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Commit | Line | Data |
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3d442233 JA |
1 | /* |
2 | * Generic helpers for smp ipi calls | |
3 | * | |
4 | * (C) Jens Axboe <jens.axboe@oracle.com> 2008 | |
3d442233 | 5 | */ |
3d442233 | 6 | #include <linux/rcupdate.h> |
59190f42 | 7 | #include <linux/rculist.h> |
641cd4cf | 8 | #include <linux/kernel.h> |
9984de1a | 9 | #include <linux/export.h> |
0b13fda1 IM |
10 | #include <linux/percpu.h> |
11 | #include <linux/init.h> | |
5a0e3ad6 | 12 | #include <linux/gfp.h> |
3d442233 | 13 | #include <linux/smp.h> |
8969a5ed | 14 | #include <linux/cpu.h> |
3d442233 | 15 | |
3bb5d2ee SS |
16 | #include "smpboot.h" |
17 | ||
351f8f8e | 18 | #ifdef CONFIG_USE_GENERIC_SMP_HELPERS |
3d442233 | 19 | enum { |
6e275637 | 20 | CSD_FLAG_LOCK = 0x01, |
3d442233 JA |
21 | }; |
22 | ||
23 | struct call_function_data { | |
9a46ad6d | 24 | struct call_single_data __percpu *csd; |
0b13fda1 | 25 | cpumask_var_t cpumask; |
f44310b9 | 26 | cpumask_var_t cpumask_ipi; |
3d442233 JA |
27 | }; |
28 | ||
e03bcb68 MM |
29 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data); |
30 | ||
3d442233 | 31 | struct call_single_queue { |
0b13fda1 | 32 | struct list_head list; |
9f5a5621 | 33 | raw_spinlock_t lock; |
3d442233 JA |
34 | }; |
35 | ||
e03bcb68 | 36 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_queue, call_single_queue); |
8969a5ed PZ |
37 | |
38 | static int | |
39 | hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) | |
40 | { | |
41 | long cpu = (long)hcpu; | |
42 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); | |
43 | ||
44 | switch (action) { | |
45 | case CPU_UP_PREPARE: | |
46 | case CPU_UP_PREPARE_FROZEN: | |
eaa95840 | 47 | if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, |
8969a5ed | 48 | cpu_to_node(cpu))) |
80b5184c | 49 | return notifier_from_errno(-ENOMEM); |
f44310b9 WY |
50 | if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL, |
51 | cpu_to_node(cpu))) | |
52 | return notifier_from_errno(-ENOMEM); | |
9a46ad6d SL |
53 | cfd->csd = alloc_percpu(struct call_single_data); |
54 | if (!cfd->csd) { | |
55 | free_cpumask_var(cfd->cpumask); | |
56 | return notifier_from_errno(-ENOMEM); | |
57 | } | |
8969a5ed PZ |
58 | break; |
59 | ||
69dd647f | 60 | #ifdef CONFIG_HOTPLUG_CPU |
8969a5ed PZ |
61 | case CPU_UP_CANCELED: |
62 | case CPU_UP_CANCELED_FROZEN: | |
63 | ||
64 | case CPU_DEAD: | |
65 | case CPU_DEAD_FROZEN: | |
66 | free_cpumask_var(cfd->cpumask); | |
f44310b9 | 67 | free_cpumask_var(cfd->cpumask_ipi); |
9a46ad6d | 68 | free_percpu(cfd->csd); |
8969a5ed PZ |
69 | break; |
70 | #endif | |
71 | }; | |
72 | ||
73 | return NOTIFY_OK; | |
74 | } | |
75 | ||
76 | static struct notifier_block __cpuinitdata hotplug_cfd_notifier = { | |
0b13fda1 | 77 | .notifier_call = hotplug_cfd, |
8969a5ed PZ |
78 | }; |
79 | ||
d8ad7d11 | 80 | void __init call_function_init(void) |
3d442233 | 81 | { |
8969a5ed | 82 | void *cpu = (void *)(long)smp_processor_id(); |
3d442233 JA |
83 | int i; |
84 | ||
85 | for_each_possible_cpu(i) { | |
86 | struct call_single_queue *q = &per_cpu(call_single_queue, i); | |
87 | ||
9f5a5621 | 88 | raw_spin_lock_init(&q->lock); |
3d442233 JA |
89 | INIT_LIST_HEAD(&q->list); |
90 | } | |
8969a5ed PZ |
91 | |
92 | hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu); | |
93 | register_cpu_notifier(&hotplug_cfd_notifier); | |
3d442233 JA |
94 | } |
95 | ||
8969a5ed PZ |
96 | /* |
97 | * csd_lock/csd_unlock used to serialize access to per-cpu csd resources | |
98 | * | |
0b13fda1 IM |
99 | * For non-synchronous ipi calls the csd can still be in use by the |
100 | * previous function call. For multi-cpu calls its even more interesting | |
101 | * as we'll have to ensure no other cpu is observing our csd. | |
8969a5ed | 102 | */ |
e1d12f32 | 103 | static void csd_lock_wait(struct call_single_data *csd) |
8969a5ed | 104 | { |
e1d12f32 | 105 | while (csd->flags & CSD_FLAG_LOCK) |
8969a5ed | 106 | cpu_relax(); |
6e275637 PZ |
107 | } |
108 | ||
e1d12f32 | 109 | static void csd_lock(struct call_single_data *csd) |
6e275637 | 110 | { |
e1d12f32 AM |
111 | csd_lock_wait(csd); |
112 | csd->flags |= CSD_FLAG_LOCK; | |
8969a5ed PZ |
113 | |
114 | /* | |
0b13fda1 IM |
115 | * prevent CPU from reordering the above assignment |
116 | * to ->flags with any subsequent assignments to other | |
117 | * fields of the specified call_single_data structure: | |
8969a5ed | 118 | */ |
8969a5ed PZ |
119 | smp_mb(); |
120 | } | |
121 | ||
e1d12f32 | 122 | static void csd_unlock(struct call_single_data *csd) |
8969a5ed | 123 | { |
e1d12f32 | 124 | WARN_ON(!(csd->flags & CSD_FLAG_LOCK)); |
0b13fda1 | 125 | |
8969a5ed | 126 | /* |
0b13fda1 | 127 | * ensure we're all done before releasing data: |
8969a5ed PZ |
128 | */ |
129 | smp_mb(); | |
0b13fda1 | 130 | |
e1d12f32 | 131 | csd->flags &= ~CSD_FLAG_LOCK; |
3d442233 JA |
132 | } |
133 | ||
134 | /* | |
0b13fda1 IM |
135 | * Insert a previously allocated call_single_data element |
136 | * for execution on the given CPU. data must already have | |
137 | * ->func, ->info, and ->flags set. | |
3d442233 | 138 | */ |
6e275637 | 139 | static |
e1d12f32 | 140 | void generic_exec_single(int cpu, struct call_single_data *csd, int wait) |
3d442233 JA |
141 | { |
142 | struct call_single_queue *dst = &per_cpu(call_single_queue, cpu); | |
3d442233 | 143 | unsigned long flags; |
6e275637 | 144 | int ipi; |
3d442233 | 145 | |
9f5a5621 | 146 | raw_spin_lock_irqsave(&dst->lock, flags); |
3d442233 | 147 | ipi = list_empty(&dst->list); |
e1d12f32 | 148 | list_add_tail(&csd->list, &dst->list); |
9f5a5621 | 149 | raw_spin_unlock_irqrestore(&dst->lock, flags); |
3d442233 | 150 | |
561920a0 | 151 | /* |
15d0d3b3 NP |
152 | * The list addition should be visible before sending the IPI |
153 | * handler locks the list to pull the entry off it because of | |
154 | * normal cache coherency rules implied by spinlocks. | |
155 | * | |
156 | * If IPIs can go out of order to the cache coherency protocol | |
157 | * in an architecture, sufficient synchronisation should be added | |
158 | * to arch code to make it appear to obey cache coherency WRT | |
0b13fda1 IM |
159 | * locking and barrier primitives. Generic code isn't really |
160 | * equipped to do the right thing... | |
561920a0 | 161 | */ |
3d442233 JA |
162 | if (ipi) |
163 | arch_send_call_function_single_ipi(cpu); | |
164 | ||
165 | if (wait) | |
e1d12f32 | 166 | csd_lock_wait(csd); |
3d442233 JA |
167 | } |
168 | ||
3d442233 | 169 | /* |
0b13fda1 IM |
170 | * Invoked by arch to handle an IPI for call function single. Must be |
171 | * called from the arch with interrupts disabled. | |
3d442233 JA |
172 | */ |
173 | void generic_smp_call_function_single_interrupt(void) | |
174 | { | |
175 | struct call_single_queue *q = &__get_cpu_var(call_single_queue); | |
0b13fda1 | 176 | LIST_HEAD(list); |
3d442233 | 177 | |
269c861b SS |
178 | /* |
179 | * Shouldn't receive this interrupt on a cpu that is not yet online. | |
180 | */ | |
181 | WARN_ON_ONCE(!cpu_online(smp_processor_id())); | |
182 | ||
9f5a5621 | 183 | raw_spin_lock(&q->lock); |
15d0d3b3 | 184 | list_replace_init(&q->list, &list); |
9f5a5621 | 185 | raw_spin_unlock(&q->lock); |
3d442233 | 186 | |
15d0d3b3 | 187 | while (!list_empty(&list)) { |
e1d12f32 AM |
188 | struct call_single_data *csd; |
189 | unsigned int csd_flags; | |
3d442233 | 190 | |
e1d12f32 AM |
191 | csd = list_entry(list.next, struct call_single_data, list); |
192 | list_del(&csd->list); | |
3d442233 | 193 | |
3d442233 | 194 | /* |
e1d12f32 | 195 | * 'csd' can be invalid after this call if flags == 0 |
0b13fda1 IM |
196 | * (when called through generic_exec_single()), |
197 | * so save them away before making the call: | |
3d442233 | 198 | */ |
e1d12f32 | 199 | csd_flags = csd->flags; |
15d0d3b3 | 200 | |
e1d12f32 | 201 | csd->func(csd->info); |
15d0d3b3 | 202 | |
8969a5ed | 203 | /* |
0b13fda1 | 204 | * Unlocked CSDs are valid through generic_exec_single(): |
8969a5ed | 205 | */ |
e1d12f32 AM |
206 | if (csd_flags & CSD_FLAG_LOCK) |
207 | csd_unlock(csd); | |
3d442233 JA |
208 | } |
209 | } | |
210 | ||
e03bcb68 | 211 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data); |
d7240b98 | 212 | |
3d442233 JA |
213 | /* |
214 | * smp_call_function_single - Run a function on a specific CPU | |
215 | * @func: The function to run. This must be fast and non-blocking. | |
216 | * @info: An arbitrary pointer to pass to the function. | |
3d442233 JA |
217 | * @wait: If true, wait until function has completed on other CPUs. |
218 | * | |
72f279b2 | 219 | * Returns 0 on success, else a negative status code. |
3d442233 | 220 | */ |
3a5f65df | 221 | int smp_call_function_single(int cpu, smp_call_func_t func, void *info, |
8691e5a8 | 222 | int wait) |
3d442233 | 223 | { |
8969a5ed PZ |
224 | struct call_single_data d = { |
225 | .flags = 0, | |
226 | }; | |
3d442233 | 227 | unsigned long flags; |
0b13fda1 | 228 | int this_cpu; |
f73be6de | 229 | int err = 0; |
3d442233 | 230 | |
0b13fda1 IM |
231 | /* |
232 | * prevent preemption and reschedule on another processor, | |
233 | * as well as CPU removal | |
234 | */ | |
235 | this_cpu = get_cpu(); | |
236 | ||
269c861b SS |
237 | /* |
238 | * Can deadlock when called with interrupts disabled. | |
239 | * We allow cpu's that are not yet online though, as no one else can | |
240 | * send smp call function interrupt to this cpu and as such deadlocks | |
241 | * can't happen. | |
242 | */ | |
243 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() | |
244 | && !oops_in_progress); | |
3d442233 | 245 | |
0b13fda1 | 246 | if (cpu == this_cpu) { |
3d442233 JA |
247 | local_irq_save(flags); |
248 | func(info); | |
249 | local_irq_restore(flags); | |
0b13fda1 IM |
250 | } else { |
251 | if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) { | |
e1d12f32 | 252 | struct call_single_data *csd = &d; |
3d442233 | 253 | |
0b13fda1 | 254 | if (!wait) |
e1d12f32 | 255 | csd = &__get_cpu_var(csd_data); |
6e275637 | 256 | |
e1d12f32 | 257 | csd_lock(csd); |
3d442233 | 258 | |
e1d12f32 AM |
259 | csd->func = func; |
260 | csd->info = info; | |
261 | generic_exec_single(cpu, csd, wait); | |
0b13fda1 IM |
262 | } else { |
263 | err = -ENXIO; /* CPU not online */ | |
264 | } | |
3d442233 JA |
265 | } |
266 | ||
267 | put_cpu(); | |
0b13fda1 | 268 | |
f73be6de | 269 | return err; |
3d442233 JA |
270 | } |
271 | EXPORT_SYMBOL(smp_call_function_single); | |
272 | ||
2ea6dec4 RR |
273 | /* |
274 | * smp_call_function_any - Run a function on any of the given cpus | |
275 | * @mask: The mask of cpus it can run on. | |
276 | * @func: The function to run. This must be fast and non-blocking. | |
277 | * @info: An arbitrary pointer to pass to the function. | |
278 | * @wait: If true, wait until function has completed. | |
279 | * | |
280 | * Returns 0 on success, else a negative status code (if no cpus were online). | |
281 | * Note that @wait will be implicitly turned on in case of allocation failures, | |
282 | * since we fall back to on-stack allocation. | |
283 | * | |
284 | * Selection preference: | |
285 | * 1) current cpu if in @mask | |
286 | * 2) any cpu of current node if in @mask | |
287 | * 3) any other online cpu in @mask | |
288 | */ | |
289 | int smp_call_function_any(const struct cpumask *mask, | |
3a5f65df | 290 | smp_call_func_t func, void *info, int wait) |
2ea6dec4 RR |
291 | { |
292 | unsigned int cpu; | |
293 | const struct cpumask *nodemask; | |
294 | int ret; | |
295 | ||
296 | /* Try for same CPU (cheapest) */ | |
297 | cpu = get_cpu(); | |
298 | if (cpumask_test_cpu(cpu, mask)) | |
299 | goto call; | |
300 | ||
301 | /* Try for same node. */ | |
af2422c4 | 302 | nodemask = cpumask_of_node(cpu_to_node(cpu)); |
2ea6dec4 RR |
303 | for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids; |
304 | cpu = cpumask_next_and(cpu, nodemask, mask)) { | |
305 | if (cpu_online(cpu)) | |
306 | goto call; | |
307 | } | |
308 | ||
309 | /* Any online will do: smp_call_function_single handles nr_cpu_ids. */ | |
310 | cpu = cpumask_any_and(mask, cpu_online_mask); | |
311 | call: | |
312 | ret = smp_call_function_single(cpu, func, info, wait); | |
313 | put_cpu(); | |
314 | return ret; | |
315 | } | |
316 | EXPORT_SYMBOL_GPL(smp_call_function_any); | |
317 | ||
3d442233 | 318 | /** |
27c379f7 | 319 | * __smp_call_function_single(): Run a function on a specific CPU |
3d442233 JA |
320 | * @cpu: The CPU to run on. |
321 | * @data: Pre-allocated and setup data structure | |
27c379f7 | 322 | * @wait: If true, wait until function has completed on specified CPU. |
3d442233 | 323 | * |
0b13fda1 IM |
324 | * Like smp_call_function_single(), but allow caller to pass in a |
325 | * pre-allocated data structure. Useful for embedding @data inside | |
326 | * other structures, for instance. | |
3d442233 | 327 | */ |
e1d12f32 | 328 | void __smp_call_function_single(int cpu, struct call_single_data *csd, |
6e275637 | 329 | int wait) |
3d442233 | 330 | { |
27c379f7 HC |
331 | unsigned int this_cpu; |
332 | unsigned long flags; | |
6e275637 | 333 | |
27c379f7 | 334 | this_cpu = get_cpu(); |
269c861b SS |
335 | /* |
336 | * Can deadlock when called with interrupts disabled. | |
337 | * We allow cpu's that are not yet online though, as no one else can | |
338 | * send smp call function interrupt to this cpu and as such deadlocks | |
339 | * can't happen. | |
340 | */ | |
341 | WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled() | |
342 | && !oops_in_progress); | |
3d442233 | 343 | |
27c379f7 HC |
344 | if (cpu == this_cpu) { |
345 | local_irq_save(flags); | |
e1d12f32 | 346 | csd->func(csd->info); |
27c379f7 HC |
347 | local_irq_restore(flags); |
348 | } else { | |
e1d12f32 AM |
349 | csd_lock(csd); |
350 | generic_exec_single(cpu, csd, wait); | |
27c379f7 HC |
351 | } |
352 | put_cpu(); | |
3d442233 JA |
353 | } |
354 | ||
355 | /** | |
54b11e6d RR |
356 | * smp_call_function_many(): Run a function on a set of other CPUs. |
357 | * @mask: The set of cpus to run on (only runs on online subset). | |
3d442233 JA |
358 | * @func: The function to run. This must be fast and non-blocking. |
359 | * @info: An arbitrary pointer to pass to the function. | |
0b13fda1 IM |
360 | * @wait: If true, wait (atomically) until function has completed |
361 | * on other CPUs. | |
3d442233 | 362 | * |
72f279b2 | 363 | * If @wait is true, then returns once @func has returned. |
3d442233 JA |
364 | * |
365 | * You must not call this function with disabled interrupts or from a | |
366 | * hardware interrupt handler or from a bottom half handler. Preemption | |
367 | * must be disabled when calling this function. | |
368 | */ | |
54b11e6d | 369 | void smp_call_function_many(const struct cpumask *mask, |
3a5f65df | 370 | smp_call_func_t func, void *info, bool wait) |
3d442233 | 371 | { |
e1d12f32 | 372 | struct call_function_data *cfd; |
9a46ad6d | 373 | int cpu, next_cpu, this_cpu = smp_processor_id(); |
3d442233 | 374 | |
269c861b SS |
375 | /* |
376 | * Can deadlock when called with interrupts disabled. | |
377 | * We allow cpu's that are not yet online though, as no one else can | |
378 | * send smp call function interrupt to this cpu and as such deadlocks | |
379 | * can't happen. | |
380 | */ | |
381 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() | |
bd924e8c | 382 | && !oops_in_progress && !early_boot_irqs_disabled); |
3d442233 | 383 | |
723aae25 | 384 | /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */ |
54b11e6d | 385 | cpu = cpumask_first_and(mask, cpu_online_mask); |
0b13fda1 | 386 | if (cpu == this_cpu) |
54b11e6d | 387 | cpu = cpumask_next_and(cpu, mask, cpu_online_mask); |
0b13fda1 | 388 | |
54b11e6d RR |
389 | /* No online cpus? We're done. */ |
390 | if (cpu >= nr_cpu_ids) | |
391 | return; | |
392 | ||
393 | /* Do we have another CPU which isn't us? */ | |
394 | next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); | |
0b13fda1 | 395 | if (next_cpu == this_cpu) |
54b11e6d RR |
396 | next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); |
397 | ||
398 | /* Fastpath: do that cpu by itself. */ | |
399 | if (next_cpu >= nr_cpu_ids) { | |
400 | smp_call_function_single(cpu, func, info, wait); | |
401 | return; | |
3d442233 JA |
402 | } |
403 | ||
e1d12f32 | 404 | cfd = &__get_cpu_var(cfd_data); |
45a57919 | 405 | |
e1d12f32 AM |
406 | cpumask_and(cfd->cpumask, mask, cpu_online_mask); |
407 | cpumask_clear_cpu(this_cpu, cfd->cpumask); | |
723aae25 MM |
408 | |
409 | /* Some callers race with other cpus changing the passed mask */ | |
e1d12f32 | 410 | if (unlikely(!cpumask_weight(cfd->cpumask))) |
723aae25 | 411 | return; |
3d442233 | 412 | |
f44310b9 | 413 | /* |
e1d12f32 AM |
414 | * After we put an entry into the list, cfd->cpumask may be cleared |
415 | * again when another CPU sends another IPI for a SMP function call, so | |
416 | * cfd->cpumask will be zero. | |
f44310b9 | 417 | */ |
e1d12f32 | 418 | cpumask_copy(cfd->cpumask_ipi, cfd->cpumask); |
3d442233 | 419 | |
e1d12f32 AM |
420 | for_each_cpu(cpu, cfd->cpumask) { |
421 | struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu); | |
9a46ad6d SL |
422 | struct call_single_queue *dst = |
423 | &per_cpu(call_single_queue, cpu); | |
424 | unsigned long flags; | |
425 | ||
426 | csd_lock(csd); | |
427 | csd->func = func; | |
428 | csd->info = info; | |
429 | ||
430 | raw_spin_lock_irqsave(&dst->lock, flags); | |
431 | list_add_tail(&csd->list, &dst->list); | |
432 | raw_spin_unlock_irqrestore(&dst->lock, flags); | |
433 | } | |
561920a0 | 434 | |
3d442233 | 435 | /* Send a message to all CPUs in the map */ |
e1d12f32 | 436 | arch_send_call_function_ipi_mask(cfd->cpumask_ipi); |
3d442233 | 437 | |
9a46ad6d | 438 | if (wait) { |
e1d12f32 AM |
439 | for_each_cpu(cpu, cfd->cpumask) { |
440 | struct call_single_data *csd; | |
441 | ||
442 | csd = per_cpu_ptr(cfd->csd, cpu); | |
9a46ad6d SL |
443 | csd_lock_wait(csd); |
444 | } | |
445 | } | |
3d442233 | 446 | } |
54b11e6d | 447 | EXPORT_SYMBOL(smp_call_function_many); |
3d442233 JA |
448 | |
449 | /** | |
450 | * smp_call_function(): Run a function on all other CPUs. | |
451 | * @func: The function to run. This must be fast and non-blocking. | |
452 | * @info: An arbitrary pointer to pass to the function. | |
0b13fda1 IM |
453 | * @wait: If true, wait (atomically) until function has completed |
454 | * on other CPUs. | |
3d442233 | 455 | * |
54b11e6d | 456 | * Returns 0. |
3d442233 JA |
457 | * |
458 | * If @wait is true, then returns once @func has returned; otherwise | |
72f279b2 | 459 | * it returns just before the target cpu calls @func. |
3d442233 JA |
460 | * |
461 | * You must not call this function with disabled interrupts or from a | |
462 | * hardware interrupt handler or from a bottom half handler. | |
463 | */ | |
3a5f65df | 464 | int smp_call_function(smp_call_func_t func, void *info, int wait) |
3d442233 | 465 | { |
3d442233 | 466 | preempt_disable(); |
54b11e6d | 467 | smp_call_function_many(cpu_online_mask, func, info, wait); |
3d442233 | 468 | preempt_enable(); |
0b13fda1 | 469 | |
54b11e6d | 470 | return 0; |
3d442233 JA |
471 | } |
472 | EXPORT_SYMBOL(smp_call_function); | |
351f8f8e AW |
473 | #endif /* USE_GENERIC_SMP_HELPERS */ |
474 | ||
34db18a0 AW |
475 | /* Setup configured maximum number of CPUs to activate */ |
476 | unsigned int setup_max_cpus = NR_CPUS; | |
477 | EXPORT_SYMBOL(setup_max_cpus); | |
478 | ||
479 | ||
480 | /* | |
481 | * Setup routine for controlling SMP activation | |
482 | * | |
483 | * Command-line option of "nosmp" or "maxcpus=0" will disable SMP | |
484 | * activation entirely (the MPS table probe still happens, though). | |
485 | * | |
486 | * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer | |
487 | * greater than 0, limits the maximum number of CPUs activated in | |
488 | * SMP mode to <NUM>. | |
489 | */ | |
490 | ||
491 | void __weak arch_disable_smp_support(void) { } | |
492 | ||
493 | static int __init nosmp(char *str) | |
494 | { | |
495 | setup_max_cpus = 0; | |
496 | arch_disable_smp_support(); | |
497 | ||
498 | return 0; | |
499 | } | |
500 | ||
501 | early_param("nosmp", nosmp); | |
502 | ||
503 | /* this is hard limit */ | |
504 | static int __init nrcpus(char *str) | |
505 | { | |
506 | int nr_cpus; | |
507 | ||
508 | get_option(&str, &nr_cpus); | |
509 | if (nr_cpus > 0 && nr_cpus < nr_cpu_ids) | |
510 | nr_cpu_ids = nr_cpus; | |
511 | ||
512 | return 0; | |
513 | } | |
514 | ||
515 | early_param("nr_cpus", nrcpus); | |
516 | ||
517 | static int __init maxcpus(char *str) | |
518 | { | |
519 | get_option(&str, &setup_max_cpus); | |
520 | if (setup_max_cpus == 0) | |
521 | arch_disable_smp_support(); | |
522 | ||
523 | return 0; | |
524 | } | |
525 | ||
526 | early_param("maxcpus", maxcpus); | |
527 | ||
528 | /* Setup number of possible processor ids */ | |
529 | int nr_cpu_ids __read_mostly = NR_CPUS; | |
530 | EXPORT_SYMBOL(nr_cpu_ids); | |
531 | ||
532 | /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */ | |
533 | void __init setup_nr_cpu_ids(void) | |
534 | { | |
535 | nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1; | |
536 | } | |
537 | ||
538 | /* Called by boot processor to activate the rest. */ | |
539 | void __init smp_init(void) | |
540 | { | |
541 | unsigned int cpu; | |
542 | ||
3bb5d2ee SS |
543 | idle_threads_init(); |
544 | ||
34db18a0 AW |
545 | /* FIXME: This should be done in userspace --RR */ |
546 | for_each_present_cpu(cpu) { | |
547 | if (num_online_cpus() >= setup_max_cpus) | |
548 | break; | |
549 | if (!cpu_online(cpu)) | |
550 | cpu_up(cpu); | |
551 | } | |
552 | ||
553 | /* Any cleanup work */ | |
554 | printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus()); | |
555 | smp_cpus_done(setup_max_cpus); | |
556 | } | |
557 | ||
351f8f8e | 558 | /* |
bd924e8c TH |
559 | * Call a function on all processors. May be used during early boot while |
560 | * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead | |
561 | * of local_irq_disable/enable(). | |
351f8f8e AW |
562 | */ |
563 | int on_each_cpu(void (*func) (void *info), void *info, int wait) | |
564 | { | |
bd924e8c | 565 | unsigned long flags; |
351f8f8e AW |
566 | int ret = 0; |
567 | ||
568 | preempt_disable(); | |
569 | ret = smp_call_function(func, info, wait); | |
bd924e8c | 570 | local_irq_save(flags); |
351f8f8e | 571 | func(info); |
bd924e8c | 572 | local_irq_restore(flags); |
351f8f8e AW |
573 | preempt_enable(); |
574 | return ret; | |
575 | } | |
576 | EXPORT_SYMBOL(on_each_cpu); | |
3fc498f1 GBY |
577 | |
578 | /** | |
579 | * on_each_cpu_mask(): Run a function on processors specified by | |
580 | * cpumask, which may include the local processor. | |
581 | * @mask: The set of cpus to run on (only runs on online subset). | |
582 | * @func: The function to run. This must be fast and non-blocking. | |
583 | * @info: An arbitrary pointer to pass to the function. | |
584 | * @wait: If true, wait (atomically) until function has completed | |
585 | * on other CPUs. | |
586 | * | |
587 | * If @wait is true, then returns once @func has returned. | |
588 | * | |
589 | * You must not call this function with disabled interrupts or | |
590 | * from a hardware interrupt handler or from a bottom half handler. | |
591 | */ | |
592 | void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func, | |
593 | void *info, bool wait) | |
594 | { | |
595 | int cpu = get_cpu(); | |
596 | ||
597 | smp_call_function_many(mask, func, info, wait); | |
598 | if (cpumask_test_cpu(cpu, mask)) { | |
599 | local_irq_disable(); | |
600 | func(info); | |
601 | local_irq_enable(); | |
602 | } | |
603 | put_cpu(); | |
604 | } | |
605 | EXPORT_SYMBOL(on_each_cpu_mask); | |
b3a7e98e GBY |
606 | |
607 | /* | |
608 | * on_each_cpu_cond(): Call a function on each processor for which | |
609 | * the supplied function cond_func returns true, optionally waiting | |
610 | * for all the required CPUs to finish. This may include the local | |
611 | * processor. | |
612 | * @cond_func: A callback function that is passed a cpu id and | |
613 | * the the info parameter. The function is called | |
614 | * with preemption disabled. The function should | |
615 | * return a blooean value indicating whether to IPI | |
616 | * the specified CPU. | |
617 | * @func: The function to run on all applicable CPUs. | |
618 | * This must be fast and non-blocking. | |
619 | * @info: An arbitrary pointer to pass to both functions. | |
620 | * @wait: If true, wait (atomically) until function has | |
621 | * completed on other CPUs. | |
622 | * @gfp_flags: GFP flags to use when allocating the cpumask | |
623 | * used internally by the function. | |
624 | * | |
625 | * The function might sleep if the GFP flags indicates a non | |
626 | * atomic allocation is allowed. | |
627 | * | |
628 | * Preemption is disabled to protect against CPUs going offline but not online. | |
629 | * CPUs going online during the call will not be seen or sent an IPI. | |
630 | * | |
631 | * You must not call this function with disabled interrupts or | |
632 | * from a hardware interrupt handler or from a bottom half handler. | |
633 | */ | |
634 | void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info), | |
635 | smp_call_func_t func, void *info, bool wait, | |
636 | gfp_t gfp_flags) | |
637 | { | |
638 | cpumask_var_t cpus; | |
639 | int cpu, ret; | |
640 | ||
641 | might_sleep_if(gfp_flags & __GFP_WAIT); | |
642 | ||
643 | if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) { | |
644 | preempt_disable(); | |
645 | for_each_online_cpu(cpu) | |
646 | if (cond_func(cpu, info)) | |
647 | cpumask_set_cpu(cpu, cpus); | |
648 | on_each_cpu_mask(cpus, func, info, wait); | |
649 | preempt_enable(); | |
650 | free_cpumask_var(cpus); | |
651 | } else { | |
652 | /* | |
653 | * No free cpumask, bother. No matter, we'll | |
654 | * just have to IPI them one by one. | |
655 | */ | |
656 | preempt_disable(); | |
657 | for_each_online_cpu(cpu) | |
658 | if (cond_func(cpu, info)) { | |
659 | ret = smp_call_function_single(cpu, func, | |
660 | info, wait); | |
661 | WARN_ON_ONCE(!ret); | |
662 | } | |
663 | preempt_enable(); | |
664 | } | |
665 | } | |
666 | EXPORT_SYMBOL(on_each_cpu_cond); | |
f37f435f TG |
667 | |
668 | static void do_nothing(void *unused) | |
669 | { | |
670 | } | |
671 | ||
672 | /** | |
673 | * kick_all_cpus_sync - Force all cpus out of idle | |
674 | * | |
675 | * Used to synchronize the update of pm_idle function pointer. It's | |
676 | * called after the pointer is updated and returns after the dummy | |
677 | * callback function has been executed on all cpus. The execution of | |
678 | * the function can only happen on the remote cpus after they have | |
679 | * left the idle function which had been called via pm_idle function | |
680 | * pointer. So it's guaranteed that nothing uses the previous pointer | |
681 | * anymore. | |
682 | */ | |
683 | void kick_all_cpus_sync(void) | |
684 | { | |
685 | /* Make sure the change is visible before we kick the cpus */ | |
686 | smp_mb(); | |
687 | smp_call_function(do_nothing, NULL, 1); | |
688 | } | |
689 | EXPORT_SYMBOL_GPL(kick_all_cpus_sync); |