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 static void cancel_freezing(struct task_struct *p) 70 { 71 unsigned long flags; 72 73 if (freezing(p)) { 74 pr_debug(" clean up: %s\n", p->comm); 75 do_not_freeze(p); 76 spin_lock_irqsave(&p->sighand->siglock, flags); 77 recalc_sigpending_tsk(p); 78 spin_unlock_irqrestore(&p->sighand->siglock, flags); 79 } 80 } 81 82 /* 0 = success, else # of processes that we failed to stop */ 83 int freeze_processes(void) 84 { 85 int todo, nr_user, user_frozen; 86 unsigned long start_time; 87 struct task_struct *g, *p; 88 89 printk( "Stopping tasks: " ); 90 start_time = jiffies; 91 user_frozen = 0; 92 do { 93 nr_user = todo = 0; 94 read_lock(&tasklist_lock); 95 do_each_thread(g, p) { 96 if (!freezeable(p)) 97 continue; 98 if (frozen(p)) 99 continue; 100 if (p->state == TASK_TRACED && frozen(p->parent)) { 101 cancel_freezing(p); 102 continue; 103 } 104 if (p->mm && !(p->flags & PF_BORROWED_MM)) { 105 /* The task is a user-space one. 106 * Freeze it unless there's a vfork completion 107 * pending 108 */ 109 if (!p->vfork_done) 110 freeze_process(p); 111 nr_user++; 112 } else { 113 /* Freeze only if the user space is frozen */ 114 if (user_frozen) 115 freeze_process(p); 116 todo++; 117 } 118 } while_each_thread(g, p); 119 read_unlock(&tasklist_lock); 120 todo += nr_user; 121 if (!user_frozen && !nr_user) { 122 sys_sync(); 123 start_time = jiffies; 124 } 125 user_frozen = !nr_user; 126 yield(); /* Yield is okay here */ 127 if (todo && time_after(jiffies, start_time + TIMEOUT)) 128 break; 129 } while(todo); 130 131 /* This does not unfreeze processes that are already frozen 132 * (we have slightly ugly calling convention in that respect, 133 * and caller must call thaw_processes() if something fails), 134 * but it cleans up leftover PF_FREEZE requests. 135 */ 136 if (todo) { 137 printk( "\n" ); 138 printk(KERN_ERR " stopping tasks timed out " 139 "after %d seconds (%d tasks remaining):\n", 140 TIMEOUT / HZ, todo); 141 read_lock(&tasklist_lock); 142 do_each_thread(g, p) { 143 if (freezeable(p) && !frozen(p)) 144 printk(KERN_ERR " %s\n", p->comm); 145 cancel_freezing(p); 146 } while_each_thread(g, p); 147 read_unlock(&tasklist_lock); 148 return todo; 149 } 150 151 printk( "|\n" ); 152 BUG_ON(in_atomic()); 153 return 0; 154 } 155 156 void thaw_processes(void) 157 { 158 struct task_struct *g, *p; 159 160 printk( "Restarting tasks..." ); 161 read_lock(&tasklist_lock); 162 do_each_thread(g, p) { 163 if (!freezeable(p)) 164 continue; 165 if (!thaw_process(p)) 166 printk(KERN_INFO " Strange, %s not stopped\n", p->comm ); 167 } while_each_thread(g, p); 168 169 read_unlock(&tasklist_lock); 170 schedule(); 171 printk( " done\n" ); 172 } 173 174 EXPORT_SYMBOL(refrigerator); 175