linux/kernel/smp.c
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   1/*
   2 * Generic helpers for smp ipi calls
   3 *
   4 * (C) Jens Axboe <jens.axboe@oracle.com> 2008
   5 */
   6
   7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   8
   9#include <linux/irq_work.h>
  10#include <linux/rcupdate.h>
  11#include <linux/rculist.h>
  12#include <linux/kernel.h>
  13#include <linux/export.h>
  14#include <linux/percpu.h>
  15#include <linux/init.h>
  16#include <linux/gfp.h>
  17#include <linux/smp.h>
  18#include <linux/cpu.h>
  19#include <linux/sched.h>
  20#include <linux/sched/idle.h>
  21#include <linux/hypervisor.h>
  22
  23#include "smpboot.h"
  24
  25enum {
  26        CSD_FLAG_LOCK           = 0x01,
  27        CSD_FLAG_SYNCHRONOUS    = 0x02,
  28};
  29
  30struct call_function_data {
  31        call_single_data_t      __percpu *csd;
  32        cpumask_var_t           cpumask;
  33        cpumask_var_t           cpumask_ipi;
  34};
  35
  36static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data);
  37
  38static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
  39
  40static void flush_smp_call_function_queue(bool warn_cpu_offline);
  41
  42int smpcfd_prepare_cpu(unsigned int cpu)
  43{
  44        struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
  45
  46        if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
  47                                     cpu_to_node(cpu)))
  48                return -ENOMEM;
  49        if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL,
  50                                     cpu_to_node(cpu))) {
  51                free_cpumask_var(cfd->cpumask);
  52                return -ENOMEM;
  53        }
  54        cfd->csd = alloc_percpu(call_single_data_t);
  55        if (!cfd->csd) {
  56                free_cpumask_var(cfd->cpumask);
  57                free_cpumask_var(cfd->cpumask_ipi);
  58                return -ENOMEM;
  59        }
  60
  61        return 0;
  62}
  63
  64int smpcfd_dead_cpu(unsigned int cpu)
  65{
  66        struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
  67
  68        free_cpumask_var(cfd->cpumask);
  69        free_cpumask_var(cfd->cpumask_ipi);
  70        free_percpu(cfd->csd);
  71        return 0;
  72}
  73
  74int smpcfd_dying_cpu(unsigned int cpu)
  75{
  76        /*
  77         * The IPIs for the smp-call-function callbacks queued by other
  78         * CPUs might arrive late, either due to hardware latencies or
  79         * because this CPU disabled interrupts (inside stop-machine)
  80         * before the IPIs were sent. So flush out any pending callbacks
  81         * explicitly (without waiting for the IPIs to arrive), to
  82         * ensure that the outgoing CPU doesn't go offline with work
  83         * still pending.
  84         */
  85        flush_smp_call_function_queue(false);
  86        return 0;
  87}
  88
  89void __init call_function_init(void)
  90{
  91        int i;
  92
  93        for_each_possible_cpu(i)
  94                init_llist_head(&per_cpu(call_single_queue, i));
  95
  96        smpcfd_prepare_cpu(smp_processor_id());
  97}
  98
  99/*
 100 * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
 101 *
 102 * For non-synchronous ipi calls the csd can still be in use by the
 103 * previous function call. For multi-cpu calls its even more interesting
 104 * as we'll have to ensure no other cpu is observing our csd.
 105 */
 106static __always_inline void csd_lock_wait(call_single_data_t *csd)
 107{
 108        smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK));
 109}
 110
 111static __always_inline void csd_lock(call_single_data_t *csd)
 112{
 113        csd_lock_wait(csd);
 114        csd->flags |= CSD_FLAG_LOCK;
 115
 116        /*
 117         * prevent CPU from reordering the above assignment
 118         * to ->flags with any subsequent assignments to other
 119         * fields of the specified call_single_data_t structure:
 120         */
 121        smp_wmb();
 122}
 123
 124static __always_inline void csd_unlock(call_single_data_t *csd)
 125{
 126        WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
 127
 128        /*
 129         * ensure we're all done before releasing data:
 130         */
 131        smp_store_release(&csd->flags, 0);
 132}
 133
 134static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
 135
 136/*
 137 * Insert a previously allocated call_single_data_t element
 138 * for execution on the given CPU. data must already have
 139 * ->func, ->info, and ->flags set.
 140 */
 141static int generic_exec_single(int cpu, call_single_data_t *csd,
 142                               smp_call_func_t func, void *info)
 143{
 144        if (cpu == smp_processor_id()) {
 145                unsigned long flags;
 146
 147                /*
 148                 * We can unlock early even for the synchronous on-stack case,
 149                 * since we're doing this from the same CPU..
 150                 */
 151                csd_unlock(csd);
 152                local_irq_save(flags);
 153                func(info);
 154                local_irq_restore(flags);
 155                return 0;
 156        }
 157
 158
 159        if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
 160                csd_unlock(csd);
 161                return -ENXIO;
 162        }
 163
 164        csd->func = func;
 165        csd->info = info;
 166
 167        /*
 168         * The list addition should be visible before sending the IPI
 169         * handler locks the list to pull the entry off it because of
 170         * normal cache coherency rules implied by spinlocks.
 171         *
 172         * If IPIs can go out of order to the cache coherency protocol
 173         * in an architecture, sufficient synchronisation should be added
 174         * to arch code to make it appear to obey cache coherency WRT
 175         * locking and barrier primitives. Generic code isn't really
 176         * equipped to do the right thing...
 177         */
 178        if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
 179                arch_send_call_function_single_ipi(cpu);
 180
 181        return 0;
 182}
 183
 184/**
 185 * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
 186 *
 187 * Invoked by arch to handle an IPI for call function single.
 188 * Must be called with interrupts disabled.
 189 */
 190void generic_smp_call_function_single_interrupt(void)
 191{
 192        flush_smp_call_function_queue(true);
 193}
 194
 195/**
 196 * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
 197 *
 198 * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
 199 *                    offline CPU. Skip this check if set to 'false'.
 200 *
 201 * Flush any pending smp-call-function callbacks queued on this CPU. This is
 202 * invoked by the generic IPI handler, as well as by a CPU about to go offline,
 203 * to ensure that all pending IPI callbacks are run before it goes completely
 204 * offline.
 205 *
 206 * Loop through the call_single_queue and run all the queued callbacks.
 207 * Must be called with interrupts disabled.
 208 */
 209static void flush_smp_call_function_queue(bool warn_cpu_offline)
 210{
 211        struct llist_head *head;
 212        struct llist_node *entry;
 213        call_single_data_t *csd, *csd_next;
 214        static bool warned;
 215
 216        lockdep_assert_irqs_disabled();
 217
 218        head = this_cpu_ptr(&call_single_queue);
 219        entry = llist_del_all(head);
 220        entry = llist_reverse_order(entry);
 221
 222        /* There shouldn't be any pending callbacks on an offline CPU. */
 223        if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
 224                     !warned && !llist_empty(head))) {
 225                warned = true;
 226                WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
 227
 228                /*
 229                 * We don't have to use the _safe() variant here
 230                 * because we are not invoking the IPI handlers yet.
 231                 */
 232                llist_for_each_entry(csd, entry, llist)
 233                        pr_warn("IPI callback %pS sent to offline CPU\n",
 234                                csd->func);
 235        }
 236
 237        llist_for_each_entry_safe(csd, csd_next, entry, llist) {
 238                smp_call_func_t func = csd->func;
 239                void *info = csd->info;
 240
 241                /* Do we wait until *after* callback? */
 242                if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
 243                        func(info);
 244                        csd_unlock(csd);
 245                } else {
 246                        csd_unlock(csd);
 247                        func(info);
 248                }
 249        }
 250
 251        /*
 252         * Handle irq works queued remotely by irq_work_queue_on().
 253         * Smp functions above are typically synchronous so they
 254         * better run first since some other CPUs may be busy waiting
 255         * for them.
 256         */
 257        irq_work_run();
 258}
 259
 260/*
 261 * smp_call_function_single - Run a function on a specific CPU
 262 * @func: The function to run. This must be fast and non-blocking.
 263 * @info: An arbitrary pointer to pass to the function.
 264 * @wait: If true, wait until function has completed on other CPUs.
 265 *
 266 * Returns 0 on success, else a negative status code.
 267 */
 268int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
 269                             int wait)
 270{
 271        call_single_data_t *csd;
 272        call_single_data_t csd_stack = {
 273                .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS,
 274        };
 275        int this_cpu;
 276        int err;
 277
 278        /*
 279         * prevent preemption and reschedule on another processor,
 280         * as well as CPU removal
 281         */
 282        this_cpu = get_cpu();
 283
 284        /*
 285         * Can deadlock when called with interrupts disabled.
 286         * We allow cpu's that are not yet online though, as no one else can
 287         * send smp call function interrupt to this cpu and as such deadlocks
 288         * can't happen.
 289         */
 290        WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
 291                     && !oops_in_progress);
 292
 293        csd = &csd_stack;
 294        if (!wait) {
 295                csd = this_cpu_ptr(&csd_data);
 296                csd_lock(csd);
 297        }
 298
 299        err = generic_exec_single(cpu, csd, func, info);
 300
 301        if (wait)
 302                csd_lock_wait(csd);
 303
 304        put_cpu();
 305
 306        return err;
 307}
 308EXPORT_SYMBOL(smp_call_function_single);
 309
 310/**
 311 * smp_call_function_single_async(): Run an asynchronous function on a
 312 *                               specific CPU.
 313 * @cpu: The CPU to run on.
 314 * @csd: Pre-allocated and setup data structure
 315 *
 316 * Like smp_call_function_single(), but the call is asynchonous and
 317 * can thus be done from contexts with disabled interrupts.
 318 *
 319 * The caller passes his own pre-allocated data structure
 320 * (ie: embedded in an object) and is responsible for synchronizing it
 321 * such that the IPIs performed on the @csd are strictly serialized.
 322 *
 323 * NOTE: Be careful, there is unfortunately no current debugging facility to
 324 * validate the correctness of this serialization.
 325 */
 326int smp_call_function_single_async(int cpu, call_single_data_t *csd)
 327{
 328        int err = 0;
 329
 330        preempt_disable();
 331
 332        /* We could deadlock if we have to wait here with interrupts disabled! */
 333        if (WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK))
 334                csd_lock_wait(csd);
 335
 336        csd->flags = CSD_FLAG_LOCK;
 337        smp_wmb();
 338
 339        err = generic_exec_single(cpu, csd, csd->func, csd->info);
 340        preempt_enable();
 341
 342        return err;
 343}
 344EXPORT_SYMBOL_GPL(smp_call_function_single_async);
 345
 346/*
 347 * smp_call_function_any - Run a function on any of the given cpus
 348 * @mask: The mask of cpus it can run on.
 349 * @func: The function to run. This must be fast and non-blocking.
 350 * @info: An arbitrary pointer to pass to the function.
 351 * @wait: If true, wait until function has completed.
 352 *
 353 * Returns 0 on success, else a negative status code (if no cpus were online).
 354 *
 355 * Selection preference:
 356 *      1) current cpu if in @mask
 357 *      2) any cpu of current node if in @mask
 358 *      3) any other online cpu in @mask
 359 */
 360int smp_call_function_any(const struct cpumask *mask,
 361                          smp_call_func_t func, void *info, int wait)
 362{
 363        unsigned int cpu;
 364        const struct cpumask *nodemask;
 365        int ret;
 366
 367        /* Try for same CPU (cheapest) */
 368        cpu = get_cpu();
 369        if (cpumask_test_cpu(cpu, mask))
 370                goto call;
 371
 372        /* Try for same node. */
 373        nodemask = cpumask_of_node(cpu_to_node(cpu));
 374        for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
 375             cpu = cpumask_next_and(cpu, nodemask, mask)) {
 376                if (cpu_online(cpu))
 377                        goto call;
 378        }
 379
 380        /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
 381        cpu = cpumask_any_and(mask, cpu_online_mask);
 382call:
 383        ret = smp_call_function_single(cpu, func, info, wait);
 384        put_cpu();
 385        return ret;
 386}
 387EXPORT_SYMBOL_GPL(smp_call_function_any);
 388
 389/**
 390 * smp_call_function_many(): Run a function on a set of other CPUs.
 391 * @mask: The set of cpus to run on (only runs on online subset).
 392 * @func: The function to run. This must be fast and non-blocking.
 393 * @info: An arbitrary pointer to pass to the function.
 394 * @wait: If true, wait (atomically) until function has completed
 395 *        on other CPUs.
 396 *
 397 * If @wait is true, then returns once @func has returned.
 398 *
 399 * You must not call this function with disabled interrupts or from a
 400 * hardware interrupt handler or from a bottom half handler. Preemption
 401 * must be disabled when calling this function.
 402 */
 403void smp_call_function_many(const struct cpumask *mask,
 404                            smp_call_func_t func, void *info, bool wait)
 405{
 406        struct call_function_data *cfd;
 407        int cpu, next_cpu, this_cpu = smp_processor_id();
 408
 409        /*
 410         * Can deadlock when called with interrupts disabled.
 411         * We allow cpu's that are not yet online though, as no one else can
 412         * send smp call function interrupt to this cpu and as such deadlocks
 413         * can't happen.
 414         */
 415        WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
 416                     && !oops_in_progress && !early_boot_irqs_disabled);
 417
 418        /* Try to fastpath.  So, what's a CPU they want? Ignoring this one. */
 419        cpu = cpumask_first_and(mask, cpu_online_mask);
 420        if (cpu == this_cpu)
 421                cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
 422
 423        /* No online cpus?  We're done. */
 424        if (cpu >= nr_cpu_ids)
 425                return;
 426
 427        /* Do we have another CPU which isn't us? */
 428        next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
 429        if (next_cpu == this_cpu)
 430                next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
 431
 432        /* Fastpath: do that cpu by itself. */
 433        if (next_cpu >= nr_cpu_ids) {
 434                smp_call_function_single(cpu, func, info, wait);
 435                return;
 436        }
 437
 438        cfd = this_cpu_ptr(&cfd_data);
 439
 440        cpumask_and(cfd->cpumask, mask, cpu_online_mask);
 441        __cpumask_clear_cpu(this_cpu, cfd->cpumask);
 442
 443        /* Some callers race with other cpus changing the passed mask */
 444        if (unlikely(!cpumask_weight(cfd->cpumask)))
 445                return;
 446
 447        cpumask_clear(cfd->cpumask_ipi);
 448        for_each_cpu(cpu, cfd->cpumask) {
 449                call_single_data_t *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                if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
 457                        __cpumask_set_cpu(cpu, cfd->cpumask_ipi);
 458        }
 459
 460        /* Send a message to all CPUs in the map */
 461        arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
 462
 463        if (wait) {
 464                for_each_cpu(cpu, cfd->cpumask) {
 465                        call_single_data_t *csd;
 466
 467                        csd = per_cpu_ptr(cfd->csd, cpu);
 468                        csd_lock_wait(csd);
 469                }
 470        }
 471}
 472EXPORT_SYMBOL(smp_call_function_many);
 473
 474/**
 475 * smp_call_function(): Run a function on all other CPUs.
 476 * @func: The function to run. This must be fast and non-blocking.
 477 * @info: An arbitrary pointer to pass to the function.
 478 * @wait: If true, wait (atomically) until function has completed
 479 *        on other CPUs.
 480 *
 481 * Returns 0.
 482 *
 483 * If @wait is true, then returns once @func has returned; otherwise
 484 * it returns just before the target cpu calls @func.
 485 *
 486 * You must not call this function with disabled interrupts or from a
 487 * hardware interrupt handler or from a bottom half handler.
 488 */
 489int smp_call_function(smp_call_func_t func, void *info, int wait)
 490{
 491        preempt_disable();
 492        smp_call_function_many(cpu_online_mask, func, info, wait);
 493        preempt_enable();
 494
 495        return 0;
 496}
 497EXPORT_SYMBOL(smp_call_function);
 498
 499/* Setup configured maximum number of CPUs to activate */
 500unsigned int setup_max_cpus = NR_CPUS;
 501EXPORT_SYMBOL(setup_max_cpus);
 502
 503
 504/*
 505 * Setup routine for controlling SMP activation
 506 *
 507 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
 508 * activation entirely (the MPS table probe still happens, though).
 509 *
 510 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
 511 * greater than 0, limits the maximum number of CPUs activated in
 512 * SMP mode to <NUM>.
 513 */
 514
 515void __weak arch_disable_smp_support(void) { }
 516
 517static int __init nosmp(char *str)
 518{
 519        setup_max_cpus = 0;
 520        arch_disable_smp_support();
 521
 522        return 0;
 523}
 524
 525early_param("nosmp", nosmp);
 526
 527/* this is hard limit */
 528static int __init nrcpus(char *str)
 529{
 530        int nr_cpus;
 531
 532        get_option(&str, &nr_cpus);
 533        if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
 534                nr_cpu_ids = nr_cpus;
 535
 536        return 0;
 537}
 538
 539early_param("nr_cpus", nrcpus);
 540
 541static int __init maxcpus(char *str)
 542{
 543        get_option(&str, &setup_max_cpus);
 544        if (setup_max_cpus == 0)
 545                arch_disable_smp_support();
 546
 547        return 0;
 548}
 549
 550early_param("maxcpus", maxcpus);
 551
 552/* Setup number of possible processor ids */
 553unsigned int nr_cpu_ids __read_mostly = NR_CPUS;
 554EXPORT_SYMBOL(nr_cpu_ids);
 555
 556/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
 557void __init setup_nr_cpu_ids(void)
 558{
 559        nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
 560}
 561
 562/* Called by boot processor to activate the rest. */
 563void __init smp_init(void)
 564{
 565        int num_nodes, num_cpus;
 566        unsigned int cpu;
 567
 568        idle_threads_init();
 569        cpuhp_threads_init();
 570
 571        pr_info("Bringing up secondary CPUs ...\n");
 572
 573        /* FIXME: This should be done in userspace --RR */
 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        num_nodes = num_online_nodes();
 582        num_cpus  = num_online_cpus();
 583        pr_info("Brought up %d node%s, %d CPU%s\n",
 584                num_nodes, (num_nodes > 1 ? "s" : ""),
 585                num_cpus,  (num_cpus  > 1 ? "s" : ""));
 586
 587        /* Final decision about SMT support */
 588        cpu_smt_check_topology();
 589        /* Any cleanup work */
 590        smp_cpus_done(setup_max_cpus);
 591}
 592
 593/*
 594 * Call a function on all processors.  May be used during early boot while
 595 * early_boot_irqs_disabled is set.  Use local_irq_save/restore() instead
 596 * of local_irq_disable/enable().
 597 */
 598int on_each_cpu(void (*func) (void *info), void *info, int wait)
 599{
 600        unsigned long flags;
 601        int ret = 0;
 602
 603        preempt_disable();
 604        ret = smp_call_function(func, info, wait);
 605        local_irq_save(flags);
 606        func(info);
 607        local_irq_restore(flags);
 608        preempt_enable();
 609        return ret;
 610}
 611EXPORT_SYMBOL(on_each_cpu);
 612
 613/**
 614 * on_each_cpu_mask(): Run a function on processors specified by
 615 * cpumask, which may include the local processor.
 616 * @mask: The set of cpus to run on (only runs on online subset).
 617 * @func: The function to run. This must be fast and non-blocking.
 618 * @info: An arbitrary pointer to pass to the function.
 619 * @wait: If true, wait (atomically) until function has completed
 620 *        on other CPUs.
 621 *
 622 * If @wait is true, then returns once @func has returned.
 623 *
 624 * You must not call this function with disabled interrupts or from a
 625 * hardware interrupt handler or from a bottom half handler.  The
 626 * exception is that it may be used during early boot while
 627 * early_boot_irqs_disabled is set.
 628 */
 629void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
 630                        void *info, bool wait)
 631{
 632        int cpu = get_cpu();
 633
 634        smp_call_function_many(mask, func, info, wait);
 635        if (cpumask_test_cpu(cpu, mask)) {
 636                unsigned long flags;
 637                local_irq_save(flags);
 638                func(info);
 639                local_irq_restore(flags);
 640        }
 641        put_cpu();
 642}
 643EXPORT_SYMBOL(on_each_cpu_mask);
 644
 645/*
 646 * on_each_cpu_cond(): Call a function on each processor for which
 647 * the supplied function cond_func returns true, optionally waiting
 648 * for all the required CPUs to finish. This may include the local
 649 * processor.
 650 * @cond_func:  A callback function that is passed a cpu id and
 651 *              the the info parameter. The function is called
 652 *              with preemption disabled. The function should
 653 *              return a blooean value indicating whether to IPI
 654 *              the specified CPU.
 655 * @func:       The function to run on all applicable CPUs.
 656 *              This must be fast and non-blocking.
 657 * @info:       An arbitrary pointer to pass to both functions.
 658 * @wait:       If true, wait (atomically) until function has
 659 *              completed on other CPUs.
 660 * @gfp_flags:  GFP flags to use when allocating the cpumask
 661 *              used internally by the function.
 662 *
 663 * The function might sleep if the GFP flags indicates a non
 664 * atomic allocation is allowed.
 665 *
 666 * Preemption is disabled to protect against CPUs going offline but not online.
 667 * CPUs going online during the call will not be seen or sent an IPI.
 668 *
 669 * You must not call this function with disabled interrupts or
 670 * from a hardware interrupt handler or from a bottom half handler.
 671 */
 672void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
 673                        smp_call_func_t func, void *info, bool wait,
 674                        gfp_t gfp_flags)
 675{
 676        cpumask_var_t cpus;
 677        int cpu, ret;
 678
 679        might_sleep_if(gfpflags_allow_blocking(gfp_flags));
 680
 681        if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) {
 682                preempt_disable();
 683                for_each_online_cpu(cpu)
 684                        if (cond_func(cpu, info))
 685                                cpumask_set_cpu(cpu, cpus);
 686                on_each_cpu_mask(cpus, func, info, wait);
 687                preempt_enable();
 688                free_cpumask_var(cpus);
 689        } else {
 690                /*
 691                 * No free cpumask, bother. No matter, we'll
 692                 * just have to IPI them one by one.
 693                 */
 694                preempt_disable();
 695                for_each_online_cpu(cpu)
 696                        if (cond_func(cpu, info)) {
 697                                ret = smp_call_function_single(cpu, func,
 698                                                                info, wait);
 699                                WARN_ON_ONCE(ret);
 700                        }
 701                preempt_enable();
 702        }
 703}
 704EXPORT_SYMBOL(on_each_cpu_cond);
 705
 706static void do_nothing(void *unused)
 707{
 708}
 709
 710/**
 711 * kick_all_cpus_sync - Force all cpus out of idle
 712 *
 713 * Used to synchronize the update of pm_idle function pointer. It's
 714 * called after the pointer is updated and returns after the dummy
 715 * callback function has been executed on all cpus. The execution of
 716 * the function can only happen on the remote cpus after they have
 717 * left the idle function which had been called via pm_idle function
 718 * pointer. So it's guaranteed that nothing uses the previous pointer
 719 * anymore.
 720 */
 721void kick_all_cpus_sync(void)
 722{
 723        /* Make sure the change is visible before we kick the cpus */
 724        smp_mb();
 725        smp_call_function(do_nothing, NULL, 1);
 726}
 727EXPORT_SYMBOL_GPL(kick_all_cpus_sync);
 728
 729/**
 730 * wake_up_all_idle_cpus - break all cpus out of idle
 731 * wake_up_all_idle_cpus try to break all cpus which is in idle state even
 732 * including idle polling cpus, for non-idle cpus, we will do nothing
 733 * for them.
 734 */
 735void wake_up_all_idle_cpus(void)
 736{
 737        int cpu;
 738
 739        preempt_disable();
 740        for_each_online_cpu(cpu) {
 741                if (cpu == smp_processor_id())
 742                        continue;
 743
 744                wake_up_if_idle(cpu);
 745        }
 746        preempt_enable();
 747}
 748EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
 749
 750/**
 751 * smp_call_on_cpu - Call a function on a specific cpu
 752 *
 753 * Used to call a function on a specific cpu and wait for it to return.
 754 * Optionally make sure the call is done on a specified physical cpu via vcpu
 755 * pinning in order to support virtualized environments.
 756 */
 757struct smp_call_on_cpu_struct {
 758        struct work_struct      work;
 759        struct completion       done;
 760        int                     (*func)(void *);
 761        void                    *data;
 762        int                     ret;
 763        int                     cpu;
 764};
 765
 766static void smp_call_on_cpu_callback(struct work_struct *work)
 767{
 768        struct smp_call_on_cpu_struct *sscs;
 769
 770        sscs = container_of(work, struct smp_call_on_cpu_struct, work);
 771        if (sscs->cpu >= 0)
 772                hypervisor_pin_vcpu(sscs->cpu);
 773        sscs->ret = sscs->func(sscs->data);
 774        if (sscs->cpu >= 0)
 775                hypervisor_pin_vcpu(-1);
 776
 777        complete(&sscs->done);
 778}
 779
 780int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
 781{
 782        struct smp_call_on_cpu_struct sscs = {
 783                .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
 784                .func = func,
 785                .data = par,
 786                .cpu  = phys ? cpu : -1,
 787        };
 788
 789        INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
 790
 791        if (cpu >= nr_cpu_ids || !cpu_online(cpu))
 792                return -ENXIO;
 793
 794        queue_work_on(cpu, system_wq, &sscs.work);
 795        wait_for_completion(&sscs.done);
 796
 797        return sscs.ret;
 798}
 799EXPORT_SYMBOL_GPL(smp_call_on_cpu);
 800