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Commit | Line | Data |
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1da177e4 LT |
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... */ | |
a9d9baa1 | 19 | static DECLARE_MUTEX(cpucontrol); |
1da177e4 | 20 | |
e041c683 | 21 | static BLOCKING_NOTIFIER_HEAD(cpu_chain); |
1da177e4 | 22 | |
a9d9baa1 AR |
23 | #ifdef CONFIG_HOTPLUG_CPU |
24 | static struct task_struct *lock_cpu_hotplug_owner; | |
25 | static int lock_cpu_hotplug_depth; | |
90d45d17 | 26 | |
a9d9baa1 | 27 | static int __lock_cpu_hotplug(int interruptible) |
90d45d17 | 28 | { |
a9d9baa1 AR |
29 | int ret = 0; |
30 | ||
31 | if (lock_cpu_hotplug_owner != current) { | |
32 | if (interruptible) | |
33 | ret = down_interruptible(&cpucontrol); | |
34 | else | |
35 | down(&cpucontrol); | |
36 | } | |
37 | ||
38 | /* | |
39 | * Set only if we succeed in locking | |
40 | */ | |
41 | if (!ret) { | |
42 | lock_cpu_hotplug_depth++; | |
43 | lock_cpu_hotplug_owner = current; | |
44 | } | |
45 | ||
46 | return ret; | |
90d45d17 AR |
47 | } |
48 | ||
a9d9baa1 AR |
49 | void lock_cpu_hotplug(void) |
50 | { | |
51 | __lock_cpu_hotplug(0); | |
52 | } | |
53 | EXPORT_SYMBOL_GPL(lock_cpu_hotplug); | |
90d45d17 | 54 | |
a9d9baa1 AR |
55 | void unlock_cpu_hotplug(void) |
56 | { | |
57 | if (--lock_cpu_hotplug_depth == 0) { | |
58 | lock_cpu_hotplug_owner = NULL; | |
59 | up(&cpucontrol); | |
60 | } | |
61 | } | |
62 | EXPORT_SYMBOL_GPL(unlock_cpu_hotplug); | |
63 | ||
64 | int lock_cpu_hotplug_interruptible(void) | |
65 | { | |
66 | return __lock_cpu_hotplug(1); | |
67 | } | |
68 | EXPORT_SYMBOL_GPL(lock_cpu_hotplug_interruptible); | |
69 | #endif /* CONFIG_HOTPLUG_CPU */ | |
90d45d17 | 70 | |
1da177e4 LT |
71 | /* Need to know about CPUs going up/down? */ |
72 | int register_cpu_notifier(struct notifier_block *nb) | |
73 | { | |
e041c683 | 74 | return blocking_notifier_chain_register(&cpu_chain, nb); |
1da177e4 LT |
75 | } |
76 | EXPORT_SYMBOL(register_cpu_notifier); | |
77 | ||
78 | void unregister_cpu_notifier(struct notifier_block *nb) | |
79 | { | |
e041c683 | 80 | blocking_notifier_chain_unregister(&cpu_chain, nb); |
1da177e4 LT |
81 | } |
82 | EXPORT_SYMBOL(unregister_cpu_notifier); | |
83 | ||
84 | #ifdef CONFIG_HOTPLUG_CPU | |
85 | static inline void check_for_tasks(int cpu) | |
86 | { | |
87 | struct task_struct *p; | |
88 | ||
89 | write_lock_irq(&tasklist_lock); | |
90 | for_each_process(p) { | |
91 | if (task_cpu(p) == cpu && | |
92 | (!cputime_eq(p->utime, cputime_zero) || | |
93 | !cputime_eq(p->stime, cputime_zero))) | |
94 | printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\ | |
95 | (state = %ld, flags = %lx) \n", | |
96 | p->comm, p->pid, cpu, p->state, p->flags); | |
97 | } | |
98 | write_unlock_irq(&tasklist_lock); | |
99 | } | |
100 | ||
101 | /* Take this CPU down. */ | |
102 | static int take_cpu_down(void *unused) | |
103 | { | |
104 | int err; | |
105 | ||
1da177e4 LT |
106 | /* Ensure this CPU doesn't handle any more interrupts. */ |
107 | err = __cpu_disable(); | |
108 | if (err < 0) | |
f3705136 | 109 | return err; |
1da177e4 | 110 | |
f3705136 ZM |
111 | /* Force idle task to run as soon as we yield: it should |
112 | immediately notice cpu is offline and die quickly. */ | |
113 | sched_idle_next(); | |
114 | return 0; | |
1da177e4 LT |
115 | } |
116 | ||
117 | int cpu_down(unsigned int cpu) | |
118 | { | |
119 | int err; | |
120 | struct task_struct *p; | |
121 | cpumask_t old_allowed, tmp; | |
122 | ||
123 | if ((err = lock_cpu_hotplug_interruptible()) != 0) | |
124 | return err; | |
125 | ||
126 | if (num_online_cpus() == 1) { | |
127 | err = -EBUSY; | |
128 | goto out; | |
129 | } | |
130 | ||
131 | if (!cpu_online(cpu)) { | |
132 | err = -EINVAL; | |
133 | goto out; | |
134 | } | |
135 | ||
e041c683 | 136 | err = blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE, |
1da177e4 LT |
137 | (void *)(long)cpu); |
138 | if (err == NOTIFY_BAD) { | |
139 | printk("%s: attempt to take down CPU %u failed\n", | |
140 | __FUNCTION__, cpu); | |
141 | err = -EINVAL; | |
142 | goto out; | |
143 | } | |
144 | ||
145 | /* Ensure that we are not runnable on dying cpu */ | |
146 | old_allowed = current->cpus_allowed; | |
147 | tmp = CPU_MASK_ALL; | |
148 | cpu_clear(cpu, tmp); | |
149 | set_cpus_allowed(current, tmp); | |
150 | ||
151 | p = __stop_machine_run(take_cpu_down, NULL, cpu); | |
152 | if (IS_ERR(p)) { | |
153 | /* CPU didn't die: tell everyone. Can't complain. */ | |
e041c683 | 154 | if (blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED, |
1da177e4 LT |
155 | (void *)(long)cpu) == NOTIFY_BAD) |
156 | BUG(); | |
157 | ||
158 | err = PTR_ERR(p); | |
159 | goto out_allowed; | |
160 | } | |
161 | ||
162 | if (cpu_online(cpu)) | |
163 | goto out_thread; | |
164 | ||
165 | /* Wait for it to sleep (leaving idle task). */ | |
166 | while (!idle_cpu(cpu)) | |
167 | yield(); | |
168 | ||
169 | /* This actually kills the CPU. */ | |
170 | __cpu_die(cpu); | |
171 | ||
172 | /* Move it here so it can run. */ | |
173 | kthread_bind(p, get_cpu()); | |
174 | put_cpu(); | |
175 | ||
176 | /* CPU is completely dead: tell everyone. Too late to complain. */ | |
e041c683 AS |
177 | if (blocking_notifier_call_chain(&cpu_chain, CPU_DEAD, |
178 | (void *)(long)cpu) == NOTIFY_BAD) | |
1da177e4 LT |
179 | BUG(); |
180 | ||
181 | check_for_tasks(cpu); | |
182 | ||
183 | out_thread: | |
184 | err = kthread_stop(p); | |
185 | out_allowed: | |
186 | set_cpus_allowed(current, old_allowed); | |
187 | out: | |
188 | unlock_cpu_hotplug(); | |
189 | return err; | |
190 | } | |
191 | #endif /*CONFIG_HOTPLUG_CPU*/ | |
192 | ||
193 | int __devinit cpu_up(unsigned int cpu) | |
194 | { | |
195 | int ret; | |
196 | void *hcpu = (void *)(long)cpu; | |
197 | ||
a9d9baa1 | 198 | if ((ret = lock_cpu_hotplug_interruptible()) != 0) |
1da177e4 LT |
199 | return ret; |
200 | ||
201 | if (cpu_online(cpu) || !cpu_present(cpu)) { | |
202 | ret = -EINVAL; | |
203 | goto out; | |
204 | } | |
90d45d17 | 205 | |
e041c683 | 206 | ret = blocking_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu); |
1da177e4 LT |
207 | if (ret == NOTIFY_BAD) { |
208 | printk("%s: attempt to bring up CPU %u failed\n", | |
209 | __FUNCTION__, cpu); | |
210 | ret = -EINVAL; | |
211 | goto out_notify; | |
212 | } | |
213 | ||
214 | /* Arch-specific enabling code. */ | |
215 | ret = __cpu_up(cpu); | |
216 | if (ret != 0) | |
217 | goto out_notify; | |
6978c705 | 218 | BUG_ON(!cpu_online(cpu)); |
1da177e4 LT |
219 | |
220 | /* Now call notifier in preparation. */ | |
e041c683 | 221 | blocking_notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu); |
1da177e4 LT |
222 | |
223 | out_notify: | |
224 | if (ret != 0) | |
e041c683 AS |
225 | blocking_notifier_call_chain(&cpu_chain, |
226 | CPU_UP_CANCELED, hcpu); | |
1da177e4 | 227 | out: |
a9d9baa1 | 228 | unlock_cpu_hotplug(); |
1da177e4 LT |
229 | return ret; |
230 | } |