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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 | */ |
47885016 | 6 | #include <linux/irq_work.h> |
3d442233 | 7 | #include <linux/rcupdate.h> |
59190f42 | 8 | #include <linux/rculist.h> |
641cd4cf | 9 | #include <linux/kernel.h> |
9984de1a | 10 | #include <linux/export.h> |
0b13fda1 IM |
11 | #include <linux/percpu.h> |
12 | #include <linux/init.h> | |
5a0e3ad6 | 13 | #include <linux/gfp.h> |
3d442233 | 14 | #include <linux/smp.h> |
8969a5ed | 15 | #include <linux/cpu.h> |
c6f4459f | 16 | #include <linux/sched.h> |
3d442233 | 17 | |
3bb5d2ee SS |
18 | #include "smpboot.h" |
19 | ||
3d442233 | 20 | enum { |
6e275637 | 21 | CSD_FLAG_LOCK = 0x01, |
8053871d | 22 | CSD_FLAG_SYNCHRONOUS = 0x02, |
3d442233 JA |
23 | }; |
24 | ||
25 | struct call_function_data { | |
9a46ad6d | 26 | struct call_single_data __percpu *csd; |
0b13fda1 | 27 | cpumask_var_t cpumask; |
3d442233 JA |
28 | }; |
29 | ||
e03bcb68 MM |
30 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data); |
31 | ||
6897fc22 | 32 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue); |
8969a5ed | 33 | |
8d056c48 SB |
34 | static void flush_smp_call_function_queue(bool warn_cpu_offline); |
35 | ||
31487f83 | 36 | int smpcfd_prepare_cpu(unsigned int cpu) |
8969a5ed | 37 | { |
8969a5ed PZ |
38 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); |
39 | ||
31487f83 RW |
40 | if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, |
41 | cpu_to_node(cpu))) | |
42 | return -ENOMEM; | |
43 | cfd->csd = alloc_percpu(struct call_single_data); | |
44 | if (!cfd->csd) { | |
8969a5ed | 45 | free_cpumask_var(cfd->cpumask); |
31487f83 RW |
46 | return -ENOMEM; |
47 | } | |
48 | ||
49 | return 0; | |
8969a5ed PZ |
50 | } |
51 | ||
31487f83 RW |
52 | int smpcfd_dead_cpu(unsigned int cpu) |
53 | { | |
54 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); | |
55 | ||
56 | free_cpumask_var(cfd->cpumask); | |
57 | free_percpu(cfd->csd); | |
58 | return 0; | |
59 | } | |
60 | ||
61 | int smpcfd_dying_cpu(unsigned int cpu) | |
62 | { | |
63 | /* | |
64 | * The IPIs for the smp-call-function callbacks queued by other | |
65 | * CPUs might arrive late, either due to hardware latencies or | |
66 | * because this CPU disabled interrupts (inside stop-machine) | |
67 | * before the IPIs were sent. So flush out any pending callbacks | |
68 | * explicitly (without waiting for the IPIs to arrive), to | |
69 | * ensure that the outgoing CPU doesn't go offline with work | |
70 | * still pending. | |
71 | */ | |
72 | flush_smp_call_function_queue(false); | |
73 | return 0; | |
74 | } | |
8969a5ed | 75 | |
d8ad7d11 | 76 | void __init call_function_init(void) |
3d442233 JA |
77 | { |
78 | int i; | |
79 | ||
6897fc22 CH |
80 | for_each_possible_cpu(i) |
81 | init_llist_head(&per_cpu(call_single_queue, i)); | |
8969a5ed | 82 | |
31487f83 | 83 | smpcfd_prepare_cpu(smp_processor_id()); |
3d442233 JA |
84 | } |
85 | ||
8969a5ed PZ |
86 | /* |
87 | * csd_lock/csd_unlock used to serialize access to per-cpu csd resources | |
88 | * | |
0b13fda1 IM |
89 | * For non-synchronous ipi calls the csd can still be in use by the |
90 | * previous function call. For multi-cpu calls its even more interesting | |
91 | * as we'll have to ensure no other cpu is observing our csd. | |
8969a5ed | 92 | */ |
90d10984 | 93 | static __always_inline void csd_lock_wait(struct call_single_data *csd) |
8969a5ed | 94 | { |
1f03e8d2 | 95 | smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK)); |
6e275637 PZ |
96 | } |
97 | ||
90d10984 | 98 | static __always_inline void csd_lock(struct call_single_data *csd) |
6e275637 | 99 | { |
e1d12f32 AM |
100 | csd_lock_wait(csd); |
101 | csd->flags |= CSD_FLAG_LOCK; | |
8969a5ed PZ |
102 | |
103 | /* | |
0b13fda1 IM |
104 | * prevent CPU from reordering the above assignment |
105 | * to ->flags with any subsequent assignments to other | |
106 | * fields of the specified call_single_data structure: | |
8969a5ed | 107 | */ |
8053871d | 108 | smp_wmb(); |
8969a5ed PZ |
109 | } |
110 | ||
90d10984 | 111 | static __always_inline void csd_unlock(struct call_single_data *csd) |
8969a5ed | 112 | { |
8053871d | 113 | WARN_ON(!(csd->flags & CSD_FLAG_LOCK)); |
0b13fda1 | 114 | |
8969a5ed | 115 | /* |
0b13fda1 | 116 | * ensure we're all done before releasing data: |
8969a5ed | 117 | */ |
8053871d | 118 | smp_store_release(&csd->flags, 0); |
3d442233 JA |
119 | } |
120 | ||
8b28499a FW |
121 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data); |
122 | ||
3d442233 | 123 | /* |
0b13fda1 IM |
124 | * Insert a previously allocated call_single_data element |
125 | * for execution on the given CPU. data must already have | |
126 | * ->func, ->info, and ->flags set. | |
3d442233 | 127 | */ |
8b28499a | 128 | static int generic_exec_single(int cpu, struct call_single_data *csd, |
8053871d | 129 | smp_call_func_t func, void *info) |
3d442233 | 130 | { |
8b28499a | 131 | if (cpu == smp_processor_id()) { |
8053871d LT |
132 | unsigned long flags; |
133 | ||
134 | /* | |
135 | * We can unlock early even for the synchronous on-stack case, | |
136 | * since we're doing this from the same CPU.. | |
137 | */ | |
138 | csd_unlock(csd); | |
8b28499a FW |
139 | local_irq_save(flags); |
140 | func(info); | |
141 | local_irq_restore(flags); | |
142 | return 0; | |
143 | } | |
144 | ||
145 | ||
5224b961 LT |
146 | if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) { |
147 | csd_unlock(csd); | |
8b28499a | 148 | return -ENXIO; |
5224b961 | 149 | } |
8b28499a | 150 | |
8b28499a FW |
151 | csd->func = func; |
152 | csd->info = info; | |
153 | ||
561920a0 | 154 | /* |
15d0d3b3 NP |
155 | * The list addition should be visible before sending the IPI |
156 | * handler locks the list to pull the entry off it because of | |
157 | * normal cache coherency rules implied by spinlocks. | |
158 | * | |
159 | * If IPIs can go out of order to the cache coherency protocol | |
160 | * in an architecture, sufficient synchronisation should be added | |
161 | * to arch code to make it appear to obey cache coherency WRT | |
0b13fda1 IM |
162 | * locking and barrier primitives. Generic code isn't really |
163 | * equipped to do the right thing... | |
561920a0 | 164 | */ |
6897fc22 | 165 | if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) |
3d442233 JA |
166 | arch_send_call_function_single_ipi(cpu); |
167 | ||
8b28499a | 168 | return 0; |
3d442233 JA |
169 | } |
170 | ||
8d056c48 SB |
171 | /** |
172 | * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks | |
173 | * | |
174 | * Invoked by arch to handle an IPI for call function single. | |
175 | * Must be called with interrupts disabled. | |
3d442233 JA |
176 | */ |
177 | void generic_smp_call_function_single_interrupt(void) | |
178 | { | |
8d056c48 SB |
179 | flush_smp_call_function_queue(true); |
180 | } | |
181 | ||
182 | /** | |
183 | * flush_smp_call_function_queue - Flush pending smp-call-function callbacks | |
184 | * | |
185 | * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an | |
186 | * offline CPU. Skip this check if set to 'false'. | |
187 | * | |
188 | * Flush any pending smp-call-function callbacks queued on this CPU. This is | |
189 | * invoked by the generic IPI handler, as well as by a CPU about to go offline, | |
190 | * to ensure that all pending IPI callbacks are run before it goes completely | |
191 | * offline. | |
192 | * | |
193 | * Loop through the call_single_queue and run all the queued callbacks. | |
194 | * Must be called with interrupts disabled. | |
195 | */ | |
196 | static void flush_smp_call_function_queue(bool warn_cpu_offline) | |
197 | { | |
198 | struct llist_head *head; | |
5fd77595 JK |
199 | struct llist_node *entry; |
200 | struct call_single_data *csd, *csd_next; | |
a219ccf4 SB |
201 | static bool warned; |
202 | ||
8d056c48 SB |
203 | WARN_ON(!irqs_disabled()); |
204 | ||
bb964a92 | 205 | head = this_cpu_ptr(&call_single_queue); |
8d056c48 | 206 | entry = llist_del_all(head); |
a219ccf4 | 207 | entry = llist_reverse_order(entry); |
3d442233 | 208 | |
8d056c48 SB |
209 | /* There shouldn't be any pending callbacks on an offline CPU. */ |
210 | if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) && | |
211 | !warned && !llist_empty(head))) { | |
a219ccf4 SB |
212 | warned = true; |
213 | WARN(1, "IPI on offline CPU %d\n", smp_processor_id()); | |
214 | ||
215 | /* | |
216 | * We don't have to use the _safe() variant here | |
217 | * because we are not invoking the IPI handlers yet. | |
218 | */ | |
219 | llist_for_each_entry(csd, entry, llist) | |
220 | pr_warn("IPI callback %pS sent to offline CPU\n", | |
221 | csd->func); | |
222 | } | |
3d442233 | 223 | |
5fd77595 | 224 | llist_for_each_entry_safe(csd, csd_next, entry, llist) { |
8053871d LT |
225 | smp_call_func_t func = csd->func; |
226 | void *info = csd->info; | |
227 | ||
228 | /* Do we wait until *after* callback? */ | |
229 | if (csd->flags & CSD_FLAG_SYNCHRONOUS) { | |
230 | func(info); | |
231 | csd_unlock(csd); | |
232 | } else { | |
233 | csd_unlock(csd); | |
234 | func(info); | |
235 | } | |
3d442233 | 236 | } |
47885016 FW |
237 | |
238 | /* | |
239 | * Handle irq works queued remotely by irq_work_queue_on(). | |
240 | * Smp functions above are typically synchronous so they | |
241 | * better run first since some other CPUs may be busy waiting | |
242 | * for them. | |
243 | */ | |
244 | irq_work_run(); | |
3d442233 JA |
245 | } |
246 | ||
247 | /* | |
248 | * smp_call_function_single - Run a function on a specific CPU | |
249 | * @func: The function to run. This must be fast and non-blocking. | |
250 | * @info: An arbitrary pointer to pass to the function. | |
3d442233 JA |
251 | * @wait: If true, wait until function has completed on other CPUs. |
252 | * | |
72f279b2 | 253 | * Returns 0 on success, else a negative status code. |
3d442233 | 254 | */ |
3a5f65df | 255 | int smp_call_function_single(int cpu, smp_call_func_t func, void *info, |
8691e5a8 | 256 | int wait) |
3d442233 | 257 | { |
8053871d LT |
258 | struct call_single_data *csd; |
259 | struct call_single_data csd_stack = { .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS }; | |
0b13fda1 | 260 | int this_cpu; |
8b28499a | 261 | int err; |
3d442233 | 262 | |
0b13fda1 IM |
263 | /* |
264 | * prevent preemption and reschedule on another processor, | |
265 | * as well as CPU removal | |
266 | */ | |
267 | this_cpu = get_cpu(); | |
268 | ||
269c861b SS |
269 | /* |
270 | * Can deadlock when called with interrupts disabled. | |
271 | * We allow cpu's that are not yet online though, as no one else can | |
272 | * send smp call function interrupt to this cpu and as such deadlocks | |
273 | * can't happen. | |
274 | */ | |
275 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() | |
276 | && !oops_in_progress); | |
3d442233 | 277 | |
8053871d LT |
278 | csd = &csd_stack; |
279 | if (!wait) { | |
280 | csd = this_cpu_ptr(&csd_data); | |
281 | csd_lock(csd); | |
282 | } | |
283 | ||
284 | err = generic_exec_single(cpu, csd, func, info); | |
285 | ||
286 | if (wait) | |
287 | csd_lock_wait(csd); | |
3d442233 JA |
288 | |
289 | put_cpu(); | |
0b13fda1 | 290 | |
f73be6de | 291 | return err; |
3d442233 JA |
292 | } |
293 | EXPORT_SYMBOL(smp_call_function_single); | |
294 | ||
d7877c03 | 295 | /** |
c46fff2a FW |
296 | * smp_call_function_single_async(): Run an asynchronous function on a |
297 | * specific CPU. | |
d7877c03 FW |
298 | * @cpu: The CPU to run on. |
299 | * @csd: Pre-allocated and setup data structure | |
d7877c03 | 300 | * |
c46fff2a FW |
301 | * Like smp_call_function_single(), but the call is asynchonous and |
302 | * can thus be done from contexts with disabled interrupts. | |
303 | * | |
304 | * The caller passes his own pre-allocated data structure | |
305 | * (ie: embedded in an object) and is responsible for synchronizing it | |
306 | * such that the IPIs performed on the @csd are strictly serialized. | |
307 | * | |
308 | * NOTE: Be careful, there is unfortunately no current debugging facility to | |
309 | * validate the correctness of this serialization. | |
d7877c03 | 310 | */ |
c46fff2a | 311 | int smp_call_function_single_async(int cpu, struct call_single_data *csd) |
d7877c03 FW |
312 | { |
313 | int err = 0; | |
d7877c03 | 314 | |
fce8ad15 | 315 | preempt_disable(); |
8053871d LT |
316 | |
317 | /* We could deadlock if we have to wait here with interrupts disabled! */ | |
318 | if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK)) | |
319 | csd_lock_wait(csd); | |
320 | ||
321 | csd->flags = CSD_FLAG_LOCK; | |
322 | smp_wmb(); | |
323 | ||
324 | err = generic_exec_single(cpu, csd, csd->func, csd->info); | |
fce8ad15 | 325 | preempt_enable(); |
d7877c03 FW |
326 | |
327 | return err; | |
328 | } | |
c46fff2a | 329 | EXPORT_SYMBOL_GPL(smp_call_function_single_async); |
d7877c03 | 330 | |
2ea6dec4 RR |
331 | /* |
332 | * smp_call_function_any - Run a function on any of the given cpus | |
333 | * @mask: The mask of cpus it can run on. | |
334 | * @func: The function to run. This must be fast and non-blocking. | |
335 | * @info: An arbitrary pointer to pass to the function. | |
336 | * @wait: If true, wait until function has completed. | |
337 | * | |
338 | * Returns 0 on success, else a negative status code (if no cpus were online). | |
2ea6dec4 RR |
339 | * |
340 | * Selection preference: | |
341 | * 1) current cpu if in @mask | |
342 | * 2) any cpu of current node if in @mask | |
343 | * 3) any other online cpu in @mask | |
344 | */ | |
345 | int smp_call_function_any(const struct cpumask *mask, | |
3a5f65df | 346 | smp_call_func_t func, void *info, int wait) |
2ea6dec4 RR |
347 | { |
348 | unsigned int cpu; | |
349 | const struct cpumask *nodemask; | |
350 | int ret; | |
351 | ||
352 | /* Try for same CPU (cheapest) */ | |
353 | cpu = get_cpu(); | |
354 | if (cpumask_test_cpu(cpu, mask)) | |
355 | goto call; | |
356 | ||
357 | /* Try for same node. */ | |
af2422c4 | 358 | nodemask = cpumask_of_node(cpu_to_node(cpu)); |
2ea6dec4 RR |
359 | for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids; |
360 | cpu = cpumask_next_and(cpu, nodemask, mask)) { | |
361 | if (cpu_online(cpu)) | |
362 | goto call; | |
363 | } | |
364 | ||
365 | /* Any online will do: smp_call_function_single handles nr_cpu_ids. */ | |
366 | cpu = cpumask_any_and(mask, cpu_online_mask); | |
367 | call: | |
368 | ret = smp_call_function_single(cpu, func, info, wait); | |
369 | put_cpu(); | |
370 | return ret; | |
371 | } | |
372 | EXPORT_SYMBOL_GPL(smp_call_function_any); | |
373 | ||
3d442233 | 374 | /** |
54b11e6d RR |
375 | * smp_call_function_many(): Run a function on a set of other CPUs. |
376 | * @mask: The set of cpus to run on (only runs on online subset). | |
3d442233 JA |
377 | * @func: The function to run. This must be fast and non-blocking. |
378 | * @info: An arbitrary pointer to pass to the function. | |
0b13fda1 IM |
379 | * @wait: If true, wait (atomically) until function has completed |
380 | * on other CPUs. | |
3d442233 | 381 | * |
72f279b2 | 382 | * If @wait is true, then returns once @func has returned. |
3d442233 JA |
383 | * |
384 | * You must not call this function with disabled interrupts or from a | |
385 | * hardware interrupt handler or from a bottom half handler. Preemption | |
386 | * must be disabled when calling this function. | |
387 | */ | |
54b11e6d | 388 | void smp_call_function_many(const struct cpumask *mask, |
3a5f65df | 389 | smp_call_func_t func, void *info, bool wait) |
3d442233 | 390 | { |
e1d12f32 | 391 | struct call_function_data *cfd; |
9a46ad6d | 392 | int cpu, next_cpu, this_cpu = smp_processor_id(); |
3d442233 | 393 | |
269c861b SS |
394 | /* |
395 | * Can deadlock when called with interrupts disabled. | |
396 | * We allow cpu's that are not yet online though, as no one else can | |
397 | * send smp call function interrupt to this cpu and as such deadlocks | |
398 | * can't happen. | |
399 | */ | |
400 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() | |
bd924e8c | 401 | && !oops_in_progress && !early_boot_irqs_disabled); |
3d442233 | 402 | |
723aae25 | 403 | /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */ |
54b11e6d | 404 | cpu = cpumask_first_and(mask, cpu_online_mask); |
0b13fda1 | 405 | if (cpu == this_cpu) |
54b11e6d | 406 | cpu = cpumask_next_and(cpu, mask, cpu_online_mask); |
0b13fda1 | 407 | |
54b11e6d RR |
408 | /* No online cpus? We're done. */ |
409 | if (cpu >= nr_cpu_ids) | |
410 | return; | |
411 | ||
412 | /* Do we have another CPU which isn't us? */ | |
413 | next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); | |
0b13fda1 | 414 | if (next_cpu == this_cpu) |
54b11e6d RR |
415 | next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); |
416 | ||
417 | /* Fastpath: do that cpu by itself. */ | |
418 | if (next_cpu >= nr_cpu_ids) { | |
419 | smp_call_function_single(cpu, func, info, wait); | |
420 | return; | |
3d442233 JA |
421 | } |
422 | ||
bb964a92 | 423 | cfd = this_cpu_ptr(&cfd_data); |
45a57919 | 424 | |
e1d12f32 AM |
425 | cpumask_and(cfd->cpumask, mask, cpu_online_mask); |
426 | cpumask_clear_cpu(this_cpu, cfd->cpumask); | |
723aae25 MM |
427 | |
428 | /* Some callers race with other cpus changing the passed mask */ | |
e1d12f32 | 429 | if (unlikely(!cpumask_weight(cfd->cpumask))) |
723aae25 | 430 | return; |
3d442233 | 431 | |
e1d12f32 AM |
432 | for_each_cpu(cpu, cfd->cpumask) { |
433 | struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu); | |
9a46ad6d SL |
434 | |
435 | csd_lock(csd); | |
8053871d LT |
436 | if (wait) |
437 | csd->flags |= CSD_FLAG_SYNCHRONOUS; | |
9a46ad6d SL |
438 | csd->func = func; |
439 | csd->info = info; | |
6897fc22 | 440 | llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)); |
9a46ad6d | 441 | } |
561920a0 | 442 | |
3d442233 | 443 | /* Send a message to all CPUs in the map */ |
73f94550 | 444 | arch_send_call_function_ipi_mask(cfd->cpumask); |
3d442233 | 445 | |
9a46ad6d | 446 | if (wait) { |
e1d12f32 AM |
447 | for_each_cpu(cpu, cfd->cpumask) { |
448 | struct call_single_data *csd; | |
449 | ||
450 | csd = per_cpu_ptr(cfd->csd, cpu); | |
9a46ad6d SL |
451 | csd_lock_wait(csd); |
452 | } | |
453 | } | |
3d442233 | 454 | } |
54b11e6d | 455 | EXPORT_SYMBOL(smp_call_function_many); |
3d442233 JA |
456 | |
457 | /** | |
458 | * smp_call_function(): Run a function on all other CPUs. | |
459 | * @func: The function to run. This must be fast and non-blocking. | |
460 | * @info: An arbitrary pointer to pass to the function. | |
0b13fda1 IM |
461 | * @wait: If true, wait (atomically) until function has completed |
462 | * on other CPUs. | |
3d442233 | 463 | * |
54b11e6d | 464 | * Returns 0. |
3d442233 JA |
465 | * |
466 | * If @wait is true, then returns once @func has returned; otherwise | |
72f279b2 | 467 | * it returns just before the target cpu calls @func. |
3d442233 JA |
468 | * |
469 | * You must not call this function with disabled interrupts or from a | |
470 | * hardware interrupt handler or from a bottom half handler. | |
471 | */ | |
3a5f65df | 472 | int smp_call_function(smp_call_func_t func, void *info, int wait) |
3d442233 | 473 | { |
3d442233 | 474 | preempt_disable(); |
54b11e6d | 475 | smp_call_function_many(cpu_online_mask, func, info, wait); |
3d442233 | 476 | preempt_enable(); |
0b13fda1 | 477 | |
54b11e6d | 478 | return 0; |
3d442233 JA |
479 | } |
480 | EXPORT_SYMBOL(smp_call_function); | |
351f8f8e | 481 | |
34db18a0 AW |
482 | /* Setup configured maximum number of CPUs to activate */ |
483 | unsigned int setup_max_cpus = NR_CPUS; | |
484 | EXPORT_SYMBOL(setup_max_cpus); | |
485 | ||
486 | ||
487 | /* | |
488 | * Setup routine for controlling SMP activation | |
489 | * | |
490 | * Command-line option of "nosmp" or "maxcpus=0" will disable SMP | |
491 | * activation entirely (the MPS table probe still happens, though). | |
492 | * | |
493 | * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer | |
494 | * greater than 0, limits the maximum number of CPUs activated in | |
495 | * SMP mode to <NUM>. | |
496 | */ | |
497 | ||
498 | void __weak arch_disable_smp_support(void) { } | |
499 | ||
500 | static int __init nosmp(char *str) | |
501 | { | |
502 | setup_max_cpus = 0; | |
503 | arch_disable_smp_support(); | |
504 | ||
505 | return 0; | |
506 | } | |
507 | ||
508 | early_param("nosmp", nosmp); | |
509 | ||
510 | /* this is hard limit */ | |
511 | static int __init nrcpus(char *str) | |
512 | { | |
513 | int nr_cpus; | |
514 | ||
515 | get_option(&str, &nr_cpus); | |
516 | if (nr_cpus > 0 && nr_cpus < nr_cpu_ids) | |
517 | nr_cpu_ids = nr_cpus; | |
518 | ||
519 | return 0; | |
520 | } | |
521 | ||
522 | early_param("nr_cpus", nrcpus); | |
523 | ||
524 | static int __init maxcpus(char *str) | |
525 | { | |
526 | get_option(&str, &setup_max_cpus); | |
527 | if (setup_max_cpus == 0) | |
528 | arch_disable_smp_support(); | |
529 | ||
530 | return 0; | |
531 | } | |
532 | ||
533 | early_param("maxcpus", maxcpus); | |
534 | ||
535 | /* Setup number of possible processor ids */ | |
536 | int nr_cpu_ids __read_mostly = NR_CPUS; | |
537 | EXPORT_SYMBOL(nr_cpu_ids); | |
538 | ||
539 | /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */ | |
540 | void __init setup_nr_cpu_ids(void) | |
541 | { | |
542 | nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1; | |
543 | } | |
544 | ||
a17bce4d BP |
545 | void __weak smp_announce(void) |
546 | { | |
547 | printk(KERN_INFO "Brought up %d CPUs\n", num_online_cpus()); | |
548 | } | |
549 | ||
34db18a0 AW |
550 | /* Called by boot processor to activate the rest. */ |
551 | void __init smp_init(void) | |
552 | { | |
553 | unsigned int cpu; | |
554 | ||
3bb5d2ee | 555 | idle_threads_init(); |
4cb28ced | 556 | cpuhp_threads_init(); |
3bb5d2ee | 557 | |
34db18a0 AW |
558 | /* FIXME: This should be done in userspace --RR */ |
559 | for_each_present_cpu(cpu) { | |
560 | if (num_online_cpus() >= setup_max_cpus) | |
561 | break; | |
562 | if (!cpu_online(cpu)) | |
563 | cpu_up(cpu); | |
564 | } | |
565 | ||
566 | /* Any cleanup work */ | |
a17bce4d | 567 | smp_announce(); |
34db18a0 AW |
568 | smp_cpus_done(setup_max_cpus); |
569 | } | |
570 | ||
351f8f8e | 571 | /* |
bd924e8c TH |
572 | * Call a function on all processors. May be used during early boot while |
573 | * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead | |
574 | * of local_irq_disable/enable(). | |
351f8f8e AW |
575 | */ |
576 | int on_each_cpu(void (*func) (void *info), void *info, int wait) | |
577 | { | |
bd924e8c | 578 | unsigned long flags; |
351f8f8e AW |
579 | int ret = 0; |
580 | ||
581 | preempt_disable(); | |
582 | ret = smp_call_function(func, info, wait); | |
bd924e8c | 583 | local_irq_save(flags); |
351f8f8e | 584 | func(info); |
bd924e8c | 585 | local_irq_restore(flags); |
351f8f8e AW |
586 | preempt_enable(); |
587 | return ret; | |
588 | } | |
589 | EXPORT_SYMBOL(on_each_cpu); | |
3fc498f1 GBY |
590 | |
591 | /** | |
592 | * on_each_cpu_mask(): Run a function on processors specified by | |
593 | * cpumask, which may include the local processor. | |
594 | * @mask: The set of cpus to run on (only runs on online subset). | |
595 | * @func: The function to run. This must be fast and non-blocking. | |
596 | * @info: An arbitrary pointer to pass to the function. | |
597 | * @wait: If true, wait (atomically) until function has completed | |
598 | * on other CPUs. | |
599 | * | |
600 | * If @wait is true, then returns once @func has returned. | |
601 | * | |
202da400 DD |
602 | * You must not call this function with disabled interrupts or from a |
603 | * hardware interrupt handler or from a bottom half handler. The | |
604 | * exception is that it may be used during early boot while | |
605 | * early_boot_irqs_disabled is set. | |
3fc498f1 GBY |
606 | */ |
607 | void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func, | |
608 | void *info, bool wait) | |
609 | { | |
610 | int cpu = get_cpu(); | |
611 | ||
612 | smp_call_function_many(mask, func, info, wait); | |
613 | if (cpumask_test_cpu(cpu, mask)) { | |
202da400 DD |
614 | unsigned long flags; |
615 | local_irq_save(flags); | |
3fc498f1 | 616 | func(info); |
202da400 | 617 | local_irq_restore(flags); |
3fc498f1 GBY |
618 | } |
619 | put_cpu(); | |
620 | } | |
621 | EXPORT_SYMBOL(on_each_cpu_mask); | |
b3a7e98e GBY |
622 | |
623 | /* | |
624 | * on_each_cpu_cond(): Call a function on each processor for which | |
625 | * the supplied function cond_func returns true, optionally waiting | |
626 | * for all the required CPUs to finish. This may include the local | |
627 | * processor. | |
628 | * @cond_func: A callback function that is passed a cpu id and | |
629 | * the the info parameter. The function is called | |
630 | * with preemption disabled. The function should | |
631 | * return a blooean value indicating whether to IPI | |
632 | * the specified CPU. | |
633 | * @func: The function to run on all applicable CPUs. | |
634 | * This must be fast and non-blocking. | |
635 | * @info: An arbitrary pointer to pass to both functions. | |
636 | * @wait: If true, wait (atomically) until function has | |
637 | * completed on other CPUs. | |
638 | * @gfp_flags: GFP flags to use when allocating the cpumask | |
639 | * used internally by the function. | |
640 | * | |
641 | * The function might sleep if the GFP flags indicates a non | |
642 | * atomic allocation is allowed. | |
643 | * | |
644 | * Preemption is disabled to protect against CPUs going offline but not online. | |
645 | * CPUs going online during the call will not be seen or sent an IPI. | |
646 | * | |
647 | * You must not call this function with disabled interrupts or | |
648 | * from a hardware interrupt handler or from a bottom half handler. | |
649 | */ | |
650 | void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info), | |
651 | smp_call_func_t func, void *info, bool wait, | |
652 | gfp_t gfp_flags) | |
653 | { | |
654 | cpumask_var_t cpus; | |
655 | int cpu, ret; | |
656 | ||
d0164adc | 657 | might_sleep_if(gfpflags_allow_blocking(gfp_flags)); |
b3a7e98e GBY |
658 | |
659 | if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) { | |
660 | preempt_disable(); | |
661 | for_each_online_cpu(cpu) | |
662 | if (cond_func(cpu, info)) | |
663 | cpumask_set_cpu(cpu, cpus); | |
664 | on_each_cpu_mask(cpus, func, info, wait); | |
665 | preempt_enable(); | |
666 | free_cpumask_var(cpus); | |
667 | } else { | |
668 | /* | |
669 | * No free cpumask, bother. No matter, we'll | |
670 | * just have to IPI them one by one. | |
671 | */ | |
672 | preempt_disable(); | |
673 | for_each_online_cpu(cpu) | |
674 | if (cond_func(cpu, info)) { | |
675 | ret = smp_call_function_single(cpu, func, | |
676 | info, wait); | |
618fde87 | 677 | WARN_ON_ONCE(ret); |
b3a7e98e GBY |
678 | } |
679 | preempt_enable(); | |
680 | } | |
681 | } | |
682 | EXPORT_SYMBOL(on_each_cpu_cond); | |
f37f435f TG |
683 | |
684 | static void do_nothing(void *unused) | |
685 | { | |
686 | } | |
687 | ||
688 | /** | |
689 | * kick_all_cpus_sync - Force all cpus out of idle | |
690 | * | |
691 | * Used to synchronize the update of pm_idle function pointer. It's | |
692 | * called after the pointer is updated and returns after the dummy | |
693 | * callback function has been executed on all cpus. The execution of | |
694 | * the function can only happen on the remote cpus after they have | |
695 | * left the idle function which had been called via pm_idle function | |
696 | * pointer. So it's guaranteed that nothing uses the previous pointer | |
697 | * anymore. | |
698 | */ | |
699 | void kick_all_cpus_sync(void) | |
700 | { | |
701 | /* Make sure the change is visible before we kick the cpus */ | |
702 | smp_mb(); | |
703 | smp_call_function(do_nothing, NULL, 1); | |
704 | } | |
705 | EXPORT_SYMBOL_GPL(kick_all_cpus_sync); | |
c6f4459f CL |
706 | |
707 | /** | |
708 | * wake_up_all_idle_cpus - break all cpus out of idle | |
709 | * wake_up_all_idle_cpus try to break all cpus which is in idle state even | |
710 | * including idle polling cpus, for non-idle cpus, we will do nothing | |
711 | * for them. | |
712 | */ | |
713 | void wake_up_all_idle_cpus(void) | |
714 | { | |
715 | int cpu; | |
716 | ||
717 | preempt_disable(); | |
718 | for_each_online_cpu(cpu) { | |
719 | if (cpu == smp_processor_id()) | |
720 | continue; | |
721 | ||
722 | wake_up_if_idle(cpu); | |
723 | } | |
724 | preempt_enable(); | |
725 | } | |
726 | EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus); |