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 | |
Paul Gortmaker | 9984de1 | 2011-05-23 14:51:41 -0400 | [diff] [blame] | 17 | #include <linux/export.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 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 25 | /* |
| 26 | * A cgroup is freezing if any FREEZING flags are set. FREEZING_SELF is |
| 27 | * set if "FROZEN" is written to freezer.state cgroupfs file, and cleared |
| 28 | * for "THAWED". FREEZING_PARENT is set if the parent freezer is FREEZING |
| 29 | * for whatever reason. IOW, a cgroup has FREEZING_PARENT set if one of |
| 30 | * its ancestors has FREEZING_SELF set. |
| 31 | */ |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 32 | enum freezer_state_flags { |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 33 | CGROUP_FREEZER_ONLINE = (1 << 0), /* freezer is fully online */ |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 34 | CGROUP_FREEZING_SELF = (1 << 1), /* this freezer is freezing */ |
| 35 | CGROUP_FREEZING_PARENT = (1 << 2), /* the parent freezer is freezing */ |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 36 | CGROUP_FROZEN = (1 << 3), /* this and its descendants frozen */ |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 37 | |
| 38 | /* mask for all FREEZING flags */ |
| 39 | CGROUP_FREEZING = CGROUP_FREEZING_SELF | CGROUP_FREEZING_PARENT, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 40 | }; |
| 41 | |
| 42 | struct freezer { |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 43 | struct cgroup_subsys_state css; |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 44 | unsigned int state; |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 45 | spinlock_t lock; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 46 | }; |
| 47 | |
Tejun Heo | a7c6d55 | 2013-08-08 20:11:23 -0400 | [diff] [blame^] | 48 | static inline struct freezer *css_freezer(struct cgroup_subsys_state *css) |
| 49 | { |
| 50 | return css ? container_of(css, struct freezer, css) : NULL; |
| 51 | } |
| 52 | |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 53 | static inline struct freezer *cgroup_freezer(struct cgroup *cgroup) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 54 | { |
Tejun Heo | a7c6d55 | 2013-08-08 20:11:23 -0400 | [diff] [blame^] | 55 | return css_freezer(cgroup_css(cgroup, freezer_subsys_id)); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 56 | } |
| 57 | |
| 58 | static inline struct freezer *task_freezer(struct task_struct *task) |
| 59 | { |
Tejun Heo | a7c6d55 | 2013-08-08 20:11:23 -0400 | [diff] [blame^] | 60 | return css_freezer(task_css(task, freezer_subsys_id)); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 61 | } |
| 62 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 63 | static struct freezer *parent_freezer(struct freezer *freezer) |
| 64 | { |
| 65 | struct cgroup *pcg = freezer->css.cgroup->parent; |
| 66 | |
| 67 | if (pcg) |
| 68 | return cgroup_freezer(pcg); |
| 69 | return NULL; |
| 70 | } |
| 71 | |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 72 | bool cgroup_freezing(struct task_struct *task) |
Tomasz Buchert | d5de4ddb | 2010-10-27 15:33:32 -0700 | [diff] [blame] | 73 | { |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 74 | bool ret; |
Tomasz Buchert | d5de4ddb | 2010-10-27 15:33:32 -0700 | [diff] [blame] | 75 | |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 76 | rcu_read_lock(); |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 77 | ret = task_freezer(task)->state & CGROUP_FREEZING; |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 78 | rcu_read_unlock(); |
| 79 | |
| 80 | return ret; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 81 | } |
| 82 | |
| 83 | /* |
| 84 | * cgroups_write_string() limits the size of freezer state strings to |
| 85 | * CGROUP_LOCAL_BUFFER_SIZE |
| 86 | */ |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 87 | static const char *freezer_state_strs(unsigned int state) |
| 88 | { |
| 89 | if (state & CGROUP_FROZEN) |
| 90 | return "FROZEN"; |
| 91 | if (state & CGROUP_FREEZING) |
| 92 | return "FREEZING"; |
| 93 | return "THAWED"; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 94 | }; |
| 95 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 96 | struct cgroup_subsys freezer_subsys; |
| 97 | |
Tejun Heo | 92fb974 | 2012-11-19 08:13:38 -0800 | [diff] [blame] | 98 | static struct cgroup_subsys_state *freezer_css_alloc(struct cgroup *cgroup) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 99 | { |
| 100 | struct freezer *freezer; |
| 101 | |
| 102 | freezer = kzalloc(sizeof(struct freezer), GFP_KERNEL); |
| 103 | if (!freezer) |
| 104 | return ERR_PTR(-ENOMEM); |
| 105 | |
| 106 | spin_lock_init(&freezer->lock); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 107 | return &freezer->css; |
| 108 | } |
| 109 | |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 110 | /** |
Tejun Heo | 92fb974 | 2012-11-19 08:13:38 -0800 | [diff] [blame] | 111 | * freezer_css_online - commit creation of a freezer cgroup |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 112 | * @cgroup: cgroup being created |
| 113 | * |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 114 | * We're committing to creation of @cgroup. Mark it online and inherit |
| 115 | * parent's freezing state while holding both parent's and our |
| 116 | * freezer->lock. |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 117 | */ |
Tejun Heo | 92fb974 | 2012-11-19 08:13:38 -0800 | [diff] [blame] | 118 | static int freezer_css_online(struct cgroup *cgroup) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 119 | { |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 120 | struct freezer *freezer = cgroup_freezer(cgroup); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 121 | struct freezer *parent = parent_freezer(freezer); |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 122 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 123 | /* |
| 124 | * The following double locking and freezing state inheritance |
| 125 | * guarantee that @cgroup can never escape ancestors' freezing |
| 126 | * states. See cgroup_for_each_descendant_pre() for details. |
| 127 | */ |
| 128 | if (parent) |
| 129 | spin_lock_irq(&parent->lock); |
| 130 | spin_lock_nested(&freezer->lock, SINGLE_DEPTH_NESTING); |
| 131 | |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 132 | freezer->state |= CGROUP_FREEZER_ONLINE; |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 133 | |
| 134 | if (parent && (parent->state & CGROUP_FREEZING)) { |
| 135 | freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN; |
| 136 | atomic_inc(&system_freezing_cnt); |
| 137 | } |
| 138 | |
| 139 | spin_unlock(&freezer->lock); |
| 140 | if (parent) |
| 141 | spin_unlock_irq(&parent->lock); |
Tejun Heo | b1929db | 2012-11-19 08:13:38 -0800 | [diff] [blame] | 142 | |
| 143 | return 0; |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 144 | } |
| 145 | |
| 146 | /** |
Tejun Heo | 92fb974 | 2012-11-19 08:13:38 -0800 | [diff] [blame] | 147 | * freezer_css_offline - initiate destruction of @cgroup |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 148 | * @cgroup: cgroup being destroyed |
| 149 | * |
| 150 | * @cgroup is going away. Mark it dead and decrement system_freezing_count |
| 151 | * if it was holding one. |
| 152 | */ |
Tejun Heo | 92fb974 | 2012-11-19 08:13:38 -0800 | [diff] [blame] | 153 | static void freezer_css_offline(struct cgroup *cgroup) |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 154 | { |
| 155 | struct freezer *freezer = cgroup_freezer(cgroup); |
| 156 | |
| 157 | spin_lock_irq(&freezer->lock); |
| 158 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 159 | if (freezer->state & CGROUP_FREEZING) |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 160 | atomic_dec(&system_freezing_cnt); |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 161 | |
| 162 | freezer->state = 0; |
| 163 | |
| 164 | spin_unlock_irq(&freezer->lock); |
| 165 | } |
| 166 | |
Tejun Heo | 92fb974 | 2012-11-19 08:13:38 -0800 | [diff] [blame] | 167 | static void freezer_css_free(struct cgroup *cgroup) |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 168 | { |
| 169 | kfree(cgroup_freezer(cgroup)); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 170 | } |
| 171 | |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 172 | /* |
Tejun Heo | ead5c47 | 2012-10-16 15:03:15 -0700 | [diff] [blame] | 173 | * Tasks can be migrated into a different freezer anytime regardless of its |
| 174 | * current state. freezer_attach() is responsible for making new tasks |
| 175 | * conform to the current state. |
| 176 | * |
| 177 | * Freezer state changes and task migration are synchronized via |
| 178 | * @freezer->lock. freezer_attach() makes the new tasks conform to the |
| 179 | * current state and all following state changes can see the new tasks. |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 180 | */ |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 181 | static void freezer_attach(struct cgroup *new_cgrp, struct cgroup_taskset *tset) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 182 | { |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 183 | struct freezer *freezer = cgroup_freezer(new_cgrp); |
Tejun Heo | bb9d97b | 2011-12-12 18:12:21 -0800 | [diff] [blame] | 184 | struct task_struct *task; |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 185 | bool clear_frozen = false; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 186 | |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 187 | spin_lock_irq(&freezer->lock); |
| 188 | |
Li Zefan | 80a6a2c | 2008-10-29 14:00:52 -0700 | [diff] [blame] | 189 | /* |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 190 | * Make the new tasks conform to the current state of @new_cgrp. |
| 191 | * For simplicity, when migrating any task to a FROZEN cgroup, we |
| 192 | * revert it to FREEZING and let update_if_frozen() determine the |
| 193 | * correct state later. |
| 194 | * |
| 195 | * Tasks in @tset are on @new_cgrp but may not conform to its |
| 196 | * current state before executing the following - !frozen tasks may |
| 197 | * be visible in a FROZEN cgroup and frozen tasks in a THAWED one. |
Li Zefan | 80a6a2c | 2008-10-29 14:00:52 -0700 | [diff] [blame] | 198 | */ |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 199 | cgroup_taskset_for_each(task, new_cgrp, tset) { |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 200 | if (!(freezer->state & CGROUP_FREEZING)) { |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 201 | __thaw_task(task); |
| 202 | } else { |
| 203 | freeze_task(task); |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 204 | freezer->state &= ~CGROUP_FROZEN; |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 205 | clear_frozen = true; |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 206 | } |
| 207 | } |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 208 | |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 209 | spin_unlock_irq(&freezer->lock); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 210 | |
| 211 | /* |
| 212 | * Propagate FROZEN clearing upwards. We may race with |
| 213 | * update_if_frozen(), but as long as both work bottom-up, either |
| 214 | * update_if_frozen() sees child's FROZEN cleared or we clear the |
| 215 | * parent's FROZEN later. No parent w/ !FROZEN children can be |
| 216 | * left FROZEN. |
| 217 | */ |
| 218 | while (clear_frozen && (freezer = parent_freezer(freezer))) { |
| 219 | spin_lock_irq(&freezer->lock); |
| 220 | freezer->state &= ~CGROUP_FROZEN; |
| 221 | clear_frozen = freezer->state & CGROUP_FREEZING; |
| 222 | spin_unlock_irq(&freezer->lock); |
| 223 | } |
Ben Blum | f780bdb | 2011-05-26 16:25:19 -0700 | [diff] [blame] | 224 | } |
| 225 | |
Li Zefan | 761b3ef | 2012-01-31 13:47:36 +0800 | [diff] [blame] | 226 | static void freezer_fork(struct task_struct *task) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 227 | { |
| 228 | struct freezer *freezer; |
| 229 | |
Paul E. McKenney | 8b46f88 | 2010-04-21 13:02:08 -0700 | [diff] [blame] | 230 | rcu_read_lock(); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 231 | freezer = task_freezer(task); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 232 | |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 233 | /* |
| 234 | * The root cgroup is non-freezable, so we can skip the |
| 235 | * following check. |
| 236 | */ |
| 237 | if (!freezer->css.cgroup->parent) |
Tejun Heo | 5edee61 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 238 | goto out; |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 239 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 240 | spin_lock_irq(&freezer->lock); |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 241 | if (freezer->state & CGROUP_FREEZING) |
Tejun Heo | 839e340 | 2011-11-21 12:32:26 -0800 | [diff] [blame] | 242 | freeze_task(task); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 243 | spin_unlock_irq(&freezer->lock); |
Tejun Heo | 5edee61 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 244 | out: |
| 245 | rcu_read_unlock(); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 246 | } |
| 247 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 248 | /** |
| 249 | * update_if_frozen - update whether a cgroup finished freezing |
| 250 | * @cgroup: cgroup of interest |
| 251 | * |
| 252 | * Once FREEZING is initiated, transition to FROZEN is lazily updated by |
| 253 | * calling this function. If the current state is FREEZING but not FROZEN, |
| 254 | * this function checks whether all tasks of this cgroup and the descendant |
| 255 | * cgroups finished freezing and, if so, sets FROZEN. |
| 256 | * |
| 257 | * The caller is responsible for grabbing RCU read lock and calling |
| 258 | * update_if_frozen() on all descendants prior to invoking this function. |
Tejun Heo | b4d1831 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 259 | * |
| 260 | * Task states and freezer state might disagree while tasks are being |
Tejun Heo | ead5c47 | 2012-10-16 15:03:15 -0700 | [diff] [blame] | 261 | * migrated into or out of @cgroup, so we can't verify task states against |
| 262 | * @freezer state here. See freezer_attach() for details. |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 263 | */ |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 264 | static void update_if_frozen(struct cgroup *cgroup) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 265 | { |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 266 | struct freezer *freezer = cgroup_freezer(cgroup); |
| 267 | struct cgroup *pos; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 268 | struct cgroup_iter it; |
| 269 | struct task_struct *task; |
Tejun Heo | b4d1831 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 270 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 271 | WARN_ON_ONCE(!rcu_read_lock_held()); |
| 272 | |
| 273 | spin_lock_irq(&freezer->lock); |
| 274 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 275 | if (!(freezer->state & CGROUP_FREEZING) || |
| 276 | (freezer->state & CGROUP_FROZEN)) |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 277 | goto out_unlock; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 278 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 279 | /* are all (live) children frozen? */ |
| 280 | cgroup_for_each_child(pos, cgroup) { |
| 281 | struct freezer *child = cgroup_freezer(pos); |
| 282 | |
| 283 | if ((child->state & CGROUP_FREEZER_ONLINE) && |
| 284 | !(child->state & CGROUP_FROZEN)) |
| 285 | goto out_unlock; |
| 286 | } |
| 287 | |
| 288 | /* are all tasks frozen? */ |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 289 | cgroup_iter_start(cgroup, &it); |
Tejun Heo | b4d1831 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 290 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 291 | while ((task = cgroup_iter_next(cgroup, &it))) { |
Tejun Heo | 3c426d5 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 292 | if (freezing(task)) { |
Tejun Heo | 3c426d5 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 293 | /* |
| 294 | * freezer_should_skip() indicates that the task |
| 295 | * should be skipped when determining freezing |
| 296 | * completion. Consider it frozen in addition to |
| 297 | * the usual frozen condition. |
| 298 | */ |
Oleg Nesterov | 5d8f72b | 2012-10-26 19:46:06 +0200 | [diff] [blame] | 299 | if (!frozen(task) && !freezer_should_skip(task)) |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 300 | goto out_iter_end; |
Tejun Heo | 3c426d5 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 301 | } |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 302 | } |
| 303 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 304 | freezer->state |= CGROUP_FROZEN; |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 305 | out_iter_end: |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 306 | cgroup_iter_end(cgroup, &it); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 307 | out_unlock: |
| 308 | spin_unlock_irq(&freezer->lock); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 309 | } |
| 310 | |
| 311 | static int freezer_read(struct cgroup *cgroup, struct cftype *cft, |
| 312 | struct seq_file *m) |
| 313 | { |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 314 | struct cgroup *pos; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 315 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 316 | rcu_read_lock(); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 317 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 318 | /* update states bottom-up */ |
| 319 | cgroup_for_each_descendant_post(pos, cgroup) |
| 320 | update_if_frozen(pos); |
| 321 | update_if_frozen(cgroup); |
| 322 | |
| 323 | rcu_read_unlock(); |
| 324 | |
| 325 | seq_puts(m, freezer_state_strs(cgroup_freezer(cgroup)->state)); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 326 | seq_putc(m, '\n'); |
| 327 | return 0; |
| 328 | } |
| 329 | |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 330 | static void freeze_cgroup(struct freezer *freezer) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 331 | { |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 332 | struct cgroup *cgroup = freezer->css.cgroup; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 333 | struct cgroup_iter it; |
| 334 | struct task_struct *task; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 335 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 336 | cgroup_iter_start(cgroup, &it); |
Tejun Heo | 51f246e | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 337 | while ((task = cgroup_iter_next(cgroup, &it))) |
| 338 | freeze_task(task); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 339 | cgroup_iter_end(cgroup, &it); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 340 | } |
| 341 | |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 342 | static void unfreeze_cgroup(struct freezer *freezer) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 343 | { |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 344 | struct cgroup *cgroup = freezer->css.cgroup; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 345 | struct cgroup_iter it; |
| 346 | struct task_struct *task; |
| 347 | |
| 348 | cgroup_iter_start(cgroup, &it); |
Tejun Heo | a5be2d0 | 2011-11-21 12:32:23 -0800 | [diff] [blame] | 349 | while ((task = cgroup_iter_next(cgroup, &it))) |
| 350 | __thaw_task(task); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 351 | cgroup_iter_end(cgroup, &it); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 352 | } |
| 353 | |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 354 | /** |
| 355 | * freezer_apply_state - apply state change to a single cgroup_freezer |
| 356 | * @freezer: freezer to apply state change to |
| 357 | * @freeze: whether to freeze or unfreeze |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 358 | * @state: CGROUP_FREEZING_* flag to set or clear |
| 359 | * |
| 360 | * Set or clear @state on @cgroup according to @freeze, and perform |
| 361 | * freezing or thawing as necessary. |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 362 | */ |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 363 | static void freezer_apply_state(struct freezer *freezer, bool freeze, |
| 364 | unsigned int state) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 365 | { |
Tejun Heo | ead5c47 | 2012-10-16 15:03:15 -0700 | [diff] [blame] | 366 | /* also synchronizes against task migration, see freezer_attach() */ |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 367 | lockdep_assert_held(&freezer->lock); |
Li Zefan | 51308ee | 2008-10-29 14:00:54 -0700 | [diff] [blame] | 368 | |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 369 | if (!(freezer->state & CGROUP_FREEZER_ONLINE)) |
| 370 | return; |
| 371 | |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 372 | if (freeze) { |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 373 | if (!(freezer->state & CGROUP_FREEZING)) |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 374 | atomic_inc(&system_freezing_cnt); |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 375 | freezer->state |= state; |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 376 | freeze_cgroup(freezer); |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 377 | } else { |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 378 | bool was_freezing = freezer->state & CGROUP_FREEZING; |
| 379 | |
| 380 | freezer->state &= ~state; |
| 381 | |
| 382 | if (!(freezer->state & CGROUP_FREEZING)) { |
| 383 | if (was_freezing) |
| 384 | atomic_dec(&system_freezing_cnt); |
| 385 | freezer->state &= ~CGROUP_FROZEN; |
| 386 | unfreeze_cgroup(freezer); |
| 387 | } |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 388 | } |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 389 | } |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 390 | |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 391 | /** |
| 392 | * freezer_change_state - change the freezing state of a cgroup_freezer |
| 393 | * @freezer: freezer of interest |
| 394 | * @freeze: whether to freeze or thaw |
| 395 | * |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 396 | * Freeze or thaw @freezer according to @freeze. The operations are |
| 397 | * recursive - all descendants of @freezer will be affected. |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 398 | */ |
| 399 | static void freezer_change_state(struct freezer *freezer, bool freeze) |
| 400 | { |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 401 | struct cgroup *pos; |
| 402 | |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 403 | /* update @freezer */ |
| 404 | spin_lock_irq(&freezer->lock); |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 405 | freezer_apply_state(freezer, freeze, CGROUP_FREEZING_SELF); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 406 | spin_unlock_irq(&freezer->lock); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 407 | |
| 408 | /* |
| 409 | * Update all its descendants in pre-order traversal. Each |
| 410 | * descendant will try to inherit its parent's FREEZING state as |
| 411 | * CGROUP_FREEZING_PARENT. |
| 412 | */ |
| 413 | rcu_read_lock(); |
| 414 | cgroup_for_each_descendant_pre(pos, freezer->css.cgroup) { |
| 415 | struct freezer *pos_f = cgroup_freezer(pos); |
| 416 | struct freezer *parent = parent_freezer(pos_f); |
| 417 | |
| 418 | /* |
| 419 | * Our update to @parent->state is already visible which is |
| 420 | * all we need. No need to lock @parent. For more info on |
| 421 | * synchronization, see freezer_post_create(). |
| 422 | */ |
| 423 | spin_lock_irq(&pos_f->lock); |
| 424 | freezer_apply_state(pos_f, parent->state & CGROUP_FREEZING, |
| 425 | CGROUP_FREEZING_PARENT); |
| 426 | spin_unlock_irq(&pos_f->lock); |
| 427 | } |
| 428 | rcu_read_unlock(); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 429 | } |
| 430 | |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 431 | static int freezer_write(struct cgroup *cgroup, struct cftype *cft, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 432 | const char *buffer) |
| 433 | { |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 434 | bool freeze; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 435 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 436 | if (strcmp(buffer, freezer_state_strs(0)) == 0) |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 437 | freeze = false; |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 438 | else if (strcmp(buffer, freezer_state_strs(CGROUP_FROZEN)) == 0) |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 439 | freeze = true; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 440 | else |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 441 | return -EINVAL; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 442 | |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 443 | freezer_change_state(cgroup_freezer(cgroup), freeze); |
Tejun Heo | 51f246e | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 444 | return 0; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 445 | } |
| 446 | |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 447 | static u64 freezer_self_freezing_read(struct cgroup *cgroup, struct cftype *cft) |
| 448 | { |
| 449 | struct freezer *freezer = cgroup_freezer(cgroup); |
| 450 | |
| 451 | return (bool)(freezer->state & CGROUP_FREEZING_SELF); |
| 452 | } |
| 453 | |
| 454 | static u64 freezer_parent_freezing_read(struct cgroup *cgroup, struct cftype *cft) |
| 455 | { |
| 456 | struct freezer *freezer = cgroup_freezer(cgroup); |
| 457 | |
| 458 | return (bool)(freezer->state & CGROUP_FREEZING_PARENT); |
| 459 | } |
| 460 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 461 | static struct cftype files[] = { |
| 462 | { |
| 463 | .name = "state", |
Tejun Heo | 4baf6e3 | 2012-04-01 12:09:55 -0700 | [diff] [blame] | 464 | .flags = CFTYPE_NOT_ON_ROOT, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 465 | .read_seq_string = freezer_read, |
| 466 | .write_string = freezer_write, |
| 467 | }, |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 468 | { |
| 469 | .name = "self_freezing", |
| 470 | .flags = CFTYPE_NOT_ON_ROOT, |
| 471 | .read_u64 = freezer_self_freezing_read, |
| 472 | }, |
| 473 | { |
| 474 | .name = "parent_freezing", |
| 475 | .flags = CFTYPE_NOT_ON_ROOT, |
| 476 | .read_u64 = freezer_parent_freezing_read, |
| 477 | }, |
Tejun Heo | 4baf6e3 | 2012-04-01 12:09:55 -0700 | [diff] [blame] | 478 | { } /* terminate */ |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 479 | }; |
| 480 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 481 | struct cgroup_subsys freezer_subsys = { |
| 482 | .name = "freezer", |
Tejun Heo | 92fb974 | 2012-11-19 08:13:38 -0800 | [diff] [blame] | 483 | .css_alloc = freezer_css_alloc, |
| 484 | .css_online = freezer_css_online, |
| 485 | .css_offline = freezer_css_offline, |
| 486 | .css_free = freezer_css_free, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 487 | .subsys_id = freezer_subsys_id, |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 488 | .attach = freezer_attach, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 489 | .fork = freezer_fork, |
Tejun Heo | 4baf6e3 | 2012-04-01 12:09:55 -0700 | [diff] [blame] | 490 | .base_cftypes = files, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 491 | }; |