cgroup: separate out include/linux/cgroup-defs.h

From 2d728f74bfc071df06773e2fd7577dd5dab6425d Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Wed, 13 May 2015 15:37:01 -0400

This patch separates out cgroup-defs.h from cgroup.h which has grown a
lot of dependencies.  cgroup-defs.h currently only contains constant
and type definitions and can be used to break circular include
dependency.  While moving, definitions are reordered so that
cgroup-defs.h has consistent logical structure.

This patch is pure reorganization.

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 464 insertions, 0 deletions

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
new file mode 100644
index 000000000000..55f3120fb952
--- /dev/null
+++ b/include/linux/cgroup-defs.h
@@ -0,0 +1,464 @@
+/*
+ * 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/percpu-refcount.h>
+#include <linux/workqueue.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;
+
+#define MAX_CGROUP_TYPE_NAMELEN 32
+#define MAX_CGROUP_ROOT_NAMELEN 64
+#define MAX_CFTYPE_NAME         64
+
+/* define the enumeration of all cgroup subsystems */
+#define SUBSYS(_x) _x ## _cgrp_id,
+enum cgroup_subsys_id {
+#include <linux/cgroup_subsys.h>
+        CGROUP_SUBSYS_COUNT,
+};
+#undef SUBSYS
+
+/* bits in struct cgroup_subsys_state flags field */
+enum {
+        CSS_NO_REF      = (1 << 0), /* no reference counting for this css */
+        CSS_ONLINE      = (1 << 1), /* between ->css_online() and ->css_offline() */
+        CSS_RELEASED    = (1 << 2), /* refcnt reached zero, released */
+};
+
+/* bits in struct cgroup flags field */
+enum {
+        /* Control Group requires release notifications to userspace */
+        CGRP_NOTIFY_ON_RELEASE,
+        /*
+         * Clone the parent's configuration when creating a new child
+         * cpuset cgroup.  For historical reasons, this option can be
+         * specified at mount time and thus is implemented here.
+         */
+        CGRP_CPUSET_CLONE_CHILDREN,
+};
+
+/* cgroup_root->flags */
+enum {
+        CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), /* __DEVEL__sane_behavior specified */
+        CGRP_ROOT_NOPREFIX      = (1 << 1), /* mounted subsystems have no named prefix */
+        CGRP_ROOT_XATTR         = (1 << 2), /* supports extended attributes */
+};
+
+/* cftype->flags */
+enum {
+        CFTYPE_ONLY_ON_ROOT     = (1 << 0),     /* only create on root cgrp */
+        CFTYPE_NOT_ON_ROOT      = (1 << 1),     /* don't create on root cgrp */
+        CFTYPE_NO_PREFIX        = (1 << 3),     /* (DON'T USE FOR NEW FILES) no subsys prefix */
+
+        /* internal flags, do not use outside cgroup core proper */
+        __CFTYPE_ONLY_ON_DFL    = (1 << 16),    /* only on default hierarchy */
+        __CFTYPE_NOT_ON_DFL     = (1 << 17),    /* not on default hierarchy */
+};
+
+/*
+ * 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 {
+        /* PI: the cgroup that this css is attached to */
+        struct cgroup *cgroup;
+
+        /* PI: the cgroup subsystem that this css is attached to */
+        struct cgroup_subsys *ss;
+
+        /* reference count - access via css_[try]get() and css_put() */
+        struct percpu_ref refcnt;
+
+        /* PI: the parent css */
+        struct cgroup_subsys_state *parent;
+
+        /* siblings list anchored at the parent's ->children */
+        struct list_head sibling;
+        struct list_head children;
+
+        /*
+         * PI: Subsys-unique ID.  0 is unused and root is always 1.  The
+         * matching css can be looked up using css_from_id().
+         */
+        int id;
+
+        unsigned int flags;
+
+        /*
+         * Monotonically increasing unique serial number which defines a
+         * uniform order among all csses.  It's guaranteed that all
+         * ->children lists are in the ascending order of ->serial_nr and
+         * used to allow interrupting and resuming iterations.
+         */
+        u64 serial_nr;
+
+        /* percpu_ref killing and RCU release */
+        struct rcu_head rcu_head;
+        struct work_struct destroy_work;
+};
+
+/*
+ * 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 {
+        /* Reference count */
+        atomic_t refcount;
+
+        /*
+         * List running through all cgroup groups in the same hash
+         * slot. Protected by css_set_lock
+         */
+        struct hlist_node hlist;
+
+        /*
+         * Lists running through all tasks using this cgroup group.
+         * mg_tasks lists tasks which belong to this cset but are in the
+         * process of being migrated out or in.  Protected by
+         * css_set_rwsem, but, during migration, once tasks are moved to
+         * mg_tasks, it can be read safely while holding cgroup_mutex.
+         */
+        struct list_head tasks;
+        struct list_head mg_tasks;
+
+        /*
+         * List of cgrp_cset_links pointing at cgroups referenced from this
+         * css_set.  Protected by css_set_lock.
+         */
+        struct list_head cgrp_links;
+
+        /* the default cgroup associated with this css_set */
+        struct cgroup *dfl_cgrp;
+
+        /*
+         * Set of subsystem states, one for each subsystem. This array is
+         * immutable after creation apart from the init_css_set during
+         * subsystem registration (at boot time).
+         */
+        struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
+
+        /*
+         * List of csets participating in the on-going migration either as
+         * source or destination.  Protected by cgroup_mutex.
+         */
+        struct list_head mg_preload_node;
+        struct list_head mg_node;
+
+        /*
+         * If this cset is acting as the source of migration the following
+         * two fields are set.  mg_src_cgrp is the source cgroup of the
+         * on-going migration and mg_dst_cset is the destination cset the
+         * target tasks on this cset should be migrated to.  Protected by
+         * cgroup_mutex.
+         */
+        struct cgroup *mg_src_cgrp;
+        struct css_set *mg_dst_cset;
+
+        /*
+         * On the default hierarhcy, ->subsys[ssid] may point to a css
+         * attached to an ancestor instead of the cgroup this css_set is
+         * associated with.  The following node is anchored at
+         * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
+         * iterate through all css's attached to a given cgroup.
+         */
+        struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
+
+        /* For RCU-protected deletion */
+        struct rcu_head rcu_head;
+};
+
+struct cgroup {
+        /* self css with NULL ->ss, points back to this cgroup */
+        struct cgroup_subsys_state self;
+
+        unsigned long flags;            /* "unsigned long" so bitops work */
+
+        /*
+         * idr allocated in-hierarchy ID.
+         *
+         * ID 0 is not used, the ID of the root cgroup is always 1, and a
+         * new cgroup will be assigned with a smallest available ID.
+         *
+         * Allocating/Removing ID must be protected by cgroup_mutex.
+         */
+        int id;
+
+        /*
+         * If this cgroup contains any tasks, it contributes one to
+         * populated_cnt.  All children with non-zero popuplated_cnt of
+         * their own contribute one.  The count is zero iff there's no task
+         * in this cgroup or its subtree.
+         */
+        int populated_cnt;
+
+        struct kernfs_node *kn;         /* cgroup kernfs entry */
+        struct kernfs_node *populated_kn; /* kn for "cgroup.subtree_populated" */
+
+        /*
+         * The bitmask of subsystems enabled on the child cgroups.
+         * ->subtree_control is the one configured through
+         * "cgroup.subtree_control" while ->child_subsys_mask is the
+         * effective one which may have more subsystems enabled.
+         * Controller knobs are made available iff it's enabled in
+         * ->subtree_control.
+         */
+        unsigned int subtree_control;
+        unsigned int child_subsys_mask;
+
+        /* Private pointers for each registered subsystem */
+        struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
+
+        struct cgroup_root *root;
+
+        /*
+         * List of cgrp_cset_links pointing at css_sets with tasks in this
+         * cgroup.  Protected by css_set_lock.
+         */
+        struct list_head cset_links;
+
+        /*
+         * On the default hierarchy, a css_set for a cgroup with some
+         * susbsys disabled will point to css's which are associated with
+         * the closest ancestor which has the subsys enabled.  The
+         * following lists all css_sets which point to this cgroup's css
+         * for the given subsystem.
+         */
+        struct list_head e_csets[CGROUP_SUBSYS_COUNT];
+
+        /*
+         * list of pidlists, up to two for each namespace (one for procs, one
+         * for tasks); created on demand.
+         */
+        struct list_head pidlists;
+        struct mutex pidlist_mutex;
+
+        /* used to wait for offlining of csses */
+        wait_queue_head_t offline_waitq;
+
+        /* used to schedule release agent */
+        struct work_struct release_agent_work;
+};
+
+/*
+ * 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 kernfs_root *kf_root;
+
+        /* The bitmask of subsystems attached to this hierarchy */
+        unsigned int subsys_mask;
+
+        /* Unique id for this hierarchy. */
+        int hierarchy_id;
+
+        /* The root cgroup.  Root is destroyed on its release. */
+        struct cgroup cgrp;
+
+        /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
+        atomic_t nr_cgrps;
+
+        /* A list running through the active hierarchies */
+        struct list_head root_list;
+
+        /* Hierarchy-specific flags */
+        unsigned int flags;
+
+        /* IDs for cgroups in this hierarchy */
+        struct idr cgroup_idr;
+
+        /* The path to use for release notifications. */
+        char release_agent_path[PATH_MAX];
+
+        /* The name for this hierarchy - may be empty */
+        char name[MAX_CGROUP_ROOT_NAMELEN];
+};
+
+/*
+ * 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 {
+        /*
+         * By convention, the name should begin with the name of the
+         * subsystem, followed by a period.  Zero length string indicates
+         * end of cftype array.
+         */
+        char name[MAX_CFTYPE_NAME];
+        int private;
+        /*
+         * If not 0, file mode is set to this value, otherwise it will
+         * be figured out automatically
+         */
+        umode_t mode;
+
+        /*
+         * The maximum length of string, excluding trailing nul, that can
+         * be passed to write.  If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
+         */
+        size_t max_write_len;
+
+        /* CFTYPE_* flags */
+        unsigned int flags;
+
+        /*
+         * Fields used for internal bookkeeping.  Initialized automatically
+         * during registration.
+         */
+        struct cgroup_subsys *ss;       /* NULL for cgroup core files */
+        struct list_head node;          /* anchored at ss->cfts */
+        struct kernfs_ops *kf_ops;
+
+        /*
+         * read_u64() is a shortcut for the common case of returning a
+         * single integer. Use it in place of read()
+         */
+        u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
+        /*
+         * read_s64() is a signed version of read_u64()
+         */
+        s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
+
+        /* generic seq_file read interface */
+        int (*seq_show)(struct seq_file *sf, void *v);
+
+        /* optional ops, implement all or none */
+        void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
+        void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
+        void (*seq_stop)(struct seq_file *sf, void *v);
+
+        /*
+         * write_u64() is a shortcut for the common case of accepting
+         * a single integer (as parsed by simple_strtoull) from
+         * userspace. Use in place of write(); return 0 or error.
+         */
+        int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
+                         u64 val);
+        /*
+         * write_s64() is a signed version of write_u64()
+         */
+        int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
+                         s64 val);
+
+        /*
+         * write() is the generic write callback which maps directly to
+         * kernfs write operation and overrides all other operations.
+         * Maximum write size is determined by ->max_write_len.  Use
+         * of_css/cft() to access the associated css and cft.
+         */
+        ssize_t (*write)(struct kernfs_open_file *of,
+                         char *buf, size_t nbytes, loff_t off);
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        struct lock_class_key   lockdep_key;
+#endif
+};
+
+/*
+ * Control Group subsystem type.
+ * See Documentation/cgroups/cgroups.txt for details
+ */
+struct cgroup_subsys {
+        struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
+        int (*css_online)(struct cgroup_subsys_state *css);
+        void (*css_offline)(struct cgroup_subsys_state *css);
+        void (*css_released)(struct cgroup_subsys_state *css);
+        void (*css_free)(struct cgroup_subsys_state *css);
+        void (*css_reset)(struct cgroup_subsys_state *css);
+        void (*css_e_css_changed)(struct cgroup_subsys_state *css);
+
+        int (*can_attach)(struct cgroup_subsys_state *css,
+                          struct cgroup_taskset *tset);
+        void (*cancel_attach)(struct cgroup_subsys_state *css,
+                              struct cgroup_taskset *tset);
+        void (*attach)(struct cgroup_subsys_state *css,
+                       struct cgroup_taskset *tset);
+        void (*fork)(struct task_struct *task);
+        void (*exit)(struct cgroup_subsys_state *css,
+                     struct cgroup_subsys_state *old_css,
+                     struct task_struct *task);
+        void (*bind)(struct cgroup_subsys_state *root_css);
+
+        int disabled;
+        int early_init;
+
+        /*
+         * If %false, this subsystem is properly hierarchical -
+         * configuration, resource accounting and restriction on a parent
+         * cgroup cover those of its children.  If %true, hierarchy support
+         * is broken in some ways - some subsystems ignore hierarchy
+         * completely while others are only implemented half-way.
+         *
+         * It's now disallowed to create nested cgroups if the subsystem is
+         * broken and cgroup core will emit a warning message on such
+         * cases.  Eventually, all subsystems will be made properly
+         * hierarchical and this will go away.
+         */
+        bool broken_hierarchy;
+        bool warned_broken_hierarchy;
+
+        /* the following two fields are initialized automtically during boot */
+        int id;
+        const char *name;
+
+        /* link to parent, protected by cgroup_lock() */
+        struct cgroup_root *root;
+
+        /* idr for css->id */
+        struct idr css_idr;
+
+        /*
+         * List of cftypes.  Each entry is the first entry of an array
+         * terminated by zero length name.
+         */
+        struct list_head cfts;
+
+        /*
+         * Base cftypes which are automatically registered.  The two can
+         * point to the same array.
+         */
+        struct cftype *dfl_cftypes;     /* for the default hierarchy */
+        struct cftype *legacy_cftypes;  /* for the legacy hierarchies */
+
+        /*
+         * A subsystem may depend on other subsystems.  When such subsystem
+         * is enabled on a cgroup, the depended-upon subsystems are enabled
+         * together if available.  Subsystems enabled due to dependency are
+         * not visible to userland until explicitly enabled.  The following
+         * specifies the mask of subsystems that this one depends on.
+         */
+        unsigned int depends_on;
+};
+
+#endif  /* CONFIG_CGROUPS */
+#endif  /* _LINUX_CGROUP_DEFS_H */