linux/include/linux/cgroup-defs.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * linux/cgroup-defs.h - basic definitions for cgroup
 *
 * This file provides basic type and interface.  Include this file directly
 * only if necessary to avoid cyclic dependencies.
 */
#ifndef _LINUX_CGROUP_DEFS_H
#define _LINUX_CGROUP_DEFS_H

#include <linux/limits.h>
#include <linux/list.h>
#include <linux/idr.h>
#include <linux/wait.h>
#include <linux/mutex.h>
#include <linux/rcupdate.h>
#include <linux/refcount.h>
#include <linux/percpu-refcount.h>
#include <linux/percpu-rwsem.h>
#include <linux/u64_stats_sync.h>
#include <linux/workqueue.h>
#include <linux/bpf-cgroup-defs.h>
#include <linux/psi_types.h>

#ifdef CONFIG_CGROUPS

struct cgroup;
struct cgroup_root;
struct cgroup_subsys;
struct cgroup_taskset;
struct kernfs_node;
struct kernfs_ops;
struct kernfs_open_file;
struct seq_file;
struct poll_table_struct;

#define MAX_CGROUP_TYPE_NAMELEN …
#define MAX_CGROUP_ROOT_NAMELEN …
#define MAX_CFTYPE_NAME …

/* define the enumeration of all cgroup subsystems */
#define SUBSYS …
enum cgroup_subsys_id { … };
#undef SUBSYS

/* bits in struct cgroup_subsys_state flags field */
enum { … };

/* bits in struct cgroup flags field */
enum { … };

/* cgroup_root->flags */
enum { … };

/* cftype->flags */
enum { … };

/*
 * cgroup_file is the handle for a file instance created in a cgroup which
 * is used, for example, to generate file changed notifications.  This can
 * be obtained by setting cftype->file_offset.
 */
struct cgroup_file { … };

/*
 * Per-subsystem/per-cgroup state maintained by the system.  This is the
 * fundamental structural building block that controllers deal with.
 *
 * Fields marked with "PI:" are public and immutable and may be accessed
 * directly without synchronization.
 */
struct cgroup_subsys_state { … };

/*
 * 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.
 */
struct css_set { … };

struct cgroup_base_stat { … };

/*
 * rstat - cgroup scalable recursive statistics.  Accounting is done
 * per-cpu in cgroup_rstat_cpu which is then lazily propagated up the
 * hierarchy on reads.
 *
 * When a stat gets updated, the cgroup_rstat_cpu and its ancestors are
 * linked into the updated tree.  On the following read, propagation only
 * considers and consumes the updated tree.  This makes reading O(the
 * number of descendants which have been active since last read) instead of
 * O(the total number of descendants).
 *
 * This is important because there can be a lot of (draining) cgroups which
 * aren't active and stat may be read frequently.  The combination can
 * become very expensive.  By propagating selectively, increasing reading
 * frequency decreases the cost of each read.
 *
 * This struct hosts both the fields which implement the above -
 * updated_children and updated_next - and the fields which track basic
 * resource statistics on top of it - bsync, bstat and last_bstat.
 */
struct cgroup_rstat_cpu { … };

struct cgroup_freezer_state { … };

struct cgroup { … };

/*
 * A cgroup_root represents the root of a cgroup hierarchy, and may be
 * associated with a kernfs_root to form an active hierarchy.  This is
 * internal to cgroup core.  Don't access directly from controllers.
 */
struct cgroup_root { … };

/*
 * struct cftype: handler definitions for cgroup control files
 *
 * When reading/writing to a file:
 *	- the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
 *	- the 'cftype' of the file is file->f_path.dentry->d_fsdata
 */
struct cftype { … };

/*
 * Control Group subsystem type.
 * See Documentation/admin-guide/cgroup-v1/cgroups.rst for details
 */
struct cgroup_subsys { … };

extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem;

/**
 * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
 * @tsk: target task
 *
 * Allows cgroup operations to synchronize against threadgroup changes
 * using a percpu_rw_semaphore.
 */
static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
{ … }

/**
 * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
 * @tsk: target task
 *
 * Counterpart of cgroup_threadcgroup_change_begin().
 */
static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
{ … }

#else	/* CONFIG_CGROUPS */

#define CGROUP_SUBSYS_COUNT …

static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
{
	might_sleep();
}

static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}

#endif	/* CONFIG_CGROUPS */

#ifdef CONFIG_SOCK_CGROUP_DATA

/*
 * sock_cgroup_data is embedded at sock->sk_cgrp_data and contains
 * per-socket cgroup information except for memcg association.
 *
 * On legacy hierarchies, net_prio and net_cls controllers directly
 * set attributes on each sock which can then be tested by the network
 * layer. On the default hierarchy, each sock is associated with the
 * cgroup it was created in and the networking layer can match the
 * cgroup directly.
 */
struct sock_cgroup_data { … };

static inline u16 sock_cgroup_prioidx(const struct sock_cgroup_data *skcd)
{ … }

static inline u32 sock_cgroup_classid(const struct sock_cgroup_data *skcd)
{ … }

static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd,
					   u16 prioidx)
{ … }

static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd,
					   u32 classid)
{ … }

#else	/* CONFIG_SOCK_CGROUP_DATA */

struct sock_cgroup_data {
};

#endif	/* CONFIG_SOCK_CGROUP_DATA */

#endif	/* _LINUX_CGROUP_DEFS_H */