Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/kernel/cpu.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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File size: 4265 byte(s)
Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 4265 byte(s)
Tag kernel26-2.6.12-alx-r9
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... */ |
19 | DECLARE_MUTEX(cpucontrol); |
20 | |
21 | static struct notifier_block *cpu_chain; |
22 | |
23 | /* Need to know about CPUs going up/down? */ |
24 | int 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 | } |
34 | EXPORT_SYMBOL(register_cpu_notifier); |
35 | |
36 | void unregister_cpu_notifier(struct notifier_block *nb) |
37 | { |
38 | down(&cpucontrol); |
39 | notifier_chain_unregister(&cpu_chain, nb); |
40 | up(&cpucontrol); |
41 | } |
42 | EXPORT_SYMBOL(unregister_cpu_notifier); |
43 | |
44 | #ifdef CONFIG_HOTPLUG_CPU |
45 | static 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. */ |
62 | static 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 | |
81 | int 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 | |
147 | out_thread: |
148 | err = kthread_stop(p); |
149 | out_allowed: |
150 | set_cpus_allowed(current, old_allowed); |
151 | out: |
152 | unlock_cpu_hotplug(); |
153 | return err; |
154 | } |
155 | #endif /*CONFIG_HOTPLUG_CPU*/ |
156 | |
157 | int __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 | |
187 | out_notify: |
188 | if (ret != 0) |
189 | notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu); |
190 | out: |
191 | up(&cpucontrol); |
192 | return ret; |
193 | } |