#ifndef _LINUX_CGROUP_H #define _LINUX_CGROUP_H /* * cgroup interface * * Copyright (C) 2003 BULL SA * Copyright (C) 2004-2006 Silicon Graphics, Inc. * */ #include <linux/sched.h> #include <linux/cpumask.h> #include <linux/nodemask.h> #include <linux/rcupdate.h> #include <linux/cgroupstats.h> #include <linux/prio_heap.h> #include <linux/rwsem.h> #ifdef CONFIG_CGROUPS struct cgroupfs_root; struct cgroup_subsys; struct inode; struct cgroup; extern int cgroup_init_early(void); extern int cgroup_init(void); extern void cgroup_lock(void); extern bool cgroup_lock_live_group(struct cgroup *cgrp); extern void cgroup_unlock(void); extern void cgroup_fork(struct task_struct *p); extern void cgroup_fork_callbacks(struct task_struct *p); extern void cgroup_post_fork(struct task_struct *p); extern void cgroup_exit(struct task_struct *p, int run_callbacks); extern int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry); extern struct file_operations proc_cgroup_operations; /* Define the enumeration of all cgroup subsystems */ #define SUBSYS(_x) _x ## _subsys_id, enum cgroup_subsys_id { #include <linux/cgroup_subsys.h> CGROUP_SUBSYS_COUNT }; #undef SUBSYS /* Per-subsystem/per-cgroup state maintained by the system. */ struct cgroup_subsys_state { /* The cgroup that this subsystem is attached to. Useful * for subsystems that want to know about the cgroup * hierarchy structure */ struct cgroup *cgroup; /* State maintained by the cgroup system to allow subsystems * to be "busy". Should be accessed via css_get(), * css_tryget() and and css_put(). */ atomic_t refcnt; unsigned long flags; }; /* bits in struct cgroup_subsys_state flags field */ enum { CSS_ROOT, /* This CSS is the root of the subsystem */ CSS_REMOVED, /* This CSS is dead */ }; /* * Call css_get() to hold a reference on the css; it can be used * for a reference obtained via: * - an existing ref-counted reference to the css * - task->cgroups for a locked task */ static inline void css_get(struct cgroup_subsys_state *css) { /* We don't need to reference count the root state */ if (!test_bit(CSS_ROOT, &css->flags)) atomic_inc(&css->refcnt); } static inline bool css_is_removed(struct cgroup_subsys_state *css) { return test_bit(CSS_REMOVED, &css->flags); } /* * Call css_tryget() to take a reference on a css if your existing * (known-valid) reference isn't already ref-counted. Returns false if * the css has been destroyed. */ static inline bool css_tryget(struct cgroup_subsys_state *css) { if (test_bit(CSS_ROOT, &css->flags)) return true; while (!atomic_inc_not_zero(&css->refcnt)) { if (test_bit(CSS_REMOVED, &css->flags)) return false; } return true; } /* * css_put() should be called to release a reference taken by * css_get() or css_tryget() */ extern void __css_put(struct cgroup_subsys_state *css); static inline void css_put(struct cgroup_subsys_state *css) { if (!test_bit(CSS_ROOT, &css->flags)) __css_put(css); } /* bits in struct cgroup flags field */ 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) */ 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 */ atomic_t count; /* * We link our 'sibling' struct into our parent's 'children'. * Our children link their 'sibling' into our 'children'. */ struct list_head sibling; /* my parent's children */ struct list_head children; /* my children */ struct cgroup *parent; /* my parent */ struct dentry *dentry; /* cgroup fs entry, RCU protected */ /* Private pointers for each registered subsystem */ struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; struct cgroupfs_root *root; struct cgroup *top_cgroup; /* * List of cg_cgroup_links pointing at css_sets with * tasks in this cgroup. Protected by css_set_lock */ struct list_head css_sets; /* * Linked list running through all cgroups that can * potentially be reaped by the release agent. Protected by * release_list_lock */ struct list_head release_list; /* pids_mutex protects the fields below */ struct rw_semaphore pids_mutex; /* Array of process ids in the cgroup */ pid_t *tasks_pids; /* How many files are using the current tasks_pids array */ int pids_use_count; /* Length of the current tasks_pids array */ int pids_length; /* For RCU-protected deletion */ struct rcu_head rcu_head; }; /* 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; /* * List running through all tasks using this cgroup * group. Protected by css_set_lock */ struct list_head tasks; /* * List of cg_cgroup_link objects on link chains from * cgroups referenced from this css_set. Protected by * css_set_lock */ struct list_head cg_links; /* * 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]; }; /* * cgroup_map_cb is an abstract callback API for reporting map-valued * control files */ struct cgroup_map_cb { int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value); 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. * * * When reading/writing to a file: * - the cgroup to use is file->f_dentry->d_parent->d_fsdata * - the 'cftype' of the file is file->f_dentry->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 */ char name[MAX_CFTYPE_NAME]; int private; /* * If non-zero, defines the maximum length of string that can * be passed to write_string; defaults to 64 */ size_t max_write_len; int (*open)(struct inode *inode, struct file *file); ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft, struct file *file, char __user *buf, size_t nbytes, loff_t *ppos); /* * 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 *cgrp, struct cftype *cft); /* * read_s64() is a signed version of read_u64() */ s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft); /* * read_map() is used for defining a map of key/value * pairs. It should call cb->fill(cb, key, value) for each * entry. The key/value pairs (and their ordering) should not * change between reboots. */ int (*read_map)(struct cgroup *cont, struct cftype *cft, struct cgroup_map_cb *cb); /* * read_seq_string() is used for outputting a simple sequence * using seqfile. */ int (*read_seq_string)(struct cgroup *cont, struct cftype *cft, struct seq_file *m); ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft, struct file *file, const char __user *buf, size_t nbytes, loff_t *ppos); /* * 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 *cgrp, struct cftype *cft, u64 val); /* * write_s64() is a signed version of write_u64() */ int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val); /* * write_string() is passed a nul-terminated kernelspace * buffer of maximum length determined by max_write_len. * Returns 0 or -ve error code. */ int (*write_string)(struct cgroup *cgrp, struct cftype *cft, const char *buffer); /* * trigger() callback can be used to get some kick from the * userspace, when the actual string written is not important * at all. The private field can be used to determine the * kick type for multiplexing. */ int (*trigger)(struct cgroup *cgrp, unsigned int event); int (*release)(struct inode *inode, struct file *file); }; struct cgroup_scanner { struct cgroup *cg; int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan); void (*process_task)(struct task_struct *p, struct cgroup_scanner *scan); struct ptr_heap *heap; }; /* 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 */ int cgroup_add_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, const struct cftype cft[], int count); int cgroup_is_removed(const struct cgroup *cgrp); int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen); 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); /* Control Group subsystem type. See Documentation/cgroups.txt for details */ struct cgroup_subsys { struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss, struct cgroup *cgrp); void (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp, struct task_struct *tsk); void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp, struct cgroup *old_cgrp, struct task_struct *tsk); void (*fork)(struct cgroup_subsys *ss, struct task_struct *task); void (*exit)(struct cgroup_subsys *ss, struct task_struct *task); int (*populate)(struct cgroup_subsys *ss, struct cgroup *cgrp); void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp); void (*bind)(struct cgroup_subsys *ss, struct cgroup *root); int subsys_id; int active; int disabled; int early_init; #define MAX_CGROUP_TYPE_NAMELEN 32 const char *name; /* * Protects sibling/children links of cgroups in this * hierarchy, plus protects which hierarchy (or none) the * subsystem is a part of (i.e. root/sibling). To avoid * potential deadlocks, the following operations should not be * undertaken while holding any hierarchy_mutex: * * - allocating memory * - initiating hotplug events */ struct mutex hierarchy_mutex; /* * Link to parent, and list entry in parent's children. * Protected by this->hierarchy_mutex and cgroup_lock() */ struct cgroupfs_root *root; struct list_head sibling; }; #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys; #include <linux/cgroup_subsys.h> #undef SUBSYS static inline struct cgroup_subsys_state *cgroup_subsys_state( struct cgroup *cgrp, int subsys_id) { return cgrp->subsys[subsys_id]; } static inline struct cgroup_subsys_state *task_subsys_state( struct task_struct *task, int subsys_id) { return rcu_dereference(task->cgroups->subsys[subsys_id]); } static inline struct cgroup* task_cgroup(struct task_struct *task, int subsys_id) { return task_subsys_state(task, subsys_id)->cgroup; } int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss, char *nodename); /* A cgroup_iter should be treated as an opaque object */ struct cgroup_iter { struct list_head *cg_link; struct list_head *task; }; /* To iterate across the tasks in a cgroup: * * 1) call cgroup_iter_start to intialize an iterator * * 2) call cgroup_iter_next() to retrieve member tasks until it * returns NULL or until you want to end the iteration * * 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. */ void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it); struct task_struct *cgroup_iter_next(struct cgroup *cgrp, struct cgroup_iter *it); void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it); int cgroup_scan_tasks(struct cgroup_scanner *scan); int cgroup_attach_task(struct cgroup *, struct task_struct *); #else /* !CONFIG_CGROUPS */ static inline int cgroup_init_early(void) { return 0; } static inline int cgroup_init(void) { return 0; } static inline void cgroup_fork(struct task_struct *p) {} static inline void cgroup_fork_callbacks(struct task_struct *p) {} static inline void cgroup_post_fork(struct task_struct *p) {} static inline void cgroup_exit(struct task_struct *p, int callbacks) {} static inline void cgroup_lock(void) {} static inline void cgroup_unlock(void) {} static inline int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) { return -EINVAL; } #endif /* !CONFIG_CGROUPS */ #endif /* _LINUX_CGROUP_H */