| 1 | |
| 2 | * Generic helpers for smp ipi calls
|
| 3 | *
|
| 4 | * (C) Jens Axboe <[email protected]> 2008
|
| 5 |
|
| 6 | #include <linux/irq_work.h>
|
| 7 | #include <linux/rcupdate.h>
|
| 8 | #include <linux/rculist.h>
|
| 9 | #include <linux/kernel.h>
|
| 10 | #include <linux/export.h>
|
| 11 | #include <linux/percpu.h>
|
| 12 | #include <linux/init.h>
|
| 13 | #include <linux/gfp.h>
|
| 14 | #include <linux/smp.h>
|
| 15 | #include <linux/cpu.h>
|
| 16 | #include <linux/sched.h>
|
| 17 |
|
| 18 | #include "smpboot.h"
|
| 19 |
|
| 20 | enum {
|
| 21 | CSD_FLAG_LOCK = 0x01,
|
| 22 | CSD_FLAG_SYNCHRONOUS = 0x02,
|
| 23 | };
|
| 24 |
|
| 25 | struct call_function_data {
|
| 26 | struct call_single_data __percpu *csd;
|
| 27 | cpumask_var_t cpumask;
|
| 28 | };
|
| 29 |
|
| 30 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data);
|
| 31 |
|
| 32 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
|
| 33 |
|
| 34 | static void flush_smp_call_function_queue(bool warn_cpu_offline);
|
| 35 |
|
| 36 | static int
|
| 37 | hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
|
| 38 | {
|
| 39 | long cpu = (long)hcpu;
|
| 40 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
|
| 41 |
|
| 42 | switch (action) {
|
| 43 | case CPU_UP_PREPARE:
|
| 44 | case CPU_UP_PREPARE_FROZEN:
|
| 45 | if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
|
| 46 | cpu_to_node(cpu)))
|
| 47 | return notifier_from_errno(-ENOMEM);
|
| 48 | cfd->csd = alloc_percpu(struct call_single_data);
|
| 49 | if (!cfd->csd) {
|
| 50 | free_cpumask_var(cfd->cpumask);
|
| 51 | return notifier_from_errno(-ENOMEM);
|
| 52 | }
|
| 53 | break;
|
| 54 |
|
| 55 | #ifdef CONFIG_HOTPLUG_CPU
|
| 56 | case CPU_UP_CANCELED:
|
| 57 | case CPU_UP_CANCELED_FROZEN:
|
| 58 |
|
| 59 |
|
| 60 | case CPU_DEAD:
|
| 61 | case CPU_DEAD_FROZEN:
|
| 62 | free_cpumask_var(cfd->cpumask);
|
| 63 | free_percpu(cfd->csd);
|
| 64 | break;
|
| 65 |
|
| 66 | case CPU_DYING:
|
| 67 | case CPU_DYING_FROZEN:
|
| 68 | |
| 69 | * The IPIs for the smp-call-function callbacks queued by other
|
| 70 | * CPUs might arrive late, either due to hardware latencies or
|
| 71 | * because this CPU disabled interrupts (inside stop-machine)
|
| 72 | * before the IPIs were sent. So flush out any pending callbacks
|
| 73 | * explicitly (without waiting for the IPIs to arrive), to
|
| 74 | * ensure that the outgoing CPU doesn't go offline with work
|
| 75 | * still pending.
|
| 76 |
|
| 77 | flush_smp_call_function_queue(false);
|
| 78 | break;
|
| 79 | #endif
|
| 80 | };
|
| 81 |
|
| 82 | return NOTIFY_OK;
|
| 83 | }
|
| 84 |
|
| 85 | static struct notifier_block hotplug_cfd_notifier = {
|
| 86 | .notifier_call = hotplug_cfd,
|
| 87 | };
|
| 88 |
|
| 89 | void __init call_function_init(void)
|
| 90 | {
|
| 91 | void *cpu = (void *)(long)smp_processor_id();
|
| 92 | int i;
|
| 93 |
|
| 94 | for_each_possible_cpu(i)
|
| 95 | init_llist_head(&per_cpu(call_single_queue, i));
|
| 96 |
|
| 97 | hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);
|
| 98 | register_cpu_notifier(&hotplug_cfd_notifier);
|
| 99 | }
|
| 100 |
|
| 101 | |
| 102 | * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
|
| 103 | *
|
| 104 | * For non-synchronous ipi calls the csd can still be in use by the
|
| 105 | * previous function call. For multi-cpu calls its even more interesting
|
| 106 | * as we'll have to ensure no other cpu is observing our csd.
|
| 107 |
|
| 108 | static void csd_lock_wait(struct call_single_data *csd)
|
| 109 | {
|
| 110 | while (smp_load_acquire(&csd->flags) & CSD_FLAG_LOCK)
|
| 111 | cpu_relax();
|
| 112 | }
|
| 113 |
|
| 114 | static void csd_lock(struct call_single_data *csd)
|
| 115 | {
|
| 116 | csd_lock_wait(csd);
|
| 117 | csd->flags |= CSD_FLAG_LOCK;
|
| 118 |
|
| 119 | |
| 120 | * prevent CPU from reordering the above assignment
|
| 121 | * to ->flags with any subsequent assignments to other
|
| 122 | * fields of the specified call_single_data structure:
|
| 123 |
|
| 124 | smp_wmb();
|
| 125 | }
|
| 126 |
|
| 127 | static void csd_unlock(struct call_single_data *csd)
|
| 128 | {
|
| 129 | WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
|
| 130 |
|
| 131 | |
| 132 | * ensure we're all done before releasing data:
|
| 133 |
|
| 134 | smp_store_release(&csd->flags, 0);
|
| 135 | }
|
| 136 |
|
| 137 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
|
| 138 |
|
| 139 | |
| 140 | * Insert a previously allocated call_single_data element
|
| 141 | * for execution on the given CPU. data must already have
|
| 142 | * ->func, ->info, and ->flags set.
|
| 143 |
|
| 144 | static int generic_exec_single(int cpu, struct call_single_data *csd,
|
| 145 | smp_call_func_t func, void *info)
|
| 146 | {
|
| 147 | if (cpu == smp_processor_id()) {
|
| 148 | unsigned long flags;
|
| 149 |
|
| 150 | |
| 151 | * We can unlock early even for the synchronous on-stack case,
|
| 152 | * since we're doing this from the same CPU..
|
| 153 |
|
| 154 | csd_unlock(csd);
|
| 155 | local_irq_save(flags);
|
| 156 | func(info);
|
| 157 | local_irq_restore(flags);
|
| 158 | return 0;
|
| 159 | }
|
| 160 |
|
| 161 |
|
| 162 | if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
|
| 163 | csd_unlock(csd);
|
| 164 | return -ENXIO;
|
| 165 | }
|
| 166 |
|
| 167 | csd->func = func;
|
| 168 | csd->info = info;
|
| 169 |
|
| 170 | |
| 171 | * The list addition should be visible before sending the IPI
|
| 172 | * handler locks the list to pull the entry off it because of
|
| 173 | * normal cache coherency rules implied by spinlocks.
|
| 174 | *
|
| 175 | * If IPIs can go out of order to the cache coherency protocol
|
| 176 | * in an architecture, sufficient synchronisation should be added
|
| 177 | * to arch code to make it appear to obey cache coherency WRT
|
| 178 | * locking and barrier primitives. Generic code isn't really
|
| 179 | * equipped to do the right thing...
|
| 180 |
|
| 181 | if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
|
| 182 | arch_send_call_function_single_ipi(cpu);
|
| 183 |
|
| 184 | return 0;
|
| 185 | }
|
| 186 |
|
| 187 | |
| 188 | * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
|
| 189 | *
|
| 190 | * Invoked by arch to handle an IPI for call function single.
|
| 191 | * Must be called with interrupts disabled.
|
| 192 |
|
| 193 | void generic_smp_call_function_single_interrupt(void)
|
| 194 | {
|
| 195 | flush_smp_call_function_queue(true);
|
| 196 | }
|
| 197 |
|
| 198 | |
| 199 | * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
|
| 200 | *
|
| 201 | * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
|
| 202 | * offline CPU. Skip this check if set to 'false'.
|
| 203 | *
|
| 204 | * Flush any pending smp-call-function callbacks queued on this CPU. This is
|
| 205 | * invoked by the generic IPI handler, as well as by a CPU about to go offline,
|
| 206 | * to ensure that all pending IPI callbacks are run before it goes completely
|
| 207 | * offline.
|
| 208 | *
|
| 209 | * Loop through the call_single_queue and run all the queued callbacks.
|
| 210 | * Must be called with interrupts disabled.
|
| 211 |
|
| 212 | static void flush_smp_call_function_queue(bool warn_cpu_offline)
|
| 213 | {
|
| 214 | struct llist_head *head;
|
| 215 | struct llist_node *entry;
|
| 216 | struct call_single_data *csd, *csd_next;
|
| 217 | static bool warned;
|
| 218 |
|
| 219 | WARN_ON(!irqs_disabled());
|
| 220 |
|
| 221 | head = this_cpu_ptr(&call_single_queue);
|
| 222 | entry = llist_del_all(head);
|
| 223 | entry = llist_reverse_order(entry);
|
| 224 |
|
| 225 |
|
| 226 | if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
|
| 227 | !warned && !llist_empty(head))) {
|
| 228 | warned = true;
|
| 229 | WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
|
| 230 |
|
| 231 | |
| 232 | * We don't have to use the _safe() variant here
|
| 233 | * because we are not invoking the IPI handlers yet.
|
| 234 |
|
| 235 | llist_for_each_entry(csd, entry, llist)
|
| 236 | pr_warn("IPI callback %pS sent to offline CPU\n",
|
| 237 | csd->func);
|
| 238 | }
|
| 239 |
|
| 240 | llist_for_each_entry_safe(csd, csd_next, entry, llist) {
|
| 241 | smp_call_func_t func = csd->func;
|
| 242 | void *info = csd->info;
|
| 243 |
|
| 244 |
|
| 245 | if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
|
| 246 | func(info);
|
| 247 | csd_unlock(csd);
|
| 248 | } else {
|
| 249 | csd_unlock(csd);
|
| 250 | func(info);
|
| 251 | }
|
| 252 | }
|
| 253 |
|
| 254 | |
| 255 | * Handle irq works queued remotely by irq_work_queue_on().
|
| 256 | * Smp functions above are typically synchronous so they
|
| 257 | * better run first since some other CPUs may be busy waiting
|
| 258 | * for them.
|
| 259 |
|
| 260 | irq_work_run();
|
| 261 | }
|
| 262 |
|
| 263 | |
| 264 | * smp_call_function_single - Run a function on a specific CPU
|
| 265 | * @func: The function to run. This must be fast and non-blocking.
|
| 266 | * @info: An arbitrary pointer to pass to the function.
|
| 267 | * @wait: If true, wait until function has completed on other CPUs.
|
| 268 | *
|
| 269 | * Returns 0 on success, else a negative status code.
|
| 270 |
|
| 271 | int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
|
| 272 | int wait)
|
| 273 | {
|
| 274 | struct call_single_data *csd;
|
| 275 | struct call_single_data csd_stack = { .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS };
|
| 276 | int this_cpu;
|
| 277 | int err;
|
| 278 |
|
| 279 | |
| 280 | * prevent preemption and reschedule on another processor,
|
| 281 | * as well as CPU removal
|
| 282 |
|
| 283 | this_cpu = get_cpu();
|
| 284 |
|
| 285 | |
| 286 | * Can deadlock when called with interrupts disabled.
|
| 287 | * We allow cpu's that are not yet online though, as no one else can
|
| 288 | * send smp call function interrupt to this cpu and as such deadlocks
|
| 289 | * can't happen.
|
| 290 |
|
| 291 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
|
| 292 | && !oops_in_progress);
|
| 293 |
|
| 294 | csd = &csd_stack;
|
| 295 | if (!wait) {
|
| 296 | csd = this_cpu_ptr(&csd_data);
|
| 297 | csd_lock(csd);
|
| 298 | }
|
| 299 |
|
| 300 | err = generic_exec_single(cpu, csd, func, info);
|
| 301 |
|
| 302 | if (wait)
|
| 303 | csd_lock_wait(csd);
|
| 304 |
|
| 305 | put_cpu();
|
| 306 |
|
| 307 | return err;
|
| 308 | }
|
| 309 | EXPORT_SYMBOL(smp_call_function_single);
|
| 310 |
|
| 311 | |
| 312 | * smp_call_function_single_async(): Run an asynchronous function on a
|
| 313 | * specific CPU.
|
| 314 | * @cpu: The CPU to run on.
|
| 315 | * @csd: Pre-allocated and setup data structure
|
| 316 | *
|
| 317 | * Like smp_call_function_single(), but the call is asynchonous and
|
| 318 | * can thus be done from contexts with disabled interrupts.
|
| 319 | *
|
| 320 | * The caller passes his own pre-allocated data structure
|
| 321 | * (ie: embedded in an object) and is responsible for synchronizing it
|
| 322 | * such that the IPIs performed on the @csd are strictly serialized.
|
| 323 | *
|
| 324 | * NOTE: Be careful, there is unfortunately no current debugging facility to
|
| 325 | * validate the correctness of this serialization.
|
| 326 |
|
| 327 | int smp_call_function_single_async(int cpu, struct call_single_data *csd)
|
| 328 | {
|
| 329 | int err = 0;
|
| 330 |
|
| 331 | preempt_disable();
|
| 332 |
|
| 333 |
|
| 334 | if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK))
|
| 335 | csd_lock_wait(csd);
|
| 336 |
|
| 337 | csd->flags = CSD_FLAG_LOCK;
|
| 338 | smp_wmb();
|
| 339 |
|
| 340 | err = generic_exec_single(cpu, csd, csd->func, csd->info);
|
| 341 | preempt_enable();
|
| 342 |
|
| 343 | return err;
|
| 344 | }
|
| 345 | EXPORT_SYMBOL_GPL(smp_call_function_single_async);
|
| 346 |
|
| 347 | |
| 348 | * smp_call_function_any - Run a function on any of the given cpus
|
| 349 | * @mask: The mask of cpus it can run on.
|
| 350 | * @func: The function to run. This must be fast and non-blocking.
|
| 351 | * @info: An arbitrary pointer to pass to the function.
|
| 352 | * @wait: If true, wait until function has completed.
|
| 353 | *
|
| 354 | * Returns 0 on success, else a negative status code (if no cpus were online).
|
| 355 | *
|
| 356 | * Selection preference:
|
| 357 | * 1) current cpu if in @mask
|
| 358 | * 2) any cpu of current node if in @mask
|
| 359 | * 3) any other online cpu in @mask
|
| 360 |
|
| 361 | int smp_call_function_any(const struct cpumask *mask,
|
| 362 | smp_call_func_t func, void *info, int wait)
|
| 363 | {
|
| 364 | unsigned int cpu;
|
| 365 | const struct cpumask *nodemask;
|
| 366 | int ret;
|
| 367 |
|
| 368 |
|
| 369 | cpu = get_cpu();
|
| 370 | if (cpumask_test_cpu(cpu, mask))
|
| 371 | goto call;
|
| 372 |
|
| 373 |
|
| 374 | nodemask = cpumask_of_node(cpu_to_node(cpu));
|
| 375 | for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
|
| 376 | cpu = cpumask_next_and(cpu, nodemask, mask)) {
|
| 377 | if (cpu_online(cpu))
|
| 378 | goto call;
|
| 379 | }
|
| 380 |
|
| 381 |
|
| 382 | cpu = cpumask_any_and(mask, cpu_online_mask);
|
| 383 | call:
|
| 384 | ret = smp_call_function_single(cpu, func, info, wait);
|
| 385 | put_cpu();
|
| 386 | return ret;
|
| 387 | }
|
| 388 | EXPORT_SYMBOL_GPL(smp_call_function_any);
|
| 389 |
|
| 390 | |
| 391 | * smp_call_function_many(): Run a function on a set of other CPUs.
|
| 392 | * @mask: The set of cpus to run on (only runs on online subset).
|
| 393 | * @func: The function to run. This must be fast and non-blocking.
|
| 394 | * @info: An arbitrary pointer to pass to the function.
|
| 395 | * @wait: If true, wait (atomically) until function has completed
|
| 396 | * on other CPUs.
|
| 397 | *
|
| 398 | * If @wait is true, then returns once @func has returned.
|
| 399 | *
|
| 400 | * You must not call this function with disabled interrupts or from a
|
| 401 | * hardware interrupt handler or from a bottom half handler. Preemption
|
| 402 | * must be disabled when calling this function.
|
| 403 |
|
| 404 | void smp_call_function_many(const struct cpumask *mask,
|
| 405 | smp_call_func_t func, void *info, bool wait)
|
| 406 | {
|
| 407 | struct call_function_data *cfd;
|
| 408 | int cpu, next_cpu, this_cpu = smp_processor_id();
|
| 409 |
|
| 410 | |
| 411 | * Can deadlock when called with interrupts disabled.
|
| 412 | * We allow cpu's that are not yet online though, as no one else can
|
| 413 | * send smp call function interrupt to this cpu and as such deadlocks
|
| 414 | * can't happen.
|
| 415 |
|
| 416 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
|
| 417 | && !oops_in_progress && !early_boot_irqs_disabled);
|
| 418 |
|
| 419 |
|
| 420 | cpu = cpumask_first_and(mask, cpu_online_mask);
|
| 421 | if (cpu == this_cpu)
|
| 422 | cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
|
| 423 |
|
| 424 |
|
| 425 | if (cpu >= nr_cpu_ids)
|
| 426 | return;
|
| 427 |
|
| 428 |
|
| 429 | next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
|
| 430 | if (next_cpu == this_cpu)
|
| 431 | next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
|
| 432 |
|
| 433 |
|
| 434 | if (next_cpu >= nr_cpu_ids) {
|
| 435 | smp_call_function_single(cpu, func, info, wait);
|
| 436 | return;
|
| 437 | }
|
| 438 |
|
| 439 | cfd = this_cpu_ptr(&cfd_data);
|
| 440 |
|
| 441 | cpumask_and(cfd->cpumask, mask, cpu_online_mask);
|
| 442 | cpumask_clear_cpu(this_cpu, cfd->cpumask);
|
| 443 |
|
| 444 |
|
| 445 | if (unlikely(!cpumask_weight(cfd->cpumask)))
|
| 446 | return;
|
| 447 |
|
| 448 | for_each_cpu(cpu, cfd->cpumask) {
|
| 449 | struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu);
|
| 450 |
|
| 451 | csd_lock(csd);
|
| 452 | if (wait)
|
| 453 | csd->flags |= CSD_FLAG_SYNCHRONOUS;
|
| 454 | csd->func = func;
|
| 455 | csd->info = info;
|
| 456 | llist_add(&csd->llist, &per_cpu(call_single_queue, cpu));
|
| 457 | }
|
| 458 |
|
| 459 |
|
| 460 | arch_send_call_function_ipi_mask(cfd->cpumask);
|
| 461 |
|
| 462 | if (wait) {
|
| 463 | for_each_cpu(cpu, cfd->cpumask) {
|
| 464 | struct call_single_data *csd;
|
| 465 |
|
| 466 | csd = per_cpu_ptr(cfd->csd, cpu);
|
| 467 | csd_lock_wait(csd);
|
| 468 | }
|
| 469 | }
|
| 470 | }
|
| 471 | EXPORT_SYMBOL(smp_call_function_many);
|
| 472 |
|
| 473 | |
| 474 | * smp_call_function(): Run a function on all other CPUs.
|
| 475 | * @func: The function to run. This must be fast and non-blocking.
|
| 476 | * @info: An arbitrary pointer to pass to the function.
|
| 477 | * @wait: If true, wait (atomically) until function has completed
|
| 478 | * on other CPUs.
|
| 479 | *
|
| 480 | * Returns 0.
|
| 481 | *
|
| 482 | * If @wait is true, then returns once @func has returned; otherwise
|
| 483 | * it returns just before the target cpu calls @func.
|
| 484 | *
|
| 485 | * You must not call this function with disabled interrupts or from a
|
| 486 | * hardware interrupt handler or from a bottom half handler.
|
| 487 |
|
| 488 | int smp_call_function(smp_call_func_t func, void *info, int wait)
|
| 489 | {
|
| 490 | preempt_disable();
|
| 491 | smp_call_function_many(cpu_online_mask, func, info, wait);
|
| 492 | preempt_enable();
|
| 493 |
|
| 494 | return 0;
|
| 495 | }
|
| 496 | EXPORT_SYMBOL(smp_call_function);
|
| 497 |
|
| 498 |
|
| 499 | unsigned int setup_max_cpus = NR_CPUS;
|
| 500 | EXPORT_SYMBOL(setup_max_cpus);
|
| 501 |
|
| 502 |
|
| 503 | |
| 504 | * Setup routine for controlling SMP activation
|
| 505 | *
|
| 506 | * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
|
| 507 | * activation entirely (the MPS table probe still happens, though).
|
| 508 | *
|
| 509 | * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
|
| 510 | * greater than 0, limits the maximum number of CPUs activated in
|
| 511 | * SMP mode to <NUM>.
|
| 512 |
|
| 513 |
|
| 514 | void __weak arch_disable_smp_support(void) { }
|
| 515 |
|
| 516 | static int __init nosmp(char *str)
|
| 517 | {
|
| 518 | setup_max_cpus = 0;
|
| 519 | arch_disable_smp_support();
|
| 520 |
|
| 521 | return 0;
|
| 522 | }
|
| 523 |
|
| 524 | early_param("nosmp", nosmp);
|
| 525 |
|
| 526 |
|
| 527 | static int __init nrcpus(char *str)
|
| 528 | {
|
| 529 | int nr_cpus;
|
| 530 |
|
| 531 | get_option(&str, &nr_cpus);
|
| 532 | if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
|
| 533 | nr_cpu_ids = nr_cpus;
|
| 534 |
|
| 535 | return 0;
|
| 536 | }
|
| 537 |
|
| 538 | early_param("nr_cpus", nrcpus);
|
| 539 |
|
| 540 | static int __init maxcpus(char *str)
|
| 541 | {
|
| 542 | get_option(&str, &setup_max_cpus);
|
| 543 | if (setup_max_cpus == 0)
|
| 544 | arch_disable_smp_support();
|
| 545 |
|
| 546 | return 0;
|
| 547 | }
|
| 548 |
|
| 549 | early_param("maxcpus", maxcpus);
|
| 550 |
|
| 551 |
|
| 552 | int nr_cpu_ids __read_mostly = NR_CPUS;
|
| 553 | EXPORT_SYMBOL(nr_cpu_ids);
|
| 554 |
|
| 555 |
|
| 556 | void __init setup_nr_cpu_ids(void)
|
| 557 | {
|
| 558 | nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
|
| 559 | }
|
| 560 |
|
| 561 | void __weak smp_announce(void)
|
| 562 | {
|
| 563 | printk(KERN_INFO "Brought up %d CPUs\n", num_online_cpus());
|
| 564 | }
|
| 565 |
|
| 566 |
|
| 567 | void __init smp_init(void)
|
| 568 | {
|
| 569 | unsigned int cpu;
|
| 570 |
|
| 571 | idle_threads_init();
|
| 572 |
|
| 573 |
|
| 574 | for_each_present_cpu(cpu) {
|
| 575 | if (num_online_cpus() >= setup_max_cpus)
|
| 576 | break;
|
| 577 | if (!cpu_online(cpu))
|
| 578 | cpu_up(cpu);
|
| 579 | }
|
| 580 |
|
| 581 |
|
| 582 | smp_announce();
|
| 583 | smp_cpus_done(setup_max_cpus);
|
| 584 | }
|
| 585 |
|
| 586 | |
| 587 | * Call a function on all processors. May be used during early boot while
|
| 588 | * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead
|
| 589 | * of local_irq_disable/enable().
|
| 590 |
|
| 591 | int on_each_cpu(void (*func) (void *info), void *info, int wait)
|
| 592 | {
|
| 593 | unsigned long flags;
|
| 594 | int ret = 0;
|
| 595 |
|
| 596 | preempt_disable();
|
| 597 | ret = smp_call_function(func, info, wait);
|
| 598 | local_irq_save(flags);
|
| 599 | func(info);
|
| 600 | local_irq_restore(flags);
|
| 601 | preempt_enable();
|
| 602 | return ret;
|
| 603 | }
|
| 604 | EXPORT_SYMBOL(on_each_cpu);
|
| 605 |
|
| 606 | |
| 607 | * on_each_cpu_mask(): Run a function on processors specified by
|
| 608 | * cpumask, which may include the local processor.
|
| 609 | * @mask: The set of cpus to run on (only runs on online subset).
|
| 610 | * @func: The function to run. This must be fast and non-blocking.
|
| 611 | * @info: An arbitrary pointer to pass to the function.
|
| 612 | * @wait: If true, wait (atomically) until function has completed
|
| 613 | * on other CPUs.
|
| 614 | *
|
| 615 | * If @wait is true, then returns once @func has returned.
|
| 616 | *
|
| 617 | * You must not call this function with disabled interrupts or from a
|
| 618 | * hardware interrupt handler or from a bottom half handler. The
|
| 619 | * exception is that it may be used during early boot while
|
| 620 | * early_boot_irqs_disabled is set.
|
| 621 |
|
| 622 | void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
|
| 623 | void *info, bool wait)
|
| 624 | {
|
| 625 | int cpu = get_cpu();
|
| 626 |
|
| 627 | smp_call_function_many(mask, func, info, wait);
|
| 628 | if (cpumask_test_cpu(cpu, mask)) {
|
| 629 | unsigned long flags;
|
| 630 | local_irq_save(flags);
|
| 631 | func(info);
|
| 632 | local_irq_restore(flags);
|
| 633 | }
|
| 634 | put_cpu();
|
| 635 | }
|
| 636 | EXPORT_SYMBOL(on_each_cpu_mask);
|
| 637 |
|
| 638 | |
| 639 | * on_each_cpu_cond(): Call a function on each processor for which
|
| 640 | * the supplied function cond_func returns true, optionally waiting
|
| 641 | * for all the required CPUs to finish. This may include the local
|
| 642 | * processor.
|
| 643 | * @cond_func: A callback function that is passed a cpu id and
|
| 644 | * the the info parameter. The function is called
|
| 645 | * with preemption disabled. The function should
|
| 646 | * return a blooean value indicating whether to IPI
|
| 647 | * the specified CPU.
|
| 648 | * @func: The function to run on all applicable CPUs.
|
| 649 | * This must be fast and non-blocking.
|
| 650 | * @info: An arbitrary pointer to pass to both functions.
|
| 651 | * @wait: If true, wait (atomically) until function has
|
| 652 | * completed on other CPUs.
|
| 653 | * @gfp_flags: GFP flags to use when allocating the cpumask
|
| 654 | * used internally by the function.
|
| 655 | *
|
| 656 | * The function might sleep if the GFP flags indicates a non
|
| 657 | * atomic allocation is allowed.
|
| 658 | *
|
| 659 | * Preemption is disabled to protect against CPUs going offline but not online.
|
| 660 | * CPUs going online during the call will not be seen or sent an IPI.
|
| 661 | *
|
| 662 | * You must not call this function with disabled interrupts or
|
| 663 | * from a hardware interrupt handler or from a bottom half handler.
|
| 664 |
|
| 665 | void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
|
| 666 | smp_call_func_t func, void *info, bool wait,
|
| 667 | gfp_t gfp_flags)
|
| 668 | {
|
| 669 | cpumask_var_t cpus;
|
| 670 | int cpu, ret;
|
| 671 |
|
| 672 | might_sleep_if(gfp_flags & __GFP_WAIT);
|
| 673 |
|
| 674 | if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
|
| 675 | preempt_disable();
|
| 676 | for_each_online_cpu(cpu)
|
| 677 | if (cond_func(cpu, info))
|
| 678 | cpumask_set_cpu(cpu, cpus);
|
| 679 | on_each_cpu_mask(cpus, func, info, wait);
|
| 680 | preempt_enable();
|
| 681 | free_cpumask_var(cpus);
|
| 682 | } else {
|
| 683 | |
| 684 | * No free cpumask, bother. No matter, we'll
|
| 685 | * just have to IPI them one by one.
|
| 686 |
|
| 687 | preempt_disable();
|
| 688 | for_each_online_cpu(cpu)
|
| 689 | if (cond_func(cpu, info)) {
|
| 690 | ret = smp_call_function_single(cpu, func,
|
| 691 | info, wait);
|
| 692 | WARN_ON_ONCE(ret);
|
| 693 | }
|
| 694 | preempt_enable();
|
| 695 | }
|
| 696 | }
|
| 697 | EXPORT_SYMBOL(on_each_cpu_cond);
|
| 698 |
|
| 699 | static void do_nothing(void *unused)
|
| 700 | {
|
| 701 | }
|
| 702 |
|
| 703 | |
| 704 | * kick_all_cpus_sync - Force all cpus out of idle
|
| 705 | *
|
| 706 | * Used to synchronize the update of pm_idle function pointer. It's
|
| 707 | * called after the pointer is updated and returns after the dummy
|
| 708 | * callback function has been executed on all cpus. The execution of
|
| 709 | * the function can only happen on the remote cpus after they have
|
| 710 | * left the idle function which had been called via pm_idle function
|
| 711 | * pointer. So it's guaranteed that nothing uses the previous pointer
|
| 712 | * anymore.
|
| 713 |
|
| 714 | void kick_all_cpus_sync(void)
|
| 715 | {
|
| 716 |
|
| 717 | smp_mb();
|
| 718 | smp_call_function(do_nothing, NULL, 1);
|
| 719 | }
|
| 720 | EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
|
| 721 |
|
| 722 | |
| 723 | * wake_up_all_idle_cpus - break all cpus out of idle
|
| 724 | * wake_up_all_idle_cpus try to break all cpus which is in idle state even
|
| 725 | * including idle polling cpus, for non-idle cpus, we will do nothing
|
| 726 | * for them.
|
| 727 |
|
| 728 | void wake_up_all_idle_cpus(void)
|
| 729 | {
|
| 730 | int cpu;
|
| 731 |
|
| 732 | preempt_disable();
|
| 733 | for_each_online_cpu(cpu) {
|
| 734 | if (cpu == smp_processor_id())
|
| 735 | continue;
|
| 736 |
|
| 737 | wake_up_if_idle(cpu);
|
| 738 | }
|
| 739 | preempt_enable();
|
| 740 | }
|
| 741 | EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
|