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 | |
bd5349cf | 22 | static __cpuinitdata RAW_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 | 61 | recursive = NULL; |
4b96b1a1 | 62 | mutex_unlock(&cpu_bitmask_lock); |
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 | { |
bd5349cf NB |
71 | int ret; |
72 | mutex_lock(&cpu_add_remove_lock); | |
73 | ret = raw_notifier_chain_register(&cpu_chain, nb); | |
74 | mutex_unlock(&cpu_add_remove_lock); | |
75 | return ret; | |
1da177e4 | 76 | } |
65edc68c CS |
77 | |
78 | #ifdef CONFIG_HOTPLUG_CPU | |
79 | ||
1da177e4 LT |
80 | EXPORT_SYMBOL(register_cpu_notifier); |
81 | ||
82 | void unregister_cpu_notifier(struct notifier_block *nb) | |
83 | { | |
bd5349cf NB |
84 | mutex_lock(&cpu_add_remove_lock); |
85 | raw_notifier_chain_unregister(&cpu_chain, nb); | |
86 | mutex_unlock(&cpu_add_remove_lock); | |
1da177e4 LT |
87 | } |
88 | EXPORT_SYMBOL(unregister_cpu_notifier); | |
89 | ||
1da177e4 LT |
90 | static inline void check_for_tasks(int cpu) |
91 | { | |
92 | struct task_struct *p; | |
93 | ||
94 | write_lock_irq(&tasklist_lock); | |
95 | for_each_process(p) { | |
96 | if (task_cpu(p) == cpu && | |
97 | (!cputime_eq(p->utime, cputime_zero) || | |
98 | !cputime_eq(p->stime, cputime_zero))) | |
99 | printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\ | |
e7407dcc | 100 | (state = %ld, flags = %x) \n", |
1da177e4 LT |
101 | p->comm, p->pid, cpu, p->state, p->flags); |
102 | } | |
103 | write_unlock_irq(&tasklist_lock); | |
104 | } | |
105 | ||
db912f96 AK |
106 | struct take_cpu_down_param { |
107 | unsigned long mod; | |
108 | void *hcpu; | |
109 | }; | |
110 | ||
1da177e4 | 111 | /* Take this CPU down. */ |
db912f96 | 112 | static int take_cpu_down(void *_param) |
1da177e4 | 113 | { |
db912f96 | 114 | struct take_cpu_down_param *param = _param; |
1da177e4 LT |
115 | int err; |
116 | ||
db912f96 AK |
117 | raw_notifier_call_chain(&cpu_chain, CPU_DYING | param->mod, |
118 | param->hcpu); | |
1da177e4 LT |
119 | /* Ensure this CPU doesn't handle any more interrupts. */ |
120 | err = __cpu_disable(); | |
121 | if (err < 0) | |
f3705136 | 122 | return err; |
1da177e4 | 123 | |
f3705136 ZM |
124 | /* Force idle task to run as soon as we yield: it should |
125 | immediately notice cpu is offline and die quickly. */ | |
126 | sched_idle_next(); | |
127 | return 0; | |
1da177e4 LT |
128 | } |
129 | ||
e3920fb4 | 130 | /* Requires cpu_add_remove_lock to be held */ |
8bb78442 | 131 | static int _cpu_down(unsigned int cpu, int tasks_frozen) |
1da177e4 | 132 | { |
e7407dcc | 133 | int err, nr_calls = 0; |
1da177e4 LT |
134 | struct task_struct *p; |
135 | cpumask_t old_allowed, tmp; | |
e7407dcc | 136 | void *hcpu = (void *)(long)cpu; |
8bb78442 | 137 | unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0; |
db912f96 AK |
138 | struct take_cpu_down_param tcd_param = { |
139 | .mod = mod, | |
140 | .hcpu = hcpu, | |
141 | }; | |
1da177e4 | 142 | |
e3920fb4 RW |
143 | if (num_online_cpus() == 1) |
144 | return -EBUSY; | |
1da177e4 | 145 | |
e3920fb4 RW |
146 | if (!cpu_online(cpu)) |
147 | return -EINVAL; | |
1da177e4 | 148 | |
e7407dcc | 149 | raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu); |
8bb78442 | 150 | err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod, |
e7407dcc | 151 | hcpu, -1, &nr_calls); |
1da177e4 | 152 | if (err == NOTIFY_BAD) { |
8bb78442 RW |
153 | __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod, |
154 | hcpu, nr_calls, NULL); | |
1da177e4 LT |
155 | printk("%s: attempt to take down CPU %u failed\n", |
156 | __FUNCTION__, cpu); | |
baaca49f GS |
157 | err = -EINVAL; |
158 | goto out_release; | |
1da177e4 LT |
159 | } |
160 | ||
161 | /* Ensure that we are not runnable on dying cpu */ | |
162 | old_allowed = current->cpus_allowed; | |
163 | tmp = CPU_MASK_ALL; | |
164 | cpu_clear(cpu, tmp); | |
165 | set_cpus_allowed(current, tmp); | |
166 | ||
aa953877 | 167 | mutex_lock(&cpu_bitmask_lock); |
db912f96 | 168 | p = __stop_machine_run(take_cpu_down, &tcd_param, cpu); |
aa953877 LT |
169 | mutex_unlock(&cpu_bitmask_lock); |
170 | ||
8fa1d7d3 | 171 | if (IS_ERR(p) || cpu_online(cpu)) { |
1da177e4 | 172 | /* CPU didn't die: tell everyone. Can't complain. */ |
8bb78442 | 173 | if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod, |
e7407dcc | 174 | hcpu) == NOTIFY_BAD) |
1da177e4 LT |
175 | BUG(); |
176 | ||
8fa1d7d3 ST |
177 | if (IS_ERR(p)) { |
178 | err = PTR_ERR(p); | |
179 | goto out_allowed; | |
180 | } | |
1da177e4 | 181 | goto out_thread; |
8fa1d7d3 | 182 | } |
1da177e4 LT |
183 | |
184 | /* Wait for it to sleep (leaving idle task). */ | |
185 | while (!idle_cpu(cpu)) | |
186 | yield(); | |
187 | ||
188 | /* This actually kills the CPU. */ | |
189 | __cpu_die(cpu); | |
190 | ||
1da177e4 | 191 | /* CPU is completely dead: tell everyone. Too late to complain. */ |
8bb78442 RW |
192 | if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD | mod, |
193 | hcpu) == NOTIFY_BAD) | |
1da177e4 LT |
194 | BUG(); |
195 | ||
196 | check_for_tasks(cpu); | |
197 | ||
198 | out_thread: | |
199 | err = kthread_stop(p); | |
200 | out_allowed: | |
201 | set_cpus_allowed(current, old_allowed); | |
baaca49f | 202 | out_release: |
8bb78442 | 203 | raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu); |
e3920fb4 RW |
204 | return err; |
205 | } | |
206 | ||
207 | int cpu_down(unsigned int cpu) | |
208 | { | |
209 | int err = 0; | |
210 | ||
211 | mutex_lock(&cpu_add_remove_lock); | |
212 | if (cpu_hotplug_disabled) | |
213 | err = -EBUSY; | |
214 | else | |
8bb78442 | 215 | err = _cpu_down(cpu, 0); |
e3920fb4 | 216 | |
aa953877 | 217 | mutex_unlock(&cpu_add_remove_lock); |
1da177e4 LT |
218 | return err; |
219 | } | |
220 | #endif /*CONFIG_HOTPLUG_CPU*/ | |
221 | ||
e3920fb4 | 222 | /* Requires cpu_add_remove_lock to be held */ |
8bb78442 | 223 | static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen) |
1da177e4 | 224 | { |
baaca49f | 225 | int ret, nr_calls = 0; |
1da177e4 | 226 | void *hcpu = (void *)(long)cpu; |
8bb78442 | 227 | unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0; |
1da177e4 | 228 | |
e3920fb4 RW |
229 | if (cpu_online(cpu) || !cpu_present(cpu)) |
230 | return -EINVAL; | |
90d45d17 | 231 | |
baaca49f | 232 | raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu); |
8bb78442 | 233 | ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE | mod, hcpu, |
baaca49f | 234 | -1, &nr_calls); |
1da177e4 LT |
235 | if (ret == NOTIFY_BAD) { |
236 | printk("%s: attempt to bring up CPU %u failed\n", | |
237 | __FUNCTION__, cpu); | |
238 | ret = -EINVAL; | |
239 | goto out_notify; | |
240 | } | |
241 | ||
242 | /* Arch-specific enabling code. */ | |
aa953877 | 243 | mutex_lock(&cpu_bitmask_lock); |
1da177e4 | 244 | ret = __cpu_up(cpu); |
aa953877 | 245 | mutex_unlock(&cpu_bitmask_lock); |
1da177e4 LT |
246 | if (ret != 0) |
247 | goto out_notify; | |
6978c705 | 248 | BUG_ON(!cpu_online(cpu)); |
1da177e4 LT |
249 | |
250 | /* Now call notifier in preparation. */ | |
8bb78442 | 251 | raw_notifier_call_chain(&cpu_chain, CPU_ONLINE | mod, hcpu); |
1da177e4 LT |
252 | |
253 | out_notify: | |
254 | if (ret != 0) | |
baaca49f | 255 | __raw_notifier_call_chain(&cpu_chain, |
8bb78442 | 256 | CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL); |
baaca49f | 257 | raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu); |
e3920fb4 RW |
258 | |
259 | return ret; | |
260 | } | |
261 | ||
b282b6f8 | 262 | int __cpuinit cpu_up(unsigned int cpu) |
e3920fb4 RW |
263 | { |
264 | int err = 0; | |
265 | ||
266 | mutex_lock(&cpu_add_remove_lock); | |
267 | if (cpu_hotplug_disabled) | |
268 | err = -EBUSY; | |
269 | else | |
8bb78442 | 270 | err = _cpu_up(cpu, 0); |
e3920fb4 RW |
271 | |
272 | mutex_unlock(&cpu_add_remove_lock); | |
273 | return err; | |
274 | } | |
275 | ||
f3de4be9 | 276 | #ifdef CONFIG_PM_SLEEP_SMP |
e3920fb4 RW |
277 | static cpumask_t frozen_cpus; |
278 | ||
279 | int disable_nonboot_cpus(void) | |
280 | { | |
e1d9fd2e | 281 | int cpu, first_cpu, error = 0; |
e3920fb4 RW |
282 | |
283 | mutex_lock(&cpu_add_remove_lock); | |
1d64b9cb | 284 | first_cpu = first_cpu(cpu_online_map); |
e3920fb4 RW |
285 | /* We take down all of the non-boot CPUs in one shot to avoid races |
286 | * with the userspace trying to use the CPU hotplug at the same time | |
287 | */ | |
288 | cpus_clear(frozen_cpus); | |
289 | printk("Disabling non-boot CPUs ...\n"); | |
290 | for_each_online_cpu(cpu) { | |
291 | if (cpu == first_cpu) | |
292 | continue; | |
8bb78442 | 293 | error = _cpu_down(cpu, 1); |
e3920fb4 RW |
294 | if (!error) { |
295 | cpu_set(cpu, frozen_cpus); | |
296 | printk("CPU%d is down\n", cpu); | |
297 | } else { | |
298 | printk(KERN_ERR "Error taking CPU%d down: %d\n", | |
299 | cpu, error); | |
300 | break; | |
301 | } | |
302 | } | |
303 | if (!error) { | |
304 | BUG_ON(num_online_cpus() > 1); | |
305 | /* Make sure the CPUs won't be enabled by someone else */ | |
306 | cpu_hotplug_disabled = 1; | |
307 | } else { | |
e1d9fd2e | 308 | printk(KERN_ERR "Non-boot CPUs are not disabled\n"); |
e3920fb4 | 309 | } |
aa953877 | 310 | mutex_unlock(&cpu_add_remove_lock); |
e3920fb4 RW |
311 | return error; |
312 | } | |
313 | ||
314 | void enable_nonboot_cpus(void) | |
315 | { | |
316 | int cpu, error; | |
317 | ||
318 | /* Allow everyone to use the CPU hotplug again */ | |
319 | mutex_lock(&cpu_add_remove_lock); | |
320 | cpu_hotplug_disabled = 0; | |
ed746e3b | 321 | if (cpus_empty(frozen_cpus)) |
1d64b9cb | 322 | goto out; |
e3920fb4 RW |
323 | |
324 | printk("Enabling non-boot CPUs ...\n"); | |
325 | for_each_cpu_mask(cpu, frozen_cpus) { | |
8bb78442 | 326 | error = _cpu_up(cpu, 1); |
e3920fb4 RW |
327 | if (!error) { |
328 | printk("CPU%d is up\n", cpu); | |
329 | continue; | |
330 | } | |
1d64b9cb | 331 | printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error); |
e3920fb4 RW |
332 | } |
333 | cpus_clear(frozen_cpus); | |
1d64b9cb RW |
334 | out: |
335 | mutex_unlock(&cpu_add_remove_lock); | |
1da177e4 | 336 | } |
f3de4be9 | 337 | #endif /* CONFIG_PM_SLEEP_SMP */ |