Thomas Gleixner | 457c899 | 2019-05-19 13:08:55 +0100 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-only |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 2 | /* |
| 3 | * kernel/freezer.c - Function to freeze a process |
| 4 | * |
| 5 | * Originally from kernel/power/process.c |
| 6 | */ |
| 7 | |
| 8 | #include <linux/interrupt.h> |
| 9 | #include <linux/suspend.h> |
Paul Gortmaker | 9984de1 | 2011-05-23 14:51:41 -0400 | [diff] [blame] | 10 | #include <linux/export.h> |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 11 | #include <linux/syscalls.h> |
| 12 | #include <linux/freezer.h> |
Tejun Heo | 8a32c44 | 2011-11-21 12:32:23 -0800 | [diff] [blame] | 13 | #include <linux/kthread.h> |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 14 | |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 15 | /* total number of freezing conditions in effect */ |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 16 | DEFINE_STATIC_KEY_FALSE(freezer_active); |
| 17 | EXPORT_SYMBOL(freezer_active); |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 18 | |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 19 | /* |
| 20 | * indicate whether PM freezing is in effect, protected by |
Pingfan Liu | 55f2503 | 2018-07-31 16:51:32 +0800 | [diff] [blame] | 21 | * system_transition_mutex |
| 22 | */ |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 23 | bool pm_freezing; |
| 24 | bool pm_nosig_freezing; |
| 25 | |
Tejun Heo | 0c9af09 | 2011-11-21 12:32:24 -0800 | [diff] [blame] | 26 | /* protects freezing and frozen transitions */ |
| 27 | static DEFINE_SPINLOCK(freezer_lock); |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 28 | |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 29 | /** |
| 30 | * freezing_slow_path - slow path for testing whether a task needs to be frozen |
| 31 | * @p: task to be tested |
| 32 | * |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 33 | * This function is called by freezing() if freezer_active isn't zero |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 34 | * and tests whether @p needs to enter and stay in frozen state. Can be |
| 35 | * called under any context. The freezers are responsible for ensuring the |
| 36 | * target tasks see the updated state. |
| 37 | */ |
| 38 | bool freezing_slow_path(struct task_struct *p) |
| 39 | { |
Colin Cross | 2b44c4d | 2013-07-24 17:41:33 -0700 | [diff] [blame] | 40 | if (p->flags & (PF_NOFREEZE | PF_SUSPEND_TASK)) |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 41 | return false; |
| 42 | |
Michal Hocko | a34c80a | 2016-07-28 15:45:16 -0700 | [diff] [blame] | 43 | if (test_tsk_thread_flag(p, TIF_MEMDIE)) |
Cong Wang | 51fae6da | 2014-10-21 09:27:12 +0200 | [diff] [blame] | 44 | return false; |
| 45 | |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 46 | if (pm_nosig_freezing || cgroup_freezing(p)) |
| 47 | return true; |
| 48 | |
Tejun Heo | 34b087e | 2011-11-23 09:28:17 -0800 | [diff] [blame] | 49 | if (pm_freezing && !(p->flags & PF_KTHREAD)) |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 50 | return true; |
| 51 | |
| 52 | return false; |
| 53 | } |
| 54 | EXPORT_SYMBOL(freezing_slow_path); |
| 55 | |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 56 | bool frozen(struct task_struct *p) |
| 57 | { |
| 58 | return READ_ONCE(p->__state) & TASK_FROZEN; |
| 59 | } |
| 60 | |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 61 | /* Refrigerator is place where frozen processes are stored :-). */ |
Tejun Heo | 8a32c44 | 2011-11-21 12:32:23 -0800 | [diff] [blame] | 62 | bool __refrigerator(bool check_kthr_stop) |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 63 | { |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 64 | unsigned int state = get_current_state(); |
Tejun Heo | a0acae0 | 2011-11-21 12:32:22 -0800 | [diff] [blame] | 65 | bool was_frozen = false; |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 66 | |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 67 | pr_debug("%s entered refrigerator\n", current->comm); |
| 68 | |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 69 | WARN_ON_ONCE(state && !(state & TASK_NORMAL)); |
| 70 | |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 71 | for (;;) { |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 72 | bool freeze; |
| 73 | |
Elliot Berman | 8f0eed4 | 2023-09-08 15:49:16 -0700 | [diff] [blame] | 74 | raw_spin_lock_irq(¤t->pi_lock); |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 75 | set_current_state(TASK_FROZEN); |
Elliot Berman | 8f0eed4 | 2023-09-08 15:49:16 -0700 | [diff] [blame] | 76 | /* unstale saved_state so that __thaw_task() will wake us up */ |
| 77 | current->saved_state = TASK_RUNNING; |
| 78 | raw_spin_unlock_irq(¤t->pi_lock); |
Tejun Heo | 5ece3ea | 2011-11-21 12:32:26 -0800 | [diff] [blame] | 79 | |
| 80 | spin_lock_irq(&freezer_lock); |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 81 | freeze = freezing(current) && !(check_kthr_stop && kthread_should_stop()); |
Tejun Heo | 5ece3ea | 2011-11-21 12:32:26 -0800 | [diff] [blame] | 82 | spin_unlock_irq(&freezer_lock); |
| 83 | |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 84 | if (!freeze) |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 85 | break; |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 86 | |
Tejun Heo | a0acae0 | 2011-11-21 12:32:22 -0800 | [diff] [blame] | 87 | was_frozen = true; |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 88 | schedule(); |
| 89 | } |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 90 | __set_current_state(TASK_RUNNING); |
Thomas Gleixner | 6301cb9 | 2009-07-17 14:15:47 +0200 | [diff] [blame] | 91 | |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 92 | pr_debug("%s left refrigerator\n", current->comm); |
Tejun Heo | 50fb4f7f | 2011-11-21 12:32:22 -0800 | [diff] [blame] | 93 | |
Tejun Heo | a0acae0 | 2011-11-21 12:32:22 -0800 | [diff] [blame] | 94 | return was_frozen; |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 95 | } |
Tejun Heo | a0acae0 | 2011-11-21 12:32:22 -0800 | [diff] [blame] | 96 | EXPORT_SYMBOL(__refrigerator); |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 97 | |
| 98 | static void fake_signal_wake_up(struct task_struct *p) |
| 99 | { |
| 100 | unsigned long flags; |
| 101 | |
Tejun Heo | 37ad8ac | 2011-11-21 12:32:26 -0800 | [diff] [blame] | 102 | if (lock_task_sighand(p, &flags)) { |
| 103 | signal_wake_up(p, 0); |
| 104 | unlock_task_sighand(p, &flags); |
| 105 | } |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 106 | } |
| 107 | |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 108 | static int __set_task_frozen(struct task_struct *p, void *arg) |
| 109 | { |
| 110 | unsigned int state = READ_ONCE(p->__state); |
| 111 | |
| 112 | if (p->on_rq) |
| 113 | return 0; |
| 114 | |
| 115 | if (p != current && task_curr(p)) |
| 116 | return 0; |
| 117 | |
| 118 | if (!(state & (TASK_FREEZABLE | __TASK_STOPPED | __TASK_TRACED))) |
| 119 | return 0; |
| 120 | |
| 121 | /* |
| 122 | * Only TASK_NORMAL can be augmented with TASK_FREEZABLE, since they |
| 123 | * can suffer spurious wakeups. |
| 124 | */ |
| 125 | if (state & TASK_FREEZABLE) |
| 126 | WARN_ON_ONCE(!(state & TASK_NORMAL)); |
| 127 | |
| 128 | #ifdef CONFIG_LOCKDEP |
| 129 | /* |
| 130 | * It's dangerous to freeze with locks held; there be dragons there. |
| 131 | */ |
| 132 | if (!(state & __TASK_FREEZABLE_UNSAFE)) |
| 133 | WARN_ON_ONCE(debug_locks && p->lockdep_depth); |
| 134 | #endif |
| 135 | |
Elliot Berman | 8f0eed4 | 2023-09-08 15:49:16 -0700 | [diff] [blame] | 136 | p->saved_state = p->__state; |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 137 | WRITE_ONCE(p->__state, TASK_FROZEN); |
| 138 | return TASK_FROZEN; |
| 139 | } |
| 140 | |
| 141 | static bool __freeze_task(struct task_struct *p) |
| 142 | { |
| 143 | /* TASK_FREEZABLE|TASK_STOPPED|TASK_TRACED -> TASK_FROZEN */ |
| 144 | return task_call_func(p, __set_task_frozen, NULL); |
| 145 | } |
| 146 | |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 147 | /** |
Tejun Heo | 839e340 | 2011-11-21 12:32:26 -0800 | [diff] [blame] | 148 | * freeze_task - send a freeze request to given task |
| 149 | * @p: task to send the request to |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 150 | * |
Marcos Paulo de Souza | 37f08be | 2012-02-21 23:57:47 +0100 | [diff] [blame] | 151 | * If @p is freezing, the freeze request is sent either by sending a fake |
| 152 | * signal (if it's not a kernel thread) or waking it up (if it's a kernel |
| 153 | * thread). |
Tejun Heo | 839e340 | 2011-11-21 12:32:26 -0800 | [diff] [blame] | 154 | * |
| 155 | * RETURNS: |
| 156 | * %false, if @p is not freezing or already frozen; %true, otherwise |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 157 | */ |
Tejun Heo | 839e340 | 2011-11-21 12:32:26 -0800 | [diff] [blame] | 158 | bool freeze_task(struct task_struct *p) |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 159 | { |
Tejun Heo | 0c9af09 | 2011-11-21 12:32:24 -0800 | [diff] [blame] | 160 | unsigned long flags; |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 161 | |
Tejun Heo | 0c9af09 | 2011-11-21 12:32:24 -0800 | [diff] [blame] | 162 | spin_lock_irqsave(&freezer_lock, flags); |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 163 | if (!freezing(p) || frozen(p) || __freeze_task(p)) { |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 164 | spin_unlock_irqrestore(&freezer_lock, flags); |
| 165 | return false; |
| 166 | } |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 167 | |
Jens Axboe | d3dc04c | 2021-03-25 18:22:11 -0600 | [diff] [blame] | 168 | if (!(p->flags & PF_KTHREAD)) |
Tejun Heo | 8cfe400 | 2010-11-26 23:07:27 +0100 | [diff] [blame] | 169 | fake_signal_wake_up(p); |
Oleg Nesterov | 5d8f72b | 2012-10-26 19:46:06 +0200 | [diff] [blame] | 170 | else |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 171 | wake_up_state(p, TASK_NORMAL); |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 172 | |
Tejun Heo | 0c9af09 | 2011-11-21 12:32:24 -0800 | [diff] [blame] | 173 | spin_unlock_irqrestore(&freezer_lock, flags); |
Tejun Heo | a320122 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 174 | return true; |
Matt Helsley | 8174f15 | 2008-10-18 20:27:19 -0700 | [diff] [blame] | 175 | } |
| 176 | |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 177 | /* |
Elliot Berman | 8f0eed4 | 2023-09-08 15:49:16 -0700 | [diff] [blame] | 178 | * Restore the saved_state before the task entered freezer. For typical task |
| 179 | * in the __refrigerator(), saved_state == TASK_RUNNING so nothing happens |
| 180 | * here. For tasks which were TASK_NORMAL | TASK_FREEZABLE, their initial state |
| 181 | * is restored unless they got an expected wakeup (see ttwu_state_match()). |
| 182 | * Returns 1 if the task state was restored. |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 183 | */ |
Elliot Berman | 8f0eed4 | 2023-09-08 15:49:16 -0700 | [diff] [blame] | 184 | static int __restore_freezer_state(struct task_struct *p, void *arg) |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 185 | { |
Elliot Berman | 8f0eed4 | 2023-09-08 15:49:16 -0700 | [diff] [blame] | 186 | unsigned int state = p->saved_state; |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 187 | |
Elliot Berman | 8f0eed4 | 2023-09-08 15:49:16 -0700 | [diff] [blame] | 188 | if (state != TASK_RUNNING) { |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 189 | WRITE_ONCE(p->__state, state); |
Elliot Berman | 8f0eed4 | 2023-09-08 15:49:16 -0700 | [diff] [blame] | 190 | return 1; |
| 191 | } |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 192 | |
Elliot Berman | 8f0eed4 | 2023-09-08 15:49:16 -0700 | [diff] [blame] | 193 | return 0; |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 194 | } |
| 195 | |
Tejun Heo | a5be2d0 | 2011-11-21 12:32:23 -0800 | [diff] [blame] | 196 | void __thaw_task(struct task_struct *p) |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 197 | { |
Elliot Berman | 8f0eed4 | 2023-09-08 15:49:16 -0700 | [diff] [blame] | 198 | unsigned long flags; |
Tejun Heo | a5be2d0 | 2011-11-21 12:32:23 -0800 | [diff] [blame] | 199 | |
Tejun Heo | 0c9af09 | 2011-11-21 12:32:24 -0800 | [diff] [blame] | 200 | spin_lock_irqsave(&freezer_lock, flags); |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 201 | if (WARN_ON_ONCE(freezing(p))) |
| 202 | goto unlock; |
| 203 | |
Elliot Berman | 8f0eed4 | 2023-09-08 15:49:16 -0700 | [diff] [blame] | 204 | if (task_call_func(p, __restore_freezer_state, NULL)) |
| 205 | goto unlock; |
Peter Zijlstra | f5d39b0 | 2022-08-22 13:18:22 +0200 | [diff] [blame] | 206 | |
| 207 | wake_up_state(p, TASK_FROZEN); |
| 208 | unlock: |
Tejun Heo | 0c9af09 | 2011-11-21 12:32:24 -0800 | [diff] [blame] | 209 | spin_unlock_irqrestore(&freezer_lock, flags); |
Matt Helsley | dc52ddc | 2008-10-18 20:27:21 -0700 | [diff] [blame] | 210 | } |
Tejun Heo | 96ee6d8 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 211 | |
| 212 | /** |
Tejun Heo | 34b087e | 2011-11-23 09:28:17 -0800 | [diff] [blame] | 213 | * set_freezable - make %current freezable |
Tejun Heo | 96ee6d8 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 214 | * |
| 215 | * Mark %current freezable and enter refrigerator if necessary. |
| 216 | */ |
Tejun Heo | 34b087e | 2011-11-23 09:28:17 -0800 | [diff] [blame] | 217 | bool set_freezable(void) |
Tejun Heo | 96ee6d8 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 218 | { |
| 219 | might_sleep(); |
| 220 | |
| 221 | /* |
| 222 | * Modify flags while holding freezer_lock. This ensures the |
| 223 | * freezer notices that we aren't frozen yet or the freezing |
| 224 | * condition is visible to try_to_freeze() below. |
| 225 | */ |
| 226 | spin_lock_irq(&freezer_lock); |
| 227 | current->flags &= ~PF_NOFREEZE; |
Tejun Heo | 96ee6d8 | 2011-11-21 12:32:25 -0800 | [diff] [blame] | 228 | spin_unlock_irq(&freezer_lock); |
| 229 | |
| 230 | return try_to_freeze(); |
| 231 | } |
Tejun Heo | 34b087e | 2011-11-23 09:28:17 -0800 | [diff] [blame] | 232 | EXPORT_SYMBOL(set_freezable); |