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
  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_csecs64;
  34         unsigned int elapsed_csecs;
  35         bool wakeup = false;
  36
  37         do_gettimeofday(&start);
  38
  39         end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
  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                         if (!freezer_should_skip(p))
  52                                 todo++;
  53                 } while_each_thread(g, p);
  54                 read_unlock(&tasklist_lock);
  55
  56                 if (!user_only) {
  57                         wq_busy = freeze_workqueues_busy();
  58                         todo += wq_busy;
  59                 }
  60
  61                 if (!todo || time_after(jiffies, end_time))
  62                         break;
  63
  64                 if (pm_wakeup_pending()) {
  65                         wakeup = true;
  66                         break;
  67                 }
  68
  69                 /*
  70                  * We need to retry, but first give the freezing tasks some
  71                  * time to enter the refrigerator.
  72                  */
  73                 msleep(10);
  74         }
  75
  76         do_gettimeofday(&end);
  77         elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
  78         do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
  79         elapsed_csecs = elapsed_csecs64;
  80
  81         if (todo) {
  82                 printk("\n");
  83                 printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds "
  84                        "(%d tasks refusing to freeze, wq_busy=%d):\n",
  85                        wakeup ? "aborted" : "failed",
  86                        elapsed_csecs / 100, elapsed_csecs % 100,
  87                        todo - wq_busy, wq_busy);
  88
  89                 if (!wakeup) {
  90                         read_lock(&tasklist_lock);
  91                         do_each_thread(g, p) {
  92                                 if (p != current && !freezer_should_skip(p)
  93                                     && freezing(p) && !frozen(p))
  94                                         sched_show_task(p);
  95                         } while_each_thread(g, p);
  96                         read_unlock(&tasklist_lock);
  97                 }
  98         } else {
  99                 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
 100                         elapsed_csecs % 100);
 101         }
 102
 103         return todo ? -EBUSY : 0;
 104 }
 105
 106 /**
 107  * freeze_processes - Signal user space processes to enter the refrigerator.
 108  *
 109  * On success, returns 0.  On failure, -errno and system is fully thawed.
 110  */
 111 int freeze_processes(void)
 112 {
 113         int error;
 114
 115         error = __usermodehelper_disable(UMH_FREEZING);
 116         if (error)
 117                 return error;
 118
 119         if (!pm_freezing)
 120                 atomic_inc(&system_freezing_cnt);
 121
 122         printk("Freezing user space processes ... ");
 123         pm_freezing = true;
 124         error = try_to_freeze_tasks(true);
 125         if (!error) {
 126                 printk("done.");
 127                 __usermodehelper_set_disable_depth(UMH_DISABLED);
 128                 oom_killer_disable();
 129         }
 130         printk("\n");
 131         BUG_ON(in_atomic());
 132
 133         if (error)
 134                 thaw_processes();
 135         return error;
 136 }
 137
 138 /**
 139  * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
 140  *
 141  * On success, returns 0.  On failure, -errno and only the kernel threads are
 142  * thawed, so as to give a chance to the caller to do additional cleanups
 143  * (if any) before thawing the userspace tasks. So, it is the responsibility
 144  * of the caller to thaw the userspace tasks, when the time is right.
 145  */
 146 int freeze_kernel_threads(void)
 147 {
 148         int error;
 149
 150         printk("Freezing remaining freezable tasks ... ");
 151         pm_nosig_freezing = true;
 152         error = try_to_freeze_tasks(false);
 153         if (!error)
 154                 printk("done.");
 155
 156         printk("\n");
 157         BUG_ON(in_atomic());
 158
 159         if (error)
 160                 thaw_kernel_threads();
 161         return error;
 162 }
 163
 164 void thaw_processes(void)
 165 {
 166         struct task_struct *g, *p;
 167
 168         if (pm_freezing)
 169                 atomic_dec(&system_freezing_cnt);
 170         pm_freezing = false;
 171         pm_nosig_freezing = false;
 172
 173         oom_killer_enable();
 174
 175         printk("Restarting tasks ... ");
 176
 177         __usermodehelper_set_disable_depth(UMH_FREEZING);
 178         thaw_workqueues();
 179
 180         read_lock(&tasklist_lock);
 181         do_each_thread(g, p) {
 182                 __thaw_task(p);
 183         } while_each_thread(g, p);
 184         read_unlock(&tasklist_lock);
 185
 186         usermodehelper_enable();
 187
 188         schedule();
 189         printk("done.\n");
 190 }
 191
 192 void thaw_kernel_threads(void)
 193 {
 194         struct task_struct *g, *p;
 195
 196         pm_nosig_freezing = false;
 197         printk("Restarting kernel threads ... ");
 198
 199         thaw_workqueues();
 200
 201         read_lock(&tasklist_lock);
 202         do_each_thread(g, p) {
 203                 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
 204                         __thaw_task(p);
 205         } while_each_thread(g, p);
 206         read_unlock(&tasklist_lock);
 207
 208         schedule();
 209         printk("done.\n");
 210 }