1 #ifndef _LINUX_CGROUP_H 2 #define _LINUX_CGROUP_H 3 /* 4 * cgroup interface 5 * 6 * Copyright (C) 2003 BULL SA 7 * Copyright (C) 2004-2006 Silicon Graphics, Inc. 8 * 9 */ 10 11 #include <linux/sched.h> 12 #include <linux/kref.h> 13 #include <linux/cpumask.h> 14 #include <linux/nodemask.h> 15 #include <linux/rcupdate.h> 16 #include <linux/cgroupstats.h> 17 #include <linux/prio_heap.h> 18 19 #ifdef CONFIG_CGROUPS 20 21 struct cgroupfs_root; 22 struct cgroup_subsys; 23 struct inode; 24 25 extern int cgroup_init_early(void); 26 extern int cgroup_init(void); 27 extern void cgroup_init_smp(void); 28 extern void cgroup_lock(void); 29 extern void cgroup_unlock(void); 30 extern void cgroup_fork(struct task_struct *p); 31 extern void cgroup_fork_callbacks(struct task_struct *p); 32 extern void cgroup_post_fork(struct task_struct *p); 33 extern void cgroup_exit(struct task_struct *p, int run_callbacks); 34 extern int cgroupstats_build(struct cgroupstats *stats, 35 struct dentry *dentry); 36 37 extern struct file_operations proc_cgroup_operations; 38 39 /* Define the enumeration of all cgroup subsystems */ 40 #define SUBSYS(_x) _x ## _subsys_id, 41 enum cgroup_subsys_id { 42 #include <linux/cgroup_subsys.h> 43 CGROUP_SUBSYS_COUNT 44 }; 45 #undef SUBSYS 46 47 /* Per-subsystem/per-cgroup state maintained by the system. */ 48 struct cgroup_subsys_state { 49 /* The cgroup that this subsystem is attached to. Useful 50 * for subsystems that want to know about the cgroup 51 * hierarchy structure */ 52 struct cgroup *cgroup; 53 54 /* State maintained by the cgroup system to allow 55 * subsystems to be "busy". Should be accessed via css_get() 56 * and css_put() */ 57 58 atomic_t refcnt; 59 60 unsigned long flags; 61 }; 62 63 /* bits in struct cgroup_subsys_state flags field */ 64 enum { 65 CSS_ROOT, /* This CSS is the root of the subsystem */ 66 }; 67 68 /* 69 * Call css_get() to hold a reference on the cgroup; 70 * 71 */ 72 73 static inline void css_get(struct cgroup_subsys_state *css) 74 { 75 /* We don't need to reference count the root state */ 76 if (!test_bit(CSS_ROOT, &css->flags)) 77 atomic_inc(&css->refcnt); 78 } 79 /* 80 * css_put() should be called to release a reference taken by 81 * css_get() 82 */ 83 84 extern void __css_put(struct cgroup_subsys_state *css); 85 static inline void css_put(struct cgroup_subsys_state *css) 86 { 87 if (!test_bit(CSS_ROOT, &css->flags)) 88 __css_put(css); 89 } 90 91 struct cgroup { 92 unsigned long flags; /* "unsigned long" so bitops work */ 93 94 /* count users of this cgroup. >0 means busy, but doesn't 95 * necessarily indicate the number of tasks in the 96 * cgroup */ 97 atomic_t count; 98 99 /* 100 * We link our 'sibling' struct into our parent's 'children'. 101 * Our children link their 'sibling' into our 'children'. 102 */ 103 struct list_head sibling; /* my parent's children */ 104 struct list_head children; /* my children */ 105 106 struct cgroup *parent; /* my parent */ 107 struct dentry *dentry; /* cgroup fs entry */ 108 109 /* Private pointers for each registered subsystem */ 110 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; 111 112 struct cgroupfs_root *root; 113 struct cgroup *top_cgroup; 114 115 /* 116 * List of cg_cgroup_links pointing at css_sets with 117 * tasks in this cgroup. Protected by css_set_lock 118 */ 119 struct list_head css_sets; 120 121 /* 122 * Linked list running through all cgroups that can 123 * potentially be reaped by the release agent. Protected by 124 * release_list_lock 125 */ 126 struct list_head release_list; 127 }; 128 129 /* A css_set is a structure holding pointers to a set of 130 * cgroup_subsys_state objects. This saves space in the task struct 131 * object and speeds up fork()/exit(), since a single inc/dec and a 132 * list_add()/del() can bump the reference count on the entire 133 * cgroup set for a task. 134 */ 135 136 struct css_set { 137 138 /* Reference count */ 139 struct kref ref; 140 141 /* 142 * List running through all cgroup groups. Protected by 143 * css_set_lock 144 */ 145 struct list_head list; 146 147 /* 148 * List running through all tasks using this cgroup 149 * group. Protected by css_set_lock 150 */ 151 struct list_head tasks; 152 153 /* 154 * List of cg_cgroup_link objects on link chains from 155 * cgroups referenced from this css_set. Protected by 156 * css_set_lock 157 */ 158 struct list_head cg_links; 159 160 /* 161 * Set of subsystem states, one for each subsystem. This array 162 * is immutable after creation apart from the init_css_set 163 * during subsystem registration (at boot time). 164 */ 165 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; 166 167 }; 168 169 /* struct cftype: 170 * 171 * The files in the cgroup filesystem mostly have a very simple read/write 172 * handling, some common function will take care of it. Nevertheless some cases 173 * (read tasks) are special and therefore I define this structure for every 174 * kind of file. 175 * 176 * 177 * When reading/writing to a file: 178 * - the cgroup to use is file->f_dentry->d_parent->d_fsdata 179 * - the 'cftype' of the file is file->f_dentry->d_fsdata 180 */ 181 182 #define MAX_CFTYPE_NAME 64 183 struct cftype { 184 /* By convention, the name should begin with the name of the 185 * subsystem, followed by a period */ 186 char name[MAX_CFTYPE_NAME]; 187 int private; 188 int (*open) (struct inode *inode, struct file *file); 189 ssize_t (*read) (struct cgroup *cgrp, struct cftype *cft, 190 struct file *file, 191 char __user *buf, size_t nbytes, loff_t *ppos); 192 /* 193 * read_uint() is a shortcut for the common case of returning a 194 * single integer. Use it in place of read() 195 */ 196 u64 (*read_uint) (struct cgroup *cgrp, struct cftype *cft); 197 ssize_t (*write) (struct cgroup *cgrp, struct cftype *cft, 198 struct file *file, 199 const char __user *buf, size_t nbytes, loff_t *ppos); 200 201 /* 202 * write_uint() is a shortcut for the common case of accepting 203 * a single integer (as parsed by simple_strtoull) from 204 * userspace. Use in place of write(); return 0 or error. 205 */ 206 int (*write_uint) (struct cgroup *cgrp, struct cftype *cft, u64 val); 207 208 int (*release) (struct inode *inode, struct file *file); 209 }; 210 211 struct cgroup_scanner { 212 struct cgroup *cg; 213 int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan); 214 void (*process_task)(struct task_struct *p, 215 struct cgroup_scanner *scan); 216 struct ptr_heap *heap; 217 }; 218 219 /* Add a new file to the given cgroup directory. Should only be 220 * called by subsystems from within a populate() method */ 221 int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, 222 const struct cftype *cft); 223 224 /* Add a set of new files to the given cgroup directory. Should 225 * only be called by subsystems from within a populate() method */ 226 int cgroup_add_files(struct cgroup *cgrp, 227 struct cgroup_subsys *subsys, 228 const struct cftype cft[], 229 int count); 230 231 int cgroup_is_removed(const struct cgroup *cgrp); 232 233 int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen); 234 235 int cgroup_task_count(const struct cgroup *cgrp); 236 237 /* Return true if the cgroup is a descendant of the current cgroup */ 238 int cgroup_is_descendant(const struct cgroup *cgrp); 239 240 /* Control Group subsystem type. See Documentation/cgroups.txt for details */ 241 242 struct cgroup_subsys { 243 struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss, 244 struct cgroup *cgrp); 245 void (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); 246 void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); 247 int (*can_attach)(struct cgroup_subsys *ss, 248 struct cgroup *cgrp, struct task_struct *tsk); 249 void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp, 250 struct cgroup *old_cgrp, struct task_struct *tsk); 251 void (*fork)(struct cgroup_subsys *ss, struct task_struct *task); 252 void (*exit)(struct cgroup_subsys *ss, struct task_struct *task); 253 int (*populate)(struct cgroup_subsys *ss, 254 struct cgroup *cgrp); 255 void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp); 256 void (*bind)(struct cgroup_subsys *ss, struct cgroup *root); 257 int subsys_id; 258 int active; 259 int disabled; 260 int early_init; 261 #define MAX_CGROUP_TYPE_NAMELEN 32 262 const char *name; 263 264 /* Protected by RCU */ 265 struct cgroupfs_root *root; 266 267 struct list_head sibling; 268 269 void *private; 270 }; 271 272 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys; 273 #include <linux/cgroup_subsys.h> 274 #undef SUBSYS 275 276 static inline struct cgroup_subsys_state *cgroup_subsys_state( 277 struct cgroup *cgrp, int subsys_id) 278 { 279 return cgrp->subsys[subsys_id]; 280 } 281 282 static inline struct cgroup_subsys_state *task_subsys_state( 283 struct task_struct *task, int subsys_id) 284 { 285 return rcu_dereference(task->cgroups->subsys[subsys_id]); 286 } 287 288 static inline struct cgroup* task_cgroup(struct task_struct *task, 289 int subsys_id) 290 { 291 return task_subsys_state(task, subsys_id)->cgroup; 292 } 293 294 int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss); 295 296 /* A cgroup_iter should be treated as an opaque object */ 297 struct cgroup_iter { 298 struct list_head *cg_link; 299 struct list_head *task; 300 }; 301 302 /* To iterate across the tasks in a cgroup: 303 * 304 * 1) call cgroup_iter_start to intialize an iterator 305 * 306 * 2) call cgroup_iter_next() to retrieve member tasks until it 307 * returns NULL or until you want to end the iteration 308 * 309 * 3) call cgroup_iter_end() to destroy the iterator. 310 * 311 * Or, call cgroup_scan_tasks() to iterate through every task in a cpuset. 312 * - cgroup_scan_tasks() holds the css_set_lock when calling the test_task() 313 * callback, but not while calling the process_task() callback. 314 */ 315 void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it); 316 struct task_struct *cgroup_iter_next(struct cgroup *cgrp, 317 struct cgroup_iter *it); 318 void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it); 319 int cgroup_scan_tasks(struct cgroup_scanner *scan); 320 int cgroup_attach_task(struct cgroup *, struct task_struct *); 321 322 #else /* !CONFIG_CGROUPS */ 323 324 static inline int cgroup_init_early(void) { return 0; } 325 static inline int cgroup_init(void) { return 0; } 326 static inline void cgroup_init_smp(void) {} 327 static inline void cgroup_fork(struct task_struct *p) {} 328 static inline void cgroup_fork_callbacks(struct task_struct *p) {} 329 static inline void cgroup_post_fork(struct task_struct *p) {} 330 static inline void cgroup_exit(struct task_struct *p, int callbacks) {} 331 332 static inline void cgroup_lock(void) {} 333 static inline void cgroup_unlock(void) {} 334 static inline int cgroupstats_build(struct cgroupstats *stats, 335 struct dentry *dentry) 336 { 337 return -EINVAL; 338 } 339 340 #endif /* !CONFIG_CGROUPS */ 341 342 #endif /* _LINUX_CGROUP_H */ 343