| 1 | |
| 2 | * Generic helpers for smp ipi calls
|
| 3 | *
|
| 4 | * (C) Jens Axboe <[email protected]> 2008
|
| 5 |
|
| 6 | #include <linux/rcupdate.h>
|
| 7 | #include <linux/rculist.h>
|
| 8 | #include <linux/kernel.h>
|
| 9 | #include <linux/export.h>
|
| 10 | #include <linux/percpu.h>
|
| 11 | #include <linux/init.h>
|
| 12 | #include <linux/gfp.h>
|
| 13 | #include <linux/smp.h>
|
| 14 | #include <linux/cpu.h>
|
| 15 |
|
| 16 | #include "smpboot.h"
|
| 17 |
|
| 18 | #ifdef CONFIG_USE_GENERIC_SMP_HELPERS
|
| 19 | static struct {
|
| 20 | struct list_head queue;
|
| 21 | raw_spinlock_t lock;
|
| 22 | } call_function __cacheline_aligned_in_smp =
|
| 23 | {
|
| 24 | .queue = LIST_HEAD_INIT(call_function.queue),
|
| 25 | .lock = __RAW_SPIN_LOCK_UNLOCKED(call_function.lock),
|
| 26 | };
|
| 27 |
|
| 28 | enum {
|
| 29 | CSD_FLAG_LOCK = 0x01,
|
| 30 | };
|
| 31 |
|
| 32 | struct call_function_data {
|
| 33 | struct call_single_data csd;
|
| 34 | atomic_t refs;
|
| 35 | cpumask_var_t cpumask;
|
| 36 | };
|
| 37 |
|
| 38 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data);
|
| 39 |
|
| 40 | struct call_single_queue {
|
| 41 | struct list_head list;
|
| 42 | raw_spinlock_t lock;
|
| 43 | };
|
| 44 |
|
| 45 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_queue, call_single_queue);
|
| 46 |
|
| 47 | static int
|
| 48 | hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
|
| 49 | {
|
| 50 | long cpu = (long)hcpu;
|
| 51 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
|
| 52 |
|
| 53 | switch (action) {
|
| 54 | case CPU_UP_PREPARE:
|
| 55 | case CPU_UP_PREPARE_FROZEN:
|
| 56 | if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
|
| 57 | cpu_to_node(cpu)))
|
| 58 | return notifier_from_errno(-ENOMEM);
|
| 59 | break;
|
| 60 |
|
| 61 | #ifdef CONFIG_HOTPLUG_CPU
|
| 62 | case CPU_UP_CANCELED:
|
| 63 | case CPU_UP_CANCELED_FROZEN:
|
| 64 |
|
| 65 | case CPU_DEAD:
|
| 66 | case CPU_DEAD_FROZEN:
|
| 67 | free_cpumask_var(cfd->cpumask);
|
| 68 | break;
|
| 69 | #endif
|
| 70 | };
|
| 71 |
|
| 72 | return NOTIFY_OK;
|
| 73 | }
|
| 74 |
|
| 75 | static struct notifier_block __cpuinitdata hotplug_cfd_notifier = {
|
| 76 | .notifier_call = hotplug_cfd,
|
| 77 | };
|
| 78 |
|
| 79 | void __init call_function_init(void)
|
| 80 | {
|
| 81 | void *cpu = (void *)(long)smp_processor_id();
|
| 82 | int i;
|
| 83 |
|
| 84 | for_each_possible_cpu(i) {
|
| 85 | struct call_single_queue *q = &per_cpu(call_single_queue, i);
|
| 86 |
|
| 87 | raw_spin_lock_init(&q->lock);
|
| 88 | INIT_LIST_HEAD(&q->list);
|
| 89 | }
|
| 90 |
|
| 91 | hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);
|
| 92 | register_cpu_notifier(&hotplug_cfd_notifier);
|
| 93 | }
|
| 94 |
|
| 95 | |
| 96 | * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
|
| 97 | *
|
| 98 | * For non-synchronous ipi calls the csd can still be in use by the
|
| 99 | * previous function call. For multi-cpu calls its even more interesting
|
| 100 | * as we'll have to ensure no other cpu is observing our csd.
|
| 101 |
|
| 102 | static void csd_lock_wait(struct call_single_data *data)
|
| 103 | {
|
| 104 | while (data->flags & CSD_FLAG_LOCK)
|
| 105 | cpu_relax();
|
| 106 | }
|
| 107 |
|
| 108 | static void csd_lock(struct call_single_data *data)
|
| 109 | {
|
| 110 | csd_lock_wait(data);
|
| 111 | data->flags = CSD_FLAG_LOCK;
|
| 112 |
|
| 113 | |
| 114 | * prevent CPU from reordering the above assignment
|
| 115 | * to ->flags with any subsequent assignments to other
|
| 116 | * fields of the specified call_single_data structure:
|
| 117 |
|
| 118 | smp_mb();
|
| 119 | }
|
| 120 |
|
| 121 | static void csd_unlock(struct call_single_data *data)
|
| 122 | {
|
| 123 | WARN_ON(!(data->flags & CSD_FLAG_LOCK));
|
| 124 |
|
| 125 | |
| 126 | * ensure we're all done before releasing data:
|
| 127 |
|
| 128 | smp_mb();
|
| 129 |
|
| 130 | data->flags &= ~CSD_FLAG_LOCK;
|
| 131 | }
|
| 132 |
|
| 133 | |
| 134 | * Insert a previously allocated call_single_data element
|
| 135 | * for execution on the given CPU. data must already have
|
| 136 | * ->func, ->info, and ->flags set.
|
| 137 |
|
| 138 | static
|
| 139 | void generic_exec_single(int cpu, struct call_single_data *data, int wait)
|
| 140 | {
|
| 141 | struct call_single_queue *dst = &per_cpu(call_single_queue, cpu);
|
| 142 | unsigned long flags;
|
| 143 | int ipi;
|
| 144 |
|
| 145 | raw_spin_lock_irqsave(&dst->lock, flags);
|
| 146 | ipi = list_empty(&dst->list);
|
| 147 | list_add_tail(&data->list, &dst->list);
|
| 148 | raw_spin_unlock_irqrestore(&dst->lock, flags);
|
| 149 |
|
| 150 | |
| 151 | * The list addition should be visible before sending the IPI
|
| 152 | * handler locks the list to pull the entry off it because of
|
| 153 | * normal cache coherency rules implied by spinlocks.
|
| 154 | *
|
| 155 | * If IPIs can go out of order to the cache coherency protocol
|
| 156 | * in an architecture, sufficient synchronisation should be added
|
| 157 | * to arch code to make it appear to obey cache coherency WRT
|
| 158 | * locking and barrier primitives. Generic code isn't really
|
| 159 | * equipped to do the right thing...
|
| 160 |
|
| 161 | if (ipi)
|
| 162 | arch_send_call_function_single_ipi(cpu);
|
| 163 |
|
| 164 | if (wait)
|
| 165 | csd_lock_wait(data);
|
| 166 | }
|
| 167 |
|
| 168 | |
| 169 | * Invoked by arch to handle an IPI for call function. Must be called with
|
| 170 | * interrupts disabled.
|
| 171 |
|
| 172 | void generic_smp_call_function_interrupt(void)
|
| 173 | {
|
| 174 | struct call_function_data *data;
|
| 175 | int cpu = smp_processor_id();
|
| 176 |
|
| 177 | |
| 178 | * Shouldn't receive this interrupt on a cpu that is not yet online.
|
| 179 |
|
| 180 | WARN_ON_ONCE(!cpu_online(cpu));
|
| 181 |
|
| 182 | |
| 183 | * Ensure entry is visible on call_function_queue after we have
|
| 184 | * entered the IPI. See comment in smp_call_function_many.
|
| 185 | * If we don't have this, then we may miss an entry on the list
|
| 186 | * and never get another IPI to process it.
|
| 187 |
|
| 188 | smp_mb();
|
| 189 |
|
| 190 | |
| 191 | * It's ok to use list_for_each_rcu() here even though we may
|
| 192 | * delete 'pos', since list_del_rcu() doesn't clear ->next
|
| 193 |
|
| 194 | list_for_each_entry_rcu(data, &call_function.queue, csd.list) {
|
| 195 | int refs;
|
| 196 | smp_call_func_t func;
|
| 197 |
|
| 198 | |
| 199 | * Since we walk the list without any locks, we might
|
| 200 | * see an entry that was completed, removed from the
|
| 201 | * list and is in the process of being reused.
|
| 202 | *
|
| 203 | * We must check that the cpu is in the cpumask before
|
| 204 | * checking the refs, and both must be set before
|
| 205 | * executing the callback on this cpu.
|
| 206 |
|
| 207 |
|
| 208 | if (!cpumask_test_cpu(cpu, data->cpumask))
|
| 209 | continue;
|
| 210 |
|
| 211 | smp_rmb();
|
| 212 |
|
| 213 | if (atomic_read(&data->refs) == 0)
|
| 214 | continue;
|
| 215 |
|
| 216 | func = data->csd.func;
|
| 217 | func(data->csd.info);
|
| 218 |
|
| 219 | |
| 220 | * If the cpu mask is not still set then func enabled
|
| 221 | * interrupts (BUG), and this cpu took another smp call
|
| 222 | * function interrupt and executed func(info) twice
|
| 223 | * on this cpu. That nested execution decremented refs.
|
| 224 |
|
| 225 | if (!cpumask_test_and_clear_cpu(cpu, data->cpumask)) {
|
| 226 | WARN(1, "%pf enabled interrupts and double executed\n", func);
|
| 227 | continue;
|
| 228 | }
|
| 229 |
|
| 230 | refs = atomic_dec_return(&data->refs);
|
| 231 | WARN_ON(refs < 0);
|
| 232 |
|
| 233 | if (refs)
|
| 234 | continue;
|
| 235 |
|
| 236 | WARN_ON(!cpumask_empty(data->cpumask));
|
| 237 |
|
| 238 | raw_spin_lock(&call_function.lock);
|
| 239 | list_del_rcu(&data->csd.list);
|
| 240 | raw_spin_unlock(&call_function.lock);
|
| 241 |
|
| 242 | csd_unlock(&data->csd);
|
| 243 | }
|
| 244 |
|
| 245 | }
|
| 246 |
|
| 247 | |
| 248 | * Invoked by arch to handle an IPI for call function single. Must be
|
| 249 | * called from the arch with interrupts disabled.
|
| 250 |
|
| 251 | void generic_smp_call_function_single_interrupt(void)
|
| 252 | {
|
| 253 | struct call_single_queue *q = &__get_cpu_var(call_single_queue);
|
| 254 | unsigned int data_flags;
|
| 255 | LIST_HEAD(list);
|
| 256 |
|
| 257 | |
| 258 | * Shouldn't receive this interrupt on a cpu that is not yet online.
|
| 259 |
|
| 260 | WARN_ON_ONCE(!cpu_online(smp_processor_id()));
|
| 261 |
|
| 262 | raw_spin_lock(&q->lock);
|
| 263 | list_replace_init(&q->list, &list);
|
| 264 | raw_spin_unlock(&q->lock);
|
| 265 |
|
| 266 | while (!list_empty(&list)) {
|
| 267 | struct call_single_data *data;
|
| 268 |
|
| 269 | data = list_entry(list.next, struct call_single_data, list);
|
| 270 | list_del(&data->list);
|
| 271 |
|
| 272 | |
| 273 | * 'data' can be invalid after this call if flags == 0
|
| 274 | * (when called through generic_exec_single()),
|
| 275 | * so save them away before making the call:
|
| 276 |
|
| 277 | data_flags = data->flags;
|
| 278 |
|
| 279 | data->func(data->info);
|
| 280 |
|
| 281 | |
| 282 | * Unlocked CSDs are valid through generic_exec_single():
|
| 283 |
|
| 284 | if (data_flags & CSD_FLAG_LOCK)
|
| 285 | csd_unlock(data);
|
| 286 | }
|
| 287 | }
|
| 288 |
|
| 289 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
|
| 290 |
|
| 291 | |
| 292 | * smp_call_function_single - Run a function on a specific CPU
|
| 293 | * @func: The function to run. This must be fast and non-blocking.
|
| 294 | * @info: An arbitrary pointer to pass to the function.
|
| 295 | * @wait: If true, wait until function has completed on other CPUs.
|
| 296 | *
|
| 297 | * Returns 0 on success, else a negative status code.
|
| 298 |
|
| 299 | int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
|
| 300 | int wait)
|
| 301 | {
|
| 302 | struct call_single_data d = {
|
| 303 | .flags = 0,
|
| 304 | };
|
| 305 | unsigned long flags;
|
| 306 | int this_cpu;
|
| 307 | int err = 0;
|
| 308 |
|
| 309 | |
| 310 | * prevent preemption and reschedule on another processor,
|
| 311 | * as well as CPU removal
|
| 312 |
|
| 313 | this_cpu = get_cpu();
|
| 314 |
|
| 315 | |
| 316 | * Can deadlock when called with interrupts disabled.
|
| 317 | * We allow cpu's that are not yet online though, as no one else can
|
| 318 | * send smp call function interrupt to this cpu and as such deadlocks
|
| 319 | * can't happen.
|
| 320 |
|
| 321 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
|
| 322 | && !oops_in_progress);
|
| 323 |
|
| 324 | if (cpu == this_cpu) {
|
| 325 | local_irq_save(flags);
|
| 326 | func(info);
|
| 327 | local_irq_restore(flags);
|
| 328 | } else {
|
| 329 | if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
|
| 330 | struct call_single_data *data = &d;
|
| 331 |
|
| 332 | if (!wait)
|
| 333 | data = &__get_cpu_var(csd_data);
|
| 334 |
|
| 335 | csd_lock(data);
|
| 336 |
|
| 337 | data->func = func;
|
| 338 | data->info = info;
|
| 339 | generic_exec_single(cpu, data, wait);
|
| 340 | } else {
|
| 341 | err = -ENXIO;
|
| 342 | }
|
| 343 | }
|
| 344 |
|
| 345 | put_cpu();
|
| 346 |
|
| 347 | return err;
|
| 348 | }
|
| 349 | EXPORT_SYMBOL(smp_call_function_single);
|
| 350 |
|
| 351 | |
| 352 | * smp_call_function_any - Run a function on any of the given cpus
|
| 353 | * @mask: The mask of cpus it can run on.
|
| 354 | * @func: The function to run. This must be fast and non-blocking.
|
| 355 | * @info: An arbitrary pointer to pass to the function.
|
| 356 | * @wait: If true, wait until function has completed.
|
| 357 | *
|
| 358 | * Returns 0 on success, else a negative status code (if no cpus were online).
|
| 359 | * Note that @wait will be implicitly turned on in case of allocation failures,
|
| 360 | * since we fall back to on-stack allocation.
|
| 361 | *
|
| 362 | * Selection preference:
|
| 363 | * 1) current cpu if in @mask
|
| 364 | * 2) any cpu of current node if in @mask
|
| 365 | * 3) any other online cpu in @mask
|
| 366 |
|
| 367 | int smp_call_function_any(const struct cpumask *mask,
|
| 368 | smp_call_func_t func, void *info, int wait)
|
| 369 | {
|
| 370 | unsigned int cpu;
|
| 371 | const struct cpumask *nodemask;
|
| 372 | int ret;
|
| 373 |
|
| 374 |
|
| 375 | cpu = get_cpu();
|
| 376 | if (cpumask_test_cpu(cpu, mask))
|
| 377 | goto call;
|
| 378 |
|
| 379 |
|
| 380 | nodemask = cpumask_of_node(cpu_to_node(cpu));
|
| 381 | for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
|
| 382 | cpu = cpumask_next_and(cpu, nodemask, mask)) {
|
| 383 | if (cpu_online(cpu))
|
| 384 | goto call;
|
| 385 | }
|
| 386 |
|
| 387 |
|
| 388 | cpu = cpumask_any_and(mask, cpu_online_mask);
|
| 389 | call:
|
| 390 | ret = smp_call_function_single(cpu, func, info, wait);
|
| 391 | put_cpu();
|
| 392 | return ret;
|
| 393 | }
|
| 394 | EXPORT_SYMBOL_GPL(smp_call_function_any);
|
| 395 |
|
| 396 | |
| 397 | * __smp_call_function_single(): Run a function on a specific CPU
|
| 398 | * @cpu: The CPU to run on.
|
| 399 | * @data: Pre-allocated and setup data structure
|
| 400 | * @wait: If true, wait until function has completed on specified CPU.
|
| 401 | *
|
| 402 | * Like smp_call_function_single(), but allow caller to pass in a
|
| 403 | * pre-allocated data structure. Useful for embedding @data inside
|
| 404 | * other structures, for instance.
|
| 405 |
|
| 406 | void __smp_call_function_single(int cpu, struct call_single_data *data,
|
| 407 | int wait)
|
| 408 | {
|
| 409 | unsigned int this_cpu;
|
| 410 | unsigned long flags;
|
| 411 |
|
| 412 | this_cpu = get_cpu();
|
| 413 | |
| 414 | * Can deadlock when called with interrupts disabled.
|
| 415 | * We allow cpu's that are not yet online though, as no one else can
|
| 416 | * send smp call function interrupt to this cpu and as such deadlocks
|
| 417 | * can't happen.
|
| 418 |
|
| 419 | WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled()
|
| 420 | && !oops_in_progress);
|
| 421 |
|
| 422 | if (cpu == this_cpu) {
|
| 423 | local_irq_save(flags);
|
| 424 | data->func(data->info);
|
| 425 | local_irq_restore(flags);
|
| 426 | } else {
|
| 427 | csd_lock(data);
|
| 428 | generic_exec_single(cpu, data, wait);
|
| 429 | }
|
| 430 | put_cpu();
|
| 431 | }
|
| 432 |
|
| 433 | |
| 434 | * smp_call_function_many(): Run a function on a set of other CPUs.
|
| 435 | * @mask: The set of cpus to run on (only runs on online subset).
|
| 436 | * @func: The function to run. This must be fast and non-blocking.
|
| 437 | * @info: An arbitrary pointer to pass to the function.
|
| 438 | * @wait: If true, wait (atomically) until function has completed
|
| 439 | * on other CPUs.
|
| 440 | *
|
| 441 | * If @wait is true, then returns once @func has returned.
|
| 442 | *
|
| 443 | * You must not call this function with disabled interrupts or from a
|
| 444 | * hardware interrupt handler or from a bottom half handler. Preemption
|
| 445 | * must be disabled when calling this function.
|
| 446 |
|
| 447 | void smp_call_function_many(const struct cpumask *mask,
|
| 448 | smp_call_func_t func, void *info, bool wait)
|
| 449 | {
|
| 450 | struct call_function_data *data;
|
| 451 | unsigned long flags;
|
| 452 | int refs, cpu, next_cpu, this_cpu = smp_processor_id();
|
| 453 |
|
| 454 | |
| 455 | * Can deadlock when called with interrupts disabled.
|
| 456 | * We allow cpu's that are not yet online though, as no one else can
|
| 457 | * send smp call function interrupt to this cpu and as such deadlocks
|
| 458 | * can't happen.
|
| 459 |
|
| 460 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
|
| 461 | && !oops_in_progress && !early_boot_irqs_disabled);
|
| 462 |
|
| 463 |
|
| 464 | cpu = cpumask_first_and(mask, cpu_online_mask);
|
| 465 | if (cpu == this_cpu)
|
| 466 | cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
|
| 467 |
|
| 468 |
|
| 469 | if (cpu >= nr_cpu_ids)
|
| 470 | return;
|
| 471 |
|
| 472 |
|
| 473 | next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
|
| 474 | if (next_cpu == this_cpu)
|
| 475 | next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
|
| 476 |
|
| 477 |
|
| 478 | if (next_cpu >= nr_cpu_ids) {
|
| 479 | smp_call_function_single(cpu, func, info, wait);
|
| 480 | return;
|
| 481 | }
|
| 482 |
|
| 483 | data = &__get_cpu_var(cfd_data);
|
| 484 | csd_lock(&data->csd);
|
| 485 |
|
| 486 |
|
| 487 | BUG_ON(atomic_read(&data->refs) || !cpumask_empty(data->cpumask));
|
| 488 |
|
| 489 | |
| 490 | * The global call function queue list add and delete are protected
|
| 491 | * by a lock, but the list is traversed without any lock, relying
|
| 492 | * on the rcu list add and delete to allow safe concurrent traversal.
|
| 493 | * We reuse the call function data without waiting for any grace
|
| 494 | * period after some other cpu removes it from the global queue.
|
| 495 | * This means a cpu might find our data block as it is being
|
| 496 | * filled out.
|
| 497 | *
|
| 498 | * We hold off the interrupt handler on the other cpu by
|
| 499 | * ordering our writes to the cpu mask vs our setting of the
|
| 500 | * refs counter. We assert only the cpu owning the data block
|
| 501 | * will set a bit in cpumask, and each bit will only be cleared
|
| 502 | * by the subject cpu. Each cpu must first find its bit is
|
| 503 | * set and then check that refs is set indicating the element is
|
| 504 | * ready to be processed, otherwise it must skip the entry.
|
| 505 | *
|
| 506 | * On the previous iteration refs was set to 0 by another cpu.
|
| 507 | * To avoid the use of transitivity, set the counter to 0 here
|
| 508 | * so the wmb will pair with the rmb in the interrupt handler.
|
| 509 |
|
| 510 | atomic_set(&data->refs, 0);
|
| 511 |
|
| 512 | data->csd.func = func;
|
| 513 | data->csd.info = info;
|
| 514 |
|
| 515 |
|
| 516 | smp_wmb();
|
| 517 |
|
| 518 |
|
| 519 | cpumask_and(data->cpumask, mask, cpu_online_mask);
|
| 520 | cpumask_clear_cpu(this_cpu, data->cpumask);
|
| 521 | refs = cpumask_weight(data->cpumask);
|
| 522 |
|
| 523 |
|
| 524 | if (unlikely(!refs)) {
|
| 525 | csd_unlock(&data->csd);
|
| 526 | return;
|
| 527 | }
|
| 528 |
|
| 529 | raw_spin_lock_irqsave(&call_function.lock, flags);
|
| 530 | |
| 531 | * Place entry at the _HEAD_ of the list, so that any cpu still
|
| 532 | * observing the entry in generic_smp_call_function_interrupt()
|
| 533 | * will not miss any other list entries:
|
| 534 |
|
| 535 | list_add_rcu(&data->csd.list, &call_function.queue);
|
| 536 | |
| 537 | * We rely on the wmb() in list_add_rcu to complete our writes
|
| 538 | * to the cpumask before this write to refs, which indicates
|
| 539 | * data is on the list and is ready to be processed.
|
| 540 |
|
| 541 | atomic_set(&data->refs, refs);
|
| 542 | raw_spin_unlock_irqrestore(&call_function.lock, flags);
|
| 543 |
|
| 544 | |
| 545 | * Make the list addition visible before sending the ipi.
|
| 546 | * (IPIs must obey or appear to obey normal Linux cache
|
| 547 | * coherency rules -- see comment in generic_exec_single).
|
| 548 |
|
| 549 | smp_mb();
|
| 550 |
|
| 551 |
|
| 552 | arch_send_call_function_ipi_mask(data->cpumask);
|
| 553 |
|
| 554 |
|
| 555 | if (wait)
|
| 556 | csd_lock_wait(&data->csd);
|
| 557 | }
|
| 558 | EXPORT_SYMBOL(smp_call_function_many);
|
| 559 |
|
| 560 | |
| 561 | * smp_call_function(): Run a function on all other CPUs.
|
| 562 | * @func: The function to run. This must be fast and non-blocking.
|
| 563 | * @info: An arbitrary pointer to pass to the function.
|
| 564 | * @wait: If true, wait (atomically) until function has completed
|
| 565 | * on other CPUs.
|
| 566 | *
|
| 567 | * Returns 0.
|
| 568 | *
|
| 569 | * If @wait is true, then returns once @func has returned; otherwise
|
| 570 | * it returns just before the target cpu calls @func.
|
| 571 | *
|
| 572 | * You must not call this function with disabled interrupts or from a
|
| 573 | * hardware interrupt handler or from a bottom half handler.
|
| 574 |
|
| 575 | int smp_call_function(smp_call_func_t func, void *info, int wait)
|
| 576 | {
|
| 577 | preempt_disable();
|
| 578 | smp_call_function_many(cpu_online_mask, func, info, wait);
|
| 579 | preempt_enable();
|
| 580 |
|
| 581 | return 0;
|
| 582 | }
|
| 583 | EXPORT_SYMBOL(smp_call_function);
|
| 584 | #endif
|
| 585 |
|
| 586 |
|
| 587 | unsigned int setup_max_cpus = NR_CPUS;
|
| 588 | EXPORT_SYMBOL(setup_max_cpus);
|
| 589 |
|
| 590 |
|
| 591 | |
| 592 | * Setup routine for controlling SMP activation
|
| 593 | *
|
| 594 | * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
|
| 595 | * activation entirely (the MPS table probe still happens, though).
|
| 596 | *
|
| 597 | * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
|
| 598 | * greater than 0, limits the maximum number of CPUs activated in
|
| 599 | * SMP mode to <NUM>.
|
| 600 |
|
| 601 |
|
| 602 | void __weak arch_disable_smp_support(void) { }
|
| 603 |
|
| 604 | static int __init nosmp(char *str)
|
| 605 | {
|
| 606 | setup_max_cpus = 0;
|
| 607 | arch_disable_smp_support();
|
| 608 |
|
| 609 | return 0;
|
| 610 | }
|
| 611 |
|
| 612 | early_param("nosmp", nosmp);
|
| 613 |
|
| 614 |
|
| 615 | static int __init nrcpus(char *str)
|
| 616 | {
|
| 617 | int nr_cpus;
|
| 618 |
|
| 619 | get_option(&str, &nr_cpus);
|
| 620 | if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
|
| 621 | nr_cpu_ids = nr_cpus;
|
| 622 |
|
| 623 | return 0;
|
| 624 | }
|
| 625 |
|
| 626 | early_param("nr_cpus", nrcpus);
|
| 627 |
|
| 628 | static int __init maxcpus(char *str)
|
| 629 | {
|
| 630 | get_option(&str, &setup_max_cpus);
|
| 631 | if (setup_max_cpus == 0)
|
| 632 | arch_disable_smp_support();
|
| 633 |
|
| 634 | return 0;
|
| 635 | }
|
| 636 |
|
| 637 | early_param("maxcpus", maxcpus);
|
| 638 |
|
| 639 |
|
| 640 | int nr_cpu_ids __read_mostly = NR_CPUS;
|
| 641 | EXPORT_SYMBOL(nr_cpu_ids);
|
| 642 |
|
| 643 |
|
| 644 | void __init setup_nr_cpu_ids(void)
|
| 645 | {
|
| 646 | nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
|
| 647 | }
|
| 648 |
|
| 649 |
|
| 650 | void __init smp_init(void)
|
| 651 | {
|
| 652 | unsigned int cpu;
|
| 653 |
|
| 654 | idle_threads_init();
|
| 655 |
|
| 656 |
|
| 657 | for_each_present_cpu(cpu) {
|
| 658 | if (num_online_cpus() >= setup_max_cpus)
|
| 659 | break;
|
| 660 | if (!cpu_online(cpu))
|
| 661 | cpu_up(cpu);
|
| 662 | }
|
| 663 |
|
| 664 |
|
| 665 | printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
|
| 666 | smp_cpus_done(setup_max_cpus);
|
| 667 | }
|
| 668 |
|
| 669 | |
| 670 | * Call a function on all processors. May be used during early boot while
|
| 671 | * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
|
| 672 | * of local_irq_disable/enable().
|
| 673 |
|
| 674 | int on_each_cpu(void (*func) (void *info), void *info, int wait)
|
| 675 | {
|
| 676 | unsigned long flags;
|
| 677 | int ret = 0;
|
| 678 |
|
| 679 | preempt_disable();
|
| 680 | ret = smp_call_function(func, info, wait);
|
| 681 | local_irq_save(flags);
|
| 682 | func(info);
|
| 683 | local_irq_restore(flags);
|
| 684 | preempt_enable();
|
| 685 | return ret;
|
| 686 | }
|
| 687 | EXPORT_SYMBOL(on_each_cpu);
|
| 688 |
|
| 689 | |
| 690 | * on_each_cpu_mask(): Run a function on processors specified by
|
| 691 | * cpumask, which may include the local processor.
|
| 692 | * @mask: The set of cpus to run on (only runs on online subset).
|
| 693 | * @func: The function to run. This must be fast and non-blocking.
|
| 694 | * @info: An arbitrary pointer to pass to the function.
|
| 695 | * @wait: If true, wait (atomically) until function has completed
|
| 696 | * on other CPUs.
|
| 697 | *
|
| 698 | * If @wait is true, then returns once @func has returned.
|
| 699 | *
|
| 700 | * You must not call this function with disabled interrupts or
|
| 701 | * from a hardware interrupt handler or from a bottom half handler.
|
| 702 |
|
| 703 | void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
|
| 704 | void *info, bool wait)
|
| 705 | {
|
| 706 | int cpu = get_cpu();
|
| 707 |
|
| 708 | smp_call_function_many(mask, func, info, wait);
|
| 709 | if (cpumask_test_cpu(cpu, mask)) {
|
| 710 | local_irq_disable();
|
| 711 | func(info);
|
| 712 | local_irq_enable();
|
| 713 | }
|
| 714 | put_cpu();
|
| 715 | }
|
| 716 | EXPORT_SYMBOL(on_each_cpu_mask);
|
| 717 |
|
| 718 | |
| 719 | * on_each_cpu_cond(): Call a function on each processor for which
|
| 720 | * the supplied function cond_func returns true, optionally waiting
|
| 721 | * for all the required CPUs to finish. This may include the local
|
| 722 | * processor.
|
| 723 | * @cond_func: A callback function that is passed a cpu id and
|
| 724 | * the the info parameter. The function is called
|
| 725 | * with preemption disabled. The function should
|
| 726 | * return a blooean value indicating whether to IPI
|
| 727 | * the specified CPU.
|
| 728 | * @func: The function to run on all applicable CPUs.
|
| 729 | * This must be fast and non-blocking.
|
| 730 | * @info: An arbitrary pointer to pass to both functions.
|
| 731 | * @wait: If true, wait (atomically) until function has
|
| 732 | * completed on other CPUs.
|
| 733 | * @gfp_flags: GFP flags to use when allocating the cpumask
|
| 734 | * used internally by the function.
|
| 735 | *
|
| 736 | * The function might sleep if the GFP flags indicates a non
|
| 737 | * atomic allocation is allowed.
|
| 738 | *
|
| 739 | * Preemption is disabled to protect against CPUs going offline but not online.
|
| 740 | * CPUs going online during the call will not be seen or sent an IPI.
|
| 741 | *
|
| 742 | * You must not call this function with disabled interrupts or
|
| 743 | * from a hardware interrupt handler or from a bottom half handler.
|
| 744 |
|
| 745 | void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
|
| 746 | smp_call_func_t func, void *info, bool wait,
|
| 747 | gfp_t gfp_flags)
|
| 748 | {
|
| 749 | cpumask_var_t cpus;
|
| 750 | int cpu, ret;
|
| 751 |
|
| 752 | might_sleep_if(gfp_flags & __GFP_WAIT);
|
| 753 |
|
| 754 | if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
|
| 755 | preempt_disable();
|
| 756 | for_each_online_cpu(cpu)
|
| 757 | if (cond_func(cpu, info))
|
| 758 | cpumask_set_cpu(cpu, cpus);
|
| 759 | on_each_cpu_mask(cpus, func, info, wait);
|
| 760 | preempt_enable();
|
| 761 | free_cpumask_var(cpus);
|
| 762 | } else {
|
| 763 | |
| 764 | * No free cpumask, bother. No matter, we'll
|
| 765 | * just have to IPI them one by one.
|
| 766 |
|
| 767 | preempt_disable();
|
| 768 | for_each_online_cpu(cpu)
|
| 769 | if (cond_func(cpu, info)) {
|
| 770 | ret = smp_call_function_single(cpu, func,
|
| 771 | info, wait);
|
| 772 | WARN_ON_ONCE(!ret);
|
| 773 | }
|
| 774 | preempt_enable();
|
| 775 | }
|
| 776 | }
|
| 777 | EXPORT_SYMBOL(on_each_cpu_cond);
|
| 778 |
|
| 779 | static void do_nothing(void *unused)
|
| 780 | {
|
| 781 | }
|
| 782 |
|
| 783 | |
| 784 | * kick_all_cpus_sync - Force all cpus out of idle
|
| 785 | *
|
| 786 | * Used to synchronize the update of pm_idle function pointer. It's
|
| 787 | * called after the pointer is updated and returns after the dummy
|
| 788 | * callback function has been executed on all cpus. The execution of
|
| 789 | * the function can only happen on the remote cpus after they have
|
| 790 | * left the idle function which had been called via pm_idle function
|
| 791 | * pointer. So it's guaranteed that nothing uses the previous pointer
|
| 792 | * anymore.
|
| 793 |
|
| 794 | void kick_all_cpus_sync(void)
|
| 795 | {
|
| 796 |
|
| 797 | smp_mb();
|
| 798 | smp_call_function(do_nothing, NULL, 1);
|
| 799 | }
|
| 800 | EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
|