name[0] != '\0')
+ count++;
+
+ /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
+ if (cfts && ss->root != &rootnode) {
+ list_for_each_entry(cgrp, &ss->root->allcg_list, allcg_node) {
+ dget(cgrp->dentry);
+ list_add_tail(&cgrp->cft_q_node, &pending);
+ }
+ }
+
+ mutex_unlock(&cgroup_mutex);
+
+ /*
+ * All new cgroups will see @cfts update on @ss->cftsets. Add/rm
+ * files for all cgroups which were created before.
+ */
+ list_for_each_entry_safe(cgrp, n, &pending, cft_q_node) {
+ struct inode *inode = cgrp->dentry->d_inode;
+
+ mutex_lock(&inode->i_mutex);
+ mutex_lock(&cgroup_mutex);
+ if (!cgroup_is_removed(cgrp))
+ cgroup_add_files(cgrp, ss, cfts, count);
+ mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&inode->i_mutex);
+
+ list_del_init(&cgrp->cft_q_node);
+ dput(cgrp->dentry);
+ }
+
+ mutex_unlock(&cgroup_cft_mutex);
+}
+
+/**
+ * cgroup_add_cftypes - add an array of cftypes to a subsystem
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Register @cfts to @ss. Files described by @cfts are created for all
+ * existing cgroups to which @ss is attached and all future cgroups will
+ * have them too. This function can be called anytime whether @ss is
+ * attached or not.
+ *
+ * Returns 0 on successful registration, -errno on failure. Note that this
+ * function currently returns 0 as long as @cfts registration is successful
+ * even if some file creation attempts on existing cgroups fail.
+ */
+int cgroup_add_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts)
+{
+ struct cftype_set *set;
+
+ set = kzalloc(sizeof(*set), GFP_KERNEL);
+ if (!set)
+ return -ENOMEM;
+
+ cgroup_cfts_prepare();
+ set->cfts = cfts;
+ list_add_tail(&set->node, &ss->cftsets);
+ cgroup_cfts_commit(ss, cfts);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(cgroup_add_cftypes);
+
/**
* cgroup_task_count - count the number of tasks in a cgroup.
* @cgrp: the cgroup in question
return err;
}
+ /* process cftsets of each subsystem */
for_each_subsys(cgrp->root, ss) {
+ struct cftype_set *set;
+
if (ss->populate && (err = ss->populate(ss, cgrp)) < 0)
return err;
+
+ list_for_each_entry(set, &ss->cftsets, node) {
+ const struct cftype *cft;
+
+ for (cft = set->cfts; cft->name[0] != '\0'; cft++) {
+ err = cgroup_add_file(cgrp, ss, cft);
+ if (err)
+ pr_warning("cgroup_populate_dir: failed to create %s, err=%d\n",
+ cft->name, err);
+ }
+ }
}
+
/* This cgroup is ready now */
for_each_subsys(cgrp->root, ss) {
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
return 0;
}
+static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss)
+{
+ INIT_LIST_HEAD(&ss->cftsets);
+
+ /*
+ * base_cftset is embedded in subsys itself, no need to worry about
+ * deregistration.
+ */
+ if (ss->base_cftypes) {
+ ss->base_cftset.cfts = ss->base_cftypes;
+ list_add_tail(&ss->base_cftset.node, &ss->cftsets);
+ }
+}
+
static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
{
struct cgroup_subsys_state *css;
printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
+ /* init base cftset */
+ cgroup_init_cftsets(ss);
+
/* Create the top cgroup state for this subsystem */
list_add(&ss->sibling, &rootnode.subsys_list);
ss->root = &rootnode;
return 0;
}
+ /* init base cftset */
+ cgroup_init_cftsets(ss);
+
/*
* need to register a subsys id before anything else - for example,
* init_cgroup_css needs it.
projects / users / willy / pagecache.git / commitdiff