kernel/power/process.c

   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 #include <linux/wakeup_reason.h>
  21 /*
  22  * Timeout for stopping processes
  23  */
  24 unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
  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_msecs64;
  34         unsigned int elapsed_msecs;
  35         bool wakeup = false;
  36         int sleep_usecs = USEC_PER_MSEC;
  37         char suspend_abort[MAX_SUSPEND_ABORT_LEN];
  38
  39         do_gettimeofday(&start);
  40
  41         end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
  42
  43         if (!user_only)
  44                 freeze_workqueues_begin();
  45
  46         while (true) {
  47                 todo = 0;
  48                 read_lock(&tasklist_lock);
  49                 do_each_thread(g, p) {
  50                         if (p == current || !freeze_task(p))
  51                                 continue;
  52
  53                         if (!freezer_should_skip(p))
  54                                 todo++;
  55                 } while_each_thread(g, p);
  56                 read_unlock(&tasklist_lock);
  57
  58                 if (!user_only) {
  59                         wq_busy = freeze_workqueues_busy();
  60                         todo += wq_busy;
  61                 }
  62
  63                 if (!todo || time_after(jiffies, end_time))
  64                         break;
  65
  66                 if (pm_wakeup_pending()) {
  67                         pm_get_active_wakeup_sources(suspend_abort,
  68                                 MAX_SUSPEND_ABORT_LEN);
  69                         log_suspend_abort_reason(suspend_abort);
  70                         wakeup = true;
  71                         break;
  72                 }
  73
  74                 /*
  75                  * We need to retry, but first give the freezing tasks some
  76                  * time to enter the refrigerator.  Start with an initial
  77                  * 1 ms sleep followed by exponential backoff until 8 ms.
  78                  */
  79                 usleep_range(sleep_usecs / 2, sleep_usecs);
  80                 if (sleep_usecs < 8 * USEC_PER_MSEC)
  81                         sleep_usecs *= 2;
  82         }
  83
  84         do_gettimeofday(&end);
  85         elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
  86         do_div(elapsed_msecs64, NSEC_PER_MSEC);
  87         elapsed_msecs = elapsed_msecs64;
  88
  89         if (wakeup) {
  90                 printk("\n");
  91                 printk(KERN_ERR "Freezing of tasks aborted after %d.%03d seconds",
  92                        elapsed_msecs / 1000, elapsed_msecs % 1000);
  93         } else if (todo) {
  94                 printk("\n");
  95                 printk(KERN_ERR "Freezing of tasks failed after %d.%03d seconds"
  96                        " (%d tasks refusing to freeze, wq_busy=%d):\n",
  97                        elapsed_msecs / 1000, elapsed_msecs % 1000,
  98                        todo - wq_busy, wq_busy);
  99
 100                 read_lock(&tasklist_lock);
 101                 do_each_thread(g, p) {
 102                         if (p != current && !freezer_should_skip(p)
 103                             && freezing(p) && !frozen(p))
 104                                 sched_show_task(p);
 105                 } while_each_thread(g, p);
 106                 read_unlock(&tasklist_lock);
 107         } else {
 108                 printk("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
 109                         elapsed_msecs % 1000);
 110         }
 111
 112         return todo ? -EBUSY : 0;
 113 }
 114
 115 /*
 116  * Returns true if all freezable tasks (except for current) are frozen already
 117  */
 118 static bool check_frozen_processes(void)
 119 {
 120         struct task_struct *g, *p;
 121         bool ret = true;
 122
 123         read_lock(&tasklist_lock);
 124         for_each_process_thread(g, p) {
 125                 if (p != current && !freezer_should_skip(p) &&
 126                     !frozen(p)) {
 127                         ret = false;
 128                         goto done;
 129                 }
 130         }
 131 done:
 132         read_unlock(&tasklist_lock);
 133
 134         return ret;
 135 }
 136
 137 /**
 138  * freeze_processes - Signal user space processes to enter the refrigerator.
 139  *
 140  * On success, returns 0.  On failure, -errno and system is fully thawed.
 141  */
 142 int freeze_processes(void)
 143 {
 144         int error;
 145         int oom_kills_saved;
 146
 147         error = __usermodehelper_disable(UMH_FREEZING);
 148         if (error)
 149                 return error;
 150
 151         if (!pm_freezing)
 152                 atomic_inc(&system_freezing_cnt);
 153
 154         printk("Freezing user space processes ... ");
 155         pm_freezing = true;
 156         oom_kills_saved = oom_kills_count();
 157         error = try_to_freeze_tasks(true);
 158         if (!error) {
 159                 __usermodehelper_set_disable_depth(UMH_DISABLED);
 160                 oom_killer_disable();
 161
 162                 /*
 163                  * There might have been an OOM kill while we were
 164                  * freezing tasks and the killed task might be still
 165                  * on the way out so we have to double check for race.
 166                  */
 167                 if (oom_kills_count() != oom_kills_saved &&
 168                                 !check_frozen_processes()) {
 169                         __usermodehelper_set_disable_depth(UMH_ENABLED);
 170                         printk("OOM in progress.");
 171                         error = -EBUSY;
 172                         goto done;
 173                 }
 174                 printk("done.");
 175         }
 176 done:
 177         printk("\n");
 178         BUG_ON(in_atomic());
 179
 180         if (error)
 181                 thaw_processes();
 182         return error;
 183 }
 184
 185 /**
 186  * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
 187  *
 188  * On success, returns 0.  On failure, -errno and only the kernel threads are
 189  * thawed, so as to give a chance to the caller to do additional cleanups
 190  * (if any) before thawing the userspace tasks. So, it is the responsibility
 191  * of the caller to thaw the userspace tasks, when the time is right.
 192  */
 193 int freeze_kernel_threads(void)
 194 {
 195         int error;
 196
 197         printk("Freezing remaining freezable tasks ... ");
 198         pm_nosig_freezing = true;
 199         error = try_to_freeze_tasks(false);
 200         if (!error)
 201                 printk("done.");
 202
 203         printk("\n");
 204         BUG_ON(in_atomic());
 205
 206         if (error)
 207                 thaw_kernel_threads();
 208         return error;
 209 }
 210
 211 void thaw_processes(void)
 212 {
 213         struct task_struct *g, *p;
 214
 215         if (pm_freezing)
 216                 atomic_dec(&system_freezing_cnt);
 217         pm_freezing = false;
 218         pm_nosig_freezing = false;
 219
 220         oom_killer_enable();
 221
 222         printk("Restarting tasks ... ");
 223
 224         __usermodehelper_set_disable_depth(UMH_FREEZING);
 225         thaw_workqueues();
 226
 227         read_lock(&tasklist_lock);
 228         do_each_thread(g, p) {
 229                 __thaw_task(p);
 230         } while_each_thread(g, p);
 231         read_unlock(&tasklist_lock);
 232
 233         usermodehelper_enable();
 234
 235         schedule();
 236         printk("done.\n");
 237 }
 238
 239 void thaw_kernel_threads(void)
 240 {
 241         struct task_struct *g, *p;
 242
 243         pm_nosig_freezing = false;
 244         printk("Restarting kernel threads ... ");
 245
 246         thaw_workqueues();
 247
 248         read_lock(&tasklist_lock);
 249         do_each_thread(g, p) {
 250                 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
 251                         __thaw_task(p);
 252         } while_each_thread(g, p);
 253         read_unlock(&tasklist_lock);
 254
 255         schedule();
 256         printk("done.\n");
 257 }