kobject: convert s390 hypervisor to use kobject_create
[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, int resume)
79 {
80         unsigned long flags;
81
82         spin_lock_irqsave(&p->sighand->siglock, flags);
83         signal_wake_up(p, resume);
84         spin_unlock_irqrestore(&p->sighand->siglock, flags);
85 }
86
87 static void send_fake_signal(struct task_struct *p)
88 {
89         if (p->state == TASK_STOPPED)
90                 force_sig_specific(SIGSTOP, p);
91         fake_signal_wake_up(p, p->state == TASK_STOPPED);
92 }
93
94 static int has_mm(struct task_struct *p)
95 {
96         return (p->mm && !(p->flags & PF_BORROWED_MM));
97 }
98
99 /**
100  *      freeze_task - send a freeze request to given task
101  *      @p: task to send the request to
102  *      @with_mm_only: if set, the request will only be sent if the task has its
103  *              own mm
104  *      Return value: 0, if @with_mm_only is set and the task has no mm of its
105  *              own or the task is frozen, 1, otherwise
106  *
107  *      The freeze request is sent by seting the tasks's TIF_FREEZE flag and
108  *      either sending a fake signal to it or waking it up, depending on whether
109  *      or not it has its own mm (ie. it is a user land task).  If @with_mm_only
110  *      is set and the task has no mm of its own (ie. it is a kernel thread),
111  *      its TIF_FREEZE flag should not be set.
112  *
113  *      The task_lock() is necessary to prevent races with exit_mm() or
114  *      use_mm()/unuse_mm() from occuring.
115  */
116 static int freeze_task(struct task_struct *p, int with_mm_only)
117 {
118         int ret = 1;
119
120         task_lock(p);
121         if (freezing(p)) {
122                 if (has_mm(p)) {
123                         if (!signal_pending(p))
124                                 fake_signal_wake_up(p, 0);
125                 } else {
126                         if (with_mm_only)
127                                 ret = 0;
128                         else
129                                 wake_up_state(p, TASK_INTERRUPTIBLE);
130                 }
131         } else {
132                 rmb();
133                 if (frozen(p)) {
134                         ret = 0;
135                 } else {
136                         if (has_mm(p)) {
137                                 set_freeze_flag(p);
138                                 send_fake_signal(p);
139                         } else {
140                                 if (with_mm_only) {
141                                         ret = 0;
142                                 } else {
143                                         set_freeze_flag(p);
144                                         wake_up_state(p, TASK_INTERRUPTIBLE);
145                                 }
146                         }
147                 }
148         }
149         task_unlock(p);
150         return ret;
151 }
152
153 static void cancel_freezing(struct task_struct *p)
154 {
155         unsigned long flags;
156
157         if (freezing(p)) {
158                 pr_debug("  clean up: %s\n", p->comm);
159                 clear_freeze_flag(p);
160                 spin_lock_irqsave(&p->sighand->siglock, flags);
161                 recalc_sigpending_and_wake(p);
162                 spin_unlock_irqrestore(&p->sighand->siglock, flags);
163         }
164 }
165
166 static int try_to_freeze_tasks(int freeze_user_space)
167 {
168         struct task_struct *g, *p;
169         unsigned long end_time;
170         unsigned int todo;
171         struct timeval start, end;
172         s64 elapsed_csecs64;
173         unsigned int elapsed_csecs;
174
175         do_gettimeofday(&start);
176
177         end_time = jiffies + TIMEOUT;
178         do {
179                 todo = 0;
180                 read_lock(&tasklist_lock);
181                 do_each_thread(g, p) {
182                         if (frozen(p) || !freezeable(p))
183                                 continue;
184
185                         if (p->state == TASK_TRACED && frozen(p->parent)) {
186                                 cancel_freezing(p);
187                                 continue;
188                         }
189
190                         if (!freeze_task(p, freeze_user_space))
191                                 continue;
192
193                         if (!freezer_should_skip(p))
194                                 todo++;
195                 } while_each_thread(g, p);
196                 read_unlock(&tasklist_lock);
197                 yield();                        /* Yield is okay here */
198                 if (time_after(jiffies, end_time))
199                         break;
200         } while (todo);
201
202         do_gettimeofday(&end);
203         elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
204         do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
205         elapsed_csecs = elapsed_csecs64;
206
207         if (todo) {
208                 /* This does not unfreeze processes that are already frozen
209                  * (we have slightly ugly calling convention in that respect,
210                  * and caller must call thaw_processes() if something fails),
211                  * but it cleans up leftover PF_FREEZE requests.
212                  */
213                 printk("\n");
214                 printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
215                                 "(%d tasks refusing to freeze):\n",
216                                 elapsed_csecs / 100, elapsed_csecs % 100, todo);
217                 show_state();
218                 read_lock(&tasklist_lock);
219                 do_each_thread(g, p) {
220                         task_lock(p);
221                         if (freezing(p) && !freezer_should_skip(p))
222                                 printk(KERN_ERR " %s\n", p->comm);
223                         cancel_freezing(p);
224                         task_unlock(p);
225                 } while_each_thread(g, p);
226                 read_unlock(&tasklist_lock);
227         } else {
228                 printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
229                         elapsed_csecs % 100);
230         }
231
232         return todo ? -EBUSY : 0;
233 }
234
235 /**
236  *      freeze_processes - tell processes to enter the refrigerator
237  */
238 int freeze_processes(void)
239 {
240         int error;
241
242         printk("Freezing user space processes ... ");
243         error = try_to_freeze_tasks(FREEZER_USER_SPACE);
244         if (error)
245                 goto Exit;
246         printk("done.\n");
247
248         printk("Freezing remaining freezable tasks ... ");
249         error = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
250         if (error)
251                 goto Exit;
252         printk("done.");
253  Exit:
254         BUG_ON(in_atomic());
255         printk("\n");
256         return error;
257 }
258
259 static void thaw_tasks(int thaw_user_space)
260 {
261         struct task_struct *g, *p;
262
263         read_lock(&tasklist_lock);
264         do_each_thread(g, p) {
265                 if (!freezeable(p))
266                         continue;
267
268                 if (!p->mm == thaw_user_space)
269                         continue;
270
271                 thaw_process(p);
272         } while_each_thread(g, p);
273         read_unlock(&tasklist_lock);
274 }
275
276 void thaw_processes(void)
277 {
278         printk("Restarting tasks ... ");
279         thaw_tasks(FREEZER_KERNEL_THREADS);
280         thaw_tasks(FREEZER_USER_SPACE);
281         schedule();
282         printk("done.\n");
283 }
284
285 EXPORT_SYMBOL(refrigerator);