Remove kthread_bind() call from _cpu_down()
[linux-2.6.git] / kernel / cpu.c
1 /* CPU control.
2  * (C) 2001, 2002, 2003, 2004 Rusty Russell
3  *
4  * This code is licenced under the GPL.
5  */
6 #include <linux/proc_fs.h>
7 #include <linux/smp.h>
8 #include <linux/init.h>
9 #include <linux/notifier.h>
10 #include <linux/sched.h>
11 #include <linux/unistd.h>
12 #include <linux/cpu.h>
13 #include <linux/module.h>
14 #include <linux/kthread.h>
15 #include <linux/stop_machine.h>
16 #include <linux/mutex.h>
17
18 /* This protects CPUs going up and down... */
19 static DEFINE_MUTEX(cpu_add_remove_lock);
20 static DEFINE_MUTEX(cpu_bitmask_lock);
21
22 static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain);
23
24 /* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
25  * Should always be manipulated under cpu_add_remove_lock
26  */
27 static int cpu_hotplug_disabled;
28
29 #ifdef CONFIG_HOTPLUG_CPU
30
31 /* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
32 static struct task_struct *recursive;
33 static int recursive_depth;
34
35 void lock_cpu_hotplug(void)
36 {
37         struct task_struct *tsk = current;
38
39         if (tsk == recursive) {
40                 static int warnings = 10;
41                 if (warnings) {
42                         printk(KERN_ERR "Lukewarm IQ detected in hotplug locking\n");
43                         WARN_ON(1);
44                         warnings--;
45                 }
46                 recursive_depth++;
47                 return;
48         }
49         mutex_lock(&cpu_bitmask_lock);
50         recursive = tsk;
51 }
52 EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
53
54 void unlock_cpu_hotplug(void)
55 {
56         WARN_ON(recursive != current);
57         if (recursive_depth) {
58                 recursive_depth--;
59                 return;
60         }
61         recursive = NULL;
62         mutex_unlock(&cpu_bitmask_lock);
63 }
64 EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
65
66 #endif  /* CONFIG_HOTPLUG_CPU */
67
68 /* Need to know about CPUs going up/down? */
69 int __cpuinit register_cpu_notifier(struct notifier_block *nb)
70 {
71         int ret;
72         mutex_lock(&cpu_add_remove_lock);
73         ret = raw_notifier_chain_register(&cpu_chain, nb);
74         mutex_unlock(&cpu_add_remove_lock);
75         return ret;
76 }
77
78 #ifdef CONFIG_HOTPLUG_CPU
79
80 EXPORT_SYMBOL(register_cpu_notifier);
81
82 void unregister_cpu_notifier(struct notifier_block *nb)
83 {
84         mutex_lock(&cpu_add_remove_lock);
85         raw_notifier_chain_unregister(&cpu_chain, nb);
86         mutex_unlock(&cpu_add_remove_lock);
87 }
88 EXPORT_SYMBOL(unregister_cpu_notifier);
89
90 static inline void check_for_tasks(int cpu)
91 {
92         struct task_struct *p;
93
94         write_lock_irq(&tasklist_lock);
95         for_each_process(p) {
96                 if (task_cpu(p) == cpu &&
97                     (!cputime_eq(p->utime, cputime_zero) ||
98                      !cputime_eq(p->stime, cputime_zero)))
99                         printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
100                                 (state = %ld, flags = %x) \n",
101                                  p->comm, p->pid, cpu, p->state, p->flags);
102         }
103         write_unlock_irq(&tasklist_lock);
104 }
105
106 /* Take this CPU down. */
107 static int take_cpu_down(void *unused)
108 {
109         int err;
110
111         /* Ensure this CPU doesn't handle any more interrupts. */
112         err = __cpu_disable();
113         if (err < 0)
114                 return err;
115
116         /* Force idle task to run as soon as we yield: it should
117            immediately notice cpu is offline and die quickly. */
118         sched_idle_next();
119         return 0;
120 }
121
122 /* Requires cpu_add_remove_lock to be held */
123 static int _cpu_down(unsigned int cpu)
124 {
125         int err, nr_calls = 0;
126         struct task_struct *p;
127         cpumask_t old_allowed, tmp;
128         void *hcpu = (void *)(long)cpu;
129
130         if (num_online_cpus() == 1)
131                 return -EBUSY;
132
133         if (!cpu_online(cpu))
134                 return -EINVAL;
135
136         raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
137         err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
138                                         hcpu, -1, &nr_calls);
139         if (err == NOTIFY_BAD) {
140                 __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED, hcpu,
141                                           nr_calls, NULL);
142                 printk("%s: attempt to take down CPU %u failed\n",
143                                 __FUNCTION__, cpu);
144                 err = -EINVAL;
145                 goto out_release;
146         }
147
148         /* Ensure that we are not runnable on dying cpu */
149         old_allowed = current->cpus_allowed;
150         tmp = CPU_MASK_ALL;
151         cpu_clear(cpu, tmp);
152         set_cpus_allowed(current, tmp);
153
154         mutex_lock(&cpu_bitmask_lock);
155         p = __stop_machine_run(take_cpu_down, NULL, cpu);
156         mutex_unlock(&cpu_bitmask_lock);
157
158         if (IS_ERR(p) || cpu_online(cpu)) {
159                 /* CPU didn't die: tell everyone.  Can't complain. */
160                 if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
161                                             hcpu) == NOTIFY_BAD)
162                         BUG();
163
164                 if (IS_ERR(p)) {
165                         err = PTR_ERR(p);
166                         goto out_allowed;
167                 }
168                 goto out_thread;
169         }
170
171         /* Wait for it to sleep (leaving idle task). */
172         while (!idle_cpu(cpu))
173                 yield();
174
175         /* This actually kills the CPU. */
176         __cpu_die(cpu);
177
178         /* CPU is completely dead: tell everyone.  Too late to complain. */
179         if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD, hcpu) == NOTIFY_BAD)
180                 BUG();
181
182         check_for_tasks(cpu);
183
184 out_thread:
185         err = kthread_stop(p);
186 out_allowed:
187         set_cpus_allowed(current, old_allowed);
188 out_release:
189         raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE,
190                                                 (void *)(long)cpu);
191         return err;
192 }
193
194 int cpu_down(unsigned int cpu)
195 {
196         int err = 0;
197
198         mutex_lock(&cpu_add_remove_lock);
199         if (cpu_hotplug_disabled)
200                 err = -EBUSY;
201         else
202                 err = _cpu_down(cpu);
203
204         mutex_unlock(&cpu_add_remove_lock);
205         return err;
206 }
207 #endif /*CONFIG_HOTPLUG_CPU*/
208
209 /* Requires cpu_add_remove_lock to be held */
210 static int __cpuinit _cpu_up(unsigned int cpu)
211 {
212         int ret, nr_calls = 0;
213         void *hcpu = (void *)(long)cpu;
214
215         if (cpu_online(cpu) || !cpu_present(cpu))
216                 return -EINVAL;
217
218         raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
219         ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu,
220                                                         -1, &nr_calls);
221         if (ret == NOTIFY_BAD) {
222                 printk("%s: attempt to bring up CPU %u failed\n",
223                                 __FUNCTION__, cpu);
224                 ret = -EINVAL;
225                 goto out_notify;
226         }
227
228         /* Arch-specific enabling code. */
229         mutex_lock(&cpu_bitmask_lock);
230         ret = __cpu_up(cpu);
231         mutex_unlock(&cpu_bitmask_lock);
232         if (ret != 0)
233                 goto out_notify;
234         BUG_ON(!cpu_online(cpu));
235
236         /* Now call notifier in preparation. */
237         raw_notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
238
239 out_notify:
240         if (ret != 0)
241                 __raw_notifier_call_chain(&cpu_chain,
242                                 CPU_UP_CANCELED, hcpu, nr_calls, NULL);
243         raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);
244
245         return ret;
246 }
247
248 int __cpuinit cpu_up(unsigned int cpu)
249 {
250         int err = 0;
251
252         mutex_lock(&cpu_add_remove_lock);
253         if (cpu_hotplug_disabled)
254                 err = -EBUSY;
255         else
256                 err = _cpu_up(cpu);
257
258         mutex_unlock(&cpu_add_remove_lock);
259         return err;
260 }
261
262 #ifdef CONFIG_SUSPEND_SMP
263 /* Needed to prevent the microcode driver from requesting firmware in its CPU
264  * hotplug notifier during the suspend/resume.
265  */
266 int suspend_cpu_hotplug;
267 EXPORT_SYMBOL(suspend_cpu_hotplug);
268
269 static cpumask_t frozen_cpus;
270
271 int disable_nonboot_cpus(void)
272 {
273         int cpu, first_cpu, error = 0;
274
275         mutex_lock(&cpu_add_remove_lock);
276         suspend_cpu_hotplug = 1;
277         first_cpu = first_cpu(cpu_online_map);
278         /* We take down all of the non-boot CPUs in one shot to avoid races
279          * with the userspace trying to use the CPU hotplug at the same time
280          */
281         cpus_clear(frozen_cpus);
282         printk("Disabling non-boot CPUs ...\n");
283         for_each_online_cpu(cpu) {
284                 if (cpu == first_cpu)
285                         continue;
286                 error = _cpu_down(cpu);
287                 if (!error) {
288                         cpu_set(cpu, frozen_cpus);
289                         printk("CPU%d is down\n", cpu);
290                 } else {
291                         printk(KERN_ERR "Error taking CPU%d down: %d\n",
292                                 cpu, error);
293                         break;
294                 }
295         }
296         if (!error) {
297                 BUG_ON(num_online_cpus() > 1);
298                 /* Make sure the CPUs won't be enabled by someone else */
299                 cpu_hotplug_disabled = 1;
300         } else {
301                 printk(KERN_ERR "Non-boot CPUs are not disabled\n");
302         }
303         suspend_cpu_hotplug = 0;
304         mutex_unlock(&cpu_add_remove_lock);
305         return error;
306 }
307
308 void enable_nonboot_cpus(void)
309 {
310         int cpu, error;
311
312         /* Allow everyone to use the CPU hotplug again */
313         mutex_lock(&cpu_add_remove_lock);
314         cpu_hotplug_disabled = 0;
315         if (cpus_empty(frozen_cpus))
316                 goto out;
317
318         suspend_cpu_hotplug = 1;
319         printk("Enabling non-boot CPUs ...\n");
320         for_each_cpu_mask(cpu, frozen_cpus) {
321                 error = _cpu_up(cpu);
322                 if (!error) {
323                         printk("CPU%d is up\n", cpu);
324                         continue;
325                 }
326                 printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
327         }
328         cpus_clear(frozen_cpus);
329         suspend_cpu_hotplug = 0;
330 out:
331         mutex_unlock(&cpu_add_remove_lock);
332 }
333 #endif