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