Commit | Line | Data |
---|---|---|
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> | |
81615b62 | 16 | #include <linux/mutex.h> |
1da177e4 LT |
17 | |
18 | /* This protects CPUs going up and down... */ | |
aa953877 LT |
19 | static DEFINE_MUTEX(cpu_add_remove_lock); |
20 | static DEFINE_MUTEX(cpu_bitmask_lock); | |
1da177e4 | 21 | |
65edc68c | 22 | static __cpuinitdata BLOCKING_NOTIFIER_HEAD(cpu_chain); |
1da177e4 | 23 | |
e3920fb4 RW |
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 | ||
a9d9baa1 | 29 | #ifdef CONFIG_HOTPLUG_CPU |
90d45d17 | 30 | |
aa953877 LT |
31 | /* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */ |
32 | static struct task_struct *recursive; | |
33 | static int recursive_depth; | |
90d45d17 | 34 | |
a9d9baa1 AR |
35 | void lock_cpu_hotplug(void) |
36 | { | |
aa953877 LT |
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; | |
a9d9baa1 AR |
51 | } |
52 | EXPORT_SYMBOL_GPL(lock_cpu_hotplug); | |
90d45d17 | 53 | |
a9d9baa1 AR |
54 | void unlock_cpu_hotplug(void) |
55 | { | |
aa953877 LT |
56 | WARN_ON(recursive != current); |
57 | if (recursive_depth) { | |
58 | recursive_depth--; | |
59 | return; | |
a9d9baa1 | 60 | } |
aa953877 LT |
61 | mutex_unlock(&cpu_bitmask_lock); |
62 | recursive = NULL; | |
a9d9baa1 AR |
63 | } |
64 | EXPORT_SYMBOL_GPL(unlock_cpu_hotplug); | |
65 | ||
a9d9baa1 | 66 | #endif /* CONFIG_HOTPLUG_CPU */ |
90d45d17 | 67 | |
1da177e4 | 68 | /* Need to know about CPUs going up/down? */ |
65edc68c | 69 | int __cpuinit register_cpu_notifier(struct notifier_block *nb) |
1da177e4 | 70 | { |
e041c683 | 71 | return blocking_notifier_chain_register(&cpu_chain, nb); |
1da177e4 | 72 | } |
65edc68c CS |
73 | |
74 | #ifdef CONFIG_HOTPLUG_CPU | |
75 | ||
1da177e4 LT |
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 | ||
1da177e4 LT |
84 | static inline void check_for_tasks(int cpu) |
85 | { | |
86 | struct task_struct *p; | |
87 | ||
88 | write_lock_irq(&tasklist_lock); | |
89 | for_each_process(p) { | |
90 | if (task_cpu(p) == cpu && | |
91 | (!cputime_eq(p->utime, cputime_zero) || | |
92 | !cputime_eq(p->stime, cputime_zero))) | |
93 | printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\ | |
94 | (state = %ld, flags = %lx) \n", | |
95 | p->comm, p->pid, cpu, p->state, p->flags); | |
96 | } | |
97 | write_unlock_irq(&tasklist_lock); | |
98 | } | |
99 | ||
100 | /* Take this CPU down. */ | |
101 | static int take_cpu_down(void *unused) | |
102 | { | |
103 | int err; | |
104 | ||
1da177e4 LT |
105 | /* Ensure this CPU doesn't handle any more interrupts. */ |
106 | err = __cpu_disable(); | |
107 | if (err < 0) | |
f3705136 | 108 | return err; |
1da177e4 | 109 | |
f3705136 ZM |
110 | /* Force idle task to run as soon as we yield: it should |
111 | immediately notice cpu is offline and die quickly. */ | |
112 | sched_idle_next(); | |
113 | return 0; | |
1da177e4 LT |
114 | } |
115 | ||
e3920fb4 RW |
116 | /* Requires cpu_add_remove_lock to be held */ |
117 | static int _cpu_down(unsigned int cpu) | |
1da177e4 LT |
118 | { |
119 | int err; | |
120 | struct task_struct *p; | |
121 | cpumask_t old_allowed, tmp; | |
122 | ||
e3920fb4 RW |
123 | if (num_online_cpus() == 1) |
124 | return -EBUSY; | |
1da177e4 | 125 | |
e3920fb4 RW |
126 | if (!cpu_online(cpu)) |
127 | return -EINVAL; | |
1da177e4 | 128 | |
e041c683 | 129 | err = blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE, |
1da177e4 LT |
130 | (void *)(long)cpu); |
131 | if (err == NOTIFY_BAD) { | |
132 | printk("%s: attempt to take down CPU %u failed\n", | |
133 | __FUNCTION__, cpu); | |
e3920fb4 | 134 | return -EINVAL; |
1da177e4 LT |
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 | ||
aa953877 | 143 | mutex_lock(&cpu_bitmask_lock); |
1da177e4 | 144 | p = __stop_machine_run(take_cpu_down, NULL, cpu); |
aa953877 LT |
145 | mutex_unlock(&cpu_bitmask_lock); |
146 | ||
1da177e4 LT |
147 | if (IS_ERR(p)) { |
148 | /* CPU didn't die: tell everyone. Can't complain. */ | |
e041c683 | 149 | if (blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED, |
1da177e4 LT |
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. */ | |
e041c683 AS |
172 | if (blocking_notifier_call_chain(&cpu_chain, CPU_DEAD, |
173 | (void *)(long)cpu) == NOTIFY_BAD) | |
1da177e4 LT |
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); | |
e3920fb4 RW |
182 | return err; |
183 | } | |
184 | ||
185 | int cpu_down(unsigned int cpu) | |
186 | { | |
187 | int err = 0; | |
188 | ||
189 | mutex_lock(&cpu_add_remove_lock); | |
190 | if (cpu_hotplug_disabled) | |
191 | err = -EBUSY; | |
192 | else | |
193 | err = _cpu_down(cpu); | |
194 | ||
aa953877 | 195 | mutex_unlock(&cpu_add_remove_lock); |
1da177e4 LT |
196 | return err; |
197 | } | |
198 | #endif /*CONFIG_HOTPLUG_CPU*/ | |
199 | ||
e3920fb4 RW |
200 | /* Requires cpu_add_remove_lock to be held */ |
201 | static int __devinit _cpu_up(unsigned int cpu) | |
1da177e4 LT |
202 | { |
203 | int ret; | |
204 | void *hcpu = (void *)(long)cpu; | |
205 | ||
e3920fb4 RW |
206 | if (cpu_online(cpu) || !cpu_present(cpu)) |
207 | return -EINVAL; | |
90d45d17 | 208 | |
e041c683 | 209 | ret = blocking_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu); |
1da177e4 LT |
210 | if (ret == NOTIFY_BAD) { |
211 | printk("%s: attempt to bring up CPU %u failed\n", | |
212 | __FUNCTION__, cpu); | |
213 | ret = -EINVAL; | |
214 | goto out_notify; | |
215 | } | |
216 | ||
217 | /* Arch-specific enabling code. */ | |
aa953877 | 218 | mutex_lock(&cpu_bitmask_lock); |
1da177e4 | 219 | ret = __cpu_up(cpu); |
aa953877 | 220 | mutex_unlock(&cpu_bitmask_lock); |
1da177e4 LT |
221 | if (ret != 0) |
222 | goto out_notify; | |
6978c705 | 223 | BUG_ON(!cpu_online(cpu)); |
1da177e4 LT |
224 | |
225 | /* Now call notifier in preparation. */ | |
e041c683 | 226 | blocking_notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu); |
1da177e4 LT |
227 | |
228 | out_notify: | |
229 | if (ret != 0) | |
e041c683 AS |
230 | blocking_notifier_call_chain(&cpu_chain, |
231 | CPU_UP_CANCELED, hcpu); | |
e3920fb4 RW |
232 | |
233 | return ret; | |
234 | } | |
235 | ||
236 | int __devinit cpu_up(unsigned int cpu) | |
237 | { | |
238 | int err = 0; | |
239 | ||
240 | mutex_lock(&cpu_add_remove_lock); | |
241 | if (cpu_hotplug_disabled) | |
242 | err = -EBUSY; | |
243 | else | |
244 | err = _cpu_up(cpu); | |
245 | ||
246 | mutex_unlock(&cpu_add_remove_lock); | |
247 | return err; | |
248 | } | |
249 | ||
250 | #ifdef CONFIG_SUSPEND_SMP | |
251 | static cpumask_t frozen_cpus; | |
252 | ||
253 | int disable_nonboot_cpus(void) | |
254 | { | |
255 | int cpu, first_cpu, error; | |
256 | ||
257 | mutex_lock(&cpu_add_remove_lock); | |
258 | first_cpu = first_cpu(cpu_present_map); | |
259 | if (!cpu_online(first_cpu)) { | |
260 | error = _cpu_up(first_cpu); | |
261 | if (error) { | |
262 | printk(KERN_ERR "Could not bring CPU%d up.\n", | |
263 | first_cpu); | |
264 | goto out; | |
265 | } | |
266 | } | |
267 | error = set_cpus_allowed(current, cpumask_of_cpu(first_cpu)); | |
268 | if (error) { | |
269 | printk(KERN_ERR "Could not run on CPU%d\n", first_cpu); | |
270 | goto out; | |
271 | } | |
272 | /* We take down all of the non-boot CPUs in one shot to avoid races | |
273 | * with the userspace trying to use the CPU hotplug at the same time | |
274 | */ | |
275 | cpus_clear(frozen_cpus); | |
276 | printk("Disabling non-boot CPUs ...\n"); | |
277 | for_each_online_cpu(cpu) { | |
278 | if (cpu == first_cpu) | |
279 | continue; | |
280 | error = _cpu_down(cpu); | |
281 | if (!error) { | |
282 | cpu_set(cpu, frozen_cpus); | |
283 | printk("CPU%d is down\n", cpu); | |
284 | } else { | |
285 | printk(KERN_ERR "Error taking CPU%d down: %d\n", | |
286 | cpu, error); | |
287 | break; | |
288 | } | |
289 | } | |
290 | if (!error) { | |
291 | BUG_ON(num_online_cpus() > 1); | |
292 | /* Make sure the CPUs won't be enabled by someone else */ | |
293 | cpu_hotplug_disabled = 1; | |
294 | } else { | |
295 | printk(KERN_ERR "Non-boot CPUs are not disabled"); | |
296 | } | |
1da177e4 | 297 | out: |
aa953877 | 298 | mutex_unlock(&cpu_add_remove_lock); |
e3920fb4 RW |
299 | return error; |
300 | } | |
301 | ||
302 | void enable_nonboot_cpus(void) | |
303 | { | |
304 | int cpu, error; | |
305 | ||
306 | /* Allow everyone to use the CPU hotplug again */ | |
307 | mutex_lock(&cpu_add_remove_lock); | |
308 | cpu_hotplug_disabled = 0; | |
309 | mutex_unlock(&cpu_add_remove_lock); | |
310 | ||
311 | printk("Enabling non-boot CPUs ...\n"); | |
312 | for_each_cpu_mask(cpu, frozen_cpus) { | |
313 | error = cpu_up(cpu); | |
314 | if (!error) { | |
315 | printk("CPU%d is up\n", cpu); | |
316 | continue; | |
317 | } | |
318 | printk(KERN_WARNING "Error taking CPU%d up: %d\n", | |
319 | cpu, error); | |
320 | } | |
321 | cpus_clear(frozen_cpus); | |
1da177e4 | 322 | } |
e3920fb4 | 323 | #endif |