#include <linux/cgroupstats.h>
#include <linux/prio_heap.h>
#include <linux/rwsem.h>
+#include <linux/idr.h>
#ifdef CONFIG_CGROUPS
struct cgroup_subsys;
struct inode;
struct cgroup;
+struct css_id;
extern int cgroup_init_early(void);
extern int cgroup_init(void);
/* Per-subsystem/per-cgroup state maintained by the system. */
struct cgroup_subsys_state {
- /* The cgroup that this subsystem is attached to. Useful
+ /*
+ * The cgroup that this subsystem is attached to. Useful
* for subsystems that want to know about the cgroup
- * hierarchy structure */
+ * hierarchy structure
+ */
struct cgroup *cgroup;
- /* State maintained by the cgroup system to allow subsystems
+ /*
+ * State maintained by the cgroup system to allow subsystems
* to be "busy". Should be accessed via css_get(),
- * css_tryget() and and css_put(). */
+ * css_tryget() and and css_put().
+ */
atomic_t refcnt;
unsigned long flags;
+ /* ID for this css, if possible */
+ struct css_id *id;
};
/* bits in struct cgroup_subsys_state flags field */
while (!atomic_inc_not_zero(&css->refcnt)) {
if (test_bit(CSS_REMOVED, &css->flags))
return false;
+ cpu_relax();
}
return true;
}
enum {
/* Control Group is dead */
CGRP_REMOVED,
- /* Control Group has previously had a child cgroup or a task,
- * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set) */
+ /*
+ * Control Group has previously had a child cgroup or a task,
+ * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set)
+ */
CGRP_RELEASABLE,
/* Control Group requires release notifications to userspace */
CGRP_NOTIFY_ON_RELEASE,
struct cgroup {
unsigned long flags; /* "unsigned long" so bitops work */
- /* count users of this cgroup. >0 means busy, but doesn't
- * necessarily indicate the number of tasks in the
- * cgroup */
+ /*
+ * count users of this cgroup. >0 means busy, but doesn't
+ * necessarily indicate the number of tasks in the cgroup
+ */
atomic_t count;
/*
struct list_head sibling; /* my parent's children */
struct list_head children; /* my children */
- struct cgroup *parent; /* my parent */
+ struct cgroup *parent; /* my parent */
struct dentry *dentry; /* cgroup fs entry, RCU protected */
/* Private pointers for each registered subsystem */
struct rcu_head rcu_head;
};
-/* A css_set is a structure holding pointers to a set of
+/*
+ * A css_set is a structure holding pointers to a set of
* cgroup_subsys_state objects. This saves space in the task struct
* object and speeds up fork()/exit(), since a single inc/dec and a
- * list_add()/del() can bump the reference count on the entire
- * cgroup set for a task.
+ * list_add()/del() can bump the reference count on the entire cgroup
+ * set for a task.
*/
struct css_set {
void *state;
};
-/* struct cftype:
- *
- * The files in the cgroup filesystem mostly have a very simple read/write
- * handling, some common function will take care of it. Nevertheless some cases
- * (read tasks) are special and therefore I define this structure for every
- * kind of file.
- *
+/*
+ * struct cftype: handler definitions for cgroup control files
*
* When reading/writing to a file:
* - the cgroup to use is file->f_dentry->d_parent->d_fsdata
#define MAX_CFTYPE_NAME 64
struct cftype {
- /* By convention, the name should begin with the name of the
- * subsystem, followed by a period */
+ /*
+ * By convention, the name should begin with the name of the
+ * subsystem, followed by a period
+ */
char name[MAX_CFTYPE_NAME];
int private;
struct ptr_heap *heap;
};
-/* Add a new file to the given cgroup directory. Should only be
- * called by subsystems from within a populate() method */
+/*
+ * Add a new file to the given cgroup directory. Should only be
+ * called by subsystems from within a populate() method
+ */
int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
const struct cftype *cft);
-/* Add a set of new files to the given cgroup directory. Should
- * only be called by subsystems from within a populate() method */
+/*
+ * Add a set of new files to the given cgroup directory. Should
+ * only be called by subsystems from within a populate() method
+ */
int cgroup_add_files(struct cgroup *cgrp,
struct cgroup_subsys *subsys,
const struct cftype cft[],
int cgroup_task_count(const struct cgroup *cgrp);
-/* Return true if the cgroup is a descendant of the current cgroup */
-int cgroup_is_descendant(const struct cgroup *cgrp);
+/* Return true if cgrp is a descendant of the task's cgroup */
+int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task);
/* Control Group subsystem type. See Documentation/cgroups.txt for details */
int active;
int disabled;
int early_init;
+ /*
+ * True if this subsys uses ID. ID is not available before cgroup_init()
+ * (not available in early_init time.)
+ */
+ bool use_id;
#define MAX_CGROUP_TYPE_NAMELEN 32
const char *name;
* - initiating hotplug events
*/
struct mutex hierarchy_mutex;
+ struct lock_class_key subsys_key;
/*
* Link to parent, and list entry in parent's children.
*/
struct cgroupfs_root *root;
struct list_head sibling;
+ /* used when use_id == true */
+ struct idr idr;
+ spinlock_t id_lock;
};
#define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
struct list_head *task;
};
-/* To iterate across the tasks in a cgroup:
+/*
+ * To iterate across the tasks in a cgroup:
*
* 1) call cgroup_iter_start to intialize an iterator
*
*
* 3) call cgroup_iter_end() to destroy the iterator.
*
- * Or, call cgroup_scan_tasks() to iterate through every task in a cpuset.
- * - cgroup_scan_tasks() holds the css_set_lock when calling the test_task()
- * callback, but not while calling the process_task() callback.
+ * Or, call cgroup_scan_tasks() to iterate through every task in a
+ * cgroup - cgroup_scan_tasks() holds the css_set_lock when calling
+ * the test_task() callback, but not while calling the process_task()
+ * callback.
*/
void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it);
struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
int cgroup_scan_tasks(struct cgroup_scanner *scan);
int cgroup_attach_task(struct cgroup *, struct task_struct *);
+/*
+ * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works
+ * if cgroup_subsys.use_id == true. It can be used for looking up and scanning.
+ * CSS ID is assigned at cgroup allocation (create) automatically
+ * and removed when subsys calls free_css_id() function. This is because
+ * the lifetime of cgroup_subsys_state is subsys's matter.
+ *
+ * Looking up and scanning function should be called under rcu_read_lock().
+ * Taking cgroup_mutex()/hierarchy_mutex() is not necessary for following calls.
+ * But the css returned by this routine can be "not populated yet" or "being
+ * destroyed". The caller should check css and cgroup's status.
+ */
+
+/*
+ * Typically Called at ->destroy(), or somewhere the subsys frees
+ * cgroup_subsys_state.
+ */
+void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css);
+
+/* Find a cgroup_subsys_state which has given ID */
+
+struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id);
+
+/*
+ * Get a cgroup whose id is greater than or equal to id under tree of root.
+ * Returning a cgroup_subsys_state or NULL.
+ */
+struct cgroup_subsys_state *css_get_next(struct cgroup_subsys *ss, int id,
+ struct cgroup_subsys_state *root, int *foundid);
+
+/* Returns true if root is ancestor of cg */
+bool css_is_ancestor(struct cgroup_subsys_state *cg,
+ struct cgroup_subsys_state *root);
+
+/* Get id and depth of css */
+unsigned short css_id(struct cgroup_subsys_state *css);
+unsigned short css_depth(struct cgroup_subsys_state *css);
+
#else /* !CONFIG_CGROUPS */
static inline int cgroup_init_early(void) { return 0; }
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