kernel/cpu.c

   1 /* CPU control.
   2  * (C) 2001, 2002, 2003, 2004 Rusty Russell
   3  *
   4  * This code is licenced under the GPL.
   5  */
   6 #include <linux/proc_fs.h>
   7 #include <linux/smp.h>
   8 #include <linux/init.h>
   9 #include <linux/notifier.h>
  10 #include <linux/sched.h>
  11 #include <linux/unistd.h>
  12 #include <linux/cpu.h>
  13 #include <linux/oom.h>
  14 #include <linux/rcupdate.h>
  15 #include <linux/export.h>
  16 #include <linux/bug.h>
  17 #include <linux/kthread.h>
  18 #include <linux/stop_machine.h>
  19 #include <linux/mutex.h>
  20 #include <linux/gfp.h>
  21 #include <linux/suspend.h>
  22
  23 #if defined(CONFIG_ARM_EXYNOS_MP_CPUFREQ) || defined(CONFIG_ARM_EXYNOS_SMP_CPUFREQ)
  24 #include <mach/cpufreq.h>
  25 #endif
  26
  27 #include "smpboot.h"
  28
  29 #ifdef CONFIG_SMP
  30 /* Serializes the updates to cpu_online_mask, cpu_present_mask */
  31 static DEFINE_MUTEX(cpu_add_remove_lock);
  32
  33 /*
  34  * The following two APIs (cpu_maps_update_begin/done) must be used when
  35  * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
  36  * The APIs cpu_notifier_register_begin/done() must be used to protect CPU
  37  * hotplug callback (un)registration performed using __register_cpu_notifier()
  38  * or __unregister_cpu_notifier().
  39  */
  40 void cpu_maps_update_begin(void)
  41 {
  42         mutex_lock(&cpu_add_remove_lock);
  43 }
  44 EXPORT_SYMBOL(cpu_notifier_register_begin);
  45
  46 void cpu_maps_update_done(void)
  47 {
  48         mutex_unlock(&cpu_add_remove_lock);
  49 }
  50 EXPORT_SYMBOL(cpu_notifier_register_done);
  51
  52 static RAW_NOTIFIER_HEAD(cpu_chain);
  53
  54 /* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
  55  * Should always be manipulated under cpu_add_remove_lock
  56  */
  57 static int cpu_hotplug_disabled;
  58
  59 #ifdef CONFIG_HOTPLUG_CPU
  60
  61 static struct {
  62         struct task_struct *active_writer;
  63         struct mutex lock; /* Synchronizes accesses to refcount, */
  64         /*
  65          * Also blocks the new readers during
  66          * an ongoing cpu hotplug operation.
  67          */
  68         int refcount;
  69 } cpu_hotplug = {
  70         .active_writer = NULL,
  71         .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
  72         .refcount = 0,
  73 };
  74
  75 void get_online_cpus(void)
  76 {
  77         might_sleep();
  78         if (cpu_hotplug.active_writer == current)
  79                 return;
  80         mutex_lock(&cpu_hotplug.lock);
  81         cpu_hotplug.refcount++;
  82         mutex_unlock(&cpu_hotplug.lock);
  83
  84 }
  85 EXPORT_SYMBOL_GPL(get_online_cpus);
  86
  87 void put_online_cpus(void)
  88 {
  89         if (cpu_hotplug.active_writer == current)
  90                 return;
  91         mutex_lock(&cpu_hotplug.lock);
  92
  93         if (WARN_ON(!cpu_hotplug.refcount))
  94                 cpu_hotplug.refcount++; /* try to fix things up */
  95
  96         if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
  97                 wake_up_process(cpu_hotplug.active_writer);
  98         mutex_unlock(&cpu_hotplug.lock);
  99
 100 }
 101 EXPORT_SYMBOL_GPL(put_online_cpus);
 102
 103 /*
 104  * This ensures that the hotplug operation can begin only when the
 105  * refcount goes to zero.
 106  *
 107  * Note that during a cpu-hotplug operation, the new readers, if any,
 108  * will be blocked by the cpu_hotplug.lock
 109  *
 110  * Since cpu_hotplug_begin() is always called after invoking
 111  * cpu_maps_update_begin(), we can be sure that only one writer is active.
 112  *
 113  * Note that theoretically, there is a possibility of a livelock:
 114  * - Refcount goes to zero, last reader wakes up the sleeping
 115  *   writer.
 116  * - Last reader unlocks the cpu_hotplug.lock.
 117  * - A new reader arrives at this moment, bumps up the refcount.
 118  * - The writer acquires the cpu_hotplug.lock finds the refcount
 119  *   non zero and goes to sleep again.
 120  *
 121  * However, this is very difficult to achieve in practice since
 122  * get_online_cpus() not an api which is called all that often.
 123  *
 124  */
 125 static void cpu_hotplug_begin(void)
 126 {
 127         cpu_hotplug.active_writer = current;
 128
 129         for (;;) {
 130                 mutex_lock(&cpu_hotplug.lock);
 131                 if (likely(!cpu_hotplug.refcount))
 132                         break;
 133                 __set_current_state(TASK_UNINTERRUPTIBLE);
 134                 mutex_unlock(&cpu_hotplug.lock);
 135                 schedule();
 136         }
 137 }
 138
 139 static void cpu_hotplug_done(void)
 140 {
 141         cpu_hotplug.active_writer = NULL;
 142         mutex_unlock(&cpu_hotplug.lock);
 143 }
 144
 145 /*
 146  * Wait for currently running CPU hotplug operations to complete (if any) and
 147  * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
 148  * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
 149  * hotplug path before performing hotplug operations. So acquiring that lock
 150  * guarantees mutual exclusion from any currently running hotplug operations.
 151  */
 152 void cpu_hotplug_disable(void)
 153 {
 154         cpu_maps_update_begin();
 155         cpu_hotplug_disabled = 1;
 156         cpu_maps_update_done();
 157 }
 158
 159 void cpu_hotplug_enable(void)
 160 {
 161         cpu_maps_update_begin();
 162         cpu_hotplug_disabled = 0;
 163         cpu_maps_update_done();
 164 }
 165
 166 #else /* #if CONFIG_HOTPLUG_CPU */
 167 static void cpu_hotplug_begin(void) {}
 168 static void cpu_hotplug_done(void) {}
 169 #endif  /* #else #if CONFIG_HOTPLUG_CPU */
 170
 171 /* Need to know about CPUs going up/down? */
 172 int __ref register_cpu_notifier(struct notifier_block *nb)
 173 {
 174         int ret;
 175         cpu_maps_update_begin();
 176         ret = raw_notifier_chain_register(&cpu_chain, nb);
 177         cpu_maps_update_done();
 178         return ret;
 179 }
 180
 181 int __ref __register_cpu_notifier(struct notifier_block *nb)
 182 {
 183         return raw_notifier_chain_register(&cpu_chain, nb);
 184 }
 185
 186 static int __cpu_notify(unsigned long val, void *v, int nr_to_call,
 187                         int *nr_calls)
 188 {
 189         int ret;
 190
 191         ret = __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,
 192                                         nr_calls);
 193
 194         return notifier_to_errno(ret);
 195 }
 196
 197 static int cpu_notify(unsigned long val, void *v)
 198 {
 199         return __cpu_notify(val, v, -1, NULL);
 200 }
 201
 202 #ifdef CONFIG_HOTPLUG_CPU
 203
 204 static void cpu_notify_nofail(unsigned long val, void *v)
 205 {
 206         BUG_ON(cpu_notify(val, v));
 207 }
 208 EXPORT_SYMBOL(register_cpu_notifier);
 209 EXPORT_SYMBOL(__register_cpu_notifier);
 210
 211 void __ref unregister_cpu_notifier(struct notifier_block *nb)
 212 {
 213         cpu_maps_update_begin();
 214         raw_notifier_chain_unregister(&cpu_chain, nb);
 215         cpu_maps_update_done();
 216 }
 217 EXPORT_SYMBOL(unregister_cpu_notifier);
 218
 219 void __ref __unregister_cpu_notifier(struct notifier_block *nb)
 220 {
 221         raw_notifier_chain_unregister(&cpu_chain, nb);
 222 }
 223 EXPORT_SYMBOL(__unregister_cpu_notifier);
 224
 225 /**
 226  * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
 227  * @cpu: a CPU id
 228  *
 229  * This function walks all processes, finds a valid mm struct for each one and
 230  * then clears a corresponding bit in mm's cpumask.  While this all sounds
 231  * trivial, there are various non-obvious corner cases, which this function
 232  * tries to solve in a safe manner.
 233  *
 234  * Also note that the function uses a somewhat relaxed locking scheme, so it may
 235  * be called only for an already offlined CPU.
 236  */
 237 void clear_tasks_mm_cpumask(int cpu)
 238 {
 239         struct task_struct *p;
 240
 241         /*
 242          * This function is called after the cpu is taken down and marked
 243          * offline, so its not like new tasks will ever get this cpu set in
 244          * their mm mask. -- Peter Zijlstra
 245          * Thus, we may use rcu_read_lock() here, instead of grabbing
 246          * full-fledged tasklist_lock.
 247          */
 248         WARN_ON(cpu_online(cpu));
 249         rcu_read_lock();
 250         for_each_process(p) {
 251                 struct task_struct *t;
 252
 253                 /*
 254                  * Main thread might exit, but other threads may still have
 255                  * a valid mm. Find one.
 256                  */
 257                 t = find_lock_task_mm(p);
 258                 if (!t)
 259                         continue;
 260                 cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
 261                 task_unlock(t);
 262         }
 263         rcu_read_unlock();
 264 }
 265
 266 static inline void check_for_tasks(int cpu)
 267 {
 268         struct task_struct *p;
 269         cputime_t utime, stime;
 270
 271         write_lock_irq(&tasklist_lock);
 272         for_each_process(p) {
 273                 task_cputime(p, &utime, &stime);
 274                 if (task_cpu(p) == cpu && p->state == TASK_RUNNING &&
 275                     (utime || stime))
 276                         printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d "
 277                                 "(state = %ld, flags = %x)\n",
 278                                 p->comm, task_pid_nr(p), cpu,
 279                                 p->state, p->flags);
 280         }
 281         write_unlock_irq(&tasklist_lock);
 282 }
 283
 284 struct take_cpu_down_param {
 285         unsigned long mod;
 286         void *hcpu;
 287 };
 288
 289 /* Take this CPU down. */
 290 static int __ref take_cpu_down(void *_param)
 291 {
 292         struct take_cpu_down_param *param = _param;
 293         int err;
 294
 295         /* Ensure this CPU doesn't handle any more interrupts. */
 296         err = __cpu_disable();
 297         if (err < 0)
 298                 return err;
 299
 300         cpu_notify(CPU_DYING | param->mod, param->hcpu);
 301         /* Park the stopper thread */
 302         kthread_park(current);
 303         return 0;
 304 }
 305
 306 /* Requires cpu_add_remove_lock to be held */
 307 static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
 308 {
 309         int err, nr_calls = 0;
 310         void *hcpu = (void *)(long)cpu;
 311         unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
 312         struct take_cpu_down_param tcd_param = {
 313                 .mod = mod,
 314                 .hcpu = hcpu,
 315         };
 316
 317         if (num_online_cpus() == 1)
 318                 return -EBUSY;
 319
 320         if (!cpu_online(cpu))
 321                 return -EINVAL;
 322
 323         cpu_hotplug_begin();
 324
 325         err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
 326         if (err) {
 327                 nr_calls--;
 328                 __cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
 329                 printk("%s: attempt to take down CPU %u failed\n",
 330                                 __func__, cpu);
 331                 goto out_release;
 332         }
 333         smpboot_park_threads(cpu);
 334
 335         err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
 336         if (err) {
 337                 /* CPU didn't die: tell everyone.  Can't complain. */
 338                 smpboot_unpark_threads(cpu);
 339                 cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
 340                 goto out_release;
 341         }
 342         BUG_ON(cpu_online(cpu));
 343
 344         /*
 345          * The migration_call() CPU_DYING callback will have removed all
 346          * runnable tasks from the cpu, there's only the idle task left now
 347          * that the migration thread is done doing the stop_machine thing.
 348          *
 349          * Wait for the stop thread to go away.
 350          */
 351         while (!idle_cpu(cpu))
 352                 cpu_relax();
 353
 354         /* This actually kills the CPU. */
 355         __cpu_die(cpu);
 356
 357         /* CPU is completely dead: tell everyone.  Too late to complain. */
 358         cpu_notify_nofail(CPU_DEAD | mod, hcpu);
 359
 360         check_for_tasks(cpu);
 361
 362 out_release:
 363         cpu_hotplug_done();
 364         if (!err)
 365                 cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
 366         return err;
 367 }
 368
 369 int __ref cpu_down(unsigned int cpu)
 370 {
 371         int err;
 372
 373         cpu_maps_update_begin();
 374
 375         if (cpu_hotplug_disabled) {
 376                 err = -EBUSY;
 377                 goto out;
 378         }
 379
 380         err = _cpu_down(cpu, 0);
 381
 382 out:
 383         cpu_maps_update_done();
 384         return err;
 385 }
 386 EXPORT_SYMBOL(cpu_down);
 387 #endif /*CONFIG_HOTPLUG_CPU*/
 388
 389 /* Requires cpu_add_remove_lock to be held */
 390 static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
 391 {
 392         int ret, nr_calls = 0;
 393         void *hcpu = (void *)(long)cpu;
 394         unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
 395         struct task_struct *idle;
 396
 397         cpu_hotplug_begin();
 398
 399         if (cpu_online(cpu) || !cpu_present(cpu)) {
 400                 ret = -EINVAL;
 401                 goto out;
 402         }
 403
 404         idle = idle_thread_get(cpu);
 405         if (IS_ERR(idle)) {
 406                 ret = PTR_ERR(idle);
 407                 goto out;
 408         }
 409
 410         ret = smpboot_create_threads(cpu);
 411         if (ret)
 412                 goto out;
 413
 414         ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
 415         if (ret) {
 416                 nr_calls--;
 417                 printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",
 418                                 __func__, cpu);
 419                 goto out_notify;
 420         }
 421
 422         /* Arch-specific enabling code. */
 423         ret = __cpu_up(cpu, idle);
 424         if (ret != 0)
 425                 goto out_notify;
 426         BUG_ON(!cpu_online(cpu));
 427
 428         /* Wake the per cpu threads */
 429         smpboot_unpark_threads(cpu);
 430
 431         /* Now call notifier in preparation. */
 432         cpu_notify(CPU_ONLINE | mod, hcpu);
 433
 434 out_notify:
 435         if (ret != 0)
 436                 __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
 437 out:
 438         cpu_hotplug_done();
 439
 440         return ret;
 441 }
 442
 443 int __cpuinit cpu_up(unsigned int cpu)
 444 {
 445         int err = 0;
 446
 447 #ifdef  CONFIG_MEMORY_HOTPLUG
 448         int nid;
 449         pg_data_t       *pgdat;
 450 #endif
 451
 452         if (!cpu_possible(cpu)) {
 453                 printk(KERN_ERR "can't online cpu %d because it is not "
 454                         "configured as may-hotadd at boot time\n", cpu);
 455 #if defined(CONFIG_IA64)
 456                 printk(KERN_ERR "please check additional_cpus= boot "
 457                                 "parameter\n");
 458 #endif
 459                 return -EINVAL;
 460         }
 461
 462 #ifdef  CONFIG_MEMORY_HOTPLUG
 463         nid = cpu_to_node(cpu);
 464         if (!node_online(nid)) {
 465                 err = mem_online_node(nid);
 466                 if (err)
 467                         return err;
 468         }
 469
 470         pgdat = NODE_DATA(nid);
 471         if (!pgdat) {
 472                 printk(KERN_ERR
 473                         "Can't online cpu %d due to NULL pgdat\n", cpu);
 474                 return -ENOMEM;
 475         }
 476
 477         if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
 478                 mutex_lock(&zonelists_mutex);
 479                 build_all_zonelists(NULL, NULL);
 480                 mutex_unlock(&zonelists_mutex);
 481         }
 482 #endif
 483
 484         cpu_maps_update_begin();
 485
 486         if (cpu_hotplug_disabled) {
 487                 err = -EBUSY;
 488                 goto out;
 489         }
 490
 491         err = _cpu_up(cpu, 0);
 492
 493 out:
 494         cpu_maps_update_done();
 495         return err;
 496 }
 497 EXPORT_SYMBOL_GPL(cpu_up);
 498
 499 #ifdef CONFIG_PM_SLEEP_SMP
 500 static cpumask_var_t frozen_cpus;
 501
 502 int disable_nonboot_cpus(void)
 503 {
 504         int cpu, first_cpu, error = 0;
 505 #if defined(CONFIG_ARM_EXYNOS_MP_CPUFREQ) || defined(CONFIG_ARM_EXYNOS_SMP_CPUFREQ)
 506         int lated_cpu;
 507
 508         if (exynos_boot_cluster == CL_ZERO)
 509                 lated_cpu = NR_CLUST0_CPUS;
 510         else
 511                 lated_cpu = NR_CLUST1_CPUS;
 512 #endif
 513
 514         cpu_maps_update_begin();
 515         first_cpu = cpumask_first(cpu_online_mask);
 516         /*
 517          * We take down all of the non-boot CPUs in one shot to avoid races
 518          * with the userspace trying to use the CPU hotplug at the same time
 519          */
 520         cpumask_clear(frozen_cpus);
 521
 522         printk("Disabling non-boot CPUs ...\n");
 523         for_each_online_cpu(cpu) {
 524 #if defined(CONFIG_ARM_EXYNOS_MP_CPUFREQ) || defined(CONFIG_ARM_EXYNOS_SMP_CPUFREQ)
 525                 if (cpu == first_cpu || cpu == lated_cpu)
 526 #else
 527                 if (cpu == first_cpu)
 528 #endif
 529                         continue;
 530                 error = _cpu_down(cpu, 1);
 531                 if (!error)
 532                         cpumask_set_cpu(cpu, frozen_cpus);
 533                 else {
 534                         printk(KERN_ERR "Error taking CPU%d down: %d\n",
 535                                 cpu, error);
 536                         break;
 537                 }
 538         }
 539
 540 #if defined(CONFIG_ARM_EXYNOS_MP_CPUFREQ) || defined(CONFIG_ARM_EXYNOS_SMP_CPUFREQ)
 541         if (num_online_cpus() > 1) {
 542                 error = _cpu_down(lated_cpu, 1);
 543                 if (!error)
 544                         cpumask_set_cpu(lated_cpu, frozen_cpus);
 545                 else
 546                         printk(KERN_ERR "Error taking CPU%d down: %d\n",
 547                                 lated_cpu, error);
 548         }
 549 #endif
 550         if (!error) {
 551                 BUG_ON(num_online_cpus() > 1);
 552                 /* Make sure the CPUs won't be enabled by someone else */
 553                 cpu_hotplug_disabled = 1;
 554         } else {
 555                 printk(KERN_ERR "Non-boot CPUs are not disabled\n");
 556         }
 557         cpu_maps_update_done();
 558         return error;
 559 }
 560
 561 void __weak arch_enable_nonboot_cpus_begin(void)
 562 {
 563 }
 564
 565 void __weak arch_enable_nonboot_cpus_end(void)
 566 {
 567 }
 568
 569 #if defined(CONFIG_SCHED_HMP) && defined(CONFIG_EXYNOS5_DYNAMIC_CPU_HOTPLUG)
 570 extern struct cpumask hmp_slow_cpu_mask;
 571 extern int disable_dm_hotplug_before_suspend;
 572 #endif
 573
 574 void __ref enable_nonboot_cpus(void)
 575 {
 576         int cpu, error;
 577
 578         /* Allow everyone to use the CPU hotplug again */
 579         cpu_maps_update_begin();
 580         cpu_hotplug_disabled = 0;
 581         if (cpumask_empty(frozen_cpus))
 582                 goto out;
 583
 584         printk(KERN_INFO "Enabling non-boot CPUs ...\n");
 585
 586         arch_enable_nonboot_cpus_begin();
 587
 588 #if defined(CONFIG_SCHED_HMP) && defined(CONFIG_EXYNOS5_DYNAMIC_CPU_HOTPLUG)
 589         if (!disable_dm_hotplug_before_suspend)
 590                 cpumask_and(frozen_cpus, frozen_cpus, &hmp_slow_cpu_mask);
 591 #endif
 592
 593         for_each_cpu(cpu, frozen_cpus) {
 594                 error = _cpu_up(cpu, 1);
 595                 if (!error) {
 596                         printk(KERN_INFO "CPU%d is up\n", cpu);
 597                         continue;
 598                 }
 599                 printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
 600         }
 601
 602         arch_enable_nonboot_cpus_end();
 603
 604         cpumask_clear(frozen_cpus);
 605 out:
 606         cpu_maps_update_done();
 607 }
 608
 609 static int __init alloc_frozen_cpus(void)
 610 {
 611         if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
 612                 return -ENOMEM;
 613         return 0;
 614 }
 615 core_initcall(alloc_frozen_cpus);
 616
 617 /*
 618  * When callbacks for CPU hotplug notifications are being executed, we must
 619  * ensure that the state of the system with respect to the tasks being frozen
 620  * or not, as reported by the notification, remains unchanged *throughout the
 621  * duration* of the execution of the callbacks.
 622  * Hence we need to prevent the freezer from racing with regular CPU hotplug.
 623  *
 624  * This synchronization is implemented by mutually excluding regular CPU
 625  * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
 626  * Hibernate notifications.
 627  */
 628 static int
 629 cpu_hotplug_pm_callback(struct notifier_block *nb,
 630                         unsigned long action, void *ptr)
 631 {
 632         switch (action) {
 633
 634         case PM_SUSPEND_PREPARE:
 635         case PM_HIBERNATION_PREPARE:
 636                 cpu_hotplug_disable();
 637                 break;
 638
 639         case PM_POST_SUSPEND:
 640         case PM_POST_HIBERNATION:
 641                 cpu_hotplug_enable();
 642                 break;
 643
 644         default:
 645                 return NOTIFY_DONE;
 646         }
 647
 648         return NOTIFY_OK;
 649 }
 650
 651
 652 static int __init cpu_hotplug_pm_sync_init(void)
 653 {
 654         /*
 655          * cpu_hotplug_pm_callback has higher priority than x86
 656          * bsp_pm_callback which depends on cpu_hotplug_pm_callback
 657          * to disable cpu hotplug to avoid cpu hotplug race.
 658          */
 659         pm_notifier(cpu_hotplug_pm_callback, 0);
 660         return 0;
 661 }
 662 core_initcall(cpu_hotplug_pm_sync_init);
 663
 664 #endif /* CONFIG_PM_SLEEP_SMP */
 665
 666 /**
 667  * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
 668  * @cpu: cpu that just started
 669  *
 670  * This function calls the cpu_chain notifiers with CPU_STARTING.
 671  * It must be called by the arch code on the new cpu, before the new cpu
 672  * enables interrupts and before the "boot" cpu returns from __cpu_up().
 673  */
 674 void __cpuinit notify_cpu_starting(unsigned int cpu)
 675 {
 676         unsigned long val = CPU_STARTING;
 677
 678 #ifdef CONFIG_PM_SLEEP_SMP
 679         if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
 680                 val = CPU_STARTING_FROZEN;
 681 #endif /* CONFIG_PM_SLEEP_SMP */
 682         cpu_notify(val, (void *)(long)cpu);
 683 }
 684
 685 #endif /* CONFIG_SMP */
 686
 687 /*
 688  * cpu_bit_bitmap[] is a special, "compressed" data structure that
 689  * represents all NR_CPUS bits binary values of 1<<nr.
 690  *
 691  * It is used by cpumask_of() to get a constant address to a CPU
 692  * mask value that has a single bit set only.
 693  */
 694
 695 /* cpu_bit_bitmap[0] is empty - so we can back into it */
 696 #define MASK_DECLARE_1(x)       [x+1][0] = (1UL << (x))
 697 #define MASK_DECLARE_2(x)       MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
 698 #define MASK_DECLARE_4(x)       MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
 699 #define MASK_DECLARE_8(x)       MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
 700
 701 const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
 702
 703         MASK_DECLARE_8(0),      MASK_DECLARE_8(8),
 704         MASK_DECLARE_8(16),     MASK_DECLARE_8(24),
 705 #if BITS_PER_LONG > 32
 706         MASK_DECLARE_8(32),     MASK_DECLARE_8(40),
 707         MASK_DECLARE_8(48),     MASK_DECLARE_8(56),
 708 #endif
 709 };
 710 EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
 711
 712 const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
 713 EXPORT_SYMBOL(cpu_all_bits);
 714
 715 #ifdef CONFIG_INIT_ALL_POSSIBLE
 716 static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
 717         = CPU_BITS_ALL;
 718 #else
 719 static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
 720 #endif
 721 const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
 722 EXPORT_SYMBOL(cpu_possible_mask);
 723
 724 static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
 725 const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
 726 EXPORT_SYMBOL(cpu_online_mask);
 727
 728 static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
 729 const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
 730 EXPORT_SYMBOL(cpu_present_mask);
 731
 732 static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
 733 const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
 734 EXPORT_SYMBOL(cpu_active_mask);
 735
 736 void set_cpu_possible(unsigned int cpu, bool possible)
 737 {
 738         if (possible)
 739                 cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));
 740         else
 741                 cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
 742 }
 743
 744 void set_cpu_present(unsigned int cpu, bool present)
 745 {
 746         if (present)
 747                 cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));
 748         else
 749                 cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));
 750 }
 751
 752 void set_cpu_online(unsigned int cpu, bool online)
 753 {
 754         if (online) {
 755                 cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
 756                 cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
 757         } else {
 758                 cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
 759         }
 760 }
 761
 762 void set_cpu_active(unsigned int cpu, bool active)
 763 {
 764         if (active)
 765                 cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
 766         else
 767                 cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits));
 768 }
 769
 770 void init_cpu_present(const struct cpumask *src)
 771 {
 772         cpumask_copy(to_cpumask(cpu_present_bits), src);
 773 }
 774
 775 void init_cpu_possible(const struct cpumask *src)
 776 {
 777         cpumask_copy(to_cpumask(cpu_possible_bits), src);
 778 }
 779
 780 void init_cpu_online(const struct cpumask *src)
 781 {
 782         cpumask_copy(to_cpumask(cpu_online_bits), src);
 783 }
 784
 785 static ATOMIC_NOTIFIER_HEAD(idle_notifier);
 786
 787 void idle_notifier_register(struct notifier_block *n)
 788 {
 789         atomic_notifier_chain_register(&idle_notifier, n);
 790 }
 791 EXPORT_SYMBOL_GPL(idle_notifier_register);
 792
 793 void idle_notifier_unregister(struct notifier_block *n)
 794 {
 795         atomic_notifier_chain_unregister(&idle_notifier, n);
 796 }
 797 EXPORT_SYMBOL_GPL(idle_notifier_unregister);
 798
 799 void idle_notifier_call_chain(unsigned long val)
 800 {
 801         atomic_notifier_call_chain(&idle_notifier, val, NULL);
 802 }
 803 EXPORT_SYMBOL_GPL(idle_notifier_call_chain);