linux/include/linux/cpumask.h
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   1#ifndef __LINUX_CPUMASK_H
   2#define __LINUX_CPUMASK_H
   3
   4/*
   5 * Cpumasks provide a bitmap suitable for representing the
   6 * set of CPU's in a system, one bit position per CPU number.  In general,
   7 * only nr_cpu_ids (<= NR_CPUS) bits are valid.
   8 */
   9#include <linux/kernel.h>
  10#include <linux/threads.h>
  11#include <linux/bitmap.h>
  12#include <linux/bug.h>
  13
  14/* Don't assign or return these: may not be this big! */
  15typedef struct cpumask { DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t;
  16
  17/**
  18 * cpumask_bits - get the bits in a cpumask
  19 * @maskp: the struct cpumask *
  20 *
  21 * You should only assume nr_cpu_ids bits of this mask are valid.  This is
  22 * a macro so it's const-correct.
  23 */
  24#define cpumask_bits(maskp) ((maskp)->bits)
  25
  26/**
  27 * cpumask_pr_args - printf args to output a cpumask
  28 * @maskp: cpumask to be printed
  29 *
  30 * Can be used to provide arguments for '%*pb[l]' when printing a cpumask.
  31 */
  32#define cpumask_pr_args(maskp)          nr_cpu_ids, cpumask_bits(maskp)
  33
  34#if NR_CPUS == 1
  35#define nr_cpu_ids              1
  36#else
  37extern int nr_cpu_ids;
  38#endif
  39
  40#ifdef CONFIG_CPUMASK_OFFSTACK
  41/* Assuming NR_CPUS is huge, a runtime limit is more efficient.  Also,
  42 * not all bits may be allocated. */
  43#define nr_cpumask_bits nr_cpu_ids
  44#else
  45#define nr_cpumask_bits NR_CPUS
  46#endif
  47
  48/*
  49 * The following particular system cpumasks and operations manage
  50 * possible, present, active and online cpus.
  51 *
  52 *     cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
  53 *     cpu_present_mask - has bit 'cpu' set iff cpu is populated
  54 *     cpu_online_mask  - has bit 'cpu' set iff cpu available to scheduler
  55 *     cpu_active_mask  - has bit 'cpu' set iff cpu available to migration
  56 *
  57 *  If !CONFIG_HOTPLUG_CPU, present == possible, and active == online.
  58 *
  59 *  The cpu_possible_mask is fixed at boot time, as the set of CPU id's
  60 *  that it is possible might ever be plugged in at anytime during the
  61 *  life of that system boot.  The cpu_present_mask is dynamic(*),
  62 *  representing which CPUs are currently plugged in.  And
  63 *  cpu_online_mask is the dynamic subset of cpu_present_mask,
  64 *  indicating those CPUs available for scheduling.
  65 *
  66 *  If HOTPLUG is enabled, then cpu_possible_mask is forced to have
  67 *  all NR_CPUS bits set, otherwise it is just the set of CPUs that
  68 *  ACPI reports present at boot.
  69 *
  70 *  If HOTPLUG is enabled, then cpu_present_mask varies dynamically,
  71 *  depending on what ACPI reports as currently plugged in, otherwise
  72 *  cpu_present_mask is just a copy of cpu_possible_mask.
  73 *
  74 *  (*) Well, cpu_present_mask is dynamic in the hotplug case.  If not
  75 *      hotplug, it's a copy of cpu_possible_mask, hence fixed at boot.
  76 *
  77 * Subtleties:
  78 * 1) UP arch's (NR_CPUS == 1, CONFIG_SMP not defined) hardcode
  79 *    assumption that their single CPU is online.  The UP
  80 *    cpu_{online,possible,present}_masks are placebos.  Changing them
  81 *    will have no useful affect on the following num_*_cpus()
  82 *    and cpu_*() macros in the UP case.  This ugliness is a UP
  83 *    optimization - don't waste any instructions or memory references
  84 *    asking if you're online or how many CPUs there are if there is
  85 *    only one CPU.
  86 */
  87
  88extern const struct cpumask *const cpu_possible_mask;
  89extern const struct cpumask *const cpu_online_mask;
  90extern const struct cpumask *const cpu_present_mask;
  91extern const struct cpumask *const cpu_active_mask;
  92
  93#if NR_CPUS > 1
  94#define num_online_cpus()       cpumask_weight(cpu_online_mask)
  95#define num_possible_cpus()     cpumask_weight(cpu_possible_mask)
  96#define num_present_cpus()      cpumask_weight(cpu_present_mask)
  97#define num_active_cpus()       cpumask_weight(cpu_active_mask)
  98#define cpu_online(cpu)         cpumask_test_cpu((cpu), cpu_online_mask)
  99#define cpu_possible(cpu)       cpumask_test_cpu((cpu), cpu_possible_mask)
 100#define cpu_present(cpu)        cpumask_test_cpu((cpu), cpu_present_mask)
 101#define cpu_active(cpu)         cpumask_test_cpu((cpu), cpu_active_mask)
 102#else
 103#define num_online_cpus()       1U
 104#define num_possible_cpus()     1U
 105#define num_present_cpus()      1U
 106#define num_active_cpus()       1U
 107#define cpu_online(cpu)         ((cpu) == 0)
 108#define cpu_possible(cpu)       ((cpu) == 0)
 109#define cpu_present(cpu)        ((cpu) == 0)
 110#define cpu_active(cpu)         ((cpu) == 0)
 111#endif
 112
 113/* verify cpu argument to cpumask_* operators */
 114static inline unsigned int cpumask_check(unsigned int cpu)
 115{
 116#ifdef CONFIG_DEBUG_PER_CPU_MAPS
 117        WARN_ON_ONCE(cpu >= nr_cpumask_bits);
 118#endif /* CONFIG_DEBUG_PER_CPU_MAPS */
 119        return cpu;
 120}
 121
 122#if NR_CPUS == 1
 123/* Uniprocessor.  Assume all masks are "1". */
 124static inline unsigned int cpumask_first(const struct cpumask *srcp)
 125{
 126        return 0;
 127}
 128
 129/* Valid inputs for n are -1 and 0. */
 130static inline unsigned int cpumask_next(int n, const struct cpumask *srcp)
 131{
 132        return n+1;
 133}
 134
 135static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
 136{
 137        return n+1;
 138}
 139
 140static inline unsigned int cpumask_next_and(int n,
 141                                            const struct cpumask *srcp,
 142                                            const struct cpumask *andp)
 143{
 144        return n+1;
 145}
 146
 147/* cpu must be a valid cpu, ie 0, so there's no other choice. */
 148static inline unsigned int cpumask_any_but(const struct cpumask *mask,
 149                                           unsigned int cpu)
 150{
 151        return 1;
 152}
 153
 154static inline unsigned int cpumask_local_spread(unsigned int i, int node)
 155{
 156        return 0;
 157}
 158
 159#define for_each_cpu(cpu, mask)                 \
 160        for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
 161#define for_each_cpu_not(cpu, mask)             \
 162        for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
 163#define for_each_cpu_and(cpu, mask, and)        \
 164        for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask, (void)and)
 165#else
 166/**
 167 * cpumask_first - get the first cpu in a cpumask
 168 * @srcp: the cpumask pointer
 169 *
 170 * Returns >= nr_cpu_ids if no cpus set.
 171 */
 172static inline unsigned int cpumask_first(const struct cpumask *srcp)
 173{
 174        return find_first_bit(cpumask_bits(srcp), nr_cpumask_bits);
 175}
 176
 177/**
 178 * cpumask_next - get the next cpu in a cpumask
 179 * @n: the cpu prior to the place to search (ie. return will be > @n)
 180 * @srcp: the cpumask pointer
 181 *
 182 * Returns >= nr_cpu_ids if no further cpus set.
 183 */
 184static inline unsigned int cpumask_next(int n, const struct cpumask *srcp)
 185{
 186        /* -1 is a legal arg here. */
 187        if (n != -1)
 188                cpumask_check(n);
 189        return find_next_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
 190}
 191
 192/**
 193 * cpumask_next_zero - get the next unset cpu in a cpumask
 194 * @n: the cpu prior to the place to search (ie. return will be > @n)
 195 * @srcp: the cpumask pointer
 196 *
 197 * Returns >= nr_cpu_ids if no further cpus unset.
 198 */
 199static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
 200{
 201        /* -1 is a legal arg here. */
 202        if (n != -1)
 203                cpumask_check(n);
 204        return find_next_zero_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
 205}
 206
 207int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
 208int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
 209unsigned int cpumask_local_spread(unsigned int i, int node);
 210
 211/**
 212 * for_each_cpu - iterate over every cpu in a mask
 213 * @cpu: the (optionally unsigned) integer iterator
 214 * @mask: the cpumask pointer
 215 *
 216 * After the loop, cpu is >= nr_cpu_ids.
 217 */
 218#define for_each_cpu(cpu, mask)                         \
 219        for ((cpu) = -1;                                \
 220                (cpu) = cpumask_next((cpu), (mask)),    \
 221                (cpu) < nr_cpu_ids;)
 222
 223/**
 224 * for_each_cpu_not - iterate over every cpu in a complemented mask
 225 * @cpu: the (optionally unsigned) integer iterator
 226 * @mask: the cpumask pointer
 227 *
 228 * After the loop, cpu is >= nr_cpu_ids.
 229 */
 230#define for_each_cpu_not(cpu, mask)                             \
 231        for ((cpu) = -1;                                        \
 232                (cpu) = cpumask_next_zero((cpu), (mask)),       \
 233                (cpu) < nr_cpu_ids;)
 234
 235/**
 236 * for_each_cpu_and - iterate over every cpu in both masks
 237 * @cpu: the (optionally unsigned) integer iterator
 238 * @mask: the first cpumask pointer
 239 * @and: the second cpumask pointer
 240 *
 241 * This saves a temporary CPU mask in many places.  It is equivalent to:
 242 *      struct cpumask tmp;
 243 *      cpumask_and(&tmp, &mask, &and);
 244 *      for_each_cpu(cpu, &tmp)
 245 *              ...
 246 *
 247 * After the loop, cpu is >= nr_cpu_ids.
 248 */
 249#define for_each_cpu_and(cpu, mask, and)                                \
 250        for ((cpu) = -1;                                                \
 251                (cpu) = cpumask_next_and((cpu), (mask), (and)),         \
 252                (cpu) < nr_cpu_ids;)
 253#endif /* SMP */
 254
 255#define CPU_BITS_NONE                                           \
 256{                                                               \
 257        [0 ... BITS_TO_LONGS(NR_CPUS)-1] = 0UL                  \
 258}
 259
 260#define CPU_BITS_CPU0                                           \
 261{                                                               \
 262        [0] =  1UL                                              \
 263}
 264
 265/**
 266 * cpumask_set_cpu - set a cpu in a cpumask
 267 * @cpu: cpu number (< nr_cpu_ids)
 268 * @dstp: the cpumask pointer
 269 */
 270static inline void cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
 271{
 272        set_bit(cpumask_check(cpu), cpumask_bits(dstp));
 273}
 274
 275/**
 276 * cpumask_clear_cpu - clear a cpu in a cpumask
 277 * @cpu: cpu number (< nr_cpu_ids)
 278 * @dstp: the cpumask pointer
 279 */
 280static inline void cpumask_clear_cpu(int cpu, struct cpumask *dstp)
 281{
 282        clear_bit(cpumask_check(cpu), cpumask_bits(dstp));
 283}
 284
 285/**
 286 * cpumask_test_cpu - test for a cpu in a cpumask
 287 * @cpu: cpu number (< nr_cpu_ids)
 288 * @cpumask: the cpumask pointer
 289 *
 290 * Returns 1 if @cpu is set in @cpumask, else returns 0
 291 */
 292static inline int cpumask_test_cpu(int cpu, const struct cpumask *cpumask)
 293{
 294        return test_bit(cpumask_check(cpu), cpumask_bits((cpumask)));
 295}
 296
 297/**
 298 * cpumask_test_and_set_cpu - atomically test and set a cpu in a cpumask
 299 * @cpu: cpu number (< nr_cpu_ids)
 300 * @cpumask: the cpumask pointer
 301 *
 302 * Returns 1 if @cpu is set in old bitmap of @cpumask, else returns 0
 303 *
 304 * test_and_set_bit wrapper for cpumasks.
 305 */
 306static inline int cpumask_test_and_set_cpu(int cpu, struct cpumask *cpumask)
 307{
 308        return test_and_set_bit(cpumask_check(cpu), cpumask_bits(cpumask));
 309}
 310
 311/**
 312 * cpumask_test_and_clear_cpu - atomically test and clear a cpu in a cpumask
 313 * @cpu: cpu number (< nr_cpu_ids)
 314 * @cpumask: the cpumask pointer
 315 *
 316 * Returns 1 if @cpu is set in old bitmap of @cpumask, else returns 0
 317 *
 318 * test_and_clear_bit wrapper for cpumasks.
 319 */
 320static inline int cpumask_test_and_clear_cpu(int cpu, struct cpumask *cpumask)
 321{
 322        return test_and_clear_bit(cpumask_check(cpu), cpumask_bits(cpumask));
 323}
 324
 325/**
 326 * cpumask_setall - set all cpus (< nr_cpu_ids) in a cpumask
 327 * @dstp: the cpumask pointer
 328 */
 329static inline void cpumask_setall(struct cpumask *dstp)
 330{
 331        bitmap_fill(cpumask_bits(dstp), nr_cpumask_bits);
 332}
 333
 334/**
 335 * cpumask_clear - clear all cpus (< nr_cpu_ids) in a cpumask
 336 * @dstp: the cpumask pointer
 337 */
 338static inline void cpumask_clear(struct cpumask *dstp)
 339{
 340        bitmap_zero(cpumask_bits(dstp), nr_cpumask_bits);
 341}
 342
 343/**
 344 * cpumask_and - *dstp = *src1p & *src2p
 345 * @dstp: the cpumask result
 346 * @src1p: the first input
 347 * @src2p: the second input
 348 *
 349 * If *@dstp is empty, returns 0, else returns 1
 350 */
 351static inline int cpumask_and(struct cpumask *dstp,
 352                               const struct cpumask *src1p,
 353                               const struct cpumask *src2p)
 354{
 355        return bitmap_and(cpumask_bits(dstp), cpumask_bits(src1p),
 356                                       cpumask_bits(src2p), nr_cpumask_bits);
 357}
 358
 359/**
 360 * cpumask_or - *dstp = *src1p | *src2p
 361 * @dstp: the cpumask result
 362 * @src1p: the first input
 363 * @src2p: the second input
 364 */
 365static inline void cpumask_or(struct cpumask *dstp, const struct cpumask *src1p,
 366                              const struct cpumask *src2p)
 367{
 368        bitmap_or(cpumask_bits(dstp), cpumask_bits(src1p),
 369                                      cpumask_bits(src2p), nr_cpumask_bits);
 370}
 371
 372/**
 373 * cpumask_xor - *dstp = *src1p ^ *src2p
 374 * @dstp: the cpumask result
 375 * @src1p: the first input
 376 * @src2p: the second input
 377 */
 378static inline void cpumask_xor(struct cpumask *dstp,
 379                               const struct cpumask *src1p,
 380                               const struct cpumask *src2p)
 381{
 382        bitmap_xor(cpumask_bits(dstp), cpumask_bits(src1p),
 383                                       cpumask_bits(src2p), nr_cpumask_bits);
 384}
 385
 386/**
 387 * cpumask_andnot - *dstp = *src1p & ~*src2p
 388 * @dstp: the cpumask result
 389 * @src1p: the first input
 390 * @src2p: the second input
 391 *
 392 * If *@dstp is empty, returns 0, else returns 1
 393 */
 394static inline int cpumask_andnot(struct cpumask *dstp,
 395                                  const struct cpumask *src1p,
 396                                  const struct cpumask *src2p)
 397{
 398        return bitmap_andnot(cpumask_bits(dstp), cpumask_bits(src1p),
 399                                          cpumask_bits(src2p), nr_cpumask_bits);
 400}
 401
 402/**
 403 * cpumask_complement - *dstp = ~*srcp
 404 * @dstp: the cpumask result
 405 * @srcp: the input to invert
 406 */
 407static inline void cpumask_complement(struct cpumask *dstp,
 408                                      const struct cpumask *srcp)
 409{
 410        bitmap_complement(cpumask_bits(dstp), cpumask_bits(srcp),
 411                                              nr_cpumask_bits);
 412}
 413
 414/**
 415 * cpumask_equal - *src1p == *src2p
 416 * @src1p: the first input
 417 * @src2p: the second input
 418 */
 419static inline bool cpumask_equal(const struct cpumask *src1p,
 420                                const struct cpumask *src2p)
 421{
 422        return bitmap_equal(cpumask_bits(src1p), cpumask_bits(src2p),
 423                                                 nr_cpumask_bits);
 424}
 425
 426/**
 427 * cpumask_intersects - (*src1p & *src2p) != 0
 428 * @src1p: the first input
 429 * @src2p: the second input
 430 */
 431static inline bool cpumask_intersects(const struct cpumask *src1p,
 432                                     const struct cpumask *src2p)
 433{
 434        return bitmap_intersects(cpumask_bits(src1p), cpumask_bits(src2p),
 435                                                      nr_cpumask_bits);
 436}
 437
 438/**
 439 * cpumask_subset - (*src1p & ~*src2p) == 0
 440 * @src1p: the first input
 441 * @src2p: the second input
 442 *
 443 * Returns 1 if *@src1p is a subset of *@src2p, else returns 0
 444 */
 445static inline int cpumask_subset(const struct cpumask *src1p,
 446                                 const struct cpumask *src2p)
 447{
 448        return bitmap_subset(cpumask_bits(src1p), cpumask_bits(src2p),
 449                                                  nr_cpumask_bits);
 450}
 451
 452/**
 453 * cpumask_empty - *srcp == 0
 454 * @srcp: the cpumask to that all cpus < nr_cpu_ids are clear.
 455 */
 456static inline bool cpumask_empty(const struct cpumask *srcp)
 457{
 458        return bitmap_empty(cpumask_bits(srcp), nr_cpumask_bits);
 459}
 460
 461/**
 462 * cpumask_full - *srcp == 0xFFFFFFFF...
 463 * @srcp: the cpumask to that all cpus < nr_cpu_ids are set.
 464 */
 465static inline bool cpumask_full(const struct cpumask *srcp)
 466{
 467        return bitmap_full(cpumask_bits(srcp), nr_cpumask_bits);
 468}
 469
 470/**
 471 * cpumask_weight - Count of bits in *srcp
 472 * @srcp: the cpumask to count bits (< nr_cpu_ids) in.
 473 */
 474static inline unsigned int cpumask_weight(const struct cpumask *srcp)
 475{
 476        return bitmap_weight(cpumask_bits(srcp), nr_cpumask_bits);
 477}
 478
 479/**
 480 * cpumask_shift_right - *dstp = *srcp >> n
 481 * @dstp: the cpumask result
 482 * @srcp: the input to shift
 483 * @n: the number of bits to shift by
 484 */
 485static inline void cpumask_shift_right(struct cpumask *dstp,
 486                                       const struct cpumask *srcp, int n)
 487{
 488        bitmap_shift_right(cpumask_bits(dstp), cpumask_bits(srcp), n,
 489                                               nr_cpumask_bits);
 490}
 491
 492/**
 493 * cpumask_shift_left - *dstp = *srcp << n
 494 * @dstp: the cpumask result
 495 * @srcp: the input to shift
 496 * @n: the number of bits to shift by
 497 */
 498static inline void cpumask_shift_left(struct cpumask *dstp,
 499                                      const struct cpumask *srcp, int n)
 500{
 501        bitmap_shift_left(cpumask_bits(dstp), cpumask_bits(srcp), n,
 502                                              nr_cpumask_bits);
 503}
 504
 505/**
 506 * cpumask_copy - *dstp = *srcp
 507 * @dstp: the result
 508 * @srcp: the input cpumask
 509 */
 510static inline void cpumask_copy(struct cpumask *dstp,
 511                                const struct cpumask *srcp)
 512{
 513        bitmap_copy(cpumask_bits(dstp), cpumask_bits(srcp), nr_cpumask_bits);
 514}
 515
 516/**
 517 * cpumask_any - pick a "random" cpu from *srcp
 518 * @srcp: the input cpumask
 519 *
 520 * Returns >= nr_cpu_ids if no cpus set.
 521 */
 522#define cpumask_any(srcp) cpumask_first(srcp)
 523
 524/**
 525 * cpumask_first_and - return the first cpu from *srcp1 & *srcp2
 526 * @src1p: the first input
 527 * @src2p: the second input
 528 *
 529 * Returns >= nr_cpu_ids if no cpus set in both.  See also cpumask_next_and().
 530 */
 531#define cpumask_first_and(src1p, src2p) cpumask_next_and(-1, (src1p), (src2p))
 532
 533/**
 534 * cpumask_any_and - pick a "random" cpu from *mask1 & *mask2
 535 * @mask1: the first input cpumask
 536 * @mask2: the second input cpumask
 537 *
 538 * Returns >= nr_cpu_ids if no cpus set.
 539 */
 540#define cpumask_any_and(mask1, mask2) cpumask_first_and((mask1), (mask2))
 541
 542/**
 543 * cpumask_of - the cpumask containing just a given cpu
 544 * @cpu: the cpu (<= nr_cpu_ids)
 545 */
 546#define cpumask_of(cpu) (get_cpu_mask(cpu))
 547
 548/**
 549 * cpumask_parse_user - extract a cpumask from a user string
 550 * @buf: the buffer to extract from
 551 * @len: the length of the buffer
 552 * @dstp: the cpumask to set.
 553 *
 554 * Returns -errno, or 0 for success.
 555 */
 556static inline int cpumask_parse_user(const char __user *buf, int len,
 557                                     struct cpumask *dstp)
 558{
 559        return bitmap_parse_user(buf, len, cpumask_bits(dstp), nr_cpu_ids);
 560}
 561
 562/**
 563 * cpumask_parselist_user - extract a cpumask from a user string
 564 * @buf: the buffer to extract from
 565 * @len: the length of the buffer
 566 * @dstp: the cpumask to set.
 567 *
 568 * Returns -errno, or 0 for success.
 569 */
 570static inline int cpumask_parselist_user(const char __user *buf, int len,
 571                                     struct cpumask *dstp)
 572{
 573        return bitmap_parselist_user(buf, len, cpumask_bits(dstp),
 574                                     nr_cpu_ids);
 575}
 576
 577/**
 578 * cpumask_parse - extract a cpumask from from a string
 579 * @buf: the buffer to extract from
 580 * @dstp: the cpumask to set.
 581 *
 582 * Returns -errno, or 0 for success.
 583 */
 584static inline int cpumask_parse(const char *buf, struct cpumask *dstp)
 585{
 586        char *nl = strchr(buf, '\n');
 587        unsigned int len = nl ? (unsigned int)(nl - buf) : strlen(buf);
 588
 589        return bitmap_parse(buf, len, cpumask_bits(dstp), nr_cpu_ids);
 590}
 591
 592/**
 593 * cpulist_parse - extract a cpumask from a user string of ranges
 594 * @buf: the buffer to extract from
 595 * @dstp: the cpumask to set.
 596 *
 597 * Returns -errno, or 0 for success.
 598 */
 599static inline int cpulist_parse(const char *buf, struct cpumask *dstp)
 600{
 601        return bitmap_parselist(buf, cpumask_bits(dstp), nr_cpu_ids);
 602}
 603
 604/**
 605 * cpumask_size - size to allocate for a 'struct cpumask' in bytes
 606 *
 607 * This will eventually be a runtime variable, depending on nr_cpu_ids.
 608 */
 609static inline size_t cpumask_size(void)
 610{
 611        return BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long);
 612}
 613
 614/*
 615 * cpumask_var_t: struct cpumask for stack usage.
 616 *
 617 * Oh, the wicked games we play!  In order to make kernel coding a
 618 * little more difficult, we typedef cpumask_var_t to an array or a
 619 * pointer: doing &mask on an array is a noop, so it still works.
 620 *
 621 * ie.
 622 *      cpumask_var_t tmpmask;
 623 *      if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
 624 *              return -ENOMEM;
 625 *
 626 *        ... use 'tmpmask' like a normal struct cpumask * ...
 627 *
 628 *      free_cpumask_var(tmpmask);
 629 *
 630 *
 631 * However, one notable exception is there. alloc_cpumask_var() allocates
 632 * only nr_cpumask_bits bits (in the other hand, real cpumask_t always has
 633 * NR_CPUS bits). Therefore you don't have to dereference cpumask_var_t.
 634 *
 635 *      cpumask_var_t tmpmask;
 636 *      if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
 637 *              return -ENOMEM;
 638 *
 639 *      var = *tmpmask;
 640 *
 641 * This code makes NR_CPUS length memcopy and brings to a memory corruption.
 642 * cpumask_copy() provide safe copy functionality.
 643 *
 644 * Note that there is another evil here: If you define a cpumask_var_t
 645 * as a percpu variable then the way to obtain the address of the cpumask
 646 * structure differently influences what this_cpu_* operation needs to be
 647 * used. Please use this_cpu_cpumask_var_t in those cases. The direct use
 648 * of this_cpu_ptr() or this_cpu_read() will lead to failures when the
 649 * other type of cpumask_var_t implementation is configured.
 650 */
 651#ifdef CONFIG_CPUMASK_OFFSTACK
 652typedef struct cpumask *cpumask_var_t;
 653
 654#define this_cpu_cpumask_var_ptr(x) this_cpu_read(x)
 655
 656bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node);
 657bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags);
 658bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node);
 659bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags);
 660void alloc_bootmem_cpumask_var(cpumask_var_t *mask);
 661void free_cpumask_var(cpumask_var_t mask);
 662void free_bootmem_cpumask_var(cpumask_var_t mask);
 663
 664#else
 665typedef struct cpumask cpumask_var_t[1];
 666
 667#define this_cpu_cpumask_var_ptr(x) this_cpu_ptr(x)
 668
 669static inline bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 670{
 671        return true;
 672}
 673
 674static inline bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags,
 675                                          int node)
 676{
 677        return true;
 678}
 679
 680static inline bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 681{
 682        cpumask_clear(*mask);
 683        return true;
 684}
 685
 686static inline bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags,
 687                                          int node)
 688{
 689        cpumask_clear(*mask);
 690        return true;
 691}
 692
 693static inline void alloc_bootmem_cpumask_var(cpumask_var_t *mask)
 694{
 695}
 696
 697static inline void free_cpumask_var(cpumask_var_t mask)
 698{
 699}
 700
 701static inline void free_bootmem_cpumask_var(cpumask_var_t mask)
 702{
 703}
 704#endif /* CONFIG_CPUMASK_OFFSTACK */
 705
 706/* It's common to want to use cpu_all_mask in struct member initializers,
 707 * so it has to refer to an address rather than a pointer. */
 708extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
 709#define cpu_all_mask to_cpumask(cpu_all_bits)
 710
 711/* First bits of cpu_bit_bitmap are in fact unset. */
 712#define cpu_none_mask to_cpumask(cpu_bit_bitmap[0])
 713
 714#define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask)
 715#define for_each_online_cpu(cpu)   for_each_cpu((cpu), cpu_online_mask)
 716#define for_each_present_cpu(cpu)  for_each_cpu((cpu), cpu_present_mask)
 717
 718/* Wrappers for arch boot code to manipulate normally-constant masks */
 719void set_cpu_possible(unsigned int cpu, bool possible);
 720void set_cpu_present(unsigned int cpu, bool present);
 721void set_cpu_online(unsigned int cpu, bool online);
 722void set_cpu_active(unsigned int cpu, bool active);
 723void init_cpu_present(const struct cpumask *src);
 724void init_cpu_possible(const struct cpumask *src);
 725void init_cpu_online(const struct cpumask *src);
 726
 727/**
 728 * to_cpumask - convert an NR_CPUS bitmap to a struct cpumask *
 729 * @bitmap: the bitmap
 730 *
 731 * There are a few places where cpumask_var_t isn't appropriate and
 732 * static cpumasks must be used (eg. very early boot), yet we don't
 733 * expose the definition of 'struct cpumask'.
 734 *
 735 * This does the conversion, and can be used as a constant initializer.
 736 */
 737#define to_cpumask(bitmap)                                              \
 738        ((struct cpumask *)(1 ? (bitmap)                                \
 739                            : (void *)sizeof(__check_is_bitmap(bitmap))))
 740
 741static inline int __check_is_bitmap(const unsigned long *bitmap)
 742{
 743        return 1;
 744}
 745
 746/*
 747 * Special-case data structure for "single bit set only" constant CPU masks.
 748 *
 749 * We pre-generate all the 64 (or 32) possible bit positions, with enough
 750 * padding to the left and the right, and return the constant pointer
 751 * appropriately offset.
 752 */
 753extern const unsigned long
 754        cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)];
 755
 756static inline const struct cpumask *get_cpu_mask(unsigned int cpu)
 757{
 758        const unsigned long *p = cpu_bit_bitmap[1 + cpu % BITS_PER_LONG];
 759        p -= cpu / BITS_PER_LONG;
 760        return to_cpumask(p);
 761}
 762
 763#define cpu_is_offline(cpu)     unlikely(!cpu_online(cpu))
 764
 765#if NR_CPUS <= BITS_PER_LONG
 766#define CPU_BITS_ALL                                            \
 767{                                                               \
 768        [BITS_TO_LONGS(NR_CPUS)-1] = BITMAP_LAST_WORD_MASK(NR_CPUS)     \
 769}
 770
 771#else /* NR_CPUS > BITS_PER_LONG */
 772
 773#define CPU_BITS_ALL                                            \
 774{                                                               \
 775        [0 ... BITS_TO_LONGS(NR_CPUS)-2] = ~0UL,                \
 776        [BITS_TO_LONGS(NR_CPUS)-1] = BITMAP_LAST_WORD_MASK(NR_CPUS)     \
 777}
 778#endif /* NR_CPUS > BITS_PER_LONG */
 779
 780/**
 781 * cpumap_print_to_pagebuf  - copies the cpumask into the buffer either
 782 *      as comma-separated list of cpus or hex values of cpumask
 783 * @list: indicates whether the cpumap must be list
 784 * @mask: the cpumask to copy
 785 * @buf: the buffer to copy into
 786 *
 787 * Returns the length of the (null-terminated) @buf string, zero if
 788 * nothing is copied.
 789 */
 790static inline ssize_t
 791cpumap_print_to_pagebuf(bool list, char *buf, const struct cpumask *mask)
 792{
 793        return bitmap_print_to_pagebuf(list, buf, cpumask_bits(mask),
 794                                      nr_cpu_ids);
 795}
 796
 797#if NR_CPUS <= BITS_PER_LONG
 798#define CPU_MASK_ALL                                                    \
 799(cpumask_t) { {                                                         \
 800        [BITS_TO_LONGS(NR_CPUS)-1] = BITMAP_LAST_WORD_MASK(NR_CPUS)     \
 801} }
 802#else
 803#define CPU_MASK_ALL                                                    \
 804(cpumask_t) { {                                                         \
 805        [0 ... BITS_TO_LONGS(NR_CPUS)-2] = ~0UL,                        \
 806        [BITS_TO_LONGS(NR_CPUS)-1] = BITMAP_LAST_WORD_MASK(NR_CPUS)     \
 807} }
 808#endif /* NR_CPUS > BITS_PER_LONG */
 809
 810#define CPU_MASK_NONE                                                   \
 811(cpumask_t) { {                                                         \
 812        [0 ... BITS_TO_LONGS(NR_CPUS)-1] =  0UL                         \
 813} }
 814
 815#define CPU_MASK_CPU0                                                   \
 816(cpumask_t) { {                                                         \
 817        [0] =  1UL                                                      \
 818} }
 819
 820#endif /* __LINUX_CPUMASK_H */
 821