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