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/smp_lock.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/suspend.h>
  14 #include <linux/module.h>
  15 #include <linux/syscalls.h>
  16 #include <linux/freezer.h>
  17
  18 /*
  19  * Timeout for stopping processes
  20  */
  21 #define TIMEOUT (20 * HZ)
  22
  23
  24 static inline int freezeable(struct task_struct * p)
  25 {
  26         if ((p == current) ||
  27             (p->flags & PF_NOFREEZE) ||
  28             (p->exit_state == EXIT_ZOMBIE) ||
  29             (p->exit_state == EXIT_DEAD) ||
  30             (p->state == TASK_STOPPED))
  31                 return 0;
  32         return 1;
  33 }
  34
  35 /* Refrigerator is place where frozen processes are stored :-). */
  36 void refrigerator(void)
  37 {
  38         /* Hmm, should we be allowed to suspend when there are realtime
  39            processes around? */
  40         long save;
  41         save = current->state;
  42         pr_debug("%s entered refrigerator\n", current->comm);
  43         printk("=");
  44
  45         frozen_process(current);
  46         spin_lock_irq(&current->sighand->siglock);
  47         recalc_sigpending(); /* We sent fake signal, clean it up */
  48         spin_unlock_irq(&current->sighand->siglock);
  49
  50         while (frozen(current)) {
  51                 current->state = TASK_UNINTERRUPTIBLE;
  52                 schedule();
  53         }
  54         pr_debug("%s left refrigerator\n", current->comm);
  55         current->state = save;
  56 }
  57
  58 static inline void freeze_process(struct task_struct *p)
  59 {
  60         unsigned long flags;
  61
  62         if (!freezing(p)) {
  63                 freeze(p);
  64                 spin_lock_irqsave(&p->sighand->siglock, flags);
  65                 signal_wake_up(p, 0);
  66                 spin_unlock_irqrestore(&p->sighand->siglock, flags);
  67         }
  68 }
  69
  70 static void cancel_freezing(struct task_struct *p)
  71 {
  72         unsigned long flags;
  73
  74         if (freezing(p)) {
  75                 pr_debug("  clean up: %s\n", p->comm);
  76                 do_not_freeze(p);
  77                 spin_lock_irqsave(&p->sighand->siglock, flags);
  78                 recalc_sigpending_tsk(p);
  79                 spin_unlock_irqrestore(&p->sighand->siglock, flags);
  80         }
  81 }
  82
  83 /* 0 = success, else # of processes that we failed to stop */
  84 int freeze_processes(void)
  85 {
  86         int todo, nr_user, user_frozen;
  87         unsigned long start_time;
  88         struct task_struct *g, *p;
  89
  90         printk( "Stopping tasks: " );
  91         start_time = jiffies;
  92         user_frozen = 0;
  93         do {
  94                 nr_user = todo = 0;
  95                 read_lock(&tasklist_lock);
  96                 do_each_thread(g, p) {
  97                         if (!freezeable(p))
  98                                 continue;
  99                         if (frozen(p))
 100                                 continue;
 101                         if (p->state == TASK_TRACED && frozen(p->parent)) {
 102                                 cancel_freezing(p);
 103                                 continue;
 104                         }
 105                         if (p->mm && !(p->flags & PF_BORROWED_MM)) {
 106                                 /* The task is a user-space one.
 107                                  * Freeze it unless there's a vfork completion
 108                                  * pending
 109                                  */
 110                                 if (!p->vfork_done)
 111                                         freeze_process(p);
 112                                 nr_user++;
 113                         } else {
 114                                 /* Freeze only if the user space is frozen */
 115                                 if (user_frozen)
 116                                         freeze_process(p);
 117                                 todo++;
 118                         }
 119                 } while_each_thread(g, p);
 120                 read_unlock(&tasklist_lock);
 121                 todo += nr_user;
 122                 if (!user_frozen && !nr_user) {
 123                         sys_sync();
 124                         start_time = jiffies;
 125                 }
 126                 user_frozen = !nr_user;
 127                 yield();                        /* Yield is okay here */
 128                 if (todo && time_after(jiffies, start_time + TIMEOUT))
 129                         break;
 130         } while(todo);
 131
 132         /* This does not unfreeze processes that are already frozen
 133          * (we have slightly ugly calling convention in that respect,
 134          * and caller must call thaw_processes() if something fails),
 135          * but it cleans up leftover PF_FREEZE requests.
 136          */
 137         if (todo) {
 138                 printk( "\n" );
 139                 printk(KERN_ERR " stopping tasks timed out "
 140                         "after %d seconds (%d tasks remaining):\n",
 141                         TIMEOUT / HZ, todo);
 142                 read_lock(&tasklist_lock);
 143                 do_each_thread(g, p) {
 144                         if (freezeable(p) && !frozen(p))
 145                                 printk(KERN_ERR "  %s\n", p->comm);
 146                         cancel_freezing(p);
 147                 } while_each_thread(g, p);
 148                 read_unlock(&tasklist_lock);
 149                 return todo;
 150         }
 151
 152         printk( "|\n" );
 153         BUG_ON(in_atomic());
 154         return 0;
 155 }
 156
 157 void thaw_processes(void)
 158 {
 159         struct task_struct *g, *p;
 160
 161         printk( "Restarting tasks..." );
 162         read_lock(&tasklist_lock);
 163         do_each_thread(g, p) {
 164                 if (!freezeable(p))
 165                         continue;
 166                 if (!thaw_process(p))
 167                         printk(KERN_INFO " Strange, %s not stopped\n", p->comm );
 168         } while_each_thread(g, p);
 169
 170         read_unlock(&tasklist_lock);
 171         schedule();
 172         printk( " done\n" );
 173 }
 174
 175 EXPORT_SYMBOL(refrigerator);