[IPV6]: Clean skb cb on IPv6 input.
[linux-2.6] / 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 BLOCKING_NOTIFIER_HEAD(cpu_chain);
23
24 #ifdef CONFIG_HOTPLUG_CPU
25
26 /* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
27 static struct task_struct *recursive;
28 static int recursive_depth;
29
30 void lock_cpu_hotplug(void)
31 {
32         struct task_struct *tsk = current;
33
34         if (tsk == recursive) {
35                 static int warnings = 10;
36                 if (warnings) {
37                         printk(KERN_ERR "Lukewarm IQ detected in hotplug locking\n");
38                         WARN_ON(1);
39                         warnings--;
40                 }
41                 recursive_depth++;
42                 return;
43         }
44         mutex_lock(&cpu_bitmask_lock);
45         recursive = tsk;
46 }
47 EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
48
49 void unlock_cpu_hotplug(void)
50 {
51         WARN_ON(recursive != current);
52         if (recursive_depth) {
53                 recursive_depth--;
54                 return;
55         }
56         mutex_unlock(&cpu_bitmask_lock);
57         recursive = NULL;
58 }
59 EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
60
61 #endif  /* CONFIG_HOTPLUG_CPU */
62
63 /* Need to know about CPUs going up/down? */
64 int __cpuinit register_cpu_notifier(struct notifier_block *nb)
65 {
66         return blocking_notifier_chain_register(&cpu_chain, nb);
67 }
68
69 #ifdef CONFIG_HOTPLUG_CPU
70
71 EXPORT_SYMBOL(register_cpu_notifier);
72
73 void unregister_cpu_notifier(struct notifier_block *nb)
74 {
75         blocking_notifier_chain_unregister(&cpu_chain, nb);
76 }
77 EXPORT_SYMBOL(unregister_cpu_notifier);
78
79 static inline void check_for_tasks(int cpu)
80 {
81         struct task_struct *p;
82
83         write_lock_irq(&tasklist_lock);
84         for_each_process(p) {
85                 if (task_cpu(p) == cpu &&
86                     (!cputime_eq(p->utime, cputime_zero) ||
87                      !cputime_eq(p->stime, cputime_zero)))
88                         printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
89                                 (state = %ld, flags = %lx) \n",
90                                  p->comm, p->pid, cpu, p->state, p->flags);
91         }
92         write_unlock_irq(&tasklist_lock);
93 }
94
95 /* Take this CPU down. */
96 static int take_cpu_down(void *unused)
97 {
98         int err;
99
100         /* Ensure this CPU doesn't handle any more interrupts. */
101         err = __cpu_disable();
102         if (err < 0)
103                 return err;
104
105         /* Force idle task to run as soon as we yield: it should
106            immediately notice cpu is offline and die quickly. */
107         sched_idle_next();
108         return 0;
109 }
110
111 int cpu_down(unsigned int cpu)
112 {
113         int err;
114         struct task_struct *p;
115         cpumask_t old_allowed, tmp;
116
117         mutex_lock(&cpu_add_remove_lock);
118         if (num_online_cpus() == 1) {
119                 err = -EBUSY;
120                 goto out;
121         }
122
123         if (!cpu_online(cpu)) {
124                 err = -EINVAL;
125                 goto out;
126         }
127
128         err = blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
129                                                 (void *)(long)cpu);
130         if (err == NOTIFY_BAD) {
131                 printk("%s: attempt to take down CPU %u failed\n",
132                                 __FUNCTION__, cpu);
133                 err = -EINVAL;
134                 goto out;
135         }
136
137         /* Ensure that we are not runnable on dying cpu */
138         old_allowed = current->cpus_allowed;
139         tmp = CPU_MASK_ALL;
140         cpu_clear(cpu, tmp);
141         set_cpus_allowed(current, tmp);
142
143         mutex_lock(&cpu_bitmask_lock);
144         p = __stop_machine_run(take_cpu_down, NULL, cpu);
145         mutex_unlock(&cpu_bitmask_lock);
146
147         if (IS_ERR(p)) {
148                 /* CPU didn't die: tell everyone.  Can't complain. */
149                 if (blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
150                                 (void *)(long)cpu) == NOTIFY_BAD)
151                         BUG();
152
153                 err = PTR_ERR(p);
154                 goto out_allowed;
155         }
156
157         if (cpu_online(cpu))
158                 goto out_thread;
159
160         /* Wait for it to sleep (leaving idle task). */
161         while (!idle_cpu(cpu))
162                 yield();
163
164         /* This actually kills the CPU. */
165         __cpu_die(cpu);
166
167         /* Move it here so it can run. */
168         kthread_bind(p, get_cpu());
169         put_cpu();
170
171         /* CPU is completely dead: tell everyone.  Too late to complain. */
172         if (blocking_notifier_call_chain(&cpu_chain, CPU_DEAD,
173                         (void *)(long)cpu) == NOTIFY_BAD)
174                 BUG();
175
176         check_for_tasks(cpu);
177
178 out_thread:
179         err = kthread_stop(p);
180 out_allowed:
181         set_cpus_allowed(current, old_allowed);
182 out:
183         mutex_unlock(&cpu_add_remove_lock);
184         return err;
185 }
186 #endif /*CONFIG_HOTPLUG_CPU*/
187
188 int __devinit cpu_up(unsigned int cpu)
189 {
190         int ret;
191         void *hcpu = (void *)(long)cpu;
192
193         mutex_lock(&cpu_add_remove_lock);
194         if (cpu_online(cpu) || !cpu_present(cpu)) {
195                 ret = -EINVAL;
196                 goto out;
197         }
198
199         ret = blocking_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
200         if (ret == NOTIFY_BAD) {
201                 printk("%s: attempt to bring up CPU %u failed\n",
202                                 __FUNCTION__, cpu);
203                 ret = -EINVAL;
204                 goto out_notify;
205         }
206
207         /* Arch-specific enabling code. */
208         mutex_lock(&cpu_bitmask_lock);
209         ret = __cpu_up(cpu);
210         mutex_unlock(&cpu_bitmask_lock);
211         if (ret != 0)
212                 goto out_notify;
213         BUG_ON(!cpu_online(cpu));
214
215         /* Now call notifier in preparation. */
216         blocking_notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
217
218 out_notify:
219         if (ret != 0)
220                 blocking_notifier_call_chain(&cpu_chain,
221                                 CPU_UP_CANCELED, hcpu);
222 out:
223         mutex_unlock(&cpu_add_remove_lock);
224         return ret;
225 }