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/wakelock.h>
  20
  21 /*
  22  * Timeout for stopping processes
  23  */
  24 #define TIMEOUT (20 * HZ)
  25
  26 static inline int freezeable(struct task_struct * p)
  27 {
  28         if ((p == current) ||
  29             (p->flags & PF_NOFREEZE) ||
  30             (p->exit_state != 0))
  31                 return 0;
  32         return 1;
  33 }
  34
  35 static int try_to_freeze_tasks(bool sig_only)
  36 {
  37         struct task_struct *g, *p;
  38         unsigned long end_time;
  39         unsigned int todo;
  40         bool wq_busy = false;
  41         struct timeval start, end;
  42         u64 elapsed_csecs64;
  43         unsigned int elapsed_csecs;
  44         unsigned int wakeup = 0;
  45
  46         do_gettimeofday(&start);
  47
  48         end_time = jiffies + TIMEOUT;
  49
  50         if (!sig_only)
  51                 freeze_workqueues_begin();
  52
  53         while (true) {
  54                 todo = 0;
  55                 read_lock(&tasklist_lock);
  56                 do_each_thread(g, p) {
  57                         if (frozen(p) || !freezeable(p))
  58                                 continue;
  59
  60                         if (!freeze_task(p, sig_only))
  61                                 continue;
  62
  63                         /*
  64                          * Now that we've done set_freeze_flag, don't
  65                          * perturb a task in TASK_STOPPED or TASK_TRACED.
  66                          * It is "frozen enough".  If the task does wake
  67                          * up, it will immediately call try_to_freeze.
  68                          */
  69                         if (!task_is_stopped_or_traced(p) &&
  70                             !freezer_should_skip(p))
  71                                 todo++;
  72                 } while_each_thread(g, p);
  73                 read_unlock(&tasklist_lock);
  74
  75                 if (!sig_only) {
  76                         wq_busy = freeze_workqueues_busy();
  77                         todo += wq_busy;
  78                 }
  79
  80                 if (todo && has_wake_lock(WAKE_LOCK_SUSPEND)) {
  81                         wakeup = 1;
  82                         break;
  83                 }
  84                 if (!todo || time_after(jiffies, end_time))
  85                         break;
  86
  87                 /*
  88                  * We need to retry, but first give the freezing tasks some
  89                  * time to enter the regrigerator.
  90                  */
  91                 msleep(10);
  92         }
  93
  94         do_gettimeofday(&end);
  95         elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
  96         do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
  97         elapsed_csecs = elapsed_csecs64;
  98
  99         if (todo) {
 100                 /* This does not unfreeze processes that are already frozen
 101                  * (we have slightly ugly calling convention in that respect,
 102                  * and caller must call thaw_processes() if something fails),
 103                  * but it cleans up leftover PF_FREEZE requests.
 104                  */
 105                 if(wakeup) {
 106                         printk("\n");
 107                         printk(KERN_ERR "Freezing of %s aborted\n",
 108                                         sig_only ? "user space " : "tasks ");
 109                 }
 110                 else {
 111                         printk("\n");
 112                         printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
 113                                "(%d tasks refusing to freeze, wq_busy=%d):\n",
 114                                elapsed_csecs / 100, elapsed_csecs % 100,
 115                                todo - wq_busy, wq_busy);
 116                 }
 117                 thaw_workqueues();
 118
 119                 read_lock(&tasklist_lock);
 120                 do_each_thread(g, p) {
 121                         task_lock(p);
 122                         if (freezing(p) && !freezer_should_skip(p) &&
 123                                 elapsed_csecs > 100)
 124                                 sched_show_task(p);
 125                         cancel_freezing(p);
 126                         task_unlock(p);
 127                 } while_each_thread(g, p);
 128                 read_unlock(&tasklist_lock);
 129         } else {
 130                 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
 131                         elapsed_csecs % 100);
 132         }
 133
 134         return todo ? -EBUSY : 0;
 135 }
 136
 137 /**
 138  *      freeze_processes - tell processes to enter the refrigerator
 139  */
 140 int freeze_processes(void)
 141 {
 142         int error;
 143
 144         printk("Freezing user space processes ... ");
 145         error = try_to_freeze_tasks(true);
 146         if (error)
 147                 goto Exit;
 148         printk("done.\n");
 149
 150         printk("Freezing remaining freezable tasks ... ");
 151         error = try_to_freeze_tasks(false);
 152         if (error)
 153                 goto Exit;
 154         printk("done.");
 155
 156         oom_killer_disable();
 157  Exit:
 158         BUG_ON(in_atomic());
 159         printk("\n");
 160
 161         return error;
 162 }
 163
 164 static void thaw_tasks(bool nosig_only)
 165 {
 166         struct task_struct *g, *p;
 167
 168         read_lock(&tasklist_lock);
 169         do_each_thread(g, p) {
 170                 if (!freezeable(p))
 171                         continue;
 172
 173                 if (nosig_only && should_send_signal(p))
 174                         continue;
 175
 176                 if (cgroup_freezing_or_frozen(p))
 177                         continue;
 178
 179                 thaw_process(p);
 180         } while_each_thread(g, p);
 181         read_unlock(&tasklist_lock);
 182 }
 183
 184 void thaw_processes(void)
 185 {
 186         oom_killer_enable();
 187
 188         printk("Restarting tasks ... ");
 189         thaw_workqueues();
 190         thaw_tasks(true);
 191         thaw_tasks(false);
 192         schedule();
 193         printk("done.\n");
 194 }
 195