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> |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 24 | #include <linux/mutex.h> |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 25 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 26 | /* |
| 27 | * A cgroup is freezing if any FREEZING flags are set. FREEZING_SELF is |
| 28 | * set if "FROZEN" is written to freezer.state cgroupfs file, and cleared |
| 29 | * for "THAWED". FREEZING_PARENT is set if the parent freezer is FREEZING |
| 30 | * for whatever reason. IOW, a cgroup has FREEZING_PARENT set if one of |
| 31 | * its ancestors has FREEZING_SELF set. |
| 32 | */ |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 33 | enum freezer_state_flags { |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 34 | CGROUP_FREEZER_ONLINE = (1 << 0), /* freezer is fully online */ |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 35 | CGROUP_FREEZING_SELF = (1 << 1), /* this freezer is freezing */ |
| 36 | CGROUP_FREEZING_PARENT = (1 << 2), /* the parent freezer is freezing */ |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 37 | CGROUP_FROZEN = (1 << 3), /* this and its descendants frozen */ |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 38 | |
| 39 | /* mask for all FREEZING flags */ |
| 40 | CGROUP_FREEZING = CGROUP_FREEZING_SELF | CGROUP_FREEZING_PARENT, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 41 | }; |
| 42 | |
| 43 | struct freezer { |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 44 | struct cgroup_subsys_state css; |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 45 | unsigned int state; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 46 | }; |
| 47 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 48 | static DEFINE_MUTEX(freezer_mutex); |
| 49 | |
Tejun Heo | a7c6d55 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 50 | static inline struct freezer *css_freezer(struct cgroup_subsys_state *css) |
| 51 | { |
| 52 | return css ? container_of(css, struct freezer, css) : NULL; |
| 53 | } |
| 54 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 55 | static inline struct freezer *task_freezer(struct task_struct *task) |
| 56 | { |
Tejun Heo | 073219e | 2014-02-08 10:36:58 -0500 | [diff] [blame] | 57 | return css_freezer(task_css(task, freezer_cgrp_id)); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 58 | } |
| 59 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 60 | static struct freezer *parent_freezer(struct freezer *freezer) |
| 61 | { |
Tejun Heo | 5c9d535 | 2014-05-16 13:22:48 -0400 | [diff] [blame] | 62 | return css_freezer(freezer->css.parent); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 63 | } |
| 64 | |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 65 | bool cgroup_freezing(struct task_struct *task) |
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 | bool ret; |
Tomasz Buchert | d5de4dd | 2010-10-27 15:33:32 -0700 | [diff] [blame] | 68 | |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 69 | rcu_read_lock(); |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 70 | ret = task_freezer(task)->state & CGROUP_FREEZING; |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 71 | rcu_read_unlock(); |
| 72 | |
| 73 | return ret; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 74 | } |
| 75 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 76 | static const char *freezer_state_strs(unsigned int state) |
| 77 | { |
| 78 | if (state & CGROUP_FROZEN) |
| 79 | return "FROZEN"; |
| 80 | if (state & CGROUP_FREEZING) |
| 81 | return "FREEZING"; |
| 82 | return "THAWED"; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 83 | }; |
| 84 | |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 85 | static struct cgroup_subsys_state * |
| 86 | freezer_css_alloc(struct cgroup_subsys_state *parent_css) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 87 | { |
| 88 | struct freezer *freezer; |
| 89 | |
| 90 | freezer = kzalloc(sizeof(struct freezer), GFP_KERNEL); |
| 91 | if (!freezer) |
| 92 | return ERR_PTR(-ENOMEM); |
| 93 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 94 | return &freezer->css; |
| 95 | } |
| 96 | |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 97 | /** |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 98 | * freezer_css_online - commit creation of a freezer css |
| 99 | * @css: css being created |
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 | * We're committing to creation of @css. Mark it online and inherit |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 102 | * parent's freezing state while holding both parent's and our |
| 103 | * freezer->lock. |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 104 | */ |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 105 | static int freezer_css_online(struct cgroup_subsys_state *css) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 106 | { |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 107 | struct freezer *freezer = css_freezer(css); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 108 | struct freezer *parent = parent_freezer(freezer); |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 109 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 110 | mutex_lock(&freezer_mutex); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 111 | |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 112 | freezer->state |= CGROUP_FREEZER_ONLINE; |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 113 | |
| 114 | if (parent && (parent->state & CGROUP_FREEZING)) { |
| 115 | freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN; |
| 116 | atomic_inc(&system_freezing_cnt); |
| 117 | } |
| 118 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 119 | mutex_unlock(&freezer_mutex); |
Tejun Heo | b1929db | 2012-11-19 08:13:38 -0800 | [diff] [blame] | 120 | return 0; |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 121 | } |
| 122 | |
| 123 | /** |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 124 | * freezer_css_offline - initiate destruction of a freezer css |
| 125 | * @css: css being destroyed |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 126 | * |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 127 | * @css is going away. Mark it dead and decrement system_freezing_count if |
| 128 | * it was holding one. |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 129 | */ |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 130 | static void freezer_css_offline(struct cgroup_subsys_state *css) |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 131 | { |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 132 | struct freezer *freezer = css_freezer(css); |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 133 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 134 | mutex_lock(&freezer_mutex); |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 135 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 136 | if (freezer->state & CGROUP_FREEZING) |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 137 | atomic_dec(&system_freezing_cnt); |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 138 | |
| 139 | freezer->state = 0; |
| 140 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 141 | mutex_unlock(&freezer_mutex); |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 142 | } |
| 143 | |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 144 | static void freezer_css_free(struct cgroup_subsys_state *css) |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 145 | { |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 146 | kfree(css_freezer(css)); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 147 | } |
| 148 | |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 149 | /* |
Tejun Heo | ead5c47 | 2012-10-16 15:03:15 -0700 | [diff] [blame] | 150 | * Tasks can be migrated into a different freezer anytime regardless of its |
| 151 | * current state. freezer_attach() is responsible for making new tasks |
| 152 | * conform to the current state. |
| 153 | * |
| 154 | * Freezer state changes and task migration are synchronized via |
| 155 | * @freezer->lock. freezer_attach() makes the new tasks conform to the |
| 156 | * current state and all following state changes can see the new tasks. |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 157 | */ |
Tejun Heo | 1f7dd3e5 | 2015-12-03 10:18:21 -0500 | [diff] [blame] | 158 | static void freezer_attach(struct cgroup_taskset *tset) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 159 | { |
Tejun Heo | bb9d97b | 2011-12-12 18:12:21 -0800 | [diff] [blame] | 160 | struct task_struct *task; |
Tejun Heo | 1f7dd3e5 | 2015-12-03 10:18:21 -0500 | [diff] [blame] | 161 | struct cgroup_subsys_state *new_css; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 162 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 163 | mutex_lock(&freezer_mutex); |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 164 | |
Li Zefan | 80a6a2c | 2008-10-29 14:00:52 -0700 | [diff] [blame] | 165 | /* |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 166 | * Make the new tasks conform to the current state of @new_css. |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 167 | * For simplicity, when migrating any task to a FROZEN cgroup, we |
| 168 | * revert it to FREEZING and let update_if_frozen() determine the |
| 169 | * correct state later. |
| 170 | * |
Tejun Heo | eb95419 | 2013-08-08 20:11:23 -0400 | [diff] [blame] | 171 | * 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] | 172 | * current state before executing the following - !frozen tasks may |
| 173 | * 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] | 174 | */ |
Tejun Heo | 1f7dd3e5 | 2015-12-03 10:18:21 -0500 | [diff] [blame] | 175 | cgroup_taskset_for_each(task, new_css, tset) { |
Tejun Heo | 599c963 | 2015-12-03 10:18:21 -0500 | [diff] [blame] | 176 | struct freezer *freezer = css_freezer(new_css); |
| 177 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 178 | if (!(freezer->state & CGROUP_FREEZING)) { |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 179 | __thaw_task(task); |
| 180 | } else { |
| 181 | freeze_task(task); |
Tejun Heo | 599c963 | 2015-12-03 10:18:21 -0500 | [diff] [blame] | 182 | /* clear FROZEN and propagate upwards */ |
| 183 | while (freezer && (freezer->state & CGROUP_FROZEN)) { |
| 184 | freezer->state &= ~CGROUP_FROZEN; |
| 185 | freezer = parent_freezer(freezer); |
| 186 | } |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 187 | } |
| 188 | } |
Matt Helsley | 957a4ee | 2008-10-18 20:27:22 -0700 | [diff] [blame] | 189 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 190 | mutex_unlock(&freezer_mutex); |
Ben Blum | f780bdb | 2011-05-26 16:25:19 -0700 | [diff] [blame] | 191 | } |
| 192 | |
Tejun Heo | a60bed2 | 2014-02-12 16:07:59 -0500 | [diff] [blame] | 193 | /** |
| 194 | * freezer_fork - cgroup post fork callback |
| 195 | * @task: a task which has just been forked |
| 196 | * |
| 197 | * @task has just been created and should conform to the current state of |
| 198 | * the cgroup_freezer it belongs to. This function may race against |
| 199 | * freezer_attach(). Losing to freezer_attach() means that we don't have |
| 200 | * to do anything as freezer_attach() will put @task into the appropriate |
| 201 | * state. |
| 202 | */ |
Oleg Nesterov | b53202e | 2015-12-03 10:24:08 -0500 | [diff] [blame] | 203 | static void freezer_fork(struct task_struct *task) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 204 | { |
| 205 | struct freezer *freezer; |
| 206 | |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 207 | /* |
Tejun Heo | a60bed2 | 2014-02-12 16:07:59 -0500 | [diff] [blame] | 208 | * The root cgroup is non-freezable, so we can skip locking the |
| 209 | * freezer. This is safe regardless of race with task migration. |
| 210 | * If we didn't race or won, skipping is obviously the right thing |
| 211 | * to do. If we lost and root is the new cgroup, noop is still the |
| 212 | * right thing to do. |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 213 | */ |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 214 | if (task_css_is_root(task, freezer_cgrp_id)) |
| 215 | return; |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 216 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 217 | mutex_lock(&freezer_mutex); |
| 218 | rcu_read_lock(); |
| 219 | |
| 220 | freezer = task_freezer(task); |
| 221 | if (freezer->state & CGROUP_FREEZING) |
Tejun Heo | 839e340 | 2011-11-21 12:32:26 -0800 | [diff] [blame] | 222 | freeze_task(task); |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 223 | |
Tejun Heo | 5edee61 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 224 | rcu_read_unlock(); |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 225 | mutex_unlock(&freezer_mutex); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 226 | } |
| 227 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 228 | /** |
| 229 | * update_if_frozen - update whether a cgroup finished freezing |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 230 | * @css: css of interest |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 231 | * |
| 232 | * Once FREEZING is initiated, transition to FROZEN is lazily updated by |
| 233 | * calling this function. If the current state is FREEZING but not FROZEN, |
| 234 | * this function checks whether all tasks of this cgroup and the descendant |
| 235 | * cgroups finished freezing and, if so, sets FROZEN. |
| 236 | * |
| 237 | * The caller is responsible for grabbing RCU read lock and calling |
| 238 | * update_if_frozen() on all descendants prior to invoking this function. |
Tejun Heo | b4d1831 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 239 | * |
| 240 | * Task states and freezer state might disagree while tasks are being |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 241 | * 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] | 242 | * @freezer state here. See freezer_attach() for details. |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 243 | */ |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 244 | static void update_if_frozen(struct cgroup_subsys_state *css) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 245 | { |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 246 | struct freezer *freezer = css_freezer(css); |
Tejun Heo | 492eb21 | 2013-08-08 20:11:25 -0400 | [diff] [blame] | 247 | struct cgroup_subsys_state *pos; |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 248 | struct css_task_iter it; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 249 | struct task_struct *task; |
Tejun Heo | b4d1831 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 250 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 251 | lockdep_assert_held(&freezer_mutex); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 252 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 253 | if (!(freezer->state & CGROUP_FREEZING) || |
| 254 | (freezer->state & CGROUP_FROZEN)) |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 255 | return; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 256 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 257 | /* are all (live) children frozen? */ |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 258 | rcu_read_lock(); |
Tejun Heo | 492eb21 | 2013-08-08 20:11:25 -0400 | [diff] [blame] | 259 | css_for_each_child(pos, css) { |
| 260 | struct freezer *child = css_freezer(pos); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 261 | |
| 262 | if ((child->state & CGROUP_FREEZER_ONLINE) && |
Tejun Heo | 36e9d2e | 2014-05-13 11:28:30 -0400 | [diff] [blame] | 263 | !(child->state & CGROUP_FROZEN)) { |
| 264 | rcu_read_unlock(); |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 265 | return; |
Tejun Heo | 36e9d2e | 2014-05-13 11:28:30 -0400 | [diff] [blame] | 266 | } |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 267 | } |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 268 | rcu_read_unlock(); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 269 | |
| 270 | /* are all tasks frozen? */ |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 271 | css_task_iter_start(css, &it); |
Tejun Heo | b4d1831 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 272 | |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 273 | while ((task = css_task_iter_next(&it))) { |
Tejun Heo | 3c426d5 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 274 | if (freezing(task)) { |
Tejun Heo | 3c426d5 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 275 | /* |
| 276 | * freezer_should_skip() indicates that the task |
| 277 | * should be skipped when determining freezing |
| 278 | * completion. Consider it frozen in addition to |
| 279 | * the usual frozen condition. |
| 280 | */ |
Oleg Nesterov | 5d8f72b | 2012-10-26 19:46:06 +0200 | [diff] [blame] | 281 | if (!frozen(task) && !freezer_should_skip(task)) |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 282 | goto out_iter_end; |
Tejun Heo | 3c426d5 | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 283 | } |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 284 | } |
| 285 | |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 286 | freezer->state |= CGROUP_FROZEN; |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 287 | out_iter_end: |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 288 | css_task_iter_end(&it); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 289 | } |
| 290 | |
Tejun Heo | 2da8ca8 | 2013-12-05 12:28:04 -0500 | [diff] [blame] | 291 | static int freezer_read(struct seq_file *m, void *v) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 292 | { |
Tejun Heo | 2da8ca8 | 2013-12-05 12:28:04 -0500 | [diff] [blame] | 293 | struct cgroup_subsys_state *css = seq_css(m), *pos; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 294 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 295 | mutex_lock(&freezer_mutex); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 296 | rcu_read_lock(); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 297 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 298 | /* update states bottom-up */ |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 299 | css_for_each_descendant_post(pos, css) { |
Tejun Heo | ec903c0 | 2014-05-13 12:11:01 -0400 | [diff] [blame] | 300 | if (!css_tryget_online(pos)) |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 301 | continue; |
| 302 | rcu_read_unlock(); |
| 303 | |
Tejun Heo | 492eb21 | 2013-08-08 20:11:25 -0400 | [diff] [blame] | 304 | update_if_frozen(pos); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 305 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 306 | rcu_read_lock(); |
| 307 | css_put(pos); |
| 308 | } |
| 309 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 310 | rcu_read_unlock(); |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 311 | mutex_unlock(&freezer_mutex); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 312 | |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 313 | seq_puts(m, freezer_state_strs(css_freezer(css)->state)); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 314 | seq_putc(m, '\n'); |
| 315 | return 0; |
| 316 | } |
| 317 | |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 318 | static void freeze_cgroup(struct freezer *freezer) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 319 | { |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 320 | struct css_task_iter it; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 321 | struct task_struct *task; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 322 | |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 323 | css_task_iter_start(&freezer->css, &it); |
| 324 | while ((task = css_task_iter_next(&it))) |
Tejun Heo | 51f246e | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 325 | freeze_task(task); |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 326 | css_task_iter_end(&it); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 327 | } |
| 328 | |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 329 | static void unfreeze_cgroup(struct freezer *freezer) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 330 | { |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 331 | struct css_task_iter it; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 332 | struct task_struct *task; |
| 333 | |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 334 | css_task_iter_start(&freezer->css, &it); |
| 335 | while ((task = css_task_iter_next(&it))) |
Tejun Heo | a5be2d0 | 2011-11-21 12:32:23 -0800 | [diff] [blame] | 336 | __thaw_task(task); |
Tejun Heo | 72ec702 | 2013-08-08 20:11:26 -0400 | [diff] [blame] | 337 | css_task_iter_end(&it); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 338 | } |
| 339 | |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 340 | /** |
| 341 | * freezer_apply_state - apply state change to a single cgroup_freezer |
| 342 | * @freezer: freezer to apply state change to |
| 343 | * @freeze: whether to freeze or unfreeze |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 344 | * @state: CGROUP_FREEZING_* flag to set or clear |
| 345 | * |
| 346 | * Set or clear @state on @cgroup according to @freeze, and perform |
| 347 | * freezing or thawing as necessary. |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 348 | */ |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 349 | static void freezer_apply_state(struct freezer *freezer, bool freeze, |
| 350 | unsigned int state) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 351 | { |
Tejun Heo | ead5c47 | 2012-10-16 15:03:15 -0700 | [diff] [blame] | 352 | /* also synchronizes against task migration, see freezer_attach() */ |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 353 | lockdep_assert_held(&freezer_mutex); |
Li Zefan | 51308ee | 2008-10-29 14:00:54 -0700 | [diff] [blame] | 354 | |
Tejun Heo | 5300a9b | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 355 | if (!(freezer->state & CGROUP_FREEZER_ONLINE)) |
| 356 | return; |
| 357 | |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 358 | if (freeze) { |
Tejun Heo | d6a2fe1 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 359 | if (!(freezer->state & CGROUP_FREEZING)) |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 360 | atomic_inc(&system_freezing_cnt); |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 361 | freezer->state |= state; |
Tejun Heo | bcd66c8 | 2012-11-09 09:12:29 -0800 | [diff] [blame] | 362 | freeze_cgroup(freezer); |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 363 | } else { |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 364 | bool was_freezing = freezer->state & CGROUP_FREEZING; |
| 365 | |
| 366 | freezer->state &= ~state; |
| 367 | |
| 368 | if (!(freezer->state & CGROUP_FREEZING)) { |
| 369 | if (was_freezing) |
| 370 | atomic_dec(&system_freezing_cnt); |
| 371 | freezer->state &= ~CGROUP_FROZEN; |
| 372 | unfreeze_cgroup(freezer); |
| 373 | } |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 374 | } |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 375 | } |
Tejun Heo | 22b4e11 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 376 | |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 377 | /** |
| 378 | * freezer_change_state - change the freezing state of a cgroup_freezer |
| 379 | * @freezer: freezer of interest |
| 380 | * @freeze: whether to freeze or thaw |
| 381 | * |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 382 | * Freeze or thaw @freezer according to @freeze. The operations are |
| 383 | * recursive - all descendants of @freezer will be affected. |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 384 | */ |
| 385 | static void freezer_change_state(struct freezer *freezer, bool freeze) |
| 386 | { |
Tejun Heo | 492eb21 | 2013-08-08 20:11:25 -0400 | [diff] [blame] | 387 | struct cgroup_subsys_state *pos; |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 388 | |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 389 | /* |
| 390 | * Update all its descendants in pre-order traversal. Each |
| 391 | * descendant will try to inherit its parent's FREEZING state as |
| 392 | * CGROUP_FREEZING_PARENT. |
| 393 | */ |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 394 | mutex_lock(&freezer_mutex); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 395 | rcu_read_lock(); |
Tejun Heo | 492eb21 | 2013-08-08 20:11:25 -0400 | [diff] [blame] | 396 | css_for_each_descendant_pre(pos, &freezer->css) { |
| 397 | struct freezer *pos_f = css_freezer(pos); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 398 | struct freezer *parent = parent_freezer(pos_f); |
| 399 | |
Tejun Heo | ec903c0 | 2014-05-13 12:11:01 -0400 | [diff] [blame] | 400 | if (!css_tryget_online(pos)) |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 401 | continue; |
| 402 | rcu_read_unlock(); |
Tejun Heo | bd8815a | 2013-08-08 20:11:27 -0400 | [diff] [blame] | 403 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 404 | if (pos_f == freezer) |
Tejun Heo | bd8815a | 2013-08-08 20:11:27 -0400 | [diff] [blame] | 405 | freezer_apply_state(pos_f, freeze, |
| 406 | CGROUP_FREEZING_SELF); |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 407 | else |
Tejun Heo | bd8815a | 2013-08-08 20:11:27 -0400 | [diff] [blame] | 408 | freezer_apply_state(pos_f, |
| 409 | parent->state & CGROUP_FREEZING, |
| 410 | CGROUP_FREEZING_PARENT); |
Tejun Heo | bd8815a | 2013-08-08 20:11:27 -0400 | [diff] [blame] | 411 | |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 412 | rcu_read_lock(); |
| 413 | css_put(pos); |
Tejun Heo | ef9fe98 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 414 | } |
| 415 | rcu_read_unlock(); |
Tejun Heo | e5ced8e | 2014-05-07 21:31:17 -0400 | [diff] [blame] | 416 | mutex_unlock(&freezer_mutex); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 417 | } |
| 418 | |
Tejun Heo | 451af504 | 2014-05-13 12:16:21 -0400 | [diff] [blame] | 419 | static ssize_t freezer_write(struct kernfs_open_file *of, |
| 420 | char *buf, size_t nbytes, loff_t off) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 421 | { |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 422 | bool freeze; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 423 | |
Tejun Heo | 451af504 | 2014-05-13 12:16:21 -0400 | [diff] [blame] | 424 | buf = strstrip(buf); |
| 425 | |
| 426 | if (strcmp(buf, freezer_state_strs(0)) == 0) |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 427 | freeze = false; |
Tejun Heo | 451af504 | 2014-05-13 12:16:21 -0400 | [diff] [blame] | 428 | else if (strcmp(buf, freezer_state_strs(CGROUP_FROZEN)) == 0) |
Tejun Heo | 04a4ec3 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 429 | freeze = true; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 430 | else |
Li Zefan | 3b1b3f6 | 2008-11-12 13:26:50 -0800 | [diff] [blame] | 431 | return -EINVAL; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 432 | |
Tejun Heo | 451af504 | 2014-05-13 12:16:21 -0400 | [diff] [blame] | 433 | freezer_change_state(css_freezer(of_css(of)), freeze); |
| 434 | return nbytes; |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 435 | } |
| 436 | |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 437 | static u64 freezer_self_freezing_read(struct cgroup_subsys_state *css, |
| 438 | struct cftype *cft) |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 439 | { |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 440 | struct freezer *freezer = css_freezer(css); |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 441 | |
| 442 | return (bool)(freezer->state & CGROUP_FREEZING_SELF); |
| 443 | } |
| 444 | |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 445 | static u64 freezer_parent_freezing_read(struct cgroup_subsys_state *css, |
| 446 | struct cftype *cft) |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 447 | { |
Tejun Heo | 182446d | 2013-08-08 20:11:24 -0400 | [diff] [blame] | 448 | struct freezer *freezer = css_freezer(css); |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 449 | |
| 450 | return (bool)(freezer->state & CGROUP_FREEZING_PARENT); |
| 451 | } |
| 452 | |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 453 | static struct cftype files[] = { |
| 454 | { |
| 455 | .name = "state", |
Tejun Heo | 4baf6e3 | 2012-04-01 12:09:55 -0700 | [diff] [blame] | 456 | .flags = CFTYPE_NOT_ON_ROOT, |
Tejun Heo | 2da8ca8 | 2013-12-05 12:28:04 -0500 | [diff] [blame] | 457 | .seq_show = freezer_read, |
Tejun Heo | 451af504 | 2014-05-13 12:16:21 -0400 | [diff] [blame] | 458 | .write = freezer_write, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 459 | }, |
Tejun Heo | a225218 | 2012-11-09 09:12:30 -0800 | [diff] [blame] | 460 | { |
| 461 | .name = "self_freezing", |
| 462 | .flags = CFTYPE_NOT_ON_ROOT, |
| 463 | .read_u64 = freezer_self_freezing_read, |
| 464 | }, |
| 465 | { |
| 466 | .name = "parent_freezing", |
| 467 | .flags = CFTYPE_NOT_ON_ROOT, |
| 468 | .read_u64 = freezer_parent_freezing_read, |
| 469 | }, |
Tejun Heo | 4baf6e3 | 2012-04-01 12:09:55 -0700 | [diff] [blame] | 470 | { } /* terminate */ |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 471 | }; |
| 472 | |
Tejun Heo | 073219e | 2014-02-08 10:36:58 -0500 | [diff] [blame] | 473 | struct cgroup_subsys freezer_cgrp_subsys = { |
Tejun Heo | 92fb974 | 2012-11-19 08:13:38 -0800 | [diff] [blame] | 474 | .css_alloc = freezer_css_alloc, |
| 475 | .css_online = freezer_css_online, |
| 476 | .css_offline = freezer_css_offline, |
| 477 | .css_free = freezer_css_free, |
Tejun Heo | 8755ade | 2012-10-16 15:03:14 -0700 | [diff] [blame] | 478 | .attach = freezer_attach, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 479 | .fork = freezer_fork, |
Tejun Heo | 5577964 | 2014-07-15 11:05:09 -0400 | [diff] [blame] | 480 | .legacy_cftypes = files, |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 481 | }; |