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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /kernel/cpu.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'kernel/cpu.c')
-rw-r--r--kernel/cpu.c193
1 files changed, 193 insertions, 0 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
new file mode 100644
index 000000000000..628f4ccda127
--- /dev/null
+++ b/kernel/cpu.c
@@ -0,0 +1,193 @@
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 <asm/semaphore.h>
17
18/* This protects CPUs going up and down... */
19DECLARE_MUTEX(cpucontrol);
20
21static struct notifier_block *cpu_chain;
22
23/* Need to know about CPUs going up/down? */
24int register_cpu_notifier(struct notifier_block *nb)
25{
26 int ret;
27
28 if ((ret = down_interruptible(&cpucontrol)) != 0)
29 return ret;
30 ret = notifier_chain_register(&cpu_chain, nb);
31 up(&cpucontrol);
32 return ret;
33}
34EXPORT_SYMBOL(register_cpu_notifier);
35
36void unregister_cpu_notifier(struct notifier_block *nb)
37{
38 down(&cpucontrol);
39 notifier_chain_unregister(&cpu_chain, nb);
40 up(&cpucontrol);
41}
42EXPORT_SYMBOL(unregister_cpu_notifier);
43
44#ifdef CONFIG_HOTPLUG_CPU
45static inline void check_for_tasks(int cpu)
46{
47 struct task_struct *p;
48
49 write_lock_irq(&tasklist_lock);
50 for_each_process(p) {
51 if (task_cpu(p) == cpu &&
52 (!cputime_eq(p->utime, cputime_zero) ||
53 !cputime_eq(p->stime, cputime_zero)))
54 printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
55 (state = %ld, flags = %lx) \n",
56 p->comm, p->pid, cpu, p->state, p->flags);
57 }
58 write_unlock_irq(&tasklist_lock);
59}
60
61/* Take this CPU down. */
62static int take_cpu_down(void *unused)
63{
64 int err;
65
66 /* Take offline: makes arch_cpu_down somewhat easier. */
67 cpu_clear(smp_processor_id(), cpu_online_map);
68
69 /* Ensure this CPU doesn't handle any more interrupts. */
70 err = __cpu_disable();
71 if (err < 0)
72 cpu_set(smp_processor_id(), cpu_online_map);
73 else
74 /* Force idle task to run as soon as we yield: it should
75 immediately notice cpu is offline and die quickly. */
76 sched_idle_next();
77
78 return err;
79}
80
81int cpu_down(unsigned int cpu)
82{
83 int err;
84 struct task_struct *p;
85 cpumask_t old_allowed, tmp;
86
87 if ((err = lock_cpu_hotplug_interruptible()) != 0)
88 return err;
89
90 if (num_online_cpus() == 1) {
91 err = -EBUSY;
92 goto out;
93 }
94
95 if (!cpu_online(cpu)) {
96 err = -EINVAL;
97 goto out;
98 }
99
100 err = notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
101 (void *)(long)cpu);
102 if (err == NOTIFY_BAD) {
103 printk("%s: attempt to take down CPU %u failed\n",
104 __FUNCTION__, cpu);
105 err = -EINVAL;
106 goto out;
107 }
108
109 /* Ensure that we are not runnable on dying cpu */
110 old_allowed = current->cpus_allowed;
111 tmp = CPU_MASK_ALL;
112 cpu_clear(cpu, tmp);
113 set_cpus_allowed(current, tmp);
114
115 p = __stop_machine_run(take_cpu_down, NULL, cpu);
116 if (IS_ERR(p)) {
117 /* CPU didn't die: tell everyone. Can't complain. */
118 if (notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
119 (void *)(long)cpu) == NOTIFY_BAD)
120 BUG();
121
122 err = PTR_ERR(p);
123 goto out_allowed;
124 }
125
126 if (cpu_online(cpu))
127 goto out_thread;
128
129 /* Wait for it to sleep (leaving idle task). */
130 while (!idle_cpu(cpu))
131 yield();
132
133 /* This actually kills the CPU. */
134 __cpu_die(cpu);
135
136 /* Move it here so it can run. */
137 kthread_bind(p, get_cpu());
138 put_cpu();
139
140 /* CPU is completely dead: tell everyone. Too late to complain. */
141 if (notifier_call_chain(&cpu_chain, CPU_DEAD, (void *)(long)cpu)
142 == NOTIFY_BAD)
143 BUG();
144
145 check_for_tasks(cpu);
146
147out_thread:
148 err = kthread_stop(p);
149out_allowed:
150 set_cpus_allowed(current, old_allowed);
151out:
152 unlock_cpu_hotplug();
153 return err;
154}
155#endif /*CONFIG_HOTPLUG_CPU*/
156
157int __devinit cpu_up(unsigned int cpu)
158{
159 int ret;
160 void *hcpu = (void *)(long)cpu;
161
162 if ((ret = down_interruptible(&cpucontrol)) != 0)
163 return ret;
164
165 if (cpu_online(cpu) || !cpu_present(cpu)) {
166 ret = -EINVAL;
167 goto out;
168 }
169 ret = notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
170 if (ret == NOTIFY_BAD) {
171 printk("%s: attempt to bring up CPU %u failed\n",
172 __FUNCTION__, cpu);
173 ret = -EINVAL;
174 goto out_notify;
175 }
176
177 /* Arch-specific enabling code. */
178 ret = __cpu_up(cpu);
179 if (ret != 0)
180 goto out_notify;
181 if (!cpu_online(cpu))
182 BUG();
183
184 /* Now call notifier in preparation. */
185 notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
186
187out_notify:
188 if (ret != 0)
189 notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu);
190out:
191 up(&cpucontrol);
192 return ret;
193}