lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 1 | /* |
| 2 | * drivers/power/process.c - Functions for starting/stopping processes on |
| 3 | * suspend transitions. |
| 4 | * |
| 5 | * Originally from swsusp. |
| 6 | */ |
| 7 | |
| 8 | |
| 9 | #undef DEBUG |
| 10 | |
| 11 | #include <linux/interrupt.h> |
| 12 | #include <linux/oom.h> |
| 13 | #include <linux/suspend.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/syscalls.h> |
| 16 | #include <linux/freezer.h> |
| 17 | #include <linux/delay.h> |
| 18 | #include <linux/workqueue.h> |
| 19 | #include <linux/kmod.h> |
| 20 | |
| 21 | /* |
| 22 | * Timeout for stopping processes |
| 23 | */ |
| 24 | #define TIMEOUT (20 * HZ) |
| 25 | |
| 26 | static int try_to_freeze_tasks(bool user_only) |
| 27 | { |
| 28 | struct task_struct *g, *p; |
| 29 | unsigned long end_time; |
| 30 | unsigned int todo; |
| 31 | bool wq_busy = false; |
| 32 | struct timeval start, end; |
| 33 | u64 elapsed_csecs64; |
| 34 | unsigned int elapsed_csecs; |
| 35 | bool wakeup = false; |
| 36 | |
| 37 | do_gettimeofday(&start); |
| 38 | |
| 39 | end_time = jiffies + TIMEOUT; |
| 40 | |
| 41 | if (!user_only) |
| 42 | freeze_workqueues_begin(); |
| 43 | |
| 44 | while (true) { |
| 45 | todo = 0; |
| 46 | read_lock(&tasklist_lock); |
| 47 | do_each_thread(g, p) { |
| 48 | if (p == current || !freeze_task(p)) |
| 49 | continue; |
| 50 | |
| 51 | /* |
| 52 | * Now that we've done set_freeze_flag, don't |
| 53 | * perturb a task in TASK_STOPPED or TASK_TRACED. |
| 54 | * It is "frozen enough". If the task does wake |
| 55 | * up, it will immediately call try_to_freeze. |
| 56 | * |
| 57 | * Because freeze_task() goes through p's scheduler lock, it's |
| 58 | * guaranteed that TASK_STOPPED/TRACED -> TASK_RUNNING |
| 59 | * transition can't race with task state testing here. |
| 60 | */ |
| 61 | if (!task_is_stopped_or_traced(p) && |
| 62 | !freezer_should_skip(p)) |
| 63 | todo++; |
| 64 | } while_each_thread(g, p); |
| 65 | read_unlock(&tasklist_lock); |
| 66 | |
| 67 | if (!user_only) { |
| 68 | wq_busy = freeze_workqueues_busy(); |
| 69 | todo += wq_busy; |
| 70 | } |
| 71 | |
| 72 | if (!todo || time_after(jiffies, end_time)) |
| 73 | break; |
| 74 | |
| 75 | if (pm_wakeup_pending()) { |
| 76 | wakeup = true; |
| 77 | break; |
| 78 | } |
| 79 | |
| 80 | /* |
| 81 | * We need to retry, but first give the freezing tasks some |
| 82 | * time to enter the regrigerator. |
| 83 | */ |
| 84 | msleep(10); |
| 85 | } |
| 86 | |
| 87 | do_gettimeofday(&end); |
| 88 | elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start); |
| 89 | do_div(elapsed_csecs64, NSEC_PER_SEC / 100); |
| 90 | elapsed_csecs = elapsed_csecs64; |
| 91 | |
| 92 | if (todo) { |
| 93 | printk("\n"); |
| 94 | printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds " |
| 95 | "(%d tasks refusing to freeze, wq_busy=%d):\n", |
| 96 | wakeup ? "aborted" : "failed", |
| 97 | elapsed_csecs / 100, elapsed_csecs % 100, |
| 98 | todo - wq_busy, wq_busy); |
| 99 | |
| 100 | if (!wakeup) { |
| 101 | read_lock(&tasklist_lock); |
| 102 | do_each_thread(g, p) { |
| 103 | if (p != current && !freezer_should_skip(p) |
| 104 | && freezing(p) && !frozen(p)) |
| 105 | sched_show_task(p); |
| 106 | } while_each_thread(g, p); |
| 107 | read_unlock(&tasklist_lock); |
| 108 | } |
| 109 | } else { |
| 110 | printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100, |
| 111 | elapsed_csecs % 100); |
| 112 | } |
| 113 | |
| 114 | return todo ? -EBUSY : 0; |
| 115 | } |
| 116 | |
| 117 | /* |
| 118 | * Returns true if all freezable tasks (except for current) are frozen already |
| 119 | */ |
| 120 | static bool check_frozen_processes(void) |
| 121 | { |
| 122 | struct task_struct *g, *p; |
| 123 | bool ret = true; |
| 124 | |
| 125 | read_lock(&tasklist_lock); |
| 126 | for_each_process_thread(g, p) { |
| 127 | if (p != current && !freezer_should_skip(p) && |
| 128 | !frozen(p)) { |
| 129 | ret = false; |
| 130 | goto done; |
| 131 | } |
| 132 | } |
| 133 | done: |
| 134 | read_unlock(&tasklist_lock); |
| 135 | |
| 136 | return ret; |
| 137 | } |
| 138 | |
| 139 | /** |
| 140 | * freeze_processes - Signal user space processes to enter the refrigerator. |
| 141 | * |
| 142 | * On success, returns 0. On failure, -errno and system is fully thawed. |
| 143 | */ |
| 144 | int freeze_processes(void) |
| 145 | { |
| 146 | int error; |
| 147 | int oom_kills_saved; |
| 148 | |
| 149 | error = __usermodehelper_disable(UMH_FREEZING); |
| 150 | if (error) |
| 151 | return error; |
| 152 | |
| 153 | if (!pm_freezing) |
| 154 | atomic_inc(&system_freezing_cnt); |
| 155 | |
| 156 | printk("Freezing user space processes ... "); |
| 157 | pm_freezing = true; |
| 158 | oom_kills_saved = oom_kills_count(); |
| 159 | error = try_to_freeze_tasks(true); |
| 160 | if (!error) { |
| 161 | __usermodehelper_set_disable_depth(UMH_DISABLED); |
| 162 | oom_killer_disable(); |
| 163 | |
| 164 | /* |
| 165 | * There might have been an OOM kill while we were |
| 166 | * freezing tasks and the killed task might be still |
| 167 | * on the way out so we have to double check for race. |
| 168 | */ |
| 169 | if (oom_kills_count() != oom_kills_saved && |
| 170 | !check_frozen_processes()) { |
| 171 | __usermodehelper_set_disable_depth(UMH_ENABLED); |
| 172 | printk("OOM in progress."); |
| 173 | error = -EBUSY; |
| 174 | goto done; |
| 175 | } |
| 176 | printk("done."); |
| 177 | } |
| 178 | done: |
| 179 | printk("\n"); |
| 180 | BUG_ON(in_atomic()); |
| 181 | |
| 182 | if (error) |
| 183 | thaw_processes(); |
| 184 | return error; |
| 185 | } |
| 186 | |
| 187 | /** |
| 188 | * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator. |
| 189 | * |
| 190 | * On success, returns 0. On failure, -errno and only the kernel threads are |
| 191 | * thawed, so as to give a chance to the caller to do additional cleanups |
| 192 | * (if any) before thawing the userspace tasks. So, it is the responsibility |
| 193 | * of the caller to thaw the userspace tasks, when the time is right. |
| 194 | */ |
| 195 | int freeze_kernel_threads(void) |
| 196 | { |
| 197 | int error; |
| 198 | |
| 199 | printk("Freezing remaining freezable tasks ... "); |
| 200 | pm_nosig_freezing = true; |
| 201 | error = try_to_freeze_tasks(false); |
| 202 | if (!error) |
| 203 | printk("done."); |
| 204 | |
| 205 | printk("\n"); |
| 206 | BUG_ON(in_atomic()); |
| 207 | |
| 208 | if (error) |
| 209 | thaw_kernel_threads(); |
| 210 | return error; |
| 211 | } |
| 212 | |
| 213 | void thaw_processes(void) |
| 214 | { |
| 215 | struct task_struct *g, *p; |
| 216 | |
| 217 | if (pm_freezing) |
| 218 | atomic_dec(&system_freezing_cnt); |
| 219 | pm_freezing = false; |
| 220 | pm_nosig_freezing = false; |
| 221 | |
| 222 | oom_killer_enable(); |
| 223 | |
| 224 | printk("Restarting tasks ... "); |
| 225 | |
| 226 | __usermodehelper_set_disable_depth(UMH_FREEZING); |
| 227 | thaw_workqueues(); |
| 228 | |
| 229 | read_lock(&tasklist_lock); |
| 230 | do_each_thread(g, p) { |
| 231 | __thaw_task(p); |
| 232 | } while_each_thread(g, p); |
| 233 | read_unlock(&tasklist_lock); |
| 234 | |
| 235 | usermodehelper_enable(); |
| 236 | |
| 237 | schedule(); |
| 238 | printk("done.\n"); |
| 239 | } |
| 240 | |
| 241 | void thaw_kernel_threads(void) |
| 242 | { |
| 243 | struct task_struct *g, *p; |
| 244 | |
| 245 | pm_nosig_freezing = false; |
| 246 | printk("Restarting kernel threads ... "); |
| 247 | |
| 248 | thaw_workqueues(); |
| 249 | |
| 250 | read_lock(&tasklist_lock); |
| 251 | do_each_thread(g, p) { |
| 252 | if (p->flags & (PF_KTHREAD | PF_WQ_WORKER)) |
| 253 | __thaw_task(p); |
| 254 | } while_each_thread(g, p); |
| 255 | read_unlock(&tasklist_lock); |
| 256 | |
| 257 | schedule(); |
| 258 | printk("done.\n"); |
| 259 | } |