Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 1 | /* |
| 2 | * cgroup_freezer.c - control group freezer subsystem |
| 3 | * |
| 4 | * Copyright IBM Corporation, 2007 |
| 5 | * |
| 6 | * Author : Cedric Le Goater <clg@fr.ibm.com> |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify it |
| 9 | * under the terms of version 2.1 of the GNU Lesser General Public License |
| 10 | * as published by the Free Software Foundation. |
| 11 | * |
| 12 | * This program is distributed in the hope that it would be useful, but |
| 13 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. |
| 15 | */ |
| 16 | |
| 17 | #include <linux/module.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 18 | #include <linux/slab.h> |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 19 | #include <linux/cgroup.h> |
| 20 | #include <linux/fs.h> |
| 21 | #include <linux/uaccess.h> |
| 22 | #include <linux/freezer.h> |
| 23 | #include <linux/seq_file.h> |
| 24 | |
| 25 | enum freezer_state { |
Matt Helsley | 81dcf33 | 2008-10-18 20:27:23 -0700 | [diff] [blame] | 26 | CGROUP_THAWED = 0, |
| 27 | CGROUP_FREEZING, |
| 28 | CGROUP_FROZEN, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 29 | }; |
| 30 | |
| 31 | struct freezer { |
| 32 | struct cgroup_subsys_state css; |
| 33 | enum freezer_state state; |
| 34 | spinlock_t lock; /* protects _writes_ to state */ |
| 35 | }; |
| 36 | |
| 37 | static inline struct freezer *cgroup_freezer( |
| 38 | struct cgroup *cgroup) |
| 39 | { |
| 40 | return container_of( |
| 41 | cgroup_subsys_state(cgroup, freezer_subsys_id), |
| 42 | struct freezer, css); |
| 43 | } |
| 44 | |
| 45 | static inline struct freezer *task_freezer(struct task_struct *task) |
| 46 | { |
| 47 | return container_of(task_subsys_state(task, freezer_subsys_id), |
| 48 | struct freezer, css); |
| 49 | } |
| 50 | |
Tomasz Buchert | d5de4dd | 2010-10-27 15:33:32 -0700 | [diff] [blame] | 51 | static inline int __cgroup_freezing_or_frozen(struct task_struct *task) |
| 52 | { |
| 53 | enum freezer_state state = task_freezer(task)->state; |
| 54 | return (state == CGROUP_FREEZING) || (state == CGROUP_FROZEN); |
| 55 | } |
| 56 | |
Matt Helsley | 5a7aadf | 2010-03-26 23:51:44 +0100 | [diff] [blame] | 57 | int cgroup_freezing_or_frozen(struct task_struct *task) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 58 | { |
Tomasz Buchert | d5de4dd | 2010-10-27 15:33:32 -0700 | [diff] [blame] | 59 | int result; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 60 | task_lock(task); |
Tomasz Buchert | d5de4dd | 2010-10-27 15:33:32 -0700 | [diff] [blame] | 61 | result = __cgroup_freezing_or_frozen(task); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 62 | task_unlock(task); |
Tomasz Buchert | d5de4dd | 2010-10-27 15:33:32 -0700 | [diff] [blame] | 63 | return result; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 64 | } |
| 65 | |
| 66 | /* |
| 67 | * cgroups_write_string() limits the size of freezer state strings to |
| 68 | * CGROUP_LOCAL_BUFFER_SIZE |
| 69 | */ |
| 70 | static const char *freezer_state_strs[] = { |
Matt Helsley | 81dcf33 | 2008-10-18 20:27:23 -0700 | [diff] [blame] | 71 | "THAWED", |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 72 | "FREEZING", |
| 73 | "FROZEN", |
| 74 | }; |
| 75 | |
| 76 | /* |
| 77 | * State diagram |
| 78 | * Transitions are caused by userspace writes to the freezer.state file. |
| 79 | * The values in parenthesis are state labels. The rest are edge labels. |
| 80 | * |
Matt Helsley | 81dcf33 | 2008-10-18 20:27:23 -0700 | [diff] [blame] | 81 | * (THAWED) --FROZEN--> (FREEZING) --FROZEN--> (FROZEN) |
| 82 | * ^ ^ | | |
| 83 | * | \_______THAWED_______/ | |
| 84 | * \__________________________THAWED____________/ |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 85 | */ |
| 86 | |
| 87 | struct cgroup_subsys freezer_subsys; |
| 88 | |
| 89 | /* Locks taken and their ordering |
| 90 | * ------------------------------ |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 91 | * cgroup_mutex (AKA cgroup_lock) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 92 | * freezer->lock |
Matt Helsley | 8f77578 | 2010-05-10 23:18:47 +0200 | [diff] [blame] | 93 | * css_set_lock |
| 94 | * task->alloc_lock (AKA task_lock) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 95 | * task->sighand->siglock |
| 96 | * |
| 97 | * cgroup code forces css_set_lock to be taken before task->alloc_lock |
| 98 | * |
| 99 | * freezer_create(), freezer_destroy(): |
| 100 | * cgroup_mutex [ by cgroup core ] |
| 101 | * |
Matt Helsley | 8f77578 | 2010-05-10 23:18:47 +0200 | [diff] [blame] | 102 | * freezer_can_attach(): |
| 103 | * cgroup_mutex (held by caller of can_attach) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 104 | * |
Matt Helsley | 8f77578 | 2010-05-10 23:18:47 +0200 | [diff] [blame] | 105 | * cgroup_freezing_or_frozen(): |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 106 | * task->alloc_lock (to get task's cgroup) |
| 107 | * |
| 108 | * freezer_fork() (preserving fork() performance means can't take cgroup_mutex): |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 109 | * freezer->lock |
| 110 | * sighand->siglock (if the cgroup is freezing) |
| 111 | * |
| 112 | * freezer_read(): |
| 113 | * cgroup_mutex |
| 114 | * freezer->lock |
Matt Helsley | 8f77578 | 2010-05-10 23:18:47 +0200 | [diff] [blame] | 115 | * write_lock css_set_lock (cgroup iterator start) |
| 116 | * task->alloc_lock |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 117 | * read_lock css_set_lock (cgroup iterator start) |
| 118 | * |
| 119 | * freezer_write() (freeze): |
| 120 | * cgroup_mutex |
| 121 | * freezer->lock |
Matt Helsley | 8f77578 | 2010-05-10 23:18:47 +0200 | [diff] [blame] | 122 | * write_lock css_set_lock (cgroup iterator start) |
| 123 | * task->alloc_lock |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 124 | * read_lock css_set_lock (cgroup iterator start) |
Matt Helsley | 8f77578 | 2010-05-10 23:18:47 +0200 | [diff] [blame] | 125 | * sighand->siglock (fake signal delivery inside freeze_task()) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 126 | * |
| 127 | * freezer_write() (unfreeze): |
| 128 | * cgroup_mutex |
| 129 | * freezer->lock |
Matt Helsley | 8f77578 | 2010-05-10 23:18:47 +0200 | [diff] [blame] | 130 | * write_lock css_set_lock (cgroup iterator start) |
| 131 | * task->alloc_lock |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 132 | * read_lock css_set_lock (cgroup iterator start) |
Matt Helsley | 8f77578 | 2010-05-10 23:18:47 +0200 | [diff] [blame] | 133 | * task->alloc_lock (inside thaw_process(), prevents race with refrigerator()) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 134 | * sighand->siglock |
| 135 | */ |
| 136 | static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss, |
| 137 | struct cgroup *cgroup) |
| 138 | { |
| 139 | struct freezer *freezer; |
| 140 | |
| 141 | freezer = kzalloc(sizeof(struct freezer), GFP_KERNEL); |
| 142 | if (!freezer) |
| 143 | return ERR_PTR(-ENOMEM); |
| 144 | |
| 145 | spin_lock_init(&freezer->lock); |
Matt Helsley | 81dcf33 | 2008-10-18 20:27:23 -0700 | [diff] [blame] | 146 | freezer->state = CGROUP_THAWED; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 147 | return &freezer->css; |
| 148 | } |
| 149 | |
| 150 | static void freezer_destroy(struct cgroup_subsys *ss, |
| 151 | struct cgroup *cgroup) |
| 152 | { |
| 153 | kfree(cgroup_freezer(cgroup)); |
| 154 | } |
| 155 | |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 156 | /* |
| 157 | * The call to cgroup_lock() in the freezer.state write method prevents |
| 158 | * a write to that file racing against an attach, and hence the |
| 159 | * can_attach() result will remain valid until the attach completes. |
| 160 | */ |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 161 | static int freezer_can_attach(struct cgroup_subsys *ss, |
| 162 | struct cgroup *new_cgroup, |
Ben Blum | f780bdb | 2011-05-26 16:25:19 -0700 | [diff] [blame] | 163 | struct task_struct *task) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 164 | { |
| 165 | struct freezer *freezer; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 166 | |
Li Zefan | 80a6a2c | 2008-10-29 14:00:52 -0700 | [diff] [blame] | 167 | /* |
| 168 | * Anything frozen can't move or be moved to/from. |
Li Zefan | 80a6a2c | 2008-10-29 14:00:52 -0700 | [diff] [blame] | 169 | */ |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 170 | |
Tomasz Buchert | 0bdba58 | 2010-10-27 15:33:33 -0700 | [diff] [blame] | 171 | freezer = cgroup_freezer(new_cgroup); |
| 172 | if (freezer->state != CGROUP_THAWED) |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 173 | return -EBUSY; |
| 174 | |
Ben Blum | f780bdb | 2011-05-26 16:25:19 -0700 | [diff] [blame] | 175 | return 0; |
| 176 | } |
| 177 | |
| 178 | static int freezer_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk) |
| 179 | { |
Tomasz Buchert | 0bdba58 | 2010-10-27 15:33:33 -0700 | [diff] [blame] | 180 | rcu_read_lock(); |
Ben Blum | f780bdb | 2011-05-26 16:25:19 -0700 | [diff] [blame] | 181 | if (__cgroup_freezing_or_frozen(tsk)) { |
Tomasz Buchert | 0bdba58 | 2010-10-27 15:33:33 -0700 | [diff] [blame] | 182 | rcu_read_unlock(); |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 183 | return -EBUSY; |
Tomasz Buchert | 0bdba58 | 2010-10-27 15:33:33 -0700 | [diff] [blame] | 184 | } |
| 185 | rcu_read_unlock(); |
Li Zefan | 80a6a2c | 2008-10-29 14:00:52 -0700 | [diff] [blame] | 186 | return 0; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 187 | } |
| 188 | |
| 189 | static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task) |
| 190 | { |
| 191 | struct freezer *freezer; |
| 192 | |
Li Zefan | 6874467 | 2008-11-12 13:26:49 -0800 | [diff] [blame] | 193 | /* |
| 194 | * No lock is needed, since the task isn't on tasklist yet, |
| 195 | * so it can't be moved to another cgroup, which means the |
| 196 | * freezer won't be removed and will be valid during this |
Paul E. McKenney | 8b46f88 | 2010-04-21 13:02:08 -0700 | [diff] [blame] | 197 | * function call. Nevertheless, apply RCU read-side critical |
| 198 | * section to suppress RCU lockdep false positives. |
Li Zefan | 6874467 | 2008-11-12 13:26:49 -0800 | [diff] [blame] | 199 | */ |
Paul E. McKenney | 8b46f88 | 2010-04-21 13:02:08 -0700 | [diff] [blame] | 200 | rcu_read_lock(); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 201 | freezer = task_freezer(task); |
Paul E. McKenney | 8b46f88 | 2010-04-21 13:02:08 -0700 | [diff] [blame] | 202 | rcu_read_unlock(); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 203 | |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 204 | /* |
| 205 | * The root cgroup is non-freezable, so we can skip the |
| 206 | * following check. |
| 207 | */ |
| 208 | if (!freezer->css.cgroup->parent) |
| 209 | return; |
| 210 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 211 | spin_lock_irq(&freezer->lock); |
Li Zefan | 7ccb974 | 2008-10-29 14:00:51 -0700 | [diff] [blame] | 212 | BUG_ON(freezer->state == CGROUP_FROZEN); |
| 213 | |
Matt Helsley | 81dcf33 | 2008-10-18 20:27:23 -0700 | [diff] [blame] | 214 | /* Locking avoids race with FREEZING -> THAWED transitions. */ |
| 215 | if (freezer->state == CGROUP_FREEZING) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 216 | freeze_task(task, true); |
| 217 | spin_unlock_irq(&freezer->lock); |
| 218 | } |
| 219 | |
| 220 | /* |
| 221 | * caller must hold freezer->lock |
| 222 | */ |
Tomasz Buchert | 2d3cbf8 | 2010-10-27 15:33:34 -0700 | [diff] [blame] | 223 | static void update_if_frozen(struct cgroup *cgroup, |
Matt Helsley | 1aece34 | 2008-10-18 20:27:24 -0700 | [diff] [blame] | 224 | struct freezer *freezer) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 225 | { |
| 226 | struct cgroup_iter it; |
| 227 | struct task_struct *task; |
| 228 | unsigned int nfrozen = 0, ntotal = 0; |
Tomasz Buchert | 2d3cbf8 | 2010-10-27 15:33:34 -0700 | [diff] [blame] | 229 | enum freezer_state old_state = freezer->state; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 230 | |
| 231 | cgroup_iter_start(cgroup, &it); |
| 232 | while ((task = cgroup_iter_next(cgroup, &it))) { |
| 233 | ntotal++; |
Tomasz Buchert | 2d3cbf8 | 2010-10-27 15:33:34 -0700 | [diff] [blame] | 234 | if (frozen(task)) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 235 | nfrozen++; |
| 236 | } |
| 237 | |
Tomasz Buchert | 2d3cbf8 | 2010-10-27 15:33:34 -0700 | [diff] [blame] | 238 | if (old_state == CGROUP_THAWED) { |
| 239 | BUG_ON(nfrozen > 0); |
| 240 | } else if (old_state == CGROUP_FREEZING) { |
| 241 | if (nfrozen == ntotal) |
| 242 | freezer->state = CGROUP_FROZEN; |
| 243 | } else { /* old_state == CGROUP_FROZEN */ |
| 244 | BUG_ON(nfrozen != ntotal); |
| 245 | } |
| 246 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 247 | cgroup_iter_end(cgroup, &it); |
| 248 | } |
| 249 | |
| 250 | static int freezer_read(struct cgroup *cgroup, struct cftype *cft, |
| 251 | struct seq_file *m) |
| 252 | { |
| 253 | struct freezer *freezer; |
| 254 | enum freezer_state state; |
| 255 | |
| 256 | if (!cgroup_lock_live_group(cgroup)) |
| 257 | return -ENODEV; |
| 258 | |
| 259 | freezer = cgroup_freezer(cgroup); |
| 260 | spin_lock_irq(&freezer->lock); |
| 261 | state = freezer->state; |
Matt Helsley | 81dcf33 | 2008-10-18 20:27:23 -0700 | [diff] [blame] | 262 | if (state == CGROUP_FREEZING) { |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 263 | /* We change from FREEZING to FROZEN lazily if the cgroup was |
| 264 | * only partially frozen when we exitted write. */ |
Tomasz Buchert | 2d3cbf8 | 2010-10-27 15:33:34 -0700 | [diff] [blame] | 265 | update_if_frozen(cgroup, freezer); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 266 | state = freezer->state; |
| 267 | } |
| 268 | spin_unlock_irq(&freezer->lock); |
| 269 | cgroup_unlock(); |
| 270 | |
| 271 | seq_puts(m, freezer_state_strs[state]); |
| 272 | seq_putc(m, '\n'); |
| 273 | return 0; |
| 274 | } |
| 275 | |
| 276 | static int try_to_freeze_cgroup(struct cgroup *cgroup, struct freezer *freezer) |
| 277 | { |
| 278 | struct cgroup_iter it; |
| 279 | struct task_struct *task; |
| 280 | unsigned int num_cant_freeze_now = 0; |
| 281 | |
Matt Helsley | 81dcf33 | 2008-10-18 20:27:23 -0700 | [diff] [blame] | 282 | freezer->state = CGROUP_FREEZING; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 283 | cgroup_iter_start(cgroup, &it); |
| 284 | while ((task = cgroup_iter_next(cgroup, &it))) { |
| 285 | if (!freeze_task(task, true)) |
| 286 | continue; |
Tomasz Buchert | 2d3cbf8 | 2010-10-27 15:33:34 -0700 | [diff] [blame] | 287 | if (frozen(task)) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 288 | continue; |
| 289 | if (!freezing(task) && !freezer_should_skip(task)) |
| 290 | num_cant_freeze_now++; |
| 291 | } |
| 292 | cgroup_iter_end(cgroup, &it); |
| 293 | |
| 294 | return num_cant_freeze_now ? -EBUSY : 0; |
| 295 | } |
| 296 | |
Li Zefan | 00c2e63 | 2008-10-29 14:00:53 -0700 | [diff] [blame] | 297 | static void unfreeze_cgroup(struct cgroup *cgroup, struct freezer *freezer) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 298 | { |
| 299 | struct cgroup_iter it; |
| 300 | struct task_struct *task; |
| 301 | |
| 302 | cgroup_iter_start(cgroup, &it); |
| 303 | while ((task = cgroup_iter_next(cgroup, &it))) { |
Li Zefan | 00c2e63 | 2008-10-29 14:00:53 -0700 | [diff] [blame] | 304 | thaw_process(task); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 305 | } |
| 306 | cgroup_iter_end(cgroup, &it); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 307 | |
Li Zefan | 00c2e63 | 2008-10-29 14:00:53 -0700 | [diff] [blame] | 308 | freezer->state = CGROUP_THAWED; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 309 | } |
| 310 | |
| 311 | static int freezer_change_state(struct cgroup *cgroup, |
| 312 | enum freezer_state goal_state) |
| 313 | { |
| 314 | struct freezer *freezer; |
| 315 | int retval = 0; |
| 316 | |
| 317 | freezer = cgroup_freezer(cgroup); |
Li Zefan | 51308ee | 2008-10-29 14:00:54 -0700 | [diff] [blame] | 318 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 319 | spin_lock_irq(&freezer->lock); |
Li Zefan | 51308ee | 2008-10-29 14:00:54 -0700 | [diff] [blame] | 320 | |
Tomasz Buchert | 2d3cbf8 | 2010-10-27 15:33:34 -0700 | [diff] [blame] | 321 | update_if_frozen(cgroup, freezer); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 322 | if (goal_state == freezer->state) |
| 323 | goto out; |
Li Zefan | 51308ee | 2008-10-29 14:00:54 -0700 | [diff] [blame] | 324 | |
| 325 | switch (goal_state) { |
Matt Helsley | 81dcf33 | 2008-10-18 20:27:23 -0700 | [diff] [blame] | 326 | case CGROUP_THAWED: |
Li Zefan | 00c2e63 | 2008-10-29 14:00:53 -0700 | [diff] [blame] | 327 | unfreeze_cgroup(cgroup, freezer); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 328 | break; |
Li Zefan | 51308ee | 2008-10-29 14:00:54 -0700 | [diff] [blame] | 329 | case CGROUP_FROZEN: |
| 330 | retval = try_to_freeze_cgroup(cgroup, freezer); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 331 | break; |
Li Zefan | 51308ee | 2008-10-29 14:00:54 -0700 | [diff] [blame] | 332 | default: |
| 333 | BUG(); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 334 | } |
| 335 | out: |
| 336 | spin_unlock_irq(&freezer->lock); |
| 337 | |
| 338 | return retval; |
| 339 | } |
| 340 | |
| 341 | static int freezer_write(struct cgroup *cgroup, |
| 342 | struct cftype *cft, |
| 343 | const char *buffer) |
| 344 | { |
| 345 | int retval; |
| 346 | enum freezer_state goal_state; |
| 347 | |
Matt Helsley | 81dcf33 | 2008-10-18 20:27:23 -0700 | [diff] [blame] | 348 | if (strcmp(buffer, freezer_state_strs[CGROUP_THAWED]) == 0) |
| 349 | goal_state = CGROUP_THAWED; |
| 350 | else if (strcmp(buffer, freezer_state_strs[CGROUP_FROZEN]) == 0) |
| 351 | goal_state = CGROUP_FROZEN; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 352 | else |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 353 | return -EINVAL; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 354 | |
| 355 | if (!cgroup_lock_live_group(cgroup)) |
| 356 | return -ENODEV; |
| 357 | retval = freezer_change_state(cgroup, goal_state); |
| 358 | cgroup_unlock(); |
| 359 | return retval; |
| 360 | } |
| 361 | |
| 362 | static struct cftype files[] = { |
| 363 | { |
| 364 | .name = "state", |
| 365 | .read_seq_string = freezer_read, |
| 366 | .write_string = freezer_write, |
| 367 | }, |
| 368 | }; |
| 369 | |
| 370 | static int freezer_populate(struct cgroup_subsys *ss, struct cgroup *cgroup) |
| 371 | { |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 372 | if (!cgroup->parent) |
| 373 | return 0; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 374 | return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files)); |
| 375 | } |
| 376 | |
| 377 | struct cgroup_subsys freezer_subsys = { |
| 378 | .name = "freezer", |
| 379 | .create = freezer_create, |
| 380 | .destroy = freezer_destroy, |
| 381 | .populate = freezer_populate, |
| 382 | .subsys_id = freezer_subsys_id, |
| 383 | .can_attach = freezer_can_attach, |
Ben Blum | f780bdb | 2011-05-26 16:25:19 -0700 | [diff] [blame] | 384 | .can_attach_task = freezer_can_attach_task, |
| 385 | .pre_attach = NULL, |
| 386 | .attach_task = NULL, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 387 | .attach = NULL, |
| 388 | .fork = freezer_fork, |
| 389 | .exit = NULL, |
| 390 | }; |