Use helpers to obtain task pid in printks
[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, task_pid_nr(p), cpu,
102                                  p->state, p->flags);
103         }
104         write_unlock_irq(&tasklist_lock);
105 }
106
107 struct take_cpu_down_param {
108         unsigned long mod;
109         void *hcpu;
110 };
111
112 /* Take this CPU down. */
113 static int take_cpu_down(void *_param)
114 {
115         struct take_cpu_down_param *param = _param;
116         int err;
117
118         raw_notifier_call_chain(&cpu_chain, CPU_DYING | param->mod,
119                                 param->hcpu);
120         /* Ensure this CPU doesn't handle any more interrupts. */
121         err = __cpu_disable();
122         if (err < 0)
123                 return err;
124
125         /* Force idle task to run as soon as we yield: it should
126            immediately notice cpu is offline and die quickly. */
127         sched_idle_next();
128         return 0;
129 }
130
131 /* Requires cpu_add_remove_lock to be held */
132 static int _cpu_down(unsigned int cpu, int tasks_frozen)
133 {
134         int err, nr_calls = 0;
135         struct task_struct *p;
136         cpumask_t old_allowed, tmp;
137         void *hcpu = (void *)(long)cpu;
138         unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
139         struct take_cpu_down_param tcd_param = {
140                 .mod = mod,
141                 .hcpu = hcpu,
142         };
143
144         if (num_online_cpus() == 1)
145                 return -EBUSY;
146
147         if (!cpu_online(cpu))
148                 return -EINVAL;
149
150         raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
151         err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod,
152                                         hcpu, -1, &nr_calls);
153         if (err == NOTIFY_BAD) {
154                 nr_calls--;
155                 __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
156                                           hcpu, nr_calls, NULL);
157                 printk("%s: attempt to take down CPU %u failed\n",
158                                 __FUNCTION__, cpu);
159                 err = -EINVAL;
160                 goto out_release;
161         }
162
163         /* Ensure that we are not runnable on dying cpu */
164         old_allowed = current->cpus_allowed;
165         tmp = CPU_MASK_ALL;
166         cpu_clear(cpu, tmp);
167         set_cpus_allowed(current, tmp);
168
169         mutex_lock(&cpu_bitmask_lock);
170         p = __stop_machine_run(take_cpu_down, &tcd_param, cpu);
171         mutex_unlock(&cpu_bitmask_lock);
172
173         if (IS_ERR(p) || cpu_online(cpu)) {
174                 /* CPU didn't die: tell everyone.  Can't complain. */
175                 if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
176                                             hcpu) == NOTIFY_BAD)
177                         BUG();
178
179                 if (IS_ERR(p)) {
180                         err = PTR_ERR(p);
181                         goto out_allowed;
182                 }
183                 goto out_thread;
184         }
185
186         /* Wait for it to sleep (leaving idle task). */
187         while (!idle_cpu(cpu))
188                 yield();
189
190         /* This actually kills the CPU. */
191         __cpu_die(cpu);
192
193         /* CPU is completely dead: tell everyone.  Too late to complain. */
194         if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD | mod,
195                                     hcpu) == NOTIFY_BAD)
196                 BUG();
197
198         check_for_tasks(cpu);
199
200 out_thread:
201         err = kthread_stop(p);
202 out_allowed:
203         set_cpus_allowed(current, old_allowed);
204 out_release:
205         raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);
206         return err;
207 }
208
209 int cpu_down(unsigned int cpu)
210 {
211         int err = 0;
212
213         mutex_lock(&cpu_add_remove_lock);
214         if (cpu_hotplug_disabled)
215                 err = -EBUSY;
216         else
217                 err = _cpu_down(cpu, 0);
218
219         mutex_unlock(&cpu_add_remove_lock);
220         return err;
221 }
222 #endif /*CONFIG_HOTPLUG_CPU*/
223
224 /* Requires cpu_add_remove_lock to be held */
225 static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
226 {
227         int ret, nr_calls = 0;
228         void *hcpu = (void *)(long)cpu;
229         unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
230
231         if (cpu_online(cpu) || !cpu_present(cpu))
232                 return -EINVAL;
233
234         raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
235         ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE | mod, hcpu,
236                                                         -1, &nr_calls);
237         if (ret == NOTIFY_BAD) {
238                 nr_calls--;
239                 printk("%s: attempt to bring up CPU %u failed\n",
240                                 __FUNCTION__, cpu);
241                 ret = -EINVAL;
242                 goto out_notify;
243         }
244
245         /* Arch-specific enabling code. */
246         mutex_lock(&cpu_bitmask_lock);
247         ret = __cpu_up(cpu);
248         mutex_unlock(&cpu_bitmask_lock);
249         if (ret != 0)
250                 goto out_notify;
251         BUG_ON(!cpu_online(cpu));
252
253         /* Now call notifier in preparation. */
254         raw_notifier_call_chain(&cpu_chain, CPU_ONLINE | mod, hcpu);
255
256 out_notify:
257         if (ret != 0)
258                 __raw_notifier_call_chain(&cpu_chain,
259                                 CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
260         raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);
261
262         return ret;
263 }
264
265 int __cpuinit cpu_up(unsigned int cpu)
266 {
267         int err = 0;
268
269         mutex_lock(&cpu_add_remove_lock);
270         if (cpu_hotplug_disabled)
271                 err = -EBUSY;
272         else
273                 err = _cpu_up(cpu, 0);
274
275         mutex_unlock(&cpu_add_remove_lock);
276         return err;
277 }
278
279 #ifdef CONFIG_PM_SLEEP_SMP
280 static cpumask_t frozen_cpus;
281
282 int disable_nonboot_cpus(void)
283 {
284         int cpu, first_cpu, error = 0;
285
286         mutex_lock(&cpu_add_remove_lock);
287         first_cpu = first_cpu(cpu_online_map);
288         /* We take down all of the non-boot CPUs in one shot to avoid races
289          * with the userspace trying to use the CPU hotplug at the same time
290          */
291         cpus_clear(frozen_cpus);
292         printk("Disabling non-boot CPUs ...\n");
293         for_each_online_cpu(cpu) {
294                 if (cpu == first_cpu)
295                         continue;
296                 error = _cpu_down(cpu, 1);
297                 if (!error) {
298                         cpu_set(cpu, frozen_cpus);
299                         printk("CPU%d is down\n", cpu);
300                 } else {
301                         printk(KERN_ERR "Error taking CPU%d down: %d\n",
302                                 cpu, error);
303                         break;
304                 }
305         }
306         if (!error) {
307                 BUG_ON(num_online_cpus() > 1);
308                 /* Make sure the CPUs won't be enabled by someone else */
309                 cpu_hotplug_disabled = 1;
310         } else {
311                 printk(KERN_ERR "Non-boot CPUs are not disabled\n");
312         }
313         mutex_unlock(&cpu_add_remove_lock);
314         return error;
315 }
316
317 void enable_nonboot_cpus(void)
318 {
319         int cpu, error;
320
321         /* Allow everyone to use the CPU hotplug again */
322         mutex_lock(&cpu_add_remove_lock);
323         cpu_hotplug_disabled = 0;
324         if (cpus_empty(frozen_cpus))
325                 goto out;
326
327         printk("Enabling non-boot CPUs ...\n");
328         for_each_cpu_mask(cpu, frozen_cpus) {
329                 error = _cpu_up(cpu, 1);
330                 if (!error) {
331                         printk("CPU%d is up\n", cpu);
332                         continue;
333                 }
334                 printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
335         }
336         cpus_clear(frozen_cpus);
337 out:
338         mutex_unlock(&cpu_add_remove_lock);
339 }
340 #endif /* CONFIG_PM_SLEEP_SMP */