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 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 53 | static inline struct freezer *task_freezer(struct task_struct *task) |
| 54 | { |
Tejun Heo | 073219e | 2014-02-08 10:36:58 -0500 | [diff] [blame] | 55 | return css_freezer(task_css(task, freezer_cgrp_id)); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 56 | } |
| 57 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 58 | static struct freezer *parent_freezer(struct freezer *freezer) |
| 59 | { |
Tejun Heo | 6387698 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 60 | return css_freezer(css_parent(&freezer->css)); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 61 | } |
| 62 | |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 63 | bool cgroup_freezing(struct task_struct *task) |
Tomasz Buchert | d5de4dd | 2010-10-27 15:33:32 -0700 | [diff] [blame] | 64 | { |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 65 | bool ret; |
Tomasz Buchert | d5de4dd | 2010-10-27 15:33:32 -0700 | [diff] [blame] | 66 | |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 67 | rcu_read_lock(); |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 68 | ret = task_freezer(task)->state & CGROUP_FREEZING; |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 69 | rcu_read_unlock(); |
| 70 | |
| 71 | return ret; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 72 | } |
| 73 | |
| 74 | /* |
| 75 | * cgroups_write_string() limits the size of freezer state strings to |
| 76 | * CGROUP_LOCAL_BUFFER_SIZE |
| 77 | */ |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 78 | static const char *freezer_state_strs(unsigned int state) |
| 79 | { |
| 80 | if (state & CGROUP_FROZEN) |
| 81 | return "FROZEN"; |
| 82 | if (state & CGROUP_FREEZING) |
| 83 | return "FREEZING"; |
| 84 | return "THAWED"; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 85 | }; |
| 86 | |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 87 | static struct cgroup_subsys_state * |
| 88 | freezer_css_alloc(struct cgroup_subsys_state *parent_css) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 89 | { |
| 90 | struct freezer *freezer; |
| 91 | |
| 92 | freezer = kzalloc(sizeof(struct freezer), GFP_KERNEL); |
| 93 | if (!freezer) |
| 94 | return ERR_PTR(-ENOMEM); |
| 95 | |
| 96 | spin_lock_init(&freezer->lock); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 97 | return &freezer->css; |
| 98 | } |
| 99 | |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 100 | /** |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 101 | * freezer_css_online - commit creation of a freezer css |
| 102 | * @css: css being created |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 103 | * |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 104 | * We're committing to creation of @css. Mark it online and inherit |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 105 | * parent's freezing state while holding both parent's and our |
| 106 | * freezer->lock. |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 107 | */ |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 108 | static int freezer_css_online(struct cgroup_subsys_state *css) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 109 | { |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 110 | struct freezer *freezer = css_freezer(css); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 111 | struct freezer *parent = parent_freezer(freezer); |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 112 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 113 | /* |
| 114 | * The following double locking and freezing state inheritance |
| 115 | * guarantee that @cgroup can never escape ancestors' freezing |
Tejun Heo | 492eb21 | 2013-08-08 20:11:25 -0400 | [diff] [blame] | 116 | * states. See css_for_each_descendant_pre() for details. |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 117 | */ |
| 118 | if (parent) |
| 119 | spin_lock_irq(&parent->lock); |
| 120 | spin_lock_nested(&freezer->lock, SINGLE_DEPTH_NESTING); |
| 121 | |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 122 | freezer->state |= CGROUP_FREEZER_ONLINE; |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 123 | |
| 124 | if (parent && (parent->state & CGROUP_FREEZING)) { |
| 125 | freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN; |
| 126 | atomic_inc(&system_freezing_cnt); |
| 127 | } |
| 128 | |
| 129 | spin_unlock(&freezer->lock); |
| 130 | if (parent) |
| 131 | spin_unlock_irq(&parent->lock); |
Tejun Heo | b1929db | 2012-11-19 08:13:38 -0800 | [diff] [blame] | 132 | |
| 133 | return 0; |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 134 | } |
| 135 | |
| 136 | /** |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 137 | * freezer_css_offline - initiate destruction of a freezer css |
| 138 | * @css: css being destroyed |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 139 | * |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 140 | * @css is going away. Mark it dead and decrement system_freezing_count if |
| 141 | * it was holding one. |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 142 | */ |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 143 | static void freezer_css_offline(struct cgroup_subsys_state *css) |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 144 | { |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 145 | struct freezer *freezer = css_freezer(css); |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 146 | |
| 147 | spin_lock_irq(&freezer->lock); |
| 148 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 149 | if (freezer->state & CGROUP_FREEZING) |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 150 | atomic_dec(&system_freezing_cnt); |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 151 | |
| 152 | freezer->state = 0; |
| 153 | |
| 154 | spin_unlock_irq(&freezer->lock); |
| 155 | } |
| 156 | |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 157 | static void freezer_css_free(struct cgroup_subsys_state *css) |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 158 | { |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 159 | kfree(css_freezer(css)); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 160 | } |
| 161 | |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 162 | /* |
Tejun Heo | ead5c47 | 2012-10-16 15:03:15 -0700 | [diff] [blame] | 163 | * Tasks can be migrated into a different freezer anytime regardless of its |
| 164 | * current state. freezer_attach() is responsible for making new tasks |
| 165 | * conform to the current state. |
| 166 | * |
| 167 | * Freezer state changes and task migration are synchronized via |
| 168 | * @freezer->lock. freezer_attach() makes the new tasks conform to the |
| 169 | * current state and all following state changes can see the new tasks. |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 170 | */ |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 171 | static void freezer_attach(struct cgroup_subsys_state *new_css, |
| 172 | struct cgroup_taskset *tset) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 173 | { |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 174 | struct freezer *freezer = css_freezer(new_css); |
Tejun Heo | bb9d97b | 2011-12-12 18:12:21 -0800 | [diff] [blame] | 175 | struct task_struct *task; |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 176 | bool clear_frozen = false; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 177 | |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 178 | spin_lock_irq(&freezer->lock); |
| 179 | |
Li Zefan | 80a6a2c | 2008-10-29 14:00:52 -0700 | [diff] [blame] | 180 | /* |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 181 | * Make the new tasks conform to the current state of @new_css. |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 182 | * For simplicity, when migrating any task to a FROZEN cgroup, we |
| 183 | * revert it to FREEZING and let update_if_frozen() determine the |
| 184 | * correct state later. |
| 185 | * |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 186 | * Tasks in @tset are on @new_css but may not conform to its |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 187 | * current state before executing the following - !frozen tasks may |
| 188 | * 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] | 189 | */ |
Tejun Heo | 924f0d9 | 2014-02-13 06:58:41 -0500 | [diff] [blame] | 190 | cgroup_taskset_for_each(task, tset) { |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 191 | if (!(freezer->state & CGROUP_FREEZING)) { |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 192 | __thaw_task(task); |
| 193 | } else { |
| 194 | freeze_task(task); |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 195 | freezer->state &= ~CGROUP_FROZEN; |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 196 | clear_frozen = true; |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 197 | } |
| 198 | } |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 199 | |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 200 | spin_unlock_irq(&freezer->lock); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 201 | |
| 202 | /* |
| 203 | * Propagate FROZEN clearing upwards. We may race with |
| 204 | * update_if_frozen(), but as long as both work bottom-up, either |
| 205 | * update_if_frozen() sees child's FROZEN cleared or we clear the |
| 206 | * parent's FROZEN later. No parent w/ !FROZEN children can be |
| 207 | * left FROZEN. |
| 208 | */ |
| 209 | while (clear_frozen && (freezer = parent_freezer(freezer))) { |
| 210 | spin_lock_irq(&freezer->lock); |
| 211 | freezer->state &= ~CGROUP_FROZEN; |
| 212 | clear_frozen = freezer->state & CGROUP_FREEZING; |
| 213 | spin_unlock_irq(&freezer->lock); |
| 214 | } |
Ben Blum | f780bdb | 2011-05-26 16:25:19 -0700 | [diff] [blame] | 215 | } |
| 216 | |
Tejun Heo | a60bed2 | 2014-02-12 16:07:59 -0500 | [diff] [blame] | 217 | /** |
| 218 | * freezer_fork - cgroup post fork callback |
| 219 | * @task: a task which has just been forked |
| 220 | * |
| 221 | * @task has just been created and should conform to the current state of |
| 222 | * the cgroup_freezer it belongs to. This function may race against |
| 223 | * freezer_attach(). Losing to freezer_attach() means that we don't have |
| 224 | * to do anything as freezer_attach() will put @task into the appropriate |
| 225 | * state. |
| 226 | */ |
Li Zefan | 761b3ef | 2012-01-31 13:47:36 +0800 | [diff] [blame] | 227 | static void freezer_fork(struct task_struct *task) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 228 | { |
| 229 | struct freezer *freezer; |
| 230 | |
Paul E. McKenney | 8b46f88 | 2010-04-21 13:02:08 -0700 | [diff] [blame] | 231 | rcu_read_lock(); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 232 | freezer = task_freezer(task); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 233 | |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 234 | /* |
Tejun Heo | a60bed2 | 2014-02-12 16:07:59 -0500 | [diff] [blame] | 235 | * The root cgroup is non-freezable, so we can skip locking the |
| 236 | * freezer. This is safe regardless of race with task migration. |
| 237 | * If we didn't race or won, skipping is obviously the right thing |
| 238 | * to do. If we lost and root is the new cgroup, noop is still the |
| 239 | * right thing to do. |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 240 | */ |
Tejun Heo | 6387698 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 241 | if (!parent_freezer(freezer)) |
Tejun Heo | 5edee61 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 242 | goto out; |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 243 | |
Tejun Heo | a60bed2 | 2014-02-12 16:07:59 -0500 | [diff] [blame] | 244 | /* |
| 245 | * Grab @freezer->lock and freeze @task after verifying @task still |
| 246 | * belongs to @freezer and it's freezing. The former is for the |
| 247 | * case where we have raced against task migration and lost and |
| 248 | * @task is already in a different cgroup which may not be frozen. |
| 249 | * This isn't strictly necessary as freeze_task() is allowed to be |
| 250 | * called spuriously but let's do it anyway for, if nothing else, |
| 251 | * documentation. |
| 252 | */ |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 253 | spin_lock_irq(&freezer->lock); |
Tejun Heo | a60bed2 | 2014-02-12 16:07:59 -0500 | [diff] [blame] | 254 | if (freezer == task_freezer(task) && (freezer->state & CGROUP_FREEZING)) |
Tejun Heo | 839e340 | 2011-11-21 12:32:26 -0800 | [diff] [blame] | 255 | freeze_task(task); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 256 | spin_unlock_irq(&freezer->lock); |
Tejun Heo | 5edee61 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 257 | out: |
| 258 | rcu_read_unlock(); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 259 | } |
| 260 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 261 | /** |
| 262 | * update_if_frozen - update whether a cgroup finished freezing |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 263 | * @css: css of interest |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 264 | * |
| 265 | * Once FREEZING is initiated, transition to FROZEN is lazily updated by |
| 266 | * calling this function. If the current state is FREEZING but not FROZEN, |
| 267 | * this function checks whether all tasks of this cgroup and the descendant |
| 268 | * cgroups finished freezing and, if so, sets FROZEN. |
| 269 | * |
| 270 | * The caller is responsible for grabbing RCU read lock and calling |
| 271 | * update_if_frozen() on all descendants prior to invoking this function. |
Tejun Heo | b4d1831 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 272 | * |
| 273 | * Task states and freezer state might disagree while tasks are being |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 274 | * migrated into or out of @css, so we can't verify task states against |
Tejun Heo | ead5c47 | 2012-10-16 15:03:15 -0700 | [diff] [blame] | 275 | * @freezer state here. See freezer_attach() for details. |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 276 | */ |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 277 | static void update_if_frozen(struct cgroup_subsys_state *css) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 278 | { |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 279 | struct freezer *freezer = css_freezer(css); |
Tejun Heo | 492eb21 | 2013-08-08 20:11:25 -0400 | [diff] [blame] | 280 | struct cgroup_subsys_state *pos; |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 281 | struct css_task_iter it; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 282 | struct task_struct *task; |
Tejun Heo | b4d1831 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 283 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 284 | WARN_ON_ONCE(!rcu_read_lock_held()); |
| 285 | |
| 286 | spin_lock_irq(&freezer->lock); |
| 287 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 288 | if (!(freezer->state & CGROUP_FREEZING) || |
| 289 | (freezer->state & CGROUP_FROZEN)) |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 290 | goto out_unlock; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 291 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 292 | /* are all (live) children frozen? */ |
Tejun Heo | 492eb21 | 2013-08-08 20:11:25 -0400 | [diff] [blame] | 293 | css_for_each_child(pos, css) { |
| 294 | struct freezer *child = css_freezer(pos); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 295 | |
| 296 | if ((child->state & CGROUP_FREEZER_ONLINE) && |
| 297 | !(child->state & CGROUP_FROZEN)) |
| 298 | goto out_unlock; |
| 299 | } |
| 300 | |
| 301 | /* are all tasks frozen? */ |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 302 | css_task_iter_start(css, &it); |
Tejun Heo | b4d1831 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 303 | |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 304 | while ((task = css_task_iter_next(&it))) { |
Tejun Heo | 3c426d5 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 305 | if (freezing(task)) { |
Tejun Heo | 3c426d5 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 306 | /* |
| 307 | * freezer_should_skip() indicates that the task |
| 308 | * should be skipped when determining freezing |
| 309 | * completion. Consider it frozen in addition to |
| 310 | * the usual frozen condition. |
| 311 | */ |
Oleg Nesterov | 5d8f72b | 2012-10-26 19:46:06 +0200 | [diff] [blame] | 312 | if (!frozen(task) && !freezer_should_skip(task)) |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 313 | goto out_iter_end; |
Tejun Heo | 3c426d5 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 314 | } |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 315 | } |
| 316 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 317 | freezer->state |= CGROUP_FROZEN; |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 318 | out_iter_end: |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 319 | css_task_iter_end(&it); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 320 | out_unlock: |
| 321 | spin_unlock_irq(&freezer->lock); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 322 | } |
| 323 | |
Tejun Heo | 2da8ca8 | 2013-12-05 12:28:04 -0500 | [diff] [blame] | 324 | static int freezer_read(struct seq_file *m, void *v) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 325 | { |
Tejun Heo | 2da8ca8 | 2013-12-05 12:28:04 -0500 | [diff] [blame] | 326 | struct cgroup_subsys_state *css = seq_css(m), *pos; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 327 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 328 | rcu_read_lock(); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 329 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 330 | /* update states bottom-up */ |
Tejun Heo | 492eb21 | 2013-08-08 20:11:25 -0400 | [diff] [blame] | 331 | css_for_each_descendant_post(pos, css) |
| 332 | update_if_frozen(pos); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 333 | |
| 334 | rcu_read_unlock(); |
| 335 | |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 336 | seq_puts(m, freezer_state_strs(css_freezer(css)->state)); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 337 | seq_putc(m, '\n'); |
| 338 | return 0; |
| 339 | } |
| 340 | |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 341 | static void freeze_cgroup(struct freezer *freezer) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 342 | { |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 343 | struct css_task_iter it; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 344 | struct task_struct *task; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 345 | |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 346 | css_task_iter_start(&freezer->css, &it); |
| 347 | while ((task = css_task_iter_next(&it))) |
Tejun Heo | 51f246e | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 348 | freeze_task(task); |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 349 | css_task_iter_end(&it); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 350 | } |
| 351 | |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 352 | static void unfreeze_cgroup(struct freezer *freezer) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 353 | { |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 354 | struct css_task_iter it; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 355 | struct task_struct *task; |
| 356 | |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 357 | css_task_iter_start(&freezer->css, &it); |
| 358 | while ((task = css_task_iter_next(&it))) |
Tejun Heo | a5be2d0 | 2011-11-21 12:32:23 -0800 | [diff] [blame] | 359 | __thaw_task(task); |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 360 | css_task_iter_end(&it); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 361 | } |
| 362 | |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 363 | /** |
| 364 | * freezer_apply_state - apply state change to a single cgroup_freezer |
| 365 | * @freezer: freezer to apply state change to |
| 366 | * @freeze: whether to freeze or unfreeze |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 367 | * @state: CGROUP_FREEZING_* flag to set or clear |
| 368 | * |
| 369 | * Set or clear @state on @cgroup according to @freeze, and perform |
| 370 | * freezing or thawing as necessary. |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 371 | */ |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 372 | static void freezer_apply_state(struct freezer *freezer, bool freeze, |
| 373 | unsigned int state) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 374 | { |
Tejun Heo | ead5c47 | 2012-10-16 15:03:15 -0700 | [diff] [blame] | 375 | /* also synchronizes against task migration, see freezer_attach() */ |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 376 | lockdep_assert_held(&freezer->lock); |
Li Zefan | 51308ee | 2008-10-29 14:00:54 -0700 | [diff] [blame] | 377 | |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 378 | if (!(freezer->state & CGROUP_FREEZER_ONLINE)) |
| 379 | return; |
| 380 | |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 381 | if (freeze) { |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 382 | if (!(freezer->state & CGROUP_FREEZING)) |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 383 | atomic_inc(&system_freezing_cnt); |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 384 | freezer->state |= state; |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 385 | freeze_cgroup(freezer); |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 386 | } else { |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 387 | bool was_freezing = freezer->state & CGROUP_FREEZING; |
| 388 | |
| 389 | freezer->state &= ~state; |
| 390 | |
| 391 | if (!(freezer->state & CGROUP_FREEZING)) { |
| 392 | if (was_freezing) |
| 393 | atomic_dec(&system_freezing_cnt); |
| 394 | freezer->state &= ~CGROUP_FROZEN; |
| 395 | unfreeze_cgroup(freezer); |
| 396 | } |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 397 | } |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 398 | } |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 399 | |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 400 | /** |
| 401 | * freezer_change_state - change the freezing state of a cgroup_freezer |
| 402 | * @freezer: freezer of interest |
| 403 | * @freeze: whether to freeze or thaw |
| 404 | * |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 405 | * Freeze or thaw @freezer according to @freeze. The operations are |
| 406 | * recursive - all descendants of @freezer will be affected. |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 407 | */ |
| 408 | static void freezer_change_state(struct freezer *freezer, bool freeze) |
| 409 | { |
Tejun Heo | 492eb21 | 2013-08-08 20:11:25 -0400 | [diff] [blame] | 410 | struct cgroup_subsys_state *pos; |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 411 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 412 | /* |
| 413 | * Update all its descendants in pre-order traversal. Each |
| 414 | * descendant will try to inherit its parent's FREEZING state as |
| 415 | * CGROUP_FREEZING_PARENT. |
| 416 | */ |
| 417 | rcu_read_lock(); |
Tejun Heo | 492eb21 | 2013-08-08 20:11:25 -0400 | [diff] [blame] | 418 | css_for_each_descendant_pre(pos, &freezer->css) { |
| 419 | struct freezer *pos_f = css_freezer(pos); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 420 | struct freezer *parent = parent_freezer(pos_f); |
| 421 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 422 | spin_lock_irq(&pos_f->lock); |
Tejun Heo | bd8815a | 2013-08-08 20:11:27 -0400 | [diff] [blame] | 423 | |
| 424 | if (pos_f == freezer) { |
| 425 | freezer_apply_state(pos_f, freeze, |
| 426 | CGROUP_FREEZING_SELF); |
| 427 | } else { |
| 428 | /* |
| 429 | * Our update to @parent->state is already visible |
| 430 | * which is all we need. No need to lock @parent. |
| 431 | * For more info on synchronization, see |
| 432 | * freezer_post_create(). |
| 433 | */ |
| 434 | freezer_apply_state(pos_f, |
| 435 | parent->state & CGROUP_FREEZING, |
| 436 | CGROUP_FREEZING_PARENT); |
| 437 | } |
| 438 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 439 | spin_unlock_irq(&pos_f->lock); |
| 440 | } |
| 441 | rcu_read_unlock(); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 442 | } |
| 443 | |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 444 | static int freezer_write(struct cgroup_subsys_state *css, struct cftype *cft, |
Tejun Heo | 4d3bb51 | 2014-03-19 10:23:54 -0400 | [diff] [blame] | 445 | char *buffer) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 446 | { |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 447 | bool freeze; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 448 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 449 | if (strcmp(buffer, freezer_state_strs(0)) == 0) |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 450 | freeze = false; |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 451 | else if (strcmp(buffer, freezer_state_strs(CGROUP_FROZEN)) == 0) |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 452 | freeze = true; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 453 | else |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 454 | return -EINVAL; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 455 | |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 456 | freezer_change_state(css_freezer(css), freeze); |
Tejun Heo | 51f246e | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 457 | return 0; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 458 | } |
| 459 | |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 460 | static u64 freezer_self_freezing_read(struct cgroup_subsys_state *css, |
| 461 | struct cftype *cft) |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 462 | { |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 463 | struct freezer *freezer = css_freezer(css); |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 464 | |
| 465 | return (bool)(freezer->state & CGROUP_FREEZING_SELF); |
| 466 | } |
| 467 | |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 468 | static u64 freezer_parent_freezing_read(struct cgroup_subsys_state *css, |
| 469 | struct cftype *cft) |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 470 | { |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 471 | struct freezer *freezer = css_freezer(css); |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 472 | |
| 473 | return (bool)(freezer->state & CGROUP_FREEZING_PARENT); |
| 474 | } |
| 475 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 476 | static struct cftype files[] = { |
| 477 | { |
| 478 | .name = "state", |
Tejun Heo | 4baf6e3 | 2012-04-01 12:09:55 -0700 | [diff] [blame] | 479 | .flags = CFTYPE_NOT_ON_ROOT, |
Tejun Heo | 2da8ca8 | 2013-12-05 12:28:04 -0500 | [diff] [blame] | 480 | .seq_show = freezer_read, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 481 | .write_string = freezer_write, |
| 482 | }, |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 483 | { |
| 484 | .name = "self_freezing", |
| 485 | .flags = CFTYPE_NOT_ON_ROOT, |
| 486 | .read_u64 = freezer_self_freezing_read, |
| 487 | }, |
| 488 | { |
| 489 | .name = "parent_freezing", |
| 490 | .flags = CFTYPE_NOT_ON_ROOT, |
| 491 | .read_u64 = freezer_parent_freezing_read, |
| 492 | }, |
Tejun Heo | 4baf6e3 | 2012-04-01 12:09:55 -0700 | [diff] [blame] | 493 | { } /* terminate */ |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 494 | }; |
| 495 | |
Tejun Heo | 073219e | 2014-02-08 10:36:58 -0500 | [diff] [blame] | 496 | struct cgroup_subsys freezer_cgrp_subsys = { |
Tejun Heo | 92fb974 | 2012-11-19 08:13:38 -0800 | [diff] [blame] | 497 | .css_alloc = freezer_css_alloc, |
| 498 | .css_online = freezer_css_online, |
| 499 | .css_offline = freezer_css_offline, |
| 500 | .css_free = freezer_css_free, |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 501 | .attach = freezer_attach, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 502 | .fork = freezer_fork, |
Tejun Heo | 4baf6e3 | 2012-04-01 12:09:55 -0700 | [diff] [blame] | 503 | .base_cftypes = files, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 504 | }; |