Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6
[linux-2.6] / 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/suspend.h>
13 #include <linux/module.h>
14 #include <linux/syscalls.h>
15 #include <linux/freezer.h>
16
17 /* 
18  * Timeout for stopping processes
19  */
20 #define TIMEOUT (20 * HZ)
21
22 #define FREEZER_KERNEL_THREADS 0
23 #define FREEZER_USER_SPACE 1
24
25 static inline int freezeable(struct task_struct * p)
26 {
27         if ((p == current) ||
28             (p->flags & PF_NOFREEZE) ||
29             (p->exit_state != 0))
30                 return 0;
31         return 1;
32 }
33
34 /*
35  * freezing is complete, mark current process as frozen
36  */
37 static inline void frozen_process(void)
38 {
39         if (!unlikely(current->flags & PF_NOFREEZE)) {
40                 current->flags |= PF_FROZEN;
41                 wmb();
42         }
43         clear_freeze_flag(current);
44 }
45
46 /* Refrigerator is place where frozen processes are stored :-). */
47 void refrigerator(void)
48 {
49         /* Hmm, should we be allowed to suspend when there are realtime
50            processes around? */
51         long save;
52
53         task_lock(current);
54         if (freezing(current)) {
55                 frozen_process();
56                 task_unlock(current);
57         } else {
58                 task_unlock(current);
59                 return;
60         }
61         save = current->state;
62         pr_debug("%s entered refrigerator\n", current->comm);
63
64         spin_lock_irq(&current->sighand->siglock);
65         recalc_sigpending(); /* We sent fake signal, clean it up */
66         spin_unlock_irq(&current->sighand->siglock);
67
68         for (;;) {
69                 set_current_state(TASK_UNINTERRUPTIBLE);
70                 if (!frozen(current))
71                         break;
72                 schedule();
73         }
74         pr_debug("%s left refrigerator\n", current->comm);
75         __set_current_state(save);
76 }
77
78 static void fake_signal_wake_up(struct task_struct *p)
79 {
80         unsigned long flags;
81
82         spin_lock_irqsave(&p->sighand->siglock, flags);
83         signal_wake_up(p, 0);
84         spin_unlock_irqrestore(&p->sighand->siglock, flags);
85 }
86
87 static int has_mm(struct task_struct *p)
88 {
89         return (p->mm && !(p->flags & PF_BORROWED_MM));
90 }
91
92 /**
93  *      freeze_task - send a freeze request to given task
94  *      @p: task to send the request to
95  *      @with_mm_only: if set, the request will only be sent if the task has its
96  *              own mm
97  *      Return value: 0, if @with_mm_only is set and the task has no mm of its
98  *              own or the task is frozen, 1, otherwise
99  *
100  *      The freeze request is sent by seting the tasks's TIF_FREEZE flag and
101  *      either sending a fake signal to it or waking it up, depending on whether
102  *      or not it has its own mm (ie. it is a user land task).  If @with_mm_only
103  *      is set and the task has no mm of its own (ie. it is a kernel thread),
104  *      its TIF_FREEZE flag should not be set.
105  *
106  *      The task_lock() is necessary to prevent races with exit_mm() or
107  *      use_mm()/unuse_mm() from occuring.
108  */
109 static int freeze_task(struct task_struct *p, int with_mm_only)
110 {
111         int ret = 1;
112
113         task_lock(p);
114         if (freezing(p)) {
115                 if (has_mm(p)) {
116                         if (!signal_pending(p))
117                                 fake_signal_wake_up(p);
118                 } else {
119                         if (with_mm_only)
120                                 ret = 0;
121                         else
122                                 wake_up_state(p, TASK_INTERRUPTIBLE);
123                 }
124         } else {
125                 rmb();
126                 if (frozen(p)) {
127                         ret = 0;
128                 } else {
129                         if (has_mm(p)) {
130                                 set_freeze_flag(p);
131                                 fake_signal_wake_up(p);
132                         } else {
133                                 if (with_mm_only) {
134                                         ret = 0;
135                                 } else {
136                                         set_freeze_flag(p);
137                                         wake_up_state(p, TASK_INTERRUPTIBLE);
138                                 }
139                         }
140                 }
141         }
142         task_unlock(p);
143         return ret;
144 }
145
146 static void cancel_freezing(struct task_struct *p)
147 {
148         unsigned long flags;
149
150         if (freezing(p)) {
151                 pr_debug("  clean up: %s\n", p->comm);
152                 clear_freeze_flag(p);
153                 spin_lock_irqsave(&p->sighand->siglock, flags);
154                 recalc_sigpending_and_wake(p);
155                 spin_unlock_irqrestore(&p->sighand->siglock, flags);
156         }
157 }
158
159 static int try_to_freeze_tasks(int freeze_user_space)
160 {
161         struct task_struct *g, *p;
162         unsigned long end_time;
163         unsigned int todo;
164         struct timeval start, end;
165         s64 elapsed_csecs64;
166         unsigned int elapsed_csecs;
167
168         do_gettimeofday(&start);
169
170         end_time = jiffies + TIMEOUT;
171         do {
172                 todo = 0;
173                 read_lock(&tasklist_lock);
174                 do_each_thread(g, p) {
175                         if (frozen(p) || !freezeable(p))
176                                 continue;
177
178                         if (!freeze_task(p, freeze_user_space))
179                                 continue;
180
181                         /*
182                          * Now that we've done set_freeze_flag, don't
183                          * perturb a task in TASK_STOPPED or TASK_TRACED.
184                          * It is "frozen enough".  If the task does wake
185                          * up, it will immediately call try_to_freeze.
186                          */
187                         if (!task_is_stopped_or_traced(p) &&
188                             !freezer_should_skip(p))
189                                 todo++;
190                 } while_each_thread(g, p);
191                 read_unlock(&tasklist_lock);
192                 yield();                        /* Yield is okay here */
193                 if (time_after(jiffies, end_time))
194                         break;
195         } while (todo);
196
197         do_gettimeofday(&end);
198         elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
199         do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
200         elapsed_csecs = elapsed_csecs64;
201
202         if (todo) {
203                 /* This does not unfreeze processes that are already frozen
204                  * (we have slightly ugly calling convention in that respect,
205                  * and caller must call thaw_processes() if something fails),
206                  * but it cleans up leftover PF_FREEZE requests.
207                  */
208                 printk("\n");
209                 printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
210                                 "(%d tasks refusing to freeze):\n",
211                                 elapsed_csecs / 100, elapsed_csecs % 100, todo);
212                 show_state();
213                 read_lock(&tasklist_lock);
214                 do_each_thread(g, p) {
215                         task_lock(p);
216                         if (freezing(p) && !freezer_should_skip(p))
217                                 printk(KERN_ERR " %s\n", p->comm);
218                         cancel_freezing(p);
219                         task_unlock(p);
220                 } while_each_thread(g, p);
221                 read_unlock(&tasklist_lock);
222         } else {
223                 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
224                         elapsed_csecs % 100);
225         }
226
227         return todo ? -EBUSY : 0;
228 }
229
230 /**
231  *      freeze_processes - tell processes to enter the refrigerator
232  */
233 int freeze_processes(void)
234 {
235         int error;
236
237         printk("Freezing user space processes ... ");
238         error = try_to_freeze_tasks(FREEZER_USER_SPACE);
239         if (error)
240                 goto Exit;
241         printk("done.\n");
242
243         printk("Freezing remaining freezable tasks ... ");
244         error = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
245         if (error)
246                 goto Exit;
247         printk("done.");
248  Exit:
249         BUG_ON(in_atomic());
250         printk("\n");
251         return error;
252 }
253
254 static void thaw_tasks(int thaw_user_space)
255 {
256         struct task_struct *g, *p;
257
258         read_lock(&tasklist_lock);
259         do_each_thread(g, p) {
260                 if (!freezeable(p))
261                         continue;
262
263                 if (!p->mm == thaw_user_space)
264                         continue;
265
266                 thaw_process(p);
267         } while_each_thread(g, p);
268         read_unlock(&tasklist_lock);
269 }
270
271 void thaw_processes(void)
272 {
273         printk("Restarting tasks ... ");
274         thaw_tasks(FREEZER_KERNEL_THREADS);
275         thaw_tasks(FREEZER_USER_SPACE);
276         schedule();
277         printk("done.\n");
278 }
279
280 EXPORT_SYMBOL(refrigerator);