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